linux/mm/sparse.c
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   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/module.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
  23struct mem_section *mem_section[NR_SECTION_ROOTS]
  24        ____cacheline_internodealigned_in_smp;
  25#else
  26struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
  27        ____cacheline_internodealigned_in_smp;
  28#endif
  29EXPORT_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
  38static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  39#else
  40static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  41#endif
  42
  43int page_to_nid(const struct page *page)
  44{
  45        return section_to_node_table[page_to_section(page)];
  46}
  47EXPORT_SYMBOL(page_to_nid);
  48
  49static 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 */
  54static inline void set_section_nid(unsigned long section_nr, int nid)
  55{
  56}
  57#endif
  58
  59#ifdef CONFIG_SPARSEMEM_EXTREME
  60static 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 = kmalloc_node(array_size, GFP_KERNEL, nid);
  69                else
  70                        section = kmalloc(array_size, GFP_KERNEL);
  71        } else
  72                section = alloc_bootmem_node(NODE_DATA(nid), array_size);
  73
  74        if (section)
  75                memset(section, 0, array_size);
  76
  77        return section;
  78}
  79
  80static int __meminit sparse_index_init(unsigned long section_nr, int nid)
  81{
  82        static DEFINE_SPINLOCK(index_init_lock);
  83        unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  84        struct mem_section *section;
  85        int ret = 0;
  86
  87        if (mem_section[root])
  88                return -EEXIST;
  89
  90        section = sparse_index_alloc(nid);
  91        if (!section)
  92                return -ENOMEM;
  93        /*
  94         * This lock keeps two different sections from
  95         * reallocating for the same index
  96         */
  97        spin_lock(&index_init_lock);
  98
  99        if (mem_section[root]) {
 100                ret = -EEXIST;
 101                goto out;
 102        }
 103
 104        mem_section[root] = section;
 105out:
 106        spin_unlock(&index_init_lock);
 107        return ret;
 108}
 109#else /* !SPARSEMEM_EXTREME */
 110static inline int sparse_index_init(unsigned long section_nr, int nid)
 111{
 112        return 0;
 113}
 114#endif
 115
 116/*
 117 * Although written for the SPARSEMEM_EXTREME case, this happens
 118 * to also work for the flat array case because
 119 * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
 120 */
 121int __section_nr(struct mem_section* ms)
 122{
 123        unsigned long root_nr;
 124        struct mem_section* root;
 125
 126        for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 127                root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 128                if (!root)
 129                        continue;
 130
 131                if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
 132                     break;
 133        }
 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 */
 144static inline unsigned long sparse_encode_early_nid(int nid)
 145{
 146        return (nid << SECTION_NID_SHIFT);
 147}
 148
 149static 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 */
 155void __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. */
 181void __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 */
 205unsigned 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 */
 228static 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 */
 236struct 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
 243static 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
 258unsigned 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
 267static 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
 274static unsigned long * __init
 275sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 276                                         unsigned long count)
 277{
 278        unsigned long section_nr;
 279
 280        /*
 281         * A page may contain usemaps for other sections preventing the
 282         * page being freed and making a section unremovable while
 283         * other sections referencing the usemap retmain active. Similarly,
 284         * a pgdat can prevent a section being removed. If section A
 285         * contains a pgdat and section B contains the usemap, both
 286         * sections become inter-dependent. This allocates usemaps
 287         * from the same section as the pgdat where possible to avoid
 288         * this problem.
 289         */
 290        section_nr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 291        return alloc_bootmem_section(usemap_size() * count, section_nr);
 292}
 293
 294static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 295{
 296        unsigned long usemap_snr, pgdat_snr;
 297        static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
 298        static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
 299        struct pglist_data *pgdat = NODE_DATA(nid);
 300        int usemap_nid;
 301
 302        usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
 303        pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 304        if (usemap_snr == pgdat_snr)
 305                return;
 306
 307        if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
 308                /* skip redundant message */
 309                return;
 310
 311        old_usemap_snr = usemap_snr;
 312        old_pgdat_snr = pgdat_snr;
 313
 314        usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
 315        if (usemap_nid != nid) {
 316                printk(KERN_INFO
 317                       "node %d must be removed before remove section %ld\n",
 318                       nid, usemap_snr);
 319                return;
 320        }
 321        /*
 322         * There is a circular dependency.
 323         * Some platforms allow un-removable section because they will just
 324         * gather other removable sections for dynamic partitioning.
 325         * Just notify un-removable section's number here.
