hugetlb.c revision c3f38a38715e9b4e7b1dda6840a1375f6894744d
1/* 2 * Generic hugetlb support. 3 * (C) William Irwin, April 2004 4 */ 5#include <linux/list.h> 6#include <linux/init.h> 7#include <linux/module.h> 8#include <linux/mm.h> 9#include <linux/seq_file.h> 10#include <linux/sysctl.h> 11#include <linux/highmem.h> 12#include <linux/mmu_notifier.h> 13#include <linux/nodemask.h> 14#include <linux/pagemap.h> 15#include <linux/mempolicy.h> 16#include <linux/cpuset.h> 17#include <linux/mutex.h> 18#include <linux/bootmem.h> 19#include <linux/sysfs.h> 20#include <linux/slab.h> 21#include <linux/rmap.h> 22#include <linux/swap.h> 23#include <linux/swapops.h> 24 25#include <asm/page.h> 26#include <asm/pgtable.h> 27#include <asm/tlb.h> 28 29#include <linux/io.h> 30#include <linux/hugetlb.h> 31#include <linux/node.h> 32#include "internal.h" 33 34const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; 35static gfp_t htlb_alloc_mask = GFP_HIGHUSER; 36unsigned long hugepages_treat_as_movable; 37 38int hugetlb_max_hstate __read_mostly; 39unsigned int default_hstate_idx; 40struct hstate hstates[HUGE_MAX_HSTATE]; 41 42__initdata LIST_HEAD(huge_boot_pages); 43 44/* for command line parsing */ 45static struct hstate * __initdata parsed_hstate; 46static unsigned long __initdata default_hstate_max_huge_pages; 47static unsigned long __initdata default_hstate_size; 48 49/* 50 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages 51 */ 52DEFINE_SPINLOCK(hugetlb_lock); 53 54static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) 55{ 56 bool free = (spool->count == 0) && (spool->used_hpages == 0); 57 58 spin_unlock(&spool->lock); 59 60 /* If no pages are used, and no other handles to the subpool 61 * remain, free the subpool the subpool remain */ 62 if (free) 63 kfree(spool); 64} 65 66struct hugepage_subpool *hugepage_new_subpool(long nr_blocks) 67{ 68 struct hugepage_subpool *spool; 69 70 spool = kmalloc(sizeof(*spool), GFP_KERNEL); 71 if (!spool) 72 return NULL; 73 74 spin_lock_init(&spool->lock); 75 spool->count = 1; 76 spool->max_hpages = nr_blocks; 77 spool->used_hpages = 0; 78 79 return spool; 80} 81 82void hugepage_put_subpool(struct hugepage_subpool *spool) 83{ 84 spin_lock(&spool->lock); 85 BUG_ON(!spool->count); 86 spool->count--; 87 unlock_or_release_subpool(spool); 88} 89 90static int hugepage_subpool_get_pages(struct hugepage_subpool *spool, 91 long delta) 92{ 93 int ret = 0; 94 95 if (!spool) 96 return 0; 97 98 spin_lock(&spool->lock); 99 if ((spool->used_hpages + delta) <= spool->max_hpages) { 100 spool->used_hpages += delta; 101 } else { 102 ret = -ENOMEM; 103 } 104 spin_unlock(&spool->lock); 105 106 return ret; 107} 108 109static void hugepage_subpool_put_pages(struct hugepage_subpool *spool, 110 long delta) 111{ 112 if (!spool) 113 return; 114 115 spin_lock(&spool->lock); 116 spool->used_hpages -= delta; 117 /* If hugetlbfs_put_super couldn't free spool due to 118 * an outstanding quota reference, free it now. */ 119 unlock_or_release_subpool(spool); 120} 121 122static inline struct hugepage_subpool *subpool_inode(struct inode *inode) 123{ 124 return HUGETLBFS_SB(inode->i_sb)->spool; 125} 126 127static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma) 128{ 129 return subpool_inode(vma->vm_file->f_dentry->d_inode); 130} 131 132/* 133 * Region tracking -- allows tracking of reservations and instantiated pages 134 * across the pages in a mapping. 135 * 136 * The region data structures are protected by a combination of the mmap_sem 137 * and the hugetlb_instantion_mutex. To access or modify a region the caller 138 * must either hold the mmap_sem for write, or the mmap_sem for read and 139 * the hugetlb_instantiation mutex: 140 * 141 * down_write(&mm->mmap_sem); 142 * or 143 * down_read(&mm->mmap_sem); 144 * mutex_lock(&hugetlb_instantiation_mutex); 145 */ 146struct file_region { 147 struct list_head link; 148 long from; 149 long to; 150}; 151 152static long region_add(struct list_head *head, long f, long t) 153{ 154 struct file_region *rg, *nrg, *trg; 155 156 /* Locate the region we are either in or before. */ 157 list_for_each_entry(rg, head, link) 158 if (f <= rg->to) 159 break; 160 161 /* Round our left edge to the current segment if it encloses us. */ 162 if (f > rg->from) 163 f = rg->from; 164 165 /* Check for and consume any regions we now overlap with. */ 166 nrg = rg; 167 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 168 if (&rg->link == head) 169 break; 170 if (rg->from > t) 171 break; 172 173 /* If this area reaches higher then extend our area to 174 * include it completely. If this is not the first area 175 * which we intend to reuse, free it. */ 176 if (rg->to > t) 177 t = rg->to; 178 if (rg != nrg) { 179 list_del(&rg->link); 180 kfree(rg); 181 } 182 } 183 nrg->from = f; 184 nrg->to = t; 185 return 0; 186} 187 188static long region_chg(struct list_head *head, long f, long t) 189{ 190 struct file_region *rg, *nrg; 191 long chg = 0; 192 193 /* Locate the region we are before or in. */ 194 list_for_each_entry(rg, head, link) 195 if (f <= rg->to) 196 break; 197 198 /* If we are below the current region then a new region is required. 199 * Subtle, allocate a new region at the position but make it zero 200 * size such that we can guarantee to record the reservation. */ 201 if (&rg->link == head || t < rg->from) { 202 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); 203 if (!nrg) 204 return -ENOMEM; 205 nrg->from = f; 206 nrg->to = f; 207 INIT_LIST_HEAD(&nrg->link); 208 list_add(&nrg->link, rg->link.prev); 209 210 return t - f; 211 } 212 213 /* Round our left edge to the current segment if it encloses us. */ 214 if (f > rg->from) 215 f = rg->from; 216 chg = t - f; 217 218 /* Check for and consume any regions we now overlap with. */ 219 list_for_each_entry(rg, rg->link.prev, link) { 220 if (&rg->link == head) 221 break; 222 if (rg->from > t) 223 return chg; 224 225 /* We overlap with this area, if it extends further than 226 * us then we must extend ourselves. Account for its 227 * existing reservation. */ 228 if (rg->to > t) { 229 chg += rg->to - t; 230 t = rg->to; 231 } 232 chg -= rg->to - rg->from; 233 } 234 return chg; 235} 236 237static long region_truncate(struct list_head *head, long end) 238{ 239 struct file_region *rg, *trg; 240 long chg = 0; 241 242 /* Locate the region we are either in or before. */ 243 list_for_each_entry(rg, head, link) 244 if (end <= rg->to) 245 break; 246 if (&rg->link == head) 247 return 0; 248 249 /* If we are in the middle of a region then adjust it. */ 250 if (end > rg->from) { 251 chg = rg->to - end; 252 rg->to = end; 253 rg = list_entry(rg->link.next, typeof(*rg), link); 254 } 255 256 /* Drop any remaining regions. */ 257 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 258 if (&rg->link == head) 259 break; 260 chg += rg->to - rg->from; 261 list_del(&rg->link); 262 kfree(rg); 263 } 264 return chg; 265} 266 267static long region_count(struct list_head *head, long f, long t) 268{ 269 struct file_region *rg; 270 long chg = 0; 271 272 /* Locate each segment we overlap with, and count that overlap. */ 273 list_for_each_entry(rg, head, link) { 274 long seg_from; 275 long seg_to; 276 277 if (rg->to <= f) 278 continue; 279 if (rg->from >= t) 280 break; 281 282 seg_from = max(rg->from, f); 283 seg_to = min(rg->to, t); 284 285 chg += seg_to - seg_from; 286 } 287 288 return chg; 289} 290 291/* 292 * Convert the address within this vma to the page offset within 293 * the mapping, in pagecache page units; huge pages here. 294 */ 295static pgoff_t vma_hugecache_offset(struct hstate *h, 296 struct vm_area_struct *vma, unsigned long address) 297{ 298 return ((address - vma->vm_start) >> huge_page_shift(h)) + 299 (vma->vm_pgoff >> huge_page_order(h)); 300} 301 302pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 303 unsigned long address) 304{ 305 return vma_hugecache_offset(hstate_vma(vma), vma, address); 306} 307 308/* 309 * Return the size of the pages allocated when backing a VMA. In the majority 310 * cases this will be same size as used by the page table entries. 311 */ 312unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) 313{ 314 struct hstate *hstate; 315 316 if (!is_vm_hugetlb_page(vma)) 317 return PAGE_SIZE; 318 319 hstate = hstate_vma(vma); 320 321 return 1UL << (hstate->order + PAGE_SHIFT); 322} 323EXPORT_SYMBOL_GPL(vma_kernel_pagesize); 324 325/* 326 * Return the page size being used by the MMU to back a VMA. In the majority 327 * of cases, the page size used by the kernel matches the MMU size. On 328 * architectures where it differs, an architecture-specific version of this 329 * function is required. 330 */ 331#ifndef vma_mmu_pagesize 332unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) 333{ 334 return vma_kernel_pagesize(vma); 335} 336#endif 337 338/* 339 * Flags for MAP_PRIVATE reservations. These are stored in the bottom 340 * bits of the reservation map pointer, which are always clear due to 341 * alignment. 342 */ 343#define HPAGE_RESV_OWNER (1UL << 0) 344#define HPAGE_RESV_UNMAPPED (1UL << 1) 345#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) 346 347/* 348 * These helpers are used to track how many pages are reserved for 349 * faults in a MAP_PRIVATE mapping. Only the process that called mmap() 350 * is guaranteed to have their future faults succeed. 351 * 352 * With the exception of reset_vma_resv_huge_pages() which is called at fork(), 353 * the reserve counters are updated with the hugetlb_lock held. It is safe 354 * to reset the VMA at fork() time as it is not in use yet and there is no 355 * chance of the global counters getting corrupted as a result of the values. 356 * 357 * The private mapping reservation is represented in a subtly different 358 * manner to a shared mapping. A shared mapping has a region map associated 359 * with the underlying file, this region map represents the backing file 360 * pages which have ever had a reservation assigned which this persists even 361 * after the page is instantiated. A private mapping has a region map 362 * associated with the original mmap which is attached to all VMAs which 363 * reference it, this region map represents those offsets which have consumed 364 * reservation ie. where pages have been instantiated. 365 */ 366static unsigned long get_vma_private_data(struct vm_area_struct *vma) 367{ 368 return (unsigned long)vma->vm_private_data; 369} 370 371static void set_vma_private_data(struct vm_area_struct *vma, 372 unsigned long value) 373{ 374 vma->vm_private_data = (void *)value; 375} 376 377struct resv_map { 378 struct kref refs; 379 struct list_head regions; 380}; 381 382static struct resv_map *resv_map_alloc(void) 383{ 384 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); 385 if (!resv_map) 386 return NULL; 387 388 kref_init(&resv_map->refs); 389 INIT_LIST_HEAD(&resv_map->regions); 390 391 return resv_map; 392} 393 394static void resv_map_release(struct kref *ref) 395{ 396 struct resv_map *resv_map = container_of(ref, struct resv_map, refs); 397 398 /* Clear out any active regions before we release the map. */ 399 region_truncate(&resv_map->regions, 0); 400 kfree(resv_map); 401} 402 403static struct resv_map *vma_resv_map(struct vm_area_struct *vma) 404{ 405 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 406 if (!