From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754828AbZEYJN4 (ORCPT ); Mon, 25 May 2009 05:13:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752092AbZEYJNt (ORCPT ); Mon, 25 May 2009 05:13:49 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:52624 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751957AbZEYJNt (ORCPT ); Mon, 25 May 2009 05:13:49 -0400 Message-ID: <4A1A6192.6050608@cn.fujitsu.com> Date: Mon, 25 May 2009 17:14:58 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Dhaval Giani CC: KAMEZAWA Hiroyuki , Andrew Morton , Paul Menage , LKML , Linux Containers , Balbir Singh , libcg-devel@lists.sourceforge.net Subject: Re: [PATCH] cgroups: handle failure of cgroup_populate_dir() at mount/remount References: <4A16153C.2080004@cn.fujitsu.com> <20090522172545.1e5e5f81.kamezawa.hiroyu@jp.fujitsu.com> <4A1663C2.4080401@cn.fujitsu.com> <20090522173421.ecacb40e.kamezawa.hiroyu@jp.fujitsu.com> <20090522091034.GC8696@linux.vnet.ibm.com> In-Reply-To: <20090522091034.GC8696@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dhaval Giani wrote: > On Fri, May 22, 2009 at 05:34:21PM +0900, KAMEZAWA Hiroyuki wrote: >> On Fri, 22 May 2009 16:35:14 +0800 >> Li Zefan wrote: >> >>> KAMEZAWA Hiroyuki wrote: >>>> On Fri, 22 May 2009 11:00:12 +0800 >>>> Li Zefan wrote: >>>> >>>>> Now we have 'stat' file in both memory and cpuacct subsystems. If we >>>>> mount these 2 subsystems with option 'noprefix', the creation of 'stat' >>>>> file for cpuacct will fail, but without any notificatin to the user. >>>>> >>>>> With this patch, we fail the mount/remount in this case. >>>>> >>>> Hm, shouldn't we allow "noprefix" to be effective only agaisnt cpuset ? >>>> I think it's just for backward-compatibility of cpuset. >>>> (I don't like the option at all.) >>>> >>> Yes, this mount option was introduced for cpuset. But it has been here for >>> a long time and people may use it when mounting other cgroup subsystems, >>> then is it OK to change to restrict its use within cpuset only? >> Asking libcgroup people may be appropriate...added CC. > > We just realized that we were not handling the noprefix usage in I guess handling noprefix will increase complexity of libcgroup? since we can't figure out which subsystem the file belongs to by looking at the prefix of the file. > libcgroup. From the pov of the library, the option should either not > exist for any subsystem or for all of them. Anything else would mean > having to add special cases. > I don't see how to totally remove 'noprefix' while keep the backward compatibility of cpuset, so I think we have to reserve it, and fix name collision caused by this option.