kern/53033: panic: lock error: Mutex: mutex_vector_enter,555: locking against myself

[venture37%geeklan.co.uk@localhost]

>Number:         53033
>Category:       kern
>Synopsis:       panic: lock error: Mutex: mutex_vector_enter,555: locking against myself
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 16 23:00:00 +0000 2018
>Originator:     Sevan Janiyan
>Release:        NetBSD-HEAD
>Organization:
>Environment:
NetBSD/amd64 8.99.12
>Description:
I have a late 2009 13" Macbook which I have NetBSD installed on. I screwed up the disk partitioning and dk wedges hide the original disklabel info which means I can't correct things easily, so I built a new kernel without the DKWEDGE options, kernel boots and is unable to find root as fstab is incorrect now (expected), system sits at the prompt with the cursor flickering extremely rapidly before more usb devices are detected.
When ukbd0 is detected it reports
"This port is broken, it does not call cnpollc() before calling cngetc()
This show be fixed, but in will work anyway (for now)"

System continues detecting USB devices & panics with "panic: lock error: Mutex: mutex_vector_enter,555: locking against myself"

Backtrace is
vpanic()
snprintf()
lockdebug_abort()
mutex_vector_enter()
ohci_device_intr_start()
usbd_start_next()
ohci_softintr()
usbd_set_polling()
ukbd_cnpollc()
ukbd_cngetc()
wskbd_cngetc()
wsdisplay_getc()
cngetc()
cngetsn()
setroot()
main()
>How-To-Repeat:

>Fix: