mm/memory_hotplug.c

   1 /*
   2  *  linux/mm/memory_hotplug.c
   3  *
   4  *  Copyright (C)
   5  */
   6
   7 #include <linux/stddef.h>
   8 #include <linux/mm.h>
   9 #include <linux/swap.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/compiler.h>
  13 #include <linux/export.h>
  14 #include <linux/pagevec.h>
  15 #include <linux/writeback.h>
  16 #include <linux/slab.h>
  17 #include <linux/sysctl.h>
  18 #include <linux/cpu.h>
  19 #include <linux/memory.h>
  20 #include <linux/memory_hotplug.h>
  21 #include <linux/highmem.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/ioport.h>
  24 #include <linux/delay.h>
  25 #include <linux/migrate.h>
  26 #include <linux/page-isolation.h>
  27 #include <linux/pfn.h>
  28 #include <linux/suspend.h>
  29 #include <linux/mm_inline.h>
  30 #include <linux/firmware-map.h>
  31 #include <linux/stop_machine.h>
  32 #include <linux/hugetlb.h>
  33 #include <linux/memblock.h>
  34
  35 #include <asm/tlbflush.h>
  36
  37 #include "internal.h"
  38
  39 /*
  40  * online_page_callback contains pointer to current page onlining function.
  41  * Initially it is generic_online_page(). If it is required it could be
  42  * changed by calling set_online_page_callback() for callback registration
  43  * and restore_online_page_callback() for generic callback restore.
  44  */
  45
  46 static void generic_online_page(struct page *page);
  47
  48 static online_page_callback_t online_page_callback = generic_online_page;
  49 static DEFINE_MUTEX(online_page_callback_lock);
  50
  51 /* The same as the cpu_hotplug lock, but for memory hotplug. */
  52 static struct {
  53         struct task_struct *active_writer;
  54         struct mutex lock; /* Synchronizes accesses to refcount, */
  55         /*
  56          * Also blocks the new readers during
  57          * an ongoing mem hotplug operation.
  58          */
  59         int refcount;
  60
  61 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  62         struct lockdep_map dep_map;
  63 #endif
  64 } mem_hotplug = {
  65         .active_writer = NULL,
  66         .lock = __MUTEX_INITIALIZER(mem_hotplug.lock),
  67         .refcount = 0,
  68 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  69         .dep_map = {.name = "mem_hotplug.lock" },
  70 #endif
  71 };
  72
  73 /* Lockdep annotations for get/put_online_mems() and mem_hotplug_begin/end() */
  74 #define memhp_lock_acquire_read() lock_map_acquire_read(&mem_hotplug.dep_map)
  75 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
  76 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
  77
  78 void get_online_mems(void)
  79 {
  80         might_sleep();
  81         if (mem_hotplug.active_writer == current)
  82                 return;
  83         memhp_lock_acquire_read();
  84         mutex_lock(&mem_hotplug.lock);
  85         mem_hotplug.refcount++;
  86         mutex_unlock(&mem_hotplug.lock);
  87
  88 }
  89
  90 void put_online_mems(void)
  91 {
  92         if (mem_hotplug.active_writer == current)
  93                 return;
  94         mutex_lock(&mem_hotplug.lock);
  95
  96         if (WARN_ON(!mem_hotplug.refcount))
  97                 mem_hotplug.refcount++; /* try to fix things up */
  98
  99         if (!--mem_hotplug.refcount && unlikely(mem_hotplug.active_writer))
 100                 wake_up_process(mem_hotplug.active_writer);
 101         mutex_unlock(&mem_hotplug.lock);
 102         memhp_lock_release();
 103
 104 }
 105
 106 static void mem_hotplug_begin(void)
 107 {
 108         mem_hotplug.active_writer = current;
 109
 110         memhp_lock_acquire();
 111         for (;;) {
 112                 mutex_lock(&mem_hotplug.lock);
 113                 if (likely(!mem_hotplug.refcount))
 114                         break;
 115                 __set_current_state(TASK_UNINTERRUPTIBLE);
 116                 mutex_unlock(&mem_hotplug.lock);
 117                 schedule();
 118         }
 119 }
 120
 121 static void mem_hotplug_done(void)
 122 {
 123         mem_hotplug.active_writer = NULL;
 124         mutex_unlock(&mem_hotplug.lock);
 125         memhp_lock_release();
 126 }
 127
 128 /* add this memory to iomem resource */
 129 static struct resource *register_memory_resource(u64 start, u64 size)
 130 {
 131         struct resource *res;
 132         res = kzalloc(sizeof(struct resource), GFP_KERNEL);
 133         BUG_ON(!res);
 134
 135         res->name = "System RAM";
 136         res->start = start;
 137         res->end = start + size - 1;
 138         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 139         if (request_resource(&iomem_resource, res) < 0) {
 140                 pr_debug("System RAM resource %pR cannot be added\n", res);
 141                 kfree(res);
 142                 res = NULL;
 143         }
 144         return res;
 145 }
 146
 147 static void release_memory_resource(struct resource *res)
 148 {
 149         if (!res)
 150                 return;
 151         release_resource(res);
 152         kfree(res);
 153         return;
 154 }
 155
 156 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 157 void get_page_bootmem(unsigned long info,  struct page *page,
 158                       unsigned long type)
 159 {
 160         page->lru.next = (struct list_head *) type;
 161         SetPagePrivate(page);
 162         set_page_private(page, info);
 163         atomic_inc(&page->_count);
 164 }
 165
 166 void put_page_bootmem(struct page *page)
 167 {
 168         unsigned long type;
 169
 170         type = (unsigned long) page->lru.next;
 171         BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
 172                type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 173
 174         if (atomic_dec_return(&page->_count) == 1) {
 175                 ClearPagePrivate(page);
 176                 set_page_private(page, 0);
 177                 INIT_LIST_HEAD(&page->lru);
 178                 free_reserved_page(page);
 179         }
 180 }
 181
 182 #ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
 183 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 184 static void register_page_bootmem_info_section(unsigned long start_pfn)
 185 {
 186         unsigned long *usemap, mapsize, section_nr, i;
 187         struct mem_section *ms;
 188         struct page *page, *memmap;
 189
 190         section_nr = pfn_to_section_nr(start_pfn);
 191         ms = __nr_to_section(section_nr);
 192
 193         /* Get section's memmap address */
 194         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 195
 196         /*
 197          * Get page for the memmap's phys address
 198          * XXX: need more consideration for sparse_vmemmap...
 199          */
 200         page = virt_to_page(memmap);
 201         mapsize = sizeof(struct page) * PAGES_PER_SECTION;
 202         mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
 203
 204         /* remember memmap's page */
 205         for (i = 0; i < mapsize; i++, page++)
 206                 get_page_bootmem(section_nr, page, SECTION_INFO);
 207
 208         usemap = __nr_to_section(section_nr)->pageblock_flags;
 209         page = virt_to_page(usemap);
 210
 211         mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
 212
 213         for (i = 0; i < mapsize; i++, page++)
 214                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
 215
 216 }
 217 #else /* CONFIG_SPARSEMEM_VMEMMAP */
 218 static void register_page_bootmem_info_section(unsigned long start_pfn)
 219 {
 220         unsigned long *usemap, mapsize, section_nr, i;
 221         struct mem_section *ms;
 222         struct page *page, *memmap;
 223
 224         if (!pfn_valid(start_pfn))
 225                 return;
 226
 227         section_nr = pfn_to_section_nr(start_pfn);
 228         ms = __nr_to_section(section_nr);
 229
 230         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 231
 232         register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
 233
 234         usemap = __nr_to_section(section_nr)->pageblock_flags;
 235         page = virt_to_page(usemap);
 236
 237         mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
 238
 239         for (i = 0; i < mapsize; i++, page++)
 240                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
 241 }
 242 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 243
 244 void register_page_bootmem_info_node(struct pglist_data *pgdat)
 245 {
 246         unsigned long i, pfn, end_pfn, nr_pages;
 247         int node = pgdat->node_id;
 248         struct page *page;
 249         struct zone *zone;
 250
 251         nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
 252         page = virt_to_page(pgdat);
 253
 254         for (i = 0; i < nr_pages; i++, page++)
 255                 get_page_bootmem(node, page, NODE_INFO);
 256
 257         zone = &pgdat->node_zones[0];
 258         for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
 259                 if (zone_is_initialized(zone)) {
 260                         nr_pages = zone->wait_table_hash_nr_entries
 261                                 * sizeof(wait_queue_head_t);
 262                         nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
 263                         page = virt_to_page(zone->wait_table);
 264
 265                         for (i = 0; i < nr_pages; i++, page++)
 266                                 get_page_bootmem(node, page, NODE_INFO);
 267                 }
 268         }
 269
 270         pfn = pgdat->node_start_pfn;
 271         end_pfn = pgdat_end_pfn(pgdat);
 272
 273         /* register section info */
 274         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 275                 /*
 276                  * Some platforms can assign the same pfn to multiple nodes - on
 277                  * node0 as well as nodeN.  To avoid registering a pfn against
 278                  * multiple nodes we check that this pfn does not already
 279                  * reside in some other nodes.
