Re: Deadlock on poweroff

Kirill A. Shutemov
2012-10-07T16:49:37Z

On Sun, Oct 07, 2012 at 09:03:11AM -0700, Paul E. McKenney wrote:
> On Sun, Oct 07, 2012 at 05:47:11AM +0300, Kirill A. Shutemov wrote:
> > Hi Paul and all,
> >
> > With commit 755609a9087fa983f567dc5452b2fa7b089b591f I've got deadlock on
> > poweroff.
> >
> > It guess it happens because of race for cpu_hotplug.lock:
> >
> > CPU A CPU B
> > disable_nonboot_cpus()
> > _cpu_down()
> > cpu_hotplug_begin()
> > mutex_lock(&cpu_hotplug.lock);
> > __cpu_notify()
> > padata_cpu_callback()
> > __padata_remove_cpu()
> > padata_replace()
> > synchronize_rcu()
> > rcu_gp_kthread()
> > get_online_cpus();
> > mutex_lock(&cpu_hotplug.lock);
> >
> > Have you seen the issue before?
>
> This is a new one for me. Does the following (very lightly tested)
> patch help?

Works for me. Thanks.

--
Kirill A. Shutemov