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Johannes Weiner
9d82c69438 mm: memcontrol: convert anon and file-thp to new mem_cgroup_charge() API 
With the page->mapping requirement gone from memcg, we can charge anon and
file-thp pages in one single step, right after they're allocated.

This removes two out of three API calls - especially the tricky commit
step that needed to happen at just the right time between when the page is
"set up" and when it's "published" - somewhat vague and fluid concepts
that varied by page type.  All we need is a freshly allocated page and a
memcg context to charge.

v2: prevent double charges on pre-allocated hugepages in khugepaged

[hannes@cmpxchg.org: Fix crash - *hpage could be ERR_PTR instead of NULL]
  Link: http://lkml.kernel.org/r/20200512215813.GA487759@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/20200508183105.225460-13-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:48 -07:00
Johannes Weiner
468c398233 mm: memcontrol: switch to native NR_ANON_THPS counter 
With rmap memcg locking already in place for NR_ANON_MAPPED, it's just a
small step to remove the MEMCG_RSS_HUGE wart and switch memcg to the
native NR_ANON_THPS accounting sites.

[hannes@cmpxchg.org: fixes]
  Link: http://lkml.kernel.org/r/20200512121750.GA397968@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>	[build-tested]
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-12-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
be5d0a74c6 mm: memcontrol: switch to native NR_ANON_MAPPED counter 
Memcg maintains a private MEMCG_RSS counter.  This divergence from the
generic VM accounting means unnecessary code overhead, and creates a
dependency for memcg that page->mapping is set up at the time of charging,
so that page types can be told apart.

Convert the generic accounting sites to mod_lruvec_page_state and friends
to maintain the per-cgroup vmstat counter of NR_ANON_MAPPED.  We use
lock_page_memcg() to stabilize page->mem_cgroup during rmap changes, the
same way we do for NR_FILE_MAPPED.

With the previous patch removing MEMCG_CACHE and the private NR_SHMEM
counter, this patch finally eliminates the need to have page->mapping set
up at charge time.  However, we need to have page->mem_cgroup set up by
the time rmap runs and does the accounting, so switch the commit and the
rmap callbacks around.

v2: fix temporary accounting bug by switching rmap<->commit (Joonsoo)

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-11-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
0d1c20722a mm: memcontrol: switch to native NR_FILE_PAGES and NR_SHMEM counters 
Memcg maintains private MEMCG_CACHE and NR_SHMEM counters.  This
divergence from the generic VM accounting means unnecessary code overhead,
and creates a dependency for memcg that page->mapping is set up at the
time of charging, so that page types can be told apart.

Convert the generic accounting sites to mod_lruvec_page_state and friends
to maintain the per-cgroup vmstat counters of NR_FILE_PAGES and NR_SHMEM.
The page is already locked in these places, so page->mem_cgroup is stable;
we only need minimal tweaks of two mem_cgroup_migrate() calls to ensure
it's set up in time.

Then replace MEMCG_CACHE with NR_FILE_PAGES and delete the private
NR_SHMEM accounting sites.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-10-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
9da7b52168 mm: memcontrol: prepare cgroup vmstat infrastructure for native anon counters 
Anonymous compound pages can be mapped by ptes, which means that if we
want to track NR_MAPPED_ANON, NR_ANON_THPS on a per-cgroup basis, we have
to be prepared to see tail pages in our accounting functions.

Make mod_lruvec_page_state() and lock_page_memcg() deal with tail pages
correctly, namely by redirecting to the head page which has the
page->mem_cgroup set up.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-9-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
49e50d277b mm: memcontrol: prepare move_account for removal of private page type counters 
When memcg uses the generic vmstat counters, it doesn't need to do
anything at charging and uncharging time.  It does, however, need to
migrate counts when pages move to a different cgroup in move_account.

Prepare the move_account function for the arrival of NR_FILE_PAGES,
NR_ANON_MAPPED, NR_ANON_THPS etc.  by having a branch for files and a
branch for anon, which can then divided into sub-branches.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-8-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
9f762dbe19 mm: memcontrol: prepare uncharging for removal of private page type counters 
The uncharge batching code adds up the anon, file, kmem counts to
determine the total number of pages to uncharge and references to drop.
But the next patches will remove the anon and file counters.

Maintain an aggregate nr_pages in the uncharge_gather struct.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-7-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
3fea5a499d mm: memcontrol: convert page cache to a new mem_cgroup_charge() API 
The try/commit/cancel protocol that memcg uses dates back to when pages
used to be uncharged upon removal from the page cache, and thus couldn't
be committed before the insertion had succeeded.  Nowadays, pages are
uncharged when they are physically freed; it doesn't matter whether the
insertion was successful or not.  For the page cache, the transaction
dance has become unnecessary.

Introduce a mem_cgroup_charge() function that simply charges a newly
allocated page to a cgroup and sets up page->mem_cgroup in one single
step.  If the insertion fails, the caller doesn't have to do anything but
free/put the page.

Then switch the page cache over to this new API.

Subsequent patches will also convert anon pages, but it needs a bit more
prep work.  Right now, memcg depends on page->mapping being already set up
at the time of charging, so that it can maintain its own MEMCG_CACHE and
MEMCG_RSS counters.  For anon, page->mapping is set under the same pte
lock under which the page is publishd, so a single charge point that can
block doesn't work there just yet.

The following prep patches will replace the private memcg counters with
the generic vmstat counters, thus removing the page->mapping dependency,
then complete the transition to the new single-point charge API and delete
the old transactional scheme.

v2: leave shmem swapcache when charging fails to avoid double IO (Joonsoo)
v3: rebase on preceeding shmem simplification patch

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-6-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
6caa6a0703 mm: memcontrol: move out cgroup swaprate throttling 
The cgroup swaprate throttling is about matching new anon allocations to
the rate of available IO when that is being throttled.  It's the io
controller hooking into the VM, rather than a memory controller thing.

Rename mem_cgroup_throttle_swaprate() to cgroup_throttle_swaprate(), and
drop the @memcg argument which is only used to check whether the preceding
page charge has succeeded and the fault is proceeding.

We could decouple the call from mem_cgroup_try_charge() here as well, but
that would cause unnecessary churn: the following patches convert all
callsites to a new charge API and we'll decouple as we go along.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-5-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
14235ab360 mm: shmem: remove rare optimization when swapin races with hole punching 
Commit 215c02bc33 ("tmpfs: fix shmem_getpage_gfp() VM_BUG_ON")
recognized that hole punching can race with swapin and removed the
BUG_ON() for a truncated entry from the swapin path.

