// SPDX-License-Identifier: GPL-2.0/* * linux/mm/mmzone.c * * management codes for pgdats, zones and page flags */  #include <linux/stddef.h>#include <linux/mm.h>#include <linux/mmzone.h> struct pglist_data *first_online_pgdat(void){	return NODE_DATA(first_online_node);} struct pglist_data *next_online_pgdat(struct pglist_data *pgdat){	int nid = next_online_node(pgdat->node_id); 	if (nid == MAX_NUMNODES)		return NULL;	return NODE_DATA(nid);} /* * next_zone - helper magic for for_each_zone() */struct zone *next_zone(struct zone *zone){	pg_data_t *pgdat = zone->zone_pgdat; 	if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)		zone++;	else {		pgdat = next_online_pgdat(pgdat);		if (pgdat)			zone = pgdat->node_zones;		else			zone = NULL;	}	return zone;} static inline int zref_in_nodemask(struct zoneref *zref,				   const nodemask_t *nodes){#ifdef CONFIG_NUMA	return node_isset(zonelist_node_idx(zref), *nodes);#else	return 1;#endif /* CONFIG_NUMA */} /* Returns the next zone at or below highest_zoneidx in a zonelist */struct zoneref *__next_zones_zonelist(struct zoneref *z,					enum zone_type highest_zoneidx,					const nodemask_t *nodes){	/*	 * Find the next suitable zone to use for the allocation.	 * Only filter based on nodemask if it's set	 */	if (unlikely(nodes == NULL))		while (zonelist_zone_idx(z) > highest_zoneidx)			z++;	else		while (zonelist_zone_idx(z) > highest_zoneidx ||				(zonelist_zone(z) && !zref_in_nodemask(z, nodes)))			z++; 	return z;} void lruvec_init(struct lruvec *lruvec){	enum lru_list lru; 	memset(lruvec, 0, sizeof(struct lruvec));	spin_lock_init(&lruvec->lru_lock);	spin_lock_init(&lruvec->cost_lock);	zswap_lruvec_state_init(lruvec); 	for_each_lru(lru)		INIT_LIST_HEAD(&lruvec->lists[lru]);	/*	 * The "Unevictable LRU" is imaginary: though its size is maintained,	 * it is never scanned, and unevictable pages are not threaded on it	 * (so that their lru fields can be reused to hold mlock_count).	 * Poison its list head, so that any operations on it would crash.	 */	list_del(&lruvec->lists[LRU_UNEVICTABLE]); 	lru_gen_init_lruvec(lruvec);} #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)int folio_xchg_last_cpupid(struct folio *folio, int cpupid){	unsigned long old_flags, flags;	int last_cpupid; 	old_flags = READ_ONCE(folio->flags.f);	do {		flags = old_flags;		last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK; 		flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);		flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;	} while (unlikely(!try_cmpxchg(&folio->flags.f, &old_flags, flags))); 	return last_cpupid;}#endif