mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-26 05:05:13 +07:00
ec2f8a306a
939 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Omar Sandoval
|
93781325da |
lockdep: fix fs_reclaim annotation
While revisiting my Btrfs swapfile series [1], I introduced a situation
in which reclaim would lock i_rwsem, and even though the swapon() path
clearly made GFP_KERNEL allocations while holding i_rwsem, I got no
complaints from lockdep. It turns out that the rework of the fs_reclaim
annotation was broken: if the current task has PF_MEMALLOC set, we don't
acquire the dummy fs_reclaim lock, but when reclaiming we always check
this _after_ we've just set the PF_MEMALLOC flag. In most cases, we can
fix this by moving the fs_reclaim_{acquire,release}() outside of the
memalloc_noreclaim_{save,restore}(), althought kswapd is slightly
different. After applying this, I got the expected lockdep splats.
1: https://lwn.net/Articles/625412/
Link: http://lkml.kernel.org/r/9f8aa70652a98e98d7c4de0fc96a4addcee13efe.1523778026.git.osandov@fb.com
Fixes:
|
||
|
Hugh Dickins
|
145e1a71e0 |
mm: fix the NULL mapping case in __isolate_lru_page()
George Boole would have noticed a slight error in 4.16 commit |
||
|
Tetsuo Handa
|
8e04944f0e |
mm,vmscan: Allow preallocating memory for register_shrinker().
syzbot is catching so many bugs triggered by commit
|
||
|
Matthew Wilcox
|
b93b016313 |
page cache: use xa_lock
Remove the address_space ->tree_lock and use the xa_lock newly added to the radix_tree_root. Rename the address_space ->page_tree to ->i_pages, since we don't really care that it's a tree. [willy@infradead.org: fix nds32, fs/dax.c] Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Jeff Layton <jlayton@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
e27be240df |
mm: memcg: make sure memory.events is uptodate when waking pollers
Commit |
||
|
Steven Rostedt
|
d51d1e6450 |
mm, vmscan, tracing: use pointer to reclaim_stat struct in trace event
The trace event trace_mm_vmscan_lru_shrink_inactive() currently has 12 parameters! Seven of them are from the reclaim_stat structure. This structure is currently local to mm/vmscan.c. By moving it to the global vmstat.h header, we can also reference it from the vmscan tracepoints. In moving it, it brings down the overhead of passing so many arguments to the trace event. In the future, we may limit the number of arguments that a trace event may pass (ideally just 6, but more realistically it may be 8). Before this patch, the code to call the trace event is this: 0f 83 aa fe ff ff jae ffffffff811e6261 <shrink_inactive_list+0x1e1> 48 8b 45 a0 mov -0x60(%rbp),%rax 45 8b 64 24 20 mov 0x20(%r12),%r12d 44 8b 6d d4 mov -0x2c(%rbp),%r13d 8b 4d d0 mov -0x30(%rbp),%ecx 44 8b 75 cc mov -0x34(%rbp),%r14d 44 8b 7d c8 mov -0x38(%rbp),%r15d 48 89 45 90 mov %rax,-0x70(%rbp) 8b 83 b8 fe ff ff mov -0x148(%rbx),%eax 8b 55 c0 mov -0x40(%rbp),%edx 8b 7d c4 mov -0x3c(%rbp),%edi 8b 75 b8 mov -0x48(%rbp),%esi 89 45 80 mov %eax,-0x80(%rbp) 65 ff 05 e4 f7 e2 7e incl %gs:0x7ee2f7e4(%rip) # 15bd0 <__preempt_count> 48 8b 05 75 5b 13 01 mov 0x1135b75(%rip),%rax # ffffffff8231bf68 <__tracepoint_mm_vmscan_lru_shrink_inactive+0x28> 48 85 c0 test %rax,%rax 74 72 je ffffffff811e646a <shrink_inactive_list+0x3ea> 48 89 c3 mov %rax,%rbx 4c 8b 10 mov (%rax),%r10 89 f8 mov %edi,%eax 48 89 85 68 ff ff ff mov %rax,-0x98(%rbp) 89 f0 mov %esi,%eax 48 89 85 60 ff ff ff mov %rax,-0xa0(%rbp) 89 c8 mov %ecx,%eax 48 89 85 78 ff ff ff mov %rax,-0x88(%rbp) 89 d0 mov %edx,%eax 48 89 85 70 ff ff ff mov %rax,-0x90(%rbp) 8b 45 8c mov -0x74(%rbp),%eax 48 8b 7b 08 mov 0x8(%rbx),%rdi 48 83 c3 18 add $0x18,%rbx 50 push %rax 41 54 push %r12 41 55 push %r13 ff b5 78 ff ff ff pushq -0x88(%rbp) 41 56 push %r14 41 57 push %r15 ff b5 70 ff ff ff pushq -0x90(%rbp) 4c 8b 8d 68 ff ff ff mov -0x98(%rbp),%r9 4c 8b 85 60 ff ff ff mov -0xa0(%rbp),%r8 48 8b 4d 98 mov -0x68(%rbp),%rcx 48 8b 55 90 mov -0x70(%rbp),%rdx 8b 75 80 mov -0x80(%rbp),%esi 41 ff d2 callq *%r10 After the patch: 0f 83 a8 fe ff ff jae ffffffff811e626d <shrink_inactive_list+0x1cd> 8b 9b b8 fe ff ff mov -0x148(%rbx),%ebx 45 8b 64 24 20 mov 0x20(%r12),%r12d 4c 8b 6d a0 mov -0x60(%rbp),%r13 65 ff 05 f5 f7 e2 7e incl %gs:0x7ee2f7f5(%rip) # 15bd0 <__preempt_count> 4c 8b 35 86 5b 13 01 mov 0x1135b86(%rip),%r14 # ffffffff8231bf68 <__tracepoint_mm_vmscan_lru_shrink_inactive+0x28> 4d 85 f6 test %r14,%r14 74 2a je ffffffff811e6411 <shrink_inactive_list+0x371> 49 8b 06 mov (%r14),%rax 8b 4d 8c mov -0x74(%rbp),%ecx 49 8b 7e 08 mov 0x8(%r14),%rdi 49 83 c6 18 add $0x18,%r14 4c 89 ea mov %r13,%rdx 45 89 e1 mov %r12d,%r9d 4c 8d 45 b8 lea -0x48(%rbp),%r8 89 de mov %ebx,%esi 51 push %rcx 48 8b 4d 98 mov -0x68(%rbp),%rcx ff d0 callq *%rax Link: http://lkml.kernel.org/r/2559d7cb-ec60-1200-2362-04fa34fd02bb@fb.com Link: http://lkml.kernel.org/r/20180322121003.4177af15@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reported-by: Alexei Starovoitov <ast@fb.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexei Starovoitov <ast@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Ryabinin
|
e3c1ac586c |
mm/vmscan: don't mess with pgdat->flags in memcg reclaim
memcg reclaim may alter pgdat->flags based on the state of LRU lists in
cgroup and its children. PGDAT_WRITEBACK may force kswapd to sleep
congested_wait(), PGDAT_DIRTY may force kswapd to writeback filesystem
pages. But the worst here is PGDAT_CONGESTED, since it may force all
direct reclaims to stall in wait_iff_congested(). Note that only kswapd
have powers to clear any of these bits. This might just never happen if
cgroup limits configured that way. So all direct reclaims will stall as
long as we have some congested bdi in the system.
Leave all pgdat->flags manipulations to kswapd. kswapd scans the whole
pgdat, only kswapd can clear pgdat->flags once node is balanced, thus
it's reasonable to leave all decisions about node state to kswapd.
Why only kswapd? Why not allow to global direct reclaim change these
flags? It is because currently only kswapd can clear these flags. I'm
less worried about the case when PGDAT_CONGESTED falsely not set, and
more worried about the case when it falsely set. If direct reclaimer
sets PGDAT_CONGESTED, do we have guarantee that after the congestion
problem is sorted out, kswapd will be woken up and clear the flag? It
seems like there is no such guarantee. E.g. direct reclaimers may
eventually balance pgdat and kswapd simply won't wake up (see
wakeup_kswapd()).
Moving pgdat->flags manipulation to kswapd, means that cgroup2 recalim
now loses its congestion throttling mechanism. Add per-cgroup
congestion state and throttle cgroup2 reclaimers if memcg is in
congestion state.
Currently there is no need in per-cgroup PGDAT_WRITEBACK and PGDAT_DIRTY
bits since they alter only kswapd behavior.
The problem could be easily demonstrated by creating heavy congestion in
one cgroup:
echo "+memory" > /sys/fs/cgroup/cgroup.subtree_control
mkdir -p /sys/fs/cgroup/congester
echo 512M > /sys/fs/cgroup/congester/memory.max
echo $$ > /sys/fs/cgroup/congester/cgroup.procs
/* generate a lot of diry data on slow HDD */
while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done &
....
while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done &
and some job in another cgroup:
mkdir /sys/fs/cgroup/victim
echo 128M > /sys/fs/cgroup/victim/memory.max
# time cat /dev/sda > /dev/null
real 10m15.054s
user 0m0.487s
sys 1m8.505s
According to the tracepoint in wait_iff_congested(), the 'cat' spent 50%
of the time sleeping there.
With the patch, cat don't waste time anymore:
# time cat /dev/sda > /dev/null
real 5m32.911s
user 0m0.411s
sys 0m56.664s
[aryabinin@virtuozzo.com: congestion state should be per-node]
Link: http://lkml.kernel.org/r/20180406135215.10057-1-aryabinin@virtuozzo.com
[ayabinin@virtuozzo.com: make congestion state per-cgroup-per-node instead of just per-cgroup[
Link: http://lkml.kernel.org/r/20180406180254.8970-2-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/20180323152029.11084-5-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Andrey Ryabinin
|
d108c7721f |
mm/vmscan: don't change pgdat state on base of a single LRU list state
We have separate LRU list for each memory cgroup. Memory reclaim iterates over cgroups and calls shrink_inactive_list() every inactive LRU list. Based on the state of a single LRU shrink_inactive_list() may flag the whole node as dirty,congested or under writeback. This is obviously wrong and hurtful. It's especially hurtful when we have possibly small congested cgroup in system. Than *all* direct reclaims waste time by sleeping in wait_iff_congested(). And the more memcgs in the system we have the longer memory allocation stall is, because wait_iff_congested() called on each lru-list scan. Sum reclaim stats across all visited LRUs on node and flag node as dirty, congested or under writeback based on that sum. Also call congestion_wait(), wait_iff_congested() once per pgdat scan, instead of once per lru-list scan. This only fixes the problem for global reclaim case. Per-cgroup reclaim may alter global pgdat flags too, which is wrong. But that is separate issue and will be addressed in the next patch. This change will not have any effect on a systems with all workload concentrated in a single cgroup. [aryabinin@virtuozzo.com: check nr_writeback against all nr_taken, not just file] Link: http://lkml.kernel.org/r/20180406180254.8970-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20180323152029.11084-4-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Ryabinin
|
c4fd4fa580 |
mm/vmscan: remove redundant current_may_throttle() check
Only kswapd can have non-zero nr_immediate, and current_may_throttle() is always true for kswapd (PF_LESS_THROTTLE bit is never set) thus it's enough to check stat.nr_immediate only. Link: http://lkml.kernel.org/r/20180315164553.17856-4-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Ryabinin
|
894befec4d |
mm/vmscan: update stale comments
Update some comments that became stale since transiton from per-zone to per-node reclaim. Link: http://lkml.kernel.org/r/20180315164553.17856-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
David Rientjes
|
5ecd9d403a |
mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory
Kswapd will not wakeup if per-zone watermarks are not failing or if too many previous attempts at background reclaim have failed. This can be true if there is a lot of free memory available. For high- order allocations, kswapd is responsible for waking up kcompactd for background compaction. If the zone is not below its watermarks or reclaim has recently failed (lots of free memory, nothing left to reclaim), kcompactd does not get woken up. When __GFP_DIRECT_RECLAIM is not allowed, allow kcompactd to still be woken up even if kswapd will not reclaim. This allows high-order allocations, such as thp, to still trigger background compaction even when the zone has an abundance of free memory. Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803111659420.209721@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Tetsuo Handa
|
e830c63a62 |
mm,vmscan: don't pretend forward progress upon shrinker_rwsem contention
Since we no longer use return value of shrink_slab() for normal reclaim, the comment is no longer true. If some do_shrink_slab() call takes unexpectedly long (root cause of stall is currently unknown) when register_shrinker()/unregister_shrinker() is pending, trying to drop caches via /proc/sys/vm/drop_caches could become infinite cond_resched() loop if many mem_cgroup are defined. For safety, let's not pretend forward progress. Link: http://lkml.kernel.org/r/201802202229.GGF26507.LVFtMSOOHFJOQF@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Huang Ying
|
e92bb4dd96 |
mm: fix races between address_space dereference and free in page_evicatable
When page_mapping() is called and the mapping is dereferenced in
page_evicatable() through shrink_active_list(), it is possible for the
inode to be truncated and the embedded address space to be freed at the
same time. This may lead to the following race.
CPU1 CPU2
truncate(inode) shrink_active_list()
... page_evictable(page)
truncate_inode_page(mapping, page);
delete_from_page_cache(page)
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(page, NULL)
page_cache_tree_delete(..)
... mapping = page_mapping(page);
page->mapping = NULL;
...
spin_unlock_irqrestore(&mapping->tree_lock, flags);
page_cache_free_page(mapping, page)
put_page(page)
if (put_page_testzero(page)) -> false
- inode now has no pages and can be freed including embedded address_space
mapping_unevictable(mapping)
test_bit(AS_UNEVICTABLE, &mapping->flags);
- we've dereferenced mapping which is potentially already free.
Similar race exists between swap cache freeing and page_evicatable()
too.
The address_space in inode and swap cache will be freed after a RCU
grace period. So the races are fixed via enclosing the page_mapping()
and address_space usage in rcu_read_lock/unlock(). Some comments are
added in code to make it clear what is protected by the RCU read lock.
Link: http://lkml.kernel.org/r/20180212081227.1940-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Andrey Ryabinin
|
1c610d5f93 |
mm/vmscan: wake up flushers for legacy cgroups too
Commit |
||
|
Shakeel Butt
|
9c4e6b1a70 |
mm, mlock, vmscan: no more skipping pagevecs
When a thread mlocks an address space backed either by file pages which are currently not present in memory or swapped out anon pages (not in swapcache), a new page is allocated and added to the local pagevec (lru_add_pvec), I/O is triggered and the thread then sleeps on the page. On I/O completion, the thread can wake on a different CPU, the mlock syscall will then sets the PageMlocked() bit of the page but will not be able to put that page in unevictable LRU as the page is on the pagevec of a different CPU. Even on drain, that page will go to evictable LRU because the PageMlocked() bit is not checked on pagevec drain. The page will eventually go to right LRU on reclaim but the LRU stats will remain skewed for a long time. This patch puts all the pages, even unevictable, to the pagevecs and on the drain, the pages will be added on their LRUs correctly by checking their evictability. This resolves the mlocked pages on pagevec of other CPUs issue because when those pagevecs will be drained, the mlocked file pages will go to unevictable LRU. Also this makes the race with munlock easier to resolve because the pagevec drains happen in LRU lock. However there is still one place which makes a page evictable and does PageLRU check on that page without LRU lock and needs special attention. TestClearPageMlocked() and isolate_lru_page() in clear_page_mlock(). #0: __pagevec_lru_add_fn #1: clear_page_mlock SetPageLRU() if (!TestClearPageMlocked()) return smp_mb() // <--required // inside does PageLRU if (!PageMlocked()) if (isolate_lru_page()) move to evictable LRU putback_lru_page() else move to unevictable LRU In '#1', TestClearPageMlocked() provides full memory barrier semantics and thus the PageLRU check (inside isolate_lru_page) can not be reordered before it. In '#0', without explicit memory barrier, the PageMlocked() check can be reordered before SetPageLRU(). If that happens, '#0' can put a page in unevictable LRU and '#1' might have just cleared the Mlocked bit of that page but fails to isolate as PageLRU fails as '#0' still hasn't set PageLRU bit of that page. That page will be stranded on the unevictable LRU. There is one (good) side effect though. Without this patch, the pages allocated for System V shared memory segment are added to evictable LRUs even after shmctl(SHM_LOCK) on that segment. This patch will correctly put such pages to unevictable LRU. Link: http://lkml.kernel.org/r/20171121211241.18877-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Jan Kara <jack@suse.cz> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mike Rapoport
|
a5d09bed7f |
mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors
Link: http://lkml.kernel.org/r/1516700871-22279-4-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
69d763fc6d |
mm: pin address_space before dereferencing it while isolating an LRU page
Minchan Kim asked the following question -- what locks protects
address_space destroying when race happens between inode trauncation and
__isolate_lru_page? Jan Kara clarified by describing the race as follows
CPU1 CPU2
truncate(inode) __isolate_lru_page()
...
truncate_inode_page(mapping, page);
delete_from_page_cache(page)
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(page, NULL)
page_cache_tree_delete(..)
... mapping = page_mapping(page);
page->mapping = NULL;
...
spin_unlock_irqrestore(&mapping->tree_lock, flags);
page_cache_free_page(mapping, page)
put_page(page)
if (put_page_testzero(page)) -> false
- inode now has no pages and can be freed including embedded address_space
if (mapping && !mapping->a_ops->migratepage)
- we've dereferenced mapping which is potentially already free.
The race is theoretically possible but unlikely. Before the
delete_from_page_cache, truncate_cleanup_page is called so the page is
likely to be !PageDirty or PageWriteback which gets skipped by the only
caller that checks the mappping in __isolate_lru_page. Even if the race
occurs, a substantial amount of work has to happen during a tiny window
with no preemption but it could potentially be done using a virtual
machine to artifically slow one CPU or halt it during the critical
window.
This patch should eliminate the race with truncation by try-locking the
page before derefencing mapping and aborting if the lock was not
acquired. There was a suggestion from Huang Ying to use RCU as a
side-effect to prevent mapping being freed. However, I do not like the
solution as it's an unconventional means of preserving a mapping and
it's not a context where rcu_read_lock is obviously protecting rcu data.
