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/bootmem.h>
  13 #include <linux/compiler.h>
  14 #include <linux/export.h>
  15 #include <linux/pagevec.h>
  16 #include <linux/writeback.h>
  17 #include <linux/slab.h>
  18 #include <linux/sysctl.h>
  19 #include <linux/cpu.h>
  20 #include <linux/memory.h>
  21 #include <linux/memory_hotplug.h>
  22 #include <linux/highmem.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/ioport.h>
  25 #include <linux/delay.h>
  26 #include <linux/migrate.h>
  27 #include <linux/page-isolation.h>
  28 #include <linux/pfn.h>
  29 #include <linux/suspend.h>
  30 #include <linux/mm_inline.h>
  31 #include <linux/firmware-map.h>
  32
  33 #include <asm/tlbflush.h>
  34
  35 #include "internal.h"
  36
  37 /*
  38  * online_page_callback contains pointer to current page onlining function.
  39  * Initially it is generic_online_page(). If it is required it could be
  40  * changed by calling set_online_page_callback() for callback registration
  41  * and restore_online_page_callback() for generic callback restore.
  42  */
  43
  44 static void generic_online_page(struct page *page);
  45
  46 static online_page_callback_t online_page_callback = generic_online_page;
  47
  48 DEFINE_MUTEX(mem_hotplug_mutex);
  49
  50 void lock_memory_hotplug(void)
  51 {
  52         mutex_lock(&mem_hotplug_mutex);
  53
  54         /* for exclusive hibernation if CONFIG_HIBERNATION=y */
  55         lock_system_sleep();
  56 }
  57
  58 void unlock_memory_hotplug(void)
  59 {
  60         unlock_system_sleep();
  61         mutex_unlock(&mem_hotplug_mutex);
  62 }
  63
  64
  65 /* add this memory to iomem resource */
  66 static struct resource *register_memory_resource(u64 start, u64 size)
  67 {
  68         struct resource *res;
  69         res = kzalloc(sizeof(struct resource), GFP_KERNEL);
  70         BUG_ON(!res);
  71
  72         res->name = "System RAM";
  73         res->start = start;
  74         res->end = start + size - 1;
  75         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
  76         if (request_resource(&iomem_resource, res) < 0) {
  77                 printk("System RAM resource %llx - %llx cannot be added\n",
  78                 (unsigned long long)res->start, (unsigned long long)res->end);
  79                 kfree(res);
  80                 res = NULL;
  81         }
  82         return res;
  83 }
  84
  85 static void release_memory_resource(struct resource *res)
  86 {
  87         if (!res)
  88                 return;
  89         release_resource(res);
  90         kfree(res);
  91         return;
  92 }
  93
  94 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
  95 #ifndef CONFIG_SPARSEMEM_VMEMMAP
  96 static void get_page_bootmem(unsigned long info,  struct page *page,
  97                              unsigned long type)
  98 {
  99         page->lru.next = (struct list_head *) type;
 100         SetPagePrivate(page);
 101         set_page_private(page, info);
 102         atomic_inc(&page->_count);
 103 }
 104
 105 /* reference to __meminit __free_pages_bootmem is valid
 106  * so use __ref to tell modpost not to generate a warning */
 107 void __ref put_page_bootmem(struct page *page)
 108 {
 109         unsigned long type;
 110
 111         type = (unsigned long) page->lru.next;
 112         BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
 113                type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 114
 115         if (atomic_dec_return(&page->_count) == 1) {
 116                 ClearPagePrivate(page);
 117                 set_page_private(page, 0);
 118                 INIT_LIST_HEAD(&page->lru);
 119                 __free_pages_bootmem(page, 0);
 120         }
 121
 122 }
 123
 124 static void register_page_bootmem_info_section(unsigned long start_pfn)
 125 {
 126         unsigned long *usemap, mapsize, section_nr, i;
 127         struct mem_section *ms;
 128         struct page *page, *memmap;
 129
 130         section_nr = pfn_to_section_nr(start_pfn);
 131         ms = __nr_to_section(section_nr);
 132
 133         /* Get section's memmap address */
 134         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 135
 136         /*
 137          * Get page for the memmap's phys address
 138          * XXX: need more consideration for sparse_vmemmap...
