>uvm_fault_wire can be used to wire the pages and you can then use 
anything
>to access the memory and even use it in a an interrupt context.
>(uvm_fault_unwire removes the wiring)
>Once the page is wired you no longer have to worry about page faults.
>However wiring/unwiring is a relative expensive function.

>kcopy/copyin/copyout can be used without first wiring the pages because
>of their internal exception handling.
>( However these functions can not be used from interrupt context)

Wouldn't you want to provide a pageable_malloc() inside the kernel?
Its a really useful interface to have [for those who are naive].

regards
-kamal