The patch also added a swapcache deletion to optimize this rare case:
Since swapin has the page locked, and free_swap_and_cache() merely
trylocks, this situation can leave the page stranded in swapcache.
Usually, page reclaim picks up stale swapcache pages, and the race can
happen at any other time when the page is locked.  (The same happens for
non-shmem swapin racing with page table zapping.) The thinking here was:
we already observed the race and we have the page locked, we may as well
do the cleanup instead of waiting for reclaim.

However, this optimization complicates the next patch which moves the
cgroup charging code around.  As this is just a minor speedup for a race
condition that is so rare that it required a fuzzer to trigger the
original BUG_ON(), it's no longer worth the complications.

Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200511181056.GA339505@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
3fba69a56e mm: memcontrol: drop @compound parameter from memcg charging API 
The memcg charging API carries a boolean @compound parameter that tells
whether the page we're dealing with is a hugepage.
mem_cgroup_commit_charge() has another boolean @lrucare that indicates
whether the page needs LRU locking or not while charging.  The majority of
callsites know those parameters at compile time, which results in a lot of
naked "false, false" argument lists.  This makes for cryptic code and is a
breeding ground for subtle mistakes.

Thankfully, the huge page state can be inferred from the page itself and
doesn't need to be passed along.  This is safe because charging completes
before the page is published and somebody may split it.

Simplify the callsites by removing @compound, and let memcg infer the
state by using hpage_nr_pages() unconditionally.  That function does
PageTransHuge() to identify huge pages, which also helpfully asserts that
nobody passes in tail pages by accident.

The following patches will introduce a new charging API, best not to carry
over unnecessary weight.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
abb242f571 mm: memcontrol: fix stat-corrupting race in charge moving 
The move_lock is a per-memcg lock, but the VM accounting code that needs
to acquire it comes from the page and follows page->mem_cgroup under RCU
protection.  That means that the page becomes unlocked not when we drop
the move_lock, but when we update page->mem_cgroup.  And that assignment
doesn't imply any memory ordering.  If that pointer write gets reordered
against the reads of the page state - page_mapped, PageDirty etc.  the
state may change while we rely on it being stable and we can end up
corrupting the counters.

Place an SMP memory barrier to make sure we're done with all page state by
the time the new page->mem_cgroup becomes visible.

Also replace the open-coded move_lock with a lock_page_memcg() to make it
more obvious what we're serializing against.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-3-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Johannes Weiner
f4129ea359 mm: fix NUMA node file count error in replace_page_cache() 
Patch series "mm: memcontrol: charge swapin pages on instantiation", v2.

This patch series reworks memcg to charge swapin pages directly at
swapin time, rather than at fault time, which may be much later, or
not happen at all.

Changes in version 2:
- prevent double charges on pre-allocated hugepages in khugepaged
- leave shmem swapcache when charging fails to avoid double IO (Joonsoo)
- fix temporary accounting bug by switching rmap<->commit (Joonsoo)
- fix double swap charge bug in cgroup1/cgroup2 code gating
- simplify swapin error checking (Joonsoo)
- mm: memcontrol: document the new swap control behavior (Alex)
- review tags

The delayed swapin charging scheme we have right now causes problems:

- Alex's per-cgroup lru_lock patches rely on pages that have been
  isolated from the LRU to have a stable page->mem_cgroup; otherwise
  the lock may change underneath him. Swapcache pages are charged only
  after they are added to the LRU, and charging doesn't follow the LRU
  isolation protocol.

- Joonsoo's anon workingset patches need a suitable LRU at the time
  the page enters the swap cache and displaces the non-resident
  info. But the correct LRU is only available after charging.

- It's a containment hole / DoS vector. Users can trigger arbitrarily
  large swap readahead using MADV_WILLNEED. The memory is never
  charged unless somebody actually touches it.

- It complicates the page->mem_cgroup stabilization rules

In order to charge pages directly at swapin time, the memcg code base
needs to be prepared, and several overdue cleanups become a necessity:

To charge pages at swapin time, we need to always have cgroup
ownership tracking of swap records. We also cannot rely on
page->mapping to tell apart page types at charge time, because that's
only set up during a page fault.

To eliminate the page->mapping dependency, memcg needs to ditch its
private page type counters (MEMCG_CACHE, MEMCG_RSS, NR_SHMEM) in favor
of the generic vmstat counters and accounting sites, such as
NR_FILE_PAGES, NR_ANON_MAPPED etc.

To switch to generic vmstat counters, the charge sequence must be
adjusted such that page->mem_cgroup is set up by the time these
counters are modified.

The series is structured as follows:

1. Bug fixes
2. Decoupling charging from rmap
3. Swap controller integration into memcg
4. Direct swapin charging

This patch (of 19):

When replacing one page with another one in the cache, we have to decrease
the file count of the old page's NUMA node and increase the one of the new
NUMA node, otherwise the old node leaks the count and the new node
eventually underflows its counter.

Fixes: 74d609585d ("page cache: Add and replace pages using the XArray")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-1-hannes@cmpxchg.org
Link: http://lkml.kernel.org/r/20200508183105.225460-2-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Qiwu Chen
df3a45f9d8 mm/vmscan: update the comment of should_continue_reclaim() 
try_to_compact_zone() has been replaced by try_to_compact_pages(), which
is necessary to be updated in the comment of should_continue_reclaim().

Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200501034907.22991-1-chenqiwu@xiaomi.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Maninder Singh
730ec8c01a mm/vmscan.c: change prototype for shrink_page_list 
commit 3c710c1ad1 ("mm, vmscan extract shrink_page_list reclaim counters
into a struct") changed data type for the function, so changing return
type for funciton and its caller.

Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Amit Sahrawat <a.sahrawat@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1588168259-25604-1-git-send-email-maninder1.s@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Jaewon Kim
1f318a9b0d mm/vmscan: count layzfree pages and fix nr_isolated_* mismatch 
Fix an nr_isolate_* mismatch problem between cma and dirty lazyfree pages.

If try_to_unmap_one is used for reclaim and it detects a dirty lazyfree
page, then the lazyfree page is changed to a normal anon page having
SwapBacked by commit 802a3a92ad ("mm: reclaim MADV_FREE pages").  Even
with the change, reclaim context correctly counts isolated files because
it uses is_file_lru to distinguish file.  And the change to anon is not
happened if try_to_unmap_one is used for migration.  So migration context
like compaction also correctly counts isolated files even though it uses
page_is_file_lru insted of is_file_lru.  Recently page_is_file_cache was
renamed to page_is_file_lru by commit 9de4f22a60 ("mm: code cleanup for
MADV_FREE").

