Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756764Ab0KJQBn (ORCPT ); Wed, 10 Nov 2010 11:01:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:15769 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756373Ab0KJQBm (ORCPT ); Wed, 10 Nov 2010 11:01:42 -0500 Date: Wed, 10 Nov 2010 16:55:30 +0100 From: Oleg Nesterov To: "Paul E. McKenney" Cc: Greg Thelen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jens Axboe Subject: Re: INFO: suspicious rcu_dereference_check() usage - kernel/pid.c:419 invoked rcu_dereference_check() without protection! Message-ID: <20101110155530.GA1905@redhat.com> References: <20101107182028.GZ15561@linux.vnet.ibm.com> <20101108151509.GA3702@redhat.com> <20101109202900.GV4032@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101109202900.GV4032@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 681 Lines: 21 On 11/09, Paul E. McKenney wrote: > > Thank you, Oleg! Greg, would you be willing to update your patch > to remove the comment? (Perhaps tasklist_lock as well...) Agreed, I think tasklock should be killed. But wait. Whatever we do, isn't this code racy? I do not see why, say, sys_ioprio_set(IOPRIO_WHO_PROCESS) can't install ->io_context after this task has already passed exit_io_context(). Jens, am I missed something? Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/