Re: workqueue: WARN at at kernel/workqueue.c:2176

[Peter Zijlstra]

On Fri, May 16, 2014 at 05:56:10PM +0800, Lai Jiangshan wrote:
> On 05/16/2014 05:35 PM, Peter Zijlstra wrote:
> > On Fri, May 16, 2014 at 11:50:42AM +0800, Lai Jiangshan wrote:
> >> After debugging, I found the hotlug-in cpu is atctive but !online in this case.
> >> the problem was introduced by 5fbd036b.
> >> Some code assumes that any cpu in cpu_active_mask is also online, but 5fbd036b breaks
> >> this assumption, so the corresponding code with this assumption should be changed too.
> > 
> > Good find, and yes it does that.
> > 
> >> The following patch is just a workaround. After it is applied, the above WARNING
> >> is gone, but I can't hit the wq problem that you found.
> > 
> > Seeing how the entirety of hotplug is basically duct tape and twigs, the
> > below isn't that bad.
> 
> I think we need to find a more grace solution...

A complete rewrite of the hotplug mess, until that time this is fine.

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