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/compiler.h>
   9 #include <linux/highmem.h>
  10 #include <linux/export.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/vmalloc.h>
  13
  14 #include "internal.h"
  15 #include <asm/dma.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/pgtable.h>
  18
  19 /*
  20  * Permanent SPARSEMEM data:
  21  *
  22  * 1) mem_section       - memory sections, mem_map's for valid memory
  23  */
  24 #ifdef CONFIG_SPARSEMEM_EXTREME
  25 struct mem_section *mem_section[NR_SECTION_ROOTS]
  26         ____cacheline_internodealigned_in_smp;
  27 #else
  28 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
  29         ____cacheline_internodealigned_in_smp;
  30 #endif
  31 EXPORT_SYMBOL(mem_section);
  32
  33 #ifdef NODE_NOT_IN_PAGE_FLAGS
  34 /*
  35  * If we did not store the node number in the page then we have to
  36  * do a lookup in the section_to_node_table in order to find which
  37  * node the page belongs to.
  38  */
  39 #if MAX_NUMNODES <= 256
  40 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  41 #else
  42 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  43 #endif
  44
  45 int page_to_nid(const struct page *page)
  46 {
  47         return section_to_node_table[page_to_section(page)];
  48 }
  49 EXPORT_SYMBOL(page_to_nid);
  50
  51 static void set_section_nid(unsigned long section_nr, int nid)
  52 {
  53         section_to_node_table[section_nr] = nid;
  54 }
  55 #else /* !NODE_NOT_IN_PAGE_FLAGS */
  56 static inline void set_section_nid(unsigned long section_nr, int nid)
  57 {
  58 }
  59 #endif
  60
  61 #ifdef CONFIG_SPARSEMEM_EXTREME
  62 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
  63 {
  64         struct mem_section *section = NULL;
  65         unsigned long array_size = SECTIONS_PER_ROOT *
  66                                    sizeof(struct mem_section);
  67
  68         if (slab_is_available()) {
  69                 if (node_state(nid, N_HIGH_MEMORY))
  70                         section = kzalloc_node(array_size, GFP_KERNEL, nid);
  71                 else
  72                         section = kzalloc(array_size, GFP_KERNEL);
  73         } else {
  74                 section = memblock_virt_alloc_node(array_size, nid);
  75         }
  76
  77         return section;
  78 }
  79
  80 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
  81 {
  82         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  83         struct mem_section *section;
  84
  85         if (mem_section[root])
  86                 return -EEXIST;
  87
  88         section = sparse_index_alloc(nid);
  89         if (!section)
  90                 return -ENOMEM;
  91
  92         mem_section[root] = section;
  93
  94         return 0;
  95 }
  96 #else /* !SPARSEMEM_EXTREME */
  97 static inline int sparse_index_init(unsigned long section_nr, int nid)
  98 {
  99         return 0;
 100 }
 101 #endif
 102
 103 #ifdef CONFIG_SPARSEMEM_EXTREME
 104 int __section_nr(struct mem_section* ms)
 105 {
 106         unsigned long root_nr;
 107         struct mem_section* root;
 108
 109         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 110                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 111                 if (!root)
 112                         continue;
 113
 114                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
 115                      break;
 116         }
 117
 118         VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
 119
 120         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 121 }
 122 #else
 123 int __section_nr(struct mem_section* ms)
 124 {
 125         return (int)(ms - mem_section[0]);
 126 }
 127 #endif
 128
 129 /*
 130  * During early boot, before section_mem_map is used for an actual
 131  * mem_map, we use section_mem_map to store the section's NUMA
 132  * node.  This keeps us from having to use another data structure.  The
 133  * node information is cleared just before we store the real mem_map.