 326         */
 327        printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
 328               pgdat_snr, nid);
 329        printk(KERN_CONT
 330               " have a circular dependency on usemap and pgdat allocations\n");
 331}
 332#else
 333static unsigned long * __init
 334sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 335                                         unsigned long count)
 336{
 337        return NULL;
 338}
 339
 340static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 341{
 342}
 343#endif /* CONFIG_MEMORY_HOTREMOVE */
 344
 345static void __init sparse_early_usemaps_alloc_node(unsigned long**usemap_map,
 346                                 unsigned long pnum_begin,
 347                                 unsigned long pnum_end,
 348                                 unsigned long usemap_count, int nodeid)
 349{
 350        void *usemap;
 351        unsigned long pnum;
 352        int size = usemap_size();
 353
 354        usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
 355                                                                 usemap_count);
 356        if (usemap) {
 357                for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 358                        if (!present_section_nr(pnum))
 359                                continue;
 360                        usemap_map[pnum] = usemap;
 361                        usemap += size;
 362                }
 363                return;
 364        }
 365
 366        usemap = alloc_bootmem_node(NODE_DATA(nodeid), size * usemap_count);
 367        if (usemap) {
 368                for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 369                        if (!present_section_nr(pnum))
 370                                continue;
 371                        usemap_map[pnum] = usemap;
 372                        usemap += size;
 373                        check_usemap_section_nr(nodeid, usemap_map[pnum]);
 374                }
 375                return;
 376        }
 377
 378        printk(KERN_WARNING "%s: allocation failed\n", __func__);
 379}
 380
 381#ifndef CONFIG_SPARSEMEM_VMEMMAP
 382struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid)
 383{
 384        struct page *map;
 385        unsigned long size;
 386
 387        map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
 388        if (map)
 389                return map;
 390
 391        size = PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
 392        map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
 393                                         PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
 394        return map;
 395}
 396void __init sparse_mem_maps_populate_node(struct page **map_map,
 397                                          unsigned long pnum_begin,
 398                                          unsigned long pnum_end,
 399                                          unsigned long map_count, int nodeid)
 400{
 401        void *map;
 402        unsigned long pnum;
 403        unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
 404
 405        map = alloc_remap(nodeid, size * map_count);
 406        if (map) {
 407                for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 408                        if (!present_section_nr(pnum))
 409                                continue;
 410                        map_map[pnum] = map;
 411                        map += size;
 412                }
 413                return;
 414        }
 415
 416        size = PAGE_ALIGN(size);
 417        map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
 418                                         PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
 419        if (map) {
 420                for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 421                        if (!present_section_nr(pnum))
 422                                continue;
 423                        map_map[pnum] = map;
 424                        map += size;
 425                }
 426                return;
 427        }
 428
 429        /* fallback */
 430        for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
 431                struct mem_section *ms;
 432
 433                if (!present_section_nr(pnum))
 434                        continue;
 435                map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
 436                if (map_map[pnum])
 437                        continue;
 438                ms = __nr_to_section(pnum);
 439                printk(KERN_ERR "%s: sparsemem memory map backing failed "
 440                        "some memory will not be available.\n", __func__);
 441                ms->section_mem_map = 0;
 442        }
 443}
 444#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 445
 446#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 447static void __init sparse_early_mem_maps_alloc_node(struct page **map_map,
 448                                 unsigned long pnum_begin,
 449                                 unsigned long pnum_end,
 450                                 unsigned long map_count, int nodeid)
 451{
 452        sparse_mem_maps_populate_node(map_map, pnum_begin, pnum_end,
 453                                         map_count, nodeid);
 454}
 455#else
 456static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
 457{
 458        struct page *map;
 459        struct mem_section *ms = __nr_to_section(pnum);
 460        int nid = sparse_early_nid(ms);
 461
 462        map = sparse_mem_map_populate(pnum, nid);
 463        if (map)
 464                return map;
 465
 466        printk(KERN_ERR "%s: sparsemem memory map backing failed "
 467                        "some memory will not be available.\n", __func__);
 468        ms->section_mem_map = 0;
 469        return NULL;
 470}
 471#endif
 472
 473void __attribute__((weak)) __meminit vmemmap_populate_print_last(void)
 474{
 475}
 476
 477/*
 478 * Allocate the accumulated non-linear sections, allocate a mem_map
 479 * for each and record the physical to section mapping.
 480 */
 481void __init sparse_init(void)
 482{
 483        unsigned long pnum;
 484        struct page *map;
 485        unsigned long *usemap;
 486        unsigned long **usemap_map;
 487        int size;
 488        int nodeid_begin = 0;
 489        unsigned long pnum_begin = 0;
 490        unsigned long usemap_count;
 491#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 492        unsigned long map_count;
 493        int size2;
 494        struct page **map_map;
 495#endif
 496
 497        /*
 498         * map is using big page (aka 2M in x86 64 bit)
 499         * usemap is less one page (aka 24 bytes)
 500         * so alloc 2M (with 2M align) and 24 bytes in turn will
 501         * make next 2M slip to one more 2M later.
