hugetlb.c revision 0fe6e20b9c4c53b3e97096ee73a0857f60aad43f
1/* 2 * Generic hugetlb support. 3 * (C) William Irwin, April 2004 4 */ 5#include <linux/list.h> 6#include <linux/init.h> 7#include <linux/module.h> 8#include <linux/mm.h> 9#include <linux/seq_file.h> 10#include <linux/sysctl.h> 11#include <linux/highmem.h> 12#include <linux/mmu_notifier.h> 13#include <linux/nodemask.h> 14#include <linux/pagemap.h> 15#include <linux/mempolicy.h> 16#include <linux/cpuset.h> 17#include <linux/mutex.h> 18#include <linux/bootmem.h> 19#include <linux/sysfs.h> 20#include <linux/slab.h> 21#include <linux/rmap.h> 22 23#include <asm/page.h> 24#include <asm/pgtable.h> 25#include <asm/io.h> 26 27#include <linux/hugetlb.h> 28#include <linux/node.h> 29#include "internal.h" 30 31const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; 32static gfp_t htlb_alloc_mask = GFP_HIGHUSER; 33unsigned long hugepages_treat_as_movable; 34 35static int max_hstate; 36unsigned int default_hstate_idx; 37struct hstate hstates[HUGE_MAX_HSTATE]; 38 39__initdata LIST_HEAD(huge_boot_pages); 40 41/* for command line parsing */ 42static struct hstate * __initdata parsed_hstate; 43static unsigned long __initdata default_hstate_max_huge_pages; 44static unsigned long __initdata default_hstate_size; 45 46#define for_each_hstate(h) \ 47 for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++) 48 49/* 50 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages 51 */ 52static DEFINE_SPINLOCK(hugetlb_lock); 53 54/* 55 * Region tracking -- allows tracking of reservations and instantiated pages 56 * across the pages in a mapping. 57 * 58 * The region data structures are protected by a combination of the mmap_sem 59 * and the hugetlb_instantion_mutex. To access or modify a region the caller 60 * must either hold the mmap_sem for write, or the mmap_sem for read and 61 * the hugetlb_instantiation mutex: 62 * 63 * down_write(&mm->mmap_sem); 64 * or 65 * down_read(&mm->mmap_sem); 66 * mutex_lock(&hugetlb_instantiation_mutex); 67 */ 68struct file_region { 69 struct list_head link; 70 long from; 71 long to; 72}; 73 74static long region_add(struct list_head *head, long f, long t) 75{ 76 struct file_region *rg, *nrg, *trg; 77 78 /* Locate the region we are either in or before. */ 79 list_for_each_entry(rg, head, link) 80 if (f <= rg->to) 81 break; 82 83 /* Round our left edge to the current segment if it encloses us. */ 84 if (f > rg->from) 85 f = rg->from; 86 87 /* Check for and consume any regions we now overlap with. */ 88 nrg = rg; 89 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 90 if (&rg->link == head) 91 break; 92 if (rg->from > t) 93 break; 94 95 /* If this area reaches higher then extend our area to 96 * include it completely. If this is not the first area 97 * which we intend to reuse, free it. */ 98 if (rg->to > t) 99 t = rg->to; 100 if (rg != nrg) { 101 list_del(&rg->link); 102 kfree(rg); 103 } 104 } 105 nrg->from = f; 106 nrg->to = t; 107 return 0; 108} 109 110static long region_chg(struct list_head *head, long f, long t) 111{ 112 struct file_region *rg, *nrg; 113 long chg = 0; 114 115 /* Locate the region we are before or in. */ 116 list_for_each_entry(rg, head, link) 117 if (f <= rg->to) 118 break; 119 120 /* If we are below the current region then a new region is required. 121 * Subtle, allocate a new region at the position but make it zero 122 * size such that we can guarantee to record the reservation. */ 123 if (&rg->link == head || t < rg->from) { 124 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); 125 if (!nrg) 126 return -ENOMEM; 127 nrg->from = f; 128 nrg->to = f; 129 INIT_LIST_HEAD(&nrg->link); 130 list_add(&nrg->link, rg->link.prev); 131 132 return t - f; 133 } 134 135 /* Round our left edge to the current segment if it encloses us. */ 136 if (f > rg->from) 137 f = rg->from; 138 chg = t - f; 139 140 /* Check for and consume any regions we now overlap with. */ 141 list_for_each_entry(rg, rg->link.prev, link) { 142 if (&rg->link == head) 143 break; 144 if (rg->from > t) 145 return chg; 146 147 /* We overlap with this area, if it extends futher than 148 * us then we must extend ourselves. Account for its 149 * existing reservation. */ 150 if (rg->to > t) { 151 chg += rg->to - t; 152 t = rg->to; 153 } 154 chg -= rg->to - rg->from; 155 } 156 return chg; 157} 158 159static long region_truncate(struct list_head *head, long end) 160{ 161 struct file_region *rg, *trg; 162 long chg = 0; 163 164 /* Locate the region we are either in or before. */ 165 list_for_each_entry(rg, head, link) 166 if (end <= rg->to) 167 break; 168 if (&rg->link == head) 169 return 0; 170 171 /* If we are in the middle of a region then adjust it. */ 172 if (end > rg->from) { 173 chg = rg->to - end; 174 rg->to = end; 175 rg = list_entry(rg->link.next, typeof(*rg), link); 176 } 177 178 /* Drop any remaining regions. */ 179 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 180 if (&rg->link == head) 181 break; 182 chg += rg->to - rg->from; 183 list_del(&rg->link); 184 kfree(rg); 185 } 186 return chg; 187} 188 189static long region_count(struct list_head *head, long f, long t) 190{ 191 struct file_region *rg; 192 long chg = 0; 193 194 /* Locate each segment we overlap with, and count that overlap. */ 195 list_for_each_entry(rg, head, link) { 196 int seg_from; 197 int seg_to; 198 199 if (rg->to <= f) 200 continue; 201 if (rg->from >= t) 202 break; 203 204 seg_from = max(rg->from, f); 205 seg_to = min(rg->to, t); 206 207 chg += seg_to - seg_from; 208 } 209 210 return chg; 211} 212 213/* 214 * Convert the address within this vma to the page offset within 215 * the mapping, in pagecache page units; huge pages here. 216 */ 217static pgoff_t vma_hugecache_offset(struct hstate *h, 218 struct vm_area_struct *vma, unsigned long address) 219{ 220 return ((address - vma->vm_start) >> huge_page_shift(h)) + 221 (vma->vm_pgoff >> huge_page_order(h)); 222} 223 224pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 225 unsigned long address) 226{ 227 return vma_hugecache_offset(hstate_vma(vma), vma, address); 228} 229 230/* 231 * Return the size of the pages allocated when backing a VMA. In the majority 232 * cases this will be same size as used by the page table entries. 233 */ 234unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) 235{ 236 struct hstate *hstate; 237 238 if (!is_vm_hugetlb_page(vma)) 239 return PAGE_SIZE; 240 241 hstate = hstate_vma(vma); 242 243 return 1UL << (hstate->order + PAGE_SHIFT); 244} 245EXPORT_SYMBOL_GPL(vma_kernel_pagesize); 246 247/* 248 * Return the page size being used by the MMU to back a VMA. In the majority 249 * of cases, the page size used by the kernel matches the MMU size. On 250 * architectures where it differs, an architecture-specific version of this 251 * function is required. 252 */ 253#ifndef vma_mmu_pagesize 254unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) 255{ 256 return vma_kernel_pagesize(vma); 257} 258#endif 259 260/* 261 * Flags for MAP_PRIVATE reservations. These are stored in the bottom 262 * bits of the reservation map pointer, which are always clear due to 263 * alignment. 264 */ 265#define HPAGE_RESV_OWNER (1UL << 0) 266#define HPAGE_RESV_UNMAPPED (1UL << 1) 267#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) 268 269/* 270 * These helpers are used to track how many pages are reserved for 271 * faults in a MAP_PRIVATE mapping. Only the process that called mmap() 272 * is guaranteed to have their future faults succeed. 273 * 274 * With the exception of reset_vma_resv_huge_pages() which is called at fork(), 275 * the reserve counters are updated with the hugetlb_lock held. It is safe 276 * to reset the VMA at fork() time as it is not in use yet and there is no 277 * chance of the global counters getting corrupted as a result of the values. 278 * 279 * The private mapping reservation is represented in a subtly different 280 * manner to a shared mapping. A shared mapping has a region map associated 281 * with the underlying file, this region map represents the backing file 282 * pages which have ever had a reservation assigned which this persists even 283 * after the page is instantiated. A private mapping has a region map 284 * associated with the original mmap which is attached to all VMAs which 285 * reference it, this region map represents those offsets which have consumed 286 * reservation ie. where pages have been instantiated. 287 */ 288static unsigned long get_vma_private_data(struct vm_area_struct *vma) 289{ 290 return (unsigned long)vma->vm_private_data; 291} 292 293static void set_vma_private_data(struct vm_area_struct *vma, 294 unsigned long value) 295{ 296 vma->vm_private_data = (void *)value; 297} 298 299struct resv_map { 300 struct kref refs; 301 struct list_head regions; 302}; 303 304static struct resv_map *resv_map_alloc(void) 305{ 306 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); 307 if (!resv_map) 308 return NULL; 309 310 kref_init(&resv_map->refs); 311 INIT_LIST_HEAD(&resv_map->regions); 312 313 return resv_map; 314} 315 316static void resv_map_release(struct kref *ref) 317{ 318 struct resv_map *resv_map = container_of(ref, struct resv_map, refs); 319 320 /* Clear out any active regions before we release the map. */ 321 region_truncate(&resv_map->regions, 0); 322 kfree(resv_map); 323} 324 325static struct resv_map *vma_resv_map(struct vm_area_struct *vma) 326{ 327 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 328 if (!(vma->vm_flags & VM_MAYSHARE)) 329 return (struct resv_map *)(get_vma_private_data(vma) & 330 ~HPAGE_RESV_MASK); 331 return NULL; 332} 333 334static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) 335{ 336 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 337 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 338 339 set_vma_private_data(vma, (get_vma_private_data(vma) & 340 HPAGE_RESV_MASK) | (unsigned long)map); 341} 342 343static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) 344{ 345 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 346 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 347 348 set_vma_private_data(vma, get_vma_private_data(vma) | flags); 349} 350 351static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) 352{ 353 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 354 355 return (get_vma_private_data(vma) & flag) != 0; 356} 357 358/* Decrement the reserved pages in the hugepage pool by one */ 359static void decrement_hugepage_resv_vma(struct hstate *h, 360 struct vm_area_struct *vma) 361{ 362 if (vma->vm_flags & VM_NORESERVE) 363 return; 364 365 if (vma->vm_flags & VM_MAYSHARE) { 366 /* Shared mappings always use reserves */ 367 h->resv_huge_pages--; 368 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 369 /* 370 * Only the process that called mmap() has reserves for 371 * private mappings. 