diff --git a/tools/testing/radix-tree/.gitignore b/tools/testing/radix-tree/.gitignore
new file mode 100644
index 0000000..d4706c0
--- /dev/null
+++ b/tools/testing/radix-tree/.gitignore
@@ -0,0 +1,6 @@
+generated/map-shift.h
+idr.c
+idr-test
+main
+multiorder
+radix-tree.c
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
new file mode 100644
index 0000000..37baecc
--- /dev/null
+++ b/tools/testing/radix-tree/Makefile
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
+	  -fsanitize=undefined
+LDFLAGS += -fsanitize=address -fsanitize=undefined
+LDLIBS+= -lpthread -lurcu
+TARGETS = main idr-test multiorder
+CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o
+OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
+	 tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
+
+ifndef SHIFT
+	SHIFT=3
+endif
+
+ifeq ($(BUILD), 32)
+	CFLAGS += -m32
+	LDFLAGS += -m32
+endif
+
+targets: generated/map-shift.h $(TARGETS)
+
+main:	$(OFILES)
+
+idr-test.o: ../../../lib/test_ida.c
+idr-test: idr-test.o $(CORE_OFILES)
+
+multiorder: multiorder.o $(CORE_OFILES)
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h
+
+vpath %.c ../../lib
+
+$(OFILES): Makefile *.h */*.h generated/map-shift.h \
+	../../include/linux/*.h \
+	../../include/asm/*.h \
+	../../../include/linux/radix-tree.h \
+	../../../include/linux/idr.h
+
+radix-tree.c: ../../../lib/radix-tree.c
+	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
+idr.c: ../../../lib/idr.c
+	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
+generated/map-shift.h:
+	@if ! grep -qws $(SHIFT) generated/map-shift.h; then		\
+		echo "#define RADIX_TREE_MAP_SHIFT $(SHIFT)" >		\
+				generated/map-shift.h;			\
+	fi
diff --git a/tools/testing/radix-tree/benchmark.c b/tools/testing/radix-tree/benchmark.c
new file mode 100644
index 0000000..99c40f3
--- /dev/null
+++ b/tools/testing/radix-tree/benchmark.c
@@ -0,0 +1,257 @@
+/*
+ * benchmark.c:
+ * Author: Konstantin Khlebnikov <koct9i@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/radix-tree.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <time.h>
+#include "test.h"
+
+#define for_each_index(i, base, order) \
+	        for (i = base; i < base + (1 << order); i++)
+
+#define NSEC_PER_SEC	1000000000L
+
+static long long benchmark_iter(struct radix_tree_root *root, bool tagged)
+{
+	volatile unsigned long sink = 0;
+	struct radix_tree_iter iter;
+	struct timespec start, finish;
+	long long nsec;
+	int l, loops = 1;
+	void **slot;
+
+#ifdef BENCHMARK
+again:
+#endif
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	for (l = 0; l < loops; l++) {
+		if (tagged) {
+			radix_tree_for_each_tagged(slot, root, &iter, 0, 0)
+				sink ^= (unsigned long)slot;
+		} else {
+			radix_tree_for_each_slot(slot, root, &iter, 0)
+				sink ^= (unsigned long)slot;
+		}
+	}
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+	       (finish.tv_nsec - start.tv_nsec);
+
+#ifdef BENCHMARK
+	if (loops == 1 && nsec * 5 < NSEC_PER_SEC) {
+		loops = NSEC_PER_SEC / nsec / 4 + 1;
+		goto again;
+	}
+#endif
+
+	nsec /= loops;
+	return nsec;
+}
+
+static void benchmark_insert(struct radix_tree_root *root,
+			     unsigned long size, unsigned long step, int order)
+{
+	struct timespec start, finish;
+	unsigned long index;
+	long long nsec;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	for (index = 0 ; index < size ; index += step)
+		item_insert_order(root, index, order);
+
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+	       (finish.tv_nsec - start.tv_nsec);
+
+	printv(2, "Size: %8ld, step: %8ld, order: %d, insertion: %15lld ns\n",
+		size, step, order, nsec);
+}
+
+static void benchmark_tagging(struct radix_tree_root *root,
+			     unsigned long size, unsigned long step, int order)
+{
+	struct timespec start, finish;
+	unsigned long index;
+	long long nsec;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	for (index = 0 ; index < size ; index += step)
+		radix_tree_tag_set(root, index, 0);
+
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+	       (finish.tv_nsec - start.tv_nsec);
+
+	printv(2, "Size: %8ld, step: %8ld, order: %d, tagging: %17lld ns\n",
+		size, step, order, nsec);
+}
+
+static void benchmark_delete(struct radix_tree_root *root,
+			     unsigned long size, unsigned long step, int order)
+{
+	struct timespec start, finish;
+	unsigned long index, i;
+	long long nsec;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	for (index = 0 ; index < size ; index += step)
+		for_each_index(i, index, order)
+			item_delete(root, i);
+
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+	       (finish.tv_nsec - start.tv_nsec);
+
+	printv(2, "Size: %8ld, step: %8ld, order: %d, deletion: %16lld ns\n",
+		size, step, order, nsec);
+}
+
+static void benchmark_size(unsigned long size, unsigned long step, int order)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	long long normal, tagged;
+
+	benchmark_insert(&tree, size, step, order);
+	benchmark_tagging(&tree, size, step, order);
+
+	tagged = benchmark_iter(&tree, true);
+	normal = benchmark_iter(&tree, false);
+
+	printv(2, "Size: %8ld, step: %8ld, order: %d, tagged iteration: %8lld ns\n",
+		size, step, order, tagged);
+	printv(2, "Size: %8ld, step: %8ld, order: %d, normal iteration: %8lld ns\n",
+		size, step, order, normal);
+
+	benchmark_delete(&tree, size, step, order);
+
+	item_kill_tree(&tree);
+	rcu_barrier();
+}
+
+static long long  __benchmark_split(unsigned long index,
+				    int old_order, int new_order)
+{
+	struct timespec start, finish;
+	long long nsec;
+	RADIX_TREE(tree, GFP_ATOMIC);
+
+	item_insert_order(&tree, index, old_order);
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	radix_tree_split(&tree, index, new_order);
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+	       (finish.tv_nsec - start.tv_nsec);
+
+	item_kill_tree(&tree);
+
+	return nsec;
+
+}
+
+static void benchmark_split(unsigned long size, unsigned long step)
+{
+	int i, j, idx;
+	long long nsec = 0;
+
+
+	for (idx = 0; idx < size; idx += step) {
+		for (i = 3; i < 11; i++) {
+			for (j = 0; j < i; j++) {
+				nsec += __benchmark_split(idx, i, j);
+			}
+		}
+	}
+
+	printv(2, "Size %8ld, step %8ld, split time %10lld ns\n",
+			size, step, nsec);
+
+}
+
+static long long  __benchmark_join(unsigned long index,
+			     unsigned order1, unsigned order2)
+{
+	unsigned long loc;
+	struct timespec start, finish;
+	long long nsec;
+	void *item, *item2 = item_create(index + 1, order1);
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert_order(&tree, index, order2);
+	item = radix_tree_lookup(&tree, index);
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	radix_tree_join(&tree, index + 1, order1, item2);
+	clock_gettime(CLOCK_MONOTONIC, &finish);
+	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
+		(finish.tv_nsec - start.tv_nsec);
+
+	loc = find_item(&tree, item);
+	if (loc == -1)
+		free(item);
+
+	item_kill_tree(&tree);
+
+	return nsec;
+}
+
+static void benchmark_join(unsigned long step)
+{
+	int i, j, idx;
+	long long nsec = 0;
+
+	for (idx = 0; idx < 1 << 10; idx += step) {
+		for (i = 1; i < 15; i++) {
+			for (j = 0; j < i; j++) {
+				nsec += __benchmark_join(idx, i, j);
+			}
+		}
+	}
+
+	printv(2, "Size %8d, step %8ld, join time %10lld ns\n",
+			1 << 10, step, nsec);
+}
+
+void benchmark(void)
+{
+	unsigned long size[] = {1 << 10, 1 << 20, 0};
+	unsigned long step[] = {1, 2, 7, 15, 63, 64, 65,
+				128, 256, 512, 12345, 0};
+	int c, s;
+
+	printv(1, "starting benchmarks\n");
+	printv(1, "RADIX_TREE_MAP_SHIFT = %d\n", RADIX_TREE_MAP_SHIFT);
+
+	for (c = 0; size[c]; c++)
+		for (s = 0; step[s]; s++)
+			benchmark_size(size[c], step[s], 0);
+
+	for (c = 0; size[c]; c++)
+		for (s = 0; step[s]; s++)
+			benchmark_size(size[c], step[s] << 9, 9);
+
+	for (c = 0; size[c]; c++)
+		for (s = 0; step[s]; s++)
+			benchmark_split(size[c], step[s]);
+
+	for (s = 0; step[s]; s++)
+		benchmark_join(step[s]);
+}
diff --git a/tools/testing/radix-tree/generated/autoconf.h b/tools/testing/radix-tree/generated/autoconf.h
new file mode 100644
index 0000000..cf88dc5
--- /dev/null
+++ b/tools/testing/radix-tree/generated/autoconf.h
@@ -0,0 +1 @@
+#define CONFIG_RADIX_TREE_MULTIORDER 1
diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
new file mode 100644
index 0000000..321ba92
--- /dev/null
+++ b/tools/testing/radix-tree/idr-test.c
@@ -0,0 +1,460 @@
+/*
+ * idr-test.c: Test the IDR API
+ * Copyright (c) 2016 Matthew Wilcox <willy@infradead.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/bitmap.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+
+#include "test.h"
+
+#define DUMMY_PTR	((void *)0x12)
+
+int item_idr_free(int id, void *p, void *data)
+{
+	struct item *item = p;
+	assert(item->index == id);
+	free(p);
+
+	return 0;
+}
+
+void item_idr_remove(struct idr *idr, int id)
+{
+	struct item *item = idr_find(idr, id);
+	assert(item->index == id);
+	idr_remove(idr, id);
+	free(item);
+}
+
+void idr_alloc_test(void)
+{
+	unsigned long i;
+	DEFINE_IDR(idr);
+
+	assert(idr_alloc_cyclic(&idr, DUMMY_PTR, 0, 0x4000, GFP_KERNEL) == 0);
+	assert(idr_alloc_cyclic(&idr, DUMMY_PTR, 0x3ffd, 0x4000, GFP_KERNEL) == 0x3ffd);
+	idr_remove(&idr, 0x3ffd);
+	idr_remove(&idr, 0);
+
+	for (i = 0x3ffe; i < 0x4003; i++) {
+		int id;
+		struct item *item;
+
+		if (i < 0x4000)
+			item = item_create(i, 0);
+		else
+			item = item_create(i - 0x3fff, 0);
+
+		id = idr_alloc_cyclic(&idr, item, 1, 0x4000, GFP_KERNEL);
+		assert(id == item->index);
+	}
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+}
+
+void idr_replace_test(void)
+{
+	DEFINE_IDR(idr);
+
+	idr_alloc(&idr, (void *)-1, 10, 11, GFP_KERNEL);
+	idr_replace(&idr, &idr, 10);
+
+	idr_destroy(&idr);
+}
+
+/*
+ * Unlike the radix tree, you can put a NULL pointer -- with care -- into
+ * the IDR.  Some interfaces, like idr_find() do not distinguish between
+ * "present, value is NULL" and "not present", but that's exactly what some
+ * users want.