(vma->vm_flags & VM_MAYSHARE)) 407 return (struct resv_map *)(get_vma_private_data(vma) & 408 ~HPAGE_RESV_MASK); 409 return NULL; 410} 411 412static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) 413{ 414 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 415 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 416 417 set_vma_private_data(vma, (get_vma_private_data(vma) & 418 HPAGE_RESV_MASK) | (unsigned long)map); 419} 420 421static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) 422{ 423 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 424 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 425 426 set_vma_private_data(vma, get_vma_private_data(vma) | flags); 427} 428 429static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) 430{ 431 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 432 433 return (get_vma_private_data(vma) & flag) != 0; 434} 435 436/* Decrement the reserved pages in the hugepage pool by one */ 437static void decrement_hugepage_resv_vma(struct hstate *h, 438 struct vm_area_struct *vma) 439{ 440 if (vma->vm_flags & VM_NORESERVE) 441 return; 442 443 if (vma->vm_flags & VM_MAYSHARE) { 444 /* Shared mappings always use reserves */ 445 h->resv_huge_pages--; 446 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 447 /* 448 * Only the process that called mmap() has reserves for 449 * private mappings. 450 */ 451 h->resv_huge_pages--; 452 } 453} 454 455/* Reset counters to 0 and clear all HPAGE_RESV_* flags */ 456void reset_vma_resv_huge_pages(struct vm_area_struct *vma) 457{ 458 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 459 if (!(vma->vm_flags & VM_MAYSHARE)) 460 vma->vm_private_data = (void *)0; 461} 462 463/* Returns true if the VMA has associated reserve pages */ 464static int vma_has_reserves(struct vm_area_struct *vma) 465{ 466 if (vma->vm_flags & VM_MAYSHARE) 467 return 1; 468 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 469 return 1; 470 return 0; 471} 472 473static void copy_gigantic_page(struct page *dst, struct page *src) 474{ 475 int i; 476 struct hstate *h = page_hstate(src); 477 struct page *dst_base = dst; 478 struct page *src_base = src; 479 480 for (i = 0; i < pages_per_huge_page(h); ) { 481 cond_resched(); 482 copy_highpage(dst, src); 483 484 i++; 485 dst = mem_map_next(dst, dst_base, i); 486 src = mem_map_next(src, src_base, i); 487 } 488} 489 490void copy_huge_page(struct page *dst, struct page *src) 491{ 492 int i; 493 struct hstate *h = page_hstate(src); 494 495 if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { 496 copy_gigantic_page(dst, src); 497 return; 498 } 499 500 might_sleep(); 501 for (i = 0; i < pages_per_huge_page(h); i++) { 502 cond_resched(); 503 copy_highpage(dst + i, src + i); 504 } 505} 506 507static void enqueue_huge_page(struct hstate *h, struct page *page) 508{ 509 int nid = page_to_nid(page); 510 list_move(&page->lru, &h->hugepage_freelists[nid]); 511 h->free_huge_pages++; 512 h->free_huge_pages_node[nid]++; 513} 514 515static struct page *dequeue_huge_page_node(struct hstate *h, int nid) 516{ 517 struct page *page; 518 519 if (list_empty(&h->hugepage_freelists[nid])) 520 return NULL; 521 page = list_entry(h->hugepage_freelists[nid].next, struct page, lru); 522 list_move(&page->lru, &h->hugepage_activelist); 523 set_page_refcounted(page); 524 h->free_huge_pages--; 525 h->free_huge_pages_node[nid]--; 526 return page; 527} 528 529static struct page *dequeue_huge_page_vma(struct hstate *h, 530 struct vm_area_struct *vma, 531 unsigned long address, int avoid_reserve) 532{ 533 struct page *page = NULL; 534 struct mempolicy *mpol; 535 nodemask_t *nodemask; 536 struct zonelist *zonelist; 537 struct zone *zone; 538 struct zoneref *z; 539 unsigned int cpuset_mems_cookie; 540 541retry_cpuset: 542 cpuset_mems_cookie = get_mems_allowed(); 543 zonelist = huge_zonelist(vma, address, 544 htlb_alloc_mask, &mpol, &nodemask); 545 /* 546 * A child process with MAP_PRIVATE mappings created by their parent 547 * have no page reserves. This check ensures that reservations are 548 * not "stolen". The child may still get SIGKILLed 549 */ 550 if (!vma_has_reserves(vma) && 551 h->free_huge_pages - h->resv_huge_pages == 0) 552 goto err; 553 554 /* If reserves cannot be used, ensure enough pages are in the pool */ 555 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) 556 goto err; 557 558 for_each_zone_zonelist_nodemask(zone, z, zonelist, 559 MAX_NR_ZONES - 1, nodemask) { 560 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) { 561 page = dequeue_huge_page_node(h, zone_to_nid(zone)); 562 if (page) { 563 if (!avoid_reserve) 564 decrement_hugepage_resv_vma(h, vma); 565 break; 566 } 567 } 568 } 569 570 mpol_cond_put(mpol); 571 if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page)) 572 goto retry_cpuset; 573 return page; 574 575err: 576 mpol_cond_put(mpol); 577 return NULL; 578} 579 580static void update_and_free_page(struct hstate *h, struct page *page) 581{ 582 int i; 583 584 VM_BUG_ON(h->order >= MAX_ORDER); 585 586 h->nr_huge_pages--; 587 h->nr_huge_pages_node[page_to_nid(page)]--; 588 for (i = 0; i < pages_per_huge_page(h); i++) { 589 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 590 1 << PG_referenced | 1 << PG_dirty | 591 1 << PG_active | 1 << PG_reserved | 592 1 << PG_private | 1 << PG_writeback); 593 } 594 set_compound_page_dtor(page, NULL); 595 set_page_refcounted(page); 596 arch_release_hugepage(page); 597 __free_pages(page, huge_page_order(h)); 598} 599 600struct hstate *size_to_hstate(unsigned long size) 601{ 602 struct hstate *h; 603 604 for_each_hstate(h) { 605 if (huge_page_size(h) == size) 606 return h; 607 } 608 return NULL; 609} 610 611static void free_huge_page(struct page *page) 612{ 613 /* 614 * Can't pass hstate in here because it is called from the 615 * compound page destructor. 616 */ 617 struct hstate *h = page_hstate(page); 618 int nid = page_to_nid(page); 619 struct hugepage_subpool *spool = 620 (struct hugepage_subpool *)page_private(page); 621 622 set_page_private(page, 0); 623 page->mapping = NULL; 624 BUG_ON(page_count(page)); 625 BUG_ON(page_mapcount(page)); 626 627 spin_lock(&hugetlb_lock); 628 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { 629 /* remove the page from active list */ 630 list_del(&page->lru); 631 update_and_free_page(h, page); 632 h->surplus_huge_pages--; 633 h->surplus_huge_pages_node[nid]--; 634 } else { 635 enqueue_huge_page(h, page); 636 } 637 spin_unlock(&hugetlb_lock); 638 hugepage_subpool_put_pages(spool, 1); 639} 640 641static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) 642{ 643 INIT_LIST_HEAD(&page->lru); 644 set_compound_page_dtor(page, free_huge_page); 645 spin_lock(&hugetlb_lock); 646 h->nr_huge_pages++; 647 h->nr_huge_pages_node[nid]++; 648 spin_unlock(&hugetlb_lock); 649 put_page(page); /* free it into the hugepage allocator */ 650} 651 652static void prep_compound_gigantic_page(struct page *page, unsigned long order) 653{ 654 int i; 655 int nr_pages = 1 << order; 656 struct page *p = page + 1; 657 658 /* we rely on prep_new_huge_page to set the destructor */ 659 set_compound_order(page, order); 660 __SetPageHead(page); 661 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { 662 __SetPageTail(p); 663 set_page_count(p, 0); 664 p->first_page = page; 665 } 666} 667 668int PageHuge(struct page *page) 669{ 670 compound_page_dtor *dtor; 671 672 if (!PageCompound(page)) 673 return 0; 674 675 page = compound_head(page); 676 dtor = get_compound_page_dtor(page); 677 678 return dtor == free_huge_page; 679} 680EXPORT_SYMBOL_GPL(PageHuge); 681 682static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 683{ 684 struct page *page; 685 686 if (h->order >= MAX_ORDER) 687 return NULL; 688 689 page = alloc_pages_exact_node(nid, 690 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 691 __GFP_REPEAT|__GFP_NOWARN, 692 huge_page_order(h)); 693 if (page) { 694 if (arch_prepare_hugepage(page)) { 695 __free_pages(page, huge_page_order(h)); 696 return NULL; 697 } 698 prep_new_huge_page(h, page, nid); 699 } 700 701 return page; 702} 703 704/* 705 * common helper functions for hstate_next_node_to_{alloc|free}. 706 * We may have allocated or freed a huge page based on a different 707 * nodes_allowed previously, so h->next_node_to_{alloc|free} might 708 * be outside of *nodes_allowed. Ensure that we use an allowed 709 * node for alloc or free. 710 */ 711static int next_node_allowed(int nid, nodemask_t *nodes_allowed) 712{ 713 nid = next_node(nid, *nodes_allowed); 714 if (nid == MAX_NUMNODES) 715 nid = first_node(*nodes_allowed); 716 VM_BUG_ON(nid >= MAX_NUMNODES); 717 718 return nid; 719} 720 721static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) 722{ 723 if (!node_isset(nid, *nodes_allowed)) 724 nid = next_node_allowed(nid, nodes_allowed); 725 return nid; 726} 727 728/* 729 * returns the previously saved node ["this node"] from which to 730 * allocate a persistent huge page for the pool and advance the 731 * next node from which to allocate, handling wrap at end of node 732 * mask. 733 */ 734static int hstate_next_node_to_alloc(struct hstate *h, 735 nodemask_t *nodes_allowed) 736{ 737 int nid; 738 739 VM_BUG_ON(!nodes_allowed); 740 741 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); 742 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); 743 744 return nid; 745} 746 747static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) 748{ 749 struct page *page; 750 int start_nid; 751 int next_nid; 752 int ret = 0; 753 754 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 755 next_nid = start_nid; 756 757 do { 758 page = alloc_fresh_huge_page_node(h, next_nid); 759 if (page) { 760 ret = 1; 761 break; 762 } 763 next_nid = hstate_next_node_to_alloc(h, nodes_allowed); 764 } while (next_nid != start_nid); 765 766 if (ret) 767 count_vm_event(HTLB_BUDDY_PGALLOC); 768 else 769 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 770 771 return ret; 772} 773 774/* 775 * helper for free_pool_huge_page() - return the previously saved 776 * node ["this node"] from which to free a huge page. Advance the 777 * next node id whether or not we find a free huge page to free so 778 * that the next attempt to free addresses the next node. 779 */ 780static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) 781{ 782 int nid; 783 784 VM_BUG_ON(!nodes_allowed); 785 786 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); 787 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); 788 789 return nid; 790} 791 792/* 793 * Free huge page from pool from next node to free. 794 * Attempt to keep persistent huge pages more or less 795 * balanced over allowed nodes. 796 * Called with hugetlb_lock locked. 797 */ 798static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, 799 bool acct_surplus) 800{ 801 int start_nid; 802 int next_nid; 803 int ret = 0; 804 805 start_nid = hstate_next_node_to_free(h, nodes_allowed); 806 next_nid = start_nid; 807 808 do { 809 /* 810 * If we're returning unused surplus pages, only examine 811 * nodes with surplus pages. 