// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/mm/swap.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * This file contains the default values for the operation of the
 * Linux VM subsystem. Fine-tuning documentation can be found in
 * Documentation/admin-guide/sysctl/vm.rst.
 * Started 18.12.91
 * Swap aging added 23.2.95, Stephen Tweedie.
 * Buffermem limits added 12.3.98, Rik van Riel.
 */

/* Extracted unchanged from Linux v6.18, mm/swap.c:455-488.
 * Complete named function; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.18/mm/swap.c#L455-L488
 * License text: GPL-2.0.txt (in this directory).
 */
void folio_mark_accessed(struct folio *folio)
{
	if (folio_test_dropbehind(folio))
		return;
	if (lru_gen_enabled()) {
		lru_gen_inc_refs(folio);
		return;
	}

	if (!folio_test_referenced(folio)) {
		folio_set_referenced(folio);
	} else if (folio_test_unevictable(folio)) {
		/*
		 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
		 * this list is never rotated or maintained, so marking an
		 * unevictable page accessed has no effect.
		 */
	} else if (!folio_test_active(folio)) {
		/*
		 * If the folio is on the LRU, queue it for activation via
		 * cpu_fbatches.lru_activate. Otherwise, assume the folio is in a
		 * folio_batch, mark it active and it'll be moved to the active
		 * LRU on the next drain.
		 */
		if (folio_test_lru(folio))
			folio_activate(folio);
		else
			__lru_cache_activate_folio(folio);
		folio_clear_referenced(folio);
		workingset_activation(folio);
	}
	if (folio_test_idle(folio))
		folio_clear_idle(folio);
}