path: root/mm
diff options
authorKirill Tkhai <ktkhai@virtuozzo.com>2018-08-21 21:51:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:43 -0700
commit8df4a44cc46bf9dcfb80a37a59ae5dea2232dc58 (patch)
treea7add543b55c9d3e583bc5af2190fc38c92ad11a /mm
parent0633da48f0793aeba27f82d30605624416723a91 (diff)
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')
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)
list_add_tail(&shrinker->list, &shrinker_list);
- idr_replace(&shrinker_idr, shrinker, shrinker->id);
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+ idr_replace(&shrinker_idr, shrinker, shrinker->id);