+#ifdef CONFIG_COMPACTION
+/* Returns true if the pageblock should be scanned for pages to isolate. */
+static inline bool isolation_suitable(struct compact_control *cc,
+ struct page *page)
+{
+ if (cc->ignore_skip_hint)
+ return true;
+
+ return !get_pageblock_skip(page);
+}
+
+/*
+ * This function is called to clear all cached information on pageblocks that
+ * should be skipped for page isolation when the migrate and free page scanner
+ * meet.
+ */
+static void __reset_isolation_suitable(struct zone *zone)
+{
+ unsigned long start_pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+ unsigned long pfn;
+
+ zone->compact_cached_migrate_pfn = start_pfn;
+ zone->compact_cached_free_pfn = end_pfn;
+ zone->compact_blockskip_flush = false;
+
+ /* Walk the zone and mark every pageblock as suitable for isolation */
+ for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+ struct page *page;
+
+ cond_resched();
+
+ if (!pfn_valid(pfn))
+ continue;
+
+ page = pfn_to_page(pfn);
+ if (zone != page_zone(page))
+ continue;
+
+ clear_pageblock_skip(page);
+ }
+}
+
+void reset_isolation_suitable(pg_data_t *pgdat)
+{
+ int zoneid;
+
+ for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+ struct zone *zone = &pgdat->node_zones[zoneid];
+ if (!populated_zone(zone))
+ continue;
+
+ /* Only flush if a full compaction finished recently */
+ if (zone->compact_blockskip_flush)
+ __reset_isolation_suitable(zone);
+ }
+}
+
+/*
+ * If no pages were isolated then mark this pageblock to be skipped in the
+ * future. The information is later cleared by __reset_isolation_suitable().
+ */
+static void update_pageblock_skip(struct compact_control *cc,
+ struct page *page, unsigned long nr_isolated,
+ bool migrate_scanner)
+{
+ struct zone *zone = cc->zone;
+ if (!page)
+ return;
+
+ if (!nr_isolated) {
+ unsigned long pfn = page_to_pfn(page);
+ set_pageblock_skip(page);
+
+ /* Update where compaction should restart */
+ if (migrate_scanner) {
+ if (!cc->finished_update_migrate &&
+ pfn > zone->compact_cached_migrate_pfn)
+ zone->compact_cached_migrate_pfn = pfn;
+ } else {
+ if (!cc->finished_update_free &&
+ pfn < zone->compact_cached_free_pfn)
+ zone->compact_cached_free_pfn = pfn;
+ }
+ }
+}
+#else
+static inline bool isolation_suitable(struct compact_control *cc,
+ struct page *page)
+{
+ return true;
+}
+
+static void update_pageblock_skip(struct compact_control *cc,
+ struct page *page, unsigned long nr_isolated,
+ bool migrate_scanner)
+{
+}
+#endif /* CONFIG_COMPACTION */
+
+static inline bool should_release_lock(spinlock_t *lock)
+{
+ return need_resched() || spin_is_contended(lock);
+}
+