On Wed, Jan 24, 2018 at 04:15:49AM +0000, Sasha Levin wrote:
> From: Jiang Biao <jiang.bi...@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.bi...@zte.com.cn
> Signed-off-by: Jiang Biao <jiang.bi...@zte.com.cn>
> Cc: Al Viro <v...@zeniv.linux.org.uk>
> Cc: Minchan Kim <minc...@kernel.org>
> Cc: Michal Hocko <mho...@kernel.org>
> Cc: <zhong.weid...@zte.com.cn>
> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
> Signed-off-by: Sasha Levin <alexander.le...@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;
> }
This patch is broken and is reverted in linux-next, via ext4/dev:
bbe45d2460da ("mbcache: revert "fs/mbcache.c: make count_objects() more
robust"")
Can you please update your "autosel" script/process/whatever to not select
commits that are reverted?
