1 /* 2 * Generic hugetlb support. 3 * (C) Nadia Yvette Chambers, 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/compiler.h> 17 #include <linux/cpuset.h> 18 #include <linux/mutex.h> 19 #include <linux/bootmem.h> 20 #include <linux/sysfs.h> 21 #include <linux/slab.h> 22 #include <linux/rmap.h> 23 #include <linux/swap.h> 24 #include <linux/swapops.h> 25 #include <linux/page-isolation.h> 26 #include <linux/jhash.h> 27 28 #include <asm/page.h> 29 #include <asm/pgtable.h> 30 #include <asm/tlb.h> 31 32 #include <linux/io.h> 33 #include <linux/hugetlb.h> 34 #include <linux/hugetlb_cgroup.h> 35 #include <linux/node.h> 36 #include "internal.h" 37 38 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; 39 unsigned long hugepages_treat_as_movable; 40 41 int hugetlb_max_hstate __read_mostly; 42 unsigned int default_hstate_idx; 43 struct hstate hstates[HUGE_MAX_HSTATE]; 44 45 __initdata LIST_HEAD(huge_boot_pages); 46 47 /* for command line parsing */ 48 static struct hstate * __initdata parsed_hstate; 49 static unsigned long __initdata default_hstate_max_huge_pages; 50 static unsigned long __initdata default_hstate_size; 51 52 /* 53 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, 54 * free_huge_pages, and surplus_huge_pages. 55 */ 56 DEFINE_SPINLOCK(hugetlb_lock); 57 58 /* 59 * Serializes faults on the same logical page. This is used to 60 * prevent spurious OOMs when the hugepage pool is fully utilized. 61 */ 62 static int num_fault_mutexes; 63 static struct mutex *htlb_fault_mutex_table ____cacheline_aligned_in_smp; 64 65 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) 66 { 67 bool free = (spool->count == 0) && (spool->used_hpages == 0); 68 69 spin_unlock(&spool->lock); 70 71 /* If no pages are used, and no other handles to the subpool 72 * remain, free the subpool the subpool remain */ 73 if (free) 74 kfree(spool); 75 } 76 77 struct hugepage_subpool *hugepage_new_subpool(long nr_blocks) 78 { 79 struct hugepage_subpool *spool; 80 81 spool = kmalloc(sizeof(*spool), GFP_KERNEL); 82 if (!spool) 83 return NULL; 84 85 spin_lock_init(&spool->lock); 86 spool->count = 1; 87 spool->max_hpages = nr_blocks; 88 spool->used_hpages = 0; 89 90 return spool; 91 } 92 93 void hugepage_put_subpool(struct hugepage_subpool *spool) 94 { 95 spin_lock(&spool->lock); 96 BUG_ON(!spool->count); 97 spool->count--; 98 unlock_or_release_subpool(spool); 99 } 100 101 static int hugepage_subpool_get_pages(struct hugepage_subpool *spool, 102 long delta) 103 { 104 int ret = 0; 105 106 if (!spool) 107 return 0; 108 109 spin_lock(&spool->lock); 110 if ((spool->used_hpages + delta) <= spool->max_hpages) { 111 spool->used_hpages += delta; 112 } else { 113 ret = -ENOMEM; 114 } 115 spin_unlock(&spool->lock); 116 117 return ret; 118 } 119 120 static void hugepage_subpool_put_pages(struct hugepage_subpool *spool, 121 long delta) 122 { 123 if (!spool) 124 return; 125 126 spin_lock(&spool->lock); 127 spool->used_hpages -= delta; 128 /* If hugetlbfs_put_super couldn't free spool due to 129 * an outstanding quota reference, free it now. */ 130 unlock_or_release_subpool(spool); 131 } 132 133 static inline struct hugepage_subpool *subpool_inode(struct inode *inode) 134 { 135 return HUGETLBFS_SB(inode->i_sb)->spool; 136 } 137 138 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma) 139 { 140 return subpool_inode(file_inode(vma->vm_file)); 141 } 142 143 /* 144 * Region tracking -- allows tracking of reservations and instantiated pages 145 * across the pages in a mapping. 146 * 147 * The region data structures are embedded into a resv_map and 148 * protected by a resv_map's lock 149 */ 150 struct file_region { 151 struct list_head link; 152 long from; 153 long to; 154 }; 155 156 static long region_add(struct resv_map *resv, long f, long t) 157 { 158 struct list_head *head = &resv->regions; 159 struct file_region *rg, *nrg, *trg; 160 161 spin_lock(&resv->lock); 162 /* Locate the region we are either in or before. */ 163 list_for_each_entry(rg, head, link) 164 if (f <= rg->to) 165 break; 166 167 /* Round our left edge to the current segment if it encloses us. */ 168 if (f > rg->from) 169 f = rg->from; 170 171 /* Check for and consume any regions we now overlap with. */ 172 nrg = rg; 173 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 174 if (&rg->link == head) 175 break; 176 if (rg->from > t) 177 break; 178 179 /* If this area reaches higher then extend our area to 180 * include it completely. If this is not the first area 181 * which we intend to reuse, free it. */ 182 if (rg->to > t) 183 t = rg->to; 184 if (rg != nrg) { 185 list_del(&rg->link); 186 kfree(rg); 187 } 188 } 189 nrg->from = f; 190 nrg->to = t; 191 spin_unlock(&resv->lock); 192 return 0; 193 } 194 195 static long region_chg(struct resv_map *resv, long f, long t) 196 { 197 struct list_head *head = &resv->regions; 198 struct file_region *rg, *nrg = NULL; 199 long chg = 0; 200 201 retry: 202 spin_lock(&resv->lock); 203 /* Locate the region we are before or in. */ 204 list_for_each_entry(rg, head, link) 205 if (f <= rg->to) 206 break; 207 208 /* If we are below the current region then a new region is required. 209 * Subtle, allocate a new region at the position but make it zero 210 * size such that we can guarantee to record the reservation. */ 211 if (&rg->link == head || t < rg->from) { 212 if (!nrg) { 213 spin_unlock(&resv->lock); 214 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); 215 if (!nrg) 216 return -ENOMEM; 217 218 nrg->from = f; 219 nrg->to = f; 220 INIT_LIST_HEAD(&nrg->link); 221 goto retry; 222 } 223 224 list_add(&nrg->link, rg->link.prev); 225 chg = t - f; 226 goto out_nrg; 227 } 228 229 /* Round our left edge to the current segment if it encloses us. */ 230 if (f > rg->from) 231 f = rg->from; 232 chg = t - f; 233 234 /* Check for and consume any regions we now overlap with. */ 235 list_for_each_entry(rg, rg->link.prev, link) { 236 if (&rg->link == head) 237 break; 238 if (rg->from > t) 239 goto out; 240 241 /* We overlap with this area, if it extends further than 242 * us then we must extend ourselves. Account for its 243 * existing reservation. */ 244 if (rg->to > t) { 245 chg += rg->to - t; 246 t = rg->to; 247 } 248 chg -= rg->to - rg->from; 249 } 250 251 out: 252 spin_unlock(&resv->lock); 253 /* We already know we raced and no longer need the new region */ 254 kfree(nrg); 255 return chg; 256 out_nrg: 257 spin_unlock(&resv->lock); 258 return chg; 259 } 260 261 static long region_truncate(struct resv_map *resv, long end) 262 { 263 struct list_head *head = &resv->regions; 264 struct file_region *rg, *trg; 265 long chg = 0; 266 267 spin_lock(&resv->lock); 268 /* Locate the region we are either in or before. */ 269 list_for_each_entry(rg, head, link) 270 if (end <= rg->to) 271 break; 272 if (&rg->link == head) 273 goto out; 274 275 /* If we are in the middle of a region then adjust it. */ 276 if (end > rg->from) { 277 chg = rg->to - end; 278 rg->to = end; 279 rg = list_entry(rg->link.next, typeof(*rg), link); 280 } 281 282 /* Drop any remaining regions. */ 283 list_for_each_entry_safe(rg, trg, rg->link.prev, link) { 284 if (&rg->link == head) 285 break; 286 chg += rg->to - rg->from; 287 list_del(&rg->link); 288 kfree(rg); 289 } 290 291 out: 292 spin_unlock(&resv->lock); 293 return chg; 294 } 295 296 static long region_count(struct resv_map *resv, long f, long t) 297 { 298 struct list_head *head = &resv->regions; 299 struct file_region *rg; 300 long chg = 0; 301 302 spin_lock(&resv->lock); 303 /* Locate each segment we overlap with, and count that overlap. */ 304 list_for_each_entry(rg, head, link) { 305 long seg_from; 306 long seg_to; 307 308 if (rg->to <= f) 309 continue; 310 if (rg->from >= t) 311 break; 312 313 seg_from = max(rg->from, f); 314 seg_to = min(rg->to, t); 315 316 chg += seg_to - seg_from; 317 } 318 spin_unlock(&resv->lock); 319 320 return chg; 321 } 322 323 /* 324 * Convert the address within this vma to the page offset within 325 * the mapping, in pagecache page units; huge pages here. 326 */ 327 static pgoff_t vma_hugecache_offset(struct hstate *h, 328 struct vm_area_struct *vma, unsigned long address) 329 { 330 return ((address - vma->vm_start) >> huge_page_shift(h)) + 331 (vma->vm_pgoff >> huge_page_order(h)); 332 } 333 334 pgoff_t linear_hugepage_index(struct vm_area_struct *vma, 335 unsigned long address) 336 { 337 return vma_hugecache_offset(hstate_vma(vma), vma, address); 338 } 339 340 /* 341 * Return the size of the pages allocated when backing a VMA. In the majority 342 * cases this will be same size as used by the page table entries. 