(kgdb) bt
#0  doadump (textdump=1) at /usr/src/sys/kern/kern_shutdown.c:260
#1  0xffffffff803ad255 in kern_reboot (howto=16644) at /usr/src/sys/kern/kern_shutdown.c:442
#2  0xffffffff803ad701 in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:607
#3  0xffffffff805dc0a0 in trap_fatal (frame=0xc, eva=Variable "eva" is not available.
) at /usr/src/sys/amd64/amd64/trap.c:819
#4  0xffffffff805dc3e9 in trap_pfault (frame=0xffffff8112f2b880, usermode=0) at /usr/src/sys/amd64/amd64/trap.c:735
#5  0xffffffff805dc8af in trap (frame=0xffffff8112f2b880) at /usr/src/sys/amd64/amd64/trap.c:474
#6  0xffffffff805c6dcf in calltrap () at /usr/src/sys/amd64/amd64/exception.S:228
#7  0xffffffff80b6778b in iwn_ampdu_tx_done (sc=0xffffff80007c8000, qid=Variable "qid" is not available.
)
    at /usr/src/sys/modules/iwn/../../dev/iwn/if_iwn.c:2816
#8  0xffffffff80b6b1d9 in iwn_notif_intr (sc=0xffffff80007c8000)
    at /usr/src/sys/modules/iwn/../../dev/iwn/if_iwn.c:2908
#9  0xffffffff80b6e88b in iwn_intr (arg=Variable "arg" is not available.
) at /usr/src/sys/modules/iwn/../../dev/iwn/if_iwn.c:3199
#10 0xffffffff80383364 in intr_event_execute_handlers (p=Variable "p" is not available.
) at /usr/src/sys/kern/kern_intr.c:1257
#11 0xffffffff80384b24 in ithread_loop (arg=0xfffffe00031e0760) at /usr/src/sys/kern/kern_intr.c:1270
#12 0xffffffff8037ffbf in fork_exit (callout=0xffffffff80384a80 <ithread_loop>, arg=0xfffffe00031e0760,
    frame=0xffffff8112f2bc50) at /usr/src/sys/kern/kern_fork.c:995
#13 0xffffffff805c72fe in fork_trampoline () at /usr/src/sys/amd64/amd64/exception.S:602
#14 0x0000000000000000 in ?? ()
#15 0x0000000000000000 in ?? ()
#16 0x0000000000000001 in ?? ()
#17 0x0000000000000000 in ?? ()
#18 0x0000000000000000 in ?? ()
#19 0x0000000000000000 in ?? ()
#20 0x0000000000000000 in ?? ()
#21 0x0000000000000000 in ?? ()