 280                  */
 281                 if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
 282                         register_page_bootmem_info_section(pfn);
 283         }
 284 }
 285 #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
 286
 287 static void __meminit grow_zone_span(struct zone *zone, unsigned long start_pfn,
 288                                      unsigned long end_pfn)
 289 {
 290         unsigned long old_zone_end_pfn;
 291
 292         zone_span_writelock(zone);
 293
 294         old_zone_end_pfn = zone_end_pfn(zone);
 295         if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
 296                 zone->zone_start_pfn = start_pfn;
 297
 298         zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
 299                                 zone->zone_start_pfn;
 300
 301         zone_span_writeunlock(zone);
 302 }
 303
 304 static void resize_zone(struct zone *zone, unsigned long start_pfn,
 305                 unsigned long end_pfn)
 306 {
 307         zone_span_writelock(zone);
 308
 309         if (end_pfn - start_pfn) {
 310                 zone->zone_start_pfn = start_pfn;
 311                 zone->spanned_pages = end_pfn - start_pfn;
 312         } else {
 313                 /*
 314                  * make it consist as free_area_init_core(),
 315                  * if spanned_pages = 0, then keep start_pfn = 0
 316                  */
 317                 zone->zone_start_pfn = 0;
 318                 zone->spanned_pages = 0;
 319         }
 320
 321         zone_span_writeunlock(zone);
 322 }
 323
 324 static void fix_zone_id(struct zone *zone, unsigned long start_pfn,
 325                 unsigned long end_pfn)
 326 {
 327         enum zone_type zid = zone_idx(zone);
 328         int nid = zone->zone_pgdat->node_id;
 329         unsigned long pfn;
 330
 331         for (pfn = start_pfn; pfn < end_pfn; pfn++)
 332                 set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 333 }
 334
 335 /* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
 336  * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
 337 static int __ref ensure_zone_is_initialized(struct zone *zone,
 338                         unsigned long start_pfn, unsigned long num_pages)
 339 {
 340         if (!zone_is_initialized(zone))
 341                 return init_currently_empty_zone(zone, start_pfn, num_pages,
 342                                                  MEMMAP_HOTPLUG);
 343         return 0;
 344 }
 345
 346 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
 347                 unsigned long start_pfn, unsigned long end_pfn)
 348 {
 349         int ret;
 350         unsigned long flags;
 351         unsigned long z1_start_pfn;
 352
 353         ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
 354         if (ret)
 355                 return ret;
 356
 357         pgdat_resize_lock(z1->zone_pgdat, &flags);
 358
 359         /* can't move pfns which are higher than @z2 */
 360         if (end_pfn > zone_end_pfn(z2))
 361                 goto out_fail;
 362         /* the move out part must be at the left most of @z2 */
 363         if (start_pfn > z2->zone_start_pfn)
 364                 goto out_fail;
 365         /* must included/overlap */
 366         if (end_pfn <= z2->zone_start_pfn)
 367                 goto out_fail;
 368
 369         /* use start_pfn for z1's start_pfn if z1 is empty */
 370         if (!zone_is_empty(z1))
 371                 z1_start_pfn = z1->zone_start_pfn;
 372         else
 373                 z1_start_pfn = start_pfn;
 374
 375         resize_zone(z1, z1_start_pfn, end_pfn);
 376         resize_zone(z2, end_pfn, zone_end_pfn(z2));
 377
 378         pgdat_resize_unlock(z1->zone_pgdat, &flags);
 379
 380         fix_zone_id(z1, start_pfn, end_pfn);
 381
 382         return 0;
 383 out_fail:
 384         pgdat_resize_unlock(z1->zone_pgdat, &flags);
 385         return -1;
 386 }
 387
 388 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
 389                 unsigned long start_pfn, unsigned long end_pfn)
 390 {
 391         int ret;
 392         unsigned long flags;
 393         unsigned long z2_end_pfn;
 394
 395         ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
 396         if (ret)
 397                 return ret;
 398
 399         pgdat_resize_lock(z1->zone_pgdat, &flags);
 400
 401         /* can't move pfns which are lower than @z1 */
 402         if (z1->zone_start_pfn > start_pfn)
 403                 goto out_fail;
 404         /* the move out part mast at the right most of @z1 */
 405         if (zone_end_pfn(z1) >  end_pfn)
 406                 goto out_fail;
 407         /* must included/overlap */
 408         if (start_pfn >= zone_end_pfn(z1))
 409                 goto out_fail;
 410
 411         /* use end_pfn for z2's end_pfn if z2 is empty */
 412         if (!zone_is_empty(z2))
 413                 z2_end_pfn = zone_end_pfn(z2);
 414         else
 415                 z2_end_pfn = end_pfn;
 416
 417         resize_zone(z1, z1->zone_start_pfn, start_pfn);
 418         resize_zone(z2, start_pfn, z2_end_pfn);
 419
 420         pgdat_resize_unlock(z1->zone_pgdat, &flags);
 421
 422         fix_zone_id(z2, start_pfn, end_pfn);
 423
 424         return 0;
 425 out_fail:
 426         pgdat_resize_unlock(z1->zone_pgdat, &flags);
 427         return -1;
 428 }
 429
 430 static void __meminit grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
 431                                       unsigned long end_pfn)
 432 {
 433         unsigned long old_pgdat_end_pfn = pgdat_end_pfn(pgdat);
 434
 435         if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
 436                 pgdat->node_start_pfn = start_pfn;
 437
 438         pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
 439                                         pgdat->node_start_pfn;
 440 }
 441
 442 static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
 443 {
 444         struct pglist_data *pgdat = zone->zone_pgdat;
 445         int nr_pages = PAGES_PER_SECTION;
 446         int nid = pgdat->node_id;
 447         int zone_type;
 448         unsigned long flags;
 449         int ret;
 450
 451         zone_type = zone - pgdat->node_zones;
 452         ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
 453         if (ret)
 454                 return ret;
 455
 456         pgdat_resize_lock(zone->zone_pgdat, &flags);
 457         grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
 458         grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
 459                         phys_start_pfn + nr_pages);
 460         pgdat_resize_unlock(zone->zone_pgdat, &flags);
 461         memmap_init_zone(nr_pages, nid, zone_type,
 462                          phys_start_pfn, MEMMAP_HOTPLUG);
 463         return 0;
 464 }
 465
 466 static int __meminit __add_section(int nid, struct zone *zone,
 467                                         unsigned long phys_start_pfn)
 468 {
 469         int ret;
 470
 471         if (pfn_valid(phys_start_pfn))
 472                 return -EEXIST;
 473
 474         ret = sparse_add_one_section(zone, phys_start_pfn);
 475
 476         if (ret < 0)
 477                 return ret;
 478
 479         ret = __add_zone(zone, phys_start_pfn);
 480
 481         if (ret < 0)
 482                 return ret;
 483
 484         return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
 485 }
 486
 487 /*
 488  * Reasonably generic function for adding memory.  It is
 489  * expected that archs that support memory hotplug will
 490  * call this function after deciding the zone to which to
 491  * add the new pages.
