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