> It looks like something has trashed the pv_table :-/
> Please look at the first four longwords at address 0x80422df0
> (or if you have rebooted, the argument to pmap_page_protect_long() if
> it happens again).  That may give a hint what is broken.

K:

panic: Segv in kernel mode: pc 801acc04 addr 869a160f
Stopped in pid 12276.1 (sort) at        netbsd:trap+0x619:      movl 
$1, r11
db> tr
panic: Segv in kernel mode: pc %x addr %x
Stack traceback :
0x89dfcc64: trap+0x619(0x89dfcd28)
0x89dfcd28: trap type=0xc code=0x869a160f pc=0x801acc04 psl=0xc00000
0x89dfccf4: pmap_page_protect_long+0x244(0x803fa4a0,0x1)
0x89dfcd78: uvm_loan+0x377(0x83f51e14,0x1ad000,0x3000,0x86fae4a0,0x2)
0x89dfcde8: 
pipe_write+0x394(0x84bcc0f4,0x84bcc120,0x89dfce9c,0x86712898,0x1)
0x89dfce58: 
dofilewrite+0x77(0x815bc914,0x1,0x84bcc0f4,0x1ad000,0x2430,0x84bcc12
0,0x1,0x89dfcf74)
0x89dfced0: sys_write+0x4b(0x815bc914,0x89dfcf54,0x89dfcf74)
0x89dfcf24: syscall_plain+0xa7(0x89dfcfb4)
db> x/wx 0x803fa4a0,4
0x803fa4a0:     0           1af000      8705a040    84000000