From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756779AbZATI4T (ORCPT ); Tue, 20 Jan 2009 03:56:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754440AbZATI4D (ORCPT ); Tue, 20 Jan 2009 03:56:03 -0500 Received: from mx2.suse.de ([195.135.220.15]:43830 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754364AbZATI4B (ORCPT ); Tue, 20 Jan 2009 03:56:01 -0500 Date: Tue, 20 Jan 2009 09:55:59 +0100 From: Nick Piggin To: Ingo Molnar , Thomas Gleixner , Vegard Nossum , Peter Zijlstra , Linux Kernel Mailing List Subject: lockdep and debug objects together are broken? Message-ID: <20090120085559.GB19505@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've had a problem frustrating my testing because lockdep was silently turning itself off... I patched out the code to disable lockdep after the first error, and it started showing up weird errors. kernel/fork.c:990 seemed to be the first to trigger (hard irqs disabled) from a call_usermodehelper call. Later, migration thread was reported to try to unlock rq->lock although it was holding no locks. Then init was reported to return to userspace without releasing an objectdebug hash lock. All that went away and everything seemed to work properly with debug objects configured out. I didn't get too far in trying to debug the problem. But it should be easy enough to reproduce (if not, I can post traces or test patches). Thanks, Nick