+ /*
+ * After page migration succeeds, the source page can
+ * be trapped in pagevec and actual freeing is delayed.
+ * Freeing code works differently based on PG_hwpoison,
+ * so there's a race. We need to make sure that the
+ * source page should be freed back to buddy before
+ * setting PG_hwpoison.
+ */
+ if (!is_free_buddy_page(page))
+ lru_add_drain_all();
+ if (!is_free_buddy_page(page))
+ drain_all_pages();