 134  */
 135 static inline unsigned long sparse_encode_early_nid(int nid)
 136 {
 137         return (nid << SECTION_NID_SHIFT);
 138 }
 139
 140 static inline int sparse_early_nid(struct mem_section *section)
 141 {
 142         return (section->section_mem_map >> SECTION_NID_SHIFT);
 143 }
 144
 145 /* Validate the physical addressing limitations of the model */
 146 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
 147                                                 unsigned long *end_pfn)
 148 {
 149         unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
 150
 151         /*
 152          * Sanity checks - do not allow an architecture to pass
 153          * in larger pfns than the maximum scope of sparsemem:
 154          */
 155         if (*start_pfn > max_sparsemem_pfn) {
 156                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 157                         "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 158                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 159                 WARN_ON_ONCE(1);
 160                 *start_pfn = max_sparsemem_pfn;
 161                 *end_pfn = max_sparsemem_pfn;
 162         } else if (*end_pfn > max_sparsemem_pfn) {
 163                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 164                         "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 165                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 166                 WARN_ON_ONCE(1);
 167                 *end_pfn = max_sparsemem_pfn;
 168         }
 169 }
 170
 171 /* Record a memory area against a node. */
 172 void __init memory_present(int nid, unsigned long start, unsigned long end)
 173 {
 174         unsigned long pfn;
 175
 176         start &= PAGE_SECTION_MASK;
 177         mminit_validate_memmodel_limits(&start, &end);
 178         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
 179                 unsigned long section = pfn_to_section_nr(pfn);
 180                 struct mem_section *ms;
 181
 182                 sparse_index_init(section, nid);
 183                 set_section_nid(section, nid);
 184
 185                 ms = __nr_to_section(section);
 186                 if (!ms->section_mem_map)
 187                         ms->section_mem_map = sparse_encode_early_nid(nid) |
 188                                                         SECTION_MARKED_PRESENT;
 189         }
 190 }
 191
 192 /*
 193  * Only used by the i386 NUMA architecures, but relatively
 194  * generic code.
 195  */
 196 unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
 197                                                      unsigned long end_pfn)
 198 {
 199         unsigned long pfn;
 200         unsigned long nr_pages = 0;
 201
 202         mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
 203         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 204                 if (nid != early_pfn_to_nid(pfn))
 205                         continue;
 206
 207                 if (pfn_present(pfn))
 208                         nr_pages += PAGES_PER_SECTION;
 209         }
 210
 211         return nr_pages * sizeof(struct page);
 212 }
 213
 214 /*
 215  * Subtle, we encode the real pfn into the mem_map such that
 216  * the identity pfn - section_mem_map will return the actual
 217  * physical page frame number.
 218  */
 219 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
 220 {
 221         return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
 222 }
 223
 224 /*
 225  * Decode mem_map from the coded memmap
 226  */
 227 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
 228 {
 229         /* mask off the extra low bits of information */
 230         coded_mem_map &= SECTION_MAP_MASK;
 231         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 232 }
 233
 234 static int __meminit sparse_init_one_section(struct mem_section *ms,
 235                 unsigned long pnum, struct page *mem_map,
 236                 unsigned long *pageblock_bitmap)
 237 {
 238         if (!present_section(ms))
 239                 return -EINVAL;
 240
 241         ms->section_mem_map &= ~SECTION_MAP_MASK;
 242         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
 243                                                         SECTION_HAS_MEM_MAP;
 244         ms->pageblock_flags = pageblock_bitmap;
 245
 246         return 1;
 247 }
 248
 249 unsigned long usemap_size(void)
 250 {
 251         unsigned long size_bytes;
 252         size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8;
 253         size_bytes = roundup(size_bytes, sizeof(unsigned long));
 254         return size_bytes;
 255 }
 256
 257 #ifdef CONFIG_MEMORY_HOTPLUG
 258 static unsigned long *__kmalloc_section_usemap(void)
 259 {
 260         return kmalloc(usemap_size(), GFP_KERNEL);
 261 }
 262 #endif /* CONFIG_MEMORY_HOTPLUG */
 263
 264 #ifdef CONFIG_MEMORY_HOTREMOVE
 265 static unsigned long * __init
 266 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 267                                          unsigned long size)
 268 {
 269         unsigned long goal, limit;
 270         unsigned long *p;
 271         int nid;
 272         /*
 273          * A page may contain usemaps for other sections preventing the
 274          * page being freed and making a section unremovable while
 275          * other sections referencing the usemap remain active. Similarly,
 276          * a pgdat can prevent a section being removed. If section A
 277          * contains a pgdat and section B contains the usemap, both
 278          * sections become inter-dependent. This allocates usemaps
 279          * from the same section as the pgdat where possible to avoid
 280          * this problem.
