There is a corner case here where start/end is after/before the block range we are currently checking. If so we need to be sure that splitting the block will eventually give use the block size we need. To do that we should adjust the block range to account for the start/end, and only continue with the split if the size/alignment will fit the requested size. Not doing so can result in leaving split blocks unmerged when it eventually fails.

Fixes: afea229fe102 ("drm: improve drm_buddy_alloc function") Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Arunpravin Paneer Selvam Arunpravin.PaneerSelvam@amd.com Cc: Christian König christian.koenig@amd.com Cc: stable@vger.kernel.org # v5.18+ --- drivers/gpu/drm/drm_buddy.c | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index c1a99bf4dffd..d09540d4065b 100644 --- a/drivers/gpu/drm/drm_buddy.c +++ b/drivers/gpu/drm/drm_buddy.c @@ -332,6 +332,7 @@ alloc_range_bias(struct drm_buddy *mm, u64 start, u64 end, unsigned int order) { + u64 req_size = mm->chunk_size << order; struct drm_buddy_block *block; struct drm_buddy_block *buddy; LIST_HEAD(dfs); @@ -367,6 +368,15 @@ alloc_range_bias(struct drm_buddy *mm, if (drm_buddy_block_is_allocated(block)) continue;

+ if (block_start < start || block_end > end) { + u64 adjusted_start = max(block_start, start); + u64 adjusted_end = min(block_end, end); + + if (round_down(adjusted_end + 1, req_size) <= + round_up(adjusted_start, req_size)) + continue; + } + if (contains(start, end, block_start, block_end) && order == drm_buddy_block_order(block)) { /*