343 */ 344 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) 345 { 346 struct hstate *hstate; 347 348 if (!is_vm_hugetlb_page(vma)) 349 return PAGE_SIZE; 350 351 hstate = hstate_vma(vma); 352 353 return 1UL << huge_page_shift(hstate); 354 } 355 EXPORT_SYMBOL_GPL(vma_kernel_pagesize); 356 357 /* 358 * Return the page size being used by the MMU to back a VMA. In the majority 359 * of cases, the page size used by the kernel matches the MMU size. On 360 * architectures where it differs, an architecture-specific version of this 361 * function is required. 362 */ 363 #ifndef vma_mmu_pagesize 364 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) 365 { 366 return vma_kernel_pagesize(vma); 367 } 368 #endif 369 370 /* 371 * Flags for MAP_PRIVATE reservations. These are stored in the bottom 372 * bits of the reservation map pointer, which are always clear due to 373 * alignment. 374 */ 375 #define HPAGE_RESV_OWNER (1UL << 0) 376 #define HPAGE_RESV_UNMAPPED (1UL << 1) 377 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) 378 379 /* 380 * These helpers are used to track how many pages are reserved for 381 * faults in a MAP_PRIVATE mapping. Only the process that called mmap() 382 * is guaranteed to have their future faults succeed. 383 * 384 * With the exception of reset_vma_resv_huge_pages() which is called at fork(), 385 * the reserve counters are updated with the hugetlb_lock held. It is safe 386 * to reset the VMA at fork() time as it is not in use yet and there is no 387 * chance of the global counters getting corrupted as a result of the values. 388 * 389 * The private mapping reservation is represented in a subtly different 390 * manner to a shared mapping. A shared mapping has a region map associated 391 * with the underlying file, this region map represents the backing file 392 * pages which have ever had a reservation assigned which this persists even 393 * after the page is instantiated. A private mapping has a region map 394 * associated with the original mmap which is attached to all VMAs which 395 * reference it, this region map represents those offsets which have consumed 396 * reservation ie. where pages have been instantiated. 397 */ 398 static unsigned long get_vma_private_data(struct vm_area_struct *vma) 399 { 400 return (unsigned long)vma->vm_private_data; 401 } 402 403 static void set_vma_private_data(struct vm_area_struct *vma, 404 unsigned long value) 405 { 406 vma->vm_private_data = (void *)value; 407 } 408 409 struct resv_map *resv_map_alloc(void) 410 { 411 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); 412 if (!resv_map) 413 return NULL; 414 415 kref_init(&resv_map->refs); 416 spin_lock_init(&resv_map->lock); 417 INIT_LIST_HEAD(&resv_map->regions); 418 419 return resv_map; 420 } 421 422 void resv_map_release(struct kref *ref) 423 { 424 struct resv_map *resv_map = container_of(ref, struct resv_map, refs); 425 426 /* Clear out any active regions before we release the map. */ 427 region_truncate(resv_map, 0); 428 kfree(resv_map); 429 } 430 431 static inline struct resv_map *inode_resv_map(struct inode *inode) 432 { 433 return inode->i_mapping->private_data; 434 } 435 436 static struct resv_map *vma_resv_map(struct vm_area_struct *vma) 437 { 438 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 439 if (vma->vm_flags & VM_MAYSHARE) { 440 struct address_space *mapping = vma->vm_file->f_mapping; 441 struct inode *inode = mapping->host; 442 443 return inode_resv_map(inode); 444 445 } else { 446 return (struct resv_map *)(get_vma_private_data(vma) & 447 ~HPAGE_RESV_MASK); 448 } 449 } 450 451 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) 452 { 453 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 454 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 455 456 set_vma_private_data(vma, (get_vma_private_data(vma) & 457 HPAGE_RESV_MASK) | (unsigned long)map); 458 } 459 460 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) 461 { 462 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 463 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); 464 465 set_vma_private_data(vma, get_vma_private_data(vma) | flags); 466 } 467 468 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) 469 { 470 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 471 472 return (get_vma_private_data(vma) & flag) != 0; 473 } 474 475 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */ 476 void reset_vma_resv_huge_pages(struct vm_area_struct *vma) 477 { 478 VM_BUG_ON(!is_vm_hugetlb_page(vma)); 479 if (!(vma->vm_flags & VM_MAYSHARE)) 480 vma->vm_private_data = (void *)0; 481 } 482 483 /* Returns true if the VMA has associated reserve pages */ 484 static int vma_has_reserves(struct vm_area_struct *vma, long chg) 485 { 486 if (vma->vm_flags & VM_NORESERVE) { 487 /* 488 * This address is already reserved by other process(chg == 0), 489 * so, we should decrement reserved count. Without decrementing, 490 * reserve count remains after releasing inode, because this 491 * allocated page will go into page cache and is regarded as 492 * coming from reserved pool in releasing step. Currently, we 493 * don't have any other solution to deal with this situation 494 * properly, so add work-around here. 495 */ 496 if (vma->vm_flags & VM_MAYSHARE && chg == 0) 497 return 1; 498 else 499 return 0; 500 } 501 502 /* Shared mappings always use reserves */ 503 if (vma->vm_flags & VM_MAYSHARE) 504 return 1; 505 506 /* 507 * Only the process that called mmap() has reserves for 508 * private mappings. 509 */ 510 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 511 return 1; 512 513 return 0; 514 } 515 516 static void enqueue_huge_page(struct hstate *h, struct page *page) 517 { 518 int nid = page_to_nid(page); 519 list_move(&page->lru, &h->hugepage_freelists[nid]); 520 h->free_huge_pages++; 521 h->free_huge_pages_node[nid]++; 522 } 523 524 static struct page *dequeue_huge_page_node(struct hstate *h, int nid) 525 { 526 struct page *page; 527 528 list_for_each_entry(page, &h->hugepage_freelists[nid], lru) 529 if (!is_migrate_isolate_page(page)) 530 break; 531 /* 532 * if 'non-isolated free hugepage' not found on the list, 533 * the allocation fails. 