Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/mm/page_alloc.c
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1 /* 2 * linux/mm/page_alloc.c 3 * 4 * Manages the free list, the system allocates free pages here. 5 * Note that kmalloc() lives in slab.c 6 * 7 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 8 * Swap reorganised 29.12.95, Stephen Tweedie 9 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 10 * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999 11 * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999 12 * Zone balancing, Kanoj Sarcar, SGI, Jan 2000 13 */ 14 15 #include <linux/config.h> 16 #include <linux/mm.h> 17 #include <linux/swap.h> 18 #include <linux/swapctl.h> 19 #include <linux/interrupt.h> 20 #include <linux/pagemap.h> 21 #include <linux/bootmem.h> 22 #include <linux/slab.h> 23 #include <linux/module.h> 24 25 int nr_swap_pages; 26 int nr_active_pages; 27 int nr_inactive_pages; 28 LIST_HEAD(inactive_list); 29 LIST_HEAD(active_list); 30 pg_data_t *pgdat_list; 31 32 /* 33 * 34 * The zone_table array is used to look up the address of the 35 * struct zone corresponding to a given zone number (ZONE_DMA, 36 * ZONE_NORMAL, or ZONE_HIGHMEM). 37 */ 38 zone_t *zone_table[MAX_NR_ZONES*MAX_NR_NODES]; 39 EXPORT_SYMBOL(zone_table); 40 41 static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" }; 42 static int zone_balance_ratio[MAX_NR_ZONES] __initdata = { 128, 128, 128, }; 43 static int zone_balance_min[MAX_NR_ZONES] __initdata = { 20 , 20, 20, }; 44 static int zone_balance_max[MAX_NR_ZONES] __initdata = { 255 , 255, 255, }; 45 46 /* 47 * Temporary debugging check. 48 */ 49 #define BAD_RANGE(zone, page) \ 50 ( \ 51 (((page) - mem_map) >= ((zone)->zone_start_mapnr+(zone)->size)) \ 52 || (((page) - mem_map) < (zone)->zone_start_mapnr) \ 53 || ((zone) != page_zone(page)) \ 54 ) 55 56 /* 57 * Freeing function for a buddy system allocator. 58 * Contrary to prior comments, this is *NOT* hairy, and there 59 * is no reason for anyone not to understand it. 60 * 61 * The concept of a buddy system is to maintain direct-mapped tables 62 * (containing bit values) for memory blocks of various "orders". 63 * The bottom level table contains the map for the smallest allocatable 64 * units of memory (here, pages), and each level above it describes 65 * pairs of units from the levels below, hence, "buddies". 66 * At a high level, all that happens here is marking the table entry 67 * at the bottom level available, and propagating the changes upward 68 * as necessary, plus some accounting needed to play nicely with other 69 * parts of the VM system. 70 * At each level, we keep one bit for each pair of blocks, which 71 * is set to 1 iff only one of the pair is allocated. So when we 72 * are allocating or freeing one, we can derive the state of the 73 * other. That is, if we allocate a small block, and both were 74 * free, the remainder of the region must be split into blocks. 