812 */ 813 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) && 814 !list_empty(&h->hugepage_freelists[next_nid])) { 815 struct page *page = 816 list_entry(h->hugepage_freelists[next_nid].next, 817 struct page, lru); 818 list_del(&page->lru); 819 h->free_huge_pages--; 820 h->free_huge_pages_node[next_nid]--; 821 if (acct_surplus) { 822 h->surplus_huge_pages--; 823 h->surplus_huge_pages_node[next_nid]--; 824 } 825 update_and_free_page(h, page); 826 ret = 1; 827 break; 828 } 829 next_nid = hstate_next_node_to_free(h, nodes_allowed); 830 } while (next_nid != start_nid); 831 832 return ret; 833} 834 835static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) 836{ 837 struct page *page; 838 unsigned int r_nid; 839 840 if (h->order >= MAX_ORDER) 841 return NULL; 842 843 /* 844 * Assume we will successfully allocate the surplus page to 845 * prevent racing processes from causing the surplus to exceed 846 * overcommit 847 * 848 * This however introduces a different race, where a process B 849 * tries to grow the static hugepage pool while alloc_pages() is 850 * called by process A. B will only examine the per-node 851 * counters in determining if surplus huge pages can be 852 * converted to normal huge pages in adjust_pool_surplus(). A 853 * won't be able to increment the per-node counter, until the 854 * lock is dropped by B, but B doesn't drop hugetlb_lock until 855 * no more huge pages can be converted from surplus to normal 856 * state (and doesn't try to convert again). Thus, we have a 857 * case where a surplus huge page exists, the pool is grown, and 858 * the surplus huge page still exists after, even though it 859 * should just have been converted to a normal huge page. This 860 * does not leak memory, though, as the hugepage will be freed 861 * once it is out of use. It also does not allow the counters to 862 * go out of whack in adjust_pool_surplus() as we don't modify 863 * the node values until we've gotten the hugepage and only the 864 * per-node value is checked there. 865 */ 866 spin_lock(&hugetlb_lock); 867 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { 868 spin_unlock(&hugetlb_lock); 869 return NULL; 870 } else { 871 h->nr_huge_pages++; 872 h->surplus_huge_pages++; 873 } 874 spin_unlock(&hugetlb_lock); 875 876 if (nid == NUMA_NO_NODE) 877 page = alloc_pages(htlb_alloc_mask|__GFP_COMP| 878 __GFP_REPEAT|__GFP_NOWARN, 879 huge_page_order(h)); 880 else 881 page = alloc_pages_exact_node(nid, 882 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| 883 __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h)); 884 885 if (page && arch_prepare_hugepage(page)) { 886 __free_pages(page, huge_page_order(h)); 887 page = NULL; 888 } 889 890 spin_lock(&hugetlb_lock); 891 if (page) { 892 INIT_LIST_HEAD(&page->lru); 893 r_nid = page_to_nid(page); 894 set_compound_page_dtor(page, free_huge_page); 895 /* 896 * We incremented the global counters already 897 */ 898 h->nr_huge_pages_node[r_nid]++; 899 h->surplus_huge_pages_node[r_nid]++; 900 __count_vm_event(HTLB_BUDDY_PGALLOC); 901 } else { 902 h->nr_huge_pages--; 903 h->surplus_huge_pages--; 904 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 905 } 906 spin_unlock(&hugetlb_lock); 907 908 return page; 909} 910 911/* 912 * This allocation function is useful in the context where vma is irrelevant. 913 * E.g. soft-offlining uses this function because it only cares physical 914 * address of error page. 915 */ 916struct page *alloc_huge_page_node(struct hstate *h, int nid) 917{ 918 struct page *page; 919 920 spin_lock(&hugetlb_lock); 921 page = dequeue_huge_page_node(h, nid); 922 spin_unlock(&hugetlb_lock); 923 924 if (!page) 925 page = alloc_buddy_huge_page(h, nid); 926 927 return page; 928} 929 930/* 931 * Increase the hugetlb pool such that it can accommodate a reservation 932 * of size 'delta'. 933 */ 934static int gather_surplus_pages(struct hstate *h, int delta) 935{ 936 struct list_head surplus_list; 937 struct page *page, *tmp; 938 int ret, i; 939 int needed, allocated; 940 bool alloc_ok = true; 941 942 needed = (h->resv_huge_pages + delta) - h->free_huge_pages; 943 if (needed <= 0) { 944 h->resv_huge_pages += delta; 945 return 0; 946 } 947 948 allocated = 0; 949 INIT_LIST_HEAD(&surplus_list); 950 951 ret = -ENOMEM; 952retry: 953 spin_unlock(&hugetlb_lock); 954 for (i = 0; i < needed; i++) { 955 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 956 if (!page) { 957 alloc_ok = false; 958 break; 959 } 960 list_add(&page->lru, &surplus_list); 961 } 962 allocated += i; 963 964 /* 965 * After retaking hugetlb_lock, we need to recalculate 'needed' 966 * because either resv_huge_pages or free_huge_pages may have changed. 967 */ 968 spin_lock(&hugetlb_lock); 969 needed = (h->resv_huge_pages + delta) - 970 (h->free_huge_pages + allocated); 971 if (needed > 0) { 972 if (alloc_ok) 973 goto retry; 974 /* 975 * We were not able to allocate enough pages to 976 * satisfy the entire reservation so we free what 977 * we've allocated so far. 978 */ 979 goto free; 980 } 981 /* 982 * The surplus_list now contains _at_least_ the number of extra pages 983 * needed to accommodate the reservation. Add the appropriate number 984 * of pages to the hugetlb pool and free the extras back to the buddy 985 * allocator. Commit the entire reservation here to prevent another 986 * process from stealing the pages as they are added to the pool but 987 * before they are reserved. 988 */ 989 needed += allocated; 990 h->resv_huge_pages += delta; 991 ret = 0; 992 993 /* Free the needed pages to the hugetlb pool */ 994 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 995 if ((--needed) < 0) 996 break; 997 /* 998 * This page is now managed by the hugetlb allocator and has 999 * no users -- drop the buddy allocator's reference. 1000 */ 1001 put_page_testzero(page); 1002 VM_BUG_ON(page_count(page)); 1003 enqueue_huge_page(h, page); 1004 } 1005free: 1006 spin_unlock(&hugetlb_lock); 1007 1008 /* Free unnecessary surplus pages to the buddy allocator */ 1009 if (!list_empty(&surplus_list)) { 1010 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 1011 put_page(page); 1012 } 1013 } 1014 spin_lock(&hugetlb_lock); 1015 1016 return ret; 1017} 1018 1019/* 1020 * When releasing a hugetlb pool reservation, any surplus pages that were 1021 * allocated to satisfy the reservation must be explicitly freed if they were 1022 * never used. 1023 * Called with hugetlb_lock held. 1024 */ 1025static void return_unused_surplus_pages(struct hstate *h, 1026 unsigned long unused_resv_pages) 1027{ 1028 unsigned long nr_pages; 1029 1030 /* Uncommit the reservation */ 1031 h->resv_huge_pages -= unused_resv_pages; 1032 1033 /* Cannot return gigantic pages currently */ 1034 if (h->order >= MAX_ORDER) 1035 return; 1036 1037 nr_pages = min(unused_resv_pages, h->surplus_huge_pages); 1038 1039 /* 1040 * We want to release as many surplus pages as possible, spread 1041 * evenly across all nodes with memory. Iterate across these nodes 1042 * until we can no longer free unreserved surplus pages. This occurs 1043 * when the nodes with surplus pages have no free pages. 1044 * free_pool_huge_page() will balance the the freed pages across the 1045 * on-line nodes with memory and will handle the hstate accounting. 1046 */ 1047 while (nr_pages--) { 1048 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1)) 1049 break; 1050 } 1051} 1052 1053/* 1054 * Determine if the huge page at addr within the vma has an associated 1055 * reservation. Where it does not we will need to logically increase 1056 * reservation and actually increase subpool usage before an allocation 1057 * can occur. Where any new reservation would be required the 1058 * reservation change is prepared, but not committed. Once the page 1059 * has been allocated from the subpool and instantiated the change should 1060 * be committed via vma_commit_reservation. No action is required on 1061 * failure. 1062 */ 1063static long vma_needs_reservation(struct hstate *h, 1064 struct vm_area_struct *vma, unsigned long addr) 1065{ 1066 struct address_space *mapping = vma->vm_file->f_mapping; 1067 struct inode *inode = mapping->host; 1068 1069 if (vma->vm_flags & VM_MAYSHARE) { 1070 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1071 return region_chg(&inode->i_mapping->private_list, 1072 idx, idx + 1); 1073 1074 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 1075 return 1; 1076 1077 } else { 1078 long err; 1079 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1080 struct resv_map *reservations = vma_resv_map(vma); 1081 1082 err = region_chg(&reservations->regions, idx, idx + 1); 1083 if (err < 0) 1084 return err; 1085 return 0; 1086 } 1087} 1088static void vma_commit_reservation(struct hstate *h, 1089 struct vm_area_struct *vma, unsigned long addr) 1090{ 1091 struct address_space *mapping = vma->vm_file->f_mapping; 1092 struct inode *inode = mapping->host; 1093 1094 if (vma->vm_flags & VM_MAYSHARE) { 1095 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1096 region_add(&inode->i_mapping->private_list, idx, idx + 1); 1097 1098 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { 1099 pgoff_t idx = vma_hugecache_offset(h, vma, addr); 1100 struct resv_map *reservations = vma_resv_map(vma); 1101 1102 /* Mark this page used in the map. */ 1103 region_add(&reservations->regions, idx, idx + 1); 1104 } 1105} 1106 1107static struct page *alloc_huge_page(struct vm_area_struct *vma, 1108 unsigned long addr, int avoid_reserve) 1109{ 1110 struct hugepage_subpool *spool = subpool_vma(vma); 1111 struct hstate *h = hstate_vma(vma); 1112 struct page *page; 1113 long chg; 1114 1115 /* 1116 * Processes that did not create the mapping will have no 1117 * reserves and will not have accounted against subpool 1118 * limit. Check that the subpool limit can be made before 1119 * satisfying the allocation MAP_NORESERVE mappings may also 1120 * need pages and subpool limit allocated allocated if no reserve 1121 * mapping overlaps. 1122 */ 1123 chg = vma_needs_reservation(h, vma, addr); 1124 if (chg < 0) 1125 return ERR_PTR(-ENOMEM); 1126 if (chg) 1127 if (hugepage_subpool_get_pages(spool, chg)) 1128 return ERR_PTR(-ENOSPC); 1129 1130 spin_lock(&hugetlb_lock); 1131 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); 1132 spin_unlock(&hugetlb_lock); 1133 1134 if (!page) { 1135 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 1136 if (!page) { 1137 hugepage_subpool_put_pages(spool, chg); 1138 return ERR_PTR(-ENOSPC); 1139 } 1140 } 1141 1142 set_page_private(page, (unsigned long)spool); 1143 1144 vma_commit_reservation(h, vma, addr); 1145 1146 return page; 1147} 1148 1149int __weak alloc_bootmem_huge_page(struct hstate *h) 1150{ 1151 struct huge_bootmem_page *m; 1152 int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]); 1153 1154 while (nr_nodes) { 1155 void *addr; 1156 1157 addr = __alloc_bootmem_node_nopanic( 1158 NODE_DATA(hstate_next_node_to_alloc(h, 1159 &node_states[N_HIGH_MEMORY])), 1160 huge_page_size(h), huge_page_size(h), 0); 1161 1162 if (addr) { 1163 /* 1164 * Use the beginning of the huge page to store the 1165 * huge_bootmem_page struct (until gather_bootmem 1166 * puts them into the mem_map). 