diff --git a/lib/test_objagg.c b/lib/test_objagg.c
new file mode 100644
index 0000000..72c1abf
--- /dev/null
+++ b/lib/test_objagg.c
@@ -0,0 +1,1021 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/* Copyright (c) 2018 Mellanox Technologies. All rights reserved */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/objagg.h>
+
+struct tokey {
+	unsigned int id;
+};
+
+#define NUM_KEYS 32
+
+static int key_id_index(unsigned int key_id)
+{
+	if (key_id >= NUM_KEYS) {
+		WARN_ON(1);
+		return 0;
+	}
+	return key_id;
+}
+
+#define BUF_LEN 128
+
+struct world {
+	unsigned int root_count;
+	unsigned int delta_count;
+	char next_root_buf[BUF_LEN];
+	struct objagg_obj *objagg_objs[NUM_KEYS];
+	unsigned int key_refs[NUM_KEYS];
+};
+
+struct root {
+	struct tokey key;
+	char buf[BUF_LEN];
+};
+
+struct delta {
+	unsigned int key_id_diff;
+};
+
+static struct objagg_obj *world_obj_get(struct world *world,
+					struct objagg *objagg,
+					unsigned int key_id)
+{
+	struct objagg_obj *objagg_obj;
+	struct tokey key;
+	int err;
+
+	key.id = key_id;
+	objagg_obj = objagg_obj_get(objagg, &key);
+	if (IS_ERR(objagg_obj)) {
+		pr_err("Key %u: Failed to get object.\n", key_id);
+		return objagg_obj;
+	}
+	if (!world->key_refs[key_id_index(key_id)]) {
+		world->objagg_objs[key_id_index(key_id)] = objagg_obj;
+	} else if (world->objagg_objs[key_id_index(key_id)] != objagg_obj) {
+		pr_err("Key %u: God another object for the same key.\n",
+		       key_id);
+		err = -EINVAL;
+		goto err_key_id_check;
+	}
+	world->key_refs[key_id_index(key_id)]++;
+	return objagg_obj;
+
+err_key_id_check:
+	objagg_obj_put(objagg, objagg_obj);
+	return ERR_PTR(err);
+}
+
+static void world_obj_put(struct world *world, struct objagg *objagg,
+			  unsigned int key_id)
+{
+	struct objagg_obj *objagg_obj;
+
+	if (!world->key_refs[key_id_index(key_id)])
+		return;
+	objagg_obj = world->objagg_objs[key_id_index(key_id)];
+	objagg_obj_put(objagg, objagg_obj);
+	world->key_refs[key_id_index(key_id)]--;
+}
+
+#define MAX_KEY_ID_DIFF 5
+
+static bool delta_check(void *priv, const void *parent_obj, const void *obj)
+{
+	const struct tokey *parent_key = parent_obj;
+	const struct tokey *key = obj;
+	int diff = key->id - parent_key->id;
+
+	return diff >= 0 && diff <= MAX_KEY_ID_DIFF;
+}
+
+static void *delta_create(void *priv, void *parent_obj, void *obj)
+{
+	struct tokey *parent_key = parent_obj;
+	struct world *world = priv;
+	struct tokey *key = obj;
+	int diff = key->id - parent_key->id;
+	struct delta *delta;
+
+	if (!delta_check(priv, parent_obj, obj))
+		return ERR_PTR(-EINVAL);
+
+	delta = kzalloc(sizeof(*delta), GFP_KERNEL);
+	if (!delta)
+		return ERR_PTR(-ENOMEM);
+	delta->key_id_diff = diff;
+	world->delta_count++;
+	return delta;
+}
+
+static void delta_destroy(void *priv, void *delta_priv)
+{
+	struct delta *delta = delta_priv;
+	struct world *world = priv;
+
+	world->delta_count--;
+	kfree(delta);
+}
+
+static void *root_create(void *priv, void *obj, unsigned int id)
+{
+	struct world *world = priv;
+	struct tokey *key = obj;
+	struct root *root;
+
+	root = kzalloc(sizeof(*root), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+	memcpy(&root->key, key, sizeof(root->key));
+	memcpy(root->buf, world->next_root_buf, sizeof(root->buf));
+	world->root_count++;
+	return root;
+}
+
+static void root_destroy(void *priv, void *root_priv)
+{
+	struct root *root = root_priv;
+	struct world *world = priv;
+
+	world->root_count--;
+	kfree(root);
+}
+
