linux/mm/memory_hotplug.c
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   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
  44static void generic_online_page(struct page *page);
  45
  46static online_page_callback_t online_page_callback = generic_online_page;
  47
  48DEFINE_MUTEX(mem_hotplug_mutex);
  49
  50void 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
  58void 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 */
  66static 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 %pR cannot be added\n", res);
  78                kfree(res);
  79                res = NULL;
  80        }
  81        return res;
  82}
  83
  84static void release_memory_resource(struct resource *res)
  85{
  86        if (!res)
  87                return;
  88        release_resource(res);
  89        kfree(res);
  90        return;
  91}
  92
  93#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
  94#ifndef CONFIG_SPARSEMEM_VMEMMAP
  95static void get_page_bootmem(unsigned long info,  struct page *page,
  96                             unsigned long type)
  97{
  98        page->lru.next = (struct list_head *) type;
  99        SetPagePrivate(page);
 100        set_page_private(page, info);
 101        atomic_inc(&page->_count);
 102}
 103
 104/* reference to __meminit __free_pages_bootmem is valid
 105 * so use __ref to tell modpost not to generate a warning */
 106void __ref put_page_bootmem(struct page *page)
 107{
 108        unsigned long type;
 109
 110        type = (unsigned long) page->lru.next;
 111        BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
 112               type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 113
 114        if (atomic_dec_return(&page->_count) == 1) {
 115                ClearPagePrivate(page);
 116                set_page_private(page, 0);
 117                INIT_LIST_HEAD(&page->lru);
 118                __free_pages_bootmem(page, 0);
 119        }
 120
 121}
 122
 123static void register_page_bootmem_info_section(unsigned long start_pfn)
 124{
 125        unsigned long *usemap, mapsize, section_nr, i;
 126        struct mem_section *ms;
 127        struct page *page, *memmap;
 128
 129        section_nr = pfn_to_section_nr(start_pfn);
 130        ms = __nr_to_section(section_nr);
 131
 132        /* Get section's memmap address */
 133        memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
 134
 135        /*
 136         * Get page for the memmap's phys address
 137         * XXX: need more consideration for sparse_vmemmap...
 138         */
 139        page = virt_to_page(memmap);
 140        mapsize = sizeof(struct page) * PAGES_PER_SECTION;
 141        mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
 142
 143        /* remember memmap's page */
 144        for (i = 0; i < mapsize; i++, page++)
 145                get_page_bootmem(section_nr, page, SECTION_INFO);
 146
 147        usemap = __nr_to_section(section_nr)->pageblock_flags;
 148        page = virt_to_page(usemap);
 149
 150        mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
 151
 152        for (i = 0; i < mapsize; i++, page++)
 153                get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
 154
 155}
 156
 157void register_page_bootmem_info_node(struct pglist_data *pgdat)
 158{
 159        unsigned long i, pfn, end_pfn, nr_pages;
 160        int node = pgdat->node_id;
 161        struct page *page;
 162        struct zone *zone;
 163
 164        nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
 165        page = virt_to_page(pgdat);
 166
 167        for (i = 0; i < nr_pages; i++, page++)
 168                get_page_bootmem(node, page, NODE_INFO);
 169
 170        zone = &pgdat->node_zones[0];
 171        for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
 172                if (zone->wait_table) {
 173                        nr_pages = zone->wait_table_hash_nr_entries
 174                                * sizeof(wait_queue_head_t);
 175                        nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
 176                        page = virt_to_page(zone->wait_table);
 177
 178                        for (i = 0; i < nr_pages; i++, page++)
 179                                get_page_bootmem(node, page, NODE_INFO);
 180                }
 181        }
 182
 183        pfn = pgdat->node_start_pfn;
 184        end_pfn = pfn + pgdat->node_spanned_pages;
 185
 186        /* register_section info */
 187        for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 188                /*
 189                 * Some platforms can assign the same pfn to multiple nodes - on
 190                 * node0 as well as nodeN.  To avoid registering a pfn against
 191                 * multiple nodes we check that this pfn does not already
 192                 * reside in some other node.
