From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Riffard Subject: Re: [BUG] netconsole broken by scheduler updates Date: Thu, 26 May 2011 12:35:19 +0200 (CEST) Message-ID: References: <4DDE1B7D.7080707@free.fr> <1306403308.1200.44.camel@twins> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Laurent Riffard , netdev@vger.kernel.org To: Peter Zijlstra Return-path: Received: from smtp2-g21.free.fr ([212.27.42.2]:42473 "EHLO smtp2-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753319Ab1EZKf2 (ORCPT ); Thu, 26 May 2011 06:35:28 -0400 In-Reply-To: <1306403308.1200.44.camel@twins> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 26 May 2011, Peter Zijlstra wrote: > On Thu, 2011-05-26 at 11:21 +0200, Laurent Riffard wrote: >> Hi, >> >> Recently, netconsole was broken by some scheduler updates. Kernel hangs >> on boot near the network card initialization. I noticed that it does >> hang just where a "inconsistent lock state" message normally appears. >> >> I did a bisection : e4a52bcb9a18142d79e231b6733cabdbf2e67c1f is the >> first bad commit. >> commit e4a52bcb9a18142d79e231b6733cabdbf2e67c1f >> Author: Peter Zijlstra >> Date: Tue Apr 5 17:23:54 2011 +0200 >> >> sched: Remove rq->lock from the first half of ttwu() >> >> >> Before this commit, kernel was booting succesfully despite the >> "inconsistent lock state" message. After this commit, the kernel does >> hang on boot, I have to push the reset button. > > Do you have CONFIG_HARDLOCKUP_DETECTOR=y, and do you get an NMI splat > after some 10 seconds? It would be interesting to see where its stuck. CONFIG_HARDLOCKUP_DETECTOR is not set for now. I'll give it a try. > Also, are you very _very_ sure that lockdep message is a false positive? I can't answer this question. I just know that before commit e4a52bcb9, the kernel was able to boot with netconsole despite this message. Maybe some netconsole developper knows. ~~ laurent