75 * If a block is freed, and its buddy is also free, then this 76 * triggers coalescing into a block of larger size. 77 * 78 * -- wli 79 */ 80 81 static void FASTCALL(__free_pages_ok (struct page *page, unsigned int order)); 82 static void __free_pages_ok (struct page *page, unsigned int order) 83 { 84 unsigned long index, page_idx, mask, flags; 85 free_area_t *area; 86 struct page *base; 87 zone_t *zone; 88 89 /* 90 * Yes, think what happens when other parts of the kernel take 91 * a reference to a page in order to pin it for io. -ben 92 */ 93 if (PageLRU(page)) { 94 if (unlikely(in_interrupt())) 95 BUG(); 96 lru_cache_del(page); 97 } 98 99 if (page->buffers) 100 BUG(); 101 if (page->mapping) 102 BUG(); 103 if (!VALID_PAGE(page)) 104 BUG(); 105 if (PageLocked(page)) 106 BUG(); 107 if (PageActive(page)) 108 BUG(); 109 page->flags &= ~((1<<PG_referenced) | (1<<PG_dirty)); 110 111 if (current->flags & PF_FREE_PAGES) 112 goto local_freelist; 113 back_local_freelist: 114 115 zone = page_zone(page); 116 117 mask = (~0UL) << order; 118 base = zone->zone_mem_map; 119 page_idx = page - base; 120 if (page_idx & ~mask) 121 BUG(); 122 index = page_idx >> (1 + order); 123 124 area = zone->free_area + order; 125 126 spin_lock_irqsave(&zone->lock, flags); 127 128 zone->free_pages -= mask; 129 130 while (mask + (1 << (MAX_ORDER-1))) { 131 struct page *buddy1, *buddy2; 132 133 if (area >= zone->free_area + MAX_ORDER) 134 BUG(); 135 if (!__test_and_change_bit(index, area->map)) 136 /* 137 * the buddy page is still allocated. 138 */ 139 break; 140 /* 141 * Move the buddy up one level. 142 * This code is taking advantage of the identity: 143 * -mask = 1+~mask 144 */ 145 buddy1 = base + (page_idx ^ -mask); 146 buddy2 = base + page_idx; 147 if (BAD_RANGE(zone,buddy1)) 148 BUG(); 149 if (BAD_RANGE(zone,buddy2)) 150 BUG(); 151 152 list_del(&buddy1->list); 153 mask <<= 1; 154 area++; 155 index >>= 1; 156 page_idx &= mask; 157 } 158 list_add(&(base + page_idx)->list, &area->free_list); 159 160 spin_unlock_irqrestore(&zone->lock, flags); 161 return; 162 163 local_freelist: 164 if (current->nr_local_pages) 165 goto back_local_freelist; 166 if (in_interrupt()) 167 goto back_local_freelist; 168 169 list_add(&page->list, ¤t->local_pages); 170 page->index = order; 171 current->nr_local_pages++; 172 } 173 174 #define MARK_USED(index, order, area) \ 175 __change_bit((index) >> (1+(order)), (area)->map) 176 177 static inline struct page * expand (zone_t *zone, struct page *page, 178 unsigned long index, int low, int high, free_area_t * area) 179 { 180 unsigned long size = 1 << high; 181 182 while (high > low) { 183 if (BAD_RANGE(zone,page)) 184 BUG(); 185 area--; 186 high--; 187 size >>= 1; 188 list_add(&(page)->list, &(area)->free_list); 189 MARK_USED(index, high, area); 190 index += size; 191 page += size; 192 } 193 if (BAD_RANGE(zone,page)) 194 BUG(); 195 return page; 196 } 197 198 static FASTCALL(struct page * rmqueue(zone_t *zone, unsigned int order)); 199 static struct page * rmqueue(zone_t *zone, unsigned int order) 200 { 201 free_area_t * area = zone->free_area + order; 202 unsigned int curr_order = order; 203 struct list_head *head, *curr; 204 unsigned long flags; 205 struct page *page; 206 207 spin_lock_irqsave(&zone->lock, flags); 208 do { 209 head = &area->free_list; 210 curr = head->next; 211 212 if (curr != head) { 213 unsigned int index; 214 215 page = list_entry(curr, struct page, list); 216 if (BAD_RANGE(zone,page)) 217 BUG(); 218 list_del(curr); 219 index = page - zone->zone_mem_map; 220 if (curr_order != MAX_ORDER-1) 221 MARK_USED(index, curr_order, area); 