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 #include <linux/swap.h> 23 #include <linux/swapops.h> 24 25 #include <asm/page.h> 26 #include <asm/pgtable.h> 27 #include <linux/io.h> 28 29 #include <linux/hugetlb.h> 30 #include <linux/node.h> 31 #include "internal.h" 32 33 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; 34 static gfp_t htlb_alloc_mask = GFP_HIGHUSER; 35 unsigned long hugepages_treat_as_movable; 36 37 static int max_hstate; 38 unsigned int default_hstate_idx; 39 struct hstate hstates[HUGE_MAX_HSTATE]; 40 41 __initdata LIST_HEAD(huge_boot_pages); 42 43 /* for command line parsing */ 44 static struct hstate * __initdata parsed_hstate; 45 static unsigned long __initdata default_hstate_max_huge_pages; 46 static unsigned long __initdata default_hstate_size; 47 48 #define for_each_hstate(h) \ 49 for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++) 50 51 /* 52 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages 53 */ 54 static DEFINE_SPINLOCK(hugetlb_lock); 55 56 /* 57 * Region tracking -- allows tracking of reservations and instantiated pages 58 * across the pages in a mapping. 59 * 60 * The region data structures are protected by a combination of the mmap_sem 61 * and the hugetlb_instantion_mutex. To access or modify a region the caller 62 * must either hold the mmap_sem for write, or the mmap_sem for read and 63 * the hugetlb_instantiation mutex: 64 * 65 * down_write(&mm->mmap_sem); 66 * or 67 * down_read(&mm->mmap_sem); 68 * mutex_lock(&hugetlb_instantiation_mutex); 69 */ 70 struct file_region { 71 struct list_head link; 72 long from; 73 long to; 74 }; 75 76 static long region_add(struct list_head *head, long f, long t) 77 { 78 struct file_region *rg, *nrg, *trg; 79 80 /* Locate the region we are either in or before. */ 81 list_for_each_entry(rg, head, link) 82 if (f <= rg->to) 83 break; 84 85 /* Round our left edge to the current segment if it encloses us. */ 86 if (f > rg->from) 87 f = rg->from; 88 89 /* Check for and consume any regions we now overlap with. */ 90 nrg = rg; 91 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 92 if (&rg->link == head) 93 break; 94 if (rg->from > t) 95 break; 96 97 /* If this area reaches higher then extend our area to 98 * include it completely. If this is not the first area 99 * which we intend to reuse, free it. */ 100 if (rg->to > t) 101 t = rg->to; 102 if (rg != nrg) { 103 list_del(&rg->link); 104 kfree(rg); 105 } 106 } 107 nrg->from = f; 108 nrg->to = t; 109 return 0; 110 } 111 112 static long region_chg(struct list_head *head, long f, long t) 113 { 114 struct file_region *rg, *nrg; 115 long chg = 0; 116 117 /* Locate the region we are before or in. */ 118 list_for_each_entry(rg, head, link) 119 if (f <= rg->to) 120 break; 121 122 /* If we are below the current region then a new region is required. 123 * Subtle, allocate a new region at the position but make it zero 124 * size such that we can guarantee to record the reservation. */ 125 if (&rg->link == head || t < rg->from) { 126 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); 127 if (!nrg) 128 return -ENOMEM; 129 nrg->from = f; 130 nrg->to = f; 131 INIT_LIST_HEAD(&nrg->link); 132 list_add(&nrg->link, rg->link.prev); 133 134 return t - f; 135 } 136 137 /* Round our left edge to the current segment if it encloses us. */ 138 if (f > rg->from) 139 f = rg->from; 140 chg = t - f; 141 142 /* Check for and consume any regions we now overlap with. */ 143 list_for_each_entry(rg, rg->link.prev, link) { 144 if (&rg->link == head) 145 break; 146 if (rg->from > t) 147 return chg; 148 149 /* We overlap with this area, if it extends further than 150 * us then we must extend ourselves. Account for its 151 * existing reservation. */ 152 if (rg->to > t) { 153 chg += rg->to - t; 154 t = rg->to; 155 } 156 chg -= rg->to - rg->from; 157 } 158 return chg; 159 } 160 161 static long region_truncate(struct list_head *head, long end) 162 { 163 struct file_region *rg, *trg; 164 long chg = 0; 165 166 /* Locate the region we are either in or before. */ 167 list_for_each_entry(rg, head, link) 168 if (end <= rg->to) 169 break; 170 if (&rg->link == head) 171 return 0; 172 173 /* If we are in the middle of a region then adjust it. */ 174 if (end > rg->from) { 175 chg = rg->to - end; 176 rg->to = end; 177 rg = list_entry(rg->link.next, typeof(*rg), link); 178 } 179 180 /* Drop any remaining regions. */ 181 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 182 if (&rg->link == head) 183 break; 184 chg += rg->to - rg->from; 185 list_del(&rg->link); 186 kfree(rg); 187 } 188 return chg; 189 } 190 191 static long region_count(struct list_head *head, long f, long t) 192 { 193 struct file_region *rg; 194 long chg = 0; 195 196 /* Locate each segment we overlap with, and count that overlap. */ 197 list_for_each_entry(rg, head, link) { 198 int seg_from; 199 int seg_to; 200 201 if (rg->to <= f) 202 continue; 203 if (rg->from >= t) 204 break; 205 206 seg_from = max(rg->from, f); 207 seg_to = min(rg->to, t); 208 209 chg += seg_to - seg_from; 210 } 211 212 return chg; 213 } 214 215 /* 216 * Convert the address within this vma to the page offset within 217 * the mapping, in pagecache page units; huge pages here. 218 */ 219 static pgoff_t vma_hugecache_offset(struct hstate *h, 220 struct vm_area_struct *vma, unsigned long address) 221 { 222 return ((address - vma->vm_start) >> huge_page_shift(h)) + 223 (vma->vm_pgoff >> huge_page_order(h)); 224 } 225 226 pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 227 unsigned long address) 228 { 229 return vma_hugecache_offset(hstate_vma(vma), vma, address); 230 } 231 232 /* 233 * Return the size of the pages allocated when backing a VMA. In the majority 234 * cases this will be same size as used by the page table entries. 235 */ 236 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) 237 { 238 struct hstate *hstate; 239 240 if (!is_vm_hugetlb_page(vma)) 241 return PAGE_SIZE; 242 243 hstate = hstate_vma(vma); 244 245 return 1UL << (hstate->order + PAGE_SHIFT); 246 } 247 EXPORT_SYMBOL_GPL(vma_kernel_pagesize); 248 249 /* 250 * Return the page size being used by the MMU to back a VMA. In the majority 251 * of cases, the page size used by the kernel matches the MMU size. On 252 * architectures where it differs, an architecture-specific version of this 253 * function is required. 254 */ 255 #ifndef vma_mmu_pagesize 256 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) 257 { 258 return vma_kernel_pagesize(vma); 259 } 260 #endif 261 262 /* 263 * Flags for MAP_PRIVATE reservations. These are stored in the bottom 264 * bits of the reservation map pointer, which are always clear due to 265 * alignment. 266 */ 267 #define HPAGE_RESV_OWNER (1UL << 0) 268 #define HPAGE_RESV_UNMAPPED (1UL << 1) 269 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) 270 271 /* 272 * These helpers are used to track how many pages are reserved for 273 * faults in a MAP_PRIVATE mapping. Only the process that called mmap() 274 * is guaranteed to have their future faults succeed. 275 * 276 * With the exception of reset_vma_resv_huge_pages() which is called at fork(), 277 * the reserve counters are updated with the hugetlb_lock held. It is safe 278 * to reset the VMA at fork() time as it is not in use yet and there is no 279 * chance of the global counters getting corrupted as a result of the values. 280 * 281 * The private mapping reservation is represented in a subtly different 282 * manner to a shared mapping. A shared mapping has a region map associated 283 * with the underlying file, this region map represents the backing file 284 * pages which have ever had a reservation assigned which this persists even 285 * after the page is instantiated. A private mapping has a region map 286 * associated with the original mmap which is attached to all VMAs which 287 * reference it, this region map represents those offsets which have consumed 288 * reservation ie. where pages have been instantiated. 289 */ 290 static unsigned long get_vma_private_data(struct vm_area_struct *vma) 291 { 292 return (unsigned long)vma->vm_private_data; 293 } 294 295 static void set_vma_private_data(struct vm_area_struct *vma, 296 unsigned long value) 297 { 298 vma->vm_private_data = (void *)value; 299 } 300 301 struct resv_map { 302 struct kref refs; 303 struct list_head regions; 304 }; 305 306 static struct resv_map *resv_map_alloc(void) 307 { 308 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); 309 if (!resv_map) 310 return NULL; 311 312 kref_init(&resv_map->refs); 313 INIT_LIST_HEAD(&resv_map->regions); 314 315 return resv_map; 316 } 317 318 static void resv_map_release(struct kref *ref) 319 { 320 struct resv_map *resv_map = container_of(ref, struct resv_map, refs); 321 322 /* Clear out any active regions before we release the map. */ 323 region_truncate(&resv_map->regions, 0); 324 kfree(resv_map); 325 } 326 327 static struct resv_map *vma_resv_map(struct vm_area_struct *vma) 328 { 329 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 330 if (!(vma->vm_flags & VM_MAYSHARE)) 331 return (struct resv_map *)(get_vma_private_data(vma) & 332 ~HPAGE_RESV_MASK); 333 return NULL; 334 } 335 336 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) 337 { 338 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 339 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 340 341 set_vma_private_data(vma, (get_vma_private_data(vma) & 342 HPAGE_RESV_MASK) | (unsigned long)map); 343 } 344 345 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) 346 { 347 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 348 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 349 350 set_vma_private_data(vma, get_vma_private_data(vma) | flags); 351 } 352 353 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) 354 { 355 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 356 357 return (get_vma_private_data(vma) & flag) != 0; 358 } 359 360 /* Decrement the reserved pages in the hugepage pool by one */ 361 static void decrement_hugepage_resv_vma(struct hstate *h, 362 struct vm_area_struct *vma) 363 { 364 if (vma->vm_flags & VM_NORESERVE) 365 return; 366 367 if (vma->vm_flags & VM_MAYSHARE) { 368 /* Shared mappings always use reserves */ 369 h->resv_huge_pages--; 370 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 371 /* 372 * Only the process that called mmap() has reserves for 373 * private mappings. 374 */ 375 h->resv_huge_pages--; 376 } 377 } 378 379 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */ 380 void reset_vma_resv_huge_pages(struct vm_area_struct *vma) 381 { 382 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 383 if (!