linux-kernel - [PATCH v6 09/10] mm/memcg: fold lock in lock_page

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Date:   Mon, 16 Dec 2019 17:26:25 +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:     Alex Shi <alex.shi@...ux.alibaba.com>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
Subject: [PATCH v6 09/10] mm/memcg: fold lock in lock_page_lru

According to the calling path of commit_charge, the lrucare is bound
with PageLRU, so we could just fold it under PageLRU. This has no
functional change.

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: cgroups@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
---
 mm/memcontrol.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 138f298b694f..f8e279487e1d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2621,9 +2621,10 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 
 static struct lruvec *lock_page_lru(struct page *page, int *isolated)
 {
-	struct lruvec *lruvec = lock_page_lruvec_irq(page);
+	struct lruvec *lruvec = NULL;
 
 	if (PageLRU(page)) {
+		lruvec = lock_page_lruvec_irq(page);
 
 		ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec, page_lru(page));
@@ -2637,17 +2638,18 @@ static struct lruvec *lock_page_lru(struct page *page, int *isolated)
 static void unlock_page_lru(struct page *page, int isolated,
 				struct lruvec *locked_lruvec)
 {
-	struct lruvec *lruvec;
+	if (isolated) {
+		struct lruvec *lruvec;
 
-	unlock_page_lruvec_irq(locked_lruvec);
-	lruvec = lock_page_lruvec_irq(page);
+		if (locked_lruvec)
+			unlock_page_lruvec_irq(locked_lruvec);
+		lruvec = lock_page_lruvec_irq(page);
 
-	if (isolated) {
 		VM_BUG_ON_PAGE(PageLRU(page), page);
 		SetPageLRU(page);
 		add_page_to_lru_list(page, lruvec, page_lru(page));
+		unlock_page_lruvec_irq(lruvec);
 	}
-	unlock_page_lruvec_irq(lruvec);
 }
 
 static void commit_charge(struct page *page, struct mem_cgroup *memcg,
-- 
1.8.3.1