hugetlb.c revision b76c8cfbff94263fdf2f408e94b78b049c24a9dc
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 <linux/node.h> 28#include "internal.h" 29 30const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; 31static gfp_t htlb_alloc_mask = GFP_HIGHUSER; 32unsigned long hugepages_treat_as_movable; 33 34static int max_hstate; 35unsigned int default_hstate_idx; 36struct hstate hstates[HUGE_MAX_HSTATE]; 37 38__initdata LIST_HEAD(huge_boot_pages); 39 40/* for command line parsing */ 41static struct hstate * __initdata parsed_hstate; 42static unsigned long __initdata default_hstate_max_huge_pages; 43static unsigned long __initdata default_hstate_size; 44 45#define for_each_hstate(h) \ 46 for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++) 47 48/* 49 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages 50 */ 51static DEFINE_SPINLOCK(hugetlb_lock); 52 53/* 54 * Region tracking -- allows tracking of reservations and instantiated pages 55 * across the pages in a mapping. 56 * 57 * The region data structures are protected by a combination of the mmap_sem 58 * and the hugetlb_instantion_mutex. To access or modify a region the caller 59 * must either hold the mmap_sem for write, or the mmap_sem for read and 60 * the hugetlb_instantiation mutex: 61 * 62 * down_write(&mm->mmap_sem); 63 * or 64 * down_read(&mm->mmap_sem); 65 * mutex_lock(&hugetlb_instantiation_mutex); 66 */ 67struct file_region { 68 struct list_head link; 69 long from; 70 long to; 71}; 72 73static long region_add(struct list_head *head, long f, long t) 74{ 75 struct file_region *rg, *nrg, *trg; 76 77 /* Locate the region we are either in or before. */ 78 list_for_each_entry(rg, head, link) 79 if (f <= rg->to) 80 break; 81 82 /* Round our left edge to the current segment if it encloses us. */ 83 if (f > rg->from) 84 f = rg->from; 85 86 /* Check for and consume any regions we now overlap with. */ 87 nrg = rg; 88 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 89 if (&rg->link == head) 90 break; 91 if (rg->from > t) 92 break; 93 94 /* If this area reaches higher then extend our area to 95 * include it completely. If this is not the first area 96 * which we intend to reuse, free it. */ 97 if (rg->to > t) 98 t = rg->to; 99 if (rg != nrg) { 100 list_del(&rg->link); 101 kfree(rg); 102 } 103 } 104 nrg->from = f; 105 nrg->to = t; 106 return 0; 107} 108 109static long region_chg(struct list_head *head, long f, long t) 110{ 111 struct file_region *rg, *nrg; 112 long chg = 0; 113 114 /* Locate the region we are before or in. */ 115 list_for_each_entry(rg, head, link) 116 if (f <= rg->to) 117 break; 118 119 /* If we are below the current region then a new region is required. 120 * Subtle, allocate a new region at the position but make it zero 121 * size such that we can guarantee to record the reservation. */ 122 if (&rg->link == head || t < rg->from) { 123 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); 124 if (!nrg) 125 return -ENOMEM; 126 nrg->from = f; 127 nrg->to = f; 128 INIT_LIST_HEAD(&nrg->link); 129 list_add(&nrg->link, rg->link.prev); 130 131 return t - f; 132 } 133 134 /* Round our left edge to the current segment if it encloses us. */ 135 if (f > rg->from) 136 f = rg->from; 137 chg = t - f; 138 139 /* Check for and consume any regions we now overlap with. */ 140 list_for_each_entry(rg, rg->link.prev, link) { 141 if (&rg->link == head) 142 break; 143 if (rg->from > t) 144 return chg; 145 146 /* We overlap with this area, if it extends futher than 147 * us then we must extend ourselves. Account for its 148 * existing reservation. */ 149 if (rg->to > t) { 150 chg += rg->to - t; 151 t = rg->to; 152 } 153 chg -= rg->to - rg->from; 154 } 155 return chg; 156} 157 158static long region_truncate(struct list_head *head, long end) 159{ 160 struct file_region *rg, *trg; 161 long chg = 0; 162 163 /* Locate the region we are either in or before. */ 164 list_for_each_entry(rg, head, link) 165 if (end <= rg->to) 166 break; 167 if (&rg->link == head) 168 return 0; 169 170 /* If we are in the middle of a region then adjust it. */ 171 if (end > rg->from) { 172 chg = rg->to - end; 173 rg->to = end; 174 rg = list_entry(rg->link.next, typeof(*rg), link); 175 } 176 177 /* Drop any remaining regions. */ 178 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 179 if (&rg->link == head) 180 break; 181 chg += rg->to - rg->from; 182 list_del(&rg->link); 183 kfree(rg); 184 } 185 return chg; 186} 187 188static long region_count(struct list_head *head, long f, long t) 189{ 190 struct file_region *rg; 191 long chg = 0; 192 193 /* Locate each segment we overlap with, and count that overlap. */ 194 list_for_each_entry(rg, head, link) { 195 int seg_from; 196 int seg_to; 197 198 if (rg->to <= f) 199 continue; 200 if (rg->from >= t) 201 break; 202 203 seg_from = max(rg->from, f); 204 seg_to = min(rg->to, t); 205 206 chg += seg_to - seg_from; 207 } 208 209 return chg; 210} 211 212/* 213 * Convert the address within this vma to the page offset within 214 * the mapping, in pagecache page units; huge pages here. 215 */ 216static pgoff_t vma_hugecache_offset(struct hstate *h, 217 struct vm_area_struct *vma, unsigned long address) 218{ 219 return ((address - vma->vm_start) >> huge_page_shift(h)) + 220 (vma->vm_pgoff >> huge_page_order(h)); 221} 222 223/* 224 * Return the size of the pages allocated when backing a VMA. In the majority 225 * cases this will be same size as used by the page table entries. 226 */ 227unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) 228{ 229 struct hstate *hstate; 230 231 if (!is_vm_hugetlb_page(vma)) 232 return PAGE_SIZE; 233 234 hstate = hstate_vma(vma); 235 236 return 1UL << (hstate->order + PAGE_SHIFT); 237} 238EXPORT_SYMBOL_GPL(vma_kernel_pagesize); 239 240/* 241 * Return the page size being used by the MMU to back a VMA. In the majority 242 * of cases, the page size used by the kernel matches the MMU size. On 243 * architectures where it differs, an architecture-specific version of this 244 * function is required. 245 */ 246#ifndef vma_mmu_pagesize 247unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) 248{ 249 return vma_kernel_pagesize(vma); 250} 251#endif 252 253/* 254 * Flags for MAP_PRIVATE reservations. These are stored in the bottom 255 * bits of the reservation map pointer, which are always clear due to 256 * alignment. 257 */ 258#define HPAGE_RESV_OWNER (1UL << 0) 259#define HPAGE_RESV_UNMAPPED (1UL << 1) 260#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) 261 262/* 263 * These helpers are used to track how many pages are reserved for 264 * faults in a MAP_PRIVATE mapping. Only the process that called mmap() 265 * is guaranteed to have their future faults succeed. 266 * 267 * With the exception of reset_vma_resv_huge_pages() which is called at fork(), 268 * the reserve counters are updated with the hugetlb_lock held. It is safe 269 * to reset the VMA at fork() time as it is not in use yet and there is no 270 * chance of the global counters getting corrupted as a result of the values. 271 * 272 * The private mapping reservation is represented in a subtly different 273 * manner to a shared mapping. A shared mapping has a region map associated 274 * with the underlying file, this region map represents the backing file 275 * pages which have ever had a reservation assigned which this persists even 276 * after the page is instantiated. A private mapping has a region map 277 * associated with the original mmap which is attached to all VMAs which 278 * reference it, this region map represents those offsets which have consumed 279 * reservation ie. where pages have been instantiated. 280 */ 281static unsigned long get_vma_private_data(struct vm_area_struct *vma) 282{ 283 return (unsigned long)vma->vm_private_data; 284} 285 286static void set_vma_private_data(struct vm_area_struct *vma, 287 unsigned long value) 288{ 289 vma->vm_private_data = (void *)value; 290} 291 292struct resv_map { 293 struct kref refs; 294 struct list_head regions; 295}; 296 297static struct resv_map *resv_map_alloc(void) 298{ 299 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); 300 if (!resv_map) 301 return NULL; 302 303 kref_init(&resv_map->refs); 304 INIT_LIST_HEAD(&resv_map->regions); 305 306 return resv_map; 307} 308 309static void resv_map_release(struct kref *ref) 310{ 311 struct resv_map *resv_map = container_of(ref, struct resv_map, refs); 312 313 /* Clear out any active regions before we release the map. */ 314 region_truncate(&resv_map->regions, 0); 315 kfree(resv_map); 316} 317 318static struct resv_map *vma_resv_map(struct vm_area_struct *vma) 319{ 320 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 321 if (!(vma->vm_flags & VM_MAYSHARE)) 322 return (struct resv_map *)(get_vma_private_data(vma) & 323 ~HPAGE_RESV_MASK); 324 return NULL; 325} 326 327static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) 328{ 329 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 330 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 331 332 set_vma_private_data(vma, (get_vma_private_data(vma) & 333 HPAGE_RESV_MASK) | (unsigned long)map); 334} 335 336static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) 337{ 338 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 339 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 340 341 set_vma_private_data(vma, get_vma_private_data(vma) | flags); 342} 343 344static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) 345{ 346 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 347 348 return (get_vma_private_data(vma) & flag) != 0; 349} 350 351/* Decrement the reserved pages in the hugepage pool by one */ 352static void decrement_hugepage_resv_vma(struct hstate *h, 353 struct vm_area_struct *vma) 354{ 355 if (vma->vm_flags & VM_NORESERVE) 356 return; 357 358 if (vma->vm_flags & VM_MAYSHARE) { 359 /* Shared mappings always use reserves */ 360 h->resv_huge_pages--; 361 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 362 /* 363 * Only the process that called mmap() has reserves for 364 * private mappings. 