include/linux/mmzone.h

   1 #ifndef _LINUX_MMZONE_H
   2 #define _LINUX_MMZONE_H
   3
   4 #ifdef __KERNEL__
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/config.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/list.h>
  10 #include <linux/wait.h>
  11 #include <linux/cache.h>
  12 #include <linux/threads.h>
  13 #include <linux/numa.h>
  14 #include <linux/init.h>
  15 #include <linux/seqlock.h>
  16 #include <asm/atomic.h>
  17
  18 /* Free memory management - zoned buddy allocator.  */
  19 #ifndef CONFIG_FORCE_MAX_ZONEORDER
  20 #define MAX_ORDER 11
  21 #else
  22 #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
  23 #endif
  24
  25 struct free_area {
  26         struct list_head        free_list;
  27         unsigned long           nr_free;
  28 };
  29
  30 struct pglist_data;
  31
  32 /*
  33  * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
  34  * So add a wild amount of padding here to ensure that they fall into separate
  35  * cachelines.  There are very few zone structures in the machine, so space
  36  * consumption is not a concern here.
  37  */
  38 #if defined(CONFIG_SMP)
  39 struct zone_padding {
  40         char x[0];
  41 } ____cacheline_maxaligned_in_smp;
  42 #define ZONE_PADDING(name)      struct zone_padding name;
  43 #else
  44 #define ZONE_PADDING(name)
  45 #endif
  46
  47 struct per_cpu_pages {
  48         int count;              /* number of pages in the list */
  49         int low;                /* low watermark, refill needed */
  50         int high;               /* high watermark, emptying needed */
  51         int batch;              /* chunk size for buddy add/remove */
  52         struct list_head list;  /* the list of pages */
  53 };
  54
  55 struct per_cpu_pageset {
  56         struct per_cpu_pages pcp[2];    /* 0: hot.  1: cold */
  57 #ifdef CONFIG_NUMA
  58         unsigned long numa_hit;         /* allocated in intended node */
  59         unsigned long numa_miss;        /* allocated in non intended node */
  60         unsigned long numa_foreign;     /* was intended here, hit elsewhere */
  61         unsigned long interleave_hit;   /* interleaver prefered this zone */
  62         unsigned long local_node;       /* allocation from local node */
  63         unsigned long other_node;       /* allocation from other node */
  64 #endif
  65 } ____cacheline_aligned_in_smp;
  66
  67 #ifdef CONFIG_NUMA
  68 #define zone_pcp(__z, __cpu) ((__z)->pageset[(__cpu)])
  69 #else
  70 #define zone_pcp(__z, __cpu) (&(__z)->pageset[(__cpu)])
  71 #endif
  72
  73 #define ZONE_DMA                0
  74 #define ZONE_DMA32              1
  75 #define ZONE_NORMAL             2
  76 #define ZONE_HIGHMEM            3
  77
  78 #define MAX_NR_ZONES            4       /* Sync this with ZONES_SHIFT */
  79 #define ZONES_SHIFT             2       /* ceil(log2(MAX_NR_ZONES)) */
  80
  81
  82 /*
  83  * When a memory allocation must conform to specific limitations (such
  84  * as being suitable for DMA) the caller will pass in hints to the
  85  * allocator in the gfp_mask, in the zone modifier bits.  These bits
  86  * are used to select a priority ordered list of memory zones which
  87  * match the requested limits.  GFP_ZONEMASK defines which bits within
  88  * the gfp_mask should be considered as zone modifiers.  Each valid
  89  * combination of the zone modifier bits has a corresponding list
  90  * of zones (in node_zonelists).  Thus for two zone modifiers there
  91  * will be a maximum of 4 (2 ** 2) zonelists, for 3 modifiers there will
  92  * be 8 (2 ** 3) zonelists.  GFP_ZONETYPES defines the number of possible
  93  * combinations of zone modifiers in "zone modifier space".
  94  *
  95  * NOTE! Make sure this matches the zones in <linux/gfp.h>
  96  */
  97 #define GFP_ZONEMASK    0x07
  98 #define GFP_ZONETYPES   5
  99
 100 /*
 101  * On machines where it is needed (eg PCs) we divide physical memory
 102  * into multiple physical zones. On a PC we have 4 zones:
 103  *
 104  * ZONE_DMA       < 16 MB       ISA DMA capable memory
 105  * ZONE_DMA32        0 MB       Empty
 106  * ZONE_NORMAL  16-896 MB       direct mapped by the kernel
 107  * ZONE_HIGHMEM  > 896 MB       only page cache and user processes
 108  */
 109
 110 struct zone {
 111         /* Fields commonly accessed by the page allocator */
 112         unsigned long           free_pages;
 113         unsigned long           pages_min, pages_low, pages_high;
 114         /*
 115          * We don't know if the memory that we're going to allocate will be freeable
 116          * or/and it will be released eventually, so to avoid totally wasting several
 117          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
 118          * to run OOM on the lower zones despite there's tons of freeable ram
 119          * on the higher zones). This array is recalculated at runtime if the
 120          * sysctl_lowmem_reserve_ratio sysctl changes.
