[1/2] drm/buddy: fix issue that force_merge cannot free all roots

Commit Message

Paneer Selvam, Arunpravin Dec. 16, 2024, 1:07 p.m. UTC

From: Lin.Cao <[e-mail]>

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 <[e-mail]>
---
 drivers/gpu/drm/drm_buddy.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Matthew Auld Dec. 16, 2024, 6:35 p.m. UTC | #1

On 16/12/2024 13:07, Arunpravin Paneer Selvam wrote:
> From: Lin.Cao <[e-mail]>
> 
> 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 <[e-mail]>

Reviewed-by: Matthew Auld <[e-mail]>

Patch

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 103c185bb1c8..ca42e6081d27 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -324,7 +324,7 @@  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;
 
@@ -332,7 +332,8 @@  void drm_buddy_fini(struct drm_buddy *mm)
 
 	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]);