From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752174AbaAQJJN (ORCPT ); Fri, 17 Jan 2014 04:09:13 -0500 Received: from merlin.infradead.org ([205.233.59.134]:57531 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751415AbaAQJJH (ORCPT ); Fri, 17 Jan 2014 04:09:07 -0500 Date: Fri, 17 Jan 2014 10:08:56 +0100 From: Peter Zijlstra To: Andrew Morton Cc: Steven Rostedt , LKML , linux-rt-users , Ingo Molnar , Thomas Gleixner , Clark Williams Subject: Re: [RFC][PATCH] preempt: Debug for possible missed preemption checks Message-ID: <20140117090856.GE11314@laptop.programming.kicks-ass.net> References: <20140116235751.084728c8@gandalf.local.home> <20140116211214.581197e5.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140116211214.581197e5.akpm@linux-foundation.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 16, 2014 at 09:12:14PM -0800, Andrew Morton wrote: > On Thu, 16 Jan 2014 23:57:51 -0500 Steven Rostedt wrote: > > > When PROVE_LOCKING and PREEMPT is configured, the preempt state > > tracking is active. Testing this out, I added a module that did the > > following: > > So I assume your kernel at least has no instances of this bug, so we > don't need the patch ;) It *is* a fairly daft thing to do. Yeah, its exceedingly daft, but I do run into it every so often. Say once a year or so. Also, its usually not really a problem on 'normal' kernels, but it absolutely blows on -rt.