[$] Revisiting the kernel's preemption models (part 1)

All that Ankur Arora seemingly wanted to do with this
patch set was to make the process of clearing huge pages on x86
systems go a little faster. What resulted was an extensive discussion on
the difficulties of managing preemption correctly in the kernel. It may be
that some changes will come to the plethora of preemption models that the
kernel currently offers.