Link: http://lkml.kernel.org/r/20180104102512.2qos3h5vqzeisrek@techsingularity.net
Fixes:
|
||
|
Jan Kara
|
a4ef876841 |
mm: remove unused pgdat_reclaimable_pages()
Remove unused function pgdat_reclaimable_pages() and node_page_state_snapshot() which becomes unused as well. Link: http://lkml.kernel.org/r/20171122094416.26019-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
e496612c51 |
mm: do not stall register_shrinker()
Shakeel Butt reported he has observed in production systems that the job loader gets stuck for 10s of seconds while doing a mount operation. It turns out that it was stuck in register_shrinker() because some unrelated job was under memory pressure and was spending time in shrink_slab(). Machines have a lot of shrinkers registered and jobs under memory pressure have to traverse all of those memcg-aware shrinkers and affect unrelated jobs which want to register their own shrinkers. To solve the issue, this patch simply bails out slab shrinking if it is found that someone wants to register a shrinker in parallel. A downside is it could cause unfair shrinking between shrinkers. However, it should be rare and we can add compilcated logic if we find it's not enough. [akpm@linux-foundation.org: tweak code comment] Link: http://lkml.kernel.org/r/20171115005602.GB23810@bbox Link: http://lkml.kernel.org/r/1511481899-20335-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Shakeel Butt <shakeelb@google.com> Reported-by: Shakeel Butt <shakeelb@google.com> Tested-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Josef Bacik
|
9092c71bb7 |
mm: use sc->priority for slab shrink targets
Previously we were using the ratio of the number of lru pages scanned to the number of eligible lru pages to determine the number of slab objects to scan. The problem with this is that these two things have nothing to do with each other, so in slab heavy work loads where there is little to no page cache we can end up with the pages scanned being a very low number. This means that we reclaim next to no slab pages and waste a lot of time reclaiming small amounts of space. Consider the following scenario, where we have the following values and the rest of the memory usage is in slab Active: 58840 kB Inactive: 46860 kB Every time we do a get_scan_count() we do this scan = size >> sc->priority where sc->priority starts at DEF_PRIORITY, which is 12. The first loop through reclaim would result in a scan target of 2 pages to 11715 total inactive pages, and 3 pages to 14710 total active pages. This is a really really small target for a system that is entirely slab pages. And this is super optimistic, this assumes we even get to scan these pages. We don't increment sc->nr_scanned unless we 1) isolate the page, which assumes it's not in use, and 2) can lock the page. Under pressure these numbers could probably go down, I'm sure there's some random pages from daemons that aren't actually in use, so the targets get even smaller. Instead use sc->priority in the same way we use it to determine scan amounts for the lru's. This generally equates to pages. Consider the following slab_pages = (nr_objects * object_size) / PAGE_SIZE What we would like to do is scan = slab_pages >> sc->priority but we don't know the number of slab pages each shrinker controls, only the objects. However say that theoretically we knew how many pages a shrinker controlled, we'd still have to convert this to objects, which would look like the following scan = shrinker_pages >> sc->priority scan_objects = (PAGE_SIZE / object_size) * scan or written another way scan_objects = (shrinker_pages >> sc->priority) * (PAGE_SIZE / object_size) which can thus be written scan_objects = ((shrinker_pages * PAGE_SIZE) / object_size) >> sc->priority which is just scan_objects = nr_objects >> sc->priority We don't need to know exactly how many pages each shrinker represents, it's objects are all the information we need. Making this change allows us to place an appropriate amount of pressure on the shrinker pools for their relative size. Link: http://lkml.kernel.org/r/1510780549-6812-1-git-send-email-josef@toxicpanda.com Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Dave Chinner <david@fromorbit.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Tetsuo Handa
|
bb422a738f |
mm,vmscan: Make unregister_shrinker() no-op if register_shrinker() failed.
Syzbot caught an oops at unregister_shrinker() because combination of
commit
|
||
|
Mel Gorman
|
2d4894b5d2 |
mm: remove cold parameter from free_hot_cold_page*
Most callers users of free_hot_cold_page claim the pages being released are cache hot. The exception is the page reclaim paths where it is likely that enough pages will be freed in the near future that the per-cpu lists are going to be recycled and the cache hotness information is lost. As no one really cares about the hotness of pages being released to the allocator, just ditch the parameter. The APIs are renamed to indicate that it's no longer about hot/cold pages. It should also be less confusing as there are subtle differences between them. __free_pages drops a reference and frees a page when the refcount reaches zero. free_hot_cold_page handled pages whose refcount was already zero which is non-obvious from the name. free_unref_page should be more obvious. No performance impact is expected as the overhead is marginal. The parameter is removed simply because it is a bit stupid to have a useless parameter copied everywhere. [mgorman@techsingularity.net: add pages to head, not tail] Link: http://lkml.kernel.org/r/20171019154321.qtpzaeftoyyw4iey@techsingularity.net Link: http://lkml.kernel.org/r/20171018075952.10627-8-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Ryabinin
|
3a50d14d0d |
mm: remove unused pgdat->inactive_ratio
Since commit
|
||
|
Linus Torvalds
|
e2c5923c34 |
Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block
Pull core block layer updates from Jens Axboe:
"This is the main pull request for block storage for 4.15-rc1.
Nothing out of the ordinary in here, and no API changes or anything
like that. Just various new features for drivers, core changes, etc.
In particular, this pull request contains:
- A patch series from Bart, closing the whole on blk/scsi-mq queue
quescing.
- A series from Christoph, building towards hidden gendisks (for
multipath) and ability to move bio chains around.
- NVMe
- Support for native multipath for NVMe (Christoph).
- Userspace notifications for AENs (Keith).
- Command side-effects support (Keith).
- SGL support (Chaitanya Kulkarni)
- FC fixes and improvements (James Smart)
- Lots of fixes and tweaks (Various)
- bcache
- New maintainer (Michael Lyle)
- Writeback control improvements (Michael)
- Various fixes (Coly, Elena, Eric, Liang, et al)
- lightnvm updates, mostly centered around the pblk interface
(Javier, Hans, and Rakesh).
- Removal of unused bio/bvec kmap atomic interfaces (me, Christoph)
- Writeback series that fix the much discussed hundreds of millions
of sync-all units. This goes all the way, as discussed previously
(me).
- Fix for missing wakeup on writeback timer adjustments (Yafang
Shao).
- Fix laptop mode on blk-mq (me).
- {mq,name} tupple lookup for IO schedulers, allowing us to have
alias names. This means you can use 'deadline' on both !mq and on
mq (where it's called mq-deadline). (me).
- blktrace race fix, oopsing on sg load (me).
- blk-mq optimizations (me).
- Obscure waitqueue race fix for kyber (Omar).
- NBD fixes (Josef).
- Disable writeback throttling by default on bfq, like we do on cfq
(Luca Miccio).
- Series from Ming that enable us to treat flush requests on blk-mq
like any other request. This is a really nice cleanup.
- Series from Ming that improves merging on blk-mq with schedulers,
getting us closer to flipping the switch on scsi-mq again.
- BFQ updates (Paolo).
- blk-mq atomic flags memory ordering fixes (Peter Z).
- Loop cgroup support (Shaohua).
- Lots of minor fixes from lots of different folks, both for core and
driver code"
* 'for-4.15/block' of git://git.kernel.dk/linux-block: (294 commits)
nvme: fix visibility of "uuid" ns attribute
blk-mq: fixup some comment typos and lengths
ide: ide-atapi: fix compile error with defining macro DEBUG
blk-mq: improve tag waiting setup for non-shared tags
brd: remove unused brd_mutex
blk-mq: only run the hardware queue if IO is pending
block: avoid null pointer dereference on null disk
fs: guard_bio_eod() needs to consider partitions
xtensa/simdisk: fix compile error
nvme: expose subsys attribute to sysfs
nvme: create 'slaves' and 'holders' entries for hidden controllers
block: create 'slaves' and 'holders' entries for hidden gendisks
nvme: also expose the namespace identification sysfs files for mpath nodes
nvme: implement multipath access to nvme subsystems
nvme: track shared namespaces
nvme: introduce a nvme_ns_ids structure
nvme: track subsystems
block, nvme: Introduce blk_mq_req_flags_t
block, scsi: Make SCSI quiesce and resume work reliably
block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
...
|
||
|
Greg Kroah-Hartman
|
b24413180f |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Jens Axboe
|
9ba4b2dfaf |
fs: kill 'nr_pages' argument from wakeup_flusher_threads()
Everybody is passing in 0 now, let's get rid of the argument. Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
||
|
Huang Ying
|
fe490cc0fe |
mm, THP, swap: add THP swapping out fallback counting
When swapping out THP (Transparent Huge Page), instead of swapping out the THP as a whole, sometimes we have to fallback to split the THP into normal pages before swapping, because no free swap clusters are available, or cgroup limit is exceeded, etc. To count the number of the fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when we fallback to split the THP. Link: http://lkml.kernel.org/r/20170724051840.2309-13-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Huang Ying
|
bd4c82c22c |
mm, THP, swap: delay splitting THP after swapped out
In this patch, splitting transparent huge page (THP) during swapping out is delayed from after adding the THP into the swap cache to after swapping out finishes. After the patch, more operations for the anonymous THP reclaiming, such as writing the THP to the swap device, removing the THP from the swap cache could be batched. So that the performance of anonymous THP swapping out could be improved. This is the second step for the THP swap support. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. With the patchset, the swap out throughput improves 42% (from about 5.81GB/s to about 8.25GB/s) in the vm-scalability swap-w-seq test case with 16 processes. At the same time, the IPI (reflect TLB flushing) reduced about 78.9%. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170724051840.2309-12-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
db73ee0d46 |
mm, vmscan: do not loop on too_many_isolated for ever
Tetsuo Handa has reported[1][2][3] that direct reclaimers might get stuck in too_many_isolated loop basically for ever because the last few pages on the LRU lists are isolated by the kswapd which is stuck on fs locks when doing the pageout or slab reclaim. This in turn means that there is nobody to actually trigger the oom killer and the system is basically unusable. too_many_isolated has been introduced by commit |
||
|
Chris Wilson
|
d460acb5bd |
mm: track actual nr_scanned during shrink_slab()
Some shrinkers may only be able to free a bunch of objects at a time, and so free more than the requested nr_to_scan in one pass. Whilst other shrinkers may find themselves even unable to scan as many objects as they counted, and so underreport. Account for the extra freed/scanned objects against the total number of objects we intend to scan, otherwise we may end up penalising the slab far more than intended. Similarly, we want to add the underperforming scan to the deferred pass so that we try harder and harder in future passes. Link: http://lkml.kernel.org/r/20170822135325.9191-1-chris@chris-wilson.co.uk Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Shaohua Li <shli@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Peter Zijlstra
|
d92a8cfcb3 |
locking/lockdep: Rework FS_RECLAIM annotation
A while ago someone, and I cannot find the email just now, asked if we could not implement the RECLAIM_FS inversion stuff with a 'fake' lock like we use for other things like workqueues etc. I think this should be possible which allows reducing the 'irq' states and will reduce the amount of __bfs() lookups we do. Removing the 1 IRQ state results in 4 less __bfs() walks per dependency, improving lockdep performance. And by moving this annotation out of the lockdep code it becomes easier for the mm people to extend. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: iamjoonsoo.kim@lge.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Michal Hocko
|
dcda9b0471 |
mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic
__GFP_REPEAT was designed to allow retry-but-eventually-fail semantic to the page allocator. This has been true but only for allocations requests larger than PAGE_ALLOC_COSTLY_ORDER. It has been always ignored for smaller sizes. This is a bit unfortunate because there is no way to express the same semantic for those requests and they are considered too important to fail so they might end up looping in the page allocator for ever, similarly to GFP_NOFAIL requests. Now that the whole tree has been cleaned up and accidental or misled usage of __GFP_REPEAT flag has been removed for !costly requests we can give the original flag a better name and more importantly a more useful semantic. Let's rename it to __GFP_RETRY_MAYFAIL which tells the user that the allocator would try really hard but there is no promise of a success. This will work independent of the order and overrides the default allocator behavior. Page allocator users have several levels of guarantee vs. cost options (take GFP_KERNEL as an example) - GFP_KERNEL & ~__GFP_RECLAIM - optimistic allocation without _any_ attempt to free memory at all. The most light weight mode which even doesn't kick the background reclaim. Should be used carefully because it might deplete the memory and the next user might hit the more aggressive reclaim - GFP_KERNEL & ~__GFP_DIRECT_RECLAIM (or GFP_NOWAIT)- optimistic allocation without any attempt to free memory from the current context but can wake kswapd to reclaim memory if the zone is below the low watermark. Can be used from either atomic contexts or when the request is a performance optimization and there is another fallback for a slow path. - (GFP_KERNEL|__GFP_HIGH) & ~__GFP_DIRECT_RECLAIM (aka GFP_ATOMIC) - non sleeping allocation with an expensive fallback so it can access some portion of memory reserves. Usually used from interrupt/bh context with an expensive slow path fallback. - GFP_KERNEL - both background and direct reclaim are allowed and the _default_ page allocator behavior is used. That means that !costly allocation requests are basically nofail but there is no guarantee of that behavior so failures have to be checked properly by callers (e.g. OOM killer victim is allowed to fail currently). - GFP_KERNEL | __GFP_NORETRY - overrides the default allocator behavior and all allocation requests fail early rather than cause disruptive reclaim (one round of reclaim in this implementation). The OOM killer is not invoked. - GFP_KERNEL | __GFP_RETRY_MAYFAIL - overrides the default allocator behavior and all allocation requests try really hard. The request will fail if the reclaim cannot make any progress. The OOM killer won't be triggered. - GFP_KERNEL | __GFP_NOFAIL - overrides the default allocator behavior and all allocation requests will loop endlessly until they succeed. This might be really dangerous especially for larger orders. Existing users of __GFP_REPEAT are changed to __GFP_RETRY_MAYFAIL because they already had their semantic. No new users are added. __alloc_pages_slowpath is changed to bail out for __GFP_RETRY_MAYFAIL if there is no progress and we have already passed the OOM point. This means that all the reclaim opportunities have been exhausted except the most disruptive one (the OOM killer) and a user defined fallback behavior is more sensible than keep retrying in the page allocator. [akpm@linux-foundation.org: fix arch/sparc/kernel/mdesc.c] [mhocko@suse.com: semantic fix] Link: http://lkml.kernel.org/r/20170626123847.GM11534@dhcp22.suse.cz [mhocko@kernel.org: address other thing spotted by Vlastimil] Link: http://lkml.kernel.org/r/20170626124233.GN11534@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170623085345.11304-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Alex Belits <alex.belits@cavium.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: David Daney <david.daney@cavium.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: NeilBrown <neilb@suse.com> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
David Rientjes
|
0622622677 |
mm, vmscan: avoid thrashing anon lru when free + file is low
The purpose of the code that commit
|
||
|
Johannes Weiner
|
385386cff4 |
mm: vmstat: move slab statistics from zone to node counters
Patch series "mm: per-lruvec slab stats" Josef is working on a new approach to balancing slab caches and the page cache. For this to work, he needs slab cache statistics on the lruvec level. These patches implement that by adding infrastructure that allows updating and reading generic VM stat items per lruvec, then switches some existing VM accounting sites, including the slab accounting ones, to this new cgroup-aware API. I'll follow up with more patches on this, because there is actually substantial simplification that can be done to the memory controller when we replace private memcg accounting with making the existing VM accounting sites cgroup-aware. But this is enough for Josef to base his slab reclaim work on, so here goes. This patch (of 5): To re-implement slab cache vs. page cache balancing, we'll need the slab counters at the lruvec level, which, ever since lru reclaim was moved from the zone to the node, is the intersection of the node, not the zone, and the memcg. We could retain the per-zone counters for when the page allocator dumps its memory information on failures, and have counters on both levels - which on all but NUMA node 0 is usually redundant. But let's keep it simple for now and just move them. If anybody complains we can restore the per-zone counters. [hannes@cmpxchg.org: fix oops] Link: http://lkml.kernel.org/r/20170605183511.GA8915@cmpxchg.org Link: http://lkml.kernel.org/r/20170530181724.27197-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Roman Gushchin
|
2262185c5b |
mm: per-cgroup memory reclaim stats
Track the following reclaim counters for every memory cgroup: PGREFILL, PGSCAN, PGSTEAL, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE and PGLAZYFREED. These values are exposed using the memory.stats interface of cgroup v2. The meaning of each value is the same as for global counters, available using /proc/vmstat. Also, for consistency, rename mem_cgroup_count_vm_event() to count_memcg_event_mm(). Link: http://lkml.kernel.org/r/1494530183-30808-1-git-send-email-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Huang Ying
|
747552b1e7 |
mm, THP, swap: enable THP swap optimization only if has compound map
If there is no compound map for a THP (Transparent Huge Page), it is possible that the map count of some sub-pages of the THP is 0. So it is better to split the THP before swapping out. In this way, the sub-pages not mapped will be freed, and we can avoid the unnecessary swap out operations for these sub-pages. Link: http://lkml.kernel.org/r/20170515112522.32457-6-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Huang Ying
|
b8f593cd08 |
mm, THP, swap: check whether THP can be split firstly
To swap out THP (Transparent Huage Page), before splitting the THP, the swap cluster will be allocated and the THP will be added into the swap cache. But it is possible that the THP cannot be split, so that we must delete the THP from the swap cache and free the swap cluster. To avoid that, in this patch, whether the THP can be split is checked firstly. The check can only be done racy, but it is good enough for most cases. With the patch, the swap out throughput improves 3.6% (from about 4.16GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170515112522.32457-5-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for can_split_huge_page()] Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
0f0746589e |
mm, THP, swap: move anonymous THP split logic to vmscan
The add_to_swap aims to allocate swap_space(ie, swap slot and swapcache) so if it fails due to lack of space in case of THP or something(hdd swap but tries THP swapout) *caller* rather than add_to_swap itself should split the THP page and retry it with base page which is more natural. Link: http://lkml.kernel.org/r/20170515112522.32457-4-ying.huang@intel.com Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
75f6d6d29a |
mm, THP, swap: unify swap slot free functions to put_swap_page
Now, get_swap_page takes struct page and allocates swap space according to page size(ie, normal or THP) so it would be more cleaner to introduce put_swap_page which is a counter function of get_swap_page. Then, it calls right swap slot free function depending on page's size. [ying.huang@intel.com: minor cleanup and fix] Link: http://lkml.kernel.org/r/20170515112522.32457-3-ying.huang@intel.com Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Nick Desaulniers
|
f2f43e566a |
mm/vmscan.c: fix unsequenced modification and access warning
Clang and its -Wunsequenced emits a warning
mm/vmscan.c:2961:25: error: unsequenced modification and access to 'gfp_mask' [-Wunsequenced]
.gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
^
While it is not clear to me whether the initialization code violates the
specification (6.7.8 par 19 (ISO/IEC 9899) looks like it disagrees) the
code is quite confusing and worth cleaning up anyway. Fix this by
reusing sc.gfp_mask rather than the updated input gfp_mask parameter.
