Laptop ACPI poweroff failed after main-c255826 -> main-c255850

At the conclusion of each morning's "update cycle," I have (for
some time) been in the habit of powering the laptop off, leaving
it powered off for about 15 seconds, then powering it back up.  (The
build machine also gets powered off, but doesn't get powered back
up until a bit before midnight.)  This is usually the only time the
laptop is powered off (which may reflect ... something :-} ).

Today's update was from:
FreeBSD g1-55.catwhisker.org 13.0-CURRENT FreeBSD 13.0-CURRENT #118 main-c255826-g81b3a0a34145-dirty: Sun Jan 10 04:02:54 PST 2021     root_at_g1-55.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY  amd64 1300134 1300134

to:
FreeBSD g1-55.catwhisker.org 13.0-CURRENT FreeBSD 13.0-CURRENT #119 main-c255850-g16079c7233be-dirty: Mon Jan 11 04:01:51 PST 2021     root_at_g1-55.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY  amd64 1300134 1300134

(and yes, while the tree was "dirty," that's because none of my
local changes are committed; the counts & hashes correspond with
what's on git.freebsd.org).

I have place a photo of the screen in
https://www.catwhisker.org/~david/FreeBSD/head/c255850/

Here is a hand-transcription of the final few lines:

acpi_button0: wake_prep disabled wake for \_SB_.PBBTN (S5)
nvidia-modeset: Unloading
pci3: unknown notify 0x2
ACPI Error: AE_ERROR, Thread 100002 could not acquire Mutex [ACPI_MTX_Caches] (0c4) (20201113/utmutex-434)
ACPI Error: Aborting method \_PTS due to previous error (AE_NO_MEMORY) (20201113/psparse-689)
acpi0: AcpiEnterSleepStatePrep failed - AE_NO_MEMORY

The operating system has halted.
Please press any key to reboot.


[At that point, after getting the photo, I pressed the power burtton
long enough to power the machine off, waited about 15 seconds, then
powered it back up.]

A copy of the (verbose) dmesg.boot (grabbed just before the attempted
power-off) may be found at
https://www.catwhisker.org/~david/FreeBSD/history/laptop.13_dmesg.txt

Normal and gzipped copies of the kernel config file ("CANARY") are at
https://www.catwhisker.org/~david/FreeBSD/head/

As may be seen, the config includes GENERIC, and tweaks it a bit --
but hasn't been changed since 01 December 2020.

While I won't be able to do much testing with the laptop for several
hours (as I use it for work), I'm happy to test when I can.

The build machine seems to have powered off without complaint, FWIW.

What may I do to help figure out what's wrong?

Peace,
david
-- 
David H. Wolfskill                              david_at_catwhisker.org
"I want him to resign. I want him out. He has caused enough damage."
 - Senator Lisa Murkowski (R-AK)

See https://www.catwhisker.org/~david/publickey.gpg for my public key.