Thread stuck in aioprn

When running stress2 I got an unkillable process stuck in the aioprn
state:

#0  sched_switch (td=0xc5652bd0, newtd=0xc4916a20, flags=1) at atomic.h:265
#1  0xc0549b96 in mi_switch (flags=1, newtd=0x0) at ../../../kern/kern_synch.c:425
#2  0xc056baa6 in sleepq_switch (wchan=0x0) at ../../../kern/subr_sleepqueue.c:450
#3  0xc056bc9b in sleepq_timedwait (wchan=0xc5668c80) at ../../../kern/subr_sleepqueue.c:567
#4  0xc054959e in msleep (ident=0xc5668c80, mtx=0xc5c6ee0c, priority=76, wmesg=0xc0763914 "aioprn", timo=100)
    at ../../../kern/kern_synch.c:207
#5  0xc05a0597 in aio_proc_rundown (arg=0x0, p=0xc5668b04) at ../../../kern/vfs_aio.c:699
#6  0xc0524769 in exit1 (td=0xc5652bd0, rv=9) at ../../../kern/kern_exit.c:237
#7  0xc0545eab in sigexit (td=0xc5652bd0, sig=9) at ../../../kern/kern_sig.c:2883
#8  0xc0546c3b in postsig (sig=9) at ../../../kern/kern_sig.c:2765
#9  0xc056e503 in ast (framep=0xed16dd38) at ../../../kern/subr_trap.c:270
#10 0xc06ff61d in doreti_ast () at ../../../i386/i386/exception.s:284

This was from the 'random syscall' test, so chances are there is some
insufficient error handling of invalid data here.

Kris