mm/sparse.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * sparse memory mappings.
   4  */
   5 #include <linux/mm.h>
   6 #include <linux/slab.h>
   7 #include <linux/mmzone.h>
   8 #include <linux/memblock.h>
   9 #include <linux/compiler.h>
  10 #include <linux/highmem.h>
  11 #include <linux/export.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/vmalloc.h>
  14 #include <linux/swap.h>
  15 #include <linux/swapops.h>
  16
  17 #include "internal.h"
  18 #include <asm/dma.h>
  19 #include <asm/pgalloc.h>
  20 #include <asm/pgtable.h>
  21
  22 /*
  23  * Permanent SPARSEMEM data:
  24  *
  25  * 1) mem_section       - memory sections, mem_map's for valid memory
  26  */
  27 #ifdef CONFIG_SPARSEMEM_EXTREME
  28 struct mem_section **mem_section;
  29 #else
  30 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
  31         ____cacheline_internodealigned_in_smp;
  32 #endif
  33 EXPORT_SYMBOL(mem_section);
  34
  35 #ifdef NODE_NOT_IN_PAGE_FLAGS
  36 /*
  37  * If we did not store the node number in the page then we have to
  38  * do a lookup in the section_to_node_table in order to find which
  39  * node the page belongs to.
  40  */
  41 #if MAX_NUMNODES <= 256
  42 static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  43 #else
  44 static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
  45 #endif
  46
  47 int page_to_nid(const struct page *page)
  48 {
  49         return section_to_node_table[page_to_section(page)];
  50 }
  51 EXPORT_SYMBOL(page_to_nid);
  52
  53 static void set_section_nid(unsigned long section_nr, int nid)
  54 {
  55         section_to_node_table[section_nr] = nid;
  56 }
  57 #else /* !NODE_NOT_IN_PAGE_FLAGS */
  58 static inline void set_section_nid(unsigned long section_nr, int nid)
  59 {
  60 }
  61 #endif
  62
  63 #ifdef CONFIG_SPARSEMEM_EXTREME
  64 static noinline struct mem_section __ref *sparse_index_alloc(int nid)
  65 {
  66         struct mem_section *section = NULL;
  67         unsigned long array_size = SECTIONS_PER_ROOT *
  68                                    sizeof(struct mem_section);
  69
  70         if (slab_is_available()) {
  71                 section = kzalloc_node(array_size, GFP_KERNEL, nid);
  72         } else {
  73                 section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
  74                                               nid);
  75                 if (!section)
  76                         panic("%s: Failed to allocate %lu bytes nid=%d\n",
  77                               __func__, array_size, nid);
  78         }
  79
  80         return section;
  81 }
  82
  83 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
  84 {
  85         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  86         struct mem_section *section;
  87
  88         /*
  89          * An existing section is possible in the sub-section hotplug
  90          * case. First hot-add instantiates, follow-on hot-add reuses
  91          * the existing section.
  92          *
  93          * The mem_hotplug_lock resolves the apparent race below.
  94          */
  95         if (mem_section[root])
  96                 return 0;
  97
  98         section = sparse_index_alloc(nid);
  99         if (!section)
 100                 return -ENOMEM;
 101
 102         mem_section[root] = section;
 103
 104         return 0;
 105 }
 106 #else /* !SPARSEMEM_EXTREME */
 107 static inline int sparse_index_init(unsigned long section_nr, int nid)
 108 {
 109         return 0;
 110 }
 111 #endif
 112
 113 #ifdef CONFIG_SPARSEMEM_EXTREME
 114 unsigned long __section_nr(struct mem_section *ms)
 115 {
 116         unsigned long root_nr;
 117         struct mem_section *root = NULL;
 118
 119         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 120                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 121                 if (!root)
 122                         continue;
 123
 124                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
 125                      break;
 126         }
 127
 128         VM_BUG_ON(!root);
 129
 130         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 131 }
 132 #else
 133 unsigned long __section_nr(struct mem_section *ms)
 134 {
 135         return (unsigned long)(ms - mem_section[0]);
 136 }
 137 #endif
 138
 139 /*
 140  * During early boot, before section_mem_map is used for an actual
 141  * mem_map, we use section_mem_map to store the section's NUMA
 142  * node.  This keeps us from having to use another data structure.  The
 143  * node information is cleared just before we store the real mem_map.
