From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752940Ab3KAMI2 (ORCPT ); Fri, 1 Nov 2013 08:08:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10475 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750799Ab3KAMI0 (ORCPT ); Fri, 1 Nov 2013 08:08:26 -0400 Message-ID: <527399A0.304@redhat.com> Date: Fri, 01 Nov 2013 08:08:00 -0400 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Thunderbird/3.1.10 MIME-Version: 1.0 To: Rik van Riel CC: Mel Gorman , peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -tip] fix race between stop_two_cpus and stop_cpus References: <20131031163144.0fd27457@annuminas.surriel.com> <20131101110825.GX2400@suse.de> <52739244.3060209@redhat.com> In-Reply-To: <52739244.3060209@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/01/2013 07:36 AM, Rik van Riel wrote: > On 11/01/2013 07:08 AM, Mel Gorman wrote: >> On Thu, Oct 31, 2013 at 04:31:44PM -0400, Rik van Riel wrote: >>> There is a race between stop_two_cpus, and the global stop_cpus. >>> >> >> What was the trigger for this? I want to see what was missing from my own >> testing. I'm going to go out on a limb and guess that CPU hotplug was also >> running in the background to specifically stress this sort of rare condition. >> Something like running a standard test with the monitors/watch-cpuoffline.sh >> from mmtests running in parallel. > > AFAIK the trigger was a test that continuously loads and > unloads kernel modules, while doing other stuff. > With this patch in place the module load/unload test ran for ~16 hours without failure. Without the patch the test usually fails in 5-10 minutes. Tested-by: Prarit Bhargava P.