+static int test_nodelta_obj_get(struct world *world, struct objagg *objagg,
+				unsigned int key_id, bool should_create_root)
+{
+	unsigned int orig_root_count = world->root_count;
+	struct objagg_obj *objagg_obj;
+	const struct root *root;
+	int err;
+
+	if (should_create_root)
+		prandom_bytes(world->next_root_buf,
+			      sizeof(world->next_root_buf));
+
+	objagg_obj = world_obj_get(world, objagg, key_id);
+	if (IS_ERR(objagg_obj)) {
+		pr_err("Key %u: Failed to get object.\n", key_id);
+		return PTR_ERR(objagg_obj);
+	}
+	if (should_create_root) {
+		if (world->root_count != orig_root_count + 1) {
+			pr_err("Key %u: Root was not created\n", key_id);
+			err = -EINVAL;
+			goto err_check_root_count;
+		}
+	} else {
+		if (world->root_count != orig_root_count) {
+			pr_err("Key %u: Root was incorrectly created\n",
+			       key_id);
+			err = -EINVAL;
+			goto err_check_root_count;
+		}
+	}
+	root = objagg_obj_root_priv(objagg_obj);
+	if (root->key.id != key_id) {
+		pr_err("Key %u: Root has unexpected key id\n", key_id);
+		err = -EINVAL;
+		goto err_check_key_id;
+	}
+	if (should_create_root &&
+	    memcmp(world->next_root_buf, root->buf, sizeof(root->buf))) {
+		pr_err("Key %u: Buffer does not match the expected content\n",
+		       key_id);
+		err = -EINVAL;
+		goto err_check_buf;
+	}
+	return 0;
+
+err_check_buf:
+err_check_key_id:
+err_check_root_count:
+	objagg_obj_put(objagg, objagg_obj);
+	return err;
+}
+
+static int test_nodelta_obj_put(struct world *world, struct objagg *objagg,
+				unsigned int key_id, bool should_destroy_root)
+{
+	unsigned int orig_root_count = world->root_count;
+
+	world_obj_put(world, objagg, key_id);
+
+	if (should_destroy_root) {
+		if (world->root_count != orig_root_count - 1) {
+			pr_err("Key %u: Root was not destroyed\n", key_id);
+			return -EINVAL;
+		}
+	} else {
+		if (world->root_count != orig_root_count) {
+			pr_err("Key %u: Root was incorrectly destroyed\n",
+			       key_id);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static int check_stats_zero(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+	int err = 0;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+
+	if (stats->stats_info_count != 0) {
+		pr_err("Stats: Object count is not zero while it should be\n");
+		err = -EINVAL;
+	}
+
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int check_stats_nodelta(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+	int i;
+	int err;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+
+	if (stats->stats_info_count != NUM_KEYS) {
+		pr_err("Stats: Unexpected object count (%u expected, %u returned)\n",
+		       NUM_KEYS, stats->stats_info_count);
+		err = -EINVAL;
+		goto stats_put;
+	}
+
+	for (i = 0; i < stats->stats_info_count; i++) {
+		if (stats->stats_info[i].stats.user_count != 2) {
+			pr_err("Stats: incorrect user count\n");
+			err = -EINVAL;
+			goto stats_put;
+		}
+		if (stats->stats_info[i].stats.delta_user_count != 2) {
+			pr_err("Stats: incorrect delta user count\n");
+			err = -EINVAL;
+			goto stats_put;
+		}
+	}
+	err = 0;
+
+stats_put:
+	objagg_stats_put(stats);
+	return err;
+}
+
+static bool delta_check_dummy(void *priv, const void *parent_obj,
+			      const void *obj)
+{
+	return false;
+}
+
+static void *delta_create_dummy(void *priv, void *parent_obj, void *obj)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static void delta_destroy_dummy(void *priv, void *delta_priv)
+{
+}
+
+static const struct objagg_ops nodelta_ops = {
+	.obj_size = sizeof(struct tokey),
+	.delta_check = delta_check_dummy,
+	.delta_create = delta_create_dummy,
+	.delta_destroy = delta_destroy_dummy,
+	.root_create = root_create,
+	.root_destroy = root_destroy,
+};
+
+static int test_nodelta(void)
+{
+	struct world world = {};
+	struct objagg *objagg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&nodelta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	err = check_stats_zero(objagg);
+	if (err)
+		goto err_stats_first_zero;
+
+	/* First round of gets, the root objects should be created */
+	for (i = 0; i < NUM_KEYS; i++) {
+		err = test_nodelta_obj_get(&world, objagg, i, true);
+		if (err)
+			goto err_obj_first_get;
+	}
+
+	/* Do the second round of gets, all roots are already created,
+	 * make sure that no new root is created
+	 */
+	for (i = 0; i < NUM_KEYS; i++) {
+		err = test_nodelta_obj_get(&world, objagg, i, false);
+		if (err)
+			goto err_obj_second_get;
+	}
+
+	err = check_stats_nodelta(objagg);
+	if (err)
+		goto err_stats_nodelta;
+
+	for (i = NUM_KEYS - 1; i >= 0; i--) {
+		err = test_nodelta_obj_put(&world, objagg, i, false);
+		if (err)
+			goto err_obj_first_put;
+	}
+	for (i = NUM_KEYS - 1; i >= 0; i--) {
+		err = test_nodelta_obj_put(&world, objagg, i, true);
+		if (err)
+			goto err_obj_second_put;
+	}
+
+	err = check_stats_zero(objagg);
+	if (err)
+		goto err_stats_second_zero;
+
+	objagg_destroy(objagg);
+	return 0;
+
+err_stats_nodelta:
+err_obj_first_put:
+err_obj_second_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, i);
+
+	i = NUM_KEYS;
+err_obj_first_get:
+err_obj_second_put:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, i);
+err_stats_first_zero:
+err_stats_second_zero:
+	objagg_destroy(objagg);
+	return err;
+}
+
+static const struct objagg_ops delta_ops = {
+	.obj_size = sizeof(struct tokey),
+	.delta_check = delta_check,
+	.delta_create = delta_create,
+	.delta_destroy = delta_destroy,
+	.root_create = root_create,
+	.root_destroy = root_destroy,
+};
+
+enum action {
+	ACTION_GET,
+	ACTION_PUT,
+};
+
+enum expect_delta {
+	EXPECT_DELTA_SAME,
+	EXPECT_DELTA_INC,
+	EXPECT_DELTA_DEC,
+};
+
+enum expect_root {
+	EXPECT_ROOT_SAME,
+	EXPECT_ROOT_INC,
+	EXPECT_ROOT_DEC,
+};
+
+struct expect_stats_info {
+	struct objagg_obj_stats stats;
+	bool is_root;
+	unsigned int key_id;
+};
+
+struct expect_stats {
+	unsigned int info_count;
+	struct expect_stats_info info[NUM_KEYS];
+};
+
+struct action_item {
+	unsigned int key_id;
+	enum action action;
+	enum expect_delta expect_delta;
+	enum expect_root expect_root;
+	struct expect_stats expect_stats;
+};
+
+#define EXPECT_STATS(count, ...)		\
+{						\
+	.info_count = count,			\
+	.info = { __VA_ARGS__ }			\
+}
+
+#define ROOT(key_id, user_count, delta_user_count)	\
+	{{user_count, delta_user_count}, true, key_id}
+
+#define DELTA(key_id, user_count)			\
+	{{user_count, user_count}, false, key_id}
+
+static const struct action_item action_items[] = {
+	{
+		1, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(1, ROOT(1, 1, 1)),
+	},	/* r: 1			d: */
+	{
+		7, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(2, ROOT(1, 1, 1), ROOT(7, 1, 1)),
+	},	/* r: 1, 7		d: */
+	{
+		3, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(3, ROOT(1, 1, 2), ROOT(7, 1, 1),
+				DELTA(3, 1)),
+	},	/* r: 1, 7		d: 3^1 */
+	{
+		5, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 1, 3), ROOT(7, 1, 1),
+				DELTA(3, 1), DELTA(5, 1)),
+	},	/* r: 1, 7		d: 3^1, 5^1 */
+	{
