[PATCH v9 14/20] mm/lru: introduce the relock_page_lruvec function

Alex Shi
2020-03-02T11:00:24Z

During the lruvec locking, a new page's lruvec is may same as
previous one. Thus we could save a re-locking, and only
change lock iff lruvec is new.

Function named relock_page_lruvec following Hugh Dickins' patch.

Signed-off-by: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: Andrey Ryabinin <aryabinin-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
Cc: Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: Mel Gorman <mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>
Cc: Konstantin Khlebnikov <khlebnikov-XoJtRXgx1JseBXzfvpsJ4g@public.gmane.org>
Cc: Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
---
include/linux/memcontrol.h | 36 ++++++++++++++++++++++++++++++++++++
mm/vmscan.c | 8 ++------
2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index b8a04f0a2ab8..f60009580d2a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1307,6 +1307,42 @@ static inline void dec_lruvec_page_state(struct page *page,
mod_lruvec_page_state(page, idx, -1);
}

+/* Don't lock again iff page's lruvec locked */
+static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
+ struct lruvec *locked_lruvec)
+{
+ struct pglist_data *pgdat = page_pgdat(page);
+ struct lruvec *lruvec;
+
+ lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+ if (likely(locked_lruvec == lruvec))
+ return lruvec;
+
+ if (unlikely(locked_lruvec))
+ unlock_page_lruvec_irq(locked_lruvec);
+
+ return lock_page_lruvec_irq(page);
+}
+
+/* Don't lock again iff page's lruvec locked */
+static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
+ struct lruvec *locked_lruvec, unsigned long *flags)
+{
+ struct pglist_data *pgdat = page_pgdat(page);
+ struct lruvec *lruvec;
+
+ lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+ if (likely(locked_lruvec == lruvec))
+ return lruvec;
+
+ if (unlikely(locked_lruvec))
+ unlock_page_lruvec_irqrestore(locked_lruvec, *flags);
+
+ return lock_page_lruvec_irqsave(page, flags);
+}
+
#ifdef CONFIG_CGROUP_WRITEBACK

struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a58cd5ee9ea1..de925bd629eb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4325,14 +4325,10 @@ void check_move_unevictable_pages(struct pagevec *pvec)

for (i = 0; i < pvec->nr; i++) {
struct page *page = pvec->pages[i];
- struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));

pgscanned++;
- if (lruvec != new_lruvec) {
- if (lruvec)
- unlock_page_lruvec_irq(lruvec);
- lruvec = lock_page_lruvec_irq(page);
- }
+
+ lruvec = relock_page_lruvec_irq(page, lruvec);

if (!TestClearPageLRU(page) || !PageUnevictable(page))
continue;
--
1.8.3.1