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

[Lin.Cao]

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 at amd.com>
---
 drivers/gpu/drm/drm_buddy.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 94f8c34fc293..5379687552bc 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -327,12 +327,14 @@ void drm_buddy_fini(struct drm_buddy *mm)
 	u64 root_size, size;
 	unsigned int order;
 	int i;
+	u64 start = 0;
 
 	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]);
-- 
2.45.2