+		3, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 1, 4), ROOT(7, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 7		d: 3^1, 3^1, 5^1 */
+	{
+		1, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 2, 5), ROOT(7, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7		d: 3^1, 3^1, 5^1 */
+	{
+		30, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(5, ROOT(1, 2, 5), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 5), ROOT(7, 1, 2), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(5, 1), DELTA(8, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1, 8^7 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 5), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1, 8^7, 8^7 */
+	{
+		3, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 4), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(3, 1), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 5^1, 8^7, 8^7 */
+	{
+		3, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(1, 2, 3), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 5^1, 8^7, 8^7 */
+	{
+		1, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(1, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 7, 30		d: 5^1, 8^7, 8^7 */
+	{
+		1, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(30, 1, 1), ROOT(1, 0, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 7, 30		d: 5^1, 8^7, 8^7 */
+	{
+		5, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_DEC,
+		EXPECT_STATS(3, ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2)),
+	},	/* r: 7, 30		d: 8^7, 8^7 */
+	{
+		5, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(4, ROOT(7, 1, 3), ROOT(30, 1, 1), ROOT(5, 1, 1),
+				DELTA(8, 2)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7 */
+	{
+		6, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 4), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 2), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 1), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(5, 1, 2), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 6^5 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(5, 1, 3), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 7, 30, 5		d: 6^5, 8^5 */
+	{
+		7, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_DEC,
+		EXPECT_STATS(4, ROOT(5, 1, 3), ROOT(30, 1, 1),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 30, 5		d: 6^5, 8^5 */
+	{
+		30, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_DEC,
+		EXPECT_STATS(3, ROOT(5, 1, 3),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 5			d: 6^5, 8^5 */
+	{
+		5, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(3, ROOT(5, 0, 2),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r:			d: 6^5, 8^5 */
+	{
+		6, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(2, ROOT(5, 0, 1),
+				DELTA(8, 1)),
+	},	/* r:			d: 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_DEC,
+		EXPECT_STATS(0, ),
+	},	/* r:			d: */
+};
+
+static int check_expect(struct world *world,
+			const struct action_item *action_item,
+			unsigned int orig_delta_count,
+			unsigned int orig_root_count)
+{
+	unsigned int key_id = action_item->key_id;
+
+	switch (action_item->expect_delta) {
+	case EXPECT_DELTA_SAME:
+		if (orig_delta_count != world->delta_count) {
+			pr_err("Key %u: Delta count changed while expected to remain the same.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_DELTA_INC:
+		if (WARN_ON(action_item->action == ACTION_PUT))
+			return -EINVAL;
+		if (orig_delta_count + 1 != world->delta_count) {
+			pr_err("Key %u: Delta count was not incremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_DELTA_DEC:
