From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754590AbaG3Ozd (ORCPT ); Wed, 30 Jul 2014 10:55:33 -0400 Received: from qmta08.emeryville.ca.mail.comcast.net ([76.96.30.80]:55002 "EHLO qmta08.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754213AbaG3Ozb (ORCPT ); Wed, 30 Jul 2014 10:55:31 -0400 Date: Wed, 30 Jul 2014 09:55:29 -0500 (CDT) From: Christoph Lameter To: Fengguang Wu cc: Tejun Heo , Jet Chen , Su Tao , Yuanhan Liu , LKP , linux-kernel@vger.kernel.org Subject: Re: [scheduler] BUG: unable to handle kernel paging request at 000000000000ce50 In-Reply-To: <20140730135616.GK16537@localhost> Message-ID: References: <20140730135616.GK16537@localhost> Content-Type: TEXT/PLAIN; CHARSET=US-ASCII Content-ID: Content-Disposition: INLINE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 30 Jul 2014, Fengguang Wu wrote: > FYI, this commit seems to convert some kernel boot hang bug into > different BUG messages. Hmmm. Still a bit confused as to why these messages occur.. Does this patch do any good? Subject: vmstat ondemand: Fix online/offline races Do not allow onlining/offlining while the shepherd task is checking for vmstat threads. On offlining a processor do the right thing cancelling the vmstat worker thread if it exista and also exclude it from the shepherd process checks. Signed-off-by: Christoph Lameter Index: linux/mm/vmstat.c =================================================================== --- linux.orig/mm/vmstat.c 2014-07-30 09:35:54.602662306 -0500 +++ linux/mm/vmstat.c 2014-07-30 09:43:07.109037043 -0500 @@ -1317,6 +1317,7 @@ static void vmstat_shepherd(struct work_ { int cpu; + get_online_cpus(); /* Check processors whose vmstat worker threads have been disabled */ for_each_cpu(cpu, cpu_stat_off) if (need_update(cpu) && @@ -1325,6 +1326,7 @@ static void vmstat_shepherd(struct work_ schedule_delayed_work_on(cpu, &per_cpu(vmstat_work, cpu), __round_jiffies_relative(sysctl_stat_interval, cpu)); + put_online_cpus(); schedule_delayed_work(&shepherd, round_jiffies_relative(sysctl_stat_interval)); @@ -1380,8 +1382,8 @@ static int vmstat_cpuup_callback(struct break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: - if (!cpumask_test_and_set_cpu(cpu, cpu_stat_off)) - cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); + cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); + cpumask_clear_cpu(cpu, cpu_stat_off); break; case CPU_DOWN_FAILED: case CPU_DOWN_FAILED_FROZEN: