/*
   * 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, 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,

  					nodemask_t *nodes)

  {
  	/*
  	 * Find the next suitable zone to use for the allocation.
  	 * Only filter based on nodemask if it's set
  	 */
  	if (likely(nodes == NULL))
  		while (zonelist_zone_idx(z) > highest_zoneidx)
  			z++;
  	else
  		while (zonelist_zone_idx(z) > highest_zoneidx ||
  				(z->zone && !zref_in_nodemask(z, nodes)))
  			z++;

  	return z;
  }

  
  #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL

  bool memmap_valid_within(unsigned long pfn,

  					struct page *page, struct zone *zone)
  {
  	if (page_to_pfn(page) != pfn)

  		return false;

  
  	if (page_zone(page) != zone)

  		return false;

  	return true;

  }
  #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */

  void lruvec_init(struct lruvec *lruvec)

  {
  	enum lru_list lru;
  
  	memset(lruvec, 0, sizeof(struct lruvec));
  
  	for_each_lru(lru)
  		INIT_LIST_HEAD(&lruvec->lists[lru]);

  }

  #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
  int page_cpupid_xchg_last(struct page *page, int cpupid)

  {
  	unsigned long old_flags, flags;

  	int last_cpupid;

  
  	do {
  		old_flags = flags = page->flags;

  		last_cpupid = page_cpupid_last(page);

  		flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
  		flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;

  	} while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags));

  	return last_cpupid;

  }
  #endif