Re: linux-next boot error: WARNING: workqueue cpumask: online intersect > possible intersect

[Dmitry Vyukov]

On Tue, Jun 11, 2019 at 8:52 PM Tejun Heo <tj@xxxxxxxxxx> wrote:
>
> Hello,
>
> On Fri, Jun 07, 2019 at 10:45:45AM +0200, Dmitry Vyukov wrote:
> > +workqueue maintainers and Michael who added this WARNING
> >
> > The WARNING was added in 2017, so I guess it's a change somewhere else
> > that triggered it.
> > The WARNING message does not seem to give enough info about the caller
> > (should it be changed to WARN_ONCE to print a stack?). How can be root
> > cause this and unbreak linux-next?
>
> So, during boot, workqueue builds masks of possible cpus of each node
> and stores them on wq_numa_possible_cpumask[] array.  The warning is
> saying that somehow online cpumask of a node became a superset of the
> possible mask, which should never happen.
>
> Dumping all masks in wq_numa_possible_cpumasks[] and cpumask_of_node()
> of each node should show what's going on.

This has reached upstream and all subsystem subtrees, now all Linux
trees are boot broken (except for few that still lack behind):
https://syzkaller.appspot.com/upstream

No new Linux code is tested by syzbot at this point.