(vma->vm_flags & VM_MAYSHARE)) 384 vma->vm_private_data = (void *)0; 385 } 386 387 /* Returns true if the VMA has associated reserve pages */ 388 static int vma_has_reserves(struct vm_area_struct *vma) 389 { 390 if (vma->vm_flags & VM_MAYSHARE) 391 return 1; 392 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 393 return 1; 394 return 0; 395 } 396 397 static void copy_gigantic_page(struct page *dst, struct page *src) 398 { 399 int i; 400 struct hstate *h = page_hstate(src); 401 struct page *dst_base = dst; 402 struct page *src_base = src; 403 404 for (i = 0; i < pages_per_huge_page(h); ) { 405 cond_resched(); 406 copy_highpage(dst, src); 407 408 i++; 409 dst = mem_map_next(dst, dst_base, i); 410 src = mem_map_next(src, src_base, i); 411 } 412 } 413 414 void copy_huge_page(struct page *dst, struct page *src) 415 { 416 int i; 417 struct hstate *h = page_hstate(src); 418 419 if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { 420 copy_gigantic_page(dst, src); 421 return; 422 } 423 424 might_sleep(); 425 for (i = 0; i < pages_per_huge_page(h); i++) { 426 cond_resched(); 427 copy_highpage(dst + i, src + i); 428 } 429 } 430 431 static void enqueue_huge_page(struct hstate *h, struct page *page) 432 { 433 int nid = page_to_nid(page); 434 list_add(&page->lru, &h->hugepage_freelists[nid]); 435 h->free_huge_pages++; 436 h->free_huge_pages_node[nid]++; 437 } 438 439 static struct page *dequeue_huge_page_node(struct hstate *h, int nid) 440 { 441 struct page *page; 442 443 if (list_empty(&h->hugepage_freelists[nid])) 444 return NULL; 445 page = list_entry(h->hugepage_freelists[nid].next, struct page, lru); 446 list_del(&page->lru); 447 set_page_refcounted(page); 448 h->free_huge_pages--; 449 h->free_huge_pages_node[nid]--; 450 return page; 451 } 452 453 static struct page *dequeue_huge_page_vma(struct hstate *h, 454 struct vm_area_struct *vma, 455 unsigned long address, int avoid_reserve) 456 { 457 struct page *page = NULL; 458 struct mempolicy *mpol; 459 nodemask_t *nodemask; 460 struct zonelist *zonelist; 461 struct zone *zone; 462 struct zoneref *z; 463 464 get_mems_allowed(); 465 zonelist = huge_zonelist(vma, address, 466 htlb_alloc_mask, &mpol, &nodemask); 467 /* 468 * A child process with MAP_PRIVATE mappings created by their parent 469 * have no page reserves. This check ensures that reservations are 470 * not "stolen". The child may still get SIGKILLed 471 */ 472 if (!vma_has_reserves(vma) && 473 h->free_huge_pages - h->resv_huge_pages == 0) 474 goto err; 475 476 /* If reserves cannot be used, ensure enough pages are in the pool */ 477 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) 478 goto err; 479 480 for_each_zone_zonelist_nodemask(zone, z, zonelist, 481 MAX_NR_ZONES - 1, nodemask) { 482 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) { 483 page = dequeue_huge_page_node(h, zone_to_nid(zone)); 484 if (page) { 485 if (!avoid_reserve) 486 decrement_hugepage_resv_vma(h, vma); 487 break; 488 } 489 } 490 } 491 err: 492 mpol_cond_put(mpol); 493 put_mems_allowed(); 494 return page; 495 } 496 497 static void update_and_free_page(struct hstate *h, struct page *page) 498 { 499 int i; 500 501 VM_BUG_ON(h->order >= MAX_ORDER); 502 503 h->nr_huge_pages--; 504 h->nr_huge_pages_node[page_to_nid(page)]--; 505 for (i = 0; i < pages_per_huge_page(h); i++) { 506 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 507 1 << PG_referenced | 1 << PG_dirty | 508 1 << PG_active | 1 << PG_reserved | 509 1 << PG_private | 1 << PG_writeback); 510 } 511 set_compound_page_dtor(page, NULL); 512 set_page_refcounted(page); 513 arch_release_hugepage(page); 514 __free_pages(page, huge_page_order(h)); 515 } 516 517 struct hstate *size_to_hstate(unsigned long size) 518 { 519 struct hstate *h; 520 521 for_each_hstate(h) { 522 if (huge_page_size(h) == size) 523 return h; 524 } 525 return NULL; 526 } 527 528 static void free_huge_page(struct page *page) 529 { 530 /* 531 * Can't pass hstate in here because it is called from the 532 * compound page destructor. 533 */ 534 struct hstate *h = page_hstate(page); 535 int nid = page_to_nid(page); 536 struct address_space *mapping; 537 538 mapping = (struct address_space *) page_private(page); 539 set_page_private(page, 0); 540 page->mapping = NULL; 541 BUG_ON(page_count(page)); 542 BUG_ON(page_mapcount(page)); 543 INIT_LIST_HEAD(&page->lru); 544 545 spin_lock(&hugetlb_lock); 546 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { 547 update_and_free_page(h, page); 548 h->surplus_huge_pages--; 549 h->surplus_huge_pages_node[nid]--; 550 } else { 551 enqueue_huge_page(h, page); 552 } 553 spin_unlock(&hugetlb_lock); 554 if (mapping) 555 hugetlb_put_quota(mapping, 1); 556 } 557 558 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) 559 { 560 set_compound_page_dtor(page, free_huge_page); 561 spin_lock(&hugetlb_lock); 562 h->nr_huge_pages++; 563 h->nr_huge_pages_node[nid]++; 564 spin_unlock(&hugetlb_lock); 565 put_page(page); /* free it into the hugepage allocator */ 566 } 567 568 static void prep_compound_gigantic_page(struct page *page, unsigned long order) 569 { 570 int i; 571 int nr_pages = 1 << order; 572 struct page *p = page + 1; 573 574 /* we rely on prep_new_huge_page to set the destructor */ 575 set_compound_order(page, order); 576 __SetPageHead(page); 577 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { 578 __SetPageTail(p); 579 set_page_count(p, 0); 580 p->first_page = page; 581 } 582 } 583 584 int PageHuge(struct page *page) 585 { 586 compound_page_dtor *dtor; 587 588 if (!PageCompound(page)) 589 return 0; 590 591 page = compound_head(page); 592 dtor = get_compound_page_dtor(page); 593 594 return dtor == free_huge_page; 595 } 596 EXPORT_SYMBOL_GPL(PageHuge); 597 598 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 599 { 600 struct page *page; 601 602 if (h->order >= MAX_ORDER) 603 return NULL; 604 605 page = alloc_pages_exact_node(nid, 606 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 607 __GFP_REPEAT|__GFP_NOWARN, 608 huge_page_order(h)); 609 if (page) { 610 if (arch_prepare_hugepage(page)) { 611 __free_pages(page, huge_page_order(h)); 612 return NULL; 613 } 614 prep_new_huge_page(h, page, nid); 615 } 616 617 return page; 618 } 619 620 /* 621 * common helper functions for hstate_next_node_to_{alloc|free}. 622 * We may have allocated or freed a huge page based on a different 623 * nodes_allowed previously, so h->next_node_to_{alloc|free} might 624 * be outside of *nodes_allowed. Ensure that we use an allowed 625 * node for alloc or free. 626 */ 627 static int next_node_allowed(int nid, nodemask_t *nodes_allowed) 628 { 629 nid = next_node(nid, *nodes_allowed); 630 if (nid == MAX_NUMNODES) 631 nid = first_node(*nodes_allowed); 632 VM_BUG_ON(nid >= MAX_NUMNODES); 633 634 return nid; 635 } 636 637 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) 638 { 639 if (!node_isset(nid, *nodes_allowed)) 640 nid = next_node_allowed(nid, nodes_allowed); 641 return nid; 642 } 643 644 /* 645 * returns the previously saved node ["this node"] from which to 646 * allocate a persistent huge page for the pool and advance the 647 * next node from which to allocate, handling wrap at end of node 648 * mask. 649 */ 650 static int hstate_next_node_to_alloc(struct hstate *h, 651 nodemask_t *nodes_allowed) 652 { 653 int nid; 654 655 VM_BUG_ON(!nodes_allowed); 656 657 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); 658 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); 659 660 return nid; 661 } 662 663 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) 664 { 665 struct page *page; 666 int start_nid; 667 int next_nid; 668 int ret = 0; 669 670 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 671 next_nid = start_nid; 672 673 do { 674 page = alloc_fresh_huge_page_node(h, next_nid); 675 if (page) { 676 ret = 1; 677 break; 678 } 679 next_nid = hstate_next_node_to_alloc(h, nodes_allowed); 680 } while (next_nid != start_nid); 681 682 if (ret) 683 count_vm_event(HTLB_BUDDY_PGALLOC); 684 else 685 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 686 687 return ret; 688 } 689 690 /* 691 * helper for free_pool_huge_page() - return the previously saved 692 * node ["this node"] from which to free a huge page. Advance the 693 * next node id whether or not we find a free huge page to free so 694 * that the next attempt to free addresses the next node. 695 */ 696 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) 697 { 698 int nid; 699 700 VM_BUG_ON(!nodes_allowed); 701 702 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); 703 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); 704 705 return nid; 706 } 707 708 /* 709 * Free huge page from pool from next node to free. 710 * Attempt to keep persistent huge pages more or less 711 * balanced over allowed nodes. 712 * Called with hugetlb_lock locked. 713 */ 714 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, 715 bool acct_surplus) 716 { 717 int start_nid; 718 int next_nid; 719 int ret = 0; 720 721 start_nid = hstate_next_node_to_free(h, nodes_allowed); 722 next_nid = start_nid; 723 724 do { 725 /* 726 * If we're returning unused surplus pages, only examine 727 * nodes with surplus pages. 728 */ 729 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) && 730 !list_empty(&h->hugepage_freelists[next_nid])) { 731 struct page *page = 732 list_entry(h->hugepage_freelists[next_nid].next, 733 struct page, lru); 734 list_del(&page->lru); 735 h->free_huge_pages--; 736 h->free_huge_pages_node[next_nid]--; 737 if (acct_surplus) { 738 h->surplus_huge_pages--; 739 h->surplus_huge_pages_node[next_nid]--; 740 } 741 update_and_free_page(h, page); 742 ret = 1; 743 break; 744 } 745 next_nid = hstate_next_node_to_free(h, nodes_allowed); 746 } while (next_nid != start_nid); 747 748 return ret; 749 } 750 751 static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) 752 { 753 struct page *page; 754 unsigned int r_nid; 755 756 if (h->order >= MAX_ORDER) 757 return NULL; 758 759 /* 760 * Assume we will successfully allocate the surplus page to 761 * prevent racing processes from causing the surplus to exceed 762 * overcommit 763 * 764 * This however introduces a different race, where a process B 765 * tries to grow the static hugepage pool while alloc_pages() is 766 * called by process A. B will only examine the per-node 767 * counters in determining if surplus huge pages can be 768 * converted to normal huge pages in adjust_pool_surplus(). A 769 * won't be able to increment the per-node counter, until the 770 * lock is dropped by B, but B doesn't drop hugetlb_lock until 771 * no more huge pages can be converted from surplus to normal 772 * state (and doesn't try to convert again). Thus, we have a 773 * case where a surplus huge page exists, the pool is grown, and 774 * the surplus huge page still exists after, even though it 775 * should just have been converted to a normal huge page. This 776 * does not leak memory, though, as the hugepage will be freed 777 * once it is out of use. It also does not allow the counters to 778 * go out of whack in adjust_pool_surplus() as we don't modify 779 * the node values until we've gotten the hugepage and only the 780 * per-node value is checked there. 