Commit Graph

1050 Commits

Author SHA1 Message Date
Andrew Morton
0edaf86cf1 include/linux/nodemask.h: create next_node_in() helper
Lots of code does

	node = next_node(node, XXX);
	if (node == MAX_NUMNODES)
		node = first_node(XXX);

so create next_node_in() to do this and use it in various places.

[mhocko@suse.com: use next_node_in() helper]
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Hui Zhu <zhuhui@xiaomi.com>
Cc: Wang Xiaoqiang <wangxq10@lzu.edu.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-19 19:12:14 -07:00
Tejun Heo
264a0ae164 memcg: relocate charge moving from ->attach to ->post_attach
Hello,

So, this ended up a lot simpler than I originally expected.  I tested
it lightly and it seems to work fine.  Petr, can you please test these
two patches w/o the lru drain drop patch and see whether the problem
is gone?

Thanks.
------ 8< ------
If charge moving is used, memcg performs relabeling of the affected
pages from its ->attach callback which is called under both
cgroup_threadgroup_rwsem and thus can't create new kthreads.  This is
fragile as various operations may depend on workqueues making forward
progress which relies on the ability to create new kthreads.

There's no reason to perform charge moving from ->attach which is deep
in the task migration path.  Move it to ->post_attach which is called
after the actual migration is finished and cgroup_threadgroup_rwsem is
dropped.

* move_charge_struct->mm is added and ->can_attach is now responsible
  for pinning and recording the target mm.  mem_cgroup_clear_mc() is
  updated accordingly.  This also simplifies mem_cgroup_move_task().

* mem_cgroup_move_task() is now called from ->post_attach instead of
  ->attach.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Debugged-and-tested-by: Petr Mladek <pmladek@suse.com>
Reported-by: Cyril Hrubis <chrubis@suse.cz>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Fixes: 1ed1328792 ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem")
Cc: <stable@vger.kernel.org> # 4.4+
2016-04-25 15:45:14 -04:00
Vladimir Davydov
e0775d10f1 mm: memcontrol: zap oom_info_lock
mem_cgroup_print_oom_info is always called under oom_lock, so
oom_info_lock is redundant.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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>
2016-03-17 15:09:34 -07:00
Johannes Weiner
8b5926560f mm: memcontrol: clarify the uncharge_list() loop
uncharge_list() does an unusual list walk because the function can take
regular lists with dedicated list_heads as well as singleton lists where
a single page is passed via the page->lru list node.

This can sometimes lead to confusion as well as suggestions to replace
the loop with a list_for_each_entry(), which wouldn't work.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.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>
2016-03-17 15:09:34 -07:00
Johannes Weiner
b6e6edcfa4 mm: memcontrol: reclaim and OOM kill when shrinking memory.max below usage
Setting the original memory.limit_in_bytes hardlimit is subject to a
race condition when the desired value is below the current usage.  The
code tries a few times to first reclaim and then see if the usage has
dropped to where we would like it to be, but there is no locking, and
the workload is free to continue making new charges up to the old limit.
Thus, attempting to shrink a workload relies on pure luck and hope that
the workload happens to cooperate.

To fix this in the cgroup2 memory.max knob, do it the other way round:
set the limit first, then try enforcement.  And if reclaim is not able
to succeed, trigger OOM kills in the group.  Keep going until the new
limit is met, we run out of OOM victims and there's only unreclaimable
memory left, or the task writing to memory.max is killed.  This allows
users to shrink groups reliably, and the behavior is consistent with
what happens when new charges are attempted in excess of memory.max.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 15:09:34 -07:00
Johannes Weiner
588083bb37 mm: memcontrol: reclaim when shrinking memory.high below usage
When setting memory.high below usage, nothing happens until the next
charge comes along, and then it will only reclaim its own charge and not
the now potentially huge excess of the new memory.high.  This can cause
groups to stay in excess of their memory.high indefinitely.

To fix that, when shrinking memory.high, kick off a reclaim cycle that
goes after the delta.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
d334c9bcb4 mm: memcontrol: cleanup css_reset callback
- Do not take memcg_limit_mutex for resetting limits - the cgroup cannot
  be altered from userspace anymore, so no need to protect them.

- Use plain page_counter_limit() for resetting ->memory and ->memsw
  limits instead of mem_cgrouop_resize_* helpers - we enlarge the limits,
  so no need in special handling.

- Reset ->swap and ->tcpmem limits as well.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
0a6b76dd23 mm: workingset: make shadow node shrinker memcg aware
Workingset code was recently made memcg aware, but shadow node shrinker
is still global.  As a result, one small cgroup can consume all memory
available for shadow nodes, possibly hurting other cgroups by reclaiming
their shadow nodes, even though reclaim distances stored in its shadow
nodes have no effect.  To avoid this, we need to make shadow node
shrinker memcg aware.

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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
b6ecd2dea4 mm: memcontrol: zap memcg_kmem_online helper
As kmem accounting is now either enabled for all cgroups or disabled
system-wide, there's no point in having memcg_kmem_online() helper -
instead one can use memcg_kmem_enabled() and mem_cgroup_online(), as
shrink_slab() now does.

There are only two places left where this helper is used -
__memcg_kmem_charge() and memcg_create_kmem_cache().  The former can
only be called if memcg_kmem_enabled() returned true.  Since the cgroup
it operates on is online, mem_cgroup_is_root() check will be enough.

memcg_create_kmem_cache() can't use mem_cgroup_online() helper instead
of memcg_kmem_online(), because it relies on the fact that in
memcg_offline_kmem() memcg->kmem_state is changed before
memcg_deactivate_kmem_caches() is called, but there we can just
open-code the check.

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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
b313aeee25 mm: memcontrol: enable kmem accounting for all cgroups in the legacy hierarchy
Workingset code was recently made memcg aware, but shadow node shrinker
is still global.  As a result, one small cgroup can consume all memory
available for shadow nodes, possibly hurting other cgroups by reclaiming
their shadow nodes, even though reclaim distances stored in its shadow
nodes have no effect.  To avoid this, we need to make shadow node
shrinker memcg aware.

The actual work is done in patch 6 of the series.  Patches 1 and 2
prepare memcg/shrinker infrastructure for the change.  Patch 3 is just a
collateral cleanup.  Patch 4 makes radix_tree_node accounted, which is
necessary for making shadow node shrinker memcg aware.  Patch 5 reduces
shadow nodes overhead in case workload mostly uses anonymous pages.

This patch:

Currently, in the legacy hierarchy kmem accounting is off for all
cgroups by default and must be enabled explicitly by writing something
to memory.kmem.limit_in_bytes.  Since we don't support reclaim on
hitting kmem limit, nor do we have any plans to implement it, this is
likely to be -1, just to enable kmem accounting and limit kernel memory
consumption by the memory.limit_in_bytes along with user memory.

This user API was introduced when the implementation of kmem accounting
lacked slab shrinker support and hence was useless in practice.  Things
have changed since then - slab shrinkers were made memcg aware, the
accounting overhead seems to be negligible, and a failure to charge a
kmem allocation should not have critical consequences, because we only
account those kernel objects that should be safe to fail.  That's why
kmem accounting is enabled by default for all cgroups in the default
hierarchy, which will eventually replace the legacy one.

The ability to enable kmem accounting for some cgroups while keeping it
disabled for others is getting difficult to maintain.  E.g.  to make
shadow node shrinker memcg aware (see mm/workingset.c), we need to know
the relationship between the number of shadow nodes allocated for a
cgroup and the size of its lru list.  If kmem accounting is enabled for
all cgroups there is no problem, but what should we do if kmem
accounting is enabled only for half of cgroups? We've no other choice
but use global lru stats while scanning root cgroup's shadow nodes, but
that would be wrong if kmem accounting was enabled for all cgroups
(which is the case if the unified hierarchy is used), in which case we
should use lru stats of the root cgroup's lruvec.

That being said, let's enable kmem accounting for all memory cgroups by
default.  If one finds it unstable or too costly, it can always be
disabled system-wide by passing cgroup.memory=nokmem to the kernel at
boot time.

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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
12580e4b54 mm: memcontrol: report kernel stack usage in cgroup2 memory.stat
Show how much memory is allocated to kernel stacks.

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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
27ee57c93f mm: memcontrol: report slab usage in cgroup2 memory.stat
Show how much memory is used for storing reclaimable and unreclaimable
in-kernel data structures allocated from slab caches.

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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
72b54e7314 mm: memcontrol: make tree_{stat,events} fetch all stats
Currently, tree_{stat,events} helpers can only get one stat index at a
time, so when there are a lot of stats to be reported one has to call it
over and over again (see memory_stat_show).  This is neither effective,
nor does it look good.  Instead, let's make these helpers take a
snapshot of all available counters.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: 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>
2016-03-17 15:09:34 -07:00
Vladimir Davydov
fcff7d7eeb mm: memcontrol: do not bypass slab charge if memcg is offline
Slab pages are charged in two steps.  First, an appropriate per memcg
cache is selected (see memcg_kmem_get_cache) basing on the current
context, then the new slab page is charged to the memory cgroup which
the selected cache was created for (see memcg_charge_slab ->
__memcg_kmem_charge_memcg).  It is OK to bypass kmemcg charge at step 1,
but if step 1 succeeded and we successfully allocated a new slab page,
step 2 must be performed, otherwise we would get a per memcg kmem cache
which contains a slab that does not hold a reference to the memory
cgroup owning the cache.  Since per memcg kmem caches are destroyed on
memcg css free, this could result in freeing a cache while there are
still active objects in it.

However, currently we will bypass slab page charge if the memory cgroup
owning the cache is offline (see __memcg_kmem_charge_memcg).  This is
very unlikely to occur in practice, because for this to happen a process
must be migrated to a different cgroup and the old cgroup must be
removed while the process is in kmalloc somewhere between steps 1 and 2
(e.g.  trying to allocate a new page).  Nevertheless, it's still better
to eliminate such a possibility.

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>
2016-03-17 15:09:34 -07:00
Johannes Weiner
9cf7666ace mm: memcontrol: drop unnecessary lru locking from mem_cgroup_migrate()
Migration accounting in the memory controller used to have to handle
both oldpage and newpage being on the LRU already; fuse's page cache
replacement used to pass a recycled newpage that had been uncharged but
not freed and removed from the LRU, and the memcg migration code used to
uncharge oldpage to "pass on" the existing charge to newpage.

Nowadays, pages are no longer uncharged when truncated from the page
cache, but rather only at free time, so if a LRU page is recycled in
page cache replacement it'll also still be charged.  And we bail out of
the charge transfer altogether in that case.  Tell commit_charge() that
we know newpage is not on the LRU, to avoid taking the zone->lru_lock
unnecessarily from the migration path.

But also, oldpage is no longer uncharged inside migration.  We only use
oldpage for its page->mem_cgroup and page size, so we don't care about
its LRU state anymore either.  Remove any mention from the kernel doc.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-15 16:55:16 -07:00
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>
2016-03-15 16:55:16 -07:00
Johannes Weiner
6a93ca8fde mm: migrate: do not touch page->mem_cgroup of live pages
Changing a page's memcg association complicates dealing with the page,
so we want to limit this as much as possible.  Page migration e.g.  does
not have to do that.  Just like page cache replacement, it can forcibly
charge a replacement page, and then uncharge the old page when it gets
freed.  Temporarily overcharging the cgroup by a single page is not an
issue in practice, and charging is so cheap nowadays that this is much
preferrable to the headache of messing with live pages.

The only place that still changes the page->mem_cgroup binding of live
pages is when pages move along with a task to another cgroup.  But that
path isolates the page from the LRU, takes the page lock, and the move
lock (lock_page_memcg()).  That means page->mem_cgroup is always stable
in callers that have the page isolated from the LRU or locked.  Lighter
unlocked paths, like writeback accounting, can use lock_page_memcg().

[akpm@linux-foundation.org: fix build]
[vdavydov@virtuozzo.com: fix lockdep splat]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.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>
2016-03-15 16:55:16 -07:00
Johannes Weiner
23047a96d7 mm: workingset: per-cgroup cache thrash detection
Cache thrash detection (see a528910e12 "mm: thrash detection-based
file cache sizing" for details) currently only works on the system
level, not inside cgroups.  Worse, as the refaults are compared to the
global number of active cache, cgroups might wrongfully get all their
refaults activated when their pages are hotter than those of others.

Move the refault machinery from the zone to the lruvec, and then tag
eviction entries with the memcg ID.  This makes the thrash detection
work correctly inside cgroups.

[sergey.senozhatsky@gmail.com: do not return from workingset_activation() with locked rcu and page]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-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>
2016-03-15 16:55:16 -07:00
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>
2016-03-15 16:55:16 -07:00
Kirill A. Shutemov
b6ec57f4b9 thp: change pmd_trans_huge_lock() interface to return ptl
After THP refcounting rework we have only two possible return values
from pmd_trans_huge_lock(): success and failure.  Return-by-pointer for
ptl doesn't make much sense in this case.

Let's convert pmd_trans_huge_lock() to return ptl on success and NULL on
failure.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
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>
2016-01-21 17:20:51 -08:00
Johannes Weiner
b2807f07f4 mm: memcontrol: add "sock" to cgroup2 memory.stat
Provide statistics on how much of a cgroup's memory footprint is made up
of socket buffers from network connections owned by the group.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
587d9f726a mm: memcontrol: basic memory statistics in cgroup2 memory controller
Provide a cgroup2 memory.stat that provides statistics on LRU memory
and fault event counters. More consumers and breakdowns will follow.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
44b7a8d33d mm: memcontrol: do not uncharge old page in page cache replacement
Changing page->mem_cgroup of a live page is tricky and fragile.  In
particular, the memcg writeback code relies on that mapping being stable
and users of mem_cgroup_replace_page() not overlapping with dirtyable
inodes.

Page cache replacement doesn't have to do that, though.  Instead of being
clever and transferring the charge from the old page to the new,
force-charge the new page and leave the old page alone.  A temporary
overcharge won't matter in practice, and the old page is going to be freed
shortly after this anyway.  And this is not performance critical.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Vladimir Davydov
5ccc5abaaf mm: free swap cache aggressively if memcg swap is full
Swap cache pages are freed aggressively if swap is nearly full (>50%
currently), because otherwise we are likely to stop scanning anonymous
when we near the swap limit even if there is plenty of freeable swap cache
pages.  We should follow the same trend in case of memory cgroup, which
has its own swap limit.

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>
2016-01-20 17:09:18 -08:00
Vladimir Davydov
d8b38438a0 mm: vmscan: do not scan anon pages if memcg swap limit is hit
We don't scan anonymous memory if we ran out of swap, neither should we do
it in case memcg swap limit is hit, because swap out is impossible anyway.

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>
2016-01-20 17:09:18 -08:00
Vladimir Davydov
37e8435119 mm: memcontrol: charge swap to cgroup2
This patchset introduces swap accounting to cgroup2.

This patch (of 7):

In the legacy hierarchy we charge memsw, which is dubious, because:

 - memsw.limit must be >= memory.limit, so it is impossible to limit
   swap usage less than memory usage. Taking into account the fact that
   the primary limiting mechanism in the unified hierarchy is
   memory.high while memory.limit is either left unset or set to a very
   large value, moving memsw.limit knob to the unified hierarchy would
   effectively make it impossible to limit swap usage according to the
   user preference.

 - memsw.usage != memory.usage + swap.usage, because a page occupying
   both swap entry and a swap cache page is charged only once to memsw
   counter. As a result, it is possible to effectively eat up to
   memory.limit of memory pages *and* memsw.limit of swap entries, which
   looks unexpected.