 144  */
 145 static inline unsigned long sparse_encode_early_nid(int nid)
 146 {
 147         return (nid << SECTION_NID_SHIFT);
 148 }
 149
 150 static inline int sparse_early_nid(struct mem_section *section)
 151 {
 152         return (section->section_mem_map >> SECTION_NID_SHIFT);
 153 }
 154
 155 /* Validate the physical addressing limitations of the model */
 156 void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
 157                                                 unsigned long *end_pfn)
 158 {
 159         unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
 160
 161         /*
 162          * Sanity checks - do not allow an architecture to pass
 163          * in larger pfns than the maximum scope of sparsemem:
 164          */
 165         if (*start_pfn > max_sparsemem_pfn) {
 166                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 167                         "Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 168                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 169                 WARN_ON_ONCE(1);
 170                 *start_pfn = max_sparsemem_pfn;
 171                 *end_pfn = max_sparsemem_pfn;
 172         } else if (*end_pfn > max_sparsemem_pfn) {
 173                 mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
 174                         "End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
 175                         *start_pfn, *end_pfn, max_sparsemem_pfn);
 176                 WARN_ON_ONCE(1);
 177                 *end_pfn = max_sparsemem_pfn;
 178         }
 179 }
 180
 181 /*
 182  * There are a number of times that we loop over NR_MEM_SECTIONS,
 183  * looking for section_present() on each.  But, when we have very
 184  * large physical address spaces, NR_MEM_SECTIONS can also be
 185  * very large which makes the loops quite long.
 186  *
 187  * Keeping track of this gives us an easy way to break out of
 188  * those loops early.
 189  */
 190 unsigned long __highest_present_section_nr;
 191 static void section_mark_present(struct mem_section *ms)
 192 {
 193         unsigned long section_nr = __section_nr(ms);
 194
 195         if (section_nr > __highest_present_section_nr)
 196                 __highest_present_section_nr = section_nr;
 197
 198         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 199 }
 200
 201 #define for_each_present_section_nr(start, section_nr)          \
 202         for (section_nr = next_present_section_nr(start-1);     \
 203              ((section_nr != -1) &&                             \
 204               (section_nr <= __highest_present_section_nr));    \
 205              section_nr = next_present_section_nr(section_nr))
 206
 207 static inline unsigned long first_present_section_nr(void)
 208 {
 209         return next_present_section_nr(-1);
 210 }
 211
 212 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 213 static void subsection_mask_set(unsigned long *map, unsigned long pfn,
 214                 unsigned long nr_pages)
 215 {
 216         int idx = subsection_map_index(pfn);
 217         int end = subsection_map_index(pfn + nr_pages - 1);
 218
 219         bitmap_set(map, idx, end - idx + 1);
 220 }
 221
 222 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
 223 {
 224         int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
 225         unsigned long nr, start_sec = pfn_to_section_nr(pfn);
 226
 227         if (!nr_pages)
 228                 return;
 229
 230         for (nr = start_sec; nr <= end_sec; nr++) {
 231                 struct mem_section *ms;
 232                 unsigned long pfns;
 233
 234                 pfns = min(nr_pages, PAGES_PER_SECTION
 235                                 - (pfn & ~PAGE_SECTION_MASK));
 236                 ms = __nr_to_section(nr);
 237                 subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
 238
 239                 pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
 240                                 pfns, subsection_map_index(pfn),
 241                                 subsection_map_index(pfn + pfns - 1));
 242
 243                 pfn += pfns;
 244                 nr_pages -= pfns;
 245         }
 246 }
 247 #else
 248 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
 249 {
 250 }
 251 #endif
 252
 253 /* Record a memory area against a node. */
 254 void __init memory_present(int nid, unsigned long start, unsigned long end)
 255 {
 256         unsigned long pfn;
 257
 258 #ifdef CONFIG_SPARSEMEM_EXTREME
 259         if (unlikely(!mem_section)) {
 260                 unsigned long size, align;
 261
 262                 size = sizeof(struct mem_section*) * NR_SECTION_ROOTS;
 263                 align = 1 << (INTERNODE_CACHE_SHIFT);
 264                 mem_section = memblock_alloc(size, align);
 265                 if (!mem_section)
 266                         panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 267                               __func__, size, align);
 268         }
 269 #endif
 270
 271         start &= PAGE_SECTION_MASK;
 272         mminit_validate_memmodel_limits(&start, &end);
 273         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
 274                 unsigned long section = pfn_to_section_nr(pfn);
 275                 struct mem_section *ms;
 276
 277                 sparse_index_init(section, nid);
 278                 set_section_nid(section, nid);
 279
 280                 ms = __nr_to_section(section);
 281                 if (!ms->section_mem_map) {
 282                         ms->section_mem_map = sparse_encode_early_nid(nid) |
 283                                                         SECTION_IS_ONLINE;
 284                         section_mark_present(ms);
 285                 }
 286         }
 287 }
 288
 289 /*
 290  * Mark all memblocks as present using memory_present(). This is a
 291  * convienence function that is useful for a number of arches
 292  * to mark all of the systems memory as present during initialization.
