[PATCH] slub: assign refcount for kmalloc_caches

[Joonsoo Kim <js1304@gmail.com>]

commit cce89f4f6911286500cf7be0363f46c9b0a12ce0('Move kmem_cache
refcounting to common code') moves some refcount manipulation code to
common code. Unfortunately, it also removed refcount assignment for
kmalloc_caches. So, kmalloc_caches's refcount is initially 0.
This makes errornous situation.

Paul Hargrove report that when he create a 8-byte kmem_cache and
destory it, he encounter below message.
'Objects remaining in kmalloc-8 on kmem_cache_close()'

8-byte kmem_cache merge with 8-byte kmalloc cache and refcount is
increased by one. So, resulting refcount is 1. When destory it, it hit
refcount = 0, then kmem_cache_close() is executed and error message is
printed.

This patch assign initial refcount 1 to kmalloc_caches, so fix this
errornous situtation.

Cc: <stable@vger.kernel.org> # v3.7
Cc: Christoph Lameter <cl@linux.com>
Reported-by: Paul Hargrove <phhargrove@lbl.gov>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>

diff --git a/mm/slub.c b/mm/slub.c
index a0d6984..321afab 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3279,6 +3279,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name,
 	if (kmem_cache_open(s, flags))
 		goto panic;
 
+	s->refcount = 1;
 	list_add(&s->list, &slab_caches);
 	return s;
 
-- 
1.7.9.5

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