From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754638Ab1LVCCH (ORCPT ); Wed, 21 Dec 2011 21:02:07 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:40392 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752446Ab1LVCCE (ORCPT ); Wed, 21 Dec 2011 21:02:04 -0500 Date: Wed, 21 Dec 2011 18:01:57 -0800 From: Tejun Heo To: Frederic Weisbecker Cc: tip-bot for Daisuke Nishimura , linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, pjt@google.com, tglx@linutronix.de, mingo@elte.hu Subject: Re: [tip:sched/core] sched: Fix cgroup movement of forking process Message-ID: <20111222020157.GR9213@google.com> References: <20111215143655.662676b0.nishimura@mxp.nes.nec.co.jp> <20111221172632.GD9213@google.com> <20111221173733.GF9213@google.com> <20111222015440.GM17668@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111222015440.GM17668@somewhere> 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, On Thu, Dec 22, 2011 at 02:54:42AM +0100, Frederic Weisbecker wrote: > > Frederic, so, it seems we actually have race conditions here. I > > really wish cgroup made sure that things like this can't happen even > > if we pay a bit of overhead in relatively cold paths. I could be > > being unrealistic tho. Any ideas? > > Hmm, I'm a bit confused about the issue. But doesn't this patch fix the issue? Yeah, I was just saying it would be nice if we don't have to fix the issue. > Also the parent can't be calling sched_fork() and cgroup_exit() at > the same time. Hmmm... so this one can't happen anymore but there are races involving cgroup_exit() which doesn't have anything to do with threadgroup lock (Dalsuke has more patches), so this doesn't really matter. Let's forget about this thread. Thanks. -- tejun