+/*
+ * Note that remove_file_migration_ptes will only work on regular mappings,
+ * Nonlinear mappings do not use migration entries.
+ */
+static void remove_file_migration_ptes(struct page *old, struct page *new)
+{
+ struct vm_area_struct *vma;
+ struct address_space *mapping = page_mapping(new);
+ struct prio_tree_iter iter;
+ pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+
+ if (!mapping)
+ return;
+
+ spin_lock(&mapping->i_mmap_lock);
+
+ vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
+ remove_migration_pte(vma, old, new);
+
+ spin_unlock(&mapping->i_mmap_lock);
+}
+
+/*
+ * Must hold mmap_sem lock on at least one of the vmas containing
+ * the page so that the anon_vma cannot vanish.
+ */
+static void remove_anon_migration_ptes(struct page *old, struct page *new)
+{
+ struct anon_vma *anon_vma;
+ struct vm_area_struct *vma;
+ unsigned long mapping;
+
+ mapping = (unsigned long)new->mapping;
+
+ if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
+ return;
+
+ /*
+ * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
+ */
+ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
+ spin_lock(&anon_vma->lock);
+
+ list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
+ remove_migration_pte(vma, old, new);
+
+ spin_unlock(&anon_vma->lock);
+}
+
+/*
+ * Get rid of all migration entries and replace them by
+ * references to the indicated page.
+ */
+static void remove_migration_ptes(struct page *old, struct page *new)
+{
+ if (PageAnon(new))
+ remove_anon_migration_ptes(old, new);
+ else
+ remove_file_migration_ptes(old, new);
+}
+
+/*
+ * Something used the pte of a page under migration. We need to
+ * get to the page and wait until migration is finished.
+ * When we return from this function the fault will be retried.
+ *
+ * This function is called from do_swap_page().
+ */
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address)
+{
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ swp_entry_t entry;
+ struct page *page;
+
+ ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+ pte = *ptep;
+ if (!is_swap_pte(pte))
+ goto out;
+
+ entry = pte_to_swp_entry(pte);
+ if (!is_migration_entry(entry))
+ goto out;
+
+ page = migration_entry_to_page(entry);
+
+ get_page(page);
+ pte_unmap_unlock(ptep, ptl);
+ wait_on_page_locked(page);
+ put_page(page);
+ return;
+out:
+ pte_unmap_unlock(ptep, ptl);