v4.19.13 snapshot.
diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c
new file mode 100644
index 0000000..def6015
--- /dev/null
+++ b/tools/testing/radix-tree/test.c
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
+#include <assert.h>
+#include <stdio.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+
+#include "test.h"
+
+struct item *
+item_tag_set(struct radix_tree_root *root, unsigned long index, int tag)
+{
+	return radix_tree_tag_set(root, index, tag);
+}
+
+struct item *
+item_tag_clear(struct radix_tree_root *root, unsigned long index, int tag)
+{
+	return radix_tree_tag_clear(root, index, tag);
+}
+
+int item_tag_get(struct radix_tree_root *root, unsigned long index, int tag)
+{
+	return radix_tree_tag_get(root, index, tag);
+}
+
+int __item_insert(struct radix_tree_root *root, struct item *item)
+{
+	return __radix_tree_insert(root, item->index, item->order, item);
+}
+
+struct item *item_create(unsigned long index, unsigned int order)
+{
+	struct item *ret = malloc(sizeof(*ret));
+
+	ret->index = index;
+	ret->order = order;
+	return ret;
+}
+
+int item_insert_order(struct radix_tree_root *root, unsigned long index,
+			unsigned order)
+{
+	struct item *item = item_create(index, order);
+	int err = __item_insert(root, item);
+	if (err)
+		free(item);
+	return err;
+}
+
+int item_insert(struct radix_tree_root *root, unsigned long index)
+{
+	return item_insert_order(root, index, 0);
+}
+
+void item_sanity(struct item *item, unsigned long index)
+{
+	unsigned long mask;
+	assert(!radix_tree_is_internal_node(item));
+	assert(item->order < BITS_PER_LONG);
+	mask = (1UL << item->order) - 1;
+	assert((item->index | mask) == (index | mask));
+}
+
+int item_delete(struct radix_tree_root *root, unsigned long index)
+{
+	struct item *item = radix_tree_delete(root, index);
+
+	if (item) {
+		item_sanity(item, index);
+		free(item);
+		return 1;
+	}
+	return 0;
+}
+
+static void item_free_rcu(struct rcu_head *head)
+{
+	struct item *item = container_of(head, struct item, rcu_head);
+
+	free(item);
+}
+
+int item_delete_rcu(struct radix_tree_root *root, unsigned long index)
+{
+	struct item *item = radix_tree_delete(root, index);
+
+	if (item) {
+		item_sanity(item, index);
+		call_rcu(&item->rcu_head, item_free_rcu);
+		return 1;
+	}
+	return 0;
+}
+
+void item_check_present(struct radix_tree_root *root, unsigned long index)
+{
+	struct item *item;
+
+	item = radix_tree_lookup(root, index);
+	assert(item != NULL);
+	item_sanity(item, index);
+}
+
+struct item *item_lookup(struct radix_tree_root *root, unsigned long index)
+{
+	return radix_tree_lookup(root, index);
+}
+
+void item_check_absent(struct radix_tree_root *root, unsigned long index)
+{
+	struct item *item;
+
+	item = radix_tree_lookup(root, index);
+	assert(item == NULL);
+}
+
+/*
+ * Scan only the passed (start, start+nr] for present items
+ */
+void item_gang_check_present(struct radix_tree_root *root,
+			unsigned long start, unsigned long nr,
+			int chunk, int hop)
+{
+	struct item *items[chunk];
+	unsigned long into;
+
+	for (into = 0; into < nr; ) {
+		int nfound;
+		int nr_to_find = chunk;
+		int i;
+
+		if (nr_to_find > (nr - into))
+			nr_to_find = nr - into;
+
+		nfound = radix_tree_gang_lookup(root, (void **)items,
+						start + into, nr_to_find);
+		assert(nfound == nr_to_find);
+		for (i = 0; i < nfound; i++)
+			assert(items[i]->index == start + into + i);
+		into += hop;
+	}
+}
+
+/*
+ * Scan the entire tree, only expecting present items (start, start+nr]
+ */
+void item_full_scan(struct radix_tree_root *root, unsigned long start,
+			unsigned long nr, int chunk)
+{
+	struct item *items[chunk];
+	unsigned long into = 0;
+	unsigned long this_index = start;
+	int nfound;
+	int i;
+
+//	printf("%s(0x%08lx, 0x%08lx, %d)\n", __FUNCTION__, start, nr, chunk);
+
+	while ((nfound = radix_tree_gang_lookup(root, (void **)items, into,
+					chunk))) {
+//		printf("At 0x%08lx, nfound=%d\n", into, nfound);
+		for (i = 0; i < nfound; i++) {
+			assert(items[i]->index == this_index);
+			this_index++;
+		}
