From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
To: "Liam R. Howlett (Google)" <liam@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
maple-tree@lists.infradead.org, Chris Mason <mason@kernel.org>,
Alice Ryhl <aliceryhl@google.com>,
Andrew Ballance <andrewjballance@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 3/3] maple_tree: Update internal warning and bug_on code
Date: Tue, 3 Nov 2026 11:52:24 +0000 [thread overview]
Message-ID: <aunI9hG6Qw8IQ1Uk@gremlin> (raw)
In-Reply-To: <20261103020724.2614498-4-liam@infradead.org>
On Mon, Nov 02, 2026 at 09:07:24PM -0500, Liam R. Howlett (Google) wrote:
> When CONFIG_DEBUG_MAPLE_TREE is set, call WARN_ON() once per site 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. The BUG_ON variants now stop instead of dumping and continuing.
>
> Update the non-debug code to call WARN_ON_ONCE() as well.
>
> The userspace tests asserted on dump_stack() but only print on
> WARN_ON(), so make WARN() fatal in maple-shared.h and have the maple
> test exit with the result of maple_tree_seed().
>
> Cc: <stable@vger.kernel.org>
> Reported-by: Lorenzo Stoakes <ljs@kernel.org>
> Fixes: f0a1f866aba1 ("maple_tree: add debug BUG_ON and WARN_ON variants")
> Signed-off-by: Liam R. Howlett (Google) <liam@infradead.org>
Thanks for doing this! This covers off my concerns with the userland testing
changes so all LGTM and:
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> ---
> include/linux/maple_tree.h | 48 ++++++++++++++---------------
> tools/testing/radix-tree/maple.c | 13 +++++---
> tools/testing/shared/maple-shared.h | 33 ++++++++++++++++++++
> 3 files changed, 66 insertions(+), 28 deletions(-)
>
> diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
> index e30e57f5f3df9..3a9751c6689fc 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); \
> } \
> @@ -713,7 +713,7 @@ 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); \
> } \
> @@ -722,16 +722,16 @@ void mt_cache_shrink(void);
> #define MT_WARN_ON(__tree, __x) ({ \
> 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 (__ONCE_LITE_IF(ret)) { \
> + 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); \
> })
> @@ -739,17 +739,17 @@ void mt_cache_shrink(void);
> #define MAS_WARN_ON(__mas, __x) ({ \
> 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 (__ONCE_LITE_IF(ret)) { \
> + 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); \
> })
> @@ -757,18 +757,18 @@ void mt_cache_shrink(void);
> #define MAS_WR_WARN_ON(__wrmas, __x) ({ \
> 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 (__ONCE_LITE_IF(ret)) { \
> + 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 +776,9 @@ 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 */
>
> /**
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index bfe4b8626c429..846c67e20e82a 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -36502,22 +36502,27 @@ static void regression_tests(void)
> test_spanning_store_regression();
> }
>
> -void maple_tree_tests(void)
> +int maple_tree_tests(void)
> {
> + int ret;
> +
> #if !defined(BENCH)
> regression_tests();
> farmer_tests();
> #endif
> - maple_tree_seed();
> + ret = maple_tree_seed();
> maple_tree_harvest();
> + return ret;
> }
>
> int __weak main(void)
> {
> + int ret;
> +
> maple_tree_init();
> - maple_tree_tests();
> + ret = maple_tree_tests();
> rcu_barrier();
> if (nr_allocated)
> printf("nr_allocated = %d\n", nr_allocated);
> - return 0;
> + return ret ? EXIT_FAILURE : EXIT_SUCCESS;
> }
> diff --git a/tools/testing/shared/maple-shared.h b/tools/testing/shared/maple-shared.h
> index 2a1e9a8594a28..5f827709773a0 100644
> --- a/tools/testing/shared/maple-shared.h
> +++ b/tools/testing/shared/maple-shared.h
> @@ -8,6 +8,7 @@
> #include "shared.h"
> #include <stdlib.h>
> #include <time.h>
> +#include <assert.h>
> #include "linux/init.h"
>
> void maple_rcu_cb(struct rcu_head *head);
> @@ -20,5 +21,37 @@ do { \
> call_rcu(&((_p_struct)->_memb), rcu_cb); \
> } while(0);
>
> +/* Make WARN() fatal */
> +#undef WARN
> +#undef WARN_ON
> +#undef WARN_ONCE
> +#undef WARN_ON_ONCE
> +#define WARN(condition, format...) ({ \
> + int __ret_warn_on = !!(condition); \
> + if (unlikely(__ret_warn_on)) { \
> + __WARN_printf(format); \
> + assert(0); \
> + } \
> + unlikely(__ret_warn_on); \
> +})
> +#define WARN_ON(condition) \
> + WARN(condition, "assertion failed at %s:%d\n", __FILE__, __LINE__)
> +#define WARN_ONCE(condition, format...) WARN(condition, format)
> +#define WARN_ON_ONCE(condition) WARN_ON(condition)
> +
> +/* Once state for the debug macros */
> +#ifndef __ONCE_LITE_IF
> +#define __ONCE_LITE_IF(condition) \
> + ({ \
> + static bool __already_done; \
> + bool __ret_once = false; \
> + \
> + if ((condition) && !__already_done) { \
> + __already_done = true; \
> + __ret_once = true; \
> + } \
> + __ret_once; \
> + })
> +#endif
>
> #endif /* __MAPLE_SHARED_H__ */
> --
> 2.47.3
>
--
Cheers, Lorenzo
prev parent reply other threads:[~2026-11-03 11:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 2:07 [PATCH v2 0/3] maple_tree fixes for 7.3 Liam R. Howlett (Google)
2026-11-03 2:07 ` [PATCH v2 1/3] maple_tree: Fix rcu reader NULL dereference after the tree is emptied Liam R. Howlett (Google)
2026-11-03 3:24 ` sashiko-bot
2026-11-04 18:41 ` Andrew Morton
2026-11-03 2:07 ` [PATCH v2 2/3] maple_tree: Test emptying tree while RCU reading Liam R. Howlett (Google)
2026-11-03 2:07 ` [PATCH v2 3/3] maple_tree: Update internal warning and bug_on code Liam R. Howlett (Google)
2026-11-03 11:52 ` Lorenzo Stoakes (ARM) [this message]
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