1 /* 2 * linux/mm/memory_hotplug.c 3 * 4 * Copyright (C) 5 */ 6 7 #include <linux/stddef.h> 8 #include <linux/mm.h> 9 #include <linux/swap.h> 10 #include <linux/interrupt.h> 11 #include <linux/pagemap.h> 12 #include <linux/bootmem.h> 13 #include <linux/compiler.h> 14 #include <linux/export.h> 15 #include <linux/pagevec.h> 16 #include <linux/writeback.h> 17 #include <linux/slab.h> 18 #include <linux/sysctl.h> 19 #include <linux/cpu.h> 20 #include <linux/memory.h> 21 #include <linux/memory_hotplug.h> 22 #include <linux/highmem.h> 23 #include <linux/vmalloc.h> 24 #include <linux/ioport.h> 25 #include <linux/delay.h> 26 #include <linux/migrate.h> 27 #include <linux/page-isolation.h> 28 #include <linux/pfn.h> 29 #include <linux/suspend.h> 30 #include <linux/mm_inline.h> 31 #include <linux/firmware-map.h> 32 33 #include <asm/tlbflush.h> 34 35 #include "internal.h" 36 37 /* 38 * online_page_callback contains pointer to current page onlining function. 39 * Initially it is generic_online_page(). If it is required it could be 40 * changed by calling set_online_page_callback() for callback registration 41 * and restore_online_page_callback() for generic callback restore. 42 */ 43 44 static void generic_online_page(struct page *page); 45 46 static online_page_callback_t online_page_callback = generic_online_page; 47 48 DEFINE_MUTEX(mem_hotplug_mutex); 49 50 void lock_memory_hotplug(void) 51 { 52 mutex_lock(&mem_hotplug_mutex); 53 54 /* for exclusive hibernation if CONFIG_HIBERNATION=y */ 55 lock_system_sleep(); 56 } 57 58 void unlock_memory_hotplug(void) 59 { 60 unlock_system_sleep(); 61 mutex_unlock(&mem_hotplug_mutex); 62 } 63 64 65 /* add this memory to iomem resource */ 66 static struct resource *register_memory_resource(u64 start, u64 size) 67 { 68 struct resource *res; 69 res = kzalloc(sizeof(struct resource), GFP_KERNEL); 70 BUG_ON(!res); 71 72 res->name = "System RAM"; 73 res->start = start; 74 res->end = start + size - 1; 75 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY; 76 if (request_resource(&iomem_resource, res) < 0) { 77 printk("System RAM resource %llx - %llx cannot be added\n", 78 (unsigned long long)res->start, (unsigned long long)res->end); 79 kfree(res); 80 res = NULL; 81 } 82 return res; 83 } 84 85 static void release_memory_resource(struct resource *res) 86 { 87 if (!res) 88 return; 89 release_resource(res); 90 kfree(res); 91 return; 92 } 93 94 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE 95 #ifndef CONFIG_SPARSEMEM_VMEMMAP 96 static void get_page_bootmem(unsigned long info, struct page *page, 97 unsigned long type) 98 { 99 page->lru.next = (struct list_head *) type; 100 SetPagePrivate(page); 101 set_page_private(page, info); 102 atomic_inc(&page->_count); 103 } 104 105 /* reference to __meminit __free_pages_bootmem is valid 106 * so use __ref to tell modpost not to generate a warning */ 107 void __ref put_page_bootmem(struct page *page) 108 { 109 unsigned long type; 110 111 type = (unsigned long) page->lru.next; 112 BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE || 113 type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE); 114 115 if (atomic_dec_return(&page->_count) == 1) { 116 ClearPagePrivate(page); 117 set_page_private(page, 0); 118 INIT_LIST_HEAD(&page->lru); 119 __free_pages_bootmem(page, 0); 120 } 121 122 } 123 124 static void register_page_bootmem_info_section(unsigned long start_pfn) 125 { 126 unsigned long *usemap, mapsize, section_nr, i; 127 struct mem_section *ms; 128 struct page *page, *memmap; 129 130 if (!pfn_valid(start_pfn)) 131 return; 132 133 section_nr = pfn_to_section_nr(start_pfn); 134 ms = __nr_to_section(section_nr); 135 136 /* Get section's memmap address */ 137 memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); 138 139 /* 140 * Get page for the memmap's phys address 141 * XXX: need more consideration for sparse_vmemmap... 