That said, we should provide a different swap limiting mechanism for
cgroup2.

This patch adds mem_cgroup->swap counter, which charges the actual number
of swap entries used by a cgroup.  It is only charged in the unified
hierarchy, while the legacy hierarchy memsw logic is left intact.

The swap usage can be monitored using new memory.swap.current file and
limited using memory.swap.max.

Note, to charge swap resource properly in the unified hierarchy, we have
to make swap_entry_free uncharge swap only when ->usage reaches zero, not
just ->count, i.e.  when all references to a swap entry, including the one
taken by swap cache, are gone.  This is necessary, because otherwise
swap-in could result in uncharging swap even if the page is still in swap
cache and hence still occupies a swap entry.  At the same time, this
shouldn't break memsw counter logic, where a page is never charged twice
for using both memory and swap, because in case of legacy hierarchy we
uncharge swap on commit (see mem_cgroup_commit_charge).

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@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>
2016-01-20 17:09:18 -08:00
Johannes Weiner
0b8f73e104 mm: memcontrol: clean up alloc, online, offline, free functions
The creation and teardown of struct mem_cgroup is fairly messy and
that has attracted mistakes and subtle bugs before.

The main cause for this is that there is no clear model about what
needs to happen when, and that attracts more chaos. So create one:

1. mem_cgroup_alloc() should allocate struct mem_cgroup and its
   auxiliary members and initialize work items, locks etc. so that the
   object it returns is fully initialized and in a neutral state.

2. mem_cgroup_css_alloc() will use mem_cgroup_alloc() to obtain a new
   memcg object and configure it and the system according to the role
   of the new memory-controlled cgroup in the hierarchy.

3. mem_cgroup_css_online() is no longer needed to synchronize with
   iterators, but it verifies css->id which isn't available earlier.

4. mem_cgroup_css_offline() implements stuff that needs to happen upon
   the user-visible destruction of a cgroup, which includes stopping
   all user interfacing as well as releasing certain structures when
   continued memory consumption would be unexpected at that point.

5. mem_cgroup_css_free() prepares the system and the memcg object for
   the object's disappearance, neutralizes its state, and then gives
   it back to mem_cgroup_free().

6. mem_cgroup_free() releases struct mem_cgroup and auxiliary memory.

[arnd@arndb.de: fix SLOB build regression]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
0db1529817 mm: memcontrol: flatten struct cg_proto
There are no more external users of struct cg_proto, flatten the
structure into struct mem_cgroup.

Since using those struct members doesn't stand out as much anymore,
add cgroup2 static branches to make it clearer which code is legacy.

Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
d886f4e483 mm: memcontrol: rein in the CONFIG space madness
What CONFIG_INET and CONFIG_LEGACY_KMEM guard inside the memory
controller code is insignificant, having these conditionals is not
worth the complication and fragility that comes with them.

[akpm@linux-foundation.org: rework mem_cgroup_css_free() statement ordering]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Vladimir Davydov
d55f90bfab net: drop tcp_memcontrol.c
tcp_memcontrol.c only contains legacy memory.tcp.kmem.* file definitions
and mem_cgroup->tcp_mem init/destroy stuff.  This doesn't belong to
network subsys.  Let's move it to memcontrol.c.  This also allows us to
reuse generic code for handling legacy memcg files.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "David S. Miller" <davem@davemloft.net>
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>
2016-01-20 17:09:18 -08:00
Johannes Weiner
489c2a20a4 mm: memcontrol: introduce CONFIG_MEMCG_LEGACY_KMEM
Let the user know that CONFIG_MEMCG_KMEM does not apply to the cgroup2
interface. This also makes legacy-only code sections stand out better.

[arnd@arndb.de: mm: memcontrol: only manage socket pressure for CONFIG_INET]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Vladimir Davydov
04823c833b mm: memcontrol: allow to disable kmem accounting for cgroup2
Kmem accounting might incur overhead that some users can't put up with.
Besides, the implementation is still considered unstable.  So let's
provide a way to disable it for those users who aren't happy with it.

To disable kmem accounting for cgroup2, pass cgroup.memory=nokmem at
boot time.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
52c29b0482 mm: memcontrol: account "kmem" consumers in cgroup2 memory controller
The original cgroup memory controller has an extension to account slab
memory (and other "kernel memory" consumers) in a separate "kmem"
counter, once the user set an explicit limit on that "kmem" pool.

However, this includes various consumers whose sizes are directly linked
to userspace activity.  Accounting them as an optional "kmem" extension
is problematic for several reasons:

1. It leaves the main memory interface with incomplete semantics. A
   user who puts their workload into a cgroup and configures a memory
   limit does not expect us to leave holes in the containment as big
   as the dentry and inode cache, or the kernel stack pages.

2. If the limit set on this random historical subgroup of consumers is
   reached, subsequent allocations will fail even when the main memory
   pool available to the cgroup is not yet exhausted and/or has
   reclaimable memory in it.

3. Calling it 'kernel memory' is misleading. The dentry and inode
   caches are no more 'kernel' (or no less 'user') memory than the
   page cache itself. Treating these consumers as different classes is
   a historical implementation detail that should not leak to users.

So, in addition to page cache, anonymous memory, and network socket
memory, account the following memory consumers per default in the
cgroup2 memory controller:

     - threadinfo
     - task_struct
     - task_delay_info
     - pid
     - cred
     - mm_struct
     - vm_area_struct and vm_region (nommu)
     - anon_vma and anon_vma_chain
     - signal_struct
     - sighand_struct
     - fs_struct
     - files_struct
     - fdtable and fdtable->full_fds_bits
     - dentry and external_name
     - inode for all filesystems.

This should give us reasonable memory isolation for most common
workloads out of the box.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
127424c86b mm: memcontrol: move kmem accounting code to CONFIG_MEMCG
The cgroup2 memory controller will account important in-kernel memory
consumers per default.  Move all necessary components to CONFIG_MEMCG.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
3893e302f6 mm: memcontrol: separate kmem code from legacy tcp accounting code
The cgroup2 memory controller will include important in-kernel memory
consumers per default, including socket memory, but it will no longer
carry the historic tcp control interface.

Separate the kmem state init from the tcp control interface init in
preparation for that.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
8e0a891213 mm: memcontrol: group kmem init and exit functions together
Put all the related code to setup and teardown the kmem accounting state
into the same location.  No functional change intended.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
567e9ab2e6 mm: memcontrol: give the kmem states more descriptive names
On any given memcg, the kmem accounting feature has three separate
states: not initialized, structures allocated, and actively accounting
slab memory.  These are represented through a combination of the
kmem_acct_activated and kmem_acct_active flags, which is confusing.

Convert to a kmem_state enum with the states NONE, ALLOCATED, and
ONLINE.  Then rename the functions to modify the state accordingly.
This follows the nomenclature of css object states more closely.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
b15aac110a mm: memcontrol: remove double kmem page_counter init
The kmem page_counter's limit is initialized to PAGE_COUNTER_MAX inside
mem_cgroup_css_online().  There is no need to repeat this from
memcg_propagate_kmem().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Johannes Weiner
6d378dac7c mm: memcontrol: drop unused @css argument in memcg_init_kmem
This series adds accounting of the historical "kmem" memory consumers to
the cgroup2 memory controller.

These consumers include the dentry cache, the inode cache, kernel stack
pages, and a few others that are pointed out in patch 7/8.  The
footprint of these consumers is directly tied to userspace activity in
common workloads, and so they have to be part of the minimally viable
configuration in order to present a complete feature to our users.

The cgroup2 interface of the memory controller is far from complete, but
this series, along with the socket memory accounting series, provides
the final semantic changes for the existing memory knobs in the cgroup2
interface, which is scheduled for initial release in the next merge
window.

This patch (of 8):

Remove unused css argument frmo memcg_init_kmem()

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Martijn Coenen
6611d8d761 memcg: only free spare array when readers are done
A spare array holding mem cgroup threshold events is kept around to make
sure we can always safely deregister an event and have an array to store
the new set of events in.

In the scenario where we're going from 1 to 0 registered events, the
pointer to the primary array containing 1 event is copied to the spare
slot, and then the spare slot is freed because no events are left.
However, it is freed before calling synchronize_rcu(), which means
readers may still be accessing threshold->primary after it is freed.

Fixed by only freeing after synchronize_rcu().

Signed-off-by: Martijn Coenen <maco@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Tejun Heo
654a0dd095 cgroup, memcg, writeback: drop spurious rcu locking around mem_cgroup_css_from_page()
In earlier versions, mem_cgroup_css_from_page() could return non-root
css on a legacy hierarchy which can go away and required rcu locking;
however, the eventual version simply returns the root cgroup if memcg is
on a legacy hierarchy and thus doesn't need rcu locking around or in it.
Remove spurious rcu lockings.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Kirill A. Shutemov
53f9263bab mm: rework mapcount accounting to enable 4k mapping of THPs
We're going to allow mapping of individual 4k pages of THP compound.  It
means we need to track mapcount on per small page basis.

Straight-forward approach is to use ->_mapcount in all subpages to track
how many time this subpage is mapped with PMDs or PTEs combined.  But
this is rather expensive: mapping or unmapping of a THP page with PMD
would require HPAGE_PMD_NR atomic operations instead of single we have
now.

The idea is to store separately how many times the page was mapped as
whole -- compound_mapcount.  This frees up ->_mapcount in subpages to
track PTE mapcount.

We use the same approach as with compound page destructor and compound
order to store compound_mapcount: use space in first tail page,
->mapping this time.

Any time we map/unmap whole compound page (THP or hugetlb) -- we
increment/decrement compound_mapcount.  When we map part of compound
page with PTE we operate on ->_mapcount of the subpage.

page_mapcount() counts both: PTE and PMD mappings of the page.

Basically, we have mapcount for a subpage spread over two counters.  It
makes tricky to detect when last mapcount for a page goes away.

We introduced PageDoubleMap() for this.  When we split THP PMD for the
first time and there's other PMD mapping left we offset up ->_mapcount
in all subpages by one and set PG_double_map on the compound page.
These additional references go away with last compound_mapcount.

This approach provides a way to detect when last mapcount goes away on
per small page basis without introducing new overhead for most common
cases.

[akpm@linux-foundation.org: fix typo in comment]
[mhocko@suse.com: ignore partial THP when moving task]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Kirill A. Shutemov
4b471e8898 mm, thp: remove infrastructure for handling splitting PMDs
With new refcounting we don't need to mark PMDs splitting.  Let's drop
code to handle this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Kirill A. Shutemov
3ac808fdd2 mm, thp: remove compound_lock()
We are going to use migration entries to stabilize page counts.  It
means we don't need compound_lock() for that.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Kirill A. Shutemov
f627c2f537 memcg: adjust to support new THP refcounting
As with rmap, with new refcounting we cannot rely on PageTransHuge() to
check if we need to charge size of huge page form the cgroup.  We need
to get information from caller to know whether it was mapped with PMD or
PTE.

We do uncharge when last reference on the page gone.  At that point if
we see PageTransHuge() it means we need to unchange whole huge page.

The tricky part is partial unmap -- when we try to unmap part of huge
page.  We don't do a special handing of this situation, meaning we don't
uncharge the part of huge page unless last user is gone or
split_huge_page() is triggered.  In case of cgroup memory pressure
happens the partial unmapped page will be split through shrinker.  This
should be good enough.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Johannes Weiner
ef12947c9c mm: memcontrol: switch to the updated jump-label API
According to <linux/jump_label.h> the direct use of struct static_key is
deprecated.  Update the socket and slab accounting code accordingly.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reported-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
8e8ae64524 mm: memcontrol: hook up vmpressure to socket pressure
Let the networking stack know when a memcg is under reclaim pressure so
that it can clamp its transmit windows accordingly.

Whenever the reclaim efficiency of a cgroup's LRU lists drops low enough
for a MEDIUM or HIGH vmpressure event to occur, assert a pressure state
in the socket and tcp memory code that tells it to curb consumption
growth from sockets associated with said control group.

Traditionally, vmpressure reports for the entire subtree of a memcg
under pressure, which drops useful information on the individual groups
reclaimed.  However, it's too late to change the userinterface, so add a
second reporting mode that reports on the level of reclaim instead of at
the level of pressure, and use that report for sockets.

vmpressure events are naturally edge triggered, so for hysteresis assert
socket pressure for a second to allow for subsequent vmpressure events
to occur before letting the socket code return to normal.

This will likely need finetuning for a wider variety of workloads, but
for now stick to the vmpressure presets and keep hysteresis simple.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
f7e1cb6ec5 mm: memcontrol: account socket memory in unified hierarchy memory controller
Socket memory can be a significant share of overall memory consumed by
common workloads.  In order to provide reasonable resource isolation in
the unified hierarchy, this type of memory needs to be included in the
tracking/accounting of a cgroup under active memory resource control.

Overhead is only incurred when a non-root control group is created AND
the memory controller is instructed to track and account the memory
footprint of that group.  cgroup.memory=nosocket can be specified on the
boot commandline to override any runtime configuration and forcibly
exclude socket memory from active memory resource control.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.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>
2016-01-14 16:00:49 -08:00
Johannes Weiner
1109208766 mm: memcontrol: move socket code for unified hierarchy accounting
The unified hierarchy memory controller will account socket memory.
Move the infrastructure functions accordingly.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
7941d2145a mm: memcontrol: do not account memory+swap on unified hierarchy
The unified hierarchy memory controller doesn't expose the memory+swap
counter to userspace, but its accounting is hardcoded in all charge
paths right now, including the per-cpu charge cache ("the stock").

To avoid adding yet more pointless memory+swap accounting with the
socket memory support in unified hierarchy, disable the counter
altogether when in unified hierarchy mode.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
80e95fe0fd mm: memcontrol: generalize the socket accounting jump label
The unified hierarchy memory controller is going to use this jump label
as well to control the networking callbacks.  Move it to the memory
controller code and give it a more generic name.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
baac50bbc3 net: tcp_memcontrol: simplify linkage between socket and page counter
There won't be any separate counters for socket memory consumed by
protocols other than TCP in the future.  Remove the indirection and link
sockets directly to their owning memory cgroup.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
e805605c72 net: tcp_memcontrol: sanitize tcp memory accounting callbacks
There won't be a tcp control soft limit, so integrating the memcg code
into the global skmem limiting scheme complicates things unnecessarily.
Replace this with simple and clear charge and uncharge calls--hidden
behind a jump label--to account skb memory.

Note that this is not purely aesthetic: as a result of shoehorning the
per-memcg code into the same memory accounting functions that handle the
global level, the old code would compare the per-memcg consumption
against the smaller of the per-memcg limit and the global limit.  This
allowed the total consumption of multiple sockets to exceed the global
limit, as long as the individual sockets stayed within bounds.  After
this change, the code will always compare the per-memcg consumption to
the per-memcg limit, and the global consumption to the global limit, and
thus close this loophole.

Without a soft limit, the per-memcg memory pressure state in sockets is
generally questionable.  However, we did it until now, so we continue to
enter it when the hard limit is hit, and packets are dropped, to let
other sockets in the cgroup know that they shouldn't grow their transmit
windows, either.  However, keep it simple in the new callback model and
leave memory pressure lazily when the next packet is accepted (as
opposed to doing it synchroneously when packets are processed).  When
packets are dropped, network performance will already be in the toilet,
so that should be a reasonable trade-off.

As described above, consumption is now checked on the per-memcg level
and the global level separately.  Likewise, memory pressure states are
maintained on both the per-memcg level and the global level, and a
socket is considered under pressure when either level asserts as much.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
3d596f7b90 net: tcp_memcontrol: protect all tcp_memcontrol calls by jump-label
Move the jump-label from sock_update_memcg() and sock_release_memcg() to
the callsite, and so eliminate those function calls when socket
accounting is not enabled.

