mm: page_alloc: change fallbacks array handling

This commit adds a row for MIGRATE_ISOLATE type to the fallbacks array
which was missing from it.  It also, changes the array traversal logic
a little making MIGRATE_RESERVE an end marker.  The letter change,
removes the implicit MIGRATE_UNMOVABLE from the end of each row which
was read by __rmqueue_fallback() function.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2c38a30d064e..d6b580c660f5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -875,11 +875,12 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
  * This array describes the order lists are fallen back to when
  * the free lists for the desirable migrate type are depleted
  */
-static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
+static int fallbacks[MIGRATE_TYPES][3] = {
         [MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_RESERVE },
         [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_RESERVE },
         [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
-        [MIGRATE_RESERVE]     = { MIGRATE_RESERVE,     MIGRATE_RESERVE,   MIGRATE_RESERVE }, /* Never used */
+        [MIGRATE_RESERVE]     = { MIGRATE_RESERVE }, /* Never used */
+        [MIGRATE_ISOLATE]     = { MIGRATE_RESERVE }, /* Never used */
 };
 
 /*
@@ -974,12 +975,12 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
         /* Find the largest possible block of pages in the other list */
         for (current_order = MAX_ORDER-1; current_order >= order;
                                                 --current_order) {
-                for (i = 0; i < MIGRATE_TYPES - 1; i++) {
+                for (i = 0;; i++) {
                         migratetype = fallbacks[start_migratetype][i];
 
                         /* MIGRATE_RESERVE handled later if necessary */
                         if (migratetype == MIGRATE_RESERVE)
-                                continue;
+                                break;
 
                         area = &(zone->free_area[current_order]);
                         if (list_empty(&area->free_list[migratetype]))