534 */ 535 if (&h->hugepage_freelists[nid] == &page->lru) 536 return NULL; 537 list_move(&page->lru, &h->hugepage_activelist); 538 set_page_refcounted(page); 539 h->free_huge_pages--; 540 h->free_huge_pages_node[nid]--; 541 return page; 542 } 543 544 /* Movability of hugepages depends on migration support. */ 545 static inline gfp_t htlb_alloc_mask(struct hstate *h) 546 { 547 if (hugepages_treat_as_movable || hugepage_migration_support(h)) 548 return GFP_HIGHUSER_MOVABLE; 549 else 550 return GFP_HIGHUSER; 551 } 552 553 static struct page *dequeue_huge_page_vma(struct hstate *h, 554 struct vm_area_struct *vma, 555 unsigned long address, int avoid_reserve, 556 long chg) 557 { 558 struct page *page = NULL; 559 struct mempolicy *mpol; 560 nodemask_t *nodemask; 561 struct zonelist *zonelist; 562 struct zone *zone; 563 struct zoneref *z; 564 unsigned int cpuset_mems_cookie; 565 566 /* 567 * A child process with MAP_PRIVATE mappings created by their parent 568 * have no page reserves. This check ensures that reservations are 569 * not "stolen". The child may still get SIGKILLed 570 */ 571 if (!vma_has_reserves(vma, chg) && 572 h->free_huge_pages - h->resv_huge_pages == 0) 573 goto err; 574 575 /* If reserves cannot be used, ensure enough pages are in the pool */ 576 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) 577 goto err; 578 579 retry_cpuset: 580 cpuset_mems_cookie = read_mems_allowed_begin(); 581 zonelist = huge_zonelist(vma, address, 582 htlb_alloc_mask(h), &mpol, &nodemask); 583 584 for_each_zone_zonelist_nodemask(zone, z, zonelist, 585 MAX_NR_ZONES - 1, nodemask) { 586 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask(h))) { 587 page = dequeue_huge_page_node(h, zone_to_nid(zone)); 588 if (page) { 589 if (avoid_reserve) 590 break; 591 if (!vma_has_reserves(vma, chg)) 592 break; 593 594 SetPagePrivate(page); 595 h->resv_huge_pages--; 596 break; 597 } 598 } 599 } 600 601 mpol_cond_put(mpol); 602 if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) 603 goto retry_cpuset; 604 return page; 605 606 err: 607 return NULL; 608 } 609 610 static void update_and_free_page(struct hstate *h, struct page *page) 611 { 612 int i; 613 614 VM_BUG_ON(h->order >= MAX_ORDER); 615 616 h->nr_huge_pages--; 617 h->nr_huge_pages_node[page_to_nid(page)]--; 618 for (i = 0; i < pages_per_huge_page(h); i++) { 619 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 620 1 << PG_referenced | 1 << PG_dirty | 621 1 << PG_active | 1 << PG_reserved | 622 1 << PG_private | 1 << PG_writeback); 623 } 624 VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page); 625 set_compound_page_dtor(page, NULL); 626 set_page_refcounted(page); 627 arch_release_hugepage(page); 628 __free_pages(page, huge_page_order(h)); 629 } 630 631 struct hstate *size_to_hstate(unsigned long size) 632 { 633 struct hstate *h; 634 635 for_each_hstate(h) { 636 if (huge_page_size(h) == size) 637 return h; 638 } 639 return NULL; 640 } 641 642 static void free_huge_page(struct page *page) 643 { 644 /* 645 * Can't pass hstate in here because it is called from the 646 * compound page destructor. 647 */ 648 struct hstate *h = page_hstate(page); 649 int nid = page_to_nid(page); 650 struct hugepage_subpool *spool = 651 (struct hugepage_subpool *)page_private(page); 652 bool restore_reserve; 653 654 set_page_private(page, 0); 655 page->mapping = NULL; 656 BUG_ON(page_count(page)); 657 BUG_ON(page_mapcount(page)); 658 restore_reserve = PagePrivate(page); 659 ClearPagePrivate(page); 660 661 spin_lock(&hugetlb_lock); 662 hugetlb_cgroup_uncharge_page(hstate_index(h), 663 pages_per_huge_page(h), page); 664 if (restore_reserve) 665 h->resv_huge_pages++; 666 667 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { 668 /* remove the page from active list */ 669 list_del(&page->lru); 670 update_and_free_page(h, page); 671 h->surplus_huge_pages--; 672 h->surplus_huge_pages_node[nid]--; 673 } else { 674 arch_clear_hugepage_flags(page); 675 enqueue_huge_page(h, page); 676 } 677 spin_unlock(&hugetlb_lock); 678 hugepage_subpool_put_pages(spool, 1); 679 } 680 681 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) 682 { 683 INIT_LIST_HEAD(&page->lru); 684 set_compound_page_dtor(page, free_huge_page); 685 spin_lock(&hugetlb_lock); 686 set_hugetlb_cgroup(page, NULL); 687 h->nr_huge_pages++; 688 h->nr_huge_pages_node[nid]++; 689 spin_unlock(&hugetlb_lock); 690 put_page(page); /* free it into the hugepage allocator */ 691 } 692 693 static void __init prep_compound_gigantic_page(struct page *page, 694 unsigned long order) 695 { 696 int i; 697 int nr_pages = 1 << order; 698 struct page *p = page + 1; 699 700 /* we rely on prep_new_huge_page to set the destructor */ 701 set_compound_order(page, order); 702 __SetPageHead(page); 703 __ClearPageReserved(page); 704 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { 705 __SetPageTail(p); 706 /* 707 * For gigantic hugepages allocated through bootmem at 708 * boot, it's safer to be consistent with the not-gigantic 709 * hugepages and clear the PG_reserved bit from all tail pages 710 * too. Otherwse drivers using get_user_pages() to access tail 711 * pages may get the reference counting wrong if they see 712 * PG_reserved set on a tail page (despite the head page not 713 * having PG_reserved set). Enforcing this consistency between 714 * head and tail pages allows drivers to optimize away a check 715 * on the head page when they need know if put_page() is needed 716 * after get_user_pages(). 717 */ 718 __ClearPageReserved(p); 719 set_page_count(p, 0); 720 p->first_page = page; 721 } 722 } 723 724 /* 725 * PageHuge() only returns true for hugetlbfs pages, but not for normal or 726 * transparent huge pages. See the PageTransHuge() documentation for more 727 * details. 728 */ 729 int PageHuge(struct page *page) 730 { 731 if (!PageCompound(page)) 732 return 0; 733 734 page = compound_head(page); 735 return get_compound_page_dtor(page) == free_huge_page; 736 } 737 EXPORT_SYMBOL_GPL(PageHuge); 738 739 /* 740 * PageHeadHuge() only returns true for hugetlbfs head page, but not for 741 * normal or transparent huge pages. 742 */ 743 int PageHeadHuge(struct page *page_head) 744 { 745 if (!PageHead(page_head)) 746 return 0; 747 748 return get_compound_page_dtor(page_head) == free_huge_page; 749 } 750 751 pgoff_t __basepage_index(struct page *page) 752 { 753 struct page *page_head = compound_head(page); 754 pgoff_t index = page_index(page_head); 755 unsigned long compound_idx; 756 757 if (!PageHuge(page_head)) 758 return page_index(page); 759 760 if (compound_order(page_head) >= MAX_ORDER) 761 compound_idx = page_to_pfn(page) - page_to_pfn(page_head); 762 else 763 compound_idx = page - page_head; 764 765 return (index << compound_order(page_head)) + compound_idx; 766 } 767 768 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 769 { 770 struct page *page; 771 772 if (h->order >= MAX_ORDER) 773 return NULL; 774 775 page = alloc_pages_exact_node(nid, 776 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE| 777 __GFP_REPEAT|__GFP_NOWARN, 778 huge_page_order(h)); 779 if (page) { 780 if (arch_prepare_hugepage(page)) { 781 __free_pages(page, huge_page_order(h)); 782 return NULL; 783 } 784 prep_new_huge_page(h, page, nid); 785 } 786 787 return page; 788 } 789 790 /* 791 * common helper functions for hstate_next_node_to_{alloc|free}. 792 * We may have allocated or freed a huge page based on a different 793 * nodes_allowed previously, so h->next_node_to_{alloc|free} might 794 * be outside of *nodes_allowed. Ensure that we use an allowed 795 * node for alloc or free. 796 */ 797 static int next_node_allowed(int nid, nodemask_t *nodes_allowed) 798 { 799 nid = next_node(nid, *nodes_allowed); 800 if (nid == MAX_NUMNODES) 801 nid = first_node(*nodes_allowed); 802 VM_BUG_ON(nid >= MAX_NUMNODES); 803 804 return nid; 805 } 806 807 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) 808 { 809 if (!node_isset(nid, *nodes_allowed)) 810 nid = next_node_allowed(nid, nodes_allowed); 811 return nid; 812 } 813 814 /* 815 * returns the previously saved node ["this node"] from which to 816 * allocate a persistent huge page for the pool and advance the 817 * next node from which to allocate, handling wrap at end of node 818 * mask. 819 */ 820 static int hstate_next_node_to_alloc(struct hstate *h, 821 nodemask_t *nodes_allowed) 822 { 823 int nid; 824 825 VM_BUG_ON(!nodes_allowed); 826 827 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); 828 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); 829 830 return nid; 831 } 832 833 /* 834 * helper for free_pool_huge_page() - return the previously saved 835 * node ["this node"] from which to free a huge page. Advance the 836 * next node id whether or not we find a free huge page to free so 837 * that the next attempt to free addresses the next node. 838 */ 839 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) 