From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939362AbXGSPcm (ORCPT ); Thu, 19 Jul 2007 11:32:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765796AbXGSPcb (ORCPT ); Thu, 19 Jul 2007 11:32:31 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:34713 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756579AbXGSPc2 (ORCPT ); Thu, 19 Jul 2007 11:32:28 -0400 Date: Thu, 19 Jul 2007 17:32:18 +0200 From: Ingo Molnar To: Olaf Kirch Cc: Jarek Poplawski , Linus Torvalds , linux-kernel@vger.kernel.org, davem@davemloft.net, Auke Kok Subject: Re: [patch] revert: [NET]: Fix races in net_rx_action vs netpoll Message-ID: <20070719153217.GA25544@elte.hu> References: <20070716091236.GA10718@elte.hu> <200707191144.24434.olaf.kirch@oracle.com> <20070719100135.GA2986@elte.hu> <200707191237.56455.olaf.kirch@oracle.com> <20070719104756.GA13769@elte.hu> <20070719105816.GA15852@elte.hu> <20070719150728.GA17000@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070719150728.GA17000@elte.hu> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar wrote: > ugh. Something really weird happened with this e1000 problem. > > i crashed the laptop in a weird way and had to power-cycle it in an > unusual fashion. After that i wanted to try your latest BUG_ON() > theory but the network hang went away! > > For 3 hours i tried to reproduce the hang (i went back to the original > git tree and the .config under which i found it, i power cycled it > again, i unplugged the power cord to make it go off battery, unplugged > the ethernet, recreated a completely new tree, etc. etc.) but with no > success! Total Heisenbug - and the really annoying thing is that you > just had a good theory about what might be happening. I'm now at > kernel build iteration #75 in this tree ... ah! Just found the reason: the bug apparently depends on the precise kernel command-line contents. I accidentally dropped ignore_loglevel (found this while comparing with the older logs i sent to you), adding it back in produces hung networking too. So it appears that a netconsole printout while e1000 is initializing (or while some other networking component is initializing) might be the culprit? Ingo