From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753140Ab1K1Qb5 (ORCPT ); Mon, 28 Nov 2011 11:31:57 -0500 Received: from mail-bw0-f46.google.com ([209.85.214.46]:44205 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751904Ab1K1Qb4 (ORCPT ); Mon, 28 Nov 2011 11:31:56 -0500 Date: Mon, 28 Nov 2011 20:31:51 +0400 From: Cyrill Gorcunov To: Tejun Heo Cc: LKML , Li Zefan , Matt Helsley , Andrey Vagin , Pavel Emelyanov Subject: Re: [RFC] cgroups: freezer -- Allow to attach a task to a frozen cgroup Message-ID: <20111128163151.GN1775@moon> References: <20111128120813.GK1775@moon> <20111128160844.GB18864@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111128160844.GB18864@google.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 On Mon, Nov 28, 2011 at 08:08:44AM -0800, Tejun Heo wrote: > On Mon, Nov 28, 2011 at 04:08:13PM +0400, Cyrill Gorcunov wrote: > > In checkpoint/restore we need an ability to attach pids to > > a frozen cgroup. Thus once pid reaches a frozen cgroup it is > > not rejected, but the task get frozen immediately. > > > > Signed-off-by: Cyrill Gorcunov > > --- > > > > I would really appreciate complains and comments. > > First of all, both freezer and cgroup have non-trivial pending > patchsets (e.g. ->can_attach_task() is scheduled for removal) and I > have changes which basically try to achieve about the same thing, so > let's slow down a bit. I think the problem is a bit more complex. > > Some thoughts I have on cgroup freezer ATM, > ... > > * Another improvement that I want to have is allowing cgroup frozen > tasks to be killed. I don't think this matters for system freezer > but for cgroup freezer both oom killer and systemd want it. > * Run ptrace over frozen tasks ;) > So, while I agree with the direction of this patch, I think this > definitely needs a lot more work to go in. I don't think we can do > much until the freezer and cgroup changes are settled. The freezer > part is now in Rafael's tree, the cgroup part is going under Linus' > review. Once they're complete, I'll provide a merged branch that > further cgroup works can be based on. > Thanks a lot for comments, Tejun! For own needs I'll make a stub in our user-space tool, once things are settled down we can move on.