Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Introduce and use a new VM interface for temporarily pinning pages. This
new interface replaces the combined use of vm_fault_quick() and
pmap_extract_and_hold() throughout the kernel.

In collaboration with: kib@

Push down the acquisition of the page queues lock into vm_page_unwire().

Add page locking to the vm_page_cow* functions.

Push down the acquisition and release of the page queues lock into
vm_page_wire().

Reviewed by: kib

Acquire the page lock around vm_page_unwire(). For consistency, extend the
scope of the object lock in agp_i810.c. (In this specific case, the scope
of the object lock shouldn't matter, but I don't want to create a bad
example that might be copied to a case where it did matter.)

Reviewed by: kib

On Alan's advice, rather than do a wholesale conversion on a single
architecture from page queue lock to a hashed array of page locks
(based on a patch by Jeff Roberson), I've implemented page lock
support in the MI code and have only moved vm_page's hold_count
out from under page queue mutex to page lock. This changes
pmap_extract_and_hold on all pmaps.

Supported by: Bitgravity Inc.

Discussed with: alc, jeffr, and kib

Welcome drm support for VIA unichrome chips.

MFC after: 2 weeks