From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752503Ab0KGSrP (ORCPT ); Sun, 7 Nov 2010 13:47:15 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:48767 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811Ab0KGSrO (ORCPT ); Sun, 7 Nov 2010 13:47:14 -0500 Date: Sun, 7 Nov 2010 10:47:11 -0800 From: "Paul E. McKenney" To: Miles Lane Cc: LKML Subject: Re: 2.6.36-git11 -- kernel/pid.c:419 invoked rcu_dereference_check() without protection! Message-ID: <20101107184711.GB15561@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 29, 2010 at 01:22:28AM -0400, Miles Lane wrote: > [ INFO: suspicious rcu_dereference_check() usage. ] > --------------------------------------------------- > kernel/pid.c:419 invoked rcu_dereference_check() without protection! > > other info that might help us debug this: > > > rcu_scheduler_active = 1, debug_locks = 1 > 1 lock held by ureadahead/943: > #0: (tasklist_lock){.+.+..}, at: [] > sys_ioprio_set+0x8e/0x2aa > > stack backtrace: > Pid: 943, comm: ureadahead Not tainted 2.6.36-git11 #8 > Call Trace: > [] lockdep_rcu_dereference+0x9d/0xa5 > [] find_task_by_pid_ns+0x3f/0x58 > [] find_task_by_vpid+0x1d/0x1f > [] sys_ioprio_set+0xbd/0x2aa > [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [] system_call_fastpath+0x16/0x1b Could you please try the patch from Sergey Senozhatsky, currently in -mm, that may be found at http://lkml.org/lkml/2010/10/29/168? Thanx, Paul