+ */
+void idr_null_test(void)
+{
+	int i;
+	DEFINE_IDR(idr);
+
+	assert(idr_is_empty(&idr));
+
+	assert(idr_alloc(&idr, NULL, 0, 0, GFP_KERNEL) == 0);
+	assert(!idr_is_empty(&idr));
+	idr_remove(&idr, 0);
+	assert(idr_is_empty(&idr));
+
+	assert(idr_alloc(&idr, NULL, 0, 0, GFP_KERNEL) == 0);
+	assert(!idr_is_empty(&idr));
+	idr_destroy(&idr);
+	assert(idr_is_empty(&idr));
+
+	for (i = 0; i < 10; i++) {
+		assert(idr_alloc(&idr, NULL, 0, 0, GFP_KERNEL) == i);
+	}
+
+	assert(idr_replace(&idr, DUMMY_PTR, 3) == NULL);
+	assert(idr_replace(&idr, DUMMY_PTR, 4) == NULL);
+	assert(idr_replace(&idr, NULL, 4) == DUMMY_PTR);
+	assert(idr_replace(&idr, DUMMY_PTR, 11) == ERR_PTR(-ENOENT));
+	idr_remove(&idr, 5);
+	assert(idr_alloc(&idr, NULL, 0, 0, GFP_KERNEL) == 5);
+	idr_remove(&idr, 5);
+
+	for (i = 0; i < 9; i++) {
+		idr_remove(&idr, i);
+		assert(!idr_is_empty(&idr));
+	}
+	idr_remove(&idr, 8);
+	assert(!idr_is_empty(&idr));
+	idr_remove(&idr, 9);
+	assert(idr_is_empty(&idr));
+
+	assert(idr_alloc(&idr, NULL, 0, 0, GFP_KERNEL) == 0);
+	assert(idr_replace(&idr, DUMMY_PTR, 3) == ERR_PTR(-ENOENT));
+	assert(idr_replace(&idr, DUMMY_PTR, 0) == NULL);
+	assert(idr_replace(&idr, NULL, 0) == DUMMY_PTR);
+
+	idr_destroy(&idr);
+	assert(idr_is_empty(&idr));
+
+	for (i = 1; i < 10; i++) {
+		assert(idr_alloc(&idr, NULL, 1, 0, GFP_KERNEL) == i);
+	}
+
+	idr_destroy(&idr);
+	assert(idr_is_empty(&idr));
+}
+
+void idr_nowait_test(void)
+{
+	unsigned int i;
+	DEFINE_IDR(idr);
+
+	idr_preload(GFP_KERNEL);
+
+	for (i = 0; i < 3; i++) {
+		struct item *item = item_create(i, 0);
+		assert(idr_alloc(&idr, item, i, i + 1, GFP_NOWAIT) == i);
+	}
+
+	idr_preload_end();
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+}
+
+void idr_get_next_test(int base)
+{
+	unsigned long i;
+	int nextid;
+	DEFINE_IDR(idr);
+	idr_init_base(&idr, base);
+
+	int indices[] = {4, 7, 9, 15, 65, 128, 1000, 99999, 0};
+
+	for(i = 0; indices[i]; i++) {
+		struct item *item = item_create(indices[i], 0);
+		assert(idr_alloc(&idr, item, indices[i], indices[i+1],
+				 GFP_KERNEL) == indices[i]);
+	}
+
+	for(i = 0, nextid = 0; indices[i]; i++) {
+		idr_get_next(&idr, &nextid);
+		assert(nextid == indices[i]);
+		nextid++;
+	}
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+}
+
+int idr_u32_cb(int id, void *ptr, void *data)
+{
+	BUG_ON(id < 0);
+	BUG_ON(ptr != DUMMY_PTR);
+	return 0;
+}
+
+void idr_u32_test1(struct idr *idr, u32 handle)
+{
+	static bool warned = false;
+	u32 id = handle;
+	int sid = 0;
+	void *ptr;
+
+	BUG_ON(idr_alloc_u32(idr, DUMMY_PTR, &id, id, GFP_KERNEL));
+	BUG_ON(id != handle);
+	BUG_ON(idr_alloc_u32(idr, DUMMY_PTR, &id, id, GFP_KERNEL) != -ENOSPC);
+	BUG_ON(id != handle);
+	if (!warned && id > INT_MAX)
+		printk("vvv Ignore these warnings\n");
+	ptr = idr_get_next(idr, &sid);
+	if (id > INT_MAX) {
+		BUG_ON(ptr != NULL);
+		BUG_ON(sid != 0);
+	} else {
+		BUG_ON(ptr != DUMMY_PTR);
+		BUG_ON(sid != id);
+	}
+	idr_for_each(idr, idr_u32_cb, NULL);
+	if (!warned && id > INT_MAX) {
+		printk("^^^ Warnings over\n");
+		warned = true;
+	}
+	BUG_ON(idr_remove(idr, id) != DUMMY_PTR);
+	BUG_ON(!idr_is_empty(idr));
+}
+
+void idr_u32_test(int base)
+{
+	DEFINE_IDR(idr);
+	idr_init_base(&idr, base);
+	idr_u32_test1(&idr, 10);
+	idr_u32_test1(&idr, 0x7fffffff);
+	idr_u32_test1(&idr, 0x80000000);
+	idr_u32_test1(&idr, 0x80000001);
+	idr_u32_test1(&idr, 0xffe00000);
+	idr_u32_test1(&idr, 0xffffffff);
+}
+
+void idr_checks(void)
+{
+	unsigned long i;
+	DEFINE_IDR(idr);
+
+	for (i = 0; i < 10000; i++) {
+		struct item *item = item_create(i, 0);
+		assert(idr_alloc(&idr, item, 0, 20000, GFP_KERNEL) == i);
+	}
+
+	assert(idr_alloc(&idr, DUMMY_PTR, 5, 30, GFP_KERNEL) < 0);
+
+	for (i = 0; i < 5000; i++)
+		item_idr_remove(&idr, i);
+
+	idr_remove(&idr, 3);
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+
+	assert(idr_is_empty(&idr));
+
+	idr_remove(&idr, 3);
+	idr_remove(&idr, 0);
+
+	assert(idr_alloc(&idr, DUMMY_PTR, 0, 0, GFP_KERNEL) == 0);
+	idr_remove(&idr, 1);
+	for (i = 1; i < RADIX_TREE_MAP_SIZE; i++)
+		assert(idr_alloc(&idr, DUMMY_PTR, 0, 0, GFP_KERNEL) == i);
+	idr_remove(&idr, 1 << 30);
+	idr_destroy(&idr);
+
+	for (i = INT_MAX - 3UL; i < INT_MAX + 1UL; i++) {
+		struct item *item = item_create(i, 0);
+		assert(idr_alloc(&idr, item, i, i + 10, GFP_KERNEL) == i);
+	}
+	assert(idr_alloc(&idr, DUMMY_PTR, i - 2, i, GFP_KERNEL) == -ENOSPC);
+	assert(idr_alloc(&idr, DUMMY_PTR, i - 2, i + 10, GFP_KERNEL) == -ENOSPC);
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+	idr_destroy(&idr);
+
+	assert(idr_is_empty(&idr));
+
+	idr_set_cursor(&idr, INT_MAX - 3UL);
+	for (i = INT_MAX - 3UL; i < INT_MAX + 3UL; i++) {
+		struct item *item;
+		unsigned int id;
+		if (i <= INT_MAX)
+			item = item_create(i, 0);
+		else
+			item = item_create(i - INT_MAX - 1, 0);
+
+		id = idr_alloc_cyclic(&idr, item, 0, 0, GFP_KERNEL);
+		assert(id == item->index);
+	}
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+	assert(idr_is_empty(&idr));
+
+	for (i = 1; i < 10000; i++) {
+		struct item *item = item_create(i, 0);
+		assert(idr_alloc(&idr, item, 1, 20000, GFP_KERNEL) == i);
+	}
+
+	idr_for_each(&idr, item_idr_free, &idr);
+	idr_destroy(&idr);
+
+	idr_replace_test();
+	idr_alloc_test();
+	idr_null_test();
+	idr_nowait_test();
+	idr_get_next_test(0);
+	idr_get_next_test(1);
+	idr_get_next_test(4);
+	idr_u32_test(4);
+	idr_u32_test(1);
+	idr_u32_test(0);
+}
+
+#define module_init(x)
+#define module_exit(x)
+#define MODULE_AUTHOR(x)
+#define MODULE_LICENSE(x)
+#define dump_stack()    assert(0)
+void ida_dump(struct ida *);
+
+#include "../../../lib/test_ida.c"
+
+/*
+ * Check that we get the correct error when we run out of memory doing
+ * allocations.  In userspace, GFP_NOWAIT will always fail an allocation.
+ * The first test is for not having a bitmap available, and the second test
+ * is for not being able to allocate a level of the radix tree.
+ */
+void ida_check_nomem(void)
+{
+	DEFINE_IDA(ida);
+	int id;
+
+	id = ida_alloc_min(&ida, 256, GFP_NOWAIT);
+	IDA_BUG_ON(&ida, id != -ENOMEM);
+	id = ida_alloc_min(&ida, 1UL << 30, GFP_NOWAIT);
+	IDA_BUG_ON(&ida, id != -ENOMEM);
+	IDA_BUG_ON(&ida, !ida_is_empty(&ida));
+}
+
+/*
+ * Check handling of conversions between exceptional entries and full bitmaps.
+ */
+void ida_check_conv_user(void)
+{
+	DEFINE_IDA(ida);
+	unsigned long i;
+
+	radix_tree_cpu_dead(1);
+	for (i = 0; i < 1000000; i++) {
+		int id = ida_alloc(&ida, GFP_NOWAIT);
+		if (id == -ENOMEM) {
+			IDA_BUG_ON(&ida, (i % IDA_BITMAP_BITS) !=
+					BITS_PER_LONG - 2);
+			id = ida_alloc(&ida, GFP_KERNEL);
+		} else {
+			IDA_BUG_ON(&ida, (i % IDA_BITMAP_BITS) ==
+					BITS_PER_LONG - 2);
+		}
+		IDA_BUG_ON(&ida, id != i);
+	}
+	ida_destroy(&ida);
+}
+
+void ida_check_random(void)
+{
+	DEFINE_IDA(ida);
+	DECLARE_BITMAP(bitmap, 2048);
+	unsigned int i;
+	time_t s = time(NULL);
+
+ repeat:
+	memset(bitmap, 0, sizeof(bitmap));
+	for (i = 0; i < 100000; i++) {
+		int i = rand();
+		int bit = i & 2047;
+		if (test_bit(bit, bitmap)) {
+			__clear_bit(bit, bitmap);
+			ida_free(&ida, bit);
+		} else {
+			__set_bit(bit, bitmap);
+			IDA_BUG_ON(&ida, ida_alloc_min(&ida, bit, GFP_KERNEL)
+					!= bit);
+		}
+	}
+	ida_destroy(&ida);
+	if (time(NULL) < s + 10)
+		goto repeat;
+}
+
+void ida_simple_get_remove_test(void)
+{
+	DEFINE_IDA(ida);
+	unsigned long i;
+
+	for (i = 0; i < 10000; i++) {
+		assert(ida_simple_get(&ida, 0, 20000, GFP_KERNEL) == i);
+	}
+	assert(ida_simple_get(&ida, 5, 30, GFP_KERNEL) < 0);
+
+	for (i = 0; i < 10000; i++) {
+		ida_simple_remove(&ida, i);
+	}
+	assert(ida_is_empty(&ida));
+
+	ida_destroy(&ida);
+}
+
+void user_ida_checks(void)
+{
+	radix_tree_cpu_dead(1);
+
+	ida_check_nomem();
+	ida_check_conv_user();
+	ida_check_random();
+	ida_simple_get_remove_test();
+
+	radix_tree_cpu_dead(1);
+}
+
+static void *ida_random_fn(void *arg)
+{
+	rcu_register_thread();
+	ida_check_random();
+	rcu_unregister_thread();
+	return NULL;
+}
+
+void ida_thread_tests(void)
+{
+	pthread_t threads[20];
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(threads); i++)
+		if (pthread_create(&threads[i], NULL, ida_random_fn, NULL)) {
+			perror("creating ida thread");
+			exit(1);
+		}
+
+	while (i--)
+		pthread_join(threads[i], NULL);
+}
+
+void ida_tests(void)
+{
+	user_ida_checks();
+	ida_checks();
+	ida_exit();
+	ida_thread_tests();
+}
+
+int __weak main(void)
+{
+	radix_tree_init();
+	idr_checks();
+	ida_tests();
+	radix_tree_cpu_dead(1);
+	rcu_barrier();
+	if (nr_allocated)
+		printf("nr_allocated = %d\n", nr_allocated);
+	return 0;
+}
diff --git a/tools/testing/radix-tree/iteration_check.c b/tools/testing/radix-tree/iteration_check.c
new file mode 100644
index 0000000..a92bab5
--- /dev/null
+++ b/tools/testing/radix-tree/iteration_check.c
@@ -0,0 +1,221 @@
+/*
+ * iteration_check.c: test races having to do with radix tree iteration
+ * Copyright (c) 2016 Intel Corporation
+ * Author: Ross Zwisler <ross.zwisler@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/radix-tree.h>
+#include <pthread.h>
+#include "test.h"
+
+#define NUM_THREADS	5
+#define MAX_IDX		100
+#define TAG		0
+#define NEW_TAG		1
+
+static pthread_mutex_t tree_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_t threads[NUM_THREADS];
+static unsigned int seeds[3];
+static RADIX_TREE(tree, GFP_KERNEL);
+static bool test_complete;
+static int max_order;
+
+/* relentlessly fill the tree with tagged entries */
+static void *add_entries_fn(void *arg)
+{
+	rcu_register_thread();
+
+	while (!test_complete) {
+		unsigned long pgoff;
+		int order;
+
+		for (pgoff = 0; pgoff < MAX_IDX; pgoff++) {
+			pthread_mutex_lock(&tree_lock);
+			for (order = max_order; order >= 0; order--) {
+				if (item_insert_order(&tree, pgoff, order)
+						== 0) {
+					item_tag_set(&tree, pgoff, TAG);
+					break;
+				}
+			}
+			pthread_mutex_unlock(&tree_lock);
+		}
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+/*
+ * Iterate over the tagged entries, doing a radix_tree_iter_retry() as we find
+ * things that have been removed and randomly resetting our iteration to the
+ * next chunk with radix_tree_iter_resume().  Both radix_tree_iter_retry() and
+ * radix_tree_iter_resume() cause radix_tree_next_slot() to be called with a
+ * NULL 'slot' variable.