840 { 841 int nid; 842 843 VM_BUG_ON(!nodes_allowed); 844 845 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); 846 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); 847 848 return nid; 849 } 850 851 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \ 852 for (nr_nodes = nodes_weight(*mask); \ 853 nr_nodes > 0 && \ 854 ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \ 855 nr_nodes--) 856 857 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \ 858 for (nr_nodes = nodes_weight(*mask); \ 859 nr_nodes > 0 && \ 860 ((node = hstate_next_node_to_free(hs, mask)) || 1); \ 861 nr_nodes--) 862 863 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) 864 { 865 struct page *page; 866 int nr_nodes, node; 867 int ret = 0; 868 869 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { 870 page = alloc_fresh_huge_page_node(h, node); 871 if (page) { 872 ret = 1; 873 break; 874 } 875 } 876 877 if (ret) 878 count_vm_event(HTLB_BUDDY_PGALLOC); 879 else 880 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 881 882 return ret; 883 } 884 885 /* 886 * Free huge page from pool from next node to free. 887 * Attempt to keep persistent huge pages more or less 888 * balanced over allowed nodes. 889 * Called with hugetlb_lock locked. 890 */ 891 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, 892 bool acct_surplus) 893 { 894 int nr_nodes, node; 895 int ret = 0; 896 897 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { 898 /* 899 * If we're returning unused surplus pages, only examine 900 * nodes with surplus pages. 901 */ 902 if ((!acct_surplus || h->surplus_huge_pages_node[node]) && 903 !list_empty(&h->hugepage_freelists[node])) { 904 struct page *page = 905 list_entry(h->hugepage_freelists[node].next, 906 struct page, lru); 907 list_del(&page->lru); 908 h->free_huge_pages--; 909 h->free_huge_pages_node[node]--; 910 if (acct_surplus) { 911 h->surplus_huge_pages--; 912 h->surplus_huge_pages_node[node]--; 913 } 914 update_and_free_page(h, page); 915 ret = 1; 916 break; 917 } 918 } 919 920 return ret; 921 } 922 923 /* 924 * Dissolve a given free hugepage into free buddy pages. This function does 925 * nothing for in-use (including surplus) hugepages. 926 */ 927 static void dissolve_free_huge_page(struct page *page) 928 { 929 spin_lock(&hugetlb_lock); 930 if (PageHuge(page) && !page_count(page)) { 931 struct hstate *h = page_hstate(page); 932 int nid = page_to_nid(page); 933 list_del(&page->lru); 934 h->free_huge_pages--; 935 h->free_huge_pages_node[nid]--; 936 update_and_free_page(h, page); 937 } 938 spin_unlock(&hugetlb_lock); 939 } 940 941 /* 942 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to 943 * make specified memory blocks removable from the system. 944 * Note that start_pfn should aligned with (minimum) hugepage size. 945 */ 946 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) 947 { 948 unsigned int order = 8 * sizeof(void *); 949 unsigned long pfn; 950 struct hstate *h; 951 952 /* Set scan step to minimum hugepage size */ 953 for_each_hstate(h) 954 if (order > huge_page_order(h)) 955 order = huge_page_order(h); 956 VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order)); 957 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) 958 dissolve_free_huge_page(pfn_to_page(pfn)); 959 } 960 961 static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) 962 { 963 struct page *page; 964 unsigned int r_nid; 965 966 if (h->order >= MAX_ORDER) 967 return NULL; 968 969 /* 970 * Assume we will successfully allocate the surplus page to 971 * prevent racing processes from causing the surplus to exceed 972 * overcommit 973 * 974 * This however introduces a different race, where a process B 975 * tries to grow the static hugepage pool while alloc_pages() is 976 * called by process A. B will only examine the per-node 977 * counters in determining if surplus huge pages can be 978 * converted to normal huge pages in adjust_pool_surplus(). A 979 * won't be able to increment the per-node counter, until the 980 * lock is dropped by B, but B doesn't drop hugetlb_lock until 981 * no more huge pages can be converted from surplus to normal 982 * state (and doesn't try to convert again). Thus, we have a 983 * case where a surplus huge page exists, the pool is grown, and 984 * the surplus huge page still exists after, even though it 985 * should just have been converted to a normal huge page. This 986 * does not leak memory, though, as the hugepage will be freed 987 * once it is out of use. It also does not allow the counters to 988 * go out of whack in adjust_pool_surplus() as we don't modify 989 * the node values until we've gotten the hugepage and only the 990 * per-node value is checked there. 991 */ 992 spin_lock(&hugetlb_lock); 993 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { 994 spin_unlock(&hugetlb_lock); 995 return NULL; 996 } else { 997 h->nr_huge_pages++; 998 h->surplus_huge_pages++; 999 } 1000 spin_unlock(&hugetlb_lock); 1001 1002 if (nid == NUMA_NO_NODE) 1003 page = alloc_pages(htlb_alloc_mask(h)|__GFP_COMP| 1004 __GFP_REPEAT|__GFP_NOWARN, 1005 huge_page_order(h)); 1006 else 1007 page = alloc_pages_exact_node(nid, 1008 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE| 1009 __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h)); 1010 1011 if (page && arch_prepare_hugepage(page)) { 1012 __free_pages(page, huge_page_order(h)); 1013 page = NULL; 1014 } 1015 1016 spin_lock(&hugetlb_lock); 1017 if (page) { 1018 INIT_LIST_HEAD(&page->lru); 1019 r_nid = page_to_nid(page); 1020 set_compound_page_dtor(page, free_huge_page); 1021 set_hugetlb_cgroup(page, NULL); 1022 /* 1023 * We incremented the global counters already 1024 */ 1025 h->nr_huge_pages_node[r_nid]++; 1026 h->surplus_huge_pages_node[r_nid]++; 1027 __count_vm_event(HTLB_BUDDY_PGALLOC); 1028 } else { 1029 h->nr_huge_pages--; 1030 h->surplus_huge_pages--; 1031 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); 1032 } 1033 spin_unlock(&hugetlb_lock); 1034 1035 return page; 1036 } 1037 1038 /* 1039 * This allocation function is useful in the context where vma is irrelevant. 1040 * E.g. soft-offlining uses this function because it only cares physical 1041 * address of error page. 1042 */ 1043 struct page *alloc_huge_page_node(struct hstate *h, int nid) 1044 { 1045 struct page *page = NULL; 1046 1047 spin_lock(&hugetlb_lock); 1048 if (h->free_huge_pages - h->resv_huge_pages > 0) 1049 page = dequeue_huge_page_node(h, nid); 1050 spin_unlock(&hugetlb_lock); 1051 1052 if (!page) 1053 page = alloc_buddy_huge_page(h, nid); 1054 1055 return page; 1056 } 1057 1058 /* 1059 * Increase the hugetlb pool such that it can accommodate a reservation 1060 * of size 'delta'. 1061 */ 1062 static int gather_surplus_pages(struct hstate *h, int delta) 1063 { 1064 struct list_head surplus_list; 1065 struct page *page, *tmp; 1066 int ret, i; 1067 int needed, allocated; 1068 bool alloc_ok = true; 1069 1070 needed = (h->resv_huge_pages + delta) - h->free_huge_pages; 1071 if (needed <= 0) { 1072 h->resv_huge_pages += delta; 1073 return 0; 1074 } 1075 1076 allocated = 0; 1077 INIT_LIST_HEAD(&surplus_list); 1078 1079 ret = -ENOMEM; 1080 retry: 1081 spin_unlock(&hugetlb_lock); 1082 for (i = 0; i < needed; i++) { 1083 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 1084 if (!page) { 1085 alloc_ok = false; 1086 break; 1087 } 1088 list_add(&page->lru, &surplus_list); 1089 } 1090 allocated += i; 1091 1092 /* 1093 * After retaking hugetlb_lock, we need to recalculate 'needed' 1094 * because either resv_huge_pages or free_huge_pages may have changed. 