372 */ 373 h->resv_huge_pages--; 374 } 375} 376 377/* Reset counters to 0 and clear all HPAGE_RESV_* flags */ 378void reset_vma_resv_huge_pages(struct vm_area_struct *vma) 379{ 380 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 381 if (!(vma->vm_flags & VM_MAYSHARE)) 382 vma->vm_private_data = (void *)0; 383} 384 385/* Returns true if the VMA has associated reserve pages */ 386static int vma_has_reserves(struct vm_area_struct *vma) 387{ 388 if (vma->vm_flags & VM_MAYSHARE) 389 return 1; 390 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 391 return 1; 392 return 0; 393} 394 395static void clear_gigantic_page(struct page *page, 396 unsigned long addr, unsigned long sz) 397{ 398 int i; 399 struct page *p = page; 400 401 might_sleep(); 402 for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) { 403 cond_resched(); 404 clear_user_highpage(p, addr + i * PAGE_SIZE); 405 } 406} 407static void clear_huge_page(struct page *page, 408 unsigned long addr, unsigned long sz) 409{ 410 int i; 411 412 if (unlikely(sz/PAGE_SIZE > MAX_ORDER_NR_PAGES)) { 413 clear_gigantic_page(page, addr, sz); 414 return; 415 } 416 417 might_sleep(); 418 for (i = 0; i < sz/PAGE_SIZE; i++) { 419 cond_resched(); 420 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 421 } 422} 423 424static void copy_gigantic_page(struct page *dst, struct page *src, 425 unsigned long addr, struct vm_area_struct *vma) 426{ 427 int i; 428 struct hstate *h = hstate_vma(vma); 429 struct page *dst_base = dst; 430 struct page *src_base = src; 431 might_sleep(); 432 for (i = 0; i < pages_per_huge_page(h); ) { 433 cond_resched(); 434 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 435 436 i++; 437 dst = mem_map_next(dst, dst_base, i); 438 src = mem_map_next(src, src_base, i); 439 } 440} 441static void copy_huge_page(struct page *dst, struct page *src, 442 unsigned long addr, struct vm_area_struct *vma) 443{ 444 int i; 445 struct hstate *h = hstate_vma(vma); 446 447 if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { 448 copy_gigantic_page(dst, src, addr, vma); 449 return; 450 } 451 452 might_sleep(); 453 for (i = 0; i < pages_per_huge_page(h); i++) { 454 cond_resched(); 455 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 456 } 457} 458 459static void enqueue_huge_page(struct hstate *h, struct page *page) 460{ 461 int nid = page_to_nid(page); 462 list_add(&page->lru, &h->hugepage_freelists[nid]); 463 h->free_huge_pages++; 464 h->free_huge_pages_node[nid]++; 465} 466 467static struct page *dequeue_huge_page_vma(struct hstate *h, 468 struct vm_area_struct *vma, 469 unsigned long address, int avoid_reserve) 470{ 471 int nid; 472 struct page *page = NULL; 473 struct mempolicy *mpol; 474 nodemask_t *nodemask; 475 struct zonelist *zonelist; 476 struct zone *zone; 477 struct zoneref *z; 478 479 get_mems_allowed(); 480 zonelist = huge_zonelist(vma, address, 481 htlb_alloc_mask, &mpol, &nodemask); 482 /* 483 * A child process with MAP_PRIVATE mappings created by their parent 484 * have no page reserves. This check ensures that reservations are 485 * not "stolen". The child may still get SIGKILLed 486 */ 487 if (!vma_has_reserves(vma) && 488 h->free_huge_pages - h->resv_huge_pages == 0) 489 goto err; 490 491 /* If reserves cannot be used, ensure enough pages are in the pool */ 492 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) 493 goto err;; 494 495 for_each_zone_zonelist_nodemask(zone, z, zonelist, 496 MAX_NR_ZONES - 1, nodemask) { 497 nid = zone_to_nid(zone); 498 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) && 499 !list_empty(&h->hugepage_freelists[nid])) { 500 page = list_entry(h->hugepage_freelists[nid].next, 501 struct page, lru); 502 list_del(&page->lru); 503 h->free_huge_pages--; 504 h->free_huge_pages_node[nid]--; 505 506 if (!avoid_reserve) 507 decrement_hugepage_resv_vma(h, vma); 508 509 break; 510 } 511 } 512err: 513 mpol_cond_put(mpol); 514 put_mems_allowed(); 515 return page; 516} 517 518static void update_and_free_page(struct hstate *h, struct page *page) 519{ 520 int i; 521 522 VM_BUG_ON(h->order >= MAX_ORDER); 523 524 h->nr_huge_pages--; 525 h->nr_huge_pages_node[page_to_nid(page)]--; 526 for (i = 0; i < pages_per_huge_page(h); i++) { 527 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 528 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved | 529 1 << PG_private | 1<< PG_writeback); 530 } 531 set_compound_page_dtor(page, NULL); 532 set_page_refcounted(page); 533 arch_release_hugepage(page); 534 __free_pages(page, huge_page_order(h)); 535} 536 537struct hstate *size_to_hstate(unsigned long size) 538{ 539 struct hstate *h; 540 541 for_each_hstate(h) { 542 if (huge_page_size(h) == size) 543 return h; 544 } 545 return NULL; 546} 547 548static void free_huge_page(struct page *page) 549{ 550 /* 551 * Can't pass hstate in here because it is called from the 552 * compound page destructor. 553 */ 554 struct hstate *h = page_hstate(page); 555 int nid = page_to_nid(page); 556 struct address_space *mapping; 557 558 mapping = (struct address_space *) page_private(page); 559 set_page_private(page, 0); 560 page->mapping = NULL; 561 BUG_ON(page_count(page)); 562 BUG_ON(page_mapcount(page)); 563 INIT_LIST_HEAD(&page->lru); 564 565 spin_lock(&hugetlb_lock); 566 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { 567 update_and_free_page(h, page); 568 h->surplus_huge_pages--; 569 h->surplus_huge_pages_node[nid]--; 570 } else { 571 enqueue_huge_page(h, page); 572 } 573 spin_unlock(&hugetlb_lock); 574 if (mapping) 575 hugetlb_put_quota(mapping, 1); 576} 577 578static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) 579{ 580 set_compound_page_dtor(page, free_huge_page); 581 spin_lock(&hugetlb_lock); 582 h->nr_huge_pages++; 583 h->nr_huge_pages_node[nid]++; 584 spin_unlock(&hugetlb_lock); 585 put_page(page); /* free it into the hugepage allocator */ 586} 587 588static void prep_compound_gigantic_page(struct page *page, unsigned long order) 589{ 590 int i; 591 int nr_pages = 1 << order; 592 struct page *p = page + 1; 593 594 /* we rely on prep_new_huge_page to set the destructor */ 595 set_compound_order(page, order); 596 __SetPageHead(page); 597 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { 598 __SetPageTail(p); 599 p->first_page = page; 600 } 601} 602 603int PageHuge(struct page *page) 604{ 605 compound_page_dtor *dtor; 606 607 if (!PageCompound(page)) 608 return 0; 609 610 page = compound_head(page); 611 dtor = get_compound_page_dtor(page); 612 613 return dtor == free_huge_page; 614} 615 616static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 617{ 618 struct page *page; 619 620 if (h->order >= MAX_ORDER) 621 return NULL; 622 623 page = alloc_pages_exact_node(nid, 624 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 625 __GFP_REPEAT|__GFP_NOWARN, 626 huge_page_order(h)); 627 if (page) { 628 if (arch_prepare_hugepage(page)) { 629 __free_pages(page, huge_page_order(h)); 630 return NULL; 631 } 632 prep_new_huge_page(h, page, nid); 633 } 634 635 return page; 636} 637 638/* 639 * common helper functions for hstate_next_node_to_{alloc|free}. 640 * We may have allocated or freed a huge page based on a different 641 * nodes_allowed previously, so h->next_node_to_{alloc|free} might 642 * be outside of *nodes_allowed. Ensure that we use an allowed 643 * node for alloc or free. 644 */ 645static int next_node_allowed(int nid, nodemask_t *nodes_allowed) 646{ 647 nid = next_node(nid, *nodes_allowed); 648 if (nid == MAX_NUMNODES) 649 nid = first_node(*nodes_allowed); 650 VM_BUG_ON(nid >= MAX_NUMNODES); 651 652 return nid; 653} 654 655static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) 656{ 657 if (!node_isset(nid, *nodes_allowed)) 658 nid = next_node_allowed(nid, nodes_allowed); 659 return nid; 660} 661 662/* 663 * returns the previously saved node ["this node"] from which to 664 * allocate a persistent huge page for the pool and advance the 665 * next node from which to allocate, handling wrap at end of node 666 * mask. 667 */ 668static int hstate_next_node_to_alloc(struct hstate *h, 669 nodemask_t *nodes_allowed) 670{ 671 int nid; 672 673 VM_BUG_ON(!nodes_allowed); 674 675 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); 676 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); 677 678 return nid; 679} 680 681static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) 682{ 683 struct page *page; 684 int start_nid; 685 int next_nid; 686 int ret = 0; 687 688 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 689 next_nid = start_nid; 690 691 do { 692 page = alloc_fresh_huge_page_node(h, next_nid); 693 if (page) { 694 ret = 1; 695 break; 696 } 697 next_nid = hstate_next_node_to_alloc(h, nodes_allowed); 698 } while (next_nid != start_nid); 699 700 if (ret) 701 count_vm_event(HTLB_BUDDY_PGALLOC); 702 else 703 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 704 705 return ret; 706} 707 708/* 709 * helper for free_pool_huge_page() - return the previously saved 710 * node ["this node"] from which to free a huge page. Advance the 711 * next node id whether or not we find a free huge page to free so 712 * that the next attempt to free addresses the next node. 713 */ 714static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) 715{ 716 int nid; 717 718 VM_BUG_ON(!nodes_allowed); 719 720 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); 721 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); 722 723 return nid; 724} 725 726/* 727 * Free huge page from pool from next node to free. 728 * Attempt to keep persistent huge pages more or less 729 * balanced over allowed nodes. 730 * Called with hugetlb_lock locked. 731 */ 732static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, 733 bool acct_surplus) 734{ 735 int start_nid; 736 int next_nid; 737 int ret = 0; 738 739 start_nid = hstate_next_node_to_free(h, nodes_allowed); 740 next_nid = start_nid; 741 742 do { 743 /* 744 * If we're returning unused surplus pages, only examine 745 * nodes with surplus pages. 