1167 */ 1168 m = addr; 1169 goto found; 1170 } 1171 nr_nodes--; 1172 } 1173 return 0; 1174 1175found: 1176 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); 1177 /* Put them into a private list first because mem_map is not up yet */ 1178 list_add(&m->list, &huge_boot_pages); 1179 m->hstate = h; 1180 return 1; 1181} 1182 1183static void prep_compound_huge_page(struct page *page, int order) 1184{ 1185 if (unlikely(order > (MAX_ORDER - 1))) 1186 prep_compound_gigantic_page(page, order); 1187 else 1188 prep_compound_page(page, order); 1189} 1190 1191/* Put bootmem huge pages into the standard lists after mem_map is up */ 1192static void __init gather_bootmem_prealloc(void) 1193{ 1194 struct huge_bootmem_page *m; 1195 1196 list_for_each_entry(m, &huge_boot_pages, list) { 1197 struct hstate *h = m->hstate; 1198 struct page *page; 1199 1200#ifdef CONFIG_HIGHMEM 1201 page = pfn_to_page(m->phys >> PAGE_SHIFT); 1202 free_bootmem_late((unsigned long)m, 1203 sizeof(struct huge_bootmem_page)); 1204#else 1205 page = virt_to_page(m); 1206#endif 1207 __ClearPageReserved(page); 1208 WARN_ON(page_count(page) != 1); 1209 prep_compound_huge_page(page, h->order); 1210 prep_new_huge_page(h, page, page_to_nid(page)); 1211 /* 1212 * If we had gigantic hugepages allocated at boot time, we need 1213 * to restore the 'stolen' pages to totalram_pages in order to 1214 * fix confusing memory reports from free(1) and another 1215 * side-effects, like CommitLimit going negative. 1216 */ 1217 if (h->order > (MAX_ORDER - 1)) 1218 totalram_pages += 1 << h->order; 1219 } 1220} 1221 1222static void __init hugetlb_hstate_alloc_pages(struct hstate *h) 1223{ 1224 unsigned long i; 1225 1226 for (i = 0; i < h->max_huge_pages; ++i) { 1227 if (h->order >= MAX_ORDER) { 1228 if (!alloc_bootmem_huge_page(h)) 1229 break; 1230 } else if (!alloc_fresh_huge_page(h, 1231 &node_states[N_HIGH_MEMORY])) 1232 break; 1233 } 1234 h->max_huge_pages = i; 1235} 1236 1237static void __init hugetlb_init_hstates(void) 1238{ 1239 struct hstate *h; 1240 1241 for_each_hstate(h) { 1242 /* oversize hugepages were init'ed in early boot */ 1243 if (h->order < MAX_ORDER) 1244 hugetlb_hstate_alloc_pages(h); 1245 } 1246} 1247 1248static char * __init memfmt(char *buf, unsigned long n) 1249{ 1250 if (n >= (1UL << 30)) 1251 sprintf(buf, "%lu GB", n >> 30); 1252 else if (n >= (1UL << 20)) 1253 sprintf(buf, "%lu MB", n >> 20); 1254 else 1255 sprintf(buf, "%lu KB", n >> 10); 1256 return buf; 1257} 1258 1259static void __init report_hugepages(void) 1260{ 1261 struct hstate *h; 1262 1263 for_each_hstate(h) { 1264 char buf[32]; 1265 printk(KERN_INFO "HugeTLB registered %s page size, " 1266 "pre-allocated %ld pages\n", 1267 memfmt(buf, huge_page_size(h)), 1268 h->free_huge_pages); 1269 } 1270} 1271 1272#ifdef CONFIG_HIGHMEM 1273static void try_to_free_low(struct hstate *h, unsigned long count, 1274 nodemask_t *nodes_allowed) 1275{ 1276 int i; 1277 1278 if (h->order >= MAX_ORDER) 1279 return; 1280 1281 for_each_node_mask(i, *nodes_allowed) { 1282 struct page *page, *next; 1283 struct list_head *freel = &h->hugepage_freelists[i]; 1284 list_for_each_entry_safe(page, next, freel, lru) { 1285 if (count >= h->nr_huge_pages) 1286 return; 1287 if (PageHighMem(page)) 1288 continue; 1289 list_del(&page->lru); 1290 update_and_free_page(h, page); 1291 h->free_huge_pages--; 1292 h->free_huge_pages_node[page_to_nid(page)]--; 1293 } 1294 } 1295} 1296#else 1297static inline void try_to_free_low(struct hstate *h, unsigned long count, 1298 nodemask_t *nodes_allowed) 1299{ 1300} 1301#endif 1302 1303/* 1304 * Increment or decrement surplus_huge_pages. Keep node-specific counters 1305 * balanced by operating on them in a round-robin fashion. 1306 * Returns 1 if an adjustment was made. 1307 */ 1308static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, 1309 int delta) 1310{ 1311 int start_nid, next_nid; 1312 int ret = 0; 1313 1314 VM_BUG_ON(delta != -1 && delta != 1); 1315 1316 if (delta < 0) 1317 start_nid = hstate_next_node_to_alloc(h, nodes_allowed); 1318 else 1319 start_nid = hstate_next_node_to_free(h, nodes_allowed); 1320 next_nid = start_nid; 1321 1322 do { 1323 int nid = next_nid; 1324 if (delta < 0) { 1325 /* 1326 * To shrink on this node, there must be a surplus page 1327 */ 1328 if (!h->surplus_huge_pages_node[nid]) { 1329 next_nid = hstate_next_node_to_alloc(h, 1330 nodes_allowed); 1331 continue; 1332 } 1333 } 1334 if (delta > 0) { 1335 /* 1336 * Surplus cannot exceed the total number of pages 1337 */ 1338 if (h->surplus_huge_pages_node[nid] >= 1339 h->nr_huge_pages_node[nid]) { 1340 next_nid = hstate_next_node_to_free(h, 1341 nodes_allowed); 1342 continue; 1343 } 1344 } 1345 1346 h->surplus_huge_pages += delta; 1347 h->surplus_huge_pages_node[nid] += delta; 1348 ret = 1; 1349 break; 1350 } while (next_nid != start_nid); 1351 1352 return ret; 1353} 1354 1355#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) 1356static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, 1357 nodemask_t *nodes_allowed) 1358{ 1359 unsigned long min_count, ret; 1360 1361 if (h->order >= MAX_ORDER) 1362 return h->max_huge_pages; 1363 1364 /* 1365 * Increase the pool size 1366 * First take pages out of surplus state. Then make up the 1367 * remaining difference by allocating fresh huge pages. 1368 * 1369 * We might race with alloc_buddy_huge_page() here and be unable 1370 * to convert a surplus huge page to a normal huge page. That is 1371 * not critical, though, it just means the overall size of the 1372 * pool might be one hugepage larger than it needs to be, but 1373 * within all the constraints specified by the sysctls. 1374 */ 1375 spin_lock(&hugetlb_lock); 1376 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { 1377 if (!adjust_pool_surplus(h, nodes_allowed, -1)) 1378 break; 1379 } 1380 1381 while (count > persistent_huge_pages(h)) { 1382 /* 1383 * If this allocation races such that we no longer need the 1384 * page, free_huge_page will handle it by freeing the page 1385 * and reducing the surplus. 1386 */ 1387 spin_unlock(&hugetlb_lock); 1388 ret = alloc_fresh_huge_page(h, nodes_allowed); 1389 spin_lock(&hugetlb_lock); 1390 if (!ret) 1391 goto out; 1392 1393 /* Bail for signals. Probably ctrl-c from user */ 1394 if (signal_pending(current)) 1395 goto out; 1396 } 1397 1398 /* 1399 * Decrease the pool size 1400 * First return free pages to the buddy allocator (being careful 1401 * to keep enough around to satisfy reservations). Then place 1402 * pages into surplus state as needed so the pool will shrink 1403 * to the desired size as pages become free. 1404 * 1405 * By placing pages into the surplus state independent of the 1406 * overcommit value, we are allowing the surplus pool size to 1407 * exceed overcommit. There are few sane options here. Since 1408 * alloc_buddy_huge_page() is checking the global counter, 1409 * though, we'll note that we're not allowed to exceed surplus 1410 * and won't grow the pool anywhere else. Not until one of the 1411 * sysctls are changed, or the surplus pages go out of use. 1412 */ 1413 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; 1414 min_count = max(count, min_count); 1415 try_to_free_low(h, min_count, nodes_allowed); 1416 while (min_count < persistent_huge_pages(h)) { 1417 if (!free_pool_huge_page(h, nodes_allowed, 0)) 1418 break; 1419 } 1420 while (count < persistent_huge_pages(h)) { 1421 if (!adjust_pool_surplus(h, nodes_allowed, 1)) 1422 break; 1423 } 1424out: 1425 ret = persistent_huge_pages(h); 1426 spin_unlock(&hugetlb_lock); 1427 return ret; 1428} 1429 1430#define HSTATE_ATTR_RO(_name) \ 1431 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 1432 1433#define HSTATE_ATTR(_name) \ 1434 static struct kobj_attribute _name##_attr = \ 1435 __ATTR(_name, 0644, _name##_show, _name##_store) 1436 1437static struct kobject *hugepages_kobj; 1438static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1439 1440static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); 1441 1442static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) 1443{ 1444 int i; 1445 1446 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1447 if (hstate_kobjs[i] == kobj) { 1448 if (nidp) 1449 *nidp = NUMA_NO_NODE; 1450 return &hstates[i]; 1451 } 1452 1453 return kobj_to_node_hstate(kobj, nidp); 1454} 1455 1456static ssize_t nr_hugepages_show_common(struct kobject *kobj, 1457 struct kobj_attribute *attr, char *buf) 1458{ 1459 struct hstate *h; 1460 unsigned long nr_huge_pages; 1461 int nid; 1462 1463 h = kobj_to_hstate(kobj, &nid); 1464 if (nid == NUMA_NO_NODE) 1465 nr_huge_pages = h->nr_huge_pages; 1466 else 1467 nr_huge_pages = h->nr_huge_pages_node[nid]; 1468 1469 return sprintf(buf, "%lu\n", nr_huge_pages); 1470} 1471 1472static ssize_t nr_hugepages_store_common(bool obey_mempolicy, 1473 struct kobject *kobj, struct kobj_attribute *attr, 1474 const char *buf, size_t len) 1475{ 1476 int err; 1477 int nid; 1478 unsigned long count; 1479 struct hstate *h; 1480 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); 1481 1482 err = strict_strtoul(buf, 10, &count); 1483 if (err) 1484 goto out; 1485 1486 h = kobj_to_hstate(kobj, &nid); 1487 if (h->order >= MAX_ORDER) { 1488 err = -EINVAL; 1489 goto out; 1490 } 1491 1492 if (nid == NUMA_NO_NODE) { 1493 /* 1494 * global hstate attribute 1495 */ 1496 if (!(obey_mempolicy && 1497 init_nodemask_of_mempolicy(nodes_allowed))) { 1498 NODEMASK_FREE(nodes_allowed); 1499 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1500 } 1501 } else if (nodes_allowed) { 1502 /* 1503 * per node hstate attribute: adjust count to global, 1504 * but restrict alloc/free to the specified node. 1505 */ 1506 count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; 1507 init_nodemask_of_node(nodes_allowed, nid); 1508 } else 1509 nodes_allowed = &node_states[N_HIGH_MEMORY]; 1510 1511 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); 1512 1513 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 1514 NODEMASK_FREE(nodes_allowed); 1515 1516 return len; 1517out: 1518 NODEMASK_FREE(nodes_allowed); 1519 return err; 1520} 1521 1522static ssize_t nr_hugepages_show(struct kobject *kobj, 1523 struct kobj_attribute *attr, char *buf) 1524{ 1525 return nr_hugepages_show_common(kobj, attr, buf); 1526} 1527 1528static ssize_t nr_hugepages_store(struct kobject *kobj, 1529 struct kobj_attribute *attr, const char *buf, size_t len) 1530{ 1531 return nr_hugepages_store_common(false, kobj, attr, buf, len); 1532} 1533HSTATE_ATTR(nr_hugepages); 1534 1535#ifdef CONFIG_NUMA 1536 1537/* 1538 * hstate attribute for optionally mempolicy-based constraint on persistent 1539 * huge page alloc/free. 1540 */ 1541static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, 1542 struct kobj_attribute *attr, char *buf) 1543{ 1544 return nr_hugepages_show_common(kobj, attr, buf); 1545} 1546 1547static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, 1548 struct kobj_attribute *attr, const char *buf, size_t len) 1549{ 1550 return nr_hugepages_store_common(true, kobj, attr, buf, len); 1551} 1552HSTATE_ATTR(nr_hugepages_mempolicy); 1553#endif 1554 1555 1556static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, 1557 struct kobj_attribute *attr, char *buf) 1558{ 1559 struct hstate *h = kobj_to_hstate(kobj, NULL); 1560 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); 1561} 1562 1563static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, 1564 struct kobj_attribute *attr, const char *buf, size_t count) 1565{ 1566 int err; 1567 unsigned long input; 1568 struct hstate *h = kobj_to_hstate(kobj, NULL); 1569 1570 if (h->order >= MAX_ORDER) 1571 return -EINVAL; 1572 1573 err = strict_strtoul(buf, 10, &input); 1574 if (err) 1575 return err; 1576 1577 spin_lock(&hugetlb_lock); 1578 h->nr_overcommit_huge_pages = input; 1579 spin_unlock(&hugetlb_lock); 1580 1581 return count; 1582} 1583HSTATE_ATTR(nr_overcommit_hugepages); 1584 1585static ssize_t free_hugepages_show(struct kobject *kobj, 1586 struct kobj_attribute *attr, char *buf) 1587{ 1588 struct hstate *h; 1589 unsigned long free_huge_pages; 1590 int nid; 1591 1592 h = kobj_to_hstate(kobj, &nid); 1593 if (nid == NUMA_NO_NODE) 1594 free_huge_pages = h->free_huge_pages; 1595 else 1596 free_huge_pages = h->free_huge_pages_node[nid]; 1597 1598 return sprintf(buf, "%lu\n", free_huge_pages); 1599} 1600HSTATE_ATTR_RO(free_hugepages); 1601 1602static ssize_t resv_hugepages_show(struct kobject *kobj, 1603 struct kobj_attribute *attr, char *buf) 1604{ 1605 struct hstate *h = kobj_to_hstate(kobj, NULL); 1606 return sprintf(buf, "%lu\n", h->resv_huge_pages); 1607} 1608HSTATE_ATTR_RO(resv_hugepages); 1609 1610static ssize_t surplus_hugepages_show(struct kobject *kobj, 1611 struct kobj_attribute *attr, char *buf) 1612{ 1613 struct hstate *h; 1614 unsigned long surplus_huge_pages; 1615 int nid; 1616 1617 h = kobj_to_hstate(kobj, &nid); 1618 if (nid == NUMA_NO_NODE) 1619 surplus_huge_pages = h->surplus_huge_pages; 1620 else 1621 surplus_huge_pages = h->surplus_huge_pages_node[nid]; 1622 1623 return sprintf(buf, "%lu\n", surplus_huge_pages); 1624} 1625HSTATE_ATTR_RO(surplus_hugepages); 1626 1627static struct attribute *hstate_attrs[] = { 1628 &nr_hugepages_attr.attr, 1629 &nr_overcommit_hugepages_attr.attr, 1630 &free_hugepages_attr.attr, 1631 &resv_hugepages_attr.attr, 1632 &surplus_hugepages_attr.attr, 1633#ifdef CONFIG_NUMA 1634 &nr_hugepages_mempolicy_attr.attr, 1635#endif 1636 NULL, 1637}; 1638 1639static struct attribute_group hstate_attr_group = { 1640 .attrs = hstate_attrs, 1641}; 1642 1643static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, 1644 struct kobject **hstate_kobjs, 1645 struct attribute_group *hstate_attr_group) 1646{ 1647 int retval; 1648 int hi = hstate_index(h); 1649 1650 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); 1651 if (!hstate_kobjs[hi]) 1652 return -ENOMEM; 1653 1654 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); 1655 if (retval) 1656 kobject_put(hstate_kobjs[hi]); 1657 1658 return retval; 1659} 1660 1661static void __init hugetlb_sysfs_init(void) 1662{ 1663 struct hstate *h; 1664 int err; 1665 1666 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); 1667 if (!hugepages_kobj) 1668 return; 1669 1670 for_each_hstate(h) { 1671 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, 1672 hstate_kobjs, &hstate_attr_group); 1673 if (err) 1674 printk(KERN_ERR "Hugetlb: Unable to add hstate %s", 1675 h->name); 1676 } 1677} 1678 1679#ifdef CONFIG_NUMA 1680 1681/* 1682 * node_hstate/s - associate per node hstate attributes, via their kobjects, 1683 * with node devices in node_devices[] using a parallel array. The array 1684 * index of a node device or _hstate == node id. 1685 * This is here to avoid any static dependency of the node device driver, in 1686 * the base kernel, on the hugetlb module. 1687 */ 1688struct node_hstate { 1689 struct kobject *hugepages_kobj; 1690 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1691}; 1692struct node_hstate node_hstates[MAX_NUMNODES]; 1693 1694/* 1695 * A subset of global hstate attributes for node devices 1696 */ 1697static struct attribute *per_node_hstate_attrs[] = { 1698 &nr_hugepages_attr.attr, 1699 &free_hugepages_attr.attr, 1700 &surplus_hugepages_attr.attr, 1701 NULL, 1702}; 1703 1704static struct attribute_group per_node_hstate_attr_group = { 1705 .attrs = per_node_hstate_attrs, 1706}; 1707 1708/* 1709 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. 1710 * Returns node id via non-NULL nidp. 1711 */ 1712static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1713{ 1714 int nid; 1715 1716 for (nid = 0; nid < nr_node_ids; nid++) { 1717 struct node_hstate *nhs = &node_hstates[nid]; 1718 int i; 1719 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1720 if (nhs->hstate_kobjs[i] == kobj) { 1721 if (nidp) 1722 *nidp = nid; 1723 return &hstates[i]; 1724 } 1725 } 1726 1727 BUG(); 1728 return NULL; 1729} 1730 1731/* 1732 * Unregister hstate attributes from a single node device. 1733 * No-op if no hstate attributes attached. 1734 */ 1735void hugetlb_unregister_node(struct node *node) 1736{ 1737 struct hstate *h; 1738 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1739 1740 if (!nhs->hugepages_kobj) 1741 return; /* no hstate attributes */ 1742 1743 for_each_hstate(h) { 1744 int idx = hstate_index(h); 1745 if (nhs->hstate_kobjs[idx]) { 1746 kobject_put(nhs->hstate_kobjs[idx]); 1747 nhs->hstate_kobjs[idx] = NULL; 1748 } 1749 } 1750 1751 kobject_put(nhs->hugepages_kobj); 1752 nhs->hugepages_kobj = NULL; 1753} 1754 1755/* 1756 * hugetlb module exit: unregister hstate attributes from node devices 1757 * that have them. 1758 */ 1759static void hugetlb_unregister_all_nodes(void) 1760{ 1761 int nid; 1762 1763 /* 1764 * disable node device registrations. 1765 */ 1766 register_hugetlbfs_with_node(NULL, NULL); 1767 1768 /* 1769 * remove hstate attributes from any nodes that have them. 1770 */ 1771 for (nid = 0; nid < nr_node_ids; nid++) 1772 hugetlb_unregister_node(&node_devices[nid]); 1773} 1774 1775/* 1776 * Register hstate attributes for a single node device. 1777 * No-op if attributes already registered. 1778 */ 1779void hugetlb_register_node(struct node *node) 1780{ 1781 struct hstate *h; 1782 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1783 int err; 1784 1785 if (nhs->hugepages_kobj) 1786 return; /* already allocated */ 1787 1788 nhs->hugepages_kobj = kobject_create_and_add("hugepages", 1789 &node->dev.kobj); 1790 if (!nhs->hugepages_kobj) 1791 return; 1792 1793 for_each_hstate(h) { 1794 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, 1795 nhs->hstate_kobjs, 1796 &per_node_hstate_attr_group); 1797 if (err) { 1798 printk(KERN_ERR "Hugetlb: Unable to add hstate %s" 1799 " for node %d\n", 1800 h->name, node->dev.id); 1801 hugetlb_unregister_node(node); 1802 break; 1803 } 1804 } 1805} 1806 1807/* 1808 * hugetlb init time: register hstate attributes for all registered node 1809 * devices of nodes that have memory. All on-line nodes should have 1810 * registered their associated device by this time. 1811 */ 1812static void hugetlb_register_all_nodes(void) 1813{ 1814 int nid; 1815 1816 for_each_node_state(nid, N_HIGH_MEMORY) { 1817 struct node *node = &node_devices[nid]; 1818 if (node->dev.id == nid) 1819 hugetlb_register_node(node); 1820 } 1821 1822 /* 1823 * Let the node device driver know we're here so it can 1824 * [un]register hstate attributes on node hotplug. 1825 */ 1826 register_hugetlbfs_with_node(hugetlb_register_node, 1827 hugetlb_unregister_node); 1828} 1829#else /* !CONFIG_NUMA */ 1830 1831static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1832{ 1833 BUG(); 1834 if (nidp) 1835 *nidp = -1; 1836 return NULL; 1837} 1838 1839static void hugetlb_unregister_all_nodes(void) { } 1840 1841static void hugetlb_register_all_nodes(void) { } 1842 1843#endif 1844 1845static void __exit hugetlb_exit(void) 1846{ 1847 struct hstate *h; 1848 1849 hugetlb_unregister_all_nodes(); 1850 1851 for_each_hstate(h) { 1852 kobject_put(hstate_kobjs[hstate_index(h)]); 1853 } 1854 1855 kobject_put(hugepages_kobj); 1856} 1857module_exit(hugetlb_exit); 1858 1859static int __init hugetlb_init(void) 1860{ 1861 /* Some platform decide whether they support huge pages at boot 1862 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when 1863 * there is no such support 1864 */ 1865 if (HPAGE_SHIFT == 0) 1866 return 0; 1867 1868 if (!size_to_hstate(default_hstate_size)) { 1869 default_hstate_size = HPAGE_SIZE; 1870 if (!size_to_hstate(default_hstate_size)) 1871 hugetlb_add_hstate(HUGETLB_PAGE_ORDER); 1872 } 1873 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size)); 1874 if (default_hstate_max_huge_pages) 1875 default_hstate.max_huge_pages = default_hstate_max_huge_pages; 1876 1877 hugetlb_init_hstates(); 1878 1879 gather_bootmem_prealloc(); 1880 1881 report_hugepages(); 1882 1883 hugetlb_sysfs_init(); 1884 1885 hugetlb_register_all_nodes(); 1886 1887 return 0; 1888} 1889module_init(hugetlb_init); 1890 1891/* Should be called on processing a hugepagesz=... option */ 1892void __init hugetlb_add_hstate(unsigned order) 1893{ 1894 struct hstate *h; 1895 unsigned long i; 1896 1897 if (size_to_hstate(PAGE_SIZE << order)) { 1898 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n"); 1899 return; 1900 } 1901 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); 1902 BUG_ON(order == 0); 1903 h = &hstates[hugetlb_max_hstate++]; 1904 h->order = order; 1905 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); 1906 h->nr_huge_pages = 0; 1907 h->free_huge_pages = 0; 1908 for (i = 0; i < MAX_NUMNODES; ++i) 1909 INIT_LIST_HEAD(&h->hugepage_freelists[i]); 1910 INIT_LIST_HEAD(&h->hugepage_activelist); 1911 h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]); 1912 h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]); 1913 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", 1914 huge_page_size(h)/1024); 1915 1916 parsed_hstate = h; 1917} 1918 1919static int __init hugetlb_nrpages_setup(char *s) 1920{ 1921 unsigned long *mhp; 1922 static unsigned long *last_mhp; 1923 1924 /* 1925 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet, 1926 * so this hugepages= parameter goes to the "default hstate". 1927 */ 1928 if (!hugetlb_max_hstate) 1929 mhp = &default_hstate_max_huge_pages; 1930 else 1931 mhp = &parsed_hstate->max_huge_pages; 1932 1933 if (mhp == last_mhp) { 1934 printk(KERN_WARNING "hugepages= specified twice without " 1935 "interleaving hugepagesz=, ignoring\n"); 1936 return 1; 1937 } 1938 1939 if (sscanf(s, "%lu", mhp) <= 0) 1940 *mhp = 0; 1941 1942 /* 1943 * Global state is always initialized later in hugetlb_init. 1944 * But we need to allocate >= MAX_ORDER hstates here early to still 1945 * use the bootmem allocator. 1946 */ 1947 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER) 1948 hugetlb_hstate_alloc_pages(parsed_hstate); 1949 1950 last_mhp = mhp; 1951 1952 return 1; 1953} 1954__setup("hugepages=", hugetlb_nrpages_setup); 1955 1956static int __init hugetlb_default_setup(char *s) 1957{ 1958 default_hstate_size = memparse(s, &s); 1959 return 1; 1960} 1961__setup("default_hugepagesz=", hugetlb_default_setup); 1962 1963static unsigned int cpuset_mems_nr(unsigned int *array) 1964{ 1965 int node; 1966 unsigned int nr = 0; 1967 1968 for_each_node_mask(node, cpuset_current_mems_allowed) 1969 nr += array[node]; 1970 1971 return nr; 1972} 1973 1974#ifdef CONFIG_SYSCTL 1975static int hugetlb_sysctl_handler_common(bool obey_mempolicy, 1976 struct ctl_table *table, int write, 1977 void __user *buffer, size_t *length, loff_t *ppos) 1978{ 1979 struct hstate *h = &default_hstate; 1980 unsigned long tmp; 1981 int ret; 1982 1983 tmp = h->max_huge_pages; 1984 1985 if (write && h->order >= MAX_ORDER) 1986 return -EINVAL; 1987 1988 table->data = &tmp; 1989 table->maxlen = sizeof(unsigned long); 1990 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 1991 if (ret) 1992 goto out; 1993 1994 if (write) { 1995 NODEMASK_ALLOC(nodemask_t, nodes_allowed, 1996 GFP_KERNEL | __GFP_NORETRY); 1997 if (!