Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756211AbcCOO3E (ORCPT ); Tue, 15 Mar 2016 10:29:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51068 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754106AbcCOO3B (ORCPT ); Tue, 15 Mar 2016 10:29:01 -0400 Date: Tue, 15 Mar 2016 10:28:58 -0400 From: Don Zickus To: Josh Hunt Cc: akpm@linux-foundation.org, uobergfe@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] watchdog: don't run proc_watchdog_update if new value is same as old Message-ID: <20160315142858.GZ194535@redhat.com> References: <1457826627-21727-1-git-send-email-johunt@akamai.com> <20160314143426.GK194535@redhat.com> <56E6CE86.5070606@akamai.com> <20160314162955.GQ194535@redhat.com> <56E78957.6020707@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56E78957.6020707@akamai.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1935 Lines: 55 On Mon, Mar 14, 2016 at 11:02:31PM -0500, Josh Hunt wrote: > On 03/14/2016 11:29 AM, Don Zickus wrote: > > > >Hi Josh, > > > >I believe Uli thought the below patch might fix it. > > > >Cheers, > >Don > > Don > > It looks like I was incorrect when I said 4.5 was getting the soft lockup. I > originally found this problem on 4.1.19 and saw both the problem my patch > solves and the soft lockups there. I thought when I checked 4.5 that I saw > both issues there as well, but going back and checking now that is not the > case. I only see the issue my patch resolves on 4.5. > > With that info my changelog is incorrect now as it states I saw a soft > lockup on the head. I will submit a v2 of my patch with the updated > changelog. I'll also cc stable this time as I'd like to see this fix end up > there as well. > > As for the soft lockups showing up on 4.1, I tried Uli's patch and it did > not help. After that I did a git bisect to figure out when the soft lockup > was fixed and it appears to be resolved after one of the commits in this > series: > > commit 81a4beef91ba4a9e8ad6054ca9933dff7e25ff28 > Author: Ulrich Obergfell > Date: Fri Sep 4 15:45:15 2015 -0700 > > watchdog: introduce watchdog_park_threads() and > watchdog_unpark_threads() > > I didn't identify the exact commit. > > It would be nice to resolve the soft lockup for the stable folks since 4.1 > and 4.4 are longterm stable releases and would see this problem. > > I did not have time to debug it any more outside of this bisection today. If > you have something you'd like me to try which may work for the stable > kernels I'm happy to test it. > > For the record I'm able to reproduce the soft lockup on 4.1 doing: > > while :; do echo 1 > /proc/sys/kernel/nmi_watchdog; sleep .1; done & sleep > 30 && kill %1 && sleep 5 Thanks for the feedback Josh! Good to know the softlockup was fixed already. :-) Cheers, Don