 193                 */
 194                if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
 195                        register_page_bootmem_info_section(pfn);
 196        }
 197}
 198#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
 199
 200static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
 201                           unsigned long end_pfn)
 202{
 203        unsigned long old_zone_end_pfn;
 204
 205        zone_span_writelock(zone);
 206
 207        old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
 208        if (start_pfn < zone->zone_start_pfn)
 209                zone->zone_start_pfn = start_pfn;
 210
 211        zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
 212                                zone->zone_start_pfn;
 213
 214        zone_span_writeunlock(zone);
 215}
 216
 217static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
 218                            unsigned long end_pfn)
 219{
 220        unsigned long old_pgdat_end_pfn =
 221                pgdat->node_start_pfn + pgdat->node_spanned_pages;
 222
 223        if (start_pfn < pgdat->node_start_pfn)
 224                pgdat->node_start_pfn = start_pfn;
 225
 226        pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
 227                                        pgdat->node_start_pfn;
 228}
 229
 230static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
 231{
 232        struct pglist_data *pgdat = zone->zone_pgdat;
 233        int nr_pages = PAGES_PER_SECTION;
 234        int nid = pgdat->node_id;
 235        int zone_type;
 236        unsigned long flags;
 237
 238        zone_type = zone - pgdat->node_zones;
 239        if (!zone->wait_table) {
 240                int ret;
 241
 242                ret = init_currently_empty_zone(zone, phys_start_pfn,
 243                                                nr_pages, MEMMAP_HOTPLUG);
 244                if (ret)
 245                        return ret;
 246        }
 247        pgdat_resize_lock(zone->zone_pgdat, &flags);
 248        grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
 249        grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
 250                        phys_start_pfn + nr_pages);
 251        pgdat_resize_unlock(zone->zone_pgdat, &flags);
 252        memmap_init_zone(nr_pages, nid, zone_type,
 253                         phys_start_pfn, MEMMAP_HOTPLUG);
 254        return 0;
 255}
 256
 257static int __meminit __add_section(int nid, struct zone *zone,
 258                                        unsigned long phys_start_pfn)
 259{
 260        int nr_pages = PAGES_PER_SECTION;
 261        int ret;
 262
 263        if (pfn_valid(phys_start_pfn))
 264                return -EEXIST;
 265
 266        ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
 267
 268        if (ret < 0)
 269                return ret;
 270
 271        ret = __add_zone(zone, phys_start_pfn);
 272
 273        if (ret < 0)
 274                return ret;
 275
 276        return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
 277}
 278
 279#ifdef CONFIG_SPARSEMEM_VMEMMAP
 280static int __remove_section(struct zone *zone, struct mem_section *ms)
 281{
 282        /*
 283         * XXX: Freeing memmap with vmemmap is not implement yet.
 284         *      This should be removed later.
 285         */
 286        return -EBUSY;
 287}
 288#else
 289static int __remove_section(struct zone *zone, struct mem_section *ms)
 290{
 291        unsigned long flags;
 292        struct pglist_data *pgdat = zone->zone_pgdat;
 293        int ret = -EINVAL;
 294
 295        if (!valid_section(ms))
 296                return ret;
 297
 298        ret = unregister_memory_section(ms);
 299        if (ret)
 300                return ret;
 301
 302        pgdat_resize_lock(pgdat, &flags);
 303        sparse_remove_one_section(zone, ms);
 304        pgdat_resize_unlock(pgdat, &flags);
 305        return 0;
 306}
 307#endif
 308
 309/*
 310 * Reasonably generic function for adding memory.  It is
 311 * expected that archs that support memory hotplug will
 312 * call this function after deciding the zone to which to
 313 * add the new pages.
 314 */
 315int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
 316                        unsigned long nr_pages)
 317{
 318        unsigned long i;
 319        int err = 0;
 320        int start_sec, end_sec;
 321        /* during initialize mem_map, align hot-added range to section */
 322        start_sec = pfn_to_section_nr(phys_start_pfn);
 323        end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
 324
 325        for (i = start_sec; i <= end_sec; i++) {
 326                err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
 327
 328                /*
 329                 * EEXIST is finally dealt with by ioresource collision
 330                 * check. see add_memory() => register_memory_resource()
 331                 * Warning will be printed if there is collision.
 332                 */
 333                if (err && (err != -EEXIST))
 334                        break;
 335                err = 0;
 336        }
 337
 338        return err;
 339}
 340EXPORT_SYMBOL_GPL(__add_pages);
 341
 342/**
 343 * __remove_pages() - remove sections of pages from a zone
 344 * @zone: zone from which pages need to be removed
 345 * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
 346 * @nr_pages: number of pages to remove (must be multiple of section size)
 347 *
 348 * Generic helper function to remove section mappings and sysfs entries
 349 * for the section of the memory we are removing. Caller needs to make
 350 * sure that pages are marked reserved and zones are adjust properly by
 351 * calling offline_pages().
