From 8df4a44cc46bf9dcfb80a37a59ae5dea2232dc58 Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Tue, 21 Aug 2018 21:51:49 -0700 Subject: 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 Reported-by: Cc: Andrey Ryabinin Cc: Johannes Weiner Cc: Josef Bacik Cc: Mel Gorman Cc: Michal Hocko Cc: Tetsuo Handa Cc: Shakeel Butt Cc: Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') 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); } -- cgit