 281          */
 282         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
 283         limit = goal + (1UL << PA_SECTION_SHIFT);
 284         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
 285 again:
 286         p = memblock_virt_alloc_try_nid_nopanic(size,
 287                                                 SMP_CACHE_BYTES, goal, limit,
 288                                                 nid);
 289         if (!p && limit) {
 290                 limit = 0;
 291                 goto again;
 292         }
 293         return p;
 294 }
 295
 296 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 297 {
 298         unsigned long usemap_snr, pgdat_snr;
 299         static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
 300         static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
 301         struct pglist_data *pgdat = NODE_DATA(nid);
 302         int usemap_nid;
 303
 304         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
 305         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 306         if (usemap_snr == pgdat_snr)
 307                 return;
 308
 309         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
 310                 /* skip redundant message */
 311                 return;
 312
 313         old_usemap_snr = usemap_snr;
 314         old_pgdat_snr = pgdat_snr;
 315
 316         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
 317         if (usemap_nid != nid) {
 318                 pr_info("node %d must be removed before remove section %ld\n",
 319                         nid, usemap_snr);
 320                 return;
 321         }
 322         /*
 323          * There is a circular dependency.
 324          * Some platforms allow un-removable section because they will just
 325          * gather other removable sections for dynamic partitioning.
 326          * Just notify un-removable section's number here.
 327          */
 328         pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
 329                 usemap_snr, pgdat_snr, nid);
 330 }
 331 #else
 332 static unsigned long * __init
 333 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 334                                          unsigned long size)
 335 {
 336         return memblock_virt_alloc_node_nopanic(size, pgdat->node_id);
 337 }
 338
 339 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 340 {
 341 }
 342 #endif /* CONFIG_MEMORY_HOTREMOVE */
 343
 344 static void __init sparse_early_usemaps_alloc_node(void *data,
 345                                  unsigned long pnum_begin,
 346                                  unsigned long pnum_end,
 347                                  unsigned long usemap_count, int nodeid)
 348 {
 349         void *usemap;
 350         unsigned long pnum;
 351         unsigned long **usemap_map = (unsigned long **)data;
 352         int size = usemap_size();
 353
 354         usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
 355                                                           size * usemap_count);
 356         if (!usemap) {
 357                 pr_warn("%s: allocation failed\n", __func__);
 358                 return;
 359         }
 360
 361         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 362                 if (!present_section_nr(pnum))
 363                         continue;
 364                 usemap_map[pnum] = usemap;
 365                 usemap += size;
 366                 check_usemap_section_nr(nodeid, usemap_map[pnum]);
 367         }
 368 }
 369
 370 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 371 struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
 372 {
 373         struct page *map;
 374         unsigned long size;
 375
 376         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
 377         if (map)
 378                 return map;
 379
 380         size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
 381         map = memblock_virt_alloc_try_nid(size,
 382                                           PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
 383                                           BOOTMEM_ALLOC_ACCESSIBLE, nid);
 384         return map;
 385 }
 386 void __init sparse_mem_maps_populate_node(struct page **map_map,
 387                                           unsigned long pnum_begin,
 388                                           unsigned long pnum_end,
 389                                           unsigned long map_count, int nodeid)
 390 {
 391         void *map;
 392         unsigned long pnum;
 393         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 394
 395         map = alloc_remap(nodeid, size * map_count);
 396         if (map) {
 397                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 398                         if (!present_section_nr(pnum))
 399                                 continue;
 400                         map_map[pnum] = map;
 401                         map += size;
 402                 }
 403                 return;
 404         }
 405
 406         size = PAGE_ALIGN(size);
 407         map = memblock_virt_alloc_try_nid(size * map_count,
 408                                           PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
 409                                           BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
 410         if (map) {