 352 */
 353int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 354                 unsigned long nr_pages)
 355{
 356        unsigned long i, ret = 0;
 357        int sections_to_remove;
 358
 359        /*
 360         * We can only remove entire sections
 361         */
 362        BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
 363        BUG_ON(nr_pages % PAGES_PER_SECTION);
 364
 365        release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
 366
 367        sections_to_remove = nr_pages / PAGES_PER_SECTION;
 368        for (i = 0; i < sections_to_remove; i++) {
 369                unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
 370                ret = __remove_section(zone, __pfn_to_section(pfn));
 371                if (ret)
 372                        break;
 373        }
 374        return ret;
 375}
 376EXPORT_SYMBOL_GPL(__remove_pages);
 377
 378int set_online_page_callback(online_page_callback_t callback)
 379{
 380        int rc = -EINVAL;
 381
 382        lock_memory_hotplug();
 383
 384        if (online_page_callback == generic_online_page) {
 385                online_page_callback = callback;
 386                rc = 0;
 387        }
 388
 389        unlock_memory_hotplug();
 390
 391        return rc;
 392}
 393EXPORT_SYMBOL_GPL(set_online_page_callback);
 394
 395int restore_online_page_callback(online_page_callback_t callback)
 396{
 397        int rc = -EINVAL;
 398
 399        lock_memory_hotplug();
 400
 401        if (online_page_callback == callback) {
 402                online_page_callback = generic_online_page;
 403                rc = 0;
 404        }
 405
 406        unlock_memory_hotplug();
 407
 408        return rc;
 409}
 410EXPORT_SYMBOL_GPL(restore_online_page_callback);
 411
 412void __online_page_set_limits(struct page *page)
 413{
 414        unsigned long pfn = page_to_pfn(page);
 415
 416        if (pfn >= num_physpages)
 417                num_physpages = pfn + 1;
 418}
 419EXPORT_SYMBOL_GPL(__online_page_set_limits);
 420
 421void __online_page_increment_counters(struct page *page)
 422{
 423        totalram_pages++;
 424
 425#ifdef CONFIG_HIGHMEM
 426        if (PageHighMem(page))
 427                totalhigh_pages++;
 428#endif
 429}
 430EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 431
 432void __online_page_free(struct page *page)
 433{
 434        ClearPageReserved(page);
 435        init_page_count(page);
 436        __free_page(page);
 437}
 438EXPORT_SYMBOL_GPL(__online_page_free);
 439
 440static void generic_online_page(struct page *page)
 441{
 442        __online_page_set_limits(page);
 443        __online_page_increment_counters(page);
 444        __online_page_free(page);
 445}
 446
 447static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 448                        void *arg)
 449{
 450        unsigned long i;
 451        unsigned long onlined_pages = *(unsigned long *)arg;
 452        struct page *page;
 453        if (PageReserved(pfn_to_page(start_pfn)))
 454                for (i = 0; i < nr_pages; i++) {
 455                        page = pfn_to_page(start_pfn + i);
 456                        (*online_page_callback)(page);
 457                        onlined_pages++;
 458                }
 459        *(unsigned long *)arg = onlined_pages;
 460        return 0;
 461}
 462
 463
 464int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
 465{
 466        unsigned long onlined_pages = 0;
 467        struct zone *zone;
 468        int need_zonelists_rebuild = 0;
 469        int nid;
 470        int ret;
 471        struct memory_notify arg;
 472
 473        lock_memory_hotplug();
 474        arg.start_pfn = pfn;
 475        arg.nr_pages = nr_pages;
 476        arg.status_change_nid = -1;
 477
 478        nid = page_to_nid(pfn_to_page(pfn));
 479        if (node_present_pages(nid) == 0)
 480                arg.status_change_nid = nid;
 481
 482        ret = memory_notify(MEM_GOING_ONLINE, &arg);
 483        ret = notifier_to_errno(ret);
 484        if (ret) {
 485                memory_notify(MEM_CANCEL_ONLINE, &arg);
 486                unlock_memory_hotplug();
 487                return ret;
 488        }
 489        /*
 490         * This doesn't need a lock to do pfn_to_page().
