WQ_UNBOUND warning since recent workqueue refactoring

[Heiner Kallweit]

Recently I started to see the following warning on linux-next and presumably
this may be related to the refactoring of the workqueue core code.

[   56.900223] workqueue: output_poll_execute [drm_kms_helper] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
[   56.923226] workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
[   97.860430] workqueue: output_poll_execute [drm_kms_helper] hogged CPU for >10000us 8 times, consider switching to WQ_UNBOUND
[   97.884453] workqueue: i915_hpd_poll_init_work [i915] hogged CPU for >10000us 8 times, consider switching to WQ_UNBOUND

Adding WQ_UNBOUND to these queues didn't change the behavior.
Maybe relevant: I run the affected system headless.