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