From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754351Ab2JSAim (ORCPT ); Thu, 18 Oct 2012 20:38:42 -0400 Received: from mail-da0-f46.google.com ([209.85.210.46]:44503 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750968Ab2JSAik (ORCPT ); Thu, 18 Oct 2012 20:38:40 -0400 Date: Thu, 18 Oct 2012 17:38:35 -0700 From: Tejun Heo To: Frederic Weisbecker Cc: Li Zefan , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, LKML Subject: Re: Is not locking task_lock in cgroup_fork() safe? Message-ID: <20121019003835.GE13370@google.com> References: <20121008020000.GB2575@localhost> <20121016193341.GD16166@google.com> <20121018200705.GG13370@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Frederic. On Thu, Oct 18, 2012 at 10:53:47PM +0200, Frederic Weisbecker wrote: > > For now, I'll revert the patches and cc stable. Let's think about > > improving it later. > > Ok for reverting in cgroup_fork(). Is it necessary for the > cgroup_post_fork() thing? I don't immediately see any race involved > there. Even if there isn't an actual race, the comment is dead wrong. I'm reverting the following three patches. Let's try again later. 7e381b0eb1 ("cgroup: Drop task_lock(parent) on cgroup_fork()") 7e3aa30ac8 ("cgroup: Remove task_lock() from cgroup_post_fork()") c84cdf75cc ("cgroup: Remove unnecessary task_lock before fetching css_set on migration") Thanks. -- tejun