(obey_mempolicy && 1998 init_nodemask_of_mempolicy(nodes_allowed))) { 1999 NODEMASK_FREE(nodes_allowed); 2000 nodes_allowed = &node_states[N_HIGH_MEMORY]; 2001 } 2002 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); 2003 2004 if (nodes_allowed != &node_states[N_HIGH_MEMORY]) 2005 NODEMASK_FREE(nodes_allowed); 2006 } 2007out: 2008 return ret; 2009} 2010 2011int hugetlb_sysctl_handler(struct ctl_table *table, int write, 2012 void __user *buffer, size_t *length, loff_t *ppos) 2013{ 2014 2015 return hugetlb_sysctl_handler_common(false, table, write, 2016 buffer, length, ppos); 2017} 2018 2019#ifdef CONFIG_NUMA 2020int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, 2021 void __user *buffer, size_t *length, loff_t *ppos) 2022{ 2023 return hugetlb_sysctl_handler_common(true, table, write, 2024 buffer, length, ppos); 2025} 2026#endif /* CONFIG_NUMA */ 2027 2028int hugetlb_treat_movable_handler(struct ctl_table *table, int write, 2029 void __user *buffer, 2030 size_t *length, loff_t *ppos) 2031{ 2032 proc_dointvec(table, write, buffer, length, ppos); 2033 if (hugepages_treat_as_movable) 2034 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; 2035 else 2036 htlb_alloc_mask = GFP_HIGHUSER; 2037 return 0; 2038} 2039 2040int hugetlb_overcommit_handler(struct ctl_table *table, int write, 2041 void __user *buffer, 2042 size_t *length, loff_t *ppos) 2043{ 2044 struct hstate *h = &default_hstate; 2045 unsigned long tmp; 2046 int ret; 2047 2048 tmp = h->nr_overcommit_huge_pages; 2049 2050 if (write && h->order >= MAX_ORDER) 2051 return -EINVAL; 2052 2053 table->data = &tmp; 2054 table->maxlen = sizeof(unsigned long); 2055 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 2056 if (ret) 2057 goto out; 2058 2059 if (write) { 2060 spin_lock(&hugetlb_lock); 2061 h->nr_overcommit_huge_pages = tmp; 2062 spin_unlock(&hugetlb_lock); 2063 } 2064out: 2065 return ret; 2066} 2067 2068#endif /* CONFIG_SYSCTL */ 2069 2070void hugetlb_report_meminfo(struct seq_file *m) 2071{ 2072 struct hstate *h = &default_hstate; 2073 seq_printf(m, 2074 "HugePages_Total: %5lu\n" 2075 "HugePages_Free: %5lu\n" 2076 "HugePages_Rsvd: %5lu\n" 2077 "HugePages_Surp: %5lu\n" 2078 "Hugepagesize: %8lu kB\n", 2079 h->nr_huge_pages, 2080 h->free_huge_pages, 2081 h->resv_huge_pages, 2082 h->surplus_huge_pages, 2083 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 2084} 2085 2086int hugetlb_report_node_meminfo(int nid, char *buf) 2087{ 2088 struct hstate *h = &default_hstate; 2089 return sprintf(buf, 2090 "Node %d HugePages_Total: %5u\n" 2091 "Node %d HugePages_Free: %5u\n" 2092 "Node %d HugePages_Surp: %5u\n", 2093 nid, h->nr_huge_pages_node[nid], 2094 nid, h->free_huge_pages_node[nid], 2095 nid, h->surplus_huge_pages_node[nid]); 2096} 2097 2098/* Return the number pages of memory we physically have, in PAGE_SIZE units. */ 2099unsigned long hugetlb_total_pages(void) 2100{ 2101 struct hstate *h = &default_hstate; 2102 return h->nr_huge_pages * pages_per_huge_page(h); 2103} 2104 2105static int hugetlb_acct_memory(struct hstate *h, long delta) 2106{ 2107 int ret = -ENOMEM; 2108 2109 spin_lock(&hugetlb_lock); 2110 /* 2111 * When cpuset is configured, it breaks the strict hugetlb page 2112 * reservation as the accounting is done on a global variable. Such 2113 * reservation is completely rubbish in the presence of cpuset because 2114 * the reservation is not checked against page availability for the 2115 * current cpuset. Application can still potentially OOM'ed by kernel 2116 * with lack of free htlb page in cpuset that the task is in. 2117 * Attempt to enforce strict accounting with cpuset is almost 2118 * impossible (or too ugly) because cpuset is too fluid that 2119 * task or memory node can be dynamically moved between cpusets. 2120 * 2121 * The change of semantics for shared hugetlb mapping with cpuset is 2122 * undesirable. However, in order to preserve some of the semantics, 2123 * we fall back to check against current free page availability as 2124 * a best attempt and hopefully to minimize the impact of changing 2125 * semantics that cpuset has. 2126 */ 2127 if (delta > 0) { 2128 if (gather_surplus_pages(h, delta) < 0) 2129 goto out; 2130 2131 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { 2132 return_unused_surplus_pages(h, delta); 2133 goto out; 2134 } 2135 } 2136 2137 ret = 0; 2138 if (delta < 0) 2139 return_unused_surplus_pages(h, (unsigned long) -delta); 2140 2141out: 2142 spin_unlock(&hugetlb_lock); 2143 return ret; 2144} 2145 2146static void hugetlb_vm_op_open(struct vm_area_struct *vma) 2147{ 2148 struct resv_map *reservations = vma_resv_map(vma); 2149 2150 /* 2151 * This new VMA should share its siblings reservation map if present. 2152 * The VMA will only ever have a valid reservation map pointer where 2153 * it is being copied for another still existing VMA. As that VMA 2154 * has a reference to the reservation map it cannot disappear until 2155 * after this open call completes. It is therefore safe to take a 2156 * new reference here without additional locking. 2157 */ 2158 if (reservations) 2159 kref_get(&reservations->refs); 2160} 2161 2162static void resv_map_put(struct vm_area_struct *vma) 2163{ 2164 struct resv_map *reservations = vma_resv_map(vma); 2165 2166 if (!reservations) 2167 return; 2168 kref_put(&reservations->refs, resv_map_release); 2169} 2170 2171static void hugetlb_vm_op_close(struct vm_area_struct *vma) 2172{ 2173 struct hstate *h = hstate_vma(vma); 2174 struct resv_map *reservations = vma_resv_map(vma); 2175 struct hugepage_subpool *spool = subpool_vma(vma); 2176 unsigned long reserve; 2177 unsigned long start; 2178 unsigned long end; 2179 2180 if (reservations) { 2181 start = vma_hugecache_offset(h, vma, vma->vm_start); 2182 end = vma_hugecache_offset(h, vma, vma->vm_end); 2183 2184 reserve = (end - start) - 2185 region_count(&reservations->regions, start, end); 2186 2187 resv_map_put(vma); 2188 2189 if (reserve) { 2190 hugetlb_acct_memory(h, -reserve); 2191 hugepage_subpool_put_pages(spool, reserve); 2192 } 2193 } 2194} 2195 2196/* 2197 * We cannot handle pagefaults against hugetlb pages at all. They cause 2198 * handle_mm_fault() to try to instantiate regular-sized pages in the 2199 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get 2200 * this far. 2201 */ 2202static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 2203{ 2204 BUG(); 2205 return 0; 2206} 2207 2208const struct vm_operations_struct hugetlb_vm_ops = { 2209 .fault = hugetlb_vm_op_fault, 2210 .open = hugetlb_vm_op_open, 2211 .close = hugetlb_vm_op_close, 2212}; 2213 2214static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, 2215 int writable) 2216{ 2217 pte_t entry; 2218 2219 if (writable) { 2220 entry = 2221 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); 2222 } else { 2223 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot)); 2224 } 2225 entry = pte_mkyoung(entry); 2226 entry = pte_mkhuge(entry); 2227 entry = arch_make_huge_pte(entry, vma, page, writable); 2228 2229 return entry; 2230} 2231 2232static void set_huge_ptep_writable(struct vm_area_struct *vma, 2233 unsigned long address, pte_t *ptep) 2234{ 2235 pte_t entry; 2236 2237 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep))); 2238 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) 2239 update_mmu_cache(vma, address, ptep); 2240} 2241 2242 2243int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, 2244 struct vm_area_struct *vma) 2245{ 2246 pte_t *src_pte, *dst_pte, entry; 2247 struct page *ptepage; 2248 unsigned long addr; 2249 int cow; 2250 struct hstate *h = hstate_vma(vma); 2251 unsigned long sz = huge_page_size(h); 2252 2253 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 2254 2255 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { 2256 src_pte = huge_pte_offset(src, addr); 2257 if (!src_pte) 2258 continue; 2259 dst_pte = huge_pte_alloc(dst, addr, sz); 2260 if (!dst_pte) 2261 goto nomem; 2262 2263 /* If the pagetables are shared don't copy or take references */ 2264 if (dst_pte == src_pte) 2265 continue; 2266 2267 spin_lock(&dst->page_table_lock); 2268 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); 2269 if (!huge_pte_none(huge_ptep_get(src_pte))) { 2270 if (cow) 2271 huge_ptep_set_wrprotect(src, addr, src_pte); 2272 entry = huge_ptep_get(src_pte); 2273 ptepage = pte_page(entry); 2274 get_page(ptepage); 2275 page_dup_rmap(ptepage); 2276 set_huge_pte_at(dst, addr, dst_pte, entry); 2277 } 2278 spin_unlock(&src->page_table_lock); 2279 spin_unlock(&dst->page_table_lock); 2280 } 2281 return 0; 2282 2283nomem: 2284 return -ENOMEM; 2285} 2286 2287static int is_hugetlb_entry_migration(pte_t pte) 2288{ 2289 swp_entry_t swp; 2290 2291 if (huge_pte_none(pte) || pte_present(pte)) 2292 return 0; 2293 swp = pte_to_swp_entry(pte); 2294 if (non_swap_entry(swp) && is_migration_entry(swp)) 2295 return 1; 2296 else 2297 return 0; 2298} 2299 2300static int is_hugetlb_entry_hwpoisoned(pte_t pte) 2301{ 2302 swp_entry_t swp; 2303 2304 if (huge_pte_none(pte) || pte_present(pte)) 2305 return 0; 2306 swp = pte_to_swp_entry(pte); 2307 if (non_swap_entry(swp) && is_hwpoison_entry(swp)) 2308 return 1; 2309 else 2310 return 0; 2311} 2312 2313void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, 2314 unsigned long start, unsigned long end, 2315 struct page *ref_page) 2316{ 2317 int force_flush = 0; 2318 struct mm_struct *mm = vma->vm_mm; 2319 unsigned long address; 2320 pte_t *ptep; 2321 pte_t pte; 2322 struct page *page; 2323 struct hstate *h = hstate_vma(vma); 2324 unsigned long sz = huge_page_size(h); 2325 2326 WARN_ON(!is_vm_hugetlb_page(vma)); 2327 BUG_ON(start & ~huge_page_mask(h)); 2328 BUG_ON(end & ~huge_page_mask(h)); 2329 2330 tlb_start_vma(tlb, vma); 2331 mmu_notifier_invalidate_range_start(mm, start, end); 2332again: 2333 spin_lock(&mm->page_table_lock); 2334 for (address = start; address < end; address += sz) { 2335 ptep = huge_pte_offset(mm, address); 2336 if (!ptep) 2337 continue; 2338 2339 if (huge_pmd_unshare(mm, &address, ptep)) 2340 continue; 2341 2342 pte = huge_ptep_get(ptep); 2343 if (huge_pte_none(pte)) 2344 continue; 2345 2346 /* 2347 * HWPoisoned hugepage is already unmapped and dropped reference 2348 */ 2349 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) 2350 continue; 2351 2352 page = pte_page(pte); 2353 /* 2354 * If a reference page is supplied, it is because a specific 2355 * page is being unmapped, not a range. Ensure the page we 2356 * are about to unmap is the actual page of interest. 2357 */ 2358 if (ref_page) { 2359 if (page != ref_page) 2360 continue; 2361 2362 /* 2363 * Mark the VMA as having unmapped its page so that 2364 * future faults in this VMA will fail rather than 2365 * looking like data was lost 2366 */ 2367 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); 2368 } 2369 2370 pte = huge_ptep_get_and_clear(mm, address, ptep); 2371 tlb_remove_tlb_entry(tlb, ptep, address); 2372 if (pte_dirty(pte)) 2373 set_page_dirty(page); 2374 2375 page_remove_rmap(page); 2376 force_flush = !