Panic on post-freeze current with ucom

[R.Mahmatkhanov]

>In message: <46790374.8040903 at yandex.ru>
>            "R.Mahmatkhanov" <cvs-src at yandex.ru> writes:
>: Good Day.
>: 
>: I just move to latest -current/i386 after the code freeze. And i catch
>: 100% reproduceble panic condition. It happens when i plug my mobile
>: phone to USB port. How it does:
>: 
>: ucom0: <CURITEL Incorporated CURITEL HX-550C USB Modem, class 2/0, rev
>: 1.10/0.00, addr 2> on uhub1
>: Fatal trap 12: page fault while in kernel mode cpuid = 0; apic id = 00
>: fault virtual address = 0x4
>: fault code = supervisor read, page not present
>: instruction pointer = 0x20: 0xc06ca396
>: stack pointer = 0x28: 0xdd30a760
>: frame pointer = 0x28: 0xdd30a760
>: code segment = base 0x0, limit 0xfffff, type = 0x1b, DPL 0, pres 1,
>:              = def32 1, gran 1
>: processor eflags = interrupt enabled, resume; IOPL = 0
>: current process = 28 (usb1)
>: [thread pid 28 tid 100023]
>: Stopped at usb_get_interface_descruptor+0x6: movl 0x4(%eax), %eax
>
>This looks like a null modem dereference.  Which driver is causing
>this?
>
>Warner

It's umodem.