1095 */ 1096 spin_lock(&hugetlb_lock); 1097 needed = (h->resv_huge_pages + delta) - 1098 (h->free_huge_pages + allocated); 1099 if (needed > 0) { 1100 if (alloc_ok) 1101 goto retry; 1102 /* 1103 * We were not able to allocate enough pages to 1104 * satisfy the entire reservation so we free what 1105 * we've allocated so far. 1106 */ 1107 goto free; 1108 } 1109 /* 1110 * The surplus_list now contains _at_least_ the number of extra pages 1111 * needed to accommodate the reservation. Add the appropriate number 1112 * of pages to the hugetlb pool and free the extras back to the buddy 1113 * allocator. Commit the entire reservation here to prevent another 1114 * process from stealing the pages as they are added to the pool but 1115 * before they are reserved. 1116 */ 1117 needed += allocated; 1118 h->resv_huge_pages += delta; 1119 ret = 0; 1120 1121 /* Free the needed pages to the hugetlb pool */ 1122 list_for_each_entry_safe(page, tmp, &surplus_list, lru) { 1123 if ((--needed) < 0) 1124 break; 1125 /* 1126 * This page is now managed by the hugetlb allocator and has 1127 * no users -- drop the buddy allocator's reference. 1128 */ 1129 put_page_testzero(page); 1130 VM_BUG_ON_PAGE(page_count(page), page); 1131 enqueue_huge_page(h, page); 1132 } 1133 free: 1134 spin_unlock(&hugetlb_lock); 1135 1136 /* Free unnecessary surplus pages to the buddy allocator */ 1137 list_for_each_entry_safe(page, tmp, &surplus_list, lru) 1138 put_page(page); 1139 spin_lock(&hugetlb_lock); 1140 1141 return ret; 1142 } 1143 1144 /* 1145 * When releasing a hugetlb pool reservation, any surplus pages that were 1146 * allocated to satisfy the reservation must be explicitly freed if they were 1147 * never used. 1148 * Called with hugetlb_lock held. 1149 */ 1150 static void return_unused_surplus_pages(struct hstate *h, 1151 unsigned long unused_resv_pages) 1152 { 1153 unsigned long nr_pages; 1154 1155 /* Uncommit the reservation */ 1156 h->resv_huge_pages -= unused_resv_pages; 1157 1158 /* Cannot return gigantic pages currently */ 1159 if (h->order >= MAX_ORDER) 1160 return; 1161 1162 nr_pages = min(unused_resv_pages, h->surplus_huge_pages); 1163 1164 /* 1165 * We want to release as many surplus pages as possible, spread 1166 * evenly across all nodes with memory. Iterate across these nodes 1167 * until we can no longer free unreserved surplus pages. This occurs 1168 * when the nodes with surplus pages have no free pages. 1169 * free_pool_huge_page() will balance the the freed pages across the 1170 * on-line nodes with memory and will handle the hstate accounting. 1171 */ 1172 while (nr_pages--) { 1173 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1)) 1174 break; 1175 cond_resched_lock(&hugetlb_lock); 1176 } 1177 } 1178 1179 /* 1180 * Determine if the huge page at addr within the vma has an associated 1181 * reservation. Where it does not we will need to logically increase 1182 * reservation and actually increase subpool usage before an allocation 1183 * can occur. Where any new reservation would be required the 1184 * reservation change is prepared, but not committed. Once the page 1185 * has been allocated from the subpool and instantiated the change should 1186 * be committed via vma_commit_reservation. No action is required on 1187 * failure. 1188 */ 1189 static long vma_needs_reservation(struct hstate *h, 1190 struct vm_area_struct *vma, unsigned long addr) 1191 { 1192 struct resv_map *resv; 1193 pgoff_t idx; 1194 long chg; 1195 1196 resv = vma_resv_map(vma); 1197 if (!resv) 1198 return 1; 1199 1200 idx = vma_hugecache_offset(h, vma, addr); 1201 chg = region_chg(resv, idx, idx + 1); 1202 1203 if (vma->vm_flags & VM_MAYSHARE) 1204 return chg; 1205 else 1206 return chg < 0 ? chg : 0; 1207 } 1208 static void vma_commit_reservation(struct hstate *h, 1209 struct vm_area_struct *vma, unsigned long addr) 1210 { 1211 struct resv_map *resv; 1212 pgoff_t idx; 1213 1214 resv = vma_resv_map(vma); 1215 if (!resv) 1216 return; 1217 1218 idx = vma_hugecache_offset(h, vma, addr); 1219 region_add(resv, idx, idx + 1); 1220 } 1221 1222 static struct page *alloc_huge_page(struct vm_area_struct *vma, 1223 unsigned long addr, int avoid_reserve) 1224 { 1225 struct hugepage_subpool *spool = subpool_vma(vma); 1226 struct hstate *h = hstate_vma(vma); 1227 struct page *page; 1228 long chg; 1229 int ret, idx; 1230 struct hugetlb_cgroup *h_cg; 1231 1232 idx = hstate_index(h); 1233 /* 1234 * Processes that did not create the mapping will have no 1235 * reserves and will not have accounted against subpool 1236 * limit. Check that the subpool limit can be made before 1237 * satisfying the allocation MAP_NORESERVE mappings may also 1238 * need pages and subpool limit allocated allocated if no reserve 1239 * mapping overlaps. 1240 */ 1241 chg = vma_needs_reservation(h, vma, addr); 1242 if (chg < 0) 1243 return ERR_PTR(-ENOMEM); 1244 if (chg || avoid_reserve) 1245 if (hugepage_subpool_get_pages(spool, 1)) 1246 return ERR_PTR(-ENOSPC); 1247 1248 ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); 1249 if (ret) { 1250 if (chg || avoid_reserve) 1251 hugepage_subpool_put_pages(spool, 1); 1252 return ERR_PTR(-ENOSPC); 1253 } 1254 spin_lock(&hugetlb_lock); 1255 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg); 1256 if (!page) { 1257 spin_unlock(&hugetlb_lock); 1258 page = alloc_buddy_huge_page(h, NUMA_NO_NODE); 1259 if (!page) { 1260 hugetlb_cgroup_uncharge_cgroup(idx, 1261 pages_per_huge_page(h), 1262 h_cg); 1263 if (chg || avoid_reserve) 1264 hugepage_subpool_put_pages(spool, 1); 1265 return ERR_PTR(-ENOSPC); 1266 } 1267 spin_lock(&hugetlb_lock); 1268 list_move(&page->lru, &h->hugepage_activelist); 1269 /* Fall through */ 1270 } 1271 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page); 1272 spin_unlock(&hugetlb_lock); 1273 1274 set_page_private(page, (unsigned long)spool); 1275 1276 vma_commit_reservation(h, vma, addr); 1277 return page; 1278 } 1279 1280 /* 1281 * alloc_huge_page()'s wrapper which simply returns the page if allocation 1282 * succeeds, otherwise NULL. This function is called from new_vma_page(), 1283 * where no ERR_VALUE is expected to be returned. 1284 */ 1285 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma, 1286 unsigned long addr, int avoid_reserve) 1287 { 1288 struct page *page = alloc_huge_page(vma, addr, avoid_reserve); 1289 if (IS_ERR(page)) 1290 page = NULL; 1291 return page; 1292 } 1293 1294 int __weak alloc_bootmem_huge_page(struct hstate *h) 1295 { 1296 struct huge_bootmem_page *m; 1297 int nr_nodes, node; 1298 1299 for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) { 1300 void *addr; 1301 1302 addr = memblock_virt_alloc_try_nid_nopanic( 1303 huge_page_size(h), huge_page_size(h), 1304 0, BOOTMEM_ALLOC_ACCESSIBLE, node); 1305 if (addr) { 1306 /* 1307 * Use the beginning of the huge page to store the 1308 * huge_bootmem_page struct (until gather_bootmem 1309 * puts them into the mem_map). 1310 */ 1311 m = addr; 1312 goto found; 1313 } 1314 } 1315 return 0; 1316 1317 found: 1318 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); 1319 /* Put them into a private list first because mem_map is not up yet */ 1320 list_add(&m->list, &huge_boot_pages); 1321 m->hstate = h; 1322 return 1; 1323 } 1324 1325 static void __init prep_compound_huge_page(struct page *page, int order) 1326 { 1327 if (unlikely(order > (MAX_ORDER - 1))) 1328 prep_compound_gigantic_page(page, order); 1329 else 1330 prep_compound_page(page, order); 1331 } 1332 1333 /* Put bootmem huge pages into the standard lists after mem_map is up */ 1334 static void __init gather_bootmem_prealloc(void) 1335 { 1336 struct huge_bootmem_page *m; 1337 1338 list_for_each_entry(m, &huge_boot_pages, list) { 1339 struct hstate *h = m->hstate; 1340 struct page *page; 1341 1342 #ifdef CONFIG_HIGHMEM 1343 page = pfn_to_page(m->phys >> PAGE_SHIFT); 1344 memblock_free_late(__pa(m), 1345 sizeof(struct huge_bootmem_page)); 1346 #else 1347 page = virt_to_page(m); 1348 #endif 1349 WARN_ON(page_count(page) != 1); 1350 prep_compound_huge_page(page, h->order); 1351 WARN_ON(PageReserved(page)); 1352 prep_new_huge_page(h, page, page_to_nid(page)); 1353 /* 1354 * If we had gigantic hugepages allocated at boot time, we need 1355 * to restore the 'stolen' pages to totalram_pages in order to 1356 * fix confusing memory reports from free(1) and another 1357 * side-effects, like CommitLimit going negative. 