781 */ 782 spin_lock(&hugetlb_lock); 783 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { 784 spin_unlock(&hugetlb_lock); 785 return NULL; 786 } else { 787 h->nr_huge_pages++; 788 h->surplus_huge_pages++; 789 } 790 spin_unlock(&hugetlb_lock); 791 792 if (nid == NUMA_NO_NODE) 793 page = alloc_pages(htlb_alloc_mask|__GFP_COMP| 794 __GFP_REPEAT|__GFP_NOWARN, 795 huge_page_order(h)); 796 else 797 page = alloc_pages_exact_node(nid, 798 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 799 __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h)); 800 801 if (page && arch_prepare_hugepage(page)) { 802 __free_pages(page, huge_page_order(h)); 803 page = NULL; 804 } 805 806 spin_lock(&hugetlb_lock); 807 if (page) { 808 r_nid = page_to_nid(page); 809 set_compound_page_dtor(page, free_huge_page); 810 /* 811 * We incremented the global counters already 812 */ 813 h->nr_huge_pages_node[r_nid]++; 814 h->surplus_huge_pages_node[r_nid]++; 815 __count_vm_event(HTLB_BUDDY_PGALLOC); 816 } else { 817 h->nr_huge_pages--; 818 h->surplus_huge_pages--; 819 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 820 } 821 spin_unlock(&hugetlb_lock); 822 823 return page; 824 } 825 826 /* 827 * This allocation function is useful in the context where vma is irrelevant. 828 * E.g. soft-offlining uses this function because it only cares physical 829 * address of error page. 830 */ 831 struct page *alloc_huge_page_node(struct hstate *h, int nid) 832 { 833 struct page *page; 834 835 spin_lock(&hugetlb_lock); 836 page = dequeue_huge_page_node(h, nid); 837 spin_unlock(&hugetlb_lock); 838 839 if (!page) 840 page = alloc_buddy_huge_page(h, nid); 841 842 return page; 843 } 844 845 /* 846 * Increase the hugetlb pool such that it can accommodate a reservation 847 * of size 'delta'. 848 */ 849 static int gather_surplus_pages(struct hstate *h, int delta) 850 { 851 struct list_head surplus_list; 852 struct page *page, *tmp; 853 int ret, i; 854 int needed, allocated; 855 856 needed = (h->resv_huge_pages + delta) - h->free_huge_pages; 857 if (needed <= 0) { 858 h->resv_huge_pages += delta; 859 return 0; 860 } 861 862 allocated = 0; 863 INIT_LIST_HEAD(&surplus_list); 864 865 ret = -ENOMEM; 866 retry: 867 spin_unlock(&hugetlb_lock); 868 for (i = 0; i < needed; i++) { 869 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 870 if (!page) 871 /* 872 * We were not able to allocate enough pages to 873 * satisfy the entire reservation so we free what 874 * we've allocated so far. 875 */ 876 goto free; 877 878 list_add(&page->lru, &surplus_list); 879 } 880 allocated += needed; 881 882 /* 883 * After retaking hugetlb_lock, we need to recalculate 'needed' 884 * because either resv_huge_pages or free_huge_pages may have changed. 885 */ 886 spin_lock(&hugetlb_lock); 887 needed = (h->resv_huge_pages + delta) - 888 (h->free_huge_pages + allocated); 889 if (needed > 0) 890 goto retry; 891 892 /* 893 * The surplus_list now contains _at_least_ the number of extra pages 894 * needed to accommodate the reservation. Add the appropriate number 895 * of pages to the hugetlb pool and free the extras back to the buddy 896 * allocator. Commit the entire reservation here to prevent another 897 * process from stealing the pages as they are added to the pool but 898 * before they are reserved. 899 */ 900 needed += allocated; 901 h->resv_huge_pages += delta; 902 ret = 0; 903 904 /* Free the needed pages to the hugetlb pool */ 905 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 906 if ((--needed) < 0) 907 break; 908 list_del(&page->lru); 909 /* 910 * This page is now managed by the hugetlb allocator and has 911 * no users -- drop the buddy allocator's reference. 912 */ 913 put_page_testzero(page); 914 VM_BUG_ON(page_count(page)); 915 enqueue_huge_page(h, page); 916 } 917 spin_unlock(&hugetlb_lock); 918 919 /* Free unnecessary surplus pages to the buddy allocator */ 920 free: 921 if (!list_empty(&surplus_list)) { 922 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 923 list_del(&page->lru); 924 put_page(page); 925 } 926 } 927 spin_lock(&hugetlb_lock); 928 929 return ret; 930 } 931 932 /* 933 * When releasing a hugetlb pool reservation, any surplus pages that were 934 * allocated to satisfy the reservation must be explicitly freed if they were 935 * never used. 936 * Called with hugetlb_lock held. 937 */ 938 static void return_unused_surplus_pages(struct hstate *h, 939 unsigned long unused_resv_pages) 940 { 941 unsigned long nr_pages; 942 943 /* Uncommit the reservation */ 944 h->resv_huge_pages -= unused_resv_pages; 945 946 /* Cannot return gigantic pages currently */ 947 if (h->order >= MAX_ORDER) 948 return; 949 950 nr_pages = min(unused_resv_pages, h->surplus_huge_pages); 951 952 /* 953 * We want to release as many surplus pages as possible, spread 954 * evenly across all nodes with memory. Iterate across these nodes 955 * until we can no longer free unreserved surplus pages. This occurs 956 * when the nodes with surplus pages have no free pages. 957 * free_pool_huge_page() will balance the the freed pages across the 958 * on-line nodes with memory and will handle the hstate accounting. 959 */ 960 while (nr_pages--) { 961 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1)) 962 break; 963 } 964 } 965 966 /* 967 * Determine if the huge page at addr within the vma has an associated 968 * reservation. Where it does not we will need to logically increase 969 * reservation and actually increase quota before an allocation can occur. 970 * Where any new reservation would be required the reservation change is 971 * prepared, but not committed. Once the page has been quota'd allocated 972 * an instantiated the change should be committed via vma_commit_reservation. 973 * No action is required on failure. 974 */ 975 static long vma_needs_reservation(struct hstate *h, 976 struct vm_area_struct *vma, unsigned long addr) 977 { 978 struct address_space *mapping = vma->vm_file->f_mapping; 979 struct inode *inode = mapping->host; 980 981 if (vma->vm_flags & VM_MAYSHARE) { 982 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 983 return region_chg(&inode->i_mapping->private_list, 984 idx, idx + 1); 985 986 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 987 return 1; 988 989 } else { 990 long err; 991 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 992 struct resv_map *reservations = vma_resv_map(vma); 993 994 err = region_chg(&reservations->regions, idx, idx + 1); 995 if (err < 0) 996 return err; 997 return 0; 998 } 999 } 1000 static void vma_commit_reservation(struct hstate *h, 1001 struct vm_area_struct *vma, unsigned long addr) 1002 { 1003 struct address_space *mapping = vma->vm_file->f_mapping; 1004 struct inode *inode = mapping->host; 1005 1006 if (vma->vm_flags & VM_MAYSHARE) { 1007 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1008 region_add(&inode->i_mapping->private_list, idx, idx + 1); 1009 1010 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 1011 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1012 struct resv_map *reservations = vma_resv_map(vma); 1013 1014 /* Mark this page used in the map. */ 1015 region_add(&reservations->regions, idx, idx + 1); 1016 } 1017 } 1018 1019 static struct page *alloc_huge_page(struct vm_area_struct *vma, 1020 unsigned long addr, int avoid_reserve) 1021 { 1022 struct hstate *h = hstate_vma(vma); 1023 struct page *page; 1024 struct address_space *mapping = vma->vm_file->f_mapping; 1025 struct inode *inode = mapping->host; 1026 long chg; 1027 1028 /* 1029 * Processes that did not create the mapping will have no reserves and 1030 * will not have accounted against quota. Check that the quota can be 1031 * made before satisfying the allocation 1032 * MAP_NORESERVE mappings may also need pages and quota allocated 1033 * if no reserve mapping overlaps. 1034 */ 1035 chg = vma_needs_reservation(h, vma, addr); 1036 if (chg < 0) 1037 return ERR_PTR(-VM_FAULT_OOM); 1038 if (chg) 1039 if (hugetlb_get_quota(inode->i_mapping, chg)) 1040 return ERR_PTR(-VM_FAULT_SIGBUS); 1041 1042 spin_lock(&hugetlb_lock); 1043 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); 1044 spin_unlock(&hugetlb_lock); 1045 1046 if (!page) { 1047 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 1048 if (!page) { 1049 hugetlb_put_quota(inode->i_mapping, chg); 1050 return ERR_PTR(-VM_FAULT_SIGBUS); 1051 } 1052 } 1053 1054 set_page_private(page, (unsigned long) mapping); 1055 1056 vma_commit_reservation(h, vma, addr); 1057 1058 return page; 1059 } 1060 1061 int __weak alloc_bootmem_huge_page(struct hstate *h) 1062 { 1063 struct huge_bootmem_page *m; 1064 int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]); 1065 1066 while (nr_nodes) { 1067 void *addr; 1068 1069 addr = __alloc_bootmem_node_nopanic( 1070 NODE_DATA(hstate_next_node_to_alloc(h, 1071 &node_states[N_HIGH_MEMORY])), 1072 huge_page_size(h), huge_page_size(h), 0); 1073 1074 if (addr) { 1075 /* 1076 * Use the beginning of the huge page to store the 1077 * huge_bootmem_page struct (until gather_bootmem 1078 * puts them into the mem_map). 1079 */ 1080 m = addr; 1081 goto found; 1082 } 1083 nr_nodes--; 1084 } 1085 return 0; 1086 1087 found: 1088 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); 1089 /* Put them into a private list first because mem_map is not up yet */ 1090 list_add(&m->list, &huge_boot_pages); 1091 m->hstate = h; 1092 return 1; 1093 } 1094 1095 static void prep_compound_huge_page(struct page *page, int order) 1096 { 1097 if (unlikely(order > (MAX_ORDER - 1))) 1098 prep_compound_gigantic_page(page, order); 1099 else 1100 prep_compound_page(page, order); 1101 } 1102 1103 /* Put bootmem huge pages into the standard lists after mem_map is up */ 1104 static void __init gather_bootmem_prealloc(void) 1105 { 1106 struct huge_bootmem_page *m; 1107 1108 list_for_each_entry(m, &huge_boot_pages, list) { 1109 struct hstate *h = m->hstate; 1110 struct page *page; 1111 1112 #ifdef CONFIG_HIGHMEM 1113 page = pfn_to_page(m->phys >> PAGE_SHIFT); 1114 free_bootmem_late((unsigned long)m, 1115 sizeof(struct huge_bootmem_page)); 1116 #else 1117 page = virt_to_page(m); 1118 #endif 1119 __ClearPageReserved(page); 1120 WARN_ON(page_count(page) != 1); 1121 prep_compound_huge_page(page, h->order); 1122 prep_new_huge_page(h, page, page_to_nid(page)); 1123 /* 1124 * If we had gigantic hugepages allocated at boot time, we need 1125 * to restore the 'stolen' pages to totalram_pages in order to 1126 * fix confusing memory reports from free(1) and another 1127 * side-effects, like CommitLimit going negative. 