mm: add free_hot_cold_page_list() helper

This patch adds helper free_hot_cold_page_list() to free list of 0-order
pages.  It frees pages directly from list without temporary page-vector.
It also calls trace_mm_pagevec_free() to simulate pagevec_free()
behaviour.

bloat-o-meter:

add/remove: 1/1 grow/shrink: 1/3 up/down: 267/-295 (-28)
function                                     old     new   delta
free_hot_cold_page_list                        -     264    +264
get_page_from_freelist                      2129    2132      +3
__pagevec_free                               243     239      -4
split_free_page                              380     373      -7
release_pages                                606     510     -96
free_page_list                               188       -    -188

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/gfp.h

@@ -358,6 +358,7 @@ void *alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
 extern void __free_pages(struct page *page, unsigned int order);
 extern void free_pages(unsigned long addr, unsigned int order);
 extern void free_hot_cold_page(struct page *page, int cold);
+extern void free_hot_cold_page_list(struct list_head *list, int cold);
 
 #define __free_page(page) __free_pages((page), 0)
 #define free_page(addr) free_pages((addr), 0)

mm/page_alloc.c

@@ -1188,6 +1188,19 @@ out:
 	local_irq_restore(flags);
 }
 
+/*
+ * Free a list of 0-order pages
+ */
+void free_hot_cold_page_list(struct list_head *list, int cold)
+{
+	struct page *page, *next;
+
+	list_for_each_entry_safe(page, next, list, lru) {
+		trace_mm_pagevec_free(page, cold);
+		free_hot_cold_page(page, cold);
+	}
+}
+
 /*
  * split_page takes a non-compound higher-order page, and splits it into
  * n (1<<order) sub-pages: page[0..n]

mm/swap.c

@@ -585,11 +585,10 @@ int lru_add_drain_all(void)
 void release_pages(struct page **pages, int nr, int cold)
 {
 	int i;
-	struct pagevec pages_to_free;
+	LIST_HEAD(pages_to_free);
 	struct zone *zone = NULL;
 	unsigned long uninitialized_var(flags);
 
-	pagevec_init(&pages_to_free, cold);
 	for (i = 0; i < nr; i++) {
 		struct page *page = pages[i];
 
@@ -620,19 +619,12 @@ void release_pages(struct page **pages, int nr, int cold)
 			del_page_from_lru(zone, page);
 		}
 
-		if (!pagevec_add(&pages_to_free, page)) {
+		list_add(&page->lru, &pages_to_free);
-			if (zone) {
-				spin_unlock_irqrestore(&zone->lru_lock, flags);
-				zone = NULL;
-			}
-			__pagevec_free(&pages_to_free);
-			pagevec_reinit(&pages_to_free);
-  		}
 	}
 	if (zone)
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 
-	pagevec_free(&pages_to_free);
+	free_hot_cold_page_list(&pages_to_free, cold);
 }
 EXPORT_SYMBOL(release_pages);
 

mm/vmscan.c

@@ -734,24 +734,6 @@ static enum page_references page_check_references(struct page *page,
 	return PAGEREF_RECLAIM;
 }
 
-static noinline_for_stack void free_page_list(struct list_head *free_pages)
-{
-	struct pagevec freed_pvec;
-	struct page *page, *tmp;
-
-	pagevec_init(&freed_pvec, 1);
-
-	list_for_each_entry_safe(page, tmp, free_pages, lru) {
-		list_del(&page->lru);
-		if (!pagevec_add(&freed_pvec, page)) {
-			__pagevec_free(&freed_pvec);
-			pagevec_reinit(&freed_pvec);
-		}
-	}
-
-	pagevec_free(&freed_pvec);
-}
-
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
@@ -1015,7 +997,7 @@ keep_lumpy:
 	if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc))
 		zone_set_flag(zone, ZONE_CONGESTED);
 
-	free_page_list(&free_pages);
+	free_hot_cold_page_list(&free_pages, 1);
 
 	list_splice(&ret_pages, page_list);
 	count_vm_events(PGACTIVATE, pgactivate);