From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754653AbYH0GmY (ORCPT ); Wed, 27 Aug 2008 02:42:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754113AbYH0GmF (ORCPT ); Wed, 27 Aug 2008 02:42:05 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:44723 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754011AbYH0GmE (ORCPT ); Wed, 27 Aug 2008 02:42:04 -0400 Date: Wed, 27 Aug 2008 08:41:39 +0200 From: Ingo Molnar To: Zhu Yi Cc: peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] lockdep: fix invalid list_del_rcu in zap_class Message-ID: <20080827064139.GD6255@elte.hu> References: <20080827063300.GA18265@mail.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080827063300.GA18265@mail.intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Zhu Yi wrote: > BUG: unable to handle kernel NULL pointer dereference at > 0000000000000008 > IP: [] zap_class+0x24/0x82 > The root cause for this oops is in add_lock_to_list() when > save_trace() fails due to MAX_STACK_TRACE_ENTRIES is reached, > entry->class is assigned but entry is never added into any lock list. > This makes the list_del_rcu() in zap_class() oops later when the > module is unloaded. This patch fixes the problem by assigning > entry->class after save_trace() returns success. good spotting! Applied to tip/core/urgent, thanks. Ingo