Commit dc2fc00b authored Jan 21, 2026 by Sanjay Yadav Committed by Matthew Auld Jan 22, 2026

drm/xe: Use DRM_BUDDY_CONTIGUOUS_ALLOCATION for contiguous allocations

The VRAM/stolen memory managers do not currently set
DRM_BUDDY_CONTIGUOUS_ALLOCATION for contiguous allocations. Enabling
this flag activates the buddy allocator's try_harder path, which helps
handle fragmented memory scenarios.

This enables the __alloc_contig_try_harder fallback in the buddy
allocator, allowing contiguous allocation requests to succeed even when
memory is fragmented by combining allocations from both(RHS and LHS)
sides of a large free block.

v2: (Matt B)
- Remove redundant logic for rounding allocation size and trimming when
  TTM_PL_FLAG_CONTIGUOUS is set, since drm_buddy now handles this when
  DRM_BUDDY_CONTIGUOUS_ALLOCATION is enabled

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6713


Suggested-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Sanjay Yadav <sanjay.kumar.yadav@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20260121111416.3104399-2-sanjay.kumar.yadav@intel.com

parent 9386f493

drivers/gpu/drm/xe/xe_ttm_vram_mgr.c

+3 −13

Original line number	Diff line number	Diff line
		@@ -81,6 +81,9 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
		if (place->flags & TTM_PL_FLAG_TOPDOWN)
		vres->flags \|= DRM_BUDDY_TOPDOWN_ALLOCATION;

		if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
		vres->flags \|= DRM_BUDDY_CONTIGUOUS_ALLOCATION;

		if (place->fpfn \|\| lpfn != man->size >> PAGE_SHIFT)
		vres->flags \|= DRM_BUDDY_RANGE_ALLOCATION;

		@@ -110,25 +113,12 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
		goto error_unlock;
		}

		if (place->fpfn + (size >> PAGE_SHIFT) != lpfn &&
		place->flags & TTM_PL_FLAG_CONTIGUOUS) {
		size = roundup_pow_of_two(size);
		min_page_size = size;

		lpfn = max_t(unsigned long, place->fpfn + (size >> PAGE_SHIFT), lpfn);
		}

		err = drm_buddy_alloc_blocks(mm, (u64)place->fpfn << PAGE_SHIFT,
		(u64)lpfn << PAGE_SHIFT, size,
		min_page_size, &vres->blocks, vres->flags);
		if (err)
		goto error_unlock;

		if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
		if (!drm_buddy_block_trim(mm, NULL, vres->base.size, &vres->blocks))
		size = vres->base.size;
		}

		if (lpfn <= mgr->visible_size >> PAGE_SHIFT) {
		vres->used_visible_size = size;
		} else {