Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758718Ab0BYBSi (ORCPT ); Wed, 24 Feb 2010 20:18:38 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:57468 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758572Ab0BYBSg (ORCPT ); Wed, 24 Feb 2010 20:18:36 -0500 Message-ID: <4B85CFD6.6010904@cn.fujitsu.com> Date: Thu, 25 Feb 2010 09:18:14 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0 MIME-Version: 1.0 To: David Rientjes CC: Nick Piggin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lee Schermerhorn Subject: Re: [regression] cpuset,mm: update tasks' mems_allowed in time (58568d2) References: <20100218134921.GF9738@laptop> <20100219033126.GI9738@laptop> <4B827043.3060305@cn.fujitsu.com> <4B838490.1050908@cn.fujitsu.com> <4B839E9D.8020604@cn.fujitsu.com> <4B84F2FD.6030605@cn.fujitsu.com> In-Reply-To: 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 Content-Length: 1140 Lines: 25 on 2010-2-25 5:08, David Rientjes wrote: > On Wed, 24 Feb 2010, Miao Xie wrote: > >> I think it is not a big deal because it is safe and doesn't cause any problem. >> Beside that, task->cpus_allowed is initialized to cpu_possible_mask on the no-cpuset >> kernel, so using cpu_possible_mask to initialize task->cpus_allowed is reasonable. >> (top cpuset is a special cpuset, isn't it?) >> > > I'm suprised that I can create a descendant cpuset of top_cpuset that > cannot include all of its parents' cpus and that the root cpuset's cpus > mask doesn't change when cpus are onlined/offlined. > top cpuset's cpus is consistent with cpu_online_mask because the kernel changes it when doing cpu hotplug. So the problem which you said doesn't exist. Just cpus_allowed of all tasks in the top cpuset is initialized to cpu_possible_mask in order to avoid updating them when doing cpu hotplug. -- 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/