drivers/gpu/drm/i915/selftests/i915_buddy.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: MIT
 /*
  * Copyright © 2019 Intel Corporation
  */

 #include <linux/prime_numbers.h>

 #include "../i915_selftest.h"
 #include "i915_random.h"

 #define SZ_8G (1ULL << 33)

 static void __igt_dump_block(struct i915_buddy_mm *mm,
 			     struct i915_buddy_block *block,
 			     bool buddy)
 {
 	pr_err("block info: header=%llx, state=%u, order=%d, offset=%llx size=%llx root=%s buddy=%s\n",
 	       block->header,
 	       i915_buddy_block_state(block),
 	       i915_buddy_block_order(block),
 	       i915_buddy_block_offset(block),
 	       i915_buddy_block_size(mm, block),
 	       yesno(!block->parent),
 	       yesno(buddy));
 }

 static void igt_dump_block(struct i915_buddy_mm *mm,
 			   struct i915_buddy_block *block)
 {
 	struct i915_buddy_block *buddy;

 	__igt_dump_block(mm, block, false);

 	buddy = get_buddy(block);
 	if (buddy)
 		__igt_dump_block(mm, buddy, true);
 }

 static int igt_check_block(struct i915_buddy_mm *mm,
 			   struct i915_buddy_block *block)
 {
 	struct i915_buddy_block *buddy;
 	unsigned int block_state;
 	u64 block_size;
 	u64 offset;
 	int err = 0;

 	block_state = i915_buddy_block_state(block);

 	if (block_state != I915_BUDDY_ALLOCATED &&
 	    block_state != I915_BUDDY_FREE &&
 	    block_state != I915_BUDDY_SPLIT) {
 		pr_err("block state mismatch\n");
 		err = -EINVAL;
 	}

 	block_size = i915_buddy_block_size(mm, block);
 	offset = i915_buddy_block_offset(block);

 	if (block_size < mm->chunk_size) {
 		pr_err("block size smaller than min size\n");
 		err = -EINVAL;
 	}

 	if (!is_power_of_2(block_size)) {
 		pr_err("block size not power of two\n");
 		err = -EINVAL;
 	}

 	if (!IS_ALIGNED(block_size, mm->chunk_size)) {
 		pr_err("block size not aligned to min size\n");
 		err = -EINVAL;
 	}

 	if (!IS_ALIGNED(offset, mm->chunk_size)) {
 		pr_err("block offset not aligned to min size\n");
 		err = -EINVAL;
 	}

 	if (!IS_ALIGNED(offset, block_size)) {
 		pr_err("block offset not aligned to block size\n");
 		err = -EINVAL;
 	}

 	buddy = get_buddy(block);

 	if (!buddy && block->parent) {
 		pr_err("buddy has gone fishing\n");
 		err = -EINVAL;
 	}

 	if (buddy) {
 		if (i915_buddy_block_offset(buddy) != (offset ^ block_size)) {
 			pr_err("buddy has wrong offset\n");
 			err = -EINVAL;
 		}

 		if (i915_buddy_block_size(mm, buddy) != block_size) {
 			pr_err("buddy size mismatch\n");
 			err = -EINVAL;
 		}

 		if (i915_buddy_block_state(buddy) == block_state &&
 		    block_state == I915_BUDDY_FREE) {
 			pr_err("block and its buddy are free\n");
 			err = -EINVAL;
 		}
 	}

 	return err;
 }

 static int igt_check_blocks(struct i915_buddy_mm *mm,
 			    struct list_head *blocks,
 			    u64 expected_size,
 			    bool is_contiguous)
 {
 	struct i915_buddy_block *block;
 	struct i915_buddy_block *prev;
 	u64 total;
 	int err = 0;

 	block = NULL;
 	prev = NULL;
 	total = 0;

 	list_for_each_entry(block, blocks, link) {
 		err = igt_check_block(mm, block);

 		if (!i915_buddy_block_is_allocated(block)) {
 			pr_err("block not allocated\n"),
 			err = -EINVAL;
 		}

 		if (is_contiguous && prev) {
 			u64 prev_block_size;
 			u64 prev_offset;
 			u64 offset;

 			prev_offset = i915_buddy_block_offset(prev);
 			prev_block_size = i915_buddy_block_size(mm, prev);
 			offset = i915_buddy_block_offset(block);

 			if (offset != (prev_offset + prev_block_size)) {
 				pr_err("block offset mismatch\n");
 				err = -EINVAL;
 			}
 		}

 		if (err)
 			break;

 		total += i915_buddy_block_size(mm, block);
 		prev = block;
 	}

 	if (!err) {
 		if (total != expected_size) {
 			pr_err("size mismatch, expected=%llx, found=%llx\n",
 			       expected_size, total);
 			err = -EINVAL;
 		}
 		return err;
 	}

