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>

include/linux/mm_inline.h

@@ -54,8 +54,14 @@ static inline enum lru_list page_lru_base_type(struct page *page)
 	return LRU_INACTIVE_ANON;
 }
 
-static inline void
-del_page_from_lru(struct zone *zone, struct page *page)
+/**
+ * page_off_lru - which LRU list was page on? clearing its lru flags.
+ * @page: the page to test
+ *
+ * Returns the LRU list a page was on, as an index into the array of LRU
+ * lists; and clears its Unevictable or Active flags, ready for freeing.
+ */
+static inline enum lru_list page_off_lru(struct page *page)
 {
 	enum lru_list lru;
 
@@ -69,9 +75,7 @@ del_page_from_lru(struct zone *zone, struct page *page)
 			lru += LRU_ACTIVE;
 		}
 	}
-	mem_cgroup_lru_del_list(page, lru);
-	list_del(&page->lru);
-	__mod_zone_page_state(zone, NR_LRU_BASE + lru, -hpage_nr_pages(page));
+	return lru;
 }
 
 /**
@@ -92,7 +96,6 @@ static inline enum lru_list page_lru(struct page *page)
 		if (PageActive(page))
 			lru += LRU_ACTIVE;
 	}
-
 	return lru;
 }
 

mm/swap.c

@@ -53,7 +53,7 @@ static void __page_cache_release(struct page *page)
 		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 @@ void release_pages(struct page **pages, int nr, int cold)
 			}
 			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);