 293  */
 294 void __init memblocks_present(void)
 295 {
 296         struct memblock_region *reg;
 297
 298         for_each_memblock(memory, reg) {
 299                 memory_present(memblock_get_region_node(reg),
 300                                memblock_region_memory_base_pfn(reg),
 301                                memblock_region_memory_end_pfn(reg));
 302         }
 303 }
 304
 305 /*
 306  * Subtle, we encode the real pfn into the mem_map such that
 307  * the identity pfn - section_mem_map will return the actual
 308  * physical page frame number.
 309  */
 310 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
 311 {
 312         unsigned long coded_mem_map =
 313                 (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
 314         BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
 315         BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
 316         return coded_mem_map;
 317 }
 318
 319 /*
 320  * Decode mem_map from the coded memmap
 321  */
 322 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
 323 {
 324         /* mask off the extra low bits of information */
 325         coded_mem_map &= SECTION_MAP_MASK;
 326         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 327 }
 328
 329 static void __meminit sparse_init_one_section(struct mem_section *ms,
 330                 unsigned long pnum, struct page *mem_map,
 331                 struct mem_section_usage *usage, unsigned long flags)
 332 {
 333         ms->section_mem_map &= ~SECTION_MAP_MASK;
 334         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
 335                 | SECTION_HAS_MEM_MAP | flags;
 336         ms->usage = usage;
 337 }
 338
 339 static unsigned long usemap_size(void)
 340 {
 341         return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
 342 }
 343
 344 size_t mem_section_usage_size(void)
 345 {
 346         return sizeof(struct mem_section_usage) + usemap_size();
 347 }
 348
 349 #ifdef CONFIG_MEMORY_HOTREMOVE
 350 static struct mem_section_usage * __init
 351 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 352                                          unsigned long size)
 353 {
 354         struct mem_section_usage *usage;
 355         unsigned long goal, limit;
 356         int nid;
 357         /*
 358          * A page may contain usemaps for other sections preventing the
 359          * page being freed and making a section unremovable while
 360          * other sections referencing the usemap remain active. Similarly,
 361          * a pgdat can prevent a section being removed. If section A
 362          * contains a pgdat and section B contains the usemap, both
 363          * sections become inter-dependent. This allocates usemaps
 364          * from the same section as the pgdat where possible to avoid
 365          * this problem.
 366          */
 367         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
 368         limit = goal + (1UL << PA_SECTION_SHIFT);
 369         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
 370 again:
 371         usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
 372         if (!usage && limit) {
 373                 limit = 0;
 374                 goto again;
 375         }
 376         return usage;
 377 }
 378
 379 static void __init check_usemap_section_nr(int nid,
 380                 struct mem_section_usage *usage)
 381 {
 382         unsigned long usemap_snr, pgdat_snr;
 383         static unsigned long old_usemap_snr;
 384         static unsigned long old_pgdat_snr;
 385         struct pglist_data *pgdat = NODE_DATA(nid);
 386         int usemap_nid;
 387
 388         /* First call */
 389         if (!old_usemap_snr) {
 390                 old_usemap_snr = NR_MEM_SECTIONS;
 391                 old_pgdat_snr = NR_MEM_SECTIONS;
 392         }
 393
 394         usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
 395         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 396         if (usemap_snr == pgdat_snr)
 397                 return;
 398
 399         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
 400                 /* skip redundant message */
 401                 return;
 402
 403         old_usemap_snr = usemap_snr;
 404         old_pgdat_snr = pgdat_snr;
 405
 406         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
 407         if (usemap_nid != nid) {
 408                 pr_info("node %d must be removed before remove section %ld\n",
 409                         nid, usemap_snr);
 410                 return;
 411         }
 412         /*
 413          * There is a circular dependency.