 	if (prev) {
 		pr_err("prev block, dump:\n");
 		igt_dump_block(mm, prev);
 	}

 	if (block) {
 		pr_err("bad block, dump:\n");
 		igt_dump_block(mm, block);
 	}

 	return err;
 }

 static int igt_check_mm(struct i915_buddy_mm *mm)
 {
 	struct i915_buddy_block *root;
 	struct i915_buddy_block *prev;
 	unsigned int i;
 	u64 total;
 	int err = 0;

 	if (!mm->n_roots) {
 		pr_err("n_roots is zero\n");
 		return -EINVAL;
 	}

 	if (mm->n_roots != hweight64(mm->size)) {
 		pr_err("n_roots mismatch, n_roots=%u, expected=%lu\n",
 		       mm->n_roots, hweight64(mm->size));
 		return -EINVAL;
 	}

 	root = NULL;
 	prev = NULL;
 	total = 0;

 	for (i = 0; i < mm->n_roots; ++i) {
 		struct i915_buddy_block *block;
 		unsigned int order;

 		root = mm->roots[i];
 		if (!root) {
 			pr_err("root(%u) is NULL\n", i);
 			err = -EINVAL;
 			break;
 		}

 		err = igt_check_block(mm, root);

 		if (!i915_buddy_block_is_free(root)) {
 			pr_err("root not free\n");
 			err = -EINVAL;
 		}

 		order = i915_buddy_block_order(root);

 		if (!i) {
 			if (order != mm->max_order) {
 				pr_err("max order root missing\n");
 				err = -EINVAL;
 			}
 		}

 		if (prev) {
 			u64 prev_block_size;
 			u64 prev_offset;
 			u64 offset;

 			prev_offset = i915_buddy_block_offset(prev);
 			prev_block_size = i915_buddy_block_size(mm, prev);
 			offset = i915_buddy_block_offset(root);

 			if (offset != (prev_offset + prev_block_size)) {
 				pr_err("root offset mismatch\n");
 				err = -EINVAL;
 			}
 		}

 		block = list_first_entry_or_null(&mm->free_list[order],
 						 struct i915_buddy_block,
 						 link);
 		if (block != root) {
 			pr_err("root mismatch at order=%u\n", order);
 			err = -EINVAL;
 		}

 		if (err)
 			break;

 		prev = root;
 		total += i915_buddy_block_size(mm, root);
 	}

 	if (!err) {
 		if (total != mm->size) {
 			pr_err("expected mm size=%llx, found=%llx\n", mm->size,
 			       total);
 			err = -EINVAL;
 		}
 		return err;
 	}

 	if (prev) {
 		pr_err("prev root(%u), dump:\n", i - 1);
 		igt_dump_block(mm, prev);
 	}

 	if (root) {
 		pr_err("bad root(%u), dump:\n", i);
 		igt_dump_block(mm, root);
 	}

 	return err;
 }

 static void igt_mm_config(u64 *size, u64 *chunk_size)
 {
 	I915_RND_STATE(prng);
 	u64 s, ms;

 	/* Nothing fancy, just try to get an interesting bit pattern */

 	prandom_seed_state(&prng, i915_selftest.random_seed);

 	s = i915_prandom_u64_state(&prng) & (SZ_8G - 1);
 	ms = BIT_ULL(12 + (prandom_u32_state(&prng) % ilog2(s >> 12)));
 	s = max(s & -ms, ms);

 	*chunk_size = ms;
 	*size = s;
 }

 static int igt_buddy_alloc_smoke(void *arg)
 {
 	struct i915_buddy_mm mm;
 	int max_order;
 	u64 chunk_size;
 	u64 mm_size;
 	int err;

 	igt_mm_config(&mm_size, &chunk_size);

 	pr_info("buddy_init with size=%llx, chunk_size=%llx\n", mm_size, chunk_size);

 	err = i915_buddy_init(&mm, mm_size, chunk_size);
 	if (err) {
 		pr_err("buddy_init failed(%d)\n", err);
 		return err;
 	}

 	for (max_order = mm.max_order; max_order >= 0; max_order--) {
 		struct i915_buddy_block *block;
 		int order;
 		LIST_HEAD(blocks);
 		u64 total;

 		err = igt_check_mm(&mm);
 		if (err) {
 			pr_err("pre-mm check failed, abort\n");
 			break;
 		}

 		pr_info("filling from max_order=%u\n", max_order);

 		order = max_order;
 		total = 0;

