From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030844AbXDVUBi (ORCPT ); Sun, 22 Apr 2007 16:01:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030869AbXDVUBW (ORCPT ); Sun, 22 Apr 2007 16:01:22 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:57643 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030844AbXDVUBT (ORCPT ); Sun, 22 Apr 2007 16:01:19 -0400 From: "Rafael J. Wysocki" To: Andrew Morton Subject: [RFC][PATCH -mm 3/3] freezer: Fix problem with kthread_stop Date: Sun, 22 Apr 2007 21:40:59 +0200 User-Agent: KMail/1.9.5 Cc: Ingo Molnar , ego@in.ibm.com, Oleg Nesterov , linux-kernel@vger.kernel.org, vatsa@in.ibm.com, paulmck@us.ibm.com, pavel@ucw.cz References: <20070419120131.GB13435@in.ibm.com> <20070420183118.GA695@elte.hu> <200704222128.49419.rjw@sisk.pl> In-Reply-To: <200704222128.49419.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200704222141.00680.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Fix the problem with kthread_stop() that causes the freezer to fail if a freezable thread is attempting to stop a frozen one and that may cause the freezer to fail if the thread being stopped is freezable and try_to_freeze_tasks() is running concurrently with kthread_stop(). Signed-off-by: Rafael J. Wysocki --- kernel/kthread.c | 9 +++++++++ 1 file changed, 9 insertions(+) Index: linux-2.6.21-rc6-mm1/kernel/kthread.c =================================================================== --- linux-2.6.21-rc6-mm1.orig/kernel/kthread.c 2007-04-09 15:23:48.000000000 +0200 +++ linux-2.6.21-rc6-mm1/kernel/kthread.c 2007-04-22 19:05:29.000000000 +0200 @@ -13,6 +13,7 @@ #include #include #include +#include #include /* @@ -232,6 +233,14 @@ int kthread_stop(struct task_struct *k) /* Now set kthread_should_stop() to true, and wake it up. */ kthread_stop_info.k = k; + if (!freezer_should_exempt(current)) { + /* We are freezable, so we must make sure that the thread being + * stopped is not frozen and will not be frozen until it dies + */ + freezer_exempt(k); + if (frozen(k)) + clear_frozen_flag(k); + } wake_up_process(k); put_task_struct(k);