memory_hotplug.c revision 04753278769f3b6c3b79a080edb52f21d83bf6e2
1/* 2 * linux/mm/memory_hotplug.c 3 * 4 * Copyright (C) 5 */ 6 7#include <linux/stddef.h> 8#include <linux/mm.h> 9#include <linux/swap.h> 10#include <linux/interrupt.h> 11#include <linux/pagemap.h> 12#include <linux/bootmem.h> 13#include <linux/compiler.h> 14#include <linux/module.h> 15#include <linux/pagevec.h> 16#include <linux/writeback.h> 17#include <linux/slab.h> 18#include <linux/sysctl.h> 19#include <linux/cpu.h> 20#include <linux/memory.h> 21#include <linux/memory_hotplug.h> 22#include <linux/highmem.h> 23#include <linux/vmalloc.h> 24#include <linux/ioport.h> 25#include <linux/cpuset.h> 26#include <linux/delay.h> 27#include <linux/migrate.h> 28#include <linux/page-isolation.h> 29 30#include <asm/tlbflush.h> 31 32/* add this memory to iomem resource */ 33static struct resource *register_memory_resource(u64 start, u64 size) 34{ 35 struct resource *res; 36 res = kzalloc(sizeof(struct resource), GFP_KERNEL); 37 BUG_ON(!res); 38 39 res->name = "System RAM"; 40 res->start = start; 41 res->end = start + size - 1; 42 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY; 43 if (request_resource(&iomem_resource, res) < 0) { 44 printk("System RAM resource %llx - %llx cannot be added\n", 45 (unsigned long long)res->start, (unsigned long long)res->end); 46 kfree(res); 47 res = NULL; 48 } 49 return res; 50} 51 52static void release_memory_resource(struct resource *res) 53{ 54 if (!res) 55 return; 56 release_resource(res); 57 kfree(res); 58 return; 59} 60 61#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE 62#ifndef CONFIG_SPARSEMEM_VMEMMAP 63static void get_page_bootmem(unsigned long info, struct page *page, int magic) 64{ 65 atomic_set(&page->_mapcount, magic); 66 SetPagePrivate(page); 67 set_page_private(page, info); 68 atomic_inc(&page->_count); 69} 70 71void put_page_bootmem(struct page *page) 72{ 73 int magic; 74 75 magic = atomic_read(&page->_mapcount); 76 BUG_ON(magic >= -1); 77 78 if (atomic_dec_return(&page->_count) == 1) { 79 ClearPagePrivate(page); 80 set_page_private(page, 0); 81 reset_page_mapcount(page); 82 __free_pages_bootmem(page, 0); 83 } 84 85} 86 87void register_page_bootmem_info_section(unsigned long start_pfn) 88{ 89 unsigned long *usemap, mapsize, section_nr, i; 90 struct mem_section *ms; 91 struct page *page, *memmap; 92 93 if (!pfn_valid(start_pfn)) 94 return; 95 96 section_nr = pfn_to_section_nr(start_pfn); 97 ms = __nr_to_section(section_nr); 98 99 /* Get section's memmap address */ 100 memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); 101 102 /* 103 * Get page for the memmap's phys address 104 * XXX: need more consideration for sparse_vmemmap... 105 */ 106 page = virt_to_page(memmap); 107 mapsize = sizeof(struct page) * PAGES_PER_SECTION; 108 mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT; 109 110 /* remember memmap's page */ 111 for (i = 0; i < mapsize; i++, page++) 112 get_page_bootmem(section_nr, page, SECTION_INFO); 113 114 usemap = __nr_to_section(section_nr)->pageblock_flags; 115 page = virt_to_page(usemap); 116 117 mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT; 118 119 for (i = 0; i < mapsize; i++, page++) 120 get_page_bootmem(section_nr, page, MIX_INFO); 121 122} 123 124void register_page_bootmem_info_node(struct pglist_data *pgdat) 125{ 126 unsigned long i, pfn, end_pfn, nr_pages; 127 int node = pgdat->node_id; 128 struct page *page; 129 