+		if (WARN_ON(action_item->action == ACTION_GET))
+			return -EINVAL;
+		if (orig_delta_count - 1 != world->delta_count) {
+			pr_err("Key %u: Delta count was not decremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	}
+
+	switch (action_item->expect_root) {
+	case EXPECT_ROOT_SAME:
+		if (orig_root_count != world->root_count) {
+			pr_err("Key %u: Root count changed while expected to remain the same.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_ROOT_INC:
+		if (WARN_ON(action_item->action == ACTION_PUT))
+			return -EINVAL;
+		if (orig_root_count + 1 != world->root_count) {
+			pr_err("Key %u: Root count was not incremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_ROOT_DEC:
+		if (WARN_ON(action_item->action == ACTION_GET))
+			return -EINVAL;
+		if (orig_root_count - 1 != world->root_count) {
+			pr_err("Key %u: Root count was not decremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static unsigned int obj_to_key_id(struct objagg_obj *objagg_obj)
+{
+	const struct tokey *root_key;
+	const struct delta *delta;
+	unsigned int key_id;
+
+	root_key = objagg_obj_root_priv(objagg_obj);
+	key_id = root_key->id;
+	delta = objagg_obj_delta_priv(objagg_obj);
+	if (delta)
+		key_id += delta->key_id_diff;
+	return key_id;
+}
+
+static int
+check_expect_stats_nums(const struct objagg_obj_stats_info *stats_info,
+			const struct expect_stats_info *expect_stats_info,
+			const char **errmsg)
+{
+	if (stats_info->is_root != expect_stats_info->is_root) {
+		if (errmsg)
+			*errmsg = "Incorrect root/delta indication";
+		return -EINVAL;
+	}
+	if (stats_info->stats.user_count !=
+	    expect_stats_info->stats.user_count) {
+		if (errmsg)
+			*errmsg = "Incorrect user count";
+		return -EINVAL;
+	}
+	if (stats_info->stats.delta_user_count !=
+	    expect_stats_info->stats.delta_user_count) {
+		if (errmsg)
+			*errmsg = "Incorrect delta user count";
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+check_expect_stats_key_id(const struct objagg_obj_stats_info *stats_info,
+			  const struct expect_stats_info *expect_stats_info,
+			  const char **errmsg)
+{
+	if (obj_to_key_id(stats_info->objagg_obj) !=
+	    expect_stats_info->key_id) {
+		if (errmsg)
+			*errmsg = "incorrect key id";
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int check_expect_stats_neigh(const struct objagg_stats *stats,
+				    const struct expect_stats *expect_stats,
+				    int pos)
+{
+	int i;
+	int err;
+
+	for (i = pos - 1; i >= 0; i--) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[pos], NULL);
+		if (err)
+			break;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[pos], NULL);
+		if (!err)
+			return 0;
+	}
+	for (i = pos + 1; i < stats->stats_info_count; i++) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[pos], NULL);
+		if (err)
+			break;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[pos], NULL);
+		if (!err)
+			return 0;
+	}
+	return -EINVAL;
+}
+
+static int __check_expect_stats(const struct objagg_stats *stats,
+				const struct expect_stats *expect_stats,
+				const char **errmsg)
+{
+	int i;
+	int err;
+
+	if (stats->stats_info_count != expect_stats->info_count) {
+		*errmsg = "Unexpected object count";
+		return -EINVAL;
+	}
+
+	for (i = 0; i < stats->stats_info_count; i++) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[i], errmsg);
+		if (err)
+			return err;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[i], errmsg);
+		if (err) {