But the nr_isolate_* mismatch problem happens on cma alloc.  There is
reclaim_clean_pages_from_list which is being used only by cma.  It was
introduced by commit 02c6de8d75 ("mm: cma: discard clean pages during
contiguous allocation instead of migration") to reclaim clean file pages
without migration.  The cma alloc uses both reclaim_clean_pages_from_list
and migrate_pages, and it uses page_is_file_lru to count isolated files.
If there are dirty lazyfree pages allocated from cma memory region, the
pages are counted as isolated file at the beginging but are counted as
isolated anon after finished.

Mem-Info:
Node 0 active_anon:3045904kB inactive_anon:611448kB active_file:14892kB inactive_file:205636kB unevictable:10416kB isolated(anon):0kB isolated(file):37664kB mapped:630216kB dirty:384kB writeback:0kB shmem:42576kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no

Like log above, there were too much isolated files, 37664kB, which
triggers too_many_isolated in reclaim even when there is no actually
isolated file in system wide.  It could be reproducible by running two
programs, writing on MADV_FREE page and doing cma alloc, respectively.
Although isolated anon is 0, I found that the internal value of isolated
anon was the negative value of isolated file.

Fix this by compensating the isolated count for both LRU lists.  Count
non-discarded lazyfree pages in shrink_page_list, then compensate the
counted number in reclaim_clean_pages_from_list.

Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200426011718.30246-1-jaewon31.kim@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Wei Yang
a892cb6b97 mm/vmscan.c: use update_lru_size() in update_lru_sizes() 
We already defined the helper update_lru_size().

Let's use this to reduce code duplication.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200331221550.1011-1-richard.weiyang@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Matthew Wilcox (Oracle)
ff45fc3ca0 mm: simplify calling a compound page destructor 
None of the three callers of get_compound_page_dtor() want to know the
value; they just want to call the function.  Replace it with
destroy_compound_page() which calls the dtor for them.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200517105051.9352-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:47 -07:00
Anshuman Khandual
5be9934328 mm/hugetlb: define a generic fallback for arch_clear_hugepage_flags() 
There are multiple similar definitions for arch_clear_hugepage_flags() on
various platforms.  Lets just add it's generic fallback definition for
platforms that do not override.  This help reduce code duplication.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1588907271-11920-4-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Anshuman Khandual
b0eae98c66 mm/hugetlb: define a generic fallback for is_hugepage_only_range() 
There are multiple similar definitions for is_hugepage_only_range() on
various platforms.  Lets just add it's generic fallback definition for
platforms that do not override.  This help reduce code duplication.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1588907271-11920-3-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Anshuman Khandual
be51e3fde5 arm64/mm: drop __HAVE_ARCH_HUGE_PTEP_GET 
Patch series "mm/hugetlb: Add some new generic fallbacks", v3.

This series adds the following new generic fallbacks.  Before that it
drops __HAVE_ARCH_HUGE_PTEP_GET from arm64 platform.

1. is_hugepage_only_range()
2. arch_clear_hugepage_flags()

After this arm (32 bit) remains the sole platform defining it's own
huge_ptep_get() via __HAVE_ARCH_HUGE_PTEP_GET.

This patch (of 3):

Platform specific huge_ptep_get() is required only when fetching the huge
PTE involves more than just dereferencing the page table pointer.  This is
not the case on arm64 platform.  Hence huge_ptep_pte() can be dropped
along with it's __HAVE_ARCH_HUGE_PTEP_GET subscription.  Before that, it
updates the generic huge_ptep_get() with READ_ONCE() which will prevent
known page table issues with THP on arm64.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/1588907271-11920-1-git-send-email-anshuman.khandual@arm.com
Link: http://lkml.kernel.org/r//1506527369-19535-1-git-send-email-will.deacon@arm.com/
Link: http://lkml.kernel.org/r/1588907271-11920-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Li Xinhai
8ac0b81ab1 mm/hugetlb: avoid unnecessary check on pud and pmd entry in huge_pte_offset 
When huge_pte_offset() is called, the parameter sz can only be PUD_SIZE or
PMD_SIZE.  If sz is PUD_SIZE and code can reach pud, then *pud must be
none, or normal hugetlb entry, or non-present (migration or hwpoisoned)
hugetlb entry, and we can directly return pud.  When sz is PMD_SIZE, pud
must be none or present, and if code can reach pmd, we can directly return
pmd.

So after this patch the code is simplified by first check on the parameter
sz, and avoid unnecessary checks in current code.  Same semantics of
existing code is maintained.

More details about relevant commits:
commit 9b19df292c ("mm/hugetlb.c: make huge_pte_offset() consistent
and document behaviour") changed the code path for pud and pmd handling,
see comments about why this patch intends to change it.
...
	pud = pud_offset(p4d, addr);
	if (sz != PUD_SIZE && pud_none(*pud)) // [1]
		return NULL;
	/* hugepage or swap? */
	if (pud_huge(*pud) || !pud_present(*pud)) // [2]
		return (pte_t *)pud;

	pmd = pmd_offset(pud, addr);
	if (sz != PMD_SIZE && pmd_none(*pmd)) // [3]
		return NULL;
	/* hugepage or swap? */
	if (pmd_huge(*pmd) || !pmd_present(*pmd)) // [4]
		return (pte_t *)pmd;

	return NULL; // [5]
...
[1]: this is necessary, return NULL for sz == PMD_SIZE;
[2]: if sz == PUD_SIZE, all valid values of pud entry will cause return;
[3]: dead code, sz != PMD_SIZE never true;
[4]: all valid values of pmd entry will cause return;
[5]: dead code, because of check in [4].

Now, this patch combines [1] and [2] for pud, and combines [3], [4] and
[5] for pmd, so avoid unnecessary checks.

I don't try to catch any invalid values in page table entry, as that will
be checked by caller and avoid extra branch in this function.  Also no
assert on sz must equal PUD_SIZE or PMD_SIZE, since this function only
call for hugetlb mapping.

For commit 3c1d7e6ccb ("mm/hugetlb: fix a addressing exception caused by
huge_pte_offset"), since we don't read the entry more than once now,
variable pud_entry and pmd_entry are not needed.

Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Longpeng <longpeng2@huawei.com>
Link: http://lkml.kernel.org/r/1587794313-16849-1-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Mike Kravetz
c2833a5bf7 hugetlbfs: fix changes to command line processing 
Previously, a check for hugepages_supported was added before processing
hugetlb command line parameters.  On some architectures such as powerpc,
hugepages_supported() is not set to true until after command line
processing.  Therefore, no hugetlb command line parameters would be
accepted.

Remove the additional checks for hugepages_supported.  In hugetlb_init,
print a warning if !hugepages_supported and command line parameters were
specified.

