[PATCH v6 03/10] mm/lru: introduce the relock_page_lruvec function

From: Alex Shi <alex.shi@linux.alibaba.com>
To: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, akpm@linux-foundation.org,
	mgorman@techsingularity.net, tj@kernel.org, hughd@google.com,
	khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com,
	yang.shi@linux.alibaba.com, willy@infradead.org,
	shakeelb@google.com, hannes@cmpxchg.org
Cc: Alex Shi <alex.shi@linux.alibaba.com>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Roman Gushchin <guro@fb.com>, Chris Down <chris@chrisdown.name>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vlastimil Babka <vbabka@suse.cz>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	swkhack <swkhack@gmail.com>,
	"Potyra, Stefan" <Stefan.Potyra@elektrobit.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	Peng Fan <peng.fan@nxp.com>, Nikolay Borisov <nborisov@suse.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH v6 03/10] mm/lru: introduce the relock_page_lruvec function
Date: Mon, 16 Dec 2019 17:26:19 +0800	[thread overview]
Message-ID: <1576488386-32544-4-git-send-email-alex.shi@linux.alibaba.com> (raw)
In-Reply-To: <1576488386-32544-1-git-send-email-alex.shi@linux.alibaba.com>

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@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: swkhack <swkhack@gmail.com>
Cc: "Potyra, Stefan" <Stefan.Potyra@elektrobit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.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 017901112789..be8bca45f7c6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4343,14 +4343,10 @@ 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

