panic: vm_fault: fault on nofault entry

For the last few days I have been getting a panic while probing devices 
(a kernel from "Mon May  2 20:36:06 CDT 2005" works fine):

<snip>
ad4: 76319MB <WDC WD800JB-00CRA1 17.07W17> at ata2-master UDMA100
ad6: 76319MB <WDC WD800JB-00CRA1 17.07W17> at ata3-master UDMA100
unknown: WARNING - INQUIRY UDMA ICRC error (retrying request)
unknown: WARNING - INQUIRY requeued due to channel reset
unknown: WARNING - INQUIRY read data overrun 18>0
panic: vm_fault: fault on nofault entry, addr: deadc000
KDB: stack backtrace:
panic(c06c86f0,deadc000,1,e35e3b0c,e35e3afc) at panic+0x13a
vm_fault(c103b000,deadc000,1,0,c227f900) at vm_fault+0x1440
trap_pfault(deadc31e,c05077c0,c070ede0,32c,deadc31e) at trap_pfault+0x82
trap(8,c0710028,c2340028,2d2,0) at trap+0x353
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc04eb7b1, esp = 0xe35e3c1c, ebp = 0xe35e3c40 ---
_mtx_lock_flags(deadc31e,0,c06a8d9c,2d2,c) at _mtx_lock_flags+0x2c
atapi_cb(c25014b0,e35e3ca0,c04eb997,c227649c,1) at atapi_cb+0x68
ata_completed(c25014b0,1,c06b6c45,d7,c227649c) at ata_completed+0x114
taskqueue_run(c2276480,0,c06b16b5,256,c070ede0) at taskqueue_run+0x8b
ithread_loop(c2276400,e35e3d38,c06b1496,30d,c2276400) at ithread_loop+0x1ff
fork_exit(c04deb26,c2276400,e35e3d38) at fork_exit+0xa1
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xe35e3d6c, ebp = 0 ---
KDB: enter: panic
[thread pid 43 tid 100032 ]
Stopped at      kdb_enter+0x32: leave
db> reset

Normally that section looks like this:

<snip>
ad4: 76319MB <WDC WD800JB-00CRA1 17.07W17> at ata2-master UDMA100
ad6: 76319MB <WDC WD800JB-00CRA1 17.07W17> at ata3-master UDMA100
da0 at asr0 bus 0 target 0 lun 0
da0: <ADAPTEC RAID-0 370F> Fixed Direct Access SCSI-2 device
da0: Tagged Queueing Enabled
da0: 35003MB (71686144 512 byte sectors: 255H 63S/T 4462C)
cd0 at ata0 bus 0 target 0 lun 0
cd0: <SONY CD-RW  CRX300E KYS1> Removable CD-ROM SCSI-0 device
cd0: 3.300MB/s transfers
cd0: Attempt to query device size failed: NOT READY, Medium not present
ATA PseudoRAID loaded
ar0: 76293MB <Promise Fasttrak RAID1 array> status: READY
ar0: disk0 READY (master) using ad4 at ata2-master
ar0: disk1 READY (mirror) using ad6 at ata3-master
Trying to mount root from ufs:/dev/da0s2a

This is trivially reproducible so if anyone needs more information from 
ddb just ask and I'll reboot...

-- 
Jonathan Noack | noackjr_at_alumni.rice.edu | OpenPGP: 0x991D8195