142 */ 143 page = virt_to_page(memmap); 144 mapsize = sizeof(struct page) * PAGES_PER_SECTION; 145 mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT; 146 147 /* remember memmap's page */ 148 for (i = 0; i < mapsize; i++, page++) 149 get_page_bootmem(section_nr, page, SECTION_INFO); 150 151 usemap = __nr_to_section(section_nr)->pageblock_flags; 152 page = virt_to_page(usemap); 153 154 mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT; 155 156 for (i = 0; i < mapsize; i++, page++) 157 get_page_bootmem(section_nr, page, MIX_SECTION_INFO); 158 159 } 160 161 void register_page_bootmem_info_node(struct pglist_data *pgdat) 162 { 163 unsigned long i, pfn, end_pfn, nr_pages; 164 int node = pgdat->node_id; 165 struct page *page; 166 struct zone *zone; 167 168 nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT; 169 page = virt_to_page(pgdat); 170 171 for (i = 0; i < nr_pages; i++, page++) 172 get_page_bootmem(node, page, NODE_INFO); 173 174 zone = &pgdat->node_zones[0]; 175 for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) { 176 if (zone->wait_table) { 177 nr_pages = zone->wait_table_hash_nr_entries 178 * sizeof(wait_queue_head_t); 179 nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT; 180 page = virt_to_page(zone->wait_table); 181 182 for (i = 0; i < nr_pages; i++, page++) 183 get_page_bootmem(node, page, NODE_INFO); 184 } 185 } 186 187 pfn = pgdat->node_start_pfn; 188 end_pfn = pfn + pgdat->node_spanned_pages; 189 190 /* register_section info */ 191 for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) 192 register_page_bootmem_info_section(pfn); 193 194 } 195 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */ 196 197 static void grow_zone_span(struct zone *zone, unsigned long start_pfn, 198 unsigned long end_pfn) 199 { 200 unsigned long old_zone_end_pfn; 201 202 zone_span_writelock(zone); 203 204 old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; 205 if (start_pfn < zone->zone_start_pfn) 206 zone->zone_start_pfn = start_pfn; 207 208 zone->spanned_pages = max(old_zone_end_pfn, end_pfn) - 209 zone->zone_start_pfn; 210 211 zone_span_writeunlock(zone); 212 } 213 214 static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn, 215 unsigned long end_pfn) 216 { 217 unsigned long old_pgdat_end_pfn = 218 pgdat->node_start_pfn + pgdat->node_spanned_pages; 219 220 if (start_pfn < pgdat->node_start_pfn) 221 pgdat->node_start_pfn = start_pfn; 222 223 pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) - 224 pgdat->node_start_pfn; 225 } 226 227 static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn) 228 { 229 struct pglist_data *pgdat = zone->zone_pgdat; 230 int nr_pages = PAGES_PER_SECTION; 231 int nid = pgdat->node_id; 232 int zone_type; 233 unsigned long flags; 234 235 zone_type = zone - pgdat->node_zones; 236 if (!zone->wait_table) { 237 int ret; 238 239 ret = init_currently_empty_zone(zone, phys_start_pfn, 