From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754138Ab1H2QEg (ORCPT ); Mon, 29 Aug 2011 12:04:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58411 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753847Ab1H2QEY (ORCPT ); Mon, 29 Aug 2011 12:04:24 -0400 Date: Mon, 29 Aug 2011 18:00:31 +0200 From: Oleg Nesterov To: Tejun Heo Cc: "Rafael J. Wysocki" , Paul Menage , containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() Message-ID: <20110829160031.GB8392@redhat.com> References: <20110829140418.GB18871@mtj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110829140418.GB18871@mtj.dyndns.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/29, Tejun Heo wrote: > > --- work.orig/kernel/cgroup_freezer.c > +++ work/kernel/cgroup_freezer.c > @@ -311,14 +311,14 @@ static int freezer_change_state(struct c > if (goal_state == freezer->state) > goto out; > > - freezer->state = goal_state; > - > switch (goal_state) { > case CGROUP_THAWED: > + freezer->state = CGROUP_THAWED; > atomic_dec(&system_freezing_cnt); > unfreeze_cgroup(cgroup, freezer); > break; > case CGROUP_FROZEN: > + freezer->state = CGROUP_FREEZING; At first glance, this is correct. I'll try to recheck. But, > atomic_inc(&system_freezing_cnt); iiuc this becomes wrong... Suppose a user writes "FROZEN" twice, before freezer->state becomes CGROUP_FROZEN. I think we should actually fix the "goal_state == freezer->state" check above. Oleg.