1358 */ 1359 if (h->order > (MAX_ORDER - 1)) 1360 adjust_managed_page_count(page, 1 << h->order); 1361 } 1362 } 1363 1364 static void __init hugetlb_hstate_alloc_pages(struct hstate *h) 1365 { 1366 unsigned long i; 1367 1368 for (i = 0; i < h->max_huge_pages; ++i) { 1369 if (h->order >= MAX_ORDER) { 1370 if (!alloc_bootmem_huge_page(h)) 1371 break; 1372 } else if (!alloc_fresh_huge_page(h, 1373 &node_states[N_MEMORY])) 1374 break; 1375 } 1376 h->max_huge_pages = i; 1377 } 1378 1379 static void __init hugetlb_init_hstates(void) 1380 { 1381 struct hstate *h; 1382 1383 for_each_hstate(h) { 1384 /* oversize hugepages were init'ed in early boot */ 1385 if (h->order < MAX_ORDER) 1386 hugetlb_hstate_alloc_pages(h); 1387 } 1388 } 1389 1390 static char * __init memfmt(char *buf, unsigned long n) 1391 { 1392 if (n >= (1UL << 30)) 1393 sprintf(buf, "%lu GB", n >> 30); 1394 else if (n >= (1UL << 20)) 1395 sprintf(buf, "%lu MB", n >> 20); 1396 else 1397 sprintf(buf, "%lu KB", n >> 10); 1398 return buf; 1399 } 1400 1401 static void __init report_hugepages(void) 1402 { 1403 struct hstate *h; 1404 1405 for_each_hstate(h) { 1406 char buf[32]; 1407 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n", 1408 memfmt(buf, huge_page_size(h)), 1409 h->free_huge_pages); 1410 } 1411 } 1412 1413 #ifdef CONFIG_HIGHMEM 1414 static void try_to_free_low(struct hstate *h, unsigned long count, 1415 nodemask_t *nodes_allowed) 1416 { 1417 int i; 1418 1419 if (h->order >= MAX_ORDER) 1420 return; 1421 1422 for_each_node_mask(i, *nodes_allowed) { 1423 struct page *page, *next; 1424 struct list_head *freel = &h->hugepage_freelists[i]; 1425 list_for_each_entry_safe(page, next, freel, lru) { 1426 if (count >= h->nr_huge_pages) 1427 return; 1428 if (PageHighMem(page)) 1429 continue; 1430 list_del(&page->lru); 1431 update_and_free_page(h, page); 1432 h->free_huge_pages--; 1433 h->free_huge_pages_node[page_to_nid(page)]--; 1434 } 1435 } 1436 } 1437 #else 1438 static inline void try_to_free_low(struct hstate *h, unsigned long count, 1439 nodemask_t *nodes_allowed) 1440 { 1441 } 1442 #endif 1443 1444 /* 1445 * Increment or decrement surplus_huge_pages. Keep node-specific counters 1446 * balanced by operating on them in a round-robin fashion. 1447 * Returns 1 if an adjustment was made. 1448 */ 1449 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, 1450 int delta) 1451 { 1452 int nr_nodes, node; 1453 1454 VM_BUG_ON(delta != -1 && delta != 1); 1455 1456 if (delta < 0) { 1457 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { 1458 if (h->surplus_huge_pages_node[node]) 1459 goto found; 1460 } 1461 } else { 1462 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { 1463 if (h->surplus_huge_pages_node[node] < 1464 h->nr_huge_pages_node[node]) 1465 goto found; 1466 } 1467 } 1468 return 0; 1469 1470 found: 1471 h->surplus_huge_pages += delta; 1472 h->surplus_huge_pages_node[node] += delta; 1473 return 1; 1474 } 1475 1476 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) 1477 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, 1478 nodemask_t *nodes_allowed) 1479 { 1480 unsigned long min_count, ret; 1481 1482 if (h->order >= MAX_ORDER) 1483 return h->max_huge_pages; 1484 1485 /* 1486 * Increase the pool size 1487 * First take pages out of surplus state. Then make up the 1488 * remaining difference by allocating fresh huge pages. 1489 * 1490 * We might race with alloc_buddy_huge_page() here and be unable 1491 * to convert a surplus huge page to a normal huge page. That is 1492 * not critical, though, it just means the overall size of the 1493 * pool might be one hugepage larger than it needs to be, but 1494 * within all the constraints specified by the sysctls. 1495 */ 1496 spin_lock(&hugetlb_lock); 1497 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { 1498 if (!adjust_pool_surplus(h, nodes_allowed, -1)) 1499 break; 1500 } 1501 1502 while (count > persistent_huge_pages(h)) { 1503 /* 1504 * If this allocation races such that we no longer need the 1505 * page, free_huge_page will handle it by freeing the page 1506 * and reducing the surplus. 1507 */ 1508 spin_unlock(&hugetlb_lock); 1509 ret = alloc_fresh_huge_page(h, nodes_allowed); 1510 spin_lock(&hugetlb_lock); 1511 if (!ret) 1512 goto out; 1513 1514 /* Bail for signals. Probably ctrl-c from user */ 1515 if (signal_pending(current)) 1516 goto out; 1517 } 1518 1519 /* 1520 * Decrease the pool size 1521 * First return free pages to the buddy allocator (being careful 1522 * to keep enough around to satisfy reservations). Then place 1523 * pages into surplus state as needed so the pool will shrink 1524 * to the desired size as pages become free. 1525 * 1526 * By placing pages into the surplus state independent of the 1527 * overcommit value, we are allowing the surplus pool size to 1528 * exceed overcommit. There are few sane options here. Since 1529 * alloc_buddy_huge_page() is checking the global counter, 1530 * though, we'll note that we're not allowed to exceed surplus 1531 * and won't grow the pool anywhere else. Not until one of the 1532 * sysctls are changed, or the surplus pages go out of use. 1533 */ 1534 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; 1535 min_count = max(count, min_count); 1536 try_to_free_low(h, min_count, nodes_allowed); 1537 while (min_count < persistent_huge_pages(h)) { 1538 if (!free_pool_huge_page(h, nodes_allowed, 0)) 1539 break; 1540 cond_resched_lock(&hugetlb_lock); 1541 } 1542 while (count < persistent_huge_pages(h)) { 1543 if (!adjust_pool_surplus(h, nodes_allowed, 1)) 1544 break; 1545 } 1546 out: 1547 ret = persistent_huge_pages(h); 1548 spin_unlock(&hugetlb_lock); 1549 return ret; 1550 } 1551 1552 #define HSTATE_ATTR_RO(_name) \ 1553 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 1554 1555 #define HSTATE_ATTR(_name) \ 1556 static struct kobj_attribute _name##_attr = \ 1557 __ATTR(_name, 0644, _name##_show, _name##_store) 1558 1559 static struct kobject *hugepages_kobj; 1560 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1561 1562 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); 1563 1564 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) 1565 { 1566 int i; 1567 1568 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1569 if (hstate_kobjs[i] == kobj) { 1570 if (nidp) 1571 *nidp = NUMA_NO_NODE; 1572 return &hstates[i]; 1573 } 1574 1575 return kobj_to_node_hstate(kobj, nidp); 1576 } 1577 1578 static ssize_t nr_hugepages_show_common(struct kobject *kobj, 1579 struct kobj_attribute *attr, char *buf) 1580 { 1581 struct hstate *h; 1582 unsigned long nr_huge_pages; 1583 int nid; 1584 1585 h = kobj_to_hstate(kobj, &nid); 1586 if (nid == NUMA_NO_NODE) 1587 nr_huge_pages = h->nr_huge_pages; 1588 else 1589 nr_huge_pages = h->nr_huge_pages_node[nid]; 1590 1591 return sprintf(buf, "%lu\n", nr_huge_pages); 1592 } 1593 1594 static ssize_t nr_hugepages_store_common(bool obey_mempolicy, 1595 struct kobject *kobj, struct kobj_attribute *attr, 1596 const char *buf, size_t len) 1597 { 1598 int err; 1599 int nid; 1600 unsigned long count; 1601 struct hstate *h; 1602 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); 1603 1604 err = kstrtoul(buf, 10, &count); 1605 if (err) 1606 goto out; 1607 1608 h = kobj_to_hstate(kobj, &nid); 1609 if (h->order >= MAX_ORDER) { 1610 err = -EINVAL; 1611 goto out; 1612 } 1613 1614 if (nid == NUMA_NO_NODE) { 1615 /* 1616 * global hstate attribute 1617 */ 1618 if (!