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
  20 /*
  21  * Permanent SPARSEMEM data:
  22  *
  23  * 1) mem_section       - memory sections, mem_map's for valid memory
  24  */
  25 #ifdef CONFIG_SPARSEMEM_EXTREME
  26 struct mem_section **mem_section;
  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                 section = kzalloc_node(array_size, GFP_KERNEL, nid);
  70         } else {
  71                 section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
  72                                               nid);
  73                 if (!section)
  74                         panic("%s: Failed to allocate %lu bytes nid=%d\n",
  75                               __func__, array_size, nid);
  76         }
  77
  78         return section;
  79 }
  80
  81 static int __meminit sparse_index_init(unsigned long section_nr, int nid)
  82 {
  83         unsigned long root = SECTION_NR_TO_ROOT(section_nr);
  84         struct mem_section *section;
  85
  86         /*
  87          * An existing section is possible in the sub-section hotplug
  88          * case. First hot-add instantiates, follow-on hot-add reuses
  89          * the existing section.
  90          *
  91          * The mem_hotplug_lock resolves the apparent race below.
  92          */
  93         if (mem_section[root])
  94                 return 0;
  95
  96         section = sparse_index_alloc(nid);
  97         if (!section)
  98                 return -ENOMEM;
  99
 100         mem_section[root] = section;
 101
 102         return 0;
 103 }
 104 #else /* !SPARSEMEM_EXTREME */
 105 static inline int sparse_index_init(unsigned long section_nr, int nid)
 106 {
 107         return 0;
 108 }
 109 #endif
 110
 111 #ifdef CONFIG_SPARSEMEM_EXTREME
 112 unsigned long __section_nr(struct mem_section *ms)
 113 {
 114         unsigned long root_nr;
 115         struct mem_section *root = NULL;
 116
 117         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 118                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 119                 if (!root)
 120                         continue;
 121
 122                 if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
 123                      break;
 124         }
 125
 126         VM_BUG_ON(!root);
 127
 128         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 129 }
 130 #else
 131 unsigned long __section_nr(struct mem_section *ms)
 132 {
 133         return (unsigned long)(ms - mem_section[0]);
 134 }
 135 #endif
 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  */
 143 static inline unsigned long sparse_encode_early_nid(int nid)
 144 {
 145         return (nid << SECTION_NID_SHIFT);
 146 }
 147
 148 static 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 */
 154 void __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 /*
 180  * There are a number of times that we loop over NR_MEM_SECTIONS,
 181  * looking for section_present() on each.  But, when we have very
 182  * large physical address spaces, NR_MEM_SECTIONS can also be
 183  * very large which makes the loops quite long.
 184  *
 185  * Keeping track of this gives us an easy way to break out of
 186  * those loops early.
 187  */
 188 unsigned long __highest_present_section_nr;
 189 static void section_mark_present(struct mem_section *ms)
 190 {
 191         unsigned long section_nr = __section_nr(ms);
 192
 193         if (section_nr > __highest_present_section_nr)
 194                 __highest_present_section_nr = section_nr;
 195
 196         ms->section_mem_map |= SECTION_MARKED_PRESENT;
 197 }
 198
 199 #define for_each_present_section_nr(start, section_nr)          \
 200         for (section_nr = next_present_section_nr(start-1);     \
 201              ((section_nr != -1) &&                             \
 202               (section_nr <= __highest_present_section_nr));    \
 203              section_nr = next_present_section_nr(section_nr))
 204
 205 static inline unsigned long first_present_section_nr(void)
 206 {
 207         return next_present_section_nr(-1);
 208 }
 209
 210 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 211 static void subsection_mask_set(unsigned long *map, unsigned long pfn,
 212                 unsigned long nr_pages)
 213 {
 214         int idx = subsection_map_index(pfn);
 215         int end = subsection_map_index(pfn + nr_pages - 1);
 216
 217         bitmap_set(map, idx, end - idx + 1);
 218 }
 219
 220 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
 221 {
 222         int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
 223         unsigned long nr, start_sec = pfn_to_section_nr(pfn);
 224
 225         if (!nr_pages)
 226                 return;
 227
 228         for (nr = start_sec; nr <= end_sec; nr++) {
 229                 struct mem_section *ms;
 230                 unsigned long pfns;
 231
 232                 pfns = min(nr_pages, PAGES_PER_SECTION
 233                                 - (pfn & ~PAGE_SECTION_MASK));
 234                 ms = __nr_to_section(nr);
