From 09f363c7363eb10cfb4b82094bd7064e5608258b Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Mon, 31 Oct 2011 17:08:57 -0700 Subject: [PATCH] vmscan: fix shrinker callback bug in fs/super.c The callback must not return -1 when nr_to_scan is zero. Fix the bug in fs/super.c and add this requirement to the callback specification. Signed-off-by: Mikulas Patocka Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/super.c | 2 +- include/linux/shrinker.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index 3f56a269a4f4..32a81f3467e0 100644 --- a/fs/super.c +++ b/fs/super.c @@ -61,7 +61,7 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc) return -1; if (!grab_super_passive(sb)) - return -1; + return !sc->nr_to_scan ? 0 : -1; if (sb->s_op && sb->s_op->nr_cached_objects) fs_objects = sb->s_op->nr_cached_objects(sb); diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 790651b4e5ba..a83833a1f7a2 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -20,6 +20,7 @@ struct shrink_control { * 'nr_to_scan' entries and attempt to free them up. It should return * the number of objects which remain in the cache. If it returns -1, it means * it cannot do any scanning at this time (eg. there is a risk of deadlock). + * The callback must not return -1 if nr_to_scan is zero. * * The 'gfpmask' refers to the allocation we are currently trying to * fulfil. -- 2.30.2