240 nr_pages, MEMMAP_HOTPLUG); 241 if (ret) 242 return ret; 243 } 244 pgdat_resize_lock(zone->zone_pgdat, &flags); 245 grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages); 246 grow_pgdat_span(zone->zone_pgdat, phys_start_pfn, 247 phys_start_pfn + nr_pages); 248 pgdat_resize_unlock(zone->zone_pgdat, &flags); 249 memmap_init_zone(nr_pages, nid, zone_type, 250 phys_start_pfn, MEMMAP_HOTPLUG); 251 return 0; 252 } 253 254 static int __meminit __add_section(int nid, struct zone *zone, 255 unsigned long phys_start_pfn) 256 { 257 int nr_pages = PAGES_PER_SECTION; 258 int ret; 259 260 if (pfn_valid(phys_start_pfn)) 261 return -EEXIST; 262 263 ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages); 264 265 if (ret < 0) 266 return ret; 267 268 ret = __add_zone(zone, phys_start_pfn); 269 270 if (ret < 0) 271 return ret; 272 273 return register_new_memory(nid, __pfn_to_section(phys_start_pfn)); 274 } 275 276 #ifdef CONFIG_SPARSEMEM_VMEMMAP 277 static int __remove_section(struct zone *zone, struct mem_section *ms) 278 { 279 /* 280 * XXX: Freeing memmap with vmemmap is not implement yet. 281 * This should be removed later. 282 */ 283 return -EBUSY; 284 } 285 #else 286 static int __remove_section(struct zone *zone, struct mem_section *ms) 287 { 288 unsigned long flags; 289 struct pglist_data *pgdat = zone->zone_pgdat; 290 int ret = -EINVAL; 291 292 if (!valid_section(ms)) 293 return ret; 294 295 ret = unregister_memory_section(ms); 296 if (ret) 297 return ret; 298 299 pgdat_resize_lock(pgdat, &flags); 300 sparse_remove_one_section(zone, ms); 301 pgdat_resize_unlock(pgdat, &flags); 302 return 0; 303 } 304 #endif 305 306 /* 307 * Reasonably generic function for adding memory. It is 308 * expected that archs that support memory hotplug will 309 * call this function after deciding the zone to which to 310 * add the new pages. 311 */ 312 int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn, 313 unsigned long nr_pages) 314 { 315 unsigned long i; 316 int err = 0; 317 int start_sec, end_sec; 318 /* during initialize mem_map, align hot-added range to section */ 319 start_sec = pfn_to_section_nr(phys_start_pfn); 320 end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1); 321 322 for (i = start_sec; i <= end_sec; i++) { 323 err = __add_section(nid, zone, i << PFN_SECTION_SHIFT); 324 325 /* 326 * EEXIST is finally dealt with by ioresource collision 327 * check. see add_memory() => register_memory_resource() 328 * Warning will be printed if there is collision. 329 */ 330 if (err && (err != -EEXIST)) 331 break; 332 err = 0; 333 } 334 335 return err; 336 } 337 EXPORT_SYMBOL_GPL(__add_pages); 338 339 /** 340 * __remove_pages() - remove sections of pages from a zone 341 * @zone: zone from which pages need to be removed 342 * @phys_start_pfn: starting pageframe (must be aligned to start of a section) 343 * @nr_pages: number of pages to remove (must be multiple of section size) 344 * 345 * Generic helper function to remove section mappings and sysfs entries 346 * for the section of the memory we are removing. Caller needs to make 347 * sure that pages are marked reserved and zones are adjust properly by 348 * calling offline_pages(). 