Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751642Ab0DOGjI (ORCPT ); Thu, 15 Apr 2010 02:39:08 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:53529 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751493Ab0DOGjG (ORCPT ); Thu, 15 Apr 2010 02:39:06 -0400 Message-ID: <4BC6B4B3.8070000@cn.fujitsu.com> Date: Thu, 15 Apr 2010 14:39:47 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: Paul Menage CC: paulmck@linux.vnet.ibm.com, Rusty Russell , linux-kernel@vger.kernel.org, linux-mm@kvack.org, containers@lists.linux-foundation.org, balbir@linux.vnet.ibm.com, lizf@cn.fujitsu.com, Oleg Nesterov , Ingo Molnar Subject: Re: Lockdep splat in cpuset code acquiring alloc_lock References: <20100414202347.GA26791@linux.vnet.ibm.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: 1135 Lines: 31 CC Oleg CC Ingo on 2010-4-15 5:10, Paul Menage wrote: > Looks like select_fallback_rq() shouldn't be calling > cpuset_cpus_allowed_locked(), which does a task_lock(), which isn't > IRQ safe. Also, according to its comments that should only be held > with the cpuset callback_mutex held, which seems unlikely from a > softirq handler. > > Also, calling cpuset_cpus_allowed_locked(p, &p->cpus_allowed) stomps > on state in p without (AFAICS) synchronization. > > The description of commit e76bd8d9850c2296a7e8e24c9dce9b5e6b55fe2f > includes the phrase " I'm fairly sure this works, but there might be a > deadlock hiding" although I think that the lockdep-reported problem is > different than what Rusty had in mind. This problem have been fixed by Oleg Nesterov, and the patchset was merged into tip tree, but it's scheduled for .35 ... http://lkml.org/lkml/2010/3/15/73 Thanks! Miao -- 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/