| From caiqian@redhat.com Fri Feb 1 13:47:04 2013 |
| From: CAI Qian <caiqian@redhat.com> |
| Date: Thu, 24 Jan 2013 22:50:09 -0500 (EST) |
| Subject: slub: assign refcount for kmalloc_caches |
| To: stable@vger.kernel.org |
| Cc: Christoph Lameter <cl@linux.com>, Joonsoo Kim <js1304@gmail.com>, Paul Hargrove <phhargrove@lbl.gov> |
| Message-ID: <2142250133.9176397.1359085809116.JavaMail.root@redhat.com> |
| |
| From: CAI Qian <caiqian@redhat.com> |
| |
| 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. |
| |
| Reported-by: Paul Hargrove <phhargrove@lbl.gov> |
| Cc: Christoph Lameter <cl@linux.com> |
| Signed-off-by: Joonsoo Kim <js1304@gmail.com> |
| Signed-off-by: CAI Qian <caiqian@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/slub.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/mm/slub.c |
| +++ b/mm/slub.c |
| @@ -3279,6 +3279,7 @@ static struct kmem_cache *__init create_ |
| if (kmem_cache_open(s, flags)) |
| goto panic; |
| |
| + s->refcount = 1; |
| list_add(&s->list, &slab_caches); |
| return s; |
| |