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

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

MFC r239065:
Stop including vm_param.h into vm_page.h. Include vm_param.h
explicitely for the kernel code which needs it.

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

Approved by: re (implicit)

Eliminate duplication of the fake page code and zone by the device and sg
pagers.

Reviewed by: jhb

Explicitly initialize the page's queue field to PQ_NONE instead of relying
on PQ_NONE being zero.

Redefine PQ_NONE and PQ_COUNT so that a page queue isn't allocated for
PQ_NONE.

Reviewed by: kib@

Eliminate page queues locking around most calls to vm_page_free().

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

Mark the fake pages constructed by the OBJT_SG pager valid. This was
accidentally lost at one point during the PAT development. Without this
fix vm_pager_get_pages() was zeroing each of the pages.

Submitted by: czander @ NVidia
MFC after: 3 days

Remove debugging that crept in with previous commit.

Reported by: nwhitehorn
Approved by: re (kib)

Add a new type of VM object: OBJT_SG. An OBJT_SG object is very similar to
a device pager (OBJT_DEVICE) object in that it uses fictitious pages to
provide aliases to other memory addresses. The primary difference is that
it uses an sglist(9) to determine the physical addresses for a given offset
into the object instead of invoking the d_mmap() method in a device driver.

Reviewed by: alc
Approved by: re (kensmith)
MFC after: 2 weeks