[PATCH 1/3] mm: workingset: remove local_irq_disable() from count_shadow_nodes()

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

In commit 0c7c1bed7e13 ("mm: make counting of list_lru_one::nr_items
lockless") the
	spin_lock(&nlru->lock);

statement was replaced with
	rcu_read_lock();

in __list_lru_count_one(). The comment in count_shadow_nodes() says that
the local_irq_disable() is required because the lock must be acquired
with disabled interrupts and (spin_lock()) does not do so.
Since the lock is replaced with rcu_read_lock() the local_irq_disable()
is no longer needed. The code path is
  list_lru_shrink_count()
    -> list_lru_count_one()
      -> __list_lru_count_one()
        -> rcu_read_lock()
        -> list_lru_from_memcg_idx()
        -> rcu_read_unlock()

Remove the local_irq_disable() statement.

Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 mm/workingset.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mm/workingset.c b/mm/workingset.c
index 40ee02c83978..ed8151180899 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -366,10 +366,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	unsigned long nodes;
 	unsigned long cache;
 
-	/* list_lru lock nests inside the IRQ-safe i_pages lock */
-	local_irq_disable();
 	nodes = list_lru_shrink_count(&shadow_nodes, sc);
-	local_irq_enable();
 
 	/*
 	 * Approximate a reasonable limit for the radix tree nodes
-- 
2.18.0