lock_page_lruvec() and its variants used rcu_read_lock() with the
intention of safeguarding against the mem_cgroup being destroyed
concurrently; but so long as they are called under the specified
conditions (as they are), there is no way for the page's mem_cgroup
to be destroyed. Delete the unnecessary rcu_read_lock() and _unlock().
Hugh Dickin's polished the commit log, Thanks a lot!
Signed-off-by: Alex Shi <alex....@linux.alibaba.com>
Acked-by: Hugh Dickins <hu...@google.com>
Cc: Hugh Dickins <hu...@google.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Michal Hocko <mho...@kernel.org>
Cc: Vladimir Davydov <vdavydov....@gmail.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: cgro...@vger.kernel.org
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/memcontrol.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8d400efc81b9..0af13c4fe4b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1356,10 +1356,8 @@ struct lruvec *lock_page_lruvec(struct page *page)
struct lruvec *lruvec;
struct pglist_data *pgdat = page_pgdat(page);
- rcu_read_lock();
lruvec = mem_cgroup_page_lruvec(page, pgdat);
spin_lock(&lruvec->lru_lock);
- rcu_read_unlock();
lruvec_memcg_debug(lruvec, page);
@@ -1371,10 +1369,8 @@ struct lruvec *lock_page_lruvec_irq(struct page *page)
struct lruvec *lruvec;
struct pglist_data *pgdat = page_pgdat(page);
- rcu_read_lock();
lruvec = mem_cgroup_page_lruvec(page, pgdat);
spin_lock_irq(&lruvec->lru_lock);
- rcu_read_unlock();
lruvec_memcg_debug(lruvec, page);
@@ -1386,10 +1382,8 @@ struct lruvec *lock_page_lruvec_irqsave(struct page
*page, unsigned long *flags)
struct lruvec *lruvec;
struct pglist_data *pgdat = page_pgdat(page);
- rcu_read_lock();
lruvec = mem_cgroup_page_lruvec(page, pgdat);
spin_lock_irqsave(&lruvec->lru_lock, *flags);
- rcu_read_unlock();
lruvec_memcg_debug(lruvec, page);
--
2.29.GIT