Link: http://lkml.kernel.org/r/20170510154030.10720-1-nick.desaulniers@gmail.com
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Thomas Gleixner
|
c6202adf3a |
mm/vmscan: Adjust system_state checks
To enable smp_processor_id() and might_sleep() debug checks earlier, it's required to add system states between SYSTEM_BOOTING and SYSTEM_RUNNING. Adjust the system_state check in kswapd_run() to handle the extra states. Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170516184736.119158930@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Minchan Kim
|
791b48b642 |
mm: vmscan: scan until it finds eligible pages
Although there are a ton of free swap and anonymous LRU page in elgible
zones, OOM happened.
balloon invoked oom-killer: gfp_mask=0x17080c0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOTRACK), nodemask=(null), order=0, oom_score_adj=0
CPU: 7 PID: 1138 Comm: balloon Not tainted 4.11.0-rc6-mm1-zram-00289-ge228d67e9677-dirty #17
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
oom_kill_process+0x21d/0x3f0
out_of_memory+0xd8/0x390
__alloc_pages_slowpath+0xbc1/0xc50
__alloc_pages_nodemask+0x1a5/0x1c0
pte_alloc_one+0x20/0x50
__pte_alloc+0x1e/0x110
__handle_mm_fault+0x919/0x960
handle_mm_fault+0x77/0x120
__do_page_fault+0x27a/0x550
trace_do_page_fault+0x43/0x150
do_async_page_fault+0x2c/0x90
async_page_fault+0x28/0x30
Mem-Info:
active_anon:424716 inactive_anon:65314 isolated_anon:0
active_file:52 inactive_file:46 isolated_file:0
unevictable:0 dirty:27 writeback:0 unstable:0
slab_reclaimable:3967 slab_unreclaimable:4125
mapped:133 shmem:43 pagetables:1674 bounce:0
free:4637 free_pcp:225 free_cma:0
Node 0 active_anon:1698864kB inactive_anon:261256kB active_file:208kB inactive_file:184kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:532kB dirty:108kB writeback:0kB shmem:172kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
DMA free:7316kB min:32kB low:44kB high:56kB active_anon:8064kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:464kB slab_unreclaimable:40kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 992 992 1952
DMA32 free:9088kB min:2048kB low:3064kB high:4080kB active_anon:952176kB inactive_anon:0kB active_file:36kB inactive_file:0kB unevictable:0kB writepending:88kB present:1032192kB managed:1019388kB mlocked:0kB slab_reclaimable:13532kB slab_unreclaimable:16460kB kernel_stack:3552kB pagetables:6672kB bounce:0kB free_pcp:56kB local_pcp:24kB free_cma:0kB
lowmem_reserve[]: 0 0 0 959
Movable free:3644kB min:1980kB low:2960kB high:3940kB active_anon:738560kB inactive_anon:261340kB active_file:188kB inactive_file:640kB unevictable:0kB writepending:20kB present:1048444kB managed:1010816kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:832kB local_pcp:60kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
DMA: 1*4kB (E) 0*8kB 18*16kB (E) 10*32kB (E) 10*64kB (E) 9*128kB (ME) 8*256kB (E) 2*512kB (E) 2*1024kB (E) 0*2048kB 0*4096kB = 7524kB
DMA32: 417*4kB (UMEH) 181*8kB (UMEH) 68*16kB (UMEH) 48*32kB (UMEH) 14*64kB (MH) 3*128kB (M) 1*256kB (H) 1*512kB (M) 2*1024kB (M) 0*2048kB 0*4096kB = 9836kB
Movable: 1*4kB (M) 1*8kB (M) 1*16kB (M) 1*32kB (M) 0*64kB 1*128kB (M) 2*256kB (M) 4*512kB (M) 1*1024kB (M) 0*2048kB 0*4096kB = 3772kB
378 total pagecache pages
17 pages in swap cache
Swap cache stats: add 17325, delete 17302, find 0/27
Free swap = 978940kB
Total swap = 1048572kB
524157 pages RAM
0 pages HighMem/MovableOnly
12629 pages reserved
0 pages cma reserved
0 pages hwpoisoned
[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name
[ 433] 0 433 4904 5 14 3 82 0 upstart-udev-br
[ 438] 0 438 12371 5 27 3 191 -1000 systemd-udevd
With investigation, skipping page of isolate_lru_pages makes reclaim
void because it returns zero nr_taken easily so LRU shrinking is
effectively nothing and just increases priority aggressively. Finally,
OOM happens.
The problem is that get_scan_count determines nr_to_scan with eligible
zones so although priority drops to zero, it couldn't reclaim any pages
if the LRU contains mostly ineligible pages.
get_scan_count:
size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
size = size >> sc->priority;
Assumes sc->priority is 0 and LRU list is as follows.
N-N-N-N-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H
(Ie, small eligible pages are in the head of LRU but others are
almost ineligible pages)
In that case, size becomes 4 so VM want to scan 4 pages but 4 pages from
tail of the LRU are not eligible pages. If get_scan_count counts
skipped pages, it doesn't reclaim any pages remained after scanning 4
pages so it ends up OOM happening.
This patch makes isolate_lru_pages try to scan pages until it encounters
eligible zones's pages.
[akpm@linux-foundation.org: clean up mind-bending `for' statement. Tweak comment text]
Fixes:
|
||
|
Vlastimil Babka
|
499118e966 |
mm: introduce memalloc_noreclaim_{save,restore}
The previous patch ("mm: prevent potential recursive reclaim due to
clearing PF_MEMALLOC") has shown that simply setting and clearing
PF_MEMALLOC in current->flags can result in wrongly clearing a
pre-existing PF_MEMALLOC flag and potentially lead to recursive reclaim.
Let's introduce helpers that support proper nesting by saving the
previous stat of the flag, similar to the existing memalloc_noio_* and
memalloc_nofs_* helpers. Convert existing setting/clearing of
PF_MEMALLOC within mm to the new helpers.
There are no known issues with the converted code, but the change makes
it more robust.
Link: http://lkml.kernel.org/r/20170405074700.29871-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Chris Leech <cleech@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Lee Duncan <lduncan@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Johannes Weiner
|
ccda7f4360 |
mm: memcontrol: use node page state naming scheme for memcg
The memory controllers stat function names are awkwardly long and arbitrarily different from the zone and node stat functions. The current interface is named: mem_cgroup_read_stat() mem_cgroup_update_stat() mem_cgroup_inc_stat() mem_cgroup_dec_stat() mem_cgroup_update_page_stat() mem_cgroup_inc_page_stat() mem_cgroup_dec_page_stat() This patch renames it to match the corresponding node stat functions: memcg_page_state() [node_page_state()] mod_memcg_state() [mod_node_state()] inc_memcg_state() [inc_node_state()] dec_memcg_state() [dec_node_state()] mod_memcg_page_state() [mod_node_page_state()] inc_memcg_page_state() [inc_node_page_state()] dec_memcg_page_state() [dec_node_page_state()] Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
71cd31135d |
mm: memcontrol: re-use node VM page state enum
The current duplication is a high-maintenance mess, and it's painful to add new items or query memcg state from the rest of the VM. This increases the size of the stat array marginally, but we should aim to track all these stats on a per-cgroup level anyway. Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
31176c7815 |
mm: memcontrol: clean up memory.events counting function
We only ever count single events, drop the @nr parameter. Rename the function accordingly. Remove low-information kerneldoc. Link: http://lkml.kernel.org/r/20170404220148.28338-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
2a2e48854d |
mm: vmscan: fix IO/refault regression in cache workingset transition
Since commit |
||
|
Minchan Kim
|
666e5a406c |
mm: make ttu's return boolean
try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for boolean return. This patch changes it. Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
33fc80e257 |
mm: remove SWAP_AGAIN in ttu
In 2002, [1] introduced SWAP_AGAIN. At that time, try_to_unmap_one used
spin_trylock(&mm->page_table_lock) so it's really easy to contend and
fail to hold a lock so SWAP_AGAIN to keep LRU status makes sense.
However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN so
remove SWAP_AGAIN and just return SWAP_FAIL.
[1]
|
||
|
Minchan Kim
|
ad6b67041a |
mm: remove SWAP_MLOCK in ttu
ttu doesn't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL because it means the page is not-swappable so it should move to another LRU list(active or unevictable). putback friends will move it to right list depending on the page's LRU flag. Link: http://lkml.kernel.org/r/1489555493-14659-6-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
18863d3a3f |
mm: remove SWAP_DIRTY in ttu
If we found lazyfree page is dirty, try_to_unmap_one can just SetPageSwapBakced in there like PG_mlocked page and just return with SWAP_FAIL which is very natural because the page is not swappable right now so that vmscan can activate it. There is no point to introduce new return value SWAP_DIRTY in try_to_unmap at the moment. Link: http://lkml.kernel.org/r/1489555493-14659-3-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Yisheng Xie
|
d6622f6365 |
mm/vmscan: more restrictive condition for retry in do_try_to_free_pages
By reviewing code, I find that when enter do_try_to_free_pages, the may_thrash is always clear, and it will retry shrink zones to tap cgroup's reserves memory by setting may_thrash when the former shrink_zones reclaim nothing. However, when memcg is disabled or on legacy hierarchy, or there do not have any memcg protected by low limit, it should not do this useless retry at all, for we do not have any cgroup's reserves memory to tap, and we have already done hard work but made no progress, which as Michal pointed out in former version, we are trying hard to control the retry logical of page alloctor, and the current additional round of reclaim is just lame. Therefore, to avoid this unneeded retrying and make code more readable, we remove the may_thrash field in scan_control, instead, introduce memcg_low_reclaim and memcg_low_skipped, and only retry when memcg_low_skipped, by setting memcg_low_reclaim. [xieyisheng1@huawei.com: remove may_thrash field, introduce mem_cgroup_reclaim] Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Michal Hocko <mhocko@kernel.org> Suggested-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
e716f2eb24 |
mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx
kswapd is woken to reclaim a node based on a failed allocation request
from any eligible zone. Once reclaiming in balance_pgdat(), it will
continue reclaiming until there is an eligible zone available for the
zone it was woken for. kswapd tracks what zone it was recently woken
for in pgdat->kswapd_classzone_idx. If it has not been woken recently,
this zone will be 0.
However, the decision on whether to sleep is made on
kswapd_classzone_idx which is 0 without a recent wakeup request and that
classzone does not account for lowmem reserves. This allows kswapd to
sleep when a low small zone such as ZONE_DMA is balanced for a GFP_DMA
request even if a stream of allocations cannot use that zone. While
kswapd may be woken again shortly in the near future there are two
consequences -- the pgdat bits that control congestion are cleared
prematurely and direct reclaim is more likely as kswapd slept
prematurely.
This patch flips kswapd_classzone_idx to default to MAX_NR_ZONES (an
invalid index) when there has been no recent wakeups. If there are no
wakeups, it'll decide whether to sleep based on the highest possible
zone available (MAX_NR_ZONES - 1). It then becomes critical that the
"pgdat balanced" decisions during reclaim and when deciding to sleep are
the same. If there is a mismatch, kswapd can stay awake continually
trying to balance tiny zones.
simoop was used to evaluate it again. Two of the preparation patches
regressed the workload so they are included as the second set of
results. Otherwise this patch looks artifically excellent
4.11.0-rc1 4.11.0-rc1 4.11.0-rc1
vanilla clear-v2 keepawake-v2
Amean p50-Read 21670074.18 ( 0.00%) 19786774.76 ( 8.69%) 22668332.52 ( -4.61%)
Amean p95-Read 25456267.64 ( 0.00%) 24101956.27 ( 5.32%) 26738688.00 ( -5.04%)
Amean p99-Read 29369064.73 ( 0.00%) 27691872.71 ( 5.71%) 30991404.52 ( -5.52%)
Amean p50-Write 1390.30 ( 0.00%) 1011.91 ( 27.22%) 924.91 ( 33.47%)
Amean p95-Write 412901.57 ( 0.00%) 34874.98 ( 91.55%) 1362.62 ( 99.67%)
Amean p99-Write 6668722.09 ( 0.00%) 575449.60 ( 91.37%) 16854.04 ( 99.75%)
Amean p50-Allocation 78714.31 ( 0.00%) 84246.26 ( -7.03%) 74729.74 ( 5.06%)
Amean p95-Allocation 175533.51 ( 0.00%) 400058.43 (-127.91%) 101609.74 ( 42.11%)
Amean p99-Allocation 247003.02 ( 0.00%) 10905600.00 (-4315.17%) 125765.57 ( 49.08%)
With this patch on top, write and allocation latencies are massively
improved. The read latencies are slightly impaired but it's worth
noting that this is mostly due to the IO scheduler and not directly
related to reclaim. The vmstats are a bit of a mix but the relevant
ones are as follows;
4.10.0-rc7 4.10.0-rc7 4.10.0-rc7
mmots-20170209 clear-v1r25keepawake-v1r25
Swap Ins 0 0 0
Swap Outs 0 608 0
Direct pages scanned 6910672
|
||
|
Mel Gorman
|
631b6e083e |
mm, vmscan: only clear pgdat congested/dirty/writeback state when balanced
A pgdat tracks if recent reclaim encountered too many dirty, writeback
or congested pages. The flags control whether kswapd writes pages back
from reclaim context, tags pages for immediate reclaim when IO
completes, whether processes block on wait_iff_congested and whether
kswapd blocks when too many pages marked for immediate reclaim are
encountered.
The state is cleared in a check function with side-effects. With the
patch "mm, vmscan: fix zone balance check in prepare_kswapd_sleep", the
timing of when the bits get cleared changed. Due to the way the check
works, it'll clear the bits if ZONE_DMA is balanced for a GFP_DMA
allocation because it does not account for lowmem reserves properly.
For the simoop workload, kswapd is not stalling when it should due to
the premature clearing, writing pages from reclaim context like crazy
and generally being unhelpful.
This patch resets the pgdat bits related to page reclaim only when
kswapd is going to sleep. The comparison with simoop is then
4.11.0-rc1 4.11.0-rc1 4.11.0-rc1
vanilla fixcheck-v2 clear-v2
Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%) 19786774.76 ( 8.69%)
Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%) 24101956.27 ( 5.32%)
Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%) 27691872.71 ( 5.71%)
Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%) 1011.91 ( 27.22%)
Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%) 34874.98 ( 91.55%)
Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%) 575449.60 ( 91.37%)
Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%) 84246.26 ( -7.03%)
Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%) 400058.43 (-127.91%)
Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%) 10905600.00 (-4315.17%)
Read latency is improved, write latency is mostly improved but
allocation latency is regressed. kswapd is still reclaiming
inefficiently, pages are being written back from writeback context and a
host of other issues. However, given the change, it needed to be
spelled out why the side-effect was moved.
Link: http://lkml.kernel.org/r/20170309075657.25121-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Shantanu Goel
|
333b0a459c |
mm, vmscan: fix zone balance check in prepare_kswapd_sleep
Patch series "Reduce amount of time kswapd sleeps prematurely", v2.
The series is unusual in that the first patch fixes one problem and
introduces other issues that are noted in the changelog. Patch 2 makes
a minor modification that is worth considering on its own but leaves the
kernel in a state where it behaves badly. It's not until patch 3 that
there is an improvement against baseline.
This was mostly motivated by examining Chris Mason's "simoop" benchmark
which puts the VM under similar pressure to HADOOP. It has been
reported that the benchmark has regressed severely during the last
number of releases. While I cannot reproduce all the same problems
Chris experienced due to hardware limitations, there was a number of
problems on a 2-socket machine with a single disk.
simoop latencies
4.11.0-rc1 4.11.0-rc1
vanilla keepawake-v2
Amean p50-Read 21670074.18 ( 0.00%) 22668332.52 ( -4.61%)
Amean p95-Read 25456267.64 ( 0.00%) 26738688.00 ( -5.04%)
Amean p99-Read 29369064.73 ( 0.00%) 30991404.52 ( -5.52%)
Amean p50-Write 1390.30 ( 0.00%) 924.91 ( 33.47%)
Amean p95-Write 412901.57 ( 0.00%) 1362.62 ( 99.67%)
Amean p99-Write 6668722.09 ( 0.00%) 16854.04 ( 99.75%)
Amean p50-Allocation 78714.31 ( 0.00%) 74729.74 ( 5.06%)
Amean p95-Allocation 175533.51 ( 0.00%) 101609.74 ( 42.11%)
Amean p99-Allocation 247003.02 ( 0.00%) 125765.57 ( 49.08%)
These are latencies. Read/write are threads reading fixed-size random
blocks from a simulated database. The allocation latency is mmaping and
faulting regions of memory. The p50, 95 and p99 reports the worst
latencies for 50% of the samples, 95% and 99% respectively.
For example, the report indicates that while the test was running 99% of
writes completed 99.75% faster. It's worth noting that on a UMA machine
that no difference in performance with simoop was observed so milage
will vary.
It's noted that there is a slight impact to read latencies but it's
mostly due to IO scheduler decisions and offset by the large reduction
in other latencies.
This patch (of 3):
The check in prepare_kswapd_sleep needs to match the one in
balance_pgdat since the latter will return as soon as any one of the
zones in the classzone is above the watermark. This is specially
important for higher order allocations since balance_pgdat will
typically reset the order to zero relying on compaction to create the
higher order pages. Without this patch, prepare_kswapd_sleep fails to
wake up kcompactd since the zone balance check fails.
It was first reported against 4.9.7 that kswapd is failing to wake up
kcompactd due to a mismatch in the zone balance check between
balance_pgdat() and prepare_kswapd_sleep().
balance_pgdat() returns as soon as a single zone satisfies the
allocation but prepare_kswapd_sleep() requires all zones to do +the
same. This causes prepare_kswapd_sleep() to never succeed except in the
order == 0 case and consequently, wakeup_kcompactd() is never called.
For the machine that originally motivated this patch, the state of
compaction from /proc/vmstat looked this way after a day and a half +of
uptime:
compact_migrate_scanned 240496
compact_free_scanned 76238632
compact_isolated 123472
compact_stall 1791
compact_fail 29
compact_success 1762
compact_daemon_wake 0
After applying the patch and about 10 hours of uptime the state looks
like this:
compact_migrate_scanned 59927299
compact_free_scanned 2021075136
compact_isolated 640926
compact_stall 4
compact_fail 2
compact_success 2
compact_daemon_wake 5160
Further notes from Mel that motivated him to pick this patch up and
resend it;
It was observed for the simoop workload (pressures the VM similar to
HADOOP) that kswapd was failing to keep ahead of direct reclaim. The
investigation noted that there was a need to rationalise kswapd
decisions to reclaim with kswapd decisions to sleep. With this patch on
a 2-socket box, there was a 49% reduction in direct reclaim scanning.
However, the impact otherwise is extremely negative. Kswapd reclaim
efficiency dropped from 98% to 76%. simoop has three latency-related
metrics for read, write and allocation (an anonymous mmap and fault).
4.11.0-rc1 4.11.0-rc1
vanilla fixcheck-v2
Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%)
Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%)
Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%)
Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%)
Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%)
Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%)
Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%)
Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%)
Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%)
Of greater concern is that the patch causes swapping and page writes
from kswapd context rose from 0 pages to 4189753 pages during the hour
the workload ran for. By and large, the patch has very bad behaviour
but easily missed as the impact on a UMA machine is negligible.
This patch is included with the data in case a bisection leads to this
area. This patch is also a pre-requisite for the rest of the series.
Link: http://lkml.kernel.org/r/20170309075657.25121-2-mgorman@techsingularity.net
Signed-off-by: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Michal Hocko
|
7dea19f9ee |
mm: introduce memalloc_nofs_{save,restore} API
GFP_NOFS context is used for the following 5 reasons currently:
- to prevent from deadlocks when the lock held by the allocation
context would be needed during the memory reclaim
- to prevent from stack overflows during the reclaim because the
allocation is performed from a deep context already
- to prevent lockups when the allocation context depends on other
reclaimers to make a forward progress indirectly
- just in case because this would be safe from the fs POV
- silence lockdep false positives
Unfortunately overuse of this allocation context brings some problems to
the MM. Memory reclaim is much weaker (especially during heavy FS
metadata workloads), OOM killer cannot be invoked because the MM layer
doesn't have enough information about how much memory is freeable by the
FS layer.
In many cases it is far from clear why the weaker context is even used
and so it might be used unnecessarily. We would like to get rid of
those as much as possible. One way to do that is to use the flag in
scopes rather than isolated cases. Such a scope is declared when really
necessary, tracked per task and all the allocation requests from within
the context will simply inherit the GFP_NOFS semantic.
Not only this is easier to understand and maintain because there are
much less problematic contexts than specific allocation requests, this
also helps code paths where FS layer interacts with other layers (e.g.
crypto, security modules, MM etc...) and there is no easy way to convey
the allocation context between the layers.
Introduce memalloc_nofs_{save,restore} API to control the scope of
GFP_NOFS allocation context. This is basically copying
memalloc_noio_{save,restore} API we have for other restricted allocation
context GFP_NOIO. The PF_MEMALLOC_NOFS flag already exists and it is
just an alias for PF_FSTRANS which has been xfs specific until recently.
There are no more PF_FSTRANS users anymore so let's just drop it.
PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS
implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO. memalloc_noio_flags
is renamed to current_gfp_context because it now cares about both
PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts. Xfs code paths preserve
their semantic. kmem_flags_convert() doesn't need to evaluate the flag
anymore.
