From 453742ba5b3cf36af348c1313f2b32f7ea4c5897 Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Tue, 27 May 2025 02:06:38 +0800 Subject: [PATCH] mm, list_lru: refactor the locking code Cocci is confused by the try lock then release RCU and return logic here. So separate the try lock part out into a standalone helper. The code is easier to follow too. No feature change, fixes: cocci warnings: (new ones prefixed by >>) >> mm/list_lru.c:82:3-9: preceding lock on line 77 >> mm/list_lru.c:82:3-9: preceding lock on line 77 mm/list_lru.c:82:3-9: preceding lock on line 75 mm/list_lru.c:82:3-9: preceding lock on line 75 Link: https://lkml.kernel.org/r/20250526180638.14609-1-ryncsn@gmail.com Signed-off-by: Kairui Song Reported-by: kernel test robot Reported-by: Julia Lawall Closes: https://lore.kernel.org/r/202505252043.pbT1tBHJ-lkp@intel.com/ Reviewed-by: Qi Zheng Reviewed-by: Muchun Song Reviewed-by: SeongJae Park Cc: Chengming Zhou Cc: Johannes Weiner Cc: Kairui Song Cc: Roman Gushchin Signed-off-by: Andrew Morton --- mm/list_lru.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index 490473af31226..ec48b5dadf519 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -60,30 +60,34 @@ list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx) return &lru->node[nid].lru; } +static inline bool lock_list_lru(struct list_lru_one *l, bool irq) +{ + if (irq) + spin_lock_irq(&l->lock); + else + spin_lock(&l->lock); + if (unlikely(READ_ONCE(l->nr_items) == LONG_MIN)) { + if (irq) + spin_unlock_irq(&l->lock); + else + spin_unlock(&l->lock); + return false; + } + return true; +} + static inline struct list_lru_one * lock_list_lru_of_memcg(struct list_lru *lru, int nid, struct mem_cgroup *memcg, bool irq, bool skip_empty) { struct list_lru_one *l; - long nr_items; rcu_read_lock(); again: l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg)); - if (likely(l)) { - if (irq) - spin_lock_irq(&l->lock); - else - spin_lock(&l->lock); - nr_items = READ_ONCE(l->nr_items); - if (likely(nr_items != LONG_MIN)) { - rcu_read_unlock(); - return l; - } - if (irq) - spin_unlock_irq(&l->lock); - else - spin_unlock(&l->lock); + if (likely(l) && lock_list_lru(l, irq)) { + rcu_read_unlock(); + return l; } /* * Caller may simply bail out if raced with reparenting or -- 2.47.2