Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758436AbYLPWX2 (ORCPT ); Tue, 16 Dec 2008 17:23:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753365AbYLPWXS (ORCPT ); Tue, 16 Dec 2008 17:23:18 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:57078 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752937AbYLPWXR (ORCPT ); Tue, 16 Dec 2008 17:23:17 -0500 Date: Tue, 16 Dec 2008 23:23:05 +0100 From: Ingo Molnar To: Alexey Zaytsev Cc: Stephen Rothwell , linux-next@vger.kernel.org, LKML , Nick Piggin Subject: Re: linux-next: Tree for December 11 Message-ID: <20081216222305.GJ14787@elte.hu> References: <20081211200459.14d18d7a.sfr@canb.auug.org.au> <20081216210834.GM14787@elte.hu> 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: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Alexey Zaytsev wrote: > On Wed, Dec 17, 2008 at 00:08, Ingo Molnar wrote: > > >> > >> The warning can also be reproduced in qemu, so it was easy to bisect. > >> > >> commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd > >> Author: Nick Piggin > >> Date: Tue Sep 30 20:50:27 2008 +1000 > >> > >> sched: improve preempt debugging > >> > >> This patch helped me out with a problem I recently had.... > >> > >> Basically, when the kernel lock is held, then preempt_count > >> underflow does not > >> get detected until it is released which may be a long time (and arbitrarily, > >> eg at different points it may be rescheduled). If the bkl is released at > >> schedule, the resulting output is actually fairly cryptic... > >> > >> With any other lock that elevates preempt_count, it is illegal to schedule > >> under it (which would get found pretty quickly). bkl allows scheduling with > >> preempt_count elevated, which makes underflows hard to debug. > >> > >> Signed-off-by: Ingo Molnar > >> > >> I understand that not this particular commit is buggy, but at least > >> I've got someone to add to the CC. ;) > >> > >> Also the author's e-mail looks suspicious. > > > > Suspicious in what way? > > Does not appear in signed-off-by. yes, because i applied and tested it through before Nick was comfortable with signing off on it. 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/