Commit 8a5b20ae authored Jul 02, 2014 by Joonsoo Kim Committed by Linus Torvalds Jul 03, 2014

slub: fix off by one in number of slab tests



min_partial means minimum number of slab cached in node partial list.
So, if nr_partial is less than it, we keep newly empty slab on node
partial list rather than freeing it.  But if nr_partial is equal or
greater than it, it means that we have enough partial slabs so should
free newly empty slab.  Current implementation missed the equal case so
if we set min_partial is 0, then, at least one slab could be cached.
This is critical problem to kmemcg destroying logic because it doesn't
works properly if some slabs is cached.  This patch fixes this problem.

Fixes 91cb69620284 ("slub: make dead memcg caches discard free slabs
immediately").

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent dc78327c

mm/slub.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1881,7 +1881,7 @@ redo:

		new.frozen = 0;

		if (!new.inuse && n->nr_partial > s->min_partial)
		if (!new.inuse && n->nr_partial >= s->min_partial)
		m = M_FREE;
		else if (new.freelist) {
		m = M_PARTIAL;
		@@ -1992,7 +1992,7 @@ static void unfreeze_partials(struct kmem_cache *s,
		new.freelist, new.counters,
		"unfreezing slab"));

		if (unlikely(!new.inuse && n->nr_partial > s->min_partial)) {
		if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
		page->next = discard_page;
		discard_page = page;
		} else {
		@@ -2620,7 +2620,7 @@ static void __slab_free(struct kmem_cache s, struct page page,
		return;
		}

		if (unlikely(!new.inuse && n->nr_partial > s->min_partial))
		if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
		goto slab_empty;

		/*

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