+ */
+static void *tagged_iteration_fn(void *arg)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+
+	rcu_register_thread();
+
+	while (!test_complete) {
+		rcu_read_lock();
+		radix_tree_for_each_tagged(slot, &tree, &iter, 0, TAG) {
+			void *entry = radix_tree_deref_slot(slot);
+			if (unlikely(!entry))
+				continue;
+
+			if (radix_tree_deref_retry(entry)) {
+				slot = radix_tree_iter_retry(&iter);
+				continue;
+			}
+
+			if (rand_r(&seeds[0]) % 50 == 0) {
+				slot = radix_tree_iter_resume(slot, &iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+/*
+ * Iterate over the entries, doing a radix_tree_iter_retry() as we find things
+ * that have been removed and randomly resetting our iteration to the next
+ * chunk with radix_tree_iter_resume().  Both radix_tree_iter_retry() and
+ * radix_tree_iter_resume() cause radix_tree_next_slot() to be called with a
+ * NULL 'slot' variable.
+ */
+static void *untagged_iteration_fn(void *arg)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+
+	rcu_register_thread();
+
+	while (!test_complete) {
+		rcu_read_lock();
+		radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+			void *entry = radix_tree_deref_slot(slot);
+			if (unlikely(!entry))
+				continue;
+
+			if (radix_tree_deref_retry(entry)) {
+				slot = radix_tree_iter_retry(&iter);
+				continue;
+			}
+
+			if (rand_r(&seeds[1]) % 50 == 0) {
+				slot = radix_tree_iter_resume(slot, &iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+/*
+ * Randomly remove entries to help induce radix_tree_iter_retry() calls in the
+ * two iteration functions.
+ */
+static void *remove_entries_fn(void *arg)
+{
+	rcu_register_thread();
+
+	while (!test_complete) {
+		int pgoff;
+
+		pgoff = rand_r(&seeds[2]) % MAX_IDX;
+
+		pthread_mutex_lock(&tree_lock);
+		item_delete(&tree, pgoff);
+		pthread_mutex_unlock(&tree_lock);
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+static void *tag_entries_fn(void *arg)
+{
+	rcu_register_thread();
+
+	while (!test_complete) {
+		tag_tagged_items(&tree, &tree_lock, 0, MAX_IDX, 10, TAG,
+					NEW_TAG);
+	}
+	rcu_unregister_thread();
+	return NULL;
+}
+
+/* This is a unit test for a bug found by the syzkaller tester */
+void iteration_test(unsigned order, unsigned test_duration)
+{
+	int i;
+
+	printv(1, "Running %siteration tests for %d seconds\n",
+			order > 0 ? "multiorder " : "", test_duration);
+
+	max_order = order;
+	test_complete = false;
+
+	for (i = 0; i < 3; i++)
+		seeds[i] = rand();
+
+	if (pthread_create(&threads[0], NULL, tagged_iteration_fn, NULL)) {
+		perror("create tagged iteration thread");
+		exit(1);
+	}
+	if (pthread_create(&threads[1], NULL, untagged_iteration_fn, NULL)) {
+		perror("create untagged iteration thread");
+		exit(1);
+	}
+	if (pthread_create(&threads[2], NULL, add_entries_fn, NULL)) {
+		perror("create add entry thread");
+		exit(1);
+	}
+	if (pthread_create(&threads[3], NULL, remove_entries_fn, NULL)) {
+		perror("create remove entry thread");
+		exit(1);
+	}
+	if (pthread_create(&threads[4], NULL, tag_entries_fn, NULL)) {
+		perror("create tag entry thread");
+		exit(1);
+	}
+
+	sleep(test_duration);
+	test_complete = true;
+
+	for (i = 0; i < NUM_THREADS; i++) {
+		if (pthread_join(threads[i], NULL)) {
+			perror("pthread_join");
+			exit(1);
+		}
+	}
+
+	item_kill_tree(&tree);
+}
diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
new file mode 100644
index 0000000..44a0d1a
--- /dev/null
+++ b/tools/testing/radix-tree/linux.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
+#include <string.h>
+#include <malloc.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <assert.h>
+
+#include <linux/gfp.h>
+#include <linux/poison.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <urcu/uatomic.h>
+
+int nr_allocated;
+int preempt_count;
+int kmalloc_verbose;
+int test_verbose;
+
+struct kmem_cache {
+	pthread_mutex_t lock;
+	int size;
+	int nr_objs;
+	void *objs;
+	void (*ctor)(void *);
+};
+
+void *kmem_cache_alloc(struct kmem_cache *cachep, int flags)
+{
+	struct radix_tree_node *node;
+
+	if (!(flags & __GFP_DIRECT_RECLAIM))
+		return NULL;
+
+	pthread_mutex_lock(&cachep->lock);
+	if (cachep->nr_objs) {
+		cachep->nr_objs--;
+		node = cachep->objs;
+		cachep->objs = node->parent;
+		pthread_mutex_unlock(&cachep->lock);
+		node->parent = NULL;
+	} else {
+		pthread_mutex_unlock(&cachep->lock);
+		node = malloc(cachep->size);
+		if (cachep->ctor)
+			cachep->ctor(node);
+	}
+
+	uatomic_inc(&nr_allocated);
+	if (kmalloc_verbose)
+		printf("Allocating %p from slab\n", node);
+	return node;
+}
+
+void kmem_cache_free(struct kmem_cache *cachep, void *objp)
+{
+	assert(objp);
+	uatomic_dec(&nr_allocated);
+	if (kmalloc_verbose)
+		printf("Freeing %p to slab\n", objp);
+	pthread_mutex_lock(&cachep->lock);
+	if (cachep->nr_objs > 10) {
+		memset(objp, POISON_FREE, cachep->size);
+		free(objp);
+	} else {
+		struct radix_tree_node *node = objp;
+		cachep->nr_objs++;
+		node->parent = cachep->objs;
+		cachep->objs = node;
+	}
+	pthread_mutex_unlock(&cachep->lock);
+}
+
+void *kmalloc(size_t size, gfp_t gfp)
+{
+	void *ret;
+
+	if (!(gfp & __GFP_DIRECT_RECLAIM))
+		return NULL;
+
+	ret = malloc(size);
+	uatomic_inc(&nr_allocated);
+	if (kmalloc_verbose)
+		printf("Allocating %p from malloc\n", ret);
+	if (gfp & __GFP_ZERO)
+		memset(ret, 0, size);
+	return ret;
+}
+
+void kfree(void *p)
+{
+	if (!p)
+		return;
+	uatomic_dec(&nr_allocated);
+	if (kmalloc_verbose)
+		printf("Freeing %p to malloc\n", p);
+	free(p);
+}
+
+struct kmem_cache *
+kmem_cache_create(const char *name, size_t size, size_t offset,
+	unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *ret = malloc(sizeof(*ret));
+
+	pthread_mutex_init(&ret->lock, NULL);
+	ret->size = size;
+	ret->nr_objs = 0;
+	ret->objs = NULL;
+	ret->ctor = ctor;
+	return ret;
+}
diff --git a/tools/testing/radix-tree/linux/bug.h b/tools/testing/radix-tree/linux/bug.h
new file mode 100644
index 0000000..23b8ed5
--- /dev/null
+++ b/tools/testing/radix-tree/linux/bug.h
@@ -0,0 +1 @@
+#include "asm/bug.h"
diff --git a/tools/testing/radix-tree/linux/compiler_types.h b/tools/testing/radix-tree/linux/compiler_types.h
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tools/testing/radix-tree/linux/compiler_types.h
diff --git a/tools/testing/radix-tree/linux/cpu.h b/tools/testing/radix-tree/linux/cpu.h
new file mode 100644
index 0000000..a45530d
--- /dev/null
+++ b/tools/testing/radix-tree/linux/cpu.h
@@ -0,0 +1 @@
+#define cpuhp_setup_state_nocalls(a, b, c, d)	(0)
diff --git a/tools/testing/radix-tree/linux/gfp.h b/tools/testing/radix-tree/linux/gfp.h
new file mode 100644
index 0000000..32159c0
--- /dev/null
+++ b/tools/testing/radix-tree/linux/gfp.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _GFP_H
+#define _GFP_H
+
+#include <linux/types.h>
+
+#define __GFP_BITS_SHIFT 26
+#define __GFP_BITS_MASK ((gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
+
+#define __GFP_HIGH		0x20u
+#define __GFP_IO		0x40u
+#define __GFP_FS		0x80u
+#define __GFP_NOWARN		0x200u
+#define __GFP_ZERO		0x8000u
+#define __GFP_ATOMIC		0x80000u
+#define __GFP_ACCOUNT		0x100000u
+#define __GFP_DIRECT_RECLAIM	0x400000u
+#define __GFP_KSWAPD_RECLAIM	0x2000000u
+
+#define __GFP_RECLAIM	(__GFP_DIRECT_RECLAIM|__GFP_KSWAPD_RECLAIM)
+
+#define GFP_ZONEMASK	0x0fu
+#define GFP_ATOMIC	(__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
+#define GFP_KERNEL	(__GFP_RECLAIM | __GFP_IO | __GFP_FS)
+#define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM)
+
+
+static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
+{
+	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
+}
+
+#endif
diff --git a/tools/testing/radix-tree/linux/idr.h b/tools/testing/radix-tree/linux/idr.h
new file mode 100644
index 0000000..4e342f2
--- /dev/null
+++ b/tools/testing/radix-tree/linux/idr.h
@@ -0,0 +1 @@
+#include "../../../../include/linux/idr.h"
diff --git a/tools/testing/radix-tree/linux/init.h b/tools/testing/radix-tree/linux/init.h
new file mode 100644
index 0000000..1bb0afc
--- /dev/null
+++ b/tools/testing/radix-tree/linux/init.h
@@ -0,0 +1 @@
+#define __init
diff --git a/tools/testing/radix-tree/linux/kernel.h b/tools/testing/radix-tree/linux/kernel.h
new file mode 100644
index 0000000..426f32f
--- /dev/null
+++ b/tools/testing/radix-tree/linux/kernel.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _KERNEL_H
+#define _KERNEL_H
+
+#include "../../include/linux/kernel.h"
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+
+#include <linux/compiler.h>
+#include <linux/err.h>
+#include <linux/bitops.h>
+#include <linux/log2.h>
+#include "../../../include/linux/kconfig.h"
+
+#define printk printf
+#define pr_debug printk
+#define pr_cont printk
+
+#endif /* _KERNEL_H */
diff --git a/tools/testing/radix-tree/linux/kmemleak.h b/tools/testing/radix-tree/linux/kmemleak.h
new file mode 100644
index 0000000..155f112
--- /dev/null
+++ b/tools/testing/radix-tree/linux/kmemleak.h
@@ -0,0 +1 @@
+static inline void kmemleak_update_trace(const void *ptr) { }
diff --git a/tools/testing/radix-tree/linux/percpu.h b/tools/testing/radix-tree/linux/percpu.h
new file mode 100644
index 0000000..b2403aa
--- /dev/null
+++ b/tools/testing/radix-tree/linux/percpu.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#define DECLARE_PER_CPU(type, val) extern type val
+#define DEFINE_PER_CPU(type, val) type val
+
+#define __get_cpu_var(var)	var
+#define this_cpu_ptr(var)	var
+#define this_cpu_read(var)	var
+#define this_cpu_xchg(var, val)		uatomic_xchg(&var, val)
+#define this_cpu_cmpxchg(var, old, new)	uatomic_cmpxchg(&var, old, new)
+#define per_cpu_ptr(ptr, cpu)   ({ (void)(cpu); (ptr); })
+#define per_cpu(var, cpu)	(*per_cpu_ptr(&(var), cpu))
diff --git a/tools/testing/radix-tree/linux/preempt.h b/tools/testing/radix-tree/linux/preempt.h
new file mode 100644
index 0000000..edb1030
--- /dev/null
+++ b/tools/testing/radix-tree/linux/preempt.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_PREEMPT_H
+#define __LINUX_PREEMPT_H
+
+extern int preempt_count;
+
+#define preempt_disable()	uatomic_inc(&preempt_count)
+#define preempt_enable()	uatomic_dec(&preempt_count)
+
+static inline int in_interrupt(void)
+{
+	return 0;
+}
+
+#endif /* __LINUX_PREEMPT_H */
diff --git a/tools/testing/radix-tree/linux/radix-tree.h b/tools/testing/radix-tree/linux/radix-tree.h
new file mode 100644
index 0000000..24f13d2
--- /dev/null
+++ b/tools/testing/radix-tree/linux/radix-tree.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TEST_RADIX_TREE_H
+#define _TEST_RADIX_TREE_H
+
+#include "generated/map-shift.h"
+#include "../../../../include/linux/radix-tree.h"
+
+extern int kmalloc_verbose;
+extern int test_verbose;
+
+static inline void trace_call_rcu(struct rcu_head *head,
+		void (*func)(struct rcu_head *head))
+{
+	if (kmalloc_verbose)
+		printf("Delaying free of %p to slab\n", (char *)head -
+				offsetof(struct radix_tree_node, rcu_head));
+	call_rcu(head, func);
+}
+
+#define printv(verbosity_level, fmt, ...) \
+	if(test_verbose >= verbosity_level) \
+		printf(fmt, ##__VA_ARGS__)
+
+#undef call_rcu
+#define call_rcu(x, y) trace_call_rcu(x, y)
+
+#endif /* _TEST_RADIX_TREE_H */
diff --git a/tools/testing/radix-tree/linux/rcupdate.h b/tools/testing/radix-tree/linux/rcupdate.h
new file mode 100644
index 0000000..73ed336
--- /dev/null
+++ b/tools/testing/radix-tree/linux/rcupdate.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _RCUPDATE_H
+#define _RCUPDATE_H
+
+#include <urcu.h>
+
+#define rcu_dereference_raw(p) rcu_dereference(p)
