On Sun, 7 Apr 2013, Borislav Petkov wrote:
> On Sun, Apr 07, 2013 at 11:20:10AM +0200, Thomas Gleixner wrote:
> > And it's even more bogus because the cpu to which we would bind in
> > kthread_create_on_cpu() is not yet online.
>
> In case you guys are wondering about reproducibility, I saw the same
> BUG_ON yesterday on a 32-bit atom smp qemu guest too (don't ask why?
> :-))
I don't have to ask. It's caused by massive brain failure on my side.
Does the patch below fix the issue ?
Thanks,
tglx
---
Index: linux-2.6/kernel/kthread.c
===================================================================
--- linux-2.6.orig/kernel/kthread.c
+++ linux-2.6/kernel/kthread.c
@@ -131,8 +131,14 @@ static void __kthread_parkme(struct kthr
schedule();
__set_current_state(TASK_INTERRUPTIBLE);
}
- clear_bit(KTHREAD_IS_PARKED, &self->flags);
__set_current_state(TASK_RUNNING);
+ clear_bit(KTHREAD_IS_PARKED, &self->flags);
+
+ /* Rebind ourself to the target cpu */
+ if (test_bit(KTHREAD_IS_PER_CPU, &self->flags)) {
+ set_cpus_allowed_ptr(currrent, cpumask_of(self->cpu));
+ current->flags |= PF_THREAD_BOUND;
+ }
}
void kthread_parkme(void)
@@ -344,11 +350,8 @@ void kthread_unpark(struct task_struct *
* park before that happens we'd see the IS_PARKED bit
* which might be about to be cleared.
*/
- if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
- if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
- __kthread_bind(k, kthread->cpu);
+ if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags))
wake_up_process(k);
- }
}
put_task_struct(k);
}
--
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