Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r259612: ttm_bo_vm_lookup_rb: actually make use of the red-black tree

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Partially revert r254880. The bitmap operations actually use long type now.

drm: Use the new drm_atomic.h, following the merge of projects/atomic64

Submitted by: jkim@

drm/ttm: Fix style in ttm_bo_release_mmap()

drm/ttm: Fix unmap of buffer object

Add a new ttm_bo_release_mmap() function to unmap pages in a
vm_object_t. Pages are freed when the buffer object is later released.

This function is called in ttm_bo_unmap_virtual_locked(), replacing
Linux' unmap_mapping_range(). In particular this is called when a buffer
object is about to be moved, so that its mapping is invalidated.

However, we don't use this function in ttm_bo_vm_dtor(), because the
vm_object_t is already marked as OBJ_DEAD and the pages will be
unmapped.

Approved by: kib@

drm/ttm: Improve comment in ttm_bo_vm_ctor() about lack of ref acquisition

Approved by: kib@

drm/ttm: Make ttm_bo_wait() call uninterruptible in page fault handler

This fixes a crash where a SIGLALRM, heavily used by X.Org, would
interrupt the wait, causing the page fault to fail and the "Xorg"
process to receive a SIGSEGV.

Approved by: kib@

On all the architectures, avoid to preallocate the physical memory
for nodes used in vm_radix.
On architectures supporting direct mapping, also avoid to pre-allocate
the KVA for such nodes.

In order to do so make the operations derived from vm_radix_insert()
to fail and handle all the deriving failure of those.

vm_radix-wise introduce a new function called vm_radix_replace(),
which can replace a leaf node, already present, with a new one,
and take into account the possibility, during vm_radix_insert()
allocation, that the operations on the radix trie can recurse.
This means that if operations in vm_radix_insert() recursed
vm_radix_insert() will start from scratch again.

Sponsored by: EMC / Isilon storage division
Reviewed by: alc (older version)
Reviewed by: jeff
Tested by: pho, scottl

The soft and hard busy mechanism rely on the vm object lock to work.
Unify the 2 concept into a real, minimal, sxlock where the shared
acquisition represent the soft busy and the exclusive acquisition
represent the hard busy.
The old VPO_WANTED mechanism becames the hard-path for this new lock
and it becomes per-page rather than per-object.
The vm_object lock becames an interlock for this functionality:
it can be held in both read or write mode.
However, if the vm_object lock is held in read mode while acquiring
or releasing the busy state, the thread owner cannot make any
assumption on the busy state unless it is also busying it.

Also:
- Add a new flag to directly shared busy pages while vm_page_alloc
and vm_page_grab are being executed. This will be very helpful
once these functions happen under a read object lock.
- Move the swapping sleep into its own per-object flag

The KPI is heavilly changed this is why the version is bumped.
It is very likely that some VM ports users will need to change
their own code.

Sponsored by: EMC / Isilon storage division
Discussed with: alc
Reviewed by: jeff, kib
Tested by: gavin, bapt (older version)
Tested by: pho, scottl

MFgem r251960: re-check the mgt device object for the requested page
after the object was relocked.

Tested by: dumbbell
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Remove unneeded page lock around vm_page_insert().

Submitted by: alc

drm/ttm: Explain why we don't need to acquire a ref in ttm_bo_vm_ctor()

drm/ttm: Fix TTM buffer object refcount

This fixes memory leaks in the radeonkms driver.

Reviewed by: Konstantin Belousov (kib@)
Tested by: J.R. Oldroyd <jr@opal.com>

Switch the vm_object mutex to be a rwlock. This will enable in the
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.

The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
- VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
- VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
- VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
- VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
(in order to avoid visibility of implementation details)
- The read-mode operations are added:
VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
sys/mutex.h in consumers directly to cater its inlining functions
using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
the compat layer because the name clash between FreeBSD and solaris
versions must be avoided.
At this purpose zfs redefines the vm_object locking functions
directly, isolating the FreeBSD components in specific compat stubs.

The KPI results heavilly broken by this commit. Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).

Sponsored by: EMC / Isilon storage division
Reviewed by: jeff
Reviewed by: pjd (ZFS specific review)
Discussed with: alc
Tested by: pho

Import the preliminary port of the TTM.

The early commit is done to facilitate the off-tree work on the
porting of the Radeon driver.

Sponsored by: The FreeBSD Foundation
Debugged and tested by: dumbbell
MFC after: 1 month