 139          */
 140         page = virt_to_page(memmap);
 141         mapsize = sizeof(struct page) * PAGES_PER_SECTION;
 142         mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
 143
 144         /* remember memmap's page */
 145         for (i = 0; i < mapsize; i++, page++)
 146                 get_page_bootmem(section_nr, page, SECTION_INFO);
 147
 148         usemap = __nr_to_section(section_nr)->pageblock_flags;
 149         page = virt_to_page(usemap);
 150
 151         mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
 152
 153         for (i = 0; i < mapsize; i++, page++)
 154                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
 155
 156 }
 157
 158 void register_page_bootmem_info_node(struct pglist_data *pgdat)
 159 {
 160         unsigned long i, pfn, end_pfn, nr_pages;
 161         int node = pgdat->node_id;
 162         struct page *page;
 163         struct zone *zone;
 164
 165         nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
 166         page = virt_to_page(pgdat);
 167
 168         for (i = 0; i < nr_pages; i++, page++)
 169                 get_page_bootmem(node, page, NODE_INFO);
 170
 171         zone = &pgdat->node_zones[0];
 172         for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
 173                 if (zone->wait_table) {
 174                         nr_pages = zone->wait_table_hash_nr_entries
 175                                 * sizeof(wait_queue_head_t);
 176                         nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
 177                         page = virt_to_page(zone->wait_table);
 178
 179                         for (i = 0; i < nr_pages; i++, page++)
 180                                 get_page_bootmem(node, page, NODE_INFO);
 181                 }
 182         }
 183
 184         pfn = pgdat->node_start_pfn;
 185         end_pfn = pfn + pgdat->node_spanned_pages;
 186
 187         /* register_section info */
 188         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 189                 /*
 190                  * Some platforms can assign the same pfn to multiple nodes - on
 191                  * node0 as well as nodeN.  To avoid registering a pfn against
 192                  * multiple nodes we check that this pfn does not already
 193                  * reside in some other node.
 194                  */
 195                 if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
 196                         register_page_bootmem_info_section(pfn);
 197         }
 198 }
 199 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 200
 201 static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
 202                            unsigned long end_pfn)
 203 {
 204         unsigned long old_zone_end_pfn;
 205
 206         zone_span_writelock(zone);
 207
 208         old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
 209         if (start_pfn < zone->zone_start_pfn)
 210                 zone->zone_start_pfn = start_pfn;
 211
 212         zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
 213                                 zone->zone_start_pfn;
 214
 215         zone_span_writeunlock(zone);
 216 }
 217
 218 static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
 219                             unsigned long end_pfn)
 220 {
 221         unsigned long old_pgdat_end_pfn =
 222                 pgdat->node_start_pfn + pgdat->node_spanned_pages;
 223
 224         if (start_pfn < pgdat->node_start_pfn)
 225                 pgdat->node_start_pfn = start_pfn;
 226
 227         pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
 228                                         pgdat->node_start_pfn;
 229 }
 230
 231 static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
 232 {
 233         struct pglist_data *pgdat = zone->zone_pgdat;
 234         int nr_pages = PAGES_PER_SECTION;
 235         int nid = pgdat->node_id;
 236         int zone_type;
 237         unsigned long flags;
 238
 239         zone_type = zone - pgdat->node_zones;
 240         if (!zone->wait_table) {
 241                 int ret;
 242
 243                 ret = init_currently_empty_zone(zone, phys_start_pfn,
 244                                                 nr_pages, MEMMAP_HOTPLUG);
 245                 if (ret)
 246                         return ret;
 247         }
 248         pgdat_resize_lock(zone->zone_pgdat, &flags);
 249         grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
 250         grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
 251                         phys_start_pfn + nr_pages);
 252         pgdat_resize_unlock(zone->zone_pgdat, &flags);
 253         memmap_init_zone(nr_pages, nid, zone_type,
 254                          phys_start_pfn, MEMMAP_HOTPLUG);
 255         return 0;
 256 }
 257
 258 static int __meminit __add_section(int nid, struct zone *zone,
 259                                         unsigned long phys_start_pfn)
 260 {
 261         int nr_pages = PAGES_PER_SECTION;
 262         int ret;
 263
 264         if (pfn_valid(phys_start_pfn))
 265                 return -EEXIST;
 266
 267         ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
 268
 269         if (ret < 0)
 270                 return ret;
 271
 272         ret = __add_zone(zone, phys_start_pfn);
 273
 274         if (ret < 0)
 275                 return ret;
 276
 277         return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
 278 }
 279
 280 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 281 static int __remove_section(struct zone *zone, struct mem_section *ms)
 282 {
 283         /*
 284          * XXX: Freeing memmap with vmemmap is not implement yet.
 285          *      This should be removed later.
 286          */
 287         return -EBUSY;
 288 }
 289 #else
 290 static int __remove_section(struct zone *zone, struct mem_section *ms)
 291 {
 292         unsigned long flags;
 293         struct pglist_data *pgdat = zone->zone_pgdat;
 294         int ret = -EINVAL;
 295
 296         if (!valid_section(ms))
 297                 return ret;
 298
 299         ret = unregister_memory_section(ms);
 300         if (ret)
 301                 return ret;
 302
 303         pgdat_resize_lock(pgdat, &flags);
 304         sparse_remove_one_section(zone, ms);
 305         pgdat_resize_unlock(pgdat, &flags);
 306         return 0;
 307 }
 308 #endif
 309
 310 /*
 311  * Reasonably generic function for adding memory.  It is
 312  * expected that archs that support memory hotplug will
 313  * call this function after deciding the zone to which to
 314  * add the new pages.
 315  */
 316 int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
 317                         unsigned long nr_pages)
 318 {
 319         unsigned long i;
 320         int err = 0;
 321         int start_sec, end_sec;
 322         /* during initialize mem_map, align hot-added range to section */
 323         start_sec = pfn_to_section_nr(phys_start_pfn);
 324         end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
 325
 326         for (i = start_sec; i <= end_sec; i++) {
 327                 err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
 328
 329                 /*
 330                  * EEXIST is finally dealt with by ioresource collision
 331                  * check. see add_memory() => register_memory_resource()
 332                  * Warning will be printed if there is collision.
 333                  */
 334                 if (err && (err != -EEXIST))
 335                         break;
 336                 err = 0;
 337         }
 338
 339         return err;
 340 }
 341 EXPORT_SYMBOL_GPL(__add_pages);
 342
 343 /**
 344  * __remove_pages() - remove sections of pages from a zone
 345  * @zone: zone from which pages need to be removed
 346  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
 347  * @nr_pages: number of pages to remove (must be multiple of section size)
 348  *
 349  * Generic helper function to remove section mappings and sysfs entries
 350  * for the section of the memory we are removing. Caller needs to make
 351  * sure that pages are marked reserved and zones are adjust properly by
 352  * calling offline_pages().
 353  */
 354 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 355                  unsigned long nr_pages)
 356 {
 357         unsigned long i, ret = 0;
 358         int sections_to_remove;
 359
 360         /*
 361          * We can only remove entire sections
 362          */
 363         BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
 364         BUG_ON(nr_pages % PAGES_PER_SECTION);
 365
 366         sections_to_remove = nr_pages / PAGES_PER_SECTION;
 367         for (i = 0; i < sections_to_remove; i++) {
 368                 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
 369                 release_mem_region(pfn << PAGE_SHIFT,
 370                                    PAGES_PER_SECTION << PAGE_SHIFT);
 371                 ret = __remove_section(zone, __pfn_to_section(pfn));
 372                 if (ret)
 373                         break;
 374         }
 375         return ret;
 376 }
 377 EXPORT_SYMBOL_GPL(__remove_pages);
 378
 379 int set_online_page_callback(online_page_callback_t callback)
 380 {
 381         int rc = -EINVAL;
 382
 383         lock_memory_hotplug();
 384
 385         if (online_page_callback == generic_online_page) {
 386                 online_page_callback = callback;
 387                 rc = 0;
 388         }
 389
 390         unlock_memory_hotplug();
 391
 392         return rc;
 393 }
 394 EXPORT_SYMBOL_GPL(set_online_page_callback);
 395
 396 int restore_online_page_callback(online_page_callback_t callback)
 397 {
 398         int rc = -EINVAL;
 399
 400         lock_memory_hotplug();
 401
 402         if (online_page_callback == callback) {
 403                 online_page_callback = generic_online_page;
 404                 rc = 0;
 405         }
 406
 407         unlock_memory_hotplug();
 408
 409         return rc;
 410 }
 411 EXPORT_SYMBOL_GPL(restore_online_page_callback);
 412
 413 void __online_page_set_limits(struct page *page)
 414 {
 415         unsigned long pfn = page_to_pfn(page);
 416
 417         if (pfn >= num_physpages)
 418                 num_physpages = pfn + 1;
 419 }
 420 EXPORT_SYMBOL_GPL(__online_page_set_limits);
 421
 422 void __online_page_increment_counters(struct page *page)
 423 {
 424         totalram_pages++;
 425
 426 #ifdef CONFIG_HIGHMEM
 427         if (PageHighMem(page))
 428                 totalhigh_pages++;
 429 #endif
 430 }
 431 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 432
 433 void __online_page_free(struct page *page)
 434 {
 435         ClearPageReserved(page);
 436         init_page_count(page);
 437         __free_page(page);
 438 }
 439 EXPORT_SYMBOL_GPL(__online_page_free);
 440
 441 static void generic_online_page(struct page *page)
 442 {
 443         __online_page_set_limits(page);
 444         __online_page_increment_counters(page);
 445         __online_page_free(page);
 446 }
 447
 448 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 449                         void *arg)
 450 {
 451         unsigned long i;
 452         unsigned long onlined_pages = *(unsigned long *)arg;
 453         struct page *page;
 454         if (PageReserved(pfn_to_page(start_pfn)))
 455                 for (i = 0; i < nr_pages; i++) {
 456                         page = pfn_to_page(start_pfn + i);
 457                         (*online_page_callback)(page);
 458                         onlined_pages++;
 459                 }
 460         *(unsigned long *)arg = onlined_pages;
 461         return 0;
 462 }
 463
 464
 465 int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
 466 {
 467         unsigned long onlined_pages = 0;
 468         struct zone *zone;
 469         int need_zonelists_rebuild = 0;
 470         int nid;
 471         int ret;
 472         struct memory_notify arg;
 473
 474         lock_memory_hotplug();
 475         arg.start_pfn = pfn;
 476         arg.nr_pages = nr_pages;
 477         arg.status_change_nid = -1;
 478
 479         nid = page_to_nid(pfn_to_page(pfn));
 480         if (node_present_pages(nid) == 0)
 481                 arg.status_change_nid = nid;
 482
 483         ret = memory_notify(MEM_GOING_ONLINE, &arg);
 484         ret = notifier_to_errno(ret);
 485         if (ret) {
 486                 memory_notify(MEM_CANCEL_ONLINE, &arg);
 487                 unlock_memory_hotplug();
 488                 return ret;
 489         }
 490         /*
 491          * This doesn't need a lock to do pfn_to_page().
 492          * The section can't be removed here because of the
 493          * memory_block->state_mutex.
 494          */
 495         zone = page_zone(pfn_to_page(pfn));
 496         /*
 497          * If this zone is not populated, then it is not in zonelist.
 498          * This means the page allocator ignores this zone.
 499          * So, zonelist must be updated after online.
 500          */
 501         mutex_lock(&zonelists_mutex);
 502         if (!populated_zone(zone))
 503                 need_zonelists_rebuild = 1;
 504
 505         ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
 506                 online_pages_range);
 507         if (ret) {
 508                 mutex_unlock(&zonelists_mutex);
 509                 printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
 510                         nr_pages, pfn);
 511                 memory_notify(MEM_CANCEL_ONLINE, &arg);
 512                 unlock_memory_hotplug();
 513                 return ret;
 514         }
 515
 516         zone->present_pages += onlined_pages;
 517         zone->zone_pgdat->node_present_pages += onlined_pages;
 518         if (onlined_pages) {
 519                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 520                 if (need_zonelists_rebuild)
 521                         build_all_zonelists(zone);
 522                 else
 523                         zone_pcp_update(zone);
 524         }
 525
 526         mutex_unlock(&zonelists_mutex);
 527
 528         init_per_zone_wmark_min();
 529
 530         if (onlined_pages)
 531                 kswapd_run(zone_to_nid(zone));
 532
 533         vm_total_pages = nr_free_pagecache_pages();
 534
 535         writeback_set_ratelimit();
 536
 537         if (onlined_pages)
 538                 memory_notify(MEM_ONLINE, &arg);
 539         unlock_memory_hotplug();
 540
 541         return 0;
 542 }
 543 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 544
 545 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 546 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
 547 {
 548         struct pglist_data *pgdat;
 549         unsigned long zones_size[MAX_NR_ZONES] = {0};
 550         unsigned long zholes_size[MAX_NR_ZONES] = {0};
 551         unsigned long start_pfn = start >> PAGE_SHIFT;
 552
 553         pgdat = arch_alloc_nodedata(nid);
 554         if (!pgdat)
 555                 return NULL;
 556
 557         arch_refresh_nodedata(nid, pgdat);
 558
 559         /* we can use NODE_DATA(nid) from here */
 560
 561         /* init node's zones as empty zones, we don't have any present pages.*/
 562         free_area_init_node(nid, zones_size, start_pfn, zholes_size);
 563
 564         /*
 565          * The node we allocated has no zone fallback lists. For avoiding
 566          * to access not-initialized zonelist, build here.
 567          */
 568         mutex_lock(&zonelists_mutex);
 569         build_all_zonelists(NULL);
 570         mutex_unlock(&zonelists_mutex);
 571
 572         return pgdat;
 573 }
 574
 575 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 576 {
 577         arch_refresh_nodedata(nid, NULL);
 578         arch_free_nodedata(pgdat);
 579         return;
 580 }
 581
 582
 583 /*
 584  * called by cpu_up() to online a node without onlined memory.
 585  */
 586 int mem_online_node(int nid)
 587 {
 588         pg_data_t       *pgdat;
 589         int     ret;
 590
 591         lock_memory_hotplug();
 592         pgdat = hotadd_new_pgdat(nid, 0);
 593         if (!pgdat) {
 594                 ret = -ENOMEM;
 595                 goto out;
 596         }
 597         node_set_online(nid);
 598         ret = register_one_node(nid);
 599         BUG_ON(ret);
 600
 601 out:
 602         unlock_memory_hotplug();
 603         return ret;
 604 }
 605
 606 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 607 int __ref add_memory(int nid, u64 start, u64 size)
 608 {
 609         pg_data_t *pgdat = NULL;
 610         int new_pgdat = 0;
 611         struct resource *res;
 612         int ret;
 613
 614         lock_memory_hotplug();
 615
 616         res = register_memory_resource(start, size);
 617         ret = -EEXIST;
 618         if (!res)
 619                 goto out;
 620
 621         if (!node_online(nid)) {
 622                 pgdat = hotadd_new_pgdat(nid, start);
 623                 ret = -ENOMEM;
 624                 if (!pgdat)
 625                         goto out;
 626                 new_pgdat = 1;
 627         }
 628
 629         /* call arch's memory hotadd */
 630         ret = arch_add_memory(nid, start, size);
 631
 632         if (ret < 0)
 633                 goto error;
 634
 635         /* we online node here. we can't roll back from here. */
 636         node_set_online(nid);
 637
 638         if (new_pgdat) {
 639                 ret = register_one_node(nid);
 640                 /*
 641                  * If sysfs file of new node can't create, cpu on the node
 642                  * can't be hot-added. There is no rollback way now.
 643                  * So, check by BUG_ON() to catch it reluctantly..
 644                  */
 645                 BUG_ON(ret);
 646         }
 647
 648         /* create new memmap entry */
 649         firmware_map_add_hotplug(start, start + size, "System RAM");
 650
 651         goto out;
 652
 653 error:
 654         /* rollback pgdat allocation and others */
 655         if (new_pgdat)
 656                 rollback_node_hotadd(nid, pgdat);
 657         if (res)
 658                 release_memory_resource(res);
 659
 660 out:
 661         unlock_memory_hotplug();
 662         return ret;
 663 }
 664 EXPORT_SYMBOL_GPL(add_memory);
 665
 666 #ifdef CONFIG_MEMORY_HOTREMOVE
 667 /*
 668  * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
 669  * set and the size of the free page is given by page_order(). Using this,
 670  * the function determines if the pageblock contains only free pages.
 671  * Due to buddy contraints, a free page at least the size of a pageblock will
 672  * be located at the start of the pageblock
 673  */
 674 static inline int pageblock_free(struct page *page)
 675 {
 676         return PageBuddy(page) && page_order(page) >= pageblock_order;
 677 }
 678
 679 /* Return the start of the next active pageblock after a given page */
 680 static struct page *next_active_pageblock(struct page *page)
 681 {
 682         /* Ensure the starting page is pageblock-aligned */
 683         BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
 684
 685         /* If the entire pageblock is free, move to the end of free page */
 686         if (pageblock_free(page)) {
 687                 int order;
 688                 /* be careful. we don't have locks, page_order can be changed.*/
 689                 order = page_order(page);
 690                 if ((order < MAX_ORDER) && (order >= pageblock_order))
 691                         return page + (1 << order);
 692         }
 693
 694         return page + pageblock_nr_pages;
 695 }
 696
 697 /* Checks if this range of memory is likely to be hot-removable. */
 698 int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
 699 {
 700         struct page *page = pfn_to_page(start_pfn);
 701         struct page *end_page = page + nr_pages;
 702
 703         /* Check the starting page of each pageblock within the range */
 704         for (; page < end_page; page = next_active_pageblock(page)) {
 705                 if (!is_pageblock_removable_nolock(page))
 706                         return 0;
 707                 cond_resched();
 708         }
 709
 710         /* All pageblocks in the memory block are likely to be hot-removable */
 711         return 1;
 712 }
 713
 714 /*
 715  * Confirm all pages in a range [start, end) is belongs to the same zone.
 716  */
 717 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 718 {
 719         unsigned long pfn, sec_end_pfn;
 720         struct zone *zone = NULL;
 721         struct page *page;
 722         int i;
 723         for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
 724              pfn < end_pfn;
 725              pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
 726                 /* Make sure the memory section is present first */
 727                 if (!present_section_nr(pfn_to_section_nr(pfn)))
 728                         continue;
 729                 for (; pfn < sec_end_pfn && pfn < end_pfn;
 730                      pfn += MAX_ORDER_NR_PAGES) {
 731                         i = 0;
 732                         /* This is just a CONFIG_HOLES_IN_ZONE check.*/
 733                         while ((i < MAX_ORDER_NR_PAGES) &&
 734                                 !pfn_valid_within(pfn + i))
 735                                 i++;
 736                         if (i == MAX_ORDER_NR_PAGES)
 737                                 continue;
 738                         page = pfn_to_page(pfn + i);
 739                         if (zone && page_zone(page) != zone)
 740                                 return 0;
 741                         zone = page_zone(page);
 742                 }
 743         }
 744         return 1;
 745 }
 746
 747 /*
 748  * Scanning pfn is much easier than scanning lru list.
 749  * Scan pfn from start to end and Find LRU page.
 750  */
 751 static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
 752 {
 753         unsigned long pfn;
 754         struct page *page;
 755         for (pfn = start; pfn < end; pfn++) {
 756                 if (pfn_valid(pfn)) {
 757                         page = pfn_to_page(pfn);
 758                         if (PageLRU(page))
 759                                 return pfn;
 760                 }
 761         }
 762         return 0;
 763 }
 764
 765 static struct page *
 766 hotremove_migrate_alloc(struct page *page, unsigned long private, int **x)
 767 {
 768         /* This should be improooooved!! */
 769         return alloc_page(GFP_HIGHUSER_MOVABLE);
 770 }
 771
 772 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
 773 static int
 774 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 775 {
 776         unsigned long pfn;
 777         struct page *page;
 778         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
 779         int not_managed = 0;
 780         int ret = 0;
 781         LIST_HEAD(source);
 782
 783         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
 784                 if (!pfn_valid(pfn))
 785                         continue;
 786                 page = pfn_to_page(pfn);
 787                 if (!get_page_unless_zero(page))
 788                         continue;
 789                 /*
 790                  * We can skip free pages. And we can only deal with pages on
 791                  * LRU.
 792                  */
 793                 ret = isolate_lru_page(page);
 794                 if (!ret) { /* Success */
 795                         put_page(page);
 796                         list_add_tail(&page->lru, &source);
 797                         move_pages--;
 798                         inc_zone_page_state(page, NR_ISOLATED_ANON +
 799                                             page_is_file_cache(page));
 800
 801                 } else {
 802 #ifdef CONFIG_DEBUG_VM
 803                         printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
 804                                pfn);
 805                         dump_page(page);
 806 #endif
 807                         put_page(page);
 808                         /* Because we don't have big zone->lock. we should
 809                            check this again here. */
 810                         if (page_count(page)) {
 811                                 not_managed++;
 812                                 ret = -EBUSY;
 813                                 break;
 814                         }
 815                 }
 816         }
 817         if (!list_empty(&source)) {
 818                 if (not_managed) {
 819                         putback_lru_pages(&source);
 820                         goto out;
 821                 }
 822                 /* this function returns # of failed pages */
 823                 ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
 824                                                         true, MIGRATE_SYNC);
 825                 if (ret)
 826                         putback_lru_pages(&source);
 827         }
 828 out:
 829         return ret;
 830 }
 831
 832 /*
 833  * remove from free_area[] and mark all as Reserved.
 834  */
 835 static int
 836 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 837                         void *data)
 838 {
 839         __offline_isolated_pages(start, start + nr_pages);
 840         return 0;
 841 }
 842
 843 static void
 844 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 845 {
 846         walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
 847                                 offline_isolated_pages_cb);
 848 }
 849
 850 /*
 851  * Check all pages in range, recoreded as memory resource, are isolated.
 852  */
 853 static int
 854 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 855                         void *data)
 856 {
 857         int ret;
 858         long offlined = *(long *)data;
 859         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
 860         offlined = nr_pages;
 861         if (!ret)
 862                 *(long *)data += offlined;
 863         return ret;
 864 }
 865
 866 static long
 867 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 868 {
 869         long offlined = 0;
 870         int ret;
 871
 872         ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
 873                         check_pages_isolated_cb);
 874         if (ret < 0)
 875                 offlined = (long)ret;
 876         return offlined;
 877 }
 878
 879 static int __ref offline_pages(unsigned long start_pfn,
 880                   unsigned long end_pfn, unsigned long timeout)
 881 {
 882         unsigned long pfn, nr_pages, expire;
 883         long offlined_pages;
 884         int ret, drain, retry_max, node;
 885         struct zone *zone;
 886         struct memory_notify arg;
 887
 888         BUG_ON(start_pfn >= end_pfn);
 889         /* at least, alignment against pageblock is necessary */
 890         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
 891                 return -EINVAL;
 892         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
 893                 return -EINVAL;
 894         /* This makes hotplug much easier...and readable.
 895            we assume this for now. .*/
 896         if (!test_pages_in_a_zone(start_pfn, end_pfn))
 897                 return -EINVAL;
 898
 899         lock_memory_hotplug();
 900
 901         zone = page_zone(pfn_to_page(start_pfn));
 902         node = zone_to_nid(zone);
 903         nr_pages = end_pfn - start_pfn;
 904
 905         /* set above range as isolated */
 906         ret = start_isolate_page_range(start_pfn, end_pfn);
 907         if (ret)
 908                 goto out;
 909
 910         arg.start_pfn = start_pfn;
 911         arg.nr_pages = nr_pages;
 912         arg.status_change_nid = -1;
 913         if (nr_pages >= node_present_pages(node))
 914                 arg.status_change_nid = node;
 915
 916         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 917         ret = notifier_to_errno(ret);
 918         if (ret)
 919                 goto failed_removal;
 920
 921         pfn = start_pfn;
 922         expire = jiffies + timeout;
 923         drain = 0;
 924         retry_max = 5;
 925 repeat:
 926         /* start memory hot removal */
 927         ret = -EAGAIN;
 928         if (time_after(jiffies, expire))
 929                 goto failed_removal;
 930         ret = -EINTR;
 931         if (signal_pending(current))
 932                 goto failed_removal;
 933         ret = 0;
 934         if (drain) {
 935                 lru_add_drain_all();
 936                 cond_resched();
 937                 drain_all_pages();
 938         }
 939
 940         pfn = scan_lru_pages(start_pfn, end_pfn);
 941         if (pfn) { /* We have page on LRU */
 942                 ret = do_migrate_range(pfn, end_pfn);
 943                 if (!ret) {
 944                         drain = 1;
 945                         goto repeat;
 946                 } else {
 947                         if (ret < 0)
 948                                 if (--retry_max == 0)
 949                                         goto failed_removal;
 950                         yield();
 951                         drain = 1;
 952                         goto repeat;
 953                 }
 954         }
 955         /* drain all zone's lru pagevec, this is asyncronous... */
 956         lru_add_drain_all();
 957         yield();
 958         /* drain pcp pages , this is synchrouns. */
 959         drain_all_pages();
 960         /* check again */
 961         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 962         if (offlined_pages < 0) {
 963                 ret = -EBUSY;
 964                 goto failed_removal;
 965         }
 966         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
 967         /* Ok, all of our target is islaoted.
 968            We cannot do rollback at this point. */
 969         offline_isolated_pages(start_pfn, end_pfn);
 970         /* reset pagetype flags and makes migrate type to be MOVABLE */
 971         undo_isolate_page_range(start_pfn, end_pfn);
 972         /* removal success */
 973         zone->present_pages -= offlined_pages;
 974         zone->zone_pgdat->node_present_pages -= offlined_pages;
 975         totalram_pages -= offlined_pages;
 976
 977         init_per_zone_wmark_min();
 978
 979         if (!node_present_pages(node)) {
 980                 node_clear_state(node, N_HIGH_MEMORY);
 981                 kswapd_stop(node);
 982         }
 983
 984         vm_total_pages = nr_free_pagecache_pages();
 985         writeback_set_ratelimit();
 986
 987         memory_notify(MEM_OFFLINE, &arg);
 988         unlock_memory_hotplug();
 989         return 0;
 990
 991 failed_removal:
 992         printk(KERN_INFO "memory offlining %lx to %lx failed\n",
 993                 start_pfn, end_pfn);
 994         memory_notify(MEM_CANCEL_OFFLINE, &arg);
 995         /* pushback to free area */
 996         undo_isolate_page_range(start_pfn, end_pfn);
 997
 998 out:
 999         unlock_memory_hotplug();
1000         return ret;
1001 }
1002
1003 int remove_memory(u64 start, u64 size)
1004 {
1005         unsigned long start_pfn, end_pfn;
1006
1007         start_pfn = PFN_DOWN(start);
1008         end_pfn = start_pfn + PFN_DOWN(size);
1009         return offline_pages(start_pfn, end_pfn, 120 * HZ);
1010 }
1011 #else
1012 int remove_memory(u64 start, u64 size)
1013 {
1014         return -EINVAL;
1015 }
1016 #endif /* CONFIG_MEMORY_HOTREMOVE */
1017 EXPORT_SYMBOL_GPL(remove_memory);