1128 */ 1129 if (h->order > (MAX_ORDER - 1)) 1130 totalram_pages += 1 << h->order; 1131 } 1132 } 1133 1134 static void __init hugetlb_hstate_alloc_pages(struct hstate *h) 1135 { 1136 unsigned long i; 1137 1138 for (i = 0; i < h->max_huge_pages; ++i) { 1139 if (h->order >= MAX_ORDER) { 1140 if (!alloc_bootmem_huge_page(h)) 1141 break; 1142 } else if (!alloc_fresh_huge_page(h, 1143 &node_states[N_HIGH_MEMORY])) 1144 break; 1145 } 1146 h->max_huge_pages = i; 1147 } 1148 1149 static void __init hugetlb_init_hstates(void) 1150 { 1151 struct hstate *h; 1152 1153 for_each_hstate(h) { 1154 /* oversize hugepages were init'ed in early boot */ 1155 if (h->order < MAX_ORDER) 1156 hugetlb_hstate_alloc_pages(h); 1157 } 1158 } 1159 1160 static char * __init memfmt(char *buf, unsigned long n) 1161 { 1162 if (n >= (1UL << 30)) 1163 sprintf(buf, "%lu GB", n >> 30); 1164 else if (n >= (1UL << 20)) 1165 sprintf(buf, "%lu MB", n >> 20); 1166 else 1167 sprintf(buf, "%lu KB", n >> 10); 1168 return buf; 1169 } 1170 1171 static void __init report_hugepages(void) 1172 { 1173 struct hstate *h; 1174 1175 for_each_hstate(h) { 1176 char buf[32]; 1177 printk(KERN_INFO "HugeTLB registered %s page size, " 1178 "pre-allocated %ld pages\n", 1179 memfmt(buf, huge_page_size(h)), 1180 h->free_huge_pages); 1181 } 1182 } 1183 1184 #ifdef CONFIG_HIGHMEM 1185 static void try_to_free_low(struct hstate *h, unsigned long count, 1186 nodemask_t *nodes_allowed) 1187 { 1188 int i; 1189 1190 if (h->order >= MAX_ORDER) 1191 return; 1192 1193 for_each_node_mask(i, *nodes_allowed) { 1194 struct page *page, *next; 1195 struct list_head *freel = &h->hugepage_freelists[i]; 1196 list_for_each_entry_safe(page, next, freel, lru) { 1197 if (count >= h->nr_huge_pages) 1198 return; 1199 if (PageHighMem(page)) 1200 continue; 1201 list_del(&page->lru); 1202 update_and_free_page(h, page); 1203 h->free_huge_pages--; 1204 h->free_huge_pages_node[page_to_nid(page)]--; 1205 } 1206 } 1207 } 1208 #else 1209 static inline void try_to_free_low(struct hstate *h, unsigned long count, 1210 nodemask_t *nodes_allowed) 1211 { 1212 } 1213 #endif 1214 1215 /* 1216 * Increment or decrement surplus_huge_pages. Keep node-specific counters 1217 * balanced by operating on them in a round-robin fashion. 1218 * Returns 1 if an adjustment was made. 1219 */ 1220 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, 1221 int delta) 1222 { 1223 int start_nid, next_nid; 1224 int ret = 0; 1225 1226 VM_BUG_ON(delta != -1 && delta != 1); 1227 1228 if (delta < 0) 1229 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 1230 else 1231 start_nid = hstate_next_node_to_free(h, nodes_allowed); 1232 next_nid = start_nid; 1233 1234 do { 1235 int nid = next_nid; 1236 if (delta < 0) { 1237 /* 1238 * To shrink on this node, there must be a surplus page 1239 */ 1240 if (!h->surplus_huge_pages_node[nid]) { 1241 next_nid = hstate_next_node_to_alloc(h, 1242 nodes_allowed); 1243 continue; 1244 } 1245 } 1246 if (delta > 0) { 1247 /* 1248 * Surplus cannot exceed the total number of pages 1249 */ 1250 if (h->surplus_huge_pages_node[nid] >= 1251 h->nr_huge_pages_node[nid]) { 1252 next_nid = hstate_next_node_to_free(h, 1253 nodes_allowed); 1254 continue; 1255 } 1256 } 1257 1258 h->surplus_huge_pages += delta; 1259 h->surplus_huge_pages_node[nid] += delta; 1260 ret = 1; 1261 break; 1262 } while (next_nid != start_nid); 1263 1264 return ret; 1265 } 1266 1267 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) 1268 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, 1269 nodemask_t *nodes_allowed) 1270 { 1271 unsigned long min_count, ret; 1272 1273 if (h->order >= MAX_ORDER) 1274 return h->max_huge_pages; 1275 1276 /* 1277 * Increase the pool size 1278 * First take pages out of surplus state. Then make up the 1279 * remaining difference by allocating fresh huge pages. 1280 * 1281 * We might race with alloc_buddy_huge_page() here and be unable 1282 * to convert a surplus huge page to a normal huge page. That is 1283 * not critical, though, it just means the overall size of the 1284 * pool might be one hugepage larger than it needs to be, but 1285 * within all the constraints specified by the sysctls. 1286 */ 1287 spin_lock(&hugetlb_lock); 1288 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { 1289 if (!adjust_pool_surplus(h, nodes_allowed, -1)) 1290 break; 1291 } 1292 1293 while (count > persistent_huge_pages(h)) { 1294 /* 1295 * If this allocation races such that we no longer need the 1296 * page, free_huge_page will handle it by freeing the page 1297 * and reducing the surplus. 1298 */ 1299 spin_unlock(&hugetlb_lock); 1300 ret = alloc_fresh_huge_page(h, nodes_allowed); 1301 spin_lock(&hugetlb_lock); 1302 if (!ret) 1303 goto out; 1304 1305 /* Bail for signals. Probably ctrl-c from user */ 1306 if (signal_pending(current)) 1307 goto out; 1308 } 1309 1310 /* 1311 * Decrease the pool size 1312 * First return free pages to the buddy allocator (being careful 1313 * to keep enough around to satisfy reservations). Then place 1314 * pages into surplus state as needed so the pool will shrink 1315 * to the desired size as pages become free. 1316 * 1317 * By placing pages into the surplus state independent of the 1318 * overcommit value, we are allowing the surplus pool size to 1319 * exceed overcommit. There are few sane options here. Since 1320 * alloc_buddy_huge_page() is checking the global counter, 1321 * though, we'll note that we're not allowed to exceed surplus 1322 * and won't grow the pool anywhere else. Not until one of the 1323 * sysctls are changed, or the surplus pages go out of use. 1324 */ 1325 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; 1326 min_count = max(count, min_count); 1327 try_to_free_low(h, min_count, nodes_allowed); 1328 while (min_count < persistent_huge_pages(h)) { 1329 if (!free_pool_huge_page(h, nodes_allowed, 0)) 1330 break; 1331 } 1332 while (count < persistent_huge_pages(h)) { 1333 if (!adjust_pool_surplus(h, nodes_allowed, 1)) 1334 break; 1335 } 1336 out: 1337 ret = persistent_huge_pages(h); 1338 spin_unlock(&hugetlb_lock); 1339 return ret; 1340 } 1341 1342 #define HSTATE_ATTR_RO(_name) \ 1343 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 1344 1345 #define HSTATE_ATTR(_name) \ 1346 static struct kobj_attribute _name##_attr = \ 1347 __ATTR(_name, 0644, _name##_show, _name##_store) 1348 1349 static struct kobject *hugepages_kobj; 1350 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1351 1352 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); 1353 1354 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) 1355 { 1356 int i; 1357 1358 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1359 if (hstate_kobjs[i] == kobj) { 1360 if (nidp) 1361 *nidp = NUMA_NO_NODE; 1362 return &hstates[i]; 1363 } 1364 1365 return kobj_to_node_hstate(kobj, nidp); 1366 } 1367 1368 static ssize_t nr_hugepages_show_common(struct kobject *kobj, 1369 struct kobj_attribute *attr, char *buf) 1370 { 1371 struct hstate *h; 1372 unsigned long nr_huge_pages; 1373 int nid; 1374 1375 h = kobj_to_hstate(kobj, &nid); 1376 if (nid == NUMA_NO_NODE) 1377 nr_huge_pages = h->nr_huge_pages; 1378 else 1379 nr_huge_pages = h->nr_huge_pages_node[nid]; 1380 1381 return sprintf(buf, "%lu\n", nr_huge_pages); 1382 } 1383 1384 static ssize_t nr_hugepages_store_common(bool obey_mempolicy, 1385 struct kobject *kobj, struct kobj_attribute *attr, 1386 const char *buf, size_t len) 1387 { 1388 int err; 1389 int nid; 1390 unsigned long count; 1391 struct hstate *h; 1392 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); 1393 1394 err = strict_strtoul(buf, 10, &count); 1395 if (err) 1396 goto out; 1397 1398 h = kobj_to_hstate(kobj, &nid); 1399 if (h->order >= MAX_ORDER) { 1400 err = -EINVAL; 1401 goto out; 1402 } 1403 1404 if (nid == NUMA_NO_NODE) { 1405 /* 1406 * global hstate attribute 1407 */ 1408 if (!(obey_mempolicy && 1409 init_nodemask_of_mempolicy(nodes_allowed))) { 1410 NODEMASK_FREE(nodes_allowed); 1411 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1412 } 1413 } else if (nodes_allowed) { 1414 /* 1415 * per node hstate attribute: adjust count to global, 1416 * but restrict alloc/free to the specified node. 1417 */ 1418 count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; 1419 init_nodemask_of_node(nodes_allowed, nid); 1420 } else 1421 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1422 1423 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); 1424 1425 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1426 NODEMASK_FREE(nodes_allowed); 1427 1428 return len; 1429 out: 1430 NODEMASK_FREE(nodes_allowed); 1431 return err; 1432 } 1433 1434 static ssize_t nr_hugepages_show(struct kobject *kobj, 1435 struct kobj_attribute *attr, char *buf) 1436 { 1437 return nr_hugepages_show_common(kobj, attr, buf); 1438 } 1439 1440 static ssize_t nr_hugepages_store(struct kobject *kobj, 1441 struct kobj_attribute *attr, const char *buf, size_t len) 1442 { 1443 return nr_hugepages_store_common(false, kobj, attr, buf, len); 1444 } 1445 HSTATE_ATTR(nr_hugepages); 1446 1447 #ifdef CONFIG_NUMA 1448 1449 /* 1450 * hstate attribute for optionally mempolicy-based constraint on persistent 1451 * huge page alloc/free. 1452 */ 1453 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, 1454 struct kobj_attribute *attr, char *buf) 1455 { 1456 return nr_hugepages_show_common(kobj, attr, buf); 1457 } 1458 1459 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, 1460 struct kobj_attribute *attr, const char *buf, size_t len) 1461 { 1462 return nr_hugepages_store_common(true, kobj, attr, buf, len); 1463 } 1464 HSTATE_ATTR(nr_hugepages_mempolicy); 1465 #endif 1466 1467 1468 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, 1469 struct kobj_attribute *attr, char *buf) 1470 { 1471 struct hstate *h = kobj_to_hstate(kobj, NULL); 1472 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); 1473 } 1474 1475 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, 1476 struct kobj_attribute *attr, const char *buf, size_t count) 1477 { 1478 int err; 1479 unsigned long input; 1480 struct hstate *h = kobj_to_hstate(kobj, NULL); 1481 1482 if (h->order >= MAX_ORDER) 1483 return -EINVAL; 1484 1485 err = strict_strtoul(buf, 10, &input); 1486 if (err) 1487 return err; 1488 1489 spin_lock(&hugetlb_lock); 1490 h->nr_overcommit_huge_pages = input; 1491 spin_unlock(&hugetlb_lock); 1492 1493 return count; 1494 } 1495 HSTATE_ATTR(nr_overcommit_hugepages); 1496 1497 static ssize_t free_hugepages_show(struct kobject *kobj, 1498 struct kobj_attribute *attr, char *buf) 1499 { 1500 struct hstate *h; 1501 unsigned long free_huge_pages; 1502 int nid; 1503 1504 h = kobj_to_hstate(kobj, &nid); 1505 if (nid == NUMA_NO_NODE) 1506 free_huge_pages = h->free_huge_pages; 1507 else 1508 free_huge_pages = h->free_huge_pages_node[nid]; 1509 1510 return sprintf(buf, "%lu\n", free_huge_pages); 1511 } 1512 HSTATE_ATTR_RO(free_hugepages); 1513 1514 static ssize_t resv_hugepages_show(struct kobject *kobj, 1515 struct kobj_attribute *attr, char *buf) 1516 { 1517 struct hstate *h = kobj_to_hstate(kobj, NULL); 1518 return sprintf(buf, "%lu\n", h->resv_huge_pages); 1519 } 1520 HSTATE_ATTR_RO(resv_hugepages); 1521 1522 static ssize_t surplus_hugepages_show(struct kobject *kobj, 1523 struct kobj_attribute *attr, char *buf) 1524 { 1525 struct hstate *h; 1526 unsigned long surplus_huge_pages; 1527 int nid; 1528 1529 h = kobj_to_hstate(kobj, &nid); 1530 if (nid == NUMA_NO_NODE) 1531 surplus_huge_pages = h->surplus_huge_pages; 1532 else 1533 surplus_huge_pages = h->surplus_huge_pages_node[nid]; 1534 1535 return sprintf(buf, "%lu\n", surplus_huge_pages); 1536 } 1537 HSTATE_ATTR_RO(surplus_hugepages); 1538 1539 static struct attribute *hstate_attrs[] = { 1540 &nr_hugepages_attr.attr, 1541 &nr_overcommit_hugepages_attr.attr, 1542 &free_hugepages_attr.attr, 1543 &resv_hugepages_attr.attr, 1544 &surplus_hugepages_attr.attr, 1545 #ifdef CONFIG_NUMA 1546 &nr_hugepages_mempolicy_attr.attr, 1547 #endif 1548 NULL, 1549 }; 1550 1551 static struct attribute_group hstate_attr_group = { 1552 .attrs = hstate_attrs, 1553 }; 1554 1555 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, 1556 struct kobject **hstate_kobjs, 1557 struct attribute_group *hstate_attr_group) 1558 { 1559 int retval; 1560 int hi = h - hstates; 1561 1562 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); 1563 if (!hstate_kobjs[hi]) 1564 return -ENOMEM; 1565 1566 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); 1567 if (retval) 1568 kobject_put(hstate_kobjs[hi]); 1569 1570 return retval; 1571 } 1572 1573 static void __init hugetlb_sysfs_init(void) 1574 { 1575 struct hstate *h; 1576 int err; 1577 1578 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); 1579 if (!hugepages_kobj) 1580 return; 1581 1582 for_each_hstate(h) { 1583 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, 1584 hstate_kobjs, &hstate_attr_group); 1585 if (err) 1586 printk(KERN_ERR "Hugetlb: Unable to add hstate %s", 1587 h->name); 1588 } 1589 } 1590 1591 #ifdef CONFIG_NUMA 1592 1593 /* 1594 * node_hstate/s - associate per node hstate attributes, via their kobjects, 1595 * with node devices in node_devices[] using a parallel array. The array 1596 * index of a node device or _hstate == node id. 1597 * This is here to avoid any static dependency of the node device driver, in 1598 * the base kernel, on the hugetlb module. 1599 */ 1600 struct node_hstate { 1601 struct kobject *hugepages_kobj; 1602 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1603 }; 1604 struct node_hstate node_hstates[MAX_NUMNODES]; 1605 1606 /* 1607 * A subset of global hstate attributes for node devices 1608 */ 1609 static struct attribute *per_node_hstate_attrs[] = { 1610 &nr_hugepages_attr.attr, 1611 &free_hugepages_attr.attr, 1612 &surplus_hugepages_attr.attr, 1613 NULL, 1614 }; 1615 1616 static struct attribute_group per_node_hstate_attr_group = { 1617 .attrs = per_node_hstate_attrs, 1618 }; 1619 1620 /* 1621 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. 1622 * Returns node id via non-NULL nidp. 1623 */ 1624 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1625 { 1626 int nid; 1627 1628 for (nid = 0; nid < nr_node_ids; nid++) { 1629 struct node_hstate *nhs = &node_hstates[nid]; 1630 int i; 1631 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1632 if (nhs->hstate_kobjs[i] == kobj) { 1633 if (nidp) 1634 *nidp = nid; 1635 return &hstates[i]; 1636 } 1637 } 1638 1639 BUG(); 1640 return NULL; 1641 } 1642 1643 /* 1644 * Unregister hstate attributes from a single node device. 1645 * No-op if no hstate attributes attached. 1646 */ 1647 void hugetlb_unregister_node(struct node *node) 1648 { 1649 struct hstate *h; 1650 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1651 1652 if (!nhs->hugepages_kobj) 1653 return; /* no hstate attributes */ 1654 1655 for_each_hstate(h) 1656 if (nhs->hstate_kobjs[h - hstates]) { 1657 kobject_put(nhs->hstate_kobjs[h - hstates]); 1658 nhs->hstate_kobjs[h - hstates] = NULL; 1659 } 1660 1661 kobject_put(nhs->hugepages_kobj); 1662 nhs->hugepages_kobj = NULL; 1663 } 1664 1665 /* 1666 * hugetlb module exit: unregister hstate attributes from node devices 1667 * that have them. 1668 */ 1669 static void hugetlb_unregister_all_nodes(void) 1670 { 1671 int nid; 1672 1673 /* 1674 * disable node device registrations. 1675 */ 1676 register_hugetlbfs_with_node(NULL, NULL); 1677 1678 /* 1679 * remove hstate attributes from any nodes that have them. 1680 */ 1681 for (nid = 0; nid < nr_node_ids; nid++) 1682 hugetlb_unregister_node(&node_devices[nid]); 1683 } 1684 1685 /* 1686 * Register hstate attributes for a single node device. 1687 * No-op if attributes already registered. 1688 */ 1689 void hugetlb_register_node(struct node *node) 1690 { 1691 struct hstate *h; 1692 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1693 int err; 1694 1695 if (nhs->hugepages_kobj) 1696 return; /* already allocated */ 1697 1698 nhs->hugepages_kobj = kobject_create_and_add("hugepages", 1699 &node->dev.kobj); 1700 if (!nhs->hugepages_kobj) 1701 return; 1702 1703 for_each_hstate(h) { 1704 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, 1705 nhs->hstate_kobjs, 1706 &per_node_hstate_attr_group); 1707 if (err) { 1708 printk(KERN_ERR "Hugetlb: Unable to add hstate %s" 1709 " for node %d\n", 1710 h->name, node->dev.id); 1711 hugetlb_unregister_node(node); 1712 break; 1713 } 1714 } 1715 } 1716 1717 /* 1718 * hugetlb init time: register hstate attributes for all registered node 1719 * devices of nodes that have memory. All on-line nodes should have 1720 * registered their associated device by this time. 1721 */ 1722 static void hugetlb_register_all_nodes(void) 1723 { 1724 int nid; 1725 1726 for_each_node_state(nid, N_HIGH_MEMORY) { 1727 struct node *node = &node_devices[nid]; 1728 if (node->dev.id == nid) 1729 hugetlb_register_node(node); 1730 } 1731 1732 /* 1733 * Let the node device driver know we're here so it can 1734 * [un]register hstate attributes on node hotplug. 1735 */ 1736 register_hugetlbfs_with_node(hugetlb_register_node, 1737 hugetlb_unregister_node); 1738 } 1739 #else /* !CONFIG_NUMA */ 1740 1741 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1742 { 1743 BUG(); 1744 if (nidp) 1745 *nidp = -1; 1746 return NULL; 1747 } 1748 1749 static void hugetlb_unregister_all_nodes(void) { } 1750 1751 static void hugetlb_register_all_nodes(void) { } 1752 1753 #endif 1754 1755 static void __exit hugetlb_exit(void) 1756 { 1757 struct hstate *h; 1758 1759 hugetlb_unregister_all_nodes(); 1760 1761 for_each_hstate(h) { 1762 kobject_put(hstate_kobjs[h - hstates]); 1763 } 1764 1765 kobject_put(hugepages_kobj); 1766 } 1767 module_exit(hugetlb_exit); 1768 1769 static int __init hugetlb_init(void) 1770 { 1771 /* Some platform decide whether they support huge pages at boot 1772 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when 1773 * there is no such support 1774 */ 1775 if (HPAGE_SHIFT == 0) 1776 return 0; 1777 1778 if (!size_to_hstate(default_hstate_size)) { 1779 default_hstate_size = HPAGE_SIZE; 1780 if (!size_to_hstate(default_hstate_size)) 1781 hugetlb_add_hstate(HUGETLB_PAGE_ORDER); 1782 } 1783 default_hstate_idx = size_to_hstate(default_hstate_size) - hstates; 1784 if (default_hstate_max_huge_pages) 1785 default_hstate.max_huge_pages = default_hstate_max_huge_pages; 1786 1787 hugetlb_init_hstates(); 1788 1789 gather_bootmem_prealloc(); 1790 1791 report_hugepages(); 1792 1793 hugetlb_sysfs_init(); 1794 1795 hugetlb_register_all_nodes(); 1796 1797 return 0; 1798 } 1799 module_init(hugetlb_init); 1800 1801 /* Should be called on processing a hugepagesz=... option */ 1802 void __init hugetlb_add_hstate(unsigned order) 1803 { 1804 struct hstate *h; 1805 unsigned long i; 1806 1807 if (size_to_hstate(PAGE_SIZE << order)) { 1808 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n"); 1809 return; 1810 } 1811 BUG_ON(max_hstate >= HUGE_MAX_HSTATE); 1812 BUG_ON(order == 0); 1813 h = &hstates[max_hstate++]; 1814 h->order = order; 1815 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); 1816 h->nr_huge_pages = 0; 1817 h->free_huge_pages = 0; 1818 for (i = 0; i < MAX_NUMNODES; ++i) 1819 INIT_LIST_HEAD(&h->hugepage_freelists[i]); 1820 h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]); 1821 h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]); 1822 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", 1823 huge_page_size(h)/1024); 1824 1825 parsed_hstate = h; 1826 } 1827 1828 static int __init hugetlb_nrpages_setup(char *s) 1829 { 1830 unsigned long *mhp; 1831 static unsigned long *last_mhp; 1832 1833 /* 1834 * !max_hstate means we haven't parsed a hugepagesz= parameter yet, 1835 * so this hugepages= parameter goes to the "default hstate". 1836 */ 1837 if (!max_hstate) 1838 mhp = &default_hstate_max_huge_pages; 1839 else 1840 mhp = &parsed_hstate->max_huge_pages; 1841 1842 if (mhp == last_mhp) { 1843 printk(KERN_WARNING "hugepages= specified twice without " 1844 "interleaving hugepagesz=, ignoring\n"); 1845 return 1; 1846 } 1847 1848 if (sscanf(s, "%lu", mhp) <= 0) 1849 *mhp = 0; 1850 1851 /* 1852 * Global state is always initialized later in hugetlb_init. 1853 * But we need to allocate >= MAX_ORDER hstates here early to still 1854 * use the bootmem allocator. 1855 */ 1856 if (max_hstate && parsed_hstate->order >= MAX_ORDER) 1857 hugetlb_hstate_alloc_pages(parsed_hstate); 1858 1859 last_mhp = mhp; 1860 1861 return 1; 1862 } 1863 __setup("hugepages=", hugetlb_nrpages_setup); 1864 1865 static int __init hugetlb_default_setup(char *s) 1866 { 1867 default_hstate_size = memparse(s, &s); 1868 return 1; 1869 } 1870 __setup("default_hugepagesz=", hugetlb_default_setup); 1871 1872 static unsigned int cpuset_mems_nr(unsigned int *array) 1873 { 1874 int node; 1875 unsigned int nr = 0; 1876 1877 for_each_node_mask(node, cpuset_current_mems_allowed) 1878 nr += array[node]; 1879 1880 return nr; 1881 } 1882 1883 #ifdef CONFIG_SYSCTL 1884 static int hugetlb_sysctl_handler_common(bool obey_mempolicy, 1885 struct ctl_table *table, int write, 1886 void __user *buffer, size_t *length, loff_t *ppos) 1887 { 1888 struct hstate *h = &default_hstate; 1889 unsigned long tmp; 1890 int ret; 1891 1892 tmp = h->max_huge_pages; 1893 1894 if (write && h->order >= MAX_ORDER) 1895 return -EINVAL; 1896 1897 table->data = &tmp; 1898 table->maxlen = sizeof(unsigned long); 1899 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 1900 if (ret) 1901 goto out; 1902 1903 if (write) { 1904 NODEMASK_ALLOC(nodemask_t, nodes_allowed, 1905 GFP_KERNEL | __GFP_NORETRY); 1906 if (!