Reported-by: Sandipan Das <sandipan.osd@gmail.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/b1f04f9f-fa46-c2a0-7693-4a0679d2a1ee@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Mike Kravetz
282f421438 hugetlbfs: clean up command line processing 
With all hugetlb page processing done in a single file clean up code.

- Make code match desired semantics
  - Update documentation with semantics
- Make all warnings and errors messages start with 'HugeTLB:'.
- Consistently name command line parsing routines.
- Warn if !hugepages_supported() and command line parameters have
  been specified.
- Add comments to code
  - Describe some of the subtle interactions
  - Describe semantics of command line arguments

This patch also fixes issues with implicitly setting the number of
gigantic huge pages to preallocate.  Previously on X86 command line,

        hugepages=2 default_hugepagesz=1G

would result in zero 1G pages being preallocated and,

        # grep HugePages_Total /proc/meminfo
        HugePages_Total:       0
        # sysctl -a | grep nr_hugepages
        vm.nr_hugepages = 2
        vm.nr_hugepages_mempolicy = 2
        # cat /proc/sys/vm/nr_hugepages
        2

After this patch 2 gigantic pages will be preallocated and all the proc,
sysfs, sysctl and meminfo files will accurately reflect this.

To address the issue with gigantic pages, a small change in behavior was
made to command line processing.  Previously the command line,

        hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256

would result in the allocation of 256 2M huge pages.  The value 128 would
be ignored without any warning.  After this patch, 128 2M pages will be
allocated and a warning message will be displayed indicating the value of
256 is ignored.  This change in behavior is required because allocation of
implicitly specified gigantic pages must be done when the
default_hugepagesz= is encountered for gigantic pages.  Previously the
code waited until later in the boot process (hugetlb_init), to allocate
pages of default size.  However the bootmem allocator required for
gigantic allocations is not available at this time.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sandipan Das <sandipan@linux.ibm.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Acked-by: Will Deacon <will@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Longpeng <longpeng2@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Mike Kravetz
3823783088 hugetlbfs: remove hugetlb_add_hstate() warning for existing hstate 
hugetlb_add_hstate() prints a warning if the hstate already exists.  This
was originally done as part of kernel command line parsing.  If
'hugepagesz=' was specified more than once, the warning

	pr_warn("hugepagesz= specified twice, ignoring\n");

would be printed.

Some architectures want to enable all huge page sizes.  They would call
hugetlb_add_hstate for all supported sizes.  However, this was done after
command line processing and as a result hstates could have already been
created for some sizes.  To make sure no warning were printed, there would
often be code like:

	if (!size_to_hstate(size)
		hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT)

The only time we want to print the warning is as the result of command
line processing.  So, remove the warning from hugetlb_add_hstate and add
it to the single arch independent routine processing "hugepagesz=".  After
this, calls to size_to_hstate() in arch specific code can be removed and
hugetlb_add_hstate can be called without worrying about warning messages.

[mike.kravetz@oracle.com: fix hugetlb initialization]
  Link: http://lkml.kernel.org/r/4c36c6ce-3774-78fa-abc4-b7346bf24348@oracle.com
  Link: http://lkml.kernel.org/r/20200428205614.246260-5-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Acked-by: Mina Almasry <almasrymina@google.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Acked-by: Will Deacon <will@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Longpeng <longpeng2@huawei.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200417185049.275845-4-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20200428205614.246260-4-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Mike Kravetz
359f25443a hugetlbfs: move hugepagesz= parsing to arch independent code 
Now that architectures provide arch_hugetlb_valid_size(), parsing of
"hugepagesz=" can be done in architecture independent code.  Create a
single routine to handle hugepagesz= parsing and remove all arch specific
routines.  We can also remove the interface hugetlb_bad_size() as this is
no longer used outside arch independent code.

This also provides consistent behavior of hugetlbfs command line options.
The hugepagesz= option should only be specified once for a specific size,
but some architectures allow multiple instances.  This appears to be more
of an oversight when code was added by some architectures to set up ALL
huge pages sizes.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Mina Almasry <almasrymina@google.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Acked-by: Will Deacon <will@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Longpeng <longpeng2@huawei.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200417185049.275845-3-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20200428205614.246260-3-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Mike Kravetz
ae94da8981 hugetlbfs: add arch_hugetlb_valid_size 
Patch series "Clean up hugetlb boot command line processing", v4.

Longpeng(Mike) reported a weird message from hugetlb command line
processing and proposed a solution [1].  While the proposed patch does
address the specific issue, there are other related issues in command line
processing.  As hugetlbfs evolved, updates to command line processing have
been made to meet immediate needs and not necessarily in a coordinated
manner.  The result is that some processing is done in arch specific code,
some is done in arch independent code and coordination is problematic.
Semantics can vary between architectures.

The patch series does the following:
- Define arch specific arch_hugetlb_valid_size routine used to validate
  passed huge page sizes.
- Move hugepagesz= command line parsing out of arch specific code and into
  an arch independent routine.
- Clean up command line processing to follow desired semantics and
  document those semantics.

[1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@huawei.com

This patch (of 3):

The architecture independent routine hugetlb_default_setup sets up the
default huge pages size.  It has no way to verify if the passed value is
valid, so it accepts it and attempts to validate at a later time.  This
requires undocumented cooperation between the arch specific and arch
independent code.

For architectures that support more than one huge page size, provide a
routine arch_hugetlb_valid_size to validate a huge page size.
hugetlb_default_setup can use this to validate passed values.

arch_hugetlb_valid_size will also be used in a subsequent patch to move
processing of the "hugepagesz=" in arch specific code to a common routine
in arch independent code.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Longpeng <longpeng2@huawei.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200428205614.246260-1-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20200428205614.246260-2-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20200417185049.275845-1-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20200417185049.275845-2-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
71a2c112a0 khugepaged: introduce 'max_ptes_shared' tunable 
'max_ptes_shared' specifies how many pages can be shared across multiple
processes.  Exceeding the number would block the collapse::

	/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_shared

A higher value may increase memory footprint for some workloads.

By default, at least half of pages has to be not shared.

[colin.king@canonical.com: fix several spelling mistakes]
  Link: http://lkml.kernel.org/r/20200420084241.65433-1-colin.king@canonical.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-9-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
3917c80280 thp: change CoW semantics for anon-THP 
Currently we have different copy-on-write semantics for anon- and
file-THP.  For anon-THP we try to allocate huge page on the write fault,
but on file-THP we split PMD and allocate 4k page.

Arguably, file-THP semantics is more desirable: we don't necessary want to
unshare full PMD range from the parent on the first access.  This is the
primary reason THP is unusable for some workloads, like Redis.

