From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert =?ISO-8859-1?Q?Sch=F6ne?= Subject: Re: PROBLEM: Kernel OOPS and possible system freeze after concurrent writing to cpufreq/scaling_governor (Resend) Date: Fri, 25 Jul 2014 10:42:49 +0200 Message-ID: <1406277769.2399.4.camel@x200t> References: <1405522398.2348.42.camel@x200t> <1406185912.2406.3.camel@x200t> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout2.zih.tu-dresden.de ([141.30.67.73]:51419 "EHLO mailout2.zih.tu-dresden.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759603AbaGYIm7 (ORCPT ); Fri, 25 Jul 2014 04:42:59 -0400 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: "Srivatsa S. Bhat" , "Rafael J. Wysocki" , "linux-pm@vger.kernel.org" The bug is still there. Here's my bash history, so that you can be sure= I checked it correctly: git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.= git linux-git cd linux-git/ git show 56d07db=20 git branch --contains 19c7630 git branch --contains 56d07db git revert -n 56d07db make oldconfig make clean make -j9 deb-pkg cd .. sudo dpkg -i linux-libc-dev_3.16.0-rc6+-2_amd64.deb sudo dpkg -i linux-image-3.16.0-rc6+_3.16.0-rc6+-2_amd64.deb sudo dpkg -i linux-headers-3.16.0-rc6+_3.16.0-rc6+-2_amd64.deb sudo dpkg -i linux-firmware-image-3.16.0-rc6+_3.16.0-rc6+-2_amd64.deb sudo update-grub2 sudo reboot Again, I didn't get a backtrace for the error, but only this: =2E.. ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^= @^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@= ^@^@ =2E.. Robert Am Donnerstag, den 24.07.2014, 15:12 +0530 schrieb Viresh Kumar: > On 24 July 2014 12:41, Robert Sch=C3=B6ne wrote: > > (Resend, because there hasn't been a reply within the last week) >=20 > How did I miss it? Yes its in my inbox. Sorry buddy.. >=20 > > crash_governor.sh: > > #!/bin/sh > > # this is called concurrently via runme.sh > > for I in `seq 1000` > > do > > echo ondemand | sudo tee /sys/devices/system/cpu/cpu*/cpufr= eq/scaling_governor > > echo userspace | sudo tee /sys/devices/system/cpu/cpu*/cpuf= req/scaling_governor > > done > > > > runme.sh: > > #!/bin/sh > > # run 8 concurrent instances > > for I in `seq 8` > > do > > ./crash_governor.sh & > > done > > > > Just run runme.sh and crash your system :) >=20 > Oh, yes. Quite easily I could see that happening :) >=20 > I have pushed a fix earlier for similar issues: > 19c7630 cpufreq: serialize calls to __cpufreq_governor() >=20 > but was later reverted by Srivatsa: > 56d07db cpufreq: Remove temporary fix for race between CPU hotplug an= d > sysfs-writes >=20 > because we didn't thought about this usecase. >=20 > I propose we get that back. I have tested a revert of 56d07db on > my setup and didn't see any crash.. >=20 > Please see if that works for you as well.. >=20 > -- > viresh --=20 Dipl.-Inf. Robert Schoene Computer Scientist - R&D Energy Efficient Computing Technische Universitaet Dresden Center for Information Services and High Performance Computing Distributed and Data Intensive Computing 01062 Dresden Tel.: +49 (351) 463-42483 =46ax : +49 (351) 463-37773 E-Mail: Robert.Schoene@tu-dresden.de