1 files changed, 26 insertions, 29 deletions

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 63a3db10a8c0..abbf42214485 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -17,22 +17,21 @@
 
 static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
 {
-	struct page *unmovable = NULL;
-	struct zone *zone;
+	struct zone *zone = page_zone(page);
+	struct page *unmovable;
 	unsigned long flags;
-	int ret = -EBUSY;
-
-	zone = page_zone(page);
 
 	spin_lock_irqsave(&zone->lock, flags);
 
 	/*
 	 * We assume the caller intended to SET migrate type to isolate.
 	 * If it is already set, then someone else must have raced and
-	 * set it before us.  Return -EBUSY
+	 * set it before us.
 	 */
-	if (is_migrate_isolate_page(page))
-		goto out;
+	if (is_migrate_isolate_page(page)) {
+		spin_unlock_irqrestore(&zone->lock, flags);
+		return -EBUSY;
+	}
 
 	/*
 	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
@@ -49,25 +48,21 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
 									NULL);
 
 		__mod_zone_freepage_state(zone, -nr_pages, mt);
-		ret = 0;
+		spin_unlock_irqrestore(&zone->lock, flags);
+		drain_all_pages(zone);
+		return 0;
 	}
 
-out:
 	spin_unlock_irqrestore(&zone->lock, flags);
-	if (!ret) {
-		drain_all_pages(zone);
-	} else {
-		WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
-
-		if ((isol_flags & REPORT_FAILURE) && unmovable)
-			/*
-			 * printk() with zone->lock held will likely trigger a
-			 * lockdep splat, so defer it here.
-			 */
-			dump_page(unmovable, "unmovable page");
+	if (isol_flags & REPORT_FAILURE) {
+		/*
+		 * printk() with zone->lock held will likely trigger a
+		 * lockdep splat, so defer it here.
+		 */
+		dump_page(unmovable, "unmovable page");
 	}
 
-	return ret;
+	return -EBUSY;
 }
 
 static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
@@ -93,7 +88,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 	 * these pages to be merged.
 	 */
 	if (PageBuddy(page)) {
-		order = page_order(page);
+		order = buddy_order(page);
 		if (order >= pageblock_order) {
 			pfn = page_to_pfn(page);
 			buddy_pfn = __find_buddy_pfn(pfn, order);
@@ -111,6 +106,11 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 	 * If we isolate freepage with more than pageblock_order, there
 	 * should be no freepage in the range, so we could avoid costly
 	 * pageblock scanning for freepage moving.
+	 *
+	 * We didn't actually touch any of the isolated pages, so place them
+	 * to the tail of the freelist. This is an optimization for memory
+	 * onlining - just onlined memory won't immediately be considered for
+	 * allocation.
 	 */
 	if (!isolated_page) {
 		nr_pages = move_freepages_block(zone, page, migratetype, NULL);
@@ -178,8 +178,7 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages)
  * (e.g. __offline_pages will need to call it after check for isolated range for
  * a next retry).
  *
- * Return: the number of isolated pageblocks on success and -EBUSY if any part
- * of range cannot be isolated.
+ * Return: 0 on success and -EBUSY if any part of range cannot be isolated.
  */
 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			     unsigned migratetype, int flags)
@@ -187,7 +186,6 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 	unsigned long pfn;
 	unsigned long undo_pfn;
 	struct page *page;
-	int nr_isolate_pageblock = 0;
 
 	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
 	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
@@ -201,10 +199,9 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 				undo_pfn = pfn;
 				goto undo;
 			}
-			nr_isolate_pageblock++;
 		}
 	}
-	return nr_isolate_pageblock;
+	return 0;
 undo:
 	for (pfn = start_pfn;
 	     pfn < undo_pfn;
@@ -264,7 +261,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 			 * the correct MIGRATE_ISOLATE freelist. There is no
 			 * simple way to verify that as VM_BUG_ON(), though.
 			 */
-			pfn += 1 << page_order(page);
+			pfn += 1 << buddy_order(page);
 		else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
 			/* A HWPoisoned page cannot be also PageBuddy */
 			pfn++;