 492  */
 493 int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
 494                         unsigned long nr_pages)
 495 {
 496         unsigned long i;
 497         int err = 0;
 498         int start_sec, end_sec;
 499         /* during initialize mem_map, align hot-added range to section */
 500         start_sec = pfn_to_section_nr(phys_start_pfn);
 501         end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
 502
 503         for (i = start_sec; i <= end_sec; i++) {
 504                 err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
 505
 506                 /*
 507                  * EEXIST is finally dealt with by ioresource collision
 508                  * check. see add_memory() => register_memory_resource()
 509                  * Warning will be printed if there is collision.
 510                  */
 511                 if (err && (err != -EEXIST))
 512                         break;
 513                 err = 0;
 514         }
 515
 516         return err;
 517 }
 518 EXPORT_SYMBOL_GPL(__add_pages);
 519
 520 #ifdef CONFIG_MEMORY_HOTREMOVE
 521 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
 522 static int find_smallest_section_pfn(int nid, struct zone *zone,
 523                                      unsigned long start_pfn,
 524                                      unsigned long end_pfn)
 525 {
 526         struct mem_section *ms;
 527
 528         for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
 529                 ms = __pfn_to_section(start_pfn);
 530
 531                 if (unlikely(!valid_section(ms)))
 532                         continue;
 533
 534                 if (unlikely(pfn_to_nid(start_pfn) != nid))
 535                         continue;
 536
 537                 if (zone && zone != page_zone(pfn_to_page(start_pfn)))
 538                         continue;
 539
 540                 return start_pfn;
 541         }
 542
 543         return 0;
 544 }
 545
 546 /* find the biggest valid pfn in the range [start_pfn, end_pfn). */
 547 static int find_biggest_section_pfn(int nid, struct zone *zone,
 548                                     unsigned long start_pfn,
 549                                     unsigned long end_pfn)
 550 {
 551         struct mem_section *ms;
 552         unsigned long pfn;
 553
 554         /* pfn is the end pfn of a memory section. */
 555         pfn = end_pfn - 1;
 556         for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
 557                 ms = __pfn_to_section(pfn);
 558
 559                 if (unlikely(!valid_section(ms)))
 560                         continue;
 561
 562                 if (unlikely(pfn_to_nid(pfn) != nid))
 563                         continue;
 564
 565                 if (zone && zone != page_zone(pfn_to_page(pfn)))
 566                         continue;
 567
 568                 return pfn;
 569         }
 570
 571         return 0;
 572 }
 573
 574 static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
 575                              unsigned long end_pfn)
 576 {
 577         unsigned long zone_start_pfn = zone->zone_start_pfn;
 578         unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
 579         unsigned long zone_end_pfn = z;
 580         unsigned long pfn;
 581         struct mem_section *ms;
 582         int nid = zone_to_nid(zone);
 583
 584         zone_span_writelock(zone);
 585         if (zone_start_pfn == start_pfn) {
 586                 /*
 587                  * If the section is smallest section in the zone, it need
 588                  * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
 589                  * In this case, we find second smallest valid mem_section
 590                  * for shrinking zone.
 591                  */
 592                 pfn = find_smallest_section_pfn(nid, zone, end_pfn,
 593                                                 zone_end_pfn);
 594                 if (pfn) {
 595                         zone->zone_start_pfn = pfn;
 596                         zone->spanned_pages = zone_end_pfn - pfn;
 597                 }
 598         } else if (zone_end_pfn == end_pfn) {
 599                 /*
 600                  * If the section is biggest section in the zone, it need
 601                  * shrink zone->spanned_pages.
 602                  * In this case, we find second biggest valid mem_section for
 603                  * shrinking zone.
 604                  */
 605                 pfn = find_biggest_section_pfn(nid, zone, zone_start_pfn,
 606                                                start_pfn);
 607                 if (pfn)
 608                         zone->spanned_pages = pfn - zone_start_pfn + 1;
 609         }
 610
 611         /*
 612          * The section is not biggest or smallest mem_section in the zone, it
 613          * only creates a hole in the zone. So in this case, we need not
 614          * change the zone. But perhaps, the zone has only hole data. Thus
 615          * it check the zone has only hole or not.
 616          */
 617         pfn = zone_start_pfn;
 618         for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
 619                 ms = __pfn_to_section(pfn);
 620
 621                 if (unlikely(!valid_section(ms)))
 622                         continue;
 623
 624                 if (page_zone(pfn_to_page(pfn)) != zone)
 625                         continue;
 626
 627                  /* If the section is current section, it continues the loop */
 628                 if (start_pfn == pfn)
 629                         continue;
 630
 631                 /* If we find valid section, we have nothing to do */
 632                 zone_span_writeunlock(zone);
 633                 return;
 634         }
 635
 636         /* The zone has no valid section */
 637         zone->zone_start_pfn = 0;
 638         zone->spanned_pages = 0;
 639         zone_span_writeunlock(zone);
 640 }
 641
 642 static void shrink_pgdat_span(struct pglist_data *pgdat,
 643                               unsigned long start_pfn, unsigned long end_pfn)
 644 {
 645         unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
 646         unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
 647         unsigned long pgdat_end_pfn = p;
 648         unsigned long pfn;
 649         struct mem_section *ms;
 650         int nid = pgdat->node_id;
 651
 652         if (pgdat_start_pfn == start_pfn) {
 653                 /*
 654                  * If the section is smallest section in the pgdat, it need
 655                  * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
 656                  * In this case, we find second smallest valid mem_section
 657                  * for shrinking zone.
 658                  */
 659                 pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
 660                                                 pgdat_end_pfn);
 661                 if (pfn) {
 662                         pgdat->node_start_pfn = pfn;
 663                         pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
 664                 }
 665         } else if (pgdat_end_pfn == end_pfn) {
 666                 /*
 667                  * If the section is biggest section in the pgdat, it need
 668                  * shrink pgdat->node_spanned_pages.
 669                  * In this case, we find second biggest valid mem_section for
 670                  * shrinking zone.
 671                  */
 672                 pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
 673                                                start_pfn);
 674                 if (pfn)
 675                         pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
 676         }
 677
 678         /*
 679          * If the section is not biggest or smallest mem_section in the pgdat,
 680          * it only creates a hole in the pgdat. So in this case, we need not
 681          * change the pgdat.
 682          * But perhaps, the pgdat has only hole data. Thus it check the pgdat
 683          * has only hole or not.
 684          */
 685         pfn = pgdat_start_pfn;
 686         for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) {
 687                 ms = __pfn_to_section(pfn);
 688
 689                 if (unlikely(!valid_section(ms)))
 690                         continue;
 691
 692                 if (pfn_to_nid(pfn) != nid)
 693                         continue;
 694
 695                  /* If the section is current section, it continues the loop */
 696                 if (start_pfn == pfn)
 697                         continue;
 698
 699                 /* If we find valid section, we have nothing to do */
 700                 return;
 701         }
 702
 703         /* The pgdat has no valid section */
 704         pgdat->node_start_pfn = 0;
 705         pgdat->node_spanned_pages = 0;
 706 }
 707
 708 static void __remove_zone(struct zone *zone, unsigned long start_pfn)
 709 {
 710         struct pglist_data *pgdat = zone->zone_pgdat;
 711         int nr_pages = PAGES_PER_SECTION;
 712         int zone_type;
 713         unsigned long flags;
 714
 715         zone_type = zone - pgdat->node_zones;
 716
 717         pgdat_resize_lock(zone->zone_pgdat, &flags);
 718         shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
 719         shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
 720         pgdat_resize_unlock(zone->zone_pgdat, &flags);
 721 }
 722
 723 static int __remove_section(struct zone *zone, struct mem_section *ms)
 724 {
 725         unsigned long start_pfn;
 726         int scn_nr;
 727         int ret = -EINVAL;
 728
 729         if (!valid_section(ms))
 730                 return ret;
 731
 732         ret = unregister_memory_section(ms);
 733         if (ret)
 734                 return ret;
 735
 736         scn_nr = __section_nr(ms);
 737         start_pfn = section_nr_to_pfn(scn_nr);
 738         __remove_zone(zone, start_pfn);
 739
 740         sparse_remove_one_section(zone, ms);
 741         return 0;
 742 }
 743
 744 /**
 745  * __remove_pages() - remove sections of pages from a zone
 746  * @zone: zone from which pages need to be removed
 747  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
 748  * @nr_pages: number of pages to remove (must be multiple of section size)
 749  *
 750  * Generic helper function to remove section mappings and sysfs entries
 751  * for the section of the memory we are removing. Caller needs to make
 752  * sure that pages are marked reserved and zones are adjust properly by
 753  * calling offline_pages().
 754  */
 755 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 756                  unsigned long nr_pages)
 757 {
 758         unsigned long i;
 759         int sections_to_remove;
 760         resource_size_t start, size;
 761         int ret = 0;
 762
 763         /*
 764          * We can only remove entire sections
 765          */
 766         BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
 767         BUG_ON(nr_pages % PAGES_PER_SECTION);
 768
 769         start = phys_start_pfn << PAGE_SHIFT;
 770         size = nr_pages * PAGE_SIZE;
 771         ret = release_mem_region_adjustable(&iomem_resource, start, size);
 772         if (ret) {
 773                 resource_size_t endres = start + size - 1;
 774
 775                 pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
 776                                 &start, &endres, ret);
 777         }
 778
 779         sections_to_remove = nr_pages / PAGES_PER_SECTION;
 780         for (i = 0; i < sections_to_remove; i++) {
 781                 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
 782                 ret = __remove_section(zone, __pfn_to_section(pfn));
 783                 if (ret)
 784                         break;
 785         }
 786         return ret;
 787 }
 788 EXPORT_SYMBOL_GPL(__remove_pages);
 789 #endif /* CONFIG_MEMORY_HOTREMOVE */
 790
 791 int set_online_page_callback(online_page_callback_t callback)
 792 {
 793         int rc = -EINVAL;
 794
 795         get_online_mems();
 796         mutex_lock(&online_page_callback_lock);
 797
 798         if (online_page_callback == generic_online_page) {
 799                 online_page_callback = callback;
 800                 rc = 0;
 801         }
 802
 803         mutex_unlock(&online_page_callback_lock);
 804         put_online_mems();
 805
 806         return rc;
 807 }
 808 EXPORT_SYMBOL_GPL(set_online_page_callback);
 809
 810 int restore_online_page_callback(online_page_callback_t callback)
 811 {
 812         int rc = -EINVAL;
 813
 814         get_online_mems();
 815         mutex_lock(&online_page_callback_lock);
 816
 817         if (online_page_callback == callback) {
 818                 online_page_callback = generic_online_page;
 819                 rc = 0;
 820         }
 821
 822         mutex_unlock(&online_page_callback_lock);
 823         put_online_mems();
 824
 825         return rc;
 826 }
 827 EXPORT_SYMBOL_GPL(restore_online_page_callback);
 828
 829 void __online_page_set_limits(struct page *page)
 830 {
 831 }
 832 EXPORT_SYMBOL_GPL(__online_page_set_limits);
 833
 834 void __online_page_increment_counters(struct page *page)
 835 {
 836         adjust_managed_page_count(page, 1);
 837 }
 838 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 839
 840 void __online_page_free(struct page *page)
 841 {
 842         __free_reserved_page(page);
 843 }
 844 EXPORT_SYMBOL_GPL(__online_page_free);
 845
 846 static void generic_online_page(struct page *page)
 847 {
 848         __online_page_set_limits(page);
 849         __online_page_increment_counters(page);
 850         __online_page_free(page);
 851 }
 852
 853 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 854                         void *arg)
 855 {
 856         unsigned long i;
 857         unsigned long onlined_pages = *(unsigned long *)arg;
 858         struct page *page;
 859         if (PageReserved(pfn_to_page(start_pfn)))
 860                 for (i = 0; i < nr_pages; i++) {
 861                         page = pfn_to_page(start_pfn + i);
 862                         (*online_page_callback)(page);
 863                         onlined_pages++;
 864                 }
 865         *(unsigned long *)arg = onlined_pages;
 866         return 0;
 867 }
 868
 869 #ifdef CONFIG_MOVABLE_NODE
 870 /*
 871  * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
 872  * normal memory.
 873  */
 874 static bool can_online_high_movable(struct zone *zone)
 875 {
 876         return true;
 877 }
 878 #else /* CONFIG_MOVABLE_NODE */
 879 /* ensure every online node has NORMAL memory */
 880 static bool can_online_high_movable(struct zone *zone)
 881 {
 882         return node_state(zone_to_nid(zone), N_NORMAL_MEMORY);
 883 }
 884 #endif /* CONFIG_MOVABLE_NODE */
 885
 886 /* check which state of node_states will be changed when online memory */
 887 static void node_states_check_changes_online(unsigned long nr_pages,
 888         struct zone *zone, struct memory_notify *arg)
 889 {
 890         int nid = zone_to_nid(zone);
 891         enum zone_type zone_last = ZONE_NORMAL;
 892
 893         /*
 894          * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
 895          * contains nodes which have zones of 0...ZONE_NORMAL,
 896          * set zone_last to ZONE_NORMAL.
 897          *
 898          * If we don't have HIGHMEM nor movable node,
 899          * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
 900          * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
 901          */
 902         if (N_MEMORY == N_NORMAL_MEMORY)
 903                 zone_last = ZONE_MOVABLE;
 904
 905         /*
 906          * if the memory to be online is in a zone of 0...zone_last, and
 907          * the zones of 0...zone_last don't have memory before online, we will
 908          * need to set the node to node_states[N_NORMAL_MEMORY] after
 909          * the memory is online.
 910          */
 911         if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
 912                 arg->status_change_nid_normal = nid;
 913         else
 914                 arg->status_change_nid_normal = -1;
 915
 916 #ifdef CONFIG_HIGHMEM
 917         /*
 918          * If we have movable node, node_states[N_HIGH_MEMORY]
 919          * contains nodes which have zones of 0...ZONE_HIGHMEM,
 920          * set zone_last to ZONE_HIGHMEM.
 921          *
 922          * If we don't have movable node, node_states[N_NORMAL_MEMORY]
 923          * contains nodes which have zones of 0...ZONE_MOVABLE,
 924          * set zone_last to ZONE_MOVABLE.
 925          */
 926         zone_last = ZONE_HIGHMEM;
 927         if (N_MEMORY == N_HIGH_MEMORY)
 928                 zone_last = ZONE_MOVABLE;
 929
 930         if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY))
 931                 arg->status_change_nid_high = nid;
 932         else
 933                 arg->status_change_nid_high = -1;
 934 #else
 935         arg->status_change_nid_high = arg->status_change_nid_normal;
 936 #endif
 937
 938         /*
 939          * if the node don't have memory befor online, we will need to
 940          * set the node to node_states[N_MEMORY] after the memory
 941          * is online.
 942          */
 943         if (!node_state(nid, N_MEMORY))
 944                 arg->status_change_nid = nid;
 945         else
 946                 arg->status_change_nid = -1;
 947 }
 948
 949 static void node_states_set_node(int node, struct memory_notify *arg)
 950 {
 951         if (arg->status_change_nid_normal >= 0)
 952                 node_set_state(node, N_NORMAL_MEMORY);
 953
 954         if (arg->status_change_nid_high >= 0)
 955                 node_set_state(node, N_HIGH_MEMORY);
 956
 957         node_set_state(node, N_MEMORY);
 958 }
 959
 960
 961 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
 962 {
 963         unsigned long flags;
 964         unsigned long onlined_pages = 0;
 965         struct zone *zone;
 966         int need_zonelists_rebuild = 0;
 967         int nid;
 968         int ret;
 969         struct memory_notify arg;
 970
 971         mem_hotplug_begin();
 972         /*
 973          * This doesn't need a lock to do pfn_to_page().
 974          * The section can't be removed here because of the
 975          * memory_block->state_mutex.
 976          */
 977         zone = page_zone(pfn_to_page(pfn));
 978
 979         ret = -EINVAL;
 980         if ((zone_idx(zone) > ZONE_NORMAL ||
 981             online_type == MMOP_ONLINE_MOVABLE) &&
 982             !can_online_high_movable(zone))
 983                 goto out;
 984
 985         if (online_type == MMOP_ONLINE_KERNEL &&
 986             zone_idx(zone) == ZONE_MOVABLE) {
 987                 if (move_pfn_range_left(zone - 1, zone, pfn, pfn + nr_pages))
 988                         goto out;
 989         }
 990         if (online_type == MMOP_ONLINE_MOVABLE &&
 991             zone_idx(zone) == ZONE_MOVABLE - 1) {
 992                 if (move_pfn_range_right(zone, zone + 1, pfn, pfn + nr_pages))
 993                         goto out;
 994         }
 995
 996         /* Previous code may changed the zone of the pfn range */
 997         zone = page_zone(pfn_to_page(pfn));
 998
 999         arg.start_pfn = pfn;
1000         arg.nr_pages = nr_pages;
1001         node_states_check_changes_online(nr_pages, zone, &arg);
1002
1003         nid = pfn_to_nid(pfn);
1004
1005         ret = memory_notify(MEM_GOING_ONLINE, &arg);
1006         ret = notifier_to_errno(ret);
1007         if (ret) {
1008                 memory_notify(MEM_CANCEL_ONLINE, &arg);
1009                 goto out;
1010         }
1011         /*
1012          * If this zone is not populated, then it is not in zonelist.
1013          * This means the page allocator ignores this zone.
1014          * So, zonelist must be updated after online.
1015          */
1016         mutex_lock(&zonelists_mutex);
1017         if (!populated_zone(zone)) {
1018                 need_zonelists_rebuild = 1;
1019                 build_all_zonelists(NULL, zone);
1020         }
1021
1022         ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
1023                 online_pages_range);
1024         if (ret) {
1025                 if (need_zonelists_rebuild)
1026                         zone_pcp_reset(zone);
1027                 mutex_unlock(&zonelists_mutex);
1028                 printk(KERN_DEBUG "online_pages [mem %#010llx-%#010llx] failed\n",
1029                        (unsigned long long) pfn << PAGE_SHIFT,
1030                        (((unsigned long long) pfn + nr_pages)
1031                             << PAGE_SHIFT) - 1);
1032                 memory_notify(MEM_CANCEL_ONLINE, &arg);
1033                 goto out;
1034         }
1035
1036         zone->present_pages += onlined_pages;
1037
1038         pgdat_resize_lock(zone->zone_pgdat, &flags);
1039         zone->zone_pgdat->node_present_pages += onlined_pages;
1040         pgdat_resize_unlock(zone->zone_pgdat, &flags);
1041
1042         if (onlined_pages) {
1043                 node_states_set_node(zone_to_nid(zone), &arg);
1044                 if (need_zonelists_rebuild)
1045                         build_all_zonelists(NULL, NULL);
1046                 else
1047                         zone_pcp_update(zone);
1048         }
1049
1050         mutex_unlock(&zonelists_mutex);
1051
1052         init_per_zone_wmark_min();
1053
1054         if (onlined_pages)
1055                 kswapd_run(zone_to_nid(zone));
1056
1057         vm_total_pages = nr_free_pagecache_pages();
1058
1059         writeback_set_ratelimit();
1060
1061         if (onlined_pages)
1062                 memory_notify(MEM_ONLINE, &arg);
1063 out:
1064         mem_hotplug_done();
1065         return ret;
1066 }
1067 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
1068
1069 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
1070 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
1071 {
1072         struct pglist_data *pgdat;
1073         unsigned long zones_size[MAX_NR_ZONES] = {0};
1074         unsigned long zholes_size[MAX_NR_ZONES] = {0};
1075         unsigned long start_pfn = PFN_DOWN(start);
1076
1077         pgdat = NODE_DATA(nid);
1078         if (!pgdat) {
1079                 pgdat = arch_alloc_nodedata(nid);
1080                 if (!pgdat)
1081                         return NULL;
1082
1083                 arch_refresh_nodedata(nid, pgdat);
1084         }
1085
1086         /* we can use NODE_DATA(nid) from here */
1087
1088         /* init node's zones as empty zones, we don't have any present pages.*/
1089         free_area_init_node(nid, zones_size, start_pfn, zholes_size);
1090
1091         /*
1092          * The node we allocated has no zone fallback lists. For avoiding
1093          * to access not-initialized zonelist, build here.
1094          */
1095         mutex_lock(&zonelists_mutex);
1096         build_all_zonelists(pgdat, NULL);
1097         mutex_unlock(&zonelists_mutex);
1098
1099         return pgdat;
1100 }
1101
1102 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
1103 {
1104         arch_refresh_nodedata(nid, NULL);
1105         arch_free_nodedata(pgdat);
1106         return;
1107 }
1108
1109
1110 /**
1111  * try_online_node - online a node if offlined
1112  *
1113  * called by cpu_up() to online a node without onlined memory.
1114  */
1115 int try_online_node(int nid)
1116 {
1117         pg_data_t       *pgdat;
1118         int     ret;
1119
1120         if (node_online(nid))
1121                 return 0;
1122
1123         mem_hotplug_begin();
1124         pgdat = hotadd_new_pgdat(nid, 0);
1125         if (!pgdat) {
1126                 pr_err("Cannot online node %d due to NULL pgdat\n", nid);
1127                 ret = -ENOMEM;
1128                 goto out;
1129         }
1130         node_set_online(nid);
1131         ret = register_one_node(nid);
1132         BUG_ON(ret);
1133
1134         if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
1135                 mutex_lock(&zonelists_mutex);
1136                 build_all_zonelists(NULL, NULL);
1137                 mutex_unlock(&zonelists_mutex);
1138         }
1139
1140 out:
1141         mem_hotplug_done();
1142         return ret;
1143 }
1144
1145 static int check_hotplug_memory_range(u64 start, u64 size)
1146 {
1147         u64 start_pfn = PFN_DOWN(start);
1148         u64 nr_pages = size >> PAGE_SHIFT;
1149
1150         /* Memory range must be aligned with section */
1151         if ((start_pfn & ~PAGE_SECTION_MASK) ||
1152             (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
1153                 pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
1154                                 (unsigned long long)start,
1155                                 (unsigned long long)size);
1156                 return -EINVAL;
1157         }
1158
1159         return 0;
1160 }
1161
1162 /*
1163  * If movable zone has already been setup, newly added memory should be check.
1164  * If its address is higher than movable zone, it should be added as movable.
1165  * Without this check, movable zone may overlap with other zone.
1166  */
1167 static int should_add_memory_movable(int nid, u64 start, u64 size)
1168 {
1169         unsigned long start_pfn = start >> PAGE_SHIFT;
1170         pg_data_t *pgdat = NODE_DATA(nid);
1171         struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
1172
1173         if (zone_is_empty(movable_zone))
1174                 return 0;
1175
1176         if (movable_zone->zone_start_pfn <= start_pfn)
1177                 return 1;
1178
1179         return 0;
1180 }
1181
1182 int zone_for_memory(int nid, u64 start, u64 size, int zone_default)
1183 {
1184         if (should_add_memory_movable(nid, start, size))
1185                 return ZONE_MOVABLE;
1186
1187         return zone_default;
1188 }
1189
1190 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
1191 int __ref add_memory(int nid, u64 start, u64 size)
1192 {
1193         pg_data_t *pgdat = NULL;
1194         bool new_pgdat;
1195         bool new_node;
1196         struct resource *res;
1197         int ret;
1198
1199         ret = check_hotplug_memory_range(start, size);
1200         if (ret)
1201                 return ret;
1202
1203         res = register_memory_resource(start, size);
1204         ret = -EEXIST;
1205         if (!res)
1206                 return ret;
1207
1208         {       /* Stupid hack to suppress address-never-null warning */
1209                 void *p = NODE_DATA(nid);
1210                 new_pgdat = !p;
1211         }
1212
1213         mem_hotplug_begin();
1214
1215         new_node = !node_online(nid);
1216         if (new_node) {
1217                 pgdat = hotadd_new_pgdat(nid, start);
1218                 ret = -ENOMEM;
1219                 if (!pgdat)
1220                         goto error;
1221         }
1222
1223         /* call arch's memory hotadd */
1224         ret = arch_add_memory(nid, start, size);
1225
1226         if (ret < 0)
1227                 goto error;
1228
1229         /* we online node here. we can't roll back from here. */
1230         node_set_online(nid);
1231
1232         if (new_node) {
1233                 ret = register_one_node(nid);
1234                 /*
1235                  * If sysfs file of new node can't create, cpu on the node
1236                  * can't be hot-added. There is no rollback way now.
1237                  * So, check by BUG_ON() to catch it reluctantly..
1238                  */
1239                 BUG_ON(ret);
1240         }
1241
1242         /* create new memmap entry */
1243         firmware_map_add_hotplug(start, start + size, "System RAM");
1244
1245         goto out;
1246
1247 error:
1248         /* rollback pgdat allocation and others */
1249         if (new_pgdat)
1250                 rollback_node_hotadd(nid, pgdat);
1251         release_memory_resource(res);
1252
1253 out:
1254         mem_hotplug_done();
1255         return ret;
1256 }
1257 EXPORT_SYMBOL_GPL(add_memory);
1258
1259 #ifdef CONFIG_MEMORY_HOTREMOVE
1260 /*
1261  * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
1262  * set and the size of the free page is given by page_order(). Using this,
1263  * the function determines if the pageblock contains only free pages.
1264  * Due to buddy contraints, a free page at least the size of a pageblock will
1265  * be located at the start of the pageblock
1266  */
1267 static inline int pageblock_free(struct page *page)
1268 {
1269         return PageBuddy(page) && page_order(page) >= pageblock_order;
1270 }
1271
1272 /* Return the start of the next active pageblock after a given page */
1273 static struct page *next_active_pageblock(struct page *page)
1274 {
1275         /* Ensure the starting page is pageblock-aligned */
1276         BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
1277
1278         /* If the entire pageblock is free, move to the end of free page */
1279         if (pageblock_free(page)) {
1280                 int order;
1281                 /* be careful. we don't have locks, page_order can be changed.*/
1282                 order = page_order(page);
1283                 if ((order < MAX_ORDER) && (order >= pageblock_order))
1284                         return page + (1 << order);
1285         }
1286
1287         return page + pageblock_nr_pages;
1288 }
1289
1290 /* Checks if this range of memory is likely to be hot-removable. */
1291 int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
1292 {
1293         struct page *page = pfn_to_page(start_pfn);
1294         struct page *end_page = page + nr_pages;
1295
1296         /* Check the starting page of each pageblock within the range */
1297         for (; page < end_page; page = next_active_pageblock(page)) {
1298                 if (!is_pageblock_removable_nolock(page))
1299                         return 0;
1300                 cond_resched();
1301         }
1302
1303         /* All pageblocks in the memory block are likely to be hot-removable */
1304         return 1;
1305 }
1306
1307 /*
1308  * Confirm all pages in a range [start, end) is belongs to the same zone.
1309  */
1310 int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
1311 {
1312         unsigned long pfn;
1313         struct zone *zone = NULL;
1314         struct page *page;
1315         int i;
1316         for (pfn = start_pfn;
1317              pfn < end_pfn;
1318              pfn += MAX_ORDER_NR_PAGES) {
1319                 i = 0;
1320                 /* This is just a CONFIG_HOLES_IN_ZONE check.*/
1321                 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
1322                         i++;
1323                 if (i == MAX_ORDER_NR_PAGES)
1324                         continue;
1325                 page = pfn_to_page(pfn + i);
1326                 if (zone && page_zone(page) != zone)
1327                         return 0;
1328                 zone = page_zone(page);
1329         }
1330         return 1;
1331 }
1332
1333 /*
1334  * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
1335  * and hugepages). We scan pfn because it's much easier than scanning over
1336  * linked list. This function returns the pfn of the first found movable
1337  * page if it's found, otherwise 0.
1338  */
1339 static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
1340 {
1341         unsigned long pfn;
1342         struct page *page;
1343         for (pfn = start; pfn < end; pfn++) {
1344                 if (pfn_valid(pfn)) {
1345                         page = pfn_to_page(pfn);
1346                         if (PageLRU(page))
1347                                 return pfn;
1348                         if (PageHuge(page)) {
1349                                 if (is_hugepage_active(page))
1350                                         return pfn;
1351                                 else
1352                                         pfn = round_up(pfn + 1,
1353                                                 1 << compound_order(page)) - 1;
1354                         }
1355                 }
1356         }
1357         return 0;
1358 }
1359
1360 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
1361 static int
1362 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
1363 {
1364         unsigned long pfn;
1365         struct page *page;
1366         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
1367         int not_managed = 0;
1368         int ret = 0;
1369         LIST_HEAD(source);
1370
1371         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
1372                 if (!pfn_valid(pfn))
1373                         continue;
1374                 page = pfn_to_page(pfn);
1375
1376                 if (PageHuge(page)) {
1377                         struct page *head = compound_head(page);
1378                         pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
1379                         if (compound_order(head) > PFN_SECTION_SHIFT) {
1380                                 ret = -EBUSY;
1381                                 break;
1382                         }
1383                         if (isolate_huge_page(page, &source))
1384                                 move_pages -= 1 << compound_order(head);
1385                         continue;
1386                 }
1387
1388                 if (!get_page_unless_zero(page))
1389                         continue;
1390                 /*
1391                  * We can skip free pages. And we can only deal with pages on
1392                  * LRU.
1393                  */
1394                 ret = isolate_lru_page(page);
1395                 if (!ret) { /* Success */
1396                         put_page(page);
1397                         list_add_tail(&page->lru, &source);
1398                         move_pages--;
1399                         inc_zone_page_state(page, NR_ISOLATED_ANON +
1400                                             page_is_file_cache(page));
1401
1402                 } else {
1403 #ifdef CONFIG_DEBUG_VM
1404                         printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
1405                                pfn);
1406                         dump_page(page, "failed to remove from LRU");
1407 #endif
1408                         put_page(page);
1409                         /* Because we don't have big zone->lock. we should
1410                            check this again here. */
1411                         if (page_count(page)) {
1412                                 not_managed++;
1413                                 ret = -EBUSY;
1414                                 break;
1415                         }
1416                 }
1417         }
1418         if (!list_empty(&source)) {
1419                 if (not_managed) {
1420                         putback_movable_pages(&source);
1421                         goto out;
1422                 }
1423
1424                 /*
1425                  * alloc_migrate_target should be improooooved!!
1426                  * migrate_pages returns # of failed pages.
1427                  */
1428                 ret = migrate_pages(&source, alloc_migrate_target, NULL, 0,
1429                                         MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
1430                 if (ret)
1431                         putback_movable_pages(&source);
1432         }
1433 out:
1434         return ret;
1435 }
1436
1437 /*
1438  * remove from free_area[] and mark all as Reserved.
1439  */
1440 static int
1441 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
1442                         void *data)
1443 {
1444         __offline_isolated_pages(start, start + nr_pages);
1445         return 0;
1446 }
1447
1448 static void
1449 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
1450 {
1451         walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
1452                                 offline_isolated_pages_cb);
1453 }
1454
1455 /*
1456  * Check all pages in range, recoreded as memory resource, are isolated.
1457  */
1458 static int
1459 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
1460                         void *data)
1461 {
1462         int ret;
1463         long offlined = *(long *)data;
1464         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
1465         offlined = nr_pages;
1466         if (!ret)
1467                 *(long *)data += offlined;
1468         return ret;
1469 }
1470
1471 static long
1472 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
1473 {
1474         long offlined = 0;
1475         int ret;
1476
1477         ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
1478                         check_pages_isolated_cb);
1479         if (ret < 0)
1480                 offlined = (long)ret;
1481         return offlined;
1482 }
1483
1484 #ifdef CONFIG_MOVABLE_NODE
1485 /*
1486  * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
1487  * normal memory.
1488  */
1489 static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
1490 {
1491         return true;
1492 }
1493 #else /* CONFIG_MOVABLE_NODE */
1494 /* ensure the node has NORMAL memory if it is still online */
1495 static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
1496 {
1497         struct pglist_data *pgdat = zone->zone_pgdat;
1498         unsigned long present_pages = 0;
1499         enum zone_type zt;
1500
1501         for (zt = 0; zt <= ZONE_NORMAL; zt++)
1502                 present_pages += pgdat->node_zones[zt].present_pages;
1503
1504         if (present_pages > nr_pages)
1505                 return true;
1506
1507         present_pages = 0;
1508         for (; zt <= ZONE_MOVABLE; zt++)
1509                 present_pages += pgdat->node_zones[zt].present_pages;
1510
1511         /*
1512          * we can't offline the last normal memory until all
1513          * higher memory is offlined.
1514          */
1515         return present_pages == 0;
1516 }
1517 #endif /* CONFIG_MOVABLE_NODE */
1518
1519 static int __init cmdline_parse_movable_node(char *p)
1520 {
1521 #ifdef CONFIG_MOVABLE_NODE
1522         /*
1523          * Memory used by the kernel cannot be hot-removed because Linux
1524          * cannot migrate the kernel pages. When memory hotplug is
1525          * enabled, we should prevent memblock from allocating memory
1526          * for the kernel.
1527          *
1528          * ACPI SRAT records all hotpluggable memory ranges. But before
1529          * SRAT is parsed, we don't know about it.
1530          *
1531          * The kernel image is loaded into memory at very early time. We
1532          * cannot prevent this anyway. So on NUMA system, we set any
1533          * node the kernel resides in as un-hotpluggable.
1534          *
1535          * Since on modern servers, one node could have double-digit
1536          * gigabytes memory, we can assume the memory around the kernel
1537          * image is also un-hotpluggable. So before SRAT is parsed, just
1538          * allocate memory near the kernel image to try the best to keep
1539          * the kernel away from hotpluggable memory.
1540          */
1541         memblock_set_bottom_up(true);
1542         movable_node_enabled = true;
1543 #else
1544         pr_warn("movable_node option not supported\n");
1545 #endif
1546         return 0;
1547 }
1548 early_param("movable_node", cmdline_parse_movable_node);
1549
1550 /* check which state of node_states will be changed when offline memory */
1551 static void node_states_check_changes_offline(unsigned long nr_pages,
1552                 struct zone *zone, struct memory_notify *arg)
1553 {
1554         struct pglist_data *pgdat = zone->zone_pgdat;
1555         unsigned long present_pages = 0;
1556         enum zone_type zt, zone_last = ZONE_NORMAL;
1557
1558         /*
1559          * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
1560          * contains nodes which have zones of 0...ZONE_NORMAL,
1561          * set zone_last to ZONE_NORMAL.
1562          *
1563          * If we don't have HIGHMEM nor movable node,
1564          * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
1565          * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
1566          */
1567         if (N_MEMORY == N_NORMAL_MEMORY)
1568                 zone_last = ZONE_MOVABLE;
1569
1570         /*
1571          * check whether node_states[N_NORMAL_MEMORY] will be changed.
1572          * If the memory to be offline is in a zone of 0...zone_last,
1573          * and it is the last present memory, 0...zone_last will
1574          * become empty after offline , thus we can determind we will
1575          * need to clear the node from node_states[N_NORMAL_MEMORY].
1576          */
1577         for (zt = 0; zt <= zone_last; zt++)
1578                 present_pages += pgdat->node_zones[zt].present_pages;
1579         if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1580                 arg->status_change_nid_normal = zone_to_nid(zone);
1581         else
1582                 arg->status_change_nid_normal = -1;
1583
1584 #ifdef CONFIG_HIGHMEM
1585         /*
1586          * If we have movable node, node_states[N_HIGH_MEMORY]
1587          * contains nodes which have zones of 0...ZONE_HIGHMEM,
1588          * set zone_last to ZONE_HIGHMEM.
1589          *
1590          * If we don't have movable node, node_states[N_NORMAL_MEMORY]
1591          * contains nodes which have zones of 0...ZONE_MOVABLE,
1592          * set zone_last to ZONE_MOVABLE.
1593          */
1594         zone_last = ZONE_HIGHMEM;
1595         if (N_MEMORY == N_HIGH_MEMORY)
1596                 zone_last = ZONE_MOVABLE;
1597
1598         for (; zt <= zone_last; zt++)
1599                 present_pages += pgdat->node_zones[zt].present_pages;
1600         if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
1601                 arg->status_change_nid_high = zone_to_nid(zone);
1602         else
1603                 arg->status_change_nid_high = -1;
1604 #else
1605         arg->status_change_nid_high = arg->status_change_nid_normal;
1606 #endif
1607
1608         /*
1609          * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
1610          */
1611         zone_last = ZONE_MOVABLE;
1612
1613         /*
1614          * check whether node_states[N_HIGH_MEMORY] will be changed
1615          * If we try to offline the last present @nr_pages from the node,
1616          * we can determind we will need to clear the node from
1617          * node_states[N_HIGH_MEMORY].
1618          */
1619         for (; zt <= zone_last; zt++)
1620                 present_pages += pgdat->node_zones[zt].present_pages;
1621         if (nr_pages >= present_pages)
1622                 arg->status_change_nid = zone_to_nid(zone);
1623         else
1624                 arg->status_change_nid = -1;
1625 }
1626
1627 static void node_states_clear_node(int node, struct memory_notify *arg)
1628 {
1629         if (arg->status_change_nid_normal >= 0)
1630                 node_clear_state(node, N_NORMAL_MEMORY);
1631
1632         if ((N_MEMORY != N_NORMAL_MEMORY) &&
1633             (arg->status_change_nid_high >= 0))
1634                 node_clear_state(node, N_HIGH_MEMORY);
1635
1636         if ((N_MEMORY != N_HIGH_MEMORY) &&
1637             (arg->status_change_nid >= 0))
1638                 node_clear_state(node, N_MEMORY);
1639 }
1640
1641 static int __ref __offline_pages(unsigned long start_pfn,
1642                   unsigned long end_pfn, unsigned long timeout)
1643 {
1644         unsigned long pfn, nr_pages, expire;
1645         long offlined_pages;
1646         int ret, drain, retry_max, node;
1647         unsigned long flags;
1648         struct zone *zone;
1649         struct memory_notify arg;
1650
1651         /* at least, alignment against pageblock is necessary */
1652         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
1653                 return -EINVAL;
1654         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
1655                 return -EINVAL;
1656         /* This makes hotplug much easier...and readable.
1657            we assume this for now. .*/
1658         if (!test_pages_in_a_zone(start_pfn, end_pfn))
1659                 return -EINVAL;
1660
1661         mem_hotplug_begin();
1662
1663         zone = page_zone(pfn_to_page(start_pfn));
1664         node = zone_to_nid(zone);
1665         nr_pages = end_pfn - start_pfn;
1666
1667         ret = -EINVAL;
1668         if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
1669                 goto out;
1670
1671         /* set above range as isolated */
1672         ret = start_isolate_page_range(start_pfn, end_pfn,
1673                                        MIGRATE_MOVABLE, true);
1674         if (ret)
1675                 goto out;
1676
1677         arg.start_pfn = start_pfn;
1678         arg.nr_pages = nr_pages;
1679         node_states_check_changes_offline(nr_pages, zone, &arg);
1680
1681         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
1682         ret = notifier_to_errno(ret);
1683         if (ret)
1684                 goto failed_removal;
1685
1686         pfn = start_pfn;
1687         expire = jiffies + timeout;
1688         drain = 0;
1689         retry_max = 5;
1690 repeat:
1691         /* start memory hot removal */
1692         ret = -EAGAIN;
1693         if (time_after(jiffies, expire))
1694                 goto failed_removal;
1695         ret = -EINTR;
1696         if (signal_pending(current))
1697                 goto failed_removal;
1698         ret = 0;
1699         if (drain) {
1700                 lru_add_drain_all();
1701                 cond_resched();
1702                 drain_all_pages();
1703         }
1704
1705         pfn = scan_movable_pages(start_pfn, end_pfn);
1706         if (pfn) { /* We have movable pages */
1707                 ret = do_migrate_range(pfn, end_pfn);
1708                 if (!ret) {
1709                         drain = 1;
1710                         goto repeat;
1711                 } else {
1712                         if (ret < 0)
1713                                 if (--retry_max == 0)
1714                                         goto failed_removal;
1715                         yield();
1716                         drain = 1;
1717                         goto repeat;
1718                 }
1719         }
1720         /* drain all zone's lru pagevec, this is asynchronous... */
1721         lru_add_drain_all();
1722         yield();
1723         /* drain pcp pages, this is synchronous. */
1724         drain_all_pages();
1725         /*
1726          * dissolve free hugepages in the memory block before doing offlining
1727          * actually in order to make hugetlbfs's object counting consistent.
1728          */
1729         dissolve_free_huge_pages(start_pfn, end_pfn);
1730         /* check again */
1731         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
1732         if (offlined_pages < 0) {
1733                 ret = -EBUSY;
1734                 goto failed_removal;
1735         }
1736         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
1737         /* Ok, all of our target is isolated.
1738            We cannot do rollback at this point. */
1739         offline_isolated_pages(start_pfn, end_pfn);
1740         /* reset pagetype flags and makes migrate type to be MOVABLE */
1741         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1742         /* removal success */
1743         adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
1744         zone->present_pages -= offlined_pages;
1745
1746         pgdat_resize_lock(zone->zone_pgdat, &flags);
1747         zone->zone_pgdat->node_present_pages -= offlined_pages;
1748         pgdat_resize_unlock(zone->zone_pgdat, &flags);
1749
1750         init_per_zone_wmark_min();
1751
1752         if (!populated_zone(zone)) {
1753                 zone_pcp_reset(zone);
1754                 mutex_lock(&zonelists_mutex);
1755                 build_all_zonelists(NULL, NULL);
1756                 mutex_unlock(&zonelists_mutex);
1757         } else
1758                 zone_pcp_update(zone);
1759
1760         node_states_clear_node(node, &arg);
1761         if (arg.status_change_nid >= 0)
1762                 kswapd_stop(node);
1763
1764         vm_total_pages = nr_free_pagecache_pages();
1765         writeback_set_ratelimit();
1766
1767         memory_notify(MEM_OFFLINE, &arg);
1768         mem_hotplug_done();
1769         return 0;
1770
1771 failed_removal:
1772         printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
1773                (unsigned long long) start_pfn << PAGE_SHIFT,
1774                ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
1775         memory_notify(MEM_CANCEL_OFFLINE, &arg);
1776         /* pushback to free area */
1777         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1778
1779 out:
1780         mem_hotplug_done();
1781         return ret;
1782 }
1783
1784 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1785 {
1786         return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
1787 }
1788 #endif /* CONFIG_MEMORY_HOTREMOVE */
1789
1790 /**
1791  * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
1792  * @start_pfn: start pfn of the memory range
1793  * @end_pfn: end pfn of the memory range
1794  * @arg: argument passed to func
1795  * @func: callback for each memory section walked
1796  *
1797  * This function walks through all present mem sections in range
1798  * [start_pfn, end_pfn) and call func on each mem section.
1799  *
1800  * Returns the return value of func.
1801  */
1802 int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
1803                 void *arg, int (*func)(struct memory_block *, void *))
1804 {
1805         struct memory_block *mem = NULL;
1806         struct mem_section *section;
1807         unsigned long pfn, section_nr;
1808         int ret;
1809
1810         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1811                 section_nr = pfn_to_section_nr(pfn);
1812                 if (!present_section_nr(section_nr))
1813                         continue;
1814
1815                 section = __nr_to_section(section_nr);
1816                 /* same memblock? */
1817                 if (mem)
1818                         if ((section_nr >= mem->start_section_nr) &&
1819                             (section_nr <= mem->end_section_nr))
1820                                 continue;
1821
1822                 mem = find_memory_block_hinted(section, mem);
1823                 if (!mem)
1824                         continue;
1825
1826                 ret = func(mem, arg);
1827                 if (ret) {
1828                         kobject_put(&mem->dev.kobj);
1829                         return ret;
1830                 }
1831         }
1832
1833         if (mem)
1834                 kobject_put(&mem->dev.kobj);
1835
1836         return 0;
1837 }
1838
1839 #ifdef CONFIG_MEMORY_HOTREMOVE
1840 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
1841 {
1842         int ret = !is_memblock_offlined(mem);
1843
1844         if (unlikely(ret)) {
1845                 phys_addr_t beginpa, endpa;
1846
1847                 beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
1848                 endpa = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
1849                 pr_warn("removing memory fails, because memory "
1850                         "[%pa-%pa] is onlined\n",
1851                         &beginpa, &endpa);
1852         }
1853
1854         return ret;
1855 }
1856
1857 static int check_cpu_on_node(pg_data_t *pgdat)
1858 {
1859         int cpu;
1860
1861         for_each_present_cpu(cpu) {
1862                 if (cpu_to_node(cpu) == pgdat->node_id)
1863                         /*
1864                          * the cpu on this node isn't removed, and we can't
1865                          * offline this node.
1866                          */
1867                         return -EBUSY;
1868         }
1869
1870         return 0;
1871 }
1872
1873 static void unmap_cpu_on_node(pg_data_t *pgdat)
1874 {
1875 #ifdef CONFIG_ACPI_NUMA
1876         int cpu;
1877
1878         for_each_possible_cpu(cpu)
1879                 if (cpu_to_node(cpu) == pgdat->node_id)
1880                         numa_clear_node(cpu);
1881 #endif
1882 }
1883
1884 static int check_and_unmap_cpu_on_node(pg_data_t *pgdat)
1885 {
1886         int ret;
1887
1888         ret = check_cpu_on_node(pgdat);
1889         if (ret)
1890                 return ret;
1891
1892         /*
1893          * the node will be offlined when we come here, so we can clear
1894          * the cpu_to_node() now.
1895          */
1896
1897         unmap_cpu_on_node(pgdat);
1898         return 0;
1899 }
1900
1901 /**
1902  * try_offline_node
1903  *
1904  * Offline a node if all memory sections and cpus of the node are removed.
1905  *
1906  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1907  * and online/offline operations before this call.
1908  */
1909 void try_offline_node(int nid)
1910 {
1911         pg_data_t *pgdat = NODE_DATA(nid);
1912         unsigned long start_pfn = pgdat->node_start_pfn;
1913         unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1914         unsigned long pfn;
1915         int i;
1916
1917         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1918                 unsigned long section_nr = pfn_to_section_nr(pfn);
1919
1920                 if (!present_section_nr(section_nr))
1921                         continue;
1922
1923                 if (pfn_to_nid(pfn) != nid)
1924                         continue;
1925
1926                 /*
1927                  * some memory sections of this node are not removed, and we
1928                  * can't offline node now.
1929                  */
1930                 return;
1931         }
1932
1933         if (check_and_unmap_cpu_on_node(pgdat))
1934                 return;
1935
1936         /*
1937          * all memory/cpu of this node are removed, we can offline this
1938          * node now.
1939          */
1940         node_set_offline(nid);
1941         unregister_one_node(nid);
1942
1943         /* free waittable in each zone */
1944         for (i = 0; i < MAX_NR_ZONES; i++) {
1945                 struct zone *zone = pgdat->node_zones + i;
1946
1947                 /*
1948                  * wait_table may be allocated from boot memory,
1949                  * here only free if it's allocated by vmalloc.
1950                  */
1951                 if (is_vmalloc_addr(zone->wait_table))
1952                         vfree(zone->wait_table);
1953         }
1954
1955         /*
1956          * Since there is no way to guarentee the address of pgdat/zone is not
1957          * on stack of any kernel threads or used by other kernel objects
1958          * without reference counting or other symchronizing method, do not
1959          * reset node_data and free pgdat here. Just reset it to 0 and reuse
1960          * the memory when the node is online again.
1961          */
1962         memset(pgdat, 0, sizeof(*pgdat));
1963 }
1964 EXPORT_SYMBOL(try_offline_node);
1965
1966 /**
1967  * remove_memory
1968  *
1969  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
1970  * and online/offline operations before this call, as required by
1971  * try_offline_node().
1972  */
1973 void __ref remove_memory(int nid, u64 start, u64 size)
1974 {
1975         int ret;
1976
1977         BUG_ON(check_hotplug_memory_range(start, size));
1978
1979         mem_hotplug_begin();
1980
1981         /*
1982          * All memory blocks must be offlined before removing memory.  Check
1983          * whether all memory blocks in question are offline and trigger a BUG()
1984          * if this is not the case.
1985          */
1986         ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
1987                                 check_memblock_offlined_cb);
1988         if (ret)
1989                 BUG();
1990
1991         /* remove memmap entry */
1992         firmware_map_remove(start, start + size, "System RAM");
1993
1994         arch_remove_memory(start, size);
1995
1996         try_offline_node(nid);
1997
1998         mem_hotplug_done();
1999 }
2000 EXPORT_SYMBOL_GPL(remove_memory);
2001 #endif /* CONFIG_MEMORY_HOTREMOVE */