 		do {
 retry:
 			block = i915_buddy_alloc(&mm, order);
 			if (IS_ERR(block)) {
 				err = PTR_ERR(block);
 				if (err == -ENOMEM) {
 					pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
 						order);
 				} else {
 					if (order--) {
 						err = 0;
 						goto retry;
 					}

 					pr_err("buddy_alloc with order=%d failed(%d)\n",
 					       order, err);
 				}

 				break;
 			}

 			list_add_tail(&block->link, &blocks);

 			if (i915_buddy_block_order(block) != order) {
 				pr_err("buddy_alloc order mismatch\n");
 				err = -EINVAL;
 				break;
 			}

 			total += i915_buddy_block_size(&mm, block);
 		} while (total < mm.size);

 		if (!err)
 			err = igt_check_blocks(&mm, &blocks, total, false);

 		i915_buddy_free_list(&mm, &blocks);

 		if (!err) {
 			err = igt_check_mm(&mm);
 			if (err)
 				pr_err("post-mm check failed\n");
 		}

 		if (err)
 			break;
 	}

 	if (err == -ENOMEM)
 		err = 0;

 	i915_buddy_fini(&mm);

 	return err;
 }

 static int igt_buddy_alloc_pessimistic(void *arg)
 {
 	const unsigned int max_order = 16;
 	struct i915_buddy_block *block, *bn;
 	struct i915_buddy_mm mm;
 	unsigned int order;
 	LIST_HEAD(blocks);
 	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.
 	 */

 	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
 	if (err) {
 		pr_err("buddy_init failed(%d)\n", err);
 		return err;
 	}
 	GEM_BUG_ON(mm.max_order != max_order);

 	for (order = 0; order < max_order; order++) {
 		block = i915_buddy_alloc(&mm, order);
 		if (IS_ERR(block)) {
 			pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
 				order);
 			err = PTR_ERR(block);
 			goto err;
 		}

 		list_add_tail(&block->link, &blocks);
 	}

 	/* And now the last remaining block available */
 	block = i915_buddy_alloc(&mm, 0);
 	if (IS_ERR(block)) {
 		pr_info("buddy_alloc hit -ENOMEM on final alloc\n");
 		err = PTR_ERR(block);
 		goto err;
 	}
 	list_add_tail(&block->link, &blocks);

 	/* Should be completely full! */
 	for (order = max_order; order--; ) {
 		block = i915_buddy_alloc(&mm, order);
 		if (!IS_ERR(block)) {
 			pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
 				order);
 			list_add_tail(&block->link, &blocks);
 			err = -EINVAL;
 			goto err;
 		}
 	}

 	block = list_last_entry(&blocks, typeof(*block), link);
 	list_del(&block->link);
 	i915_buddy_free(&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);
 		i915_buddy_free(&mm, block);

 		block = i915_buddy_alloc(&mm, order);
 		if (IS_ERR(block)) {
 			pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
 				order);
 			err = PTR_ERR(block);
 			goto err;
 		}
 		i915_buddy_free(&mm, block);
 		order++;
 	}

 	/* To confirm, now the whole mm should be available */
 	block = i915_buddy_alloc(&mm, max_order);
 	if (IS_ERR(block)) {
 		pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
 			max_order);
 		err = PTR_ERR(block);
 		goto err;
 	}
 	i915_buddy_free(&mm, block);

 err:
 	i915_buddy_free_list(&mm, &blocks);
 	i915_buddy_fini(&mm);
 	return err;
 }

 static int igt_buddy_alloc_optimistic(void *arg)
 {
 	const int max_order = 16;
 	struct i915_buddy_block *block;
 	struct i915_buddy_mm mm;
 	LIST_HEAD(blocks);
 	int order;
 	int err;

 	/*
 	 * Create a mm with one block of each order available, and
 	 * try to allocate them all.
 	 */

 	err = i915_buddy_init(&mm,
 			      PAGE_SIZE * ((1 << (max_order + 1)) - 1),
 			      PAGE_SIZE);
 	if (err) {
 		pr_err("buddy_init failed(%d)\n", err);
 		return err;
 	}
 	GEM_BUG_ON(mm.max_order != max_order);

 	for (order = 0; order <= max_order; order++) {
 		block = i915_buddy_alloc(&mm, order);
 		if (IS_ERR(block)) {
 			pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
 				order);
 			err = PTR_ERR(block);
 			goto err;
 		}

 		list_add_tail(&block->link, &blocks);
 	}

 	/* Should be completely full! */
 	block = i915_buddy_alloc(&mm, 0);
 	if (!IS_ERR(block)) {
 		pr_info("buddy_alloc unexpectedly succeeded, it should be full!");
 		list_add_tail(&block->link, &blocks);
 		err = -EINVAL;
 		goto err;
 	}

 err:
 	i915_buddy_free_list(&mm, &blocks);
 	i915_buddy_fini(&mm);
 	return err;
 }

 static int igt_buddy_alloc_pathological(void *arg)
 {
 	const int max_order = 16;
 	struct i915_buddy_block *block;
 	struct i915_buddy_mm mm;
 	LIST_HEAD(blocks);
 	LIST_HEAD(holes);
 	int order, top;
 	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. Free the largest block, then whittle down again.
 	 * Eventually we will have a fully 50% fragmented mm.
 	 */

