Re: cpu stopper threads and load balancing leads to deadlock

[Peter Zijlstra]

On Thu, May 03, 2018 at 07:39:41AM -0700, Paul E. McKenney wrote:
> Huh.
> 
> No, RCU_NONIDLE() only works for idle, not for offline.

Oh bummer..

> Maybe...  Let me take a look.  There must be some way to mark a
> specific lock acquisition and release as being lockdep-invisible...

But I suspect it flags a real issue. Shutting it up isn't the issue as
such. There could be a concurrent sched domain rebuild while we do this
setup, and if we free that domain while we're looking at it, bad things
happen.

... I wonder what brought this failure to pass now. This code has been
like this a for a long time.