Re: [PATCH 5/7] drm/selftests: add drm buddy pessimistic testcase

[Matthew Auld <matthew.auld@intel.com>]

On 03/02/2022 13:32, Arunpravin wrote:
> create a pot-sized mm, then allocate one of each possible
> order within. This should leave the mm with exactly one
> page left.
> 
> Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
> ---
>   .../gpu/drm/selftests/drm_buddy_selftests.h   |   1 +
>   drivers/gpu/drm/selftests/test-drm_buddy.c    | 153 ++++++++++++++++++
>   2 files changed, 154 insertions(+)
> 
> diff --git a/drivers/gpu/drm/selftests/drm_buddy_selftests.h b/drivers/gpu/drm/selftests/drm_buddy_selftests.h
> index 21a6bd38864f..b14f04a1de19 100644
> --- a/drivers/gpu/drm/selftests/drm_buddy_selftests.h
> +++ b/drivers/gpu/drm/selftests/drm_buddy_selftests.h
> @@ -10,3 +10,4 @@ selftest(sanitycheck, igt_sanitycheck) /* keep first (selfcheck for igt) */
>   selftest(buddy_alloc_limit, igt_buddy_alloc_limit)
>   selftest(buddy_alloc_range, igt_buddy_alloc_range)
>   selftest(buddy_alloc_optimistic, igt_buddy_alloc_optimistic)
> +selftest(buddy_alloc_pessimistic, igt_buddy_alloc_pessimistic)
> diff --git a/drivers/gpu/drm/selftests/test-drm_buddy.c b/drivers/gpu/drm/selftests/test-drm_buddy.c
> index b193d9556fb4..e97f583ed0cd 100644
> --- a/drivers/gpu/drm/selftests/test-drm_buddy.c
> +++ b/drivers/gpu/drm/selftests/test-drm_buddy.c
> @@ -314,6 +314,159 @@ static void igt_mm_config(u64 *size, u64 *chunk_size)
>   	*size = (u64)s << 12;
>   }
>   
> +static int igt_buddy_alloc_pessimistic(void *arg)
> +{
> +	u64 mm_size, size, min_page_size, start = 0;
> +	struct drm_buddy_block *block, *bn;
> +	const unsigned int max_order = 16;
> +	unsigned long flags = 0;
> +	struct drm_buddy mm;
> +	unsigned int order;
> +	LIST_HEAD(blocks);
> +	LIST_HEAD(tmp);
> +	int err;
> +
> +	/*
> +	 * Create a pot-sized mm, then allocate one of each possible
> +	 * order within. This should leave the mm with exactly one
> +	 * page left.
> +	 */
> +
> +	mm_size = PAGE_SIZE << max_order;
> +	err = drm_buddy_init(&mm, mm_size, PAGE_SIZE);
> +	if (err) {
> +		pr_err("buddy_init failed(%d)\n", err);
> +		return err;
> +	}
> +	BUG_ON(mm.max_order != max_order);
> +
> +	for (order = 0; order < max_order; order++) {
> +		size = min_page_size = get_size(order, PAGE_SIZE);
> +		err = drm_buddy_alloc_blocks(&mm, start, mm_size, size, min_page_size, &tmp, flags);
> +		if (err) {
> +			pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
> +				order);
> +			goto err;
> +		}
> +
> +		block = list_first_entry_or_null(&tmp,
> +						 struct drm_buddy_block,
> +						 link);
> +		if (!block) {
> +			pr_err("alloc_blocks has no blocks\n");
> +			err = -EINVAL;
> +			goto err;
> +		}
> +
> +		list_del(&block->link);
> +		list_add_tail(&block->link, &blocks);
> +	}
> +
> +	/* And now the last remaining block available */
> +	size = min_page_size = get_size(0, PAGE_SIZE);
> +	err = drm_buddy_alloc_blocks(&mm, start, mm_size, size, min_page_size, &tmp, flags);
> +	if (err) {
> +		pr_info("buddy_alloc hit -ENOMEM on final alloc\n");
> +		goto err;
> +	}
> +
> +	block = list_first_entry_or_null(&tmp,
> +					 struct drm_buddy_block,
> +					 link);
> +	if (!block) {
> +		pr_err("alloc_blocks has no blocks\n");
> +		err = -EINVAL;
> +		goto err;
> +	}
> +
> +	list_del(&block->link);
> +	list_add_tail(&block->link, &blocks);
> +
> +	/* Should be completely full! */
> +	for (order = max_order; order--; ) {
> +		size = min_page_size = get_size(order, PAGE_SIZE);
> +		err = drm_buddy_alloc_blocks(&mm, start, mm_size, size, min_page_size, &tmp, flags);
> +		if (!err) {
> +			pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
> +				order);
> +			block = list_first_entry_or_null(&tmp,
> +							 struct drm_buddy_block,
> +							 link);
> +			if (!block) {
> +				pr_err("alloc_blocks has no blocks\n");
> +				err = -EINVAL;
> +				goto err;
> +			}
> +
> +			list_del(&block->link);
> +			list_add_tail(&block->link, &blocks);
> +			err = -EINVAL;
> +			goto err;
> +		}
> +	}
> +
> +	block = list_last_entry(&blocks, typeof(*block), link);
> +	list_del(&block->link);
> +	drm_buddy_free_block(&mm, block);
> +
> +	/* As we free in increasing size, we make available larger blocks */
> +	order = 1;
> +	list_for_each_entry_safe(block, bn, &blocks, link) {
> +		list_del(&block->link);
> +		drm_buddy_free_block(&mm, block);
> +
> +		size = min_page_size = get_size(order, PAGE_SIZE);
> +		err = drm_buddy_alloc_blocks(&mm, start, mm_size, size, min_page_size, &tmp, flags);
> +		if (err) {
> +			pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
> +				order);
> +			goto err;
> +		}
> +
> +		block = list_first_entry_or_null(&tmp,
> +						 struct drm_buddy_block,
> +						 link);
> +		if (!block) {
> +			pr_err("alloc_blocks has no blocks\n");
> +			err = -EINVAL;
> +			goto err;
> +		}
> +
> +		list_del(&block->link);
> +		drm_buddy_free_block(&mm, block);
> +		order++;
> +	}
> +
> +	/* To confirm, now the whole mm should be available */
> +	size = min_page_size = get_size(max_order, PAGE_SIZE);
> +	err = drm_buddy_alloc_blocks(&mm, start, mm_size, size, min_page_size, &tmp, flags);
> +	if (err) {
> +		pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
> +			max_order);
> +		goto err;
> +	}
> +
> +	block = list_first_entry_or_null(&tmp,
> +					 struct drm_buddy_block,
> +					 link);
> +	if (!block) {
> +		pr_err("alloc_blocks has no blocks\n");
> +		err = -EINVAL;
> +		goto err;
> +	}
> +
> +	list_del(&block->link);
> +	drm_buddy_free_block(&mm, block);
> +
> +	if (!err)

Always true?

Reviewed-by: Matthew Auld <matthew.auld@intel.com>

> +		pr_info("%s - succeeded\n", __func__);
> +
> +err:
> +	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_fini(&mm);
> +	return err;
> +}
> +
>   static int igt_buddy_alloc_optimistic(void *arg)
>   {
>   	u64 mm_size, size, min_page_size, start = 0;