This patch shouldn't introduce any functional changes.
Let's hope that filesystems will drop direct GFP_NOFS (resp. ~__GFP_FS)
usage as much as possible and only use a properly documented
memalloc_nofs_{save,restore} checkpoints where they are appropriate.
[akpm@linux-foundation.org: fix comment typo, reflow comment]
Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Shaohua Li
|
802a3a92ad |
mm: reclaim MADV_FREE pages
When memory pressure is high, we free MADV_FREE pages. If the pages are not dirty in pte, the pages could be freed immediately. Otherwise we can't reclaim them. We put the pages back to anonumous LRU list (by setting SwapBacked flag) and the pages will be reclaimed in normal swapout way. We use normal page reclaim policy. Since MADV_FREE pages are put into inactive file list, such pages and inactive file pages are reclaimed according to their age. This is expected, because we don't want to reclaim too many MADV_FREE pages before used once pages. Based on Minchan's original patch [minchan@kernel.org: clean up lazyfree page handling] Link: http://lkml.kernel.org/r/20170303025237.GB3503@bbox Link: http://lkml.kernel.org/r/14b8eb1d3f6bf6cc492833f183ac8c304e560484.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Shaohua Li
|
a128ca71fb |
mm: delete unnecessary TTU_* flags
Patch series "mm: fix some MADV_FREE issues", v5. We are trying to use MADV_FREE in jemalloc. Several issues are found. Without solving the issues, jemalloc can't use the MADV_FREE feature. - Doesn't support system without swap enabled. Because if swap is off, we can't or can't efficiently age anonymous pages. And since MADV_FREE pages are mixed with other anonymous pages, we can't reclaim MADV_FREE pages. In current implementation, MADV_FREE will fallback to MADV_DONTNEED without swap enabled. But in our environment, a lot of machines don't enable swap. This will prevent our setup using MADV_FREE. - Increases memory pressure. page reclaim bias file pages reclaim against anonymous pages. This doesn't make sense for MADV_FREE pages, because those pages could be freed easily and refilled with very slight penality. Even page reclaim doesn't bias file pages, there is still an issue, because MADV_FREE pages and other anonymous pages are mixed together. To reclaim a MADV_FREE page, we probably must scan a lot of other anonymous pages, which is inefficient. In our test, we usually see oom with MADV_FREE enabled and nothing without it. - Accounting. There are two accounting problems. We don't have a global accounting. If the system is abnormal, we don't know if it's a problem from MADV_FREE side. The other problem is RSS accounting. MADV_FREE pages are accounted as normal anon pages and reclaimed lazily, so application's RSS becomes bigger. This confuses our workloads. We have monitoring daemon running and if it finds applications' RSS becomes abnormal, the daemon will kill the applications even kernel can reclaim the memory easily. To address the first the two issues, we can either put MADV_FREE pages into a separate LRU list (Minchan's previous patches and V1 patches), or put them into LRU_INACTIVE_FILE list (suggested by Johannes). The patchset use the second idea. The reason is LRU_INACTIVE_FILE list is tiny nowadays and should be full of used once file pages. So we can still efficiently reclaim MADV_FREE pages there without interference with other anon and active file pages. Putting the pages into inactive file list also has an advantage which allows page reclaim to prioritize MADV_FREE pages and used once file pages. MADV_FREE pages are put into the lru list and clear SwapBacked flag, so PageAnon(page) && !PageSwapBacked(page) will indicate a MADV_FREE pages. These pages will directly freed without pageout if they are clean, otherwise normal swap will reclaim them. For the third issue, the previous post adds global accounting and a separate RSS count for MADV_FREE pages. The problem is we never get accurate accounting for MADV_FREE pages. The pages are mapped to userspace, can be dirtied without notice from kernel side. To get accurate accounting, we could write protect the page, but then there is extra page fault overhead, which people don't want to pay. Jemalloc guys have concerns about the inaccurate accounting, so this post drops the accounting patches temporarily. The info exported to /proc/pid/smaps for MADV_FREE pages are kept, which is the only place we can get accurate accounting right now. This patch (of 6): Johannes pointed out TTU_LZFREE is unnecessary. It's true because we always have the flag set if we want to do an unmap. For cases we don't do an unmap, the TTU_LZFREE part of code should never run. Also the TTU_UNMAP is unnecessary. If no other flags set (for example, TTU_MIGRATION), an unmap is implied. The patch includes Johannes's cleanup and dead TTU_ACTION macro removal code Link: http://lkml.kernel.org/r/4be3ea1bc56b26fd98a54d0a6f70bec63f6d8980.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
3db65812d6 |
Revert "mm, vmscan: account for skipped pages as a partial scan"
This reverts commit
|
||
|
Johannes Weiner
|
c822f6223d |
mm: delete NR_PAGES_SCANNED and pgdat_reclaimable()
NR_PAGES_SCANNED counts number of pages scanned since the last page free event in the allocator. This was used primarily to measure the reclaimability of zones and nodes, and determine when reclaim should give up on them. In that role, it has been replaced in the preceding patches by a different mechanism. Being implemented as an efficient vmstat counter, it was automatically exported to userspace as well. It's however unlikely that anyone outside the kernel is using this counter in any meaningful way. Remove the counter and the unused pgdat_reclaimable(). Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
688035f729 |
mm: don't avoid high-priority reclaim on memcg limit reclaim
Commit
|
||
|
Johannes Weiner
|
a2d7f8e461 |
mm: don't avoid high-priority reclaim on unreclaimable nodes
Commit |
||
|
Johannes Weiner
|
047d72c30e |
mm: remove seemingly spurious reclaimability check from laptop_mode gating
Commit
|
||
|
Johannes Weiner
|
d450abd81b |
mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling
PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
all free pages in each zone fall below half the min watermark. During
the summation, we want to exclude zones that don't have reclaimables.
Checking the same pgdat over and over again doesn't make sense.
Fixes:
|
||
|
Johannes Weiner
|
c73322d098 |
mm: fix 100% CPU kswapd busyloop on unreclaimable nodes
Patch series "mm: kswapd spinning on unreclaimable nodes - fixes and
cleanups".
Jia reported a scenario in which the kswapd of a node indefinitely spins
at 100% CPU usage. We have seen similar cases at Facebook.
The kernel's current method of judging its ability to reclaim a node (or
whether to back off and sleep) is based on the amount of scanned pages
in proportion to the amount of reclaimable pages. In Jia's and our
scenarios, there are no reclaimable pages in the node, however, and the
condition for backing off is never met. Kswapd busyloops in an attempt
to restore the watermarks while having nothing to work with.
This series reworks the definition of an unreclaimable node based not on
scanning but on whether kswapd is able to actually reclaim pages in
MAX_RECLAIM_RETRIES (16) consecutive runs. This is the same criteria
the page allocator uses for giving up on direct reclaim and invoking the
OOM killer. If it cannot free any pages, kswapd will go to sleep and
leave further attempts to direct reclaim invocations, which will either
make progress and re-enable kswapd, or invoke the OOM killer.
Patch #1 fixes the immediate problem Jia reported, the remainder are
smaller fixlets, cleanups, and overall phasing out of the old method.
Patch #6 is the odd one out. It's a nice cleanup to get_scan_count(),
and directly related to #5, but in itself not relevant to the series.
If the whole series is too ambitious for 4.11, I would consider the
first three patches fixes, the rest cleanups.
This patch (of 9):
Jia He reports a problem with kswapd spinning at 100% CPU when
requesting more hugepages than memory available in the system:
$ echo 4000 >/proc/sys/vm/nr_hugepages
top - 13:42:59 up 3:37, 1 user, load average: 1.09, 1.03, 1.01
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 12.5 sy, 0.0 ni, 85.5 id, 2.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 31371520 total, 30915136 used, 456384 free, 320 buffers
KiB Swap: 6284224 total, 115712 used, 6168512 free. 48192 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
76 root 20 0 0 0 0 R 100.0 0.000 217:17.29 kswapd3
At that time, there are no reclaimable pages left in the node, but as
kswapd fails to restore the high watermarks it refuses to go to sleep.
Kswapd needs to back away from nodes that fail to balance. Up until
commit
|
||
|
Ingo Molnar
|
5b3cc15aff |
sched/headers: Prepare to move the memalloc_noio_*() APIs to <linux/sched/mm.h>
Update the .c files that depend on these APIs. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Mel Gorman
|
c2f83143f1 |
mm, vmscan: clear PGDAT_WRITEBACK when zone is balanced
Hillf Danton pointed out that since commit |
||
|
Johannes Weiner
|
c55e8d035b |
mm: vmscan: move dirty pages out of the way until they're flushed
We noticed a performance regression when moving hadoop workloads from 3.10 kernels to 4.0 and 4.6. This is accompanied by increased pageout activity initiated by kswapd as well as frequent bursts of allocation stalls and direct reclaim scans. Even lowering the dirty ratios to the equivalent of less than 1% of memory would not eliminate the issue, suggesting that dirty pages concentrate where the scanner is looking. This can be traced back to recent efforts of thrash avoidance. Where 3.10 would not detect refaulting pages and continuously supply clean cache to the inactive list, a thrashing workload on 4.0+ will detect and activate refaulting pages right away, distilling used-once pages on the inactive list much more effectively. This is by design, and it makes sense for clean cache. But for the most part our workload's cache faults are refaults and its use-once cache is from streaming writes. We end up with most of the inactive list dirty, and we don't go after the active cache as long as we have use-once pages around. But waiting for writes to avoid reclaiming clean cache that *might* refault is a bad trade-off. Even if the refaults happen, reads are faster than writes. Before getting bogged down on writeback, reclaim should first look at *all* cache in the system, even active cache. To accomplish this, activate pages that are dirty or under writeback when they reach the end of the inactive LRU. The pages are marked for immediate reclaim, meaning they'll get moved back to the inactive LRU tail as soon as they're written back and become reclaimable. But in the meantime, by reducing the inactive list to only immediately reclaimable pages, we allow the scanner to deactivate and refill the inactive list with clean cache from the active list tail to guarantee forward progress. [hannes@cmpxchg.org: update comment] Link: http://lkml.kernel.org/r/20170202191957.22872-8-hannes@cmpxchg.org Link: http://lkml.kernel.org/r/20170123181641.23938-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
4eda482350 |
mm: vmscan: only write dirty pages that the scanner has seen twice
Dirty pages can easily reach the end of the LRU while there are still clean pages to reclaim around. Don't let kswapd write them back just because there are a lot of them. It costs more CPU to find the clean pages, but that's almost certainly better than to disrupt writeback from the flushers with LRU-order single-page writes from reclaim. And the flushers have been woken up by that point, so we spend IO capacity on flushing and CPU capacity on finding the clean cache. Only start writing dirty pages if they have cycled around the LRU twice now and STILL haven't been queued on the IO device. It's possible that the dirty pages are so sparsely distributed across different bdis, inodes, memory cgroups, that the flushers take forever to get to the ones we want reclaimed. Once we see them twice on the LRU, we know that's the quicker way to find them, so do LRU writeback. Link: http://lkml.kernel.org/r/20170123181641.23938-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
bbef938429 |
mm: vmscan: remove old flusher wakeup from direct reclaim path
Direct reclaim has been replaced by kswapd reclaim in pretty much all common memory pressure situations, so this code most likely doesn't accomplish the described effect anymore. The previous patch wakes up flushers for all reclaimers when we encounter dirty pages at the tail end of the LRU. Remove the crufty old direct reclaim invocation. Link: http://lkml.kernel.org/r/20170123181641.23938-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
726d061fbd |
mm: vmscan: kick flushers when we encounter dirty pages on the LRU
Memory pressure can put dirty pages at the end of the LRU without anybody running into dirty limits. Don't start writing individual pages from kswapd while the flushers might be asleep. Unlike the old direct reclaim flusher wakeup (removed in the next patch) that flushes the number of pages just scanned, this patch wakes the flushers for all outstanding dirty pages. That seemed to perform better in a synthetic test that pushes dirty pages to the end of the LRU and into reclaim, because we know LRU aging outstrips writeback already, and this way we give younger dirty pages a headstart rather than wait until reclaim runs into them as well. It also means less plugging and risk of exhausting the struct request pool from reclaim. There is a concern that this will cause temporary files that used to get dirtied and truncated before writeback to now get written to disk under memory pressure. If this turns out to be a real problem, we'll have to revisit this and tame the reclaim flusher wakeups. [hannes@cmpxchg.org: mention dirty expiration as a condition] Link: http://lkml.kernel.org/r/20170126174739.GA30636@cmpxchg.org Link: http://lkml.kernel.org/r/20170123181641.23938-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
1276ad68e2 |
mm: vmscan: scan dirty pages even in laptop mode
Patch series "mm: vmscan: fix kswapd writeback regression".
We noticed a regression on multiple hadoop workloads when moving from
3.10 to 4.0 and 4.6, which involves kswapd getting tangled up in page
writeout, causing direct reclaim herds that also don't make progress.
I tracked it down to the thrash avoidance efforts after 3.10 that make
the kernel better at keeping use-once cache and use-many cache sorted on
the inactive and active list, with more aggressive protection of the
active list as long as there is inactive cache. Unfortunately, our
workload's use-once cache is mostly from streaming writes. Waiting for
writes to avoid potential reloads in the future is not a good tradeoff.
These patches do the following:
1. Wake the flushers when kswapd sees a lump of dirty pages. It's
possible to be below the dirty background limit and still have cache
velocity push them through the LRU. So start a-flushin'.
2. Let kswapd only write pages that have been rotated twice. This makes
sure we really tried to get all the clean pages on the inactive list
before resorting to horrible LRU-order writeback.
3. Move rotating dirty pages off the inactive list. Instead of churning
or waiting on page writeback, we'll go after clean active cache. This
might lead to thrashing, but in this state memory demand outstrips IO
speed anyway, and reads are faster than writes.
Mel backported the series to 4.10-rc5 with one minor conflict and ran a
couple of tests on it. Mix of read/write random workload didn't show
anything interesting. Write-only database didn't show much difference
in performance but there were slight reductions in IO -- probably in the
noise.
simoop did show big differences although not as big as Mel expected.
This is Chris Mason's workload that similate the VM activity of hadoop.
Mel won't go through the full details but over the samples measured
during an hour it reported
4.10.0-rc5 4.10.0-rc5
vanilla johannes-v1r1
Amean p50-Read 21346531.56 ( 0.00%) 21697513.24 ( -1.64%)
Amean p95-Read 24700518.40 ( 0.00%) 25743268.98 ( -4.22%)
Amean p99-Read 27959842.13 ( 0.00%) 28963271.11 ( -3.59%)
Amean p50-Write 1138.04 ( 0.00%) 989.82 ( 13.02%)
Amean p95-Write 1106643.48 ( 0.00%) 12104.00 ( 98.91%)
Amean p99-Write 1569213.22 ( 0.00%) 36343.38 ( 97.68%)
Amean p50-Allocation 85159.82 ( 0.00%) 79120.70 ( 7.09%)
Amean p95-Allocation 204222.58 ( 0.00%) 129018.43 ( 36.82%)
Amean p99-Allocation 278070.04 ( 0.00%) 183354.43 ( 34.06%)
Amean final-p50-Read 21266432.00 ( 0.00%) 21921792.00 ( -3.08%)
Amean final-p95-Read 24870912.00 ( 0.00%) 26116096.00 ( -5.01%)
Amean final-p99-Read 28147712.00 ( 0.00%) 29523968.00 ( -4.89%)
Amean final-p50-Write 1130.00 ( 0.00%) 977.00 ( 13.54%)
Amean final-p95-Write 1033216.00 ( 0.00%) 2980.00 ( 99.71%)
Amean final-p99-Write 1517568.00 ( 0.00%) 32672.00 ( 97.85%)
Amean final-p50-Allocation 86656.00 ( 0.00%) 78464.00 ( 9.45%)
Amean final-p95-Allocation 211712.00 ( 0.00%) 116608.00 ( 44.92%)
Amean final-p99-Allocation 287232.00 ( 0.00%) 168704.00 ( 41.27%)
The latencies are actually completely horrific in comparison to 4.4 (and
4.10-rc5 is worse than 4.9 according to historical data for reasons Mel
hasn't analysed yet).
Still, 95% of write latency (p95-write) is halved by the series and
allocation latency is way down. Direct reclaim activity is one fifth of
what it was according to vmstats. Kswapd activity is higher but this is
not necessarily surprising. Kswapd efficiency is unchanged at 99% (99%
of pages scanned were reclaimed) but direct reclaim efficiency went from
77% to 99%
In the vanilla kernel, 627MB of data was written back from reclaim
context. With the series, no data was written back. With or without
the patch, pages are being immediately reclaimed after writeback
completes. However, with the patch, only 1/8th of the pages are
reclaimed like this.
This patch (of 5):
We have an elaborate dirty/writeback throttling mechanism inside the
reclaim scanner, but for that to work the pages have to go through
shrink_page_list() and get counted for what they are. Otherwise, we
mess up the LRU order and don't match reclaim speed to writeback.
Especially during deactivation, there is never a reason to skip dirty
pages; nothing is even trying to write them out from there. Don't mess
up the LRU order for nothing, shuffle these pages along.
Link: http://lkml.kernel.org/r/20170123181641.23938-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Michal Hocko
|
abd6e8a7ac |
Revert "mm: bail out in shrink_inactive_list()"
This reverts commit
|
||
|
Michal Hocko
|
71ab6cfe88 |
mm, vmscan: consider eligible zones in get_scan_count
get_scan_count() considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan
In both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.
A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.
The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX at
maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.
Fix this by filtering out all the ineligible zones when calculating the
lru size for both paths and consider only sc->reclaim_idx zones.
The patch would need to be tweaked a bit to apply to 4.10 and older but
I will do that as soon as it hits the Linus tree in the next merge
window.
