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