From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756075Ab1G1VNH (ORCPT ); Thu, 28 Jul 2011 17:13:07 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:60266 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754678Ab1G1VNF (ORCPT ); Thu, 28 Jul 2011 17:13:05 -0400 From: "Rafael J. Wysocki" To: Oliver Neukum Subject: Re: [PATCH] Unfreeze tasks after an oops in the freezer Date: Thu, 28 Jul 2011 23:14:05 +0200 User-Agent: KMail/1.13.6 (Linux/3.0.0+; KDE/4.6.0; x86_64; ; ) Cc: Andrew Morton , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <201107271235.58734.oneukum@suse.de> In-Reply-To: <201107271235.58734.oneukum@suse.de> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201107282314.05894.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, July 27, 2011, Oliver Neukum wrote: > From ee5849f0bc39d554ef91747ff80c307ac3e05cdd Mon Sep 17 00:00:00 2001 > From: Oliver Neukum > Date: Wed, 27 Jul 2011 12:27:00 +0200 > Subject: [PATCH] Unfreeze tasks after an oops in the freezer > > If an oops kills the task suspending or snapshotting > is system, the system is dead because the action is > never completed and the tasks never thawed. > > Signed-off-by: Oliver Neukum > --- > include/linux/freezer.h | 2 ++ > kernel/panic.c | 8 ++++++++ > kernel/power/process.c | 11 +++++++++++ > 3 files changed, 21 insertions(+), 0 deletions(-) > > diff --git a/include/linux/freezer.h b/include/linux/freezer.h > index 1effc8b..ab0168a 100644 > --- a/include/linux/freezer.h > +++ b/include/linux/freezer.h > @@ -50,6 +50,7 @@ extern int thaw_process(struct task_struct *p); > extern void refrigerator(void); > extern int freeze_processes(void); > extern void thaw_processes(void); > +extern void thaw_in_oops(void); > > static inline int try_to_freeze(void) > { > @@ -181,6 +182,7 @@ static inline void freezer_count(void) {} > static inline int freezer_should_skip(struct task_struct *p) { return 0; } > static inline void set_freezable(void) {} > static inline void set_freezable_with_signal(void) {} > +static inline void thaw_in_oops(void) {} > > #define wait_event_freezable(wq, condition) \ > wait_event_interruptible(wq, condition) > diff --git a/kernel/panic.c b/kernel/panic.c > index 6923167..ccdd834 100644 > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #define PANIC_TIMER_STEP 100 > #define PANIC_BLINK_SPD 18 > @@ -355,6 +356,13 @@ void oops_exit(void) > do_oops_enter_exit(); > print_oops_end_marker(); > kmsg_dump(KMSG_DUMP_OOPS); > + /* > + * if we oops while tasks are frozen, the system > + * will stop dead because the task that would thaw it > + * has been killed. So the system must be explicitly > + * thawed here. > + */ > + thaw_in_oops(); > } > > #ifdef WANT_WARN_ON_SLOWPATH > diff --git a/kernel/power/process.c b/kernel/power/process.c > index 0cf3a27..c03e88b 100644 > --- a/kernel/power/process.c > +++ b/kernel/power/process.c > @@ -22,6 +22,9 @@ > */ > #define TIMEOUT (20 * HZ) > > +/* in case we oops while processes are frozen */ > +static bool tasks_frozen = false; > + > static inline int freezable(struct task_struct * p) > { > if ((p == current) || > @@ -131,6 +134,7 @@ static int try_to_freeze_tasks(bool sig_only) > elapsed_csecs % 100); > } > > + tasks_frozen = (todo == 0); I'd prefer it to be set by freeze_processes(), when oom_killer_disable() is called. > return todo ? -EBUSY : 0; > } > > @@ -189,7 +193,14 @@ void thaw_processes(void) > thaw_workqueues(); > thaw_tasks(true); > thaw_tasks(false); > + tasks_frozen = false; > schedule(); > printk("done.\n"); > } > > +void thaw_in_oops(void) > +{ > + if (tasks_frozen) > + thaw_processes(); > +} > + Thanks, Rafael