 	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
 	if (err) {
 		pr_err("buddy_init failed(%d)\n", err);
 		return err;
 	}
 	GEM_BUG_ON(mm.max_order != max_order);

 	for (top = max_order; top; top--) {
 		/* Make room by freeing the largest allocated block */
 		block = list_first_entry_or_null(&blocks, typeof(*block), link);
 		if (block) {
 			list_del(&block->link);
 			i915_buddy_free(&mm, block);
 		}

 		for (order = top; order--; ) {
 			block = i915_buddy_alloc(&mm, order);
 			if (IS_ERR(block)) {
 				pr_info("buddy_alloc hit -ENOMEM with order=%d, top=%d\n",
 					order, top);
 				err = PTR_ERR(block);
 				goto err;
 			}
 			list_add_tail(&block->link, &blocks);
 		}

 		/* There should be one final page for this sub-allocation */
 		block = i915_buddy_alloc(&mm, 0);
 		if (IS_ERR(block)) {
 			pr_info("buddy_alloc hit -ENOMEM for hole\n");
 			err = PTR_ERR(block);
 			goto err;
 		}
 		list_add_tail(&block->link, &holes);

 		block = i915_buddy_alloc(&mm, top);
 		if (!IS_ERR(block)) {
 			pr_info("buddy_alloc unexpectedly succeeded at top-order %d/%d, it should be full!",
 				top, max_order);
 			list_add_tail(&block->link, &blocks);
 			err = -EINVAL;
 			goto err;
 		}
 	}

 	i915_buddy_free_list(&mm, &holes);

 	/* Nothing larger than blocks of chunk_size now available */
 	for (order = 1; order <= max_order; order++) {
 		block = i915_buddy_alloc(&mm, order);
 		if (!IS_ERR(block)) {
 			pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
 				order);
 			list_add_tail(&block->link, &blocks);
 			err = -EINVAL;
 			goto err;
 		}
 	}

 err:
 	list_splice_tail(&holes, &blocks);
 	i915_buddy_free_list(&mm, &blocks);
 	i915_buddy_fini(&mm);
 	return err;
 }

 static int igt_buddy_alloc_range(void *arg)
 {
 	struct i915_buddy_mm mm;
 	unsigned long page_num;
 	LIST_HEAD(blocks);
 	u64 chunk_size;
 	u64 offset;
 	u64 size;
 	u64 rem;
 	int err;

 	igt_mm_config(&size, &chunk_size);

 	pr_info("buddy_init with size=%llx, chunk_size=%llx\n", size, chunk_size);

 	err = i915_buddy_init(&mm, size, chunk_size);
 	if (err) {
 		pr_err("buddy_init failed(%d)\n", err);
 		return err;
 	}

 	err = igt_check_mm(&mm);
 	if (err) {
 		pr_err("pre-mm check failed, abort, abort, abort!\n");
 		goto err_fini;
 	}

 	rem = mm.size;
 	offset = 0;

 	for_each_prime_number_from(page_num, 1, ULONG_MAX - 1) {
 		struct i915_buddy_block *block;
 		LIST_HEAD(tmp);

 		size = min(page_num * mm.chunk_size, rem);

 		err = i915_buddy_alloc_range(&mm, &tmp, offset, size);
 		if (err) {
 			if (err == -ENOMEM) {
 				pr_info("alloc_range hit -ENOMEM with size=%llx\n",
 					size);
 			} else {
 				pr_err("alloc_range with offset=%llx, size=%llx failed(%d)\n",
 				       offset, size, err);
 			}

 			break;
 		}

 		block = list_first_entry_or_null(&tmp,
 						 struct i915_buddy_block,
 						 link);
 		if (!block) {
 			pr_err("alloc_range has no blocks\n");
 			err = -EINVAL;
 			break;
 		}

 		if (i915_buddy_block_offset(block) != offset) {
 			pr_err("alloc_range start offset mismatch, found=%llx, expected=%llx\n",
 			       i915_buddy_block_offset(block), offset);
 			err = -EINVAL;
 		}

 		if (!err)
 			err = igt_check_blocks(&mm, &tmp, size, true);

 		list_splice_tail(&tmp, &blocks);

 		if (err)
 			break;