 414          * Some platforms allow un-removable section because they will just
 415          * gather other removable sections for dynamic partitioning.
 416          * Just notify un-removable section's number here.
 417          */
 418         pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
 419                 usemap_snr, pgdat_snr, nid);
 420 }
 421 #else
 422 static struct mem_section_usage * __init
 423 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 424                                          unsigned long size)
 425 {
 426         return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
 427 }
 428
 429 static void __init check_usemap_section_nr(int nid,
 430                 struct mem_section_usage *usage)
 431 {
 432 }
 433 #endif /* CONFIG_MEMORY_HOTREMOVE */
 434
 435 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 436 static unsigned long __init section_map_size(void)
 437 {
 438         return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
 439 }
 440
 441 #else
 442 static unsigned long __init section_map_size(void)
 443 {
 444         return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
 445 }
 446
 447 struct page __init *__populate_section_memmap(unsigned long pfn,
 448                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 449 {
 450         unsigned long size = section_map_size();
 451         struct page *map = sparse_buffer_alloc(size);
 452         phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
 453
 454         if (map)
 455                 return map;
 456
 457         map = memblock_alloc_try_nid_raw(size, size, addr,
 458                                           MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 459         if (!map)
 460                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
 461                       __func__, size, PAGE_SIZE, nid, &addr);
 462
 463         return map;
 464 }
 465 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 466
 467 static void *sparsemap_buf __meminitdata;
 468 static void *sparsemap_buf_end __meminitdata;
 469
 470 static inline void __meminit sparse_buffer_free(unsigned long size)
 471 {
 472         WARN_ON(!sparsemap_buf || size == 0);
 473         memblock_free_early(__pa(sparsemap_buf), size);
 474 }
 475
 476 static void __init sparse_buffer_init(unsigned long size, int nid)
 477 {
 478         phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
 479         WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
 480         /*
 481          * Pre-allocated buffer is mainly used by __populate_section_memmap
 482          * and we want it to be properly aligned to the section size - this is
 483          * especially the case for VMEMMAP which maps memmap to PMDs
 484          */
 485         sparsemap_buf = memblock_alloc_exact_nid_raw(size, section_map_size(),
 486                                         addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 487         sparsemap_buf_end = sparsemap_buf + size;
 488 }
 489
 490 static void __init sparse_buffer_fini(void)
 491 {
 492         unsigned long size = sparsemap_buf_end - sparsemap_buf;
 493
 494         if (sparsemap_buf && size > 0)
 495                 sparse_buffer_free(size);
 496         sparsemap_buf = NULL;
 497 }
 498
 499 void * __meminit sparse_buffer_alloc(unsigned long size)
 500 {
 501         void *ptr = NULL;
 502
 503         if (sparsemap_buf) {
 504                 ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
 505                 if (ptr + size > sparsemap_buf_end)
 506                         ptr = NULL;
 507                 else {
 508                         /* Free redundant aligned space */
 509                         if ((unsigned long)(ptr - sparsemap_buf) > 0)
 510                                 sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
 511                         sparsemap_buf = ptr + size;
 512                 }
 513         }
 514         return ptr;
 515 }
 516
 517 void __weak __meminit vmemmap_populate_print_last(void)
 518 {
 519 }
 520
 521 /*
 522  * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
 523  * And number of present sections in this node is map_count.
 524  */
 525 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
 526                                    unsigned long pnum_end,
 527                                    unsigned long map_count)
 528 {
 529         struct mem_section_usage *usage;
 530         unsigned long pnum;
 531         struct page *map;
 532
 533         usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
 534                         mem_section_usage_size() * map_count);
 535         if (!usage) {
 536                 pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
 537                 goto failed;
 538         }
 539         sparse_buffer_init(map_count * section_map_size(), nid);
 540         for_each_present_section_nr(pnum_begin, pnum) {
 541                 unsigned long pfn = section_nr_to_pfn(pnum);
 542
 543                 if (pnum >= pnum_end)
 544                         break;
 545
 546                 map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
 547                                 nid, NULL);
 548                 if (!map) {
 549                         pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
 550                                __func__, nid);
 551                         pnum_begin = pnum;
 552                         goto failed;
 553                 }
 554                 check_usemap_section_nr(nid, usage);
 555                 sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
 556                                 SECTION_IS_EARLY);
 557                 usage = (void *) usage + mem_section_usage_size();
 558         }
 559         sparse_buffer_fini();
 560         return;
 561 failed:
 562         /* We failed to allocate, mark all the following pnums as not present */
 563         for_each_present_section_nr(pnum_begin, pnum) {
 564                 struct mem_section *ms;
 565
 566                 if (pnum >= pnum_end)
 567                         break;
 568                 ms = __nr_to_section(pnum);
 569                 ms->section_mem_map = 0;
 570         }
 571 }
 572
 573 /*
 574  * Allocate the accumulated non-linear sections, allocate a mem_map
 575  * for each and record the physical to section mapping.
