When running ltp stress test for 7*24 hours, the vmscan occasionally complains the following warning continuously, mb_cache_scan+0x0/0x3f0 negative objects to delete nr=-9232265467809300450 ... The tracing result shows the freeable(mb_cache_count returns) is -1, which causes the continuous accumulation and overflow of total_scan. This patch make sure the mb_cache_count not return negative value, which make the mbcache shrinker more robust. Signed-off-by: Jiang Biao <jiang.biao2@xxxxxxxxxx> --- fs/mbcache.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/mbcache.c b/fs/mbcache.c index d818fd2..b8b8b9c 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; } -- 2.7.4