 		offset += size;

 		rem -= size;
 		if (!rem)
 			break;
 	}

 	if (err == -ENOMEM)
 		err = 0;

 	i915_buddy_free_list(&mm, &blocks);

 	if (!err) {
 		err = igt_check_mm(&mm);
 		if (err)
 			pr_err("post-mm check failed\n");
 	}

 err_fini:
 	i915_buddy_fini(&mm);

 	return err;
 }

 int i915_buddy_mock_selftests(void)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_buddy_alloc_pessimistic),
 		SUBTEST(igt_buddy_alloc_optimistic),
 		SUBTEST(igt_buddy_alloc_pathological),
 		SUBTEST(igt_buddy_alloc_smoke),
 		SUBTEST(igt_buddy_alloc_range),
 	};

 	return i915_subtests(tests, NULL);
 }
	// SPDX-License-Identifier: MIT
	/*
	* Copyright © 2019 Intel Corporation
	*/

	#include <linux/prime_numbers.h>

	#include "../i915_selftest.h"
	#include "i915_random.h"

	#define SZ_8G (1ULL << 33)

	static void __igt_dump_block(struct i915_buddy_mm *mm,
	struct i915_buddy_block *block,
	bool buddy)
	{
	pr_err("block info: header=%llx, state=%u, order=%d, offset=%llx size=%llx root=%s buddy=%s\n",
	block->header,
	i915_buddy_block_state(block),
	i915_buddy_block_order(block),
	i915_buddy_block_offset(block),
	i915_buddy_block_size(mm, block),
	yesno(!block->parent),
	yesno(buddy));
	}

	static void igt_dump_block(struct i915_buddy_mm *mm,
	struct i915_buddy_block *block)
	{
	struct i915_buddy_block *buddy;

	__igt_dump_block(mm, block, false);

	buddy = get_buddy(block);
	if (buddy)
	__igt_dump_block(mm, buddy, true);
	}

	static int igt_check_block(struct i915_buddy_mm *mm,
	struct i915_buddy_block *block)
	{
	struct i915_buddy_block *buddy;
	unsigned int block_state;
	u64 block_size;
	u64 offset;
	int err = 0;

	block_state = i915_buddy_block_state(block);

	if (block_state != I915_BUDDY_ALLOCATED &&
	block_state != I915_BUDDY_FREE &&
	block_state != I915_BUDDY_SPLIT) {
	pr_err("block state mismatch\n");
	err = -EINVAL;
	}

	block_size = i915_buddy_block_size(mm, block);
	offset = i915_buddy_block_offset(block);

	if (block_size < mm->chunk_size) {
	pr_err("block size smaller than min size\n");
	err = -EINVAL;
	}

	if (!is_power_of_2(block_size)) {
	pr_err("block size not power of two\n");
	err = -EINVAL;
	}

	if (!IS_ALIGNED(block_size, mm->chunk_size)) {
	pr_err("block size not aligned to min size\n");
	err = -EINVAL;
	}

	if (!IS_ALIGNED(offset, mm->chunk_size)) {
	pr_err("block offset not aligned to min size\n");
	err = -EINVAL;
	}

	if (!IS_ALIGNED(offset, block_size)) {
	pr_err("block offset not aligned to block size\n");
	err = -EINVAL;
	}

	buddy = get_buddy(block);

	if (!buddy && block->parent) {
	pr_err("buddy has gone fishing\n");
	err = -EINVAL;
	}

	if (buddy) {
	if (i915_buddy_block_offset(buddy) != (offset ^ block_size)) {
	pr_err("buddy has wrong offset\n");
	err = -EINVAL;
	}

	if (i915_buddy_block_size(mm, buddy) != block_size) {
	pr_err("buddy size mismatch\n");
	err = -EINVAL;
	}

	if (i915_buddy_block_state(buddy) == block_state &&
	block_state == I915_BUDDY_FREE) {
	pr_err("block and its buddy are free\n");
	err = -EINVAL;
	}
	}

	return err;
	}

	static int igt_check_blocks(struct i915_buddy_mm *mm,
	struct list_head *blocks,
	u64 expected_size,
	bool is_contiguous)
	{
	struct i915_buddy_block *block;
	struct i915_buddy_block *prev;
	u64 total;
	int err = 0;

	block = NULL;
	prev = NULL;
	total = 0;

	list_for_each_entry(block, blocks, link) {
	err = igt_check_block(mm, block);

	if (!i915_buddy_block_is_allocated(block)) {
	pr_err("block not allocated\n"),
	err = -EINVAL;
	}

	if (is_contiguous && prev) {
	u64 prev_block_size;
	u64 prev_offset;
	u64 offset;

	prev_offset = i915_buddy_block_offset(prev);
	prev_block_size = i915_buddy_block_size(mm, prev);
	offset = i915_buddy_block_offset(block);

	if (offset != (prev_offset + prev_block_size)) {
	pr_err("block offset mismatch\n");
	err = -EINVAL;
	}
	}

	if (err)
	break;

	total += i915_buddy_block_size(mm, block);
	prev = block;
	}

	if (!err) {
	if (total != expected_size) {
	pr_err("size mismatch, expected=%llx, found=%llx\n",
	expected_size, total);
	err = -EINVAL;
	}
	return err;
	}

	if (prev) {
	pr_err("prev block, dump:\n");
	igt_dump_block(mm, prev);
	}

	if (block) {
	pr_err("bad block, dump:\n");
	igt_dump_block(mm, block);
	}

	return err;
	}

	static int igt_check_mm(struct i915_buddy_mm *mm)
	{
	struct i915_buddy_block *root;
	struct i915_buddy_block *prev;
	unsigned int i;
	u64 total;
	int err = 0;

	if (!mm->n_roots) {
	pr_err("n_roots is zero\n");
	return -EINVAL;
	}

	if (mm->n_roots != hweight64(mm->size)) {
	pr_err("n_roots mismatch, n_roots=%u, expected=%lu\n",
	mm->n_roots, hweight64(mm->size));
	return -EINVAL;
	}

	root = NULL;
	prev = NULL;
	total = 0;

	for (i = 0; i < mm->n_roots; ++i) {
	struct i915_buddy_block *block;
	unsigned int order;

	root = mm->roots[i];
	if (!root) {
	pr_err("root(%u) is NULL\n", i);
	err = -EINVAL;
	break;
	}

	err = igt_check_block(mm, root);

	if (!i915_buddy_block_is_free(root)) {
	pr_err("root not free\n");
	err = -EINVAL;
	}

	order = i915_buddy_block_order(root);

	if (!i) {
	if (order != mm->max_order) {
	pr_err("max order root missing\n");
	err = -EINVAL;
	}
	}

	if (prev) {
	u64 prev_block_size;
	u64 prev_offset;
	u64 offset;

	prev_offset = i915_buddy_block_offset(prev);
	prev_block_size = i915_buddy_block_size(mm, prev);
	offset = i915_buddy_block_offset(root);

	if (offset != (prev_offset + prev_block_size)) {
	pr_err("root offset mismatch\n");
	err = -EINVAL;
	}
	}

	block = list_first_entry_or_null(&mm->free_list[order],
	struct i915_buddy_block,
	link);
	if (block != root) {
	pr_err("root mismatch at order=%u\n", order);
	err = -EINVAL;
	}

	if (err)
	break;

	prev = root;
	total += i915_buddy_block_size(mm, root);
	}

	if (!err) {
	if (total != mm->size) {
	pr_err("expected mm size=%llx, found=%llx\n", mm->size,
	total);
	err = -EINVAL;
	}
	return err;
	}

	if (prev) {
	pr_err("prev root(%u), dump:\n", i - 1);
	igt_dump_block(mm, prev);
	}

	if (root) {
	pr_err("bad root(%u), dump:\n", i);
	igt_dump_block(mm, root);
	}

	return err;
	}

	static void igt_mm_config(u64 size, u64 chunk_size)
	{
	I915_RND_STATE(prng);
	u64 s, ms;

	/* Nothing fancy, just try to get an interesting bit pattern */

	prandom_seed_state(&prng, i915_selftest.random_seed);

	s = i915_prandom_u64_state(&prng) & (SZ_8G - 1);
	ms = BIT_ULL(12 + (prandom_u32_state(&prng) % ilog2(s >> 12)));
	s = max(s & -ms, ms);

	*chunk_size = ms;
	*size = s;
	}

	static int igt_buddy_alloc_smoke(void *arg)
	{
	struct i915_buddy_mm mm;
	int max_order;
	u64 chunk_size;
	u64 mm_size;
	int err;

	igt_mm_config(&mm_size, &chunk_size);

	pr_info("buddy_init with size=%llx, chunk_size=%llx\n", mm_size, chunk_size);

	err = i915_buddy_init(&mm, mm_size, chunk_size);
	if (err) {
	pr_err("buddy_init failed(%d)\n", err);
	return err;
	}

	for (max_order = mm.max_order; max_order >= 0; max_order--) {
	struct i915_buddy_block *block;
	int order;
	LIST_HEAD(blocks);
	u64 total;

	err = igt_check_mm(&mm);
	if (err) {
	pr_err("pre-mm check failed, abort\n");
	break;
	}

	pr_info("filling from max_order=%u\n", max_order);

