kernel crash in fault.c

[Nandakumar NarayanaSwamy]

Hi All,
I am getting a kernel crash when i try to load (using insmod) my
driver module into the kernel.
When the kernel boots up, it identifies my device (hardware
device) and allocates memory and fixup irq for that.
Mean while in driver i am registering the driver using,
pci_register_driver. When i tried to access (write a word) the 
PCI
memory space allocated for my device, the kernel crashes saying
"Unable to handle kernel paging request at virtual address "
in fault.c function : do_page_fault?

Can anyone throw a light on this?

Thanks in advance,
Nanda.