Revert "BACKPORT: mm: fix pageblock heuristic"

This reverts commit 81da353e5d0c2f2a8f2cc2f6f2541d481836bb35.
1petro · Sep 24, 2020 · bb579c4 · bb579c4
1 parent 0eb678a
commit bb579c4
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Showing 3 changed files with 12 additions and 17 deletions.
diff --git a/mm/compaction.c b/mm/compaction.c
@@ -1345,7 +1345,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc,
 		 * other migratetype buddy lists.
 		 */
 		if (find_suitable_fallback(area, order, migratetype,
-						true, cc->order, &can_steal) != -1)
+						true, &can_steal) != -1)
 			return COMPACT_PARTIAL;
 	}
 

diff --git a/mm/internal.h b/mm/internal.h
@@ -250,8 +250,9 @@ isolate_freepages_range(struct compact_control *cc,
 unsigned long
 isolate_migratepages_range(struct compact_control *cc,
 			   unsigned long low_pfn, unsigned long end_pfn);
-int find_suitable_fallback(struct free_area *area, unsigned int current_order,
-			int migratetype, bool only_stealable, int start_order, bool *can_steal);
+int find_suitable_fallback(struct free_area *area, unsigned int order,
+			int migratetype, bool only_stealable, bool *can_steal);
+
 #endif
 
 /*

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
@@ -1655,8 +1655,7 @@ static void change_pageblock_range(struct page *pageblock_page,
  * is worse than movable allocations stealing from unmovable and reclaimable
  * pageblocks.
  */
-static bool can_steal_fallback(unsigned int current_order, unsigned int start_order,
-			       int start_mt, int fallback_mt)
+static bool can_steal_fallback(unsigned int order, int start_mt)
 {
 	/*
 	 * Leaving this order check is intended, although there is
@@ -1665,17 +1664,12 @@ static bool can_steal_fallback(unsigned int current_order, unsigned int start_or
 	 * but, below check doesn't guarantee it and that is just heuristic
 	 * so could be changed anytime.
 	 */
-	if (current_order >= pageblock_order)
+	if (order >= pageblock_order)
 		return true;
 
-	/* don't let unmovable allocations cause migrations simply because of free pages */
-	if ((start_mt != MIGRATE_UNMOVABLE && current_order >= pageblock_order / 2) ||
-	        /* only steal reclaimable page blocks for unmovable allocations */
-	        (start_mt == MIGRATE_UNMOVABLE && fallback_mt != MIGRATE_MOVABLE && current_order >= pageblock_order / 2) ||
-	        /* reclaimable can steal aggressively */
+	if (order >= pageblock_order / 2 ||
 		start_mt == MIGRATE_RECLAIMABLE ||
-		/* allow unmovable allocs up to 64K without migrating blocks */
-		(start_mt == MIGRATE_UNMOVABLE && start_order >= 5) ||
+		start_mt == MIGRATE_UNMOVABLE ||
 		page_group_by_mobility_disabled)
 		return true;
 
@@ -1715,8 +1709,8 @@ static void steal_suitable_fallback(struct zone *zone, struct page *page,
  * we can steal other freepages all together. This would help to reduce
  * fragmentation due to mixed migratetype pages in one pageblock.
  */
-int find_suitable_fallback(struct free_area *area, unsigned int current_order,
-			int migratetype, bool only_stealable, int start_order, bool *can_steal)
+int find_suitable_fallback(struct free_area *area, unsigned int order,
+			int migratetype, bool only_stealable, bool *can_steal)
 {
 	int i;
 	int fallback_mt;
@@ -1733,7 +1727,7 @@ int find_suitable_fallback(struct free_area *area, unsigned int current_order,
 		if (list_empty(&area->free_list[fallback_mt]))
 			continue;
 
-		if (can_steal_fallback(current_order, start_order, migratetype, fallback_mt))
+		if (can_steal_fallback(order, migratetype))
 			*can_steal = true;
 
 		if (!only_stealable)
@@ -1869,7 +1863,7 @@ __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype)
 				--current_order) {
 		area = &(zone->free_area[current_order]);
 		fallback_mt = find_suitable_fallback(area, current_order,
-				start_migratetype, false, order, &can_steal);
+				start_migratetype, false, &can_steal);
 		if (fallback_mt == -1)
 			continue;