222 zone->free_pages -= 1UL << order; 223 224 page = expand(zone, page, index, order, curr_order, area); 225 spin_unlock_irqrestore(&zone->lock, flags); 226 227 set_page_count(page, 1); 228 if (BAD_RANGE(zone,page)) 229 BUG(); 230 if (PageLRU(page)) 231 BUG(); 232 if (PageActive(page)) 233 BUG(); 234 return page; 235 } 236 curr_order++; 237 area++; 238 } while (curr_order < MAX_ORDER); 239 spin_unlock_irqrestore(&zone->lock, flags); 240 241 return NULL; 242 } 243 244 #ifndef CONFIG_DISCONTIGMEM 245 struct page *_alloc_pages(unsigned int gfp_mask, unsigned int order) 246 { 247 return __alloc_pages(gfp_mask, order, 248 contig_page_data.node_zonelists+(gfp_mask & GFP_ZONEMASK)); 249 } 250 #endif 251 252 static struct page * FASTCALL(balance_classzone(zone_t *, unsigned int, unsigned int, int *)); 253 static struct page * balance_classzone(zone_t * classzone, unsigned int gfp_mask, unsigned int order, int * freed) 254 { 255 struct page * page = NULL; 256 int __freed = 0; 257 258 if (!(gfp_mask & __GFP_WAIT)) 259 goto out; 260 if (in_interrupt()) 261 BUG(); 262 263 current->allocation_order = order; 264 current->flags |= PF_MEMALLOC | PF_FREE_PAGES; 265 266 __freed = try_to_free_pages_zone(classzone, gfp_mask); 267 268 current->flags &= ~(PF_MEMALLOC | PF_FREE_PAGES); 269 270 if (current->nr_local_pages) { 271 struct list_head * entry, * local_pages; 272 struct page * tmp; 273 int nr_pages; 274 275 local_pages = ¤t->local_pages; 276 277 if (likely(__freed)) { 278 /* pick from the last inserted so we're lifo */ 279 entry = local_pages->next; 280 do { 281 tmp = list_entry(entry, struct page, list); 282 if (tmp->index == order && memclass(page_zone(tmp), classzone)) { 283 list_del(entry); 284 current->nr_local_pages--; 285 set_page_count(tmp, 1); 286 page = tmp; 287 288 if (page->buffers) 289 BUG(); 290 if (page->mapping) 291 BUG(); 292 if (!VALID_PAGE(page)) 293 BUG(); 294 if (PageLocked(page)) 295 BUG(); 296 if (PageLRU(page)) 297 BUG(); 298 if (PageActive(page)) 299 BUG(); 300 if (PageDirty(page)) 301 BUG(); 302 303 break; 304 } 305 } while ((entry = entry->next) != local_pages); 306 } 307 308 nr_pages = current->nr_local_pages; 309 /* free in reverse order so that the global order will be lifo */ 310 while ((entry = local_pages->prev) != local_pages) { 311 list_del(entry); 312 tmp = list_entry(entry, struct page, list); 313 __free_pages_ok(tmp, tmp->index); 314 if (!nr_pages--) 315 BUG(); 316 } 317 current->nr_local_pages = 0; 318 } 319 out: 320 *freed = __freed; 321 return page; 322 } 323 324 /* 325 * This is the 'heart' of the zoned buddy allocator: 326 */ 327 struct page * __alloc_pages(unsigned int gfp_mask, unsigned int order, zonelist_t *zonelist) 328 { 329 unsigned long min; 330 zone_t **zone, * classzone; 331 struct page * page; 332 int freed; 333 334 zone = zonelist->zones; 335 classzone = *zone; 336 if (classzone == NULL) 337 return NULL; 338 min = 1UL << order; 339 for (;;) { 340 zone_t *z = *(zone++); 341 if (!z) 342 break; 343 344 min += z->pages_low; 345 if (z->free_pages > min) { 346 page = rmqueue(z, order); 347 if (page) 348 return page; 349 } 350 } 351 352 classzone->need_balance = 1; 353 mb(); 354 if (waitqueue_active(&kswapd_wait)) 355 wake_up_interruptible(&kswapd_wait); 356 357 zone = zonelist->zones; 358 min = 1UL << order; 359 for (;;) { 360 unsigned long local_min; 361 zone_t *z = *(zone++); 362 if (!z) 363 break; 364 365 local_min = z->pages_min; 366 if (!