1 files changed, 17 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 7e3683fd4f3c..11673c5d2c20 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -434,7 +434,9 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
         /* pte contains position in swap or file, so copy. */
         if (unlikely(!pte_present(pte))) {
                 if (!pte_file(pte)) {
-                        swap_duplicate(pte_to_swp_entry(pte));
+                        swp_entry_t entry = pte_to_swp_entry(pte);
+
+                        swap_duplicate(entry);
                         /* make sure dst_mm is on swapoff's mmlist. */
                         if (unlikely(list_empty(&dst_mm->mmlist))) {
                                 spin_lock(&mmlist_lock);
@@ -443,6 +445,16 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                                                  &src_mm->mmlist);
                                 spin_unlock(&mmlist_lock);
                         }
+                        if (is_write_migration_entry(entry) &&
+                                        is_cow_mapping(vm_flags)) {
+                                /*
+                                 * COW mappings require pages in both parent
+                                 * and child to be set to read.
+                                 */
+                                make_migration_entry_read(&entry);
+                                pte = swp_entry_to_pte(entry);
+                                set_pte_at(src_mm, addr, src_pte, pte);
+                        }
                 }
                 goto out_set_pte;
         }
@@ -1879,6 +1891,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 goto out;
 
         entry = pte_to_swp_entry(orig_pte);
+        if (is_migration_entry(entry)) {
+                migration_entry_wait(mm, pmd, address);
+                goto out;
+        }
         page = lookup_swap_cache(entry);
         if (!page) {
                 swapin_readahead(entry, address, vma);