struct zone *zone; 130 131 nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT; 132 page = virt_to_page(pgdat); 133 134 for (i = 0; i < nr_pages; i++, page++) 135 get_page_bootmem(node, page, NODE_INFO); 136 137 zone = &pgdat->node_zones[0]; 138 for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) { 139 if (zone->wait_table) { 140 nr_pages = zone->wait_table_hash_nr_entries 141 * sizeof(wait_queue_head_t); 142 nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT; 143 page = virt_to_page(zone->wait_table); 144 145 for (i = 0; i < nr_pages; i++, page++) 146 get_page_bootmem(node, page, NODE_INFO); 147 } 148 } 149 150 pfn = pgdat->node_start_pfn; 151 end_pfn = pfn + pgdat->node_spanned_pages; 152 153 /* register_section info */ 154 for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) 155 register_page_bootmem_info_section(pfn); 156 157} 158#endif /* !CONFIG_SPARSEMEM_VMEMMAP */ 159 160static int __add_zone(struct zone *zone, unsigned long phys_start_pfn) 161{ 162 struct pglist_data *pgdat = zone->zone_pgdat; 163 int nr_pages = PAGES_PER_SECTION; 164 int nid = pgdat->node_id; 165 int zone_type; 166 167 zone_type = zone - pgdat->node_zones; 168 if (!zone->wait_table) { 169 int ret = 0; 170 ret = init_currently_empty_zone(zone, phys_start_pfn, 171 nr_pages, MEMMAP_HOTPLUG); 172 if (ret < 0) 173 return ret; 174 } 175 memmap_init_zone(nr_pages, nid, zone_type, 176 phys_start_pfn, MEMMAP_HOTPLUG); 177 return 0; 178} 179 180static int __add_section(struct zone *zone, unsigned long phys_start_pfn) 181{ 182 int nr_pages = PAGES_PER_SECTION; 183 int ret; 184 185 if (pfn_valid(phys_start_pfn)) 186 return -EEXIST; 187 188 ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages); 189 190 if (ret < 0) 191 return ret; 192 193 ret = __add_zone(zone, phys_start_pfn); 194 195 if (ret < 0) 196 return ret; 197 198 return register_new_memory(__pfn_to_section(phys_start_pfn)); 199} 200 201static int __remove_section(struct zone *zone, struct mem_section *ms) 202{ 203 unsigned long flags; 204 struct pglist_data *pgdat = zone->zone_pgdat; 205 int ret = -EINVAL; 206 207 if (!valid_section(ms)) 208 return ret; 209 210 ret = unregister_memory_section(ms); 211 if (ret) 212 return ret; 213 214 pgdat_resize_lock(pgdat, &flags); 215 sparse_remove_one_section(zone, ms); 216 pgdat_resize_unlock(pgdat, &flags); 217 return 0; 218} 219 220/* 221 * Reasonably generic function for adding memory. It is 222 * expected that archs that support memory hotplug will 223 * call this function after deciding the zone to which to 224 * add the new pages. 225 */ 226int __add_pages(struct zone *zone, unsigned long phys_start_pfn, 227 unsigned long nr_pages) 228{ 229 unsigned long i; 230 int err = 0; 231 int start_sec, end_sec; 232 /* during initialize mem_map, align hot-added range to section */ 233 start_sec = pfn_to_section_nr(phys_start_pfn); 234 end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1); 235 236 for (i = start_sec; i <= end_sec; i++) { 237 err = __add_section(zone, i << PFN_SECTION_SHIFT); 238 239 /* 240 * EEXIST is finally dealt with by ioresource collision 241 * check. see add_memory() => register_memory_resource() 242 * Warning will be printed if there is collision. 