+ maple_tree-assert-static-storage-for-define_mtree.patch added to mm-new branch

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

The patch titled
     Subject: maple_tree: assert static storage for DEFINE_MTREE()
has been added to the -mm mm-new branch.  Its filename is
     maple_tree-assert-static-storage-for-define_mtree.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-assert-static-storage-for-define_mtree.patch

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

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Yury Norov <ynorov@nvidia.com>
Subject: maple_tree: assert static storage for DEFINE_MTREE()
Date: Fri, 11 Sep 2026 18:14:43 -0400

DEFINE_MTREE() uses MTREE_INIT(), which initializes the tree's embedded
lock with a static spinlock initializer.  If the tree is an automatic
local object, lockdep rejects its address as a non-static class key and
disables locking validation on the first lock acquisition.

Apply ASSERT_STATIC_STORAGE() to DEFINE_MTREE() to catch automatic local
definitions at compile time.  For example:

  void example(void)
  {
          DEFINE_MTREE(mt);
          mtree_destroy(&mt);
  }

GCC reports:

  error: initializer element is not constant
    name##_storage_check = &(name)
                           ^
  note: in expansion of macro 'ASSERT_STATIC_STORAGE'
    ASSERT_STATIC_STORAGE(name)
  note: in expansion of macro 'DEFINE_MTREE'
    DEFINE_MTREE(mt);

File-scope definitions and static local trees remain valid.  Automatic
local trees must instead use mt_init() or mt_init_flags().  Direct uses of
MTREE_INIT() and MTREE_INIT_EXT() are unchanged.

Replace the local DEFINE_MTREE() in the interval-tree span test with a
plain declaration; the test already initializes the tree with
mt_init_flags() before use.  Convert the three local Maple Trees in the
userspace radix-tree tests to mt_init().

Validated file-scope and static local definitions with a kernel object
build, and confirmed that an automatic local definition fails to compile. 
The Maple Tree test and region allocation benchmark objects also build
with lockdep enabled.

Link: https://lore.kernel.org/20260911221444.1523311-4-ynorov@nvidia.com
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Christopher Li <sparse@chrisli.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
---

 include/linux/maple_tree.h       |    4 +++-
 lib/interval_tree_test.c         |    2 +-
 tools/testing/radix-tree/maple.c |   12 +++++++++---
 3 files changed, 13 insertions(+), 5 deletions(-)

--- a/include/linux/maple_tree.h~maple_tree-assert-static-storage-for-define_mtree
+++ a/include/linux/maple_tree.h
@@ -9,6 +9,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/compiler.h>
 #include <linux/rcupdate.h>
 #include <linux/spinlock.h>
 
@@ -297,7 +298,8 @@ struct maple_tree {
 #endif
 
 #define DEFINE_MTREE(name)						\
-	struct maple_tree name = MTREE_INIT(name, 0)
+	struct maple_tree name = MTREE_INIT(name, 0);		\
+	ASSERT_STATIC_STORAGE(name)
 
 #define mtree_lock(mt)		spin_lock((&(mt)->ma_lock))
 #define mtree_lock_nested(mas, subclass) \
--- a/lib/interval_tree_test.c~maple_tree-assert-static-storage-for-define_mtree
+++ a/lib/interval_tree_test.c
@@ -244,7 +244,7 @@ static int span_iteration_check(void)
 	unsigned long start, last;
 	struct interval_tree_span_iter span, mas_span;
 
-	DEFINE_MTREE(tree);
+	struct maple_tree tree;
 
 	MA_STATE(mas, &tree, 0, 0);
 
--- a/tools/testing/radix-tree/maple.c~maple_tree-assert-static-storage-for-define_mtree
+++ a/tools/testing/radix-tree/maple.c
@@ -36022,10 +36022,12 @@ static noinline void __init check_erase_
 
 static noinline void __init check_mtree_dup(struct maple_tree *mt)
 {
-	DEFINE_MTREE(new);
+	struct maple_tree new;
 	int i, j, ret, count = 0;
 	unsigned int rand_seed = 17, rand;
 
+	mt_init(&new);
+
 	/* store a value at [0, 0] */
 	mt_init_flags(mt, 0);
 	mtree_store_range(mt, 0, 0, xa_mk_value(0), GFP_KERNEL);
@@ -36319,7 +36321,9 @@ static inline int check_vma_modification
 void farmer_tests(void)
 {
 	struct maple_node *node;
-	DEFINE_MTREE(tree);
+	struct maple_tree tree;
+
+	mt_init(&tree);
 
 	mt_dump(&tree, mt_dump_dec);
 
@@ -36432,9 +36436,11 @@ static unsigned long get_last_index(stru
 static void test_spanning_store_regression(void)
 {
 	unsigned long from = 0, to = 0;
-	DEFINE_MTREE(tree);
+	struct maple_tree tree;
 	MA_STATE(mas, &tree, 0, 0);
 
+	mt_init(&tree);
+
 	/*
 	 * Build a 3-level tree. We require a parent node below the root node
 	 * and 2 leaf nodes under it, so we can span the entirety of the right
_

Patches currently in -mm which might be from ynorov@nvidia.com are

lib-fix-lock-initialization-in-region-allocation-benchmark.patch
compilerh-add-assert_static_storage.patch
idr-assert-static-storage-for-define_ida.patch
maple_tree-assert-static-storage-for-define_mtree.patch