Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758221Ab2JSToX (ORCPT ); Fri, 19 Oct 2012 15:44:23 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:49540 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752624Ab2JSToV (ORCPT ); Fri, 19 Oct 2012 15:44:21 -0400 MIME-Version: 1.0 In-Reply-To: <20121019193808.GL13370@google.com> References: <20121008020000.GB2575@localhost> <20121019005922.GG13370@google.com> <20121019193808.GL13370@google.com> Date: Fri, 19 Oct 2012 15:44:20 -0400 Message-ID: Subject: Re: [PATCH cgroup/for-3.7-fixes 1/2] Revert "cgroup: Remove task_lock() from cgroup_post_fork()" From: Frederic Weisbecker To: Tejun Heo Cc: Li Zefan , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, LKML Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1489 Lines: 34 2012/10/19 Tejun Heo : > On Fri, Oct 19, 2012 at 09:35:26AM -0400, Frederic Weisbecker wrote: >> 2012/10/18 Tejun Heo : >> > From d935a5d6832a264ce52f4257e176f4f96cbaf048 Mon Sep 17 00:00:00 2001 >> > From: Tejun Heo >> > Date: Thu, 18 Oct 2012 17:40:30 -0700 >> > >> > This reverts commit 7e3aa30ac8c904a706518b725c451bb486daaae9. >> > >> > The commit incorrectly assumed that fork path always performed >> > threadgroup_change_begin/end() and depended on that for >> > synchronization against task exit and cgroup migration paths instead >> > of explicitly grabbing task_lock(). >> > >> > threadgroup_change is not locked when forking a new process (as >> > opposed to a new thread in the same process) and even if it were it >> > wouldn't be effective as different processes use different threadgroup >> > locks. >> > >> > Revert the incorrect optimization. >> >> Ok but there is still no good reason to task_lock() there. But the >> comment is indeed wrong, how about fixing it instead? I can send you >> a patch for that. > > For -stable, I think it's better to revert. If you want to remove > task_lock, let's do it for 3.8. I don't think that a wrong comment justifies a patch to stable. -- 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/