 491         * The section can't be removed here because of the
 492         * memory_block->state_mutex.
 493         */
 494        zone = page_zone(pfn_to_page(pfn));
 495        /*
 496         * If this zone is not populated, then it is not in zonelist.
 497         * This means the page allocator ignores this zone.
 498         * So, zonelist must be updated after online.
 499         */
 500        mutex_lock(&zonelists_mutex);
 501        if (!populated_zone(zone))
 502                need_zonelists_rebuild = 1;
 503
 504        ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
 505                online_pages_range);
 506        if (ret) {
 507                mutex_unlock(&zonelists_mutex);
 508                printk(KERN_DEBUG "online_pages [mem %#010llx-%#010llx] failed\n",
 509                       (unsigned long long) pfn << PAGE_SHIFT,
 510                       (((unsigned long long) pfn + nr_pages)
 511                            << PAGE_SHIFT) - 1);
 512                memory_notify(MEM_CANCEL_ONLINE, &arg);
 513                unlock_memory_hotplug();
 514                return ret;
 515        }
 516
 517        zone->present_pages += onlined_pages;
 518        zone->zone_pgdat->node_present_pages += onlined_pages;
 519        if (onlined_pages) {
 520                node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 521                if (need_zonelists_rebuild)
 522                        build_all_zonelists(NULL, zone);
 523                else
 524                        zone_pcp_update(zone);
 525        }
 526
 527        mutex_unlock(&zonelists_mutex);
 528
 529        init_per_zone_wmark_min();
 530
 531        if (onlined_pages)
 532                kswapd_run(zone_to_nid(zone));
 533
 534        vm_total_pages = nr_free_pagecache_pages();
 535
 536        writeback_set_ratelimit();
 537
 538        if (onlined_pages)
 539                memory_notify(MEM_ONLINE, &arg);
 540        unlock_memory_hotplug();
 541
 542        return 0;
 543}
 544#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 545
 546/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 547static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
 548{
 549        struct pglist_data *pgdat;
 550        unsigned long zones_size[MAX_NR_ZONES] = {0};
 551        unsigned long zholes_size[MAX_NR_ZONES] = {0};
 552        unsigned long start_pfn = start >> PAGE_SHIFT;
 553
 554        pgdat = arch_alloc_nodedata(nid);
 555        if (!pgdat)
 556                return NULL;
 557
 558        arch_refresh_nodedata(nid, pgdat);
 559
 560        /* we can use NODE_DATA(nid) from here */
 561
 562        /* init node's zones as empty zones, we don't have any present pages.*/
 563        free_area_init_node(nid, zones_size, start_pfn, zholes_size);
 564
 565        /*
 566         * The node we allocated has no zone fallback lists. For avoiding
 567         * to access not-initialized zonelist, build here.
 568         */
 569        mutex_lock(&zonelists_mutex);
 570        build_all_zonelists(pgdat, NULL);
 571        mutex_unlock(&zonelists_mutex);
 572
 573        return pgdat;
 574}
 575
 576static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 577{
 578        arch_refresh_nodedata(nid, NULL);
 579        arch_free_nodedata(pgdat);
 580        return;
 581}
 582
 583
 584/*
 585 * called by cpu_up() to online a node without onlined memory.
 586 */
 587int mem_online_node(int nid)
 588{
 589        pg_data_t       *pgdat;
 590        int     ret;
 591
 592        lock_memory_hotplug();
 593        pgdat = hotadd_new_pgdat(nid, 0);
 594        if (!pgdat) {
 595                ret = -ENOMEM;
 596                goto out;
 597        }
 598        node_set_online(nid);
 599        ret = register_one_node(nid);
 600        BUG_ON(ret);
 601
 602out:
 603        unlock_memory_hotplug();
 604        return ret;
 605}
 606
 607/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 608int __ref add_memory(int nid, u64 start, u64 size)
 609{
 610        pg_data_t *pgdat = NULL;
 611        int new_pgdat = 0;
 612        struct resource *res;
 613        int ret;
 614
 615        lock_memory_hotplug();
 616
 617        res = register_memory_resource(start, size);
 618        ret = -EEXIST;
 619        if (!res)
 620                goto out;
 621
 622        if (!node_online(nid)) {
 623                pgdat = hotadd_new_pgdat(nid, start);
 624                ret = -ENOMEM;
 625                if (!pgdat)
 626                        goto error;
 627                new_pgdat = 1;
 628        }
 629
 630        /* call arch's memory hotadd */
 631        ret = arch_add_memory(nid, start, size);
 632
 633        if (ret < 0)
 634                goto error;
 635
 636        /* we online node here. we can't roll back from here. */
 637        node_set_online(nid);
 638
 639        if (new_pgdat) {
 640                ret = register_one_node(nid);
 641                /*
 642                 * If sysfs file of new node can't create, cpu on the node
 643                 * can't be hot-added. There is no rollback way now.