+#define rcu_dereference_protected(p, cond) rcu_dereference(p)
+
+#endif
diff --git a/tools/testing/radix-tree/linux/slab.h b/tools/testing/radix-tree/linux/slab.h
new file mode 100644
index 0000000..a037def
--- /dev/null
+++ b/tools/testing/radix-tree/linux/slab.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SLAB_H
+#define SLAB_H
+
+#include <linux/types.h>
+#include <linux/gfp.h>
+
+#define SLAB_HWCACHE_ALIGN 1
+#define SLAB_PANIC 2
+#define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
+
+void *kmalloc(size_t size, gfp_t);
+void kfree(void *);
+
+static inline void *kzalloc(size_t size, gfp_t gfp)
+{
+        return kmalloc(size, gfp | __GFP_ZERO);
+}
+
+void *kmem_cache_alloc(struct kmem_cache *cachep, int flags);
+void kmem_cache_free(struct kmem_cache *cachep, void *objp);
+
+struct kmem_cache *
+kmem_cache_create(const char *name, size_t size, size_t offset,
+	unsigned long flags, void (*ctor)(void *));
+
+#endif		/* SLAB_H */
diff --git a/tools/testing/radix-tree/linux/xarray.h b/tools/testing/radix-tree/linux/xarray.h
new file mode 100644
index 0000000..df3812c
--- /dev/null
+++ b/tools/testing/radix-tree/linux/xarray.h
@@ -0,0 +1,2 @@
+#include "generated/map-shift.h"
+#include "../../../../include/linux/xarray.h"
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
new file mode 100644
index 0000000..b741686
--- /dev/null
+++ b/tools/testing/radix-tree/main.c
@@ -0,0 +1,388 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <assert.h>
+#include <limits.h>
+
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+
+#include "test.h"
+#include "regression.h"
+
+void __gang_check(unsigned long middle, long down, long up, int chunk, int hop)
+{
+	long idx;
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	middle = 1 << 30;
+
+	for (idx = -down; idx < up; idx++)
+		item_insert(&tree, middle + idx);
+
+	item_check_absent(&tree, middle - down - 1);
+	for (idx = -down; idx < up; idx++)
+		item_check_present(&tree, middle + idx);
+	item_check_absent(&tree, middle + up);
+
+	if (chunk > 0) {
+		item_gang_check_present(&tree, middle - down, up + down,
+				chunk, hop);
+		item_full_scan(&tree, middle - down, down + up, chunk);
+	}
+	item_kill_tree(&tree);
+}
+
+void gang_check(void)
+{
+	__gang_check(1UL << 30, 128, 128, 35, 2);
+	__gang_check(1UL << 31, 128, 128, 32, 32);
+	__gang_check(1UL << 31, 128, 128, 32, 100);
+	__gang_check(1UL << 31, 128, 128, 17, 7);
+	__gang_check(0xffff0000UL, 0, 65536, 17, 7);
+	__gang_check(0xfffffffeUL, 1, 1, 17, 7);
+}
+
+void __big_gang_check(void)
+{
+	unsigned long start;
+	int wrapped = 0;
+
+	start = 0;
+	do {
+		unsigned long old_start;
+
+//		printf("0x%08lx\n", start);
+		__gang_check(start, rand() % 113 + 1, rand() % 71,
+				rand() % 157, rand() % 91 + 1);
+		old_start = start;
+		start += rand() % 1000000;
+		start %= 1ULL << 33;
+		if (start < old_start)
+			wrapped = 1;
+	} while (!wrapped);
+}
+
+void big_gang_check(bool long_run)
+{
+	int i;
+
+	for (i = 0; i < (long_run ? 1000 : 3); i++) {
+		__big_gang_check();
+		printv(2, "%d ", i);
+		fflush(stdout);
+	}
+}
+
+void add_and_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 44);
+	item_check_present(&tree, 44);
+	item_check_absent(&tree, 43);
+	item_kill_tree(&tree);
+}
+
+void dynamic_height_check(void)
+{
+	int i;
+	RADIX_TREE(tree, GFP_KERNEL);
+	tree_verify_min_height(&tree, 0);
+
+	item_insert(&tree, 42);
+	tree_verify_min_height(&tree, 42);
+
+	item_insert(&tree, 1000000);
+	tree_verify_min_height(&tree, 1000000);
+
+	assert(item_delete(&tree, 1000000));
+	tree_verify_min_height(&tree, 42);
+
+	assert(item_delete(&tree, 42));
+	tree_verify_min_height(&tree, 0);
+
+	for (i = 0; i < 1000; i++) {
+		item_insert(&tree, i);
+		tree_verify_min_height(&tree, i);
+	}
+
+	i--;
+	for (;;) {
+		assert(item_delete(&tree, i));
+		if (i == 0) {
+			tree_verify_min_height(&tree, 0);
+			break;
+		}
+		i--;
+		tree_verify_min_height(&tree, i);
+	}
+
+	item_kill_tree(&tree);
+}
+
+void check_copied_tags(struct radix_tree_root *tree, unsigned long start, unsigned long end, unsigned long *idx, int count, int fromtag, int totag)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+/*		if (i % 1000 == 0)
+			putchar('.'); */
+		if (idx[i] < start || idx[i] > end) {
+			if (item_tag_get(tree, idx[i], totag)) {
+				printv(2, "%lu-%lu: %lu, tags %d-%d\n", start,
+				       end, idx[i], item_tag_get(tree, idx[i],
+								 fromtag),
+				       item_tag_get(tree, idx[i], totag));
+			}
+			assert(!item_tag_get(tree, idx[i], totag));
+			continue;
+		}
+		if (item_tag_get(tree, idx[i], fromtag) ^
+			item_tag_get(tree, idx[i], totag)) {
+			printv(2, "%lu-%lu: %lu, tags %d-%d\n", start, end,
+			       idx[i], item_tag_get(tree, idx[i], fromtag),
+			       item_tag_get(tree, idx[i], totag));
+		}
+		assert(!(item_tag_get(tree, idx[i], fromtag) ^
+			 item_tag_get(tree, idx[i], totag)));
+	}
+}
+
+#define ITEMS 50000
+
+void copy_tag_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	unsigned long idx[ITEMS];
+	unsigned long start, end, count = 0, tagged, cur, tmp;
+	int i;
+
+//	printf("generating radix tree indices...\n");
+	start = rand();
+	end = rand();
+	if (start > end && (rand() % 10)) {
+		cur = start;
+		start = end;
+		end = cur;
+	}
+	/* Specifically create items around the start and the end of the range
+	 * with high probability to check for off by one errors */
+	cur = rand();
+	if (cur & 1) {
+		item_insert(&tree, start);
+		if (cur & 2) {
+			if (start <= end)
+				count++;
+			item_tag_set(&tree, start, 0);
+		}
+	}
+	if (cur & 4) {
+		item_insert(&tree, start-1);
+		if (cur & 8)
+			item_tag_set(&tree, start-1, 0);
+	}
+	if (cur & 16) {
+		item_insert(&tree, end);
+		if (cur & 32) {
+			if (start <= end)
+				count++;
+			item_tag_set(&tree, end, 0);
+		}
+	}
+	if (cur & 64) {
+		item_insert(&tree, end+1);
+		if (cur & 128)
+			item_tag_set(&tree, end+1, 0);
+	}
+
+	for (i = 0; i < ITEMS; i++) {
+		do {
+			idx[i] = rand();
+		} while (item_lookup(&tree, idx[i]));
+
+		item_insert(&tree, idx[i]);
+		if (rand() & 1) {
+			item_tag_set(&tree, idx[i], 0);
+			if (idx[i] >= start && idx[i] <= end)
+				count++;
+		}
+/*		if (i % 1000 == 0)
+			putchar('.'); */
+	}
+
+//	printf("\ncopying tags...\n");
+	tagged = tag_tagged_items(&tree, NULL, start, end, ITEMS, 0, 1);
+
+//	printf("checking copied tags\n");
+	assert(tagged == count);
+	check_copied_tags(&tree, start, end, idx, ITEMS, 0, 1);
+
+	/* Copy tags in several rounds */
+//	printf("\ncopying tags...\n");
+	tmp = rand() % (count / 10 + 2);
+	tagged = tag_tagged_items(&tree, NULL, start, end, tmp, 0, 2);
+	assert(tagged == count);
+
+//	printf("%lu %lu %lu\n", tagged, tmp, count);
+//	printf("checking copied tags\n");
+	check_copied_tags(&tree, start, end, idx, ITEMS, 0, 2);
+	verify_tag_consistency(&tree, 0);
+	verify_tag_consistency(&tree, 1);
+	verify_tag_consistency(&tree, 2);
+//	printf("\n");
+	item_kill_tree(&tree);
+}
+
+static void __locate_check(struct radix_tree_root *tree, unsigned long index,
+			unsigned order)
+{
+	struct item *item;
+	unsigned long index2;
+
+	item_insert_order(tree, index, order);
+	item = item_lookup(tree, index);
+	index2 = find_item(tree, item);
+	if (index != index2) {
+		printv(2, "index %ld order %d inserted; found %ld\n",
+			index, order, index2);
+		abort();
+	}
+}
+
+static void __order_0_locate_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	int i;
+
+	for (i = 0; i < 50; i++)
+		__locate_check(&tree, rand() % INT_MAX, 0);
+
+	item_kill_tree(&tree);
+}
+
+static void locate_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	unsigned order;
+	unsigned long offset, index;
+
+	__order_0_locate_check();
+
+	for (order = 0; order < 20; order++) {
+		for (offset = 0; offset < (1 << (order + 3));
+		     offset += (1UL << order)) {
+			for (index = 0; index < (1UL << (order + 5));
+			     index += (1UL << order)) {
+				__locate_check(&tree, index + offset, order);
+			}
+			if (find_item(&tree, &tree) != -1)
+				abort();
+
+			item_kill_tree(&tree);
+		}
+	}
+
+	if (find_item(&tree, &tree) != -1)
+		abort();
+	__locate_check(&tree, -1, 0);
+	if (find_item(&tree, &tree) != -1)
+		abort();
+	item_kill_tree(&tree);
+}
+
+static void single_thread_tests(bool long_run)
+{
+	int i;
+
+	printv(1, "starting single_thread_tests: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	multiorder_checks();
+	rcu_barrier();
+	printv(2, "after multiorder_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	locate_check();
+	rcu_barrier();
+	printv(2, "after locate_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	tag_check();
+	rcu_barrier();
+	printv(2, "after tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	gang_check();
+	rcu_barrier();
+	printv(2, "after gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	add_and_check();
+	rcu_barrier();
+	printv(2, "after add_and_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	dynamic_height_check();
+	rcu_barrier();
+	printv(2, "after dynamic_height_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	idr_checks();
+	ida_tests();
+	rcu_barrier();
+	printv(2, "after idr_checks: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	big_gang_check(long_run);
+	rcu_barrier();
+	printv(2, "after big_gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	for (i = 0; i < (long_run ? 2000 : 3); i++) {
+		copy_tag_check();
+		printv(2, "%d ", i);
+		fflush(stdout);
+	}
+	rcu_barrier();
+	printv(2, "after copy_tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+}
+
+int main(int argc, char **argv)
+{
+	bool long_run = false;
+	int opt;
+	unsigned int seed = time(NULL);
+
+	while ((opt = getopt(argc, argv, "ls:v")) != -1) {
+		if (opt == 'l')
+			long_run = true;
+		else if (opt == 's')
+			seed = strtoul(optarg, NULL, 0);
+		else if (opt == 'v')
+			test_verbose++;
+	}
+
+	printf("random seed %u\n", seed);
+	srand(seed);
+
+	printf("running tests\n");
+
+	rcu_register_thread();
+	radix_tree_init();
+
+	regression1_test();
+	regression2_test();
+	regression3_test();
+	iteration_test(0, 10 + 90 * long_run);
+	iteration_test(7, 10 + 90 * long_run);
+	single_thread_tests(long_run);
+
+	/* Free any remaining preallocated nodes */
+	radix_tree_cpu_dead(0);
+
+	benchmark();
+
+	rcu_barrier();
+	printv(2, "after rcu_barrier: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
+	rcu_unregister_thread();
+
+	printf("tests completed\n");
+
+	exit(0);
+}
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
new file mode 100644
index 0000000..7bf4056
--- /dev/null
+++ b/tools/testing/radix-tree/multiorder.c
@@ -0,0 +1,719 @@
+/*
+ * multiorder.c: Multi-order radix tree entry testing
+ * Copyright (c) 2016 Intel Corporation
+ * Author: Ross Zwisler <ross.zwisler@linux.intel.com>
+ * Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/radix-tree.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <pthread.h>
+
+#include "test.h"
+
+#define for_each_index(i, base, order) \
+	for (i = base; i < base + (1 << order); i++)
+
+static void __multiorder_tag_test(int index, int order)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	int base, err, i;
+
+	/* our canonical entry */
+	base = index & ~((1 << order) - 1);
+
+	printv(2, "Multiorder tag test with index %d, canonical entry %d\n",
+			index, base);
+
+	err = item_insert_order(&tree, index, order);
+	assert(!err);
+
+	/*
+	 * Verify we get collisions for covered indices.  We try and fail to
+	 * insert an exceptional entry so we don't leak memory via
+	 * item_insert_order().
