mm/mmzone.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/mm/mmzone.c
   4  *
   5  * management codes for pgdats, zones and page flags
   6  */
   7
   8
   9 #include <linux/stddef.h>
  10 #include <linux/mm.h>
  11 #include <linux/mmzone.h>
  12
  13 struct pglist_data *first_online_pgdat(void)
  14 {
  15         return NODE_DATA(first_online_node);
  16 }
  17
  18 struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
  19 {
  20         int nid = next_online_node(pgdat->node_id);
  21
  22         if (nid == MAX_NUMNODES)
  23                 return NULL;
  24         return NODE_DATA(nid);
  25 }
  26
  27 /*
  28  * next_zone - helper magic for for_each_zone()
  29  */
  30 struct zone *next_zone(struct zone *zone)
  31 {
  32         pg_data_t *pgdat = zone->zone_pgdat;
  33
  34         if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
  35                 zone++;
  36         else {
  37                 pgdat = next_online_pgdat(pgdat);
  38                 if (pgdat)
  39                         zone = pgdat->node_zones;
  40                 else
  41                         zone = NULL;
  42         }
  43         return zone;
  44 }
  45
  46 static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
  47 {
  48 #ifdef CONFIG_NUMA
  49         return node_isset(zonelist_node_idx(zref), *nodes);
  50 #else
  51         return 1;
  52 #endif /* CONFIG_NUMA */
  53 }
  54
  55 /* Returns the next zone at or below highest_zoneidx in a zonelist */
  56 struct zoneref *__next_zones_zonelist(struct zoneref *z,
  57                                         enum zone_type highest_zoneidx,
  58                                         nodemask_t *nodes)
  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 (unlikely(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         return z;
  73 }
  74
  75 void lruvec_init(struct lruvec *lruvec)
  76 {
  77         enum lru_list lru;
  78
  79         memset(lruvec, 0, sizeof(struct lruvec));
  80         spin_lock_init(&lruvec->lru_lock);
  81
  82         for_each_lru(lru)
  83                 INIT_LIST_HEAD(&lruvec->lists[lru]);
  84         /*
  85          * The "Unevictable LRU" is imaginary: though its size is maintained,
  86          * it is never scanned, and unevictable pages are not threaded on it
  87          * (so that their lru fields can be reused to hold mlock_count).
  88          * Poison its list head, so that any operations on it would crash.
  89          */
  90         list_del(&lruvec->lists[LRU_UNEVICTABLE]);
  91
  92         lru_gen_init_lruvec(lruvec);
  93 }
  94
  95 #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
  96 int page_cpupid_xchg_last(struct page *page, int cpupid)
  97 {
  98         unsigned long old_flags, flags;
  99         int last_cpupid;
 100
 101         old_flags = READ_ONCE(page->flags);
 102         do {
 103                 flags = old_flags;
 104                 last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
 105
 106                 flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
 107                 flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
 108         } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags)));
 109
 110         return last_cpupid;
 111 }
 112 #endif