 235                 subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
 236
 237                 pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
 238                                 pfns, subsection_map_index(pfn),
 239                                 subsection_map_index(pfn + pfns - 1));
 240
 241                 pfn += pfns;
 242                 nr_pages -= pfns;
 243         }
 244 }
 245 #else
 246 void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
 247 {
 248 }
 249 #endif
 250
 251 /* Record a memory area against a node. */
 252 void __init memory_present(int nid, unsigned long start, unsigned long end)
 253 {
 254         unsigned long pfn;
 255
 256 #ifdef CONFIG_SPARSEMEM_EXTREME
 257         if (unlikely(!mem_section)) {
 258                 unsigned long size, align;
 259
 260                 size = sizeof(struct mem_section*) * NR_SECTION_ROOTS;
 261                 align = 1 << (INTERNODE_CACHE_SHIFT);
 262                 mem_section = memblock_alloc(size, align);
 263                 if (!mem_section)
 264                         panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 265                               __func__, size, align);
 266         }
 267 #endif
 268
 269         start &= PAGE_SECTION_MASK;
 270         mminit_validate_memmodel_limits(&start, &end);
 271         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
 272                 unsigned long section = pfn_to_section_nr(pfn);
 273                 struct mem_section *ms;
 274
 275                 sparse_index_init(section, nid);
 276                 set_section_nid(section, nid);
 277
 278                 ms = __nr_to_section(section);
 279                 if (!ms->section_mem_map) {
 280                         ms->section_mem_map = sparse_encode_early_nid(nid) |
 281                                                         SECTION_IS_ONLINE;
 282                         section_mark_present(ms);
 283                 }
 284         }
 285 }
 286
 287 /*
 288  * Mark all memblocks as present using memory_present(). This is a
 289  * convenience function that is useful for a number of arches
 290  * to mark all of the systems memory as present during initialization.
 291  */
 292 void __init memblocks_present(void)
 293 {
 294         struct memblock_region *reg;
 295
 296         for_each_memblock(memory, reg) {
 297                 memory_present(memblock_get_region_node(reg),
 298                                memblock_region_memory_base_pfn(reg),
 299                                memblock_region_memory_end_pfn(reg));
 300         }
 301 }
 302
 303 /*
 304  * Subtle, we encode the real pfn into the mem_map such that
 305  * the identity pfn - section_mem_map will return the actual
 306  * physical page frame number.
 307  */
 308 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
 309 {
 310         unsigned long coded_mem_map =
 311                 (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
 312         BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
 313         BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
 314         return coded_mem_map;
 315 }
 316
 317 /*
 318  * Decode mem_map from the coded memmap
 319  */
 320 struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
 321 {
 322         /* mask off the extra low bits of information */
 323         coded_mem_map &= SECTION_MAP_MASK;
 324         return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 325 }
 326
 327 static void __meminit sparse_init_one_section(struct mem_section *ms,
 328                 unsigned long pnum, struct page *mem_map,
 329                 struct mem_section_usage *usage, unsigned long flags)
 330 {
 331         ms->section_mem_map &= ~SECTION_MAP_MASK;
 332         ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
 333                 | SECTION_HAS_MEM_MAP | flags;
 334         ms->usage = usage;
 335 }
 336
 337 static unsigned long usemap_size(void)
 338 {
 339         return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
 340 }
 341
 342 size_t mem_section_usage_size(void)
 343 {
 344         return sizeof(struct mem_section_usage) + usemap_size();
 345 }
 346
 347 #ifdef CONFIG_MEMORY_HOTREMOVE
 348 static struct mem_section_usage * __init
 349 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 350                                          unsigned long size)
 351 {
 352         struct mem_section_usage *usage;
 353         unsigned long goal, limit;
 354         int nid;
 355         /*
 356          * A page may contain usemaps for other sections preventing the
 357          * page being freed and making a section unremovable while
 358          * other sections referencing the usemap remain active. Similarly,
 359          * a pgdat can prevent a section being removed. If section A
 360          * contains a pgdat and section B contains the usemap, both
 361          * sections become inter-dependent. This allocates usemaps
 362          * from the same section as the pgdat where possible to avoid
 363          * this problem.