This also eliminates the need for dummy functions because the calls will
be optimized away if the Kconfig options are not enabled.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Johannes Weiner
7d828602e5 mm: memcontrol: export root_mem_cgroup
A later patch will need this symbol in files other than memcontrol.c, so
export it now and replace mem_cgroup_root_css at the same time.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Vladimir Davydov
9ee11ba425 memcg: do not allow to disable tcp accounting after limit is set
There are two bits defined for cg_proto->flags - MEMCG_SOCK_ACTIVATED
and MEMCG_SOCK_ACTIVE - both are set in tcp_update_limit, but the former
is never cleared while the latter can be cleared by unsetting the limit.
This allows to disable tcp socket accounting for new sockets after it
was enabled by writing -1 to memory.kmem.tcp.limit_in_bytes while still
guaranteeing that memcg_socket_limit_enabled static key will be
decremented on memcg destruction.

This functionality looks dubious, because it is not clear what a use
case would be.  By enabling tcp accounting a user accepts the price.  If
they then find the performance degradation unacceptable, they can always
restart their workload with tcp accounting disabled.  It does not seem
there is any need to flip it while the workload is running.

Besides, it contradicts to how kmem accounting API works: writing
whatever to memory.kmem.limit_in_bytes enables kmem accounting for the
cgroup in question, after which it cannot be disabled.  Therefore one
might expect that writing -1 to memory.kmem.tcp.limit_in_bytes just
enables socket accounting w/o limiting it, which might be useful by
itself, but it isn't true.

Since this API peculiarity is not documented anywhere, I propose to drop
it.  This will allow to simplify the code by dropping cg_proto->flags.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: 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>
2016-01-14 16:00:49 -08:00
Vladimir Davydov
230e9fc286 slab: add SLAB_ACCOUNT flag
Currently, if we want to account all objects of a particular kmem cache,
we have to pass __GFP_ACCOUNT to each kmem_cache_alloc call, which is
inconvenient.  This patch introduces SLAB_ACCOUNT flag which if passed
to kmem_cache_create will force accounting for every allocation from
this cache even if __GFP_ACCOUNT is not passed.

This patch does not make any of the existing caches use this flag - it
will be done later in the series.

Note, a cache with SLAB_ACCOUNT cannot be merged with a cache w/o
SLAB_ACCOUNT, because merged caches share the same kmem_cache struct and
hence cannot have different sets of SLAB_* flags.  Thus using this flag
will probably reduce the number of merged slabs even if kmem accounting
is not used (only compiled in).

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Thelen <gthelen@google.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-14 16:00:49 -08:00
Linus Torvalds
34a9304a96 Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:

 - cgroup v2 interface is now official.  It's no longer hidden behind a
   devel flag and can be mounted using the new cgroup2 fs type.

   Unfortunately, cpu v2 interface hasn't made it yet due to the
   discussion around in-process hierarchical resource distribution and
   only memory and io controllers can be used on the v2 interface at the
   moment.

 - The existing documentation which has always been a bit of mess is
   relocated under Documentation/cgroup-v1/. Documentation/cgroup-v2.txt
   is added as the authoritative documentation for the v2 interface.

 - Some features are added through for-4.5-ancestor-test branch to
   enable netfilter xt_cgroup match to use cgroup v2 paths.  The actual
   netfilter changes will be merged through the net tree which pulled in
   the said branch.

 - Various cleanups

* 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: rename cgroup documentations
  cgroup: fix a typo.
  cgroup: Remove resource_counter.txt in Documentation/cgroup-legacy/00-INDEX.
  cgroup: demote subsystem init messages to KERN_DEBUG
  cgroup: Fix uninitialized variable warning
  cgroup: put controller Kconfig options in meaningful order
  cgroup: clean up the kernel configuration menu nomenclature
  cgroup_pids: fix a typo.
  Subject: cgroup: Fix incomplete dd command in blkio documentation
  cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends
  cpuset: Replace all instances of time_t with time64_t
  cgroup: replace unified-hierarchy.txt with a proper cgroup v2 documentation
  cgroup: rename Documentation/cgroups/ to Documentation/cgroup-legacy/
  cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type
2016-01-12 19:20:32 -08:00
Vladimir Davydov
6df38689e0 mm: memcontrol: fix possible memcg leak due to interrupted reclaim
Memory cgroup reclaim can be interrupted with mem_cgroup_iter_break()
once enough pages have been reclaimed, in which case, in contrast to a
full round-trip over a cgroup sub-tree, the current position stored in
mem_cgroup_reclaim_iter of the target cgroup does not get invalidated
and so is left holding the reference to the last scanned cgroup.  If the
target cgroup does not get scanned again (we might have just reclaimed
the last page or all processes might exit and free their memory
voluntary), we will leak it, because there is nobody to put the
reference held by the iterator.

The problem is easy to reproduce by running the following command
sequence in a loop:

    mkdir /sys/fs/cgroup/memory/test
    echo 100M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
    echo $$ > /sys/fs/cgroup/memory/test/cgroup.procs
    memhog 150M
    echo $$ > /sys/fs/cgroup/memory/cgroup.procs
    rmdir test

The cgroups generated by it will never get freed.

This patch fixes this issue by making mem_cgroup_iter avoid taking
reference to the current position.  In order not to hit use-after-free
bug while running reclaim in parallel with cgroup deletion, we make use
of ->css_released cgroup callback to clear references to the dying
cgroup in all reclaim iterators that might refer to it.  This callback
is called right before scheduling rcu work which will free css, so if we
access iter->position from rcu read section, we might be sure it won't
go away under us.

[hannes@cmpxchg.org: clean up css ref handling]
Fixes: 5ac8fb31ad ("mm: memcontrol: convert reclaim iterator to simple css refcounting")
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-29 17:45:49 -08:00
Ross Zwisler
eed67d75b6 cgroup: Fix uninitialized variable warning
Commit 1f7dd3e5a6 ("cgroup: fix handling of multi-destination migration
from subtree_control enabling") introduced the following compiler warning:

mm/memcontrol.c: In function ‘mem_cgroup_can_attach’:
mm/memcontrol.c:4790:9: warning: ‘memcg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   mc.to = memcg;
         ^

Fix this by initializing 'memcg' to NULL.

This was found using gcc (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6).

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2015-12-28 10:42:07 -05:00
Hugh Dickins
25be6a6595 mm: fix kerneldoc on mem_cgroup_replace_page
Whoops, I missed removing the kerneldoc comment of the lrucare arg
removed from mem_cgroup_replace_page; but it's a good comment, keep it.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-12 10:15:34 -08:00
Vladimir Davydov
9516a18a9a memcg: fix memory.high target
When the memory.high threshold is exceeded, try_charge() schedules a
task_work to reclaim the excess.  The reclaim target is set to the
number of pages requested by try_charge().

This is wrong, because try_charge() usually charges more pages than
requested (batch > nr_pages) in order to refill per cpu stocks.  As a
result, a process in a cgroup can easily exceed memory.high
significantly when doing a lot of charges w/o returning to userspace
(e.g.  reading a file in big chunks).

Fix this issue by assuring that when exceeding memory.high a process
reclaims as many pages as were actually charged (i.e.  batch).

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-12 10:15:34 -08:00
Tejun Heo
1f7dd3e5a6 cgroup: fix handling of multi-destination migration from subtree_control enabling
Consider the following v2 hierarchy.

  P0 (+memory) --- P1 (-memory) --- A
                                 \- B
       
P0 has memory enabled in its subtree_control while P1 doesn't.  If
both A and B contain processes, they would belong to the memory css of
P1.  Now if memory is enabled on P1's subtree_control, memory csses
should be created on both A and B and A's processes should be moved to
the former and B's processes the latter.  IOW, enabling controllers
can cause atomic migrations into different csses.

The core cgroup migration logic has been updated accordingly but the
controller migration methods haven't and still assume that all tasks
migrate to a single target css; furthermore, the methods were fed the
css in which subtree_control was updated which is the parent of the
target csses.  pids controller depends on the migration methods to
move charges and this made the controller attribute charges to the
wrong csses often triggering the following warning by driving a
counter negative.

 WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40()
 Modules linked in:
 CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29
 ...
  ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000
  ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00
  ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8
 Call Trace:
  [<ffffffff81551ffc>] dump_stack+0x4e/0x82
  [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0
  [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20
  [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40
  [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0
  [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330
  [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190
  [<ffffffff81189016>] cgroup_attach_task+0x176/0x200
  [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460
  [<ffffffff81189684>] cgroup_procs_write+0x14/0x20
  [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0
  [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190
  [<ffffffff81265f88>] __vfs_write+0x28/0xe0
  [<ffffffff812666fc>] vfs_write+0xac/0x1a0
  [<ffffffff81267019>] SyS_write+0x49/0xb0
  [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76

This patch fixes the bug by removing @css parameter from the three
migration methods, ->can_attach, ->cancel_attach() and ->attach() and
updating cgroup_taskset iteration helpers also return the destination
css in addition to the task being migrated.  All controllers are
updated accordingly.

* Controllers which don't care whether there are one or multiple
  target csses can be converted trivially.  cpu, io, freezer, perf,
  netclassid and netprio fall in this category.

* cpuset's current implementation assumes that there's single source
  and destination and thus doesn't support v2 hierarchy already.  The
  only change made by this patchset is how that single destination css
  is obtained.

* memory migration path already doesn't do anything on v2.  How the
  single destination css is obtained is updated and the prep stage of
  mem_cgroup_can_attach() is reordered to accomodate the change.

* pids is the only controller which was affected by this bug.  It now
  correctly handles multi-destination migrations and no longer causes
  counter underflow from incorrect accounting.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 10:18:21 -05:00
Andrew Morton
6f6461562e mm/memcontrol.c: uninline mem_cgroup_usage
gcc version 5.2.1 20151010 (Debian 5.2.1-22)
$ size mm/memcontrol.o mm/memcontrol.o.before
   text    data     bss     dec     hex filename
  35535    7908      64   43507    a9f3 mm/memcontrol.o
  35762    7908      64   43734    aad6 mm/memcontrol.o.before

Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Mel Gorman
71baba4b92 mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep.  Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep.  The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake.  As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags.  This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@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>
2015-11-06 17:50:42 -08:00
Mel Gorman
d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@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>
2015-11-06 17:50:42 -08:00
Linus Torvalds
2e3078af2c Merge branch 'akpm' (patches from Andrew)
Merge patch-bomb from Andrew Morton:

 - inotify tweaks

 - some ocfs2 updates (many more are awaiting review)

 - various misc bits

 - kernel/watchdog.c updates

 - Some of mm.  I have a huge number of MM patches this time and quite a
   lot of it is quite difficult and much will be held over to next time.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (162 commits)
  selftests: vm: add tests for lock on fault
  mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage
  mm: introduce VM_LOCKONFAULT
  mm: mlock: add new mlock system call
  mm: mlock: refactor mlock, munlock, and munlockall code
  kasan: always taint kernel on report
  mm, slub, kasan: enable user tracking by default with KASAN=y
  kasan: use IS_ALIGNED in memory_is_poisoned_8()
  kasan: Fix a type conversion error
  lib: test_kasan: add some testcases
  kasan: update reference to kasan prototype repo
  kasan: move KASAN_SANITIZE in arch/x86/boot/Makefile
  kasan: various fixes in documentation
  kasan: update log messages
  kasan: accurately determine the type of the bad access
  kasan: update reported bug types for kernel memory accesses
  kasan: update reported bug types for not user nor kernel memory accesses
  mm/kasan: prevent deadlock in kasan reporting
  mm/kasan: don't use kasan shadow pointer in generic functions
  mm/kasan: MODULE_VADDR is not available on all archs
  ...
2015-11-05 23:10:54 -08:00
Michal Hocko
c12176d336 memcg: fix thresholds for 32b architectures.
Commit 424cdc1413 ("memcg: convert threshold to bytes") has fixed a
regression introduced by 3e32cb2e0a ("mm: memcontrol: lockless page
counters") where thresholds were silently converted to use page units
rather than bytes when interpreting the user input.

The fix is not complete, though, as properly pointed out by Ben Hutchings
during stable backport review.  The page count is converted to bytes but
unsigned long is used to hold the value which would be obviously not
sufficient for 32b systems with more than 4G thresholds.  The same applies
to usage as taken from mem_cgroup_usage which might overflow.

Let's remove this bytes vs.  pages internal tracking differences and
handle thresholds in page units internally.  Chage mem_cgroup_usage() to
return the value in page units and revert 424cdc1413 because this should
be sufficient for the consistent handling.  mem_cgroup_read_u64 as the
only users of mem_cgroup_usage outside of the threshold handling code is
converted to give the proper in bytes result.  It is doing that already
for page_counter output so this is more consistent as well.

The value presented to the userspace is still in bytes units.

Fixes: 424cdc1413 ("memcg: convert threshold to bytes")
Fixes: 3e32cb2e0a ("mm: memcontrol: lockless page counters")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
From: Michal Hocko <mhocko@kernel.org>
Subject: memcg-fix-thresholds-for-32b-architectures-fix

Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
From: Andrew Morton <akpm@linux-foundation.org>
Subject: memcg-fix-thresholds-for-32b-architectures-fix-fix

don't attempt to inline mem_cgroup_usage()

The compiler ignores the inline anwyay.  And __always_inlining it adds 600
bytes of goop to the .o file.

Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Johannes Weiner
6071ca5201 mm: page_counter: let page_counter_try_charge() return bool
page_counter_try_charge() currently returns 0 on success and -ENOMEM on
failure, which is surprising behavior given the function name.

Make it follow the expected pattern of try_stuff() functions that return a
boolean true to indicate success, or false for failure.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.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>
2015-11-05 19:34:48 -08:00
Johannes Weiner
f5fc3c5d81 mm: memcontrol: eliminate root memory.current
memory.current on the root level doesn't add anything that wouldn't be
more accurate and detailed using system statistics.  It already doesn't
include slabs, and it'll be a pain to keep in sync when further memory
types are accounted in the memory controller.  Remove it.

Note that this applies to the new unified hierarchy interface only.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins
45637bab30 mm: rename mem_cgroup_migrate to mem_cgroup_replace_page
After v4.3's commit 0610c25daa ("memcg: fix dirty page migration")
mem_cgroup_migrate() doesn't have much to offer in page migration: convert
migrate_misplaced_transhuge_page() to set_page_memcg() instead.

Then rename mem_cgroup_migrate() to mem_cgroup_replace_page(), since its
remaining callers are replace_page_cache_page() and shmem_replace_page():
both of whom passed lrucare true, so just eliminate that argument.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov
df4065516b memcg: simplify and inline __mem_cgroup_from_kmem
Before the previous patch ("memcg: unify slab and other kmem pages
charging"), __mem_cgroup_from_kmem had to handle two types of kmem - slab
pages and pages allocated with alloc_kmem_pages - memcg in the page
struct.  Now we can unify it.  Since after it, this function becomes tiny
we can fold it into mem_cgroup_from_kmem.

[hughd@google.com: move mem_cgroup_from_kmem into list_lru.c]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov
f3ccb2c422 memcg: unify slab and other kmem pages charging
We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and
uncharging kmem pages to memcg, but currently they are not used for
charging slab pages (i.e.  they are only used for charging pages allocated
with alloc_kmem_pages).  The only reason why the slab subsystem uses
special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it
needs to charge to the memcg of kmem cache while memcg_charge_kmem charges
to the memcg that the current task belongs to.

