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