[PATCH v9 0/6] TTM shrinker helpers and xe buffer object shrinker

[Thomas Hellström]

This series implements TTM shrinker / eviction helpers and an xe bo
shrinker. It builds on a previous series, *and obsoletes that one*.

https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/

Where the comment about layering
https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/#ma918844aa8a6efe8768fdcda0c6590d5c93850c9

now addressed, and this version also implements shmem objects for backup
rather than direct swap-cache insertions, which was used in the previuos
series. It turns out that with per-page backup / shrinking, shmem objects
appears to work just as well as direct swap-cache insertions with the
added benefit that was introduced in the previous TTM shrinker series to
avoid running out of swap entries isn't really needed.

The series earlier consisted of a LRU traversal part and the current part.
The LRU traversal part is merged, but is still mentioned in the history
below.

Patch 1 could in theory be skipped but introduces a possibility to easily
add or test multiple backup backends, like the direct swap-cache
insertion or even files into fast dedicated nvme storage for for example.

Patch 2 introduces helpers in the ttm_pool code for page-by-page shrinking
and recovery. It avoids having to temporarily allocate a huge amount of
memory to be able to shrink a buffer object. It also introduces the
possibility to immediately write-back pages if needed, since that tends
to be a bit delayed when left to kswapd.

Patch 3 Adds a simple error injection to the above code to help increase
test coverage.

Patch 4 Implements a shrinker helper in TTM, and exports the LRU walker.

Patch 5 Implements the xe bo shrinker.

Patch 6 Increases (removes) the XE_PL_TT watermark.

v2:
- Squash obsolete revision history in the patch commit messages.
- Fix a couple of review comments by Christian
- Don't store the mem_type in the TTM managers but in the
  resource cursor.
- Rename introduced TTM *back_up* function names to *backup*
- Add ttm pool recovery fault injection.
- Shrinker xe kunit test
- Various bugfixes

v3:
- Address some review comments from Matthew Brost and Christian König.
- Use the restartable LRU walk for TTM swapping and eviction.
- Provide a POC drm_exec locking implementation for exhaustive
  eviction. (Christian König).

v4:
- Remove the RFC exhaustive eviction part. While the path to exhaustive
  eviction is pretty clear and demonstrated in v3, there is still some
  drm_exec work that needs to be agreed and implemented.
- Add shrinker power management. On some hw we need to wake when shrinking.
- Fix the lru walker helper for -EALREADY errors.
- Add drm/xe: Increase the XE_PL_TT watermark.

v5:
- Update also TTM kunit tests
- Handle ghost- and zombie objects in the shrinker.
- A couple of compile- and UAF fixes reported by Kernel Build Robot and
  Dan Carpenter.

v6:
- Address review comments from Matthew Brost on the
  restartable LRU traversal path.

v7:
- Split out TTM restartable LRU traversal path and merge that.
- Adapt the review comments on that seires.

v8:
- Address review comments from Matthew Brost as detailed in the
  respective patches.

v9:
- Rebase and fix compilation errors

Cc: Somalapuram Amaranath <Amaranath.Somalapuram at amd.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Cc: <dri-devel at lists.freedesktop.org>

Thomas Hellström (6):
  drm/ttm: Add a virtual base class for graphics memory backup
  drm/ttm/pool: Provide a helper to shrink pages
  drm/ttm: Use fault-injection to test error paths
  drm/ttm: Add a shrinker helper and export the LRU walker for driver
    use
  drm/xe: Add a shrinker for xe bos
  drm/xe: Increase the XE_PL_TT watermark

 drivers/gpu/drm/ttm/Makefile           |   2 +-
 drivers/gpu/drm/ttm/ttm_backup_shmem.c | 139 ++++++++
 drivers/gpu/drm/ttm/ttm_bo_util.c      |  65 ++++
 drivers/gpu/drm/ttm/ttm_pool.c         | 419 ++++++++++++++++++++++++-
 drivers/gpu/drm/ttm/ttm_tt.c           |  37 +++
 drivers/gpu/drm/xe/Makefile            |   1 +
 drivers/gpu/drm/xe/tests/xe_bo.c       | 224 +++++++++++++
 drivers/gpu/drm/xe/xe_bo.c             | 166 +++++++++-
 drivers/gpu/drm/xe/xe_bo.h             |  36 +++
 drivers/gpu/drm/xe/xe_device.c         |   8 +
 drivers/gpu/drm/xe/xe_device_types.h   |   2 +
 drivers/gpu/drm/xe/xe_shrinker.c       | 289 +++++++++++++++++
 drivers/gpu/drm/xe/xe_shrinker.h       |  18 ++
 drivers/gpu/drm/xe/xe_ttm_sys_mgr.c    |   3 +-
 include/drm/ttm/ttm_backup.h           | 137 ++++++++
 include/drm/ttm/ttm_bo.h               |  17 +
 include/drm/ttm/ttm_pool.h             |   6 +
 include/drm/ttm/ttm_tt.h               |  30 ++
 18 files changed, 1567 insertions(+), 32 deletions(-)
 create mode 100644 drivers/gpu/drm/ttm/ttm_backup_shmem.c
 create mode 100644 drivers/gpu/drm/xe/xe_shrinker.c
 create mode 100644 drivers/gpu/drm/xe/xe_shrinker.h
 create mode 100644 include/drm/ttm/ttm_backup.h

-- 
2.44.0