 502         * then in big system, the memory will have a lot of holes...
 503         * here try to allocate 2M pages continuously.
 504         *
 505         * powerpc need to call sparse_init_one_section right after each
 506         * sparse_early_mem_map_alloc, so allocate usemap_map at first.
 507         */
 508        size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
 509        usemap_map = alloc_bootmem(size);
 510        if (!usemap_map)
 511                panic("can not allocate usemap_map\n");
 512
 513        for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 514                struct mem_section *ms;
 515
 516                if (!present_section_nr(pnum))
 517                        continue;
 518                ms = __nr_to_section(pnum);
 519                nodeid_begin = sparse_early_nid(ms);
 520                pnum_begin = pnum;
 521                break;
 522        }
 523        usemap_count = 1;
 524        for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
 525                struct mem_section *ms;
 526                int nodeid;
 527
 528                if (!present_section_nr(pnum))
 529                        continue;
 530                ms = __nr_to_section(pnum);
 531                nodeid = sparse_early_nid(ms);
 532                if (nodeid == nodeid_begin) {
 533                        usemap_count++;
 534                        continue;
 535                }
 536                /* ok, we need to take cake of from pnum_begin to pnum - 1*/
 537                sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum,
 538                                                 usemap_count, nodeid_begin);
 539                /* new start, update count etc*/
 540                nodeid_begin = nodeid;
 541                pnum_begin = pnum;
 542                usemap_count = 1;
 543        }
 544        /* ok, last chunk */
 545        sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS,
 546                                         usemap_count, nodeid_begin);
 547
 548#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 549        size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
 550        map_map = alloc_bootmem(size2);
 551        if (!map_map)
 552                panic("can not allocate map_map\n");
 553
 554        for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 555                struct mem_section *ms;
 556
 557                if (!present_section_nr(pnum))
 558                        continue;
 559                ms = __nr_to_section(pnum);
 560                nodeid_begin = sparse_early_nid(ms);
 561                pnum_begin = pnum;
 562                break;
 563        }
 564        map_count = 1;
 565        for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
 566                struct mem_section *ms;
 567                int nodeid;
 568
 569                if (!present_section_nr(pnum))
 570                        continue;
 571                ms = __nr_to_section(pnum);
 572                nodeid = sparse_early_nid(ms);
 573                if (nodeid == nodeid_begin) {
 574                        map_count++;
 575                        continue;
 576                }
 577                /* ok, we need to take cake of from pnum_begin to pnum - 1*/
 578                sparse_early_mem_maps_alloc_node(map_map, pnum_begin, pnum,
 579                                                 map_count, nodeid_begin);
 580                /* new start, update count etc*/
 581                nodeid_begin = nodeid;
 582                pnum_begin = pnum;
 583                map_count = 1;
 584        }
 585        /* ok, last chunk */
 586        sparse_early_mem_maps_alloc_node(map_map, pnum_begin, NR_MEM_SECTIONS,
 587                                         map_count, nodeid_begin);
 588#endif
 589
 590        for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 591                if (!present_section_nr(pnum))
 592                        continue;
 593
 594                usemap = usemap_map[pnum];
 595                if (!usemap)
 596                        continue;
 597
 598#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 599                map = map_map[pnum];
 600#else
 601                map = sparse_early_mem_map_alloc(pnum);
 602#endif
 603                if (!map)
 604                        continue;
 605
 606                sparse_init_one_section(__nr_to_section(pnum), pnum, map,
 607                                                                usemap);
 608        }
 609
 610        vmemmap_populate_print_last();
 611
 612#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 613        free_bootmem(__pa(map_map), size2);
 614#endif
 615        free_bootmem(__pa(usemap_map), size);
 616}
 617
 618#ifdef CONFIG_MEMORY_HOTPLUG
 619#ifdef CONFIG_SPARSEMEM_VMEMMAP
 620static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
 621                                                 unsigned long nr_pages)
 622{
 623        /* This will make the necessary allocations eventually. */
 624        return sparse_mem_map_populate(pnum, nid);
 625}
 626static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 627{
 628        return; /* XXX: Not implemented yet */
 629}
 630static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 631{
 632}
 633#else
 634static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
 635{
 636        struct page *page, *ret;
 637        unsigned long memmap_size = sizeof(struct page) * nr_pages;
 638
 639        page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
 640        if (page)
 641                goto got_map_page;
 642
 643        ret = vmalloc(memmap_size);
 644        if (ret)
 645                goto got_map_ptr;
 646
 647        return NULL;
 648got_map_page:
 649        ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
 650got_map_ptr:
 651        memset(ret, 0, memmap_size);
 652
 653        return ret;
 654}
 655
 656static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
 657                                                  unsigned long nr_pages)
 658{
 659        return __kmalloc_section_memmap(nr_pages);
 660}
 661
 662static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
 663{
 664        if (is_vmalloc_addr(memmap))
 665                vfree(memmap);
 666        else
 667                free_pages((unsigned long)memmap,
 668                           get_order(sizeof(struct page) * nr_pages));
 669}
 670
 671static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 672{
 673        unsigned long maps_section_nr, removing_section_nr, i;
 674        unsigned long magic;
 675
 676        for (i = 0; i < nr_pages; i++, page++) {
 677                magic = (unsigned long) page->lru.next;
 678
 679                BUG_ON(magic == NODE_INFO);
 680
 681                maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
 682                removing_section_nr = page->private;
 683
 684                /*
 685                 * When this function is called, the removing section is
 686                 * logical offlined state. This means all pages are isolated
 687                 * from page allocator. If removing section's memmap is placed
 688                 * on the same section, it must not be freed.
