From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758701AbYDGW3b (ORCPT ); Mon, 7 Apr 2008 18:29:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758323AbYDGW3V (ORCPT ); Mon, 7 Apr 2008 18:29:21 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:58167 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758149AbYDGW3T (ORCPT ); Mon, 7 Apr 2008 18:29:19 -0400 From: "Rafael J. Wysocki" To: Andi Kleen Subject: Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8 Date: Tue, 8 Apr 2008 00:29:30 +0200 User-Agent: KMail/1.9.6 (enterprise 20070904.708012) Cc: Jiri Kosina , Zdenek Kabelac , Kernel development list , Ingo Molnar , Thomas Gleixner References: <20080407222352.GG16647@one.firstfloor.org> In-Reply-To: <20080407222352.GG16647@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200804080029.31102.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, 8 of April 2008, Andi Kleen wrote: > On Tue, Apr 08, 2008 at 12:11:17AM +0200, Jiri Kosina wrote: > > On Tue, 8 Apr 2008, Andi Kleen wrote: > > > > > > I know. However preempt_count is a little bit inconsistent in such cases > > > > though. > > > And? interrupts off beats preempt count anyways. Why did you write the > > > patch? Was there a (incorrect) warning triggered? > > > > Reported at http://lkml.org/lkml/2008/4/7/130 > > > > BTW is also mce_init() (called from mce_resume()) guaranteed to run with > > IRQs off? > > [cc rafael] > > The mce resume is a sysdev. > > sysdevs were always supposed to run completely with interrupts off. If they > don't anymore that's some kind of higher level resume code bug which you need > to fix there, not hack around in the low level code. They are executed with interrupts disabled, on one CPU. > If it does that it likely broke more code too. > > Obviously turning on preemption anywhere around the machine check is > fatal because it touches CPU state and if you reschedule you could > switch to another CPU and change or access the wrong CPU's state. FWIW, at the point when sysdevs are resumed we are single-threaded. Thanks, Rafael