1 files changed, 41 insertions, 35 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 514fd8008114..822babd808fe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2301,7 +2301,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 {
 	struct zone *last_compact_zone = NULL;
 	unsigned long compact_result;
-
+	struct page *page;
 
 	if (!order)
 		return NULL;
@@ -2313,49 +2313,55 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 						&last_compact_zone);
 	current->flags &= ~PF_MEMALLOC;
 
-	if (compact_result > COMPACT_DEFERRED)
-		count_vm_event(COMPACTSTALL);
-	else
+	switch (compact_result) {
+	case COMPACT_DEFERRED:
 		*deferred_compaction = true;
+		/* fall-through */
+	case COMPACT_SKIPPED:
+		return NULL;
+	default:
+		break;
+	}
 
-	if (compact_result > COMPACT_SKIPPED) {
-		struct page *page;
+	/*
+	 * At least in one zone compaction wasn't deferred or skipped, so let's
+	 * count a compaction stall
+	 */
+	count_vm_event(COMPACTSTALL);
 
-		/* Page migration frees to the PCP lists but we want merging */
-		drain_pages(get_cpu());
-		put_cpu();
+	/* Page migration frees to the PCP lists but we want merging */
+	drain_pages(get_cpu());
+	put_cpu();
 
-		page = get_page_from_freelist(gfp_mask, nodemask,
-				order, zonelist, high_zoneidx,
-				alloc_flags & ~ALLOC_NO_WATERMARKS,
-				preferred_zone, classzone_idx, migratetype);
+	page = get_page_from_freelist(gfp_mask, nodemask,
+			order, zonelist, high_zoneidx,
+			alloc_flags & ~ALLOC_NO_WATERMARKS,
+			preferred_zone, classzone_idx, migratetype);
 
-		if (page) {
-			struct zone *zone = page_zone(page);
+	if (page) {
+		struct zone *zone = page_zone(page);
 
-			zone->compact_blockskip_flush = false;
-			compaction_defer_reset(zone, order, true);
-			count_vm_event(COMPACTSUCCESS);
-			return page;
-		}
+		zone->compact_blockskip_flush = false;
+		compaction_defer_reset(zone, order, true);
+		count_vm_event(COMPACTSUCCESS);
+		return page;
+	}
 
-		/*
-		 * last_compact_zone is where try_to_compact_pages thought
-		 * allocation should succeed, so it did not defer compaction.
-		 * But now we know that it didn't succeed, so we do the defer.
-		 */
-		if (last_compact_zone && mode != MIGRATE_ASYNC)
-			defer_compaction(last_compact_zone, order);
+	/*
+	 * last_compact_zone is where try_to_compact_pages thought allocation
+	 * should succeed, so it did not defer compaction. But here we know
+	 * that it didn't succeed, so we do the defer.
+	 */
+	if (last_compact_zone && mode != MIGRATE_ASYNC)
+		defer_compaction(last_compact_zone, order);
 
-		/*
-		 * It's bad if compaction run occurs and fails.
-		 * The most likely reason is that pages exist,
-		 * but not enough to satisfy watermarks.
-		 */
-		count_vm_event(COMPACTFAIL);
+	/*
+	 * It's bad if compaction run occurs and fails. The most likely reason
+	 * is that pages exist, but not enough to satisfy watermarks.
+	 */
+	count_vm_event(COMPACTFAIL);
 
-		cond_resched();
-	}
+	cond_resched();
 
 	return NULL;
 }