(obey_mempolicy && 1907 init_nodemask_of_mempolicy(nodes_allowed))) { 1908 NODEMASK_FREE(nodes_allowed); 1909 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1910 } 1911 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); 1912 1913 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1914 NODEMASK_FREE(nodes_allowed); 1915 } 1916 out: 1917 return ret; 1918 } 1919 1920 int hugetlb_sysctl_handler(struct ctl_table *table, int write, 1921 void __user *buffer, size_t *length, loff_t *ppos) 1922 { 1923 1924 return hugetlb_sysctl_handler_common(false, table, write, 1925 buffer, length, ppos); 1926 } 1927 1928 #ifdef CONFIG_NUMA 1929 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, 1930 void __user *buffer, size_t *length, loff_t *ppos) 1931 { 1932 return hugetlb_sysctl_handler_common(true, table, write, 1933 buffer, length, ppos); 1934 } 1935 #endif /* CONFIG_NUMA */ 1936 1937 int hugetlb_treat_movable_handler(struct ctl_table *table, int write, 1938 void __user *buffer, 1939 size_t *length, loff_t *ppos) 1940 { 1941 proc_dointvec(table, write, buffer, length, ppos); 1942 if (hugepages_treat_as_movable) 1943 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; 1944 else 1945 htlb_alloc_mask = GFP_HIGHUSER; 1946 return 0; 1947 } 1948 1949 int hugetlb_overcommit_handler(struct ctl_table *table, int write, 1950 void __user *buffer, 1951 size_t *length, loff_t *ppos) 1952 { 1953 struct hstate *h = &default_hstate; 1954 unsigned long tmp; 1955 int ret; 1956 1957 tmp = h->nr_overcommit_huge_pages; 1958 1959 if (write && h->order >= MAX_ORDER) 1960 return -EINVAL; 1961 1962 table->data = &tmp; 1963 table->maxlen = sizeof(unsigned long); 1964 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 1965 if (ret) 1966 goto out; 1967 1968 if (write) { 1969 spin_lock(&hugetlb_lock); 1970 h->nr_overcommit_huge_pages = tmp; 1971 spin_unlock(&hugetlb_lock); 1972 } 1973 out: 1974 return ret; 1975 } 1976 1977 #endif /* CONFIG_SYSCTL */ 1978 1979 void hugetlb_report_meminfo(struct seq_file *m) 1980 { 1981 struct hstate *h = &default_hstate; 1982 seq_printf(m, 1983 "HugePages_Total: %5lu\n" 1984 "HugePages_Free: %5lu\n" 1985 "HugePages_Rsvd: %5lu\n" 1986 "HugePages_Surp: %5lu\n" 1987 "Hugepagesize: %8lu kB\n", 1988 h->nr_huge_pages, 1989 h->free_huge_pages, 1990 h->resv_huge_pages, 1991 h->surplus_huge_pages, 1992 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 1993 } 1994 1995 int hugetlb_report_node_meminfo(int nid, char *buf) 1996 { 1997 struct hstate *h = &default_hstate; 1998 return sprintf(buf, 1999 "Node %d HugePages_Total: %5u\n" 2000 "Node %d HugePages_Free: %5u\n" 2001 "Node %d HugePages_Surp: %5u\n", 2002 nid, h->nr_huge_pages_node[nid], 2003 nid, h->free_huge_pages_node[nid], 2004 nid, h->surplus_huge_pages_node[nid]); 2005 } 2006 2007 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ 2008 unsigned long hugetlb_total_pages(void) 2009 { 2010 struct hstate *h = &default_hstate; 2011 return h->nr_huge_pages * pages_per_huge_page(h); 2012 } 2013 2014 static int hugetlb_acct_memory(struct hstate *h, long delta) 2015 { 2016 int ret = -ENOMEM; 2017 2018 spin_lock(&hugetlb_lock); 2019 /* 2020 * When cpuset is configured, it breaks the strict hugetlb page 2021 * reservation as the accounting is done on a global variable. Such 2022 * reservation is completely rubbish in the presence of cpuset because 2023 * the reservation is not checked against page availability for the 2024 * current cpuset. Application can still potentially OOM'ed by kernel 2025 * with lack of free htlb page in cpuset that the task is in. 2026 * Attempt to enforce strict accounting with cpuset is almost 2027 * impossible (or too ugly) because cpuset is too fluid that 2028 * task or memory node can be dynamically moved between cpusets. 2029 * 2030 * The change of semantics for shared hugetlb mapping with cpuset is 2031 * undesirable. However, in order to preserve some of the semantics, 2032 * we fall back to check against current free page availability as 2033 * a best attempt and hopefully to minimize the impact of changing 2034 * semantics that cpuset has. 2035 */ 2036 if (delta > 0) { 2037 if (gather_surplus_pages(h, delta) < 0) 2038 goto out; 2039 2040 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { 2041 return_unused_surplus_pages(h, delta); 2042 goto out; 2043 } 2044 } 2045 2046 ret = 0; 2047 if (delta < 0) 2048 return_unused_surplus_pages(h, (unsigned long) -delta); 2049 2050 out: 2051 spin_unlock(&hugetlb_lock); 2052 return ret; 2053 } 2054 2055 static void hugetlb_vm_op_open(struct vm_area_struct *vma) 2056 { 2057 struct resv_map *reservations = vma_resv_map(vma); 2058 2059 /* 2060 * This new VMA should share its siblings reservation map if present. 2061 * The VMA will only ever have a valid reservation map pointer where 2062 * it is being copied for another still existing VMA. As that VMA 2063 * has a reference to the reservation map it cannot disappear until 2064 * after this open call completes. It is therefore safe to take a 2065 * new reference here without additional locking. 2066 */ 2067 if (reservations) 2068 kref_get(&reservations->refs); 2069 } 2070 2071 static void hugetlb_vm_op_close(struct vm_area_struct *vma) 2072 { 2073 struct hstate *h = hstate_vma(vma); 2074 struct resv_map *reservations = vma_resv_map(vma); 2075 unsigned long reserve; 2076 unsigned long start; 2077 unsigned long end; 2078 2079 if (reservations) { 2080 start = vma_hugecache_offset(h, vma, vma->vm_start); 2081 end = vma_hugecache_offset(h, vma, vma->vm_end); 2082 2083 reserve = (end - start) - 2084 region_count(&reservations->regions, start, end); 2085 2086 kref_put(&reservations->refs, resv_map_release); 2087 2088 if (reserve) { 2089 hugetlb_acct_memory(h, -reserve); 2090 hugetlb_put_quota(vma->vm_file->f_mapping, reserve); 2091 } 2092 } 2093 } 2094 2095 /* 2096 * We cannot handle pagefaults against hugetlb pages at all. They cause 2097 * handle_mm_fault() to try to instantiate regular-sized pages in the 2098 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get 2099 * this far. 2100 */ 2101 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 2102 { 2103 BUG(); 2104 return 0; 2105 } 2106 2107 const struct vm_operations_struct hugetlb_vm_ops = { 2108 .fault = hugetlb_vm_op_fault, 2109 .open = hugetlb_vm_op_open, 2110 .close = hugetlb_vm_op_close, 2111 }; 2112 2113 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, 2114 int writable) 2115 { 2116 pte_t entry; 2117 2118 if (writable) { 2119 entry = 2120 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); 2121 } else { 2122 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot)); 2123 } 2124 entry = pte_mkyoung(entry); 2125 entry = pte_mkhuge(entry); 2126 2127 return entry; 2128 } 2129 2130 static void set_huge_ptep_writable(struct vm_area_struct *vma, 2131 unsigned long address, pte_t *ptep) 2132 { 2133 pte_t entry; 2134 2135 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep))); 2136 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) 2137 update_mmu_cache(vma, address, ptep); 2138 } 2139 2140 2141 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, 2142 struct vm_area_struct *vma) 2143 { 2144 pte_t *src_pte, *dst_pte, entry; 2145 struct page *ptepage; 2146 unsigned long addr; 2147 int cow; 2148 struct hstate *h = hstate_vma(vma); 2149 unsigned long sz = huge_page_size(h); 2150 2151 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 2152 2153 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { 2154 src_pte = huge_pte_offset(src, addr); 2155 if (!src_pte) 2156 continue; 2157 dst_pte = huge_pte_alloc(dst, addr, sz); 2158 if (!dst_pte) 2159 goto nomem; 2160 2161 /* If the pagetables are shared don't copy or take references */ 2162 if (dst_pte == src_pte) 2163 continue; 2164 2165 spin_lock(&dst->page_table_lock); 2166 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); 2167 if (!huge_pte_none(huge_ptep_get(src_pte))) { 2168 if (cow) 2169 huge_ptep_set_wrprotect(src, addr, src_pte); 2170 entry = huge_ptep_get(src_pte); 2171 ptepage = pte_page(entry); 2172 get_page(ptepage); 2173 page_dup_rmap(ptepage); 2174 set_huge_pte_at(dst, addr, dst_pte, entry); 2175 } 2176 spin_unlock(&src->page_table_lock); 2177 spin_unlock(&dst->page_table_lock); 2178 } 2179 return 0; 2180 2181 nomem: 2182 return -ENOMEM; 2183 } 2184 2185 static int is_hugetlb_entry_migration(pte_t pte) 2186 { 2187 swp_entry_t swp; 2188 2189 if (huge_pte_none(pte) || pte_present(pte)) 2190 return 0; 2191 swp = pte_to_swp_entry(pte); 2192 if (non_swap_entry(swp) && is_migration_entry(swp)) 2193 return 1; 2194 else 2195 return 0; 2196 } 2197 2198 static int is_hugetlb_entry_hwpoisoned(pte_t pte) 2199 { 2200 swp_entry_t swp; 2201 2202 if (huge_pte_none(pte) || pte_present(pte)) 2203 return 0; 2204 swp = pte_to_swp_entry(pte); 2205 if (non_swap_entry(swp) && is_hwpoison_entry(swp)) 2206 return 1; 2207 else 2208 return 0; 2209 } 2210 2211 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2212 unsigned long end, struct page *ref_page) 2213 { 2214 struct mm_struct *mm = vma->vm_mm; 2215 unsigned long address; 2216 pte_t *ptep; 2217 pte_t pte; 2218 struct page *page; 2219 struct page *tmp; 2220 struct hstate *h = hstate_vma(vma); 2221 unsigned long sz = huge_page_size(h); 2222 2223 /* 2224 * A page gathering list, protected by per file i_mmap_mutex. The 2225 * lock is used to avoid list corruption from multiple unmapping 2226 * of the same page since we are using page->lru. 2227 */ 2228 LIST_HEAD(page_list); 2229 2230 WARN_ON(!is_vm_hugetlb_page(vma)); 2231 BUG_ON(start & ~huge_page_mask(h)); 2232 BUG_ON(end & ~huge_page_mask(h)); 2233 2234 mmu_notifier_invalidate_range_start(mm, start, end); 2235 spin_lock(&mm->page_table_lock); 2236 for (address = start; address < end; address += sz) { 2237 ptep = huge_pte_offset(mm, address); 2238 if (!ptep) 2239 continue; 2240 2241 if (huge_pmd_unshare(mm, &address, ptep)) 2242 continue; 2243 2244 /* 2245 * If a reference page is supplied, it is because a specific 2246 * page is being unmapped, not a range. Ensure the page we 2247 * are about to unmap is the actual page of interest. 2248 */ 2249 if (ref_page) { 2250 pte = huge_ptep_get(ptep); 2251 if (huge_pte_none(pte)) 2252 continue; 2253 page = pte_page(pte); 2254 if (page != ref_page) 2255 continue; 2256 2257 /* 2258 * Mark the VMA as having unmapped its page so that 2259 * future faults in this VMA will fail rather than 2260 * looking like data was lost 2261 */ 2262 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); 2263 } 2264 2265 pte = huge_ptep_get_and_clear(mm, address, ptep); 2266 if (huge_pte_none(pte)) 2267 continue; 2268 2269 /* 2270 * HWPoisoned hugepage is already unmapped and dropped reference 2271 */ 2272 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) 2273 continue; 2274 2275 page = pte_page(pte); 2276 if (pte_dirty(pte)) 2277 set_page_dirty(page); 2278 list_add(&page->lru, &page_list); 2279 } 2280 spin_unlock(&mm->page_table_lock); 2281 flush_tlb_range(vma, start, end); 2282 mmu_notifier_invalidate_range_end(mm, start, end); 2283 list_for_each_entry_safe(page, tmp, &page_list, lru) { 2284 page_remove_rmap(page); 2285 list_del(&page->lru); 2286 put_page(page); 2287 } 2288 } 2289 2290 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2291 unsigned long end, struct page *ref_page) 2292 { 2293 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 2294 __unmap_hugepage_range(vma, start, end, ref_page); 2295 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 2296 } 2297 2298 /* 2299 * This is called when the original mapper is failing to COW a MAP_PRIVATE 2300 * mappping it owns the reserve page for. The intention is to unmap the page 2301 * from other VMAs and let the children be SIGKILLed if they are faulting the 2302 * same region. 