From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934760AbZGQQ51 (ORCPT ); Fri, 17 Jul 2009 12:57:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934748AbZGQQ50 (ORCPT ); Fri, 17 Jul 2009 12:57:26 -0400 Received: from cam-admin0.cambridge.arm.com ([193.131.176.58]:53661 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934734AbZGQQ50 (ORCPT ); Fri, 17 Jul 2009 12:57:26 -0400 Subject: Re: [RFC PATCH] kmemleak: Scan all thread stacks From: Catalin Marinas To: Ingo Molnar Cc: Peter Zijlstra , "Paul E. McKenney" , linux-kernel@vger.kernel.org In-Reply-To: <20090717164346.GC5131@elte.hu> References: <20090717093359.8288.45464.stgit@pc1117.cambridge.arm.com> <20090717164346.GC5131@elte.hu> Content-Type: text/plain Organization: ARM Ltd Date: Fri, 17 Jul 2009 17:57:06 +0100 Message-Id: <1247849826.6313.64.camel@pc1117.cambridge.arm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 17 Jul 2009 16:57:07.0475 (UTC) FILETIME=[9E3DAE30:01CA06FF] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2009-07-17 at 18:43 +0200, Ingo Molnar wrote: > * Catalin Marinas wrote: > > 2. Is it safe to use rcu_read_lock() and task_lock() when scanning the > > corresponding kernel stack (thread_info structure)? The loop doesn't > > do any modification to the task list. The reason for this is to > > allow kernel preemption when scanning the stacks. > > you cannot generally preempt while holding the RCU read-lock. This may work with rcupreempt enabled. But, with classic RCU is it safe to call schedule (or cond_resched) while holding the RCU read-lock? Thanks. -- Catalin