To remove this diversity, this patch adds an extra argument to
__memcg_kmem_charge that can be a pointer to a memcg or NULL.  If it is
not NULL, the function tries to charge to the memcg it points to,
otherwise it charge to the current context.  Next, it makes the slab
subsystem use this function to charge slab pages.

Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only
in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined.  Since
__memcg_kmem_charge stores a pointer to the memcg in the page struct, we
don't need memcg_uncharge_slab anymore and can use free_kmem_pages.
Besides, one can now detect which memcg a slab page belongs to by reading
/proc/kpagecgroup.

Note, this patch switches slab to charge-after-alloc design.  Since this
design is already used for all other memcg charges, it should not make any
difference.

[hannes@cmpxchg.org: better to have an outer function than a magic parameter for the memcg lookup]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.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>
2015-11-05 19:34:48 -08:00
Vladimir Davydov
d05e83a6f8 memcg: simplify charging kmem pages
Charging kmem pages proceeds in two steps.  First, we try to charge the
allocation size to the memcg the current task belongs to, then we allocate
a page and "commit" the charge storing the pointer to the memcg in the
page struct.

Such a design looks overcomplicated, because there is not much sense in
trying charging the allocation before actually allocating a page: we won't
be able to consume much memory over the limit even if we charge after
doing the actual allocation, besides we already charge user pages post
factum, so being pedantic with kmem pages just looks pointless.

So this patch simplifies the design by merging the "charge" and the
"commit" steps into the same function, which takes the allocated page.

Also, rename the charge and uncharge methods to memcg_kmem_charge and
memcg_kmem_uncharge and make the charge method return error code instead
of bool to conform to mem_cgroup_try_charge.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Jerome Marchand
3608de0787 mm/memcontrol.c: fix order calculation in try_charge()
Since commit 6539cc0538 ("mm: memcontrol: fold mem_cgroup_do_charge()"),
the order to pass to mem_cgroup_oom() is calculated by passing the
number of pages to get_order() instead of the expected size in bytes.
AFAICT, it only affects the value displayed in the oom warning message.
This patch fix this.

Michal said:

: We haven't noticed that just because the OOM is enabled only for page
: faults of order-0 (single page) and get_order work just fine.  Thanks for
: noticing this.  If we ever start triggering OOM on different orders this
: would be broken.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tejun Heo
10d53c748b memcg: ratify and consolidate over-charge handling
try_charge() is the main charging logic of memcg.  When it hits the limit
but either can't fail the allocation due to __GFP_NOFAIL or the task is
likely to free memory very soon, being OOM killed, has SIGKILL pending or
exiting, it "bypasses" the charge to the root memcg and returns -EINTR.
While this is one approach which can be taken for these situations, it has
several issues.

* It unnecessarily lies about the reality.  The number itself doesn't
  go over the limit but the actual usage does.  memcg is either forced
  to or actively chooses to go over the limit because that is the
  right behavior under the circumstances, which is completely fine,
  but, if at all avoidable, it shouldn't be misrepresenting what's
  happening by sneaking the charges into the root memcg.

* Despite trying, we already do over-charge.  kmemcg can't deal with
  switching over to the root memcg by the point try_charge() returns
  -EINTR, so it open-codes over-charing.

* It complicates the callers.  Each try_charge() user has to handle
  the weird -EINTR exception.  memcg_charge_kmem() does the manual
  over-charging.  mem_cgroup_do_precharge() performs unnecessary
  uncharging of root memcg, which BTW is inconsistent with what
  memcg_charge_kmem() does but not broken as [un]charging are noops on
  root memcg.  mem_cgroup_try_charge() needs to switch the returned
  cgroup to the root one.

The reality is that in memcg there are cases where we are forced and/or
willing to go over the limit.  Each such case needs to be scrutinized and
justified but there definitely are situations where that is the right
thing to do.  We alredy do this but with a superficial and inconsistent
disguise which leads to unnecessary complications.

This patch updates try_charge() so that it over-charges and returns 0 when
deemed necessary.  -EINTR return is removed along with all special case
handling in the callers.

While at it, remove the local variable @ret, which was initialized to zero
and never changed, along with done: label which just returned the always
zero @ret.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tejun Heo
b23afb93d3 memcg: punt high overage reclaim to return-to-userland path
Currently, try_charge() tries to reclaim memory synchronously when the
high limit is breached; however, if the allocation doesn't have
__GFP_WAIT, synchronous reclaim is skipped.  If a process performs only
speculative allocations, it can blow way past the high limit.  This is
actually easily reproducible by simply doing "find /".  slab/slub
allocator tries speculative allocations first, so as long as there's
memory which can be consumed without blocking, it can keep allocating
memory regardless of the high limit.

This patch makes try_charge() always punt the over-high reclaim to the
return-to-userland path.  If try_charge() detects that high limit is
breached, it adds the overage to current->memcg_nr_pages_over_high and
schedules execution of mem_cgroup_handle_over_high() which performs
synchronous reclaim from the return-to-userland path.

As long as kernel doesn't have a run-away allocation spree, this should
provide enough protection while making kmemcg behave more consistently.
It also has the following benefits.

- All over-high reclaims can use GFP_KERNEL regardless of the specific
  gfp mask in use, e.g. GFP_NOFS, when the limit was breached.

- It copes with prio inversion.  Previously, a low-prio task with
  small memory.high might perform over-high reclaim with a bunch of
  locks held.  If a higher prio task needed any of these locks, it
  would have to wait until the low prio task finished reclaim and
  released the locks.  By handing over-high reclaim to the task exit
  path this issue can be avoided.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tejun Heo
626ebc4100 memcg: flatten task_struct->memcg_oom
task_struct->memcg_oom is a sub-struct containing fields which are used
for async memcg oom handling.  Most task_struct fields aren't packaged
this way and it can lead to unnecessary alignment paddings.  This patch
flattens it.

* task.memcg_oom.memcg          -> task.memcg_in_oom
* task.memcg_oom.gfp_mask	-> task.memcg_oom_gfp_mask
* task.memcg_oom.order          -> task.memcg_oom_order
* task.memcg_oom.may_oom        -> task.memcg_may_oom

In addition, task.memcg_may_oom is relocated to where other bitfields are
which reduces the size of task_struct.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Linus Torvalds
69234acee5 Merge branch 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "The cgroup core saw several significant updates this cycle:

   - percpu_rwsem for threadgroup locking is reinstated.  This was
     temporarily dropped due to down_write latency issues.  Oleg's
     rework of percpu_rwsem which is scheduled to be merged in this
     merge window resolves the issue.

   - On the v2 hierarchy, when controllers are enabled and disabled, all
     operations are atomic and can fail and revert cleanly.  This allows
     ->can_attach() failure which is necessary for cpu RT slices.

   - Tasks now stay associated with the original cgroups after exit
     until released.  This allows tracking resources held by zombies
     (e.g.  pids) and makes it easy to find out where zombies came from
     on the v2 hierarchy.  The pids controller was broken before these
     changes as zombies escaped the limits; unfortunately, updating this
     behavior required too many invasive changes and I don't think it's
     a good idea to backport them, so the pids controller on 4.3, the
     first version which included the pids controller, will stay broken
     at least until I'm sure about the cgroup core changes.

   - Optimization of a couple common tests using static_key"

* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
  cgroup: fix race condition around termination check in css_task_iter_next()
  blkcg: don't create "io.stat" on the root cgroup
  cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
  cgroup: replace error handling in cgroup_init() with WARN_ON()s
  cgroup: add cgroup_subsys->free() method and use it to fix pids controller
  cgroup: keep zombies associated with their original cgroups
  cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
  cgroup: don't hold css_set_rwsem across css task iteration
  cgroup: reorganize css_task_iter functions
  cgroup: factor out css_set_move_task()
  cgroup: keep css_set and task lists in chronological order
  cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
  cgroup: make css_sets pin the associated cgroups
  cgroup: relocate cgroup_[try]get/put()
  cgroup: move check_for_release() invocation
  cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
  cgroup: make cgroup->nr_populated count the number of populated css_sets
  cgroup: remove an unused parameter from cgroup_task_migrate()
  cgroup: fix too early usage of static_branch_disable()
  cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
  ...
2015-11-05 14:51:32 -08:00
Linus Torvalds
ea1ee5ff1b Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block layer fixes from Jens Axboe:
 "A final set of fixes for 4.3.

  It is (again) bigger than I would have liked, but it's all been
  through the testing mill and has been carefully reviewed by multiple
  parties.  Each fix is either a regression fix for this cycle, or is
  marked stable.  You can scold me at KS.  The pull request contains:

   - Three simple fixes for NVMe, fixing regressions since 4.3.  From
     Arnd, Christoph, and Keith.

   - A single xen-blkfront fix from Cathy, fixing a NULL dereference if
     an error is returned through the staste change callback.

   - Fixup for some bad/sloppy code in nbd that got introduced earlier
     in this cycle.  From Markus Pargmann.

   - A blk-mq tagset use-after-free fix from Junichi.

   - A backing device lifetime fix from Tejun, fixing a crash.

   - And finally, a set of regression/stable fixes for cgroup writeback
     from Tejun"

* 'for-linus' of git://git.kernel.dk/linux-block:
  writeback: remove broken rbtree_postorder_for_each_entry_safe() usage in cgwb_bdi_destroy()
  NVMe: Fix memory leak on retried commands
  block: don't release bdi while request_queue has live references
  nvme: use an integer value to Linux errno values
  blk-mq: fix use-after-free in blk_mq_free_tag_set()
  nvme: fix 32-bit build warning
  writeback: fix incorrect calculation of available memory for memcg domains
  writeback: memcg dirty_throttle_control should be initialized with wb->memcg_completions
  writeback: bdi_writeback iteration must not skip dying ones
  writeback: fix bdi_writeback iteration in wakeup_dirtytime_writeback()
  writeback: laptop_mode_timer_fn() needs rcu_read_lock() around bdi_writeback iteration
  nbd: Add locking for tasks
  xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)
2015-10-24 07:20:57 +09:00
Shaohua Li
424cdc1413 memcg: convert threshold to bytes
page_counter_memparse() returns pages for the threshold, while
mem_cgroup_usage() returns bytes for memory usage.  Convert the
threshold to bytes.

Fixes: 3e32cb2e0a ("memcg: rename cgroup_event to mem_cgroup_event").
Signed-off-by: Shaohua Li <shli@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-16 11:42:28 -07:00
Tejun Heo
27bd4dbb8d cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
Currently, cgroup_has_tasks() tests whether the target cgroup has any
css_set linked to it.  This works because a css_set's refcnt converges
with the number of tasks linked to it and thus there's no css_set
linked to a cgroup if it doesn't have any live tasks.

To help tracking resource usage of zombie tasks, putting the ref of
css_set will be separated from disassociating the task from the
css_set which means that a cgroup may have css_sets linked to it even
when it doesn't have any live tasks.

This patch replaces cgroup_has_tasks() with cgroup_is_populated()
which tests cgroup->nr_populated instead which locally counts the
number of populated css_sets.  Unlike cgroup_has_tasks(),
cgroup_is_populated() is recursive - if any of the descendants is
populated, the cgroup is populated too.  While this changes the
meaning of the test, all the existing users are okay with the change.

While at it, replace the open-coded ->populated_cnt test in
cgroup_events_show() with cgroup_is_populated().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
2015-10-15 16:41:50 -04:00
Tejun Heo
c5edf9cdc4 writeback: fix incorrect calculation of available memory for memcg domains
For memcg domains, the amount of available memory was calculated as

 min(the amount currently in use + headroom according to memcg,
     total clean memory)

This isn't quite correct as what should be capped by the amount of
clean memory is the headroom, not the sum of memory in use and
headroom.  For example, if a memcg domain has a significant amount of
dirty memory, the above can lead to a value which is lower than the
current amount in use which doesn't make much sense.  In most
circumstances, the above leads to a number which is somewhat but not
drastically lower.

As the amount of memory which can be readily allocated to the memcg
domain is capped by the amount of system-wide clean memory which is
not already assigned to the memcg itself, the number we want is

 the amount currently in use +
 min(headroom according to memcg, clean memory elsewhere in the system)

This patch updates mem_cgroup_wb_stats() to return the number of
filepages and headroom instead of the calculated available pages.
mdtc_cap_avail() is renamed to mdtc_calc_avail() and performs the
above calculation from file, headroom, dirty and globally clean pages.

v2: Dummy mem_cgroup_wb_stats() implementation wasn't updated leading
    to build failure when !CGROUP_WRITEBACK.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: c2aa723a60 ("writeback: implement memcg writeback domain based throttling")
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-10-12 10:31:13 -06:00
Greg Thelen
ef510194ce memcg: remove pcp_counter_lock
Commit 733a572e66 ("memcg: make mem_cgroup_read_{stat|event}() iterate
possible cpus instead of online") removed the last use of the per memcg
pcp_counter_lock but forgot to remove the variable.

Kill the vestigial variable.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-01 21:42:35 -04:00
Greg Thelen
484ebb3b8c memcg: make mem_cgroup_read_stat() unsigned
mem_cgroup_read_stat() returns a page count by summing per cpu page
counters.  The summing is racy wrt.  updates, so a transient negative
sum is possible.  Callers don't want negative values:

 - mem_cgroup_wb_stats() doesn't want negative nr_dirty or nr_writeback.
   This could confuse dirty throttling.

 - oom reports and memory.stat shouldn't show confusing negative usage.

 - tree_usage() already avoids negatives.

Avoid returning negative page counts from mem_cgroup_read_stat() and
convert it to unsigned.

[akpm@linux-foundation.org: fix old typo while we're in there]
Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-01 21:42:35 -04:00
Tejun Heo
4530eddb59 cgroup, memcg, cpuset: implement cgroup_taskset_for_each_leader()
It wasn't explicitly documented but, when a process is being migrated,
cpuset and memcg depend on cgroup_taskset_first() returning the
threadgroup leader; however, this approach is somewhat ghetto and
would no longer work for the planned multi-process migration.

This patch introduces explicit cgroup_taskset_for_each_leader() which
iterates over only the threadgroup leaders and replaces
cgroup_taskset_first() usages for accessing the leader with it.

This prepares both memcg and cpuset for multi-process migration.  This
patch also updates the documentation for cgroup_taskset_for_each() to
clarify the iteration rules and removes comments mentioning task
ordering in tasksets.

v2: A previous patch which added threadgroup leader test was dropped.
    Patch updated accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
2015-09-22 12:46:53 -04:00
Tejun Heo
472912a2b5 memcg: generate file modified notifications on "memory.events"
cgroup core only recently grew generic notification support.  Wire up
"memory.events" so that it triggers a file modified event whenever its
content changes.

v2: Refreshed on top of mem_cgroup relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizefan@huawei.com>
2015-09-21 15:14:47 -04:00
Tejun Heo
7dbdb199d3 cgroup: replace cftype->mode with CFTYPE_WORLD_WRITABLE
cftype->mode allows controllers to give arbitrary permissions to
interface knobs.  Except for "cgroup.event_control", the existing uses
are spurious.

* Some explicitly specify S_IRUGO | S_IWUSR even though that's the
  default.

* "cpuset.memory_pressure" specifies S_IRUGO while also setting a
  write callback which returns -EACCES.  All it needs to do is simply
  not setting a write callback.

