patches/old/maple_tree-assert-retrieving-new-value-on-a-tree-containing-just-a-leaf-node.patch

From: Wei Yang <richard.weiyang@gmail.com>
Subject: maple_tree: assert retrieving new value on a tree containing just a leaf node
Date: Wed, 11 Jun 2025 01:12:53 +0000

Original code may not get the new value after overwriting the whole range
on a maple tree containing just a leaf node.  The reason is we didn't set
the only root node dead during destroy.

Add a test case to ensure the new value is returned when overwriting a
tree containing just a leaf node.

Link: https://lkml.kernel.org/r/20250611011253.19515-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/radix-tree/maple.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

--- a/tools/testing/radix-tree/maple.c~maple_tree-assert-retrieving-new-value-on-a-tree-containing-just-a-leaf-node
+++ a/tools/testing/radix-tree/maple.c
@@ -35256,6 +35256,30 @@ static noinline void __init check_rcu_si
 	MT_BUG_ON(mt, mas_prev(&mas_reader, 0) != xa_mk_value(val));
 	rcu_read_unlock();
 
+	/* Clear out tree & create one with only root node */
+	mas_lock(&mas_writer);
+	mas_set_range(&mas_writer, 0, ULONG_MAX);
+	mas_store_gfp(&mas_writer, NULL, GFP_KERNEL);
+	mas_set_range(&mas_writer, 0, 0);
+	for (i = 0; i <= 5; i++) {
+		mas_writer.index = i * 10;
+		mas_writer.last = i * 10 + 5;
+		mas_store_gfp(&mas_writer, xa_mk_value(i), GFP_KERNEL);
+	}
+	mas_unlock(&mas_writer);
+	target = 10;
+	mas_set_range(&mas_reader, target, target);
+	rcu_read_lock();
+	MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(target/10));
+
+	/* Overwrite the whole range */
+	mas_lock(&mas_writer);
+	mas_set_range(&mas_writer, 0, ULONG_MAX);
+	mas_store_gfp(&mas_writer, xa_mk_value(val), GFP_KERNEL);
+	mas_unlock(&mas_writer);
+	MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(val));
+	rcu_read_unlock();
+
 	rcu_unregister_thread();
 }
 
_