 576  */
 577 void __init sparse_init(void)
 578 {
 579         unsigned long pnum_begin = first_present_section_nr();
 580         int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
 581         unsigned long pnum_end, map_count = 1;
 582
 583         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
 584         set_pageblock_order();
 585
 586         for_each_present_section_nr(pnum_begin + 1, pnum_end) {
 587                 int nid = sparse_early_nid(__nr_to_section(pnum_end));
 588
 589                 if (nid == nid_begin) {
 590                         map_count++;
 591                         continue;
 592                 }
 593                 /* Init node with sections in range [pnum_begin, pnum_end) */
 594                 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
 595                 nid_begin = nid;
 596                 pnum_begin = pnum_end;
 597                 map_count = 1;
 598         }
 599         /* cover the last node */
 600         sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
 601         vmemmap_populate_print_last();
 602 }
 603
 604 #ifdef CONFIG_MEMORY_HOTPLUG
 605
 606 /* Mark all memory sections within the pfn range as online */
 607 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 608 {
 609         unsigned long pfn;
 610
 611         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 612                 unsigned long section_nr = pfn_to_section_nr(pfn);
 613                 struct mem_section *ms;
 614
 615                 /* onlining code should never touch invalid ranges */
 616                 if (WARN_ON(!valid_section_nr(section_nr)))
 617                         continue;
 618
 619                 ms = __nr_to_section(section_nr);
 620                 ms->section_mem_map |= SECTION_IS_ONLINE;
 621         }
 622 }
 623
 624 #ifdef CONFIG_MEMORY_HOTREMOVE
 625 /* Mark all memory sections within the pfn range as offline */
 626 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 627 {
 628         unsigned long pfn;
 629
 630         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 631                 unsigned long section_nr = pfn_to_section_nr(pfn);
 632                 struct mem_section *ms;
 633
 634                 /*
 635                  * TODO this needs some double checking. Offlining code makes
 636                  * sure to check pfn_valid but those checks might be just bogus
 637                  */
 638                 if (WARN_ON(!valid_section_nr(section_nr)))
 639                         continue;
 640
 641                 ms = __nr_to_section(section_nr);
 642                 ms->section_mem_map &= ~SECTION_IS_ONLINE;
 643         }
 644 }
 645 #endif
 646
 647 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 648 static struct page * __meminit populate_section_memmap(unsigned long pfn,
 649                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 650 {
 651         return __populate_section_memmap(pfn, nr_pages, nid, altmap);
 652 }
 653
 654 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 655                 struct vmem_altmap *altmap)
 656 {
 657         unsigned long start = (unsigned long) pfn_to_page(pfn);
 658         unsigned long end = start + nr_pages * sizeof(struct page);
 659
 660         vmemmap_free(start, end, altmap);
 661 }
 662 static void free_map_bootmem(struct page *memmap)
 663 {
 664         unsigned long start = (unsigned long)memmap;
 665         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
 666
 667         vmemmap_free(start, end, NULL);
 668 }
 669
 670 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
 671 {
 672         DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 673         DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
 674         struct mem_section *ms = __pfn_to_section(pfn);
 675         unsigned long *subsection_map = ms->usage
 676                 ? &ms->usage->subsection_map[0] : NULL;
 677
 678         subsection_mask_set(map, pfn, nr_pages);
 679         if (subsection_map)
 680                 bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
 681
 682         if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
 683                                 "section already deactivated (%#lx + %ld)\n",
 684                                 pfn, nr_pages))
 685                 return -EINVAL;
 686
 687         bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
 688         return 0;
 689 }
 690
 691 static bool is_subsection_map_empty(struct mem_section *ms)
 692 {
 693         return bitmap_empty(&ms->usage->subsection_map[0],
 694                             SUBSECTIONS_PER_SECTION);
 695 }
 696
 697 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 698 {
 699         struct mem_section *ms = __pfn_to_section(pfn);
 700         DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 701         unsigned long *subsection_map;