Link: http://lkml.kernel.org/r/20170117103702.28542-3-mhocko@kernel.org
Fixes:
|
||
|
Michal Hocko
|
fd53880373 |
mm, vmscan: cleanup lru size claculations
lruvec_lru_size returns the full size of the LRU list while we sometimes need a value reduced only to eligible zones (e.g. for lowmem requests). inactive_list_is_low is one such user. Later patches will add more of them. Add a new parameter to lruvec_lru_size and allow it filter out zones which are not eligible for the given context. Link: http://lkml.kernel.org/r/20170117103702.28542-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
f0958906cd |
mm, vmscan: do not count freed pages as PGDEACTIVATE
PGDEACTIVATE represents the number of pages moved from the active list to the inactive list. At least this sounds like the original motivation of the counter. move_active_pages_to_lru, however, counts pages which got freed in the mean time as deactivated as well. This is a very rare event and counting them as deactivation in itself is not harmful but it makes the code more convoluted than necessary - we have to count both all pages and those which are freed which is a bit confusing. After this patch the PGDEACTIVATE should have a slightly more clear semantic and only count those pages which are moved from the active to the inactive list which is a plus. Link: http://lkml.kernel.org/r/20170112211221.17636-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
dcec0b60a8 |
mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint
Currently we have tracepoints for both active and inactive LRU lists reclaim but we do not have any which would tell us why we we decided to age the active list. Without that it is quite hard to diagnose active/inactive lists balancing. Add mm_vmscan_inactive_list_is_low tracepoint to tell us this information. Link: http://lkml.kernel.org/r/20170104101942.4860-8-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
5bccd16657 |
mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint
mm_vmscan_lru_shrink_inactive will currently report the number of scanned and reclaimed pages. This doesn't give us an idea how the reclaim went except for the overall effectiveness though. Export and show other counters which will tell us why we couldn't reclaim some pages. - nr_dirty, nr_writeback, nr_congested and nr_immediate tells us how many pages are blocked due to IO - nr_activate tells us how many pages were moved to the active list - nr_ref_keep reports how many pages are kept on the LRU due to references (mostly for the file pages which are about to go for another round through the inactive list) - nr_unmap_fail - how many pages failed to unmap All these are rather low level so they might change in future but the tracepoint is already implementation specific so no tools should be depending on its stability. Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
3c710c1ad1 |
mm, vmscan: extract shrink_page_list reclaim counters into a struct
shrink_page_list returns quite some counters back to its caller. Extract the existing 5 into struct reclaim_stat because this makes the code easier to follow and also allows further counters to be returned. While we are at it, make all of them unsigned rather than unsigned long as we do not really need full 64b for them (we never scan more than SWAP_CLUSTER_MAX pages at once). This should reduce some stack space. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20170104101942.4860-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
32b3f2974a |
mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint
mm_vmscan_lru_isolate currently prints only whether the LRU we isolate from is file or anonymous but we do not know which LRU this is. It is useful to know whether the list is active or inactive, since we are using the same function to isolate pages from both of them and it's hard to distinguish otherwise. Link: http://lkml.kernel.org/r/20170104101942.4860-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
1265e3a69f |
mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate
mm_vmscan_lru_isolate shows the number of requested, scanned and taken pages. This is mostly OK but on 32b systems the number of scanned pages is quite misleading because it includes both the scanned and skipped pages. Moreover the skipped part is scaled based on the number of taken pages. Let's report the exact numbers without any additional logic and add the number of skipped pages. This should make the reported data much more easier to interpret. Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
9d998b4f1e |
mm, vmscan: add active list aging tracepoint
Our reclaim process has several tracepoints to tell us more about how things are progressing. We are, however, missing a tracepoint to track active list aging. Introduce mm_vmscan_lru_shrink_active which reports the number of - nr_taken is number of isolated pages from the active list - nr_referenced pages which tells us that we are hitting referenced pages which are deactivated. If this is a large part of the reported nr_deactivated pages then we might be hitting into the active list too early because they might be still part of the working set. This might help to debug performance issues. - nr_active pages which tells us how many pages are kept on the active list - mostly exec file backed pages. A high number can indicate that we might be trashing on executables. [mhocko@suse.com: update] Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
b4536f0c82 |
mm, memcg: fix the active list aging for lowmem requests when memcg is enabled
Nils Holland and Klaus Ethgen have reported unexpected OOM killer invocations with 32b kernel starting with 4.8 kernels kworker/u4:5 invoked oom-killer: gfp_mask=0x2400840(GFP_NOFS|__GFP_NOFAIL), nodemask=0, order=0, oom_score_adj=0 kworker/u4:5 cpuset=/ mems_allowed=0 CPU: 1 PID: 2603 Comm: kworker/u4:5 Not tainted 4.9.0-gentoo #2 [...] Mem-Info: active_anon:58685 inactive_anon:90 isolated_anon:0 active_file:274324 inactive_file:281962 isolated_file:0 unevictable:0 dirty:649 writeback:0 unstable:0 slab_reclaimable:40662 slab_unreclaimable:17754 mapped:7382 shmem:202 pagetables:351 bounce:0 free:206736 free_pcp:332 free_cma:0 Node 0 active_anon:234740kB inactive_anon:360kB active_file:1097296kB inactive_file:1127848kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:29528kB dirty:2596kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 184320kB anon_thp: 808kB writeback_tmp:0kB unstable:0kB pages_scanned:0 all_unreclaimable? no DMA free:3952kB min:788kB low:984kB high:1180kB active_anon:0kB inactive_anon:0kB active_file:7316kB inactive_file:0kB unevictable:0kB writepending:96kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:3200kB slab_unreclaimable:1408kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 813 3474 3474 Normal free:41332kB min:41368kB low:51708kB high:62048kB active_anon:0kB inactive_anon:0kB active_file:532748kB inactive_file:44kB unevictable:0kB writepending:24kB present:897016kB managed:836248kB mlocked:0kB slab_reclaimable:159448kB slab_unreclaimable:69608kB kernel_stack:1112kB pagetables:1404kB bounce:0kB free_pcp:528kB local_pcp:340kB free_cma:0kB lowmem_reserve[]: 0 0 21292 21292 HighMem free:781660kB min:512kB low:34356kB high:68200kB active_anon:234740kB inactive_anon:360kB active_file:557232kB inactive_file:1127804kB unevictable:0kB writepending:2592kB present:2725384kB managed:2725384kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:800kB local_pcp:608kB free_cma:0kB the oom killer is clearly pre-mature because there there is still a lot of page cache in the zone Normal which should satisfy this lowmem request. Further debugging has shown that the reclaim cannot make any forward progress because the page cache is hidden in the active list which doesn't get rotated because inactive_list_is_low is not memcg aware. The code simply subtracts per-zone highmem counters from the respective memcg's lru sizes which doesn't make any sense. We can simply end up always seeing the resulting active and inactive counts 0 and return false. This issue is not limited to 32b kernels but in practice the effect on systems without CONFIG_HIGHMEM would be much harder to notice because we do not invoke the OOM killer for allocations requests targeting < ZONE_NORMAL. Fix the issue by tracking per zone lru page counts in mem_cgroup_per_node and subtract per-memcg highmem counts when memcg is enabled. Introduce helper lruvec_zone_lru_size which redirects to either zone counters or mem_cgroup_get_zone_lru_size when appropriate. We are losing empty LRU but non-zero lru size detection introduced by |
||
|
Linus Torvalds
|
e34bac726d |
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton: - various misc bits - most of MM (quite a lot of MM material is awaiting the merge of linux-next dependencies) - kasan - printk updates - procfs updates - MAINTAINERS - /lib updates - checkpatch updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (123 commits) init: reduce rootwait polling interval time to 5ms binfmt_elf: use vmalloc() for allocation of vma_filesz checkpatch: don't emit unified-diff error for rename-only patches checkpatch: don't check c99 types like uint8_t under tools checkpatch: avoid multiple line dereferences checkpatch: don't check .pl files, improve absolute path commit log test scripts/checkpatch.pl: fix spelling checkpatch: don't try to get maintained status when --no-tree is given lib/ida: document locking requirements a bit better lib/rbtree.c: fix typo in comment of ____rb_erase_color lib/Kconfig.debug: make CONFIG_STRICT_DEVMEM depend on CONFIG_DEVMEM MAINTAINERS: add drm and drm/i915 irc channels MAINTAINERS: add "C:" for URI for chat where developers hang out MAINTAINERS: add drm and drm/i915 bug filing info MAINTAINERS: add "B:" for URI where to file bugs get_maintainer: look for arbitrary letter prefixes in sections printk: add Kconfig option to set default console loglevel printk/sound: handle more message headers printk/btrfs: handle more message headers printk/kdb: handle more message headers ... |
||
|
Linus Torvalds
|
e71c3978d6 |
Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull smp hotplug updates from Thomas Gleixner: "This is the final round of converting the notifier mess to the state machine. The removal of the notifiers and the related infrastructure will happen around rc1, as there are conversions outstanding in other trees. The whole exercise removed about 2000 lines of code in total and in course of the conversion several dozen bugs got fixed. The new mechanism allows to test almost every hotplug step standalone, so usage sites can exercise all transitions extensively. There is more room for improvement, like integrating all the pointlessly different architecture mechanisms of synchronizing, setting cpus online etc into the core code" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) tracing/rb: Init the CPU mask on allocation soc/fsl/qbman: Convert to hotplug state machine soc/fsl/qbman: Convert to hotplug state machine zram: Convert to hotplug state machine KVM/PPC/Book3S HV: Convert to hotplug state machine arm64/cpuinfo: Convert to hotplug state machine arm64/cpuinfo: Make hotplug notifier symmetric mm/compaction: Convert to hotplug state machine iommu/vt-d: Convert to hotplug state machine mm/zswap: Convert pool to hotplug state machine mm/zswap: Convert dst-mem to hotplug state machine mm/zsmalloc: Convert to hotplug state machine mm/vmstat: Convert to hotplug state machine mm/vmstat: Avoid on each online CPU loops mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead() tracing/rb: Convert to hotplug state machine oprofile/nmi timer: Convert to hotplug state machine net/iucv: Use explicit clean up labels in iucv_init() x86/pci/amd-bus: Convert to hotplug state machine x86/oprofile/nmi: Convert to hotplug state machine ... |
||
|
Shaohua Li
|
5f33a0803b |
mm/vmscan.c: set correct defer count for shrinker
Our system uses significantly more slab memory with memcg enabled with the latest kernel. With 3.10 kernel, slab uses 2G memory, while with 4.6 kernel, 6G memory is used. The shrinker has problem. Let's see we have two memcg for one shrinker. In do_shrink_slab: 1. Check cg1. nr_deferred = 0, assume total_scan = 700. batch size is 1024, then no memory is freed. nr_deferred = 700 2. Check cg2. nr_deferred = 700. Assume freeable = 20, then total_scan = 10 or 40. Let's assume it's 10. No memory is freed. nr_deferred = 10. The deferred share of cg1 is lost in this case. kswapd will free no memory even run above steps again and again. The fix makes sure one memcg's deferred share isn't lost. Link: http://lkml.kernel.org/r/2414be961b5d25892060315fbb56bb19d81d0c07.1476227351.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
bd041733c9 |
mm, vmscan: add cond_resched() into shrink_node_memcg()
Boris Zhmurov has reported RCU stalls during the kswapd reclaim:
INFO: rcu_sched detected stalls on CPUs/tasks:
23-...: (22 ticks this GP) idle=92f/140000000000000/0 softirq=2638404/2638404 fqs=23
(detected by 4, t=6389 jiffies, g=786259, c=786258, q=42115)
Task dump for CPU 23:
kswapd1 R running task 0 148 2 0x00000008
Call Trace:
shrink_node+0xd2/0x2f0
kswapd+0x2cb/0x6a0
mem_cgroup_shrink_node+0x160/0x160
kthread+0xbd/0xe0
__switch_to+0x1fa/0x5c0
ret_from_fork+0x1f/0x40
kthread_create_on_node+0x180/0x180
a closer code inspection has shown that we might indeed miss all the
scheduling points in the reclaim path if no pages can be isolated from
the LRU list. This is a pathological case but other reports from Donald
Buczek have shown that we might indeed hit such a path:
clusterd-989 [009] .... 118023.654491: mm_vmscan_direct_reclaim_end: nr_reclaimed=193
kswapd1-86 [001] dN.. 118023.987475: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239830 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.320968: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239844 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.654375: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239858 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.987036: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239872 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.319651: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239886 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.652248: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239900 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.984870: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239914 nr_taken=0 file=1
[...]
kswapd1-86 [001] dN.. 118084.274403: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4241133 nr_taken=0 file=1
this is minute long snapshot which didn't take a single page from the
LRU. It is not entirely clear why only 1303 pages have been scanned
during that time (maybe there was a heavy IRQ activity interfering).
In any case it looks like we can really hit long periods without
scheduling on non preemptive kernels so an explicit cond_resched() in
shrink_node_memcg which is independent on the reclaim operation is due.
Link: http://lkml.kernel.org/r/20161202095841.16648-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Boris Zhmurov <bb@kernelpanic.ru>
Tested-by: Boris Zhmurov <bb@kernelpanic.ru>
Reported-by: Donald Buczek <buczek@molgen.mpg.de>
Reported-by: "Christopher S. Aker" <caker@theshore.net>
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Sebastian Andrzej Siewior
|
517bbed906 |
mm/vmscan: Convert to hotplug state machine
Install the callbacks via the state machine. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161103145021.28528-8-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
||
|
Johannes Weiner
|
89a2848381 |
mm: memcontrol: do not recurse in direct reclaim
On 4.0, we saw a stack corruption from a page fault entering direct memory cgroup reclaim, calling into btrfs_releasepage(), which then tried to allocate an extent and recursed back into a kmem charge ad nauseam: [...] btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 memcg_charge_kmem+0x40/0x80 new_slab+0x2d9/0x5a0 __slab_alloc+0x2fd/0x44f kmem_cache_alloc+0x193/0x1e0 alloc_extent_state+0x21/0xc0 __clear_extent_bit+0x2b5/0x400 try_release_extent_mapping+0x1a3/0x220 __btrfs_releasepage+0x31/0x70 btrfs_releasepage+0x2c/0x30 try_to_release_page+0x32/0x50 shrink_page_list+0x6da/0x7a0 shrink_inactive_list+0x1e5/0x510 shrink_lruvec+0x605/0x7f0 shrink_zone+0xee/0x320 do_try_to_free_pages+0x174/0x440 try_to_free_mem_cgroup_pages+0xa7/0x130 try_charge+0x17b/0x830 mem_cgroup_try_charge+0x65/0x1c0 handle_mm_fault+0x117f/0x1510 __do_page_fault+0x177/0x420 do_page_fault+0xc/0x10 page_fault+0x22/0x30 On later kernels, kmem charging is opt-in rather than opt-out, and that particular kmem allocation in btrfs_releasepage() is no longer being charged and won't recurse and overrun the stack anymore. But it's not impossible for an accounted allocation to happen from the memcg direct reclaim context, and we needed to reproduce this crash many times before we even got a useful stack trace out of it. Like other direct reclaimers, mark tasks in memcg reclaim PF_MEMALLOC to avoid recursing into any other form of direct reclaim. Then let recursive charges from PF_MEMALLOC contexts bypass the cgroup limit. Link: http://lkml.kernel.org/r/20161025141050.GA13019@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Aneesh Kumar K.V
|
c9634cf012 |
mm: use zonelist name instead of using hardcoded index
Use the existing enums instead of hardcoded index when looking at the zonelist. This makes it more readable. No functionality change by this patch. Link: http://lkml.kernel.org/r/1472227078-24852-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
bf48438354 |
mm, vmscan: get rid of throttle_vm_writeout
throttle_vm_writeout() was introduced back in 2005 to fix OOMs caused by
excessive pageout activity during the reclaim. Too many pages could be
put under writeback therefore LRUs would be full of unreclaimable pages
until the IO completes and in turn the OOM killer could be invoked.
There have been some important changes introduced since then in the
reclaim path though. Writers are throttled by balance_dirty_pages when
initiating the buffered IO and later during the memory pressure, the
direct reclaim is throttled by wait_iff_congested if the node is
considered congested by dirty pages on LRUs and the underlying bdi is
congested by the queued IO. The kswapd is throttled as well if it
encounters pages marked for immediate reclaim or under writeback which
signals that that there are too many pages under writeback already.
Finally should_reclaim_retry does congestion_wait if the reclaim cannot
make any progress and there are too many dirty/writeback pages.
Another important aspect is that we do not issue any IO from the direct
reclaim context anymore. In a heavy parallel load this could queue a
lot of IO which would be very scattered and thus unefficient which would
just make the problem worse.
This three mechanisms should throttle and keep the amount of IO in a
steady state even under heavy IO and memory pressure so yet another
throttling point doesn't really seem helpful. Quite contrary, Mikulas
Patocka has reported that swap backed by dm-crypt doesn't work properly
because the swapout IO cannot make sufficient progress as the writeout
path depends on dm_crypt worker which has to allocate memory to perform
the encryption. In order to guarantee a forward progress it relies on
the mempool allocator. mempool_alloc(), however, prefers to use the
underlying (usually page) allocator before it grabs objects from the
pool. Such an allocation can dive into the memory reclaim and
consequently to throttle_vm_writeout. If there are too many dirty or
pages under writeback it will get throttled even though it is in fact a
flusher to clear pending pages.
kworker/u4:0 D ffff88003df7f438 10488 6 2 0x00000000
Workqueue: kcryptd kcryptd_crypt [dm_crypt]
Call Trace:
schedule+0x3c/0x90
schedule_timeout+0x1d8/0x360
io_schedule_timeout+0xa4/0x110
congestion_wait+0x86/0x1f0
throttle_vm_writeout+0x44/0xd0
shrink_zone_memcg+0x613/0x720
shrink_zone+0xe0/0x300
do_try_to_free_pages+0x1ad/0x450
try_to_free_pages+0xef/0x300
__alloc_pages_nodemask+0x879/0x1210
alloc_pages_current+0xa1/0x1f0
new_slab+0x2d7/0x6a0
___slab_alloc+0x3fb/0x5c0
__slab_alloc+0x51/0x90
kmem_cache_alloc+0x27b/0x310
mempool_alloc_slab+0x1d/0x30
mempool_alloc+0x91/0x230
bio_alloc_bioset+0xbd/0x260
kcryptd_crypt+0x114/0x3b0 [dm_crypt]
Let's just drop throttle_vm_writeout altogether. It is not very much
helpful anymore.
I have tried to test a potential writeback IO runaway similar to the one
described in the original patch which has introduced that [1]. Small
virtual machine (512MB RAM, 4 CPUs, 2G of swap space and disk image on a
rather slow NFS in a sync mode on the host) with 8 parallel writers each
writing 1G worth of data. As soon as the pagecache fills up and the
direct reclaim hits then I start anon memory consumer in a loop
(allocating 300M and exiting after populating it) in the background to
make the memory pressure even stronger as well as to disrupt the steady
state for the IO. The direct reclaim is throttled because of the
congestion as well as kswapd hitting congestion_wait due to nr_immediate
but throttle_vm_writeout doesn't ever trigger the sleep throughout the
test. Dirty+writeback are close to nr_dirty_threshold with some
fluctuations caused by the anon consumer.
[1] https://www2.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc1/2.6.9-rc1-mm3/broken-out/vm-pageout-throttling.patch
Link: http://lkml.kernel.org/r/1471171473-21418-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: NeilBrown <neilb@suse.com>
Cc: Ondrej Kozina <okozina@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Vlastimil Babka
|
fdd4c6149a |
mm, vmscan: make compaction_ready() more accurate and readable
The compaction_ready() is used during direct reclaim for costly order allocations to skip reclaim for zones where compaction should be attempted instead. It's combining the standard compaction_suitable() check with its own watermark check based on high watermark with extra gap, and the result is confusing at best. This patch attempts to better structure and document the checks involved. First, compaction_suitable() can determine that the allocation should either succeed already, or that compaction doesn't have enough free pages to proceed. The third possibility is that compaction has enough free pages, but we still decide to reclaim first - unless we are already above the high watermark with gap. This does not mean that the reclaim will actually reach this watermark during single attempt, this is rather an over-reclaim protection. So document the code as such. The check for compaction_deferred() is removed completely, as it in fact had no proper role here. The result after this patch is mainly a less confusing code. We also skip some over-reclaim in cases where the allocation should already succed. Link: http://lkml.kernel.org/r/20160810091226.6709-12-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vlastimil Babka
|
9861a62c33 |
mm, compaction: create compact_gap wrapper
Compaction uses a watermark gap of (2UL << order) pages at various places and it's not immediately obvious why. Abstract it through a compact_gap() wrapper to create a single place with a thorough explanation. [vbabka@suse.cz: clarify the comment of compact_gap()] Link: http://lkml.kernel.org/r/7b6aed1f-fdf8-2063-9ff4-bbe4de712d37@suse.cz Link: http://lkml.kernel.org/r/20160810091226.6709-9-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vlastimil Babka
|
cf378319d3 |
mm, compaction: rename COMPACT_PARTIAL to COMPACT_SUCCESS
COMPACT_PARTIAL has historically meant that compaction returned after doing some work without fully compacting a zone. It however didn't distinguish if compaction terminated because it succeeded in creating the requested high-order page. This has changed recently and now we only return COMPACT_PARTIAL when compaction thinks it succeeded, or the high-order watermark check in compaction_suitable() passes and no compaction needs to be done. So at this point we can make the return value clearer by renaming it to COMPACT_SUCCESS. The next patch will remove some redundant tests for success where compaction just returned COMPACT_SUCCESS. Link: http://lkml.kernel.org/r/20160810091226.6709-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Hugh Dickins
|
b385d21f27 |
mm: delete unnecessary and unsafe init_tlb_ubc()
init_tlb_ubc() looked unnecessary to me: tlb_ubc is statically
initialized with zeroes in the init_task, and copied from parent to
child while it is quiescent in arch_dup_task_struct(); so I went to
delete it.