(gfp_mask & __GFP_WAIT)) 367 local_min >>= 2; 368 min += local_min; 369 if (z->free_pages > min) { 370 page = rmqueue(z, order); 371 if (page) 372 return page; 373 } 374 } 375 376 /* here we're in the low on memory slow path */ 377 378 rebalance: 379 if (current->flags & (PF_MEMALLOC | PF_MEMDIE)) { 380 zone = zonelist->zones; 381 for (;;) { 382 zone_t *z = *(zone++); 383 if (!z) 384 break; 385 386 page = rmqueue(z, order); 387 if (page) 388 return page; 389 } 390 return NULL; 391 } 392 393 /* Atomic allocations - we can't balance anything */ 394 if (!(gfp_mask & __GFP_WAIT)) 395 return NULL; 396 397 page = balance_classzone(classzone, gfp_mask, order, &freed); 398 if (page) 399 return page; 400 401 zone = zonelist->zones; 402 min = 1UL << order; 403 for (;;) { 404 zone_t *z = *(zone++); 405 if (!z) 406 break; 407 408 min += z->pages_min; 409 if (z->free_pages > min) { 410 page = rmqueue(z, order); 411 if (page) 412 return page; 413 } 414 } 415 416 /* Don't let big-order allocations loop */ 417 if (order > 3) 418 return NULL; 419 420 /* Yield for kswapd, and try again */ 421 yield(); 422 goto rebalance; 423 } 424 425 /* 426 * Common helper functions. 427 */ 428 unsigned long __get_free_pages(unsigned int gfp_mask, unsigned int order) 429 { 430 struct page * page; 431 432 page = alloc_pages(gfp_mask, order); 433 if (!page) 434 return 0; 435 return (unsigned long) page_address(page); 436 } 437 438 unsigned long get_zeroed_page(unsigned int gfp_mask) 439 { 440 struct page * page; 441 442 page = alloc_pages(gfp_mask, 0); 443 if (page) { 444 void *address = page_address(page); 445 clear_page(address); 446 return (unsigned long) address; 447 } 448 return 0; 449 } 450 451 void __free_pages(struct page *page, unsigned int order) 452 { 453 if (!PageReserved(page) && put_page_testzero(page)) 454 __free_pages_ok(page, order); 455 } 456 457 void free_pages(unsigned long addr, unsigned int order) 458 { 459 if (addr != 0) 460 __free_pages(virt_to_page(addr), order); 461 } 462 463 /* 464 * Total amount of free (allocatable) RAM: 465 */ 466 unsigned int nr_free_pages (void) 467 { 468 unsigned int sum = 0; 469 zone_t *zone; 470 471 for_each_zone(zone) 472 sum += zone->free_pages; 473 474 return sum; 475 } 476 477 /* 478 * Amount of free RAM allocatable as buffer memory: 479 */ 480 unsigned int nr_free_buffer_pages (void) 481 { 482 pg_data_t *pgdat; 483 unsigned int sum = 0; 484 485 for_each_pgdat(pgdat) { 486 zonelist_t *zonelist = pgdat->node_zonelists + (GFP_USER & GFP_ZONEMASK); 487 zone_t **zonep = zonelist->zones; 488 zone_t *zone; 489 490 for (zone = *zonep++; zone; zone = *zonep++) { 491 unsigned long size = zone->size; 492 unsigned long high = zone->pages_high; 493 if (size > high) 494 sum += size - high; 495 } 496 } 497 498 return sum; 499 } 500 501 #if CONFIG_HIGHMEM 502 unsigned int nr_free_highpages (void) 503 { 504 pg_data_t *pgdat; 505 unsigned int pages = 0; 506 507 for_each_pgdat(pgdat) 508 pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages; 509 510 return pages; 511 } 512 #endif 513 514 #define K(x) ((x) << (PAGE_SHIFT-10)) 515 516 /* 517 * Show free area list (used inside shift_scroll-lock stuff) 518 * We also calculate the percentage fragmentation. We do this by counting the 519 * memory on each free list with the exception of the first item on the list. 520 */ 521 void show_free_areas_core(pg_data_t *pgdat) 522 { 523 unsigned int order; 524 unsigned type; 525 pg_data_t *tmpdat = pgdat; 526 527 printk("Free pages: %6dkB (%6dkB HighMem)\n", 528 K(nr_free_pages()), 529 K(nr_free_highpages())); 530 531 while (tmpdat) { 532 zone_t *zone; 533 for (zone = tmpdat->node_zones; 534 zone < tmpdat->node_zones + MAX_NR_ZONES; zone++) 535 printk("Zone:%s freepages:%6lukB min:%6lukB low:%6lukB " 536 "high:%6lukB\n", 537 zone->name, 538 K(zone->free_pages), 539 K(zone->pages_min), 540 K(zone->pages_low), 541 K(zone->pages_high)); 542 543 tmpdat = tmpdat->node_next; 544 } 545 546 printk("( Active: %d, inactive: %d, free: %d )\n", 547 nr_active_pages, 548 nr_inactive_pages, 549 nr_free_pages()); 550 551 for (type = 0; type < MAX_NR_ZONES; type++) { 552 struct list_head *head, *curr; 553 zone_t *zone = pgdat->node_zones + type; 554 unsigned long nr, total, flags; 555 556 total = 0; 557 if (zone->size) { 558 spin_lock_irqsave(&zone->lock, flags); 559 for (order = 0; order < MAX_ORDER; order++) { 560 head = &(zone->free_area + order)->free_list; 561 curr = head; 562 nr = 0; 563 for (;;) { 564 if ((curr = curr->next) == head) 565 break; 566 nr++; 567 } 568 total += nr * (1 << order); 569 printk("%lu*%lukB ", nr, K(1UL) << order); 570 } 571 spin_unlock_irqrestore(&zone->lock, flags); 572 } 573 printk("= %lukB)\n", K(total)); 574 } 575 576 #ifdef SWAP_CACHE_INFO 577 show_swap_cache_info(); 578 #endif 579 } 580 581 void show_free_areas(void) 582 { 583 show_free_areas_core(pgdat_list); 584 } 585 586 /* 587 * Builds allocation fallback zone lists. 588 */ 589 static inline void build_zonelists(pg_data_t *pgdat) 590 { 591 int i, j, k; 592 593 for (i = 0; i <= GFP_ZONEMASK; i++) { 594 zonelist_t *zonelist; 595 zone_t *zone; 596 597 zonelist = pgdat->node_zonelists + i; 598 memset(zonelist, 0, sizeof(*zonelist)); 599 600 j = 0; 601 k = ZONE_NORMAL; 602 if (i & __GFP_HIGHMEM) 603 k = ZONE_HIGHMEM; 604 if (i & __GFP_DMA) 605 k = ZONE_DMA; 606 607 switch (k) { 608 default: 609 BUG(); 610 /* 611 * fallthrough: 612 */ 613 case ZONE_HIGHMEM: 614 zone = pgdat->node_zones + ZONE_HIGHMEM; 615 if (zone->size) { 616 #ifndef CONFIG_HIGHMEM 617 BUG(); 618 #endif 619 zonelist->zones[j++] = zone; 620 } 621 case ZONE_NORMAL: 622 zone = pgdat->node_zones + ZONE_NORMAL; 623 if (zone->size) 624 zonelist->zones[j++] = zone; 625 case ZONE_DMA: 626 zone = pgdat->node_zones + ZONE_DMA; 627 if (zone->size) 628 zonelist->zones[j++] = zone; 629 } 630 zonelist->zones[j++] = NULL; 631 } 632 } 633 634 /* 635 * Helper functions to size the waitqueue hash table. 636 * Essentially these want to choose hash table sizes sufficiently 637 * large so that collisions trying to wait on pages are rare. 638 * But in fact, the number of active page waitqueues on typical 639 * systems is ridiculously low, less than 200. So this is even 640 * conservative, even though it seems large. 641 * 642 * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to 643 * waitqueues, i.e. the size of the waitq table given the number of pages. 