746 */ 747 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) && 748 !list_empty(&h->hugepage_freelists[next_nid])) { 749 struct page *page = 750 list_entry(h->hugepage_freelists[next_nid].next, 751 struct page, lru); 752 list_del(&page->lru); 753 h->free_huge_pages--; 754 h->free_huge_pages_node[next_nid]--; 755 if (acct_surplus) { 756 h->surplus_huge_pages--; 757 h->surplus_huge_pages_node[next_nid]--; 758 } 759 update_and_free_page(h, page); 760 ret = 1; 761 break; 762 } 763 next_nid = hstate_next_node_to_free(h, nodes_allowed); 764 } while (next_nid != start_nid); 765 766 return ret; 767} 768 769static struct page *alloc_buddy_huge_page(struct hstate *h, 770 struct vm_area_struct *vma, unsigned long address) 771{ 772 struct page *page; 773 unsigned int nid; 774 775 if (h->order >= MAX_ORDER) 776 return NULL; 777 778 /* 779 * Assume we will successfully allocate the surplus page to 780 * prevent racing processes from causing the surplus to exceed 781 * overcommit 782 * 783 * This however introduces a different race, where a process B 784 * tries to grow the static hugepage pool while alloc_pages() is 785 * called by process A. B will only examine the per-node 786 * counters in determining if surplus huge pages can be 787 * converted to normal huge pages in adjust_pool_surplus(). A 788 * won't be able to increment the per-node counter, until the 789 * lock is dropped by B, but B doesn't drop hugetlb_lock until 790 * no more huge pages can be converted from surplus to normal 791 * state (and doesn't try to convert again). Thus, we have a 792 * case where a surplus huge page exists, the pool is grown, and 793 * the surplus huge page still exists after, even though it 794 * should just have been converted to a normal huge page. This 795 * does not leak memory, though, as the hugepage will be freed 796 * once it is out of use. It also does not allow the counters to 797 * go out of whack in adjust_pool_surplus() as we don't modify 798 * the node values until we've gotten the hugepage and only the 799 * per-node value is checked there. 800 */ 801 spin_lock(&hugetlb_lock); 802 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { 803 spin_unlock(&hugetlb_lock); 804 return NULL; 805 } else { 806 h->nr_huge_pages++; 807 h->surplus_huge_pages++; 808 } 809 spin_unlock(&hugetlb_lock); 810 811 page = alloc_pages(htlb_alloc_mask|__GFP_COMP| 812 __GFP_REPEAT|__GFP_NOWARN, 813 huge_page_order(h)); 814 815 if (page && arch_prepare_hugepage(page)) { 816 __free_pages(page, huge_page_order(h)); 817 return NULL; 818 } 819 820 spin_lock(&hugetlb_lock); 821 if (page) { 822 /* 823 * This page is now managed by the hugetlb allocator and has 824 * no users -- drop the buddy allocator's reference. 825 */ 826 put_page_testzero(page); 827 VM_BUG_ON(page_count(page)); 828 nid = page_to_nid(page); 829 set_compound_page_dtor(page, free_huge_page); 830 /* 831 * We incremented the global counters already 832 */ 833 h->nr_huge_pages_node[nid]++; 834 h->surplus_huge_pages_node[nid]++; 835 __count_vm_event(HTLB_BUDDY_PGALLOC); 836 } else { 837 h->nr_huge_pages--; 838 h->surplus_huge_pages--; 839 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 840 } 841 spin_unlock(&hugetlb_lock); 842 843 return page; 844} 845 846/* 847 * Increase the hugetlb pool such that it can accomodate a reservation 848 * of size 'delta'. 849 */ 850static int gather_surplus_pages(struct hstate *h, int delta) 851{ 852 struct list_head surplus_list; 853 struct page *page, *tmp; 854 int ret, i; 855 int needed, allocated; 856 857 needed = (h->resv_huge_pages + delta) - h->free_huge_pages; 858 if (needed <= 0) { 859 h->resv_huge_pages += delta; 860 return 0; 861 } 862 863 allocated = 0; 864 INIT_LIST_HEAD(&surplus_list); 865 866 ret = -ENOMEM; 867retry: 868 spin_unlock(&hugetlb_lock); 869 for (i = 0; i < needed; i++) { 870 page = alloc_buddy_huge_page(h, NULL, 0); 871 if (!page) { 872 /* 873 * We were not able to allocate enough pages to 874 * satisfy the entire reservation so we free what 875 * we've allocated so far. 876 */ 877 spin_lock(&hugetlb_lock); 878 needed = 0; 879 goto free; 880 } 881 882 list_add(&page->lru, &surplus_list); 883 } 884 allocated += needed; 885 886 /* 887 * After retaking hugetlb_lock, we need to recalculate 'needed' 888 * because either resv_huge_pages or free_huge_pages may have changed. 889 */ 890 spin_lock(&hugetlb_lock); 891 needed = (h->resv_huge_pages + delta) - 892 (h->free_huge_pages + allocated); 893 if (needed > 0) 894 goto retry; 895 896 /* 897 * The surplus_list now contains _at_least_ the number of extra pages 898 * needed to accomodate the reservation. Add the appropriate number 899 * of pages to the hugetlb pool and free the extras back to the buddy 900 * allocator. Commit the entire reservation here to prevent another 901 * process from stealing the pages as they are added to the pool but 902 * before they are reserved. 903 */ 904 needed += allocated; 905 h->resv_huge_pages += delta; 906 ret = 0; 907free: 908 /* Free the needed pages to the hugetlb pool */ 909 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 910 if ((--needed) < 0) 911 break; 912 list_del(&page->lru); 913 enqueue_huge_page(h, page); 914 } 915 916 /* Free unnecessary surplus pages to the buddy allocator */ 917 if (!list_empty(&surplus_list)) { 918 spin_unlock(&hugetlb_lock); 919 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 920 list_del(&page->lru); 921 /* 922 * The page has a reference count of zero already, so 923 * call free_huge_page directly instead of using 924 * put_page. This must be done with hugetlb_lock 925 * unlocked which is safe because free_huge_page takes 926 * hugetlb_lock before deciding how to free the page. 927 */ 928 free_huge_page(page); 929 } 930 spin_lock(&hugetlb_lock); 931 } 932 933 return ret; 934} 935 936/* 937 * When releasing a hugetlb pool reservation, any surplus pages that were 938 * allocated to satisfy the reservation must be explicitly freed if they were 939 * never used. 940 * Called with hugetlb_lock held. 941 */ 942static void return_unused_surplus_pages(struct hstate *h, 943 unsigned long unused_resv_pages) 944{ 945 unsigned long nr_pages; 946 947 /* Uncommit the reservation */ 948 h->resv_huge_pages -= unused_resv_pages; 949 950 /* Cannot return gigantic pages currently */ 951 if (h->order >= MAX_ORDER) 952 return; 953 954 nr_pages = min(unused_resv_pages, h->surplus_huge_pages); 955 956 /* 957 * We want to release as many surplus pages as possible, spread 958 * evenly across all nodes with memory. Iterate across these nodes 959 * until we can no longer free unreserved surplus pages. This occurs 960 * when the nodes with surplus pages have no free pages. 961 * free_pool_huge_page() will balance the the freed pages across the 962 * on-line nodes with memory and will handle the hstate accounting. 963 */ 964 while (nr_pages--) { 965 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1)) 966 break; 967 } 968} 969 970/* 971 * Determine if the huge page at addr within the vma has an associated 972 * reservation. Where it does not we will need to logically increase 973 * reservation and actually increase quota before an allocation can occur. 974 * Where any new reservation would be required the reservation change is 975 * prepared, but not committed. Once the page has been quota'd allocated 976 * an instantiated the change should be committed via vma_commit_reservation. 977 * No action is required on failure. 978 */ 979static long vma_needs_reservation(struct hstate *h, 980 struct vm_area_struct *vma, unsigned long addr) 981{ 982 struct address_space *mapping = vma->vm_file->f_mapping; 983 struct inode *inode = mapping->host; 984 985 if (vma->vm_flags & VM_MAYSHARE) { 986 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 987 return region_chg(&inode->i_mapping->private_list, 988 idx, idx + 1); 989 990 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 991 return 1; 992 993 } else { 994 long err; 995 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 996 struct resv_map *reservations = vma_resv_map(vma); 997 998 err = region_chg(&reservations->regions, idx, idx + 1); 999 if (err < 0) 1000 return err; 1001 return 0; 1002 } 1003} 1004static void vma_commit_reservation(struct hstate *h, 1005 struct vm_area_struct *vma, unsigned long addr) 1006{ 1007 struct address_space *mapping = vma->vm_file->f_mapping; 1008 struct inode *inode = mapping->host; 1009 1010 if (vma->vm_flags & VM_MAYSHARE) { 1011 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1012 region_add(&inode->i_mapping->private_list, idx, idx + 1); 1013 1014 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 1015 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1016 struct resv_map *reservations = vma_resv_map(vma); 1017 1018 /* Mark this page used in the map. */ 1019 region_add(&reservations->regions, idx, idx + 1); 1020 } 1021} 1022 1023static struct page *alloc_huge_page(struct vm_area_struct *vma, 1024 unsigned long addr, int avoid_reserve) 1025{ 1026 struct hstate *h = hstate_vma(vma); 1027 struct page *page; 1028 struct address_space *mapping = vma->vm_file->f_mapping; 1029 struct inode *inode = mapping->host; 1030 long chg; 1031 1032 /* 1033 * Processes that did not create the mapping will have no reserves and 1034 * will not have accounted against quota. Check that the quota can be 1035 * made before satisfying the allocation 1036 * MAP_NORESERVE mappings may also need pages and quota allocated 1037 * if no reserve mapping overlaps. 1038 */ 1039 chg = vma_needs_reservation(h, vma, addr); 1040 if (chg < 0) 1041 return ERR_PTR(chg); 1042 if (chg) 1043 if (hugetlb_get_quota(inode->i_mapping, chg)) 1044 return ERR_PTR(-ENOSPC); 1045 1046 spin_lock(&hugetlb_lock); 1047 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); 1048 spin_unlock(&hugetlb_lock); 1049 1050 if (!page) { 1051 page = alloc_buddy_huge_page(h, vma, addr); 1052 if (!page) { 1053 hugetlb_put_quota(inode->i_mapping, chg); 1054 return ERR_PTR(-VM_FAULT_SIGBUS); 1055 } 1056 } 1057 1058 set_page_refcounted(page); 1059 set_page_private(page, (unsigned long) mapping); 1060 1061 vma_commit_reservation(h, vma, addr); 1062 1063 return page; 1064} 1065 1066int __weak alloc_bootmem_huge_page(struct hstate *h) 1067{ 1068 struct huge_bootmem_page *m; 1069 int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]); 1070 1071 while (nr_nodes) { 1072 void *addr; 1073 1074 addr = __alloc_bootmem_node_nopanic( 1075 NODE_DATA(hstate_next_node_to_alloc(h, 1076 &node_states[N_HIGH_MEMORY])), 1077 huge_page_size(h), huge_page_size(h), 0); 1078 1079 if (addr) { 1080 /* 1081 * Use the beginning of the huge page to store the 1082 * huge_bootmem_page struct (until gather_bootmem 1083 * puts them into the mem_map). 