Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL for 4.9 38/55] fs/mbcache.c: make count_objects() more robust | Date | Wed, 24 Jan 2018 04:15:49 +0000 |
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From: Jiang Biao <jiang.biao2@zte.com.cn>
[ Upstream commit d5dabd633922ac5ee5bcc67748f7defb8b211469 ]
When running ltp stress test for 7*24 hours, vmscan occasionally emits the following warning continuously:
mb_cache_scan+0x0/0x3f0 negative objects to delete nr=-9232265467809300450 ...
Tracing shows the freeable(mb_cache_count returns) is -1, which causes the continuous accumulation and overflow of total_scan.
This patch makes sure that mb_cache_count() cannot return a negative value, which makes the mbcache shrinker more robust.
Link: http://lkml.kernel.org/r/1511753419-52328-1-git-send-email-jiang.biao2@zte.com.cn Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: <zhong.weidong@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> --- fs/mbcache.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/mbcache.c b/fs/mbcache.c index c5bd19ffa326..35ab4187bfe1 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -269,6 +269,9 @@ static unsigned long mb_cache_count(struct shrinker *shrink, struct mb_cache *cache = container_of(shrink, struct mb_cache, c_shrink); + /* Unlikely, but not impossible */ + if (unlikely(cache->c_entry_count < 0)) + return 0; return cache->c_entry_count; } -- 2.11.0
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