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        sections_to_remove = nr_pages / PAGES_PER_SECTION;
 366        for (i = 0; i < sections_to_remove; i++) {
 367                unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
 368                release_mem_region(pfn << PAGE_SHIFT,
 369                                   PAGES_PER_SECTION << PAGE_SHIFT);
 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 (need_zonelists_rebuild)
 520                build_all_zonelists(zone);
 521        else
 522                zone_pcp_update(zone);
 523
 524        mutex_unlock(&zonelists_mutex);
 525
 526        init_per_zone_wmark_min();
 527
 528        if (onlined_pages) {
 529                kswapd_run(zone_to_nid(zone));
 530                node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 531        }
 532
 533        vm_total_pages = nr_free_pagecache_pages();
 534
 535        writeback_set_ratelimit();
 536
 537        if (onlined_pages)
 538                memory_notify(MEM_ONLINE, &arg);
 539        unlock_memory_hotplug();
 540
 541        return 0;
 542}
 543#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 544
 545/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 546static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
 547{
 548        struct pglist_data *pgdat;
 549        unsigned long zones_size[MAX_NR_ZONES] = {0};
 550        unsigned long zholes_size[MAX_NR_ZONES] = {0};
 551        unsigned long start_pfn = start >> PAGE_SHIFT;
 552
 553        pgdat = arch_alloc_nodedata(nid);
 554        if (!pgdat)
 555                return NULL;
 556
 557        arch_refresh_nodedata(nid, pgdat);
 558
 559        /* we can use NODE_DATA(nid) from here */
 560
 561        /* init node's zones as empty zones, we don't have any present pages.*/
 562        free_area_init_node(nid, zones_size, start_pfn, zholes_size);
 563
 564        /*
 565         * The node we allocated has no zone fallback lists. For avoiding
 566         * to access not-initialized zonelist, build here.
 567         */
 568        mutex_lock(&zonelists_mutex);
 569        build_all_zonelists(NULL);
 570        mutex_unlock(&zonelists_mutex);
 571
 572        return pgdat;
 573}
 574
 575static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 576{
 577        arch_refresh_nodedata(nid, NULL);
 578        arch_free_nodedata(pgdat);
 579        return;
 580}
 581
 582
 583/*
 584 * called by cpu_up() to online a node without onlined memory.
 585 */
 586int mem_online_node(int nid)
 587{
 588        pg_data_t       *pgdat;
 589        int     ret;
 590
 591        lock_memory_hotplug();
 592        pgdat = hotadd_new_pgdat(nid, 0);
 593        if (!pgdat) {
 594                ret = -ENOMEM;
 595                goto out;
 596        }
 597        node_set_online(nid);
 598        ret = register_one_node(nid);
 599        BUG_ON(ret);
 600
 601out:
 602        unlock_memory_hotplug();
 603        return ret;
 604}
 605
 606/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 607int __ref add_memory(int nid, u64 start, u64 size)
 608{
 609        pg_data_t *pgdat = NULL;
 610        int new_pgdat = 0;
 611        struct resource *res;
 612        int ret;
 613
 614        lock_memory_hotplug();
 615
 616        res = register_memory_resource(start, size);
 617        ret = -EEXIST;
 618        if (!res)
 619                goto out;
 620
 621        if (!node_online(nid)) {
 622                pgdat = hotadd_new_pgdat(nid, start);
 623                ret = -ENOMEM;
 624                if (!pgdat)
 625                        goto error;
 626                new_pgdat = 1;
 627        }
 628
 629        /* call arch's memory hotadd */
 630        ret = arch_add_memory(nid, start, size);
 631
 632        if (ret < 0)
 633                goto error;
 634
 635        /* we online node here. we can't roll back from here. */
 636        node_set_online(nid);
 637
 638        if (new_pgdat) {
 639                ret = register_one_node(nid);
 640                /*
 641                 * If sysfs file of new node can't create, cpu on the node
 642                 * can't be hot-added. There is no rollback way now.
 643                 * So, check by BUG_ON() to catch it reluctantly..
 644                 */
 645                BUG_ON(ret);
 646        }
 647
 648        /* create new memmap entry */
 649        firmware_map_add_hotplug(start, start + size, "System RAM");
 650
 651        goto out;
 652
 653error:
 654        /* rollback pgdat allocation and others */
 655        if (new_pgdat)
 656                rollback_node_hotadd(nid, pgdat);
 657        if (res)
 658                release_memory_resource(res);
 659
 660out:
 661        unlock_memory_hotplug();
 662        return ret;
 663}
 664EXPORT_SYMBOL_GPL(add_memory);
 665
 666#ifdef CONFIG_MEMORY_HOTREMOVE
 667/*
 668 * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
 669 * set and the size of the free page is given by page_order(). Using this,
 670 * the function determines if the pageblock contains only free pages.