365 */ 366 h->resv_huge_pages--; 367 } 368} 369 370/* Reset counters to 0 and clear all HPAGE_RESV_* flags */ 371void reset_vma_resv_huge_pages(struct vm_area_struct *vma) 372{ 373 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 374 if (!(vma->vm_flags & VM_MAYSHARE)) 375 vma->vm_private_data = (void *)0; 376} 377 378/* Returns true if the VMA has associated reserve pages */ 379static int vma_has_reserves(struct vm_area_struct *vma) 380{ 381 if (vma->vm_flags & VM_MAYSHARE) 382 return 1; 383 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 384 return 1; 385 return 0; 386} 387 388static void clear_gigantic_page(struct page *page, 389 unsigned long addr, unsigned long sz) 390{ 391 int i; 392 struct page *p = page; 393 394 might_sleep(); 395 for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) { 396 cond_resched(); 397 clear_user_highpage(p, addr + i * PAGE_SIZE); 398 } 399} 400static void clear_huge_page(struct page *page, 401 unsigned long addr, unsigned long sz) 402{ 403 int i; 404 405 if (unlikely(sz > MAX_ORDER_NR_PAGES)) { 406 clear_gigantic_page(page, addr, sz); 407 return; 408 } 409 410 might_sleep(); 411 for (i = 0; i < sz/PAGE_SIZE; i++) { 412 cond_resched(); 413 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 414 } 415} 416 417static void copy_gigantic_page(struct page *dst, struct page *src, 418 unsigned long addr, struct vm_area_struct *vma) 419{ 420 int i; 421 struct hstate *h = hstate_vma(vma); 422 struct page *dst_base = dst; 423 struct page *src_base = src; 424 might_sleep(); 425 for (i = 0; i < pages_per_huge_page(h); ) { 426 cond_resched(); 427 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 428 429 i++; 430 dst = mem_map_next(dst, dst_base, i); 431 src = mem_map_next(src, src_base, i); 432 } 433} 434static void copy_huge_page(struct page *dst, struct page *src, 435 unsigned long addr, struct vm_area_struct *vma) 436{ 437 int i; 438 struct hstate *h = hstate_vma(vma); 439 440 if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { 441 copy_gigantic_page(dst, src, addr, vma); 442 return; 443 } 444 445 might_sleep(); 446 for (i = 0; i < pages_per_huge_page(h); i++) { 447 cond_resched(); 448 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 449 } 450} 451 452static void enqueue_huge_page(struct hstate *h, struct page *page) 453{ 454 int nid = page_to_nid(page); 455 list_add(&page->lru, &h->hugepage_freelists[nid]); 456 h->free_huge_pages++; 457 h->free_huge_pages_node[nid]++; 458} 459 460static struct page *dequeue_huge_page_vma(struct hstate *h, 461 struct vm_area_struct *vma, 462 unsigned long address, int avoid_reserve) 463{ 464 int nid; 465 struct page *page = NULL; 466 struct mempolicy *mpol; 467 nodemask_t *nodemask; 468 struct zonelist *zonelist = huge_zonelist(vma, address, 469 htlb_alloc_mask, &mpol, &nodemask); 470 struct zone *zone; 471 struct zoneref *z; 472 473 /* 474 * A child process with MAP_PRIVATE mappings created by their parent 475 * have no page reserves. This check ensures that reservations are 476 * not "stolen". The child may still get SIGKILLed 477 */ 478 if (!vma_has_reserves(vma) && 479 h->free_huge_pages - h->resv_huge_pages == 0) 480 return NULL; 481 482 /* If reserves cannot be used, ensure enough pages are in the pool */ 483 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) 484 return NULL; 485 486 for_each_zone_zonelist_nodemask(zone, z, zonelist, 487 MAX_NR_ZONES - 1, nodemask) { 488 nid = zone_to_nid(zone); 489 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) && 490 !list_empty(&h->hugepage_freelists[nid])) { 491 page = list_entry(h->hugepage_freelists[nid].next, 492 struct page, lru); 493 list_del(&page->lru); 494 h->free_huge_pages--; 495 h->free_huge_pages_node[nid]--; 496 497 if (!avoid_reserve) 498 decrement_hugepage_resv_vma(h, vma); 499 500 break; 501 } 502 } 503 mpol_cond_put(mpol); 504 return page; 505} 506 507static void update_and_free_page(struct hstate *h, struct page *page) 508{ 509 int i; 510 511 VM_BUG_ON(h->order >= MAX_ORDER); 512 513 h->nr_huge_pages--; 514 h->nr_huge_pages_node[page_to_nid(page)]--; 515 for (i = 0; i < pages_per_huge_page(h); i++) { 516 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 517 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved | 518 1 << PG_private | 1<< PG_writeback); 519 } 520 set_compound_page_dtor(page, NULL); 521 set_page_refcounted(page); 522 arch_release_hugepage(page); 523 __free_pages(page, huge_page_order(h)); 524} 525 526struct hstate *size_to_hstate(unsigned long size) 527{ 528 struct hstate *h; 529 530 for_each_hstate(h) { 531 if (huge_page_size(h) == size) 532 return h; 533 } 534 return NULL; 535} 536 537static void free_huge_page(struct page *page) 538{ 539 /* 540 * Can't pass hstate in here because it is called from the 541 * compound page destructor. 542 */ 543 struct hstate *h = page_hstate(page); 544 int nid = page_to_nid(page); 545 struct address_space *mapping; 546 547 mapping = (struct address_space *) page_private(page); 548 set_page_private(page, 0); 549 BUG_ON(page_count(page)); 550 INIT_LIST_HEAD(&page->lru); 551 552 spin_lock(&hugetlb_lock); 553 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { 554 update_and_free_page(h, page); 555 h->surplus_huge_pages--; 556 h->surplus_huge_pages_node[nid]--; 557 } else { 558 enqueue_huge_page(h, page); 559 } 560 spin_unlock(&hugetlb_lock); 561 if (mapping) 562 hugetlb_put_quota(mapping, 1); 563} 564 565static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) 566{ 567 set_compound_page_dtor(page, free_huge_page); 568 spin_lock(&hugetlb_lock); 569 h->nr_huge_pages++; 570 h->nr_huge_pages_node[nid]++; 571 spin_unlock(&hugetlb_lock); 572 put_page(page); /* free it into the hugepage allocator */ 573} 574 575static void prep_compound_gigantic_page(struct page *page, unsigned long order) 576{ 577 int i; 578 int nr_pages = 1 << order; 579 struct page *p = page + 1; 580 581 /* we rely on prep_new_huge_page to set the destructor */ 582 set_compound_order(page, order); 583 __SetPageHead(page); 584 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { 585 __SetPageTail(p); 586 p->first_page = page; 587 } 588} 589 590int PageHuge(struct page *page) 591{ 592 compound_page_dtor *dtor; 593 594 if (!PageCompound(page)) 595 return 0; 596 597 page = compound_head(page); 598 dtor = get_compound_page_dtor(page); 599 600 return dtor == free_huge_page; 601} 602 603static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 604{ 605 struct page *page; 606 607 if (h->order >= MAX_ORDER) 608 return NULL; 609 610 page = alloc_pages_exact_node(nid, 611 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 612 __GFP_REPEAT|__GFP_NOWARN, 613 huge_page_order(h)); 614 if (page) { 615 if (arch_prepare_hugepage(page)) { 616 __free_pages(page, huge_page_order(h)); 617 return NULL; 618 } 619 prep_new_huge_page(h, page, nid); 620 } 621 622 return page; 623} 624 625/* 626 * common helper functions for hstate_next_node_to_{alloc|free}. 627 * We may have allocated or freed a huge page based on a different 628 * nodes_allowed previously, so h->next_node_to_{alloc|free} might 629 * be outside of *nodes_allowed. Ensure that we use an allowed 630 * node for alloc or free. 631 */ 632static int next_node_allowed(int nid, nodemask_t *nodes_allowed) 633{ 634 nid = next_node(nid, *nodes_allowed); 635 if (nid == MAX_NUMNODES) 636 nid = first_node(*nodes_allowed); 637 VM_BUG_ON(nid >= MAX_NUMNODES); 638 639 return nid; 640} 641 642static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) 643{ 644 if (!node_isset(nid, *nodes_allowed)) 645 nid = next_node_allowed(nid, nodes_allowed); 646 return nid; 647} 648 649/* 650 * returns the previously saved node ["this node"] from which to 651 * allocate a persistent huge page for the pool and advance the 652 * next node from which to allocate, handling wrap at end of node 653 * mask. 654 */ 655static int hstate_next_node_to_alloc(struct hstate *h, 656 nodemask_t *nodes_allowed) 657{ 658 int nid; 659 660 VM_BUG_ON(!nodes_allowed); 661 662 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); 663 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); 664 665 return nid; 666} 667 668static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) 669{ 670 struct page *page; 671 int start_nid; 672 int next_nid; 673 int ret = 0; 674 675 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 676 next_nid = start_nid; 677 678 do { 679 page = alloc_fresh_huge_page_node(h, next_nid); 680 if (page) { 681 ret = 1; 682 break; 683 } 684 next_nid = hstate_next_node_to_alloc(h, nodes_allowed); 685 } while (next_nid != start_nid); 686 687 if (ret) 688 count_vm_event(HTLB_BUDDY_PGALLOC); 689 else 690 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 691 692 return ret; 693} 694 695/* 696 * helper for free_pool_huge_page() - return the previously saved 697 * node ["this node"] from which to free a huge page. Advance the 698 * next node id whether or not we find a free huge page to free so 699 * that the next attempt to free addresses the next node. 700 */ 701static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) 702{ 703 int nid; 704 705 VM_BUG_ON(!nodes_allowed); 706 707 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); 708 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); 709 710 return nid; 711} 712 713/* 714 * Free huge page from pool from next node to free. 715 * Attempt to keep persistent huge pages more or less 716 * balanced over allowed nodes. 717 * Called with hugetlb_lock locked. 718 */ 719static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, 720 bool acct_surplus) 721{ 722 int start_nid; 723 int next_nid; 724 int ret = 0; 725 726 start_nid = hstate_next_node_to_free(h, nodes_allowed); 727 next_nid = start_nid; 728 729 do { 730 /* 731 * If we're returning unused surplus pages, only examine 732 * nodes with surplus pages. 