+int PageMovable(struct page *page)
+{
+ struct address_space *mapping;
+
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ if (!__PageMovable(page))
+ return 0;
+
+ mapping = page_mapping(page);
+ if (mapping && mapping->a_ops && mapping->a_ops->isolate_page)
+ return 1;
+
+ return 0;
+}
+EXPORT_SYMBOL(PageMovable);
+
+void __SetPageMovable(struct page *page, struct address_space *mapping)
+{
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE((unsigned long)mapping & PAGE_MAPPING_MOVABLE, page);
+ page->mapping = (void *)((unsigned long)mapping | PAGE_MAPPING_MOVABLE);
+}
+EXPORT_SYMBOL(__SetPageMovable);
+
+void __ClearPageMovable(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageMovable(page), page);
+ /*
+ * Clear registered address_space val with keeping PAGE_MAPPING_MOVABLE
+ * flag so that VM can catch up released page by driver after isolation.
+ * With it, VM migration doesn't try to put it back.
+ */
+ page->mapping = (void *)((unsigned long)page->mapping &
+ PAGE_MAPPING_MOVABLE);
+}
+EXPORT_SYMBOL(__ClearPageMovable);
+