"cgroup.event_control" uses cftype->mode to make the file
world-writable.  It's a misdesigned interface and we don't want
controllers to be tweaking interface file permissions in general.
This patch removes cftype->mode and all its spurious uses and
implements CFTYPE_WORLD_WRITABLE for "cgroup.event_control" which is
marked as compatibility-only.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
2015-09-18 17:54:23 -04:00
Tejun Heo
9e10a130d9 cgroup: replace cgroup_on_dfl() tests in controllers with cgroup_subsys_on_dfl()
cgroup_on_dfl() tests whether the cgroup's root is the default
hierarchy; however, an individual controller is only interested in
whether the controller is attached to the default hierarchy and never
tests a cgroup which doesn't belong to the hierarchy that the
controller is attached to.

This patch replaces cgroup_on_dfl() tests in controllers with faster
static_key based cgroup_subsys_on_dfl().  This leaves cgroup core as
the only user of cgroup_on_dfl() and the function is moved from the
header file to cgroup.c.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
2015-09-18 11:56:28 -04:00
Vladimir Davydov
e993d905c8 memcg: zap try_get_mem_cgroup_from_page
It is only used in mem_cgroup_try_charge, so fold it in and zap it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10 13:29:01 -07:00
Vladimir Davydov
2fc0452470 memcg: add page_cgroup_ino helper
This patchset introduces a new user API for tracking user memory pages
that have not been used for a given period of time.  The purpose of this
is to provide the userspace with the means of tracking a workload's
working set, i.e.  the set of pages that are actively used by the
workload.  Knowing the working set size can be useful for partitioning the
system more efficiently, e.g.  by tuning memory cgroup limits
appropriately, or for job placement within a compute cluster.

==== USE CASES ====

The unified cgroup hierarchy has memory.low and memory.high knobs, which
are defined as the low and high boundaries for the workload working set
size.  However, the working set size of a workload may be unknown or
change in time.  With this patch set, one can periodically estimate the
amount of memory unused by each cgroup and tune their memory.low and
memory.high parameters accordingly, therefore optimizing the overall
memory utilization.

Another use case is balancing workloads within a compute cluster.  Knowing
how much memory is not really used by a workload unit may help take a more
optimal decision when considering migrating the unit to another node
within the cluster.

Also, as noted by Minchan, this would be useful for per-process reclaim
(https://lwn.net/Articles/545668/). With idle tracking, we could reclaim idle
pages only by smart user memory manager.

==== USER API ====

The user API consists of two new files:

 * /sys/kernel/mm/page_idle/bitmap.  This file implements a bitmap where each
   bit corresponds to a page, indexed by PFN. When the bit is set, the
   corresponding page is idle. A page is considered idle if it has not been
   accessed since it was marked idle. To mark a page idle one should set the
   bit corresponding to the page by writing to the file. A value written to the
   file is OR-ed with the current bitmap value. Only user memory pages can be
   marked idle, for other page types input is silently ignored. Writing to this
   file beyond max PFN results in the ENXIO error. Only available when
   CONFIG_IDLE_PAGE_TRACKING is set.

   This file can be used to estimate the amount of pages that are not
   used by a particular workload as follows:

   1. mark all pages of interest idle by setting corresponding bits in the
      /sys/kernel/mm/page_idle/bitmap
   2. wait until the workload accesses its working set
   3. read /sys/kernel/mm/page_idle/bitmap and count the number of bits set

 * /proc/kpagecgroup.  This file contains a 64-bit inode number of the
   memory cgroup each page is charged to, indexed by PFN. Only available when
   CONFIG_MEMCG is set.

   This file can be used to find all pages (including unmapped file pages)
   accounted to a particular cgroup. Using /sys/kernel/mm/page_idle/bitmap, one
   can then estimate the cgroup working set size.

For an example of using these files for estimating the amount of unused
memory pages per each memory cgroup, please see the script attached
below.

==== REASONING ====

The reason to introduce the new user API instead of using
/proc/PID/{clear_refs,smaps} is that the latter has two serious
drawbacks:

 - it does not count unmapped file pages
 - it affects the reclaimer logic

The new API attempts to overcome them both. For more details on how it
is achieved, please see the comment to patch 6.

==== PATCHSET STRUCTURE ====

The patch set is organized as follows:

 - patch 1 adds page_cgroup_ino() helper for the sake of
   /proc/kpagecgroup and patches 2-3 do related cleanup
 - patch 4 adds /proc/kpagecgroup, which reports cgroup ino each page is
   charged to
 - patch 5 introduces a new mmu notifier callback, clear_young, which is
   a lightweight version of clear_flush_young; it is used in patch 6
 - patch 6 implements the idle page tracking feature, including the
   userspace API, /sys/kernel/mm/page_idle/bitmap
 - patch 7 exports idle flag via /proc/kpageflags

==== SIMILAR WORKS ====

Originally, the patch for tracking idle memory was proposed back in 2011
by Michel Lespinasse (see http://lwn.net/Articles/459269/).  The main
difference between Michel's patch and this one is that Michel implemented
a kernel space daemon for estimating idle memory size per cgroup while
this patch only provides the userspace with the minimal API for doing the
job, leaving the rest up to the userspace.  However, they both share the
same idea of Idle/Young page flags to avoid affecting the reclaimer logic.

==== PERFORMANCE EVALUATION ====

SPECjvm2008 (https://www.spec.org/jvm2008/) was used to evaluate the
performance impact introduced by this patch set.  Three runs were carried
out:

 - base: kernel without the patch
 - patched: patched kernel, the feature is not used
 - patched-active: patched kernel, 1 minute-period daemon is used for
   tracking idle memory

For tracking idle memory, idlememstat utility was used:
https://github.com/locker/idlememstat

testcase            base            patched        patched-active

compiler       537.40 ( 0.00)%   532.26 (-0.96)%   538.31 ( 0.17)%
compress       305.47 ( 0.00)%   301.08 (-1.44)%   300.71 (-1.56)%
crypto         284.32 ( 0.00)%   282.21 (-0.74)%   284.87 ( 0.19)%
derby          411.05 ( 0.00)%   413.44 ( 0.58)%   412.07 ( 0.25)%
mpegaudio      189.96 ( 0.00)%   190.87 ( 0.48)%   189.42 (-0.28)%
scimark.large   46.85 ( 0.00)%    46.41 (-0.94)%    47.83 ( 2.09)%
scimark.small  412.91 ( 0.00)%   415.41 ( 0.61)%   421.17 ( 2.00)%
serial         204.23 ( 0.00)%   213.46 ( 4.52)%   203.17 (-0.52)%
startup         36.76 ( 0.00)%    35.49 (-3.45)%    35.64 (-3.05)%
sunflow        115.34 ( 0.00)%   115.08 (-0.23)%   117.37 ( 1.76)%
xml            620.55 ( 0.00)%   619.95 (-0.10)%   620.39 (-0.03)%

composite      211.50 ( 0.00)%   211.15 (-0.17)%   211.67 ( 0.08)%

time idlememstat:

17.20user 65.16system 2:15:23elapsed 1%CPU (0avgtext+0avgdata 8476maxresident)k
448inputs+40outputs (1major+36052minor)pagefaults 0swaps

==== SCRIPT FOR COUNTING IDLE PAGES PER CGROUP ====
#! /usr/bin/python
#

import os
import stat
import errno
import struct

CGROUP_MOUNT = "/sys/fs/cgroup/memory"
BUFSIZE = 8 * 1024  # must be multiple of 8

def get_hugepage_size():
    with open("/proc/meminfo", "r") as f:
        for s in f:
            k, v = s.split(":")
            if k == "Hugepagesize":
                return int(v.split()[0]) * 1024

PAGE_SIZE = os.sysconf("SC_PAGE_SIZE")
HUGEPAGE_SIZE = get_hugepage_size()

def set_idle():
    f = open("/sys/kernel/mm/page_idle/bitmap", "wb", BUFSIZE)
    while True:
        try:
            f.write(struct.pack("Q", pow(2, 64) - 1))
        except IOError as err:
            if err.errno == errno.ENXIO:
                break
            raise
    f.close()

def count_idle():
    f_flags = open("/proc/kpageflags", "rb", BUFSIZE)
    f_cgroup = open("/proc/kpagecgroup", "rb", BUFSIZE)

    with open("/sys/kernel/mm/page_idle/bitmap", "rb", BUFSIZE) as f:
        while f.read(BUFSIZE): pass  # update idle flag

    idlememsz = {}
    while True:
        s1, s2 = f_flags.read(8), f_cgroup.read(8)
        if not s1 or not s2:
            break

        flags, = struct.unpack('Q', s1)
        cgino, = struct.unpack('Q', s2)

        unevictable = (flags >> 18) & 1
        huge = (flags >> 22) & 1
        idle = (flags >> 25) & 1

        if idle and not unevictable:
            idlememsz[cgino] = idlememsz.get(cgino, 0) + \
                (HUGEPAGE_SIZE if huge else PAGE_SIZE)

    f_flags.close()
    f_cgroup.close()
    return idlememsz

if __name__ == "__main__":
    print "Setting the idle flag for each page..."
    set_idle()

    raw_input("Wait until the workload accesses its working set, "
              "then press Enter")

    print "Counting idle pages..."
    idlememsz = count_idle()

    for dir, subdirs, files in os.walk(CGROUP_MOUNT):
        ino = os.stat(dir)[stat.ST_INO]
        print dir + ": " + str(idlememsz.get(ino, 0) / 1024) + " kB"
==== END SCRIPT ====

This patch (of 8):

Add page_cgroup_ino() helper to memcg.

This function returns the inode number of the closest online ancestor of
the memory cgroup a page is charged to.  It is required for exporting
information about which page is charged to which cgroup to userspace,
which will be introduced by a following patch.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10 13:29:01 -07:00
Michal Hocko
e752eb6881 memcg: move memcg_proto_active from sock.h
The only user is sock_update_memcg which is living in memcontrol.c so it
doesn't make much sense to pollute sock.h by this inline helper.  Move it
to memcontrol.c and open code it into its only caller.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.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>
2015-09-08 15:35:28 -07:00
Michal Hocko
a03f1f0589 memcg, tcp_kmem: check for cg_proto in sock_update_memcg
sk_prot->proto_cgroup is allowed to return NULL but sock_update_memcg
doesn't check for NULL.  The function relies on the mem_cgroup_is_root
check because we shouldn't get NULL otherwise because mem_cgroup_from_task
will always return !NULL.

All other callers are checking for NULL and we can safely replace
mem_cgroup_is_root() check by cg_proto != NULL which will be more
straightforward (proto_cgroup returns NULL for the root memcg already).

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.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>
2015-09-08 15:35:28 -07:00
Tejun Heo
9f2115f93b memcg: restructure mem_cgroup_can_attach()
Restructure it to lower nesting level and help the planned threadgroup
leader iteration changes.

This is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Michal Hocko
33398cf2f3 memcg: export struct mem_cgroup
mem_cgroup structure is defined in mm/memcontrol.c currently which means
that the code outside of this file has to use external API even for
trivial access stuff.

This patch exports mm_struct with its dependencies and makes some of the
exported functions inlines.  This even helps to reduce the code size a bit
(make defconfig + CONFIG_MEMCG=y)

  text		data    bss     dec     	 hex 	filename
  12355346        1823792 1089536 15268674         e8fb42 vmlinux.before
  12354970        1823792 1089536 15268298         e8f9ca vmlinux.after

This is not much (370B) but better than nothing.

We also save a function call in some hot paths like callers of
mem_cgroup_count_vm_event which is used for accounting.

The patch doesn't introduce any functional changes.

[vdavykov@parallels.com: inline memcg_kmem_is_active]
[vdavykov@parallels.com: do not expose type outside of CONFIG_MEMCG]
[akpm@linux-foundation.org: memcontrol.h needs eventfd.h for eventfd_ctx]
[akpm@linux-foundation.org: export mem_cgroup_from_task() to modules]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.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>
2015-09-08 15:35:28 -07:00
David Rientjes
54e9e29132 mm, oom: pass an oom order of -1 when triggered by sysrq
The force_kill member of struct oom_control isn't needed if an order of -1
is used instead.  This is the same as order == -1 in struct
compact_control which requires full memory compaction.

This patch introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.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>
2015-09-08 15:35:28 -07:00
David Rientjes
6e0fc46dc2 mm, oom: organize oom context into struct
There are essential elements to an oom context that are passed around to
multiple functions.

Organize these elements into a new struct, struct oom_control, that
specifies the context for an oom condition.

This patch introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Sebastian Andrzej Siewior
ce9ce6659a mm: memcontrol: bring back the VM_BUG_ON() in mem_cgroup_swapout()
Clark stumbled over a VM_BUG_ON() in -RT which was then was removed by
Johannes in commit f371763a79 ("mm: memcontrol: fix false-positive
VM_BUG_ON() on -rt").  The comment before that patch was a tiny bit better
than it is now.  While the patch claimed to fix a false-postive on -RT
this was not the case.  None of the -RT folks ACKed it and it was not a
false positive report.  That was a *real* problem.

This patch updates the comment that is improper because it refers to
"disabled preemption" as a consequence of that lock being taken.  A
spin_lock() disables preemption, true, but in this case the code relies on
the fact that the lock _also_ disables interrupts once it is acquired.
And this is the important detail (which was checked the VM_BUG_ON()) which
needs to be pointed out.  This is the hint one needs while looking at the
code.  It was explained by Johannes on the list that the per-CPU variables
are protected by local_irq_save().  The BUG_ON() was helpful.  This code
has been workarounded in -RT in the meantime.  I wouldn't mind running
into more of those if the code in question uses *special* kind of locking
since now there is no verification (in terms of lockdep or BUG_ON()) and
therefore I bring the VM_BUG_ON() check back in.

The two functions after the comment could also have a "local_irq_save()"
dance around them in order to serialize access to the per-CPU variables.
This has been avoided because the interrupts should be off.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Linus Torvalds
e4bc13adfd Merge branch 'for-4.2/writeback' of git://git.kernel.dk/linux-block
Pull cgroup writeback support from Jens Axboe:
 "This is the big pull request for adding cgroup writeback support.

  This code has been in development for a long time, and it has been
  simmering in for-next for a good chunk of this cycle too.  This is one
  of those problems that has been talked about for at least half a
  decade, finally there's a solution and code to go with it.

  Also see last weeks writeup on LWN:

        http://lwn.net/Articles/648292/"

* 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits)
  writeback, blkio: add documentation for cgroup writeback support
  vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
  writeback: do foreign inode detection iff cgroup writeback is enabled
  v9fs: fix error handling in v9fs_session_init()
  bdi: fix wrong error return value in cgwb_create()
  buffer: remove unusued 'ret' variable
  writeback: disassociate inodes from dying bdi_writebacks
  writeback: implement foreign cgroup inode bdi_writeback switching
  writeback: add lockdep annotation to inode_to_wb()
  writeback: use unlocked_inode_to_wb transaction in inode_congested()
  writeback: implement unlocked_inode_to_wb transaction and use it for stat updates
  writeback: implement [locked_]inode_to_wb_and_lock_list()
  writeback: implement foreign cgroup inode detection
  writeback: make writeback_control track the inode being written back
  writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
  mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use
  writeback: implement memcg writeback domain based throttling
  writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
  writeback: implement memcg wb_domain
  writeback: update wb_over_bg_thresh() to use wb_domain aware operations
  ...
2015-06-25 16:00:17 -07:00
Tejun Heo
c2b42d3cad memcg: convert mem_cgroup->under_oom from atomic_t to int
memcg->under_oom tracks whether the memcg is under OOM conditions and is
an atomic_t counter managed with mem_cgroup_[un]mark_under_oom().  While
atomic_t appears to be simple synchronization-wise, when used as a
synchronization construct like here, it's trickier and more error-prone
due to weak memory ordering rules, especially around atomic_read(), and
false sense of security.

