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authorMuchun Song <songmuchun@bytedance.com>2021-11-05 23:37:47 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-06 23:30:35 +0300
commit60ec6a48eec24986a6414740a2481d22efc1b2f9 (patch)
tree0132f7845f227774a39350d459b664ee8ec59515 /mm/list_lru.c
parent58056f77502f3567b760c9a8fc8d2e9081515b2d (diff)
downloadlinux-60ec6a48eec24986a6414740a2481d22efc1b2f9.tar.xz
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 <songmuchun@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/list_lru.c')
-rw-r--r--mm/list_lru.c11
1 files changed, 0 insertions, 11 deletions
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;
}