drivers/gpu/drm/tests/drm_buddy_test.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2019 Intel Corporation
 * Copyright © 2022 Maíra Canal <mairacanal@riseup.net>
 */

#include <kunit/test.h>

#include <linux/prime_numbers.h>
#include <linux/sched/signal.h>
#include <linux/sizes.h>

#include <drm/drm_buddy.h>

#include "../lib/drm_random.h"

static inline u64 get_size(int order, u64 chunk_size)
{
	return (1 << order) * chunk_size;
}

static void drm_test_buddy_alloc_contiguous(struct kunit *test)
{
	u64 mm_size, ps = SZ_4K, i, n_pages, total;
	struct drm_buddy_block *block;
	struct drm_buddy mm;
	LIST_HEAD(left);
	LIST_HEAD(middle);
	LIST_HEAD(right);
	LIST_HEAD(allocated);

	mm_size = 16 * 3 * SZ_4K;

	KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, mm_size, ps));

	/*
	 * Idea is to fragment the address space by alternating block
	 * allocations between three different lists; one for left, middle and
	 * right. We can then free a list to simulate fragmentation. In
	 * particular we want to exercise the DRM_BUDDY_CONTIGUOUS_ALLOCATION,
	 * including the try_harder path.
	 */

	i = 0;
	n_pages = mm_size / ps;
	do {
		struct list_head *list;
		int slot = i % 3;

		if (slot == 0)
			list = &left;
		else if (slot == 1)
			list = &middle;
		else
			list = &right;
		KUNIT_ASSERT_FALSE_MSG(test,
				       drm_buddy_alloc_blocks(&mm, 0, mm_size,
							      ps, ps, list, 0),
				       "buddy_alloc hit an error size=%d\n",
				       ps);
	} while (++i < n_pages);

	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							   3 * ps, ps, &allocated,
							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc didn't error size=%d\n", 3 * ps);

	drm_buddy_free_list(&mm, &middle);
	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							   3 * ps, ps, &allocated,
							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc didn't error size=%llu\n", 3 * ps);
	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							   2 * ps, ps, &allocated,
							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc didn't error size=%llu\n", 2 * ps);

	drm_buddy_free_list(&mm, &right);
	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							   3 * ps, ps, &allocated,
							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc didn't error size=%llu\n", 3 * ps);
	/*
	 * At this point we should have enough contiguous space for 2 blocks,
	 * however they are never buddies (since we freed middle and right) so
	 * will require the try_harder logic to find them.
	 */
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							    2 * ps, ps, &allocated,
							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc hit an error size=%d\n", 2 * ps);

	drm_buddy_free_list(&mm, &left);
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
							    3 * ps, ps, &allocated,
							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
			       "buddy_alloc hit an error size=%d\n", 3 * ps);

	total = 0;
	list_for_each_entry(block, &allocated, link)
		total += drm_buddy_block_size(&mm, block);

	KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);

	drm_buddy_free_list(&mm, &allocated);
	drm_buddy_fini(&mm);
}

static void drm_test_buddy_alloc_pathological(struct kunit *test)
{
	u64 mm_size, size, start = 0;
	struct drm_buddy_block *block;
	const int max_order = 3;
	unsigned long flags = 0;
	int order, top;
	struct drm_buddy mm;
	LIST_HEAD(blocks);
	LIST_HEAD(holes);
	LIST_HEAD(tmp);

	/*
	 * 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.
	 */

	mm_size = PAGE_SIZE << max_order;
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_init(&mm, mm_size, PAGE_SIZE),
			       "buddy_init failed\n");

	KUNIT_EXPECT_EQ(test, 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);
			drm_buddy_free_block(&mm, block);
		}

		for (order = top; order--;) {
			size = get_size(order, PAGE_SIZE);
			KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start,
									    mm_size, size, size,
										&tmp, flags),
					"buddy_alloc hit -ENOMEM with order=%d, top=%d\n",
					order, top);

			block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
			KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

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

		/* There should be one final page for this sub-allocation */
		size = get_size(0, PAGE_SIZE);
		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								    size, size, &tmp, flags),
							   "buddy_alloc hit -ENOMEM for hole\n");

		block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
		KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

		list_move_tail(&block->link, &holes);

		size = get_size(top, PAGE_SIZE);
		KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								   size, size, &tmp, flags),
							  "buddy_alloc unexpectedly succeeded at top-order %d/%d, it should be full!",
							  top, max_order);
	}

	drm_buddy_free_list(&mm, &holes);

	/* Nothing larger than blocks of chunk_size now available */
	for (order = 1; order <= max_order; order++) {
		size = get_size(order, PAGE_SIZE);
		KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								   size, size, &tmp, flags),
							  "buddy_alloc unexpectedly succeeded at order %d, it should be full!",
							  order);
	}

	list_splice_tail(&holes, &blocks);
	drm_buddy_free_list(&mm, &blocks);
	drm_buddy_fini(&mm);
}

static void drm_test_buddy_alloc_pessimistic(struct kunit *test)
{
	u64 mm_size, 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);