For example, both non-trivial read sites of memcg->under_oom are a bit
problematic although not being actually broken.

* mem_cgroup_oom_register_event()

  It isn't explicit what guarantees the memory ordering between event
  addition and memcg->under_oom check.  This isn't broken only because
  memcg_oom_lock is used for both event list and memcg->oom_lock.

* memcg_oom_recover()

  The lockless test doesn't have any explanation why this would be
  safe.

mem_cgroup_[un]mark_under_oom() are very cold paths and there's no point
in avoiding locking memcg_oom_lock there.  This patch converts
memcg->under_oom from atomic_t to int, puts their modifications under
memcg_oom_lock and documents why the lockless test in
memcg_oom_recover() is safe.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@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>
2015-06-24 17:49:45 -07:00
Tejun Heo
f4b90b70b7 memcg: remove unused mem_cgroup->oom_wakeups
Since commit 4942642080 ("mm: memcg: handle non-error OOM situations
more gracefully"), nobody uses mem_cgroup->oom_wakeups.  Remove it.

While at it, also fold memcg_wakeup_oom() into memcg_oom_recover() which
is its only user.  This cleanup was suggested by Michal.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@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>
2015-06-24 17:49:45 -07:00
Johannes Weiner
dc56401fc9 mm: oom_kill: simplify OOM killer locking
The zonelist locking and the oom_sem are two overlapping locks that are
used to serialize global OOM killing against different things.

The historical zonelist locking serializes OOM kills from allocations with
overlapping zonelists against each other to prevent killing more tasks
than necessary in the same memory domain.  Only when neither tasklists nor
zonelists from two concurrent OOM kills overlap (tasks in separate memcgs
bound to separate nodes) are OOM kills allowed to execute in parallel.

The younger oom_sem is a read-write lock to serialize OOM killing against
the PM code trying to disable the OOM killer altogether.

However, the OOM killer is a fairly cold error path, there is really no
reason to optimize for highly performant and concurrent OOM kills.  And
the oom_sem is just flat-out redundant.

Replace both locking schemes with a single global mutex serializing OOM
kills regardless of context.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Chinner <david@fromorbit.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>
2015-06-24 17:49:43 -07:00
Johannes Weiner
16e951966f mm: oom_kill: clean up victim marking and exiting interfaces
Rename unmark_oom_victim() to exit_oom_victim().  Marking and unmarking
are related in functionality, but the interface is not symmetrical at
all: one is an internal OOM killer function used during the killing, the
other is for an OOM victim to signal its own death on exit later on.
This has locking implications, see follow-up changes.

While at it, rename mark_tsk_oom_victim() to mark_oom_victim(), which
is easier on the eye.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Chinner <david@fromorbit.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>
2015-06-24 17:49:43 -07:00
Johannes Weiner
f371763a79 mm: memcontrol: fix false-positive VM_BUG_ON() on -rt
On -rt, the VM_BUG_ON(!irqs_disabled()) triggers inside the memcg
swapout path because the spin_lock_irq(&mapping->tree_lock) in the
caller doesn't actually disable the hardware interrupts - which is fine,
because on -rt the tophalves run in process context and so we are still
safe from preemption while updating the statistics.

Remove the VM_BUG_ON() but keep the comment of what we rely on.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Clark Williams <williams@redhat.com>
Cc: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-10 16:43:43 -07:00
Vladimir Davydov
7d638093d4 memcg: do not call reclaim if !__GFP_WAIT
When trimming memcg consumption excess (see memory.high), we call
try_to_free_mem_cgroup_pages without checking if we are allowed to sleep
in the current context, which can result in a deadlock.  Fix this.

Fixes: 241994ed86 ("mm: memcontrol: default hierarchy interface for memory")
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-10 16:43:43 -07:00
Tejun Heo
c2aa723a60 writeback: implement memcg writeback domain based throttling
While cgroup writeback support now connects memcg and blkcg so that
writeback IOs are properly attributed and controlled, the IO back
pressure propagation mechanism implemented in balance_dirty_pages()
and its subroutines wasn't aware of cgroup writeback.

Processes belonging to a memcg may have access to only subset of total
memory available in the system and not factoring this into dirty
throttling rendered it completely ineffective for processes under
memcg limits and memcg ended up building a separate ad-hoc degenerate
mechanism directly into vmscan code to limit page dirtying.

The previous patches updated balance_dirty_pages() and its subroutines
so that they can deal with multiple wb_domain's (writeback domains)
and defined per-memcg wb_domain.  Processes belonging to a non-root
memcg are bound to two wb_domains, global wb_domain and memcg
wb_domain, and should be throttled according to IO pressures from both
domains.  This patch updates dirty throttling code so that it repeats
similar calculations for the two domains - the differences between the
two are few and minor - and applies the lower of the two sets of
resulting constraints.

wb_over_bg_thresh(), which controls when background writeback
terminates, is also updated to consider both global and memcg
wb_domains.  It returns true if dirty is over bg_thresh for either
domain.

This makes the dirty throttling mechanism operational for memcg
domains including writeback-bandwidth-proportional dirty page
distribution inside them but the ad-hoc memcg throttling mechanism in
vmscan is still in place.  The next patch will rip it out.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:38:13 -06:00
Tejun Heo
2529bb3aad writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
The amount of available memory to a memcg wb_domain can change as
memcg configuration changes.  A domain's ->dirty_limit exists to
smooth out sudden drops in dirty threshold; however, when a domain's
size actually drops significantly, it hinders the dirty throttling
from adjusting to the new configuration leading to unexpected
behaviors including unnecessary OOM kills.

This patch resolves the issue by adding wb_domain_size_changed() which
resets ->dirty_limit[_tstmp] and making memcg call it on configuration
changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:38:13 -06:00
Tejun Heo
841710aa6e writeback: implement memcg wb_domain
Dirtyable memory is distributed to a wb (bdi_writeback) according to
the relative bandwidth the wb is writing out in the whole system.
This distribution is global - each wb is measured against all other
wb's and gets the proportinately sized portion of the memory in the
whole system.

For cgroup writeback, the amount of dirtyable memory is scoped by
memcg and thus each wb would need to be measured and controlled in its
memcg.  IOW, a wb will belong to two writeback domains - the global
and memcg domains.

The previous patches laid the groundwork to support the two wb_domains
and this patch implements memcg wb_domain.  memcg->cgwb_domain is
initialized on css online and destroyed on css release,
wb->memcg_completions is added, and __wb_writeout_inc() is updated to
increment completions against both global and memcg wb_domains.

The following patches will update balance_dirty_pages() and its
subroutines to actually consider memcg wb_domain for throttling.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:38:13 -06:00
Tejun Heo
733a572e66 memcg: make mem_cgroup_read_{stat|event}() iterate possible cpus instead of online
cpu_possible_mask represents the CPUs which are actually possible
during that boot instance.  For systems which don't support CPU
hotplug, this will match cpu_online_mask exactly in most cases.  Even
for systems which support CPU hotplug, the number of possible CPU
slots is highly unlikely to diverge greatly from the number of online
CPUs.  The only cases where the difference between possible and online
caused problems were when the boot code failed to initialize the
possible mask and left it fully set at NR_CPUS - 1.

As such, most per-cpu constructs allocate for all possible CPUs and
often iterate over the possibles, which also has the benefit of
avoiding the blocking CPU hotplug synchronization.

memcg open codes per-cpu stat counting for mem_cgroup_read_stat() and
mem_cgroup_read_events(), which iterates over online CPUs and handles
CPU hotplug operations explicitly.  This complexity doesn't actually
buy anything.  Switch to iterating over the possibles and drop the
explicit CPU hotplug handling.

Eventually, we want to convert memcg to use percpu_counter instead of
its own custom implementation which also benefits from quick access
w/o summing for cases where larger error margin is acceptable.

This will allow mem_cgroup_read_stat() to be called from non-sleepable
contexts which will be used by cgroup writeback.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:38:12 -06:00
Tejun Heo
52ebea749a writeback: make backing_dev_info host cgroup-specific bdi_writebacks
For the planned cgroup writeback support, on each bdi
(backing_dev_info), each memcg will be served by a separate wb
(bdi_writeback).  This patch updates bdi so that a bdi can host
multiple wbs (bdi_writebacks).

On the default hierarchy, blkcg implicitly enables memcg.  This allows
using memcg's page ownership for attributing writeback IOs, and every
memcg - blkcg combination can be served by its own wb by assigning a
dedicated wb to each memcg.  This means that there may be multiple
wb's of a bdi mapped to the same blkcg.  As congested state is per
blkcg - bdi combination, those wb's should share the same congested
state.  This is achieved by tracking congested state via
bdi_writeback_congested structs which are keyed by blkcg.

bdi->wb remains unchanged and will keep serving the root cgroup.
cgwb's (cgroup wb's) for non-root cgroups are created on-demand or
looked up while dirtying an inode according to the memcg of the page
being dirtied or current task.  Each cgwb is indexed on bdi->cgwb_tree
by its memcg id.  Once an inode is associated with its wb, it can be
retrieved using inode_to_wb().

Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all
pages will keep being associated with bdi->wb.

v3: inode_attach_wb() in account_page_dirtied() moved inside
    mapping_cap_account_dirty() block where it's known to be !NULL.
    Also, an unnecessary NULL check before kfree() removed.  Both
    detected by the kbuild bot.

v2: Updated so that wb association is per inode and wb is per memcg
    rather than blkcg.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:33:35 -06:00
Tejun Heo
ad7fa852d3 memcg: implement mem_cgroup_css_from_page()
Implement mem_cgroup_css_from_page() which returns the
cgroup_subsys_state of the memcg associated with a given page on the
default hierarchy.  This will be used by cgroup writeback support.

This function assumes that page->mem_cgroup association doesn't change
until the page is released, which is true on the default hierarchy as
long as replace_page_cache_page() is not used.  As the only user of
replace_page_cache_page() is FUSE which won't support cgroup writeback
for the time being, this works for now, and replace_page_cache_page()
will soon be updated so that the invariant actually holds.

Note that the RCU protected page->mem_cgroup access is consistent with
other usages across memcg but ultimately incorrect.  These unlocked
accesses are missing required barriers.  page->mem_cgroup should be
made an RCU pointer and updated and accessed using RCU operations.

v4: Instead of triggering WARN, return the root css on the traditional
    hierarchies.  This makes the function a lot easier to deal with
    especially as there's no light way to synchronize against
    hierarchy rebinding.

v3: s/mem_cgroup_migrate()/mem_cgroup_css_from_page()/

v2: Trigger WARN if the function is used on the traditional
    hierarchies and add comment about the assumed invariant.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:33:34 -06:00
Tejun Heo
56161634e4 memcg: add mem_cgroup_root_css
Add global mem_cgroup_root_css which points to the root memcg css.
This will be used by cgroup writeback support.  If memcg is disabled,
it's defined as ERR_PTR(-EINVAL).

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
aCc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:33:33 -06:00
Greg Thelen
c4843a7593 memcg: add per cgroup dirty page accounting
When modifying PG_Dirty on cached file pages, update the new
MEM_CGROUP_STAT_DIRTY counter.  This is done in the same places where
global NR_FILE_DIRTY is managed.  The new memcg stat is visible in the
per memcg memory.stat cgroupfs file.  The most recent past attempt at
this was http://thread.gmane.org/gmane.linux.kernel.cgroups/8632

The new accounting supports future efforts to add per cgroup dirty
page throttling and writeback.  It also helps an administrator break
down a container's memory usage and provides evidence to understand
memcg oom kills (the new dirty count is included in memcg oom kill
messages).

The ability to move page accounting between memcg
(memory.move_charge_at_immigrate) makes this accounting more
complicated than the global counter.  The existing
mem_cgroup_{begin,end}_page_stat() lock is used to serialize move
accounting with stat updates.
Typical update operation:
	memcg = mem_cgroup_begin_page_stat(page)
	if (TestSetPageDirty()) {
		[...]
		mem_cgroup_update_page_stat(memcg)
	}
	mem_cgroup_end_page_stat(memcg)

Summary of mem_cgroup_end_page_stat() overhead:
- Without CONFIG_MEMCG it's a no-op
- With CONFIG_MEMCG and no inter memcg task movement, it's just
  rcu_read_lock()
- With CONFIG_MEMCG and inter memcg  task movement, it's
  rcu_read_lock() + spin_lock_irqsave()

A memcg parameter is added to several routines because their callers
now grab mem_cgroup_begin_page_stat() which returns the memcg later
needed by for mem_cgroup_update_page_stat().

Because mem_cgroup_begin_page_stat() may disable interrupts, some
adjustments are needed:
- move __mark_inode_dirty() from __set_page_dirty() to its caller.
  __mark_inode_dirty() locking does not want interrupts disabled.
- use spin_lock_irqsave(tree_lock) rather than spin_lock_irq() in
  __delete_from_page_cache(), replace_page_cache_page(),
  invalidate_complete_page2(), and __remove_mapping().

   text    data     bss      dec    hex filename
8925147 1774832 1785856 12485835 be84cb vmlinux-!CONFIG_MEMCG-before
8925339 1774832 1785856 12486027 be858b vmlinux-!CONFIG_MEMCG-after
                            +192 text bytes
8965977 1784992 1785856 12536825 bf4bf9 vmlinux-CONFIG_MEMCG-before
8966750 1784992 1785856 12537598 bf4efe vmlinux-CONFIG_MEMCG-after
                            +773 text bytes

Performance tests run on v4.0-rc1-36-g4f671fe2f952.  Lower is better for
all metrics, they're all wall clock or cycle counts.  The read and write
fault benchmarks just measure fault time, they do not include I/O time.

* CONFIG_MEMCG not set:
                            baseline                              patched
  kbuild                 1m25.030000(+-0.088% 3 samples)       1m25.426667(+-0.120% 3 samples)
  dd write 100 MiB          0.859211561 +-15.10%                  0.874162885 +-15.03%
  dd write 200 MiB          1.670653105 +-17.87%                  1.669384764 +-11.99%
  dd write 1000 MiB         8.434691190 +-14.15%                  8.474733215 +-14.77%
  read fault cycles       254.0(+-0.000% 10 samples)            253.0(+-0.000% 10 samples)
  write fault cycles     2021.2(+-3.070% 10 samples)           1984.5(+-1.036% 10 samples)

* CONFIG_MEMCG=y root_memcg:
                            baseline                              patched
  kbuild                 1m25.716667(+-0.105% 3 samples)       1m25.686667(+-0.153% 3 samples)
  dd write 100 MiB          0.855650830 +-14.90%                  0.887557919 +-14.90%
  dd write 200 MiB          1.688322953 +-12.72%                  1.667682724 +-13.33%
  dd write 1000 MiB         8.418601605 +-14.30%                  8.673532299 +-15.00%
  read fault cycles       266.0(+-0.000% 10 samples)            266.0(+-0.000% 10 samples)
  write fault cycles     2051.7(+-1.349% 10 samples)           2049.6(+-1.686% 10 samples)

* CONFIG_MEMCG=y non-root_memcg:
                            baseline                              patched
  kbuild                 1m26.120000(+-0.273% 3 samples)       1m25.763333(+-0.127% 3 samples)
  dd write 100 MiB          0.861723964 +-15.25%                  0.818129350 +-14.82%
  dd write 200 MiB          1.669887569 +-13.30%                  1.698645885 +-13.27%
  dd write 1000 MiB         8.383191730 +-14.65%                  8.351742280 +-14.52%
  read fault cycles       265.7(+-0.172% 10 samples)            267.0(+-0.000% 10 samples)
  write fault cycles     2070.6(+-1.512% 10 samples)           2084.4(+-2.148% 10 samples)

As expected anon page faults are not affected by this patch.

tj: Updated to apply on top of the recent cancel_dirty_page() changes.