+//		printf("Found 0x%08lx->0x%08lx\n",
+//			items[0]->index, items[nfound-1]->index);
+		into = this_index;
+	}
+	if (chunk)
+		assert(this_index == start + nr);
+	nfound = radix_tree_gang_lookup(root, (void **)items,
+					this_index, chunk);
+	assert(nfound == 0);
+}
+
+/* Use the same pattern as tag_pages_for_writeback() in mm/page-writeback.c */
+int tag_tagged_items(struct radix_tree_root *root, pthread_mutex_t *lock,
+			unsigned long start, unsigned long end, unsigned batch,
+			unsigned iftag, unsigned thentag)
+{
+	unsigned long tagged = 0;
+	struct radix_tree_iter iter;
+	void **slot;
+
+	if (batch == 0)
+		batch = 1;
+
+	if (lock)
+		pthread_mutex_lock(lock);
+	radix_tree_for_each_tagged(slot, root, &iter, start, iftag) {
+		if (iter.index > end)
+			break;
+		radix_tree_iter_tag_set(root, &iter, thentag);
+		tagged++;
+		if ((tagged % batch) != 0)
+			continue;
+		slot = radix_tree_iter_resume(slot, &iter);
+		if (lock) {
+			pthread_mutex_unlock(lock);
+			rcu_barrier();
+			pthread_mutex_lock(lock);
+		}
+	}
+	if (lock)
+		pthread_mutex_unlock(lock);
+
+	return tagged;
+}
+
+/* Use the same pattern as find_swap_entry() in mm/shmem.c */
+unsigned long find_item(struct radix_tree_root *root, void *item)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	unsigned long found = -1;
+	unsigned long checked = 0;
+
+	radix_tree_for_each_slot(slot, root, &iter, 0) {
+		if (*slot == item) {
+			found = iter.index;
+			break;
+		}
+		checked++;
+		if ((checked % 4) != 0)
+			continue;
+		slot = radix_tree_iter_resume(slot, &iter);
+	}
+
+	return found;
+}
+
+static int verify_node(struct radix_tree_node *slot, unsigned int tag,
+			int tagged)
+{
+	int anyset = 0;
+	int i;
+	int j;
+
+	slot = entry_to_node(slot);
+
+	/* Verify consistency at this level */
+	for (i = 0; i < RADIX_TREE_TAG_LONGS; i++) {
+		if (slot->tags[tag][i]) {
+			anyset = 1;
+			break;
+		}
+	}
+	if (tagged != anyset) {
+		printf("tag: %u, shift %u, tagged: %d, anyset: %d\n",
+			tag, slot->shift, tagged, anyset);
+		for (j = 0; j < RADIX_TREE_MAX_TAGS; j++) {
+			printf("tag %d: ", j);
+			for (i = 0; i < RADIX_TREE_TAG_LONGS; i++)
+				printf("%016lx ", slot->tags[j][i]);
+			printf("\n");
+		}
+		return 1;
+	}
+	assert(tagged == anyset);
+
+	/* Go for next level */
+	if (slot->shift > 0) {
+		for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
+			if (slot->slots[i])
+				if (verify_node(slot->slots[i], tag,
+					    !!test_bit(i, slot->tags[tag]))) {
+					printf("Failure at off %d\n", i);
+					for (j = 0; j < RADIX_TREE_MAX_TAGS; j++) {
+						printf("tag %d: ", j);
+						for (i = 0; i < RADIX_TREE_TAG_LONGS; i++)
+							printf("%016lx ", slot->tags[j][i]);
+						printf("\n");
+					}
+					return 1;
+				}
+	}
+	return 0;
+}
+
+void verify_tag_consistency(struct radix_tree_root *root, unsigned int tag)
+{
+	struct radix_tree_node *node = root->rnode;
+	if (!radix_tree_is_internal_node(node))
+		return;
+	verify_node(node, tag, !!root_tag_get(root, tag));
+}
+
+void item_kill_tree(struct radix_tree_root *root)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	struct item *items[32];
+	int nfound;
+
+	radix_tree_for_each_slot(slot, root, &iter, 0) {
+		if (radix_tree_exceptional_entry(*slot))
+			radix_tree_delete(root, iter.index);
+	}
+
+	while ((nfound = radix_tree_gang_lookup(root, (void **)items, 0, 32))) {
+		int i;
+
+		for (i = 0; i < nfound; i++) {
+			void *ret;
+
+			ret = radix_tree_delete(root, items[i]->index);
+			assert(ret == items[i]);
+			free(items[i]);
+		}
+	}
+	assert(radix_tree_gang_lookup(root, (void **)items, 0, 32) == 0);
+	assert(root->rnode == NULL);
+}
+
+void tree_verify_min_height(struct radix_tree_root *root, int maxindex)
+{
+	unsigned shift;
+	struct radix_tree_node *node = root->rnode;
+	if (!radix_tree_is_internal_node(node)) {
+		assert(maxindex == 0);
+		return;
+	}
+
+	node = entry_to_node(node);
+	assert(maxindex <= node_maxindex(node));
+
+	shift = node->shift;
+	if (shift > 0)
+		assert(maxindex > shift_maxindex(shift - RADIX_TREE_MAP_SHIFT));
+	else
+		assert(maxindex > 0);
+}