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/spinlock.h>
   8 #include <linux/list.h>
   9 #include <linux/wait.h>
  10 #include <linux/cache.h>
  11 #include <linux/threads.h>
  12 #include <linux/numa.h>
  13 #include <linux/init.h>
  14 #include <linux/seqlock.h>
  15 #include <linux/nodemask.h>
  16 #include <asm/atomic.h>
  17 #include <asm/page.h>
  18
  19 /* Free memory management - zoned buddy allocator.  */
  20 #ifndef CONFIG_FORCE_MAX_ZONEORDER
  21 #define MAX_ORDER 11
  22 #else
  23 #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
  24 #endif
  25 #define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1))
  26
  27 struct free_area {
  28         struct list_head        free_list;
  29         unsigned long           nr_free;
  30 };
  31
  32 struct pglist_data;
  33
  34 /*
  35  * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
  36  * So add a wild amount of padding here to ensure that they fall into separate
  37  * cachelines.  There are very few zone structures in the machine, so space
  38  * consumption is not a concern here.
  39  */
  40 #if defined(CONFIG_SMP)
  41 struct zone_padding {
  42         char x[0];
  43 } ____cacheline_internodealigned_in_smp;
  44 #define ZONE_PADDING(name)      struct zone_padding name;
  45 #else
  46 #define ZONE_PADDING(name)
  47 #endif
  48
  49 enum zone_stat_item {
  50         NR_ANON_PAGES,  /* Mapped anonymous pages */
  51         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
  52                            only modified from process context */
  53         NR_FILE_PAGES,
  54         NR_SLAB_RECLAIMABLE,
  55         NR_SLAB_UNRECLAIMABLE,
  56         NR_PAGETABLE,   /* used for pagetables */
  57         NR_FILE_DIRTY,
  58         NR_WRITEBACK,
  59         NR_UNSTABLE_NFS,        /* NFS unstable pages */
  60         NR_BOUNCE,
  61         NR_VMSCAN_WRITE,
  62 #ifdef CONFIG_NUMA
  63         NUMA_HIT,               /* allocated in intended node */
  64         NUMA_MISS,              /* allocated in non intended node */
  65         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
  66         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
  67         NUMA_LOCAL,             /* allocation from local node */
  68         NUMA_OTHER,             /* allocation from other node */
  69 #endif
  70         NR_VM_ZONE_STAT_ITEMS };
  71
  72 struct per_cpu_pages {
  73         int count;              /* number of pages in the list */
  74         int high;               /* high watermark, emptying needed */
  75         int batch;              /* chunk size for buddy add/remove */
  76         struct list_head list;  /* the list of pages */
  77 };
  78
  79 struct per_cpu_pageset {
  80         struct per_cpu_pages pcp[2];    /* 0: hot.  1: cold */
  81 #ifdef CONFIG_SMP
  82         s8 stat_threshold;
  83         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
  84 #endif
  85 } ____cacheline_aligned_in_smp;
  86
  87 #ifdef CONFIG_NUMA
  88 #define zone_pcp(__z, __cpu) ((__z)->pageset[(__cpu)])
  89 #else
  90 #define zone_pcp(__z, __cpu) (&(__z)->pageset[(__cpu)])
  91 #endif
  92
  93 enum zone_type {
  94         /*
  95          * ZONE_DMA is used when there are devices that are not able
  96          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
  97          * carve out the portion of memory that is needed for these devices.
  98          * The range is arch specific.
  99          *
 100          * Some examples
 101          *
 102          * Architecture         Limit
 103          * ---------------------------
 104          * parisc, ia64, sparc  <4G
 105          * s390                 <2G
 106          * arm26                <48M
 107          * arm                  Various
 108          * alpha                Unlimited or 0-16MB.
 109          *
 110          * i386, x86_64 and multiple other arches
 111          *                      <16M.
