From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754665Ab3CUBW5 (ORCPT ); Wed, 20 Mar 2013 21:22:57 -0400 Received: from szxga01-in.huawei.com ([119.145.14.64]:49369 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496Ab3CUBWq (ORCPT ); Wed, 20 Mar 2013 21:22:46 -0400 Message-ID: <514A60CD.60208@huawei.com> Date: Thu, 21 Mar 2013 09:22:21 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Tejun Heo CC: LKML , Cgroups , , KAMEZAWA Hiroyuki , Michal Hocko , Johannes Weiner , Glauber Costa Subject: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name() Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.68.215] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As cgroup supports rename, it's unsafe to dereference dentry->d_name without proper vfs locks. Fix this by using cgroup_name(). Signed-off-by: Li Zefan --- This patch depends on "cgroup: fix cgroup_path() vs rename() race", which has been queued for 3.10. --- mm/memcontrol.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 53b8201..72be5c9 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3217,17 +3217,16 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep) static char *memcg_cache_name(struct mem_cgroup *memcg, struct kmem_cache *s) { char *name; - struct dentry *dentry; + + name = (char *)__get_free_page(GFP_TEMPORARY); + if (!name) + return NULL; rcu_read_lock(); - dentry = rcu_dereference(memcg->css.cgroup->dentry); + snprintf(name, PAGE_SIZE, "%s(%d:%s)", s->name, memcg_cache_id(memcg), + cgroup_name(memcg->css.cgroup)); rcu_read_unlock(); - BUG_ON(dentry == NULL); - - name = kasprintf(GFP_KERNEL, "%s(%d:%s)", s->name, - memcg_cache_id(memcg), dentry->d_name.name); - return name; } @@ -3247,7 +3246,7 @@ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg, if (new) new->allocflags |= __GFP_KMEMCG; - kfree(name); + free_page((unsigned long)name); return new; } -- 1.8.0.2