Signed-off-by: Sha Zhengju <handai.szj@gmail.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02 08:33:33 -06:00
Jason Low
4db0c3c298 mm: remove rest of ACCESS_ONCE() usages
We converted some of the usages of ACCESS_ONCE to READ_ONCE in the mm/
tree since it doesn't work reliably on non-scalar types.

This patch removes the rest of the usages of ACCESS_ONCE, and use the new
READ_ONCE API for the read accesses.  This makes things cleaner, instead
of using separate/multiple sets of APIs.

Signed-off-by: Jason Low <jason.low2@hp.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:35:18 -07:00
Vladimir Davydov
2564f683d1 memcg: remove obsolete comment
Low and high watermarks, as they defined in the TODO to the mem_cgroup
struct, have already been implemented by Johannes, so remove the stale
comment.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:35:16 -07:00
Vladimir Davydov
adbe427b92 memcg: zap mem_cgroup_lookup()
mem_cgroup_lookup() is a wrapper around mem_cgroup_from_id(), which
checks that id != 0 before issuing the function call.  Today, there is
no point in this additional check apart from optimization, because there
is no css with id <= 0, so that css_from_id, called by
mem_cgroup_from_id, will return NULL for any id <= 0.

Since mem_cgroup_from_id is only called from mem_cgroup_lookup, let us
zap mem_cgroup_lookup, substituting calls to it with mem_cgroup_from_id
and moving the check if id > 0 to css_from_id.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@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>
2015-04-15 16:35:16 -07:00
Balasubramani Vivekanandan
2415b9f5cb memcg: print cgroup information when system panics due to panic_on_oom
If kernel panics due to oom, caused by a cgroup reaching its limit, when
'compulsory panic_on_oom' is enabled, then we will only see that the OOM
happened because of "compulsory panic_on_oom is enabled" but this doesn't
tell the difference between mempolicy and memcg.  And dumping system wide
information is plain wrong and more confusing.  This patch provides the
information of the cgroup whose limit triggerred panic

Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
Acked-by: Michal Hocko <mhocko@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>
2015-04-14 16:49:05 -07:00
Chen Gang
b1b0deabbf mm: memcontrol: let mem_cgroup_move_account() have effect only if MMU enabled
When !MMU, it will report warning. The related warning with allmodconfig
under c6x:

    CC      mm/memcontrol.o
  mm/memcontrol.c:2802:12: warning: 'mem_cgroup_move_account' defined but not used [-Wunused-function]
   static int mem_cgroup_move_account(struct page *page,
              ^

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14 16:49:04 -07:00
Johannes Weiner
1575e68b3c mm: memcontrol: update copyright notice
Add myself to the list of copyright holders.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14 16:49:00 -07:00
Vladimir Davydov
7feee590bb memcg: disable hierarchy support if bound to the legacy cgroup hierarchy
If the memory cgroup controller is initially mounted in the scope of the
default cgroup hierarchy and then remounted to a legacy hierarchy, it will
still have hierarchy support enabled, which is incorrect.  We should
disable hierarchy support if bound to the legacy cgroup hierarchy.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-03-12 18:46:08 -07:00
Johannes Weiner
d2973697b3 mm: memcontrol: use "max" instead of "infinity" in control knobs
The memcg control knobs indicate the highest possible value using the
symbolic name "infinity", which is long and awkward to type.

Switch to the string "max", which is just as descriptive but shorter and
sweeter.

This changes a user interface, so do it before the release and before
the development flag is dropped from the default hierarchy.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-28 09:57:51 -08:00
Michal Hocko
4e54dede38 memcg: fix low limit calculation
A memcg is considered low limited even when the current usage is equal to
the low limit.  This leads to interesting side effects e.g.
groups/hierarchies with no memory accounted are considered protected and
so the reclaim will emit MEMCG_LOW event when encountering them.

Another and much bigger issue was reported by Joonsoo Kim.  He has hit a
NULL ptr dereference with the legacy cgroup API which even doesn't have
low limit exposed.  The limit is 0 by default but the initial check fails
for memcg with 0 consumption and parent_mem_cgroup() would return NULL if
use_hierarchy is 0 and so page_counter_read would try to dereference NULL.

I suppose that the current implementation is just an overlook because the
documentation in Documentation/cgroups/unified-hierarchy.txt says:

  "The memory.low boundary on the other hand is a top-down allocated
  reserve.  A cgroup enjoys reclaim protection when it and all its
  ancestors are below their low boundaries"

Fix the usage and the low limit comparision in mem_cgroup_low accordingly.

Fixes: 241994ed86 (mm: memcontrol: default hierarchy interface for memory)
Reported-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-28 09:57:51 -08:00
Vladimir Davydov
f48b80a5e2 memcg: cleanup static keys decrement
Move memcg_socket_limit_enabled decrement to tcp_destroy_cgroup (called
from memcg_destroy_kmem -> mem_cgroup_sockets_destroy) and zap a bunch of
wrapper functions.

Although this patch moves static keys decrement from __mem_cgroup_free to
mem_cgroup_css_free, it does not introduce any functional changes, because
the keys are incremented on setting the limit (tcp or kmem), which can
only happen after successful mem_cgroup_css_online.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:10 -08:00
Vladimir Davydov
2788cf0c40 memcg: reparent list_lrus and free kmemcg_id on css offline
Now, the only reason to keep kmemcg_id till css free is list_lru, which
uses it to distribute elements between per-memcg lists.  However, it can
be easily sorted out - we only need to change kmemcg_id of an offline
cgroup to its parent's id, making further list_lru_add()'s add elements to
the parent's list, and then move all elements from the offline cgroup's
list to the one of its parent.  It will work, because a racing
list_lru_del() does not need to know the list it is deleting the element
from.  It can decrement the wrong nr_items counter though, but the ongoing
reparenting will fix it.  After list_lru reparenting is done we are free
to release kmemcg_id saving a valuable slot in a per-memcg array for new
cgroups.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@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>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:10 -08:00
Vladimir Davydov
2a4db7eb93 memcg: free memcg_caches slot on css offline
We need to look up a kmem_cache in ->memcg_params.memcg_caches arrays only
on allocations, so there is no need to have the array entries set until
css free - we can clear them on css offline.  This will allow us to reuse
array entries more efficiently and avoid costly array relocations.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@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>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:10 -08:00
Vladimir Davydov
f7ce3190c4 slab: embed memcg_cache_params to kmem_cache
Currently, kmem_cache stores a pointer to struct memcg_cache_params
instead of embedding it.  The rationale is to save memory when kmem
accounting is disabled.  However, the memcg_cache_params has shrivelled
drastically since it was first introduced:

* Initially:

struct memcg_cache_params {
	bool is_root_cache;
	union {
		struct kmem_cache *memcg_caches[0];
		struct {
			struct mem_cgroup *memcg;
			struct list_head list;
			struct kmem_cache *root_cache;
			bool dead;
			atomic_t nr_pages;
			struct work_struct destroy;
		};
	};
};

* Now:

struct memcg_cache_params {
	bool is_root_cache;
	union {
		struct {
			struct rcu_head rcu_head;
			struct kmem_cache *memcg_caches[0];
		};
		struct {
			struct mem_cgroup *memcg;
			struct kmem_cache *root_cache;
		};
	};
};

So the memory saving does not seem to be a clear win anymore.

OTOH, keeping a pointer to memcg_cache_params struct instead of embedding
it results in touching one more cache line on kmem alloc/free hot paths.
Besides, it makes linking kmem caches in a list chained by a field of
struct memcg_cache_params really painful due to a level of indirection,
while I want to make them linked in the following patch.  That said, let
us embed it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@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>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00
Vladimir Davydov
60d3fd32a7 list_lru: introduce per-memcg lists
There are several FS shrinkers, including super_block::s_shrink, that
keep reclaimable objects in the list_lru structure.  Hence to turn them
to memcg-aware shrinkers, it is enough to make list_lru per-memcg.

This patch does the trick.  It adds an array of lru lists to the
list_lru_node structure (per-node part of the list_lru), one for each
kmem-active memcg, and dispatches every item addition or removal to the
list corresponding to the memcg which the item is accounted to.  So now
the list_lru structure is not just per node, but per node and per memcg.

Not all list_lrus need this feature, so this patch also adds a new
method, list_lru_init_memcg, which initializes a list_lru as memcg
aware.  Otherwise (i.e.  if initialized with old list_lru_init), the
list_lru won't have per memcg lists.

Just like per memcg caches arrays, the arrays of per-memcg lists are
indexed by memcg_cache_id, so we must grow them whenever
memcg_nr_cache_ids is increased.  So we introduce a callback,
memcg_update_all_list_lrus, invoked by memcg_alloc_cache_id if the id
space is full.

The locking is implemented in a manner similar to lruvecs, i.e.  we have
one lock per node that protects all lists (both global and per cgroup) on
the node.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00
Vladimir Davydov
05257a1a3d memcg: add rwsem to synchronize against memcg_caches arrays relocation
We need a stable value of memcg_nr_cache_ids in kmem_cache_create()
(memcg_alloc_cache_params() wants it for root caches), where we only
hold the slab_mutex and no memcg-related locks.  As a result, we have to
update memcg_nr_cache_ids under the slab_mutex, which we can only take
on the slab's side (see memcg_update_array_size).  This looks awkward
and will become even worse when per-memcg list_lru is introduced, which
also wants stable access to memcg_nr_cache_ids.

To get rid of this dependency between the memcg_nr_cache_ids and the
slab_mutex, this patch introduces a special rwsem.  The rwsem is held
for writing during memcg_caches arrays relocation and memcg_nr_cache_ids
updates.  Therefore one can take it for reading to get a stable access
to memcg_caches arrays and/or memcg_nr_cache_ids.

Currently the semaphore is taken for reading only from
kmem_cache_create, right before taking the slab_mutex, so right now
there's no much point in using rwsem instead of mutex.  However, once
list_lru is made per-memcg it will allow list_lru initializations to
proceed concurrently.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00
Vladimir Davydov
dbcf73e26c memcg: rename some cache id related variables
memcg_limited_groups_array_size, which defines the size of memcg_caches
arrays, sounds rather cumbersome.  Also it doesn't point anyhow that
it's related to kmem/caches stuff.  So let's rename it to
memcg_nr_cache_ids.  It's concise and points us directly to
memcg_cache_id.

Also, rename kmem_limited_groups to memcg_cache_ida.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00
Vladimir Davydov
cb731d6c62 vmscan: per memory cgroup slab shrinkers
This patch adds SHRINKER_MEMCG_AWARE flag.  If a shrinker has this flag
set, it will be called per memory cgroup.  The memory cgroup to scan
objects from is passed in shrink_control->memcg.  If the memory cgroup
is NULL, a memcg aware shrinker is supposed to scan objects from the
global list.  Unaware shrinkers are only called on global pressure with
memcg=NULL.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00
Naoya Horiguchi
26bcd64aa9 memcg: cleanup preparation for page table walk
pagewalk.c can handle vma in itself, so we don't have to pass vma via
walk->private.  And both of mem_cgroup_count_precharge() and
mem_cgroup_move_charge() do for each vma loop themselves, but now it's
done in pagewalk.c, so let's clean up them.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:06 -08:00
Johannes Weiner
21afa38eed mm: memcontrol: consolidate swap controller code
The swap controller code is scattered all over the file.  Gather all
the code that isn't directly needed by the memory controller at the
end of the file in its own CONFIG_MEMCG_SWAP section.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:03 -08:00
Johannes Weiner
95a045f63d mm: memcontrol: consolidate memory controller initialization
The initialization code for the per-cpu charge stock and the soft
limit tree is compact enough to inline it into mem_cgroup_init().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:03 -08:00
Johannes Weiner
9c608dbe6a mm: memcontrol: simplify soft limit tree init code
- No need to test the node for N_MEMORY.  node_online() is enough for
  node fallback to work in slab, use NUMA_NO_NODE for everything else.

- Remove the BUG_ON() for allocation failure.  A NULL pointer crash is
  just as descriptive, and the absent return value check is obvious.

- Move local variables to the inner-most blocks.

- Point to the tree structure after its initialized, not before, it's
  just more logical that way.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:03 -08:00
Michal Hocko
c32b3cbe0d oom, PM: make OOM detection in the freezer path raceless
Commit 5695be142e ("OOM, PM: OOM killed task shouldn't escape PM
suspend") has left a race window when OOM killer manages to
note_oom_kill after freeze_processes checks the counter.  The race
window is quite small and really unlikely and partial solution deemed
sufficient at the time of submission.

Tejun wasn't happy about this partial solution though and insisted on a
full solution.  That requires the full OOM and freezer's task freezing
exclusion, though.  This is done by this patch which introduces oom_sem
RW lock and turns oom_killer_disable() into a full OOM barrier.

oom_killer_disabled check is moved from the allocation path to the OOM
level and we take oom_sem for reading for both the check and the whole
OOM invocation.

oom_killer_disable() takes oom_sem for writing so it waits for all
currently running OOM killer invocations.  Then it disable all the further
OOMs by setting oom_killer_disabled and checks for any oom victims.
Victims are counted via mark_tsk_oom_victim resp.  unmark_oom_victim.  The
last victim wakes up all waiters enqueued by oom_killer_disable().
Therefore this function acts as the full OOM barrier.

The page fault path is covered now as well although it was assumed to be
safe before.  As per Tejun, "We used to have freezing points deep in file
system code which may be reacheable from page fault." so it would be
better and more robust to not rely on freezing points here.  Same applies
to the memcg OOM killer.

out_of_memory tells the caller whether the OOM was allowed to trigger and
the callers are supposed to handle the situation.  The page allocation
path simply fails the allocation same as before.  The page fault path will
retry the fault (more on that later) and Sysrq OOM trigger will simply
complain to the log.

Normally there wouldn't be any unfrozen user tasks after
try_to_freeze_tasks so the function will not block. But if there was an
OOM killer racing with try_to_freeze_tasks and the OOM victim didn't
finish yet then we have to wait for it. This should complete in a finite
time, though, because

	- the victim cannot loop in the page fault handler (it would die
	  on the way out from the exception)
	- it cannot loop in the page allocator because all the further
	  allocation would fail and __GFP_NOFAIL allocations are not
	  acceptable at this stage
	- it shouldn't be blocked on any locks held by frozen tasks
	  (try_to_freeze expects lockless context) and kernel threads and
	  work queues are not frozen yet

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Suggested-by: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:03 -08:00
Michal Hocko
49550b6055 oom: add helpers for setting and clearing TIF_MEMDIE
This patchset addresses a race which was described in the changelog for
5695be142e ("OOM, PM: OOM killed task shouldn't escape PM suspend"):

: PM freezer relies on having all tasks frozen by the time devices are
: getting frozen so that no task will touch them while they are getting
: frozen.  But OOM killer is allowed to kill an already frozen task in order
: to handle OOM situtation.  In order to protect from late wake ups OOM
: killer is disabled after all tasks are frozen.  This, however, still keeps
: a window open when a killed task didn't manage to die by the time
: freeze_processes finishes.

The original patch hasn't closed the race window completely because that
would require a more complex solution as it can be seen by this patchset.

The primary motivation was to close the race condition between OOM killer
and PM freezer _completely_.  As Tejun pointed out, even though the race
condition is unlikely the harder it would be to debug weird bugs deep in
the PM freezer when the debugging options are reduced considerably.  I can
only speculate what might happen when a task is still runnable
unexpectedly.

