From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754956Ab1AUTn1 (ORCPT ); Fri, 21 Jan 2011 14:43:27 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:43646 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754892Ab1AUTn0 (ORCPT ); Fri, 21 Jan 2011 14:43:26 -0500 Date: Fri, 21 Jan 2011 20:43:17 +0100 From: Ingo Molnar To: Linus Torvalds Cc: Alexander Gordeev , Andrew Morton , Linux Kernel Mailing List , Thomas Gleixner Subject: Re: PPS parport boot lockup: INFO: HARDIRQ-READ-safe -> HARDIRQ-READ-unsafe lock order detected Message-ID: <20110121194317.GA8908@elte.hu> References: <20110119083916.GA2166@elte.hu> <20110121174438.7521539f@tornado.gnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 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 * Linus Torvalds wrote: > HOWEVER, even then I think you should see the lockdep message as a > problem. The automated toolchain is great because it shows problems > that it thinks might happen - not when they happen, but based on a > simpler theoretical model. Ignoring the error because there is some > rule in place that is hard to explain to the automated toolchain is > the wrong thing to do, because it makes the lockdep automation less > reliable. Yeah. Also, inevitably the false positives have a higher likelyhood of making it into a released kernel, often because the bugs where there was a real lockup as well got noticed via other means. It's similar with compiler warnings as well: the questionable ones where GCC is wrong or at least confused accumulate. Also note that here there's a real lockup here as well, shortly after the lockdep message - the boot never continues, the box keep spewing the PPS debug messages: [ 76.240020] pps pps0: PPS event at 4294911356 [ 76.244380] pps pps0: PPS event at 1295471377.240018362 [ 76.249608] pps pps0: capture assert seq #2 [ 77.252019] pps pps0: PPS event at 4294911609 [ 77.256379] pps pps0: PPS event at 1295471378.252017372 [ 77.261604] pps pps0: capture assert seq #3 [ 78.264021] pps pps0: PPS event at 4294911862 [ 78.268387] pps pps0: PPS event at 1295471379.264018619 [ 78.273621] pps pps0: capture assert seq #4 [ 79.276018] pps pps0: PPS event at 4294912115 [ 79.280384] pps pps0: PPS event at 1295471380.276016791 [ 79.285619] pps pps0: capture assert seq #5 But nothing happens, the boot never continues. Thanks, Ingo