[PATCH 3/3] mm/hugetlb: add FOLL_MIGRATION validation before waiting for a migration entry

[Baolin Wang]

The hugetlb should keep the same logics with normal page when waiting
for a migration pte entry, that means we should also validate if
the FOLL_MIGRATION flag is set before waiting for a migration pte entry
of a hugetlb page.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 mm/hugetlb.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index efb53ba..fac1b33 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -7000,6 +7000,11 @@ struct page * __weak
 			goto out;
 		}
 	} else {
+		if (!(flags & FOLL_MIGRATION)) {
+			page = NULL;
+			goto out;
+		}
+
 		if (is_hugetlb_entry_migration(pte)) {
 			spin_unlock(ptl);
 			__migration_entry_wait_huge((pte_t *)pmd, ptl);
@@ -7038,6 +7043,11 @@ struct page * __weak
 			goto out;
 		}
 	} else {
+		if (!(flags & FOLL_MIGRATION)) {
+			page = NULL;
+			goto out;
+		}
+
 		if (is_hugetlb_entry_migration(pte)) {
 			spin_unlock(ptl);
 			__migration_entry_wait(mm, (pte_t *)pud, ptl);
-- 
1.8.3.1