1084 */ 1085 m = addr; 1086 goto found; 1087 } 1088 nr_nodes--; 1089 } 1090 return 0; 1091 1092found: 1093 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); 1094 /* Put them into a private list first because mem_map is not up yet */ 1095 list_add(&m->list, &huge_boot_pages); 1096 m->hstate = h; 1097 return 1; 1098} 1099 1100static void prep_compound_huge_page(struct page *page, int order) 1101{ 1102 if (unlikely(order > (MAX_ORDER - 1))) 1103 prep_compound_gigantic_page(page, order); 1104 else 1105 prep_compound_page(page, order); 1106} 1107 1108/* Put bootmem huge pages into the standard lists after mem_map is up */ 1109static void __init gather_bootmem_prealloc(void) 1110{ 1111 struct huge_bootmem_page *m; 1112 1113 list_for_each_entry(m, &huge_boot_pages, list) { 1114 struct page *page = virt_to_page(m); 1115 struct hstate *h = m->hstate; 1116 __ClearPageReserved(page); 1117 WARN_ON(page_count(page) != 1); 1118 prep_compound_huge_page(page, h->order); 1119 prep_new_huge_page(h, page, page_to_nid(page)); 1120 } 1121} 1122 1123static void __init hugetlb_hstate_alloc_pages(struct hstate *h) 1124{ 1125 unsigned long i; 1126 1127 for (i = 0; i < h->max_huge_pages; ++i) { 1128 if (h->order >= MAX_ORDER) { 1129 if (!alloc_bootmem_huge_page(h)) 1130 break; 1131 } else if (!alloc_fresh_huge_page(h, 1132 &node_states[N_HIGH_MEMORY])) 1133 break; 1134 } 1135 h->max_huge_pages = i; 1136} 1137 1138static void __init hugetlb_init_hstates(void) 1139{ 1140 struct hstate *h; 1141 1142 for_each_hstate(h) { 1143 /* oversize hugepages were init'ed in early boot */ 1144 if (h->order < MAX_ORDER) 1145 hugetlb_hstate_alloc_pages(h); 1146 } 1147} 1148 1149static char * __init memfmt(char *buf, unsigned long n) 1150{ 1151 if (n >= (1UL << 30)) 1152 sprintf(buf, "%lu GB", n >> 30); 1153 else if (n >= (1UL << 20)) 1154 sprintf(buf, "%lu MB", n >> 20); 1155 else 1156 sprintf(buf, "%lu KB", n >> 10); 1157 return buf; 1158} 1159 1160static void __init report_hugepages(void) 1161{ 1162 struct hstate *h; 1163 1164 for_each_hstate(h) { 1165 char buf[32]; 1166 printk(KERN_INFO "HugeTLB registered %s page size, " 1167 "pre-allocated %ld pages\n", 1168 memfmt(buf, huge_page_size(h)), 1169 h->free_huge_pages); 1170 } 1171} 1172 1173#ifdef CONFIG_HIGHMEM 1174static void try_to_free_low(struct hstate *h, unsigned long count, 1175 nodemask_t *nodes_allowed) 1176{ 1177 int i; 1178 1179 if (h->order >= MAX_ORDER) 1180 return; 1181 1182 for_each_node_mask(i, *nodes_allowed) { 1183 struct page *page, *next; 1184 struct list_head *freel = &h->hugepage_freelists[i]; 1185 list_for_each_entry_safe(page, next, freel, lru) { 1186 if (count >= h->nr_huge_pages) 1187 return; 1188 if (PageHighMem(page)) 1189 continue; 1190 list_del(&page->lru); 1191 update_and_free_page(h, page); 1192 h->free_huge_pages--; 1193 h->free_huge_pages_node[page_to_nid(page)]--; 1194 } 1195 } 1196} 1197#else 1198static inline void try_to_free_low(struct hstate *h, unsigned long count, 1199 nodemask_t *nodes_allowed) 1200{ 1201} 1202#endif 1203 1204/* 1205 * Increment or decrement surplus_huge_pages. Keep node-specific counters 1206 * balanced by operating on them in a round-robin fashion. 1207 * Returns 1 if an adjustment was made. 1208 */ 1209static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, 1210 int delta) 1211{ 1212 int start_nid, next_nid; 1213 int ret = 0; 1214 1215 VM_BUG_ON(delta != -1 && delta != 1); 1216 1217 if (delta < 0) 1218 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 1219 else 1220 start_nid = hstate_next_node_to_free(h, nodes_allowed); 1221 next_nid = start_nid; 1222 1223 do { 1224 int nid = next_nid; 1225 if (delta < 0) { 1226 /* 1227 * To shrink on this node, there must be a surplus page 1228 */ 1229 if (!h->surplus_huge_pages_node[nid]) { 1230 next_nid = hstate_next_node_to_alloc(h, 1231 nodes_allowed); 1232 continue; 1233 } 1234 } 1235 if (delta > 0) { 1236 /* 1237 * Surplus cannot exceed the total number of pages 1238 */ 1239 if (h->surplus_huge_pages_node[nid] >= 1240 h->nr_huge_pages_node[nid]) { 1241 next_nid = hstate_next_node_to_free(h, 1242 nodes_allowed); 1243 continue; 1244 } 1245 } 1246 1247 h->surplus_huge_pages += delta; 1248 h->surplus_huge_pages_node[nid] += delta; 1249 ret = 1; 1250 break; 1251 } while (next_nid != start_nid); 1252 1253 return ret; 1254} 1255 1256#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) 1257static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, 1258 nodemask_t *nodes_allowed) 1259{ 1260 unsigned long min_count, ret; 1261 1262 if (h->order >= MAX_ORDER) 1263 return h->max_huge_pages; 1264 1265 /* 1266 * Increase the pool size 1267 * First take pages out of surplus state. Then make up the 1268 * remaining difference by allocating fresh huge pages. 1269 * 1270 * We might race with alloc_buddy_huge_page() here and be unable 1271 * to convert a surplus huge page to a normal huge page. That is 1272 * not critical, though, it just means the overall size of the 1273 * pool might be one hugepage larger than it needs to be, but 1274 * within all the constraints specified by the sysctls. 1275 */ 1276 spin_lock(&hugetlb_lock); 1277 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { 1278 if (!adjust_pool_surplus(h, nodes_allowed, -1)) 1279 break; 1280 } 1281 1282 while (count > persistent_huge_pages(h)) { 1283 /* 1284 * If this allocation races such that we no longer need the 1285 * page, free_huge_page will handle it by freeing the page 1286 * and reducing the surplus. 1287 */ 1288 spin_unlock(&hugetlb_lock); 1289 ret = alloc_fresh_huge_page(h, nodes_allowed); 1290 spin_lock(&hugetlb_lock); 1291 if (!ret) 1292 goto out; 1293 1294 /* Bail for signals. Probably ctrl-c from user */ 1295 if (signal_pending(current)) 1296 goto out; 1297 } 1298 1299 /* 1300 * Decrease the pool size 1301 * First return free pages to the buddy allocator (being careful 1302 * to keep enough around to satisfy reservations). Then place 1303 * pages into surplus state as needed so the pool will shrink 1304 * to the desired size as pages become free. 1305 * 1306 * By placing pages into the surplus state independent of the 1307 * overcommit value, we are allowing the surplus pool size to 1308 * exceed overcommit. There are few sane options here. Since 1309 * alloc_buddy_huge_page() is checking the global counter, 1310 * though, we'll note that we're not allowed to exceed surplus 1311 * and won't grow the pool anywhere else. Not until one of the 1312 * sysctls are changed, or the surplus pages go out of use. 1313 */ 1314 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; 1315 min_count = max(count, min_count); 1316 try_to_free_low(h, min_count, nodes_allowed); 1317 while (min_count < persistent_huge_pages(h)) { 1318 if (!free_pool_huge_page(h, nodes_allowed, 0)) 1319 break; 1320 } 1321 while (count < persistent_huge_pages(h)) { 1322 if (!adjust_pool_surplus(h, nodes_allowed, 1)) 1323 break; 1324 } 1325out: 1326 ret = persistent_huge_pages(h); 1327 spin_unlock(&hugetlb_lock); 1328 return ret; 1329} 1330 1331#define HSTATE_ATTR_RO(_name) \ 1332 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 1333 1334#define HSTATE_ATTR(_name) \ 1335 static struct kobj_attribute _name##_attr = \ 1336 __ATTR(_name, 0644, _name##_show, _name##_store) 1337 1338static struct kobject *hugepages_kobj; 1339static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1340 1341static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); 1342 1343static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) 1344{ 1345 int i; 1346 1347 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1348 if (hstate_kobjs[i] == kobj) { 1349 if (nidp) 1350 *nidp = NUMA_NO_NODE; 1351 return &hstates[i]; 1352 } 1353 1354 return kobj_to_node_hstate(kobj, nidp); 1355} 1356 1357static ssize_t nr_hugepages_show_common(struct kobject *kobj, 1358 struct kobj_attribute *attr, char *buf) 1359{ 1360 struct hstate *h; 1361 unsigned long nr_huge_pages; 1362 int nid; 1363 1364 h = kobj_to_hstate(kobj, &nid); 1365 if (nid == NUMA_NO_NODE) 1366 nr_huge_pages = h->nr_huge_pages; 1367 else 1368 nr_huge_pages = h->nr_huge_pages_node[nid]; 1369 1370 return sprintf(buf, "%lu\n", nr_huge_pages); 1371} 1372static ssize_t nr_hugepages_store_common(bool obey_mempolicy, 1373 struct kobject *kobj, struct kobj_attribute *attr, 1374 const char *buf, size_t len) 1375{ 1376 int err; 1377 int nid; 1378 unsigned long count; 1379 struct hstate *h; 1380 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); 1381 1382 err = strict_strtoul(buf, 10, &count); 1383 if (err) 1384 return 0; 1385 1386 h = kobj_to_hstate(kobj, &nid); 1387 if (nid == NUMA_NO_NODE) { 1388 /* 1389 * global hstate attribute 1390 */ 1391 if (!