kworker with empty task->cpus_allowed (was Re: [v4.12-rc1 regression] mount ext4 fs results in kernel crash on PPC64le host)

[Tejun Heo]

Hello, Michael.

On Fri, Jun 30, 2017 at 11:08:22AM +1000, Michael Ellerman wrote:
> Tejun Heo <tj at kernel.org> writes:
> 
> > Could be the same problem as the one reported in the following thread.
> >
> >  http://lkml.kernel.org/r/1497266622.15415.39.camel@abdul.in.ibm.com
> >
> > The root cause there is ppc arch code not setting up possible cpu <->
> > numa mapping during boot.
> 
> Huh?
> 
> You changed the workqueue code to avoid that in 2186d9f940b6
> ("workqueue: move wq_numa_init() to workqueue_init()"), didn't you?

That was a different issue.  This one is cpu <-> numa node mapping not
being stable across cpu hotplug.

Thanks.

-- 
tejun