linux-kernel - [PATCH v8 04/10] mm/lru: introduce the relock_page

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Date:   Thu, 16 Jan 2020 11:05:03 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, tj@...nel.org, hughd@...gle.com,
        khlebnikov@...dex-team.ru, daniel.m.jordan@...cle.com,
        yang.shi@...ux.alibaba.com, willy@...radead.org,
        shakeelb@...gle.com, hannes@...xchg.org
Cc:     Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>,
        Chris Down <chris@...isdown.name>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        swkhack <swkhack@...il.com>,
        "Potyra, Stefan" <Stefan.Potyra@...ktrobit.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Peng Fan <peng.fan@....com>,
        Nikolay Borisov <nborisov@...e.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH v8 04/10] mm/lru: introduce the relock_page_lruvec function

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@...ux.alibaba.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Vladimir Davydov <vdavydov.dev@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Roman Gushchin <guro@...com>
Cc: Shakeel Butt <shakeelb@...gle.com>
Cc: Chris Down <chris@...isdown.name>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: swkhack <swkhack@...il.com>
Cc: "Potyra, Stefan" <Stefan.Potyra@...ktrobit.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Cc: Peng Fan <peng.fan@....com>
Cc: Nikolay Borisov <nborisov@...e.com>
Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Kirill Tkhai <ktkhai@...tuozzo.com>
Cc: Yang Shi <yang.shi@...ux.alibaba.com>
Cc: Yafang Shao <laoar.shao@...il.com>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: linux-kernel@...r.kernel.org
Cc: cgroups@...r.kernel.org
Cc: linux-mm@...ck.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 8389b9b927ef..09e861df48e8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1299,6 +1299,42 @@ 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 7e1cb41da1fb..ee20a64a7ccc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4355,14 +4355,10 @@ 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 (!PageLRU(page) || !PageUnevictable(page))
 			continue;
-- 
1.8.3.1