 689                 * If it is freed, page allocator may allocate it which will
 690                 * be removed physically soon.
 691                 */
 692                if (maps_section_nr != removing_section_nr)
 693                        put_page_bootmem(page);
 694        }
 695}
 696#endif /* CONFIG_SPARSEMEM_VMEMMAP */
 697
 698static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 699{
 700        struct page *usemap_page;
 701        unsigned long nr_pages;
 702
 703        if (!usemap)
 704                return;
 705
 706        usemap_page = virt_to_page(usemap);
 707        /*
 708         * Check to see if allocation came from hot-plug-add
 709         */
 710        if (PageSlab(usemap_page)) {
 711                kfree(usemap);
 712                if (memmap)
 713                        __kfree_section_memmap(memmap, PAGES_PER_SECTION);
 714                return;
 715        }
 716
 717        /*
 718         * The usemap came from bootmem. This is packed with other usemaps
 719         * on the section which has pgdat at boot time. Just keep it as is now.
 720         */
 721
 722        if (memmap) {
 723                struct page *memmap_page;
 724                memmap_page = virt_to_page(memmap);
 725
 726                nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
 727                        >> PAGE_SHIFT;
 728
 729                free_map_bootmem(memmap_page, nr_pages);
 730        }
 731}
 732
 733/*
 734 * returns the number of sections whose mem_maps were properly
 735 * set.  If this is <=0, then that means that the passed-in
 736 * map was not consumed and must be freed.
 737 */
 738int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 739                           int nr_pages)
 740{
 741        unsigned long section_nr = pfn_to_section_nr(start_pfn);
 742        struct pglist_data *pgdat = zone->zone_pgdat;
 743        struct mem_section *ms;
 744        struct page *memmap;
 745        unsigned long *usemap;
 746        unsigned long flags;
 747        int ret;
 748
 749        /*
 750         * no locking for this, because it does its own
 751         * plus, it does a kmalloc
 752         */
 753        ret = sparse_index_init(section_nr, pgdat->node_id);
 754        if (ret < 0 && ret != -EEXIST)
 755                return ret;
 756        memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, nr_pages);
 757        if (!memmap)
 758                return -ENOMEM;
 759        usemap = __kmalloc_section_usemap();
 760        if (!usemap) {
 761                __kfree_section_memmap(memmap, nr_pages);
 762                return -ENOMEM;
 763        }
 764
 765        pgdat_resize_lock(pgdat, &flags);
 766
 767        ms = __pfn_to_section(start_pfn);
 768        if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
 769                ret = -EEXIST;
 770                goto out;
 771        }
 772
 773        ms->section_mem_map |= SECTION_MARKED_PRESENT;
 774
 775        ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
 776
 777out:
 778        pgdat_resize_unlock(pgdat, &flags);
 779        if (ret <= 0) {
 780                kfree(usemap);
 781                __kfree_section_memmap(memmap, nr_pages);
 782        }
 783        return ret;
 784}
 785
 786void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 787{
 788        struct page *memmap = NULL;
 789        unsigned long *usemap = NULL;
 790
 791        if (ms->section_mem_map) {
 792                usemap = ms->pageblock_flags;
 793                memmap = sparse_decode_mem_map(ms->section_mem_map,
 794                                                __section_nr(ms));
 795                ms->section_mem_map = 0;
 796                ms->pageblock_flags = NULL;
 797        }
 798
 799        free_section_usemap(memmap, usemap);
 800}
 801#endif
 802
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