+/*
+ * Returns true if MIGRATE_UNMOVABLE pageblock was successfully
+ * converted to MIGRATE_MOVABLE type, false otherwise.
+ */
+static bool rescue_unmovable_pageblock(struct page *page)
+{
+ unsigned long pfn, start_pfn, end_pfn;
+ struct page *start_page, *end_page;
+
+ pfn = page_to_pfn(page);
+ start_pfn = pfn & ~(pageblock_nr_pages - 1);
+ end_pfn = start_pfn + pageblock_nr_pages;
+
+ start_page = pfn_to_page(start_pfn);
+ end_page = pfn_to_page(end_pfn);
+
+ /* Do not deal with pageblocks that overlap zones */
+ if (page_zone(start_page) != page_zone(end_page))
+ return false;
+
+ for (page = start_page, pfn = start_pfn; page < end_page; pfn++,
+ page++) {
+ if (!pfn_valid_within(pfn))
+ continue;
+
+ if (PageBuddy(page)) {
+ int order = page_order(page);
+
+ pfn += (1 << order) - 1;
+ page += (1 << order) - 1;
+
+ continue;
+ } else if (page_count(page) == 0 || PageLRU(page))
+ continue;
+
+ return false;
+ }
+
+ set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+ move_freepages_block(page_zone(page), page, MIGRATE_MOVABLE);
+ return true;
+}
+
+enum smt_result {
+ GOOD_AS_MIGRATION_TARGET,
+ FAIL_UNMOVABLE_TARGET,
+ FAIL_BAD_TARGET,
+};