+	 */
+	for_each_index(i, base, order) {
+		err = __radix_tree_insert(&tree, i, order,
+				(void *)(0xA0 | RADIX_TREE_EXCEPTIONAL_ENTRY));
+		assert(err == -EEXIST);
+	}
+
+	for_each_index(i, base, order) {
+		assert(!radix_tree_tag_get(&tree, i, 0));
+		assert(!radix_tree_tag_get(&tree, i, 1));
+	}
+
+	assert(radix_tree_tag_set(&tree, index, 0));
+
+	for_each_index(i, base, order) {
+		assert(radix_tree_tag_get(&tree, i, 0));
+		assert(!radix_tree_tag_get(&tree, i, 1));
+	}
+
+	assert(tag_tagged_items(&tree, NULL, 0, ~0UL, 10, 0, 1) == 1);
+	assert(radix_tree_tag_clear(&tree, index, 0));
+
+	for_each_index(i, base, order) {
+		assert(!radix_tree_tag_get(&tree, i, 0));
+		assert(radix_tree_tag_get(&tree, i, 1));
+	}
+
+	assert(radix_tree_tag_clear(&tree, index, 1));
+
+	assert(!radix_tree_tagged(&tree, 0));
+	assert(!radix_tree_tagged(&tree, 1));
+
+	item_kill_tree(&tree);
+}
+
+static void __multiorder_tag_test2(unsigned order, unsigned long index2)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	unsigned long index = (1 << order);
+	index2 += index;
+
+	assert(item_insert_order(&tree, 0, order) == 0);
+	assert(item_insert(&tree, index2) == 0);
+
+	assert(radix_tree_tag_set(&tree, 0, 0));
+	assert(radix_tree_tag_set(&tree, index2, 0));
+
+	assert(tag_tagged_items(&tree, NULL, 0, ~0UL, 10, 0, 1) == 2);
+
+	item_kill_tree(&tree);
+}
+
+static void multiorder_tag_tests(void)
+{
+	int i, j;
+
+	/* test multi-order entry for indices 0-7 with no sibling pointers */
+	__multiorder_tag_test(0, 3);
+	__multiorder_tag_test(5, 3);
+
+	/* test multi-order entry for indices 8-15 with no sibling pointers */
+	__multiorder_tag_test(8, 3);
+	__multiorder_tag_test(15, 3);
+
+	/*
+	 * Our order 5 entry covers indices 0-31 in a tree with height=2.
+	 * This is broken up as follows:
+	 * 0-7:		canonical entry
+	 * 8-15:	sibling 1
+	 * 16-23:	sibling 2
+	 * 24-31:	sibling 3
+	 */
+	__multiorder_tag_test(0, 5);
+	__multiorder_tag_test(29, 5);
+
+	/* same test, but with indices 32-63 */
+	__multiorder_tag_test(32, 5);
+	__multiorder_tag_test(44, 5);
+
+	/*
+	 * Our order 8 entry covers indices 0-255 in a tree with height=3.
+	 * This is broken up as follows:
+	 * 0-63:	canonical entry
+	 * 64-127:	sibling 1
+	 * 128-191:	sibling 2
+	 * 192-255:	sibling 3
+	 */
+	__multiorder_tag_test(0, 8);
+	__multiorder_tag_test(190, 8);
+
+	/* same test, but with indices 256-511 */
+	__multiorder_tag_test(256, 8);
+	__multiorder_tag_test(300, 8);
+
+	__multiorder_tag_test(0x12345678UL, 8);
+
+	for (i = 1; i < 10; i++)
+		for (j = 0; j < (10 << i); j++)
+			__multiorder_tag_test2(i, j);
+}
+
+static void multiorder_check(unsigned long index, int order)
+{
+	unsigned long i;
+	unsigned long min = index & ~((1UL << order) - 1);
+	unsigned long max = min + (1UL << order);
+	void **slot;
+	struct item *item2 = item_create(min, order);
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	printv(2, "Multiorder index %ld, order %d\n", index, order);
+
+	assert(item_insert_order(&tree, index, order) == 0);
+
+	for (i = min; i < max; i++) {
+		struct item *item = item_lookup(&tree, i);
+		assert(item != 0);
+		assert(item->index == index);
+	}
+	for (i = 0; i < min; i++)
+		item_check_absent(&tree, i);
+	for (i = max; i < 2*max; i++)
+		item_check_absent(&tree, i);
+	for (i = min; i < max; i++)
+		assert(radix_tree_insert(&tree, i, item2) == -EEXIST);
+
+	slot = radix_tree_lookup_slot(&tree, index);
+	free(*slot);
+	radix_tree_replace_slot(&tree, slot, item2);
+	for (i = min; i < max; i++) {
+		struct item *item = item_lookup(&tree, i);
+		assert(item != 0);
+		assert(item->index == min);
+	}
+
+	assert(item_delete(&tree, min) != 0);
+
+	for (i = 0; i < 2*max; i++)
+		item_check_absent(&tree, i);
+}
+
+static void multiorder_shrink(unsigned long index, int order)
+{
+	unsigned long i;
+	unsigned long max = 1 << order;
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_node *node;
+
+	printv(2, "Multiorder shrink index %ld, order %d\n", index, order);
+
+	assert(item_insert_order(&tree, 0, order) == 0);
+
+	node = tree.rnode;
+
+	assert(item_insert(&tree, index) == 0);
+	assert(node != tree.rnode);
+
+	assert(item_delete(&tree, index) != 0);
+	assert(node == tree.rnode);
+
+	for (i = 0; i < max; i++) {
+		struct item *item = item_lookup(&tree, i);
+		assert(item != 0);
+		assert(item->index == 0);
+	}
+	for (i = max; i < 2*max; i++)
+		item_check_absent(&tree, i);
+
+	if (!item_delete(&tree, 0)) {
+		printv(2, "failed to delete index %ld (order %d)\n", index, order);
+		abort();
+	}
+
+	for (i = 0; i < 2*max; i++)
+		item_check_absent(&tree, i);
+}
+
+static void multiorder_insert_bug(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 0);
+	radix_tree_tag_set(&tree, 0, 0);
+	item_insert_order(&tree, 3 << 6, 6);
+
+	item_kill_tree(&tree);
+}
+
+void multiorder_iteration(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_iter iter;
+	void **slot;
+	int i, j, err;
+
+	printv(1, "Multiorder iteration test\n");
+
+#define NUM_ENTRIES 11
+	int index[NUM_ENTRIES] = {0, 2, 4, 8, 16, 32, 34, 36, 64, 72, 128};
+	int order[NUM_ENTRIES] = {1, 1, 2, 3,  4,  1,  0,  1,  3,  0, 7};
+
+	for (i = 0; i < NUM_ENTRIES; i++) {
+		err = item_insert_order(&tree, index[i], order[i]);
+		assert(!err);
+	}
+
+	for (j = 0; j < 256; j++) {
+		for (i = 0; i < NUM_ENTRIES; i++)
+			if (j <= (index[i] | ((1 << order[i]) - 1)))
+				break;
+
+		radix_tree_for_each_slot(slot, &tree, &iter, j) {
+			int height = order[i] / RADIX_TREE_MAP_SHIFT;
+			int shift = height * RADIX_TREE_MAP_SHIFT;
+			unsigned long mask = (1UL << order[i]) - 1;
+			struct item *item = *slot;
+
+			assert((iter.index | mask) == (index[i] | mask));
+			assert(iter.shift == shift);
+			assert(!radix_tree_is_internal_node(item));
+			assert((item->index | mask) == (index[i] | mask));
+			assert(item->order == order[i]);
+			i++;
+		}
+	}
+
+	item_kill_tree(&tree);
+}
+
+void multiorder_tagged_iteration(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_iter iter;
+	void **slot;
+	int i, j;
+
+	printv(1, "Multiorder tagged iteration test\n");
+
+#define MT_NUM_ENTRIES 9
+	int index[MT_NUM_ENTRIES] = {0, 2, 4, 16, 32, 40, 64, 72, 128};
+	int order[MT_NUM_ENTRIES] = {1, 0, 2, 4,  3,  1,  3,  0,   7};
+
+#define TAG_ENTRIES 7
+	int tag_index[TAG_ENTRIES] = {0, 4, 16, 40, 64, 72, 128};
+
+	for (i = 0; i < MT_NUM_ENTRIES; i++)
+		assert(!item_insert_order(&tree, index[i], order[i]));
+
+	assert(!radix_tree_tagged(&tree, 1));
+
+	for (i = 0; i < TAG_ENTRIES; i++)
+		assert(radix_tree_tag_set(&tree, tag_index[i], 1));
+
+	for (j = 0; j < 256; j++) {
+		int k;
+
+		for (i = 0; i < TAG_ENTRIES; i++) {
+			for (k = i; index[k] < tag_index[i]; k++)
+				;
+			if (j <= (index[k] | ((1 << order[k]) - 1)))
+				break;
+		}
+
+		radix_tree_for_each_tagged(slot, &tree, &iter, j, 1) {
+			unsigned long mask;
+			struct item *item = *slot;
+			for (k = i; index[k] < tag_index[i]; k++)
+				;
+			mask = (1UL << order[k]) - 1;
+
+			assert((iter.index | mask) == (tag_index[i] | mask));
+			assert(!radix_tree_is_internal_node(item));
+			assert((item->index | mask) == (tag_index[i] | mask));
+			assert(item->order == order[k]);
+			i++;
+		}
+	}
+
+	assert(tag_tagged_items(&tree, NULL, 0, ~0UL, TAG_ENTRIES, 1, 2) ==
+				TAG_ENTRIES);
+
+	for (j = 0; j < 256; j++) {
+		int mask, k;
+
+		for (i = 0; i < TAG_ENTRIES; i++) {
+			for (k = i; index[k] < tag_index[i]; k++)
+				;
+			if (j <= (index[k] | ((1 << order[k]) - 1)))
+				break;
+		}
+
+		radix_tree_for_each_tagged(slot, &tree, &iter, j, 2) {
+			struct item *item = *slot;
+			for (k = i; index[k] < tag_index[i]; k++)
+				;
+			mask = (1 << order[k]) - 1;
+
+			assert((iter.index | mask) == (tag_index[i] | mask));
+			assert(!radix_tree_is_internal_node(item));
+			assert((item->index | mask) == (tag_index[i] | mask));
+			assert(item->order == order[k]);
+			i++;
+		}
+	}
+
+	assert(tag_tagged_items(&tree, NULL, 1, ~0UL, MT_NUM_ENTRIES * 2, 1, 0)
+			== TAG_ENTRIES);
+	i = 0;
+	radix_tree_for_each_tagged(slot, &tree, &iter, 0, 0) {
+		assert(iter.index == tag_index[i]);
+		i++;
+	}
+
+	item_kill_tree(&tree);
+}
+
+/*
+ * Basic join checks: make sure we can't find an entry in the tree after
+ * a larger entry has replaced it
+ */
+static void multiorder_join1(unsigned long index,
+				unsigned order1, unsigned order2)
+{
+	unsigned long loc;
+	void *item, *item2 = item_create(index + 1, order1);
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert_order(&tree, index, order2);
+	item = radix_tree_lookup(&tree, index);
+	radix_tree_join(&tree, index + 1, order1, item2);
+	loc = find_item(&tree, item);
+	if (loc == -1)
+		free(item);
+	item = radix_tree_lookup(&tree, index + 1);
+	assert(item == item2);
+	item_kill_tree(&tree);
+}
+
+/*
+ * Check that the accounting of exceptional entries is handled correctly
+ * by joining an exceptional entry to a normal pointer.
+ */
+static void multiorder_join2(unsigned order1, unsigned order2)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_node *node;
+	void *item1 = item_create(0, order1);
+	void *item2;
+
+	item_insert_order(&tree, 0, order2);
+	radix_tree_insert(&tree, 1 << order2, (void *)0x12UL);
+	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
+	assert(item2 == (void *)0x12UL);
+	assert(node->exceptional == 1);
+
+	item2 = radix_tree_lookup(&tree, 0);
+	free(item2);
+
+	radix_tree_join(&tree, 0, order1, item1);
+	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
+	assert(item2 == item1);
+	assert(node->exceptional == 0);
+	item_kill_tree(&tree);
+}
+
+/*
+ * This test revealed an accounting bug for exceptional entries at one point.
+ * Nodes were being freed back into the pool with an elevated exception count
+ * by radix_tree_join() and then radix_tree_split() was failing to zero the
+ * count of exceptional entries.
