v4.19.13 snapshot.
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");
+}