// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Swap reorganised 29.12.95, Stephen Tweedie.
 *  kswapd added: 7.1.96  sct
 *  Removed kswapd_ctl limits, and swap out as many pages as needed
 *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.
 *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
 *  Multiqueue VM started 5.8.00, Rik van Riel.
 */

/* Extracted unchanged from Linux v6.0, mm/vmscan.c:2280-2315.
 * Complete function definition; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.0/mm/vmscan.c#L2280
 * License text: GPL-2.0.txt (in this directory).
 */
static int too_many_isolated(struct pglist_data *pgdat, int file,
		struct scan_control *sc)
{
	unsigned long inactive, isolated;
	bool too_many;

	if (current_is_kswapd())
		return 0;

	if (!writeback_throttling_sane(sc))
		return 0;

	if (file) {
		inactive = node_page_state(pgdat, NR_INACTIVE_FILE);
		isolated = node_page_state(pgdat, NR_ISOLATED_FILE);
	} else {
		inactive = node_page_state(pgdat, NR_INACTIVE_ANON);
		isolated = node_page_state(pgdat, NR_ISOLATED_ANON);
	}

	/*
	 * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
	 * won't get blocked by normal direct-reclaimers, forming a circular
	 * deadlock.
	 */
	if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
		inactive >>= 3;

	too_many = isolated > inactive;

	/* Wake up tasks throttled due to too_many_isolated. */
	if (!too_many)
		wake_throttle_isolated(pgdat);

	return too_many;
}