 112          */
 113         ZONE_DMA,
 114 #ifdef CONFIG_ZONE_DMA32
 115         /*
 116          * x86_64 needs two ZONE_DMAs because it supports devices that are
 117          * only able to do DMA to the lower 16M but also 32 bit devices that
 118          * can only do DMA areas below 4G.
 119          */
 120         ZONE_DMA32,
 121 #endif
 122         /*
 123          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
 124          * performed on pages in ZONE_NORMAL if the DMA devices support
 125          * transfers to all addressable memory.
 126          */
 127         ZONE_NORMAL,
 128 #ifdef CONFIG_HIGHMEM
 129         /*
 130          * A memory area that is only addressable by the kernel through
 131          * mapping portions into its own address space. This is for example
 132          * used by i386 to allow the kernel to address the memory beyond
 133          * 900MB. The kernel will set up special mappings (page
 134          * table entries on i386) for each page that the kernel needs to
 135          * access.
 136          */
 137         ZONE_HIGHMEM,
 138 #endif
 139         MAX_NR_ZONES
 140 };
 141
 142 /*
 143  * When a memory allocation must conform to specific limitations (such
 144  * as being suitable for DMA) the caller will pass in hints to the
 145  * allocator in the gfp_mask, in the zone modifier bits.  These bits
 146  * are used to select a priority ordered list of memory zones which
 147  * match the requested limits. See gfp_zone() in include/linux/gfp.h
 148  */
 149
 150 #if !defined(CONFIG_ZONE_DMA32) && !defined(CONFIG_HIGHMEM)
 151 #define ZONES_SHIFT 1
 152 #else
 153 #define ZONES_SHIFT 2
 154 #endif
 155
 156 struct zone {
 157         /* Fields commonly accessed by the page allocator */
 158         unsigned long           free_pages;
 159         unsigned long           pages_min, pages_low, pages_high;
 160         /*
 161          * We don't know if the memory that we're going to allocate will be freeable
 162          * or/and it will be released eventually, so to avoid totally wasting several
 163          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
 164          * to run OOM on the lower zones despite there's tons of freeable ram
 165          * on the higher zones). This array is recalculated at runtime if the
 166          * sysctl_lowmem_reserve_ratio sysctl changes.
 167          */
 168         unsigned long           lowmem_reserve[MAX_NR_ZONES];
 169
 170 #ifdef CONFIG_NUMA
 171         int node;
 172         /*
 173          * zone reclaim becomes active if more unmapped pages exist.
 174          */
 175         unsigned long           min_unmapped_pages;
 176         unsigned long           min_slab_pages;
 177         struct per_cpu_pageset  *pageset[NR_CPUS];
 178 #else
 179         struct per_cpu_pageset  pageset[NR_CPUS];
 180 #endif
 181         /*
 182          * free areas of different sizes
 183          */
 184         spinlock_t              lock;
 185 #ifdef CONFIG_MEMORY_HOTPLUG
 186         /* see spanned/present_pages for more description */
 187         seqlock_t               span_seqlock;
 188 #endif
 189         struct free_area        free_area[MAX_ORDER];
 190
 191
 192         ZONE_PADDING(_pad1_)
 193
 194         /* Fields commonly accessed by the page reclaim scanner */
 195         spinlock_t              lru_lock;
 196         struct list_head        active_list;
 197         struct list_head        inactive_list;
 198         unsigned long           nr_scan_active;
 199         unsigned long           nr_scan_inactive;
 200         unsigned long           nr_active;
 201         unsigned long           nr_inactive;
 202         unsigned long           pages_scanned;     /* since last reclaim */
 203         int                     all_unreclaimable; /* All pages pinned */
 204
 205         /* A count of how many reclaimers are scanning this zone */
 206         atomic_t                reclaim_in_progress;
 207
 208         /* Zone statistics */
 209         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
 210
 211         /*
 212          * prev_priority holds the scanning priority for this zone.  It is
 213          * defined as the scanning priority at which we achieved our reclaim
 214          * target at the previous try_to_free_pages() or balance_pgdat()
 215          * invokation.