 121          */
 122         unsigned long           lowmem_reserve[MAX_NR_ZONES];
 123
 124 #ifdef CONFIG_NUMA
 125         struct per_cpu_pageset  *pageset[NR_CPUS];
 126 #else
 127         struct per_cpu_pageset  pageset[NR_CPUS];
 128 #endif
 129         /*
 130          * free areas of different sizes
 131          */
 132         spinlock_t              lock;
 133 #ifdef CONFIG_MEMORY_HOTPLUG
 134         /* see spanned/present_pages for more description */
 135         seqlock_t               span_seqlock;
 136 #endif
 137         struct free_area        free_area[MAX_ORDER];
 138
 139
 140         ZONE_PADDING(_pad1_)
 141
 142         /* Fields commonly accessed by the page reclaim scanner */
 143         spinlock_t              lru_lock;
 144         struct list_head        active_list;
 145         struct list_head        inactive_list;
 146         unsigned long           nr_scan_active;
 147         unsigned long           nr_scan_inactive;
 148         unsigned long           nr_active;
 149         unsigned long           nr_inactive;
 150         unsigned long           pages_scanned;     /* since last reclaim */
 151         int                     all_unreclaimable; /* All pages pinned */
 152
 153         /*
 154          * Does the allocator try to reclaim pages from the zone as soon
 155          * as it fails a watermark_ok() in __alloc_pages?
 156          */
 157         int                     reclaim_pages;
 158         /* A count of how many reclaimers are scanning this zone */
 159         atomic_t                reclaim_in_progress;
 160
 161         /*
 162          * prev_priority holds the scanning priority for this zone.  It is
 163          * defined as the scanning priority at which we achieved our reclaim
 164          * target at the previous try_to_free_pages() or balance_pgdat()
 165          * invokation.
 166          *
 167          * We use prev_priority as a measure of how much stress page reclaim is
 168          * under - it drives the swappiness decision: whether to unmap mapped
 169          * pages.
 170          *
 171          * temp_priority is used to remember the scanning priority at which
 172          * this zone was successfully refilled to free_pages == pages_high.
 173          *
 174          * Access to both these fields is quite racy even on uniprocessor.  But
 175          * it is expected to average out OK.
 176          */
 177         int temp_priority;
 178         int prev_priority;
 179
 180
 181         ZONE_PADDING(_pad2_)
 182         /* Rarely used or read-mostly fields */
 183
 184         /*
 185          * wait_table           -- the array holding the hash table
 186          * wait_table_size      -- the size of the hash table array
 187          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
 188          *
 189          * The purpose of all these is to keep track of the people
 190          * waiting for a page to become available and make them
 191          * runnable again when possible. The trouble is that this
 192          * consumes a lot of space, especially when so few things
 193          * wait on pages at a given time. So instead of using
 194          * per-page waitqueues, we use a waitqueue hash table.
 195          *
 196          * The bucket discipline is to sleep on the same queue when
 197          * colliding and wake all in that wait queue when removing.
 198          * When something wakes, it must check to be sure its page is
 199          * truly available, a la thundering herd. The cost of a
 200          * collision is great, but given the expected load of the
 201          * table, they should be so rare as to be outweighed by the
 202          * benefits from the saved space.
 203          *
 204          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
 205          * primary users of these fields, and in mm/page_alloc.c
 206          * free_area_init_core() performs the initialization of them.
 207          */
 208         wait_queue_head_t       * wait_table;
 209         unsigned long           wait_table_size;
 210         unsigned long           wait_table_bits;
 211
 212         /*
 213          * Discontig memory support fields.
 214          */
 215         struct pglist_data      *zone_pgdat;
 216         struct page             *zone_mem_map;
 217         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
 218         unsigned long           zone_start_pfn;
 219
 220         /*
 221          * zone_start_pfn, spanned_pages and present_pages are all
 222          * protected by span_seqlock.  It is a seqlock because it has
 223          * to be read outside of zone->lock, and it is done in the main
 224          * allocator path.  But, it is written quite infrequently.
