From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753159Ab0EGGyT (ORCPT ); Fri, 7 May 2010 02:54:19 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:60079 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752669Ab0EGGyR (ORCPT ); Fri, 7 May 2010 02:54:17 -0400 Message-ID: <4BE3B985.1000407@cn.fujitsu.com> Date: Fri, 07 May 2010 14:56:05 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com, Jens Axboe CC: "containers@lists.osdl.org" , Paul Menage , Andrew Morton , LKML , Vivek Goyal , Gui Jianfeng Subject: Re: [PATCH 5/5] blk-cgroup: Fix an RCU warning in blkiocg_create() References: <4BD016F4.8060108@cn.fujitsu.com> <4BD017AC.1020209@cn.fujitsu.com> <20100422195725.GM2524@linux.vnet.ibm.com> In-Reply-To: <20100422195725.GM2524@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul E. McKenney wrote: > On Thu, Apr 22, 2010 at 05:32:28PM +0800, Li Zefan wrote: >> with CONFIG_PROVE_RCU=y, a warning can be triggered: >> >> # mount -t cgroup -o blkio xxx /mnt >> # mkdir /mnt/subgroup >> >> ... >> kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection! >> ... >> >> To fix this, we avoid caling css_depth() here, which is a bit simpler >> than the original code. > > Queued for 2.6.34, thank you! > Seems neither you nor Jens queued this patch... > Thanx, Paul > >> Signed-off-by: Li Zefan >> --- >> block/blk-cgroup.c | 8 ++++---- >> 1 files changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index 5fe03de..2cc682b 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -286,16 +286,16 @@ done: >> static struct cgroup_subsys_state * >> blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) >> { >> - struct blkio_cgroup *blkcg, *parent_blkcg; >> + struct blkio_cgroup *blkcg; >> + struct cgroup *parent = cgroup->parent; >> >> - if (!cgroup->parent) { >> + if (!parent) { >> blkcg = &blkio_root_cgroup; >> goto done; >> } >> >> /* Currently we do not support hierarchy deeper than two level (0,1) */ >> - parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent); >> - if (css_depth(&parent_blkcg->css) > 0) >> + if (parent != cgroup->top_cgroup) >> return ERR_PTR(-EINVAL); >> >> blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); >> -- >> 1.6.3 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ > >