Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756578Ab2BGGuL (ORCPT ); Tue, 7 Feb 2012 01:50:11 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:61195 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754575Ab2BGGuH (ORCPT ); Tue, 7 Feb 2012 01:50:07 -0500 Date: Tue, 7 Feb 2012 10:50:04 +0400 From: Anton Vorontsov To: Oleg Nesterov Cc: Greg KH , KOSAKI Motohiro , "Eric W. Biederman" , "Paul E. McKenney" , Paul Mundt , Russell King , Mike Frysinger , Benjamin Herrenschmidt , Richard Weinberger , linux-kernel@vger.kernel.org Subject: [PATCH 3/8] arm: Fix possible race on task->mm Message-ID: <20120207065004.GC1496@oksana.dev.rtsoft.ru> References: <20120207064809.GA29061@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20120207064809.GA29061@oksana.dev.rtsoft.ru> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1042 Lines: 34 Checking for task->mm is dangerous as ->mm might disappear (exit_mm() assigns NULL under task_lock(), so tasklist lock is not enough). We can't use get_task_mm()/mmput() pair as mmput() might sleep, so let's take the task lock while we care about its mm. Signed-off-by: Anton Vorontsov --- arch/arm/kernel/smp.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 57db122..85db3f2 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -168,8 +168,10 @@ int __cpu_disable(void) read_lock(&tasklist_lock); for_each_process(p) { + task_lock(p); if (p->mm) cpumask_clear_cpu(cpu, mm_cpumask(p->mm)); + task_unlock(p); } read_unlock(&tasklist_lock); -- 1.7.7.6 -- 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/