On a plus side and as a side effect the oom enable/disable has a better
(full barrier) semantic without polluting hot paths.

I have tested the series in KVM with 100M RAM:
- many small tasks (20M anon mmap) which are triggering OOM continually
- s2ram which resumes automatically is triggered in a loop
	echo processors > /sys/power/pm_test
	while true
	do
		echo mem > /sys/power/state
		sleep 1s
	done
- simple module which allocates and frees 20M in 8K chunks. If it sees
  freezing(current) then it tries another round of allocation before calling
  try_to_freeze
- debugging messages of PM stages and OOM killer enable/disable/fail added
  and unmark_oom_victim is delayed by 1s after it clears TIF_MEMDIE and before
  it wakes up waiters.
- rebased on top of the current mmotm which means some necessary updates
  in mm/oom_kill.c. mark_tsk_oom_victim is now called under task_lock but
  I think this should be OK because __thaw_task shouldn't interfere with any
  locking down wake_up_process. Oleg?

As expected there are no OOM killed tasks after oom is disabled and
allocations requested by the kernel thread are failing after all the tasks
are frozen and OOM disabled.  I wasn't able to catch a race where
oom_killer_disable would really have to wait but I kinda expected the race
is really unlikely.

[  242.609330] Killed process 2992 (mem_eater) total-vm:24412kB, anon-rss:2164kB, file-rss:4kB
[  243.628071] Unmarking 2992 OOM victim. oom_victims: 1
[  243.636072] (elapsed 2.837 seconds) done.
[  243.641985] Trying to disable OOM killer
[  243.643032] Waiting for concurent OOM victims
[  243.644342] OOM killer disabled
[  243.645447] Freezing remaining freezable tasks ... (elapsed 0.005 seconds) done.
[  243.652983] Suspending console(s) (use no_console_suspend to debug)
[  243.903299] kmem_eater: page allocation failure: order:1, mode:0x204010
[...]
[  243.992600] PM: suspend of devices complete after 336.667 msecs
[  243.993264] PM: late suspend of devices complete after 0.660 msecs
[  243.994713] PM: noirq suspend of devices complete after 1.446 msecs
[  243.994717] ACPI: Preparing to enter system sleep state S3
[  243.994795] PM: Saving platform NVS memory
[  243.994796] Disabling non-boot CPUs ...

The first 2 patches are simple cleanups for OOM.  They should go in
regardless the rest IMO.

Patches 3 and 4 are trivial printk -> pr_info conversion and they should
go in ditto.

The main patch is the last one and I would appreciate acks from Tejun and
Rafael.  I think the OOM part should be OK (except for __thaw_task vs.
task_lock where a look from Oleg would appreciated) but I am not so sure I
haven't screwed anything in the freezer code.  I have found several
surprises there.

This patch (of 5):

This patch is just a preparatory and it doesn't introduce any functional
change.

Note:
I am utterly unhappy about lowmemory killer abusing TIF_MEMDIE just to
wait for the oom victim and to prevent from new killing. This is
just a side effect of the flag. The primary meaning is to give the oom
victim access to the memory reserves and that shouldn't be necessary
here.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:03 -08:00
Johannes Weiner
1dfab5abcd mm: memcontrol: fold move_anon() and move_file()
Turn the move type enum into flags and give the flags field a shorter
name.  Once that is done, move_anon() and move_file() are simple enough to
just fold them into the callsites.

[akpm@linux-foundation.org: tweak MOVE_MASK definition, per Michal]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:02 -08:00
Johannes Weiner
241994ed86 mm: memcontrol: default hierarchy interface for memory
Introduce the basic control files to account, partition, and limit
memory using cgroups in default hierarchy mode.

This interface versioning allows us to address fundamental design
issues in the existing memory cgroup interface, further explained
below.  The old interface will be maintained indefinitely, but a
clearer model and improved workload performance should encourage
existing users to switch over to the new one eventually.

The control files are thus:

  - memory.current shows the current consumption of the cgroup and its
    descendants, in bytes.

  - memory.low configures the lower end of the cgroup's expected
    memory consumption range.  The kernel considers memory below that
    boundary to be a reserve - the minimum that the workload needs in
    order to make forward progress - and generally avoids reclaiming
    it, unless there is an imminent risk of entering an OOM situation.

  - memory.high configures the upper end of the cgroup's expected
    memory consumption range.  A cgroup whose consumption grows beyond
    this threshold is forced into direct reclaim, to work off the
    excess and to throttle new allocations heavily, but is generally
    allowed to continue and the OOM killer is not invoked.

  - memory.max configures the hard maximum amount of memory that the
    cgroup is allowed to consume before the OOM killer is invoked.

  - memory.events shows event counters that indicate how often the
    cgroup was reclaimed while below memory.low, how often it was
    forced to reclaim excess beyond memory.high, how often it hit
    memory.max, and how often it entered OOM due to memory.max.  This
    allows users to identify configuration problems when observing a
    degradation in workload performance.  An overcommitted system will
    have an increased rate of low boundary breaches, whereas increased
    rates of high limit breaches, maximum hits, or even OOM situations
    will indicate internally overcommitted cgroups.

For existing users of memory cgroups, the following deviations from
the current interface are worth pointing out and explaining:

  - The original lower boundary, the soft limit, is defined as a limit
    that is per default unset.  As a result, the set of cgroups that
    global reclaim prefers is opt-in, rather than opt-out.  The costs
    for optimizing these mostly negative lookups are so high that the
    implementation, despite its enormous size, does not even provide
    the basic desirable behavior.  First off, the soft limit has no
    hierarchical meaning.  All configured groups are organized in a
    global rbtree and treated like equal peers, regardless where they
    are located in the hierarchy.  This makes subtree delegation
    impossible.  Second, the soft limit reclaim pass is so aggressive
    that it not just introduces high allocation latencies into the
    system, but also impacts system performance due to overreclaim, to
    the point where the feature becomes self-defeating.

    The memory.low boundary on the other hand is a top-down allocated
    reserve.  A cgroup enjoys reclaim protection when it and all its
    ancestors are below their low boundaries, which makes delegation
    of subtrees possible.  Secondly, new cgroups have no reserve per
    default and in the common case most cgroups are eligible for the
    preferred reclaim pass.  This allows the new low boundary to be
    efficiently implemented with just a minor addition to the generic
    reclaim code, without the need for out-of-band data structures and
    reclaim passes.  Because the generic reclaim code considers all
    cgroups except for the ones running low in the preferred first
    reclaim pass, overreclaim of individual groups is eliminated as
    well, resulting in much better overall workload performance.

  - The original high boundary, the hard limit, is defined as a strict
    limit that can not budge, even if the OOM killer has to be called.
    But this generally goes against the goal of making the most out of
    the available memory.  The memory consumption of workloads varies
    during runtime, and that requires users to overcommit.  But doing
    that with a strict upper limit requires either a fairly accurate
    prediction of the working set size or adding slack to the limit.
    Since working set size estimation is hard and error prone, and
    getting it wrong results in OOM kills, most users tend to err on
    the side of a looser limit and end up wasting precious resources.

    The memory.high boundary on the other hand can be set much more
    conservatively.  When hit, it throttles allocations by forcing
    them into direct reclaim to work off the excess, but it never
    invokes the OOM killer.  As a result, a high boundary that is
    chosen too aggressively will not terminate the processes, but
    instead it will lead to gradual performance degradation.  The user
    can monitor this and make corrections until the minimal memory
    footprint that still gives acceptable performance is found.

    In extreme cases, with many concurrent allocations and a complete
    breakdown of reclaim progress within the group, the high boundary
    can be exceeded.  But even then it's mostly better to satisfy the
    allocation from the slack available in other groups or the rest of
    the system than killing the group.  Otherwise, memory.max is there
    to limit this type of spillover and ultimately contain buggy or
    even malicious applications.

  - The original control file names are unwieldy and inconsistent in
    many different ways.  For example, the upper boundary hit count is
    exported in the memory.failcnt file, but an OOM event count has to
    be manually counted by listening to memory.oom_control events, and
    lower boundary / soft limit events have to be counted by first
    setting a threshold for that value and then counting those events.
    Also, usage and limit files encode their units in the filename.
    That makes the filenames very long, even though this is not
    information that a user needs to be reminded of every time they
    type out those names.

    To address these naming issues, as well as to signal clearly that
    the new interface carries a new configuration model, the naming
    conventions in it necessarily differ from the old interface.

  - The original limit files indicate the state of an unset limit with
    a very high number, and a configured limit can be unset by echoing
    -1 into those files.  But that very high number is implementation
    and architecture dependent and not very descriptive.  And while -1
    can be understood as an underflow into the highest possible value,
    -2 or -10M etc. do not work, so it's not inconsistent.

    memory.low, memory.high, and memory.max will use the string
    "infinity" to indicate and set the highest possible value.

[akpm@linux-foundation.org: use seq_puts() for basic strings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:02 -08:00
Johannes Weiner
650c5e5654 mm: page_counter: pull "-1" handling out of page_counter_memparse()
The unified hierarchy interface for memory cgroups will no longer use "-1"
to mean maximum possible resource value.  In preparation for this, make
the string an argument and let the caller supply it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:02 -08:00
Greg Thelen
0ca44b148e memcg: add BUILD_BUG_ON() for string tables
Use BUILD_BUG_ON() to compile assert that memcg string tables are in sync
with corresponding enums.  There aren't currently any issues with these
tables.  This is just defensive.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:02 -08:00
Vladimir Davydov
90cbc25088 vmscan: force scan offline memory cgroups
Since commit b2052564e6 ("mm: memcontrol: continue cache reclaim from
offlined groups") pages charged to a memory cgroup are not reparented when
the cgroup is removed.  Instead, they are supposed to be reclaimed in a
regular way, along with pages accounted to online memory cgroups.

However, an lruvec of an offline memory cgroup will sooner or later get so
small that it will be scanned only at low scan priorities (see
get_scan_count()).  Therefore, if there are enough reclaimable pages in
big lruvecs, pages accounted to offline memory cgroups will never be
scanned at all, wasting memory.

Fix this by unconditionally forcing scanning dead lruvecs from kswapd.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.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>
2015-02-11 17:06:02 -08:00
Johannes Weiner
6de226191d mm: memcontrol: track move_lock state internally
The complexity of memcg page stat synchronization is currently leaking
into the callsites, forcing them to keep track of the move_lock state and
the IRQ flags.  Simplify the API by tracking it in the memcg.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:00 -08:00
Vladimir Davydov
d5b3cf7139 memcg: zap memcg_slab_caches and memcg_slab_mutex
mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to
the given cgroup.  Currently, it is only used on css free in order to
destroy all caches corresponding to the memory cgroup being freed.  The
list is protected by memcg_slab_mutex.  The mutex is also used to protect
kmem_cache->memcg_params->memcg_caches arrays and synchronizes
kmem_cache_destroy vs memcg_unregister_all_caches.

However, we can perfectly get on without these two.  To destroy all caches
corresponding to a memory cgroup, we can walk over the global list of kmem
caches, slab_caches, and we can do all the synchronization stuff using the
slab_mutex instead of the memcg_slab_mutex.  This patch therefore gets rid
of the memcg_slab_caches and memcg_slab_mutex.

Apart from this nice cleanup, it also:

 - assures that rcu_barrier() is called once at max when a root cache is
   destroyed or a memory cgroup is freed, no matter how many caches have
   SLAB_DESTROY_BY_RCU flag set;

 - fixes the race between kmem_cache_destroy and kmem_cache_create that
   exists, because memcg_cleanup_cache_params, which is called from
   kmem_cache_destroy after checking that kmem_cache->refcount=0,
   releases the slab_mutex, which gives kmem_cache_create a chance to
   make an alias to a cache doomed to be destroyed.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 14:30:34 -08:00
Vladimir Davydov
3e0350a364 memcg: zap memcg_name argument of memcg_create_kmem_cache
Instead of passing the name of the memory cgroup which the cache is
created for in the memcg_name_argument, let's obtain it immediately in
memcg_create_kmem_cache.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 14:30:34 -08:00
Vladimir Davydov
dbf22eb6d8 memcg: zap __memcg_{charge,uncharge}_slab
They are simple wrappers around memcg_{charge,uncharge}_kmem, so let's
zap them and call these functions directly.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-10 14:30:34 -08:00
Kirill A. Shutemov
0661a33611 mm: remove rest usage of VM_NONLINEAR and pte_file()
One bit in ->vm_flags is unused now!

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.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>
2015-02-10 14:30:31 -08:00
Michal Hocko
f5e03a4989 memcg, shmem: fix shmem migration to use lrucare
It has been reported that 965GM might trigger

  VM_BUG_ON_PAGE(!lrucare && PageLRU(oldpage), oldpage)

in mem_cgroup_migrate when shmem wants to replace a swap cache page
because of shmem_should_replace_page (the page is allocated from an
inappropriate zone).  shmem_replace_page expects that the oldpage is not
on LRU list and calls mem_cgroup_migrate without lrucare.  This is
obviously incorrect because swapcache pages might be on the LRU list
(e.g. swapin readahead page).

Fix this by enabling lrucare for the migration in shmem_replace_page.
Also clarify that lrucare should be used even if one of the pages might
be on LRU list.

The BUG_ON will trigger only when CONFIG_DEBUG_VM is enabled but even
without that the migration code might leave the old page on an
inappropriate memcg' LRU which is not that critical because the page
would get removed with its last reference but it is still confusing.

Fixes: 0a31bc97c8 ("mm: memcontrol: rewrite uncharge API")
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Dave Airlie <airlied@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-05 13:35:29 -08:00
Greg Thelen
0346dadbf0 memcg: remove extra newlines from memcg oom kill log
Commit e61734c55c ("cgroup: remove cgroup->name") added two extra
newlines to memcg oom kill log messages.  This makes dmesg hard to read
and parse.  The issue affects 3.15+.

Example:

  Task in /t                          <<< extra #1
   killed as a result of limit of /t
                                      <<< extra #2
  memory: usage 102400kB, limit 102400kB, failcnt 274712

Remove the extra newlines from memcg oom kill messages, so the messages
look like:

  Task in /t killed as a result of limit of /t
  memory: usage 102400kB, limit 102400kB, failcnt 240649

Fixes: e61734c55c ("cgroup: remove cgroup->name")
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-01-26 13:37:18 -08:00
Vladimir Davydov
4bdfc1c4a9 memcg: fix destination cgroup leak on task charges migration
We are supposed to take one css reference per each memory page and per
each swap entry accounted to a memory cgroup.  However, during task
charges migration we take a reference to the destination cgroup twice
per each swap entry: first in mem_cgroup_do_precharge()->try_charge()
and then in mem_cgroup_move_swap_account(), permanently leaking the
destination cgroup.

The hunk taking the second reference seems to be a leftover from the
pre-00501b531c472 ("mm: memcontrol: rewrite charge API") era.  Remove it
to fix the leak.

Fixes: e8ea14cc6e (mm: memcontrol: take a css reference for each charged page)
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-01-08 15:10:52 -08:00
Johannes Weiner
24d404dc10 mm: memcontrol: switch soft limit default back to infinity
Commit 3e32cb2e0a ("mm: memcontrol: lockless page counters")
accidentally switched the soft limit default from infinity to zero,
which turns all memcgs with even a single page into soft limit excessors
and engages soft limit reclaim on all of them during global memory
pressure.  This makes global reclaim generally more aggressive, but also
inverts the meaning of existing soft limit configurations where unset
soft limits are usually more generous than set ones.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-01-08 15:10:52 -08:00