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| author | Kirill Tkhai <ktkhai@virtuozzo.com> | 2018-08-21 21:51:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:43 -0700 |
| commit | 8df4a44cc46bf9dcfb80a37a59ae5dea2232dc58 (patch) | |
| tree | a7add543b55c9d3e583bc5af2190fc38c92ad11a /mm/vmscan.c | |
| parent | 0633da48f0793aeba27f82d30605624416723a91 (diff) | |
| download | lwn-8df4a44cc46bf9dcfb80a37a59ae5dea2232dc58.tar.gz lwn-8df4a44cc46bf9dcfb80a37a59ae5dea2232dc58.zip | |
mm: check shrinker is memcg-aware in register_shrinker_prepared()
There is a sad BUG introduced in patch adding SHRINKER_REGISTERING.
shrinker_idr business is only for memcg-aware shrinkers. Only such type
of shrinkers have id and they must be finaly installed via idr_replace()
in this function. For !memcg-aware shrinkers we never initialize
shrinker->id field.
But there are all types of shrinkers passed to idr_replace(), and every
!memcg-aware shrinker with random ID (most probably, its id is 0)
replaces memcg-aware shrinker pointed by the ID in IDR.
This patch fixes the problem.
Link: http://lkml.kernel.org/r/8ff8a793-8211-713a-4ed9-d6e52390c2fc@virtuozzo.com
Fixes: 7e010df53c80 "mm: use special value SHRINKER_REGISTERING instead of list_empty() check"
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reported-by: <syzbot+d5f648a1bfe15678786b@syzkaller.appspotmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <syzkaller-bugs@googlegroups.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 4375b1e9bd56..3c6e2bfee427 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -408,7 +408,8 @@ void register_shrinker_prepared(struct shrinker *shrinker) down_write(&shrinker_rwsem); list_add_tail(&shrinker->list, &shrinker_list); #ifdef CONFIG_MEMCG_KMEM - idr_replace(&shrinker_idr, shrinker, shrinker->id); + if (shrinker->flags & SHRINKER_MEMCG_AWARE) + idr_replace(&shrinker_idr, shrinker, shrinker->id); #endif up_write(&shrinker_rwsem); } |