The original THP refcounting didn't allow to have PTE-mapped compound
pages, so we had no options, but to allocate huge page on CoW (with
fallback to 512 4k pages).

The current refcounting doesn't have such limitations and we can cut a lot
of complex code out of fault path.

khugepaged is now able to recover THP from such ranges if the
configuration allows.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-8-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
5503fbf2b0 khugepaged: allow to collapse PTE-mapped compound pages 
We can collapse PTE-mapped compound pages.  We only need to avoid handling
them more than once: lock/unlock page only once if it's present in the PMD
range multiple times as it handled on compound level.  The same goes for
LRU isolation and putback.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-7-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
9445689f3b khugepaged: allow to collapse a page shared across fork 
The page can be included into collapse as long as it doesn't have extra
pins (from GUP or otherwise).

Logic to check the refcount is moved to a separate function.  For pages in
swap cache, add compound_nr(page) to the expected refcount, in order to
handle the compound page case.  This is in preparation for the following
patch.

VM_BUG_ON_PAGE() was removed from __collapse_huge_page_copy() as the
invariant it checks is no longer valid: the source can be mapped multiple
times now.

[yang.shi@linux.alibaba.com: remove error message when checking external pins]
  Link: http://lkml.kernel.org/r/1589317383-9595-1-git-send-email-yang.shi@linux.alibaba.com
[cai@lca.pw: fix set-but-not-used warning]
  Link: http://lkml.kernel.org/r/20200521145644.GA6367@ovpn-112-192.phx2.redhat.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-6-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
ae2c5d8042 khugepaged: drain LRU add pagevec after swapin 
collapse_huge_page() tries to swap in pages that are part of the PMD
range.  Just swapped in page goes though LRU add cache.  The cache gets
extra reference on the page.

The extra reference can lead to the collapse fail: the following
__collapse_huge_page_isolate() would check refcount and abort collapse
seeing unexpected refcount.

The fix is to drain local LRU add cache in
__collapse_huge_page_swapin() if we successfully swapped in any pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-5-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
a980df33e9 khugepaged: drain all LRU caches before scanning pages 
Having a page in LRU add cache offsets page refcount and gives
false-negative on PageLRU().  It reduces collapse success rate.

Drain all LRU add caches before scanning.  It happens relatively rare and
should not disturb the system too much.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-4-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
ffe945e633 khugepaged: do not stop collapse if less than half PTEs are referenced 
__collapse_huge_page_swapin() checks the number of referenced PTE to
decide if the memory range is hot enough to justify swapin.

We have few problems with the approach:

 - It is way too late: we can do the check much earlier and safe time.
   khugepaged_scan_pmd() already knows if we have any pages to swap in
   and number of referenced page.

 - It stops collapse altogether if there's not enough referenced pages,
   not only swappingin.

Fix it by making the right check early. We also can avoid additional
page table scanning if khugepaged_scan_pmd() haven't found any swap
entries.

Fixes: 0db501f7a3 ("mm, thp: convert from optimistic swapin collapsing to conservative")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-3-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Kirill A. Shutemov
e0c13f9761 khugepaged: add self test 
Patch series "thp/khugepaged improvements and CoW semantics", v4.

The patchset adds khugepaged selftest (anon-THP only for now), expands
cases khugepaged can handle and switches anon-THP copy-on-write handling
to 4k.

This patch (of 8):

The test checks if khugepaged is able to recover huge page where we expect
to do so.  It only covers anon-THP for now.

Currently the test shows few failures.  They are going to be addressed by
the following patches.

[colin.king@canonical.com: fix several spelling mistakes]
  Link: http://lkml.kernel.org/r/20200420084241.65433-1-colin.king@canonical.com
[aneesh.kumar@linux.ibm.com: replace the usage of system(3) in the test]
  Link: http://lkml.kernel.org/r/20200429110727.89388-1-aneesh.kumar@linux.ibm.com
[kirill@shutemov.name: fixup for issues I've noticed]
  Link: http://lkml.kernel.org/r/20200429124816.jp272trghrzxx5j5@box
[jhubbard@nvidia.com: add khugepaged to .gitignore]
  Link: http://lkml.kernel.org/r/20200517002509.362401-1-jhubbard@nvidia.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Link: http://lkml.kernel.org/r/20200416160026.16538-1-kirill.shutemov@linux.intel.com
Link: http://lkml.kernel.org/r/20200416160026.16538-2-kirill.shutemov@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:46 -07:00
Chen Tao
633bf2fe8d mm/page_alloc.c: add missing newline 
Add missing line breaks on pr_warn().

Signed-off-by: Chen Tao <chentao107@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200603063547.235825-1-chentao107@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
ec3b39c731 padata: document multithreaded jobs 
Add Documentation for multithreaded jobs.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-9-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
ecd0965069 mm: make deferred init's max threads arch-specific 
Using padata during deferred init has only been tested on x86, so for now
limit it to this architecture.

If another arch wants this, it can find the max thread limit that's best
for it and override deferred_page_init_max_threads().

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-8-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
e44431498f mm: parallelize deferred_init_memmap() 
Deferred struct page init is a significant bottleneck in kernel boot.
Optimizing it maximizes availability for large-memory systems and allows
spinning up short-lived VMs as needed without having to leave them
running.  It also benefits bare metal machines hosting VMs that are
sensitive to downtime.  In projects such as VMM Fast Restart[1], where
guest state is preserved across kexec reboot, it helps prevent application
and network timeouts in the guests.

Multithread to take full advantage of system memory bandwidth.

The maximum number of threads is capped at the number of CPUs on the node
because speedups always improve with additional threads on every system
tested, and at this phase of boot, the system is otherwise idle and
waiting on page init to finish.

Helper threads operate on section-aligned ranges to both avoid false
sharing when setting the pageblock's migrate type and to avoid accessing
uninitialized buddy pages, though max order alignment is enough for the
latter.

The minimum chunk size is also a section.  There was benefit to using
multiple threads even on relatively small memory (1G) systems, and this is
the smallest size that the alignment allows.

The time (milliseconds) is the slowest node to initialize since boot
blocks until all nodes finish.  intel_pstate is loaded in active mode
without hwp and with turbo enabled, and intel_idle is active as well.

