On 22.06.2018 18:12, Sebastian Andrzej Siewior wrote:
> 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@xxxxxxxxxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Looks good for me.
Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
> ---
> 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
>
