From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751386AbaBLGhT (ORCPT ); Wed, 12 Feb 2014 01:37:19 -0500 Received: from mail-qc0-f172.google.com ([209.85.216.172]:43231 "EHLO mail-qc0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750809AbaBLGhR (ORCPT ); Wed, 12 Feb 2014 01:37:17 -0500 Date: Wed, 12 Feb 2014 01:37:13 -0500 From: Tejun Heo To: Li Zefan Cc: Michal Hocko , LKML , Cgroups Subject: Re: [PATCH v2] cgroup: protect modifications to cgroup->idr with cgroup_mutex Message-ID: <20140212063713.GA7984@mtj.dyndns.org> References: <52FB14A5.9030307@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52FB14A5.9030307@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Li. On Wed, Feb 12, 2014 at 02:28:53PM +0800, Li Zefan wrote: > v2: > - Don't call deactivate_super() inside cgroup_mutex, as cgroup_kill_sb() > will be called if sb refcnt reaches 0. I don't think this can happen, > as cgroup_create() is called through vfs, so vfs should guarantee the > superblock won't disappear. Still better not depend on it even my guess > is probably correct. If the deadlock can't actually happen, I don't really care either way as the code goes away after kernfs conversion anyway. I've already applied v1, so if you think this change is important, can you send an incremental patch? Thanks! -- tejun