 702         int rc = 0;
 703
 704         subsection_mask_set(map, pfn, nr_pages);
 705
 706         subsection_map = &ms->usage->subsection_map[0];
 707
 708         if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
 709                 rc = -EINVAL;
 710         else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
 711                 rc = -EEXIST;
 712         else
 713                 bitmap_or(subsection_map, map, subsection_map,
 714                                 SUBSECTIONS_PER_SECTION);
 715
 716         return rc;
 717 }
 718 #else
 719 struct page * __meminit populate_section_memmap(unsigned long pfn,
 720                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 721 {
 722         return kvmalloc_node(array_size(sizeof(struct page),
 723                                         PAGES_PER_SECTION), GFP_KERNEL, nid);
 724 }
 725
 726 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 727                 struct vmem_altmap *altmap)
 728 {
 729         kvfree(pfn_to_page(pfn));
 730 }
 731
 732 static void free_map_bootmem(struct page *memmap)
 733 {
 734         unsigned long maps_section_nr, removing_section_nr, i;
 735         unsigned long magic, nr_pages;
 736         struct page *page = virt_to_page(memmap);
 737
 738         nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
 739                 >> PAGE_SHIFT;
 740
 741         for (i = 0; i < nr_pages; i++, page++) {
 742                 magic = (unsigned long) page->freelist;
 743
 744                 BUG_ON(magic == NODE_INFO);
 745
 746                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
 747                 removing_section_nr = page_private(page);
 748
 749                 /*
 750                  * When this function is called, the removing section is
 751                  * logical offlined state. This means all pages are isolated
 752                  * from page allocator. If removing section's memmap is placed
 753                  * on the same section, it must not be freed.
 754                  * If it is freed, page allocator may allocate it which will
 755                  * be removed physically soon.
 756                  */
 757                 if (maps_section_nr != removing_section_nr)
 758                         put_page_bootmem(page);
 759         }
 760 }
 761
 762 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
 763 {
 764         return 0;
 765 }
 766
 767 static bool is_subsection_map_empty(struct mem_section *ms)
 768 {
 769         return true;
 770 }
 771
 772 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 773 {
 774         return 0;
 775 }
 776 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 777
 778 /*
 779  * To deactivate a memory region, there are 3 cases to handle across
 780  * two configurations (SPARSEMEM_VMEMMAP={y,n}):
 781  *
 782  * 1. deactivation of a partial hot-added section (only possible in
 783  *    the SPARSEMEM_VMEMMAP=y case).
 784  *      a) section was present at memory init.
 785  *      b) section was hot-added post memory init.
 786  * 2. deactivation of a complete hot-added section.
 787  * 3. deactivation of a complete section from memory init.
 788  *
 789  * For 1, when subsection_map does not empty we will not be freeing the
 790  * usage map, but still need to free the vmemmap range.
 791  *
 792  * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
 793  */
 794 static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
 795                 struct vmem_altmap *altmap)
 796 {
 797         struct mem_section *ms = __pfn_to_section(pfn);
 798         bool section_is_early = early_section(ms);
 799         struct page *memmap = NULL;
 800         bool empty;
 801
 802         if (clear_subsection_map(pfn, nr_pages))
 803                 return;
 804
 805         empty = is_subsection_map_empty(ms);
 806         if (empty) {
 807                 unsigned long section_nr = pfn_to_section_nr(pfn);
 808
 809                 /*
 810                  * When removing an early section, the usage map is kept (as the
 811                  * usage maps of other sections fall into the same page). It
 812                  * will be re-used when re-adding the section - which is then no
 813                  * longer an early section. If the usage map is PageReserved, it
 814                  * was allocated during boot.
 815                  */
 816                 if (!PageReserved(virt_to_page(ms->usage))) {
 817                         kfree(ms->usage);
 818                         ms->usage = NULL;
 819                 }
 820                 memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 821                 /*
 822                  * Mark the section invalid so that valid_section()
 823                  * return false. This prevents code from dereferencing
 824                  * ms->usage array.
