[Pull Request][Lucid] Fix Xorg hangs with some i915 chipsets

[Seth Forshee]

This is a rather large series of non-trivial backports to fix a Xorg
hang caused by the i915 driver. Patches 5 and 6 are the key patches that
implement an LRU-based eviction algorithm; patches 1-4 are
prerequisites, patch 7 fixes some of the clean-up, and patch 8 adds a
periodic flush to retire active buffers.

This is a pretty severe bug for those affected by it, but it's also a
huge amount of change for a stable kernel, so let me know if it's beyond
hope for an SRU.

SRU Justification:

  Impact: When the GPU aperture becomes sufficiently fragmented two or
  more mmapped buffers in active use can repeatedly push each other out
  of the aperture. This results in a sort of livelock situation, with
  Xorg appearing to be hung with high CPU utilization.

  Fix: Backport of a series of patches that convert the i915 eviction
  algorithm from a best-fit approach to one based on evicting the least
  recently used objects and a patch that adds a periodic flush requests
  to retire active buffers when no client is active.

  Testcase: Without these patches this scenario can be triggered
  ocassionally when visiting certain web pages that utilize Flash or
  viewing certain images in Firefox, as described on bugs #599017 and
  #330460. Testing the same pages/images with these patches does not
  induce the hang.


The following changes since commit 9cc333d02cb4620561e91a63ed86a2159ec32638:

  UBUNTU: Ubuntu-2.6.32-33.67 (2011-06-16 11:26:04 -0500)

are available in the git repository at:
  git://kernel.ubuntu.com/sforshee/ubuntu-lucid.git lp599017

Chris Wilson (5):
      drm/i915: Move the eviction logic to its own file.
      drm/i915: Implement fair lru eviction across both rings.  (v2)
      drm/i915: Maintain LRU order of inactive objects upon access by CPU (v2)
      drm/i915/evict: Ensure we completely cleanup on failure
      drm/i915: Periodically flush the active lists and requests

Daniel Vetter (3):
      drm_mm: extract check_free_mm_node
      drm: implement helper functions for scanning lru list
      drm/i915: prepare for fair lru eviction

 drivers/gpu/drm/drm_mm.c              |  236 +++++++++++++++++++++++++-----
 drivers/gpu/drm/i915/Makefile         |    1 +
 drivers/gpu/drm/i915/i915_drv.h       |   13 ++
 drivers/gpu/drm/i915/i915_gem.c       |  228 ++++-------------------------
 drivers/gpu/drm/i915/i915_gem_evict.c |  253 +++++++++++++++++++++++++++++++++
 include/drm/drm_mm.h                  |   15 ++-
 6 files changed, 510 insertions(+), 236 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/i915_gem_evict.c