The patch titled
Subject: fs/mbcache.c: make count_objects() more robust
has been added to the -mm tree. Its filename is
fs-mbcache-make-count_objects-more-robust.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-mbcache-make-count_objects-more-robust.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-mbcache-make-count_objects-more-robust.patch
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------------------------------------------------------
From: Jiang Biao <jiang.biao2@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Jiang Biao <jiang.biao2@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: <zhong.weidong@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/mbcache.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN fs/mbcache.c~fs-mbcache-make-count_objects-more-robust fs/mbcache.c
--- a/fs/mbcache.c~fs-mbcache-make-count_objects-more-robust
+++ a/fs/mbcache.c
@@ -269,6 +269,9 @@ static unsigned long mb_cache_count(stru
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;
}
_
Patches currently in -mm which might be from jiang.biao2@xxxxxxxxxx are
fs-mbcache-make-count_objects-more-robust.patch
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