2303 */ 2304 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, 2305 struct page *page, unsigned long address) 2306 { 2307 struct hstate *h = hstate_vma(vma); 2308 struct vm_area_struct *iter_vma; 2309 struct address_space *mapping; 2310 struct prio_tree_iter iter; 2311 pgoff_t pgoff; 2312 2313 /* 2314 * vm_pgoff is in PAGE_SIZE units, hence the different calculation 2315 * from page cache lookup which is in HPAGE_SIZE units. 2316 */ 2317 address = address & huge_page_mask(h); 2318 pgoff = vma_hugecache_offset(h, vma, address); 2319 mapping = (struct address_space *)page_private(page); 2320 2321 /* 2322 * Take the mapping lock for the duration of the table walk. As 2323 * this mapping should be shared between all the VMAs, 2324 * __unmap_hugepage_range() is called as the lock is already held 2325 */ 2326 mutex_lock(&mapping->i_mmap_mutex); 2327 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 2328 /* Do not unmap the current VMA */ 2329 if (iter_vma == vma) 2330 continue; 2331 2332 /* 2333 * Unmap the page from other VMAs without their own reserves. 2334 * They get marked to be SIGKILLed if they fault in these 2335 * areas. This is because a future no-page fault on this VMA 2336 * could insert a zeroed page instead of the data existing 2337 * from the time of fork. This would look like data corruption 2338 */ 2339 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2340 __unmap_hugepage_range(iter_vma, 2341 address, address + huge_page_size(h), 2342 page); 2343 } 2344 mutex_unlock(&mapping->i_mmap_mutex); 2345 2346 return 1; 2347 } 2348 2349 /* 2350 * Hugetlb_cow() should be called with page lock of the original hugepage held. 2351 * Called with hugetlb_instantiation_mutex held and pte_page locked so we 2352 * cannot race with other handlers or page migration. 2353 * Keep the pte_same checks anyway to make transition from the mutex easier. 2354 */ 2355 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, 2356 unsigned long address, pte_t *ptep, pte_t pte, 2357 struct page *pagecache_page) 2358 { 2359 struct hstate *h = hstate_vma(vma); 2360 struct page *old_page, *new_page; 2361 int avoidcopy; 2362 int outside_reserve = 0; 2363 2364 old_page = pte_page(pte); 2365 2366 retry_avoidcopy: 2367 /* If no-one else is actually using this page, avoid the copy 2368 * and just make the page writable */ 2369 avoidcopy = (page_mapcount(old_page) == 1); 2370 if (avoidcopy) { 2371 if (PageAnon(old_page)) 2372 page_move_anon_rmap(old_page, vma, address); 2373 set_huge_ptep_writable(vma, address, ptep); 2374 return 0; 2375 } 2376 2377 /* 2378 * If the process that created a MAP_PRIVATE mapping is about to 2379 * perform a COW due to a shared page count, attempt to satisfy 2380 * the allocation without using the existing reserves. The pagecache 2381 * page is used to determine if the reserve at this address was 2382 * consumed or not. If reserves were used, a partial faulted mapping 2383 * at the time of fork() could consume its reserves on COW instead 2384 * of the full address range. 2385 */ 2386 if (!(vma->vm_flags & VM_MAYSHARE) && 2387 is_vma_resv_set(vma, HPAGE_RESV_OWNER) && 2388 old_page != pagecache_page) 2389 outside_reserve = 1; 2390 2391 page_cache_get(old_page); 2392 2393 /* Drop page_table_lock as buddy allocator may be called */ 2394 spin_unlock(&mm->page_table_lock); 2395 new_page = alloc_huge_page(vma, address, outside_reserve); 2396 2397 if (IS_ERR(new_page)) { 2398 page_cache_release(old_page); 2399 2400 /* 2401 * If a process owning a MAP_PRIVATE mapping fails to COW, 2402 * it is due to references held by a child and an insufficient 2403 * huge page pool. To guarantee the original mappers 2404 * reliability, unmap the page from child processes. The child 2405 * may get SIGKILLed if it later faults. 2406 */ 2407 if (outside_reserve) { 2408 BUG_ON(huge_pte_none(pte)); 2409 if (unmap_ref_private(mm, vma, old_page, address)) { 2410 BUG_ON(page_count(old_page) != 1); 2411 BUG_ON(huge_pte_none(pte)); 2412 spin_lock(&mm->page_table_lock); 2413 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2414 if (likely(pte_same(huge_ptep_get(ptep), pte))) 2415 goto retry_avoidcopy; 2416 /* 2417 * race occurs while re-acquiring page_table_lock, and 2418 * our job is done. 2419 */ 2420 return 0; 2421 } 2422 WARN_ON_ONCE(1); 2423 } 2424 2425 /* Caller expects lock to be held */ 2426 spin_lock(&mm->page_table_lock); 2427 return -PTR_ERR(new_page); 2428 } 2429 2430 /* 2431 * When the original hugepage is shared one, it does not have 2432 * anon_vma prepared. 2433 */ 2434 if (unlikely(anon_vma_prepare(vma))) { 2435 page_cache_release(new_page); 2436 page_cache_release(old_page); 2437 /* Caller expects lock to be held */ 2438 spin_lock(&mm->page_table_lock); 2439 return VM_FAULT_OOM; 2440 } 2441 2442 copy_user_huge_page(new_page, old_page, address, vma, 2443 pages_per_huge_page(h)); 2444 __SetPageUptodate(new_page); 2445 2446 /* 2447 * Retake the page_table_lock to check for racing updates 2448 * before the page tables are altered 2449 */ 2450 spin_lock(&mm->page_table_lock); 2451 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2452 if (likely(pte_same(huge_ptep_get(ptep), pte))) { 2453 /* Break COW */ 2454 mmu_notifier_invalidate_range_start(mm, 2455 address & huge_page_mask(h), 2456 (address & huge_page_mask(h)) + huge_page_size(h)); 2457 huge_ptep_clear_flush(vma, address, ptep); 2458 set_huge_pte_at(mm, address, ptep, 2459 make_huge_pte(vma, new_page, 1)); 2460 page_remove_rmap(old_page); 2461 hugepage_add_new_anon_rmap(new_page, vma, address); 2462 /* Make the old page be freed below */ 2463 new_page = old_page; 2464 mmu_notifier_invalidate_range_end(mm, 2465 address & huge_page_mask(h), 2466 (address & huge_page_mask(h)) + huge_page_size(h)); 2467 } 2468 page_cache_release(new_page); 2469 page_cache_release(old_page); 2470 return 0; 2471 } 2472 2473 /* Return the pagecache page at a given address within a VMA */ 2474 static struct page *hugetlbfs_pagecache_page(struct hstate *h, 2475 struct vm_area_struct *vma, unsigned long address) 2476 { 2477 struct address_space *mapping; 2478 pgoff_t idx; 2479 2480 mapping = vma->vm_file->f_mapping; 2481 idx = vma_hugecache_offset(h, vma, address); 2482 2483 return find_lock_page(mapping, idx); 2484 } 2485 2486 /* 2487 * Return whether there is a pagecache page to back given address within VMA. 2488 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. 2489 */ 2490 static bool hugetlbfs_pagecache_present(struct hstate *h, 2491 struct vm_area_struct *vma, unsigned long address) 2492 { 2493 struct address_space *mapping; 2494 pgoff_t idx; 2495 struct page *page; 2496 2497 mapping = vma->vm_file->f_mapping; 2498 idx = vma_hugecache_offset(h, vma, address); 2499 2500 page = find_get_page(mapping, idx); 2501 if (page) 2502 put_page(page); 2503 return page != NULL; 2504 } 2505 2506 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2507 unsigned long address, pte_t *ptep, unsigned int flags) 2508 { 2509 struct hstate *h = hstate_vma(vma); 2510 int ret = VM_FAULT_SIGBUS; 2511 int anon_rmap = 0; 2512 pgoff_t idx; 2513 unsigned long size; 2514 struct page *page; 2515 struct address_space *mapping; 2516 pte_t new_pte; 2517 2518 /* 2519 * Currently, we are forced to kill the process in the event the 2520 * original mapper has unmapped pages from the child due to a failed 2521 * COW. Warn that such a situation has occurred as it may not be obvious 2522 */ 2523 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { 2524 printk(KERN_WARNING 2525 "PID %d killed due to inadequate hugepage pool\n", 2526 current->pid); 2527 return ret; 2528 } 2529 2530 mapping = vma->vm_file->f_mapping; 2531 idx = vma_hugecache_offset(h, vma, address); 2532 2533 /* 2534 * Use page lock to guard against racing truncation 2535 * before we get page_table_lock. 2536 */ 2537 retry: 2538 page = find_lock_page(mapping, idx); 2539 if (!page) { 2540 size = i_size_read(mapping->host) >> huge_page_shift(h); 2541 if (idx >= size) 2542 goto out; 2543 page = alloc_huge_page(vma, address, 0); 2544 if (IS_ERR(page)) { 2545 ret = -PTR_ERR(page); 2546 goto out; 2547 } 2548 clear_huge_page(page, address, pages_per_huge_page(h)); 2549 __SetPageUptodate(page); 2550 2551 if (vma->vm_flags & VM_MAYSHARE) { 2552 int err; 2553 struct inode *inode = mapping->host; 2554 2555 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); 2556 if (err) { 2557 put_page(page); 2558 if (err == -EEXIST) 2559 goto retry; 2560 goto out; 2561 } 2562 2563 spin_lock(&inode->i_lock); 2564 inode->i_blocks += blocks_per_huge_page(h); 2565 spin_unlock(&inode->i_lock); 2566 } else { 2567 lock_page(page); 2568 if (unlikely(anon_vma_prepare(vma))) { 2569 ret = VM_FAULT_OOM; 2570 goto backout_unlocked; 2571 } 2572 anon_rmap = 1; 2573 } 2574 } else { 2575 /* 2576 * If memory error occurs between mmap() and fault, some process 2577 * don't have hwpoisoned swap entry for errored virtual address. 2578 * So we need to block hugepage fault by PG_hwpoison bit check. 2579 */ 2580 if (unlikely(PageHWPoison(page))) { 2581 ret = VM_FAULT_HWPOISON | 2582 VM_FAULT_SET_HINDEX(h - hstates); 2583 goto backout_unlocked; 2584 } 2585 } 2586 2587 /* 2588 * If we are going to COW a private mapping later, we examine the 2589 * pending reservations for this page now. This will ensure that 2590 * any allocations necessary to record that reservation occur outside 2591 * the spinlock. 