Re: [PATCH 1/1] kthread: don't abuse kthread_create_on_cpu() in __kthread_create_worker()

[Petr Mladek]

On Thu 2016-11-10 18:20:31, Oleg Nesterov wrote:
> kthread_create_on_cpu() sets KTHREAD_IS_PER_CPU and kthread->cpu, this
> only makes sense if this kthread can be parked/unparked by cpuhp code.
> kthread workers never call kthread_parkme() so this has no effect.

Yes.

> Change __kthread_create_worker() to simply call kthread_bind(task, cpu).
> The very fact that kthread_create_on_cpu() doesn't accept a generic fmt
> shows that it should not be used outside of smpboot.c.
> 
> Now, the only reason we can not unexport this helper and move it into
> smpboot.c is that it sets kthread->cpu and struct kthread is not exported.
> And the only reason we can not kill kthread->cpu is that kthread_unpark()
> is used by drivers/gpu/drm/amd/scheduler/gpu_scheduler.c and thus we can
> not turn _unpark into kthread_unpark(struct smp_hotplug_thread *, cpu).
> 
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

The change looks fine to me. Feel free to add one or both of these:

Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Tested-by: Petr Mladek <pmladek@xxxxxxxx>

Best Regards,
Petr