Re: broken suspend (sched related) [Was: 2.6.24-rc4-mm1]

[Ingo Molnar <mingo@elte.hu>]

* Jiri Slaby <jirislaby@gmail.com> wrote:

> On 12/05/2007 06:17 AM, Andrew Morton wrote:
> >   ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc4/2.6.24-rc4-mm1/
> 
> >  git-sched.patch
> 
> breaks suspend here since -rc3-mm2. More precisely, this one:
> softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
> 
> 2.6.24-rc4-mm1 minus this one works just fine. Otherwise disks stop, graphics
> stops and then it hangs not powering down.
> 
> Core 2 Duo, SMP kernel, voluntary preempt, 250 HZ, SLUB, 64 bit.
> 
> Ideas?

thanks for tracking it down. Does the patch below help?

	Ingo

---
 kernel/softlockup.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Index: linux/kernel/softlockup.c
===================================================================
--- linux.orig/kernel/softlockup.c
+++ linux/kernel/softlockup.c
@@ -101,7 +101,11 @@ void softlockup_tick(void)
 
 	now = get_timestamp(this_cpu);
 
-	/* Warn about unreasonable delays: */
+	/* Wake up the high-prio watchdog task every second: */
+	if (now > (touch_timestamp + 1))
+		wake_up_process(per_cpu(watchdog_task, this_cpu));
+
+	/* Warn about unreasonable 10+ seconds delays: */
 	if (now <= (touch_timestamp + softlockup_thresh))
 		return;
 
@@ -214,7 +218,7 @@ static int watchdog(void *__bind_cpu)
 	 */
 	while (!kthread_should_stop()) {
 		touch_softlockup_watchdog();
-		msleep_interruptible(10000);
+		schedule();
 
 		/*
 		 * Only do the hung-tasks check on one CPU:
--
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