 825                  */
 826                 ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
 827         }
 828
 829         if (section_is_early && memmap)
 830                 free_map_bootmem(memmap);
 831         else
 832                 depopulate_section_memmap(pfn, nr_pages, altmap);
 833
 834         if (empty)
 835                 ms->section_mem_map = (unsigned long)NULL;
 836 }
 837
 838 static struct page * __meminit section_activate(int nid, unsigned long pfn,
 839                 unsigned long nr_pages, struct vmem_altmap *altmap)
 840 {
 841         struct mem_section *ms = __pfn_to_section(pfn);
 842         struct mem_section_usage *usage = NULL;
 843         struct page *memmap;
 844         int rc = 0;
 845
 846         if (!ms->usage) {
 847                 usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
 848                 if (!usage)
 849                         return ERR_PTR(-ENOMEM);
 850                 ms->usage = usage;
 851         }
 852
 853         rc = fill_subsection_map(pfn, nr_pages);
 854         if (rc) {
 855                 if (usage)
 856                         ms->usage = NULL;
 857                 kfree(usage);
 858                 return ERR_PTR(rc);
 859         }
 860
 861         /*
 862          * The early init code does not consider partially populated
 863          * initial sections, it simply assumes that memory will never be
 864          * referenced.  If we hot-add memory into such a section then we
 865          * do not need to populate the memmap and can simply reuse what
 866          * is already there.
 867          */
 868         if (nr_pages < PAGES_PER_SECTION && early_section(ms))
 869                 return pfn_to_page(pfn);
 870
 871         memmap = populate_section_memmap(pfn, nr_pages, nid, altmap);
 872         if (!memmap) {
 873                 section_deactivate(pfn, nr_pages, altmap);
 874                 return ERR_PTR(-ENOMEM);
 875         }
 876
 877         return memmap;
 878 }
 879
 880 /**
 881  * sparse_add_section - add a memory section, or populate an existing one
 882  * @nid: The node to add section on
 883  * @start_pfn: start pfn of the memory range
 884  * @nr_pages: number of pfns to add in the section
 885  * @altmap: device page map
 886  *
 887  * This is only intended for hotplug.
 888  *
 889  * Note that only VMEMMAP supports sub-section aligned hotplug,
 890  * the proper alignment and size are gated by check_pfn_span().
 891  *
 892  *
 893  * Return:
 894  * * 0          - On success.
 895  * * -EEXIST    - Section has been present.
 896  * * -ENOMEM    - Out of memory.
 897  */
 898 int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 899                 unsigned long nr_pages, struct vmem_altmap *altmap)
 900 {
 901         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 902         struct mem_section *ms;
 903         struct page *memmap;
 904         int ret;
 905
 906         ret = sparse_index_init(section_nr, nid);
 907         if (ret < 0)
 908                 return ret;
 909
 910         memmap = section_activate(nid, start_pfn, nr_pages, altmap);
 911         if (IS_ERR(memmap))
 912                 return PTR_ERR(memmap);
 913
 914         /*
 915          * Poison uninitialized struct pages in order to catch invalid flags
 916          * combinations.
 917          */
 918         page_init_poison(memmap, sizeof(struct page) * nr_pages);
 919
 920         ms = __nr_to_section(section_nr);
 921         set_section_nid(section_nr, nid);
 922         section_mark_present(ms);
 923
 924         /* Align memmap to section boundary in the subsection case */
 925         if (section_nr_to_pfn(section_nr) != start_pfn)
 926                 memmap = pfn_to_page(section_nr_to_pfn(section_nr));
 927         sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
 928
 929         return 0;
 930 }
 931
 932 #ifdef CONFIG_MEMORY_FAILURE
 933 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 934 {
 935         int i;
 936
 937         /*
 938          * A further optimization is to have per section refcounted
 939          * num_poisoned_pages.  But that would need more space per memmap, so
 940          * for now just do a quick global check to speed up this routine in the
 941          * absence of bad pages.
 942          */
 943         if (atomic_long_read(&num_poisoned_pages) == 0)
 944                 return;
 945
 946         for (i = 0; i < nr_pages; i++) {
 947                 if (PageHWPoison(&memmap[i])) {
 948                         num_poisoned_pages_dec();
 949                         ClearPageHWPoison(&memmap[i]);
 950                 }
 951         }
 952 }
 953 #else
 954 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 955 {
 956 }
 957 #endif
 958
 959 void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
 960                 unsigned long nr_pages, unsigned long map_offset,
 961                 struct vmem_altmap *altmap)
 962 {
 963         clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
 964                         nr_pages - map_offset);
 965         section_deactivate(pfn, nr_pages, altmap);
 966 }
 967 #endif /* CONFIG_MEMORY_HOTPLUG */