Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756962AbYCDClW (ORCPT ); Mon, 3 Mar 2008 21:41:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752333AbYCDClO (ORCPT ); Mon, 3 Mar 2008 21:41:14 -0500 Received: from mga02.intel.com ([134.134.136.20]:3423 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681AbYCDClO (ORCPT ); Mon, 3 Mar 2008 21:41:14 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,441,1199692800"; d="scan'208";a="349364633" Subject: Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline From: Yi Yang Reply-To: yi.y.yang@intel.com To: Dmitry Adamushko Cc: Ingo Molnar , akpm@linux-foundation.org, linux-kernel@vger.kernel.org In-Reply-To: References: <1204483329.3607.8.camel@yangyi-dev.bj.intel.com> <20080303115652.GA9257@elte.hu> Content-Type: text/plain Organization: Intel Date: Mon, 03 Mar 2008 22:53:34 +0800 Message-Id: <1204556014.3842.13.camel@yangyi-dev.bj.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 (2.10.1-4.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1469 Lines: 39 On Mon, 2008-03-03 at 13:02 +0100, Dmitry Adamushko wrote: > On 03/03/2008, Ingo Molnar wrote: > > > > * Dmitry Adamushko wrote: > > > > > per_cpu(watchdog_task, hotcpu) = NULL; > > > + mlseep(1); > > > > > > that wont build very well ... > > yeah, I forgot to mention that it's not even compile-tested :-/ > I re-created it from scratch instead of looking for the original one. > > please, this one (again, not compile-tested) > > --- softlockup-prev-2.c 2008-03-03 12:38:36.000000000 +0100 > +++ softlockup.c 2008-03-03 13:00:20.000000000 +0100 > @@ -294,6 +294,7 @@ cpu_callback(struct notifier_block *nfb, > case CPU_DEAD_FROZEN: > p = per_cpu(watchdog_task, hotcpu); > per_cpu(watchdog_task, hotcpu) = NULL; > + msleep(1); > kthread_stop(p); > break; > #endif /* CONFIG_HOTPLUG_CPU */ I don't think it can fix this issue, it only gives one chance to scheduler, i think there are another potential and very serious issues inside of scheduler or locking or what else we don't know. Maybe migration is a doubtful point as Gautham mentioned. > -- 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/