mm/sparse.c

   1 /*
   2  * sparse memory mappings.
   3  */
   4 #include <linux/mm.h>
   5 #include <linux/slab.h>
   6 #include <linux/mmzone.h>
   7 #include <linux/bootmem.h>
   8 #include <linux/highmem.h>
   9 #include <linux/export.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/vmalloc.h>
  12 #include "internal.h"
  13 #include <asm/dma.h>
  14 #include <asm/pgalloc.h>
  15 #include <asm/pgtable.h>
  16
  17 /*
  18  * Permanent SPARSEMEM data:
  19  *
  20  * 1) mem_section       - memory sections, mem_map's for valid memory
  21  */
  22 #ifdef CONFIG_SPARSEMEM_EXTREME
  23 struct mem_section *mem_section[NR_SECTION_ROOTS]
  24         ____cacheline_internodealigned_in_smp;
  25 #else
  26 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
  27         ____cacheline_internodealigned_in_smp;
  28 #endif
  29 EXPORT_SYMBOL(mem_section);
  30
  31 #ifdef NODE_NOT_IN_PAGE_FLAGS
  32 /*
  33  * If we did not store the node number in the page then we have to
  34  * do a lookup in the section_to_node_table in order to find which
  35  * node the page belongs to.
  36  */
  37 #if MAX_NUMNODES <= 256
  38 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  39 #else
  40 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  41 #endif
  42
  43 int page_to_nid(const struct page *page)
  44 {
  45         return section_to_node_table[page_to_section(page)];
  46 }
  47 EXPORT_SYMBOL(page_to_nid);
  48
  49 static void set_section_nid(unsigned long section_nr, int nid)
  50 {
  51         section_to_node_table[section_nr] = nid;
  52 }
  53 #else /* !NODE_NOT_IN_PAGE_FLAGS */
  54 static inline void set_section_nid(unsigned long section_nr, int nid)
  55 {
  56 }
  57 #endif
  58
  59 #ifdef CONFIG_SPARSEMEM_EXTREME
  60 static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
  61 {
  62         struct mem_section *section = NULL;
  63         unsigned long array_size = SECTIONS_PER_ROOT *
  64                                    sizeof(struct mem_section);
  65
  66         if (slab_is_available()) {
  67                 if (node_state(nid, N_HIGH_MEMORY))
  68                         section = kzalloc_node(array_size, GFP_KERNEL, nid);
  69                 else
  70                         section = kzalloc(array_size, GFP_KERNEL);
  71         } else {
  72                 section = alloc_bootmem_node(NODE_DATA(nid), array_size);
  73         }
  74
  75         return section;
  76 }
  77
  78 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
  79 {
  80         static DEFINE_SPINLOCK(index_init_lock);
  81         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  82         struct mem_section *section;
  83         int ret = 0;
  84
  85         if (mem_section[root])
  86                 return -EEXIST;
  87
  88         section = sparse_index_alloc(nid);
  89         if (!section)
  90                 return -ENOMEM;
  91         /*
  92          * This lock keeps two different sections from
  93          * reallocating for the same index
  94          */
  95         spin_lock(&index_init_lock);
  96
  97         if (mem_section[root]) {
  98                 ret = -EEXIST;
  99                 goto out;
 100         }
 101
 102         mem_section[root] = section;
 103 out:
 104         spin_unlock(&index_init_lock);
 105         return ret;
 106 }
 107 #else /* !SPARSEMEM_EXTREME */
 108 static inline int sparse_index_init(unsigned long section_nr, int nid)
 109 {
 110         return 0;
 111 }
 112 #endif
 113
 114 /*
 115  * Although written for the SPARSEMEM_EXTREME case, this happens
 116  * to also work for the flat array case because
 117  * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
 118  */
 119 int __section_nr(struct mem_section* ms)
 120 {
 121         unsigned long root_nr;
 122         struct mem_section* root;
 123
 124         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 125                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 126                 if (!root)
 127                         continue;
 128
 129                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
 130                      break;
 131         }
 132
 133         VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
 134
 135         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 136 }
 137
 138 /*
 139  * During early boot, before section_mem_map is used for an actual
 140  * mem_map, we use section_mem_map to store the section's NUMA
 141  * node.  This keeps us from having to use another data structure.  The
 142  * node information is cleared just before we store the real mem_map.