733 */ 734 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) && 735 !list_empty(&h->hugepage_freelists[next_nid])) { 736 struct page *page = 737 list_entry(h->hugepage_freelists[next_nid].next, 738 struct page, lru); 739 list_del(&page->lru); 740 h->free_huge_pages--; 741 h->free_huge_pages_node[next_nid]--; 742 if (acct_surplus) { 743 h->surplus_huge_pages--; 744 h->surplus_huge_pages_node[next_nid]--; 745 } 746 update_and_free_page(h, page); 747 ret = 1; 748 break; 749 } 750 next_nid = hstate_next_node_to_free(h, nodes_allowed); 751 } while (next_nid != start_nid); 752 753 return ret; 754} 755 756static struct page *alloc_buddy_huge_page(struct hstate *h, 757 struct vm_area_struct *vma, unsigned long address) 758{ 759 struct page *page; 760 unsigned int nid; 761 762 if (h->order >= MAX_ORDER) 763 return NULL; 764 765 /* 766 * Assume we will successfully allocate the surplus page to 767 * prevent racing processes from causing the surplus to exceed 768 * overcommit 769 * 770 * This however introduces a different race, where a process B 771 * tries to grow the static hugepage pool while alloc_pages() is 772 * called by process A. B will only examine the per-node 773 * counters in determining if surplus huge pages can be 774 * converted to normal huge pages in adjust_pool_surplus(). A 775 * won't be able to increment the per-node counter, until the 776 * lock is dropped by B, but B doesn't drop hugetlb_lock until 777 * no more huge pages can be converted from surplus to normal 778 * state (and doesn't try to convert again). Thus, we have a 779 * case where a surplus huge page exists, the pool is grown, and 780 * the surplus huge page still exists after, even though it 781 * should just have been converted to a normal huge page. This 782 * does not leak memory, though, as the hugepage will be freed 783 * once it is out of use. It also does not allow the counters to 784 * go out of whack in adjust_pool_surplus() as we don't modify 785 * the node values until we've gotten the hugepage and only the 786 * per-node value is checked there. 787 */ 788 spin_lock(&hugetlb_lock); 789 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { 790 spin_unlock(&hugetlb_lock); 791 return NULL; 792 } else { 793 h->nr_huge_pages++; 794 h->surplus_huge_pages++; 795 } 796 spin_unlock(&hugetlb_lock); 797 798 page = alloc_pages(htlb_alloc_mask|__GFP_COMP| 799 __GFP_REPEAT|__GFP_NOWARN, 800 huge_page_order(h)); 801 802 if (page && arch_prepare_hugepage(page)) { 803 __free_pages(page, huge_page_order(h)); 804 return NULL; 805 } 806 807 spin_lock(&hugetlb_lock); 808 if (page) { 809 /* 810 * This page is now managed by the hugetlb allocator and has 811 * no users -- drop the buddy allocator's reference. 812 */ 813 put_page_testzero(page); 814 VM_BUG_ON(page_count(page)); 815 nid = page_to_nid(page); 816 set_compound_page_dtor(page, free_huge_page); 817 /* 818 * We incremented the global counters already 819 */ 820 h->nr_huge_pages_node[nid]++; 821 h->surplus_huge_pages_node[nid]++; 822 __count_vm_event(HTLB_BUDDY_PGALLOC); 823 } else { 824 h->nr_huge_pages--; 825 h->surplus_huge_pages--; 826 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 827 } 828 spin_unlock(&hugetlb_lock); 829 830 return page; 831} 832 833/* 834 * Increase the hugetlb pool such that it can accomodate a reservation 835 * of size 'delta'. 836 */ 837static int gather_surplus_pages(struct hstate *h, int delta) 838{ 839 struct list_head surplus_list; 840 struct page *page, *tmp; 841 int ret, i; 842 int needed, allocated; 843 844 needed = (h->resv_huge_pages + delta) - h->free_huge_pages; 845 if (needed <= 0) { 846 h->resv_huge_pages += delta; 847 return 0; 848 } 849 850 allocated = 0; 851 INIT_LIST_HEAD(&surplus_list); 852 853 ret = -ENOMEM; 854retry: 855 spin_unlock(&hugetlb_lock); 856 for (i = 0; i < needed; i++) { 857 page = alloc_buddy_huge_page(h, NULL, 0); 858 if (!page) { 859 /* 860 * We were not able to allocate enough pages to 861 * satisfy the entire reservation so we free what 862 * we've allocated so far. 863 */ 864 spin_lock(&hugetlb_lock); 865 needed = 0; 866 goto free; 867 } 868 869 list_add(&page->lru, &surplus_list); 870 } 871 allocated += needed; 872 873 /* 874 * After retaking hugetlb_lock, we need to recalculate 'needed' 875 * because either resv_huge_pages or free_huge_pages may have changed. 876 */ 877 spin_lock(&hugetlb_lock); 878 needed = (h->resv_huge_pages + delta) - 879 (h->free_huge_pages + allocated); 880 if (needed > 0) 881 goto retry; 882 883 /* 884 * The surplus_list now contains _at_least_ the number of extra pages 885 * needed to accomodate the reservation. Add the appropriate number 886 * of pages to the hugetlb pool and free the extras back to the buddy 887 * allocator. Commit the entire reservation here to prevent another 888 * process from stealing the pages as they are added to the pool but 889 * before they are reserved. 890 */ 891 needed += allocated; 892 h->resv_huge_pages += delta; 893 ret = 0; 894free: 895 /* Free the needed pages to the hugetlb pool */ 896 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 897 if ((--needed) < 0) 898 break; 899 list_del(&page->lru); 900 enqueue_huge_page(h, page); 901 } 902 903 /* Free unnecessary surplus pages to the buddy allocator */ 904 if (!list_empty(&surplus_list)) { 905 spin_unlock(&hugetlb_lock); 906 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 907 list_del(&page->lru); 908 /* 909 * The page has a reference count of zero already, so 910 * call free_huge_page directly instead of using 911 * put_page. This must be done with hugetlb_lock 912 * unlocked which is safe because free_huge_page takes 913 * hugetlb_lock before deciding how to free the page. 914 */ 915 free_huge_page(page); 916 } 917 spin_lock(&hugetlb_lock); 918 } 919 920 return ret; 921} 922 923/* 924 * When releasing a hugetlb pool reservation, any surplus pages that were 925 * allocated to satisfy the reservation must be explicitly freed if they were 926 * never used. 927 * Called with hugetlb_lock held. 928 */ 929static void return_unused_surplus_pages(struct hstate *h, 930 unsigned long unused_resv_pages) 931{ 932 unsigned long nr_pages; 933 934 /* Uncommit the reservation */ 935 h->resv_huge_pages -= unused_resv_pages; 936 937 /* Cannot return gigantic pages currently */ 938 if (h->order >= MAX_ORDER) 939 return; 940 941 nr_pages = min(unused_resv_pages, h->surplus_huge_pages); 942 943 /* 944 * We want to release as many surplus pages as possible, spread 945 * evenly across all nodes with memory. Iterate across these nodes 946 * until we can no longer free unreserved surplus pages. This occurs 947 * when the nodes with surplus pages have no free pages. 948 * free_pool_huge_page() will balance the the freed pages across the 949 * on-line nodes with memory and will handle the hstate accounting. 950 */ 951 while (nr_pages--) { 952 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1)) 953 break; 954 } 955} 956 957/* 958 * Determine if the huge page at addr within the vma has an associated 959 * reservation. Where it does not we will need to logically increase 960 * reservation and actually increase quota before an allocation can occur. 961 * Where any new reservation would be required the reservation change is 962 * prepared, but not committed. Once the page has been quota'd allocated 963 * an instantiated the change should be committed via vma_commit_reservation. 964 * No action is required on failure. 965 */ 966static long vma_needs_reservation(struct hstate *h, 967 struct vm_area_struct *vma, unsigned long addr) 968{ 969 struct address_space *mapping = vma->vm_file->f_mapping; 970 struct inode *inode = mapping->host; 971 972 if (vma->vm_flags & VM_MAYSHARE) { 973 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 974 return region_chg(&inode->i_mapping->private_list, 975 idx, idx + 1); 976 977 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 978 return 1; 979 980 } else { 981 long err; 982 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 983 struct resv_map *reservations = vma_resv_map(vma); 984 985 err = region_chg(&reservations->regions, idx, idx + 1); 986 if (err < 0) 987 return err; 988 return 0; 989 } 990} 991static void vma_commit_reservation(struct hstate *h, 992 struct vm_area_struct *vma, unsigned long addr) 993{ 994 struct address_space *mapping = vma->vm_file->f_mapping; 995 struct inode *inode = mapping->host; 996 997 if (vma->vm_flags & VM_MAYSHARE) { 998 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 999 region_add(&inode->i_mapping->private_list, idx, idx + 1); 1000 1001 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 1002 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1003 struct resv_map *reservations = vma_resv_map(vma); 1004 1005 /* Mark this page used in the map. */ 1006 region_add(&reservations->regions, idx, idx + 1); 1007 } 1008} 1009 1010static struct page *alloc_huge_page(struct vm_area_struct *vma, 1011 unsigned long addr, int avoid_reserve) 1012{ 1013 struct hstate *h = hstate_vma(vma); 1014 struct page *page; 1015 struct address_space *mapping = vma->vm_file->f_mapping; 1016 struct inode *inode = mapping->host; 1017 long chg; 1018 1019 /* 1020 * Processes that did not create the mapping will have no reserves and 1021 * will not have accounted against quota. Check that the quota can be 1022 * made before satisfying the allocation 1023 * MAP_NORESERVE mappings may also need pages and quota allocated 1024 * if no reserve mapping overlaps. 1025 */ 1026 chg = vma_needs_reservation(h, vma, addr); 1027 if (chg < 0) 1028 return ERR_PTR(chg); 1029 if (chg) 1030 if (hugetlb_get_quota(inode->i_mapping, chg)) 1031 return ERR_PTR(-ENOSPC); 1032 1033 spin_lock(&hugetlb_lock); 1034 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); 1035 spin_unlock(&hugetlb_lock); 1036 1037 if (!page) { 1038 page = alloc_buddy_huge_page(h, vma, addr); 1039 if (!page) { 1040 hugetlb_put_quota(inode->i_mapping, chg); 1041 return ERR_PTR(-VM_FAULT_OOM); 1042 } 1043 } 1044 1045 set_page_refcounted(page); 1046 set_page_private(page, (unsigned long) mapping); 1047 1048 vma_commit_reservation(h, vma, addr); 1049 1050 return page; 1051} 1052 1053int __weak alloc_bootmem_huge_page(struct hstate *h) 1054{ 1055 struct huge_bootmem_page *m; 1056 int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]); 1057 1058 while (nr_nodes) { 1059 void *addr; 1060 1061 addr = __alloc_bootmem_node_nopanic( 1062 NODE_DATA(hstate_next_node_to_alloc(h, 1063 &node_states[N_HIGH_MEMORY])), 1064 huge_page_size(h), huge_page_size(h), 0); 1065 1066 if (addr) { 1067 /* 1068 * Use the beginning of the huge page to store the 1069 * huge_bootmem_page struct (until gather_bootmem 1070 * puts them into the mem_map). 