hugetlbfs: add swap entry check in follow_hugetlb_page()

[pandora-kernel.git] / mm / hugetlb.c

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ca9a7c6..1a12f5b 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2961,7 +2961,17 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        break;
                }
 
-               if (absent ||
+               /*
+                * We need call hugetlb_fault for both hugepages under migration
+                * (in which case hugetlb_fault waits for the migration,) and
+                * hwpoisoned hugepages (in which case we need to prevent the
+                * caller from accessing to them.) In order to do this, we use
+                * here is_swap_pte instead of is_hugetlb_entry_migration and
+                * is_hugetlb_entry_hwpoisoned. This is because it simply covers
+                * both cases, and because we can't follow correct pages
+                * directly from any kind of swap entries.
+                */
+               if (absent || is_swap_pte(huge_ptep_get(pte)) ||
                    ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
                        int ret;