 411                 for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 412                         if (!present_section_nr(pnum))
 413                                 continue;
 414                         map_map[pnum] = map;
 415                         map += size;
 416                 }
 417                 return;
 418         }
 419
 420         /* fallback */
 421         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 422                 struct mem_section *ms;
 423
 424                 if (!present_section_nr(pnum))
 425                         continue;
 426                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 427                 if (map_map[pnum])
 428                         continue;
 429                 ms = __nr_to_section(pnum);
 430                 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
 431                        __func__);
 432                 ms->section_mem_map = 0;
 433         }
 434 }
 435 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 436
 437 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 438 static void __init sparse_early_mem_maps_alloc_node(void *data,
 439                                  unsigned long pnum_begin,
 440                                  unsigned long pnum_end,
 441                                  unsigned long map_count, int nodeid)
 442 {
 443         struct page **map_map = (struct page **)data;
 444         sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
 445                                          map_count, nodeid);
 446 }
 447 #else
 448 static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
 449 {
 450         struct page *map;
 451         struct mem_section *ms = __nr_to_section(pnum);
 452         int nid = sparse_early_nid(ms);
 453
 454         map = sparse_mem_map_populate(pnum, nid);
 455         if (map)
 456                 return map;
 457
 458         pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
 459                __func__);
 460         ms->section_mem_map = 0;
 461         return NULL;
 462 }
 463 #endif
 464
 465 void __weak __meminit vmemmap_populate_print_last(void)
 466 {
 467 }
 468
 469 /**
 470  *  alloc_usemap_and_memmap - memory alloction for pageblock flags and vmemmap
 471  *  @map: usemap_map for pageblock flags or mmap_map for vmemmap
 472  */
 473 static void __init alloc_usemap_and_memmap(void (*alloc_func)
 474                                         (void *, unsigned long, unsigned long,
 475                                         unsigned long, int), void *data)
 476 {
 477         unsigned long pnum;
 478         unsigned long map_count;
 479         int nodeid_begin = 0;
 480         unsigned long pnum_begin = 0;
 481
 482         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 483                 struct mem_section *ms;
 484
 485                 if (!present_section_nr(pnum))
 486                         continue;
 487                 ms = __nr_to_section(pnum);
 488                 nodeid_begin = sparse_early_nid(ms);
 489                 pnum_begin = pnum;
 490                 break;
 491         }
 492         map_count = 1;
 493         for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
 494                 struct mem_section *ms;
 495                 int nodeid;
 496
 497                 if (!present_section_nr(pnum))
 498                         continue;
 499                 ms = __nr_to_section(pnum);
 500                 nodeid = sparse_early_nid(ms);
 501                 if (nodeid == nodeid_begin) {
 502                         map_count++;
 503                         continue;
 504                 }
 505                 /* ok, we need to take cake of from pnum_begin to pnum - 1*/
 506                 alloc_func(data, pnum_begin, pnum,
 507                                                 map_count, nodeid_begin);
 508                 /* new start, update count etc*/
 509                 nodeid_begin = nodeid;
 510                 pnum_begin = pnum;
 511                 map_count = 1;
 512         }
 513         /* ok, last chunk */
 514         alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
 515                                                 map_count, nodeid_begin);
 516 }
 517
 518 /*
 519  * Allocate the accumulated non-linear sections, allocate a mem_map
 520  * for each and record the physical to section mapping.
 521  */
 522 void __init sparse_init(void)
 523 {
 524         unsigned long pnum;
 525         struct page *map;
 526         unsigned long *usemap;
 527         unsigned long **usemap_map;
 528         int size;
 529 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 530         int size2;
 531         struct page **map_map;
 532 #endif
 533
 534         /* see include/linux/mmzone.h 'struct mem_section' definition */
 535         BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
 536
 537         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
 538         set_pageblock_order();
 539
 540         /*
 541          * map is using big page (aka 2M in x86 64 bit)
 542          * usemap is less one page (aka 24 bytes)
 543          * so alloc 2M (with 2M align) and 24 bytes in turn will
 544          * make next 2M slip to one more 2M later.
 545          * then in big system, the memory will have a lot of holes...
 546          * here try to allocate 2M pages continuously.