+			/* It is possible that one of the neighbor stats with
+			 * same numbers have the correct key id, so check it
+			 */
+			err = check_expect_stats_neigh(stats, expect_stats, i);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+static int check_expect_stats(struct objagg *objagg,
+			      const struct expect_stats *expect_stats,
+			      const char **errmsg)
+{
+	const struct objagg_stats *stats;
+	int err;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats)) {
+		*errmsg = "objagg_stats_get() failed.";
+		return PTR_ERR(stats);
+	}
+	err = __check_expect_stats(stats, expect_stats, errmsg);
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int test_delta_action_item(struct world *world,
+				  struct objagg *objagg,
+				  const struct action_item *action_item,
+				  bool inverse)
+{
+	unsigned int orig_delta_count = world->delta_count;
+	unsigned int orig_root_count = world->root_count;
+	unsigned int key_id = action_item->key_id;
+	enum action action = action_item->action;
+	struct objagg_obj *objagg_obj;
+	const char *errmsg;
+	int err;
+
+	if (inverse)
+		action = action == ACTION_GET ? ACTION_PUT : ACTION_GET;
+
+	switch (action) {
+	case ACTION_GET:
+		objagg_obj = world_obj_get(world, objagg, key_id);
+		if (IS_ERR(objagg_obj))
+			return PTR_ERR(objagg_obj);
+		break;
+	case ACTION_PUT:
+		world_obj_put(world, objagg, key_id);
+		break;
+	}
+
+	if (inverse)
+		return 0;
+	err = check_expect(world, action_item,
+			   orig_delta_count, orig_root_count);
+	if (err)
+		goto errout;
+
+	err = check_expect_stats(objagg, &action_item->expect_stats, &errmsg);
+	if (err) {
+		pr_err("Key %u: Stats: %s\n", action_item->key_id, errmsg);
+		goto errout;
+	}
+
+	return 0;
+
+errout:
+	/* This can only happen when action is not inversed.
+	 * So in case of an error, cleanup by doing inverse action.
+	 */
+	test_delta_action_item(world, objagg, action_item, true);
+	return err;
+}
+
+static int test_delta(void)
+{
+	struct world world = {};
+	struct objagg *objagg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&delta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	for (i = 0; i < ARRAY_SIZE(action_items); i++) {
+		err = test_delta_action_item(&world, objagg,
+					     &action_items[i], false);
+		if (err)
+			goto err_do_action_item;
+	}
+
+	objagg_destroy(objagg);
+	return 0;
+
+err_do_action_item:
+	for (i--; i >= 0; i--)
+		test_delta_action_item(&world, objagg, &action_items[i], true);
+
+	objagg_destroy(objagg);
+	return err;
+}
+
+struct hints_case {
+	const unsigned int *key_ids;
+	size_t key_ids_count;
+	struct expect_stats expect_stats;
+	struct expect_stats expect_stats_hints;
+};
+
+static const unsigned int hints_case_key_ids[] = {
+	1, 7, 3, 5, 3, 1, 30, 8, 8, 5, 6, 8,
+};
+
+static const struct hints_case hints_case = {
+	.key_ids = hints_case_key_ids,
+	.key_ids_count = ARRAY_SIZE(hints_case_key_ids),
+	.expect_stats =
+		EXPECT_STATS(7, ROOT(1, 2, 7), ROOT(7, 1, 4), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(3, 2),
+				DELTA(5, 2), DELTA(6, 1)),
+	.expect_stats_hints =
+		EXPECT_STATS(7, ROOT(3, 2, 9), ROOT(1, 2, 2), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(5, 2),
+				DELTA(6, 1), DELTA(7, 1)),
+};
+
+static void __pr_debug_stats(const struct objagg_stats *stats)
+{
+	int i;
+
+	for (i = 0; i < stats->stats_info_count; i++)
+		pr_debug("Stat index %d key %u: u %d, d %d, %s\n", i,
+			 obj_to_key_id(stats->stats_info[i].objagg_obj),
+			 stats->stats_info[i].stats.user_count,
