linux-kernel - [PATCH AUTOSEL 6.12 483/486] drm/buddy: fix issue that force

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Message-Id: <20250505223922.2682012-483-sashal@kernel.org>
Date: Mon,  5 May 2025 18:39:19 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: "Lin.Cao" <lincao12@....com>,
	Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>,
	Matthew Auld <matthew.auld@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.12 483/486] drm/buddy: fix issue that force_merge cannot free all roots

From: "Lin.Cao" <lincao12@....com>

[ Upstream commit 467dce3817bd2b62ccd6fcfd7aae76f242ac907e ]

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@....com>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>
Reviewed-by: Matthew Auld <matthew.auld@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241226070116.309290-1-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/drm_buddy.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 103c185bb1c8a..ca42e6081d27c 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]);
-- 
2.39.5