1071 */ 1072 m = addr; 1073 goto found; 1074 } 1075 nr_nodes--; 1076 } 1077 return 0; 1078 1079found: 1080 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); 1081 /* Put them into a private list first because mem_map is not up yet */ 1082 list_add(&m->list, &huge_boot_pages); 1083 m->hstate = h; 1084 return 1; 1085} 1086 1087static void prep_compound_huge_page(struct page *page, int order) 1088{ 1089 if (unlikely(order > (MAX_ORDER - 1))) 1090 prep_compound_gigantic_page(page, order); 1091 else 1092 prep_compound_page(page, order); 1093} 1094 1095/* Put bootmem huge pages into the standard lists after mem_map is up */ 1096static void __init gather_bootmem_prealloc(void) 1097{ 1098 struct huge_bootmem_page *m; 1099 1100 list_for_each_entry(m, &huge_boot_pages, list) { 1101 struct page *page = virt_to_page(m); 1102 struct hstate *h = m->hstate; 1103 __ClearPageReserved(page); 1104 WARN_ON(page_count(page) != 1); 1105 prep_compound_huge_page(page, h->order); 1106 prep_new_huge_page(h, page, page_to_nid(page)); 1107 } 1108} 1109 1110static void __init hugetlb_hstate_alloc_pages(struct hstate *h) 1111{ 1112 unsigned long i; 1113 1114 for (i = 0; i < h->max_huge_pages; ++i) { 1115 if (h->order >= MAX_ORDER) { 1116 if (!alloc_bootmem_huge_page(h)) 1117 break; 1118 } else if (!alloc_fresh_huge_page(h, 1119 &node_states[N_HIGH_MEMORY])) 1120 break; 1121 } 1122 h->max_huge_pages = i; 1123} 1124 1125static void __init hugetlb_init_hstates(void) 1126{ 1127 struct hstate *h; 1128 1129 for_each_hstate(h) { 1130 /* oversize hugepages were init'ed in early boot */ 1131 if (h->order < MAX_ORDER) 1132 hugetlb_hstate_alloc_pages(h); 1133 } 1134} 1135 1136static char * __init memfmt(char *buf, unsigned long n) 1137{ 1138 if (n >= (1UL << 30)) 1139 sprintf(buf, "%lu GB", n >> 30); 1140 else if (n >= (1UL << 20)) 1141 sprintf(buf, "%lu MB", n >> 20); 1142 else 1143 sprintf(buf, "%lu KB", n >> 10); 1144 return buf; 1145} 1146 1147static void __init report_hugepages(void) 1148{ 1149 struct hstate *h; 1150 1151 for_each_hstate(h) { 1152 char buf[32]; 1153 printk(KERN_INFO "HugeTLB registered %s page size, " 1154 "pre-allocated %ld pages\n", 1155 memfmt(buf, huge_page_size(h)), 1156 h->free_huge_pages); 1157 } 1158} 1159 1160#ifdef CONFIG_HIGHMEM 1161static void try_to_free_low(struct hstate *h, unsigned long count, 1162 nodemask_t *nodes_allowed) 1163{ 1164 int i; 1165 1166 if (h->order >= MAX_ORDER) 1167 return; 1168 1169 for_each_node_mask(i, *nodes_allowed) { 1170 struct page *page, *next; 1171 struct list_head *freel = &h->hugepage_freelists[i]; 1172 list_for_each_entry_safe(page, next, freel, lru) { 1173 if (count >= h->nr_huge_pages) 1174 return; 1175 if (PageHighMem(page)) 1176 continue; 1177 list_del(&page->lru); 1178 update_and_free_page(h, page); 1179 h->free_huge_pages--; 1180 h->free_huge_pages_node[page_to_nid(page)]--; 1181 } 1182 } 1183} 1184#else 1185static inline void try_to_free_low(struct hstate *h, unsigned long count, 1186 nodemask_t *nodes_allowed) 1187{ 1188} 1189#endif 1190 1191/* 1192 * Increment or decrement surplus_huge_pages. Keep node-specific counters 1193 * balanced by operating on them in a round-robin fashion. 1194 * Returns 1 if an adjustment was made. 1195 */ 1196static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, 1197 int delta) 1198{ 1199 int start_nid, next_nid; 1200 int ret = 0; 1201 1202 VM_BUG_ON(delta != -1 && delta != 1); 1203 1204 if (delta < 0) 1205 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 1206 else 1207 start_nid = hstate_next_node_to_free(h, nodes_allowed); 1208 next_nid = start_nid; 1209 1210 do { 1211 int nid = next_nid; 1212 if (delta < 0) { 1213 /* 1214 * To shrink on this node, there must be a surplus page 1215 */ 1216 if (!h->surplus_huge_pages_node[nid]) { 1217 next_nid = hstate_next_node_to_alloc(h, 1218 nodes_allowed); 1219 continue; 1220 } 1221 } 1222 if (delta > 0) { 1223 /* 1224 * Surplus cannot exceed the total number of pages 1225 */ 1226 if (h->surplus_huge_pages_node[nid] >= 1227 h->nr_huge_pages_node[nid]) { 1228 next_nid = hstate_next_node_to_free(h, 1229 nodes_allowed); 1230 continue; 1231 } 1232 } 1233 1234 h->surplus_huge_pages += delta; 1235 h->surplus_huge_pages_node[nid] += delta; 1236 ret = 1; 1237 break; 1238 } while (next_nid != start_nid); 1239 1240 return ret; 1241} 1242 1243#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) 1244static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, 1245 nodemask_t *nodes_allowed) 1246{ 1247 unsigned long min_count, ret; 1248 1249 if (h->order >= MAX_ORDER) 1250 return h->max_huge_pages; 1251 1252 /* 1253 * Increase the pool size 1254 * First take pages out of surplus state. Then make up the 1255 * remaining difference by allocating fresh huge pages. 1256 * 1257 * We might race with alloc_buddy_huge_page() here and be unable 1258 * to convert a surplus huge page to a normal huge page. That is 1259 * not critical, though, it just means the overall size of the 1260 * pool might be one hugepage larger than it needs to be, but 1261 * within all the constraints specified by the sysctls. 1262 */ 1263 spin_lock(&hugetlb_lock); 1264 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { 1265 if (!adjust_pool_surplus(h, nodes_allowed, -1)) 1266 break; 1267 } 1268 1269 while (count > persistent_huge_pages(h)) { 1270 /* 1271 * If this allocation races such that we no longer need the 1272 * page, free_huge_page will handle it by freeing the page 1273 * and reducing the surplus. 1274 */ 1275 spin_unlock(&hugetlb_lock); 1276 ret = alloc_fresh_huge_page(h, nodes_allowed); 1277 spin_lock(&hugetlb_lock); 1278 if (!ret) 1279 goto out; 1280 1281 } 1282 1283 /* 1284 * Decrease the pool size 1285 * First return free pages to the buddy allocator (being careful 1286 * to keep enough around to satisfy reservations). Then place 1287 * pages into surplus state as needed so the pool will shrink 1288 * to the desired size as pages become free. 1289 * 1290 * By placing pages into the surplus state independent of the 1291 * overcommit value, we are allowing the surplus pool size to 1292 * exceed overcommit. There are few sane options here. Since 1293 * alloc_buddy_huge_page() is checking the global counter, 1294 * though, we'll note that we're not allowed to exceed surplus 1295 * and won't grow the pool anywhere else. Not until one of the 1296 * sysctls are changed, or the surplus pages go out of use. 1297 */ 1298 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; 1299 min_count = max(count, min_count); 1300 try_to_free_low(h, min_count, nodes_allowed); 1301 while (min_count < persistent_huge_pages(h)) { 1302 if (!free_pool_huge_page(h, nodes_allowed, 0)) 1303 break; 1304 } 1305 while (count < persistent_huge_pages(h)) { 1306 if (!adjust_pool_surplus(h, nodes_allowed, 1)) 1307 break; 1308 } 1309out: 1310 ret = persistent_huge_pages(h); 1311 spin_unlock(&hugetlb_lock); 1312 return ret; 1313} 1314 1315#define HSTATE_ATTR_RO(_name) \ 1316 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 1317 1318#define HSTATE_ATTR(_name) \ 1319 static struct kobj_attribute _name##_attr = \ 1320 __ATTR(_name, 0644, _name##_show, _name##_store) 1321 1322static struct kobject *hugepages_kobj; 1323static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1324 1325static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); 1326 1327static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) 1328{ 1329 int i; 1330 1331 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1332 if (hstate_kobjs[i] == kobj) { 1333 if (nidp) 1334 *nidp = NUMA_NO_NODE; 1335 return &hstates[i]; 1336 } 1337 1338 return kobj_to_node_hstate(kobj, nidp); 1339} 1340 1341static ssize_t nr_hugepages_show_common(struct kobject *kobj, 1342 struct kobj_attribute *attr, char *buf) 1343{ 1344 struct hstate *h; 1345 unsigned long nr_huge_pages; 1346 int nid; 1347 1348 h = kobj_to_hstate(kobj, &nid); 1349 if (nid == NUMA_NO_NODE) 1350 nr_huge_pages = h->nr_huge_pages; 1351 else 1352 nr_huge_pages = h->nr_huge_pages_node[nid]; 1353 1354 return sprintf(buf, "%lu\n", nr_huge_pages); 1355} 1356static ssize_t nr_hugepages_store_common(bool obey_mempolicy, 1357 struct kobject *kobj, struct kobj_attribute *attr, 1358 const char *buf, size_t len) 1359{ 1360 int err; 1361 int nid; 1362 unsigned long count; 1363 struct hstate *h; 1364 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); 1365 1366 err = strict_strtoul(buf, 10, &count); 1367 if (err) 1368 return 0; 1369 1370 h = kobj_to_hstate(kobj, &nid); 1371 if (nid == NUMA_NO_NODE) { 1372 /* 1373 * global hstate attribute 1374 */ 1375 if (!