[PATCH v17 12/21] mm/lru: move lock into lru_note_cost

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

This patch move lru_lock into lru_note_cost. It's a bit ugly and may
cost more locking, but it's necessary for later per pgdat lru_lock to
per memcg lru_lock change.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 mm/swap.c   | 5 +++--
 mm/vmscan.c | 4 +---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index b88ca630db70..f645965fde0e 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -269,7 +269,9 @@ void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
 {
 	do {
 		unsigned long lrusize;
+		struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 
+		spin_lock_irq(&pgdat->lru_lock);
 		/* Record cost event */
 		if (file)
 			lruvec->file_cost += nr_pages;
@@ -293,15 +295,14 @@ void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
 			lruvec->file_cost /= 2;
 			lruvec->anon_cost /= 2;
 		}
+		spin_unlock_irq(&pgdat->lru_lock);
 	} while ((lruvec = parent_lruvec(lruvec)));
 }
 
 void lru_note_cost_page(struct page *page)
 {
-	spin_lock_irq(&page_pgdat(page)->lru_lock);
 	lru_note_cost(mem_cgroup_page_lruvec(page, page_pgdat(page)),
 		      page_is_file_lru(page), hpage_nr_pages(page));
-	spin_unlock_irq(&page_pgdat(page)->lru_lock);
 }
 
 static void __activate_page(struct page *page, struct lruvec *lruvec)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ddb29d813d77..c1c4259b4de5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1976,19 +1976,17 @@ static int current_may_throttle(void)
 				&stat, false);
 
 	spin_lock_irq(&pgdat->lru_lock);
-
 	move_pages_to_lru(lruvec, &page_list);
 
 	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
-	lru_note_cost(lruvec, file, stat.nr_pageout);
 	item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;
 	if (!cgroup_reclaim(sc))
 		__count_vm_events(item, nr_reclaimed);
 	__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
 	__count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
-
 	spin_unlock_irq(&pgdat->lru_lock);
 
+	lru_note_cost(lruvec, file, stat.nr_pageout);
 	mem_cgroup_uncharge_list(&page_list);
 	free_unref_page_list(&page_list);
 
-- 
1.8.3.1