From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755808Ab2DIOBc (ORCPT ); Mon, 9 Apr 2012 10:01:32 -0400 Received: from mx2.parallels.com ([64.131.90.16]:40016 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753487Ab2DIOBb (ORCPT ); Mon, 9 Apr 2012 10:01:31 -0400 Message-ID: <4F82EB5C.7090003@parallels.com> Date: Mon, 9 Apr 2012 10:59:56 -0300 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: Tejun Heo , Li Zefan , Paul Turner , , "devel@openvz.org" , linux-kernel Subject: bind() call in cgroup's css structure Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [201.82.19.44] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Tejun, During your cgroup refactor, I was wondering if you have any plans to get rid of the bind() callback that is called when hierarchies are moved? At least in tree, there seems to be no users for that. I actually planned to use it myself, to start or remove a jump label when cpuacct and cpu cgroups were comounted. Problem is, because we have some calls in the cpuset cgroup from inside the cpu hotplug handler, we end up taking the almighty cgroup_mutex from inside the cpu_hotplug.lock. jump labels take it in most arches through the get_online_cpus() function call. This means we effectively can't apply jump labels with the cgroup_mutex held, which is the case throughout the whole bind() call. All that explained, I figured I might as well ask before I attempted a solution to that myself: as much as populate(), bind seems to be one of the overly complicated callbacks, designed for a scenario in which everything can come and go at will, which is something we're trying to fix. thanks in advance for your answer!