From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756525Ab3BRRSX (ORCPT ); Mon, 18 Feb 2013 12:18:23 -0500 Received: from mail-da0-f48.google.com ([209.85.210.48]:47682 "EHLO mail-da0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756446Ab3BRRSV (ORCPT ); Mon, 18 Feb 2013 12:18:21 -0500 Date: Mon, 18 Feb 2013 09:18:17 -0800 From: Tejun Heo To: Li Zefan Cc: Cgroups , LKML , "Kirill A. Shutemov" Subject: Re: [PATCH v2] cgroup: fix cgroup_rmdir() vs close(eventfd) race Message-ID: <20130218171817.GF17414@htj.dyndns.org> References: <5121C647.7030608@huawei.com> <20130218171647.GD17414@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130218171647.GD17414@htj.dyndns.org> 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 On Mon, Feb 18, 2013 at 09:16:47AM -0800, Tejun Heo wrote: > On Mon, Feb 18, 2013 at 02:12:23PM +0800, Li Zefan wrote: > > commit 205a872bd6f9a9a09ef035ef1e90185a8245cc58 ("cgroup: fix lockdep > > warning for event_control") solved a deadlock by introducing a new > > bug. > > > > Move cgrp->event_list to a temporary list doesn't mean you can traverse > > this list locklessly, because at the same time cgroup_event_wake() can > > be called and remove the event from the list. The result of this race > > is disastrous. > > > > We adopt the way how kvm irqfd code implements race-free event removal, > > which is now described in the comments in cgroup_event_wake(). > > > > Signed-off-by: Li Zefan > > Applied to cgroup/for-3.9. Never mind. Just spotted v3 and applied that one instead. -- tejun