    Intel(R) Xeon(R) Platinum 8167M CPU @ 2.00GHz (Skylake, bare metal)
      2 nodes * 26 cores * 2 threads = 104 CPUs
      384G/node = 768G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --   4089.7 (  8.1)         --   1785.7 (  7.6)
       2% (  1)       1.7%   4019.3 (  1.5)       3.8%   1717.7 ( 11.8)
      12% (  6)      34.9%   2662.7 (  2.9)      79.9%    359.3 (  0.6)
      25% ( 13)      39.9%   2459.0 (  3.6)      91.2%    157.0 (  0.0)
      37% ( 19)      39.2%   2485.0 ( 29.7)      90.4%    172.0 ( 28.6)
      50% ( 26)      39.3%   2482.7 ( 25.7)      90.3%    173.7 ( 30.0)
      75% ( 39)      39.0%   2495.7 (  5.5)      89.4%    190.0 (  1.0)
     100% ( 52)      40.2%   2443.7 (  3.8)      92.3%    138.0 (  1.0)

    Intel(R) Xeon(R) CPU E5-2699C v4 @ 2.20GHz (Broadwell, kvm guest)
      1 node * 16 cores * 2 threads = 32 CPUs
      192G/node = 192G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --   1988.7 (  9.6)         --   1096.0 ( 11.5)
       3% (  1)       1.1%   1967.0 ( 17.6)       0.3%   1092.7 ( 11.0)
      12% (  4)      41.1%   1170.3 ( 14.2)      73.8%    287.0 (  3.6)
      25% (  8)      47.1%   1052.7 ( 21.9)      83.9%    177.0 ( 13.5)
      38% ( 12)      48.9%   1016.3 ( 12.1)      86.8%    144.7 (  1.5)
      50% ( 16)      48.9%   1015.7 (  8.1)      87.8%    134.0 (  4.4)
      75% ( 24)      49.1%   1012.3 (  3.1)      88.1%    130.3 (  2.3)
     100% ( 32)      49.5%   1004.0 (  5.3)      88.5%    125.7 (  2.1)

    Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz (Haswell, bare metal)
      2 nodes * 18 cores * 2 threads = 72 CPUs
      128G/node = 256G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --   1680.0 (  4.6)         --    627.0 (  4.0)
       3% (  1)       0.3%   1675.7 (  4.5)      -0.2%    628.0 (  3.6)
      11% (  4)      25.6%   1250.7 (  2.1)      67.9%    201.0 (  0.0)
      25% (  9)      30.7%   1164.0 ( 17.3)      81.8%    114.3 ( 17.7)
      36% ( 13)      31.4%   1152.7 ( 10.8)      84.0%    100.3 ( 17.9)
      50% ( 18)      31.5%   1150.7 (  9.3)      83.9%    101.0 ( 14.1)
      75% ( 27)      31.7%   1148.0 (  5.6)      84.5%     97.3 (  6.4)
     100% ( 36)      32.0%   1142.3 (  4.0)      85.6%     90.0 (  1.0)

    AMD EPYC 7551 32-Core Processor (Zen, kvm guest)
      1 node * 8 cores * 2 threads = 16 CPUs
      64G/node = 64G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --   1029.3 ( 25.1)         --    240.7 (  1.5)
       6% (  1)      -0.6%   1036.0 (  7.8)      -2.2%    246.0 (  0.0)
      12% (  2)      11.8%    907.7 (  8.6)      44.7%    133.0 (  1.0)
      25% (  4)      13.9%    886.0 ( 10.6)      62.6%     90.0 (  6.0)
      38% (  6)      17.8%    845.7 ( 14.2)      69.1%     74.3 (  3.8)
      50% (  8)      16.8%    856.0 ( 22.1)      72.9%     65.3 (  5.7)
      75% ( 12)      15.4%    871.0 ( 29.2)      79.8%     48.7 (  7.4)
     100% ( 16)      21.0%    813.7 ( 21.0)      80.5%     47.0 (  5.2)

Server-oriented distros that enable deferred page init sometimes run in
small VMs, and they still benefit even though the fraction of boot time
saved is smaller:

    AMD EPYC 7551 32-Core Processor (Zen, kvm guest)
      1 node * 2 cores * 2 threads = 4 CPUs
      16G/node = 16G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --    716.0 ( 14.0)         --     49.7 (  0.6)
      25% (  1)       1.8%    703.0 (  5.3)      -4.0%     51.7 (  0.6)
      50% (  2)       1.6%    704.7 (  1.2)      43.0%     28.3 (  0.6)
      75% (  3)       2.7%    696.7 ( 13.1)      49.7%     25.0 (  0.0)
     100% (  4)       4.1%    687.0 ( 10.4)      55.7%     22.0 (  0.0)

    Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz (Haswell, kvm guest)
      1 node * 2 cores * 2 threads = 4 CPUs
      14G/node = 14G memory

                   kernel boot                 deferred init
                   ------------------------    ------------------------
    node% (thr)    speedup  time_ms (stdev)    speedup  time_ms (stdev)
          (  0)         --    787.7 (  6.4)         --    122.3 (  0.6)
      25% (  1)       0.2%    786.3 ( 10.8)      -2.5%    125.3 (  2.1)
      50% (  2)       5.9%    741.0 ( 13.9)      37.6%     76.3 ( 19.7)
      75% (  3)       8.3%    722.0 ( 19.0)      49.9%     61.3 (  3.2)
     100% (  4)       9.3%    714.7 (  9.5)      56.4%     53.3 (  1.5)

On Josh's 96-CPU and 192G memory system:

    Without this patch series:
    [    0.487132] node 0 initialised, 23398907 pages in 292ms
    [    0.499132] node 1 initialised, 24189223 pages in 304ms
    ...
    [    0.629376] Run /sbin/init as init process

    With this patch series:
    [    0.231435] node 1 initialised, 24189223 pages in 32ms
    [    0.236718] node 0 initialised, 23398907 pages in 36ms

[1] https://static.sched.com/hosted_files/kvmforum2019/66/VMM-fast-restart_kvmforum2019.pdf

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-7-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
89c7c4022d mm: don't track number of pages during deferred initialization 
Deferred page init used to report the number of pages initialized:

  node 0 initialised, 32439114 pages in 97ms

Tracking this makes the code more complicated when using multiple threads.
Given that the statistic probably has limited value, especially since a
zone grows on demand so that the page count can vary, just remove it.

The boot message now looks like

  node 0 deferred pages initialised in 97ms

Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-6-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
004ed42638 padata: add basic support for multithreaded jobs 
Sometimes the kernel doesn't take full advantage of system memory
bandwidth, leading to a single CPU spending excessive time in
initialization paths where the data scales with memory size.

Multithreading naturally addresses this problem.

Extend padata, a framework that handles many parallel yet singlethreaded
jobs, to also handle multithreaded jobs by adding support for splitting up
the work evenly, specifying a minimum amount of work that's appropriate
for one helper thread to do, load balancing between helpers, and
coordinating them.