 216          *
 217          * We use prev_priority as a measure of how much stress page reclaim is
 218          * under - it drives the swappiness decision: whether to unmap mapped
 219          * pages.
 220          *
 221          * Access to both this field is quite racy even on uniprocessor.  But
 222          * it is expected to average out OK.
 223          */
 224         int prev_priority;
 225
 226
 227         ZONE_PADDING(_pad2_)
 228         /* Rarely used or read-mostly fields */
 229
 230         /*
 231          * wait_table           -- the array holding the hash table
 232          * wait_table_hash_nr_entries   -- the size of the hash table array
 233          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
 234          *
 235          * The purpose of all these is to keep track of the people
 236          * waiting for a page to become available and make them
 237          * runnable again when possible. The trouble is that this
 238          * consumes a lot of space, especially when so few things
 239          * wait on pages at a given time. So instead of using
 240          * per-page waitqueues, we use a waitqueue hash table.
 241          *
 242          * The bucket discipline is to sleep on the same queue when
 243          * colliding and wake all in that wait queue when removing.
 244          * When something wakes, it must check to be sure its page is
 245          * truly available, a la thundering herd. The cost of a
 246          * collision is great, but given the expected load of the
 247          * table, they should be so rare as to be outweighed by the
 248          * benefits from the saved space.
 249          *
 250          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
 251          * primary users of these fields, and in mm/page_alloc.c
 252          * free_area_init_core() performs the initialization of them.
 253          */
 254         wait_queue_head_t       * wait_table;
 255         unsigned long           wait_table_hash_nr_entries;
 256         unsigned long           wait_table_bits;
 257
 258         /*
 259          * Discontig memory support fields.
 260          */
 261         struct pglist_data      *zone_pgdat;
 262         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
 263         unsigned long           zone_start_pfn;
 264
 265         /*
 266          * zone_start_pfn, spanned_pages and present_pages are all
 267          * protected by span_seqlock.  It is a seqlock because it has
 268          * to be read outside of zone->lock, and it is done in the main
 269          * allocator path.  But, it is written quite infrequently.
 270          *
 271          * The lock is declared along with zone->lock because it is
 272          * frequently read in proximity to zone->lock.  It's good to
 273          * give them a chance of being in the same cacheline.
 274          */
 275         unsigned long           spanned_pages;  /* total size, including holes */
 276         unsigned long           present_pages;  /* amount of memory (excluding holes) */
 277
 278         /*
 279          * rarely used fields:
 280          */
 281         char                    *name;
 282 } ____cacheline_internodealigned_in_smp;
 283
 284 /*
 285  * The "priority" of VM scanning is how much of the queues we will scan in one
 286  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
 287  * queues ("queue_length >> 12") during an aging round.
 288  */
 289 #define DEF_PRIORITY 12
 290
 291 /*
 292  * One allocation request operates on a zonelist. A zonelist
 293  * is a list of zones, the first one is the 'goal' of the
 294  * allocation, the other zones are fallback zones, in decreasing
 295  * priority.
 296  *
 297  * Right now a zonelist takes up less than a cacheline. We never
 298  * modify it apart from boot-up, and only a few indices are used,
 299  * so despite the zonelist table being relatively big, the cache
 300  * footprint of this construct is very small.
 301  */
 302 struct zonelist {
 303         struct zone *zones[MAX_NUMNODES * MAX_NR_ZONES + 1]; // NULL delimited
 304 };
 305
 306 #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
 307 struct node_active_region {
 308         unsigned long start_pfn;
 309         unsigned long end_pfn;
 310         int nid;
 311 };
 312 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
 313
 314 #ifndef CONFIG_DISCONTIGMEM
 315 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
 316 extern struct page *mem_map;
 317 #endif
 318
 319 /*
 320  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
 321  * (mostly NUMA machines?) to denote a higher-level memory zone than the
 322  * zone denotes.
