Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755623AbYCENy4 (ORCPT ); Wed, 5 Mar 2008 08:54:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754203AbYCENx7 (ORCPT ); Wed, 5 Mar 2008 08:53:59 -0500 Received: from x346.tv-sign.ru ([89.108.83.215]:59963 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754151AbYCENx5 (ORCPT ); Wed, 5 Mar 2008 08:53:57 -0500 Date: Wed, 5 Mar 2008 16:53:14 +0300 From: Oleg Nesterov To: Gautham R Shenoy Cc: Yi Yang , Ingo Molnar , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Thomas Gleixner Subject: Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline Message-ID: <20080305135314.GA84@tv-sign.ru> References: <1204483329.3607.8.camel@yangyi-dev.bj.intel.com> <20080303153154.GA11288@in.ibm.com> <1204555505.3842.4.camel@yangyi-dev.bj.intel.com> <20080304052613.GA28632@in.ibm.com> <20080304150107.GA564@tv-sign.ru> <20080305100509.GA9265@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080305100509.GA9265@in.ibm.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1115 Lines: 31 On 03/05, Gautham R Shenoy wrote: > > On Tue, Mar 04, 2008 at 06:01:07PM +0300, Oleg Nesterov wrote: > > On 03/04, Gautham R Shenoy wrote: > > > > > > So at times, the callback thread is blocked on kthread_stop(k) in > > > softlockup.c, while other time, it was blocked in > > > cleanup_workqueue_threads() in workqueue.c. > > > > >From another message: > > > > > > However, it remains in R< state > > > > What about cwq->thread? Was it TASK_RUNNING too? > > No, it was in TASK_UNINTERRUPTIBLE state. The last thing it ever > executed was the wait_for_completion in flush_cpu_workqueue() You misunderstood ;) The task doing _cpu_down() hang in flush_cpu_workqueue(), because cwq->thread doesn't want to die. But what was cwq->thread->state? Could you try the patch? Yi constantly sees the tasks in R< state. I am starting to suspect some scheduling issue. Oleg. -- 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/