__tlb_remove_page(tlb, page); 2377 if (force_flush) 2378 break; 2379 /* Bail out after unmapping reference page if supplied */ 2380 if (ref_page) 2381 break; 2382 } 2383 spin_unlock(&mm->page_table_lock); 2384 /* 2385 * mmu_gather ran out of room to batch pages, we break out of 2386 * the PTE lock to avoid doing the potential expensive TLB invalidate 2387 * and page-free while holding it. 2388 */ 2389 if (force_flush) { 2390 force_flush = 0; 2391 tlb_flush_mmu(tlb); 2392 if (address < end && !ref_page) 2393 goto again; 2394 } 2395 mmu_notifier_invalidate_range_end(mm, start, end); 2396 tlb_end_vma(tlb, vma); 2397} 2398 2399void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2400 unsigned long end, struct page *ref_page) 2401{ 2402 struct mm_struct *mm; 2403 struct mmu_gather tlb; 2404 2405 mm = vma->vm_mm; 2406 2407 tlb_gather_mmu(&tlb, mm, 0); 2408 __unmap_hugepage_range(&tlb, vma, start, end, ref_page); 2409 tlb_finish_mmu(&tlb, start, end); 2410} 2411 2412/* 2413 * This is called when the original mapper is failing to COW a MAP_PRIVATE 2414 * mappping it owns the reserve page for. The intention is to unmap the page 2415 * from other VMAs and let the children be SIGKILLed if they are faulting the 2416 * same region. 2417 */ 2418static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, 2419 struct page *page, unsigned long address) 2420{ 2421 struct hstate *h = hstate_vma(vma); 2422 struct vm_area_struct *iter_vma; 2423 struct address_space *mapping; 2424 struct prio_tree_iter iter; 2425 pgoff_t pgoff; 2426 2427 /* 2428 * vm_pgoff is in PAGE_SIZE units, hence the different calculation 2429 * from page cache lookup which is in HPAGE_SIZE units. 2430 */ 2431 address = address & huge_page_mask(h); 2432 pgoff = vma_hugecache_offset(h, vma, address); 2433 mapping = vma->vm_file->f_dentry->d_inode->i_mapping; 2434 2435 /* 2436 * Take the mapping lock for the duration of the table walk. As 2437 * this mapping should be shared between all the VMAs, 2438 * __unmap_hugepage_range() is called as the lock is already held 2439 */ 2440 mutex_lock(&mapping->i_mmap_mutex); 2441 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 2442 /* Do not unmap the current VMA */ 2443 if (iter_vma == vma) 2444 continue; 2445 2446 /* 2447 * Unmap the page from other VMAs without their own reserves. 2448 * They get marked to be SIGKILLed if they fault in these 2449 * areas. This is because a future no-page fault on this VMA 2450 * could insert a zeroed page instead of the data existing 2451 * from the time of fork. This would look like data corruption 2452 */ 2453 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2454 unmap_hugepage_range(iter_vma, address, 2455 address + huge_page_size(h), page); 2456 } 2457 mutex_unlock(&mapping->i_mmap_mutex); 2458 2459 return 1; 2460} 2461 2462/* 2463 * Hugetlb_cow() should be called with page lock of the original hugepage held. 2464 * Called with hugetlb_instantiation_mutex held and pte_page locked so we 2465 * cannot race with other handlers or page migration. 2466 * Keep the pte_same checks anyway to make transition from the mutex easier. 2467 */ 2468static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, 2469 unsigned long address, pte_t *ptep, pte_t pte, 2470 struct page *pagecache_page) 2471{ 2472 struct hstate *h = hstate_vma(vma); 2473 struct page *old_page, *new_page; 2474 int avoidcopy; 2475 int outside_reserve = 0; 2476 2477 old_page = pte_page(pte); 2478 2479retry_avoidcopy: 2480 /* If no-one else is actually using this page, avoid the copy 2481 * and just make the page writable */ 2482 avoidcopy = (page_mapcount(old_page) == 1); 2483 if (avoidcopy) { 2484 if (PageAnon(old_page)) 2485 page_move_anon_rmap(old_page, vma, address); 2486 set_huge_ptep_writable(vma, address, ptep); 2487 return 0; 2488 } 2489 2490 /* 2491 * If the process that created a MAP_PRIVATE mapping is about to 2492 * perform a COW due to a shared page count, attempt to satisfy 2493 * the allocation without using the existing reserves. The pagecache 2494 * page is used to determine if the reserve at this address was 2495 * consumed or not. If reserves were used, a partial faulted mapping 2496 * at the time of fork() could consume its reserves on COW instead 2497 * of the full address range. 2498 */ 2499 if (!(vma->vm_flags & VM_MAYSHARE) && 2500 is_vma_resv_set(vma, HPAGE_RESV_OWNER) && 2501 old_page != pagecache_page) 2502 outside_reserve = 1; 2503 2504 page_cache_get(old_page); 2505 2506 /* Drop page_table_lock as buddy allocator may be called */ 2507 spin_unlock(&mm->page_table_lock); 2508 new_page = alloc_huge_page(vma, address, outside_reserve); 2509 2510 if (IS_ERR(new_page)) { 2511 long err = PTR_ERR(new_page); 2512 page_cache_release(old_page); 2513 2514 /* 2515 * If a process owning a MAP_PRIVATE mapping fails to COW, 2516 * it is due to references held by a child and an insufficient 2517 * huge page pool. To guarantee the original mappers 2518 * reliability, unmap the page from child processes. The child 2519 * may get SIGKILLed if it later faults. 2520 */ 2521 if (outside_reserve) { 2522 BUG_ON(huge_pte_none(pte)); 2523 if (unmap_ref_private(mm, vma, old_page, address)) { 2524 BUG_ON(huge_pte_none(pte)); 2525 spin_lock(&mm->page_table_lock); 2526 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2527 if (likely(pte_same(huge_ptep_get(ptep), pte))) 2528 goto retry_avoidcopy; 2529 /* 2530 * race occurs while re-acquiring page_table_lock, and 2531 * our job is done. 2532 */ 2533 return 0; 2534 } 2535 WARN_ON_ONCE(1); 2536 } 2537 2538 /* Caller expects lock to be held */ 2539 spin_lock(&mm->page_table_lock); 2540 if (err == -ENOMEM) 2541 return VM_FAULT_OOM; 2542 else 2543 return VM_FAULT_SIGBUS; 2544 } 2545 2546 /* 2547 * When the original hugepage is shared one, it does not have 2548 * anon_vma prepared. 2549 */ 2550 if (unlikely(anon_vma_prepare(vma))) { 2551 page_cache_release(new_page); 2552 page_cache_release(old_page); 2553 /* Caller expects lock to be held */ 2554 spin_lock(&mm->page_table_lock); 2555 return VM_FAULT_OOM; 2556 } 2557 2558 copy_user_huge_page(new_page, old_page, address, vma, 2559 pages_per_huge_page(h)); 2560 __SetPageUptodate(new_page); 2561 2562 /* 2563 * Retake the page_table_lock to check for racing updates 2564 * before the page tables are altered 2565 */ 2566 spin_lock(&mm->page_table_lock); 2567 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2568 if (likely(pte_same(huge_ptep_get(ptep), pte))) { 2569 /* Break COW */ 2570 mmu_notifier_invalidate_range_start(mm, 2571 address & huge_page_mask(h), 2572 (address & huge_page_mask(h)) + huge_page_size(h)); 2573 huge_ptep_clear_flush(vma, address, ptep); 2574 set_huge_pte_at(mm, address, ptep, 2575 make_huge_pte(vma, new_page, 1)); 2576 page_remove_rmap(old_page); 2577 hugepage_add_new_anon_rmap(new_page, vma, address); 2578 /* Make the old page be freed below */ 2579 new_page = old_page; 2580 mmu_notifier_invalidate_range_end(mm, 2581 address & huge_page_mask(h), 2582 (address & huge_page_mask(h)) + huge_page_size(h)); 2583 } 2584 page_cache_release(new_page); 2585 page_cache_release(old_page); 2586 return 0; 2587} 2588 2589/* Return the pagecache page at a given address within a VMA */ 2590static struct page *hugetlbfs_pagecache_page(struct hstate *h, 2591 struct vm_area_struct *vma, unsigned long address) 2592{ 2593 struct address_space *mapping; 2594 pgoff_t idx; 2595 2596 mapping = vma->vm_file->f_mapping; 2597 idx = vma_hugecache_offset(h, vma, address); 2598 2599 return find_lock_page(mapping, idx); 2600} 2601 2602/* 2603 * Return whether there is a pagecache page to back given address within VMA. 2604 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. 2605 */ 2606static bool hugetlbfs_pagecache_present(struct hstate *h, 2607 struct vm_area_struct *vma, unsigned long address) 2608{ 2609 struct address_space *mapping; 2610 pgoff_t idx; 2611 struct page *page; 2612 2613 mapping = vma->vm_file->f_mapping; 2614 idx = vma_hugecache_offset(h, vma, address); 2615 2616 page = find_get_page(mapping, idx); 2617 if (page) 2618 put_page(page); 2619 return page != NULL; 2620} 2621 2622static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2623 unsigned long address, pte_t *ptep, unsigned int flags) 2624{ 2625 struct hstate *h = hstate_vma(vma); 2626 int ret = VM_FAULT_SIGBUS; 2627 int anon_rmap = 0; 2628 pgoff_t idx; 2629 unsigned long size; 2630 struct page *page; 2631 struct address_space *mapping; 2632 pte_t new_pte; 2633 2634 /* 2635 * Currently, we are forced to kill the process in the event the 2636 * original mapper has unmapped pages from the child due to a failed 2637 * COW. Warn that such a situation has occurred as it may not be obvious 2638 */ 2639 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { 2640 printk(KERN_WARNING 2641 "PID %d killed due to inadequate hugepage pool\n", 2642 current->pid); 2643 return ret; 2644 } 2645 2646 mapping = vma->vm_file->f_mapping; 2647 idx = vma_hugecache_offset(h, vma, address); 2648 2649 /* 2650 * Use page lock to guard against racing truncation 2651 * before we get page_table_lock. 2652 */ 2653retry: 2654 page = find_lock_page(mapping, idx); 2655 if (!page) { 2656 size = i_size_read(mapping->host) >> huge_page_shift(h); 2657 if (idx >= size) 2658 goto out; 2659 page = alloc_huge_page(vma, address, 0); 2660 if (IS_ERR(page)) { 2661 ret = PTR_ERR(page); 2662 if (ret == -ENOMEM) 2663 ret = VM_FAULT_OOM; 2664 else 2665 ret = VM_FAULT_SIGBUS; 2666 goto out; 2667 } 2668 clear_huge_page(page, address, pages_per_huge_page(h)); 2669 __SetPageUptodate(page); 2670 2671 if (vma->vm_flags & VM_MAYSHARE) { 2672 int err; 2673 struct inode *inode = mapping->host; 2674 2675 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); 2676 if (err) { 2677 put_page(page); 2678 if (err == -EEXIST) 2679 goto retry; 2680 goto out; 2681 } 2682 2683 spin_lock(&inode->i_lock); 2684 inode->i_blocks += blocks_per_huge_page(h); 2685 spin_unlock(&inode->i_lock); 2686 } else { 2687 lock_page(page); 2688 if (unlikely(anon_vma_prepare(vma))) { 2689 ret = VM_FAULT_OOM; 2690 goto backout_unlocked; 2691 } 2692 anon_rmap = 1; 2693 } 2694 } else { 2695 /* 2696 * If memory error occurs between mmap() and fault, some process 2697 * don't have hwpoisoned swap entry for errored virtual address. 2698 * So we need to block hugepage fault by PG_hwpoison bit check. 2699 */ 2700 if (unlikely(PageHWPoison(page))) { 2701 ret = VM_FAULT_HWPOISON | 2702 VM_FAULT_SET_HINDEX(hstate_index(h)); 2703 goto backout_unlocked; 2704 } 2705 } 2706 2707 /* 2708 * If we are going to COW a private mapping later, we examine the 2709 * pending reservations for this page now. This will ensure that 2710 * any allocations necessary to record that reservation occur outside 2711 * the spinlock. 