 323  *
 324  * On NUMA machines, each NUMA node would have a pg_data_t to describe
 325  * it's memory layout.
 326  *
 327  * Memory statistics and page replacement data structures are maintained on a
 328  * per-zone basis.
 329  */
 330 struct bootmem_data;
 331 typedef struct pglist_data {
 332         struct zone node_zones[MAX_NR_ZONES];
 333         struct zonelist node_zonelists[MAX_NR_ZONES];
 334         int nr_zones;
 335 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 336         struct page *node_mem_map;
 337 #endif
 338         struct bootmem_data *bdata;
 339 #ifdef CONFIG_MEMORY_HOTPLUG
 340         /*
 341          * Must be held any time you expect node_start_pfn, node_present_pages
 342          * or node_spanned_pages stay constant.  Holding this will also
 343          * guarantee that any pfn_valid() stays that way.
 344          *
 345          * Nests above zone->lock and zone->size_seqlock.
 346          */
 347         spinlock_t node_size_lock;
 348 #endif
 349         unsigned long node_start_pfn;
 350         unsigned long node_present_pages; /* total number of physical pages */
 351         unsigned long node_spanned_pages; /* total size of physical page
 352                                              range, including holes */
 353         int node_id;
 354         wait_queue_head_t kswapd_wait;
 355         struct task_struct *kswapd;
 356         int kswapd_max_order;
 357 } pg_data_t;
 358
 359 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
 360 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
 361 #ifdef CONFIG_FLAT_NODE_MEM_MAP
 362 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
 363 #else
 364 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
 365 #endif
 366 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
 367
 368 #include <linux/memory_hotplug.h>
 369
 370 void __get_zone_counts(unsigned long *active, unsigned long *inactive,
 371                         unsigned long *free, struct pglist_data *pgdat);
 372 void get_zone_counts(unsigned long *active, unsigned long *inactive,
 373                         unsigned long *free);
 374 void build_all_zonelists(void);
 375 void wakeup_kswapd(struct zone *zone, int order);
 376 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 377                 int classzone_idx, int alloc_flags);
 378
 379 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
 380                                      unsigned long size);
 381
 382 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 383 void memory_present(int nid, unsigned long start, unsigned long end);
 384 #else
 385 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
 386 #endif
 387
 388 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
 389 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 390 #endif
 391
 392 /*
 393  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
 394  */
 395 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
 396
 397 static inline int populated_zone(struct zone *zone)
 398 {
 399         return (!!zone->present_pages);
 400 }
 401
 402 static inline int is_highmem_idx(enum zone_type idx)
 403 {
 404 #ifdef CONFIG_HIGHMEM
 405         return (idx == ZONE_HIGHMEM);
 406 #else
 407         return 0;
 408 #endif
 409 }
 410
 411 static inline int is_normal_idx(enum zone_type idx)
 412 {
 413         return (idx == ZONE_NORMAL);
 414 }
 415
 416 /**
 417  * is_highmem - helper function to quickly check if a struct zone is a
 418  *              highmem zone or not.  This is an attempt to keep references
 419  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
 420  * @zone - pointer to struct zone variable
 421  */
 422 static inline int is_highmem(struct zone *zone)
 423 {
 424 #ifdef CONFIG_HIGHMEM
 425         return zone == zone->zone_pgdat->node_zones + ZONE_HIGHMEM;
 426 #else
 427         return 0;
 428 #endif
 429 }
 430
 431 static inline int is_normal(struct zone *zone)
 432 {
 433         return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
 434 }
 435
 436 static inline int is_dma32(struct zone *zone)
 437 {
 438 #ifdef CONFIG_ZONE_DMA32
 439         return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
 440 #else
 441         return 0;
 442 #endif
 443 }
 444
 445 static inline int is_dma(struct zone *zone)
 446 {
 447         return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
 448 }
 449
