From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754691Ab1LGQ5j (ORCPT ); Wed, 7 Dec 2011 11:57:39 -0500 Received: from cantor2.suse.de ([195.135.220.15]:33227 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756973Ab1LGQSX (ORCPT ); Wed, 7 Dec 2011 11:18:23 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Dec 7 08:08:24 2011 Message-Id: <20111207160824.801299363@clark.kroah.org> User-Agent: quilt/0.50-23.1 Date: Wed, 07 Dec 2011 08:06:46 -0800 From: Greg KH To: , Cc: , , , Michal Hocko , Li Zefan , Tomasz Buchert , Paul Menage , Tejun Heo Subject: [26/80] cgroup_freezer: fix freezing groups with stopped tasks In-Reply-To: <20111207161256.GA7736@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michal Hocko commit 884a45d964dd395eda945842afff5e16bcaedf56 upstream. 2d3cbf8b (cgroup_freezer: update_freezer_state() does incorrect state transitions) removed is_task_frozen_enough and replaced it with a simple frozen call. This, however, breaks freezing for a group with stopped tasks because those cannot be frozen and so the group remains in CGROUP_FREEZING state (update_if_frozen doesn't count stopped tasks) and never reaches CGROUP_FROZEN. Let's add is_task_frozen_enough back and use it at the original locations (update_if_frozen and try_to_freeze_cgroup). Semantically we consider stopped tasks as frozen enough so we should consider both cases when testing frozen tasks. Testcase: mkdir /dev/freezer mount -t cgroup -o freezer none /dev/freezer mkdir /dev/freezer/foo sleep 1h & pid=$! kill -STOP $pid echo $pid > /dev/freezer/foo/tasks echo FROZEN > /dev/freezer/foo/freezer.state while true do cat /dev/freezer/foo/freezer.state [ "`cat /dev/freezer/foo/freezer.state`" = "FROZEN" ] && break sleep 1 done echo OK Signed-off-by: Michal Hocko Acked-by: Li Zefan Cc: Tomasz Buchert Cc: Paul Menage Cc: Andrew Morton Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup_freezer.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -153,6 +153,13 @@ static void freezer_destroy(struct cgrou kfree(cgroup_freezer(cgroup)); } +/* task is frozen or will freeze immediately when next it gets woken */ +static bool is_task_frozen_enough(struct task_struct *task) +{ + return frozen(task) || + (task_is_stopped_or_traced(task) && freezing(task)); +} + /* * The call to cgroup_lock() in the freezer.state write method prevents * a write to that file racing against an attach, and hence the @@ -231,7 +238,7 @@ static void update_if_frozen(struct cgro cgroup_iter_start(cgroup, &it); while ((task = cgroup_iter_next(cgroup, &it))) { ntotal++; - if (frozen(task)) + if (is_task_frozen_enough(task)) nfrozen++; } @@ -284,7 +291,7 @@ static int try_to_freeze_cgroup(struct c while ((task = cgroup_iter_next(cgroup, &it))) { if (!freeze_task(task, true)) continue; - if (frozen(task)) + if (is_task_frozen_enough(task)) continue; if (!freezing(task) && !freezer_should_skip(task)) num_cant_freeze_now++;