 671 * Due to buddy contraints, a free page at least the size of a pageblock will
 672 * be located at the start of the pageblock
 673 */
 674static inline int pageblock_free(struct page *page)
 675{
 676        return PageBuddy(page) && page_order(page) >= pageblock_order;
 677}
 678
 679/* Return the start of the next active pageblock after a given page */
 680static struct page *next_active_pageblock(struct page *page)
 681{
 682        /* Ensure the starting page is pageblock-aligned */
 683        BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
 684
 685        /* If the entire pageblock is free, move to the end of free page */
 686        if (pageblock_free(page)) {
 687                int order;
 688                /* be careful. we don't have locks, page_order can be changed.*/
 689                order = page_order(page);
 690                if ((order < MAX_ORDER) && (order >= pageblock_order))
 691                        return page + (1 << order);
 692        }
 693
 694        return page + pageblock_nr_pages;
 695}
 696
 697/* Checks if this range of memory is likely to be hot-removable. */
 698int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
 699{
 700        struct page *page = pfn_to_page(start_pfn);
 701        struct page *end_page = page + nr_pages;
 702
 703        /* Check the starting page of each pageblock within the range */
 704        for (; page < end_page; page = next_active_pageblock(page)) {
 705                if (!is_pageblock_removable_nolock(page))
 706                        return 0;
 707                cond_resched();
 708        }
 709
 710        /* All pageblocks in the memory block are likely to be hot-removable */
 711        return 1;
 712}
 713
 714/*
 715 * Confirm all pages in a range [start, end) is belongs to the same zone.
 716 */
 717static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 718{
 719        unsigned long pfn;
 720        struct zone *zone = NULL;
 721        struct page *page;
 722        int i;
 723        for (pfn = start_pfn;
 724             pfn < end_pfn;
 725             pfn += MAX_ORDER_NR_PAGES) {
 726                i = 0;
 727                /* This is just a CONFIG_HOLES_IN_ZONE check.*/
 728                while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
 729                        i++;
 730                if (i == MAX_ORDER_NR_PAGES)
 731                        continue;
 732                page = pfn_to_page(pfn + i);
 733                if (zone && page_zone(page) != zone)
 734                        return 0;
 735                zone = page_zone(page);
 736        }
 737        return 1;
 738}
 739
 740/*
 741 * Scanning pfn is much easier than scanning lru list.
 742 * Scan pfn from start to end and Find LRU page.
 743 */
 744static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
 745{
 746        unsigned long pfn;
 747        struct page *page;
 748        for (pfn = start; pfn < end; pfn++) {
 749                if (pfn_valid(pfn)) {
 750                        page = pfn_to_page(pfn);
 751                        if (PageLRU(page))
 752                                return pfn;
 753                }
 754        }
 755        return 0;
 756}
 757
 758static struct page *
 759hotremove_migrate_alloc(struct page *page, unsigned long private, int **x)
 760{
 761        /* This should be improooooved!! */
 762        return alloc_page(GFP_HIGHUSER_MOVABLE);
 763}
 764
 765#define NR_OFFLINE_AT_ONCE_PAGES        (256)
 766static int
 767do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 768{
 769        unsigned long pfn;
 770        struct page *page;
 771        int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
 772        int not_managed = 0;
 773        int ret = 0;
 774        LIST_HEAD(source);
 775
 776        for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
 777                if (!pfn_valid(pfn))
 778                        continue;
 779                page = pfn_to_page(pfn);
 780                if (!get_page_unless_zero(page))
 781                        continue;
 782                /*
 783                 * We can skip free pages. And we can only deal with pages on
 784                 * LRU.
 785                 */
 786                ret = isolate_lru_page(page);
 787                if (!ret) { /* Success */
 788                        put_page(page);
 789                        list_add_tail(&page->lru, &source);
 790                        move_pages--;
 791                        inc_zone_page_state(page, NR_ISOLATED_ANON +
 792                                            page_is_file_cache(page));
 793
 794                } else {
 795#ifdef CONFIG_DEBUG_VM
 796                        printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
 797                               pfn);
 798                        dump_page(page);
 799#endif
 800                        put_page(page);
 801                        /* Because we don't have big zone->lock. we should
 802                           check this again here. */
 803                        if (page_count(page)) {
 804                                not_managed++;
 805                                ret = -EBUSY;
 806                                break;
 807                        }
 808                }
 809        }
 810        if (!list_empty(&source)) {
 811                if (not_managed) {
 812                        putback_lru_pages(&source);
 813                        goto out;
 814                }
 815                /* this function returns # of failed pages */
 816                ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
 817                                                        true, MIGRATE_SYNC);
 818                if (ret)
 819                        putback_lru_pages(&source);
 820        }
 821out:
 822        return ret;
 823}
 824
 825/*
 826 * remove from free_area[] and mark all as Reserved.
 827 */
 828static int
 829offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 830                        void *data)
 831{
 832        __offline_isolated_pages(start, start + nr_pages);
 833        return 0;
 834}
 835
 836static void
 837offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 838{
 839        walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
 840                                offline_isolated_pages_cb);
 841}
 842
 843/*
 844 * Check all pages in range, recoreded as memory resource, are isolated.
