From 60ec6a48eec24986a6414740a2481d22efc1b2f9 Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Fri, 5 Nov 2021 13:37:47 -0700 Subject: mm: list_lru: remove holding lru lock Since commit e5bc3af7734f ("rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()"), the critical section of spin lock can serve as an RCU read-side critical section which already allows readers that hold nlru->lock to avoid taking rcu lock. So just remove holding lock. Link: https://lkml.kernel.org/r/20211025124534.56345-1-songmuchun@bytedance.com Signed-off-by: Muchun Song Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Roman Gushchin Cc: Shakeel Butt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/list_lru.c | 11 ----------- 1 file changed, 11 deletions(-) (limited to 'mm/list_lru.c') diff --git a/mm/list_lru.c b/mm/list_lru.c index a6031f1c5bd7..9a1f7df1afc9 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -398,18 +398,7 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, } memcpy(&new->lru, &old->lru, flex_array_size(new, lru, old_size)); - - /* - * The locking below allows readers that hold nlru->lock avoid taking - * rcu_read_lock (see list_lru_from_memcg_idx). - * - * Since list_lru_{add,del} may be called under an IRQ-safe lock, - * we have to use IRQ-safe primitives here to avoid deadlock. - */ - spin_lock_irq(&nlru->lock); rcu_assign_pointer(nlru->memcg_lrus, new); - spin_unlock_irq(&nlru->lock); - kvfree_rcu(old, rcu); return 0; } -- cgit v1.2.3-70-g09d2