 225          *
 226          * The lock is declared along with zone->lock because it is
 227          * frequently read in proximity to zone->lock.  It's good to
 228          * give them a chance of being in the same cacheline.
 229          */
 230         unsigned long           spanned_pages;  /* total size, including holes */
 231         unsigned long           present_pages;  /* amount of memory (excluding holes) */
 232
 233         /*
 234          * rarely used fields:
 235          */
 236         char                    *name;
 237 } ____cacheline_maxaligned_in_smp;
 238
 239
 240 /*
 241  * The "priority" of VM scanning is how much of the queues we will scan in one
 242  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
 243  * queues ("queue_length >> 12") during an aging round.
 244  */
 245 #define DEF_PRIORITY 12
 246
 247 /*
 248  * One allocation request operates on a zonelist. A zonelist
 249  * is a list of zones, the first one is the 'goal' of the
 250  * allocation, the other zones are fallback zones, in decreasing
 251  * priority.
 252  *
 253  * Right now a zonelist takes up less than a cacheline. We never
 254  * modify it apart from boot-up, and only a few indices are used,
 255  * so despite the zonelist table being relatively big, the cache
 256  * footprint of this construct is very small.
 257  */
 258 struct zonelist {
 259         struct zone *zones[MAX_NUMNODES * MAX_NR_ZONES + 1]; // NULL delimited
 260 };
 261
 262
 263 /*
 264  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
 265  * (mostly NUMA machines?) to denote a higher-level memory zone than the
 266  * zone denotes.
 267  *
 268  * On NUMA machines, each NUMA node would have a pg_data_t to describe
 269  * it's memory layout.
 270  *
 271  * Memory statistics and page replacement data structures are maintained on a
 272  * per-zone basis.
 273  */
 274 struct bootmem_data;
 275 typedef struct pglist_data {
 276         struct zone node_zones[MAX_NR_ZONES];
 277         struct zonelist node_zonelists[GFP_ZONETYPES];
 278         int nr_zones;
 279 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 280         struct page *node_mem_map;
 281 #endif
 282         struct bootmem_data *bdata;
 283 #ifdef CONFIG_MEMORY_HOTPLUG
 284         /*
 285          * Must be held any time you expect node_start_pfn, node_present_pages
 286          * or node_spanned_pages stay constant.  Holding this will also
 287          * guarantee that any pfn_valid() stays that way.
 288          *
 289          * Nests above zone->lock and zone->size_seqlock.
 290          */
 291         spinlock_t node_size_lock;
 292 #endif
 293         unsigned long node_start_pfn;
 294         unsigned long node_present_pages; /* total number of physical pages */
 295         unsigned long node_spanned_pages; /* total size of physical page
 296                                              range, including holes */
 297         int node_id;
 298         struct pglist_data *pgdat_next;
 299         wait_queue_head_t kswapd_wait;
 300         struct task_struct *kswapd;
 301         int kswapd_max_order;
 302 } pg_data_t;
 303
 304 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
 305 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
 306 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 307 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
 308 #else
 309 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
 310 #endif
 311 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
 312
 313 #include <linux/memory_hotplug.h>
 314
 315 extern struct pglist_data *pgdat_list;
 316
 317 void __get_zone_counts(unsigned long *active, unsigned long *inactive,
 318                         unsigned long *free, struct pglist_data *pgdat);
 319 void get_zone_counts(unsigned long *active, unsigned long *inactive,
 320                         unsigned long *free);
 321 void build_all_zonelists(void);
 322 void wakeup_kswapd(struct zone *zone, int order);
 323 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 324                 int classzone_idx, int alloc_flags);
 325
 326 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 327 void memory_present(int nid, unsigned long start, unsigned long end);
 328 #else
 329 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
 330 #endif
 331
 332 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
 333 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 334 #endif
 335
 336 /*
 337  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
 338  */
 339 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
 340
 341 /**
 342  * for_each_pgdat - helper macro to iterate over all nodes
 343  * @pgdat - pointer to a pg_data_t variable
 344  *
 345  * Meant to help with common loops of the form
 346  * pgdat = pgdat_list;
 347  * while(pgdat) {
 348  *      ...
 349  *      pgdat = pgdat->pgdat_next;
 350  * }
 351  */
 352 #define for_each_pgdat(pgdat) \
 353         for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
 354
 355 /*
 356  * next_zone - helper magic for for_each_zone()
 357  * Thanks to William Lee Irwin III for this piece of ingenuity.
