[PATCH] updated preempt-kernel

[Robert Love]

Testers Wanted:

patches to enable a fully preemptible kernel are available at:
	http://tech9.net/rml/linux
for kernels 2.4.10, 2.4.12, 2.4.12-ac3, and 2.4.13-pre5.

What is this:

A preemptible kernel.  It lowers your latency.

What is New:

* sync with new kernel releases

* if HIGHMEM_DEBUG was on the preempt counter would be incremented at
times but never decremented.  this resulted in preemption becoming
permanently disabled.

* if HIGHMEM_DEBUG was not on, HIGHMEM would crash the system horribly
due to a case where preemption was enabled without a corresponding
disable.

* reapply dropped hunk to pgalloc to prevent reentrancy onto per-CPU
data

The next few patches are going to work on identifying any remaining
per-CPU variables that need explicit locking under preemption.

	Robert Love