243 */ 244 if (err && (err != -EEXIST)) 245 break; 246 err = 0; 247 } 248 249 return err; 250} 251EXPORT_SYMBOL_GPL(__add_pages); 252 253/** 254 * __remove_pages() - remove sections of pages from a zone 255 * @zone: zone from which pages need to be removed 256 * @phys_start_pfn: starting pageframe (must be aligned to start of a section) 257 * @nr_pages: number of pages to remove (must be multiple of section size) 258 * 259 * Generic helper function to remove section mappings and sysfs entries 260 * for the section of the memory we are removing. Caller needs to make 261 * sure that pages are marked reserved and zones are adjust properly by 262 * calling offline_pages(). 263 */ 264int __remove_pages(struct zone *zone, unsigned long phys_start_pfn, 265 unsigned long nr_pages) 266{ 267 unsigned long i, ret = 0; 268 int sections_to_remove; 269 270 /* 271 * We can only remove entire sections 272 */ 273 BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK); 274 BUG_ON(nr_pages % PAGES_PER_SECTION); 275 276 release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE); 277 278 sections_to_remove = nr_pages / PAGES_PER_SECTION; 279 for (i = 0; i < sections_to_remove; i++) { 280 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION; 281 ret = __remove_section(zone, __pfn_to_section(pfn)); 282 if (ret) 283 break; 284 } 285 return ret; 286} 287EXPORT_SYMBOL_GPL(__remove_pages); 288 289static void grow_zone_span(struct zone *zone, 290 unsigned long start_pfn, unsigned long end_pfn) 291{ 292 unsigned long old_zone_end_pfn; 293 294 zone_span_writelock(zone); 295 296 old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; 297 if (start_pfn < zone->zone_start_pfn) 298 zone->zone_start_pfn = start_pfn; 299 300 zone->spanned_pages = max(old_zone_end_pfn, end_pfn) - 301 zone->zone_start_pfn; 302 303 zone_span_writeunlock(zone); 304} 305 306static void grow_pgdat_span(struct pglist_data *pgdat, 307 unsigned long start_pfn, unsigned long end_pfn) 308{ 309 unsigned long old_pgdat_end_pfn = 310 pgdat->node_start_pfn + pgdat->node_spanned_pages; 311 312 if (start_pfn < pgdat->node_start_pfn) 313 pgdat->node_start_pfn = start_pfn; 314 315 pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) - 316 pgdat->node_start_pfn; 317} 318 319void online_page(struct page *page) 320{ 321 totalram_pages++; 322 num_physpages++; 323 324#ifdef CONFIG_HIGHMEM 325 if (PageHighMem(page)) 326 totalhigh_pages++; 327#endif 328 329#ifdef CONFIG_FLATMEM 330 max_mapnr = max(page_to_pfn(page), max_mapnr); 331#endif 332 333 ClearPageReserved(page); 334 init_page_count(page); 335 __free_page(page); 336} 337 338static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, 339 void *arg) 340{ 341 unsigned long i; 342 unsigned long onlined_pages = *(unsigned long *)arg; 343 struct page *page; 344 if (PageReserved(pfn_to_page(start_pfn))) 345 for (i = 0; i < nr_pages; i++) { 346 page = pfn_to_page(start_pfn + i); 347 online_page(page); 348 onlined_pages++; 349 } 350 *(unsigned long *)arg = onlined_pages; 351 return 0; 352} 353 354 355int online_pages(unsigned long pfn, unsigned long nr_pages) 356{ 357 unsigned long flags; 358 unsigned long onlined_pages = 0; 359 struct zone *zone; 360 int need_zonelists_rebuild = 0; 361 int nid; 362 int ret; 363 struct memory_notify arg; 364 365 arg.start_pfn = pfn; 366 arg.nr_pages = nr_pages; 367 arg.status_change_nid = -1; 368 369 nid = page_to_nid(pfn_to_page(pfn)); 370 if (node_present_pages(nid) == 0) 371 arg.status_change_nid = nid; 372 373 ret = memory_notify(MEM_GOING_ONLINE, &arg); 374 ret = notifier_to_errno(ret); 375 if (ret) { 376 memory_notify(MEM_CANCEL_ONLINE, &arg); 377 return ret; 378 } 379 /* 380 * This doesn't need a lock to do pfn_to_page(). 