(obey_mempolicy && 1392 init_nodemask_of_mempolicy(nodes_allowed))) { 1393 NODEMASK_FREE(nodes_allowed); 1394 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1395 } 1396 } else if (nodes_allowed) { 1397 /* 1398 * per node hstate attribute: adjust count to global, 1399 * but restrict alloc/free to the specified node. 1400 */ 1401 count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; 1402 init_nodemask_of_node(nodes_allowed, nid); 1403 } else 1404 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1405 1406 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); 1407 1408 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1409 NODEMASK_FREE(nodes_allowed); 1410 1411 return len; 1412} 1413 1414static ssize_t nr_hugepages_show(struct kobject *kobj, 1415 struct kobj_attribute *attr, char *buf) 1416{ 1417 return nr_hugepages_show_common(kobj, attr, buf); 1418} 1419 1420static ssize_t nr_hugepages_store(struct kobject *kobj, 1421 struct kobj_attribute *attr, const char *buf, size_t len) 1422{ 1423 return nr_hugepages_store_common(false, kobj, attr, buf, len); 1424} 1425HSTATE_ATTR(nr_hugepages); 1426 1427#ifdef CONFIG_NUMA 1428 1429/* 1430 * hstate attribute for optionally mempolicy-based constraint on persistent 1431 * huge page alloc/free. 1432 */ 1433static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, 1434 struct kobj_attribute *attr, char *buf) 1435{ 1436 return nr_hugepages_show_common(kobj, attr, buf); 1437} 1438 1439static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, 1440 struct kobj_attribute *attr, const char *buf, size_t len) 1441{ 1442 return nr_hugepages_store_common(true, kobj, attr, buf, len); 1443} 1444HSTATE_ATTR(nr_hugepages_mempolicy); 1445#endif 1446 1447 1448static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, 1449 struct kobj_attribute *attr, char *buf) 1450{ 1451 struct hstate *h = kobj_to_hstate(kobj, NULL); 1452 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); 1453} 1454static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, 1455 struct kobj_attribute *attr, const char *buf, size_t count) 1456{ 1457 int err; 1458 unsigned long input; 1459 struct hstate *h = kobj_to_hstate(kobj, NULL); 1460 1461 err = strict_strtoul(buf, 10, &input); 1462 if (err) 1463 return 0; 1464 1465 spin_lock(&hugetlb_lock); 1466 h->nr_overcommit_huge_pages = input; 1467 spin_unlock(&hugetlb_lock); 1468 1469 return count; 1470} 1471HSTATE_ATTR(nr_overcommit_hugepages); 1472 1473static ssize_t free_hugepages_show(struct kobject *kobj, 1474 struct kobj_attribute *attr, char *buf) 1475{ 1476 struct hstate *h; 1477 unsigned long free_huge_pages; 1478 int nid; 1479 1480 h = kobj_to_hstate(kobj, &nid); 1481 if (nid == NUMA_NO_NODE) 1482 free_huge_pages = h->free_huge_pages; 1483 else 1484 free_huge_pages = h->free_huge_pages_node[nid]; 1485 1486 return sprintf(buf, "%lu\n", free_huge_pages); 1487} 1488HSTATE_ATTR_RO(free_hugepages); 1489 1490static ssize_t resv_hugepages_show(struct kobject *kobj, 1491 struct kobj_attribute *attr, char *buf) 1492{ 1493 struct hstate *h = kobj_to_hstate(kobj, NULL); 1494 return sprintf(buf, "%lu\n", h->resv_huge_pages); 1495} 1496HSTATE_ATTR_RO(resv_hugepages); 1497 1498static ssize_t surplus_hugepages_show(struct kobject *kobj, 1499 struct kobj_attribute *attr, char *buf) 1500{ 1501 struct hstate *h; 1502 unsigned long surplus_huge_pages; 1503 int nid; 1504 1505 h = kobj_to_hstate(kobj, &nid); 1506 if (nid == NUMA_NO_NODE) 1507 surplus_huge_pages = h->surplus_huge_pages; 1508 else 1509 surplus_huge_pages = h->surplus_huge_pages_node[nid]; 1510 1511 return sprintf(buf, "%lu\n", surplus_huge_pages); 1512} 1513HSTATE_ATTR_RO(surplus_hugepages); 1514 1515static struct attribute *hstate_attrs[] = { 1516 &nr_hugepages_attr.attr, 1517 &nr_overcommit_hugepages_attr.attr, 1518 &free_hugepages_attr.attr, 1519 &resv_hugepages_attr.attr, 1520 &surplus_hugepages_attr.attr, 1521#ifdef CONFIG_NUMA 1522 &nr_hugepages_mempolicy_attr.attr, 1523#endif 1524 NULL, 1525}; 1526 1527static struct attribute_group hstate_attr_group = { 1528 .attrs = hstate_attrs, 1529}; 1530 1531static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, 1532 struct kobject **hstate_kobjs, 1533 struct attribute_group *hstate_attr_group) 1534{ 1535 int retval; 1536 int hi = h - hstates; 1537 1538 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); 1539 if (!hstate_kobjs[hi]) 1540 return -ENOMEM; 1541 1542 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); 1543 if (retval) 1544 kobject_put(hstate_kobjs[hi]); 1545 1546 return retval; 1547} 1548 1549static void __init hugetlb_sysfs_init(void) 1550{ 1551 struct hstate *h; 1552 int err; 1553 1554 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); 1555 if (!hugepages_kobj) 1556 return; 1557 1558 for_each_hstate(h) { 1559 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, 1560 hstate_kobjs, &hstate_attr_group); 1561 if (err) 1562 printk(KERN_ERR "Hugetlb: Unable to add hstate %s", 1563 h->name); 1564 } 1565} 1566 1567#ifdef CONFIG_NUMA 1568 1569/* 1570 * node_hstate/s - associate per node hstate attributes, via their kobjects, 1571 * with node sysdevs in node_devices[] using a parallel array. The array 1572 * index of a node sysdev or _hstate == node id. 1573 * This is here to avoid any static dependency of the node sysdev driver, in 1574 * the base kernel, on the hugetlb module. 1575 */ 1576struct node_hstate { 1577 struct kobject *hugepages_kobj; 1578 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1579}; 1580struct node_hstate node_hstates[MAX_NUMNODES]; 1581 1582/* 1583 * A subset of global hstate attributes for node sysdevs 1584 */ 1585static struct attribute *per_node_hstate_attrs[] = { 1586 &nr_hugepages_attr.attr, 1587 &free_hugepages_attr.attr, 1588 &surplus_hugepages_attr.attr, 1589 NULL, 1590}; 1591 1592static struct attribute_group per_node_hstate_attr_group = { 1593 .attrs = per_node_hstate_attrs, 1594}; 1595 1596/* 1597 * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj. 1598 * Returns node id via non-NULL nidp. 1599 */ 1600static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1601{ 1602 int nid; 1603 1604 for (nid = 0; nid < nr_node_ids; nid++) { 1605 struct node_hstate *nhs = &node_hstates[nid]; 1606 int i; 1607 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1608 if (nhs->hstate_kobjs[i] == kobj) { 1609 if (nidp) 1610 *nidp = nid; 1611 return &hstates[i]; 1612 } 1613 } 1614 1615 BUG(); 1616 return NULL; 1617} 1618 1619/* 1620 * Unregister hstate attributes from a single node sysdev. 1621 * No-op if no hstate attributes attached. 1622 */ 1623void hugetlb_unregister_node(struct node *node) 1624{ 1625 struct hstate *h; 1626 struct node_hstate *nhs = &node_hstates[node->sysdev.id]; 1627 1628 if (!nhs->hugepages_kobj) 1629 return; /* no hstate attributes */ 1630 1631 for_each_hstate(h) 1632 if (nhs->hstate_kobjs[h - hstates]) { 1633 kobject_put(nhs->hstate_kobjs[h - hstates]); 1634 nhs->hstate_kobjs[h - hstates] = NULL; 1635 } 1636 1637 kobject_put(nhs->hugepages_kobj); 1638 nhs->hugepages_kobj = NULL; 1639} 1640 1641/* 1642 * hugetlb module exit: unregister hstate attributes from node sysdevs 1643 * that have them. 1644 */ 1645static void hugetlb_unregister_all_nodes(void) 1646{ 1647 int nid; 1648 1649 /* 1650 * disable node sysdev registrations. 1651 */ 1652 register_hugetlbfs_with_node(NULL, NULL); 1653 1654 /* 1655 * remove hstate attributes from any nodes that have them. 1656 */ 1657 for (nid = 0; nid < nr_node_ids; nid++) 1658 hugetlb_unregister_node(&node_devices[nid]); 1659} 1660 1661/* 1662 * Register hstate attributes for a single node sysdev. 1663 * No-op if attributes already registered. 1664 */ 1665void hugetlb_register_node(struct node *node) 1666{ 1667 struct hstate *h; 1668 struct node_hstate *nhs = &node_hstates[node->sysdev.id]; 1669 int err; 1670 1671 if (nhs->hugepages_kobj) 1672 return; /* already allocated */ 1673 1674 nhs->hugepages_kobj = kobject_create_and_add("hugepages", 1675 &node->sysdev.kobj); 1676 if (!nhs->hugepages_kobj) 1677 return; 1678 1679 for_each_hstate(h) { 1680 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, 1681 nhs->hstate_kobjs, 1682 &per_node_hstate_attr_group); 1683 if (err) { 1684 printk(KERN_ERR "Hugetlb: Unable to add hstate %s" 1685 " for node %d\n", 1686 h->name, node->sysdev.id); 1687 hugetlb_unregister_node(node); 1688 break; 1689 } 1690 } 1691} 1692 1693/* 1694 * hugetlb init time: register hstate attributes for all registered node 1695 * sysdevs of nodes that have memory. All on-line nodes should have 1696 * registered their associated sysdev by this time. 1697 */ 1698static void hugetlb_register_all_nodes(void) 1699{ 1700 int nid; 1701 1702 for_each_node_state(nid, N_HIGH_MEMORY) { 1703 struct node *node = &node_devices[nid]; 1704 if (node->sysdev.id == nid) 1705 hugetlb_register_node(node); 1706 } 1707 1708 /* 1709 * Let the node sysdev driver know we're here so it can 1710 * [un]register hstate attributes on node hotplug. 1711 */ 1712 register_hugetlbfs_with_node(hugetlb_register_node, 1713 hugetlb_unregister_node); 1714} 1715#else /* !CONFIG_NUMA */ 1716 1717static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1718{ 1719 BUG(); 1720 if (nidp) 1721 *nidp = -1; 1722 return NULL; 1723} 1724 1725static void hugetlb_unregister_all_nodes(void) { } 1726 1727static void hugetlb_register_all_nodes(void) { } 1728 1729#endif 1730 1731static void __exit hugetlb_exit(void) 1732{ 1733 struct hstate *h; 1734 1735 hugetlb_unregister_all_nodes(); 1736 1737 for_each_hstate(h) { 1738 kobject_put(hstate_kobjs[h - hstates]); 1739 } 1740 1741 kobject_put(hugepages_kobj); 1742} 1743module_exit(hugetlb_exit); 1744 1745static int __init hugetlb_init(void) 1746{ 1747 /* Some platform decide whether they support huge pages at boot 1748 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when 1749 * there is no such support 1750 */ 1751 if (HPAGE_SHIFT == 0) 1752 return 0; 1753 1754 if (!size_to_hstate(default_hstate_size)) { 1755 default_hstate_size = HPAGE_SIZE; 1756 if (!size_to_hstate(default_hstate_size)) 1757 hugetlb_add_hstate(HUGETLB_PAGE_ORDER); 1758 } 1759 default_hstate_idx = size_to_hstate(default_hstate_size) - hstates; 1760 if (default_hstate_max_huge_pages) 1761 default_hstate.max_huge_pages = default_hstate_max_huge_pages; 1762 1763 hugetlb_init_hstates(); 1764 1765 gather_bootmem_prealloc(); 1766 1767 report_hugepages(); 1768 1769 hugetlb_sysfs_init(); 1770 1771 hugetlb_register_all_nodes(); 1772 1773 return 0; 1774} 1775module_init(hugetlb_init); 1776 1777/* Should be called on processing a hugepagesz=... option */ 1778void __init hugetlb_add_hstate(unsigned order) 1779{ 1780 struct hstate *h; 1781 unsigned long i; 1782 1783 if (size_to_hstate(PAGE_SIZE << order)) { 1784 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n"); 1785 return; 1786 } 1787 BUG_ON(max_hstate >= HUGE_MAX_HSTATE); 1788 BUG_ON(order == 0); 1789 h = &hstates[max_hstate++]; 1790 h->order = order; 1791 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); 1792 h->nr_huge_pages = 0; 1793 h->free_huge_pages = 0; 1794 for (i = 0; i < MAX_NUMNODES; ++i) 1795 INIT_LIST_HEAD(&h->hugepage_freelists[i]); 1796 h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]); 1797 h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]); 1798 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", 1799 huge_page_size(h)/1024); 1800 1801 parsed_hstate = h; 1802} 1803 1804static int __init hugetlb_nrpages_setup(char *s) 1805{ 1806 unsigned long *mhp; 1807 static unsigned long *last_mhp; 1808 1809 /* 1810 * !max_hstate means we haven't parsed a hugepagesz= parameter yet, 1811 * so this hugepages= parameter goes to the "default hstate". 