A puzzle for you...
---
drivers/gpu/drm/i915/i915_buddy.c | 17 +-
drivers/gpu/drm/i915/selftests/i915_buddy.c | 230 +++++++++++++++++++-
2 files changed, 234 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_buddy.c b/drivers/gpu/drm/i915/i915_buddy.c
index c0ac68d71d94..e5667540282a 100644
--- a/drivers/gpu/drm/i915/i915_buddy.c
+++ b/drivers/gpu/drm/i915/i915_buddy.c
@@ -16,7 +16,7 @@ static void mark_allocated(struct i915_buddy_block *block)
block->header &= ~I915_BUDDY_HEADER_STATE;
block->header |= I915_BUDDY_ALLOCATED;
- list_del_init(&block->link);
+ list_del(&block->link);
}
static void mark_free(struct i915_buddy_mm *mm,
@@ -34,7 +34,7 @@ static void mark_split(struct i915_buddy_block *block)
block->header &= ~I915_BUDDY_HEADER_STATE;
block->header |= I915_BUDDY_SPLIT;
- list_del_init(&block->link);
+ list_del(&block->link);
}
int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 min_size)
@@ -170,9 +170,6 @@ static int split_block(struct i915_buddy_mm *mm,
block->left->parent = block;
- INIT_LIST_HEAD(&block->left->link);
- INIT_LIST_HEAD(&block->left->tmp_link);
-
block->right = kmem_cache_zalloc(mm->blocks, GFP_KERNEL);
if (!block->right) {
kmem_cache_free(mm->blocks, block->left);
@@ -184,9 +181,6 @@ static int split_block(struct i915_buddy_mm *mm,
block->right->parent = block;
- INIT_LIST_HEAD(&block->right->link);
- INIT_LIST_HEAD(&block->right->tmp_link);
-
mark_free(mm, block->left);
mark_free(mm, block->right);
@@ -213,9 +207,9 @@ get_buddy(struct i915_buddy_block *block)
static void __i915_buddy_free(struct i915_buddy_mm *mm,
struct i915_buddy_block *block)
{
- list_del_init(&block->link); /* We have ownership now */
+ struct i915_buddy_block *parent;
- while (block->parent) {
+ while ((parent = block->parent)) {
struct i915_buddy_block *buddy;
buddy = get_buddy(block);
@@ -228,7 +222,7 @@ static void __i915_buddy_free(struct i915_buddy_mm *mm,
kmem_cache_free(mm->blocks, block);
kmem_cache_free(mm->blocks, buddy);
- block = block->parent;
+ block = parent;
}
mark_free(mm, block);
@@ -248,6 +242,7 @@ void i915_buddy_free_list(struct i915_buddy_mm *mm,
list_for_each_entry_safe(block, on, objects, link)
i915_buddy_free(mm, block);
+ INIT_LIST_HEAD(objects);
}
/*
diff --git a/drivers/gpu/drm/i915/selftests/i915_buddy.c b/drivers/gpu/drm/i915/selftests/i915_buddy.c
index 2159aa9f4867..943a9d08d2f5 100644
--- a/drivers/gpu/drm/i915/selftests/i915_buddy.c
+++ b/drivers/gpu/drm/i915/selftests/i915_buddy.c
@@ -295,7 +295,7 @@ static void igt_mm_config(u64 *size, u64 *min_size)
*size = s;
}
-static int igt_buddy_alloc(void *arg)
+static int igt_buddy_alloc_smoke(void *arg)
{
struct i915_buddy_mm mm;
int max_order;
@@ -385,6 +385,229 @@ static int igt_buddy_alloc(void *arg)
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(buddies);
+ 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);
+ }
+
+ 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;
+ }
+ }
+
+ /* Split the final block */
+ block = i915_buddy_alloc(&mm, 0);
+ if (IS_ERR(block)) {
+ pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
+ 0);
+ err = PTR_ERR(block);
+ goto err;
+ }
+ list_add_tail(&block->link, &blocks);
+
+ /* Nothing larger than blocks of min_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:
+ 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;
@@ -483,7 +706,10 @@ static int igt_buddy_alloc_range(void *arg)
int i915_buddy_mock_selftests(void)
{
static const struct i915_subtest tests[] = {
- SUBTEST(igt_buddy_alloc),
+ 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),
};
--
2.20.1
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