	/*
	 * 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;
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_init(&mm, mm_size, PAGE_SIZE),
			       "buddy_init failed\n");

	KUNIT_EXPECT_EQ(test, mm.max_order, max_order);

	for (order = 0; order < max_order; order++) {
		size = get_size(order, PAGE_SIZE);
		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								    size, size, &tmp, flags),
							   "buddy_alloc hit -ENOMEM with order=%d\n",
							   order);

		block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
		KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

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

	/* And now the last remaining block available */
	size = get_size(0, PAGE_SIZE);
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
							    size, size, &tmp, flags),
						   "buddy_alloc hit -ENOMEM on final alloc\n");

	block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
	KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

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

	/* Should be completely full! */
	for (order = max_order; order--;) {
		size = get_size(order, PAGE_SIZE);
		KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								   size, size, &tmp, flags),
							  "buddy_alloc unexpectedly succeeded, it should be full!");
	}

	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 = get_size(order, PAGE_SIZE);
		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								    size, size, &tmp, flags),
							   "buddy_alloc hit -ENOMEM with order=%d\n",
							   order);

		block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
		KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

		list_del(&block->link);
		drm_buddy_free_block(&mm, block);
		order++;
	}

	/* To confirm, now the whole mm should be available */
	size = get_size(max_order, PAGE_SIZE);
	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
							    size, size, &tmp, flags),
						   "buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
						   max_order);

	block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
	KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

	list_del(&block->link);
	drm_buddy_free_block(&mm, block);
	drm_buddy_free_list(&mm, &blocks);
	drm_buddy_fini(&mm);
}

static void drm_test_buddy_alloc_optimistic(struct kunit *test)
{
	u64 mm_size, size, start = 0;
	struct drm_buddy_block *block;
	unsigned long flags = 0;
	const int max_order = 16;
	struct drm_buddy mm;
	LIST_HEAD(blocks);
	LIST_HEAD(tmp);
	int order;

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

	mm_size = PAGE_SIZE * ((1 << (max_order + 1)) - 1);

	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_init(&mm, mm_size, PAGE_SIZE),
			       "buddy_init failed\n");

	KUNIT_EXPECT_EQ(test, mm.max_order, max_order);

	for (order = 0; order <= max_order; order++) {
		size = get_size(order, PAGE_SIZE);
		KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
								    size, size, &tmp, flags),
							   "buddy_alloc hit -ENOMEM with order=%d\n",
							   order);

		block = list_first_entry_or_null(&tmp, struct drm_buddy_block, link);
		KUNIT_ASSERT_TRUE_MSG(test, block, "alloc_blocks has no blocks\n");

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

	/* Should be completely full! */
	size = get_size(0, PAGE_SIZE);
	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, start, mm_size,
							   size, size, &tmp, flags),
						  "buddy_alloc unexpectedly succeeded, it should be full!");

	drm_buddy_free_list(&mm, &blocks);
	drm_buddy_fini(&mm);
}

static void drm_test_buddy_alloc_limit(struct kunit *test)
{
	u64 size = U64_MAX, start = 0;
	struct drm_buddy_block *block;
	unsigned long flags = 0;
	LIST_HEAD(allocated);
	struct drm_buddy mm;

	KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, size, PAGE_SIZE));

	KUNIT_EXPECT_EQ_MSG(test, mm.max_order, DRM_BUDDY_MAX_ORDER,
			    "mm.max_order(%d) != %d\n", mm.max_order,
						DRM_BUDDY_MAX_ORDER);

	size = mm.chunk_size << mm.max_order;
	KUNIT_EXPECT_FALSE(test, drm_buddy_alloc_blocks(&mm, start, size, size,
							PAGE_SIZE, &allocated, flags));

	block = list_first_entry_or_null(&allocated, struct drm_buddy_block, link);
	KUNIT_EXPECT_TRUE(test, block);

	KUNIT_EXPECT_EQ_MSG(test, drm_buddy_block_order(block), mm.max_order,
			    "block order(%d) != %d\n",
						drm_buddy_block_order(block), mm.max_order);

	KUNIT_EXPECT_EQ_MSG(test, drm_buddy_block_size(&mm, block),
			    BIT_ULL(mm.max_order) * PAGE_SIZE,
						"block size(%llu) != %llu\n",
						drm_buddy_block_size(&mm, block),
						BIT_ULL(mm.max_order) * PAGE_SIZE);

	drm_buddy_free_list(&mm, &allocated);
	drm_buddy_fini(&mm);
}

static struct kunit_case drm_buddy_tests[] = {
	KUNIT_CASE(drm_test_buddy_alloc_limit),
	KUNIT_CASE(drm_test_buddy_alloc_optimistic),
	KUNIT_CASE(drm_test_buddy_alloc_pessimistic),
	KUNIT_CASE(drm_test_buddy_alloc_pathological),
	KUNIT_CASE(drm_test_buddy_alloc_contiguous),
	{}
};

static struct kunit_suite drm_buddy_test_suite = {
	.name = "drm_buddy",
	.test_cases = drm_buddy_tests,
};

kunit_test_suite(drm_buddy_test_suite);

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL");