Simple panic with 6.1.4?

[Darren Reed <darrenr%netbsd.org@localhost>]

I was extracting src.tgz in a VM and thinking that it was taking too
long, opened up another window and did "mount -o async -u /".

uvm_fault(0xc0c736c0, 0xfffff000, 1) -> 0xe
fatal page fault in supervisor mode
trap type 6 code 0 eip c053913f cs 8 eflags 10283 cr2 fffffffc ilevel 0
panic: trap
cpu0: Begin traceback...
printf_nolog(c0ba9593,c781bbac,c781bbac,c053913f,8,10283,fffffffc,0,c11d3aa0,c05
4cde4) at netbsd:printf_nolog
trap_tss() at netbsd:trap_tss
--- trap via task gate ---
c11d3aa0:
cpu0: End traceback...

(gdb) where
#0  0xc05a2208 in cpu_reboot ()
#1  0xc0790ada in vpanic ()
#2  0xc0790b7f in panic ()
#3  0xc07df31c in trap ()
#4  0xc010cf48 in calltrap ()
#5  0xc781bbac in end ()
#6  0x00000010 in _KERNEL_OPT_NVCODA ()
#7  0x00000030 in _KERNEL_OPT_RASOPS_DEFAULT_HEIGHT ()
#8  0xc0b70010 in ?? ()
#9  0xc0892bf4 in wapbl_begin ()
#10 0xc0814600 in ufs_reclaim ()
#11 0xc030d2d6 in ffs_reclaim ()
#12 0xc08ac57a in VOP_RECLAIM ()
#13 0xc088efa2 in vclean ()
#14 0xc088fa10 in cleanvnode ()
#15 0xc088fb0a in vdrain_thread ()
#16 0xc0100321 in lwp_trampoline ()

Kind Regards,
Darren