Re: softlockup: automatically detect hung TASK_UNINTERRUPTIBLEtasks

[Ingo Molnar]

* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> > Does that kernel have:
> > 
> > commit ed50d6cbc394cd0966469d3e249353c9dd1d38b9
> > Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> > Date:   Sat Feb 2 00:23:08 2008 +0100
> > 
> >     debug: softlockup looping fix
> 
> yup.  It was fetched less than 24 hours ago.

does the patch below improve the situation?

	Ingo

---
 arch/x86/kernel/reboot.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

Index: linux-x86.q/arch/x86/kernel/reboot.c
===================================================================
--- linux-x86.q.orig/arch/x86/kernel/reboot.c
+++ linux-x86.q/arch/x86/kernel/reboot.c
@@ -396,8 +396,20 @@ void machine_shutdown(void)
 	if (!cpu_isset(reboot_cpu_id, cpu_online_map))
 		reboot_cpu_id = smp_processor_id();
 
-	/* Make certain I only run on the appropriate processor */
-	set_cpus_allowed(current, cpumask_of_cpu(reboot_cpu_id));
+	/*
+	 * Make certain we only run on the appropriate processor,
+	 * and with sufficient priority:
+	 */
+	{
+		struct sched_param schedparm;
+		schedparm.sched_priority = 99;
+		int ret;
+
+		ret = sched_setscheduler(current, SCHED_RR, &schedparm);
+		WARN_ON_ONCE(1);
+
+		set_cpus_allowed(current, cpumask_of_cpu(reboot_cpu_id));
+	}
 
 	/* O.K Now that I'm on the appropriate processor,
 	 * stop all of the others.
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