+ test_maple_tree-test-maple_range_64-node-in-rcu-mode.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: test_maple_tree: test maple_range_64 node in RCU mode
has been added to the -mm mm-unstable branch.  Its filename is
     test_maple_tree-test-maple_range_64-node-in-rcu-mode.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/test_maple_tree-test-maple_range_64-node-in-rcu-mode.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Dimitris Charisis <dchar@cslab.ece.ntua.gr>
Subject: test_maple_tree: test maple_range_64 node in RCU mode
Date: Mon, 05 Oct 2026 12:47:28 +0000

This commit adds a test that builds two maple_range_64 trees in RCU
mode.  The first tree has a root that is a full maple_range_64 node and
ensures that the destruction under RCU does not misinterpret the last
slot as metadata. 226 insertions produce such a root on a 64-bit build.

The second tree is a height 3 tree whose root holds 15 child pointers
and metadata in its last slot, so every slot is non-zero and ensures
that the destruction under RCU does not descend into the metadata slot.
3166 insertions produce such a tree on a 64-bit build.

Link: https://lore.kernel.org/20261005-fix-maple-tree-range64-rcu-v3-2-ebe7fb278e20@cslab.ece.ntua.gr
Signed-off-by: Dimitris Charisis <dchar@cslab.ece.ntua.gr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Liam R. Howlett (Google) <liam@infradead.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
---

 lib/test_maple_tree.c |   32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

--- a/lib/test_maple_tree.c~test_maple_tree-test-maple_range_64-node-in-rcu-mode
+++ a/lib/test_maple_tree.c
@@ -3710,6 +3710,36 @@ static noinline void __init alloc_cyclic
 	MT_BUG_ON(mt, ret != 1);
 }
 
+static noinline void __init check_range64_in_rcu(struct maple_tree *mt)
+{
+	unsigned long i;
+	unsigned long nr_entries = 226; /* Build a full maple_range_64 root node */
+
+	MT_BUG_ON(mt, !mtree_empty(mt));
+	mt_init_flags(mt, MT_FLAGS_USE_RCU);
+
+	for (i = 0; i < nr_entries; i++) {
+		MT_BUG_ON(mt, mtree_test_insert_range(mt, i*10, i*10 + 9,
+						      xa_mk_value(i)));
+	}
+
+	mtree_destroy(mt);
+	rcu_barrier();
+
+	nr_entries = 3166; /* Height 3. Root has 15 children + metadata */
+
+	MT_BUG_ON(mt, !mtree_empty(mt));
+	mt_init_flags(mt, MT_FLAGS_USE_RCU);
+
+	for (i = 0; i < nr_entries; i++) {
+		MT_BUG_ON(mt, mtree_test_insert_range(mt, i*10, i*10 + 9,
+						      xa_mk_value(i)));
+	}
+
+	mtree_destroy(mt);
+	rcu_barrier();
+}
+
 static DEFINE_MTREE(tree);
 static int __init maple_tree_seed(void)
 {
@@ -3999,6 +4029,8 @@ static int __init maple_tree_seed(void)
 	alloc_cyclic_testing(&tree);
 	mtree_destroy(&tree);
 
+	check_range64_in_rcu(&tree);
+
 
 #if defined(BENCH)
 skip:
_

Patches currently in -mm which might be from dchar@cslab.ece.ntua.gr are

maple_tree-fix-maple_range_64-crashes-in-rcu-mode.patch
test_maple_tree-test-maple_range_64-node-in-rcu-mode.patch