349 */ 350 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn, 351 unsigned long nr_pages) 352 { 353 unsigned long i, ret = 0; 354 int sections_to_remove; 355 356 /* 357 * We can only remove entire sections 358 */ 359 BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK); 360 BUG_ON(nr_pages % PAGES_PER_SECTION); 361 362 sections_to_remove = nr_pages / PAGES_PER_SECTION; 363 for (i = 0; i < sections_to_remove; i++) { 364 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION; 365 release_mem_region(pfn << PAGE_SHIFT, 366 PAGES_PER_SECTION << PAGE_SHIFT); 367 ret = __remove_section(zone, __pfn_to_section(pfn)); 368 if (ret) 369 break; 370 } 371 return ret; 372 } 373 EXPORT_SYMBOL_GPL(__remove_pages); 374 375 int set_online_page_callback(online_page_callback_t callback) 376 { 377 int rc = -EINVAL; 378 379 lock_memory_hotplug(); 380 381 if (online_page_callback == generic_online_page) { 382 online_page_callback = callback; 383 rc = 0; 384 } 385 386 unlock_memory_hotplug(); 387 388 return rc; 389 } 390 EXPORT_SYMBOL_GPL(set_online_page_callback); 391 392 int restore_online_page_callback(online_page_callback_t callback) 393 { 394 int rc = -EINVAL; 395 396 lock_memory_hotplug(); 397 398 if (online_page_callback == callback) { 399 online_page_callback = generic_online_page; 400 rc = 0; 401 } 402 403 unlock_memory_hotplug(); 404 405 return rc; 406 } 407 EXPORT_SYMBOL_GPL(restore_online_page_callback); 408 409 void __online_page_set_limits(struct page *page) 410 { 411 unsigned long pfn = page_to_pfn(page); 412 413 if (pfn >= num_physpages) 414 num_physpages = pfn + 1; 415 } 416 EXPORT_SYMBOL_GPL(__online_page_set_limits); 417 418 void __online_page_increment_counters(struct page *page) 419 { 420 totalram_pages++; 421 422 #ifdef CONFIG_HIGHMEM 423 if (PageHighMem(page)) 424 totalhigh_pages++; 425 #endif 426 } 427 EXPORT_SYMBOL_GPL(__online_page_increment_counters); 428 429 void __online_page_free(struct page *page) 430 { 431 ClearPageReserved(page); 432 init_page_count(page); 433 __free_page(page); 434 } 435 EXPORT_SYMBOL_GPL(__online_page_free); 436 437 static void generic_online_page(struct page *page) 438 { 439 __online_page_set_limits(page); 440 __online_page_increment_counters(page); 441 __online_page_free(page); 442 } 443 444 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, 445 void *arg) 446 { 447 unsigned long i; 448 unsigned long onlined_pages = *(unsigned long *)arg; 449 struct page *page; 450 if (PageReserved(pfn_to_page(start_pfn))) 451 for (i = 0; i < nr_pages; i++) { 452 page = pfn_to_page(start_pfn + i); 453 (*online_page_callback)(page); 454 onlined_pages++; 455 } 456 *(unsigned long *)arg = onlined_pages; 457 return 0; 458 } 459 460 461 int __ref online_pages(unsigned long pfn, unsigned long nr_pages) 462 { 463 unsigned long onlined_pages = 0; 464 struct zone *zone; 465 int need_zonelists_rebuild = 0; 466 int nid; 467 int ret; 468 struct memory_notify arg; 469 470 lock_memory_hotplug(); 471 arg.start_pfn = pfn; 472 arg.nr_pages = nr_pages; 473 arg.status_change_nid = -1; 474 475 nid = page_to_nid(pfn_to_page(pfn)); 476 if (node_present_pages(nid) == 0) 477 arg.status_change_nid = nid; 478 479 ret = memory_notify(MEM_GOING_ONLINE, &arg); 480 ret = notifier_to_errno(ret); 481 if (ret) { 482 memory_notify(MEM_CANCEL_ONLINE, &arg); 483 unlock_memory_hotplug(); 484 return ret; 485 } 486 /* 487 * This doesn't need a lock to do pfn_to_page(). 488 * The section can't be removed here because of the 489 * memory_block->state_mutex. 