201  * Folios that were pinned via memfd_pin_folios() or other similar routines
440  * unpin_folios() - release an array of gup-pinned folios.
441  * @folios:  array of folios to be marked dirty and released.
442  * @nfolios: number of folios in the @folios array.
444  * For each folio in the @folios array, release the folio using gup_put_folio.
448 void unpin_folios(struct folio **folios, unsigned long nfolios)  in unpin_folios()  argument
453 	 * If this WARN_ON() fires, then the system *might* be leaking folios  in unpin_folios()
463 			if (folios[i] != folios[j])  in unpin_folios()
466 		if (folios[i])  in unpin_folios()
467 			gup_put_folio(folios[i], j - i, FOLL_PIN);  in unpin_folios()
516  *    FOLL_PIN on large folios: folio's refcount will be incremented by
519  *    FOLL_PIN on single-page folios: folio's refcount will be incremented by
2221  * An array of either pages or folios ("pofs"). Although it may seem tempting to
2222  * avoid this complication, by simply interpreting a list of folios as a list of
2230 		struct folio **folios;  member
2240 		return pofs->folios[i];  in pofs_get_folio()
2252 		unpin_folios(pofs->folios, pofs->nr_entries);  in pofs_unpin()
2283  * Returns the number of collected folios. Return value is always >= 0.
2328  * Unpins all folios and migrates device coherent folios and movable_folio_list.
2329  * Returns -EAGAIN if all folios were successfully migrated or -errno for
2361 		 * We can't migrate folios with unexpected references, so drop  in migrate_longterm_unpinnable_folios()
2363 		 * Migrating folios have been added to movable_folio_list after  in migrate_longterm_unpinnable_folios()
2412  * Check whether all folios are *allowed* to be pinned indefinitely (long term).
2413  * Rather confusingly, all folios in the range are required to be pinned via
2418  * 0: if everything is OK and all folios in the range are allowed to be pinned,
2419  * then this routine leaves all folios pinned and returns zero for success.
2421  * -EAGAIN: if any folios in the range are not allowed to be pinned, then this
2422  * routine will migrate those folios away, unpin all the folios in the range. If
2423  * migration of the entire set of folios succeeds, then -EAGAIN is returned. The
2429  * error back up the call stack. The caller does not need to unpin any folios in
2433 					     struct folio **folios)  in check_and_migrate_movable_folios()  argument
2436 		.folios = folios,  in check_and_migrate_movable_folios()
2467 					     struct folio **folios)  in check_and_migrate_movable_folios()  argument
2739  * GUP-fast must reject all secretmem folios.
2741  * Writing to pinned file-backed dirty tracked folios is inherently problematic
2767 	/* secretmem folios are always order-0 folios. */  in gup_fast_folio_allowed()
2806 	/* Anonymous folios pose no problem. */  in gup_fast_folio_allowed()
3434  * memfd_pin_folios() - pin folios associated with a memfd
3435  * @memfd:      the memfd whose folios are to be pinned
3438  * @folios:     array that receives pointers to the folios pinned
3439  * @max_folios: maximum number of entries in @folios
3442  * Attempt to pin folios associated with a memfd in the contiguous range
3444  * the folios can either be found in the page cache or need to be allocated
3445  * if necessary. Once the folios are located, they are all pinned via
3447  * And, eventually, these pinned folios must be released either using
3450  * It must be noted that the folios may be pinned for an indefinite amount
3455  * Returns number of folios pinned, which could be less than @max_folios
3457  * If no folios were pinned, it returns -errno.
3460 		      struct folio **folios, unsigned int max_folios,  in memfd_pin_folios()  argument
3501 			 * In most cases, we should be able to find the folios  in memfd_pin_folios()
3516 				folio = fbatch.folios[i];  in memfd_pin_folios()
3527 				folios[nr_folios] = folio;  in memfd_pin_folios()
3545 		ret = check_and_migrate_movable_folios(nr_folios, folios);  in memfd_pin_folios()
3552 	unpin_folios(folios, nr_folios);  in memfd_pin_folios()