 450 /* These two functions are used to setup the per zone pages min values */
 451 struct ctl_table;
 452 struct file;
 453 int min_free_kbytes_sysctl_handler(struct ctl_table *, int, struct file *,
 454                                         void __user *, size_t *, loff_t *);
 455 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 456 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, struct file *,
 457                                         void __user *, size_t *, loff_t *);
 458 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int, struct file *,
 459                                         void __user *, size_t *, loff_t *);
 460 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
 461                         struct file *, void __user *, size_t *, loff_t *);
 462 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
 463                         struct file *, void __user *, size_t *, loff_t *);
 464
 465 #include <linux/topology.h>
 466 /* Returns the number of the current Node. */
 467 #ifndef numa_node_id
 468 #define numa_node_id()          (cpu_to_node(raw_smp_processor_id()))
 469 #endif
 470
 471 #ifndef CONFIG_NEED_MULTIPLE_NODES
 472
 473 extern struct pglist_data contig_page_data;
 474 #define NODE_DATA(nid)          (&contig_page_data)
 475 #define NODE_MEM_MAP(nid)       mem_map
 476 #define MAX_NODES_SHIFT         1
 477
 478 #else /* CONFIG_NEED_MULTIPLE_NODES */
 479
 480 #include <asm/mmzone.h>
 481
 482 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
 483
 484 extern struct pglist_data *first_online_pgdat(void);
 485 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
 486 extern struct zone *next_zone(struct zone *zone);
 487
 488 /**
 489  * for_each_pgdat - helper macro to iterate over all nodes
 490  * @pgdat - pointer to a pg_data_t variable
 491  */
 492 #define for_each_online_pgdat(pgdat)                    \
 493         for (pgdat = first_online_pgdat();              \
 494              pgdat;                                     \
 495              pgdat = next_online_pgdat(pgdat))
 496 /**
 497  * for_each_zone - helper macro to iterate over all memory zones
 498  * @zone - pointer to struct zone variable
 499  *
 500  * The user only needs to declare the zone variable, for_each_zone
 501  * fills it in.
 502  */
 503 #define for_each_zone(zone)                             \
 504         for (zone = (first_online_pgdat())->node_zones; \
 505              zone;                                      \
 506              zone = next_zone(zone))
 507
 508 #ifdef CONFIG_SPARSEMEM
 509 #include <asm/sparsemem.h>
 510 #endif
 511
 512 #if BITS_PER_LONG == 32
 513 /*
 514  * with 32 bit page->flags field, we reserve 9 bits for node/zone info.
 515  * there are 4 zones (3 bits) and this leaves 9-3=6 bits for nodes.
 516  */
 517 #define FLAGS_RESERVED          9
 518
 519 #elif BITS_PER_LONG == 64
 520 /*
 521  * with 64 bit flags field, there's plenty of room.
 522  */
 523 #define FLAGS_RESERVED          32
 524
 525 #else
 526
 527 #error BITS_PER_LONG not defined
 528
 529 #endif
 530
 531 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
 532         !defined(CONFIG_ARCH_POPULATES_NODE_MAP)
 533 #define early_pfn_to_nid(nid)  (0UL)
 534 #endif
 535
 536 #ifdef CONFIG_FLATMEM
 537 #define pfn_to_nid(pfn)         (0)
 538 #endif
 539
 540 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
 541 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
 542
 543 #ifdef CONFIG_SPARSEMEM
 544
 545 /*
 546  * SECTION_SHIFT                #bits space required to store a section #
 547  *
 548  * PA_SECTION_SHIFT             physical address to/from section number
 549  * PFN_SECTION_SHIFT            pfn to/from section number
 550  */
 551 #define SECTIONS_SHIFT          (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
 552
 553 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
 554 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
 555
 556 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
 557
 558 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
 559 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
 560
 561 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
 562 #error Allocator MAX_ORDER exceeds SECTION_SIZE
 563 #endif
 564
 565 struct page;
 566 struct mem_section {
 567         /*
 568          * This is, logically, a pointer to an array of struct
 569          * pages.  However, it is stored with some other magic.