This is inspired by work from Pavel Tatashin and Steve Sistare.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-5-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
4611ce2246 padata: allocate work structures for parallel jobs from a pool 
padata allocates per-CPU, per-instance work structs for parallel jobs.  A
do_parallel call assigns a job to a sequence number and hashes the number
to a CPU, where the job will eventually run using the corresponding work.

This approach fit with how padata used to bind a job to each CPU
round-robin, makes less sense after commit bfde23ce20 ("padata: unbind
parallel jobs from specific CPUs") because a work isn't bound to a
particular CPU anymore, and isn't needed at all for multithreaded jobs
because they don't have sequence numbers.

Replace the per-CPU works with a preallocated pool, which allows sharing
them between existing padata users and the upcoming multithreaded user.
The pool will also facilitate setting NUMA-aware concurrency limits with
later users.

The pool is sized according to the number of possible CPUs.  With this
limit, MAX_OBJ_NUM no longer makes sense, so remove it.

If the global pool is exhausted, a parallel job is run in the current task
instead to throttle a system trying to do too much in parallel.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-4-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
f1b192b117 padata: initialize earlier 
padata will soon initialize the system's struct pages in parallel, so it
needs to be ready by page_alloc_init_late().

The error return from padata_driver_init() triggers an initcall warning,
so add a warning to padata_init() to avoid silent failure.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-3-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
305dacf779 padata: remove exit routine 
Patch series "padata: parallelize deferred page init", v3.

Deferred struct page init is a bottleneck in kernel boot--the biggest for
us and probably others.  Optimizing it maximizes availability for
large-memory systems and allows spinning up short-lived VMs as needed
without having to leave them running.  It also benefits bare metal
machines hosting VMs that are sensitive to downtime.  In projects such as
VMM Fast Restart[1], where guest state is preserved across kexec reboot,
it helps prevent application and network timeouts in the guests.

So, multithread deferred init to take full advantage of system memory
bandwidth.

Extend padata, a framework that handles many parallel singlethreaded jobs,
to handle multithreaded jobs as well by adding support for splitting up
the work evenly, specifying a minimum amount of work that's appropriate
for one helper thread to do, load balancing between helpers, and
coordinating them.  More documentation in patches 4 and 8.

This series is the first step in a project to address other memory
proportional bottlenecks in the kernel such as pmem struct page init, vfio
page pinning, hugetlb fallocate, and munmap.  Deferred page init doesn't
require concurrency limits, resource control, or priority adjustments like
these other users will because it happens during boot when the system is
otherwise idle and waiting for page init to finish.

This has been run on a variety of x86 systems and speeds up kernel boot by
4% to 49%, saving up to 1.6 out of 4 seconds.  Patch 6 has more numbers.

This patch (of 8):

padata_driver_exit() is unnecessary because padata isn't built as a module
and doesn't exit.

padata's init routine will soon allocate memory, so getting rid of the
exit function now avoids pointless code to free it.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Josh Triplett <josh@joshtriplett.org>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200527173608.2885243-1-daniel.m.jordan@oracle.com
Link: http://lkml.kernel.org/r/20200527173608.2885243-2-daniel.m.jordan@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Pavel Tatashin
da97f2d56b mm: call cond_resched() from deferred_init_memmap() 
Now that deferred pages are initialized with interrupts enabled we can
replace touch_nmi_watchdog() with cond_resched(), as it was before
3a2d7fa8a3.

For now, we cannot do the same in deferred_grow_zone() as it is still
initializes pages with interrupts disabled.

This change fixes RCU problem described in
https://lkml.kernel.org/r/20200401104156.11564-2-david@redhat.com

[   60.474005] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[   60.475000] rcu:  1-...0: (0 ticks this GP) idle=02a/1/0x4000000000000000 softirq=1/1 fqs=15000
[   60.475000] rcu:  (detected by 0, t=60002 jiffies, g=-1199, q=1)
[   60.475000] Sending NMI from CPU 0 to CPUs 1:
[    1.760091] NMI backtrace for cpu 1
[    1.760091] CPU: 1 PID: 20 Comm: pgdatinit0 Not tainted 4.18.0-147.9.1.el8_1.x86_64 #1
[    1.760091] Hardware name: Red Hat KVM, BIOS 1.13.0-1.module+el8.2.0+5520+4e5817f3 04/01/2014
[    1.760091] RIP: 0010:__init_single_page.isra.65+0x10/0x4f
[    1.760091] Code: 48 83 cf 63 48 89 f8 0f 1f 40 00 48 89 c6 48 89 d7 e8 6b 18 80 ff 66 90 5b c3 31 c0 b9 10 00 00 00 49 89 f8 48 c1 e6 33 f3 ab <b8> 07 00 00 00 48 c1 e2 36 41 c7 40 34 01 00 00 00 48 c1 e0 33 41
[    1.760091] RSP: 0000:ffffba783123be40 EFLAGS: 00000006
[    1.760091] RAX: 0000000000000000 RBX: fffffad34405e300 RCX: 0000000000000000
[    1.760091] RDX: 0000000000000000 RSI: 0010000000000000 RDI: fffffad34405e340
[    1.760091] RBP: 0000000033f3177e R08: fffffad34405e300 R09: 0000000000000002
[    1.760091] R10: 000000000000002b R11: ffff98afb691a500 R12: 0000000000000002
[    1.760091] R13: 0000000000000000 R14: 000000003f03ea00 R15: 000000003e10178c
[    1.760091] FS:  0000000000000000(0000) GS:ffff9c9ebeb00000(0000) knlGS:0000000000000000
[    1.760091] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.760091] CR2: 00000000ffffffff CR3: 000000a1cf20a001 CR4: 00000000003606e0
[    1.760091] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    1.760091] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    1.760091] Call Trace:
[    1.760091]  deferred_init_pages+0x8f/0xbf
[    1.760091]  deferred_init_memmap+0x184/0x29d
[    1.760091]  ? deferred_free_pages.isra.97+0xba/0xba
[    1.760091]  kthread+0x112/0x130
[    1.760091]  ? kthread_flush_work_fn+0x10/0x10
[    1.760091]  ret_from_fork+0x35/0x40
[   89.123011] node 0 initialised, 1055935372 pages in 88650ms

Fixes: 3a2d7fa8a3 ("mm: disable interrupts while initializing deferred pages")
Reported-by: Yiqian Wei <yiwei@redhat.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[4.17+]
Link: http://lkml.kernel.org/r/20200403140952.17177-4-pasha.tatashin@soleen.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Pavel Tatashin
3d060856ad mm: initialize deferred pages with interrupts enabled 
Initializing struct pages is a long task and keeping interrupts disabled
for the duration of this operation introduces a number of problems.

