6  * this heavily depends upon page migration to do all the real heavy
301 	 * is necessary for the block to be a migration source/target.  in __reset_isolation_pfn()
814 		/* async migration should just abort */  in isolate_migratepages_block()
831 	/* Time to isolate some pages for migration */  in isolate_migratepages_block()
836 			 * We have isolated all migration candidates in the  in isolate_migratepages_block()
996 		 * Migration will fail if an anonymous page is pinned in memory,  in isolate_migratepages_block()
1177 	 * scanning in the near future or migration failed in which case the  in isolate_migratepages_block()
1269 /* Returns true if the page is within a block suitable for migration to */
1273 	/* If the page is a large free page, then disallow migration */  in suitable_migration_target()
1287 	/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */  in suitable_migration_target()
1305  * the migration scanner, and compaction should thus terminate.
1314  * Used when scanning for a suitable migration target which scans freelists
1330  * Similar to move_freelist_head except used by the migration scanner
1591 	 * The low boundary is the end of the pageblock the migration scanner  in isolate_freepages()
1614 		 * suitable migration targets, so periodically check resched.  in isolate_freepages()
1624 		/* Check the block is suitable for migration */  in isolate_freepages()
1670 	 * call to isolate_freepages_block(), or we met the migration scanner  in isolate_freepages()
1755  * Briefly search the free lists for a migration source that already has
1756  * some free pages to reduce the number of pages that need migration
1799 	 * When starting the migration scanner, pick any pageblock within the  in fast_find_migrateblock()
1801 	 * within the first eighth to reduce the chances that a migration  in fast_find_migrateblock()
1958 		 * Either we isolated something and proceed with migration. Or  in isolate_migratepages()
2118 	 * migration source is unmovable/reclaimable but it's not worth  in __compact_finished()
2197 	 * isolate free pages for migration targets. This means that the  in __compaction_suitable()
2207 	 * suitable migration targets  in __compaction_suitable()
2365 	 * Migrate has separate cached PFNs for ASYNC and SYNC* migration on  in compact_zone()
2389 		 * migration. If it fails, it'll be marked skip and scanning  in compact_zone()
2454 		 * Has the migration scanner moved away from the previous  in compact_zone()
2587 	 * tricky context because the migration might require IO  in try_to_compact_pages()
2873 			 * We use sync migration mode here, so we defer like  in kcompactd_do_work()