[PATCH v2] drm: add a check to verify the size alignment

[Arunpravin Paneer Selvam]

Add a simple check to reject any size not aligned to the
min_page_size.

handle instances when size is not aligned with the min_page_size.
Unigine Heaven has allocation requests for example required pages
are 257 and alignment request is 256. To allocate the left over 1
page, continues the iteration to find the order value which is 0
and when it compares with min_order = 8, triggers the BUG_ON(order
< min_order). To avoid this problem, we added a simple check to
return -EINVAL if size is not aligned to the min_page_size.

v2: Added more details to the commit description

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
Suggested-by: Matthew Auld <matthew.auld at intel.com>
---
 drivers/gpu/drm/drm_buddy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 72f52f293249..b503c88786b0 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -661,6 +661,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 	if (range_overflows(start, size, mm->size))
 		return -EINVAL;
 
+	if (WARN_ON(!IS_ALIGNED(size, min_page_size)))
+		return -EINVAL;
+
 	/* Actual range allocation */
 	if (start + size == end)
 		return __drm_buddy_alloc_range(mm, start, size, blocks);

base-commit: 056d47eaf6ea753fa2e21da31f9cbd8b721bbb7b
-- 
2.25.1