But inserted temporary debug WARN_ONs in place of init_tlb_ubc() to
check that it was always empty at that point, and found them firing:
because memcg reclaim can recurse into global reclaim (when allocating
biosets for swapout in my case), and arrive back at the init_tlb_ubc()
in shrink_node_memcg().
Resetting tlb_ubc.flush_required at that point is wrong: if the upper
level needs a deferred TLB flush, but the lower level turns out not to,
we miss a TLB flush. But fortunately, that's the only part of the
protocol that does not nest: with the initialization removed, cpumask
collects bits from upper and lower levels, and flushes TLB when needed.
Fixes:
|
||
|
Mel Gorman
|
6aa303defb |
mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator
Firmware Assisted Dump (FA_DUMP) on ppc64 reserves substantial amounts
of memory when booting a secondary kernel. Srikar Dronamraju reported
that multiple nodes may have no memory managed by the buddy allocator
but still return true for populated_zone().
Commit
|
||
|
Vladimir Davydov
|
b5afba2974 |
mm: vmscan: fix memcg-aware shrinkers not called on global reclaim
We must call shrink_slab() for each memory cgroup on both global and
memcg reclaim in shrink_node_memcg(). Commit d71df22b55099 accidentally
changed that so that now shrink_slab() is only called with memcg != NULL
on memcg reclaim. As a result, memcg-aware shrinkers (including
dentry/inode) are never invoked on global reclaim. Fix that.
Fixes:
|
||
|
Minchan Kim
|
91dcade47a |
mm: bail out in shrink_inactive_list()
With node-lru, if there are enough reclaimable pages in highmem but nothing in lowmem, VM can try to shrink inactive list although the requested zone is lowmem. The problem is that if the inactive list is full of highmem pages then a direct reclaimer searching for a lowmem page waste CPU scanning uselessly. It just burns out CPU. Even, many direct reclaimers are stalled by too_many_isolated if lots of parallel reclaimer are going on although there are no reclaimable memory in inactive list. I tried the experiment 4 times in 32bit 2G 8 CPU KVM machine to get elapsed time. hackbench 500 process 2 = Old = 1st: 289s 2nd: 310s 3rd: 112s 4th: 272s = Now = 1st: 31s 2nd: 132s 3rd: 162s 4th: 50s. [akpm@linux-foundation.org: fixes per Mel] Link: http://lkml.kernel.org/r/1469433119-1543-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
d7f05528ee |
mm, vmscan: account for skipped pages as a partial scan
Page reclaim determines whether a pgdat is unreclaimable by examining how many pages have been scanned since a page was freed and comparing that to the LRU sizes. Skipped pages are not reclaim candidates but contribute to scanned. This can prematurely mark a pgdat as unreclaimable and trigger an OOM kill. This patch accounts for skipped pages as a partial scan so that an unreclaimable pgdat will still be marked as such but by scaling the cost of a skip, it'll avoid the pgdat being marked prematurely. Link: http://lkml.kernel.org/r/1469110261-7365-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
f8d1a31163 |
mm: consider whether to decivate based on eligible zones inactive ratio
Minchan Kim reported that with per-zone lru state it was possible to
identify that a normal zone with 8^M anonymous pages could trigger OOM
with non-atomic order-0 allocations as all pages in the zone were in the
active list.
gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0
Call Trace:
__alloc_pages_nodemask+0xe52/0xe60
? new_slab+0x39c/0x3b0
new_slab+0x39c/0x3b0
___slab_alloc.constprop.87+0x6da/0x840
? __alloc_skb+0x3c/0x260
? enqueue_task_fair+0x73/0xbf0
? poll_select_copy_remaining+0x140/0x140
__slab_alloc.isra.81.constprop.86+0x40/0x6d
? __alloc_skb+0x3c/0x260
kmem_cache_alloc+0x22c/0x260
? __alloc_skb+0x3c/0x260
__alloc_skb+0x3c/0x260
alloc_skb_with_frags+0x4e/0x1a0
sock_alloc_send_pskb+0x16a/0x1b0
? wait_for_unix_gc+0x31/0x90
unix_stream_sendmsg+0x28d/0x340
sock_sendmsg+0x2d/0x40
sock_write_iter+0x6c/0xc0
__vfs_write+0xc0/0x120
vfs_write+0x9b/0x1a0
? __might_fault+0x49/0xa0
SyS_write+0x44/0x90
do_fast_syscall_32+0xa6/0x1e0
Mem-Info:
active_anon:101103 inactive_anon:102219 isolated_anon:0
active_file:503 inactive_file:544 isolated_file:0
unevictable:0 dirty:0 writeback:34 unstable:0
slab_reclaimable:6298 slab_unreclaimable:74669
mapped:863 shmem:0 pagetables:100998 bounce:0
free:23573 free_pcp:1861 free_cma:0
Node 0 active_anon:404412kB inactive_anon:409040kB active_file:2012kB inactive_file:2176kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:3452kB dirty:0kB writeback:136kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1320845 all_unreclaimable? yes
DMA free:3296kB min:68kB low:84kB high:100kB active_anon:5540kB inactive_anon:0kB active_file:0kB inactive_file:0kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:248kB slab_unreclaimable:2628kB kernel_stack:792kB pagetables:2316kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 809 1965 1965
Normal free:3600kB min:3604kB low:4504kB high:5404kB active_anon:86304kB inactive_anon:0kB active_file:160kB inactive_file:376kB present:897016kB managed:858524kB mlocked:0kB slab_reclaimable:24944kB slab_unreclaimable:296048kB kernel_stack:163832kB pagetables:35892kB bounce:0kB free_pcp:3076kB local_pcp:656kB free_cma:0kB
lowmem_reserve[]: 0 0 9247 9247
HighMem free:86156kB min:512kB low:1796kB high:3080kB active_anon:312852kB inactive_anon:410024kB active_file:1924kB inactive_file:2012kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:365784kB bounce:0kB free_pcp:3868kB local_pcp:720kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
DMA: 8*4kB (UM) 8*8kB (UM) 4*16kB (M) 2*32kB (UM) 2*64kB (UM) 1*128kB (M) 3*256kB (UME) 2*512kB (UE) 1*1024kB (E) 0*2048kB 0*4096kB = 3296kB
Normal: 240*4kB (UME) 160*8kB (UME) 23*16kB (ME) 3*32kB (UE) 3*64kB (UME) 2*128kB (ME) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3408kB
HighMem: 10942*4kB (UM) 3102*8kB (UM) 866*16kB (UM) 76*32kB (UM) 11*64kB (UM) 4*128kB (UM) 1*256kB (M) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 86344kB
Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
54409 total pagecache pages
53215 pages in swap cache
Swap cache stats: add 300982, delete 247765, find 157978/226539
Free swap = 3803244kB
Total swap = 4192252kB
524186 pages RAM
295934 pages HighMem/MovableOnly
9642 pages reserved
0 pages cma reserved
The problem is due to the active deactivation logic in
inactive_list_is_low:
Node 0 active_anon:404412kB inactive_anon:409040kB
IOW, (inactive_anon of node * inactive_ratio > active_anon of node) due
to highmem anonymous stat so VM never deactivates normal zone's
anonymous pages.
This patch is a modified version of Minchan's original solution but
based upon it. The problem with Minchan's patch is that any low zone
with an imbalanced list could force a rotation.
In this patch, a zone-constrained global reclaim will rotate the list if
the inactive/active ratio of all eligible zones needs to be corrected.
It is possible that higher zone pages will be initially rotated
prematurely but this is the safer choice to maintain overall LRU age.
Link: http://lkml.kernel.org/r/20160722090929.GJ10438@techsingularity.net
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Mel Gorman
|
5a1c84b404 |
mm: remove reclaim and compaction retry approximations
If per-zone LRU accounting is available then there is no point approximating whether reclaim and compaction should retry based on pgdat statistics. This is effectively a revert of "mm, vmstat: remove zone and node double accounting by approximating retries" with the difference that inactive/active stats are still available. This preserves the history of why the approximation was retried and why it had to be reverted to handle OOM kills on 32-bit systems. Link: http://lkml.kernel.org/r/1469110261-7365-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
71c799f498 |
mm: add per-zone lru list stat
When I did stress test with hackbench, I got OOM message frequently which didn't ever happen in zone-lru. gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0 .. .. __alloc_pages_nodemask+0xe52/0xe60 ? new_slab+0x39c/0x3b0 new_slab+0x39c/0x3b0 ___slab_alloc.constprop.87+0x6da/0x840 ? __alloc_skb+0x3c/0x260 ? _raw_spin_unlock_irq+0x27/0x60 ? trace_hardirqs_on_caller+0xec/0x1b0 ? finish_task_switch+0xa6/0x220 ? poll_select_copy_remaining+0x140/0x140 __slab_alloc.isra.81.constprop.86+0x40/0x6d ? __alloc_skb+0x3c/0x260 kmem_cache_alloc+0x22c/0x260 ? __alloc_skb+0x3c/0x260 __alloc_skb+0x3c/0x260 alloc_skb_with_frags+0x4e/0x1a0 sock_alloc_send_pskb+0x16a/0x1b0 ? wait_for_unix_gc+0x31/0x90 ? alloc_set_pte+0x2ad/0x310 unix_stream_sendmsg+0x28d/0x340 sock_sendmsg+0x2d/0x40 sock_write_iter+0x6c/0xc0 __vfs_write+0xc0/0x120 vfs_write+0x9b/0x1a0 ? __might_fault+0x49/0xa0 SyS_write+0x44/0x90 do_fast_syscall_32+0xa6/0x1e0 sysenter_past_esp+0x45/0x74 Mem-Info: active_anon:104698 inactive_anon:105791 isolated_anon:192 active_file:433 inactive_file:283 isolated_file:22 unevictable:0 dirty:0 writeback:296 unstable:0 slab_reclaimable:6389 slab_unreclaimable:78927 mapped:474 shmem:0 pagetables:101426 bounce:0 free:10518 free_pcp:334 free_cma:0 Node 0 active_anon:418792kB inactive_anon:423164kB active_file:1732kB inactive_file:1132kB unevictable:0kB isolated(anon):768kB isolated(file):88kB mapped:1896kB dirty:0kB writeback:1184kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1478632 all_unreclaimable? yes DMA free:3304kB min:68kB low:84kB high:100kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:4088kB kernel_stack:0kB pagetables:2480kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 809 1965 1965 Normal free:3436kB min:3604kB low:4504kB high:5404kB present:897016kB managed:858460kB mlocked:0kB slab_reclaimable:25556kB slab_unreclaimable:311712kB kernel_stack:164608kB pagetables:30844kB bounce:0kB free_pcp:620kB local_pcp:104kB free_cma:0kB lowmem_reserve[]: 0 0 9247 9247 HighMem free:33808kB min:512kB low:1796kB high:3080kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:372252kB bounce:0kB free_pcp:428kB local_pcp:72kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 2*4kB (UM) 2*8kB (UM) 0*16kB 1*32kB (U) 1*64kB (U) 2*128kB (UM) 1*256kB (U) 1*512kB (M) 0*1024kB 1*2048kB (U) 0*4096kB = 3192kB Normal: 33*4kB (MH) 79*8kB (ME) 11*16kB (M) 4*32kB (M) 2*64kB (ME) 2*128kB (EH) 7*256kB (EH) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3244kB HighMem: 2590*4kB (UM) 1568*8kB (UM) 491*16kB (UM) 60*32kB (UM) 6*64kB (M) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 33064kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 25121 total pagecache pages 24160 pages in swap cache Swap cache stats: add 86371, delete 62211, find 42865/60187 Free swap = 4015560kB Total swap = 4192252kB 524186 pages RAM 295934 pages HighMem/MovableOnly 9658 pages reserved 0 pages cma reserved The order-0 allocation for normal zone failed while there are a lot of reclaimable memory(i.e., anonymous memory with free swap). I wanted to analyze the problem but it was hard because we removed per-zone lru stat so I couldn't know how many of anonymous memory there are in normal/dma zone. When we investigate OOM problem, reclaimable memory count is crucial stat to find a problem. Without it, it's hard to parse the OOM message so I believe we should keep it. With per-zone lru stat, gfp_mask=0x26004c0(GFP_KERNEL|__GFP_REPEAT|__GFP_NOTRACK), order=0 Mem-Info: active_anon:101103 inactive_anon:102219 isolated_anon:0 active_file:503 inactive_file:544 isolated_file:0 unevictable:0 dirty:0 writeback:34 unstable:0 slab_reclaimable:6298 slab_unreclaimable:74669 mapped:863 shmem:0 pagetables:100998 bounce:0 free:23573 free_pcp:1861 free_cma:0 Node 0 active_anon:404412kB inactive_anon:409040kB active_file:2012kB inactive_file:2176kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:3452kB dirty:0kB writeback:136kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1320845 all_unreclaimable? yes DMA free:3296kB min:68kB low:84kB high:100kB active_anon:5540kB inactive_anon:0kB active_file:0kB inactive_file:0kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:248kB slab_unreclaimable:2628kB kernel_stack:792kB pagetables:2316kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 809 1965 1965 Normal free:3600kB min:3604kB low:4504kB high:5404kB active_anon:86304kB inactive_anon:0kB active_file:160kB inactive_file:376kB present:897016kB managed:858524kB mlocked:0kB slab_reclaimable:24944kB slab_unreclaimable:296048kB kernel_stack:163832kB pagetables:35892kB bounce:0kB free_pcp:3076kB local_pcp:656kB free_cma:0kB lowmem_reserve[]: 0 0 9247 9247 HighMem free:86156kB min:512kB low:1796kB high:3080kB active_anon:312852kB inactive_anon:410024kB active_file:1924kB inactive_file:2012kB present:1183736kB managed:1183736kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:365784kB bounce:0kB free_pcp:3868kB local_pcp:720kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 DMA: 8*4kB (UM) 8*8kB (UM) 4*16kB (M) 2*32kB (UM) 2*64kB (UM) 1*128kB (M) 3*256kB (UME) 2*512kB (UE) 1*1024kB (E) 0*2048kB 0*4096kB = 3296kB Normal: 240*4kB (UME) 160*8kB (UME) 23*16kB (ME) 3*32kB (UE) 3*64kB (UME) 2*128kB (ME) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3408kB HighMem: 10942*4kB (UM) 3102*8kB (UM) 866*16kB (UM) 76*32kB (UM) 11*64kB (UM) 4*128kB (UM) 1*256kB (M) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 86344kB Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB 54409 total pagecache pages 53215 pages in swap cache Swap cache stats: add 300982, delete 247765, find 157978/226539 Free swap = 3803244kB Total swap = 4192252kB 524186 pages RAM 295934 pages HighMem/MovableOnly 9642 pages reserved 0 pages cma reserved With that, we can see normal zone has a 86M reclaimable memory so we can know something goes wrong(I will fix the problem in next patch) in reclaim. [mgorman@techsingularity.net: rename zone LRU stats in /proc/vmstat] Link: http://lkml.kernel.org/r/20160725072300.GK10438@techsingularity.net Link: http://lkml.kernel.org/r/1469110261-7365-2-git-send-email-mgorman@techsingularity.net Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
785b99febb |
mm, vmscan: release/reacquire lru_lock on pgdat change
With node-lru, the locking is based on the pgdat. As Minchan pointed out, there is an opportunity to reduce LRU lock release/acquire in check_move_unevictable_pages by only changing lock on a pgdat change. [mgorman@techsingularity.net: remove double initialisation] Link: http://lkml.kernel.org/r/20160719074835.GC10438@techsingularity.net Link: http://lkml.kernel.org/r/1468853426-12858-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
22fecdf5e1 |
mm, vmscan: remove redundant check in shrink_zones()
As pointed out by Minchan Kim, shrink_zones() checks for populated zones in a zonelist but a zonelist can never contain unpopulated zones. While it's not related to the node-lru series, it can be cleaned up now. Link: http://lkml.kernel.org/r/1468853426-12858-2-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Suggested-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
7ee36a14f0 |
mm, vmscan: Update all zone LRU sizes before updating memcg
Minchan Kim reported setting the following warning on a 32-bit system although it can affect 64-bit systems. WARNING: CPU: 4 PID: 1322 at mm/memcontrol.c:998 mem_cgroup_update_lru_size+0x103/0x110 mem_cgroup_update_lru_size(f44b4000, 1, -7): zid 1 lru_size 1 but empty Modules linked in: CPU: 4 PID: 1322 Comm: cp Not tainted 4.7.0-rc4-mm1+ #143 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x76/0xaf __warn+0xea/0x110 ? mem_cgroup_update_lru_size+0x103/0x110 warn_slowpath_fmt+0x3b/0x40 mem_cgroup_update_lru_size+0x103/0x110 isolate_lru_pages.isra.61+0x2e2/0x360 shrink_active_list+0xac/0x2a0 ? __delay+0xe/0x10 shrink_node_memcg+0x53c/0x7a0 shrink_node+0xab/0x2a0 do_try_to_free_pages+0xc6/0x390 try_to_free_pages+0x245/0x590 LRU list contents and counts are updated separately. Counts are updated before pages are added to the LRU and updated after pages are removed. The warning above is from a check in mem_cgroup_update_lru_size that ensures that list sizes of zero are empty. The problem is that node-lru needs to account for highmem pages if CONFIG_HIGHMEM is set. One impact of the implementation is that the sizes are updated in multiple passes when pages from multiple zones were isolated. This happens whether HIGHMEM is set or not. When multiple zones are isolated, it's possible for a debugging check in memcg to be tripped. This patch forces all the zone counts to be updated before the memcg function is called. Link: http://lkml.kernel.org/r/1468588165-12461-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Tested-by: Minchan Kim <minchan@kernel.org> Reported-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
bca6759258 |
mm, vmstat: remove zone and node double accounting by approximating retries
The number of LRU pages, dirty pages and writeback pages must be
accounted for on both zones and nodes because of the reclaim retry
logic, compaction retry logic and highmem calculations all depending on
per-zone stats.
Many lowmem allocations are immune from OOM kill due to a check in
__alloc_pages_may_oom for (ac->high_zoneidx < ZONE_NORMAL) since commit
|
||
|
Mel Gorman
|
7cc30fcfd2 |
mm: vmstat: account per-zone stalls and pages skipped during reclaim
The vmstat allocstall was fairly useful in the general sense but node-based LRUs change that. It's important to know if a stall was for an address-limited allocation request as this will require skipping pages from other zones. This patch adds pgstall_* counters to replace allocstall. The sum of the counters will equal the old allocstall so it can be trivially recalculated. A high number of address-limited allocation requests may result in a lot of useless LRU scanning for suitable pages. As address-limited allocations require pages to be skipped, it's important to know how much useless LRU scanning took place so this patch adds pgskip* counters. This yields the following model 1. The number of address-space limited stalls can be accounted for (pgstall) 2. The amount of useless work required to reclaim the data is accounted (pgskip) 3. The total number of scans is available from pgscan_kswapd and pgscan_direct so from that the ratio of useful to useless scans can be calculated. [mgorman@techsingularity.net: s/pgstall/allocstall/] Link: http://lkml.kernel.org/r/1468404004-5085-3-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-33-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
e5146b12e2 |
mm, vmscan: add classzone information to tracepoints
This is convenient when tracking down why the skip count is high because it'll show what classzone kswapd woke up at and what zones are being isolated. Link: http://lkml.kernel.org/r/1467970510-21195-29-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
84c7a7771f |
mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit
The buffer_heads_over_limit limit in kswapd is inconsistent with direct reclaim behaviour. It may force an an attempt to reclaim from all zones and then not reclaim at all because higher zones were balanced than required by the original request. This patch will causes kswapd to consider reclaiming from all zones if buffer_heads_over_limit. However, if there are eligible zones for the allocation request that woke kswapd then no reclaim will occur even if buffer_heads_over_limit. This avoids kswapd over-reclaiming just because buffer_heads_over_limit. [mgorman@techsingularity.net: fix comment about buffer_heads_over_limit] Link: http://lkml.kernel.org/r/1468404004-5085-2-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-28-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
d9f21d426d |
mm, vmscan: avoid passing in `remaining' unnecessarily to prepare_kswapd_sleep()
As pointed out by Minchan Kim, the first call to prepare_kswapd_sleep() always passes in 0 for `remaining' and the second call can trivially check the parameter in advance. Suggested-by: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1467970510-21195-27-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
4f588331bd |
mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready
The scan_control structure has enough information available for compaction_ready() to make a decision. The classzone_idx manipulations in shrink_zones() are no longer necessary as the highest populated zone is no longer used to determine if shrink_slab should be called or not. [mgorman@techsingularity.net remove redundant check in shrink_zones()] Link: http://lkml.kernel.org/r/1468588165-12461-3-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-26-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
970a39a363 |
mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node
shrink_node receives all information it needs about classzone_idx from sc->reclaim_idx so remove the aliases. Link: http://lkml.kernel.org/r/1467970510-21195-25-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
a5f5f91da6 |
mm: convert zone_reclaim to node_reclaim
As reclaim is now per-node based, convert zone_reclaim to be node_reclaim. It is possible that a node will be reclaimed multiple times if it has multiple zones but this is unavoidable without caching all nodes traversed so far. The documentation and interface to userspace is the same from a configuration perspective and will will be similar in behaviour unless the node-local allocation requests were also limited to lower zones. Link: http://lkml.kernel.org/r/1467970510-21195-24-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
e1a556374a |
mm, vmscan: only wakeup kswapd once per node for the requested classzone
kswapd is woken when zones are below the low watermark but the wakeup decision is not taking the classzone into account. Now that reclaim is node-based, it is only required to wake kswapd once per node and only if all zones are unbalanced for the requested classzone. Note that one node might be checked multiple times if the zonelist is ordered by node because there is no cheap way of tracking what nodes have already been visited. For zone-ordering, each node should be checked only once. Link: http://lkml.kernel.org/r/1467970510-21195-22-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
c4a25635b6 |
mm: move vmscan writes and file write accounting to the node
As reclaim is now node-based, it follows that page write activity due to page reclaim should also be accounted for on the node. For consistency, also account page writes and page dirtying on a per-node basis. After this patch, there are a few remaining zone counters that may appear strange but are fine. NUMA stats are still per-zone as this is a user-space interface that tools consume. NR_MLOCK, NR_SLAB_*, NR_PAGETABLE, NR_KERNEL_STACK and NR_BOUNCE are all allocations that potentially pin low memory and cannot trivially be reclaimed on demand. This information is still useful for debugging a page allocation failure warning. Link: http://lkml.kernel.org/r/1467970510-21195-21-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
11fb998986 |
mm: move most file-based accounting to the node
There are now a number of accounting oddities such as mapped file pages being accounted for on the node while the total number of file pages are accounted on the zone. This can be coped with to some extent but it's confusing so this patch moves the relevant file-based accounted. Due to throttling logic in the page allocator for reliable OOM detection, it is still necessary to track dirty and writeback pages on a per-zone basis. [mgorman@techsingularity.net: fix NR_ZONE_WRITE_PENDING accounting] Link: http://lkml.kernel.org/r/1468404004-5085-5-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-20-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
50658e2e04 |
mm: move page mapped accounting to the node
Reclaim makes decisions based on the number of pages that are mapped but it's mixing node and zone information. Account NR_FILE_MAPPED and NR_ANON_PAGES pages on the node. Link: http://lkml.kernel.org/r/1467970510-21195-18-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
ef8f232799 |
mm, memcg: move memcg limit enforcement from zones to nodes
Memcg needs adjustment after moving LRUs to the node. Limits are tracked per memcg but the soft-limit excess is tracked per zone. As global page reclaim is based on the node, it is easy to imagine a situation where a zone soft limit is exceeded even though the memcg limit is fine. This patch moves the soft limit tree the node. Technically, all the variable names should also change but people are already familiar by the meaning of "mz" even if "mn" would be a more appropriate name now. Link: http://lkml.kernel.org/r/1467970510-21195-15-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
a9dd0a8310 |
mm, vmscan: make shrink_node decisions more node-centric
Earlier patches focused on having direct reclaim and kswapd use data that is node-centric for reclaiming but shrink_node() itself still uses too much zone information. This patch removes unnecessary zone-based information with the most important decision being whether to continue reclaim or not. Some memcg APIs are adjusted as a result even though memcg itself still uses some zone information. [mgorman@techsingularity.net: optimization] Link: http://lkml.kernel.org/r/1468588165-12461-2-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-14-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
86c79f6b54 |
mm: vmscan: do not reclaim from kswapd if there is any eligible zone
kswapd scans from highest to lowest for a zone that requires balancing. This was necessary when reclaim was per-zone to fairly age pages on lower zones. Now that we are reclaiming on a per-node basis, any eligible zone can be used and pages will still be aged fairly. This patch avoids reclaiming excessively unless buffer_heads are over the limit and it's necessary to reclaim from a higher zone than requested by the waker of kswapd to relieve low memory pressure. [hillf.zj@alibaba-inc.com: Force kswapd reclaim no more than needed] Link: http://lkml.kernel.org/r/1466518566-30034-12-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-13-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
6256c6b499 |
mm, vmscan: remove duplicate logic clearing node congestion and dirty state
Reclaim may stall if there is too much dirty or congested data on a node. This was previously based on zone flags and the logic for clearing the flags is in two places. As congestion/dirty tracking is now tracked on a per-node basis, we can remove some duplicate logic. Link: http://lkml.kernel.org/r/1467970510-21195-12-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
79dafcdca3 |
mm, vmscan: by default have direct reclaim only shrink once per node
Direct reclaim iterates over all zones in the zonelist and shrinking them but this is in conflict with node-based reclaim. In the default case, only shrink once per node. Link: http://lkml.kernel.org/r/1467970510-21195-11-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
38087d9b03 |
mm, vmscan: simplify the logic deciding whether kswapd sleeps
kswapd goes through some complex steps trying to figure out if it should stay awake based on the classzone_idx and the requested order. It is unnecessarily complex and passes in an invalid classzone_idx to balance_pgdat(). What matters most of all is whether a larger order has been requsted and whether kswapd successfully reclaimed at the previous order. This patch irons out the logic to check just that and the end result is less headache inducing. Link: http://lkml.kernel.org/r/1467970510-21195-10-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
31483b6ad2 |
mm, vmscan: remove balance gap
The balance gap was introduced to apply equal pressure to all zones when reclaiming for a higher zone. With node-based LRU, the need for the balance gap is removed and the code is dead so remove it. [vbabka@suse.cz: Also remove KSWAPD_ZONE_BALANCE_GAP_RATIO] Link: http://lkml.kernel.org/r/1467970510-21195-9-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
1d82de618d |
mm, vmscan: make kswapd reclaim in terms of nodes
Patch "mm: vmscan: Begin reclaiming pages on a per-node basis" started thinking of reclaim in terms of nodes but kswapd is still zone-centric. This patch gets rid of many of the node-based versus zone-based decisions. o A node is considered balanced when any eligible lower zone is balanced. This eliminates one class of age-inversion problem because we avoid reclaiming a newer page just because it's in the wrong zone o pgdat_balanced disappears because we now only care about one zone being balanced. o Some anomalies related to writeback and congestion tracking being based on zones disappear. o kswapd no longer has to take care to reclaim zones in the reverse order that the page allocator uses. o Most importantly of all, reclaim from node 0 with multiple zones will have similar aging and reclaiming characteristics as every other node. Link: http://lkml.kernel.org/r/1467970510-21195-8-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
f7b60926eb |
mm, vmscan: have kswapd only scan based on the highest requested zone
kswapd checks all eligible zones to see if they need balancing even if it was woken for a lower zone. This made sense when we reclaimed on a per-zone basis because we wanted to shrink zones fairly so avoid age-inversion problems. Ideally this is completely unnecessary when reclaiming on a per-node basis. In theory, there may still be anomalies when all requests are for lower zones and very old pages are preserved in higher zones but this should be the exceptional case. Link: http://lkml.kernel.org/r/1467970510-21195-7-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
b2e18757f2 |
mm, vmscan: begin reclaiming pages on a per-node basis
This patch makes reclaim decisions on a per-node basis. A reclaimer knows what zone is required by the allocation request and skips pages from higher zones. In many cases this will be ok because it's a GFP_HIGHMEM request of some description. On 64-bit, ZONE_DMA32 requests will cause some problems but 32-bit devices on 64-bit platforms are increasingly rare. Historically it would have been a major problem on 32-bit with big Highmem:Lowmem ratios but such configurations are also now rare and even where they exist, they are not encouraged. If it really becomes a problem, it'll manifest as very low reclaim efficiencies. Link: http://lkml.kernel.org/r/1467970510-21195-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
599d0c954f |
mm, vmscan: move LRU lists to node
This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
a52633d8e9 |
mm, vmscan: move lru_lock to the node
Node-based reclaim requires node-based LRUs and locking. This is a preparation patch that just moves the lru_lock to the node so later patches are easier to review. It is a mechanical change but note this patch makes contention worse because the LRU lock is hotter and direct reclaim and kswapd can contend on the same lock even when reclaiming from different zones. Link: http://lkml.kernel.org/r/1467970510-21195-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Kirill A. Shutemov
|
7751b2da6b |
vmscan: split file huge pages before paging them out
This is preparation of vmscan for file huge pages. We cannot write out huge pages, so we need to split them on the way out. Link: http://lkml.kernel.org/r/1466021202-61880-22-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Minchan Kim
|
b1123ea6d3 |
mm: balloon: use general non-lru movable page feature
Now, VM has a feature to migrate non-lru movable pages so balloon
doesn't need custom migration hooks in migrate.c and compaction.c.
Instead, this patch implements the page->mapping->a_ops->
{isolate|migrate|putback} functions.
With that, we could remove hooks for ballooning in general migration
functions and make balloon compaction simple.
[akpm@linux-foundation.org: compaction.h requires that the includer first include node.h]
Link: http://lkml.kernel.org/r/1464736881-24886-4-git-send-email-minchan@kernel.org
Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Michal Hocko
|
0a0337e0d1 |
mm, oom: rework oom detection
__alloc_pages_slowpath has traditionally relied on the direct reclaim and did_some_progress as an indicator that it makes sense to retry allocation rather than declaring OOM. shrink_zones had to rely on zone_reclaimable if shrink_zone didn't make any progress to prevent from a premature OOM killer invocation - the LRU might be full of dirty or writeback pages and direct reclaim cannot clean those up. zone_reclaimable allows to rescan the reclaimable lists several times and restart if a page is freed. This is really subtle behavior and it might lead to a livelock when a single freed page keeps allocator looping but the current task will not be able to allocate that single page. OOM killer would be more appropriate than looping without any progress for unbounded amount of time. This patch changes OOM detection logic and pulls it out from shrink_zone which is too low to be appropriate for any high level decisions such as OOM which is per zonelist property. It is __alloc_pages_slowpath which knows how many attempts have been done and what was the progress so far therefore it is more appropriate to implement this logic. The new heuristic is implemented in should_reclaim_retry helper called from __alloc_pages_slowpath. It tries to be more deterministic and easier to follow. It builds on an assumption that retrying makes sense only if the currently reclaimable memory + free pages would allow the current allocation request to succeed (as per __zone_watermark_ok) at least for one zone in the usable zonelist. This alone wouldn't be sufficient, though, because the writeback might get stuck and reclaimable pages might be pinned for a really long time or even depend on the current allocation context. Therefore there is a backoff mechanism implemented which reduces the reclaim target after each reclaim round without any progress. This means that we should eventually converge to only NR_FREE_PAGES as the target and fail on the wmark check and proceed to OOM. The backoff is simple and linear with 1/16 of the reclaimable pages for each round without any progress. We are optimistic and reset counter for successful reclaim rounds. Costly high order pages mostly preserve their semantic and those without __GFP_REPEAT fail right away while those which have the flag set will back off after the amount of reclaimable pages reaches equivalent of the requested order. The only difference is that if there was no progress during the reclaim we rely on zone watermark check. This is more logical thing to do than previous 1<<order attempts which were a result of zone_reclaimable faking the progress. [vdavydov@virtuozzo.com: check classzone_idx for shrink_zone] [hannes@cmpxchg.org: separate the heuristic into should_reclaim_retry] [rientjes@google.com: use zone_page_state_snapshot for NR_FREE_PAGES] [rientjes@google.com: shrink_zones doesn't need to return anything] Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
b6459cc154 |
vmscan: consider classzone_idx in compaction_ready
Motivation:
As pointed out by Linus [2][3] relying on zone_reclaimable as a way to
communicate the reclaim progress is rater dubious. I tend to agree,
not only it is really obscure, it is not hard to imagine cases where a
single page freed in the loop keeps all the reclaimers looping without
getting any progress because their gfp_mask wouldn't allow to get that
page anyway (e.g. single GFP_ATOMIC alloc and free loop). This is rather
rare so it doesn't happen in the practice but the current logic which we
have is rather obscure and hard to follow a also non-deterministic.
This is an attempt to make the OOM detection more deterministic and
easier to follow because each reclaimer basically tracks its own
progress which is implemented at the page allocator layer rather spread
out between the allocator and the reclaim. The more on the
implementation is described in the first patch.
I have tested several different scenarios but it should be clear that
testing OOM killer is quite hard to be representative. There is usually
a tiny gap between almost OOM and full blown OOM which is often time
sensitive. Anyway, I have tested the following 2 scenarios and I would
appreciate if there are more to test.
Testing environment: a virtual machine with 2G of RAM and 2CPUs without
any swap to make the OOM more deterministic.
1) 2 writers (each doing dd with 4M blocks to an xfs partition with 1G
file size, removes the files and starts over again) running in
parallel for 10s to build up a lot of dirty pages when 100 parallel
mem_eaters (anon private populated mmap which waits until it gets
signal) with 80M each.
This causes an OOM flood of course and I have compared both patched
and unpatched kernels. The test is considered finished after there
are no OOM conditions detected. This should tell us whether there are
any excessive kills or some of them premature (e.g. due to dirty pages):
I have performed two runs this time each after a fresh boot.
* base kernel
$ grep "Out of memory:" base-oom-run1.log | wc -l
78
$ grep "Out of memory:" base-oom-run2.log | wc -l
78
$ grep "Kill process" base-oom-run1.log | tail -n1
[ 91.391203] Out of memory: Kill process 3061 (mem_eater) score 39 or sacrifice child
$ grep "Kill process" base-oom-run2.log | tail -n1
[ 82.141919] Out of memory: Kill process 3086 (mem_eater) score 39 or sacrifice child
$ grep "DMA32 free:" base-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5376.00 max: 6776.00 avg: 5530.75 std: 166.50 nr: 61
$ grep "DMA32 free:" base-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5416.00 max: 5608.00 avg: 5514.15 std: 42.94 nr: 52
$ grep "DMA32.*all_unreclaimable? no" base-oom-run1.log | wc -l
1
$ grep "DMA32.*all_unreclaimable? no" base-oom-run2.log | wc -l
3
* patched kernel
$ grep "Out of memory:" patched-oom-run1.log | wc -l
78
miso@tiehlicka /mnt/share/devel/miso/kvm $ grep "Out of memory:" patched-oom-run2.log | wc -l
77
e grep "Kill process" patched-oom-run1.log | tail -n1
[ 497.317732] Out of memory: Kill process 3108 (mem_eater) score 39 or sacrifice child
$ grep "Kill process" patched-oom-run2.log | tail -n1
[ 316.169920] Out of memory: Kill process 3093 (mem_eater) score 39 or sacrifice child
$ grep "DMA32 free:" patched-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5420.00 max: 5808.00 avg: 5513.90 std: 60.45 nr: 78
$ grep "DMA32 free:" patched-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5380.00 max: 6384.00 avg: 5520.94 std: 136.84 nr: 77
e grep "DMA32.*all_unreclaimable? no" patched-oom-run1.log | wc -l
2
$ grep "DMA32.*all_unreclaimable? no" patched-oom-run2.log | wc -l
3
The patched kernel run noticeably longer while invoking OOM killer same
number of times. This means that the original implementation is much
more aggressive and triggers the OOM killer sooner. free pages stats
show that neither kernels went OOM too early most of the time, though. I
guess the difference is in the backoff when retries without any progress
do sleep for a while if there is memory under writeback or dirty which
is highly likely considering the parallel IO.
Both kernels have seen races where zone wasn't marked unreclaimable
and we still hit the OOM killer. This is most likely a race where
a task managed to exit between the last allocation attempt and the oom
killer invocation.
2) 2 writers again with 10s of run and then 10 mem_eaters to consume as much
memory as possible without triggering the OOM killer. This required a lot
of tuning but I've considered 3 consecutive runs in three different boots
without OOM as a success.
* base kernel
size=$(awk '/MemFree/{printf "%dK", ($2/10)-(16*1024)}' /proc/meminfo)
* patched kernel
size=$(awk '/MemFree/{printf "%dK", ($2/10)-(12*1024)}' /proc/meminfo)
That means 40M more memory was usable without triggering OOM killer. The
base kernel sometimes managed to handle the same as patched but it
wasn't consistent and failed in at least on of the 3 runs. This seems
like a minor improvement.
I was testing also GPF_REPEAT costly requests (hughetlb) with fragmented
memory and under memory pressure. The results are in patch 11 where the
logic is implemented. In short I can see huge improvement there.
I am certainly interested in other usecases as well as well as any
feedback. Especially those which require higher order requests.
This patch (of 14):
While playing with the oom detection rework [1] I have noticed that my
heavy order-9 (hugetlb) load close to OOM ended up in an endless loop
where the reclaim hasn't made any progress but did_some_progress didn't
reflect that and compaction_suitable was backing off because no zone is
above low wmark + 1 << order.
It turned out that this is in fact an old standing bug in
compaction_ready which ignores the requested_highidx and did the
watermark check for 0 classzone_idx. This succeeds for zone DMA most
of the time as the zone is mostly unused because of lowmem protection.
As a result costly high order allocatios always report a successfull
progress even when there was none. This wasn't a problem so far
because these allocations usually fail quite early or retry only few
times with __GFP_REPEAT but this will change after later patch in this
series so make sure to not lie about the progress and propagate
requested_highidx down to compaction_ready and use it for both the
watermak check and compaction_suitable to fix this issue.
