Re: [PATCH 6/7] smp/hotplug: Differentiate the AP-work lockdep class between up and down

[Peter Zijlstra]

On Mon, Sep 25, 2017 at 05:54:59PM +0900, Byungchul Park wrote:
> On Wed, Sep 20, 2017 at 07:00:20PM +0200, Peter Zijlstra wrote:
> > With lockdep-crossrelease we get deadlock reports that span cpu-up and
> > cpu-down chains. Such deadlocks cannot possibly happen because cpu-up
> > and cpu-down are globally serialized.
> > 
> >   CPU0                  CPU1                    CPU2
> >   cpuhp_up_callbacks:   takedown_cpu:           cpuhp_thread_fun:
> > 
> >   cpuhp_state
> >                         irq_lock_sparse()
> >     irq_lock_sparse()
> >                         wait_for_completion()
> >                                                 cpuhp_state
> >                                                 complete()
> > 
> > Now that we have consistent AP state, we can trivially separate the
> > AP-work class between up and down using st->bringup.
> 
> Could you tell me what branch you worked the patches based on?
> This is similar to the problem of workqueue so I want to fix it on
> top of yours, as well.

I wrote the patches on top of tip/master. Thomas maintains these bits so
hopefully he'll eventually merge them in the right tip tree.