On contiguous allocation, we round up the size to the *next* power of 2, implement a function to free the unused pages after the newly allocate block.
v2(Matthew Auld): - replace function name 'drm_buddy_free_unused_pages' with drm_buddy_block_trim - replace input argument name 'actual_size' with 'new_size' - add more validation checks for input arguments - add overlaps check to avoid needless searching and splitting - merged the below patch to see the feature in action - add free unused pages support to i915 driver - lock drm_buddy_block_trim() function as it calls mark_free/mark_split are all globally visible
v3(Matthew Auld): - remove trim method error handling as we address the failure case at drm_buddy_block_trim() function
v4: - in case of trim, at __alloc_range() split_block failure path marks the block as free and removes it from the original list, potentially also freeing it, to overcome this problem, we turn the drm_buddy_block_trim() input node into a temporary node to prevent recursively freeing itself, but still retain the un-splitting/freeing of the other nodes(Matthew Auld)
- modify the drm_buddy_block_trim() function return type
v5(Matthew Auld): - revert drm_buddy_block_trim() function return type changes in v4 - modify drm_buddy_block_trim() passing argument n_pages to original_size as n_pages has already been rounded up to the next power-of-two and passing n_pages results noop
v6: - fix warnings reported by kernel test robot lkp@intel.com
v7: - modify drm_buddy_block_trim() function doc description - at drm_buddy_block_trim() handle non-allocated block as a serious programmer error - fix a typo
Signed-off-by: Arunpravin Arunpravin.PaneerSelvam@amd.com Reviewed-by: Matthew Auld matthew.auld@intel.com --- drivers/gpu/drm/drm_buddy.c | 69 +++++++++++++++++++ drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 10 +++ include/drm/drm_buddy.h | 4 ++ 3 files changed, 83 insertions(+)
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index 30cad939a112..4845ef784b5e 100644 --- a/drivers/gpu/drm/drm_buddy.c +++ b/drivers/gpu/drm/drm_buddy.c @@ -542,6 +542,75 @@ static int __drm_buddy_alloc_range(struct drm_buddy *mm, return __alloc_range(mm, &dfs, start, size, blocks); }
+/** + * drm_buddy_block_trim - free unused pages + * + * @mm: DRM buddy manager + * @new_size: original size requested + * @blocks: Input and output list of allocated blocks. + * MUST contain single block as input to be trimmed. + * On success will contain the newly allocated blocks + * making up the @new_size. Blocks always appear in + * ascending order + * + * For contiguous allocation, we round up the size to the nearest + * power of two value, drivers consume *actual* size, so remaining + * portions are unused and can be optionally freed with this function + * + * Returns: + * 0 on success, error code on failure. + */ +int drm_buddy_block_trim(struct drm_buddy *mm, + u64 new_size, + struct list_head *blocks) +{ + struct drm_buddy_block *parent; + struct drm_buddy_block *block; + LIST_HEAD(dfs); + u64 new_start; + int err; + + if (!list_is_singular(blocks)) + return -EINVAL; + + block = list_first_entry(blocks, + struct drm_buddy_block, + link); + + if (WARN_ON(!drm_buddy_block_is_allocated(block))) + return -EINVAL; + + if (new_size > drm_buddy_block_size(mm, block)) + return -EINVAL; + + if (!new_size || !IS_ALIGNED(new_size, mm->chunk_size)) + return -EINVAL; + + if (new_size == drm_buddy_block_size(mm, block)) + return 0; + + list_del(&block->link); + mark_free(mm, block); + mm->avail += drm_buddy_block_size(mm, block); + + /* Prevent recursively freeing this node */ + parent = block->parent; + block->parent = NULL; + + new_start = drm_buddy_block_offset(block); + list_add(&block->tmp_link, &dfs); + err = __alloc_range(mm, &dfs, new_start, new_size, blocks); + if (err) { + mark_allocated(block); + mm->avail -= drm_buddy_block_size(mm, block); + list_add(&block->link, blocks); + } + + block->parent = parent; + return err; +} +EXPORT_SYMBOL(drm_buddy_block_trim); + /** * drm_buddy_alloc_blocks - allocate power-of-two blocks * diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c index 45b091626278..b52684552523 100644 --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c @@ -97,6 +97,16 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man, if (unlikely(err)) goto err_free_blocks;
+ if (place->flags & TTM_PL_FLAG_CONTIGUOUS) { + u64 original_size = (u64)bman_res->base.num_pages << PAGE_SHIFT; + + mutex_lock(&bman->lock); + drm_buddy_block_trim(mm, + original_size, + &bman_res->blocks); + mutex_unlock(&bman->lock); + } + *res = &bman_res->base; return 0;
diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h index f0378fb48d06..bd21f9dfd15e 100644 --- a/include/drm/drm_buddy.h +++ b/include/drm/drm_buddy.h @@ -140,6 +140,10 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm, struct list_head *blocks, unsigned long flags);
+int drm_buddy_block_trim(struct drm_buddy *mm, + u64 new_size, + struct list_head *blocks); + void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);