 644                 * So, check by BUG_ON() to catch it reluctantly..
 645                 */
 646                BUG_ON(ret);
 647        }
 648
 649        /* create new memmap entry */
 650        firmware_map_add_hotplug(start, start + size, "System RAM");
 651
 652        goto out;
 653
 654error:
 655        /* rollback pgdat allocation and others */
 656        if (new_pgdat)
 657                rollback_node_hotadd(nid, pgdat);
 658        if (res)
 659                release_memory_resource(res);
 660
 661out:
 662        unlock_memory_hotplug();
 663        return ret;
 664}
 665EXPORT_SYMBOL_GPL(add_memory);
 666
 667#ifdef CONFIG_MEMORY_HOTREMOVE
 668/*
 669 * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
 670 * set and the size of the free page is given by page_order(). Using this,
 671 * the function determines if the pageblock contains only free pages.
 672 * Due to buddy contraints, a free page at least the size of a pageblock will
 673 * be located at the start of the pageblock
 674 */
 675static inline int pageblock_free(struct page *page)
 676{
 677        return PageBuddy(page) && page_order(page) >= pageblock_order;
 678}
 679
 680/* Return the start of the next active pageblock after a given page */
 681static struct page *next_active_pageblock(struct page *page)
 682{
 683        /* Ensure the starting page is pageblock-aligned */
 684        BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
 685
 686        /* If the entire pageblock is free, move to the end of free page */
 687        if (pageblock_free(page)) {
 688                int order;
 689                /* be careful. we don't have locks, page_order can be changed.*/
 690                order = page_order(page);
 691                if ((order < MAX_ORDER) && (order >= pageblock_order))
 692                        return page + (1 << order);
 693        }
 694
 695        return page + pageblock_nr_pages;
 696}
 697
 698/* Checks if this range of memory is likely to be hot-removable. */
 699int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
 700{
 701        struct page *page = pfn_to_page(start_pfn);
 702        struct page *end_page = page + nr_pages;
 703
 704        /* Check the starting page of each pageblock within the range */
 705        for (; page < end_page; page = next_active_pageblock(page)) {
 706                if (!is_pageblock_removable_nolock(page))
 707                        return 0;
 708                cond_resched();
 709        }
 710
 711        /* All pageblocks in the memory block are likely to be hot-removable */
 712        return 1;
 713}
 714
 715/*
 716 * Confirm all pages in a range [start, end) is belongs to the same zone.
 717 */
 718static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 719{
 720        unsigned long pfn;
 721        struct zone *zone = NULL;
 722        struct page *page;
 723        int i;
 724        for (pfn = start_pfn;
 725             pfn < end_pfn;
 726             pfn += MAX_ORDER_NR_PAGES) {
 727                i = 0;
 728                /* This is just a CONFIG_HOLES_IN_ZONE check.*/
 729                while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
 730                        i++;
 731                if (i == MAX_ORDER_NR_PAGES)
 732                        continue;
 733                page = pfn_to_page(pfn + i);
 734                if (zone && page_zone(page) != zone)
 735                        return 0;
 736                zone = page_zone(page);
 737        }
 738        return 1;
 739}
 740
 741/*
 742 * Scanning pfn is much easier than scanning lru list.
 743 * Scan pfn from start to end and Find LRU page.
 744 */
 745static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
 746{
 747        unsigned long pfn;
 748        struct page *page;
 749        for (pfn = start; pfn < end; pfn++) {
 750                if (pfn_valid(pfn)) {
 751                        page = pfn_to_page(pfn);
 752                        if (PageLRU(page))
 753                                return pfn;
 754                }
 755        }
 756        return 0;
 757}
 758
 759#define NR_OFFLINE_AT_ONCE_PAGES        (256)
 760static int
 761do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 762{
 763        unsigned long pfn;
 764        struct page *page;
 765        int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
 766        int not_managed = 0;
 767        int ret = 0;
 768        LIST_HEAD(source);
 769
 770        for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
 771                if (!pfn_valid(pfn))
 772                        continue;
 773                page = pfn_to_page(pfn);
 774                if (!get_page_unless_zero(page))
 775                        continue;
 776                /*
 777                 * We can skip free pages. And we can only deal with pages on
 778                 * LRU.
