Re: CFS and suspend2: hang in atomic copy

[Ingo Molnar <mingo@elte.hu>]

* Bob Picco <bob.picco@hp.com> wrote:

> I had hoped to collect more data with CFS V2. It crashes in 
> scale_nice_down for s2ram when attempting to disable_nonboot_cpus. So 
> part of traceback looks like (typed by hand with obvious omissions):
> 
> scale_nice_down
> update_stats_wait_end - not shown in traceback because inlined
> pick_next_task_fair
> migration_call
> task_rq_lock
> notifier_call_chain
> _cpu_down
> disable_nonboot_cpus

ok, this looks similar to the jpeg Christian did. Does the patch below 
fix the crash for you?

	Ingo

---
 kernel/sched.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -4425,6 +4425,8 @@ static void migrate_dead_tasks(unsigned 
 	struct task_struct *next;
 
 	for (;;) {
+		if (!rq->nr_running)
+			break;
 		next = pick_next_task(rq, rq->curr);
 		if (!next)
 			break;
-
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