"shutdown -p": (noperiph:aacp0:0:6:0): Device power down failed

Just updated my build machine from r203376 to r203425, which seeme dto
go well, but after I issued "shutdown -p now" (as I leave the machine
off when it's not in use), I saw the following on the serial console:

Uptime: 1m45s
(noperiph:aacp0:0:0:0): Device power down failed
(noperiph:aacp0:0:1:0): Device power down failed
(noperiph:aacp0:0:2:0): Device power down failed
(noperiph:aacp0:0:3:0): Device power down failed
(noperiph:aacp0:0:6:0): Device power down failed
Kernel page fault with the following non-sleepable locks held:
exclusive sleep mutex AAC I/O lock (AAC I/O lock) r = 0 (0xc56f2130) locked _at_ /usr/src/sys/dev/aac/aac.c:844
KDB: stack backtrace:
db_trace_self_wrapper(c0ca2cb6,e9aefb14,c08d68a5,c0c48d6b,34c,...) at db_trace_self_wrapper+0x26
kdb_backtrace(c0c48d6b,34c,ffffffff,c0f3bf6c,e9aefb4c,...) at kdb_backtrace+0x29
_witness_debugger(c0ca5178,e9aefb60,4,1,0,...) at _witness_debugger+0x25
witness_warn(5,0,c0cd9bf4,e9aefb88,c55717f8,...) at witness_warn+0x1fd
trap(e9aefbec) at trap+0x19e
calltrap() at calltrap+0x6
--- trap 0xc, eip = 0xc048550b, esp = 0xe9aefc2c, ebp = 0xe9aefc44 ---
xpt_done(c5200704,c56f2130,8,c0c48d6b,c56f2000,...) at xpt_done+0x1b
aac_cam_complete(c56fcec0,0,c0c48d6b,34c,c55fbd80,...) at aac_cam_complete+0x120
aac_new_intr(c56f2000,e9aefcc8,c0880bb4,c0e00340,c5576638,...) at aac_new_intr+0x1f0
intr_event_execute_handlers(c55717f8,c5576600,c0c9adc4,533,c5576670,...) at intr_event_execute_handlers+0x125
ithread_loop(c56f1bd0,e9aefd38,c0c9ab3d,343,c55717f8,...) at ithread_loop+0x9f
fork_exit(c08698b0,c56f1bd0,e9aefd38) at fork_exit+0xb8
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xe9aefd70, ebp = 0 ---


Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x14
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc048550b
stack pointer           = 0x28:0xe9aefc2c
frame pointer           = 0x28:0xe9aefc44
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 12 (irq24: aac0)
[thread pid 12 tid 100024 ]
Stopped at      xpt_done+0x1b:  movl    0x14(%eax),%ebx
db> show locks
exclusive sleep mutex AAC I/O lock (AAC I/O lock) r = 0 (0xc56f2130) locked _at_ /usr/src/sys/dev/aac/aac.c:844
db> 

I'll leave the machine in that state so I can poke at it, if there's
interest in figuring out what's wrong.  My laptop is a bit behind
the build machine at the moment -- it's just started building the
stable/8 kernel -- but I expect to be building head on it soon, and
I'll report if anything interesting turns up.

And to clarify, at r203376, the build machine handled the poweroff
request just fine.

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
Depriving a girl or boy of an opportunity for education is evil.

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