CURRENT- and vmd(8): Panic upon bootup with recent HEAD

Hi freebsd-current@ (CC'd ambrisko@ and imp@),

Right now, with a laptop (HP Spectre x360 13t-aw200) which needs the 
vmd(8) driver for NVMe, I am getting kernel panics upon bootup with a 
recent kernel.

Here's a screenshot of the panic: 
https://bz-attachments.freebsd.org/attachment.cgi?id=226185 (blurry 
since I took it on the plane)

The bug is here: 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=256915

If I use an older kernel (which I'm doing for now), it works fine. If I 
use the memstick USB, it crashes with the same panic.

I initially thought it was commit 
ddfc9c4c59e2ea4871100d8c076adffe3af8ff21, but even when I reverted to 
one before the said commit, it still panicked with the same error.

I don't see any changes to vmd(8), so changes to some other PC subsystem 
(PCI/ACPI/x86/NVMe/etc.) after commit 
ab6d05336caaa10ae315f81534851e3764a8660c (current kernel commit) must 
have caused the error.

-Neel (nc@)