 570          * (see sparse.c::sparse_init_one_section())
 571          *
 572          * Additionally during early boot we encode node id of
 573          * the location of the section here to guide allocation.
 574          * (see sparse.c::memory_present())
 575          *
 576          * Making it a UL at least makes someone do a cast
 577          * before using it wrong.
 578          */
 579         unsigned long section_mem_map;
 580 };
 581
 582 #ifdef CONFIG_SPARSEMEM_EXTREME
 583 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
 584 #else
 585 #define SECTIONS_PER_ROOT       1
 586 #endif
 587
 588 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
 589 #define NR_SECTION_ROOTS        (NR_MEM_SECTIONS / SECTIONS_PER_ROOT)
 590 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
 591
 592 #ifdef CONFIG_SPARSEMEM_EXTREME
 593 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
 594 #else
 595 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
 596 #endif
 597
 598 static inline struct mem_section *__nr_to_section(unsigned long nr)
 599 {
 600         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
 601                 return NULL;
 602         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
 603 }
 604 extern int __section_nr(struct mem_section* ms);
 605
 606 /*
 607  * We use the lower bits of the mem_map pointer to store
 608  * a little bit of information.  There should be at least
 609  * 3 bits here due to 32-bit alignment.
 610  */
 611 #define SECTION_MARKED_PRESENT  (1UL<<0)
 612 #define SECTION_HAS_MEM_MAP     (1UL<<1)
 613 #define SECTION_MAP_LAST_BIT    (1UL<<2)
 614 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
 615 #define SECTION_NID_SHIFT       2
 616
 617 static inline struct page *__section_mem_map_addr(struct mem_section *section)
 618 {
 619         unsigned long map = section->section_mem_map;
 620         map &= SECTION_MAP_MASK;
 621         return (struct page *)map;
 622 }
 623
 624 static inline int valid_section(struct mem_section *section)
 625 {
 626         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
 627 }
 628
 629 static inline int section_has_mem_map(struct mem_section *section)
 630 {
 631         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
 632 }
 633
 634 static inline int valid_section_nr(unsigned long nr)
 635 {
 636         return valid_section(__nr_to_section(nr));
 637 }
 638
 639 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
 640 {
 641         return __nr_to_section(pfn_to_section_nr(pfn));
 642 }
 643
 644 static inline int pfn_valid(unsigned long pfn)
 645 {
 646         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
 647                 return 0;
 648         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
 649 }
 650
 651 /*
 652  * These are _only_ used during initialisation, therefore they
 653  * can use __initdata ...  They could have names to indicate
 654  * this restriction.
 655  */
 656 #ifdef CONFIG_NUMA
 657 #define pfn_to_nid(pfn)                                                 \
 658 ({                                                                      \
 659         unsigned long __pfn_to_nid_pfn = (pfn);                         \
 660         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
 661 })
 662 #else
 663 #define pfn_to_nid(pfn)         (0)
 664 #endif
 665
 666 #define early_pfn_valid(pfn)    pfn_valid(pfn)
 667 void sparse_init(void);
 668 #else
 669 #define sparse_init()   do {} while (0)
 670 #define sparse_index_init(_sec, _nid)  do {} while (0)
 671 #endif /* CONFIG_SPARSEMEM */
 672
 673 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
 674 #define early_pfn_in_nid(pfn, nid)      (early_pfn_to_nid(pfn) == (nid))
 675 #else
 676 #define early_pfn_in_nid(pfn, nid)      (1)
 677 #endif
 678
 679 #ifndef early_pfn_valid
 680 #define early_pfn_valid(pfn)    (1)
 681 #endif
 682
 683 void memory_present(int nid, unsigned long start, unsigned long end);
 684 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 685
 686 #endif /* !__ASSEMBLY__ */
 687 #endif /* __KERNEL__ */
 688 #endif /* _LINUX_MMZONE_H */