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| author | Jiang Biao <jiang.biao2@zte.com.cn> | 2017-11-29 16:11:01 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-29 18:40:43 -0800 |
| commit | d5dabd633922ac5ee5bcc67748f7defb8b211469 (patch) | |
| tree | 730e56bdd410584dc90fd8d80f5a9eda322dffc9 /fs | |
| parent | 90daf3062fc0f8f919d5496fe167bbd6016a6a63 (diff) | |
| download | lwn-d5dabd633922ac5ee5bcc67748f7defb8b211469.tar.gz lwn-d5dabd633922ac5ee5bcc67748f7defb8b211469.zip | |
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')
| -rw-r--r-- | fs/mbcache.c | 3 |
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, c_shrink); + /* Unlikely, but not impossible */ + if (unlikely(cache->c_entry_count < 0)) + return 0; return cache->c_entry_count; } |