2592 */ 2593 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 2594 if (vma_needs_reservation(h, vma, address) < 0) { 2595 ret = VM_FAULT_OOM; 2596 goto backout_unlocked; 2597 } 2598 2599 spin_lock(&mm->page_table_lock); 2600 size = i_size_read(mapping->host) >> huge_page_shift(h); 2601 if (idx >= size) 2602 goto backout; 2603 2604 ret = 0; 2605 if (!huge_pte_none(huge_ptep_get(ptep))) 2606 goto backout; 2607 2608 if (anon_rmap) 2609 hugepage_add_new_anon_rmap(page, vma, address); 2610 else 2611 page_dup_rmap(page); 2612 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) 2613 && (vma->vm_flags & VM_SHARED))); 2614 set_huge_pte_at(mm, address, ptep, new_pte); 2615 2616 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 2617 /* Optimization, do the COW without a second fault */ 2618 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); 2619 } 2620 2621 spin_unlock(&mm->page_table_lock); 2622 unlock_page(page); 2623 out: 2624 return ret; 2625 2626 backout: 2627 spin_unlock(&mm->page_table_lock); 2628 backout_unlocked: 2629 unlock_page(page); 2630 put_page(page); 2631 goto out; 2632 } 2633 2634 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2635 unsigned long address, unsigned int flags) 2636 { 2637 pte_t *ptep; 2638 pte_t entry; 2639 int ret; 2640 struct page *page = NULL; 2641 struct page *pagecache_page = NULL; 2642 static DEFINE_MUTEX(hugetlb_instantiation_mutex); 2643 struct hstate *h = hstate_vma(vma); 2644 2645 address &= huge_page_mask(h); 2646 2647 ptep = huge_pte_offset(mm, address); 2648 if (ptep) { 2649 entry = huge_ptep_get(ptep); 2650 if (unlikely(is_hugetlb_entry_migration(entry))) { 2651 migration_entry_wait(mm, (pmd_t *)ptep, address); 2652 return 0; 2653 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) 2654 return VM_FAULT_HWPOISON_LARGE | 2655 VM_FAULT_SET_HINDEX(h - hstates); 2656 } 2657 2658 ptep = huge_pte_alloc(mm, address, huge_page_size(h)); 2659 if (!ptep) 2660 return VM_FAULT_OOM; 2661 2662 /* 2663 * Serialize hugepage allocation and instantiation, so that we don't 2664 * get spurious allocation failures if two CPUs race to instantiate 2665 * the same page in the page cache. 2666 */ 2667 mutex_lock(&hugetlb_instantiation_mutex); 2668 entry = huge_ptep_get(ptep); 2669 if (huge_pte_none(entry)) { 2670 ret = hugetlb_no_page(mm, vma, address, ptep, flags); 2671 goto out_mutex; 2672 } 2673 2674 ret = 0; 2675 2676 /* 2677 * If we are going to COW the mapping later, we examine the pending 2678 * reservations for this page now. This will ensure that any 2679 * allocations necessary to record that reservation occur outside the 2680 * spinlock. For private mappings, we also lookup the pagecache 2681 * page now as it is used to determine if a reservation has been 2682 * consumed. 2683 */ 2684 if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) { 2685 if (vma_needs_reservation(h, vma, address) < 0) { 2686 ret = VM_FAULT_OOM; 2687 goto out_mutex; 2688 } 2689 2690 if (!(vma->vm_flags & VM_MAYSHARE)) 2691 pagecache_page = hugetlbfs_pagecache_page(h, 2692 vma, address); 2693 } 2694 2695 /* 2696 * hugetlb_cow() requires page locks of pte_page(entry) and 2697 * pagecache_page, so here we need take the former one 2698 * when page != pagecache_page or !pagecache_page. 2699 * Note that locking order is always pagecache_page -> page, 2700 * so no worry about deadlock. 2701 */ 2702 page = pte_page(entry); 2703 if (page != pagecache_page) 2704 lock_page(page); 2705 2706 spin_lock(&mm->page_table_lock); 2707 /* Check for a racing update before calling hugetlb_cow */ 2708 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 2709 goto out_page_table_lock; 2710 2711 2712 if (flags & FAULT_FLAG_WRITE) { 2713 if (!pte_write(entry)) { 2714 ret = hugetlb_cow(mm, vma, address, ptep, entry, 2715 pagecache_page); 2716 goto out_page_table_lock; 2717 } 2718 entry = pte_mkdirty(entry); 2719 } 2720 entry = pte_mkyoung(entry); 2721 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 2722 flags & FAULT_FLAG_WRITE)) 2723 update_mmu_cache(vma, address, ptep); 2724 2725 out_page_table_lock: 2726 spin_unlock(&mm->page_table_lock); 2727 2728 if (pagecache_page) { 2729 unlock_page(pagecache_page); 2730 put_page(pagecache_page); 2731 } 2732 if (page != pagecache_page) 2733 unlock_page(page); 2734 2735 out_mutex: 2736 mutex_unlock(&hugetlb_instantiation_mutex); 2737 2738 return ret; 2739 } 2740 2741 /* Can be overriden by architectures */ 2742 __attribute__((weak)) struct page * 2743 follow_huge_pud(struct mm_struct *mm, unsigned long address, 2744 pud_t *pud, int write) 2745 { 2746 BUG(); 2747 return NULL; 2748 } 2749 2750 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 2751 struct page **pages, struct vm_area_struct **vmas, 2752 unsigned long *position, int *length, int i, 2753 unsigned int flags) 2754 { 2755 unsigned long pfn_offset; 2756 unsigned long vaddr = *position; 2757 int remainder = *length; 2758 struct hstate *h = hstate_vma(vma); 2759 2760 spin_lock(&mm->page_table_lock); 2761 while (vaddr < vma->vm_end && remainder) { 2762 pte_t *pte; 2763 int absent; 2764 struct page *page; 2765 2766 /* 2767 * Some archs (sparc64, sh*) have multiple pte_ts to 2768 * each hugepage. We have to make sure we get the 2769 * first, for the page indexing below to work. 2770 */ 2771 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); 2772 absent = !pte || huge_pte_none(huge_ptep_get(pte)); 2773 2774 /* 2775 * When coredumping, it suits get_dump_page if we just return 2776 * an error where there's an empty slot with no huge pagecache 2777 * to back it. This way, we avoid allocating a hugepage, and 2778 * the sparse dumpfile avoids allocating disk blocks, but its 2779 * huge holes still show up with zeroes where they need to be. 2780 */ 2781 if (absent && (flags & FOLL_DUMP) && 2782 !hugetlbfs_pagecache_present(h, vma, vaddr)) { 2783 remainder = 0; 2784 break; 2785 } 2786 2787 if (absent || 2788 ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { 2789 int ret; 2790 2791 spin_unlock(&mm->page_table_lock); 2792 ret = hugetlb_fault(mm, vma, vaddr, 2793 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); 2794 spin_lock(&mm->page_table_lock); 2795 if (!(ret & VM_FAULT_ERROR)) 2796 continue; 2797 2798 remainder = 0; 2799 break; 2800 } 2801 2802 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; 2803 page = pte_page(huge_ptep_get(pte)); 2804 same_page: 2805 if (pages) { 2806 pages[i] = mem_map_offset(page, pfn_offset); 2807 get_page(pages[i]); 2808 } 2809 2810 if (vmas) 2811 vmas[i] = vma; 2812 2813 vaddr += PAGE_SIZE; 2814 ++pfn_offset; 2815 --remainder; 2816 ++i; 2817 if (vaddr < vma->vm_end && remainder && 2818 pfn_offset < pages_per_huge_page(h)) { 2819 /* 2820 * We use pfn_offset to avoid touching the pageframes 2821 * of this compound page. 2822 */ 2823 goto same_page; 2824 } 2825 } 2826 spin_unlock(&mm->page_table_lock); 2827 *length = remainder; 2828 *position = vaddr; 2829 2830 return i ? i : -EFAULT; 2831 } 2832 2833 void hugetlb_change_protection(struct vm_area_struct *vma, 2834 unsigned long address, unsigned long end, pgprot_t newprot) 2835 { 2836 struct mm_struct *mm = vma->vm_mm; 2837 unsigned long start = address; 2838 pte_t *ptep; 2839 pte_t pte; 2840 struct hstate *h = hstate_vma(vma); 2841 2842 BUG_ON(address >= end); 2843 flush_cache_range(vma, address, end); 2844 2845 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 2846 spin_lock(&mm->page_table_lock); 2847 for (; address < end; address += huge_page_size(h)) { 2848 ptep = huge_pte_offset(mm, address); 2849 if (!ptep) 2850 continue; 2851 if (huge_pmd_unshare(mm, &address, ptep)) 2852 continue; 2853 if (!huge_pte_none(huge_ptep_get(ptep))) { 2854 pte = huge_ptep_get_and_clear(mm, address, ptep); 2855 pte = pte_mkhuge(pte_modify(pte, newprot)); 2856 set_huge_pte_at(mm, address, ptep, pte); 2857 } 2858 } 2859 spin_unlock(&mm->page_table_lock); 2860 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 2861 2862 flush_tlb_range(vma, start, end); 2863 } 2864 2865 int hugetlb_reserve_pages(struct inode *inode, 2866 long from, long to, 2867 struct vm_area_struct *vma, 2868 vm_flags_t vm_flags) 2869 { 2870 long ret, chg; 2871 struct hstate *h = hstate_inode(inode); 2872 2873 /* 2874 * Only apply hugepage reservation if asked. At fault time, an 2875 * attempt will be made for VM_NORESERVE to allocate a page 2876 * and filesystem quota without using reserves 2877 */ 2878 if (vm_flags & VM_NORESERVE) 2879 return 0; 2880 2881 /* 2882 * Shared mappings base their reservation on the number of pages that 2883 * are already allocated on behalf of the file. Private mappings need 2884 * to reserve the full area even if read-only as mprotect() may be 2885 * called to make the mapping read-write. Assume !vma is a shm mapping 2886 */ 2887 if (!vma || vma->vm_flags & VM_MAYSHARE) 2888 chg = region_chg(&inode->i_mapping->private_list, from, to); 2889 else { 2890 struct resv_map *resv_map = resv_map_alloc(); 2891 if (!resv_map) 2892 return -ENOMEM; 2893 2894 chg = to - from; 2895 2896 set_vma_resv_map(vma, resv_map); 2897 set_vma_resv_flags(vma, HPAGE_RESV_OWNER); 2898 } 2899 2900 if (chg < 0) 2901 return chg; 2902 2903 /* There must be enough filesystem quota for the mapping */ 2904 if (hugetlb_get_quota(inode->i_mapping, chg)) 2905 return -ENOSPC; 2906 2907 /* 2908 * Check enough hugepages are available for the reservation. 2909 * Hand back the quota if there are not 2910 */ 2911 ret = hugetlb_acct_memory(h, chg); 2912 if (ret < 0) { 2913 hugetlb_put_quota(inode->i_mapping, chg); 2914 return ret; 2915 } 2916 2917 /* 2918 * Account for the reservations made. Shared mappings record regions 2919 * that have reservations as they are shared by multiple VMAs. 2920 * When the last VMA disappears, the region map says how much 2921 * the reservation was and the page cache tells how much of 2922 * the reservation was consumed. Private mappings are per-VMA and 2923 * only the consumed reservations are tracked. When the VMA 2924 * disappears, the original reservation is the VMA size and the 2925 * consumed reservations are stored in the map. Hence, nothing 2926 * else has to be done for private mappings here 2927 */ 2928 if (!vma || vma->vm_flags & VM_MAYSHARE) 2929 region_add(&inode->i_mapping->private_list, from, to); 2930 return 0; 2931 } 2932 2933 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) 2934 { 2935 struct hstate *h = hstate_inode(inode); 2936 long chg = region_truncate(&inode->i_mapping->private_list, offset); 2937 2938 spin_lock(&inode->i_lock); 2939 inode->i_blocks -= (blocks_per_huge_page(h) * freed); 2940 spin_unlock(&inode->i_lock); 2941 2942 hugetlb_put_quota(inode->i_mapping, (chg - freed)); 2943 hugetlb_acct_memory(h, -(chg - freed)); 2944 } 2945 2946 #ifdef CONFIG_MEMORY_FAILURE 2947 2948 /* Should be called in hugetlb_lock */ 2949 static int is_hugepage_on_freelist(struct page *hpage) 2950 { 2951 struct page *page; 2952 struct page *tmp; 2953 struct hstate *h = page_hstate(hpage); 2954 int nid = page_to_nid(hpage); 2955 2956 list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) 2957 if (page == hpage) 2958 return 1; 2959 return 0; 2960 } 2961 2962 /* 2963 * This function is called from memory failure code. 2964 * Assume the caller holds page lock of the head page. 2965 */ 2966 int dequeue_hwpoisoned_huge_page(struct page *hpage) 2967 { 2968 struct hstate *h = page_hstate(hpage); 2969 int nid = page_to_nid(hpage); 2970 int ret = -EBUSY; 2971 2972 spin_lock(&hugetlb_lock); 2973 if (is_hugepage_on_freelist(hpage)) { 2974 list_del(&hpage->lru); 2975 set_page_refcounted(hpage); 2976 h->free_huge_pages--; 2977 h->free_huge_pages_node[nid]--; 2978 ret = 0; 2979 } 2980 spin_unlock(&hugetlb_lock); 2981 return ret; 2982 } 2983 #endif 2984