From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764484AbZAULuh (ORCPT ); Wed, 21 Jan 2009 06:50:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757181AbZAULu2 (ORCPT ); Wed, 21 Jan 2009 06:50:28 -0500 Received: from casper.infradead.org ([85.118.1.10]:59546 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756180AbZAULu1 (ORCPT ); Wed, 21 Jan 2009 06:50:27 -0500 Subject: Re: lockdep and debug objects together are broken? From: Peter Zijlstra To: Ingo Molnar Cc: Nick Piggin , Vegard Nossum , Thomas Gleixner , Linux Kernel Mailing List In-Reply-To: <20090121114229.GA10606@elte.hu> References: <20090120085559.GB19505@wotan.suse.de> <19f34abd0901201311t2425056dia6182812f7270297@mail.gmail.com> <20090121071950.GM24891@wotan.suse.de> <20090121114229.GA10606@elte.hu> Content-Type: text/plain Date: Wed, 21 Jan 2009 12:50:02 +0100 Message-Id: <1232538602.4847.158.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2009-01-21 at 12:42 +0100, Ingo Molnar wrote: > So by the time you'd rearm, there's a lot of tasks with no proper locking > state built up. We might be able to re-arm via stop_machine_run perhaps. Won't work either, kstopmachine only preempts everybody. We'd require something stronger. What we need is a point where there's guaranteed no locks held, for regular tasks that would be a trip to userspace and back, but for kernel tasks that's a bit harder -- does the freezer stuff guarantee this? Supposing we have such a point for all tasks, what you then do is wipe all lock state and rig a trigger to start tracking lock state once you passed through the point.