+			 stats->stats_info[i].stats.delta_user_count,
+			 stats->stats_info[i].is_root ? "root" : "noroot");
+}
+
+static void pr_debug_stats(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return;
+	__pr_debug_stats(stats);
+	objagg_stats_put(stats);
+}
+
+static void pr_debug_hints_stats(struct objagg_hints *objagg_hints)
+{
+	const struct objagg_stats *stats;
+
+	stats = objagg_hints_stats_get(objagg_hints);
+	if (IS_ERR(stats))
+		return;
+	__pr_debug_stats(stats);
+	objagg_stats_put(stats);
+}
+
+static int check_expect_hints_stats(struct objagg_hints *objagg_hints,
+				    const struct expect_stats *expect_stats,
+				    const char **errmsg)
+{
+	const struct objagg_stats *stats;
+	int err;
+
+	stats = objagg_hints_stats_get(objagg_hints);
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+	err = __check_expect_stats(stats, expect_stats, errmsg);
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int test_hints_case(const struct hints_case *hints_case)
+{
+	struct objagg_obj *objagg_obj;
+	struct objagg_hints *hints;
+	struct world world2 = {};
+	struct world world = {};
+	struct objagg *objagg2;
+	struct objagg *objagg;
+	const char *errmsg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&delta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	for (i = 0; i < hints_case->key_ids_count; i++) {
+		objagg_obj = world_obj_get(&world, objagg,
+					   hints_case->key_ids[i]);
+		if (IS_ERR(objagg_obj)) {
+			err = PTR_ERR(objagg_obj);
+			goto err_world_obj_get;
+		}
+	}
+
+	pr_debug_stats(objagg);
+	err = check_expect_stats(objagg, &hints_case->expect_stats, &errmsg);
+	if (err) {
+		pr_err("Stats: %s\n", errmsg);
+		goto err_check_expect_stats;
+	}
+
+	hints = objagg_hints_get(objagg, OBJAGG_OPT_ALGO_SIMPLE_GREEDY);
+	if (IS_ERR(hints)) {
+		err = PTR_ERR(hints);
+		goto err_hints_get;
+	}
+
+	pr_debug_hints_stats(hints);
+	err = check_expect_hints_stats(hints, &hints_case->expect_stats_hints,
+				       &errmsg);
+	if (err) {
+		pr_err("Hints stats: %s\n", errmsg);
+		goto err_check_expect_hints_stats;
+	}
+
+	objagg2 = objagg_create(&delta_ops, hints, &world2);
+	if (IS_ERR(objagg2))
+		return PTR_ERR(objagg2);
+
+	for (i = 0; i < hints_case->key_ids_count; i++) {
+		objagg_obj = world_obj_get(&world2, objagg2,
+					   hints_case->key_ids[i]);
+		if (IS_ERR(objagg_obj)) {
+			err = PTR_ERR(objagg_obj);
+			goto err_world2_obj_get;
+		}
+	}
+
+	pr_debug_stats(objagg2);
+	err = check_expect_stats(objagg2, &hints_case->expect_stats_hints,
+				 &errmsg);
+	if (err) {
+		pr_err("Stats2: %s\n", errmsg);
+		goto err_check_expect_stats2;
+	}
+
+	err = 0;
+
+err_check_expect_stats2:
+err_world2_obj_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world2, objagg, hints_case->key_ids[i]);
+	objagg_hints_put(hints);
+	objagg_destroy(objagg2);
+	i = hints_case->key_ids_count;
+err_check_expect_hints_stats:
+err_hints_get:
+err_check_expect_stats:
+err_world_obj_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, hints_case->key_ids[i]);
+
+	objagg_destroy(objagg);
+	return err;
+}
+static int test_hints(void)
+{
+	return test_hints_case(&hints_case);
+}
+
+static int __init test_objagg_init(void)
+{
+	int err;
+
+	err = test_nodelta();
+	if (err)
+		return err;
+	err = test_delta();
+	if (err)
+		return err;
+	return test_hints();
+}
+
+static void __exit test_objagg_exit(void)
+{
+}
+
+module_init(test_objagg_init);
+module_exit(test_objagg_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
+MODULE_DESCRIPTION("Test module for objagg");