	order = max_order;
	total = 0;

	do {
	retry:
	block = i915_buddy_alloc(&mm, order);
	if (IS_ERR(block)) {
	err = PTR_ERR(block);
	if (err == -ENOMEM) {
	pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
	order);
	} else {
	if (order--) {
	err = 0;
	goto retry;
	}

	pr_err("buddy_alloc with order=%d failed(%d)\n",
	order, err);
	}

	break;
	}

	list_add_tail(&block->link, &blocks);

	if (i915_buddy_block_order(block) != order) {
	pr_err("buddy_alloc order mismatch\n");
	err = -EINVAL;
	break;
	}

	total += i915_buddy_block_size(&mm, block);
	} while (total < mm.size);

	if (!err)
	err = igt_check_blocks(&mm, &blocks, total, false);

	i915_buddy_free_list(&mm, &blocks);

	if (!err) {
	err = igt_check_mm(&mm);
	if (err)
	pr_err("post-mm check failed\n");
	}

	if (err)
	break;
	}

	if (err == -ENOMEM)
	err = 0;

	i915_buddy_fini(&mm);

	return err;
	}

	static int igt_buddy_alloc_pessimistic(void *arg)
	{
	const unsigned int max_order = 16;
	struct i915_buddy_block block, bn;
	struct i915_buddy_mm mm;
	unsigned int order;
	LIST_HEAD(blocks);
	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.
	*/

	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
	if (err) {
	pr_err("buddy_init failed(%d)\n", err);
	return err;
	}
	GEM_BUG_ON(mm.max_order != max_order);

	for (order = 0; order < max_order; order++) {
	block = i915_buddy_alloc(&mm, order);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
	order);
	err = PTR_ERR(block);
	goto err;
	}

	list_add_tail(&block->link, &blocks);
	}

	/* And now the last remaining block available */
	block = i915_buddy_alloc(&mm, 0);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc hit -ENOMEM on final alloc\n");
	err = PTR_ERR(block);
	goto err;
	}
	list_add_tail(&block->link, &blocks);

	/* Should be completely full! */
	for (order = max_order; order--; ) {
	block = i915_buddy_alloc(&mm, order);
	if (!IS_ERR(block)) {
	pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
	order);
	list_add_tail(&block->link, &blocks);
	err = -EINVAL;
	goto err;
	}
	}

	block = list_last_entry(&blocks, typeof(*block), link);
	list_del(&block->link);
	i915_buddy_free(&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);
	i915_buddy_free(&mm, block);

	block = i915_buddy_alloc(&mm, order);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
	order);
	err = PTR_ERR(block);
	goto err;
	}
	i915_buddy_free(&mm, block);
	order++;
	}

	/* To confirm, now the whole mm should be available */
	block = i915_buddy_alloc(&mm, max_order);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
	max_order);
	err = PTR_ERR(block);
	goto err;
	}
	i915_buddy_free(&mm, block);

	err:
	i915_buddy_free_list(&mm, &blocks);
	i915_buddy_fini(&mm);
	return err;
	}

	static int igt_buddy_alloc_optimistic(void *arg)
	{
	const int max_order = 16;
	struct i915_buddy_block *block;
	struct i915_buddy_mm mm;
	LIST_HEAD(blocks);
	int order;
	int err;

	/*
	* Create a mm with one block of each order available, and
	* try to allocate them all.
	*/

	err = i915_buddy_init(&mm,
	PAGE_SIZE * ((1 << (max_order + 1)) - 1),
	PAGE_SIZE);
	if (err) {
	pr_err("buddy_init failed(%d)\n", err);
	return err;
	}
	GEM_BUG_ON(mm.max_order != max_order);

	for (order = 0; order <= max_order; order++) {
	block = i915_buddy_alloc(&mm, order);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
	order);
	err = PTR_ERR(block);
	goto err;
	}

	list_add_tail(&block->link, &blocks);
	}

	/* Should be completely full! */
	block = i915_buddy_alloc(&mm, 0);
	if (!IS_ERR(block)) {
	pr_info("buddy_alloc unexpectedly succeeded, it should be full!");
	list_add_tail(&block->link, &blocks);
	err = -EINVAL;
	goto err;
	}

	err:
	i915_buddy_free_list(&mm, &blocks);
	i915_buddy_fini(&mm);
	return err;
	}

	static int igt_buddy_alloc_pathological(void *arg)
	{
	const int max_order = 16;
	struct i915_buddy_block *block;
	struct i915_buddy_mm mm;
	LIST_HEAD(blocks);
	LIST_HEAD(holes);
	int order, top;
	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. Free the largest block, then whittle down again.
	* Eventually we will have a fully 50% fragmented mm.
	*/

