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drm: mm: track free areas implicitly

The idea is to track free holes implicitly by marking the allocation
immediatly preceeding a hole.

To avoid an ugly corner case add a dummy head_node to struct drm_mm
to track the hole that spans to complete allocation area when the
memory manager is empty.

To guarantee that there's always a preceeding/following node (that might
be marked as hole_follows == 1), move the mm->node_list list_head to the

The main allocator and fair-lru scan code actually becomes simpler.
Only the debug code slightly suffers because free areas are no longer

Also add drm_mm_for_each_node (which will be much more useful when
struct drm_mm_node is embeddable).

Signed-off-by: Daniel Vetter <>
Signed-off-by: Dave Airlie <>
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1 parent 31a5b8c commit ea7b1dd44867e9cd6bac67e7c9fc3f128b5b255c @danvet danvet committed with Dave Airlie Feb 18, 2011
Showing with 225 additions and 260 deletions.
  1. +213 −251 drivers/gpu/drm/drm_mm.c
  2. +12 −9 include/drm/drm_mm.h
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