 845 */
 846static int
 847check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 848                        void *data)
 849{
 850        int ret;
 851        long offlined = *(long *)data;
 852        ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
 853        offlined = nr_pages;
 854        if (!ret)
 855                *(long *)data += offlined;
 856        return ret;
 857}
 858
 859static long
 860check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 861{
 862        long offlined = 0;
 863        int ret;
 864
 865        ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
 866                        check_pages_isolated_cb);
 867        if (ret < 0)
 868                offlined = (long)ret;
 869        return offlined;
 870}
 871
 872static int __ref offline_pages(unsigned long start_pfn,
 873                  unsigned long end_pfn, unsigned long timeout)
 874{
 875        unsigned long pfn, nr_pages, expire;
 876        long offlined_pages;
 877        int ret, drain, retry_max, node;
 878        struct zone *zone;
 879        struct memory_notify arg;
 880
 881        BUG_ON(start_pfn >= end_pfn);
 882        /* at least, alignment against pageblock is necessary */
 883        if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
 884                return -EINVAL;
 885        if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
 886                return -EINVAL;
 887        /* This makes hotplug much easier...and readable.
 888           we assume this for now. .*/
 889        if (!test_pages_in_a_zone(start_pfn, end_pfn))
 890                return -EINVAL;
 891
 892        lock_memory_hotplug();
 893
 894        zone = page_zone(pfn_to_page(start_pfn));
 895        node = zone_to_nid(zone);
 896        nr_pages = end_pfn - start_pfn;
 897
 898        /* set above range as isolated */
 899        ret = start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 900        if (ret)
 901                goto out;
 902
 903        arg.start_pfn = start_pfn;
 904        arg.nr_pages = nr_pages;
 905        arg.status_change_nid = -1;
 906        if (nr_pages >= node_present_pages(node))
 907                arg.status_change_nid = node;
 908
 909        ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 910        ret = notifier_to_errno(ret);
 911        if (ret)
 912                goto failed_removal;
 913
 914        pfn = start_pfn;
 915        expire = jiffies + timeout;
 916        drain = 0;
 917        retry_max = 5;
 918repeat:
 919        /* start memory hot removal */
 920        ret = -EAGAIN;
 921        if (time_after(jiffies, expire))
 922                goto failed_removal;
 923        ret = -EINTR;
 924        if (signal_pending(current))
 925                goto failed_removal;
 926        ret = 0;
 927        if (drain) {
 928                lru_add_drain_all();
 929                cond_resched();
 930                drain_all_pages();
 931        }
 932
 933        pfn = scan_lru_pages(start_pfn, end_pfn);
 934        if (pfn) { /* We have page on LRU */
 935                ret = do_migrate_range(pfn, end_pfn);
 936                if (!ret) {
 937                        drain = 1;
 938                        goto repeat;
 939                } else {
 940                        if (ret < 0)
 941                                if (--retry_max == 0)
 942                                        goto failed_removal;
 943                        yield();
 944                        drain = 1;
 945                        goto repeat;
 946                }
 947        }
 948        /* drain all zone's lru pagevec, this is asyncronous... */
 949        lru_add_drain_all();
 950        yield();
 951        /* drain pcp pages , this is synchrouns. */
 952        drain_all_pages();
 953        /* check again */
 954        offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 955        if (offlined_pages < 0) {
 956                ret = -EBUSY;
 957                goto failed_removal;
 958        }
 959        printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
 960        /* Ok, all of our target is islaoted.
 961           We cannot do rollback at this point. */
 962        offline_isolated_pages(start_pfn, end_pfn);
 963        /* reset pagetype flags and makes migrate type to be MOVABLE */
 964        undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 965        /* removal success */
 966        zone->present_pages -= offlined_pages;
 967        zone->zone_pgdat->node_present_pages -= offlined_pages;
 968        totalram_pages -= offlined_pages;
 969
 970        init_per_zone_wmark_min();
 971
 972        if (!node_present_pages(node)) {
 973                node_clear_state(node, N_HIGH_MEMORY);
 974                kswapd_stop(node);
 975        }
 976
 977        vm_total_pages = nr_free_pagecache_pages();
 978        writeback_set_ratelimit();
 979
 980        memory_notify(MEM_OFFLINE, &arg);
 981        unlock_memory_hotplug();
 982        return 0;
 983
 984failed_removal:
 985        printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
 986               (unsigned long long) start_pfn << PAGE_SHIFT,
 987               ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
 988        memory_notify(MEM_CANCEL_OFFLINE, &arg);
 989        /* pushback to free area */
 990        undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 991
 992out:
 993        unlock_memory_hotplug();
 994        return ret;
 995}
 996
 997int remove_memory(u64 start, u64 size)
 998{
 999        unsigned long start_pfn, end_pfn;
1000
1001        start_pfn = PFN_DOWN(start);
1002        end_pfn = start_pfn + PFN_DOWN(size);
1003        return offline_pages(start_pfn, end_pfn, 120 * HZ);
1004}
1005#else
1006int remove_memory(u64 start, u64 size)
1007{
1008        return -EINVAL;
1009}
1010#endif /* CONFIG_MEMORY_HOTREMOVE */
1011EXPORT_SYMBOL_GPL(remove_memory);
1012
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