Re: [PATCH v6 1/6] drm: move the buddy allocator from i915 into common drm

On 26/12/2021 22:24, Arunpravin wrote:

Move the base i915 buddy allocator code into drm

• Move i915_buddy.h to include/drm
• Move i915_buddy.c to drm root folder
• Rename "i915" string with "drm" string wherever applicable
• Rename "I915" string with "DRM" string wherever applicable
• Fix header file dependencies
• Fix alignment issues
• add Makefile support for drm buddy
• export functions and write kerneldoc description
• Remove i915 selftest config check condition as buddy selftest will be moved to drm selftest folder

cleanup i915 buddy references in i915 driver module and replace with drm buddy

v2:

• include header file in alphabetical order(Thomas)
• merged changes listed in the body section into a single patch to keep the build intact(Christian, Jani)

v3:

• make drm buddy a separate module(Thomas, Christian)

v4:

• Fix build error reported by kernel test robot lkp@intel.com
• removed i915 buddy selftest from i915_mock_selftests.h to avoid build error
• removed selftests/i915_buddy.c file as we create a new set of buddy test cases in drm/selftests folder

v5:

• Fix merge conflict issue

Signed-off-by: Arunpravin Arunpravin.PaneerSelvam@amd.com

<snip>

+int drm_buddy_init(struct drm_buddy_mm *mm, u64 size, u64 chunk_size) +{

• unsigned int i;
• u64 offset;
• if (size < chunk_size)

• return -EINVAL;
  

• if (chunk_size < PAGE_SIZE)

• return -EINVAL;
  

• if (!is_power_of_2(chunk_size))

• return -EINVAL;
  

• size = round_down(size, chunk_size);
• mm->size = size;
• mm->avail = size;
• mm->chunk_size = chunk_size;
• mm->max_order = ilog2(size) - ilog2(chunk_size);
• BUG_ON(mm->max_order > DRM_BUDDY_MAX_ORDER);
• mm->slab_blocks = KMEM_CACHE(drm_buddy_block, 0);
• if (!mm->slab_blocks)

• return -ENOMEM;
  

It looks like every KMEM_CACHE() also creates a debugfs entry? See the error here[1]. I guess because we end with multiple instances in i915. If so, is it possible to have a single KMEM_CACHE() as part of the buddy module, similar to what i915 was doing previously?

[1] https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_8217/shard-skl4/igt@i915_sel...