 358  */
 359 static inline struct zone *next_zone(struct zone *zone)
 360 {
 361         pg_data_t *pgdat = zone->zone_pgdat;
 362
 363         if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
 364                 zone++;
 365         else if (pgdat->pgdat_next) {
 366                 pgdat = pgdat->pgdat_next;
 367                 zone = pgdat->node_zones;
 368         } else
 369                 zone = NULL;
 370
 371         return zone;
 372 }
 373
 374 /**
 375  * for_each_zone - helper macro to iterate over all memory zones
 376  * @zone - pointer to struct zone variable
 377  *
 378  * The user only needs to declare the zone variable, for_each_zone
 379  * fills it in. This basically means for_each_zone() is an
 380  * easier to read version of this piece of code:
 381  *
 382  * for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
 383  *      for (i = 0; i < MAX_NR_ZONES; ++i) {
 384  *              struct zone * z = pgdat->node_zones + i;
 385  *              ...
 386  *      }
 387  * }
 388  */
 389 #define for_each_zone(zone) \
 390         for (zone = pgdat_list->node_zones; zone; zone = next_zone(zone))
 391
 392 static inline int is_highmem_idx(int idx)
 393 {
 394         return (idx == ZONE_HIGHMEM);
 395 }
 396
 397 static inline int is_normal_idx(int idx)
 398 {
 399         return (idx == ZONE_NORMAL);
 400 }
 401 /**
 402  * is_highmem - helper function to quickly check if a struct zone is a
 403  *              highmem zone or not.  This is an attempt to keep references
 404  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
 405  * @zone - pointer to struct zone variable
 406  */
 407 static inline int is_highmem(struct zone *zone)
 408 {
 409         return zone == zone->zone_pgdat->node_zones + ZONE_HIGHMEM;
 410 }
 411
 412 static inline int is_normal(struct zone *zone)
 413 {
 414         return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
 415 }
 416
 417 /* These two functions are used to setup the per zone pages min values */
 418 struct ctl_table;
 419 struct file;
 420 int min_free_kbytes_sysctl_handler(struct ctl_table *, int, struct file *,
 421                                         void __user *, size_t *, loff_t *);
 422 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 423 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, struct file *,
 424                                         void __user *, size_t *, loff_t *);
 425
 426 #include <linux/topology.h>
 427 /* Returns the number of the current Node. */
 428 #ifndef numa_node_id
 429 #define numa_node_id()          (cpu_to_node(raw_smp_processor_id()))
 430 #endif
 431
 432 #ifndef CONFIG_NEED_MULTIPLE_NODES
 433
 434 extern struct pglist_data contig_page_data;
 435 #define NODE_DATA(nid)          (&contig_page_data)
 436 #define NODE_MEM_MAP(nid)       mem_map
 437 #define MAX_NODES_SHIFT         1
 438 #define pfn_to_nid(pfn)         (0)
 439
 440 #else /* CONFIG_NEED_MULTIPLE_NODES */
 441
 442 #include <asm/mmzone.h>
 443
 444 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
 445
 446 #ifdef CONFIG_SPARSEMEM
 447 #include <asm/sparsemem.h>
 448 #endif
 449
 450 #if BITS_PER_LONG == 32
 451 /*
 452  * with 32 bit page->flags field, we reserve 9 bits for node/zone info.
 453  * there are 4 zones (3 bits) and this leaves 9-3=6 bits for nodes.
 454  */
 455 #define FLAGS_RESERVED          9
 456
 457 #elif BITS_PER_LONG == 64
 458 /*
 459  * with 64 bit flags field, there's plenty of room.
 460  */
 461 #define FLAGS_RESERVED          32
 462
 463 #else
 464
 465 #error BITS_PER_LONG not defined
 466
 467 #endif
 468
 469 #ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
 470 #define early_pfn_to_nid(nid)  (0UL)
 471 #endif
 472
 473 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
 474 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
 475
 476 #ifdef CONFIG_SPARSEMEM
 477
 478 /*
 479  * SECTION_SHIFT                #bits space required to store a section #
 480  *
 481  * PA_SECTION_SHIFT             physical address to/from section number
 482  * PFN_SECTION_SHIFT            pfn to/from section number
 483  */
 484 #define SECTIONS_SHIFT          (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
 485
 486 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
 487 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
 488
 489 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
 490
 491 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
 492 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
 493
 494 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
 495 #error Allocator MAX_ORDER exceeds SECTION_SIZE
 496 #endif
 497
 498 struct page;
 499 struct mem_section {
 500         /*
 501          * This is, logically, a pointer to an array of struct
 502          * pages.  However, it is stored with some other magic.