381 * The section can't be removed here because of the 382 * memory_block->state_mutex. 383 */ 384 zone = page_zone(pfn_to_page(pfn)); 385 pgdat_resize_lock(zone->zone_pgdat, &flags); 386 grow_zone_span(zone, pfn, pfn + nr_pages); 387 grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages); 388 pgdat_resize_unlock(zone->zone_pgdat, &flags); 389 390 /* 391 * If this zone is not populated, then it is not in zonelist. 392 * This means the page allocator ignores this zone. 393 * So, zonelist must be updated after online. 394 */ 395 if (!populated_zone(zone)) 396 need_zonelists_rebuild = 1; 397 398 walk_memory_resource(pfn, nr_pages, &onlined_pages, 399 online_pages_range); 400 zone->present_pages += onlined_pages; 401 zone->zone_pgdat->node_present_pages += onlined_pages; 402 403 setup_per_zone_pages_min(); 404 if (onlined_pages) { 405 kswapd_run(zone_to_nid(zone)); 406 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); 407 } 408 409 if (need_zonelists_rebuild) 410 build_all_zonelists(); 411 vm_total_pages = nr_free_pagecache_pages(); 412 writeback_set_ratelimit(); 413 414 if (onlined_pages) 415 memory_notify(MEM_ONLINE, &arg); 416 417 return 0; 418} 419#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ 420 421static pg_data_t *hotadd_new_pgdat(int nid, u64 start) 422{ 423 struct pglist_data *pgdat; 424 unsigned long zones_size[MAX_NR_ZONES] = {0}; 425 unsigned long zholes_size[MAX_NR_ZONES] = {0}; 426 unsigned long start_pfn = start >> PAGE_SHIFT; 427 428 pgdat = arch_alloc_nodedata(nid); 429 if (!pgdat) 430 return NULL; 431 432 arch_refresh_nodedata(nid, pgdat); 433 434 /* we can use NODE_DATA(nid) from here */ 435 436 /* init node's zones as empty zones, we don't have any present pages.*/ 437 free_area_init_node(nid, pgdat, zones_size, start_pfn, zholes_size); 438 439 return pgdat; 440} 441 442static void rollback_node_hotadd(int nid, pg_data_t *pgdat) 443{ 444 arch_refresh_nodedata(nid, NULL); 445 arch_free_nodedata(pgdat); 446 return; 447} 448 449 450int add_memory(int nid, u64 start, u64 size) 451{ 452 pg_data_t *pgdat = NULL; 453 int new_pgdat = 0; 454 struct resource *res; 455 int ret; 456 457 res = register_memory_resource(start, size); 458 if (!res) 459 return -EEXIST; 460 461 if (!node_online(nid)) { 462 pgdat = hotadd_new_pgdat(nid, start); 463 if (!pgdat) 464 return -ENOMEM; 465 new_pgdat = 1; 466 } 467 468 /* call arch's memory hotadd */ 469 ret = arch_add_memory(nid, start, size); 470 471 if (ret < 0) 472 goto error; 473 474 /* we online node here. we can't roll back from here. */ 475 node_set_online(nid); 476 477 cpuset_track_online_nodes(); 478 479 if (new_pgdat) { 480 ret = register_one_node(nid); 481 /* 482 * If sysfs file of new node can't create, cpu on the node 483 * can't be hot-added. There is no rollback way now. 484 * So, check by BUG_ON() to catch it reluctantly.. 485 */ 486 BUG_ON(ret); 487 } 488 489 return ret; 490error: 491 /* rollback pgdat allocation and others */ 492 if (new_pgdat) 493 rollback_node_hotadd(nid, pgdat); 494 if (res) 495 release_memory_resource(res); 496 497 return ret; 498} 499EXPORT_SYMBOL_GPL(add_memory); 500 501#ifdef CONFIG_MEMORY_HOTREMOVE 502/* 503 * Confirm all pages in a range [start, end) is belongs to the same zone. 504 */ 505static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) 506{ 507 unsigned long pfn; 508 struct zone *zone = NULL; 509 struct page *page; 510 int i; 511 for (pfn = start_pfn; 512 pfn < end_pfn; 513 pfn += MAX_ORDER_NR_PAGES) { 514 i = 0; 515 /* This is just a CONFIG_HOLES_IN_ZONE check.*/ 516 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) 517 i++; 518 if (i == MAX_ORDER_NR_PAGES) 519 continue; 520 page = pfn_to_page(pfn + i); 521 if (zone && page_zone(page) != zone) 522 return 0; 523 zone = page_zone(page); 524 } 525 return 1; 526} 527 528/* 529 * Scanning pfn is much easier than scanning lru list. 530 * Scan pfn from start to end and Find LRU page. 531 */ 532int scan_lru_pages(unsigned long start, unsigned long end) 533{ 534 unsigned long pfn; 535 struct page *page; 536 for (pfn = start; pfn < end; pfn++) { 537 if (pfn_valid(pfn)) { 538 page = pfn_to_page(pfn); 539 if (PageLRU(page)) 540 return pfn; 541 } 542 } 543 return 0; 544} 545 546static struct page * 547hotremove_migrate_alloc(struct page *page, 548 unsigned long private, 549 int **x) 550{ 551 /* This should be improoooooved!! */ 552 return alloc_page(GFP_HIGHUSER_PAGECACHE); 553} 554 555 556#define NR_OFFLINE_AT_ONCE_PAGES (256) 557static int 558do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) 559{ 560 unsigned long pfn; 561 struct page *page; 562 int move_pages = NR_OFFLINE_AT_ONCE_PAGES; 563 int not_managed = 0; 564 int ret = 0; 565 LIST_HEAD(source); 566 567 for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) { 568 if (!pfn_valid(pfn)) 569 continue; 570 page = pfn_to_page(pfn); 571 if (!page_count(page)) 572 continue; 573 /* 574 * We can skip free pages. And we can only deal with pages on 575 * LRU. 576 */ 577 ret = isolate_lru_page(page, &source); 578 if (!ret) { /* Success */ 579 move_pages--; 580 } else { 581 /* Becasue we don't have big zone->lock. we should 582 check this again here. */ 583 if (page_count(page)) 584 not_managed++; 585#ifdef CONFIG_DEBUG_VM 586 printk(KERN_INFO "removing from LRU failed" 587 " %lx/%d/%lx\n", 588 pfn, page_count(page), page->flags); 589#endif 590 } 591 } 592 ret = -EBUSY; 593 if (not_managed) { 594 if (!list_empty(&source)) 595 putback_lru_pages(&source); 596 goto out; 597 } 598 ret = 0; 599 if (list_empty(&source)) 600 goto out; 601 /* this function returns # of failed pages */ 602 ret = migrate_pages(&source, hotremove_migrate_alloc, 0); 603 604out: 605 return ret; 606} 607 608/* 609 * remove from free_area[] and mark all as Reserved. 610 */ 611static int 612offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages, 613 void *data) 614{ 615 __offline_isolated_pages(start, start + nr_pages); 616 return 0; 617} 618 619static void 620offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) 621{ 622 walk_memory_resource(start_pfn, end_pfn - start_pfn, NULL, 623 offline_isolated_pages_cb); 624} 625 626/* 627 * Check all pages in range, recoreded as memory resource, are isolated. 628 */ 629static int 630check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages, 631 void *data) 632{ 633 int ret; 634 long offlined = *(long *)data; 635 ret = test_pages_isolated(start_pfn, start_pfn + nr_pages); 636 offlined = nr_pages; 637 if (!ret) 638 *(long *)data += offlined; 639 return ret; 640} 641 642static long 643check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) 644{ 645 long offlined = 0; 646 int ret; 647 648 ret = walk_memory_resource(start_pfn, end_pfn - start_pfn, &offlined, 649 check_pages_isolated_cb); 650 if (ret < 0) 651 offlined = (long)ret; 652 return offlined; 653} 654 655int offline_pages(unsigned long start_pfn, 656 unsigned long end_pfn, unsigned long timeout) 657{ 658 unsigned long pfn, nr_pages, expire; 659 long offlined_pages; 660 int ret, drain, retry_max, node; 661 struct zone *zone; 662 struct memory_notify arg; 663 664 BUG_ON(start_pfn >= end_pfn); 665 /* at least, alignment against pageblock is necessary */ 666 if (!IS_ALIGNED(start_pfn, pageblock_nr_pages)) 667 return -EINVAL; 668 if (!IS_ALIGNED(end_pfn, pageblock_nr_pages)) 669 return -EINVAL; 670 /* This makes hotplug much easier...and readable. 671 we assume this for now. .*/ 672 if (!test_pages_in_a_zone(start_pfn, end_pfn)) 673 return -EINVAL; 674 675 zone = page_zone(pfn_to_page(start_pfn)); 676 node = zone_to_nid(zone); 677 nr_pages = end_pfn - start_pfn; 678 679 /* set above range as isolated */ 680 ret = start_isolate_page_range(start_pfn, end_pfn); 681 if (ret) 682 return ret; 683 684 arg.start_pfn = start_pfn; 685 arg.nr_pages = nr_pages; 686 arg.status_change_nid = -1; 687 if (nr_pages >= node_present_pages(node)) 688 arg.status_change_nid = node; 689 690 ret = memory_notify(MEM_GOING_OFFLINE, &arg); 691 ret = notifier_to_errno(ret); 692 if (ret) 693 goto failed_removal; 694 695 pfn = start_pfn; 696 expire = jiffies + timeout; 697 drain = 0; 698 retry_max = 5; 699repeat: 700 /* start memory hot removal */ 701 ret = -EAGAIN; 702 if (time_after(jiffies, expire)) 703 goto failed_removal; 704 ret = -EINTR; 705 if (signal_pending(current)) 706 goto failed_removal; 707 ret = 0; 708 if (drain) { 709 lru_add_drain_all(); 710 flush_scheduled_work(); 711 cond_resched(); 712 drain_all_pages(); 713 } 714 715 pfn = scan_lru_pages(start_pfn, end_pfn); 716 if (pfn) { /* We have page on LRU */ 717 ret = do_migrate_range(pfn, end_pfn); 718 if (!ret) { 719 drain = 1; 720 goto repeat; 721 } else { 722 if (ret < 0) 723 if (--retry_max == 0) 724 goto failed_removal; 725 yield(); 726 drain = 1; 727 goto repeat; 728 } 729 } 730 /* drain all zone's lru pagevec, this is asyncronous... */ 731 lru_add_drain_all(); 732 flush_scheduled_work(); 733 yield(); 734 /* drain pcp pages , this is synchrouns. */ 735 drain_all_pages(); 736 /* check again */ 737 offlined_pages = check_pages_isolated(start_pfn, end_pfn); 738 if (offlined_pages < 0) { 739 ret = -EBUSY; 740 goto failed_removal; 741 } 742 printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages); 743 /* Ok, all of our target is islaoted. 744 We cannot do rollback at this point. */ 745 offline_isolated_pages(start_pfn, end_pfn); 746 /* reset pagetype flags and makes migrate type to be MOVABLE */ 747 undo_isolate_page_range(start_pfn, end_pfn); 748 /* removal success */ 749 zone->present_pages -= offlined_pages; 750 zone->zone_pgdat->node_present_pages -= offlined_pages; 751 totalram_pages -= offlined_pages; 752 num_physpages -= offlined_pages; 753 754 vm_total_pages = nr_free_pagecache_pages(); 755 writeback_set_ratelimit(); 756 757 memory_notify(MEM_OFFLINE, &arg); 758 return 0; 759 760failed_removal: 761 printk(KERN_INFO "memory offlining %lx to %lx failed\n", 762 start_pfn, end_pfn); 763 memory_notify(MEM_CANCEL_OFFLINE, &arg); 764 /* pushback to free area */ 765 undo_isolate_page_range(start_pfn, end_pfn); 766 767 return ret; 768} 769#else 770int remove_memory(u64 start, u64 size) 771{ 772 return -EINVAL; 773} 774EXPORT_SYMBOL_GPL(remove_memory); 775#endif /* CONFIG_MEMORY_HOTREMOVE */ 776