[PATCH v4 0/5] Add reclaim to the dmem cgroup controller

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

When writing a "max" limit lower than the current usage, the
existing code silently failed. This series aims to improve
on that by returning -EBUSY on failure and also attempt
to synchronously reclaim device memory to push the usage
under the new max limit to avoid the error.

Patch 1 fixes a pre-existing amdgpu_vram_mgr_init() error path
Patch 2 implements and documents a reclaim callback interface
      for the dmem controller.
Patch 3 implements a TTM reclaim callback.
Patch 4-5 hooks up the reclaim callback to the dmem cgroups-
      aware drivers xe and amdgpu.

v2:
- Remove the error propagation that was in a previous series (Maarten)
- A number of updates in patch 1. See its commit message for
  details (Maarten)

v3:
- Add patch 1 fixing a pre-existing amdgpu_vram_mgr_init() error path
  bug where drmm_cgroup_register_region() was called before
  INIT_LIST_HEAD() and gpu_buddy_init(), causing a kernel panic on
  failure. (Sashiko-bot)
- Use an rwsem to protect reclaim callback registration and region
  unregister against concurrent reclaim invocations. (Sashiko-bot)
- Fix ttm_resource_manager_set_dmem_region() storing an error pointer
  in man->cg unconditionally. (Sashiko-bot)
- Fix kernel-doc function name format for ttm_bo_evict_cgroup() and
  ttm_resource_manager_set_dmem_region().

v4:
- Rebased on drm-tip; dropped the XE_PL_STOLEN guard in the xe patch
  as stolen memory uses a separate TTM manager.

User-space tests are at
https://patchwork.freedesktop.org/series/163935/

Test-with: 20260428065411.4222-1-thomas.hellstrom@linux.intel.com

Thomas Hellström (5):
  drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init()
  cgroup/dmem: Add reclaim callback for lowering max below current usage
  drm/ttm: Hook up a cgroup-aware reclaim callback for the dmem
    controller
  drm/xe: Wire up dmem cgroup reclaim for VRAM manager
  drm/amdgpu: Wire up dmem cgroup reclaim for VRAM manager

 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c      |   2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c |  10 +-
 drivers/gpu/drm/ttm/ttm_bo.c                 |  95 ++++++++++++++++-
 drivers/gpu/drm/ttm/ttm_bo_util.c            |   3 +-
 drivers/gpu/drm/ttm/ttm_resource.c           |  37 +++++++
 drivers/gpu/drm/xe/xe_ttm_vram_mgr.c         |  14 ++-
 include/drm/ttm/ttm_bo.h                     |  10 ++
 include/drm/ttm/ttm_resource.h               |   4 +
 include/linux/cgroup_dmem.h                  |  24 +++++
 kernel/cgroup/dmem.c                         | 106 +++++++++++++++++--
 10 files changed, 283 insertions(+), 22 deletions(-)

-- 
2.54.0