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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 22 Jun 2018 10:48:51 +0200
Subject: [PATCH 1/3] mm: workingset: remove local_irq_disable() from
count_shadow_nodes()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.5-rt3.tar.xz
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(-)
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -366,10 +366,7 @@ static unsigned long count_shadow_nodes(
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
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