1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 51a90b7f2d60..e988037abd2a 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -1,6 +1,8 @@
 #ifndef _LINUX_COMPACTION_H
 #define _LINUX_COMPACTION_H
 
+#include <linux/node.h>
+
 /* Return values for compact_zone() and try_to_compact_pages() */
 /* compaction didn't start as it was not possible or direct reclaim was more suitable */
 #define COMPACT_SKIPPED         0
@@ -11,6 +13,23 @@
 /* The full zone was compacted */
 #define COMPACT_COMPLETE        3
 
+/*
+ * compaction supports three modes
+ *
+ * COMPACT_ASYNC_MOVABLE uses asynchronous migration and only scans
+ *    MIGRATE_MOVABLE pageblocks as migration sources and targets.
+ * COMPACT_ASYNC_UNMOVABLE uses asynchronous migration and only scans
+ *    MIGRATE_MOVABLE pageblocks as migration sources.
+ *    MIGRATE_UNMOVABLE pageblocks are scanned as potential migration
+ *    targets and convers them to MIGRATE_MOVABLE if possible
+ * COMPACT_SYNC uses synchronous migration and scans all pageblocks
+ */
+enum compact_mode {
+        COMPACT_ASYNC_MOVABLE,
+        COMPACT_ASYNC_UNMOVABLE,
+        COMPACT_SYNC,
+};
+
 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,