// 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 v6.1, mm/swap.c:977-1056.
 * Full function definition; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.1/mm/swap.c#L977
 * License text: GPL-2.0.txt (in this directory).
 */
void release_pages(struct page **pages, int nr)
{
	int i;
	LIST_HEAD(pages_to_free);
	struct lruvec *lruvec = NULL;
	unsigned long flags = 0;
	unsigned int lock_batch;

	for (i = 0; i < nr; i++) {
		struct folio *folio = page_folio(pages[i]);

		/*
		 * Make sure the IRQ-safe lock-holding time does not get
		 * excessive with a continuous string of pages from the
		 * same lruvec. The lock is held only if lruvec != NULL.
		 */
		if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
			unlock_page_lruvec_irqrestore(lruvec, flags);
			lruvec = NULL;
		}

		if (is_huge_zero_page(&folio->page))
			continue;

		if (folio_is_zone_device(folio)) {
			if (lruvec) {
				unlock_page_lruvec_irqrestore(lruvec, flags);
				lruvec = NULL;
			}
			if (put_devmap_managed_page(&folio->page))
				continue;
			if (folio_put_testzero(folio))
				free_zone_device_page(&folio->page);
			continue;
		}

		if (!folio_put_testzero(folio))
			continue;

		if (folio_test_large(folio)) {
			if (lruvec) {
				unlock_page_lruvec_irqrestore(lruvec, flags);
				lruvec = NULL;
			}
			__folio_put_large(folio);
			continue;
		}

		if (folio_test_lru(folio)) {
			struct lruvec *prev_lruvec = lruvec;

			lruvec = folio_lruvec_relock_irqsave(folio, lruvec,
									&flags);
			if (prev_lruvec != lruvec)
				lock_batch = 0;

			lruvec_del_folio(lruvec, folio);
			__folio_clear_lru_flags(folio);
		}

		/*
		 * In rare cases, when truncation or holepunching raced with
		 * munlock after VM_LOCKED was cleared, Mlocked may still be
		 * found set here.  This does not indicate a problem, unless
		 * "unevictable_pgs_cleared" appears worryingly large.
		 */
		if (unlikely(folio_test_mlocked(folio))) {
			__folio_clear_mlocked(folio);
			zone_stat_sub_folio(folio, NR_MLOCK);
			count_vm_event(UNEVICTABLE_PGCLEARED);
		}

		list_add(&folio->lru, &pages_to_free);
	}
	if (lruvec)
		unlock_page_lruvec_irqrestore(lruvec, flags);

	mem_cgroup_uncharge_list(&pages_to_free);
	free_unref_page_list(&pages_to_free);
}