[PATCH 3/4] maple_tree: Update internal warning and bug_on code

From: Liam R. Howlett (Google)

Date: Wed Oct 28 2026 - 11:47:58 EST


When CONFIG_DEBUG_MAPLE_TREE is set, call the WARN_ON_ONCE() after the
custom information is dumped about the tree. Without using the kernel's
WARN_ON calls, syzbot will not catch issues detected by this code.

Update the non-debug code to call WARN_ON_ONCE() as well.

Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
Fixes: bf857ddd21d0b ("maple_tree: move debug check to __mas_set_range()")
Signed-off-by: Liam R. Howlett (Google) <liam@xxxxxxxxxxxxx>
---
include/linux/maple_tree.h | 54 +++++++++++++++++++++-----------------
1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e30e57f5f3df9..0f96f1f19eb95 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -680,7 +680,7 @@ void mt_cache_shrink(void);
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
+ BUG_ON(1); \
} else { \
atomic_inc(&maple_tree_tests_passed); \
} \
@@ -696,7 +696,7 @@ void mt_cache_shrink(void);
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
+ BUG_ON(1); \
} else { \
atomic_inc(&maple_tree_tests_passed); \
} \
@@ -713,62 +713,68 @@ void mt_cache_shrink(void);
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
+ BUG_ON(1); \
} else { \
atomic_inc(&maple_tree_tests_passed); \
} \
} while (0)

#define MT_WARN_ON(__tree, __x) ({ \
+ static bool __warned; \
int ret = !!(__x); \
atomic_inc(&maple_tree_tests_run); \
- if (ret) { \
- pr_info("WARN at %s:%d (%u)\n", \
- __func__, __LINE__, __x); \
+ if (!ret) { \
+ atomic_inc(&maple_tree_tests_passed); \
+ } else if (!__warned) { \
+ __warned = true; \
+ pr_info("WARN at %s:%d\n", \
+ __func__, __LINE__); \
mt_dump(__tree, mt_dump_hex); \
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
- } else { \
- atomic_inc(&maple_tree_tests_passed); \
+ WARN_ON(1); \
} \
unlikely(ret); \
})

#define MAS_WARN_ON(__mas, __x) ({ \
+ static bool __warned; \
int ret = !!(__x); \
atomic_inc(&maple_tree_tests_run); \
- if (ret) { \
- pr_info("WARN at %s:%d (%u)\n", \
- __func__, __LINE__, __x); \
+ if (!ret) { \
+ atomic_inc(&maple_tree_tests_passed); \
+ } else if (!__warned) { \
+ __warned = true; \
+ pr_info("WARN at %s:%d\n", \
+ __func__, __LINE__); \
mas_dump(__mas); \
mt_dump((__mas)->tree, mt_dump_hex); \
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
- } else { \
- atomic_inc(&maple_tree_tests_passed); \
+ WARN_ON(1); \
} \
unlikely(ret); \
})

#define MAS_WR_WARN_ON(__wrmas, __x) ({ \
+ static bool __warned; \
int ret = !!(__x); \
atomic_inc(&maple_tree_tests_run); \
- if (ret) { \
- pr_info("WARN at %s:%d (%u)\n", \
- __func__, __LINE__, __x); \
+ if (!ret) { \
+ atomic_inc(&maple_tree_tests_passed); \
+ } else if (!__warned) { \
+ __warned = true; \
+ pr_info("WARN at %s:%d\n", \
+ __func__, __LINE__); \
mas_wr_dump(__wrmas); \
mas_dump((__wrmas)->mas); \
mt_dump((__wrmas)->mas->tree, mt_dump_hex); \
pr_info("Pass: %u Run:%u\n", \
atomic_read(&maple_tree_tests_passed), \
atomic_read(&maple_tree_tests_run)); \
- dump_stack(); \
- } else { \
- atomic_inc(&maple_tree_tests_passed); \
+ WARN_ON(1); \
} \
unlikely(ret); \
})
@@ -776,9 +782,9 @@ void mt_cache_shrink(void);
#define MT_BUG_ON(__tree, __x) BUG_ON(__x)
#define MAS_BUG_ON(__mas, __x) BUG_ON(__x)
#define MAS_WR_BUG_ON(__mas, __x) BUG_ON(__x)
-#define MT_WARN_ON(__tree, __x) WARN_ON(__x)
-#define MAS_WARN_ON(__mas, __x) WARN_ON(__x)
-#define MAS_WR_WARN_ON(__mas, __x) WARN_ON(__x)
+#define MT_WARN_ON(__tree, __x) WARN_ON_ONCE(__x)
+#define MAS_WARN_ON(__mas, __x) WARN_ON_ONCE(__x)
+#define MAS_WR_WARN_ON(__mas, __x) WARN_ON_ONCE(__x)
#endif /* CONFIG_DEBUG_MAPLE_TREE */

/**
--
2.47.3