mm, vmscan: move lru_lock to the node

Node-based reclaim requires node-based LRUs and locking.  This is a
preparation patch that just moves the lru_lock to the node so later
patches are easier to review.  It is a mechanical change but note this
patch makes contention worse because the LRU lock is hotter and direct
reclaim and kswapd can contend on the same lock even when reclaiming
from different zones.

Link: http://lkml.kernel.org/r/1467970510-21195-3-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap.c b/mm/swap.c
index 616df4d..bf37e5c 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -62,12 +62,12 @@
 		struct lruvec *lruvec;
 		unsigned long flags;
 
-		spin_lock_irqsave(&zone->lru_lock, flags);
+		spin_lock_irqsave(zone_lru_lock(zone), flags);
 		lruvec = mem_cgroup_page_lruvec(page, zone);
 		VM_BUG_ON_PAGE(!PageLRU(page), page);
 		__ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
-		spin_unlock_irqrestore(&zone->lru_lock, flags);
+		spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 	}
 	mem_cgroup_uncharge(page);
 }
@@ -189,16 +189,16 @@
 
 		if (pagezone != zone) {
 			if (zone)
-				spin_unlock_irqrestore(&zone->lru_lock, flags);
+				spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 			zone = pagezone;
-			spin_lock_irqsave(&zone->lru_lock, flags);
+			spin_lock_irqsave(zone_lru_lock(zone), flags);
 		}
 
 		lruvec = mem_cgroup_page_lruvec(page, zone);
 		(*move_fn)(page, lruvec, arg);
 	}
 	if (zone)
-		spin_unlock_irqrestore(&zone->lru_lock, flags);
+		spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 	release_pages(pvec->pages, pvec->nr, pvec->cold);
 	pagevec_reinit(pvec);
 }
@@ -318,9 +318,9 @@
 	struct zone *zone = page_zone(page);
 
 	page = compound_head(page);
-	spin_lock_irq(&zone->lru_lock);
+	spin_lock_irq(zone_lru_lock(zone));
 	__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
-	spin_unlock_irq(&zone->lru_lock);
+	spin_unlock_irq(zone_lru_lock(zone));
 }
 #endif
 
@@ -448,13 +448,13 @@
 	struct zone *zone = page_zone(page);
 	struct lruvec *lruvec;
 
-	spin_lock_irq(&zone->lru_lock);
+	spin_lock_irq(zone_lru_lock(zone));
 	lruvec = mem_cgroup_page_lruvec(page, zone);
 	ClearPageActive(page);
 	SetPageUnevictable(page);
 	SetPageLRU(page);
 	add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
-	spin_unlock_irq(&zone->lru_lock);
+	spin_unlock_irq(zone_lru_lock(zone));
 }
 
 /**
@@ -744,7 +744,7 @@
 		 * same zone. The lock is held only if zone != NULL.
 		 */
 		if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
-			spin_unlock_irqrestore(&zone->lru_lock, flags);
+			spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 			zone = NULL;
 		}
 
@@ -759,7 +759,7 @@
 
 		if (PageCompound(page)) {
 			if (zone) {
-				spin_unlock_irqrestore(&zone->lru_lock, flags);
+				spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 				zone = NULL;
 			}
 			__put_compound_page(page);
@@ -771,11 +771,11 @@
 
 			if (pagezone != zone) {
 				if (zone)
-					spin_unlock_irqrestore(&zone->lru_lock,
+					spin_unlock_irqrestore(zone_lru_lock(zone),
 									flags);
 				lock_batch = 0;
 				zone = pagezone;
-				spin_lock_irqsave(&zone->lru_lock, flags);
+				spin_lock_irqsave(zone_lru_lock(zone), flags);
 			}
 
 			lruvec = mem_cgroup_page_lruvec(page, zone);
@@ -790,7 +790,7 @@
 		list_add(&page->lru, &pages_to_free);
 	}
 	if (zone)
-		spin_unlock_irqrestore(&zone->lru_lock, flags);
+		spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 
 	mem_cgroup_uncharge_list(&pages_to_free);
 	free_hot_cold_page_list(&pages_to_free, cold);
@@ -826,7 +826,7 @@
 	VM_BUG_ON_PAGE(PageCompound(page_tail), page);
 	VM_BUG_ON_PAGE(PageLRU(page_tail), page);
 	VM_BUG_ON(NR_CPUS != 1 &&
-		  !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
+		  !spin_is_locked(zone_lru_lock(lruvec_zone(lruvec))));
 
 	if (!list)
 		SetPageLRU(page_tail);