mm/mmzone.c

   1 /*
   2  * linux/mm/mmzone.c
   3  *
   4  * management codes for pgdats, zones and page flags
   5  */
   6
   7
   8 #include <linux/stddef.h>
   9 #include <linux/mm.h>
  10 #include <linux/mmzone.h>
  11 #include <linux/export.h>
  12
  13 struct pglist_data *first_online_pgdat(void)
  14 {
  15         return NODE_DATA(first_online_node);
  16 }
  17 EXPORT_SYMBOL_GPL(first_online_pgdat);
  18
  19 struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
  20 {
  21         int nid = next_online_node(pgdat->node_id);
  22
  23         if (nid == MAX_NUMNODES)
  24                 return NULL;
  25         return NODE_DATA(nid);
  26 }
  27 EXPORT_SYMBOL_GPL(next_online_pgdat);
  28
  29 /*
  30  * next_zone - helper magic for for_each_zone()
  31  */
  32 struct zone *next_zone(struct zone *zone)
  33 {
  34         pg_data_t *pgdat = zone->zone_pgdat;
  35
  36         if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
  37                 zone++;
  38         else {
  39                 pgdat = next_online_pgdat(pgdat);
  40                 if (pgdat)
  41                         zone = pgdat->node_zones;
  42                 else
  43                         zone = NULL;
  44         }
  45         return zone;
  46 }
  47 EXPORT_SYMBOL_GPL(next_zone);
  48
  49 static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
  50 {
  51 #ifdef CONFIG_NUMA
  52         return node_isset(zonelist_node_idx(zref), *nodes);
  53 #else
  54         return 1;
  55 #endif /* CONFIG_NUMA */
  56 }
  57
  58 /* Returns the next zone at or below highest_zoneidx in a zonelist */
  59 struct zoneref *next_zones_zonelist(struct zoneref *z,
  60                                         enum zone_type highest_zoneidx,
  61                                         nodemask_t *nodes,
  62                                         struct zone **zone)
  63 {
  64         /*
  65          * Find the next suitable zone to use for the allocation.
  66          * Only filter based on nodemask if it's set
  67          */
  68         if (likely(nodes == NULL))
  69                 while (zonelist_zone_idx(z) > highest_zoneidx)
  70                         z++;
  71         else
  72                 while (zonelist_zone_idx(z) > highest_zoneidx ||
  73                                 (z->zone && !zref_in_nodemask(z, nodes)))
  74                         z++;
  75
  76         *zone = zonelist_zone(z);
  77         return z;
  78 }
  79
  80 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
  81 int memmap_valid_within(unsigned long pfn,
  82                                         struct page *page, struct zone *zone)
  83 {
  84         if (page_to_pfn(page) != pfn)
  85                 return 0;
  86
  87         if (page_zone(page) != zone)
  88                 return 0;
  89
  90         return 1;
  91 }
  92 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
  93
  94 void lruvec_init(struct lruvec *lruvec)
  95 {
  96         enum lru_list lru;
  97
  98         memset(lruvec, 0, sizeof(struct lruvec));
  99
 100         for_each_lru(lru)
 101                 INIT_LIST_HEAD(&lruvec->lists[lru]);
 102 }
 103
 104 #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_NID_NOT_IN_PAGE_FLAGS)
 105 int page_nid_xchg_last(struct page *page, int nid)
 106 {
 107         unsigned long old_flags, flags;
 108         int last_nid;
 109
 110         do {
 111                 old_flags = flags = page->flags;
 112                 last_nid = page_nid_last(page);
 113
 114                 flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT);
 115                 flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT;
 116         } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags));
 117
 118         return last_nid;
 119 }
 120 #endif