From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934668Ab1JaWfg (ORCPT ); Mon, 31 Oct 2011 18:35:36 -0400 Received: from mail-qy0-f174.google.com ([209.85.216.174]:64840 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934573Ab1JaWfc (ORCPT ); Mon, 31 Oct 2011 18:35:32 -0400 Date: Mon, 31 Oct 2011 15:35:26 -0700 From: Tejun Heo To: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: arnd@arndb.de, oleg@redhat.com, matthltc@us.ibm.com Subject: [PATCH 19/17] freezer: use lock_task_sighand() in fake_signal_wake_up() Message-ID: <20111031223526.GE18855@google.com> References: <1320087928-32307-1-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1320087928-32307-1-git-send-email-tj@kernel.org> 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 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 Acked-by: Oleg Nesterov Cc: "Rafael J. Wysocki" Cc: Paul Menage --- kernel/freezer.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/freezer.c b/kernel/freezer.c index 10f9840..a9c18c7 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -93,9 +93,10 @@ static void fake_signal_wake_up(struct task_struct *p) { unsigned long flags; - spin_lock_irqsave(&p->sighand->siglock, flags); - signal_wake_up(p, 1); - spin_unlock_irqrestore(&p->sighand->siglock, flags); + if (lock_task_sighand(p, &flags)) { + signal_wake_up(p, 1); + unlock_task_sighand(p, &flags); + } } /** -- 1.7.3.1