From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752717AbXCEHu2 (ORCPT ); Mon, 5 Mar 2007 02:50:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752718AbXCEHu2 (ORCPT ); Mon, 5 Mar 2007 02:50:28 -0500 Received: from mail.queued.net ([207.210.101.209]:4033 "EHLO mail.queued.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752717AbXCEHu1 (ORCPT ); Mon, 5 Mar 2007 02:50:27 -0500 Message-ID: <45EBCBBE.6000001@debian.org> Date: Mon, 05 Mar 2007 02:50:22 -0500 From: Andres Salomon User-Agent: Thunderbird 1.5.0.9 (X11/20070102) MIME-Version: 1.0 To: Ingo Molnar CC: tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] highres: Do not run the TIMER_SOFTIRQ after switching to highres mode References: <45E8E2F8.1030102@debian.org> <1172912540.24738.108.camel@localhost.localdomain> <45EAAA21.4040803@debian.org> <1173013794.24738.130.camel@localhost.localdomain> <45EAC5B1.2060306@debian.org> <20070305072518.GB14993@elte.hu> In-Reply-To: <20070305072518.GB14993@elte.hu> X-Enigmail-Version: 0.94.2.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Andres Salomon wrote: > >> Thomas Gleixner wrote: >>>>> The question is, how the tick timer gets enqueued in the softirq queue. >>>>> Can you isolate the codepath, where this happens ? >>> The TIMER_SOFTIRQ runs the hrtimers during bootup until a usable >>> clocksource and clock event sources are registered. The switch to high >>> resolution mode happens inside of the TIMER_SOFTIRQ, but runs the >>> softirq afterwards. That way the tick emulation timer, which was set up >>> in the switch to highres might be executed in the softirq context, which >>> is a BUG. The rbtree has not to be touched by the softirq after the >>> highres switch. >>> >> And an additional request, just to make it explicit that we should not >> have any NO_SOFTIRQ callbacks in the tree; BUG out if we encounter >> such a thing. > > please change it to WARN_ON_ONCE()... > > 'bug out' might mean: 'dead box'/'no resume'/'no bootup'. > > Ingo Certainly; note that hrtimers.c has quite a few BUG calls which could render a box dead, though. Patch to follow..