 143  */
 144 static inline unsigned long sparse_encode_early_nid(int nid)
 145 {
 146         return (nid << SECTION_NID_SHIFT);
 147 }
 148
 149 static inline int sparse_early_nid(struct mem_section *section)
 150 {
 151         return (section->section_mem_map >> SECTION_NID_SHIFT);
 152 }
 153
 154 /* Validate the physical addressing limitations of the model */
 155 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
 156                                                 unsigned long *end_pfn)
 157 {
 158         unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
 159
 160         /*
 161          * Sanity checks - do not allow an architecture to pass
 162          * in larger pfns than the maximum scope of sparsemem:
 163          */
 164         if (*start_pfn > max_sparsemem_pfn) {
 165                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 166                         "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 167                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 168                 WARN_ON_ONCE(1);
 169                 *start_pfn = max_sparsemem_pfn;
 170                 *end_pfn = max_sparsemem_pfn;
 171         } else if (*end_pfn > max_sparsemem_pfn) {
 172                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 173                         "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 174                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 175                 WARN_ON_ONCE(1);
 176                 *end_pfn = max_sparsemem_pfn;
 177         }
 178 }
 179
 180 /* Record a memory area against a node. */
 181 void __init memory_present(int nid, unsigned long start, unsigned long end)
 182 {
 183         unsigned long pfn;
 184
 185         start &= PAGE_SECTION_MASK;
 186         mminit_validate_memmodel_limits(&start, &end);
 187         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
 188                 unsigned long section = pfn_to_section_nr(pfn);
 189                 struct mem_section *ms;
 190
 191                 sparse_index_init(section, nid);
 192                 set_section_nid(section, nid);
 193
 194                 ms = __nr_to_section(section);
 195                 if (!ms->section_mem_map)
 196                         ms->section_mem_map = sparse_encode_early_nid(nid) |
 197                                                         SECTION_MARKED_PRESENT;
 198         }
 199 }
 200
 201 /*
 202  * Only used by the i386 NUMA architecures, but relatively
 203  * generic code.
 204  */
 205 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
 206                                                      unsigned long end_pfn)
 207 {
 208         unsigned long pfn;
 209         unsigned long nr_pages = 0;
 210
 211         mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
 212         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 213                 if (nid != early_pfn_to_nid(pfn))
 214                         continue;
 215
 216                 if (pfn_present(pfn))
 217                         nr_pages += PAGES_PER_SECTION;
 218         }
 219
 220         return nr_pages * sizeof(struct page);
 221 }
 222
 223 /*
 224  * Subtle, we encode the real pfn into the mem_map such that
 225  * the identity pfn - section_mem_map will return the actual
 226  * physical page frame number.