	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
	if (err) {
	pr_err("buddy_init failed(%d)\n", err);
	return err;
	}
	GEM_BUG_ON(mm.max_order != max_order);

	for (top = max_order; top; top--) {
	/* Make room by freeing the largest allocated block */
	block = list_first_entry_or_null(&blocks, typeof(*block), link);
	if (block) {
	list_del(&block->link);
	i915_buddy_free(&mm, block);
	}

	for (order = top; order--; ) {
	block = i915_buddy_alloc(&mm, order);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc hit -ENOMEM with order=%d, top=%d\n",
	order, top);
	err = PTR_ERR(block);
	goto err;
	}
	list_add_tail(&block->link, &blocks);
	}

	/* There should be one final page for this sub-allocation */
	block = i915_buddy_alloc(&mm, 0);
	if (IS_ERR(block)) {
	pr_info("buddy_alloc hit -ENOMEM for hole\n");
	err = PTR_ERR(block);
	goto err;
	}
	list_add_tail(&block->link, &holes);

	block = i915_buddy_alloc(&mm, top);
	if (!IS_ERR(block)) {
	pr_info("buddy_alloc unexpectedly succeeded at top-order %d/%d, it should be full!",
	top, max_order);
	list_add_tail(&block->link, &blocks);
	err = -EINVAL;
	goto err;
	}
	}

	i915_buddy_free_list(&mm, &holes);

	/* Nothing larger than blocks of chunk_size now available */
	for (order = 1; order <= max_order; order++) {
	block = i915_buddy_alloc(&mm, order);
	if (!IS_ERR(block)) {
	pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
	order);
	list_add_tail(&block->link, &blocks);
	err = -EINVAL;
	goto err;
	}
	}

	err:
	list_splice_tail(&holes, &blocks);
	i915_buddy_free_list(&mm, &blocks);
	i915_buddy_fini(&mm);
	return err;
	}

	static int igt_buddy_alloc_range(void *arg)
	{
	struct i915_buddy_mm mm;
	unsigned long page_num;
	LIST_HEAD(blocks);
	u64 chunk_size;
	u64 offset;
	u64 size;
	u64 rem;
	int err;

	igt_mm_config(&size, &chunk_size);

	pr_info("buddy_init with size=%llx, chunk_size=%llx\n", size, chunk_size);

	err = i915_buddy_init(&mm, size, chunk_size);
	if (err) {
	pr_err("buddy_init failed(%d)\n", err);
	return err;
	}

	err = igt_check_mm(&mm);
	if (err) {
	pr_err("pre-mm check failed, abort, abort, abort!\n");
	goto err_fini;
	}

	rem = mm.size;
	offset = 0;

	for_each_prime_number_from(page_num, 1, ULONG_MAX - 1) {
	struct i915_buddy_block *block;
	LIST_HEAD(tmp);

	size = min(page_num * mm.chunk_size, rem);

	err = i915_buddy_alloc_range(&mm, &tmp, offset, size);
	if (err) {
	if (err == -ENOMEM) {
	pr_info("alloc_range hit -ENOMEM with size=%llx\n",
	size);
	} else {
	pr_err("alloc_range with offset=%llx, size=%llx failed(%d)\n",
	offset, size, err);
	}

	break;
	}

	block = list_first_entry_or_null(&tmp,
	struct i915_buddy_block,
	link);
	if (!block) {
	pr_err("alloc_range has no blocks\n");
	err = -EINVAL;
	break;
	}

	if (i915_buddy_block_offset(block) != offset) {
	pr_err("alloc_range start offset mismatch, found=%llx, expected=%llx\n",
	i915_buddy_block_offset(block), offset);
	err = -EINVAL;
	}

	if (!err)
	err = igt_check_blocks(&mm, &tmp, size, true);

	list_splice_tail(&tmp, &blocks);

	if (err)
	break;

	offset += size;

	rem -= size;
	if (!rem)
	break;
	}

	if (err == -ENOMEM)
	err = 0;

	i915_buddy_free_list(&mm, &blocks);

	if (!err) {
	err = igt_check_mm(&mm);
	if (err)
	pr_err("post-mm check failed\n");
	}

	err_fini:
	i915_buddy_fini(&mm);

	return err;
	}

	int i915_buddy_mock_selftests(void)
	{
	static const struct i915_subtest tests[] = {
	SUBTEST(igt_buddy_alloc_pessimistic),
	SUBTEST(igt_buddy_alloc_optimistic),
	SUBTEST(igt_buddy_alloc_pathological),
	SUBTEST(igt_buddy_alloc_smoke),
	SUBTEST(igt_buddy_alloc_range),
	};

	return i915_subtests(tests, NULL);
	}