(obey_mempolicy && 1619 init_nodemask_of_mempolicy(nodes_allowed))) { 1620 NODEMASK_FREE(nodes_allowed); 1621 nodes_allowed = &node_states[N_MEMORY]; 1622 } 1623 } else if (nodes_allowed) { 1624 /* 1625 * per node hstate attribute: adjust count to global, 1626 * but restrict alloc/free to the specified node. 1627 */ 1628 count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; 1629 init_nodemask_of_node(nodes_allowed, nid); 1630 } else 1631 nodes_allowed = &node_states[N_MEMORY]; 1632 1633 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); 1634 1635 if (nodes_allowed != &node_states[N_MEMORY]) 1636 NODEMASK_FREE(nodes_allowed); 1637 1638 return len; 1639 out: 1640 NODEMASK_FREE(nodes_allowed); 1641 return err; 1642 } 1643 1644 static ssize_t nr_hugepages_show(struct kobject *kobj, 1645 struct kobj_attribute *attr, char *buf) 1646 { 1647 return nr_hugepages_show_common(kobj, attr, buf); 1648 } 1649 1650 static ssize_t nr_hugepages_store(struct kobject *kobj, 1651 struct kobj_attribute *attr, const char *buf, size_t len) 1652 { 1653 return nr_hugepages_store_common(false, kobj, attr, buf, len); 1654 } 1655 HSTATE_ATTR(nr_hugepages); 1656 1657 #ifdef CONFIG_NUMA 1658 1659 /* 1660 * hstate attribute for optionally mempolicy-based constraint on persistent 1661 * huge page alloc/free. 1662 */ 1663 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, 1664 struct kobj_attribute *attr, char *buf) 1665 { 1666 return nr_hugepages_show_common(kobj, attr, buf); 1667 } 1668 1669 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, 1670 struct kobj_attribute *attr, const char *buf, size_t len) 1671 { 1672 return nr_hugepages_store_common(true, kobj, attr, buf, len); 1673 } 1674 HSTATE_ATTR(nr_hugepages_mempolicy); 1675 #endif 1676 1677 1678 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, 1679 struct kobj_attribute *attr, char *buf) 1680 { 1681 struct hstate *h = kobj_to_hstate(kobj, NULL); 1682 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); 1683 } 1684 1685 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, 1686 struct kobj_attribute *attr, const char *buf, size_t count) 1687 { 1688 int err; 1689 unsigned long input; 1690 struct hstate *h = kobj_to_hstate(kobj, NULL); 1691 1692 if (h->order >= MAX_ORDER) 1693 return -EINVAL; 1694 1695 err = kstrtoul(buf, 10, &input); 1696 if (err) 1697 return err; 1698 1699 spin_lock(&hugetlb_lock); 1700 h->nr_overcommit_huge_pages = input; 1701 spin_unlock(&hugetlb_lock); 1702 1703 return count; 1704 } 1705 HSTATE_ATTR(nr_overcommit_hugepages); 1706 1707 static ssize_t free_hugepages_show(struct kobject *kobj, 1708 struct kobj_attribute *attr, char *buf) 1709 { 1710 struct hstate *h; 1711 unsigned long free_huge_pages; 1712 int nid; 1713 1714 h = kobj_to_hstate(kobj, &nid); 1715 if (nid == NUMA_NO_NODE) 1716 free_huge_pages = h->free_huge_pages; 1717 else 1718 free_huge_pages = h->free_huge_pages_node[nid]; 1719 1720 return sprintf(buf, "%lu\n", free_huge_pages); 1721 } 1722 HSTATE_ATTR_RO(free_hugepages); 1723 1724 static ssize_t resv_hugepages_show(struct kobject *kobj, 1725 struct kobj_attribute *attr, char *buf) 1726 { 1727 struct hstate *h = kobj_to_hstate(kobj, NULL); 1728 return sprintf(buf, "%lu\n", h->resv_huge_pages); 1729 } 1730 HSTATE_ATTR_RO(resv_hugepages); 1731 1732 static ssize_t surplus_hugepages_show(struct kobject *kobj, 1733 struct kobj_attribute *attr, char *buf) 1734 { 1735 struct hstate *h; 1736 unsigned long surplus_huge_pages; 1737 int nid; 1738 1739 h = kobj_to_hstate(kobj, &nid); 1740 if (nid == NUMA_NO_NODE) 1741 surplus_huge_pages = h->surplus_huge_pages; 1742 else 1743 surplus_huge_pages = h->surplus_huge_pages_node[nid]; 1744 1745 return sprintf(buf, "%lu\n", surplus_huge_pages); 1746 } 1747 HSTATE_ATTR_RO(surplus_hugepages); 1748 1749 static struct attribute *hstate_attrs[] = { 1750 &nr_hugepages_attr.attr, 1751 &nr_overcommit_hugepages_attr.attr, 1752 &free_hugepages_attr.attr, 1753 &resv_hugepages_attr.attr, 1754 &surplus_hugepages_attr.attr, 1755 #ifdef CONFIG_NUMA 1756 &nr_hugepages_mempolicy_attr.attr, 1757 #endif 1758 NULL, 1759 }; 1760 1761 static struct attribute_group hstate_attr_group = { 1762 .attrs = hstate_attrs, 1763 }; 1764 1765 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, 1766 struct kobject **hstate_kobjs, 1767 struct attribute_group *hstate_attr_group) 1768 { 1769 int retval; 1770 int hi = hstate_index(h); 1771 1772 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); 1773 if (!hstate_kobjs[hi]) 1774 return -ENOMEM; 1775 1776 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); 1777 if (retval) 1778 kobject_put(hstate_kobjs[hi]); 1779 1780 return retval; 1781 } 1782 1783 static void __init hugetlb_sysfs_init(void) 1784 { 1785 struct hstate *h; 1786 int err; 1787 1788 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); 1789 if (!hugepages_kobj) 1790 return; 1791 1792 for_each_hstate(h) { 1793 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, 1794 hstate_kobjs, &hstate_attr_group); 1795 if (err) 1796 pr_err("Hugetlb: Unable to add hstate %s", h->name); 1797 } 1798 } 1799 1800 #ifdef CONFIG_NUMA 1801 1802 /* 1803 * node_hstate/s - associate per node hstate attributes, via their kobjects, 1804 * with node devices in node_devices[] using a parallel array. The array 1805 * index of a node device or _hstate == node id. 1806 * This is here to avoid any static dependency of the node device driver, in 1807 * the base kernel, on the hugetlb module. 1808 */ 1809 struct node_hstate { 1810 struct kobject *hugepages_kobj; 1811 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; 1812 }; 1813 struct node_hstate node_hstates[MAX_NUMNODES]; 1814 1815 /* 1816 * A subset of global hstate attributes for node devices 1817 */ 1818 static struct attribute *per_node_hstate_attrs[] = { 1819 &nr_hugepages_attr.attr, 1820 &free_hugepages_attr.attr, 1821 &surplus_hugepages_attr.attr, 1822 NULL, 1823 }; 1824 1825 static struct attribute_group per_node_hstate_attr_group = { 1826 .attrs = per_node_hstate_attrs, 1827 }; 1828 1829 /* 1830 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. 1831 * Returns node id via non-NULL nidp. 1832 */ 1833 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1834 { 1835 int nid; 1836 1837 for (nid = 0; nid < nr_node_ids; nid++) { 1838 struct node_hstate *nhs = &node_hstates[nid]; 1839 int i; 1840 for (i = 0; i < HUGE_MAX_HSTATE; i++) 1841 if (nhs->hstate_kobjs[i] == kobj) { 1842 if (nidp) 1843 *nidp = nid; 1844 return &hstates[i]; 1845 } 1846 } 1847 1848 BUG(); 1849 return NULL; 1850 } 1851 1852 /* 1853 * Unregister hstate attributes from a single node device. 1854 * No-op if no hstate attributes attached. 1855 */ 1856 static void hugetlb_unregister_node(struct node *node) 1857 { 1858 struct hstate *h; 1859 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1860 1861 if (!nhs->hugepages_kobj) 1862 return; /* no hstate attributes */ 1863 1864 for_each_hstate(h) { 1865 int idx = hstate_index(h); 1866 if (nhs->hstate_kobjs[idx]) { 1867 kobject_put(nhs->hstate_kobjs[idx]); 1868 nhs->hstate_kobjs[idx] = NULL; 1869 } 1870 } 1871 1872 kobject_put(nhs->hugepages_kobj); 1873 nhs->hugepages_kobj = NULL; 1874 } 1875 1876 /* 1877 * hugetlb module exit: unregister hstate attributes from node devices 1878 * that have them. 1879 */ 1880 static void hugetlb_unregister_all_nodes(void) 1881 { 1882 int nid; 1883 1884 /* 1885 * disable node device registrations. 1886 */ 1887 register_hugetlbfs_with_node(NULL, NULL); 1888 1889 /* 1890 * remove hstate attributes from any nodes that have them. 1891 */ 1892 for (nid = 0; nid < nr_node_ids; nid++) 1893 hugetlb_unregister_node(node_devices[nid]); 1894 } 1895 1896 /* 1897 * Register hstate attributes for a single node device. 1898 * No-op if attributes already registered. 