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Howlett (Oracle)" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, "Liam R. Howlett (Oracle)" , Breno Leitao Subject: [PATCH v3 03/19] maple_tree: Add write lock checking with lockdep sequence numbers Date: Fri, 21 Aug 2026 15:26:11 -0400 Message-ID: <20260821192627.4085470-4-liam@infradead.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260821192627.4085470-1-liam@infradead.org> References: <20260821192627.4085470-1-liam@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Use the lockdep sequence numbers to ensure the write lock is not dropped between write operations. The lockdep sequence is recorded on any walk that starts from the top of the tree and re-checked prior to any operation using an active node. When lockdep detects an issue, it sets debug_locks to 0 disabling further reports. __lock_sequnece() will return u32 ~0 when debug_locks is zero, and the real sequnece count cannot return such a high value as it is less than 32bits. By always updating the sequence number, regardless of lock state and by ignoring ~0 value in the sequence number will avoid ever printing a WARN_ON when lockdep sets debug_locks to 0. Cc: Breno Leitao Tested-by: Breno Leitao Signed-off-by: Liam R. Howlett (Oracle) --- include/linux/maple_tree.h | 7 +++-- lib/maple_tree.c | 64 +++++++++++++++++++++++++++++++------- 2 files changed, 57 insertions(+), 14 deletions(-) diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index 1acf932fcd33c..d63ac92208d02 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -484,9 +484,12 @@ struct ma_state { unsigned char mas_flags; unsigned char end; /* The end of the node */ enum store_type store_type; /* The type of store needed for this operation */ -#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) +#ifdef CONFIG_LOCKDEP + u32 ld_seq; +#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD unsigned long rcu_gp; -#endif +#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */ +#endif /* CONFIG_LOCKDEP */ }; struct ma_wr_state { diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 6d805521beddf..d8c826e1ca0cf 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1148,40 +1148,77 @@ static inline void mas_free(struct ma_state *mas, struct maple_enode *used) ma_free_rcu(mte_to_node(used)); } -void mas_lock_check(struct ma_state *mas) + +#ifdef CONFIG_LOCKDEP +static struct lockdep_map *mas_lockdep_map(struct ma_state *mas) { + struct maple_tree *mt = mas->tree; + + if (mt_external_lock(mt)) + return mt->ma_external_lock; + + return &(mt->ma_lock).dep_map; +} + +#endif + +static void mas_lock_check(struct ma_state *mas) +{ +#ifdef CONFIG_LOCKDEP + struct lockdep_map *map; + u32 seq; -#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) if (!mas_is_active(mas)) return; +#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD if (!mt_locked(mas->tree)) { if (mt_in_rcu(mas->tree)) WARN_ON_ONCE(poll_state_synchronize_rcu(mas->rcu_gp)); } -#endif +#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */ + + map = mas_lockdep_map(mas); + if (!map) + return; + + seq = lock_sequence(map); + if (seq != UINT_MAX && mas->ld_seq != UINT_MAX) + WARN_ON_ONCE(mas->ld_seq != seq); +#endif /* CONFIG_LOCKDEP */ } -void mas_init_lock_check(struct ma_state *mas) +static void mas_init_lock_check(struct ma_state *mas) { -#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) +#ifdef CONFIG_LOCKDEP + struct lockdep_map *map; +#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD if (!mt_locked(mas->tree)) { if (mt_in_rcu(mas->tree)) mas->rcu_gp = get_state_synchronize_rcu(); + return; } -#endif +#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */ + + map = mas_lockdep_map(mas); + if (map) /* Update regardless of lock state */ + mas->ld_seq = lock_sequence(map); +#endif /* CONFIG_LOCKDEP */ } static void mas_may_init_lock_check(struct ma_state *mas) { -#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) - if (mas_is_start(mas) || mas_is_paused(mas)) +#ifdef CONFIG_LOCKDEP +#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD + if (mas_is_start(mas) || mas_is_paused(mas)) { mas_init_lock_check(mas); - else - mas_lock_check(mas); -#endif + return; + } +#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */ + mas_lock_check(mas); +#endif /* CONFIG_LOCKDEP */ } /* @@ -4864,6 +4901,7 @@ void *mas_store(struct ma_state *mas, void *entry) { MA_WR_STATE(wr_mas, mas, entry); + mas_may_init_lock_check(mas); trace_ma_write(TP_FCT, mas, 0, entry); #ifdef CONFIG_DEBUG_MAPLE_TREE if (MAS_WARN_ON(mas, mas->index > mas->last)) @@ -4922,6 +4960,7 @@ int mas_store_gfp(struct ma_state *mas, void *entry, gfp_t gfp) MA_WR_STATE(wr_mas, mas, entry); int ret = 0; + mas_may_init_lock_check(mas); retry: mas_wr_preallocate(&wr_mas, entry); if (unlikely(mas_nomem(mas, gfp))) { @@ -4952,6 +4991,7 @@ void mas_store_prealloc(struct ma_state *mas, void *entry) { MA_WR_STATE(wr_mas, mas, entry); + mas_lock_check(mas); if (mas->store_type == wr_store_root) { mas_wr_prealloc_setup(&wr_mas); goto store; @@ -4984,6 +5024,7 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp) { MA_WR_STATE(wr_mas, mas, entry); + mas_may_init_lock_check(mas); mas_wr_prealloc_setup(&wr_mas); mas->store_type = mas_wr_store_type(&wr_mas); mas_prealloc_calc(&wr_mas, entry); @@ -5469,7 +5510,6 @@ EXPORT_SYMBOL_GPL(mas_find_range); static bool mas_find_rev_setup(struct ma_state *mas, unsigned long min, void **entry) { - switch (mas->status) { case ma_active: goto active; -- 2.47.3