 779                 */
 780                ret = isolate_lru_page(page);
 781                if (!ret) { /* Success */
 782                        put_page(page);
 783                        list_add_tail(&page->lru, &source);
 784                        move_pages--;
 785                        inc_zone_page_state(page, NR_ISOLATED_ANON +
 786                                            page_is_file_cache(page));
 787
 788                } else {
 789#ifdef CONFIG_DEBUG_VM
 790                        printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
 791                               pfn);
 792                        dump_page(page);
 793#endif
 794                        put_page(page);
 795                        /* Because we don't have big zone->lock. we should
 796                           check this again here. */
 797                        if (page_count(page)) {
 798                                not_managed++;
 799                                ret = -EBUSY;
 800                                break;
 801                        }
 802                }
 803        }
 804        if (!list_empty(&source)) {
 805                if (not_managed) {
 806                        putback_lru_pages(&source);
 807                        goto out;
 808                }
 809
 810                /*
 811                 * alloc_migrate_target should be improooooved!!
 812                 * migrate_pages returns # of failed pages.
 813                 */
 814                ret = migrate_pages(&source, alloc_migrate_target, 0,
 815                                                        true, MIGRATE_SYNC);
 816                if (ret)
 817                        putback_lru_pages(&source);
 818        }
 819out:
 820        return ret;
 821}
 822
 823/*
 824 * remove from free_area[] and mark all as Reserved.
 825 */
 826static int
 827offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 828                        void *data)
 829{
 830        __offline_isolated_pages(start, start + nr_pages);
 831        return 0;
 832}
 833
 834static void
 835offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 836{
 837        walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
 838                                offline_isolated_pages_cb);
 839}
 840
 841/*
 842 * Check all pages in range, recoreded as memory resource, are isolated.
 843 */
 844static int
 845check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 846                        void *data)
 847{
 848        int ret;
 849        long offlined = *(long *)data;
 850        ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
 851        offlined = nr_pages;
 852        if (!ret)
 853                *(long *)data += offlined;
 854        return ret;
 855}
 856
 857static long
 858check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 859{
 860        long offlined = 0;
 861        int ret;
 862
 863        ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
 864                        check_pages_isolated_cb);
 865        if (ret < 0)
 866                offlined = (long)ret;
 867        return offlined;
 868}
 869
 870static int __ref __offline_pages(unsigned long start_pfn,
 871                  unsigned long end_pfn, unsigned long timeout)
 872{
 873        unsigned long pfn, nr_pages, expire;
 874        long offlined_pages;
 875        int ret, drain, retry_max, node;
 876        struct zone *zone;
 877        struct memory_notify arg;
 878
 879        BUG_ON(start_pfn >= end_pfn);
 880        /* at least, alignment against pageblock is necessary */
 881        if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
 882                return -EINVAL;
 883        if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
 884                return -EINVAL;
 885        /* This makes hotplug much easier...and readable.
