This is for stable-3.7.y only and this problem has already been solved
in mainline through some slab/slub re-work which isn't suitable to
backport here. See create_kmalloc_cache() in mm/slab_common.c there.
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 erroneous 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 destroy 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
erroneous situation.
Cc: <[email protected]> # v3.7
Cc: Christoph Lameter <[email protected]>
Reported-by: Paul Hargrove <[email protected]>
Signed-off-by: Joonsoo Kim <[email protected]>
Signed-off-by: CAI Qian <[email protected]>
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;
--
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