From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754475Ab1HaKWu (ORCPT ); Wed, 31 Aug 2011 06:22:50 -0400 Received: from mail-ww0-f42.google.com ([74.125.82.42]:43031 "EHLO mail-ww0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754090Ab1HaKWp (ORCPT ); Wed, 31 Aug 2011 06:22:45 -0400 Date: Wed, 31 Aug 2011 12:22:37 +0200 From: Tejun Heo To: "Rafael J. Wysocki" , Oleg Nesterov , Paul Menage Cc: containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH pm-freezer 4/4] freezer: use lock_task_sighand() in fake_signal_wake_up() Message-ID: <20110831102237.GD2828@mtj.dyndns.org> References: <20110831102100.GA2828@mtj.dyndns.org> <20110831102143.GB2828@mtj.dyndns.org> <20110831102210.GC2828@mtj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110831102210.GC2828@mtj.dyndns.org> 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 cgroup_freezer calls freeze_task() without holding tasklist_lock and, if the task is exiting, its ->sighand may be gone by the time fake_signal_wake_up() is called. Use lock_task_sighand() instead of accessing ->sighand directly. Signed-off-by: Tejun Heo Reported-by: Oleg Nesterov Cc: "Rafael J. Wysocki" Cc: Paul Menage --- kernel/freezer.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) Index: work/kernel/freezer.c =================================================================== --- work.orig/kernel/freezer.c +++ work/kernel/freezer.c @@ -95,9 +95,10 @@ static void fake_signal_wake_up(struct t { unsigned long flags; - spin_lock_irqsave(&p->sighand->siglock, flags); - signal_wake_up(p, 0); - spin_unlock_irqrestore(&p->sighand->siglock, flags); + if (lock_task_sighand(p, &flags)) { + signal_wake_up(p, 0); + unlock_task_sighand(p, &flags); + } } /**