 364          */
 365         goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
 366         limit = goal + (1UL << PA_SECTION_SHIFT);
 367         nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
 368 again:
 369         usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
 370         if (!usage && limit) {
 371                 limit = 0;
 372                 goto again;
 373         }
 374         return usage;
 375 }
 376
 377 static void __init check_usemap_section_nr(int nid,
 378                 struct mem_section_usage *usage)
 379 {
 380         unsigned long usemap_snr, pgdat_snr;
 381         static unsigned long old_usemap_snr;
 382         static unsigned long old_pgdat_snr;
 383         struct pglist_data *pgdat = NODE_DATA(nid);
 384         int usemap_nid;
 385
 386         /* First call */
 387         if (!old_usemap_snr) {
 388                 old_usemap_snr = NR_MEM_SECTIONS;
 389                 old_pgdat_snr = NR_MEM_SECTIONS;
 390         }
 391
 392         usemap_snr = pfn_to_section_nr(__pa(usage) >> PAGE_SHIFT);
 393         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 394         if (usemap_snr == pgdat_snr)
 395                 return;
 396
 397         if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
 398                 /* skip redundant message */
 399                 return;
 400
 401         old_usemap_snr = usemap_snr;
 402         old_pgdat_snr = pgdat_snr;
 403
 404         usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
 405         if (usemap_nid != nid) {
 406                 pr_info("node %d must be removed before remove section %ld\n",
 407                         nid, usemap_snr);
 408                 return;
 409         }
 410         /*
 411          * There is a circular dependency.
 412          * Some platforms allow un-removable section because they will just
 413          * gather other removable sections for dynamic partitioning.
 414          * Just notify un-removable section's number here.
 415          */
 416         pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
 417                 usemap_snr, pgdat_snr, nid);
 418 }
 419 #else
 420 static struct mem_section_usage * __init
 421 sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 422                                          unsigned long size)
 423 {
 424         return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
 425 }
 426
 427 static void __init check_usemap_section_nr(int nid,
 428                 struct mem_section_usage *usage)
 429 {
 430 }
 431 #endif /* CONFIG_MEMORY_HOTREMOVE */
 432
 433 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 434 static unsigned long __init section_map_size(void)
 435 {
 436         return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
 437 }
 438
 439 #else
 440 static unsigned long __init section_map_size(void)
 441 {
 442         return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
 443 }
 444
 445 struct page __init *__populate_section_memmap(unsigned long pfn,
 446                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 447 {
 448         unsigned long size = section_map_size();
 449         struct page *map = sparse_buffer_alloc(size);
 450         phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
 451
 452         if (map)
 453                 return map;
 454
 455         map = memblock_alloc_try_nid_raw(size, size, addr,
 456                                           MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 457         if (!map)
 458                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
 459                       __func__, size, PAGE_SIZE, nid, &addr);
 460
 461         return map;
 462 }
 463 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 464
 465 static void *sparsemap_buf __meminitdata;
 466 static void *sparsemap_buf_end __meminitdata;
 467
 468 static inline void __meminit sparse_buffer_free(unsigned long size)
 469 {
 470         WARN_ON(!sparsemap_buf || size == 0);
 471         memblock_free_early(__pa(sparsemap_buf), size);
 472 }
 473
