It means that you've got a bad pointer in your code.
Exactly the same thing it would mean if you got a "SEGV" in a Linux program, or a GPF in a Windows program. Except that pointer errors in kernel drivers tend to crash your OS on you ;-)
As far as an "EXAMPLE !!!!" - it sounds like you've got one or two good examples right in your code.
As far as what to do about it, I'd recommend both of these books:
Linux Device Drivers, 3rd Ed:
http://www.bookpool.com/sm/0596005903
Linux Kernel Development, 2nd Ed:
http://www.bookpool.com/sm/0672327201
