path: root/fs/mbcache.c
diff options
authorJiang Biao <jiang.biao2@zte.com.cn>2017-11-29 16:11:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-29 18:40:43 -0800
commitd5dabd633922ac5ee5bcc67748f7defb8b211469 (patch)
tree730e56bdd410584dc90fd8d80f5a9eda322dffc9 /fs/mbcache.c
parent90daf3062fc0f8f919d5496fe167bbd6016a6a63 (diff)
fs/mbcache.c: make count_objects() more robust
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>
Diffstat (limited to 'fs/mbcache.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/mbcache.c b/fs/mbcache.c
index d818fd236787..b8b8b9ced9f8 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,
+ /* Unlikely, but not impossible */
+ if (unlikely(cache->c_entry_count < 0))
+ return 0;
return cache->c_entry_count;