[1] http://lkml.kernel.org/r/1459855533-4600-1-git-send-email-mhocko@kernel.org
[2] https://lkml.org/lkml/2015/10/12/808
[3] https://lkml.org/lkml/2015/10/13/597
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Rik van Riel
|
59dc76b0d4 |
mm: vmscan: reduce size of inactive file list
The inactive file list should still be large enough to contain readahead windows and freshly written file data, but it no longer is the only source for detecting multiple accesses to file pages. The workingset refault measurement code causes recently evicted file pages that get accessed again after a shorter interval to be promoted directly to the active list. With that mechanism in place, we can afford to (on a larger system) dedicate more memory to the active file list, so we can actually cache more of the frequently used file pages in memory, and not have them pushed out by streaming writes, once-used streaming file reads, etc. This can help things like database workloads, where only half the page cache can currently be used to cache the database working set. This patch automatically increases that fraction on larger systems, using the same ratio that has already been used for anonymous memory. [hannes@cmpxchg.org: cgroup-awareness] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Andres Freund <andres@anarazel.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Hugh Dickins
|
9d5e6a9f22 |
mm: update_lru_size do the __mod_zone_page_state
Konstantin Khlebnikov pointed out (nearly four years ago, when lumpy reclaim was removed) that lru_size can be updated by -nr_taken once per call to isolate_lru_pages(), instead of page by page. Update it inside isolate_lru_pages(), or at its two callsites? I chose to update it at the callsites, rearranging and grouping the updates by nr_taken and nr_scanned together in both. With one exception, mem_cgroup_update_lru_size(,lru,) is then used where __mod_zone_page_state(,NR_LRU_BASE+lru,) is used; and we shall be adding some more calls in a future commit. Make the code a little smaller and simpler by incorporating stat update in lru_size update. The exception was move_active_pages_to_lru(), which aggregated the pgmoved stat update separately from the individual lru_size updates; but I still think this a simplification worth making. However, the __mod_zone_page_state is not peculiar to mem_cgroups: so better use the name update_lru_size, calls mem_cgroup_update_lru_size when CONFIG_MEMCG. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Joonsoo Kim
|
0139aa7b7f |
mm: rename _count, field of the struct page, to _refcount
Many developers already know that field for reference count of the struct page is _count and atomic type. They would try to handle it directly and this could break the purpose of page reference count tracepoint. To prevent direct _count modification, this patch rename it to _refcount and add warning message on the code. After that, developer who need to handle reference count will find that field should not be accessed directly. [akpm@linux-foundation.org: fix comments, per Vlastimil] [akpm@linux-foundation.org: Documentation/vm/transhuge.txt too] [sfr@canb.auug.org.au: sync ethernet driver changes] Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Sunil Goutham <sgoutham@cavium.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Manish Chopra <manish.chopra@qlogic.com> Cc: Yuval Mintz <yuval.mintz@qlogic.com> Cc: Tariq Toukan <tariqt@mellanox.com> Cc: Saeed Mahameed <saeedm@mellanox.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vlastimil Babka
|
fd901c9538 |
mm: wake kcompactd before kswapd's short sleep
When kswapd goes to sleep it checks if the node is balanced and at first
it sleeps only for HZ/10 time, then rechecks if the node is still
balanced and nobody has woken it during the initial sleep. Only then it
goes fully sleep until an allocation slowpath wakes it up again.
For higher-order allocations, waking up kcompactd is done only before
the full sleep. This turns out to be an issue in case another
high-order allocation fails during the initial sleep. It will wake
kswapd up, however kswapd considers the zone balanced from the order-0
perspective, and will just quickly try to sleep again. So if there's a
longer stream of high-order allocations hitting the slowpath and waking
up kswapd, it might never actually wake up kcompactd, which may be
considered a regression from kswapd-based compaction. In the worst
case, it might be that a single allocation that cannot direct
reclaim/compact itself is waking kswapd in the retry loop and preventing
kcompactd from being woken up and unblocking it.
This patch makes sure kcompactd is woken up in such situations by simply
moving the wakeup before the short initial sleep. More efficient
solution would be to wake kcompactd immediately instead of kswapd if the
node is already order-0 balanced, but in that case we should also move
reset_isolation_suitable() call to kcompactd so it's not adding to the
allocator's latency. Since it's late in the 4.6 cycle, let's go with
the simpler change for now.
Fixes:
|
||
|
Minchan Kim
|
7bf52fb891 |
mm: vmscan: reclaim highmem zone if buffer_heads is over limit
We have been reclaimed highmem zone if buffer_heads is over limit but commit |
||
|
Joonsoo Kim
|
fe896d1878 |
mm: introduce page reference manipulation functions
The success of CMA allocation largely depends on the success of migration and key factor of it is page reference count. Until now, page reference is manipulated by direct calling atomic functions so we cannot follow up who and where manipulate it. Then, it is hard to find actual reason of CMA allocation failure. CMA allocation should be guaranteed to succeed so finding offending place is really important. In this patch, call sites where page reference is manipulated are converted to introduced wrapper function. This is preparation step to add tracepoint to each page reference manipulation function. With this facility, we can easily find reason of CMA allocation failure. There is no functional change in this patch. In addition, this patch also converts reference read sites. It will help a second step that renames page._count to something else and prevents later attempt to direct access to it (Suggested by Andrew). Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
0fc9f58a90 |
mm: vmscan: pass root_mem_cgroup instead of NULL to memcg aware shrinker
It's just convenient to implement a memcg aware shrinker when you know that shrink_control->memcg != NULL unless memcg_kmem_enabled() returns false. Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vlastimil Babka
|
accf62422b |
mm, kswapd: replace kswapd compaction with waking up kcompactd
Similarly to direct reclaim/compaction, kswapd attempts to combine
reclaim and compaction to attempt making memory allocation of given
order available.
The details differ from direct reclaim e.g. in having high watermark as
a goal. The code involved in kswapd's reclaim/compaction decisions has
evolved to be quite complex.
Testing reveals that it doesn't actually work in at least one scenario,
and closer inspection suggests that it could be greatly simplified
without compromising on the goal (make high-order page available) or
efficiency (don't reclaim too much). The simplification relieas of
doing all compaction in kcompactd, which is simply woken up when high
watermarks are reached by kswapd's reclaim.
The scenario where kswapd compaction doesn't work was found with mmtests
test stress-highalloc configured to attempt order-9 allocations without
direct reclaim, just waking up kswapd. There was no compaction attempt
from kswapd during the whole test. Some added instrumentation shows
what happens:
- balance_pgdat() sets end_zone to Normal, as it's not balanced
- reclaim is attempted on DMA zone, which sets nr_attempted to 99, but
it cannot reclaim anything, so sc.nr_reclaimed is 0
- for zones DMA32 and Normal, kswapd_shrink_zone uses testorder=0, so
it merely checks if high watermarks were reached for base pages.
This is true, so no reclaim is attempted. For DMA, testorder=0
wasn't used, as compaction_suitable() returned COMPACT_SKIPPED
- even though the pgdat_needs_compaction flag wasn't set to false, no
compaction happens due to the condition sc.nr_reclaimed >
nr_attempted being false (as 0 < 99)
- priority-- due to nr_reclaimed being 0, repeat until priority reaches
0 pgdat_balanced() is false as only the small zone DMA appears
balanced (curiously in that check, watermark appears OK and
compaction_suitable() returns COMPACT_PARTIAL, because a lower
classzone_idx is used there)
Now, even if it was decided that reclaim shouldn't be attempted on the
DMA zone, the scenario would be the same, as (sc.nr_reclaimed=0 >
nr_attempted=0) is also false. The condition really should use >= as
the comment suggests. Then there is a mismatch in the check for setting
pgdat_needs_compaction to false using low watermark, while the rest uses
high watermark, and who knows what other subtlety. Hopefully this
demonstrates that this is unsustainable.
Luckily we can simplify this a lot. The reclaim/compaction decisions
make sense for direct reclaim scenario, but in kswapd, our primary goal
is to reach high watermark in order-0 pages. Afterwards we can attempt
compaction just once. Unlike direct reclaim, we don't reclaim extra
pages (over the high watermark), the current code already disallows it
for good reasons.
After this patch, we simply wake up kcompactd to process the pgdat,
after we have either succeeded or failed to reach the high watermarks in
kswapd, which goes to sleep. We pass kswapd's order and classzone_idx,
so kcompactd can apply the same criteria to determine which zones are
worth compacting. Note that we use the classzone_idx from
wakeup_kswapd(), not balanced_classzone_idx which can include higher
zones that kswapd tried to balance too, but didn't consider them in
pgdat_balanced().
Since kswapd now cannot create high-order pages itself, we need to
adjust how it determines the zones to be balanced. The key element here
is adding a "highorder" parameter to zone_balanced, which, when set to
false, makes it consider only order-0 watermark instead of the desired
higher order (this was done previously by kswapd_shrink_zone(), but not
elsewhere). This false is passed for example in pgdat_balanced().
Importantly, wakeup_kswapd() uses true to make sure kswapd and thus
kcompactd are woken up for a high-order allocation failure.
The last thing is to decide what to do with pageblock_skip bitmap
handling. Compaction maintains a pageblock_skip bitmap to record
pageblocks where isolation recently failed. This bitmap can be reset by
three ways:
1) direct compaction is restarting after going through the full deferred cycle
2) kswapd goes to sleep, and some other direct compaction has previously
finished scanning the whole zone and set zone->compact_blockskip_flush.
Note that a successful direct compaction clears this flag.
3) compaction was invoked manually via trigger in /proc
The case 2) is somewhat fuzzy to begin with, but after introducing
kcompactd we should update it. The check for direct compaction in 1),
and to set the flush flag in 2) use current_is_kswapd(), which doesn't
work for kcompactd. Thus, this patch adds bool direct_compaction to
compact_control to use in 2). For the case 1) we remove the check
completely - unlike the former kswapd compaction, kcompactd does use the
deferred compaction functionality, so flushing tied to restarting from
deferred compaction makes sense here.
Note that when kswapd goes to sleep, kcompactd is woken up, so it will
see the flushed pageblock_skip bits. This is different from when the
former kswapd compaction observed the bits and I believe it makes more
sense. Kcompactd can afford to be more thorough than a direct
compaction trying to limit allocation latency, or kswapd whose primary
goal is to reclaim.
For testing, I used stress-highalloc configured to do order-9
allocations with GFP_NOWAIT|__GFP_HIGH|__GFP_COMP, so they relied just
on kswapd/kcompactd reclaim/compaction (the interfering kernel builds in
phases 1 and 2 work as usual):
stress-highalloc
4.5-rc1+before 4.5-rc1+after
-nodirect -nodirect
Success 1 Min 1.00 ( 0.00%) 5.00 (-66.67%)
Success 1 Mean 1.40 ( 0.00%) 6.20 (-55.00%)
Success 1 Max 2.00 ( 0.00%) 7.00 (-16.67%)
Success 2 Min 1.00 ( 0.00%) 5.00 (-66.67%)
Success 2 Mean 1.80 ( 0.00%) 6.40 (-52.38%)
Success 2 Max 3.00 ( 0.00%) 7.00 (-16.67%)
Success 3 Min 34.00 ( 0.00%) 62.00 ( 1.59%)
Success 3 Mean 41.80 ( 0.00%) 63.80 ( 1.24%)
Success 3 Max 53.00 ( 0.00%) 65.00 ( 2.99%)
User 3166.67 3181.09
System 1153.37 1158.25
Elapsed 1768.53 1799.37
4.5-rc1+before 4.5-rc1+after
-nodirect -nodirect
Direct pages scanned 32938 32797
Kswapd pages scanned 2183166 2202613
Kswapd pages reclaimed 2152359 2143524
Direct pages reclaimed 32735 32545
Percentage direct scans 1% 1%
THP fault alloc 579 612
THP collapse alloc 304 316
THP splits 0 0
THP fault fallback 793 778
THP collapse fail 11 16
Compaction stalls 1013 1007
Compaction success 92 67
Compaction failures 920 939
Page migrate success 238457 721374
Page migrate failure 23021 23469
Compaction pages isolated 504695 1479924
Compaction migrate scanned 661390 8812554
Compaction free scanned 13476658 84327916
Compaction cost 262 838
After this patch we see improvements in allocation success rate
(especially for phase 3) along with increased compaction activity. The
compaction stalls (direct compaction) in the interfering kernel builds
(probably THP's) also decreased somewhat thanks to kcompactd activity,
yet THP alloc successes improved a bit.
Note that elapsed and user time isn't so useful for this benchmark,
because of the background interference being unpredictable. It's just
to quickly spot some major unexpected differences. System time is
somewhat more useful and that didn't increase.
Also (after adjusting mmtests' ftrace monitor):
Time kswapd awake 2547781 2269241
Time kcompactd awake 0 119253
Time direct compacting 939937 557649
Time kswapd compacting 0 0
Time kcompactd compacting 0 119099
The decrease of overal time spent compacting appears to not match the
increased compaction stats. I suspect the tasks get rescheduled and
since the ftrace monitor doesn't see that, the reported time is wall
time, not CPU time. But arguably direct compactors care about overall
latency anyway, whether busy compacting or waiting for CPU doesn't
matter. And that latency seems to almost halved.
It's also interesting how much time kswapd spent awake just going
through all the priorities and failing to even try compacting, over and
over.
We can also configure stress-highalloc to perform both direct
reclaim/compaction and wakeup kswapd/kcompactd, by using
GFP_KERNEL|__GFP_HIGH|__GFP_COMP:
stress-highalloc
4.5-rc1+before 4.5-rc1+after
-direct -direct
Success 1 Min 4.00 ( 0.00%) 9.00 (-50.00%)
Success 1 Mean 8.00 ( 0.00%) 10.00 (-19.05%)
Success 1 Max 12.00 ( 0.00%) 11.00 ( 15.38%)
Success 2 Min 4.00 ( 0.00%) 9.00 (-50.00%)
Success 2 Mean 8.20 ( 0.00%) 10.00 (-16.28%)
Success 2 Max 13.00 ( 0.00%) 11.00 ( 8.33%)
Success 3 Min 75.00 ( 0.00%) 74.00 ( 1.33%)
Success 3 Mean 75.60 ( 0.00%) 75.20 ( 0.53%)
Success 3 Max 77.00 ( 0.00%) 76.00 ( 0.00%)
User 3344.73 3246.04
System 1194.24 1172.29
Elapsed 1838.04 1836.76
4.5-rc1+before 4.5-rc1+after
-direct -direct
Direct pages scanned 125146 120966
Kswapd pages scanned 2119757 2135012
Kswapd pages reclaimed 2073183 2108388
Direct pages reclaimed 124909 120577
Percentage direct scans 5% 5%
THP fault alloc 599 652
THP collapse alloc 323 354
THP splits 0 0
THP fault fallback 806 793
THP collapse fail 17 16
Compaction stalls 2457 2025
Compaction success 906 518
Compaction failures 1551 1507
Page migrate success 2031423 2360608
Page migrate failure 32845 40852
Compaction pages isolated
|
||
|
Vlastimil Babka
|
81c5857b27 |
mm, kswapd: remove bogus check of balance_classzone_idx
During work on kcompactd integration I have spotted a confusing check of balance_classzone_idx, which I believe is bogus. The balanced_classzone_idx is filled by balance_pgdat() as the highest zone it attempted to balance. This was introduced by commit |
||
|
Johannes Weiner
|
fdf1cdb91b |
mm: remove unnecessary uses of lock_page_memcg()
There are several users that nest lock_page_memcg() inside lock_page() to prevent page->mem_cgroup from changing. But the page lock prevents pages from moving between cgroups, so that is unnecessary overhead. Remove lock_page_memcg() in contexts with locked contexts and fix the debug code in the page stat functions to be okay with the page lock. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
62cccb8c8e |
mm: simplify lock_page_memcg()
Now that migration doesn't clear page->mem_cgroup of live pages anymore, it's safe to make lock_page_memcg() and the memcg stat functions take pages, and spare the callers from memcg objects. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
23047a96d7 |
mm: workingset: per-cgroup cache thrash detection
Cache thrash detection (see
|
||
|
Johannes Weiner
|
81f8c3a461 |
mm: memcontrol: generalize locking for the page->mem_cgroup binding
These patches tag the page cache radix tree eviction entries with the memcg an evicted page belonged to, thus making per-cgroup LRU reclaim work properly and be as adaptive to new cache workingsets as global reclaim already is. This should have been part of the original thrash detection patch series, but was deferred due to the complexity of those patches. This patch (of 5): So far the only sites that needed to exclude charge migration to stabilize page->mem_cgroup have been per-cgroup page statistics, hence the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection will add another site that needs to ensure page->mem_cgroup lifetime. Rename these locking functions to the more generic lock_page_memcg() and unlock_page_memcg(). Since charge migration is a cgroup1 feature only, we might be able to delete it at some point, and these now easy to identify locking sites along with it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Michal Hocko
|
0db2cb8da8 |
mm, vmscan: make zone_reclaimable_pages more precise
zone_reclaimable_pages() is used in should_reclaim_retry() which uses it to calculate the target for the watermark check. This means that precise numbers are important for the correct decision. zone_reclaimable_pages uses zone_page_state which can contain stale data with per-cpu diffs not synced yet (the last vmstat_update might have run 1s in the past). Use zone_page_state_snapshot() in zone_reclaimable_pages() instead. None of the current callers is in a hot path where getting the precise value (which involves per-cpu iteration) would cause an unreasonable overhead. Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Suggested-by: David Rientjes <rientjes@google.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
cecf257b62 |
mm: vmscan: do not clear SHRINKER_NUMA_AWARE if nr_node_ids == 1
Currently, on shrinker registration we clear SHRINKER_NUMA_AWARE if there's the only NUMA node present. The comment states that this will allow us to save some small loop time later. It used to be true when this code was added (see commit |
||
|
Kirill A. Shutemov
|
cf2a82ee43 |
mm: downgrade VM_BUG in isolate_lru_page() to warning
Calling isolate_lru_page() is wrong and shouldn't happen, but it not nessesary fatal: the page just will not be isolated if it's not on LRU. Let's downgrade the VM_BUG_ON_PAGE() to WARN_RATELIMIT(). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Ross Zwisler
|
f9fe48bece |
dax: support dirty DAX entries in radix tree
Add support for tracking dirty DAX entries in the struct address_space radix tree. This tree is already used for dirty page writeback, and it already supports the use of exceptional (non struct page*) entries. In order to properly track dirty DAX pages we will insert new exceptional entries into the radix tree that represent dirty DAX PTE or PMD pages. These exceptional entries will also contain the writeback addresses for the PTE or PMD faults that we can use at fsync/msync time. There are currently two types of exceptional entries (shmem and shadow) that can be placed into the radix tree, and this adds a third. We rely on the fact that only one type of exceptional entry can be found in a given radix tree based on its usage. This happens for free with DAX vs shmem but we explicitly prevent shadow entries from being added to radix trees for DAX mappings. The only shadow entries that would be generated for DAX radix trees would be to track zero page mappings that were created for holes. These pages would receive minimal benefit from having shadow entries, and the choice to have only one type of exceptional entry in a given radix tree makes the logic simpler both in clear_exceptional_entry() and in the rest of DAX. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Dave Chinner <david@fromorbit.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jan Kara <jack@suse.com> Cc: Jeff Layton <jlayton@poochiereds.net> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |