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