 474 static void __init sparse_buffer_init(unsigned long size, int nid)
 475 {
 476         phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
 477         WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
 478         /*
 479          * Pre-allocated buffer is mainly used by __populate_section_memmap
 480          * and we want it to be properly aligned to the section size - this is
 481          * especially the case for VMEMMAP which maps memmap to PMDs
 482          */
 483         sparsemap_buf = memblock_alloc_exact_nid_raw(size, section_map_size(),
 484                                         addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
 485         sparsemap_buf_end = sparsemap_buf + size;
 486 }
 487
 488 static void __init sparse_buffer_fini(void)
 489 {
 490         unsigned long size = sparsemap_buf_end - sparsemap_buf;
 491
 492         if (sparsemap_buf && size > 0)
 493                 sparse_buffer_free(size);
 494         sparsemap_buf = NULL;
 495 }
 496
 497 void * __meminit sparse_buffer_alloc(unsigned long size)
 498 {
 499         void *ptr = NULL;
 500
 501         if (sparsemap_buf) {
 502                 ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
 503                 if (ptr + size > sparsemap_buf_end)
 504                         ptr = NULL;
 505                 else {
 506                         /* Free redundant aligned space */
 507                         if ((unsigned long)(ptr - sparsemap_buf) > 0)
 508                                 sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
 509                         sparsemap_buf = ptr + size;
 510                 }
 511         }
 512         return ptr;
 513 }
 514
 515 void __weak __meminit vmemmap_populate_print_last(void)
 516 {
 517 }
 518
 519 /*
 520  * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
 521  * And number of present sections in this node is map_count.
 522  */
 523 static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
 524                                    unsigned long pnum_end,
 525                                    unsigned long map_count)
 526 {
 527         struct mem_section_usage *usage;
 528         unsigned long pnum;
 529         struct page *map;
 530
 531         usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
 532                         mem_section_usage_size() * map_count);
 533         if (!usage) {
 534                 pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
 535                 goto failed;
 536         }
 537         sparse_buffer_init(map_count * section_map_size(), nid);
 538         for_each_present_section_nr(pnum_begin, pnum) {
 539                 unsigned long pfn = section_nr_to_pfn(pnum);
 540
 541                 if (pnum >= pnum_end)
 542                         break;
 543
 544                 map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
 545                                 nid, NULL);
 546                 if (!map) {
 547                         pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
 548                                __func__, nid);
 549                         pnum_begin = pnum;
 550                         goto failed;
 551                 }
 552                 check_usemap_section_nr(nid, usage);
 553                 sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
 554                                 SECTION_IS_EARLY);
 555                 usage = (void *) usage + mem_section_usage_size();
 556         }
 557         sparse_buffer_fini();
 558         return;
 559 failed:
 560         /* We failed to allocate, mark all the following pnums as not present */
 561         for_each_present_section_nr(pnum_begin, pnum) {
 562                 struct mem_section *ms;
 563
 564                 if (pnum >= pnum_end)
 565                         break;
 566                 ms = __nr_to_section(pnum);
 567                 ms->section_mem_map = 0;
 568         }
 569 }
 570
 571 /*
 572  * Allocate the accumulated non-linear sections, allocate a mem_map
 573  * for each and record the physical to section mapping.
