Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755948Ab2J2NwJ (ORCPT ); Mon, 29 Oct 2012 09:52:09 -0400 Received: from cantor2.suse.de ([195.135.220.15]:60301 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753311Ab2J2NwH (ORCPT ); Mon, 29 Oct 2012 09:52:07 -0400 Date: Mon, 29 Oct 2012 14:52:03 +0100 From: Michal Hocko To: Glauber Costa Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Tejun Heo , Li Zefan , Johannes Weiner , KAMEZAWA Hiroyuki , Balbir Singh Subject: Re: [PATCH v3 2/6] memcg: root_cgroup cannot reach mem_cgroup_move_parent Message-ID: <20121029135203.GA20757@dhcp22.suse.cz> References: <1351251453-6140-1-git-send-email-mhocko@suse.cz> <1351251453-6140-3-git-send-email-mhocko@suse.cz> <508E8910.40203@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <508E8910.40203@parallels.com> 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 Content-Length: 1298 Lines: 34 On Mon 29-10-12 17:48:00, Glauber Costa wrote: > On 10/26/2012 03:37 PM, Michal Hocko wrote: > > The root cgroup cannot be destroyed so we never hit it down the > > mem_cgroup_pre_destroy path and mem_cgroup_force_empty_write shouldn't > > even try to do anything if called for the root. > > > > This means that mem_cgroup_move_parent doesn't have to bother with the > > root cgroup and it can assume it can always move charges upwards. > > > > Signed-off-by: Michal Hocko > > Reviewed-by: Tejun Heo > > I think it would be safer to have this folded in the last patch, to > avoid a weird intermediate state (specially for force_empty). force_empty excludes root cgroup explicitly so there is no way to fail here. I have kept VM_BUG_ON for future reference but it also can go away completely. > Being a single statement, it doesn't confuse review so much. > > However, this is also pretty much just a nitpick, do as you prefer. > > Reviewed-by: Glauber Costa > -- Michal Hocko SUSE Labs -- 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/