Re: [PATCH v1] kthread/smpboot: Serialize kthread parking against wakeup

[Peter Zijlstra]

On Wed, Jun 06, 2018 at 03:51:16PM +0200, Oleg Nesterov wrote:
> In particular, I think that kthread_park() on a parked kthread
> must not be possible.

It happens though; I put in a WARN and someone triggered it -- although
I could not reproduce :/