hang/panic when attaching/detaching Nikon Coolpix L5

[Toomas Aas]

Hello!

My system is 7-STABLE i386 from Jun 18.

I attach a digital camera (Nikon Coolpix L5) via USB to my computer, which 
has Asrock K7S41GX motherboard, with onboard SiS 5571 USB controller. The 
camera is set to 'Mass storage' mode.

The system seems to recognize the camera with some success:

Jun 25 16:35:48 bsd root: Unknown USB device: vendor 0x04b0 product 0x020d bus 
uhub1
Jun 25 16:35:48 bsd kernel: umass0: <NIKON NIKON DSC COOLPIX L5, class 0/0, 
rev 1.10/1.00, addr 2> on uhub1
Jun 25 16:35:48 bsd kernel: da0 at umass-sim0 bus 0 target 0 lun 0
Jun 25 16:35:48 bsd kernel: da0: <NIKON DSC COOLPIX L5 > Removable Direct 
Access SCSI-2 device
Jun 25 16:35:48 bsd kernel: da0: 1.000MB/s transfers
Jun 25 16:35:48 bsd kernel: da0: 485MB (994304 512 byte sectors: 64H 32S/T 
485C)

However, at that point the system pretty much hangs. I cannot start any new 
programs from the shell - after entering the command nothing happens and the 
command prompt does not return, hitting Ctrl+C has no effect.

3. I disconnect the camera and kernel panics. 

umass0: BBB reset failed, IOERROR
umass0: BBB bulk-in clear stall failed, IOERROR
umass0: at uhub1, port 2 (addr 2) disconnected
(da0:umass-sim0:0:0:0): lost device
(da0:dead-sim0):0:0:0): Synchronize cache failed, status == 0x39, scsi status 
== 0x0
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x0
fault code = supervisor write, page not present
instruction pointer = 0x20:0xc043fb4b
stack pointer = 0x28:0xd4cd4adc
frame pointer = 0x28:0xd4cd4af8
code segment = base 0x0, limit 0xfffff, type 0x1b
                     = DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt ennabled, resume, IOPL = 0
current process = 2 (g_event)
trap number = 12
panic: page fault
Uptime: 1m 20s

Instruction pointer and current process are always identical.

Unfortunately I haven't been able to get a kernel crash dump - I have all 
prerequisites set up, but the dump is not recorded, maybe because the system 
is already in an unstable state when the panic occurs. The best I can do is 
this:

$ nm -n /boot/kernel/kernel | grep c043fb
c043fb10 T xpt_done

Note that I haven't mounted the camera before disconnecting, so it's probably 
not the 'frequently reported problem' described on Jeremy Chadwick's wiki 
page.

Any further ideas on how to debug such problem?

--
Toomas Aas