Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934873AbZARSZE (ORCPT ); Sun, 18 Jan 2009 13:25:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756281AbZARSYv (ORCPT ); Sun, 18 Jan 2009 13:24:51 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:40246 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757169AbZARSYv (ORCPT ); Sun, 18 Jan 2009 13:24:51 -0500 Date: Sun, 18 Jan 2009 19:24:42 +0100 From: Ingo Molnar To: Alexey Zaytsev Cc: Nick Piggin , Peter Zijlstra , Laurent Riffard , Kernel development list Subject: Re: next-20090107: WARNING: at kernel/sched.c:4435 sub_preempt_count Message-ID: <20090118182442.GC24570@elte.hu> References: <4966897E.5020302@free.fr> <20090111024945.GC7077@elte.hu> <20090114020040.GA19806@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0015] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1767 Lines: 51 * Alexey Zaytsev wrote: > Hi. > > On Wed, Jan 14, 2009 at 05:00, Nick Piggin wrote: > > On Sun, Jan 11, 2009 at 03:49:45AM +0100, Ingo Molnar wrote: > >> > >> * Alexey Zaytsev wrote: > >> > >> > One more instance of http://marc.info/?l=linux-kernel&m=123134586202636&w=2 > >> > Added Ingo Molnar to CC. > >> > >> added Nick on Cc:. Nick, it's about: > >> > >> > commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd > >> > Author: Nick Piggin > >> > Date: Tue Sep 30 20:50:27 2008 +1000 > >> > > >> > sched: improve preempt debugging > >> > >> causing a seemingly spurious warning. > > > > I don't know how it is spurious... Presumably the sequence _would_ have > > caused preempt count to go negative if the bkl were not held... > > > > __do_softirq does a __local_bh_disable on entry, and it seems like the > > _local_bh_enable on exit is what causes this warning. So something is > > unbalanced somehow. Or is it some weird thing we do in early boot that > > I am missing? > > > > Can you put in some printks around these functions in early boot to > > get an idea of what preempt_count is doing? > > Sorry for the delay. I was busy and forgot about this issue. > The warning does not show in -rc2 any more. Was it fixed, or > just shadowed by something? We reverted it in: 01e3eb8: Revert "sched: improve preempt debugging" We can apply a fixed version again if the failure mode is understood and fixed. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/