2712 */ 2713 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 2714 if (vma_needs_reservation(h, vma, address) < 0) { 2715 ret = VM_FAULT_OOM; 2716 goto backout_unlocked; 2717 } 2718 2719 spin_lock(&mm->page_table_lock); 2720 size = i_size_read(mapping->host) >> huge_page_shift(h); 2721 if (idx >= size) 2722 goto backout; 2723 2724 ret = 0; 2725 if (!huge_pte_none(huge_ptep_get(ptep))) 2726 goto backout; 2727 2728 if (anon_rmap) 2729 hugepage_add_new_anon_rmap(page, vma, address); 2730 else 2731 page_dup_rmap(page); 2732 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) 2733 && (vma->vm_flags & VM_SHARED))); 2734 set_huge_pte_at(mm, address, ptep, new_pte); 2735 2736 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 2737 /* Optimization, do the COW without a second fault */ 2738 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); 2739 } 2740 2741 spin_unlock(&mm->page_table_lock); 2742 unlock_page(page); 2743out: 2744 return ret; 2745 2746backout: 2747 spin_unlock(&mm->page_table_lock); 2748backout_unlocked: 2749 unlock_page(page); 2750 put_page(page); 2751 goto out; 2752} 2753 2754int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2755 unsigned long address, unsigned int flags) 2756{ 2757 pte_t *ptep; 2758 pte_t entry; 2759 int ret; 2760 struct page *page = NULL; 2761 struct page *pagecache_page = NULL; 2762 static DEFINE_MUTEX(hugetlb_instantiation_mutex); 2763 struct hstate *h = hstate_vma(vma); 2764 2765 address &= huge_page_mask(h); 2766 2767 ptep = huge_pte_offset(mm, address); 2768 if (ptep) { 2769 entry = huge_ptep_get(ptep); 2770 if (unlikely(is_hugetlb_entry_migration(entry))) { 2771 migration_entry_wait(mm, (pmd_t *)ptep, address); 2772 return 0; 2773 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) 2774 return VM_FAULT_HWPOISON_LARGE | 2775 VM_FAULT_SET_HINDEX(hstate_index(h)); 2776 } 2777 2778 ptep = huge_pte_alloc(mm, address, huge_page_size(h)); 2779 if (!ptep) 2780 return VM_FAULT_OOM; 2781 2782 /* 2783 * Serialize hugepage allocation and instantiation, so that we don't 2784 * get spurious allocation failures if two CPUs race to instantiate 2785 * the same page in the page cache. 2786 */ 2787 mutex_lock(&hugetlb_instantiation_mutex); 2788 entry = huge_ptep_get(ptep); 2789 if (huge_pte_none(entry)) { 2790 ret = hugetlb_no_page(mm, vma, address, ptep, flags); 2791 goto out_mutex; 2792 } 2793 2794 ret = 0; 2795 2796 /* 2797 * If we are going to COW the mapping later, we examine the pending 2798 * reservations for this page now. This will ensure that any 2799 * allocations necessary to record that reservation occur outside the 2800 * spinlock. For private mappings, we also lookup the pagecache 2801 * page now as it is used to determine if a reservation has been 2802 * consumed. 2803 */ 2804 if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) { 2805 if (vma_needs_reservation(h, vma, address) < 0) { 2806 ret = VM_FAULT_OOM; 2807 goto out_mutex; 2808 } 2809 2810 if (!(vma->vm_flags & VM_MAYSHARE)) 2811 pagecache_page = hugetlbfs_pagecache_page(h, 2812 vma, address); 2813 } 2814 2815 /* 2816 * hugetlb_cow() requires page locks of pte_page(entry) and 2817 * pagecache_page, so here we need take the former one 2818 * when page != pagecache_page or !pagecache_page. 2819 * Note that locking order is always pagecache_page -> page, 2820 * so no worry about deadlock. 2821 */ 2822 page = pte_page(entry); 2823 get_page(page); 2824 if (page != pagecache_page) 2825 lock_page(page); 2826 2827 spin_lock(&mm->page_table_lock); 2828 /* Check for a racing update before calling hugetlb_cow */ 2829 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 2830 goto out_page_table_lock; 2831 2832 2833 if (flags & FAULT_FLAG_WRITE) { 2834 if (!pte_write(entry)) { 2835 ret = hugetlb_cow(mm, vma, address, ptep, entry, 2836 pagecache_page); 2837 goto out_page_table_lock; 2838 } 2839 entry = pte_mkdirty(entry); 2840 } 2841 entry = pte_mkyoung(entry); 2842 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 2843 flags & FAULT_FLAG_WRITE)) 2844 update_mmu_cache(vma, address, ptep); 2845 2846out_page_table_lock: 2847 spin_unlock(&mm->page_table_lock); 2848 2849 if (pagecache_page) { 2850 unlock_page(pagecache_page); 2851 put_page(pagecache_page); 2852 } 2853 if (page != pagecache_page) 2854 unlock_page(page); 2855 put_page(page); 2856 2857out_mutex: 2858 mutex_unlock(&hugetlb_instantiation_mutex); 2859 2860 return ret; 2861} 2862 2863/* Can be overriden by architectures */ 2864__attribute__((weak)) struct page * 2865follow_huge_pud(struct mm_struct *mm, unsigned long address, 2866 pud_t *pud, int write) 2867{ 2868 BUG(); 2869 return NULL; 2870} 2871 2872int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 2873 struct page **pages, struct vm_area_struct **vmas, 2874 unsigned long *position, int *length, int i, 2875 unsigned int flags) 2876{ 2877 unsigned long pfn_offset; 2878 unsigned long vaddr = *position; 2879 int remainder = *length; 2880 struct hstate *h = hstate_vma(vma); 2881 2882 spin_lock(&mm->page_table_lock); 2883 while (vaddr < vma->vm_end && remainder) { 2884 pte_t *pte; 2885 int absent; 2886 struct page *page; 2887 2888 /* 2889 * Some archs (sparc64, sh*) have multiple pte_ts to 2890 * each hugepage. We have to make sure we get the 2891 * first, for the page indexing below to work. 2892 */ 2893 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); 2894 absent = !pte || huge_pte_none(huge_ptep_get(pte)); 2895 2896 /* 2897 * When coredumping, it suits get_dump_page if we just return 2898 * an error where there's an empty slot with no huge pagecache 2899 * to back it. This way, we avoid allocating a hugepage, and 2900 * the sparse dumpfile avoids allocating disk blocks, but its 2901 * huge holes still show up with zeroes where they need to be. 2902 */ 2903 if (absent && (flags & FOLL_DUMP) && 2904 !hugetlbfs_pagecache_present(h, vma, vaddr)) { 2905 remainder = 0; 2906 break; 2907 } 2908 2909 if (absent || 2910 ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { 2911 int ret; 2912 2913 spin_unlock(&mm->page_table_lock); 2914 ret = hugetlb_fault(mm, vma, vaddr, 2915 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); 2916 spin_lock(&mm->page_table_lock); 2917 if (!(ret & VM_FAULT_ERROR)) 2918 continue; 2919 2920 remainder = 0; 2921 break; 2922 } 2923 2924 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; 2925 page = pte_page(huge_ptep_get(pte)); 2926same_page: 2927 if (pages) { 2928 pages[i] = mem_map_offset(page, pfn_offset); 2929 get_page(pages[i]); 2930 } 2931 2932 if (vmas) 2933 vmas[i] = vma; 2934 2935 vaddr += PAGE_SIZE; 2936 ++pfn_offset; 2937 --remainder; 2938 ++i; 2939 if (vaddr < vma->vm_end && remainder && 2940 pfn_offset < pages_per_huge_page(h)) { 2941 /* 2942 * We use pfn_offset to avoid touching the pageframes 2943 * of this compound page. 2944 */ 2945 goto same_page; 2946 } 2947 } 2948 spin_unlock(&mm->page_table_lock); 2949 *length = remainder; 2950 *position = vaddr; 2951 2952 return i ? i : -EFAULT; 2953} 2954 2955void hugetlb_change_protection(struct vm_area_struct *vma, 2956 unsigned long address, unsigned long end, pgprot_t newprot) 2957{ 2958 struct mm_struct *mm = vma->vm_mm; 2959 unsigned long start = address; 2960 pte_t *ptep; 2961 pte_t pte; 2962 struct hstate *h = hstate_vma(vma); 2963 2964 BUG_ON(address >= end); 2965 flush_cache_range(vma, address, end); 2966 2967 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 2968 spin_lock(&mm->page_table_lock); 2969 for (; address < end; address += huge_page_size(h)) { 2970 ptep = huge_pte_offset(mm, address); 2971 if (!ptep) 2972 continue; 2973 if (huge_pmd_unshare(mm, &address, ptep)) 2974 continue; 2975 if (!huge_pte_none(huge_ptep_get(ptep))) { 2976 pte = huge_ptep_get_and_clear(mm, address, ptep); 2977 pte = pte_mkhuge(pte_modify(pte, newprot)); 2978 set_huge_pte_at(mm, address, ptep, pte); 2979 } 2980 } 2981 spin_unlock(&mm->page_table_lock); 2982 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 2983 2984 flush_tlb_range(vma, start, end); 2985} 2986 2987int hugetlb_reserve_pages(struct inode *inode, 2988 long from, long to, 2989 struct vm_area_struct *vma, 2990 vm_flags_t vm_flags) 2991{ 2992 long ret, chg; 2993 struct hstate *h = hstate_inode(inode); 2994 struct hugepage_subpool *spool = subpool_inode(inode); 2995 2996 /* 2997 * Only apply hugepage reservation if asked. At fault time, an 2998 * attempt will be made for VM_NORESERVE to allocate a page 2999 * without using reserves 3000 */ 3001 if (vm_flags & VM_NORESERVE) 3002 return 0; 3003 3004 /* 3005 * Shared mappings base their reservation on the number of pages that 3006 * are already allocated on behalf of the file. Private mappings need 3007 * to reserve the full area even if read-only as mprotect() may be 3008 * called to make the mapping read-write. Assume !vma is a shm mapping 3009 */ 3010 if (!vma || vma->vm_flags & VM_MAYSHARE) 3011 chg = region_chg(&inode->i_mapping->private_list, from, to); 3012 else { 3013 struct resv_map *resv_map = resv_map_alloc(); 3014 if (!resv_map) 3015 return -ENOMEM; 3016 3017 chg = to - from; 3018 3019 set_vma_resv_map(vma, resv_map); 3020 set_vma_resv_flags(vma, HPAGE_RESV_OWNER); 3021 } 3022 3023 if (chg < 0) { 3024 ret = chg; 3025 goto out_err; 3026 } 3027 3028 /* There must be enough pages in the subpool for the mapping */ 3029 if (hugepage_subpool_get_pages(spool, chg)) { 3030 ret = -ENOSPC; 3031 goto out_err; 3032 } 3033 3034 /* 3035 * Check enough hugepages are available for the reservation. 3036 * Hand the pages back to the subpool if there are not 3037 */ 3038 ret = hugetlb_acct_memory(h, chg); 3039 if (ret < 0) { 3040 hugepage_subpool_put_pages(spool, chg); 3041 goto out_err; 3042 } 3043 3044 /* 3045 * Account for the reservations made. Shared mappings record regions 3046 * that have reservations as they are shared by multiple VMAs. 3047 * When the last VMA disappears, the region map says how much 3048 * the reservation was and the page cache tells how much of 3049 * the reservation was consumed. Private mappings are per-VMA and 3050 * only the consumed reservations are tracked. When the VMA 3051 * disappears, the original reservation is the VMA size and the 3052 * consumed reservations are stored in the map. Hence, nothing 3053 * else has to be done for private mappings here 3054 */ 3055 if (!vma || vma->vm_flags & VM_MAYSHARE) 3056 region_add(&inode->i_mapping->private_list, from, to); 3057 return 0; 3058out_err: 3059 if (vma) 3060 resv_map_put(vma); 3061 return ret; 3062} 3063 3064void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) 3065{ 3066 struct hstate *h = hstate_inode(inode); 3067 long chg = region_truncate(&inode->i_mapping->private_list, offset); 3068 struct hugepage_subpool *spool = subpool_inode(inode); 3069 3070 spin_lock(&inode->i_lock); 3071 inode->i_blocks -= (blocks_per_huge_page(h) * freed); 3072 spin_unlock(&inode->i_lock); 3073 3074 hugepage_subpool_put_pages(spool, (chg - freed)); 3075 hugetlb_acct_memory(h, -(chg - freed)); 3076} 3077 3078#ifdef CONFIG_MEMORY_FAILURE 3079 3080/* Should be called in hugetlb_lock */ 3081static int is_hugepage_on_freelist(struct page *hpage) 3082{ 3083 struct page *page; 3084 struct page *tmp; 3085 struct hstate *h = page_hstate(hpage); 3086 int nid = page_to_nid(hpage); 3087 3088 list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) 3089 if (page == hpage) 3090 return 1; 3091 return 0; 3092} 3093 3094/* 3095 * This function is called from memory failure code. 3096 * Assume the caller holds page lock of the head page. 3097 */ 3098int dequeue_hwpoisoned_huge_page(struct page *hpage) 3099{ 3100 struct hstate *h = page_hstate(hpage); 3101 int nid = page_to_nid(hpage); 3102 int ret = -EBUSY; 3103 3104 spin_lock(&hugetlb_lock); 3105 if (is_hugepage_on_freelist(hpage)) { 3106 list_del(&hpage->lru); 3107 set_page_refcounted(hpage); 3108 h->free_huge_pages--; 3109 h->free_huge_pages_node[nid]--; 3110 ret = 0; 3111 } 3112 spin_unlock(&hugetlb_lock); 3113 return ret; 3114} 3115#endif 3116