+err:
+ for (i = 0; i < nr_pages; i++)
+ if (pages[i])
+ unpin_user_page(pages[i]);
+ putback_movable_pages(movable_page_list);
+
+ return ret;
+}
+
+/*
+ * Check whether all pages are *allowed* to be pinned. Rather confusingly, all
+ * pages in the range are required to be pinned via FOLL_PIN, before calling
+ * this routine.
+ *
+ * If any pages in the range are not allowed to be pinned, then this routine
+ * will migrate those pages away, unpin all the pages in the range and return
+ * -EAGAIN. The caller should re-pin the entire range with FOLL_PIN and then
+ * call this routine again.
+ *
+ * If an error other than -EAGAIN occurs, this indicates a migration failure.
+ * The caller should give up, and propagate the error back up the call stack.
+ *
+ * If everything is OK and all pages in the range are allowed to be pinned, then
+ * this routine leaves all pages pinned and returns zero for success.
+ */
+static long check_and_migrate_movable_pages(unsigned long nr_pages,
+ struct page **pages)
+{
+ unsigned long collected;
+ LIST_HEAD(movable_page_list);
+
+ collected = collect_longterm_unpinnable_pages(&movable_page_list,
+ nr_pages, pages);
+ if (!collected)
+ return 0;
+
+ return migrate_longterm_unpinnable_pages(&movable_page_list, nr_pages,
+ pages);