+ */
+static void multiorder_join3(unsigned int order)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_node *node;
+	void **slot;
+	struct radix_tree_iter iter;
+	unsigned long i;
+
+	for (i = 0; i < (1 << order); i++) {
+		radix_tree_insert(&tree, i, (void *)0x12UL);
+	}
+
+	radix_tree_join(&tree, 0, order, (void *)0x16UL);
+	rcu_barrier();
+
+	radix_tree_split(&tree, 0, 0);
+
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		radix_tree_iter_replace(&tree, &iter, slot, (void *)0x12UL);
+	}
+
+	__radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(node->exceptional == node->count);
+
+	item_kill_tree(&tree);
+}
+
+static void multiorder_join(void)
+{
+	int i, j, idx;
+
+	for (idx = 0; idx < 1024; idx = idx * 2 + 3) {
+		for (i = 1; i < 15; i++) {
+			for (j = 0; j < i; j++) {
+				multiorder_join1(idx, i, j);
+			}
+		}
+	}
+
+	for (i = 1; i < 15; i++) {
+		for (j = 0; j < i; j++) {
+			multiorder_join2(i, j);
+		}
+	}
+
+	for (i = 3; i < 10; i++) {
+		multiorder_join3(i);
+	}
+}
+
+static void check_mem(unsigned old_order, unsigned new_order, unsigned alloc)
+{
+	struct radix_tree_preload *rtp = &radix_tree_preloads;
+	if (rtp->nr != 0)
+		printv(2, "split(%u %u) remaining %u\n", old_order, new_order,
+							rtp->nr);
+	/*
+	 * Can't check for equality here as some nodes may have been
+	 * RCU-freed while we ran.  But we should never finish with more
+	 * nodes allocated since they should have all been preloaded.
+	 */
+	if (nr_allocated > alloc)
+		printv(2, "split(%u %u) allocated %u %u\n", old_order, new_order,
+							alloc, nr_allocated);
+}
+
+static void __multiorder_split(int old_order, int new_order)
+{
+	RADIX_TREE(tree, GFP_ATOMIC);
+	void **slot;
+	struct radix_tree_iter iter;
+	unsigned alloc;
+	struct item *item;
+
+	radix_tree_preload(GFP_KERNEL);
+	assert(item_insert_order(&tree, 0, old_order) == 0);
+	radix_tree_preload_end();
+
+	/* Wipe out the preloaded cache or it'll confuse check_mem() */
+	radix_tree_cpu_dead(0);
+
+	item = radix_tree_tag_set(&tree, 0, 2);
+
+	radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
+	alloc = nr_allocated;
+	radix_tree_split(&tree, 0, new_order);
+	check_mem(old_order, new_order, alloc);
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		radix_tree_iter_replace(&tree, &iter, slot,
+					item_create(iter.index, new_order));
+	}
+	radix_tree_preload_end();
+
+	item_kill_tree(&tree);
+	free(item);
+}
+
+static void __multiorder_split2(int old_order, int new_order)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	void **slot;
+	struct radix_tree_iter iter;
+	struct radix_tree_node *node;
+	void *item;
+
+	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+
+	item = __radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(item == (void *)0x12);
+	assert(node->exceptional > 0);
+
+	radix_tree_split(&tree, 0, new_order);
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		radix_tree_iter_replace(&tree, &iter, slot,
+					item_create(iter.index, new_order));
+	}
+
+	item = __radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(item != (void *)0x12);
+	assert(node->exceptional == 0);
+
+	item_kill_tree(&tree);
+}
+
+static void __multiorder_split3(int old_order, int new_order)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	void **slot;
+	struct radix_tree_iter iter;
+	struct radix_tree_node *node;
+	void *item;
+
+	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+
+	item = __radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(item == (void *)0x12);
+	assert(node->exceptional > 0);
+
+	radix_tree_split(&tree, 0, new_order);
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		radix_tree_iter_replace(&tree, &iter, slot, (void *)0x16);
+	}
+
+	item = __radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(item == (void *)0x16);
+	assert(node->exceptional > 0);
+
+	item_kill_tree(&tree);
+
+	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+
+	item = __radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(item == (void *)0x12);
+	assert(node->exceptional > 0);
+
+	radix_tree_split(&tree, 0, new_order);
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		if (iter.index == (1 << new_order))
+			radix_tree_iter_replace(&tree, &iter, slot,
+						(void *)0x16);
+		else
+			radix_tree_iter_replace(&tree, &iter, slot, NULL);
+	}
+
+	item = __radix_tree_lookup(&tree, 1 << new_order, &node, NULL);
+	assert(item == (void *)0x16);
+	assert(node->count == node->exceptional);
+	do {
+		node = node->parent;
+		if (!node)
+			break;
+		assert(node->count == 1);
+		assert(node->exceptional == 0);
+	} while (1);
+
+	item_kill_tree(&tree);
+}
+
+static void multiorder_split(void)
+{
+	int i, j;
+
+	for (i = 3; i < 11; i++)
+		for (j = 0; j < i; j++) {
+			__multiorder_split(i, j);
+			__multiorder_split2(i, j);
+			__multiorder_split3(i, j);
+		}
+}
+
+static void multiorder_account(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	struct radix_tree_node *node;
+	void **slot;
+
+	item_insert_order(&tree, 0, 5);
+
+	__radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+	__radix_tree_lookup(&tree, 0, &node, NULL);
+	assert(node->count == node->exceptional * 2);
+	radix_tree_delete(&tree, 1 << 5);
+	assert(node->exceptional == 0);
+
+	__radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+	__radix_tree_lookup(&tree, 1 << 5, &node, &slot);
+	assert(node->count == node->exceptional * 2);
+	__radix_tree_replace(&tree, node, slot, NULL, NULL);
+	assert(node->exceptional == 0);
+
+	item_kill_tree(&tree);
+}
+
+bool stop_iteration = false;
+
+static void *creator_func(void *ptr)
+{
+	/* 'order' is set up to ensure we have sibling entries */
+	unsigned int order = RADIX_TREE_MAP_SHIFT - 1;
+	struct radix_tree_root *tree = ptr;
+	int i;
+
+	for (i = 0; i < 10000; i++) {
+		item_insert_order(tree, 0, order);
+		item_delete_rcu(tree, 0);
+	}
+
+	stop_iteration = true;
+	return NULL;
+}
+
+static void *iterator_func(void *ptr)
+{
+	struct radix_tree_root *tree = ptr;
+	struct radix_tree_iter iter;
+	struct item *item;
+	void **slot;
+
+	while (!stop_iteration) {
+		rcu_read_lock();
+		radix_tree_for_each_slot(slot, tree, &iter, 0) {
+			item = radix_tree_deref_slot(slot);
+
+			if (!item)
+				continue;
+			if (radix_tree_deref_retry(item)) {
+				slot = radix_tree_iter_retry(&iter);
+				continue;
+			}
+
+			item_sanity(item, iter.index);
+		}
+		rcu_read_unlock();
+	}
+	return NULL;
+}
+
+static void multiorder_iteration_race(void)
+{
+	const int num_threads = sysconf(_SC_NPROCESSORS_ONLN);
+	pthread_t worker_thread[num_threads];
+	RADIX_TREE(tree, GFP_KERNEL);
+	int i;
+
+	pthread_create(&worker_thread[0], NULL, &creator_func, &tree);
+	for (i = 1; i < num_threads; i++)
+		pthread_create(&worker_thread[i], NULL, &iterator_func, &tree);
+
+	for (i = 0; i < num_threads; i++)
+		pthread_join(worker_thread[i], NULL);
+
+	item_kill_tree(&tree);
+}
+
+void multiorder_checks(void)
+{
+	int i;
+
+	for (i = 0; i < 20; i++) {
+		multiorder_check(200, i);
+		multiorder_check(0, i);
+		multiorder_check((1UL << i) + 1, i);
+	}
+
+	for (i = 0; i < 15; i++)
+		multiorder_shrink((1UL << (i + RADIX_TREE_MAP_SHIFT)), i);
+
+	multiorder_insert_bug();
+	multiorder_tag_tests();
+	multiorder_iteration();
+	multiorder_tagged_iteration();
+	multiorder_join();
+	multiorder_split();
+	multiorder_account();
+	multiorder_iteration_race();
+
+	radix_tree_cpu_dead(0);
+}
+
+int __weak main(void)
+{
+	radix_tree_init();
+	multiorder_checks();
+	return 0;
+}
diff --git a/tools/testing/radix-tree/regression.h b/tools/testing/radix-tree/regression.h
new file mode 100644
index 0000000..3c8a158
--- /dev/null
+++ b/tools/testing/radix-tree/regression.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __REGRESSION_H__
+#define __REGRESSION_H__
+
+void regression1_test(void);
+void regression2_test(void);
+void regression3_test(void);
+
+#endif
diff --git a/tools/testing/radix-tree/regression1.c b/tools/testing/radix-tree/regression1.c
new file mode 100644
index 0000000..0aece09
--- /dev/null
+++ b/tools/testing/radix-tree/regression1.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Regression1
+ * Description:
+ * Salman Qazi describes the following radix-tree bug:
+ *
+ * In the following case, we get can get a deadlock:
+ *
+ * 0.  The radix tree contains two items, one has the index 0.
+ * 1.  The reader (in this case find_get_pages) takes the rcu_read_lock.
+ * 2.  The reader acquires slot(s) for item(s) including the index 0 item.
+ * 3.  The non-zero index item is deleted, and as a consequence the other item
+ *     is moved to the root of the tree. The place where it used to be is queued
+ *     for deletion after the readers finish.
+ * 3b. The zero item is deleted, removing it from the direct slot, it remains in
+ *     the rcu-delayed indirect node.
+ * 4.  The reader looks at the index 0 slot, and finds that the page has 0 ref
+ *     count
+ * 5.  The reader looks at it again, hoping that the item will either be freed
+ *     or the ref count will increase. This never happens, as the slot it is
+ *     looking at will never be updated. Also, this slot can never be reclaimed
+ *     because the reader is holding rcu_read_lock and is in an infinite loop.
+ *
+ * The fix is to re-use the same "indirect" pointer case that requires a slot
+ * lookup retry into a general "retry the lookup" bit.
+ *
+ * Running:
+ * This test should run to completion in a few seconds. The above bug would
+ * cause it to hang indefinitely.
+ *
+ * Upstream commit:
+ * Not yet
+ */
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "regression.h"
+
+static RADIX_TREE(mt_tree, GFP_KERNEL);
+static pthread_mutex_t mt_lock = PTHREAD_MUTEX_INITIALIZER;
+
+struct page {
+	pthread_mutex_t lock;
+	struct rcu_head rcu;
+	int count;
+	unsigned long index;
+};
+
+static struct page *page_alloc(void)
+{
+	struct page *p;
+	p = malloc(sizeof(struct page));
+	p->count = 1;
+	p->index = 1;
+	pthread_mutex_init(&p->lock, NULL);
+
+	return p;
+}
+
+static void page_rcu_free(struct rcu_head *rcu)
+{
+	struct page *p = container_of(rcu, struct page, rcu);
+	assert(!p->count);
+	pthread_mutex_destroy(&p->lock);
+	free(p);
+}
+
+static void page_free(struct page *p)
+{
+	call_rcu(&p->rcu, page_rcu_free);
+}
+
+static unsigned find_get_pages(unsigned long start,
+			    unsigned int nr_pages, struct page **pages)
+{
+	unsigned int i;
+	unsigned int ret;
+	unsigned int nr_found;
+
+	rcu_read_lock();
+restart:
+	nr_found = radix_tree_gang_lookup_slot(&mt_tree,
+				(void ***)pages, NULL, start, nr_pages);
+	ret = 0;
+	for (i = 0; i < nr_found; i++) {
+		struct page *page;
+repeat:
+		page = radix_tree_deref_slot((void **)pages[i]);
+		if (unlikely(!page))
+			continue;
+
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				assert((start | i) == 0);
+				goto restart;
+			}
+			/*
+			 * No exceptional entries are inserted in this test.