644 */ 645 #define PAGES_PER_WAITQUEUE 256 646 647 static inline unsigned long wait_table_size(unsigned long pages) 648 { 649 unsigned long size = 1; 650 651 pages /= PAGES_PER_WAITQUEUE; 652 653 while (size < pages) 654 size <<= 1; 655 656 /* 657 * Once we have dozens or even hundreds of threads sleeping 658 * on IO we've got bigger problems than wait queue collision. 659 * Limit the size of the wait table to a reasonable size. 660 */ 661 size = min(size, 4096UL); 662 663 return size; 664 } 665 666 /* 667 * This is an integer logarithm so that shifts can be used later 668 * to extract the more random high bits from the multiplicative 669 * hash function before the remainder is taken. 670 */ 671 static inline unsigned long wait_table_bits(unsigned long size) 672 { 673 return ffz(~size); 674 } 675 676 #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1)) 677 678 /* 679 * Set up the zone data structures: 680 * - mark all pages reserved 681 * - mark all memory queues empty 682 * - clear the memory bitmaps 683 */ 684 void __init free_area_init_core(int nid, pg_data_t *pgdat, struct page **gmap, 685 unsigned long *zones_size, unsigned long zone_start_paddr, 686 unsigned long *zholes_size, struct page *lmem_map) 687 { 688 unsigned long i, j; 689 unsigned long map_size; 690 unsigned long totalpages, offset, realtotalpages; 691 const unsigned long zone_required_alignment = 1UL << (MAX_ORDER-1); 692 693 if (zone_start_paddr & ~PAGE_MASK) 694 BUG(); 695 696 totalpages = 0; 697 for (i = 0; i < MAX_NR_ZONES; i++) { 698 unsigned long size = zones_size[i]; 699 totalpages += size; 700 } 701 realtotalpages = totalpages; 702 if (zholes_size) 703 for (i = 0; i < MAX_NR_ZONES; i++) 704 realtotalpages -= zholes_size[i]; 705 706 printk("On node %d totalpages: %lu\n", nid, realtotalpages); 707 708 /* 709 * Some architectures (with lots of mem and discontinous memory 710 * maps) have to search for a good mem_map area: 711 * For discontigmem, the conceptual mem map array starts from 712 * PAGE_OFFSET, we need to align the actual array onto a mem map 713 * boundary, so that MAP_NR works. 714 */ 715 map_size = (totalpages + 1)*sizeof(struct page); 716 if (lmem_map == (struct page *)0) { 717 lmem_map = (struct page *) alloc_bootmem_node(pgdat, map_size); 718 lmem_map = (struct page *)(PAGE_OFFSET + 719 MAP_ALIGN((unsigned long)lmem_map - PAGE_OFFSET)); 720 } 721 *gmap = pgdat->node_mem_map = lmem_map; 722 pgdat->node_size = totalpages; 723 pgdat->node_start_paddr = zone_start_paddr; 724 pgdat->node_start_mapnr = (lmem_map - mem_map); 725 pgdat->nr_zones = 0; 726 727 offset = lmem_map - mem_map; 728 for (j = 0; j < MAX_NR_ZONES; j++) { 729 zone_t *zone = pgdat->node_zones + j; 730 unsigned long mask; 731 unsigned long size, realsize; 732 733 zone_table[nid * MAX_NR_ZONES + j] = zone; 734 realsize = size = zones_size[j]; 735 if (zholes_size) 736 realsize -= zholes_size[j]; 737 738 printk("zone(%lu): %lu pages.