116 	 * TODO: these pages will not be folios in the future. All  in isolate_movable_ops_page()
196 	 * TODO: these pages will not be folios in the future. All  in putback_movable_ops_page()
229  * TODO: migration core will treat both pages as folios and lock them before
232  * folios in the future, so that must be reworked.
559  * 1 for anonymous folios without a mapping
560  * 2 for folios with a mapping
561  * 3 for folios with a mapping and the private flag set.
653 	 * Note that anonymous folios are accounted for  in __folio_migrate_mapping()
874  * folios that do not have private data.
876  * Folios are locked upon entry and exit.
992  * buffer_migrate_folio() - Migration function for folios with buffers.
1014  * buffer_migrate_folio_norefs() - Migration function for folios with buffers.
1067  * The src and dst folios are locked and the src folios was unmapped from
1091 		 * Most folios have a mapping and most filesystems  in move_to_new_folio()
1092 		 * provide a migrate_folio callback. Anonymous folios  in move_to_new_folio()
1104 		 * For pagecache folios, src->mapping must be cleared before src  in move_to_new_folio()
1105 		 * is freed. Anonymous folios must stay anonymous until freed.  in move_to_new_folio()
1591 	int nr_succeeded;	/* Normal and large folios migrated successfully, in
1593 	int nr_failed_pages;	/* Normal and large folios failed to be migrated, in
1594 				   units of base pages.  Untried folios aren't counted */
1602  * Returns the number of hugetlb folios that were not migrated, or an error code
1603  * after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no hugetlb folios are movable
1604  * any more because the list has become empty or no retryable hugetlb folios
1662 				 * other folios, just exit.  in migrate_hugetlbs()
1687 	 * nr_failed is number of hugetlb folios failed to be migrated.  After  in migrate_hugetlbs()
1689 	 * folios as failed.  in migrate_hugetlbs()
1773  * migrate_pages_batch() first unmaps folios in the from list as many as
1774  * possible, then move the unmapped folios.
1834 			 * page cache folios. They exist, in contrast to  in migrate_pages_batch()
1835 			 * non-existent order-1 anonymous folios, and do not  in migrate_pages_batch()
1854 			 * to normal folios.  in migrate_pages_batch()
1856 			 * Split folios are put in split_folios, and  in migrate_pages_batch()
1889 				 * other folios, move unmapped folios, then exit.  in migrate_pages_batch()
1956 	/* Flush TLBs for all unmapped folios */  in migrate_pages_batch()
1965 		/* Move the unmapped folios */  in migrate_pages_batch()
1977 	/* Cleanup remaining folios */  in migrate_pages_batch()
1991 	LIST_HEAD(folios);  in migrate_pages_sync()
1997 				 reason, &folios, split_folios, &astats,  in migrate_pages_sync()
2006 		list_splice_tail(&folios, ret_folios);  in migrate_pages_sync()
2016 	 * Fall back to migrate all failed folios one by one synchronously. All  in migrate_pages_sync()
2017 	 * failed folios except split THPs will be retried, so their failure  in migrate_pages_sync()
2020 	list_splice_tail_init(&folios, from);  in migrate_pages_sync()
2022 		list_move(from->next, &folios);  in migrate_pages_sync()
2023 		rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,  in migrate_pages_sync()
2026 		list_splice_tail_init(&folios, ret_folios);  in migrate_pages_sync()
2036  * migrate_pages - migrate the folios specified in a list, to the free folios
2039  * @from:		The list of folios to be migrated.
2040  * @get_new_folio:	The function used to allocate free folios to be used
2042  * @put_new_folio:	The function used to free target folios if migration
2048  * @ret_succeeded:	Set to the number of folios migrated successfully if
2051  * The function returns after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no folios
2052  * are movable any more because the list has become empty or no retryable folios
2059  * split folios of the large folio are migrated successfully.
2068 	LIST_HEAD(folios);  in migrate_pages()
2085 		/* Retried hugetlb folios will be kept in list  */  in migrate_pages()
2096 		list_cut_before(&folios, from, &folio2->lru);  in migrate_pages()
2098 		list_splice_init(from, &folios);  in migrate_pages()
2100 		rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,  in migrate_pages()
2105 		rc = migrate_pages_sync(&folios, get_new_folio, put_new_folio,  in migrate_pages()
2108 	list_splice_tail_init(&folios, &ret_folios);  in migrate_pages()
2116 		 * Failure isn't counted since all split folios of a large folio  in migrate_pages()
2136 	 * Return 0 in case all split folios of fail-to-migrate large folios  in migrate_pages()
2654 		 * Do not migrate file folios that are mapped in multiple  in migrate_misplaced_folio_prepare()
2665 		 * Do not migrate dirty folios as not all filesystems can move  in migrate_misplaced_folio_prepare()
2666 		 * dirty folios in MIGRATE_ASYNC mode which is a waste of  in migrate_misplaced_folio_prepare()