+			 */
+			assert(0);
+		}
+
+		pthread_mutex_lock(&page->lock);
+		if (!page->count) {
+			pthread_mutex_unlock(&page->lock);
+			goto repeat;
+		}
+		/* don't actually update page refcount */
+		pthread_mutex_unlock(&page->lock);
+
+		/* Has the page moved? */
+		if (unlikely(page != *((void **)pages[i]))) {
+			goto repeat;
+		}
+
+		pages[ret] = page;
+		ret++;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static pthread_barrier_t worker_barrier;
+
+static void *regression1_fn(void *arg)
+{
+	rcu_register_thread();
+
+	if (pthread_barrier_wait(&worker_barrier) ==
+			PTHREAD_BARRIER_SERIAL_THREAD) {
+		int j;
+
+		for (j = 0; j < 1000000; j++) {
+			struct page *p;
+
+			p = page_alloc();
+			pthread_mutex_lock(&mt_lock);
+			radix_tree_insert(&mt_tree, 0, p);
+			pthread_mutex_unlock(&mt_lock);
+
+			p = page_alloc();
+			pthread_mutex_lock(&mt_lock);
+			radix_tree_insert(&mt_tree, 1, p);
+			pthread_mutex_unlock(&mt_lock);
+
+			pthread_mutex_lock(&mt_lock);
+			p = radix_tree_delete(&mt_tree, 1);
+			pthread_mutex_lock(&p->lock);
+			p->count--;
+			pthread_mutex_unlock(&p->lock);
+			pthread_mutex_unlock(&mt_lock);
+			page_free(p);
+
+			pthread_mutex_lock(&mt_lock);
+			p = radix_tree_delete(&mt_tree, 0);
+			pthread_mutex_lock(&p->lock);
+			p->count--;
+			pthread_mutex_unlock(&p->lock);
+			pthread_mutex_unlock(&mt_lock);
+			page_free(p);
+		}
+	} else {
+		int j;
+
+		for (j = 0; j < 100000000; j++) {
+			struct page *pages[10];
+
+			find_get_pages(0, 10, pages);
+		}
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+static pthread_t *threads;
+void regression1_test(void)
+{
+	int nr_threads;
+	int i;
+	long arg;
+
+	/* Regression #1 */
+	printv(1, "running regression test 1, should finish in under a minute\n");
+	nr_threads = 2;
+	pthread_barrier_init(&worker_barrier, NULL, nr_threads);
+
+	threads = malloc(nr_threads * sizeof(pthread_t *));
+
+	for (i = 0; i < nr_threads; i++) {
+		arg = i;
+		if (pthread_create(&threads[i], NULL, regression1_fn, (void *)arg)) {
+			perror("pthread_create");
+			exit(1);
+		}
+	}
+
+	for (i = 0; i < nr_threads; i++) {
+		if (pthread_join(threads[i], NULL)) {
+			perror("pthread_join");
+			exit(1);
+		}
+	}
+
+	free(threads);
+
+	printv(1, "regression test 1, done\n");
+}
diff --git a/tools/testing/radix-tree/regression2.c b/tools/testing/radix-tree/regression2.c
new file mode 100644
index 0000000..424b91c
--- /dev/null
+++ b/tools/testing/radix-tree/regression2.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Regression2
+ * Description:
+ * Toshiyuki Okajima describes the following radix-tree bug:
+ *
+ * In the following case, we can get a hangup on
+ *   radix_radix_tree_gang_lookup_tag_slot.
+ *
+ * 0.  The radix tree contains RADIX_TREE_MAP_SIZE items. And the tag of
+ *     a certain item has PAGECACHE_TAG_DIRTY.
+ * 1.  radix_tree_range_tag_if_tagged(, start, end, , PAGECACHE_TAG_DIRTY,
+ *     PAGECACHE_TAG_TOWRITE) is called to add PAGECACHE_TAG_TOWRITE tag
+ *     for the tag which has PAGECACHE_TAG_DIRTY. However, there is no tag with
+ *     PAGECACHE_TAG_DIRTY within the range from start to end. As the result,
+ *     There is no tag with PAGECACHE_TAG_TOWRITE but the root tag has
+ *     PAGECACHE_TAG_TOWRITE.
+ * 2.  An item is added into the radix tree and then the level of it is
+ *     extended into 2 from 1. At that time, the new radix tree node succeeds
+ *     the tag status of the root tag. Therefore the tag of the new radix tree
+ *     node has PAGECACHE_TAG_TOWRITE but there is not slot with
+ *     PAGECACHE_TAG_TOWRITE tag in the child node of the new radix tree node.
+ * 3.  The tag of a certain item is cleared with PAGECACHE_TAG_DIRTY.
+ * 4.  All items within the index range from 0 to RADIX_TREE_MAP_SIZE - 1 are
+ *     released. (Only the item which index is RADIX_TREE_MAP_SIZE exist in the
+ *     radix tree.) As the result, the slot of the radix tree node is NULL but
+ *     the tag which corresponds to the slot has PAGECACHE_TAG_TOWRITE.
+ * 5.  radix_tree_gang_lookup_tag_slot(PAGECACHE_TAG_TOWRITE) calls
+ *     __lookup_tag. __lookup_tag returns with 0. And __lookup_tag doesn't
+ *     change the index that is the input and output parameter. Because the 1st
+ *     slot of the radix tree node is NULL, but the tag which corresponds to
+ *     the slot has PAGECACHE_TAG_TOWRITE.
+ *     Therefore radix_tree_gang_lookup_tag_slot tries to get some items by
+ *     calling __lookup_tag, but it cannot get any items forever.
+ *
+ * The fix is to change that radix_tree_tag_if_tagged doesn't tag the root tag
+ * if it doesn't set any tags within the specified range.
+ *
+ * Running:
+ * This test should run to completion immediately. The above bug would cause it
+ * to hang indefinitely.
+ *
+ * Upstream commit:
+ * Not yet
+ */
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "regression.h"
+#include "test.h"
+
+#define PAGECACHE_TAG_DIRTY     0
+#define PAGECACHE_TAG_WRITEBACK 1
+#define PAGECACHE_TAG_TOWRITE   2
+
+static RADIX_TREE(mt_tree, GFP_KERNEL);
+unsigned long page_count = 0;
+
+struct page {
+	unsigned long index;
+};
+
+static struct page *page_alloc(void)
+{
+	struct page *p;
+	p = malloc(sizeof(struct page));
+	p->index = page_count++;
+
+	return p;
+}
+
+void regression2_test(void)
+{
+	int i;
+	struct page *p;
+	int max_slots = RADIX_TREE_MAP_SIZE;
+	unsigned long int start, end;
+	struct page *pages[1];
+
+	printv(1, "running regression test 2 (should take milliseconds)\n");
+	/* 0. */
+	for (i = 0; i <= max_slots - 1; i++) {
+		p = page_alloc();
+		radix_tree_insert(&mt_tree, i, p);
+	}
+	radix_tree_tag_set(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY);
+
+	/* 1. */
+	start = 0;
+	end = max_slots - 2;
+	tag_tagged_items(&mt_tree, NULL, start, end, 1,
+				PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE);
+
+	/* 2. */
+	p = page_alloc();
+	radix_tree_insert(&mt_tree, max_slots, p);
+
+	/* 3. */
+	radix_tree_tag_clear(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY);
+
+	/* 4. */
+	for (i = max_slots - 1; i >= 0; i--)
+		free(radix_tree_delete(&mt_tree, i));
+
+	/* 5. */
+	// NOTE: start should not be 0 because radix_tree_gang_lookup_tag_slot
+	//       can return.
+	start = 1;
+	end = max_slots - 2;
+	radix_tree_gang_lookup_tag_slot(&mt_tree, (void ***)pages, start, end,
+		PAGECACHE_TAG_TOWRITE);
+
+	/* We remove all the remained nodes */
+	free(radix_tree_delete(&mt_tree, max_slots));
+
+	BUG_ON(!radix_tree_empty(&mt_tree));
+
+	printv(1, "regression test 2, done\n");
+}
diff --git a/tools/testing/radix-tree/regression3.c b/tools/testing/radix-tree/regression3.c
new file mode 100644
index 0000000..ace2543
--- /dev/null
+++ b/tools/testing/radix-tree/regression3.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Regression3
+ * Description:
+ * Helper radix_tree_iter_retry resets next_index to the current index.
+ * In following radix_tree_next_slot current chunk size becomes zero.
+ * This isn't checked and it tries to dereference null pointer in slot.
+ *
+ * Helper radix_tree_iter_resume reset slot to NULL and next_index to index + 1,
+ * for tagger iteraction it also must reset cached tags in iterator to abort
+ * next radix_tree_next_slot and go to slow-path into radix_tree_next_chunk.
+ *
+ * Running:
+ * This test should run to completion immediately. The above bug would
+ * cause it to segfault.
+ *
+ * Upstream commit:
+ * Not yet
+ */
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "regression.h"
+
+void regression3_test(void)
+{
+	RADIX_TREE(root, GFP_KERNEL);
+	void *ptr0 = (void *)4ul;
+	void *ptr = (void *)8ul;
+	struct radix_tree_iter iter;
+	void **slot;
+	bool first;
+
+	printv(1, "running regression test 3 (should take milliseconds)\n");
+
+	radix_tree_insert(&root, 0, ptr0);
+	radix_tree_tag_set(&root, 0, 0);
+
+	first = true;
+	radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) {
+		printv(2, "tagged %ld %p\n", iter.index, *slot);
+		if (first) {
+			radix_tree_insert(&root, 1, ptr);
+			radix_tree_tag_set(&root, 1, 0);
+			first = false;
+		}
+		if (radix_tree_deref_retry(*slot)) {
+			printv(2, "retry at %ld\n", iter.index);
+			slot = radix_tree_iter_retry(&iter);
+			continue;
+		}
+	}
+	radix_tree_delete(&root, 1);
+
+	first = true;
+	radix_tree_for_each_slot(slot, &root, &iter, 0) {
+		printv(2, "slot %ld %p\n", iter.index, *slot);
+		if (first) {
+			radix_tree_insert(&root, 1, ptr);
+			first = false;
+		}
+		if (radix_tree_deref_retry(*slot)) {
+			printv(2, "retry at %ld\n", iter.index);
+			slot = radix_tree_iter_retry(&iter);
+			continue;
+		}
+	}
+	radix_tree_delete(&root, 1);
+
+	first = true;
+	radix_tree_for_each_contig(slot, &root, &iter, 0) {
+		printv(2, "contig %ld %p\n", iter.index, *slot);
+		if (first) {
+			radix_tree_insert(&root, 1, ptr);
+			first = false;
+		}
+		if (radix_tree_deref_retry(*slot)) {
+			printv(2, "retry at %ld\n", iter.index);
+			slot = radix_tree_iter_retry(&iter);
+			continue;
+		}
+	}
+
+	radix_tree_for_each_slot(slot, &root, &iter, 0) {
+		printv(2, "slot %ld %p\n", iter.index, *slot);
+		if (!iter.index) {
+			printv(2, "next at %ld\n", iter.index);
+			slot = radix_tree_iter_resume(slot, &iter);
+		}
+	}
+
+	radix_tree_for_each_contig(slot, &root, &iter, 0) {
+		printv(2, "contig %ld %p\n", iter.index, *slot);
+		if (!iter.index) {
+			printv(2, "next at %ld\n", iter.index);
+			slot = radix_tree_iter_resume(slot, &iter);
+		}
+	}
+
+	radix_tree_tag_set(&root, 0, 0);
+	radix_tree_tag_set(&root, 1, 0);
+	radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) {
+		printv(2, "tagged %ld %p\n", iter.index, *slot);
+		if (!iter.index) {
+			printv(2, "next at %ld\n", iter.index);
+			slot = radix_tree_iter_resume(slot, &iter);
+		}
+	}
+
+	radix_tree_delete(&root, 0);
+	radix_tree_delete(&root, 1);
+
+	printv(1, "regression test 3 passed\n");
+}
diff --git a/tools/testing/radix-tree/tag_check.c b/tools/testing/radix-tree/tag_check.c
new file mode 100644
index 0000000..543181e
--- /dev/null
+++ b/tools/testing/radix-tree/tag_check.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+
+#include "test.h"
+
+
+static void
+__simple_checks(struct radix_tree_root *tree, unsigned long index, int tag)
+{
+	unsigned long first = 0;
+	int ret;
+
+	item_check_absent(tree, index);
+	assert(item_tag_get(tree, index, tag) == 0);
+
+	item_insert(tree, index);
+	assert(item_tag_get(tree, index, tag) == 0);
+	item_tag_set(tree, index, tag);
+	ret = item_tag_get(tree, index, tag);
+	assert(ret != 0);
+	ret = tag_tagged_items(tree, NULL, first, ~0UL, 10, tag, !tag);
+	assert(ret == 1);
+	ret = item_tag_get(tree, index, !tag);
+	assert(ret != 0);
+	ret = item_delete(tree, index);
+	assert(ret != 0);
+	item_insert(tree, index);
+	ret = item_tag_get(tree, index, tag);
+	assert(ret == 0);
+	ret = item_delete(tree, index);
+	assert(ret != 0);
+	ret = item_delete(tree, index);
+	assert(ret == 0);
+}
+
+void simple_checks(void)
+{
+	unsigned long index;
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	for (index = 0; index < 10000; index++) {
+		__simple_checks(&tree, index, 0);
+		__simple_checks(&tree, index, 1);
+	}
+	verify_tag_consistency(&tree, 0);
+	verify_tag_consistency(&tree, 1);
+	printv(2, "before item_kill_tree: %d allocated\n", nr_allocated);
+	item_kill_tree(&tree);
+	rcu_barrier();
+	printv(2, "after item_kill_tree: %d allocated\n", nr_allocated);
+}
+
+/*
+ * Check that tags propagate correctly when extending a tree.
+ */
+static void extend_checks(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 43);
+	assert(item_tag_get(&tree, 43, 0) == 0);
+	item_tag_set(&tree, 43, 0);
+	assert(item_tag_get(&tree, 43, 0) == 1);
+	item_insert(&tree, 1000000);
+	assert(item_tag_get(&tree, 43, 0) == 1);
+
+	item_insert(&tree, 0);
+	item_tag_set(&tree, 0, 0);
+	item_delete(&tree, 1000000);
+	assert(item_tag_get(&tree, 43, 0) != 0);
+	item_delete(&tree, 43);
+	assert(item_tag_get(&tree, 43, 0) == 0);	/* crash */
+	assert(item_tag_get(&tree, 0, 0) == 1);
+
+	verify_tag_consistency(&tree, 0);
+
+	item_kill_tree(&tree);
+}
+
+/*
+ * Check that tags propagate correctly when contracting a tree.
