panic: mtx_lock() of spin mutex (null) @ /usr/src/sys/net/iflib.c:3716

[Mark Johnston]

On Wed, Apr 11, 2018 at 04:39:58AM -0700, David Wolfskill wrote:
> This was running:
> 
> FreeBSD g1-215.catwhisker.org 12.0-CURRENT FreeBSD 12.0-CURRENT #156  r332399M/332400:1200061: Wed Apr 11 04:17:45 PDT 2018     root at g1-215.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY  amd64
> 
> during boot, after updating from:
> 
> FreeBSD g1-215.catwhisker.org 12.0-CURRENT FreeBSD 12.0-CURRENT #155  r332354M/332357:1200061: Tue Apr 10 04:00:41 PDT 2018     root at g1-215.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY  amd64
> 
> (My build machine, which uses an re((4) NIC, did not encounter the issue.)
> 
> It appears that r332389 is implicated.

I'm seeing this too, under bhyve with e1000 emulation. Reverting r332389
fixes the problem.