The patch titled
Subject: mm/memcg: remove rcu locking for lock_page_lruvec function series
has been added to the -mm tree. Its filename is
mm-memcg-remove-rcu-locking-for-lock_page_lruvec-function-series.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-remove-rcu-locking-for-lock_page_lruvec-function-series.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-remove-rcu-locking-for-lock_page_lruvec-function-series.patch
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------------------------------------------------------
From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Subject: mm/memcg: remove rcu locking for lock_page_lruvec function series
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 Dickins polished the commit log. Thanks a lot!
Link: https://lkml.kernel.org/r/1608614453-10739-2-git-send-email-alex.shi@xxxxxxxxxxxxxxxxx
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 6 ------
1 file changed, 6 deletions(-)
--- a/mm/memcontrol.c~mm-memcg-remove-rcu-locking-for-lock_page_lruvec-function-series
+++ a/mm/memcontrol.c
@@ -1357,10 +1357,8 @@ struct lruvec *lock_page_lruvec(struct p
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);
@@ -1372,10 +1370,8 @@ struct lruvec *lock_page_lruvec_irq(stru
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);
@@ -1387,10 +1383,8 @@ struct lruvec *lock_page_lruvec_irqsave(
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);
_
Patches currently in -mm which might be from alex.shi@xxxxxxxxxxxxxxxxx are
mm-memcg-revise-the-using-condition-of-lock_page_lruvec-function-series.patch
mm-memcg-remove-rcu-locking-for-lock_page_lruvec-function-series.patch
mm-vmscan-__isolate_lru_page_prepare-clean-up.patch
mm-compaction-remove-rcu_read_lock-during-page-compaction.patch
