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/module.h>
  15#include <linux/pagevec.h>
  16#include <linux/writeback.h>
  17#include <linux/slab.h>
  18#include <linux/sysctl.h>
  19#include <linux/cpu.h>
  20#include <linux/memory.h>
  21#include <linux/memory_hotplug.h>
  22#include <linux/highmem.h>
  23#include <linux/vmalloc.h>
  24#include <linux/ioport.h>
  25#include <linux/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 %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
  85static 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
  96static 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 */
 107void __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
 124static 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
 161void 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
 197static 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
 214static 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
 227static 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
 254static 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
 277static 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
 286static 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 */
 312int __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}
 337EXPORT_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 */
 350int __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}
 373EXPORT_SYMBOL_GPL(__remove_pages);
 374
 375int 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}
 390EXPORT_SYMBOL_GPL(set_online_page_callback);
 391
 392int 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}
 407EXPORT_SYMBOL_GPL(restore_online_page_callback);
 408
 409void __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}
 416EXPORT_SYMBOL_GPL(__online_page_set_limits);
 417
 418void __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}
 427EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 428
 429void __online_page_free(struct page *page)
 430{
 431        ClearPageReserved(page);
 432        init_page_count(page);
 433        __free_page(page);
 434}
 435EXPORT_SYMBOL_GPL(__online_page_free);
 436
 437static 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
 444static 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
 461int __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 */
 541static 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
 570static 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 */
 581int 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
 596out:
 597        unlock_memory_hotplug();
 598        return ret;
 599}
 600
 601/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 602int __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
 648error:
 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
 655out:
 656        unlock_memory_hotplug();
 657        return ret;
 658}
 659EXPORT_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 */
 669static 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 */
 675static 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. */
 693int 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 */
 712static 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 */
 739static 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
 753static struct page *
 754hotremove_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)
 761static int
 762do_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        }
 816out:
 817        return ret;
 818}
 819
 820/*
 821 * remove from free_area[] and mark all as Reserved.
 822 */
 823static int
 824offline_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
 831static void
 832offline_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 */
 841static int
 842check_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
 854static long
 855check_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
 867static 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;
 913repeat:
 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
 979failed_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
 986out:
 987        unlock_memory_hotplug();
 988        return ret;
 989}
 990
 991int 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
1000int remove_memory(u64 start, u64 size)
1001{
1002        return -EINVAL;
1003}
1004#endif /* CONFIG_MEMORY_HOTREMOVE */
1005EXPORT_SYMBOL_GPL(remove_memory);
1006
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