490 */ 491 zone = page_zone(pfn_to_page(pfn)); 492 /* 493 * If this zone is not populated, then it is not in zonelist. 494 * This means the page allocator ignores this zone. 495 * So, zonelist must be updated after online. 496 */ 497 mutex_lock(&zonelists_mutex); 498 if (!populated_zone(zone)) 499 need_zonelists_rebuild = 1; 500 501 ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages, 502 online_pages_range); 503 if (ret) { 504 mutex_unlock(&zonelists_mutex); 505 printk(KERN_DEBUG "online_pages %lx at %lx failed\n", 506 nr_pages, pfn); 507 memory_notify(MEM_CANCEL_ONLINE, &arg); 508 unlock_memory_hotplug(); 509 return ret; 510 } 511 512 zone->present_pages += onlined_pages; 513 zone->zone_pgdat->node_present_pages += onlined_pages; 514 if (need_zonelists_rebuild) 515 build_all_zonelists(zone); 516 else 517 zone_pcp_update(zone); 518 519 mutex_unlock(&zonelists_mutex); 520 521 init_per_zone_wmark_min(); 522 523 if (onlined_pages) { 524 kswapd_run(zone_to_nid(zone)); 525 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); 526 } 527 528 vm_total_pages = nr_free_pagecache_pages(); 529 530 writeback_set_ratelimit(); 531 532 if (onlined_pages) 533 memory_notify(MEM_ONLINE, &arg); 534 unlock_memory_hotplug(); 535 536 return 0; 537 } 538 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ 539 540 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ 541 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) 542 { 543 struct pglist_data *pgdat; 544 unsigned long zones_size[MAX_NR_ZONES] = {0}; 545 unsigned long zholes_size[MAX_NR_ZONES] = {0}; 546 unsigned long start_pfn = start >> PAGE_SHIFT; 547 548 pgdat = arch_alloc_nodedata(nid); 549 if (!pgdat) 550 return NULL; 551 552 arch_refresh_nodedata(nid, pgdat); 553 554 /* we can use NODE_DATA(nid) from here */ 555 556 /* init node's zones as empty zones, we don't have any present pages.*/ 557 free_area_init_node(nid, zones_size, start_pfn, zholes_size); 558 559 /* 560 * The node we allocated has no zone fallback lists. For avoiding 561 * to access not-initialized zonelist, build here. 562 */ 563 mutex_lock(&zonelists_mutex); 564 build_all_zonelists(NULL); 565 mutex_unlock(&zonelists_mutex); 566 567 return pgdat; 568 } 569 570 static void rollback_node_hotadd(int nid, pg_data_t *pgdat) 571 { 572 arch_refresh_nodedata(nid, NULL); 573 arch_free_nodedata(pgdat); 574 return; 575 } 576 577 578 /* 579 * called by cpu_up() to online a node without onlined memory. 580 */ 581 int mem_online_node(int nid) 582 { 583 pg_data_t *pgdat; 584 int ret; 585 586 lock_memory_hotplug(); 587 pgdat = hotadd_new_pgdat(nid, 0); 588 if (!pgdat) { 589 ret = -ENOMEM; 590 goto out; 591 } 592 node_set_online(nid); 593 ret = register_one_node(nid); 594 BUG_ON(ret); 595 596 out: 597 unlock_memory_hotplug(); 598 return ret; 599 } 600 601 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ 602 int __ref add_memory(int nid, u64 start, u64 size) 603 { 604 pg_data_t *pgdat = NULL; 605 int new_pgdat = 0; 606 struct resource *res; 607 int ret; 608 609 lock_memory_hotplug(); 610 611 res = register_memory_resource(start, size); 612 ret = -EEXIST; 613 if (!res) 614 goto out; 615 616 if (!node_online(nid)) { 617 pgdat = hotadd_new_pgdat(nid, start); 618 ret = -ENOMEM; 619 if (!pgdat) 620 goto out; 621 new_pgdat = 1; 622 } 623 624 /* call arch's memory hotadd */ 625 ret = arch_add_memory(nid, start, size); 626 627 if (ret < 0) 628 goto error; 629 630 /* we online node here. we can't roll back from here. */ 631 node_set_online(nid); 632 633 if (new_pgdat) { 634 ret = register_one_node(nid); 635 /* 636 * If sysfs file of new node can't create, cpu on the node 637 * can't be hot-added. There is no rollback way now. 638 * So, check by BUG_ON() to catch it reluctantly.. 