1 files changed, 46 insertions, 16 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 76e2a6f3749f..4749e52106ba 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1171,7 +1171,7 @@ static int unmap_and_move(new_page_t get_new_page,
 	struct page *newpage = NULL;
 
 	if (!thp_migration_supported() && PageTransHuge(page))
-		return -ENOMEM;
+		return -ENOSYS;
 
 	if (page_count(page) == 1) {
 		/* page was freed from under us. So we are done. */
@@ -1378,6 +1378,20 @@ out:
 	return rc;
 }
 
+static inline int try_split_thp(struct page *page, struct page **page2,
+				struct list_head *from)
+{
+	int rc = 0;
+
+	lock_page(page);
+	rc = split_huge_page_to_list(page, from);
+	unlock_page(page);
+	if (!rc)
+		list_safe_reset_next(page, *page2, lru);
+
+	return rc;
+}
+
 /*
  * migrate_pages - migrate the pages specified in a list, to the free pages
  *		   supplied as the target for the page migration
@@ -1455,24 +1469,40 @@ retry:
 			 *		     from list
 			 */
 			switch(rc) {
+			/*
+			 * THP migration might be unsupported or the
+			 * allocation could've failed so we should
+			 * retry on the same page with the THP split
+			 * to base pages.
+			 *
+			 * Head page is retried immediately and tail
+			 * pages are added to the tail of the list so
+			 * we encounter them after the rest of the list
+			 * is processed.
+			 */
+			case -ENOSYS:
+				/* THP migration is unsupported */
+				if (is_thp) {
+					if (!try_split_thp(page, &page2, from)) {
+						nr_thp_split++;
+						goto retry;
+					}
+
+					nr_thp_failed++;
+					nr_failed += nr_subpages;
+					break;
+				}
+
+				/* Hugetlb migration is unsupported */
+				nr_failed++;
+				break;
 			case -ENOMEM:
 				/*
-				 * THP migration might be unsupported or the
-				 * allocation could've failed so we should
-				 * retry on the same page with the THP split
-				 * to base pages.
-				 *
-				 * Head page is retried immediately and tail
-				 * pages are added to the tail of the list so
-				 * we encounter them after the rest of the list
-				 * is processed.
+				 * When memory is low, don't bother to try to migrate
+				 * other pages, just exit.
 				 */
 				if (is_thp) {
-					lock_page(page);
-					rc = split_huge_page_to_list(page, from);
-					unlock_page(page);
-					if (!rc) {
-						list_safe_reset_next(page, page2, lru);
+					if (!try_split_thp(page, &page2, from)) {
 						nr_thp_split++;
 						goto retry;
 					}
@@ -1500,7 +1530,7 @@ retry:
 				break;
 			default:
 				/*
-				 * Permanent failure (-EBUSY, -ENOSYS, etc.):
+				 * Permanent failure (-EBUSY, etc.):
 				 * unlike -EAGAIN case, the failed page is
 				 * removed from migration page list and not
 				 * retried in the next outer loop.