 227  */
 228 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
 229 {
 230         return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
 231 }
 232
 233 /*
 234  * Decode mem_map from the coded memmap
 235  */
 236 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
 237 {
 238         /* mask off the extra low bits of information */
 239         coded_mem_map &= SECTION_MAP_MASK;
 240         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 241 }
 242
 243 static int __meminit sparse_init_one_section(struct mem_section *ms,
 244                 unsigned long pnum, struct page *mem_map,
 245                 unsigned long *pageblock_bitmap)
 246 {
 247         if (!present_section(ms))
 248                 return -EINVAL;
 249
 250         ms->section_mem_map &= ~SECTION_MAP_MASK;
 251         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
 252                                                         SECTION_HAS_MEM_MAP;
 253         ms->pageblock_flags = pageblock_bitmap;
 254
 255         return 1;
 256 }
 257
 258 unsigned long usemap_size(void)
 259 {
 260         unsigned long size_bytes;
 261         size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
 262         size_bytes = roundup(size_bytes, sizeof(unsigned long));
 263         return size_bytes;
 264 }
 265
 266 #ifdef CONFIG_MEMORY_HOTPLUG
 267 static unsigned long *__kmalloc_section_usemap(void)
 268 {
 269         return kmalloc(usemap_size(), GFP_KERNEL);
 270 }
 271 #endif /* CONFIG_MEMORY_HOTPLUG */
 272
 273 #ifdef CONFIG_MEMORY_HOTREMOVE
 274 static unsigned long * __init
 275 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 276                                          unsigned long size)
 277 {
 278         unsigned long goal, limit;
 279         unsigned long *p;
 280         int nid;
 281         /*
 282          * A page may contain usemaps for other sections preventing the
 283          * page being freed and making a section unremovable while
 284          * other sections referencing the usemap retmain active. Similarly,
 285          * a pgdat can prevent a section being removed. If section A
 286          * contains a pgdat and section B contains the usemap, both
 287          * sections become inter-dependent. This allocates usemaps
 288          * from the same section as the pgdat where possible to avoid
 289          * this problem.
 290          */
 291         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
 292         limit = goal + (1UL << PA_SECTION_SHIFT);
 293         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
 294 again:
 295         p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
 296                                           SMP_CACHE_BYTES, goal, limit);
 297         if (!p && limit) {
 298                 limit = 0;
 299                 goto again;
 300         }
 301         return p;
 302 }
 303
 304 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 305 {
 306         unsigned long usemap_snr, pgdat_snr;
 307         static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
 308         static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
 309         struct pglist_data *pgdat = NODE_DATA(nid);
 310         int usemap_nid;
 311
 312         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
 313         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 314         if (usemap_snr == pgdat_snr)
 315                 return;
 316
 317         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
 318                 /* skip redundant message */
 319                 return;
 320
 321         old_usemap_snr = usemap_snr;
 322         old_pgdat_snr = pgdat_snr;
 323
 324         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
 325         if (usemap_nid != nid) {
 326                 printk(KERN_INFO
 327                        "node %d must be removed before remove section %ld\n",
 328                        nid, usemap_snr);
 329                 return;
 330         }
 331         /*
 332          * There is a circular dependency.
 333          * Some platforms allow un-removable section because they will just
 334          * gather other removable sections for dynamic partitioning.
 335          * Just notify un-removable section's number here.
 336          */
 337         printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
 338                pgdat_snr, nid);
 339         printk(KERN_CONT
 340                " have a circular dependency on usemap and pgdat allocations\n");
 341 }
 342 #else
 343 static unsigned long * __init
 344 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 345                                          unsigned long size)
 346 {
 347         return alloc_bootmem_node_nopanic(pgdat, size);
 348 }
 349
 350 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 351 {
 352 }
 353 #endif /* CONFIG_MEMORY_HOTREMOVE */
 354
 355 static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
 356                                  unsigned long pnum_begin,
 357                                  unsigned long pnum_end,
 358                                  unsigned long usemap_count, int nodeid)
 359 {
 360         void *usemap;
 361         unsigned long pnum;
 362         int size = usemap_size();
 363
 364         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
 365                                                           size * usemap_count);
 366         if (!usemap) {
 367                 printk(KERN_WARNING "%s: allocation failed\n", __func__);
 368                 return;
 369         }
 370
 371         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 372                 if (!present_section_nr(pnum))
 373                         continue;
 374                 usemap_map[pnum] = usemap;
 375                 usemap += size;
 376                 check_usemap_section_nr(nodeid, usemap_map[pnum]);
 377         }
 378 }
 379
 380 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 381 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
 382 {
 383         struct page *map;
 384         unsigned long size;
 385
 386         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
 387         if (map)
 388                 return map;
 389
 390         size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
 391         map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
 392                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
 393         return map;
 394 }
 395 void __init sparse_mem_maps_populate_node(struct page **map_map,
 396                                           unsigned long pnum_begin,
 397                                           unsigned long pnum_end,
 398                                           unsigned long map_count, int nodeid)
 399 {
 400         void *map;
 401         unsigned long pnum;
 402         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 403
 404         map = alloc_remap(nodeid, size * map_count);
 405         if (map) {
 406                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 407                         if (!present_section_nr(pnum))
 408                                 continue;
 409                         map_map[pnum] = map;
 410                         map += size;
 411                 }
 412                 return;
 413         }
 414
 415         size = PAGE_ALIGN(size);
 416         map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
 417                                          PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
 418         if (map) {
 419                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 420                         if (!present_section_nr(pnum))
 421                                 continue;
 422                         map_map[pnum] = map;
 423                         map += size;
 424                 }
 425                 return;
 426         }
 427
 428         /* fallback */
 429         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 430                 struct mem_section *ms;
 431
 432                 if (!present_section_nr(pnum))
 433                         continue;
 434                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 435                 if (map_map[pnum])
 436                         continue;
 437                 ms = __nr_to_section(pnum);
 438                 printk(KERN_ERR "%s: sparsemem memory map backing failed "
 439                         "some memory will not be available.\n", __func__);
 440                 ms->section_mem_map = 0;
 441         }
 442 }
 443 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 444
 445 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 446 static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
 447                                  unsigned long pnum_begin,
 448                                  unsigned long pnum_end,
 449                                  unsigned long map_count, int nodeid)
 450 {
 451         sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
 452                                          map_count, nodeid);
 453 }
 454 #else
 455 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
 456 {
 457         struct page *map;
 458         struct mem_section *ms = __nr_to_section(pnum);
 459         int nid = sparse_early_nid(ms);
 460
 461         map = sparse_mem_map_populate(pnum, nid);
 462         if (map)
 463                 return map;
 464
 465         printk(KERN_ERR "%s: sparsemem memory map backing failed "
 466                         "some memory will not be available.\n", __func__);
 467         ms->section_mem_map = 0;
 468         return NULL;
 469 }
 470 #endif
 471
 472 void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
 473 {
 474 }
 475
 476 /*
 477  * Allocate the accumulated non-linear sections, allocate a mem_map
 478  * for each and record the physical to section mapping.
 479  */
 480 void __init sparse_init(void)
 481 {
 482         unsigned long pnum;
 483         struct page *map;
 484         unsigned long *usemap;
 485         unsigned long **usemap_map;
 486         int size;
 487         int nodeid_begin = 0;
 488         unsigned long pnum_begin = 0;
 489         unsigned long usemap_count;
 490 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 491         unsigned long map_count;
 492         int size2;
 493         struct page **map_map;
 494 #endif
 495
 496         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
 497         set_pageblock_order();
 498
 499         /*
 500          * map is using big page (aka 2M in x86 64 bit)
 501          * usemap is less one page (aka 24 bytes)
 502          * so alloc 2M (with 2M align) and 24 bytes in turn will
 503          * make next 2M slip to one more 2M later.
 504          * then in big system, the memory will have a lot of holes...
 505          * here try to allocate 2M pages continuously.
 506          *
 507          * powerpc need to call sparse_init_one_section right after each
 508          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
 509          */
 510         size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
 511         usemap_map = alloc_bootmem(size);
 512         if (!usemap_map)
 513                 panic("can not allocate usemap_map\n");
 514
 515         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 516                 struct mem_section *ms;
 517
 518                 if (!present_section_nr(pnum))
 519                         continue;
 520                 ms = __nr_to_section(pnum);
 521                 nodeid_begin = sparse_early_nid(ms);
 522                 pnum_begin = pnum;
 523                 break;
 524         }
 525         usemap_count = 1;
 526         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
 527                 struct mem_section *ms;
 528                 int nodeid;
 529
 530                 if (!present_section_nr(pnum))
 531                         continue;
 532                 ms = __nr_to_section(pnum);
 533                 nodeid = sparse_early_nid(ms);
 534                 if (nodeid == nodeid_begin) {
 535                         usemap_count++;
 536                         continue;
 537                 }
 538                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
 539                 sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
 540                                                  usemap_count, nodeid_begin);
 541                 /* new start, update count etc*/
 542                 nodeid_begin = nodeid;
 543                 pnum_begin = pnum;
 544                 usemap_count = 1;
 545         }
 546         /* ok, last chunk */
 547         sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
 548                                          usemap_count, nodeid_begin);
 549
 550 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 551         size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
 552         map_map = alloc_bootmem(size2);
 553         if (!map_map)
 554                 panic("can not allocate map_map\n");
 555
 556         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 557                 struct mem_section *ms;
 558
 559                 if (!present_section_nr(pnum))
 560                         continue;
 561                 ms = __nr_to_section(pnum);
 562                 nodeid_begin = sparse_early_nid(ms);
 563                 pnum_begin = pnum;
 564                 break;
 565         }
 566         map_count = 1;
 567         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
 568                 struct mem_section *ms;
 569                 int nodeid;
 570
 571                 if (!present_section_nr(pnum))
 572                         continue;
 573                 ms = __nr_to_section(pnum);
 574                 nodeid = sparse_early_nid(ms);
 575                 if (nodeid == nodeid_begin) {
 576                         map_count++;
 577                         continue;
 578                 }
 579                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
 580                 sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
 581                                                  map_count, nodeid_begin);
 582                 /* new start, update count etc*/
 583                 nodeid_begin = nodeid;
 584                 pnum_begin = pnum;
 585                 map_count = 1;
 586         }
 587         /* ok, last chunk */
 588         sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
 589                                          map_count, nodeid_begin);
 590 #endif
 591
 592         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 593                 if (!present_section_nr(pnum))
 594                         continue;
 595
 596                 usemap = usemap_map[pnum];
 597                 if (!usemap)
 598                         continue;
 599
 600 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 601                 map = map_map[pnum];
 602 #else
 603                 map = sparse_early_mem_map_alloc(pnum);
 604 #endif
 605                 if (!map)
 606                         continue;
 607
 608                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
 609                                                                 usemap);
 610         }
 611
 612         vmemmap_populate_print_last();
 613
 614 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 615         free_bootmem(__pa(map_map), size2);
 616 #endif
 617         free_bootmem(__pa(usemap_map), size);
 618 }
 619
 620 #ifdef CONFIG_MEMORY_HOTPLUG
 621 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 622 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
 623                                                  unsigned long nr_pages)
 624 {
 625         /* This will make the necessary allocations eventually. */
 626         return sparse_mem_map_populate(pnum, nid);
 627 }
 628 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 629 {
 630         return; /* XXX: Not implemented yet */
 631 }
 632 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 633 {
 634 }
 635 #else
 636 static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
 637 {
 638         struct page *page, *ret;
 639         unsigned long memmap_size = sizeof(struct page) * nr_pages;
 640
 641         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
 642         if (page)
 643                 goto got_map_page;
 644
 645         ret = vmalloc(memmap_size);
 646         if (ret)
 647                 goto got_map_ptr;
 648
 649         return NULL;
 650 got_map_page:
 651         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
 652 got_map_ptr:
 653         memset(ret, 0, memmap_size);
 654
 655         return ret;
 656 }
 657
 658 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
 659                                                   unsigned long nr_pages)
 660 {
 661         return __kmalloc_section_memmap(nr_pages);
 662 }
 663
 664 static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 665 {
 666         if (is_vmalloc_addr(memmap))
 667                 vfree(memmap);
 668         else
 669                 free_pages((unsigned long)memmap,
 670                            get_order(sizeof(struct page) * nr_pages));
 671 }
 672
 673 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 674 {
 675         unsigned long maps_section_nr, removing_section_nr, i;
 676         unsigned long magic;
 677
 678         for (i = 0; i < nr_pages; i++, page++) {
 679                 magic = (unsigned long) page->lru.next;
 680
 681                 BUG_ON(magic == NODE_INFO);
 682
 683                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
 684                 removing_section_nr = page->private;
 685
 686                 /*
 687                  * When this function is called, the removing section is
 688                  * logical offlined state. This means all pages are isolated
 689                  * from page allocator. If removing section's memmap is placed
 690                  * on the same section, it must not be freed.
