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| author |   Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2022-07-22 19:45:39 +0900 |
|---|---|---|
| committer |   akpm <akpm@linux-foundation.org> | 2022-07-29 18:07:18 -0700 |
| commit | 68aaee147e597b495622b7c9038e5922c7c61f57 (patch) | |
| tree | 2da6862990dfea13856ad34b55e41e2ab1d6c1ca /mm/mmap.c | |
| parent | mm/gup.c: fix formatting in check_and_migrate_movable_page() (diff) | |
| download | linux-dev-68aaee147e597b495622b7c9038e5922c7c61f57.tar.xz linux-dev-68aaee147e597b495622b7c9038e5922c7c61f57.zip | |
mm: memcontrol: fix potential oom_lock recursion deadlock
syzbot is reporting GFP_KERNEL allocation with oom_lock held when
reporting memcg OOM [1]. If this allocation triggers the global OOM
situation then the system can livelock because the GFP_KERNEL
allocation with oom_lock held cannot trigger the global OOM killer
because __alloc_pages_may_oom() fails to hold oom_lock.
Fix this problem by removing the allocation from memory_stat_format()
completely, and pass static buffer when calling from memcg OOM path.
Note that the caller holding filesystem lock was the trigger for syzbot
to report this locking dependency. Doing GFP_KERNEL allocation with
filesystem lock held can deadlock the system even without involving OOM
situation.
Link: https://syzkaller.appspot.com/bug?extid=2d2aeadc6ce1e1f11d45 [1]
Link: https://lkml.kernel.org/r/86afb39f-8c65-bec2-6cfc-c5e3cd600c0b@I-love.SAKURA.ne.jp
Fixes: c8713d0b23123759 ("mm: memcontrol: dump memory.stat during cgroup OOM")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+2d2aeadc6ce1e1f11d45@syzkaller.appspotmail.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
0 files changed, 0 insertions, 0 deletions