 886           we assume this for now. .*/
 887        if (!test_pages_in_a_zone(start_pfn, end_pfn))
 888                return -EINVAL;
 889
 890        lock_memory_hotplug();
 891
 892        zone = page_zone(pfn_to_page(start_pfn));
 893        node = zone_to_nid(zone);
 894        nr_pages = end_pfn - start_pfn;
 895
 896        /* set above range as isolated */
 897        ret = start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 898        if (ret)
 899                goto out;
 900
 901        arg.start_pfn = start_pfn;
 902        arg.nr_pages = nr_pages;
 903        arg.status_change_nid = -1;
 904        if (nr_pages >= node_present_pages(node))
 905                arg.status_change_nid = node;
 906
 907        ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 908        ret = notifier_to_errno(ret);
 909        if (ret)
 910                goto failed_removal;
 911
 912        pfn = start_pfn;
 913        expire = jiffies + timeout;
 914        drain = 0;
 915        retry_max = 5;
 916repeat:
 917        /* start memory hot removal */
 918        ret = -EAGAIN;
 919        if (time_after(jiffies, expire))
 920                goto failed_removal;
 921        ret = -EINTR;
 922        if (signal_pending(current))
 923                goto failed_removal;
 924        ret = 0;
 925        if (drain) {
 926                lru_add_drain_all();
 927                cond_resched();
 928                drain_all_pages();
 929        }
 930
 931        pfn = scan_lru_pages(start_pfn, end_pfn);
 932        if (pfn) { /* We have page on LRU */
 933                ret = do_migrate_range(pfn, end_pfn);
 934                if (!ret) {
 935                        drain = 1;
 936                        goto repeat;
 937                } else {
 938                        if (ret < 0)
 939                                if (--retry_max == 0)
 940                                        goto failed_removal;
 941                        yield();
 942                        drain = 1;
 943                        goto repeat;
 944                }
 945        }
 946        /* drain all zone's lru pagevec, this is asyncronous... */
 947        lru_add_drain_all();
 948        yield();
 949        /* drain pcp pages , this is synchrouns. */
 950        drain_all_pages();
 951        /* check again */
 952        offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 953        if (offlined_pages < 0) {
 954                ret = -EBUSY;
 955                goto failed_removal;
 956        }
 957        printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
 958        /* Ok, all of our target is islaoted.
 959           We cannot do rollback at this point. */
 960        offline_isolated_pages(start_pfn, end_pfn);
 961        /* reset pagetype flags and makes migrate type to be MOVABLE */
 962        undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 963        /* removal success */
 964        zone->present_pages -= offlined_pages;
 965        zone->zone_pgdat->node_present_pages -= offlined_pages;
 966        totalram_pages -= offlined_pages;
 967
 968        init_per_zone_wmark_min();
 969
 970        if (!populated_zone(zone)) {
 971                zone_pcp_reset(zone);
 972                mutex_lock(&zonelists_mutex);
 973                build_all_zonelists(NULL, NULL);
 974                mutex_unlock(&zonelists_mutex);
 975        } else
 976                zone_pcp_update(zone);
 977
 978        if (!node_present_pages(node)) {
 979                node_clear_state(node, N_HIGH_MEMORY);
 980                kswapd_stop(node);
 981        }
 982
 983        vm_total_pages = nr_free_pagecache_pages();
 984        writeback_set_ratelimit();
 985
 986        memory_notify(MEM_OFFLINE, &arg);
 987        unlock_memory_hotplug();
 988        return 0;
 989
 990failed_removal:
 991        printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
 992               (unsigned long long) start_pfn << PAGE_SHIFT,
 993               ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
 994        memory_notify(MEM_CANCEL_OFFLINE, &arg);
 995        /* pushback to free area */
 996        undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 997
 998out:
 999        unlock_memory_hotplug();
1000        return ret;
1001}
1002
1003int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1004{
1005        return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
1006}
1007
1008int remove_memory(u64 start, u64 size)
1009{
1010        struct memory_block *mem = NULL;
1011        struct mem_section *section;
1012        unsigned long start_pfn, end_pfn;
1013        unsigned long pfn, section_nr;
1014        int ret;
1015
1016        start_pfn = PFN_DOWN(start);
1017        end_pfn = start_pfn + PFN_DOWN(size);
1018
1019        for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1020                section_nr = pfn_to_section_nr(pfn);
1021                if (!present_section_nr(section_nr))
1022                        continue;
1023
1024                section = __nr_to_section(section_nr);
1025                /* same memblock? */
1026                if (mem)
1027                        if ((section_nr >= mem->start_section_nr) &&
1028                            (section_nr <= mem->end_section_nr))
1029                                continue;
1030
1031                mem = find_memory_block_hinted(section, mem);
1032                if (!mem)
1033                        continue;
1034
1035                ret = offline_memory_block(mem);
1036                if (ret) {
1037                        kobject_put(&mem->dev.kobj);
1038                        return ret;
1039                }
1040        }
1041
1042        if (mem)
1043                kobject_put(&mem->dev.kobj);
1044
1045        return 0;
1046}
1047#else
1048int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1049{
1050        return -EINVAL;
1051}
1052int remove_memory(u64 start, u64 size)
1053{
1054        return -EINVAL;
1055}
1056#endif /* CONFIG_MEMORY_HOTREMOVE */
1057EXPORT_SYMBOL_GPL(remove_memory);
1058
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