[PATCH v4 5/9] mm/swap: only change the lru_lock iff page's lruvec is different

[Alex Shi <alex.shi@linux.alibaba.com>]

Since we introduced relock_page_lruvec, we could use it in more place
to reduce spin_locks.

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
---
 mm/swap.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 05fee145e382..a023e6095bd9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -197,11 +197,12 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
 	for (i = 0; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
 
-		lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page), &flags);
+		lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
 
 		(*move_fn)(page, lruvec, arg);
-		spin_unlock_irqrestore(&lruvec->lru_lock, flags);
 	}
+	if (lruvec)
+		spin_unlock_irqrestore(&lruvec->lru_lock, flags);
 
 	release_pages(pvec->pages, pvec->nr);
 	pagevec_reinit(pvec);
@@ -820,15 +821,12 @@ void release_pages(struct page **pages, int nr)
 		}
 
 		if (PageLRU(page)) {
-			struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
+			struct lruvec *pre_lruvec = lruvec;
 
-			if (new_lruvec != lruvec) {
-				if (lruvec)
-					spin_unlock_irqrestore(&lruvec->lru_lock, flags);
+			lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
+			if (pre_lruvec != lruvec)
 				lock_batch = 0;
-				lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page), &flags);
 
-			}
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
 			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
-- 
1.8.3.1