1. jiffies are not updated for long period of time, and thus incorrect time
   is reported. See proposed solution and discussion here:
   lkml/20200311123848.118638-1-shile.zhang@linux.alibaba.com
2. It prevents farther improving deferred page initialization by allowing
   intra-node multi-threading.

We are keeping interrupts disabled to solve a rather theoretical problem
that was never observed in real world (See 3a2d7fa8a3).

Let's keep interrupts enabled. In case we ever encounter a scenario where
an interrupt thread wants to allocate large amount of memory this early in
boot we can deal with that by growing zone (see deferred_grow_zone()) by
the needed amount before starting deferred_init_memmap() threads.

Before:
[    1.232459] node 0 initialised, 12058412 pages in 1ms

After:
[    1.632580] node 0 initialised, 12051227 pages in 436ms

Fixes: 3a2d7fa8a3 ("mm: disable interrupts while initializing deferred pages")
Reported-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Yiqian Wei <yiwei@redhat.com>
Cc: <stable@vger.kernel.org>	[4.17+]
Link: http://lkml.kernel.org/r/20200403140952.17177-3-pasha.tatashin@soleen.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Daniel Jordan
117003c327 mm/pagealloc.c: call touch_nmi_watchdog() on max order boundaries in deferred init 
Patch series "initialize deferred pages with interrupts enabled", v4.

Keep interrupts enabled during deferred page initialization in order to
make code more modular and allow jiffies to update.

Original approach, and discussion can be found here:
 http://lkml.kernel.org/r/20200311123848.118638-1-shile.zhang@linux.alibaba.com

This patch (of 3):

deferred_init_memmap() disables interrupts the entire time, so it calls
touch_nmi_watchdog() periodically to avoid soft lockup splats.  Soon it
will run with interrupts enabled, at which point cond_resched() should be
used instead.

deferred_grow_zone() makes the same watchdog calls through code shared
with deferred init but will continue to run with interrupts disabled, so
it can't call cond_resched().

Pull the watchdog calls up to these two places to allow the first to be
changed later, independently of the second.  The frequency reduces from
twice per pageblock (init and free) to once per max order block.

Fixes: 3a2d7fa8a3 ("mm: disable interrupts while initializing deferred pages")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: James Morris <jmorris@namei.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Yiqian Wei <yiwei@redhat.com>
Cc: <stable@vger.kernel.org>	[4.17+]
Link: http://lkml.kernel.org/r/20200403140952.17177-2-pasha.tatashin@soleen.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Anshuman Khandual
ae70eddd56 mm/page_alloc: restrict and formalize compound_page_dtors[] 
Restrict elements in compound_page_dtors[] array per NR_COMPOUND_DTORS and
explicitly position them according to enum compound_dtor_id.  This
improves protection against possible misalignment between
compound_page_dtors[] and enum compound_dtor_id later on.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/1589795958-19317-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Charan Teja Reddy
aa09259109 mm, page_alloc: reset the zone->watermark_boost early 
Updating the zone watermarks by any means, like min_free_kbytes,
water_mark_scale_factor etc, when ->watermark_boost is set will result in
higher low and high watermarks than the user asked.

Below are the steps to reproduce the problem on system setup of Android
kernel running on Snapdragon hardware.

1) Default settings of the system are as below:

   #cat /proc/sys/vm/min_free_kbytes = 5162
   #cat /proc/zoneinfo | grep -e boost -e low -e "high " -e min -e Node
	Node 0, zone   Normal
		min      797
		low      8340
		high     8539

2) Monitor the zone->watermark_boost(by adding a debug print in the
   kernel) and whenever it is greater than zero value, write the same
   value of min_free_kbytes obtained from step 1.

   #echo 5162 > /proc/sys/vm/min_free_kbytes

3) Then read the zone watermarks in the system while the
   ->watermark_boost is zero.  This should show the same values of
   watermarks as step 1 but shown a higher values than asked.

   #cat /proc/zoneinfo | grep -e boost -e low -e "high " -e min -e Node
	Node 0, zone   Normal
		min      797
		low      21148
		high     21347

These higher values are because of updating the zone watermarks using the
macro min_wmark_pages(zone) which also adds the zone->watermark_boost.

	#define min_wmark_pages(z) (z->_watermark[WMARK_MIN] +
					z->watermark_boost)

So the steps that lead to the issue are:

1) On the extfrag event, watermarks are boosted by storing the required
   value in ->watermark_boost.

2) User tries to update the zone watermarks level in the system through
   min_free_kbytes or watermark_scale_factor.

3) Later, when kswapd woke up, it resets the zone->watermark_boost to
   zero.

In step 2), we use the min_wmark_pages() macro to store the watermarks
in the zone structure thus the values are always offsetted by
->watermark_boost value. This can be avoided by resetting the
->watermark_boost to zero before it is used.

Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Link: http://lkml.kernel.org/r/1589457511-4255-1-git-send-email-charante@codeaurora.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00
Sandipan Das
b418a0f9f0 mm/page_alloc.c: reset numa stats for boot pagesets 
Initially, the per-cpu pagesets of each zone are set to the boot pagesets.
The real pagesets are allocated later but before that happens, page
allocations do occur and the numa stats for the boot pagesets get
incremented since they are common to all zones at that point.

The real pagesets, however, are allocated for the populated zones only.
Unpopulated zones, like those associated with memory-less nodes, continue
using the boot pageset and end up skewing the numa stats of the
corresponding node.

E.g.

  $ numactl -H
  available: 2 nodes (0-1)
  node 0 cpus: 0 1 2 3
  node 0 size: 0 MB
  node 0 free: 0 MB
  node 1 cpus: 4 5 6 7
  node 1 size: 8131 MB
  node 1 free: 6980 MB
  node distances:
  node   0   1
    0:  10  40
    1:  40  10

  $ numastat
                             node0           node1
  numa_hit                     108           56495
  numa_miss                      0               0
  numa_foreign                   0               0
  interleave_hit                 0            4537
  local_node                   108           31547
  other_node                     0           24948

Hence, the boot pageset stats need to be cleared after the real pagesets
are allocated.

After this point, the stats of the boot pagesets do not change as page
allocations requested for a memory-less node will either fail (if
__GFP_THISNODE is used) or get fulfilled by a preferred zone of a
different node based on the fallback zonelist.

[sandipan@linux.ibm.com: v3]
  Link: http://lkml.kernel.org/r/20200511170356.162531-1-sandipan@linux.ibm.com
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Link: http://lkml.kernel.org/r/9c9c2d1b15e37f6e6bf32f99e3100035e90c4ac9.1588868430.git.sandipan@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-06-03 20:09:45 -07:00