From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751930Ab1HUSBb (ORCPT ); Sun, 21 Aug 2011 14:01:31 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:55576 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750784Ab1HUSB3 (ORCPT ); Sun, 21 Aug 2011 14:01:29 -0400 From: "Rafael J. Wysocki" To: Tejun Heo Subject: Re: [GIT PULL pm-next] freezer: fix various bugs and simplify implementation Date: Sun, 21 Aug 2011 20:03:14 +0200 User-Agent: KMail/1.13.6 (Linux/3.1.0-rc2+; KDE/4.6.0; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, arnd@arndb.de, oleg@redhat.com, lizf@cn.fujitsu.com, paul@paulmenage.org, Matt Helsley , Martin Schwidefsky References: <20110820094434.GA24151@htj.dyndns.org> <201108201833.39089.rjw@sisk.pl> <20110821091200.GB24151@htj.dyndns.org> In-Reply-To: <20110821091200.GB24151@htj.dyndns.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201108212003.14722.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday, August 21, 2011, Tejun Heo wrote: > Hello, Rafafel. > > On Sat, Aug 20, 2011 at 06:33:38PM +0200, Rafael J. Wysocki wrote: > > > ssh://master.kernel.org/pub/scm/linux/kernel/git/tj/misc.git freezer > > > > Pulled and stored in the pm-freezer branch in my tree, and merged into > > the linux-next branch. > > Cool. > > > > FYI, this patchset will cause a conflict with s390 TIF flag fix patch. > > > The conflict is trivial and Stephen should be able to handle it > > > without any problem. Also, I'm planning on doing some further work on > > > cgroup freezer and then will try to bridge it with job control. If > > > that plan fans out, I might ask Oleg to pull from the pm tree. > > > > I'm not sure if Linus likes it. He generally doesn't want the trees > > that he pulls from to be entangled this way. > > The job control portion has to go through Linus anyway, so let's see > how that flies. > > > > This shouldn't matter too much either way but it *might* be a good idea to > > > keep this line of patches in a separate branch. > > > > I'm going to keep it in the pm-freezer branch anyway (there may be patches > > on top of it, though) > > Yeah, I'm pretty sure it will need some fix too. Speaking of which, the addition of might_sleep() to try_to_freeze() causes a badly looking backtrace to appear during reboot on ARM, so I'd prefer it to go into __refrigerator(). Please tell me what you think of the patch below. Rafael --- From: Rafael J. Wysocki Subject: PM / Freezer: Move might_sleep() from try_to_freeze() There are some code paths that call try_to_freeze() from interrupt context, but doing so they know that the current process cannot possible be freezing (e.g. during reboot on ARM). However, the recently added might_sleep() annotation in try_to_freeze() triggers in those cases, making it look like there were bugs in those places, which really isn't the case. Therefore move might_sleep() from try_to_freeze() to __refrigerator() so that it doesn't produce false positives. Signed-off-by: Rafael J. Wysocki --- include/linux/freezer.h | 1 - kernel/freezer.c | 2 ++ 2 files changed, 2 insertions(+), 1 deletion(-) Index: linux/include/linux/freezer.h =================================================================== --- linux.orig/include/linux/freezer.h +++ linux/include/linux/freezer.h @@ -41,7 +41,6 @@ extern void thaw_processes(void); static inline bool try_to_freeze(void) { - might_sleep(); if (likely(!freezing(current))) return false; return __refrigerator(false); Index: linux/kernel/freezer.c =================================================================== --- linux.orig/kernel/freezer.c +++ linux/kernel/freezer.c @@ -54,6 +54,8 @@ bool __refrigerator(bool check_kthr_stop bool was_frozen = false; long save; + might_sleep(); + /* * No point in checking freezing() again - the caller already did. * Proceed to enter FROZEN.