 691                  * If it is freed, page allocator may allocate it which will
 692                  * be removed physically soon.
 693                  */
 694                 if (maps_section_nr != removing_section_nr)
 695                         put_page_bootmem(page);
 696         }
 697 }
 698 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 699
 700 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 701 {
 702         struct page *usemap_page;
 703         unsigned long nr_pages;
 704
 705         if (!usemap)
 706                 return;
 707
 708         usemap_page = virt_to_page(usemap);
 709         /*
 710          * Check to see if allocation came from hot-plug-add
 711          */
 712         if (PageSlab(usemap_page)) {
 713                 kfree(usemap);
 714                 if (memmap)
 715                         __kfree_section_memmap(memmap, PAGES_PER_SECTION);
 716                 return;
 717         }
 718
 719         /*
 720          * The usemap came from bootmem. This is packed with other usemaps
 721          * on the section which has pgdat at boot time. Just keep it as is now.
 722          */
 723
 724         if (memmap) {
 725                 struct page *memmap_page;
 726                 memmap_page = virt_to_page(memmap);
 727
 728                 nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
 729                         >> PAGE_SHIFT;
 730
 731                 free_map_bootmem(memmap_page, nr_pages);
 732         }
 733 }
 734
 735 /*
 736  * returns the number of sections whose mem_maps were properly
 737  * set.  If this is <=0, then that means that the passed-in
 738  * map was not consumed and must be freed.
 739  */
 740 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 741                            int nr_pages)
 742 {
 743         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 744         struct pglist_data *pgdat = zone->zone_pgdat;
 745         struct mem_section *ms;
 746         struct page *memmap;
 747         unsigned long *usemap;
 748         unsigned long flags;
 749         int ret;
 750
 751         /*
 752          * no locking for this, because it does its own
 753          * plus, it does a kmalloc
 754          */
 755         ret = sparse_index_init(section_nr, pgdat->node_id);
 756         if (ret < 0 && ret != -EEXIST)
 757                 return ret;
 758         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
 759         if (!memmap)
 760                 return -ENOMEM;
 761         usemap = __kmalloc_section_usemap();
 762         if (!usemap) {
 763                 __kfree_section_memmap(memmap, nr_pages);
 764                 return -ENOMEM;
 765         }
 766
 767         pgdat_resize_lock(pgdat, &flags);
 768
 769         ms = __pfn_to_section(start_pfn);
 770         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
 771                 ret = -EEXIST;
 772                 goto out;
 773         }
 774
 775         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 776
 777         ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
 778
 779 out:
 780         pgdat_resize_unlock(pgdat, &flags);
 781         if (ret <= 0) {
 782                 kfree(usemap);
 783                 __kfree_section_memmap(memmap, nr_pages);
 784         }
 785         return ret;
 786 }
 787
 788 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 789 {
 790         struct page *memmap = NULL;
 791         unsigned long *usemap = NULL;
 792
 793         if (ms->section_mem_map) {
 794                 usemap = ms->pageblock_flags;
 795                 memmap = sparse_decode_mem_map(ms->section_mem_map,
 796                                                 __section_nr(ms));
 797                 ms->section_mem_map = 0;
 798                 ms->pageblock_flags = NULL;
 799         }
 800
 801         free_section_usemap(memmap, usemap);
 802 }
 803 #endif