1812 */ 1813 if (!max_hstate) 1814 mhp = &default_hstate_max_huge_pages; 1815 else 1816 mhp = &parsed_hstate->max_huge_pages; 1817 1818 if (mhp == last_mhp) { 1819 printk(KERN_WARNING "hugepages= specified twice without " 1820 "interleaving hugepagesz=, ignoring\n"); 1821 return 1; 1822 } 1823 1824 if (sscanf(s, "%lu", mhp) <= 0) 1825 *mhp = 0; 1826 1827 /* 1828 * Global state is always initialized later in hugetlb_init. 1829 * But we need to allocate >= MAX_ORDER hstates here early to still 1830 * use the bootmem allocator. 1831 */ 1832 if (max_hstate && parsed_hstate->order >= MAX_ORDER) 1833 hugetlb_hstate_alloc_pages(parsed_hstate); 1834 1835 last_mhp = mhp; 1836 1837 return 1; 1838} 1839__setup("hugepages=", hugetlb_nrpages_setup); 1840 1841static int __init hugetlb_default_setup(char *s) 1842{ 1843 default_hstate_size = memparse(s, &s); 1844 return 1; 1845} 1846__setup("default_hugepagesz=", hugetlb_default_setup); 1847 1848static unsigned int cpuset_mems_nr(unsigned int *array) 1849{ 1850 int node; 1851 unsigned int nr = 0; 1852 1853 for_each_node_mask(node, cpuset_current_mems_allowed) 1854 nr += array[node]; 1855 1856 return nr; 1857} 1858 1859#ifdef CONFIG_SYSCTL 1860static int hugetlb_sysctl_handler_common(bool obey_mempolicy, 1861 struct ctl_table *table, int write, 1862 void __user *buffer, size_t *length, loff_t *ppos) 1863{ 1864 struct hstate *h = &default_hstate; 1865 unsigned long tmp; 1866 1867 if (!write) 1868 tmp = h->max_huge_pages; 1869 1870 table->data = &tmp; 1871 table->maxlen = sizeof(unsigned long); 1872 proc_doulongvec_minmax(table, write, buffer, length, ppos); 1873 1874 if (write) { 1875 NODEMASK_ALLOC(nodemask_t, nodes_allowed, 1876 GFP_KERNEL | __GFP_NORETRY); 1877 if (!(obey_mempolicy && 1878 init_nodemask_of_mempolicy(nodes_allowed))) { 1879 NODEMASK_FREE(nodes_allowed); 1880 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1881 } 1882 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); 1883 1884 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1885 NODEMASK_FREE(nodes_allowed); 1886 } 1887 1888 return 0; 1889} 1890 1891int hugetlb_sysctl_handler(struct ctl_table *table, int write, 1892 void __user *buffer, size_t *length, loff_t *ppos) 1893{ 1894 1895 return hugetlb_sysctl_handler_common(false, table, write, 1896 buffer, length, ppos); 1897} 1898 1899#ifdef CONFIG_NUMA 1900int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, 1901 void __user *buffer, size_t *length, loff_t *ppos) 1902{ 1903 return hugetlb_sysctl_handler_common(true, table, write, 1904 buffer, length, ppos); 1905} 1906#endif /* CONFIG_NUMA */ 1907 1908int hugetlb_treat_movable_handler(struct ctl_table *table, int write, 1909 void __user *buffer, 1910 size_t *length, loff_t *ppos) 1911{ 1912 proc_dointvec(table, write, buffer, length, ppos); 1913 if (hugepages_treat_as_movable) 1914 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; 1915 else 1916 htlb_alloc_mask = GFP_HIGHUSER; 1917 return 0; 1918} 1919 1920int hugetlb_overcommit_handler(struct ctl_table *table, int write, 1921 void __user *buffer, 1922 size_t *length, loff_t *ppos) 1923{ 1924 struct hstate *h = &default_hstate; 1925 unsigned long tmp; 1926 1927 if (!write) 1928 tmp = h->nr_overcommit_huge_pages; 1929 1930 table->data = &tmp; 1931 table->maxlen = sizeof(unsigned long); 1932 proc_doulongvec_minmax(table, write, buffer, length, ppos); 1933 1934 if (write) { 1935 spin_lock(&hugetlb_lock); 1936 h->nr_overcommit_huge_pages = tmp; 1937 spin_unlock(&hugetlb_lock); 1938 } 1939 1940 return 0; 1941} 1942 1943#endif /* CONFIG_SYSCTL */ 1944 1945void hugetlb_report_meminfo(struct seq_file *m) 1946{ 1947 struct hstate *h = &default_hstate; 1948 seq_printf(m, 1949 "HugePages_Total: %5lu\n" 1950 "HugePages_Free: %5lu\n" 1951 "HugePages_Rsvd: %5lu\n" 1952 "HugePages_Surp: %5lu\n" 1953 "Hugepagesize: %8lu kB\n", 1954 h->nr_huge_pages, 1955 h->free_huge_pages, 1956 h->resv_huge_pages, 1957 h->surplus_huge_pages, 1958 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 1959} 1960 1961int hugetlb_report_node_meminfo(int nid, char *buf) 1962{ 1963 struct hstate *h = &default_hstate; 1964 return sprintf(buf, 1965 "Node %d HugePages_Total: %5u\n" 1966 "Node %d HugePages_Free: %5u\n" 1967 "Node %d HugePages_Surp: %5u\n", 1968 nid, h->nr_huge_pages_node[nid], 1969 nid, h->free_huge_pages_node[nid], 1970 nid, h->surplus_huge_pages_node[nid]); 1971} 1972 1973/* Return the number pages of memory we physically have, in PAGE_SIZE units. */ 1974unsigned long hugetlb_total_pages(void) 1975{ 1976 struct hstate *h = &default_hstate; 1977 return h->nr_huge_pages * pages_per_huge_page(h); 1978} 1979 1980static int hugetlb_acct_memory(struct hstate *h, long delta) 1981{ 1982 int ret = -ENOMEM; 1983 1984 spin_lock(&hugetlb_lock); 1985 /* 1986 * When cpuset is configured, it breaks the strict hugetlb page 1987 * reservation as the accounting is done on a global variable. Such 1988 * reservation is completely rubbish in the presence of cpuset because 1989 * the reservation is not checked against page availability for the 1990 * current cpuset. Application can still potentially OOM'ed by kernel 1991 * with lack of free htlb page in cpuset that the task is in. 1992 * Attempt to enforce strict accounting with cpuset is almost 1993 * impossible (or too ugly) because cpuset is too fluid that 1994 * task or memory node can be dynamically moved between cpusets. 1995 * 1996 * The change of semantics for shared hugetlb mapping with cpuset is 1997 * undesirable. However, in order to preserve some of the semantics, 1998 * we fall back to check against current free page availability as 1999 * a best attempt and hopefully to minimize the impact of changing 2000 * semantics that cpuset has. 2001 */ 2002 if (delta > 0) { 2003 if (gather_surplus_pages(h, delta) < 0) 2004 goto out; 2005 2006 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { 2007 return_unused_surplus_pages(h, delta); 2008 goto out; 2009 } 2010 } 2011 2012 ret = 0; 2013 if (delta < 0) 2014 return_unused_surplus_pages(h, (unsigned long) -delta); 2015 2016out: 2017 spin_unlock(&hugetlb_lock); 2018 return ret; 2019} 2020 2021static void hugetlb_vm_op_open(struct vm_area_struct *vma) 2022{ 2023 struct resv_map *reservations = vma_resv_map(vma); 2024 2025 /* 2026 * This new VMA should share its siblings reservation map if present. 2027 * The VMA will only ever have a valid reservation map pointer where 2028 * it is being copied for another still existing VMA. As that VMA 2029 * has a reference to the reservation map it cannot dissappear until 2030 * after this open call completes. It is therefore safe to take a 2031 * new reference here without additional locking. 2032 */ 2033 if (reservations) 2034 kref_get(&reservations->refs); 2035} 2036 2037static void hugetlb_vm_op_close(struct vm_area_struct *vma) 2038{ 2039 struct hstate *h = hstate_vma(vma); 2040 struct resv_map *reservations = vma_resv_map(vma); 2041 unsigned long reserve; 2042 unsigned long start; 2043 unsigned long end; 2044 2045 if (reservations) { 2046 start = vma_hugecache_offset(h, vma, vma->vm_start); 2047 end = vma_hugecache_offset(h, vma, vma->vm_end); 2048 2049 reserve = (end - start) - 2050 region_count(&reservations->regions, start, end); 2051 2052 kref_put(&reservations->refs, resv_map_release); 2053 2054 if (reserve) { 2055 hugetlb_acct_memory(h, -reserve); 2056 hugetlb_put_quota(vma->vm_file->f_mapping, reserve); 2057 } 2058 } 2059} 2060 2061/* 2062 * We cannot handle pagefaults against hugetlb pages at all. They cause 2063 * handle_mm_fault() to try to instantiate regular-sized pages in the 2064 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get 2065 * this far. 2066 */ 2067static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 2068{ 2069 BUG(); 2070 return 0; 2071} 2072 2073const struct vm_operations_struct hugetlb_vm_ops = { 2074 .fault = hugetlb_vm_op_fault, 2075 .open = hugetlb_vm_op_open, 2076 .close = hugetlb_vm_op_close, 2077}; 2078 2079static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, 2080 int writable) 2081{ 2082 pte_t entry; 2083 2084 if (writable) { 2085 entry = 2086 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); 2087 } else { 2088 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot)); 2089 } 2090 entry = pte_mkyoung(entry); 2091 entry = pte_mkhuge(entry); 2092 2093 return entry; 2094} 2095 2096static void set_huge_ptep_writable(struct vm_area_struct *vma, 2097 unsigned long address, pte_t *ptep) 2098{ 2099 pte_t entry; 2100 2101 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep))); 2102 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) { 2103 update_mmu_cache(vma, address, ptep); 2104 } 2105} 2106 2107 2108int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, 2109 struct vm_area_struct *vma) 2110{ 2111 pte_t *src_pte, *dst_pte, entry; 2112 struct page *ptepage; 2113 unsigned long addr; 2114 int cow; 2115 struct hstate *h = hstate_vma(vma); 2116 unsigned long sz = huge_page_size(h); 2117 2118 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 2119 2120 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { 2121 src_pte = huge_pte_offset(src, addr); 2122 if (!src_pte) 2123 continue; 2124 dst_pte = huge_pte_alloc(dst, addr, sz); 2125 if (!dst_pte) 2126 goto nomem; 2127 2128 /* If the pagetables are shared don't copy or take references */ 2129 if (dst_pte == src_pte) 2130 continue; 2131 2132 spin_lock(&dst->page_table_lock); 2133 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); 2134 if (!huge_pte_none(huge_ptep_get(src_pte))) { 2135 if (cow) 2136 huge_ptep_set_wrprotect(src, addr, src_pte); 2137 entry = huge_ptep_get(src_pte); 2138 ptepage = pte_page(entry); 2139 get_page(ptepage); 2140 page_dup_rmap(ptepage); 2141 set_huge_pte_at(dst, addr, dst_pte, entry); 2142 } 2143 spin_unlock(&src->page_table_lock); 2144 spin_unlock(&dst->page_table_lock); 2145 } 2146 return 0; 2147 2148nomem: 2149 return -ENOMEM; 2150} 2151 2152void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2153 unsigned long end, struct page *ref_page) 2154{ 2155 struct mm_struct *mm = vma->vm_mm; 2156 unsigned long address; 2157 pte_t *ptep; 2158 pte_t pte; 2159 struct page *page; 2160 struct page *tmp; 2161 struct hstate *h = hstate_vma(vma); 2162 unsigned long sz = huge_page_size(h); 2163 2164 /* 2165 * A page gathering list, protected by per file i_mmap_lock. The 2166 * lock is used to avoid list corruption from multiple unmapping 2167 * of the same page since we are using page->lru. 2168 */ 2169 LIST_HEAD(page_list); 2170 2171 WARN_ON(!is_vm_hugetlb_page(vma)); 2172 BUG_ON(start & ~huge_page_mask(h)); 2173 BUG_ON(end & ~huge_page_mask(h)); 2174 2175 mmu_notifier_invalidate_range_start(mm, start, end); 2176 spin_lock(&mm->page_table_lock); 2177 for (address = start; address < end; address += sz) { 2178 ptep = huge_pte_offset(mm, address); 2179 if (!ptep) 2180 continue; 2181 2182 if (huge_pmd_unshare(mm, &address, ptep)) 2183 continue; 2184 2185 /* 2186 * If a reference page is supplied, it is because a specific 2187 * page is being unmapped, not a range. Ensure the page we 2188 * are about to unmap is the actual page of interest. 