Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751583AbdCCK6t (ORCPT ); Fri, 3 Mar 2017 05:58:49 -0500 Received: from smtp2.it.da.ut.ee ([193.40.5.67]:46316 "EHLO smtp2.it.da.ut.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751137AbdCCK6p (ORCPT ); Fri, 3 Mar 2017 05:58:45 -0500 Date: Fri, 3 Mar 2017 12:58:06 +0200 (EET) From: Meelis Roos To: Thomas Gleixner cc: Linux Kernel list , x86@kernel.org, Peter Zijlstra Subject: Re: PPro arch_cpu_idle: NMI watchdog: Watchdog detected hard LOCKUP on cpu 1 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (LRH 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1740 Lines: 40 > On Thu, 2 Mar 2017, Thomas Gleixner wrote: > > On Wed, 1 Mar 2017, Thomas Gleixner wrote: > > > On Thu, 2 Mar 2017, Meelis Roos wrote: > > > > > > > > > This is on my trusty IBM PC365, dual Pentium Pro. 4.10 worked fine, > > > > > > 4.10.0-09686-g9e314890292c and 4.10.0-10770-g2d6be4abf514 exhibit a > > > > > > problem. Ocassionally NMI watchdog kicks in and discovers one of the > > > > > > CPUs in LOCKUP. The system keeps running fine. The first lockup was > > > > > > different, all the others were from arch_cpu_idle. Sometime ecey couple > > > > > > of seconds (after some activity), sometimes nothing for a long time > > > > > > (idle, no SSH logins). > > > > > > > > > > The only watchdog related patch which hit after 4.10 is: > > > > > > > > > > 8dcde9def5a1 kernel/watchdog.c: do not hardcode CPU 0 as the initial thread > > > > > > > > > > Can you try to revert that for a start? I'm not seeing why it should be the > > > > > culprit from a quick glance, but ... > > > > > > > > Reverting this patch does not help. > > > > > > I did not expect that, but excluding it was a valid shot in the > > > dark. Thanmks for trying. > > > > > > To be honest, I have no idea what causes that at the moment, but I will > > > come back to you tomorrow after thinking it through (with brain awake) how > > > to debug this. > > > > Went through the related changes which came in during the merge window. One > > which affects the per cpu timers is: 914122c389d0 > > > > Can you try to revert that one please? > > Running out of obvious culprits. Any chance that you can do a bisect or > this too painful on that box? I started bisect yesterday on the P4 that has one similar occurrance. -- Meelis Roos (mroos@linux.ee)