 547          *
 548          * powerpc need to call sparse_init_one_section right after each
 549          * sparse_early_mem_map_alloc, so allocate usemap_map at first.
 550          */
 551         size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
 552         usemap_map = memblock_virt_alloc(size, 0);
 553         if (!usemap_map)
 554                 panic("can not allocate usemap_map\n");
 555         alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node,
 556                                                         (void *)usemap_map);
 557
 558 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 559         size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
 560         map_map = memblock_virt_alloc(size2, 0);
 561         if (!map_map)
 562                 panic("can not allocate map_map\n");
 563         alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node,
 564                                                         (void *)map_map);
 565 #endif
 566
 567         for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 568                 if (!present_section_nr(pnum))
 569                         continue;
 570
 571                 usemap = usemap_map[pnum];
 572                 if (!usemap)
 573                         continue;
 574
 575 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 576                 map = map_map[pnum];
 577 #else
 578                 map = sparse_early_mem_map_alloc(pnum);
 579 #endif
 580                 if (!map)
 581                         continue;
 582
 583                 sparse_init_one_section(__nr_to_section(pnum), pnum, map,
 584                                                                 usemap);
 585         }
 586
 587         vmemmap_populate_print_last();
 588
 589 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 590         memblock_free_early(__pa(map_map), size2);
 591 #endif
 592         memblock_free_early(__pa(usemap_map), size);
 593 }
 594
 595 #ifdef CONFIG_MEMORY_HOTPLUG
 596 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 597 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
 598 {
 599         /* This will make the necessary allocations eventually. */
 600         return sparse_mem_map_populate(pnum, nid);
 601 }
 602 static void __kfree_section_memmap(struct page *memmap)
 603 {
 604         unsigned long start = (unsigned long)memmap;
 605         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
 606
 607         vmemmap_free(start, end);
 608 }
 609 #ifdef CONFIG_MEMORY_HOTREMOVE
 610 static void free_map_bootmem(struct page *memmap)
 611 {
 612         unsigned long start = (unsigned long)memmap;
 613         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
 614
 615         vmemmap_free(start, end);
 616 }
 617 #endif /* CONFIG_MEMORY_HOTREMOVE */
 618 #else
 619 static struct page *__kmalloc_section_memmap(void)
 620 {
 621         struct page *page, *ret;
 622         unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
 623
 624         page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
 625         if (page)
 626                 goto got_map_page;
 627
 628         ret = vmalloc(memmap_size);
 629         if (ret)
 630                 goto got_map_ptr;
 631
 632         return NULL;
 633 got_map_page:
 634         ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
 635 got_map_ptr:
 636
 637         return ret;
 638 }
 639
 640 static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid)
 641 {
 642         return __kmalloc_section_memmap();
 643 }
 644
 645 static void __kfree_section_memmap(struct page *memmap)
 646 {
 647         if (is_vmalloc_addr(memmap))
 648                 vfree(memmap);
 649         else
 650                 free_pages((unsigned long)memmap,
 651                            get_order(sizeof(struct page) * PAGES_PER_SECTION));
 652 }
 653
 654 #ifdef CONFIG_MEMORY_HOTREMOVE
 655 static void free_map_bootmem(struct page *memmap)
 656 {
 657         unsigned long maps_section_nr, removing_section_nr, i;
 658         unsigned long magic, nr_pages;
 659         struct page *page = virt_to_page(memmap);
 660
 661         nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
 662                 >> PAGE_SHIFT;
 663
 664         for (i = 0; i < nr_pages; i++, page++) {
 665                 magic = (unsigned long) page->lru.next;
 666
 667                 BUG_ON(magic == NODE_INFO);
 668
 669                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
 670                 removing_section_nr = page->private;
 671
 672                 /*
 673                  * When this function is called, the removing section is
 674                  * logical offlined state. This means all pages are isolated
 675                  * from page allocator. If removing section's memmap is placed
 676                  * on the same section, it must not be freed.
 677                  * If it is freed, page allocator may allocate it which will
 678                  * be removed physically soon.