639 */ 640 BUG_ON(ret); 641 } 642 643 /* create new memmap entry */ 644 firmware_map_add_hotplug(start, start + size, "System RAM"); 645 646 goto out; 647 648 error: 649 /* rollback pgdat allocation and others */ 650 if (new_pgdat) 651 rollback_node_hotadd(nid, pgdat); 652 if (res) 653 release_memory_resource(res); 654 655 out: 656 unlock_memory_hotplug(); 657 return ret; 658 } 659 EXPORT_SYMBOL_GPL(add_memory); 660 661 #ifdef CONFIG_MEMORY_HOTREMOVE 662 /* 663 * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy 664 * set and the size of the free page is given by page_order(). Using this, 665 * the function determines if the pageblock contains only free pages. 666 * Due to buddy contraints, a free page at least the size of a pageblock will 667 * be located at the start of the pageblock 668 */ 669 static inline int pageblock_free(struct page *page) 670 { 671 return PageBuddy(page) && page_order(page) >= pageblock_order; 672 } 673 674 /* Return the start of the next active pageblock after a given page */ 675 static struct page *next_active_pageblock(struct page *page) 676 { 677 /* Ensure the starting page is pageblock-aligned */ 678 BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1)); 679 680 /* If the entire pageblock is free, move to the end of free page */ 681 if (pageblock_free(page)) { 682 int order; 683 /* be careful. we don't have locks, page_order can be changed.*/ 684 order = page_order(page); 685 if ((order < MAX_ORDER) && (order >= pageblock_order)) 686 return page + (1 << order); 687 } 688 689 return page + pageblock_nr_pages; 690 } 691 692 /* Checks if this range of memory is likely to be hot-removable. */ 693 int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) 694 { 695 struct page *page = pfn_to_page(start_pfn); 696 struct page *end_page = page + nr_pages; 697 698 /* Check the starting page of each pageblock within the range */ 699 for (; page < end_page; page = next_active_pageblock(page)) { 700 if (!is_pageblock_removable_nolock(page)) 701 return 0; 702 cond_resched(); 703 } 704 705 /* All pageblocks in the memory block are likely to be hot-removable */ 706 return 1; 707 } 708 709 /* 710 * Confirm all pages in a range [start, end) is belongs to the same zone. 711 */ 712 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) 713 { 714 unsigned long pfn; 715 struct zone *zone = NULL; 716 struct page *page; 717 int i; 718 for (pfn = start_pfn; 719 pfn < end_pfn; 720 pfn += MAX_ORDER_NR_PAGES) { 721 i = 0; 722 /* This is just a CONFIG_HOLES_IN_ZONE check.*/ 723 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) 724 i++; 725 if (i == MAX_ORDER_NR_PAGES) 726 continue; 727 page = pfn_to_page(pfn + i); 728 if (zone && page_zone(page) != zone) 729 return 0; 730 zone = page_zone(page); 731 } 732 return 1; 733 } 734 735 /* 736 * Scanning pfn is much easier than scanning lru list. 737 * Scan pfn from start to end and Find LRU page. 738 */ 739 static unsigned long scan_lru_pages(unsigned long start, unsigned long end) 740 { 741 unsigned long pfn; 742 struct page *page; 743 for (pfn = start; pfn < end; pfn++) { 744 if (pfn_valid(pfn)) { 745 page = pfn_to_page(pfn); 746 if (PageLRU(page)) 747 return pfn; 748 } 749 } 750 return 0; 751 } 752 753 static struct page * 754 hotremove_migrate_alloc(struct page *page, unsigned long private, int **x) 755 { 756 /* This should be improooooved!! */ 757 return alloc_page(GFP_HIGHUSER_MOVABLE); 758 } 759 760 #define NR_OFFLINE_AT_ONCE_PAGES (256) 761 static int 762 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) 763 { 764 unsigned long pfn; 765 struct page *page; 766 int move_pages = NR_OFFLINE_AT_ONCE_PAGES; 767 int not_managed = 0; 768 int ret = 0; 769 LIST_HEAD(source); 770 771 for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) { 772 if (!pfn_valid(pfn)) 773 continue; 774 page = pfn_to_page(pfn); 775 if (!get_page_unless_zero(page)) 776 continue; 777 /* 778 * We can skip free pages. And we can only deal with pages on 779 * LRU. 780 */ 781 ret = isolate_lru_page(page); 782 if (!ret) { /* Success */ 783 put_page(page); 784 list_add_tail(&page->lru, &source); 785 move_pages--; 786 inc_zone_page_state(page, NR_ISOLATED_ANON + 787 page_is_file_cache(page)); 788 789 } else { 790 #ifdef CONFIG_DEBUG_VM 791 printk(KERN_ALERT "removing pfn %lx from LRU failed\n", 792 pfn); 793 dump_page(page); 794 #endif 795 put_page(page); 796 /* Because we don't have big zone->lock. we should 797 check this again here. */ 798 if (page_count(page)) { 799 not_managed++; 800 ret = -EBUSY; 801 break; 802 } 803 } 804 } 805 if (!list_empty(&source)) { 806 if (not_managed) { 807 putback_lru_pages(&source); 808 goto out; 809 } 810 /* this function returns # of failed pages */ 811 ret = migrate_pages(&source, hotremove_migrate_alloc, 0, 812 true, MIGRATE_SYNC); 813 if (ret) 814 putback_lru_pages(&source); 815 } 816 out: 817 return ret; 818 } 819 820 /* 821 * remove from free_area[] and mark all as Reserved. 822 */ 823 static int 824 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages, 825 void *data) 826 { 827 __offline_isolated_pages(start, start + nr_pages); 828 return 0; 829 } 830 831 static void 832 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) 833 { 834 walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL, 835 offline_isolated_pages_cb); 836 } 837 838 /* 839 * Check all pages in range, recoreded as memory resource, are isolated. 840 */ 841 static int 842 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages, 843 void *data) 844 { 845 int ret; 846 long offlined = *(long *)data; 847 ret = test_pages_isolated(start_pfn, start_pfn + nr_pages); 848 offlined = nr_pages; 849 if (!ret) 850 *(long *)data += offlined; 851 return ret; 852 } 853 854 static long 855 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) 856 { 857 long offlined = 0; 858 int ret; 859 860 ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined, 861 check_pages_isolated_cb); 862 if (ret < 0) 863 offlined = (long)ret; 864 return offlined; 865 } 866 867 static int __ref offline_pages(unsigned long start_pfn, 868 unsigned long end_pfn, unsigned long timeout) 869 { 870 unsigned long pfn, nr_pages, expire; 871 long offlined_pages; 872 int ret, drain, retry_max, node; 873 struct zone *zone; 874 struct memory_notify arg; 875 876 BUG_ON(start_pfn >= end_pfn); 877 /* at least, alignment against pageblock is necessary */ 878 if (!IS_ALIGNED(start_pfn, pageblock_nr_pages)) 879 return -EINVAL; 880 if (!IS_ALIGNED(end_pfn, pageblock_nr_pages)) 881 return -EINVAL; 882 /* This makes hotplug much easier...and readable. 