Extend the scoreboard approach from the previous commit to used blocks, so drm_buddy_print() can report per-order allocation pressure in O(1).
Unlike free blocks, an allocated block can leave the allocated state through mark_free() (normal free and gpu_buddy_block_trim()) or be consumed directly by gpu_block_free() during coalescing. Both sites are guarded by gpu_buddy_block_is_allocated() and paired with the increment in mark_allocated(). v2: - Update after fix for use-after-free in split_block() call sites - Change goto label to out_free_used_scoreboard for clarity - Make drm_buddy_print() and gpu_buddy_print() symmetric for used and free Signed-off-by: Francois Dugast <[email protected]> Assisted-by: GitHub Copilot:claude-sonnet-4.6 --- drivers/gpu/buddy.c | 39 +++++++++++++++++++++++++++---------- drivers/gpu/drm/drm_buddy.c | 18 +++++++++++------ include/linux/gpu_buddy.h | 8 ++++++++ 3 files changed, 49 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c index de18b63fef0a..f81d0d8fde15 100644 --- a/drivers/gpu/buddy.c +++ b/drivers/gpu/buddy.c @@ -194,6 +194,7 @@ static void mark_allocated(struct gpu_buddy *mm, block->header |= GPU_BUDDY_ALLOCATED; mm->free_scoreboard[gpu_buddy_block_order(block)]--; + mm->used_scoreboard[gpu_buddy_block_order(block)]++; rbtree_remove(mm, block); } @@ -203,6 +204,9 @@ static void mark_free(struct gpu_buddy *mm, { enum gpu_buddy_free_tree tree; + if (gpu_buddy_block_is_allocated(block)) + mm->used_scoreboard[gpu_buddy_block_order(block)]--; + block->header &= ~GPU_BUDDY_HEADER_STATE; block->header |= GPU_BUDDY_FREE; @@ -281,6 +285,9 @@ static unsigned int __gpu_buddy_free(struct gpu_buddy *mm, if (force_merge && gpu_buddy_block_is_clear(buddy)) mm->clear_avail -= gpu_buddy_block_size(mm, buddy); + if (gpu_buddy_block_is_allocated(block)) + mm->used_scoreboard[gpu_buddy_block_order(block)]--; + gpu_block_free(mm, block); gpu_block_free(mm, buddy); @@ -398,11 +405,17 @@ int gpu_buddy_init(struct gpu_buddy *mm, u64 size, u64 chunk_size) if (!mm->free_scoreboard) return -ENOMEM; + mm->used_scoreboard = kcalloc(mm->max_order + 1, + sizeof(*mm->used_scoreboard), + GFP_KERNEL); + if (!mm->used_scoreboard) + goto out_free_free_scoreboard; + mm->free_trees = kmalloc_array(GPU_BUDDY_MAX_FREE_TREES, sizeof(*mm->free_trees), GFP_KERNEL); if (!mm->free_trees) - goto out_free_scoreboard; + goto out_free_used_scoreboard; for_each_free_tree(i) { mm->free_trees[i] = kmalloc_array(mm->max_order + 1, @@ -464,7 +477,9 @@ int gpu_buddy_init(struct gpu_buddy *mm, u64 size, u64 chunk_size) while (i--) kfree(mm->free_trees[i]); kfree(mm->free_trees); -out_free_scoreboard: +out_free_used_scoreboard: + kfree(mm->used_scoreboard); +out_free_free_scoreboard: kfree(mm->free_scoreboard); return -ENOMEM; } @@ -505,6 +520,7 @@ void gpu_buddy_fini(struct gpu_buddy *mm) kfree(mm->free_trees); kfree(mm->roots); kfree(mm->free_scoreboard); + kfree(mm->used_scoreboard); } EXPORT_SYMBOL(gpu_buddy_fini); @@ -1505,15 +1521,18 @@ void gpu_buddy_print(struct gpu_buddy *mm) mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20); for (order = mm->max_order; order >= 0; order--) { - u64 count = mm->free_scoreboard[order]; - u64 free = count * (mm->chunk_size << order); - - if (free < SZ_1M) - pr_info("order-%2d free: %8llu KiB, blocks: %llu\n", - order, free >> 10, count); + u64 free_count = mm->free_scoreboard[order]; + u64 used_count = mm->used_scoreboard[order]; + u64 block_size = mm->chunk_size << order; + u64 free = free_count * block_size; + u64 used = used_count * block_size; + + if (block_size < SZ_1M) + pr_info("order-%2d free: %8llu KiB, used: %8llu KiB, free_blocks: %llu, used_blocks: %llu\n", + order, free >> 10, used >> 10, free_count, used_count); else - pr_info("order-%2d free: %8llu MiB, blocks: %llu\n", - order, free >> 20, count); + pr_info("order-%2d free: %8llu MiB, used: %8llu MiB, free_blocks: %llu, used_blocks: %llu\n", + order, free >> 20, used >> 20, free_count, used_count); } } EXPORT_SYMBOL(gpu_buddy_print); diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index eef995e08a37..1536e59c6fe7 100644 --- a/drivers/gpu/drm/drm_buddy.c +++ b/drivers/gpu/drm/drm_buddy.c @@ -47,17 +47,23 @@ void drm_buddy_print(struct gpu_buddy *mm, struct drm_printer *p) mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20); for (order = mm->max_order; order >= 0; order--) { - u64 count = mm->free_scoreboard[order]; - u64 free = count * (mm->chunk_size << order); + u64 free_count = mm->free_scoreboard[order]; + u64 used_count = mm->used_scoreboard[order]; + u64 block_size = mm->chunk_size << order; + u64 free = free_count * block_size; + u64 used = used_count * block_size; drm_printf(p, "order-%2d ", order); - if (free < SZ_1M) - drm_printf(p, "free: %8llu KiB", free >> 10); + if (block_size < SZ_1M) + drm_printf(p, "free: %8llu KiB, used: %8llu KiB", + free >> 10, used >> 10); else - drm_printf(p, "free: %8llu MiB", free >> 20); + drm_printf(p, "free: %8llu MiB, used: %8llu MiB", + free >> 20, used >> 20); - drm_printf(p, ", blocks: %llu\n", count); + drm_printf(p, ", free_blocks: %llu, used_blocks: %llu\n", + free_count, used_count); } } EXPORT_SYMBOL(drm_buddy_print); diff --git a/include/linux/gpu_buddy.h b/include/linux/gpu_buddy.h index a28f7d7637ca..e037714563d8 100644 --- a/include/linux/gpu_buddy.h +++ b/include/linux/gpu_buddy.h @@ -180,6 +180,14 @@ struct gpu_buddy { * called on a free block. */ u64 *free_scoreboard; + /* + * Per-order used block scoreboard: used_scoreboard[order] holds the + * number of blocks of that order currently in the allocated state. + * Incremented in mark_allocated(), decremented in mark_free() (guarded + * by gpu_buddy_block_is_allocated()) and in __gpu_buddy_free() when an + * allocated block is consumed directly during buddy coalescing. + */ + u64 *used_scoreboard; /* public: */ unsigned int n_roots; unsigned int max_order; -- 2.43.0