(obey_mempolicy && 1376 init_nodemask_of_mempolicy(nodes_allowed))) { 1377 NODEMASK_FREE(nodes_allowed); 1378 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1379 } 1380 } else if (nodes_allowed) { 1381 /* 1382 * per node hstate attribute: adjust count to global, 1383 * but restrict alloc/free to the specified node. 1384 */ 1385 count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; 1386 init_nodemask_of_node(nodes_allowed, nid); 1387 } else 1388 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1389 1390 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); 1391 1392 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1393 NODEMASK_FREE(nodes_allowed); 1394 1395 return len; 1396} 1397 1398static ssize_t nr_hugepages_show(struct kobject *kobj, 1399 struct kobj_attribute *attr, char *buf) 1400{ 1401 return nr_hugepages_show_common(kobj, attr, buf); 1402} 1403 1404static ssize_t nr_hugepages_store(struct kobject *kobj, 1405 struct kobj_attribute *attr, const char *buf, size_t len) 1406{ 1407 return nr_hugepages_store_common(false, kobj, attr, buf, len); 1408} 1409HSTATE_ATTR(nr_hugepages); 1410 1411#ifdef CONFIG_NUMA 1412 1413/* 1414 * hstate attribute for optionally mempolicy-based constraint on persistent 1415 * huge page alloc/free. 1416 */ 1417static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, 1418 struct kobj_attribute *attr, char *buf) 1419{ 1420 return nr_hugepages_show_common(kobj, attr, buf); 1421} 1422 1423static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, 1424 struct kobj_attribute *attr, const char *buf, size_t len) 1425{ 1426 return nr_hugepages_store_common(true, kobj, attr, buf, len); 1427} 1428HSTATE_ATTR(nr_hugepages_mempolicy); 1429#endif 1430 1431 1432static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, 1433 struct kobj_attribute *attr, char *buf) 1434{ 1435 struct hstate *h = kobj_to_hstate(kobj, NULL); 1436 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); 1437} 1438static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, 1439 struct kobj_attribute *attr, const char *buf, size_t count) 1440{ 1441 int err; 1442 unsigned long input; 1443 struct hstate *h = kobj_to_hstate(kobj, NULL); 1444 1445 err = strict_strtoul(buf, 10, &input); 1446 if (err) 1447 return 0; 1448 1449 spin_lock(&hugetlb_lock); 1450 h->nr_overcommit_huge_pages = input; 1451 spin_unlock(&hugetlb_lock); 1452 1453 return count; 1454} 1455HSTATE_ATTR(nr_overcommit_hugepages); 1456 1457static ssize_t free_hugepages_show(struct kobject *kobj, 1458 struct kobj_attribute *attr, char *buf) 1459{ 1460 struct hstate *h; 1461 unsigned long free_huge_pages; 1462 int nid; 1463 1464 h = kobj_to_hstate(kobj, &nid); 1465 if (nid == NUMA_NO_NODE) 1466 free_huge_pages = h->free_huge_pages; 1467 else 1468 free_huge_pages = h->free_huge_pages_node[nid]; 1469 1470 return sprintf(buf, "%lu\n", free_huge_pages); 1471} 1472HSTATE_ATTR_RO(free_hugepages); 1473 1474static ssize_t resv_hugepages_show(struct kobject *kobj, 1475 struct kobj_attribute *attr, char *buf) 1476{ 1477 struct hstate *h = kobj_to_hstate(kobj, NULL); 1478 return sprintf(buf, "%lu\n", h->resv_huge_pages); 1479} 1480HSTATE_ATTR_RO(resv_hugepages); 1481 1482static ssize_t surplus_hugepages_show(struct kobject *kobj, 1483 struct kobj_attribute *attr, char *buf) 1484{ 1485 struct hstate *h; 1486 unsigned long surplus_huge_pages; 1487 int nid; 1488 1489 h = kobj_to_hstate(kobj, &nid); 1490 if (nid == NUMA_NO_NODE) 1491 surplus_huge_pages = h->surplus_huge_pages; 1492 else 1493 surplus_huge_pages = h->surplus_huge_pages_node[nid]; 1494 1495 return sprintf(buf, "%lu\n", surplus_huge_pages); 1496} 1497HSTATE_ATTR_RO(surplus_hugepages); 1498 1499static struct attribute *hstate_attrs[] = { 1500 &nr_hugepages_attr.attr, 1501 &nr_overcommit_hugepages_attr.attr, 1502 &free_hugepages_attr.attr, 1503 &resv_hugepages_attr.attr, 1504 &surplus_hugepages_attr.attr, 1505#ifdef CONFIG_NUMA 1506 &nr_hugepages_mempolicy_attr.attr, 1507#endif 1508 NULL, 1509}; 1510 1511static struct attribute_group hstate_attr_group = { 1512 .attrs = hstate_attrs, 1513}; 1514 1515static int __init hugetlb_sysfs_add_hstate(struct hstate *h, 1516 struct kobject *parent, 1517 struct kobject **hstate_kobjs, 1518 struct attribute_group *hstate_attr_group) 1519{ 1520 int retval; 1521 int hi = h - hstates; 1522 1523 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); 1524 if (!hstate_kobjs[hi]) 1525 return -ENOMEM; 1526 1527 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); 1528 if (retval) 1529 kobject_put(hstate_kobjs[hi]); 1530 1531 return retval; 1532} 1533 1534static void __init hugetlb_sysfs_init(void) 1535{ 1536 struct hstate *h; 1537 int err; 1538 1539 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); 1540 if (!hugepages_kobj) 1541 return; 1542 1543 for_each_hstate(h) { 1544 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, 1545 hstate_kobjs, &hstate_attr_group); 1546 if (err) 1547 printk(KERN_ERR "Hugetlb: Unable to add hstate %s", 1548 h->name); 1549 } 1550} 1551 1552#ifdef CONFIG_NUMA 1553 1554/* 1555 * node_hstate/s - associate per node hstate attributes, via their kobjects, 1556 * with node sysdevs in node_devices[] using a parallel array. The array 1557 * index of a node sysdev or _hstate == node id. 1558 * This is here to avoid any static dependency of the node sysdev driver, in 1559 * the base kernel, on the hugetlb module. 1560 */ 1561struct node_hstate { 1562 struct kobject *hugepages_kobj; 1563 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1564}; 1565struct node_hstate node_hstates[MAX_NUMNODES]; 1566 1567/* 1568 * A subset of global hstate attributes for node sysdevs 1569 */ 1570static struct attribute *per_node_hstate_attrs[] = { 1571 &nr_hugepages_attr.attr, 1572 &free_hugepages_attr.attr, 1573 &surplus_hugepages_attr.attr, 1574 NULL, 1575}; 1576 1577static struct attribute_group per_node_hstate_attr_group = { 1578 .attrs = per_node_hstate_attrs, 1579}; 1580 1581/* 1582 * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj. 1583 * Returns node id via non-NULL nidp. 1584 */ 1585static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1586{ 1587 int nid; 1588 1589 for (nid = 0; nid < nr_node_ids; nid++) { 1590 struct node_hstate *nhs = &node_hstates[nid]; 1591 int i; 1592 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1593 if (nhs->hstate_kobjs[i] == kobj) { 1594 if (nidp) 1595 *nidp = nid; 1596 return &hstates[i]; 1597 } 1598 } 1599 1600 BUG(); 1601 return NULL; 1602} 1603 1604/* 1605 * Unregister hstate attributes from a single node sysdev. 1606 * No-op if no hstate attributes attached. 1607 */ 1608void hugetlb_unregister_node(struct node *node) 1609{ 1610 struct hstate *h; 1611 struct node_hstate *nhs = &node_hstates[node->sysdev.id]; 1612 1613 if (!nhs->hugepages_kobj) 1614 return; /* no hstate attributes */ 1615 1616 for_each_hstate(h) 1617 if (nhs->hstate_kobjs[h - hstates]) { 1618 kobject_put(nhs->hstate_kobjs[h - hstates]); 1619 nhs->hstate_kobjs[h - hstates] = NULL; 1620 } 1621 1622 kobject_put(nhs->hugepages_kobj); 1623 nhs->hugepages_kobj = NULL; 1624} 1625 1626/* 1627 * hugetlb module exit: unregister hstate attributes from node sysdevs 1628 * that have them. 1629 */ 1630static void hugetlb_unregister_all_nodes(void) 1631{ 1632 int nid; 1633 1634 /* 1635 * disable node sysdev registrations. 1636 */ 1637 register_hugetlbfs_with_node(NULL, NULL); 1638 1639 /* 1640 * remove hstate attributes from any nodes that have them. 1641 */ 1642 for (nid = 0; nid < nr_node_ids; nid++) 1643 hugetlb_unregister_node(&node_devices[nid]); 1644} 1645 1646/* 1647 * Register hstate attributes for a single node sysdev. 1648 * No-op if attributes already registered. 1649 */ 1650void hugetlb_register_node(struct node *node) 1651{ 1652 struct hstate *h; 1653 struct node_hstate *nhs = &node_hstates[node->sysdev.id]; 1654 int err; 1655 1656 if (nhs->hugepages_kobj) 1657 return; /* already allocated */ 1658 1659 nhs->hugepages_kobj = kobject_create_and_add("hugepages", 1660 &node->sysdev.kobj); 1661 if (!nhs->hugepages_kobj) 1662 return; 1663 1664 for_each_hstate(h) { 1665 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, 1666 nhs->hstate_kobjs, 1667 &per_node_hstate_attr_group); 1668 if (err) { 1669 printk(KERN_ERR "Hugetlb: Unable to add hstate %s" 1670 " for node %d\n", 1671 h->name, node->sysdev.id); 1672 hugetlb_unregister_node(node); 1673 break; 1674 } 1675 } 1676} 1677 1678/* 1679 * hugetlb init time: register hstate attributes for all registered node 1680 * sysdevs of nodes that have memory. All on-line nodes should have 1681 * registered their associated sysdev by this time. 1682 */ 1683static void hugetlb_register_all_nodes(void) 1684{ 1685 int nid; 1686 1687 for_each_node_state(nid, N_HIGH_MEMORY) { 1688 struct node *node = &node_devices[nid]; 1689 if (node->sysdev.id == nid) 1690 hugetlb_register_node(node); 1691 } 1692 1693 /* 1694 * Let the node sysdev driver know we're here so it can 1695 * [un]register hstate attributes on node hotplug. 1696 */ 1697 register_hugetlbfs_with_node(hugetlb_register_node, 1698 hugetlb_unregister_node); 1699} 1700#else /* !CONFIG_NUMA */ 1701 1702static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1703{ 1704 BUG(); 1705 if (nidp) 1706 *nidp = -1; 1707 return NULL; 1708} 1709 1710static void hugetlb_unregister_all_nodes(void) { } 1711 1712static void hugetlb_register_all_nodes(void) { } 1713 1714#endif 1715 1716static void __exit hugetlb_exit(void) 1717{ 1718 struct hstate *h; 1719 1720 hugetlb_unregister_all_nodes(); 1721 1722 for_each_hstate(h) { 1723 kobject_put(hstate_kobjs[h - hstates]); 1724 } 1725 1726 kobject_put(hugepages_kobj); 1727} 1728module_exit(hugetlb_exit); 1729 1730static int __init hugetlb_init(void) 1731{ 1732 /* Some platform decide whether they support huge pages at boot 1733 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when 1734 * there is no such support 1735 */ 1736 if (HPAGE_SHIFT == 0) 1737 return 0; 1738 1739 if (!size_to_hstate(default_hstate_size)) { 1740 default_hstate_size = HPAGE_SIZE; 1741 if (!size_to_hstate(default_hstate_size)) 1742 hugetlb_add_hstate(HUGETLB_PAGE_ORDER); 1743 } 1744 default_hstate_idx = size_to_hstate(default_hstate_size) - hstates; 1745 if (default_hstate_max_huge_pages) 1746 default_hstate.max_huge_pages = default_hstate_max_huge_pages; 1747 1748 hugetlb_init_hstates(); 1749 1750 gather_bootmem_prealloc(); 1751 1752 report_hugepages(); 1753 1754 hugetlb_sysfs_init(); 1755 1756 hugetlb_register_all_nodes(); 1757 1758 return 0; 1759} 1760module_init(hugetlb_init); 1761 1762/* Should be called on processing a hugepagesz=... option */ 1763void __init hugetlb_add_hstate(unsigned order) 1764{ 1765 struct hstate *h; 1766 unsigned long i; 1767 1768 if (size_to_hstate(PAGE_SIZE << order)) { 1769 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n"); 1770 return; 1771 } 1772 BUG_ON(max_hstate >= HUGE_MAX_HSTATE); 1773 BUG_ON(order == 0); 1774 h = &hstates[max_hstate++]; 1775 h->order = order; 1776 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); 1777 h->nr_huge_pages = 0; 1778 h->free_huge_pages = 0; 1779 for (i = 0; i < MAX_NUMNODES; ++i) 1780 INIT_LIST_HEAD(&h->hugepage_freelists[i]); 1781 h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]); 1782 h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]); 1783 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", 1784 huge_page_size(h)/1024); 1785 1786 parsed_hstate = h; 1787} 1788 1789static int __init hugetlb_nrpages_setup(char *s) 1790{ 1791 unsigned long *mhp; 1792 static unsigned long *last_mhp; 1793 1794 /* 1795 * !max_hstate means we haven't parsed a hugepagesz= parameter yet, 1796 * so this hugepages= parameter goes to the "default hstate". 