mm/page_alloc.c: use list_for_each_entry in mark_free_pages()

Use list_for_each_entry instead of list_for_each + list_entry to
simplify the code.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -1980,7 +1980,7 @@ void mark_free_pages(struct zone *zone)
 	unsigned long pfn, max_zone_pfn;
 	unsigned long flags;
 	unsigned int order, t;
-	struct list_head *curr;
+	struct page *page;
 
 	if (zone_is_empty(zone))
 		return;
@@ -1990,17 +1990,17 @@ void mark_free_pages(struct zone *zone)
 	max_zone_pfn = zone_end_pfn(zone);
 	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 		if (pfn_valid(pfn)) {
-			struct page *page = pfn_to_page(pfn);
-
+			page = pfn_to_page(pfn);
 			if (!swsusp_page_is_forbidden(page))
 				swsusp_unset_page_free(page);
 		}
 
 	for_each_migratetype_order(order, t) {
-		list_for_each(curr, &zone->free_area[order].free_list[t]) {
+		list_for_each_entry(page,
+				&zone->free_area[order].free_list[t], lru) {
 			unsigned long i;
 
-			pfn = page_to_pfn(list_entry(curr, struct page, lru));
+			pfn = page_to_pfn(page);
 			for (i = 0; i < (1UL << order); i++)
 				swsusp_set_page_free(pfn_to_page(pfn + i));
 		}