drm/buddy: fix issue that force_merge cannot free all roots

[ Upstream commit 467dce3 ]

If buddy manager have more than one roots and each root have sub-block
need to be free. When drm_buddy_fini called, the first loop of
force_merge will merge and free all of the sub block of first root,
which offset is 0x0 and size is biggest(more than have of the mm size).
In subsequent force_merge rounds, if we use 0 as start and use remaining
mm size as end, the block of other roots will be skipped in
__force_merge function. It will cause the other roots can not be freed.

Solution: use roots' offset as the start could fix this issue.

Signed-off-by: Lin.Cao <lincao12@amd.com>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241226070116.309290-1-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit aa52c70ae1322430da509e5ee98f817f2dcae2ed)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>

Author: Lin.Cao

drivers/gpu/drm/drm_buddy.c

@@ -324,15 +324,16 @@ EXPORT_SYMBOL(drm_buddy_init);
  */
 void drm_buddy_fini(struct drm_buddy *mm)
 {
-	u64 root_size, size;
+	u64 root_size, size, start;
 	unsigned int order;
 	int i;
 
 	size = mm->size;
 
 	for (i = 0; i < mm->n_roots; ++i) {
 		order = ilog2(size) - ilog2(mm->chunk_size);
-		__force_merge(mm, 0, size, order);
+		start = drm_buddy_block_offset(mm->roots[i]);
+		__force_merge(mm, start, start + size, order);
 
 		WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
 		drm_block_free(mm, mm->roots[i]);