1797 */ 1798 if (!max_hstate) 1799 mhp = &default_hstate_max_huge_pages; 1800 else 1801 mhp = &parsed_hstate->max_huge_pages; 1802 1803 if (mhp == last_mhp) { 1804 printk(KERN_WARNING "hugepages= specified twice without " 1805 "interleaving hugepagesz=, ignoring\n"); 1806 return 1; 1807 } 1808 1809 if (sscanf(s, "%lu", mhp) <= 0) 1810 *mhp = 0; 1811 1812 /* 1813 * Global state is always initialized later in hugetlb_init. 1814 * But we need to allocate >= MAX_ORDER hstates here early to still 1815 * use the bootmem allocator. 1816 */ 1817 if (max_hstate && parsed_hstate->order >= MAX_ORDER) 1818 hugetlb_hstate_alloc_pages(parsed_hstate); 1819 1820 last_mhp = mhp; 1821 1822 return 1; 1823} 1824__setup("hugepages=", hugetlb_nrpages_setup); 1825 1826static int __init hugetlb_default_setup(char *s) 1827{ 1828 default_hstate_size = memparse(s, &s); 1829 return 1; 1830} 1831__setup("default_hugepagesz=", hugetlb_default_setup); 1832 1833static unsigned int cpuset_mems_nr(unsigned int *array) 1834{ 1835 int node; 1836 unsigned int nr = 0; 1837 1838 for_each_node_mask(node, cpuset_current_mems_allowed) 1839 nr += array[node]; 1840 1841 return nr; 1842} 1843 1844#ifdef CONFIG_SYSCTL 1845static int hugetlb_sysctl_handler_common(bool obey_mempolicy, 1846 struct ctl_table *table, int write, 1847 void __user *buffer, size_t *length, loff_t *ppos) 1848{ 1849 struct hstate *h = &default_hstate; 1850 unsigned long tmp; 1851 1852 if (!write) 1853 tmp = h->max_huge_pages; 1854 1855 table->data = &tmp; 1856 table->maxlen = sizeof(unsigned long); 1857 proc_doulongvec_minmax(table, write, buffer, length, ppos); 1858 1859 if (write) { 1860 NODEMASK_ALLOC(nodemask_t, nodes_allowed, 1861 GFP_KERNEL | __GFP_NORETRY); 1862 if (!(obey_mempolicy && 1863 init_nodemask_of_mempolicy(nodes_allowed))) { 1864 NODEMASK_FREE(nodes_allowed); 1865 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1866 } 1867 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); 1868 1869 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1870 NODEMASK_FREE(nodes_allowed); 1871 } 1872 1873 return 0; 1874} 1875 1876int hugetlb_sysctl_handler(struct ctl_table *table, int write, 1877 void __user *buffer, size_t *length, loff_t *ppos) 1878{ 1879 1880 return hugetlb_sysctl_handler_common(false, table, write, 1881 buffer, length, ppos); 1882} 1883 1884#ifdef CONFIG_NUMA 1885int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, 1886 void __user *buffer, size_t *length, loff_t *ppos) 1887{ 1888 return hugetlb_sysctl_handler_common(true, table, write, 1889 buffer, length, ppos); 1890} 1891#endif /* CONFIG_NUMA */ 1892 1893int hugetlb_treat_movable_handler(struct ctl_table *table, int write, 1894 void __user *buffer, 1895 size_t *length, loff_t *ppos) 1896{ 1897 proc_dointvec(table, write, buffer, length, ppos); 1898 if (hugepages_treat_as_movable) 1899 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; 1900 else 1901 htlb_alloc_mask = GFP_HIGHUSER; 1902 return 0; 1903} 1904 1905int hugetlb_overcommit_handler(struct ctl_table *table, int write, 1906 void __user *buffer, 1907 size_t *length, loff_t *ppos) 1908{ 1909 struct hstate *h = &default_hstate; 1910 unsigned long tmp; 1911 1912 if (!write) 1913 tmp = h->nr_overcommit_huge_pages; 1914 1915 table->data = &tmp; 1916 table->maxlen = sizeof(unsigned long); 1917 proc_doulongvec_minmax(table, write, buffer, length, ppos); 1918 1919 if (write) { 1920 spin_lock(&hugetlb_lock); 1921 h->nr_overcommit_huge_pages = tmp; 1922 spin_unlock(&hugetlb_lock); 1923 } 1924 1925 return 0; 1926} 1927 1928#endif /* CONFIG_SYSCTL */ 1929 1930void hugetlb_report_meminfo(struct seq_file *m) 1931{ 1932 struct hstate *h = &default_hstate; 1933 seq_printf(m, 1934 "HugePages_Total: %5lu\n" 1935 "HugePages_Free: %5lu\n" 1936 "HugePages_Rsvd: %5lu\n" 1937 "HugePages_Surp: %5lu\n" 1938 "Hugepagesize: %8lu kB\n", 1939 h->nr_huge_pages, 1940 h->free_huge_pages, 1941 h->resv_huge_pages, 1942 h->surplus_huge_pages, 1943 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 1944} 1945 1946int hugetlb_report_node_meminfo(int nid, char *buf) 1947{ 1948 struct hstate *h = &default_hstate; 1949 return sprintf(buf, 1950 "Node %d HugePages_Total: %5u\n" 1951 "Node %d HugePages_Free: %5u\n" 1952 "Node %d HugePages_Surp: %5u\n", 1953 nid, h->nr_huge_pages_node[nid], 1954 nid, h->free_huge_pages_node[nid], 1955 nid, h->surplus_huge_pages_node[nid]); 1956} 1957 1958/* Return the number pages of memory we physically have, in PAGE_SIZE units. */ 1959unsigned long hugetlb_total_pages(void) 1960{ 1961 struct hstate *h = &default_hstate; 1962 return h->nr_huge_pages * pages_per_huge_page(h); 1963} 1964 1965static int hugetlb_acct_memory(struct hstate *h, long delta) 1966{ 1967 int ret = -ENOMEM; 1968 1969 spin_lock(&hugetlb_lock); 1970 /* 1971 * When cpuset is configured, it breaks the strict hugetlb page 1972 * reservation as the accounting is done on a global variable. Such 1973 * reservation is completely rubbish in the presence of cpuset because 1974 * the reservation is not checked against page availability for the 1975 * current cpuset. Application can still potentially OOM'ed by kernel 1976 * with lack of free htlb page in cpuset that the task is in. 1977 * Attempt to enforce strict accounting with cpuset is almost 1978 * impossible (or too ugly) because cpuset is too fluid that 1979 * task or memory node can be dynamically moved between cpusets. 1980 * 1981 * The change of semantics for shared hugetlb mapping with cpuset is 1982 * undesirable. However, in order to preserve some of the semantics, 1983 * we fall back to check against current free page availability as 1984 * a best attempt and hopefully to minimize the impact of changing 1985 * semantics that cpuset has. 1986 */ 1987 if (delta > 0) { 1988 if (gather_surplus_pages(h, delta) < 0) 1989 goto out; 1990 1991 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { 1992 return_unused_surplus_pages(h, delta); 1993 goto out; 1994 } 1995 } 1996 1997 ret = 0; 1998 if (delta < 0) 1999 return_unused_surplus_pages(h, (unsigned long) -delta); 2000 2001out: 2002 spin_unlock(&hugetlb_lock); 2003 return ret; 2004} 2005 2006static void hugetlb_vm_op_open(struct vm_area_struct *vma) 2007{ 2008 struct resv_map *reservations = vma_resv_map(vma); 2009 2010 /* 2011 * This new VMA should share its siblings reservation map if present. 2012 * The VMA will only ever have a valid reservation map pointer where 2013 * it is being copied for another still existing VMA. As that VMA 2014 * has a reference to the reservation map it cannot dissappear until 2015 * after this open call completes. It is therefore safe to take a 2016 * new reference here without additional locking. 2017 */ 2018 if (reservations) 2019 kref_get(&reservations->refs); 2020} 2021 2022static void hugetlb_vm_op_close(struct vm_area_struct *vma) 2023{ 2024 struct hstate *h = hstate_vma(vma); 2025 struct resv_map *reservations = vma_resv_map(vma); 2026 unsigned long reserve; 2027 unsigned long start; 2028 unsigned long end; 2029 2030 if (reservations) { 2031 start = vma_hugecache_offset(h, vma, vma->vm_start); 2032 end = vma_hugecache_offset(h, vma, vma->vm_end); 2033 2034 reserve = (end - start) - 2035 region_count(&reservations->regions, start, end); 2036 2037 kref_put(&reservations->refs, resv_map_release); 2038 2039 if (reserve) { 2040 hugetlb_acct_memory(h, -reserve); 2041 hugetlb_put_quota(vma->vm_file->f_mapping, reserve); 2042 } 2043 } 2044} 2045 2046/* 2047 * We cannot handle pagefaults against hugetlb pages at all. They cause 2048 * handle_mm_fault() to try to instantiate regular-sized pages in the 2049 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get 2050 * this far. 2051 */ 2052static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 2053{ 2054 BUG(); 2055 return 0; 2056} 2057 2058const struct vm_operations_struct hugetlb_vm_ops = { 2059 .fault = hugetlb_vm_op_fault, 2060 .open = hugetlb_vm_op_open, 2061 .close = hugetlb_vm_op_close, 2062}; 2063 2064static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, 2065 int writable) 2066{ 2067 pte_t entry; 2068 2069 if (writable) { 2070 entry = 2071 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); 2072 } else { 2073 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot)); 2074 } 2075 entry = pte_mkyoung(entry); 2076 entry = pte_mkhuge(entry); 2077 2078 return entry; 2079} 2080 2081static void set_huge_ptep_writable(struct vm_area_struct *vma, 2082 unsigned long address, pte_t *ptep) 2083{ 2084 pte_t entry; 2085 2086 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep))); 2087 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) { 2088 update_mmu_cache(vma, address, entry); 2089 } 2090} 2091 2092 2093int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, 2094 struct vm_area_struct *vma) 2095{ 2096 pte_t *src_pte, *dst_pte, entry; 2097 struct page *ptepage; 2098 unsigned long addr; 2099 int cow; 2100 struct hstate *h = hstate_vma(vma); 2101 unsigned long sz = huge_page_size(h); 2102 2103 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 2104 2105 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { 2106 src_pte = huge_pte_offset(src, addr); 2107 if (!src_pte) 2108 continue; 2109 dst_pte = huge_pte_alloc(dst, addr, sz); 2110 if (!dst_pte) 2111 goto nomem; 2112 2113 /* If the pagetables are shared don't copy or take references */ 2114 if (dst_pte == src_pte) 2115 continue; 2116 2117 spin_lock(&dst->page_table_lock); 2118 