Re: CFS and suspend2: hang in atomic copy

Ingo Molnar
2007-04-19T06:28:49Z

* Christian Hesse <mail@earthworm.de> wrote:

> I now got some error message from my system:
>
> http://www.eworm.de/tmp/cfs-suspend.jpg

ah, this pinpoints a bug: for performance reasons pick_next_task()
assumes that the runqueue is not empty - which is true for schedule(),
but not in migrate_dead_tasks(). 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;