+ */
+static void contract_checks(void)
+{
+	struct item *item;
+	int tmp;
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	tmp = 1<<RADIX_TREE_MAP_SHIFT;
+	item_insert(&tree, tmp);
+	item_insert(&tree, tmp+1);
+	item_tag_set(&tree, tmp, 0);
+	item_tag_set(&tree, tmp, 1);
+	item_tag_set(&tree, tmp+1, 0);
+	item_delete(&tree, tmp+1);
+	item_tag_clear(&tree, tmp, 1);
+
+	assert(radix_tree_gang_lookup_tag(&tree, (void **)&item, 0, 1, 0) == 1);
+	assert(radix_tree_gang_lookup_tag(&tree, (void **)&item, 0, 1, 1) == 0);
+
+	assert(item_tag_get(&tree, tmp, 0) == 1);
+	assert(item_tag_get(&tree, tmp, 1) == 0);
+
+	verify_tag_consistency(&tree, 0);
+	item_kill_tree(&tree);
+}
+
+/*
+ * Stupid tag thrasher
+ *
+ * Create a large linear array corresponding to the tree.   Each element in
+ * the array is coherent with each node in the tree
+ */
+
+enum {
+	NODE_ABSENT = 0,
+	NODE_PRESENT = 1,
+	NODE_TAGGED = 2,
+};
+
+#define THRASH_SIZE		(1000 * 1000)
+#define N 127
+#define BATCH	33
+
+static void gang_check(struct radix_tree_root *tree,
+			char *thrash_state, int tag)
+{
+	struct item *items[BATCH];
+	int nr_found;
+	unsigned long index = 0;
+	unsigned long last_index = 0;
+
+	while ((nr_found = radix_tree_gang_lookup_tag(tree, (void **)items,
+					index, BATCH, tag))) {
+		int i;
+
+		for (i = 0; i < nr_found; i++) {
+			struct item *item = items[i];
+
+			while (last_index < item->index) {
+				assert(thrash_state[last_index] != NODE_TAGGED);
+				last_index++;
+			}
+			assert(thrash_state[last_index] == NODE_TAGGED);
+			last_index++;
+		}
+		index = items[nr_found - 1]->index + 1;
+	}
+}
+
+static void do_thrash(struct radix_tree_root *tree, char *thrash_state, int tag)
+{
+	int insert_chunk;
+	int delete_chunk;
+	int tag_chunk;
+	int untag_chunk;
+	int total_tagged = 0;
+	int total_present = 0;
+
+	for (insert_chunk = 1; insert_chunk < THRASH_SIZE; insert_chunk *= N)
+	for (delete_chunk = 1; delete_chunk < THRASH_SIZE; delete_chunk *= N)
+	for (tag_chunk = 1; tag_chunk < THRASH_SIZE; tag_chunk *= N)
+	for (untag_chunk = 1; untag_chunk < THRASH_SIZE; untag_chunk *= N) {
+		int i;
+		unsigned long index;
+		int nr_inserted = 0;
+		int nr_deleted = 0;
+		int nr_tagged = 0;
+		int nr_untagged = 0;
+		int actual_total_tagged;
+		int actual_total_present;
+
+		for (i = 0; i < insert_chunk; i++) {
+			index = rand() % THRASH_SIZE;
+			if (thrash_state[index] != NODE_ABSENT)
+				continue;
+			item_check_absent(tree, index);
+			item_insert(tree, index);
+			assert(thrash_state[index] != NODE_PRESENT);
+			thrash_state[index] = NODE_PRESENT;
+			nr_inserted++;
+			total_present++;
+		}
+
+		for (i = 0; i < delete_chunk; i++) {
+			index = rand() % THRASH_SIZE;
+			if (thrash_state[index] == NODE_ABSENT)
+				continue;
+			item_check_present(tree, index);
+			if (item_tag_get(tree, index, tag)) {
+				assert(thrash_state[index] == NODE_TAGGED);
+				total_tagged--;
+			} else {
+				assert(thrash_state[index] == NODE_PRESENT);
+			}
+			item_delete(tree, index);
+			assert(thrash_state[index] != NODE_ABSENT);
+			thrash_state[index] = NODE_ABSENT;
+			nr_deleted++;
+			total_present--;
+		}
+
+		for (i = 0; i < tag_chunk; i++) {
+			index = rand() % THRASH_SIZE;
+			if (thrash_state[index] != NODE_PRESENT) {
+				if (item_lookup(tree, index))
+					assert(item_tag_get(tree, index, tag));
+				continue;
+			}
+			item_tag_set(tree, index, tag);
+			item_tag_set(tree, index, tag);
+			assert(thrash_state[index] != NODE_TAGGED);
+			thrash_state[index] = NODE_TAGGED;
+			nr_tagged++;
+			total_tagged++;
+		}
+
+		for (i = 0; i < untag_chunk; i++) {
+			index = rand() % THRASH_SIZE;
+			if (thrash_state[index] != NODE_TAGGED)
+				continue;
+			item_check_present(tree, index);
+			assert(item_tag_get(tree, index, tag));
+			item_tag_clear(tree, index, tag);
+			item_tag_clear(tree, index, tag);
+			assert(thrash_state[index] != NODE_PRESENT);
+			thrash_state[index] = NODE_PRESENT;
+			nr_untagged++;
+			total_tagged--;
+		}
+
+		actual_total_tagged = 0;
+		actual_total_present = 0;
+		for (index = 0; index < THRASH_SIZE; index++) {
+			switch (thrash_state[index]) {
+			case NODE_ABSENT:
+				item_check_absent(tree, index);
+				break;
+			case NODE_PRESENT:
+				item_check_present(tree, index);
+				assert(!item_tag_get(tree, index, tag));
+				actual_total_present++;
+				break;
+			case NODE_TAGGED:
+				item_check_present(tree, index);
+				assert(item_tag_get(tree, index, tag));
+				actual_total_present++;
+				actual_total_tagged++;
+				break;
+			}
+		}
+
+		gang_check(tree, thrash_state, tag);
+
+		printv(2, "%d(%d) %d(%d) %d(%d) %d(%d) / "
+				"%d(%d) present, %d(%d) tagged\n",
+			insert_chunk, nr_inserted,
+			delete_chunk, nr_deleted,
+			tag_chunk, nr_tagged,
+			untag_chunk, nr_untagged,
+			total_present, actual_total_present,
+			total_tagged, actual_total_tagged);
+	}
+}
+
+static void thrash_tags(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+	char *thrash_state;
+
+	thrash_state = malloc(THRASH_SIZE);
+	memset(thrash_state, 0, THRASH_SIZE);
+
+	do_thrash(&tree, thrash_state, 0);
+
+	verify_tag_consistency(&tree, 0);
+	item_kill_tree(&tree);
+	free(thrash_state);
+}
+
+static void leak_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 1000000);
+	item_delete(&tree, 1000000);
+	item_kill_tree(&tree);
+}
+
+static void __leak_check(void)
+{
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	printv(2, "%d: nr_allocated=%d\n", __LINE__, nr_allocated);
+	item_insert(&tree, 1000000);
+	printv(2, "%d: nr_allocated=%d\n", __LINE__, nr_allocated);
+	item_delete(&tree, 1000000);
+	printv(2, "%d: nr_allocated=%d\n", __LINE__, nr_allocated);
+	item_kill_tree(&tree);
+	printv(2, "%d: nr_allocated=%d\n", __LINE__, nr_allocated);
+}
+
+static void single_check(void)
+{
+	struct item *items[BATCH];
+	RADIX_TREE(tree, GFP_KERNEL);
+	int ret;
+	unsigned long first = 0;
+
+	item_insert(&tree, 0);
+	item_tag_set(&tree, 0, 0);
+	ret = radix_tree_gang_lookup_tag(&tree, (void **)items, 0, BATCH, 0);
+	assert(ret == 1);
+	ret = radix_tree_gang_lookup_tag(&tree, (void **)items, 1, BATCH, 0);
+	assert(ret == 0);
+	verify_tag_consistency(&tree, 0);
+	verify_tag_consistency(&tree, 1);
+	ret = tag_tagged_items(&tree, NULL, first, 10, 10, 0, 1);
+	assert(ret == 1);
+	ret = radix_tree_gang_lookup_tag(&tree, (void **)items, 0, BATCH, 1);
+	assert(ret == 1);
+	item_tag_clear(&tree, 0, 0);
+	ret = radix_tree_gang_lookup_tag(&tree, (void **)items, 0, BATCH, 0);
+	assert(ret == 0);
+	item_kill_tree(&tree);
+}
+
+void radix_tree_clear_tags_test(void)
+{
+	unsigned long index;
+	struct radix_tree_node *node;
+	struct radix_tree_iter iter;
+	void **slot;
+
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert(&tree, 0);
+	item_tag_set(&tree, 0, 0);
+	__radix_tree_lookup(&tree, 0, &node, &slot);
+	radix_tree_clear_tags(&tree, node, slot);
+	assert(item_tag_get(&tree, 0, 0) == 0);
+
+	for (index = 0; index < 1000; index++) {
+		item_insert(&tree, index);
+		item_tag_set(&tree, index, 0);
+	}
+
+	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+		radix_tree_clear_tags(&tree, iter.node, slot);
+		assert(item_tag_get(&tree, iter.index, 0) == 0);
+	}
+
+	item_kill_tree(&tree);
+}
+
+void tag_check(void)
+{
+	single_check();
+	extend_checks();
+	contract_checks();
+	rcu_barrier();
+	printv(2, "after extend_checks: %d allocated\n", nr_allocated);
+	__leak_check();
+	leak_check();
+	rcu_barrier();
+	printv(2, "after leak_check: %d allocated\n", nr_allocated);
+	simple_checks();
+	rcu_barrier();
+	printv(2, "after simple_checks: %d allocated\n", nr_allocated);
+	thrash_tags();
+	rcu_barrier();
+	printv(2, "after thrash_tags: %d allocated\n", nr_allocated);
+	radix_tree_clear_tags_test();
+}
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);
+}
diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
new file mode 100644
index 0000000..92d901e
--- /dev/null
+++ b/tools/testing/radix-tree/test.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/gfp.h>
+#include <linux/types.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+
+struct item {
+	struct rcu_head	rcu_head;
+	unsigned long index;
+	unsigned int order;
+};
+
+struct item *item_create(unsigned long index, unsigned int order);
+int __item_insert(struct radix_tree_root *root, struct item *item);
+int item_insert(struct radix_tree_root *root, unsigned long index);
+void item_sanity(struct item *item, unsigned long index);
+int item_insert_order(struct radix_tree_root *root, unsigned long index,
+			unsigned order);
+int item_delete(struct radix_tree_root *root, unsigned long index);
+int item_delete_rcu(struct radix_tree_root *root, unsigned long index);
+struct item *item_lookup(struct radix_tree_root *root, unsigned long index);
+
+void item_check_present(struct radix_tree_root *root, unsigned long index);
+void item_check_absent(struct radix_tree_root *root, unsigned long index);
+void item_gang_check_present(struct radix_tree_root *root,
+			unsigned long start, unsigned long nr,
+			int chunk, int hop);
+void item_full_scan(struct radix_tree_root *root, unsigned long start,
+			unsigned long nr, int chunk);
+void item_kill_tree(struct radix_tree_root *root);
+
+int tag_tagged_items(struct radix_tree_root *, pthread_mutex_t *,
+			unsigned long start, unsigned long end, unsigned batch,
+			unsigned iftag, unsigned thentag);
+unsigned long find_item(struct radix_tree_root *, void *item);
+
+void tag_check(void);
+void multiorder_checks(void);
+void iteration_test(unsigned order, unsigned duration);
+void benchmark(void);
+void idr_checks(void);
+void ida_tests(void);
+
+struct item *
+item_tag_set(struct radix_tree_root *root, unsigned long index, int tag);
+struct item *
+item_tag_clear(struct radix_tree_root *root, unsigned long index, int tag);
+int item_tag_get(struct radix_tree_root *root, unsigned long index, int tag);
+void tree_verify_min_height(struct radix_tree_root *root, int maxindex);
+void verify_tag_consistency(struct radix_tree_root *root, unsigned int tag);
+
+extern int nr_allocated;
+
+/* Normally private parts of lib/radix-tree.c */
+struct radix_tree_node *entry_to_node(void *ptr);
+void radix_tree_dump(struct radix_tree_root *root);
+int root_tag_get(struct radix_tree_root *root, unsigned int tag);
+unsigned long node_maxindex(struct radix_tree_node *);
+unsigned long shift_maxindex(unsigned int shift);
+int radix_tree_cpu_dead(unsigned int cpu);
+struct radix_tree_preload {
+	unsigned nr;
+	struct radix_tree_node *nodes;
+};
+extern struct radix_tree_preload radix_tree_preloads;