6  * this heavily depends upon page migration to do all the real heavy
145 	 * With it, VM migration doesn't try to put it back.  in __ClearPageMovable()
307 	 * is necessary for the block to be a migration source/target.  in __reset_isolation_pfn()
615 		 * so it is correct to skip the suitable migration target  in isolate_freepages_block()
824 		/* async migration should just abort */  in isolate_migratepages_block()
841 	/* Time to isolate some pages for migration */  in isolate_migratepages_block()
846 			 * We have isolated all migration candidates in the  in isolate_migratepages_block()
959 		 * Migration will fail if an anonymous page is pinned in memory,  in isolate_migratepages_block()
1078 	 * scanning in the near future or migration failed in which case the  in isolate_migratepages_block()
1168 /* Returns true if the page is within a block suitable for migration to */
1172 	/* If the page is a large free page, then disallow migration */  in suitable_migration_target()
1186 	/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */  in suitable_migration_target()
1204  * the migration scanner, and compaction should thus terminate.
1213  * Used when scanning for a suitable migration target which scans freelists
1230  * Similar to move_freelist_head except used by the migration scanner
1484 	 * The low boundary is the end of the pageblock the migration scanner  in isolate_freepages()
1507 		 * suitable migration targets, so periodically check resched.  in isolate_freepages()
1517 		/* Check the block is suitable for migration */  in isolate_freepages()
1563 	 * call to isolate_freepages_block(), or we met the migration scanner  in isolate_freepages()
1652  * Briefly search the free lists for a migration source that already has
1653  * some free pages to reduce the number of pages that need migration
1695 	 * When starting the migration scanner, pick any pageblock within the  in fast_find_migrateblock()
1697 	 * within the first eighth to reduce the chances that a migration  in fast_find_migrateblock()
1859 		 * Either we isolated something and proceed with migration. Or  in isolate_migratepages()
1866 	/* Record where migration scanner will be restarted. */  in isolate_migratepages()
2002 	 * migration source is unmovable/reclaimable but it's not worth  in __compact_finished()
2101 	 * isolate free pages for migration targets. This means that the  in __compaction_suitable()
2111 	 * suitable migration targets  in __compaction_suitable()
2261 	 * Migrate has separate cached PFNs for ASYNC and SYNC* migration on  in compact_zone()
2285 		 * migration. If it fails, it'll be marked skip and scanning  in compact_zone()
2352 		 * Has the migration scanner moved away from the previous  in compact_zone()
2478 	 * tricky context because the migration might require IO  in try_to_compact_pages()
2742 			 * We use sync migration mode here, so we defer like  in kcompactd_do_work()