Re: [lkp] [workqueue] 82607adcf9: BUG: workqueue lockup - pool cpus=0 flags=0x4 nice=0 stuck for 42s!

[Tejun Heo]

Hello,

On Sun, Feb 14, 2016 at 09:07:04AM +0800, kernel test robot wrote:
> FYI, we noticed the below changes on
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> commit 82607adcf9cdf40fb7b5331269780c8f70ec6e35 ("workqueue: implement lockup detector")
> 
> 
> [   75.684302] virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
> [   88.791869] ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 11
> [   88.795120] virtio-pci 0000:00:07.0: virtio_pci: leaving for legacy driver
> [   90.789792] BUG: workqueue lockup - pool cpus=0 flags=0x4 nice=0 stuck for 42s!
> [   90.794158] Showing busy workqueues and worker pools:
> [   90.796507] workqueue cgroup_pidlist_destroy: flags=0x0
> [   90.798976]   pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1

Was the VM not executing for a long time?  I can't think why
cgroup_pidlist_destroy would hang for over 40s.

Thanks.

-- 
tejun