1/*
  2 * linux/mm/mmzone.c
  3 *
  4 * management codes for pgdats and zones.
  5 */
  6
  7
  8#include <linux/stddef.h>
  9#include <linux/mm.h>
 10#include <linux/mmzone.h>
 11
 12struct pglist_data *first_online_pgdat(void)
 13{
 14	return NODE_DATA(first_online_node);
 15}
 16
 17struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
 18{
 19	int nid = next_online_node(pgdat->node_id);
 20
 21	if (nid == MAX_NUMNODES)
 22		return NULL;
 23	return NODE_DATA(nid);
 24}
 25
 26/*
 27 * next_zone - helper magic for for_each_zone()
 28 */
 29struct zone *next_zone(struct zone *zone)
 30{
 31	pg_data_t *pgdat = zone->zone_pgdat;
 32
 33	if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
 34		zone++;
 35	else {
 36		pgdat = next_online_pgdat(pgdat);
 37		if (pgdat)
 38			zone = pgdat->node_zones;
 39		else
 40			zone = NULL;
 41	}
 42	return zone;
 43}
 44
 45static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
 46{
 47#ifdef CONFIG_NUMA
 48	return node_isset(zonelist_node_idx(zref), *nodes);
 49#else
 50	return 1;
 51#endif /* CONFIG_NUMA */
 52}
 53
 54/* Returns the next zone at or below highest_zoneidx in a zonelist */
 55struct zoneref *next_zones_zonelist(struct zoneref *z,
 56					enum zone_type highest_zoneidx,
 57					nodemask_t *nodes,
 58					struct zone **zone)
 59{
 60	/*
 61	 * Find the next suitable zone to use for the allocation.
 62	 * Only filter based on nodemask if it's set
 63	 */
 64	if (likely(nodes == NULL))
 65		while (zonelist_zone_idx(z) > highest_zoneidx)
 66			z++;
 67	else
 68		while (zonelist_zone_idx(z) > highest_zoneidx ||
 69				(z->zone && !zref_in_nodemask(z, nodes)))
 70			z++;
 71
 72	*zone = zonelist_zone(z);
 73	return z;
 74}
 75
 76#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
 77int memmap_valid_within(unsigned long pfn,
 78					struct page *page, struct zone *zone)
 79{
 80	if (page_to_pfn(page) != pfn)
 81		return 0;
 82
 83	if (page_zone(page) != zone)
 84		return 0;
 85
 86	return 1;
 87}
 88#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
 89
 90void lruvec_init(struct lruvec *lruvec, struct zone *zone)
 91{
 92	enum lru_list lru;
 93
 94	memset(lruvec, 0, sizeof(struct lruvec));
 95
 96	for_each_lru(lru)
 97		INIT_LIST_HEAD(&lruvec->lists[lru]);
 98
 99#ifdef CONFIG_CGROUP_MEM_RES_CTLR
100	lruvec->zone = zone;
101#endif
102}