 503          * (see sparse.c::sparse_init_one_section())
 504          *
 505          * Making it a UL at least makes someone do a cast
 506          * before using it wrong.
 507          */
 508         unsigned long section_mem_map;
 509 };
 510
 511 #ifdef CONFIG_SPARSEMEM_EXTREME
 512 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
 513 #else
 514 #define SECTIONS_PER_ROOT       1
 515 #endif
 516
 517 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
 518 #define NR_SECTION_ROOTS        (NR_MEM_SECTIONS / SECTIONS_PER_ROOT)
 519 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
 520
 521 #ifdef CONFIG_SPARSEMEM_EXTREME
 522 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
 523 #else
 524 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
 525 #endif
 526
 527 static inline struct mem_section *__nr_to_section(unsigned long nr)
 528 {
 529         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
 530                 return NULL;
 531         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
 532 }
 533 extern int __section_nr(struct mem_section* ms);
 534
 535 /*
 536  * We use the lower bits of the mem_map pointer to store
 537  * a little bit of information.  There should be at least
 538  * 3 bits here due to 32-bit alignment.
 539  */
 540 #define SECTION_MARKED_PRESENT  (1UL<<0)
 541 #define SECTION_HAS_MEM_MAP     (1UL<<1)
 542 #define SECTION_MAP_LAST_BIT    (1UL<<2)
 543 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
 544
 545 static inline struct page *__section_mem_map_addr(struct mem_section *section)
 546 {
 547         unsigned long map = section->section_mem_map;
 548         map &= SECTION_MAP_MASK;
 549         return (struct page *)map;
 550 }
 551
 552 static inline int valid_section(struct mem_section *section)
 553 {
 554         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
 555 }
 556
 557 static inline int section_has_mem_map(struct mem_section *section)
 558 {
 559         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
 560 }
 561
 562 static inline int valid_section_nr(unsigned long nr)
 563 {
 564         return valid_section(__nr_to_section(nr));
 565 }
 566
 567 /*
 568  * Given a kernel address, find the home node of the underlying memory.
 569  */
 570 #define kvaddr_to_nid(kaddr)    pfn_to_nid(__pa(kaddr) >> PAGE_SHIFT)
 571
 572 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
 573 {
 574         return __nr_to_section(pfn_to_section_nr(pfn));
 575 }
 576
 577 #define pfn_to_page(pfn)                                                \
 578 ({                                                                      \
 579         unsigned long __pfn = (pfn);                                    \
 580         __section_mem_map_addr(__pfn_to_section(__pfn)) + __pfn;        \
 581 })
 582 #define page_to_pfn(page)                                               \
 583 ({                                                                      \
 584         page - __section_mem_map_addr(__nr_to_section(                  \
 585                 page_to_section(page)));                                \
 586 })
 587
 588 static inline int pfn_valid(unsigned long pfn)
 589 {
 590         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
 591                 return 0;
 592         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
 593 }
 594
 595 /*
 596  * These are _only_ used during initialisation, therefore they
 597  * can use __initdata ...  They could have names to indicate
 598  * this restriction.
 599  */
 600 #ifdef CONFIG_NUMA
 601 #define pfn_to_nid              early_pfn_to_nid
 602 #endif
 603
 604 #define pfn_to_pgdat(pfn)                                               \
 605 ({                                                                      \
 606         NODE_DATA(pfn_to_nid(pfn));                                     \
 607 })
 608
 609 #define early_pfn_valid(pfn)    pfn_valid(pfn)
 610 void sparse_init(void);
 611 #else
 612 #define sparse_init()   do {} while (0)
 613 #define sparse_index_init(_sec, _nid)  do {} while (0)
 614 #endif /* CONFIG_SPARSEMEM */
 615
 616 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
 617 #define early_pfn_in_nid(pfn, nid)      (early_pfn_to_nid(pfn) == (nid))
 618 #else
 619 #define early_pfn_in_nid(pfn, nid)      (1)
 620 #endif
 621
 622 #ifndef early_pfn_valid
 623 #define early_pfn_valid(pfn)    (1)
 624 #endif
 625
 626 void memory_present(int nid, unsigned long start, unsigned long end);
 627 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 628
 629 #endif /* !__ASSEMBLY__ */
 630 #endif /* __KERNEL__ */
 631 #endif /* _LINUX_MMZONE_H */