From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752918Ab2ITRKw (ORCPT ); Thu, 20 Sep 2012 13:10:52 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:39674 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752593Ab2ITRKu (ORCPT ); Thu, 20 Sep 2012 13:10:50 -0400 Date: Thu, 20 Sep 2012 10:10:45 -0700 From: Tejun Heo To: Borislav Petkov , Michael Wang , Peter Zijlstra , Akinobu Mita , lkml Subject: Re: kernel BUG at kernel/sched/core.c:1465! Message-ID: <20120920171045.GC28934@google.com> References: <20120919091230.GA25576@liondog.tnic> <505AB9F7.6030605@linux.vnet.ibm.com> <20120920125801.GA15045@x1.osrc.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120920125801.GA15045@x1.osrc.amd.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, guys. On Thu, Sep 20, 2012 at 02:58:01PM +0200, Borislav Petkov wrote: > commit c5c473e29c641380aef4a9d1f9c39de49219980f > Merge: 925a6f0bf8bd 6889125b8b4e > Author: Linus Torvalds > Date: Wed Sep 19 11:00:07 2012 -0700 > > Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq > > Pull workqueue / powernow-k8 fix from Tejun Heo: > "This is the fix for the bug where cpufreq/powernow-k8 was tripping > BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a > different CPU. > > and this is exactly the same BUG_ON I'm hitting. and powernowk8_target > is in the stack trace so it has to be the same issue. Yeah, it's powernow-k8 migrating kworker to a different CPU. It's really curious that there are multiple reports of this in this cycle. Nothing on workqueue side has changed and powernow-k8 has been broken for very long time. The only way this can get triggered is by contending on fidvid_mutex in powernow-k8. I suppose something changed in such way that this happens with some regularity. Have no specific idea what. Anyways, mainline should be okay now. Thanks. -- tejun