 679                  */
 680                 if (maps_section_nr != removing_section_nr)
 681                         put_page_bootmem(page);
 682         }
 683 }
 684 #endif /* CONFIG_MEMORY_HOTREMOVE */
 685 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 686
 687 /*
 688  * returns the number of sections whose mem_maps were properly
 689  * set.  If this is <=0, then that means that the passed-in
 690  * map was not consumed and must be freed.
 691  */
 692 int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn)
 693 {
 694         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 695         struct pglist_data *pgdat = zone->zone_pgdat;
 696         struct mem_section *ms;
 697         struct page *memmap;
 698         unsigned long *usemap;
 699         unsigned long flags;
 700         int ret;
 701
 702         /*
 703          * no locking for this, because it does its own
 704          * plus, it does a kmalloc
 705          */
 706         ret = sparse_index_init(section_nr, pgdat->node_id);
 707         if (ret < 0 && ret != -EEXIST)
 708                 return ret;
 709         memmap = kmalloc_section_memmap(section_nr, pgdat->node_id);
 710         if (!memmap)
 711                 return -ENOMEM;
 712         usemap = __kmalloc_section_usemap();
 713         if (!usemap) {
 714                 __kfree_section_memmap(memmap);
 715                 return -ENOMEM;
 716         }
 717
 718         pgdat_resize_lock(pgdat, &flags);
 719
 720         ms = __pfn_to_section(start_pfn);
 721         if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
 722                 ret = -EEXIST;
 723                 goto out;
 724         }
 725
 726         memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
 727
 728         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 729
 730         ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
 731
 732 out:
 733         pgdat_resize_unlock(pgdat, &flags);
 734         if (ret <= 0) {
 735                 kfree(usemap);
 736                 __kfree_section_memmap(memmap);
 737         }
 738         return ret;
 739 }
 740
 741 #ifdef CONFIG_MEMORY_HOTREMOVE
 742 #ifdef CONFIG_MEMORY_FAILURE
 743 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 744 {
 745         int i;
 746
 747         if (!memmap)
 748                 return;
 749
 750         for (i = 0; i < nr_pages; i++) {
 751                 if (PageHWPoison(&memmap[i])) {
 752                         atomic_long_sub(1, &num_poisoned_pages);
 753                         ClearPageHWPoison(&memmap[i]);
 754                 }
 755         }
 756 }
 757 #else
 758 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 759 {
 760 }
 761 #endif
 762
 763 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 764 {
 765         struct page *usemap_page;
 766
 767         if (!usemap)
 768                 return;
 769
 770         usemap_page = virt_to_page(usemap);
 771         /*
 772          * Check to see if allocation came from hot-plug-add
 773          */
 774         if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
 775                 kfree(usemap);
 776                 if (memmap)
 777                         __kfree_section_memmap(memmap);
 778                 return;
 779         }
 780
 781         /*
 782          * The usemap came from bootmem. This is packed with other usemaps
 783          * on the section which has pgdat at boot time. Just keep it as is now.
 784          */
 785
 786         if (memmap)
 787                 free_map_bootmem(memmap);
 788 }
 789
 790 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
 791                 unsigned long map_offset)
 792 {
 793         struct page *memmap = NULL;
 794         unsigned long *usemap = NULL, flags;
 795         struct pglist_data *pgdat = zone->zone_pgdat;
 796
 797         pgdat_resize_lock(pgdat, &flags);
 798         if (ms->section_mem_map) {
 799                 usemap = ms->pageblock_flags;
 800                 memmap = sparse_decode_mem_map(ms->section_mem_map,
 801                                                 __section_nr(ms));
 802                 ms->section_mem_map = 0;
 803                 ms->pageblock_flags = NULL;
 804         }
 805         pgdat_resize_unlock(pgdat, &flags);
 806
 807         clear_hwpoisoned_pages(memmap + map_offset,
 808                         PAGES_PER_SECTION - map_offset);
 809         free_section_usemap(memmap, usemap);
 810 }
 811 #endif /* CONFIG_MEMORY_HOTREMOVE */
 812 #endif /* CONFIG_MEMORY_HOTPLUG */