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); 2119 if (!huge_pte_none(huge_ptep_get(src_pte))) { 2120 if (cow) 2121 huge_ptep_set_wrprotect(src, addr, src_pte); 2122 entry = huge_ptep_get(src_pte); 2123 ptepage = pte_page(entry); 2124 get_page(ptepage); 2125 set_huge_pte_at(dst, addr, dst_pte, entry); 2126 } 2127 spin_unlock(&src->page_table_lock); 2128 spin_unlock(&dst->page_table_lock); 2129 } 2130 return 0; 2131 2132nomem: 2133 return -ENOMEM; 2134} 2135 2136void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2137 unsigned long end, struct page *ref_page) 2138{ 2139 struct mm_struct *mm = vma->vm_mm; 2140 unsigned long address; 2141 pte_t *ptep; 2142 pte_t pte; 2143 struct page *page; 2144 struct page *tmp; 2145 struct hstate *h = hstate_vma(vma); 2146 unsigned long sz = huge_page_size(h); 2147 2148 /* 2149 * A page gathering list, protected by per file i_mmap_lock. The 2150 * lock is used to avoid list corruption from multiple unmapping 2151 * of the same page since we are using page->lru. 2152 */ 2153 LIST_HEAD(page_list); 2154 2155 WARN_ON(!is_vm_hugetlb_page(vma)); 2156 BUG_ON(start & ~huge_page_mask(h)); 2157 BUG_ON(end & ~huge_page_mask(h)); 2158 2159 mmu_notifier_invalidate_range_start(mm, start, end); 2160 spin_lock(&mm->page_table_lock); 2161 for (address = start; address < end; address += sz) { 2162 ptep = huge_pte_offset(mm, address); 2163 if (!ptep) 2164 continue; 2165 2166 if (huge_pmd_unshare(mm, &address, ptep)) 2167 continue; 2168 2169 /* 2170 * If a reference page is supplied, it is because a specific 2171 * page is being unmapped, not a range. Ensure the page we 2172 * are about to unmap is the actual page of interest. 2173 */ 2174 if (ref_page) { 2175 pte = huge_ptep_get(ptep); 2176 if (huge_pte_none(pte)) 2177 continue; 2178 page = pte_page(pte); 2179 if (page != ref_page) 2180 continue; 2181 2182 /* 2183 * Mark the VMA as having unmapped its page so that 2184 * future faults in this VMA will fail rather than 2185 * looking like data was lost 2186 */ 2187 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); 2188 } 2189 2190 pte = huge_ptep_get_and_clear(mm, address, ptep); 2191 if (huge_pte_none(pte)) 2192 continue; 2193 2194 page = pte_page(pte); 2195 if (pte_dirty(pte)) 2196 set_page_dirty(page); 2197 list_add(&page->lru, &page_list); 2198 } 2199 spin_unlock(&mm->page_table_lock); 2200 flush_tlb_range(vma, start, end); 2201 mmu_notifier_invalidate_range_end(mm, start, end); 2202 list_for_each_entry_safe(page, tmp, &page_list, lru) { 2203 list_del(&page->lru); 2204 put_page(page); 2205 } 2206} 2207 2208void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2209 unsigned long end, struct page *ref_page) 2210{ 2211 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); 2212 __unmap_hugepage_range(vma, start, end, ref_page); 2213 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); 2214} 2215 2216/* 2217 * This is called when the original mapper is failing to COW a MAP_PRIVATE 2218 * mappping it owns the reserve page for. The intention is to unmap the page 2219 * from other VMAs and let the children be SIGKILLed if they are faulting the 2220 * same region. 2221 */ 2222static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, 2223 struct page *page, unsigned long address) 2224{ 2225 struct hstate *h = hstate_vma(vma); 2226 struct vm_area_struct *iter_vma; 2227 struct address_space *mapping; 2228 struct prio_tree_iter iter; 2229 pgoff_t pgoff; 2230 2231 /* 2232 * vm_pgoff is in PAGE_SIZE units, hence the different calculation 2233 * from page cache lookup which is in HPAGE_SIZE units. 2234 */ 2235 address = address & huge_page_mask(h); 2236 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) 2237 + (vma->vm_pgoff >> PAGE_SHIFT); 2238 mapping = (struct address_space *)page_private(page); 2239 2240 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 2241 /* Do not unmap the current VMA */ 2242 if (iter_vma == vma) 2243 continue; 2244 2245 /* 2246 * Unmap the page from other VMAs without their own reserves. 2247 * They get marked to be SIGKILLed if they fault in these 2248 * areas. This is because a future no-page fault on this VMA 2249 * could insert a zeroed page instead of the data existing 2250 * from the time of fork. This would look like data corruption 2251 */ 2252 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2253 unmap_hugepage_range(iter_vma, 2254 address, address + huge_page_size(h), 2255 page); 2256 } 2257 2258 return 1; 2259} 2260 2261static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, 2262 unsigned long address, pte_t *ptep, pte_t pte, 2263 struct page *pagecache_page) 2264{ 2265 struct hstate *h = hstate_vma(vma); 2266 struct page *old_page, *new_page; 2267 int avoidcopy; 2268 int outside_reserve = 0; 2269 2270 old_page = pte_page(pte); 2271 2272retry_avoidcopy: 2273 /* If no-one else is actually using this page, avoid the copy 2274 * and just make the page writable */ 2275 avoidcopy = (page_count(old_page) == 1); 2276 if (avoidcopy) { 2277 set_huge_ptep_writable(vma, address, ptep); 2278 return 0; 2279 } 2280 2281 /* 2282 * If the process that created a MAP_PRIVATE mapping is about to 2283 * perform a COW due to a shared page count, attempt to satisfy 2284 * the allocation without using the existing reserves. The pagecache 2285 * page is used to determine if the reserve at this address was 2286 * consumed or not. If reserves were used, a partial faulted mapping 2287 * at the time of fork() could consume its reserves on COW instead 2288 * of the full address range. 2289 */ 2290 if (!(vma->vm_flags & VM_MAYSHARE) && 2291 is_vma_resv_set(vma, HPAGE_RESV_OWNER) && 2292 old_page != pagecache_page) 2293 outside_reserve = 1; 2294 2295 page_cache_get(old_page); 2296 2297 /* Drop page_table_lock as buddy allocator may be called */ 2298 spin_unlock(&mm->page_table_lock); 2299 new_page = alloc_huge_page(vma, address, outside_reserve); 2300 2301 if (IS_ERR(new_page)) { 2302 page_cache_release(old_page); 2303 2304 /* 2305 * If a process owning a MAP_PRIVATE mapping fails to COW, 2306 * it is due to references held by a child and an insufficient 2307 * huge page pool. To guarantee the original mappers 2308 * reliability, unmap the page from child processes. The child 2309 * may get SIGKILLed if it later faults. 2310 */ 2311 if (outside_reserve) { 2312 BUG_ON(huge_pte_none(pte)); 2313 if (unmap_ref_private(mm, vma, old_page, address)) { 2314 BUG_ON(page_count(old_page) != 1); 2315 BUG_ON(huge_pte_none(pte)); 2316 spin_lock(&mm->page_table_lock); 2317 goto retry_avoidcopy; 2318 } 2319 WARN_ON_ONCE(1); 2320 } 2321 2322 /* Caller expects lock to be held */ 2323 spin_lock(&mm->page_table_lock); 2324 return -PTR_ERR(new_page); 2325 } 2326 2327 copy_huge_page(new_page, old_page, address, vma); 2328 __SetPageUptodate(new_page); 2329 2330 /* 2331 * Retake the page_table_lock to check for racing updates 2332 * before the page tables are altered 2333 */ 2334 spin_lock(&mm->page_table_lock); 2335 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2336 if (likely(pte_same(huge_ptep_get(ptep), pte))) { 2337 /* Break COW */ 2338 huge_ptep_clear_flush(vma, address, ptep); 2339 set_huge_pte_at(mm, address, ptep, 2340 make_huge_pte(vma, new_page, 1)); 2341 /* Make the old page be freed below */ 2342 new_page = old_page; 2343 } 2344 page_cache_release(new_page); 2345 page_cache_release(old_page); 2346 return 0; 2347} 2348 2349/* Return the pagecache page at a given address within a VMA */ 2350static struct page *hugetlbfs_pagecache_page(struct hstate *h, 2351 struct vm_area_struct *vma, unsigned long address) 2352{ 2353 struct address_space *mapping; 2354 pgoff_t idx; 2355 2356 mapping = vma->vm_file->f_mapping; 2357 idx = vma_hugecache_offset(h, vma, address); 2358 2359 return find_lock_page(mapping, idx); 2360} 2361 2362/* 2363 * Return whether there is a pagecache page to back given address within VMA. 2364 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. 2365 */ 2366static bool hugetlbfs_pagecache_present(struct hstate *h, 2367 struct vm_area_struct *vma, unsigned long address) 2368{ 2369 struct address_space *mapping; 2370 pgoff_t idx; 2371 struct page *page; 2372 2373 mapping = vma->vm_file->f_mapping; 2374 idx = vma_hugecache_offset(h, vma, address); 2375 2376 page = find_get_page(mapping, idx); 2377 if (page) 2378 put_page(page); 2379 return page != NULL; 2380} 2381 2382static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2383 unsigned long address, pte_t *ptep, unsigned int flags) 2384{ 2385 struct hstate *h = hstate_vma(vma); 2386 int ret = VM_FAULT_SIGBUS; 2387 pgoff_t idx; 2388 unsigned long size; 2389 struct page *page; 2390 struct address_space *mapping; 2391 pte_t new_pte; 2392 2393 /* 2394 * Currently, we are forced to kill the process in the event the 2395 * original mapper has unmapped pages from the child due to a failed 2396 * COW. Warn that such a situation has occured as it may not be obvious 2397 */ 2398 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { 2399 printk(KERN_WARNING 2400 "PID %d killed due to inadequate hugepage pool\n", 2401 current->pid); 2402 return ret; 2403 } 2404 2405 mapping = vma->vm_file->f_mapping; 2406 idx = vma_hugecache_offset(h, vma, address); 2407 2408 /* 2409 * Use page lock to guard against racing truncation 2410 * before we get page_table_lock. 2411 */ 2412retry: 2413 page = find_lock_page(mapping, idx); 2414 if (!page) { 2415 size = i_size_read(mapping->host) >> huge_page_shift(h); 2416 if (idx >= size) 2417 goto out; 2418 page = alloc_huge_page(vma, address, 0); 2419 if (IS_ERR(page)) { 2420 ret = -PTR_ERR(page); 2421 goto out; 2422 } 2423 clear_huge_page(page, address, huge_page_size(h)); 2424 __SetPageUptodate(page); 2425 2426 if (vma->vm_flags & VM_MAYSHARE) { 2427 int err; 2428 struct inode *inode = mapping->host; 2429 2430 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); 2431 if (err) { 2432 put_page(page); 2433 if (err == -EEXIST) 2434 goto retry; 2435 goto out; 2436 } 2437 2438 spin_lock(&inode->i_lock); 2439 inode->i_blocks += blocks_per_huge_page(h); 2440 spin_unlock(&inode->i_lock); 2441 } else 2442 lock_page(page); 2443 } 2444 2445 /* 2446 * If we are going to COW a private mapping later, we examine the 2447 * pending reservations for this page now. This will ensure that 2448 * any allocations necessary to record that reservation occur outside 2449 * the spinlock. 