From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750904AbcBEClH (ORCPT ); Thu, 4 Feb 2016 21:41:07 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:35774 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750723AbcBECkt (ORCPT ); Thu, 4 Feb 2016 21:40:49 -0500 Message-ID: <1454640046.3545.8.camel@gmail.com> Subject: Re: Crashes with 874bbfe600a6 in 3.18.25 From: Mike Galbraith To: Daniel Bilik , Jan Kara Cc: Thomas Gleixner , LKML , stable@vger.kernel.org Date: Fri, 05 Feb 2016 03:40:46 +0100 In-Reply-To: <20160204173931.4735a8de14fc0bde6c114321@neosystem.cz> References: <20160126093400.GV24938@quack.suse.cz> <20160126111438.GA731@pathway.suse.cz> <56B1C9E4.4020400@suse.cz> <20160203122855.GB6762@dhcp22.suse.cz> <20160203162441.GE14091@mtj.duckdns.org> <1454518913.6148.15.camel@gmail.com> <20160203170652.GI14091@mtj.duckdns.org> <1454580263.3407.114.camel@gmail.com> <20160204112044.GE4956@quack.suse.cz> <20160204173931.4735a8de14fc0bde6c114321@neosystem.cz> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2016-02-04 at 17:39 +0100, Daniel Bilik wrote: > On Thu, 4 Feb 2016 12:20:44 +0100 > Jan Kara wrote: > > > Thanks for backport Thomas and to Mike for persistence :). I've asked my > > friend seeing crashes with 3.18.25 to try whether this patch fixes the > > issues. It may take some time so stay tuned... > > Patch tested and it really fixes the crash we were experiencing on 3.18.25 > with commit 874bbfe+. But it seem to introduce (rather scary) regression. > Tested host shows abnormal cpu usage in both kernel and userland under the > same load and traffic pattern. One picture is worth a thousand words, so > I've taken snapshots of our graphs, see here: > http://neosystem.cz/test/linux-3.18.25/ > The host was running 3.18.25 with commit 874bbfe+ (1e7af29+ on > 3.18-stable) reverted. With this commit included, it crashed within > minutes. Around 13:30 we booted 3.18.25 with commit 874bbfe+ included and > with the patch from Thomas. And around 15:40 we've booted the host with > previous kernel, just to ensure this abnormal behaviour was really caused > by the test kernel. > Also interesting, in addition to high cpu usage, there is abnormally high > number of zombie processes reported by the system. IMHO you should restore the CC list and re-post. (If I were the maintainer of either the workqueue code or 3.18-stable, I'd be highly interested in this finding). -Mike