From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030367AbXDZKKZ (ORCPT ); Thu, 26 Apr 2007 06:10:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030490AbXDZKKZ (ORCPT ); Thu, 26 Apr 2007 06:10:25 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:57596 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030367AbXDZKKX (ORCPT ); Thu, 26 Apr 2007 06:10:23 -0400 Date: Thu, 26 Apr 2007 15:39:22 +0530 From: Gautham R Shenoy To: Andrew Morton Cc: "Rafael J. Wysocki" , "Eric W. Biederman" , LKML , Oleg Nesterov Subject: Re: 2.6.21-rc7-mm1: BUG_ON in kthread_bind during _cpu_down Message-ID: <20070426100922.GB12892@in.ibm.com> Reply-To: ego@in.ibm.com References: <200704260110.22224.rjw@sisk.pl> <20070425165410.b73443b4.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070425165410.b73443b4.akpm@linux-foundation.org> User-Agent: Mutt/1.5.12-2006-07-14 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 25, 2007 at 04:54:10PM -0700, Andrew Morton wrote: > On Thu, 26 Apr 2007 01:10:21 +0200 "Rafael J. Wysocki" wrote: > > > Hi, > > > > The BUG_ON in khthread_bind (line 165 in kthread.c) triggers for me during > > attempted suspend to disk, when disable_nonboot_cpus() calls _cpu_down() > > (on x86_64). > Caused due to Oleg's patch http://lkml.org/lkml/2007/4/13/93. Agreed that most of the time a kthread_create(p) is followed by a kthread_bind(p), in which case the assertion WARN_ON(p->state != TASK_UNINTERRUPTIBLE) makes sense. But, in cpu hotplug case, we need to rebind the stop_machine_run thread from the cpu which has just been offlined to any online cpu. (kernel/cpu.c line 180) At this point, the thread would be in TASK_INTERRUPTIBLE waiting for us to call a kthread_stop on it.(kernel/kthread.c line 161) We only need to ensure in kthread_bind that the task which is being bound is not running or exiting. Doesn't matter if it's sleeping in TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE state. Signed-off-by: Gautham R Shenoy --- kernel/kthread.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-) Index: linux-2.6.21-rc7/kernel/kthread.c =================================================================== --- linux-2.6.21-rc7.orig/kernel/kthread.c +++ linux-2.6.21-rc7/kernel/kthread.c @@ -162,7 +162,8 @@ EXPORT_SYMBOL(kthread_create); */ void kthread_bind(struct task_struct *k, unsigned int cpu) { - if (k->state != TASK_UNINTERRUPTIBLE) { + if (k->state != TASK_UNINTERRUPTIBLE && + k->state != TASK_INTERRUPTIBLE) { WARN_ON(1); return; } -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!"