mm/migrate: correct failure handling if !hugepage_migration_support()

We should remove the page from the list if we fail with ENOSYS, since
migrate_pages() consider error cases except -ENOMEM and -EAGAIN as
permanent failure and it assumes that the page would be removed from the
list.  Without this patch, we could overcount number of failure.

In addition, we should put back the new hugepage if
!hugepage_migration_support().  If not, we would leak hugepage memory.

Signed-off-by: Joonsoo Kim <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Reviewed-by: Wanpeng Li <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Cc: Rafael Aquini <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zhang Yanfei <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 5 insertions, 2 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 626ca3c5d07b..13bedcc4656b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1013,7 +1013,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 {
 	int rc = 0;
 	int *result = NULL;
-	struct page *new_hpage = get_new_page(hpage, private, &result);
+	struct page *new_hpage;
 	struct anon_vma *anon_vma = NULL;
 
 	/*
@@ -1023,9 +1023,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	 * tables or check whether the hugepage is pmd-based or not before
 	 * kicking migration.
 	 */
-	if (!hugepage_migration_support(page_hstate(hpage)))
+	if (!hugepage_migration_support(page_hstate(hpage))) {
+		putback_active_hugepage(hpage);
 		return -ENOSYS;
+	}
 
+	new_hpage = get_new_page(hpage, private, &result);
 	if (!new_hpage)
 		return -ENOMEM;