[PATCH 3/4] mm/migration: return errno when isolate_huge_page failed

[Miaohe Lin]

We might fail to isolate huge page due to e.g. the page is under migration
which cleared HPageMigratable. So we should return -EBUSY in this case
rather than always return 1 which could confuse the user.

Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration")
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/migrate.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 381963231a62..044656a14ae2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1632,10 +1632,8 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 		goto out_putpage;
 
 	if (PageHuge(page)) {
-		if (PageHead(page)) {
-			isolate_huge_page(page, pagelist);
-			err = 1;
-		}
+		if (PageHead(page))
+			err = isolate_huge_page(page, pagelist) ? 1 : -EBUSY;
 	} else {
 		struct page *head;
 
-- 
2.23.0