2189 */ 2190 if (ref_page) { 2191 pte = huge_ptep_get(ptep); 2192 if (huge_pte_none(pte)) 2193 continue; 2194 page = pte_page(pte); 2195 if (page != ref_page) 2196 continue; 2197 2198 /* 2199 * Mark the VMA as having unmapped its page so that 2200 * future faults in this VMA will fail rather than 2201 * looking like data was lost 2202 */ 2203 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); 2204 } 2205 2206 pte = huge_ptep_get_and_clear(mm, address, ptep); 2207 if (huge_pte_none(pte)) 2208 continue; 2209 2210 page = pte_page(pte); 2211 if (pte_dirty(pte)) 2212 set_page_dirty(page); 2213 list_add(&page->lru, &page_list); 2214 } 2215 spin_unlock(&mm->page_table_lock); 2216 flush_tlb_range(vma, start, end); 2217 mmu_notifier_invalidate_range_end(mm, start, end); 2218 list_for_each_entry_safe(page, tmp, &page_list, lru) { 2219 page_remove_rmap(page); 2220 list_del(&page->lru); 2221 put_page(page); 2222 } 2223} 2224 2225void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2226 unsigned long end, struct page *ref_page) 2227{ 2228 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); 2229 __unmap_hugepage_range(vma, start, end, ref_page); 2230 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); 2231} 2232 2233/* 2234 * This is called when the original mapper is failing to COW a MAP_PRIVATE 2235 * mappping it owns the reserve page for. The intention is to unmap the page 2236 * from other VMAs and let the children be SIGKILLed if they are faulting the 2237 * same region. 2238 */ 2239static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, 2240 struct page *page, unsigned long address) 2241{ 2242 struct hstate *h = hstate_vma(vma); 2243 struct vm_area_struct *iter_vma; 2244 struct address_space *mapping; 2245 struct prio_tree_iter iter; 2246 pgoff_t pgoff; 2247 2248 /* 2249 * vm_pgoff is in PAGE_SIZE units, hence the different calculation 2250 * from page cache lookup which is in HPAGE_SIZE units. 2251 */ 2252 address = address & huge_page_mask(h); 2253 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) 2254 + (vma->vm_pgoff >> PAGE_SHIFT); 2255 mapping = (struct address_space *)page_private(page); 2256 2257 /* 2258 * Take the mapping lock for the duration of the table walk. As 2259 * this mapping should be shared between all the VMAs, 2260 * __unmap_hugepage_range() is called as the lock is already held 2261 */ 2262 spin_lock(&mapping->i_mmap_lock); 2263 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 2264 /* Do not unmap the current VMA */ 2265 if (iter_vma == vma) 2266 continue; 2267 2268 /* 2269 * Unmap the page from other VMAs without their own reserves. 2270 * They get marked to be SIGKILLed if they fault in these 2271 * areas. This is because a future no-page fault on this VMA 2272 * could insert a zeroed page instead of the data existing 2273 * from the time of fork. This would look like data corruption 2274 */ 2275 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2276 __unmap_hugepage_range(iter_vma, 2277 address, address + huge_page_size(h), 2278 page); 2279 } 2280 spin_unlock(&mapping->i_mmap_lock); 2281 2282 return 1; 2283} 2284 2285/* 2286 * Hugetlb_cow() should be called with page lock of the original hugepage held. 2287 */ 2288static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, 2289 unsigned long address, pte_t *ptep, pte_t pte, 2290 struct page *pagecache_page) 2291{ 2292 struct hstate *h = hstate_vma(vma); 2293 struct page *old_page, *new_page; 2294 int avoidcopy; 2295 int outside_reserve = 0; 2296 2297 old_page = pte_page(pte); 2298 2299retry_avoidcopy: 2300 /* If no-one else is actually using this page, avoid the copy 2301 * and just make the page writable */ 2302 avoidcopy = (page_mapcount(old_page) == 1); 2303 if (avoidcopy) { 2304 if (!trylock_page(old_page)) 2305 if (PageAnon(old_page)) 2306 page_move_anon_rmap(old_page, vma, address); 2307 set_huge_ptep_writable(vma, address, ptep); 2308 return 0; 2309 } 2310 2311 /* 2312 * If the process that created a MAP_PRIVATE mapping is about to 2313 * perform a COW due to a shared page count, attempt to satisfy 2314 * the allocation without using the existing reserves. The pagecache 2315 * page is used to determine if the reserve at this address was 2316 * consumed or not. If reserves were used, a partial faulted mapping 2317 * at the time of fork() could consume its reserves on COW instead 2318 * of the full address range. 2319 */ 2320 if (!(vma->vm_flags & VM_MAYSHARE) && 2321 is_vma_resv_set(vma, HPAGE_RESV_OWNER) && 2322 old_page != pagecache_page) 2323 outside_reserve = 1; 2324 2325 page_cache_get(old_page); 2326 2327 /* Drop page_table_lock as buddy allocator may be called */ 2328 spin_unlock(&mm->page_table_lock); 2329 new_page = alloc_huge_page(vma, address, outside_reserve); 2330 2331 if (IS_ERR(new_page)) { 2332 page_cache_release(old_page); 2333 2334 /* 2335 * If a process owning a MAP_PRIVATE mapping fails to COW, 2336 * it is due to references held by a child and an insufficient 2337 * huge page pool. To guarantee the original mappers 2338 * reliability, unmap the page from child processes. The child 2339 * may get SIGKILLed if it later faults. 2340 */ 2341 if (outside_reserve) { 2342 BUG_ON(huge_pte_none(pte)); 2343 if (unmap_ref_private(mm, vma, old_page, address)) { 2344 BUG_ON(page_count(old_page) != 1); 2345 BUG_ON(huge_pte_none(pte)); 2346 spin_lock(&mm->page_table_lock); 2347 goto retry_avoidcopy; 2348 } 2349 WARN_ON_ONCE(1); 2350 } 2351 2352 /* Caller expects lock to be held */ 2353 spin_lock(&mm->page_table_lock); 2354 return -PTR_ERR(new_page); 2355 } 2356 2357 /* 2358 * When the original hugepage is shared one, it does not have 2359 * anon_vma prepared. 2360 */ 2361 if (unlikely(anon_vma_prepare(vma))) 2362 return VM_FAULT_OOM; 2363 2364 copy_huge_page(new_page, old_page, address, vma); 2365 __SetPageUptodate(new_page); 2366 2367 /* 2368 * Retake the page_table_lock to check for racing updates 2369 * before the page tables are altered 2370 */ 2371 spin_lock(&mm->page_table_lock); 2372 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2373 if (likely(pte_same(huge_ptep_get(ptep), pte))) { 2374 /* Break COW */ 2375 huge_ptep_clear_flush(vma, address, ptep); 2376 set_huge_pte_at(mm, address, ptep, 2377 make_huge_pte(vma, new_page, 1)); 2378 page_remove_rmap(old_page); 2379 hugepage_add_anon_rmap(new_page, vma, address); 2380 /* Make the old page be freed below */ 2381 new_page = old_page; 2382 } 2383 page_cache_release(new_page); 2384 page_cache_release(old_page); 2385 return 0; 2386} 2387 2388/* Return the pagecache page at a given address within a VMA */ 2389static struct page *hugetlbfs_pagecache_page(struct hstate *h, 2390 struct vm_area_struct *vma, unsigned long address) 2391{ 2392 struct address_space *mapping; 2393 pgoff_t idx; 2394 2395 mapping = vma->vm_file->f_mapping; 2396 idx = vma_hugecache_offset(h, vma, address); 2397 2398 return find_lock_page(mapping, idx); 2399} 2400 2401/* 2402 * Return whether there is a pagecache page to back given address within VMA. 2403 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. 2404 */ 2405static bool hugetlbfs_pagecache_present(struct hstate *h, 2406 struct vm_area_struct *vma, unsigned long address) 2407{ 2408 struct address_space *mapping; 2409 pgoff_t idx; 2410 struct page *page; 2411 2412 mapping = vma->vm_file->f_mapping; 2413 idx = vma_hugecache_offset(h, vma, address); 2414 2415 page = find_get_page(mapping, idx); 2416 if (page) 2417 put_page(page); 2418 return page != NULL; 2419} 2420 2421static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2422 unsigned long address, pte_t *ptep, unsigned int flags) 2423{ 2424 struct hstate *h = hstate_vma(vma); 2425 int ret = VM_FAULT_SIGBUS; 2426 pgoff_t idx; 2427 unsigned long size; 2428 struct page *page; 2429 struct address_space *mapping; 2430 pte_t new_pte; 2431 2432 /* 2433 * Currently, we are forced to kill the process in the event the 2434 * original mapper has unmapped pages from the child due to a failed 2435 * COW. Warn that such a situation has occured as it may not be obvious 2436 */ 2437 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { 2438 printk(KERN_WARNING 2439 "PID %d killed due to inadequate hugepage pool\n", 2440 current->pid); 2441 return ret; 2442 } 2443 2444 mapping = vma->vm_file->f_mapping; 2445 idx = vma_hugecache_offset(h, vma, address); 2446 2447 /* 2448 * Use page lock to guard against racing truncation 2449 * before we get page_table_lock. 2450 */ 2451retry: 2452 page = find_lock_page(mapping, idx); 2453 if (!page) { 2454 size = i_size_read(mapping->host) >> huge_page_shift(h); 2455 if (idx >= size) 2456 goto out; 2457 page = alloc_huge_page(vma, address, 0); 2458 if (IS_ERR(page)) { 2459 ret = -PTR_ERR(page); 2460 goto out; 2461 } 2462 clear_huge_page(page, address, huge_page_size(h)); 2463 __SetPageUptodate(page); 2464 2465 if (vma->vm_flags & VM_MAYSHARE) { 2466 int err; 2467 struct inode *inode = mapping->host; 2468 2469 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); 2470 if (err) { 2471 put_page(page); 2472 if (err == -EEXIST) 2473 goto retry; 2474 goto out; 2475 } 2476 2477 spin_lock(&inode->i_lock); 2478 inode->i_blocks += blocks_per_huge_page(h); 2479 spin_unlock(&inode->i_lock); 2480 page_dup_rmap(page); 2481 } else { 2482 lock_page(page); 2483 if (unlikely(anon_vma_prepare(vma))) { 2484 ret = VM_FAULT_OOM; 2485 goto backout_unlocked; 2486 } 2487 hugepage_add_new_anon_rmap(page, vma, address); 2488 } 2489 } else { 2490 page_dup_rmap(page); 2491 } 2492 2493 /* 2494 * If we are going to COW a private mapping later, we examine the 2495 * pending reservations for this page now. This will ensure that 2496 * any allocations necessary to record that reservation occur outside 2497 * the spinlock. 