 574  */
 575 void __init sparse_init(void)
 576 {
 577         unsigned long pnum_begin = first_present_section_nr();
 578         int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
 579         unsigned long pnum_end, map_count = 1;
 580
 581         /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
 582         set_pageblock_order();
 583
 584         for_each_present_section_nr(pnum_begin + 1, pnum_end) {
 585                 int nid = sparse_early_nid(__nr_to_section(pnum_end));
 586
 587                 if (nid == nid_begin) {
 588                         map_count++;
 589                         continue;
 590                 }
 591                 /* Init node with sections in range [pnum_begin, pnum_end) */
 592                 sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
 593                 nid_begin = nid;
 594                 pnum_begin = pnum_end;
 595                 map_count = 1;
 596         }
 597         /* cover the last node */
 598         sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
 599         vmemmap_populate_print_last();
 600 }
 601
 602 #ifdef CONFIG_MEMORY_HOTPLUG
 603
 604 /* Mark all memory sections within the pfn range as online */
 605 void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 606 {
 607         unsigned long pfn;
 608
 609         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 610                 unsigned long section_nr = pfn_to_section_nr(pfn);
 611                 struct mem_section *ms;
 612
 613                 /* onlining code should never touch invalid ranges */
 614                 if (WARN_ON(!valid_section_nr(section_nr)))
 615                         continue;
 616
 617                 ms = __nr_to_section(section_nr);
 618                 ms->section_mem_map |= SECTION_IS_ONLINE;
 619         }
 620 }
 621
 622 #ifdef CONFIG_MEMORY_HOTREMOVE
 623 /* Mark all memory sections within the pfn range as offline */
 624 void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 625 {
 626         unsigned long pfn;
 627
 628         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 629                 unsigned long section_nr = pfn_to_section_nr(pfn);
 630                 struct mem_section *ms;
 631
 632                 /*
 633                  * TODO this needs some double checking. Offlining code makes
 634                  * sure to check pfn_valid but those checks might be just bogus
 635                  */
 636                 if (WARN_ON(!valid_section_nr(section_nr)))
 637                         continue;
 638
 639                 ms = __nr_to_section(section_nr);
 640                 ms->section_mem_map &= ~SECTION_IS_ONLINE;
 641         }
 642 }
 643 #endif
 644
 645 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 646 static struct page * __meminit populate_section_memmap(unsigned long pfn,
 647                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 648 {
 649         return __populate_section_memmap(pfn, nr_pages, nid, altmap);
 650 }
 651
 652 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 653                 struct vmem_altmap *altmap)
 654 {
 655         unsigned long start = (unsigned long) pfn_to_page(pfn);
 656         unsigned long end = start + nr_pages * sizeof(struct page);
 657
 658         vmemmap_free(start, end, altmap);
 659 }
 660 static void free_map_bootmem(struct page *memmap)
 661 {
 662         unsigned long start = (unsigned long)memmap;
 663         unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
 664
 665         vmemmap_free(start, end, NULL);
 666 }
 667
 668 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
 669 {
 670         DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 671         DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
 672         struct mem_section *ms = __pfn_to_section(pfn);
 673         unsigned long *subsection_map = ms->usage
 674                 ? &ms->usage->subsection_map[0] : NULL;
 675
 676         subsection_mask_set(map, pfn, nr_pages);
 677         if (subsection_map)
 678                 bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
 679
 680         if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
 681                                 "section already deactivated (%#lx + %ld)\n",
 682                                 pfn, nr_pages))
 683                 return -EINVAL;
 684
 685         bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
 686         return 0;
 687 }
 688
 689 static bool is_subsection_map_empty(struct mem_section *ms)
 690 {
 691         return bitmap_empty(&ms->usage->subsection_map[0],
 692                             SUBSECTIONS_PER_SECTION);
 693 }
 694
 695 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 696 {
 697         struct mem_section *ms = __pfn_to_section(pfn);
 698         DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 699         unsigned long *subsection_map;
 700         int rc = 0;
 701
 702         subsection_mask_set(map, pfn, nr_pages);
 703
 704         subsection_map = &ms->usage->subsection_map[0];
 705
 706         if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
 707                 rc = -EINVAL;
 708         else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
 709                 rc = -EEXIST;
 710         else
 711                 bitmap_or(subsection_map, map, subsection_map,
 712                                 SUBSECTIONS_PER_SECTION);
 713
 714         return rc;
 715 }
 716 #else
 717 struct page * __meminit populate_section_memmap(unsigned long pfn,
 718                 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 719 {
 720         return kvmalloc_node(array_size(sizeof(struct page),
 721                                         PAGES_PER_SECTION), GFP_KERNEL, nid);
 722 }
 723
 724 static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 725                 struct vmem_altmap *altmap)
 726 {
 727         kvfree(pfn_to_page(pfn));
 728 }
 729
 730 static void free_map_bootmem(struct page *memmap)
 731 {
 732         unsigned long maps_section_nr, removing_section_nr, i;
 733         unsigned long magic, nr_pages;
 734         struct page *page = virt_to_page(memmap);
 735
 736         nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
 737                 >> PAGE_SHIFT;
 738
 739         for (i = 0; i < nr_pages; i++, page++) {
 740                 magic = (unsigned long) page->freelist;
 741
 742                 BUG_ON(magic == NODE_INFO);
 743
 744                 maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
 745                 removing_section_nr = page_private(page);
 746
 747                 /*
 748                  * When this function is called, the removing section is
 749                  * logical offlined state. This means all pages are isolated
 750                  * from page allocator. If removing section's memmap is placed
 751                  * on the same section, it must not be freed.
 752                  * If it is freed, page allocator may allocate it which will
 753                  * be removed physically soon.
 754                  */
 755                 if (maps_section_nr != removing_section_nr)
 756                         put_page_bootmem(page);
 757         }
 758 }
 759
 760 static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
 761 {
 762         return 0;
 763 }
 764
 765 static bool is_subsection_map_empty(struct mem_section *ms)
 766 {
 767         return true;
 768 }
 769
 770 static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 771 {
 772         return 0;
 773 }
 774 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 775
 776 /*
 777  * To deactivate a memory region, there are 3 cases to handle across
 778  * two configurations (SPARSEMEM_VMEMMAP={y,n}):
 779  *
 780  * 1. deactivation of a partial hot-added section (only possible in
 781  *    the SPARSEMEM_VMEMMAP=y case).
 782  *      a) section was present at memory init.
 783  *      b) section was hot-added post memory init.
 784  * 2. deactivation of a complete hot-added section.
 785  * 3. deactivation of a complete section from memory init.
 786  *
 787  * For 1, when subsection_map does not empty we will not be freeing the
 788  * usage map, but still need to free the vmemmap range.
 789  *
 790  * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
 791  */
 792 static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
 793                 struct vmem_altmap *altmap)
 794 {
 795         struct mem_section *ms = __pfn_to_section(pfn);
 796         bool section_is_early = early_section(ms);
 797         struct page *memmap = NULL;
 798         bool empty;
 799
 800         if (clear_subsection_map(pfn, nr_pages))
 801                 return;
 802
 803         empty = is_subsection_map_empty(ms);
 804         if (empty) {
 805                 unsigned long section_nr = pfn_to_section_nr(pfn);
 806
 807                 /*
 808                  * When removing an early section, the usage map is kept (as the
 809                  * usage maps of other sections fall into the same page). It
 810                  * will be re-used when re-adding the section - which is then no
 811                  * longer an early section. If the usage map is PageReserved, it
 812                  * was allocated during boot.
 813                  */
 814                 if (!PageReserved(virt_to_page(ms->usage))) {
 815                         kfree(ms->usage);
 816                         ms->usage = NULL;
 817                 }
 818                 memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 819                 /*
 820                  * Mark the section invalid so that valid_section()
 821                  * return false. This prevents code from dereferencing
 822                  * ms->usage array.
 823                  */
 824                 ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
 825         }
 826
 827         /*
 828          * The memmap of early sections is always fully populated. See
 829          * section_activate() and pfn_valid() .
 830          */
 831         if (!section_is_early)
 832                 depopulate_section_memmap(pfn, nr_pages, altmap);
 833         else if (memmap)
 834                 free_map_bootmem(memmap);
 835
 836         if (empty)
 837                 ms->section_mem_map = (unsigned long)NULL;
 838 }
 839
 840 static struct page * __meminit section_activate(int nid, unsigned long pfn,
 841                 unsigned long nr_pages, struct vmem_altmap *altmap)
 842 {
 843         struct mem_section *ms = __pfn_to_section(pfn);
 844         struct mem_section_usage *usage = NULL;
 845         struct page *memmap;
 846         int rc = 0;
 847
 848         if (!ms->usage) {
 849                 usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
 850                 if (!usage)
 851                         return ERR_PTR(-ENOMEM);
 852                 ms->usage = usage;
 853         }
 854
 855         rc = fill_subsection_map(pfn, nr_pages);
 856         if (rc) {
 857                 if (usage)
 858                         ms->usage = NULL;
 859                 kfree(usage);
 860                 return ERR_PTR(rc);
 861         }
 862
 863         /*
 864          * The early init code does not consider partially populated
 865          * initial sections, it simply assumes that memory will never be
 866          * referenced.  If we hot-add memory into such a section then we
 867          * do not need to populate the memmap and can simply reuse what
 868          * is already there.
