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