2498 */ 2499 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 2500 if (vma_needs_reservation(h, vma, address) < 0) { 2501 ret = VM_FAULT_OOM; 2502 goto backout_unlocked; 2503 } 2504 2505 spin_lock(&mm->page_table_lock); 2506 size = i_size_read(mapping->host) >> huge_page_shift(h); 2507 if (idx >= size) 2508 goto backout; 2509 2510 ret = 0; 2511 if (!huge_pte_none(huge_ptep_get(ptep))) 2512 goto backout; 2513 2514 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) 2515 && (vma->vm_flags & VM_SHARED))); 2516 set_huge_pte_at(mm, address, ptep, new_pte); 2517 2518 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 2519 /* Optimization, do the COW without a second fault */ 2520 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); 2521 } 2522 2523 spin_unlock(&mm->page_table_lock); 2524 unlock_page(page); 2525out: 2526 return ret; 2527 2528backout: 2529 spin_unlock(&mm->page_table_lock); 2530backout_unlocked: 2531 unlock_page(page); 2532 put_page(page); 2533 goto out; 2534} 2535 2536int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2537 unsigned long address, unsigned int flags) 2538{ 2539 pte_t *ptep; 2540 pte_t entry; 2541 int ret; 2542 struct page *page = NULL; 2543 struct page *pagecache_page = NULL; 2544 static DEFINE_MUTEX(hugetlb_instantiation_mutex); 2545 struct hstate *h = hstate_vma(vma); 2546 2547 ptep = huge_pte_alloc(mm, address, huge_page_size(h)); 2548 if (!ptep) 2549 return VM_FAULT_OOM; 2550 2551 /* 2552 * Serialize hugepage allocation and instantiation, so that we don't 2553 * get spurious allocation failures if two CPUs race to instantiate 2554 * the same page in the page cache. 2555 */ 2556 mutex_lock(&hugetlb_instantiation_mutex); 2557 entry = huge_ptep_get(ptep); 2558 if (huge_pte_none(entry)) { 2559 ret = hugetlb_no_page(mm, vma, address, ptep, flags); 2560 goto out_mutex; 2561 } 2562 2563 ret = 0; 2564 2565 /* 2566 * If we are going to COW the mapping later, we examine the pending 2567 * reservations for this page now. This will ensure that any 2568 * allocations necessary to record that reservation occur outside the 2569 * spinlock. For private mappings, we also lookup the pagecache 2570 * page now as it is used to determine if a reservation has been 2571 * consumed. 2572 */ 2573 if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) { 2574 if (vma_needs_reservation(h, vma, address) < 0) { 2575 ret = VM_FAULT_OOM; 2576 goto out_mutex; 2577 } 2578 2579 if (!(vma->vm_flags & VM_MAYSHARE)) 2580 pagecache_page = hugetlbfs_pagecache_page(h, 2581 vma, address); 2582 } 2583 2584 if (!pagecache_page) { 2585 page = pte_page(entry); 2586 lock_page(page); 2587 } 2588 2589 spin_lock(&mm->page_table_lock); 2590 /* Check for a racing update before calling hugetlb_cow */ 2591 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 2592 goto out_page_table_lock; 2593 2594 2595 if (flags & FAULT_FLAG_WRITE) { 2596 if (!pte_write(entry)) { 2597 ret = hugetlb_cow(mm, vma, address, ptep, entry, 2598 pagecache_page); 2599 goto out_page_table_lock; 2600 } 2601 entry = pte_mkdirty(entry); 2602 } 2603 entry = pte_mkyoung(entry); 2604 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 2605 flags & FAULT_FLAG_WRITE)) 2606 update_mmu_cache(vma, address, ptep); 2607 2608out_page_table_lock: 2609 spin_unlock(&mm->page_table_lock); 2610 2611 if (pagecache_page) { 2612 unlock_page(pagecache_page); 2613 put_page(pagecache_page); 2614 } else { 2615 unlock_page(page); 2616 } 2617 2618out_mutex: 2619 mutex_unlock(&hugetlb_instantiation_mutex); 2620 2621 return ret; 2622} 2623 2624/* Can be overriden by architectures */ 2625__attribute__((weak)) struct page * 2626follow_huge_pud(struct mm_struct *mm, unsigned long address, 2627 pud_t *pud, int write) 2628{ 2629 BUG(); 2630 return NULL; 2631} 2632 2633int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 2634 struct page **pages, struct vm_area_struct **vmas, 2635 unsigned long *position, int *length, int i, 2636 unsigned int flags) 2637{ 2638 unsigned long pfn_offset; 2639 unsigned long vaddr = *position; 2640 int remainder = *length; 2641 struct hstate *h = hstate_vma(vma); 2642 2643 spin_lock(&mm->page_table_lock); 2644 while (vaddr < vma->vm_end && remainder) { 2645 pte_t *pte; 2646 int absent; 2647 struct page *page; 2648 2649 /* 2650 * Some archs (sparc64, sh*) have multiple pte_ts to 2651 * each hugepage. We have to make sure we get the 2652 * first, for the page indexing below to work. 2653 */ 2654 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); 2655 absent = !pte || huge_pte_none(huge_ptep_get(pte)); 2656 2657 /* 2658 * When coredumping, it suits get_dump_page if we just return 2659 * an error where there's an empty slot with no huge pagecache 2660 * to back it. This way, we avoid allocating a hugepage, and 2661 * the sparse dumpfile avoids allocating disk blocks, but its 2662 * huge holes still show up with zeroes where they need to be. 2663 */ 2664 if (absent && (flags & FOLL_DUMP) && 2665 !hugetlbfs_pagecache_present(h, vma, vaddr)) { 2666 remainder = 0; 2667 break; 2668 } 2669 2670 if (absent || 2671 ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { 2672 int ret; 2673 2674 spin_unlock(&mm->page_table_lock); 2675 ret = hugetlb_fault(mm, vma, vaddr, 2676 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); 2677 spin_lock(&mm->page_table_lock); 2678 if (!(ret & VM_FAULT_ERROR)) 2679 continue; 2680 2681 remainder = 0; 2682 break; 2683 } 2684 2685 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; 2686 page = pte_page(huge_ptep_get(pte)); 2687same_page: 2688 if (pages) { 2689 pages[i] = mem_map_offset(page, pfn_offset); 2690 get_page(pages[i]); 2691 } 2692 2693 if (vmas) 2694 vmas[i] = vma; 2695 2696 vaddr += PAGE_SIZE; 2697 ++pfn_offset; 2698 --remainder; 2699 ++i; 2700 if (vaddr < vma->vm_end && remainder && 2701 pfn_offset < pages_per_huge_page(h)) { 2702 /* 2703 * We use pfn_offset to avoid touching the pageframes 2704 * of this compound page. 2705 */ 2706 goto same_page; 2707 } 2708 } 2709 spin_unlock(&mm->page_table_lock); 2710 *length = remainder; 2711 *position = vaddr; 2712 2713 return i ? i : -EFAULT; 2714} 2715 2716void hugetlb_change_protection(struct vm_area_struct *vma, 2717 unsigned long address, unsigned long end, pgprot_t newprot) 2718{ 2719 struct mm_struct *mm = vma->vm_mm; 2720 unsigned long start = address; 2721 pte_t *ptep; 2722 pte_t pte; 2723 struct hstate *h = hstate_vma(vma); 2724 2725 BUG_ON(address >= end); 2726 flush_cache_range(vma, address, end); 2727 2728 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); 2729 spin_lock(&mm->page_table_lock); 2730 for (; address < end; address += huge_page_size(h)) { 2731 ptep = huge_pte_offset(mm, address); 2732 if (!ptep) 2733 continue; 2734 if (huge_pmd_unshare(mm, &address, ptep)) 2735 continue; 2736 if (!huge_pte_none(huge_ptep_get(ptep))) { 2737 pte = huge_ptep_get_and_clear(mm, address, ptep); 2738 pte = pte_mkhuge(pte_modify(pte, newprot)); 2739 set_huge_pte_at(mm, address, ptep, pte); 2740 } 2741 } 2742 spin_unlock(&mm->page_table_lock); 2743 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); 2744 2745 flush_tlb_range(vma, start, end); 2746} 2747 2748int hugetlb_reserve_pages(struct inode *inode, 2749 long from, long to, 2750 struct vm_area_struct *vma, 2751 int acctflag) 2752{ 2753 long ret, chg; 2754 struct hstate *h = hstate_inode(inode); 2755 2756 /* 2757 * Only apply hugepage reservation if asked. At fault time, an 2758 * attempt will be made for VM_NORESERVE to allocate a page 2759 * and filesystem quota without using reserves 2760 */ 2761 if (acctflag & VM_NORESERVE) 2762 return 0; 2763 2764 /* 2765 * Shared mappings base their reservation on the number of pages that 2766 * are already allocated on behalf of the file. Private mappings need 2767 * to reserve the full area even if read-only as mprotect() may be 2768 * called to make the mapping read-write. Assume !vma is a shm mapping 2769 */ 2770 if (!vma || vma->vm_flags & VM_MAYSHARE) 2771 chg = region_chg(&inode->i_mapping->private_list, from, to); 2772 else { 2773 struct resv_map *resv_map = resv_map_alloc(); 2774 if (!resv_map) 2775 return -ENOMEM; 2776 2777 chg = to - from; 2778 2779 set_vma_resv_map(vma, resv_map); 2780 set_vma_resv_flags(vma, HPAGE_RESV_OWNER); 2781 } 2782 2783 if (chg < 0) 2784 return chg; 2785 2786 /* There must be enough filesystem quota for the mapping */ 2787 if (hugetlb_get_quota(inode->i_mapping, chg)) 2788 return -ENOSPC; 2789 2790 /* 2791 * Check enough hugepages are available for the reservation. 2792 * Hand back the quota if there are not 2793 */ 2794 ret = hugetlb_acct_memory(h, chg); 2795 if (ret < 0) { 2796 hugetlb_put_quota(inode->i_mapping, chg); 2797 return ret; 2798 } 2799 2800 /* 2801 * Account for the reservations made. Shared mappings record regions 2802 * that have reservations as they are shared by multiple VMAs. 2803 * When the last VMA disappears, the region map says how much 2804 * the reservation was and the page cache tells how much of 2805 * the reservation was consumed. Private mappings are per-VMA and 2806 * only the consumed reservations are tracked. When the VMA 2807 * disappears, the original reservation is the VMA size and the 2808 * consumed reservations are stored in the map. Hence, nothing 2809 * else has to be done for private mappings here 2810 */ 2811 if (!vma || vma->vm_flags & VM_MAYSHARE) 2812 region_add(&inode->i_mapping->private_list, from, to); 2813 return 0; 2814} 2815 2816void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) 2817{ 2818 struct hstate *h = hstate_inode(inode); 2819 long chg = region_truncate(&inode->i_mapping->private_list, offset); 2820 2821 spin_lock(&inode->i_lock); 2822 inode->i_blocks -= (blocks_per_huge_page(h) * freed); 2823 spin_unlock(&inode->i_lock); 2824 2825 hugetlb_put_quota(inode->i_mapping, (chg - freed)); 2826 hugetlb_acct_memory(h, -(chg - freed)); 2827} 2828