 869          */
 870         if (nr_pages < PAGES_PER_SECTION && early_section(ms))
 871                 return pfn_to_page(pfn);
 872
 873         memmap = populate_section_memmap(pfn, nr_pages, nid, altmap);
 874         if (!memmap) {
 875                 section_deactivate(pfn, nr_pages, altmap);
 876                 return ERR_PTR(-ENOMEM);
 877         }
 878
 879         return memmap;
 880 }
 881
 882 /**
 883  * sparse_add_section - add a memory section, or populate an existing one
 884  * @nid: The node to add section on
 885  * @start_pfn: start pfn of the memory range
 886  * @nr_pages: number of pfns to add in the section
 887  * @altmap: device page map
 888  *
 889  * This is only intended for hotplug.
 890  *
 891  * Note that only VMEMMAP supports sub-section aligned hotplug,
 892  * the proper alignment and size are gated by check_pfn_span().
 893  *
 894  *
 895  * Return:
 896  * * 0          - On success.
 897  * * -EEXIST    - Section has been present.
 898  * * -ENOMEM    - Out of memory.
 899  */
 900 int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 901                 unsigned long nr_pages, struct vmem_altmap *altmap)
 902 {
 903         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 904         struct mem_section *ms;
 905         struct page *memmap;
 906         int ret;
 907
 908         ret = sparse_index_init(section_nr, nid);
 909         if (ret < 0)
 910                 return ret;
 911
 912         memmap = section_activate(nid, start_pfn, nr_pages, altmap);
 913         if (IS_ERR(memmap))
 914                 return PTR_ERR(memmap);
 915
 916         /*
 917          * Poison uninitialized struct pages in order to catch invalid flags
 918          * combinations.
 919          */
 920         page_init_poison(memmap, sizeof(struct page) * nr_pages);
 921
 922         ms = __nr_to_section(section_nr);
 923         set_section_nid(section_nr, nid);
 924         section_mark_present(ms);
 925
 926         /* Align memmap to section boundary in the subsection case */
 927         if (section_nr_to_pfn(section_nr) != start_pfn)
 928                 memmap = pfn_to_page(section_nr_to_pfn(section_nr));
 929         sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
 930
 931         return 0;
 932 }
 933
 934 #ifdef CONFIG_MEMORY_FAILURE
 935 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 936 {
 937         int i;
 938
 939         /*
 940          * A further optimization is to have per section refcounted
 941          * num_poisoned_pages.  But that would need more space per memmap, so
 942          * for now just do a quick global check to speed up this routine in the
 943          * absence of bad pages.
 944          */
 945         if (atomic_long_read(&num_poisoned_pages) == 0)
 946                 return;
 947
 948         for (i = 0; i < nr_pages; i++) {
 949                 if (PageHWPoison(&memmap[i])) {
 950                         num_poisoned_pages_dec();
 951                         ClearPageHWPoison(&memmap[i]);
 952                 }
 953         }
 954 }
 955 #else
 956 static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 957 {
 958 }
 959 #endif
 960
 961 void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
 962                 unsigned long nr_pages, unsigned long map_offset,
 963                 struct vmem_altmap *altmap)
 964 {
 965         clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
 966                         nr_pages - map_offset);
 967         section_deactivate(pfn, nr_pages, altmap);
 968 }
 969 #endif /* CONFIG_MEMORY_HOTPLUG */