[PATCH AUTOSEL 3.18 85/98] mm: migrate: hugetlb: putback destination hugepage to active list

[Sasha Levin]

From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>

[ Upstream commit 3aaa76e125c1dd58c9b599baa8c6021896874c12 ]

Since commit bcc54222309c ("mm: hugetlb: introduce page_huge_active")
each hugetlb page maintains its active flag to avoid a race condition
betwe= en multiple calls of isolate_huge_page(), but current kernel
doesn't set the f= lag on a hugepage allocated by migration because the
proper putback routine isn= 't called.  This means that users could
still encounter the race referred to by bcc54222309c in this special
case, so this patch fixes it.

Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active")
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>  [4.1.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 4d743bce5a23..57559f9295f9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1077,7 +1077,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	if (rc != MIGRATEPAGE_SUCCESS && put_new_page)
 		put_new_page(new_hpage, private);
 	else
-		put_page(new_hpage);
+		putback_active_hugepage(new_hpage);
 
 	if (result) {
 		if (rc)
-- 
2.17.1