\n", j, size); 739 zone->size = size; 740 zone->name = zone_names[j]; 741 zone->lock = SPIN_LOCK_UNLOCKED; 742 zone->zone_pgdat = pgdat; 743 zone->free_pages = 0; 744 zone->need_balance = 0; 745 if (!size) 746 continue; 747 748 /* 749 * The per-page waitqueue mechanism uses hashed waitqueues 750 * per zone. 751 */ 752 zone->wait_table_size = wait_table_size(size); 753 zone->wait_table_shift = 754 BITS_PER_LONG - wait_table_bits(zone->wait_table_size); 755 zone->wait_table = (wait_queue_head_t *) 756 alloc_bootmem_node(pgdat, zone->wait_table_size 757 * sizeof(wait_queue_head_t)); 758 759 for(i = 0; i < zone->wait_table_size; ++i) 760 init_waitqueue_head(zone->wait_table + i); 761 762 pgdat->nr_zones = j+1; 763 764 mask = (realsize / zone_balance_ratio[j]); 765 if (mask < zone_balance_min[j]) 766 mask = zone_balance_min[j]; 767 else if (mask > zone_balance_max[j]) 768 mask = zone_balance_max[j]; 769 zone->pages_min = mask; 770 zone->pages_low = mask*2; 771 zone->pages_high = mask*3; 772 773 zone->zone_mem_map = mem_map + offset; 774 zone->zone_start_mapnr = offset; 775 zone->zone_start_paddr = zone_start_paddr; 776 777 if ((zone_start_paddr >> PAGE_SHIFT) & (zone_required_alignment-1)) 778 printk("BUG: wrong zone alignment, it will crash\n"); 779 780 /* 781 * Initially all pages are reserved - free ones are freed 782 * up by free_all_bootmem() once the early boot process is 783 * done. Non-atomic initialization, single-pass. 784 */ 785 for (i = 0; i < size; i++) { 786 struct page *page = mem_map + offset + i; 787 set_page_zone(page, nid * MAX_NR_ZONES + j); 788 set_page_count(page, 0); 789 SetPageReserved(page); 790 INIT_LIST_HEAD(&page->list); 791 if (j != ZONE_HIGHMEM) 792 set_page_address(page, __va(zone_start_paddr)); 793 zone_start_paddr += PAGE_SIZE; 794 } 795 796 offset += size; 797 for (i = 0; ; i++) { 798 unsigned long bitmap_size; 799 800 INIT_LIST_HEAD(&zone->free_area[i].free_list); 801 if (i == MAX_ORDER-1) { 802 zone->free_area[i].map = NULL; 803 break; 804 } 805 806 /* 807 * Page buddy system uses "index >> (i+1)", 808 * where "index" is at most "size-1". 809 * 810 * The extra "+3" is to round down to byte 811 * size (8 bits per byte assumption). Thus 812 * we get "(size-1) >> (i+4)" as the last byte 813 * we can access. 814 * 815 * The "+1" is because we want to round the 816 * byte allocation up rather than down. So 817 * we should have had a "+7" before we shifted 818 * down by three. Also, we have to add one as 819 * we actually _use_ the last bit (it's [0,n] 820 * inclusive, not [0,n[). 821 * 822 * So we actually had +7+1 before we shift 823 * down by 3. But (n+8) >> 3 == (n >> 3) + 1 824 * (modulo overflows, which we do not have). 825 * 826 * Finally, we LONG_ALIGN because all bitmap 827 * operations are on longs. 828 */ 829 bitmap_size = (size-1) >> (i+4); 830 bitmap_size = LONG_ALIGN(bitmap_size+1); 831 zone->free_area[i].map = 832 (unsigned long *) alloc_bootmem_node(pgdat, bitmap_size); 833 } 834 } 835 build_zonelists(pgdat); 836 } 837 838 void __init free_area_init(unsigned long *zones_size) 839 { 840 free_area_init_core(0, &contig_page_data, &mem_map, zones_size, 0, 0, 0); 841 } 842 843 static int __init setup_mem_frac(char *str) 844 { 845 int j = 0; 846 847 while (get_option(&str, &zone_balance_ratio[j++]) == 2); 848 printk("setup_mem_frac: "); 849 for (j = 0; j < MAX_NR_ZONES; j++) printk("%d ", zone_balance_ratio[j]); 850 printk("\n"); 851 return 1; 852 } 853 854 __setup("memfrac=", setup_mem_frac);
Cache object: 10104706c3679e3f366696e72e755642
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