mm: remove del_page_from_lru, add page_off_lru

del_page_from_lru() repeats del_page_from_lru_list(), also working out
which LRU the page was on, clearing the relevant bits.  Decouple those
functions: remove del_page_from_lru() and add page_off_lru().

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.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 0d1b24b..b0f529b 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -53,7 +53,7 @@
 		spin_lock_irqsave(&zone->lru_lock, flags);
 		VM_BUG_ON(!PageLRU(page));
 		__ClearPageLRU(page);
-		del_page_from_lru(zone, page);
+		del_page_from_lru_list(zone, page, page_off_lru(page));
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
 }
@@ -617,7 +617,7 @@
 			}
 			VM_BUG_ON(!PageLRU(page));
 			__ClearPageLRU(page);
-			del_page_from_lru(zone, page);
+			del_page_from_lru_list(zone, page, page_off_lru(page));
 		}
 
 		list_add(&page->lru, &pages_to_free);