883 we assume this for now. .*/ 884 if (!test_pages_in_a_zone(start_pfn, end_pfn)) 885 return -EINVAL; 886 887 lock_memory_hotplug(); 888 889 zone = page_zone(pfn_to_page(start_pfn)); 890 node = zone_to_nid(zone); 891 nr_pages = end_pfn - start_pfn; 892 893 /* set above range as isolated */ 894 ret = start_isolate_page_range(start_pfn, end_pfn); 895 if (ret) 896 goto out; 897 898 arg.start_pfn = start_pfn; 899 arg.nr_pages = nr_pages; 900 arg.status_change_nid = -1; 901 if (nr_pages >= node_present_pages(node)) 902 arg.status_change_nid = node; 903 904 ret = memory_notify(MEM_GOING_OFFLINE, &arg); 905 ret = notifier_to_errno(ret); 906 if (ret) 907 goto failed_removal; 908 909 pfn = start_pfn; 910 expire = jiffies + timeout; 911 drain = 0; 912 retry_max = 5; 913 repeat: 914 /* start memory hot removal */ 915 ret = -EAGAIN; 916 if (time_after(jiffies, expire)) 917 goto failed_removal; 918 ret = -EINTR; 919 if (signal_pending(current)) 920 goto failed_removal; 921 ret = 0; 922 if (drain) { 923 lru_add_drain_all(); 924 cond_resched(); 925 drain_all_pages(); 926 } 927 928 pfn = scan_lru_pages(start_pfn, end_pfn); 929 if (pfn) { /* We have page on LRU */ 930 ret = do_migrate_range(pfn, end_pfn); 931 if (!ret) { 932 drain = 1; 933 goto repeat; 934 } else { 935 if (ret < 0) 936 if (--retry_max == 0) 937 goto failed_removal; 938 yield(); 939 drain = 1; 940 goto repeat; 941 } 942 } 943 /* drain all zone's lru pagevec, this is asyncronous... */ 944 lru_add_drain_all(); 945 yield(); 946 /* drain pcp pages , this is synchrouns. */ 947 drain_all_pages(); 948 /* check again */ 949 offlined_pages = check_pages_isolated(start_pfn, end_pfn); 950 if (offlined_pages < 0) { 951 ret = -EBUSY; 952 goto failed_removal; 953 } 954 printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages); 955 /* Ok, all of our target is islaoted. 956 We cannot do rollback at this point. */ 957 offline_isolated_pages(start_pfn, end_pfn); 958 /* reset pagetype flags and makes migrate type to be MOVABLE */ 959 undo_isolate_page_range(start_pfn, end_pfn); 960 /* removal success */ 961 zone->present_pages -= offlined_pages; 962 zone->zone_pgdat->node_present_pages -= offlined_pages; 963 totalram_pages -= offlined_pages; 964 965 init_per_zone_wmark_min(); 966 967 if (!node_present_pages(node)) { 968 node_clear_state(node, N_HIGH_MEMORY); 969 kswapd_stop(node); 970 } 971 972 vm_total_pages = nr_free_pagecache_pages(); 973 writeback_set_ratelimit(); 974 975 memory_notify(MEM_OFFLINE, &arg); 976 unlock_memory_hotplug(); 977 return 0; 978 979 failed_removal: 980 printk(KERN_INFO "memory offlining %lx to %lx failed\n", 981 start_pfn, end_pfn); 982 memory_notify(MEM_CANCEL_OFFLINE, &arg); 983 /* pushback to free area */ 984 undo_isolate_page_range(start_pfn, end_pfn); 985 986 out: 987 unlock_memory_hotplug(); 988 return ret; 989 } 990 991 int remove_memory(u64 start, u64 size) 992 { 993 unsigned long start_pfn, end_pfn; 994 995 start_pfn = PFN_DOWN(start); 996 end_pfn = start_pfn + PFN_DOWN(size); 997 return offline_pages(start_pfn, end_pfn, 120 * HZ); 998 } 999 #else 1000 int remove_memory(u64 start, u64 size) 1001 { 1002 return -EINVAL; 1003 } 1004 #endif /* CONFIG_MEMORY_HOTREMOVE */ 1005 EXPORT_SYMBOL_GPL(remove_memory); 1006