2450 */ 2451 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 2452 if (vma_needs_reservation(h, vma, address) < 0) { 2453 ret = VM_FAULT_OOM; 2454 goto backout_unlocked; 2455 } 2456 2457 spin_lock(&mm->page_table_lock); 2458 size = i_size_read(mapping->host) >> huge_page_shift(h); 2459 if (idx >= size) 2460 goto backout; 2461 2462 ret = 0; 2463 if (!huge_pte_none(huge_ptep_get(ptep))) 2464 goto backout; 2465 2466 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) 2467 && (vma->vm_flags & VM_SHARED))); 2468 set_huge_pte_at(mm, address, ptep, new_pte); 2469 2470 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 2471 /* Optimization, do the COW without a second fault */ 2472 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); 2473 } 2474 2475 spin_unlock(&mm->page_table_lock); 2476 unlock_page(page); 2477out: 2478 return ret; 2479 2480backout: 2481 spin_unlock(&mm->page_table_lock); 2482backout_unlocked: 2483 unlock_page(page); 2484 put_page(page); 2485 goto out; 2486} 2487 2488int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2489 unsigned long address, unsigned int flags) 2490{ 2491 pte_t *ptep; 2492 pte_t entry; 2493 int ret; 2494 struct page *pagecache_page = NULL; 2495 static DEFINE_MUTEX(hugetlb_instantiation_mutex); 2496 struct hstate *h = hstate_vma(vma); 2497 2498 ptep = huge_pte_alloc(mm, address, huge_page_size(h)); 2499 if (!ptep) 2500 return VM_FAULT_OOM; 2501 2502 /* 2503 * Serialize hugepage allocation and instantiation, so that we don't 2504 * get spurious allocation failures if two CPUs race to instantiate 2505 * the same page in the page cache. 2506 */ 2507 mutex_lock(&hugetlb_instantiation_mutex); 2508 entry = huge_ptep_get(ptep); 2509 if (huge_pte_none(entry)) { 2510 ret = hugetlb_no_page(mm, vma, address, ptep, flags); 2511 goto out_mutex; 2512 } 2513 2514 ret = 0; 2515 2516 /* 2517 * If we are going to COW the mapping later, we examine the pending 2518 * reservations for this page now. This will ensure that any 2519 * allocations necessary to record that reservation occur outside the 2520 * spinlock. For private mappings, we also lookup the pagecache 2521 * page now as it is used to determine if a reservation has been 2522 * consumed. 2523 */ 2524 if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) { 2525 if (vma_needs_reservation(h, vma, address) < 0) { 2526 ret = VM_FAULT_OOM; 2527 goto out_mutex; 2528 } 2529 2530 if (!(vma->vm_flags & VM_MAYSHARE)) 2531 pagecache_page = hugetlbfs_pagecache_page(h, 2532 vma, address); 2533 } 2534 2535 spin_lock(&mm->page_table_lock); 2536 /* Check for a racing update before calling hugetlb_cow */ 2537 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 2538 goto out_page_table_lock; 2539 2540 2541 if (flags & FAULT_FLAG_WRITE) { 2542 if (!pte_write(entry)) { 2543 ret = hugetlb_cow(mm, vma, address, ptep, entry, 2544 pagecache_page); 2545 goto out_page_table_lock; 2546 } 2547 entry = pte_mkdirty(entry); 2548 } 2549 entry = pte_mkyoung(entry); 2550 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 2551 flags & FAULT_FLAG_WRITE)) 2552 update_mmu_cache(vma, address, entry); 2553 2554out_page_table_lock: 2555 spin_unlock(&mm->page_table_lock); 2556 2557 if (pagecache_page) { 2558 unlock_page(pagecache_page); 2559 put_page(pagecache_page); 2560 } 2561 2562out_mutex: 2563 mutex_unlock(&hugetlb_instantiation_mutex); 2564 2565 return ret; 2566} 2567 2568/* Can be overriden by architectures */ 2569__attribute__((weak)) struct page * 2570follow_huge_pud(struct mm_struct *mm, unsigned long address, 2571 pud_t *pud, int write) 2572{ 2573 BUG(); 2574 return NULL; 2575} 2576 2577int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 2578 struct page **pages, struct vm_area_struct **vmas, 2579 unsigned long *position, int *length, int i, 2580 unsigned int flags) 2581{ 2582 unsigned long pfn_offset; 2583 unsigned long vaddr = *position; 2584 int remainder = *length; 2585 struct hstate *h = hstate_vma(vma); 2586 2587 spin_lock(&mm->page_table_lock); 2588 while (vaddr < vma->vm_end && remainder) { 2589 pte_t *pte; 2590 int absent; 2591 struct page *page; 2592 2593 /* 2594 * Some archs (sparc64, sh*) have multiple pte_ts to 2595 * each hugepage. We have to make sure we get the 2596 * first, for the page indexing below to work. 2597 */ 2598 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); 2599 absent = !pte || huge_pte_none(huge_ptep_get(pte)); 2600 2601 /* 2602 * When coredumping, it suits get_dump_page if we just return 2603 * an error where there's an empty slot with no huge pagecache 2604 * to back it. This way, we avoid allocating a hugepage, and 2605 * the sparse dumpfile avoids allocating disk blocks, but its 2606 * huge holes still show up with zeroes where they need to be. 2607 */ 2608 if (absent && (flags & FOLL_DUMP) && 2609 !hugetlbfs_pagecache_present(h, vma, vaddr)) { 2610 remainder = 0; 2611 break; 2612 } 2613 2614 if (absent || 2615 ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { 2616 int ret; 2617 2618 spin_unlock(&mm->page_table_lock); 2619 ret = hugetlb_fault(mm, vma, vaddr, 2620 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); 2621 spin_lock(&mm->page_table_lock); 2622 if (!(ret & VM_FAULT_ERROR)) 2623 continue; 2624 2625 remainder = 0; 2626 break; 2627 } 2628 2629 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; 2630 page = pte_page(huge_ptep_get(pte)); 2631same_page: 2632 if (pages) { 2633 pages[i] = mem_map_offset(page, pfn_offset); 2634 get_page(pages[i]); 2635 } 2636 2637 if (vmas) 2638 vmas[i] = vma; 2639 2640 vaddr += PAGE_SIZE; 2641 ++pfn_offset; 2642 --remainder; 2643 ++i; 2644 if (vaddr < vma->vm_end && remainder && 2645 pfn_offset < pages_per_huge_page(h)) { 2646 /* 2647 * We use pfn_offset to avoid touching the pageframes 2648 * of this compound page. 2649 */ 2650 goto same_page; 2651 } 2652 } 2653 spin_unlock(&mm->page_table_lock); 2654 *length = remainder; 2655 *position = vaddr; 2656 2657 return i ? i : -EFAULT; 2658} 2659 2660void hugetlb_change_protection(struct vm_area_struct *vma, 2661 unsigned long address, unsigned long end, pgprot_t newprot) 2662{ 2663 struct mm_struct *mm = vma->vm_mm; 2664 unsigned long start = address; 2665 pte_t *ptep; 2666 pte_t pte; 2667 struct hstate *h = hstate_vma(vma); 2668 2669 BUG_ON(address >= end); 2670 flush_cache_range(vma, address, end); 2671 2672 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); 2673 spin_lock(&mm->page_table_lock); 2674 for (; address < end; address += huge_page_size(h)) { 2675 ptep = huge_pte_offset(mm, address); 2676 if (!ptep) 2677 continue; 2678 if (huge_pmd_unshare(mm, &address, ptep)) 2679 continue; 2680 if (!huge_pte_none(huge_ptep_get(ptep))) { 2681 pte = huge_ptep_get_and_clear(mm, address, ptep); 2682 pte = pte_mkhuge(pte_modify(pte, newprot)); 2683 set_huge_pte_at(mm, address, ptep, pte); 2684 } 2685 } 2686 spin_unlock(&mm->page_table_lock); 2687 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); 2688 2689 flush_tlb_range(vma, start, end); 2690} 2691 2692int hugetlb_reserve_pages(struct inode *inode, 2693 long from, long to, 2694 struct vm_area_struct *vma, 2695 int acctflag) 2696{ 2697 long ret, chg; 2698 struct hstate *h = hstate_inode(inode); 2699 2700 /* 2701 * Only apply hugepage reservation if asked. At fault time, an 2702 * attempt will be made for VM_NORESERVE to allocate a page 2703 * and filesystem quota without using reserves 2704 */ 2705 if (acctflag & VM_NORESERVE) 2706 return 0; 2707 2708 /* 2709 * Shared mappings base their reservation on the number of pages that 2710 * are already allocated on behalf of the file. Private mappings need 2711 * to reserve the full area even if read-only as mprotect() may be 2712 * called to make the mapping read-write. Assume !vma is a shm mapping 2713 */ 2714 if (!vma || vma->vm_flags & VM_MAYSHARE) 2715 chg = region_chg(&inode->i_mapping->private_list, from, to); 2716 else { 2717 struct resv_map *resv_map = resv_map_alloc(); 2718 if (!resv_map) 2719 return -ENOMEM; 2720 2721 chg = to - from; 2722 2723 set_vma_resv_map(vma, resv_map); 2724 set_vma_resv_flags(vma, HPAGE_RESV_OWNER); 2725 } 2726 2727 if (chg < 0) 2728 return chg; 2729 2730 /* There must be enough filesystem quota for the mapping */ 2731 if (hugetlb_get_quota(inode->i_mapping, chg)) 2732 return -ENOSPC; 2733 2734 /* 2735 * Check enough hugepages are available for the reservation. 2736 * Hand back the quota if there are not 2737 */ 2738 ret = hugetlb_acct_memory(h, chg); 2739 if (ret < 0) { 2740 hugetlb_put_quota(inode->i_mapping, chg); 2741 return ret; 2742 } 2743 2744 /* 2745 * Account for the reservations made. Shared mappings record regions 2746 * that have reservations as they are shared by multiple VMAs. 2747 * When the last VMA disappears, the region map says how much 2748 * the reservation was and the page cache tells how much of 2749 * the reservation was consumed. Private mappings are per-VMA and 2750 * only the consumed reservations are tracked. When the VMA 2751 * disappears, the original reservation is the VMA size and the 2752 * consumed reservations are stored in the map. Hence, nothing 2753 * else has to be done for private mappings here 2754 */ 2755 if (!vma || vma->vm_flags & VM_MAYSHARE) 2756 region_add(&inode->i_mapping->private_list, from, to); 2757 return 0; 2758} 2759 2760void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) 2761{ 2762 struct hstate *h = hstate_inode(inode); 2763 long chg = region_truncate(&inode->i_mapping->private_list, offset); 2764 2765 spin_lock(&inode->i_lock); 2766 inode->i_blocks -= (blocks_per_huge_page(h) * freed); 2767 spin_unlock(&inode->i_lock); 2768 2769 hugetlb_put_quota(inode->i_mapping, (chg - freed)); 2770 hugetlb_acct_memory(h, -(chg - freed)); 2771} 2772