1899 */ 1900 static void hugetlb_register_node(struct node *node) 1901 { 1902 struct hstate *h; 1903 struct node_hstate *nhs = &node_hstates[node->dev.id]; 1904 int err; 1905 1906 if (nhs->hugepages_kobj) 1907 return; /* already allocated */ 1908 1909 nhs->hugepages_kobj = kobject_create_and_add("hugepages", 1910 &node->dev.kobj); 1911 if (!nhs->hugepages_kobj) 1912 return; 1913 1914 for_each_hstate(h) { 1915 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, 1916 nhs->hstate_kobjs, 1917 &per_node_hstate_attr_group); 1918 if (err) { 1919 pr_err("Hugetlb: Unable to add hstate %s for node %d\n", 1920 h->name, node->dev.id); 1921 hugetlb_unregister_node(node); 1922 break; 1923 } 1924 } 1925 } 1926 1927 /* 1928 * hugetlb init time: register hstate attributes for all registered node 1929 * devices of nodes that have memory. All on-line nodes should have 1930 * registered their associated device by this time. 1931 */ 1932 static void hugetlb_register_all_nodes(void) 1933 { 1934 int nid; 1935 1936 for_each_node_state(nid, N_MEMORY) { 1937 struct node *node = node_devices[nid]; 1938 if (node->dev.id == nid) 1939 hugetlb_register_node(node); 1940 } 1941 1942 /* 1943 * Let the node device driver know we're here so it can 1944 * [un]register hstate attributes on node hotplug. 1945 */ 1946 register_hugetlbfs_with_node(hugetlb_register_node, 1947 hugetlb_unregister_node); 1948 } 1949 #else /* !CONFIG_NUMA */ 1950 1951 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) 1952 { 1953 BUG(); 1954 if (nidp) 1955 *nidp = -1; 1956 return NULL; 1957 } 1958 1959 static void hugetlb_unregister_all_nodes(void) { } 1960 1961 static void hugetlb_register_all_nodes(void) { } 1962 1963 #endif 1964 1965 static void __exit hugetlb_exit(void) 1966 { 1967 struct hstate *h; 1968 1969 hugetlb_unregister_all_nodes(); 1970 1971 for_each_hstate(h) { 1972 kobject_put(hstate_kobjs[hstate_index(h)]); 1973 } 1974 1975 kobject_put(hugepages_kobj); 1976 kfree(htlb_fault_mutex_table); 1977 } 1978 module_exit(hugetlb_exit); 1979 1980 static int __init hugetlb_init(void) 1981 { 1982 int i; 1983 1984 /* Some platform decide whether they support huge pages at boot 1985 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when 1986 * there is no such support 1987 */ 1988 if (HPAGE_SHIFT == 0) 1989 return 0; 1990 1991 if (!size_to_hstate(default_hstate_size)) { 1992 default_hstate_size = HPAGE_SIZE; 1993 if (!size_to_hstate(default_hstate_size)) 1994 hugetlb_add_hstate(HUGETLB_PAGE_ORDER); 1995 } 1996 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size)); 1997 if (default_hstate_max_huge_pages) 1998 default_hstate.max_huge_pages = default_hstate_max_huge_pages; 1999 2000 hugetlb_init_hstates(); 2001 gather_bootmem_prealloc(); 2002 report_hugepages(); 2003 2004 hugetlb_sysfs_init(); 2005 hugetlb_register_all_nodes(); 2006 hugetlb_cgroup_file_init(); 2007 2008 #ifdef CONFIG_SMP 2009 num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus()); 2010 #else 2011 num_fault_mutexes = 1; 2012 #endif 2013 htlb_fault_mutex_table = 2014 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL); 2015 BUG_ON(!htlb_fault_mutex_table); 2016 2017 for (i = 0; i < num_fault_mutexes; i++) 2018 mutex_init(&htlb_fault_mutex_table[i]); 2019 return 0; 2020 } 2021 module_init(hugetlb_init); 2022 2023 /* Should be called on processing a hugepagesz=... option */ 2024 void __init hugetlb_add_hstate(unsigned order) 2025 { 2026 struct hstate *h; 2027 unsigned long i; 2028 2029 if (size_to_hstate(PAGE_SIZE << order)) { 2030 pr_warning("hugepagesz= specified twice, ignoring\n"); 2031 return; 2032 } 2033 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); 2034 BUG_ON(order == 0); 2035 h = &hstates[hugetlb_max_hstate++]; 2036 h->order = order; 2037 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); 2038 h->nr_huge_pages = 0; 2039 h->free_huge_pages = 0; 2040 for (i = 0; i < MAX_NUMNODES; ++i) 2041 INIT_LIST_HEAD(&h->hugepage_freelists[i]); 2042 INIT_LIST_HEAD(&h->hugepage_activelist); 2043 h->next_nid_to_alloc = first_node(node_states[N_MEMORY]); 2044 h->next_nid_to_free = first_node(node_states[N_MEMORY]); 2045 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", 2046 huge_page_size(h)/1024); 2047 2048 parsed_hstate = h; 2049 } 2050 2051 static int __init hugetlb_nrpages_setup(char *s) 2052 { 2053 unsigned long *mhp; 2054 static unsigned long *last_mhp; 2055 2056 /* 2057 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet, 2058 * so this hugepages= parameter goes to the "default hstate". 2059 */ 2060 if (!hugetlb_max_hstate) 2061 mhp = &default_hstate_max_huge_pages; 2062 else 2063 mhp = &parsed_hstate->max_huge_pages; 2064 2065 if (mhp == last_mhp) { 2066 pr_warning("hugepages= specified twice without " 2067 "interleaving hugepagesz=, ignoring\n"); 2068 return 1; 2069 } 2070 2071 if (sscanf(s, "%lu", mhp) <= 0) 2072 *mhp = 0; 2073 2074 /* 2075 * Global state is always initialized later in hugetlb_init. 2076 * But we need to allocate >= MAX_ORDER hstates here early to still 2077 * use the bootmem allocator. 2078 */ 2079 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER) 2080 hugetlb_hstate_alloc_pages(parsed_hstate); 2081 2082 last_mhp = mhp; 2083 2084 return 1; 2085 } 2086 __setup("hugepages=", hugetlb_nrpages_setup); 2087 2088 static int __init hugetlb_default_setup(char *s) 2089 { 2090 default_hstate_size = memparse(s, &s); 2091 return 1; 2092 } 2093 __setup("default_hugepagesz=", hugetlb_default_setup); 2094 2095 static unsigned int cpuset_mems_nr(unsigned int *array) 2096 { 2097 int node; 2098 unsigned int nr = 0; 2099 2100 for_each_node_mask(node, cpuset_current_mems_allowed) 2101 nr += array[node]; 2102 2103 return nr; 2104 } 2105 2106 #ifdef CONFIG_SYSCTL 2107 static int hugetlb_sysctl_handler_common(bool obey_mempolicy, 2108 struct ctl_table *table, int write, 2109 void __user *buffer, size_t *length, loff_t *ppos) 2110 { 2111 struct hstate *h = &default_hstate; 2112 unsigned long tmp; 2113 int ret; 2114 2115 tmp = h->max_huge_pages; 2116 2117 if (write && h->order >= MAX_ORDER) 2118 return -EINVAL; 2119 2120 table->data = &tmp; 2121 table->maxlen = sizeof(unsigned long); 2122 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 2123 if (ret) 2124 goto out; 2125 2126 if (write) { 2127 NODEMASK_ALLOC(nodemask_t, nodes_allowed, 2128 GFP_KERNEL | __GFP_NORETRY); 2129 if (!(obey_mempolicy && 2130 init_nodemask_of_mempolicy(nodes_allowed))) { 2131 NODEMASK_FREE(nodes_allowed); 2132 nodes_allowed = &node_states[N_MEMORY]; 2133 } 2134 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); 2135 2136 if (nodes_allowed != &node_states[N_MEMORY]) 2137 NODEMASK_FREE(nodes_allowed); 2138 } 2139 out: 2140 return ret; 2141 } 2142 2143 int hugetlb_sysctl_handler(struct ctl_table *table, int write, 2144 void __user *buffer, size_t *length, loff_t *ppos) 2145 { 2146 2147 return hugetlb_sysctl_handler_common(false, table, write, 2148 buffer, length, ppos); 2149 } 2150 2151 #ifdef CONFIG_NUMA 2152 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, 2153 void __user *buffer, size_t *length, loff_t *ppos) 2154 { 2155 return hugetlb_sysctl_handler_common(true, table, write, 2156 buffer, length, ppos); 2157 } 2158 #endif /* CONFIG_NUMA */ 2159 2160 int hugetlb_overcommit_handler(struct ctl_table *table, int write, 2161 void __user *buffer, 2162 size_t *length, loff_t *ppos) 2163 { 2164 struct hstate *h = &default_hstate; 2165 unsigned long tmp; 2166 int ret; 2167 2168 tmp = h->nr_overcommit_huge_pages; 2169 2170 if (write && h->order >= MAX_ORDER) 2171 return -EINVAL; 2172 2173 table->data = &tmp; 2174 table->maxlen = sizeof(unsigned long); 2175 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); 2176 if (ret) 2177 goto out; 2178 2179 if (write) { 2180 spin_lock(&hugetlb_lock); 2181 h->nr_overcommit_huge_pages = tmp; 2182 spin_unlock(&hugetlb_lock); 2183 } 2184 out: 2185 return ret; 2186 } 2187 2188 #endif /* CONFIG_SYSCTL */ 2189 2190 void hugetlb_report_meminfo(struct seq_file *m) 2191 { 2192 struct hstate *h = &default_hstate; 2193 seq_printf(m, 2194 "HugePages_Total: %5lu\n" 2195 "HugePages_Free: %5lu\n" 2196 "HugePages_Rsvd: %5lu\n" 2197 "HugePages_Surp: %5lu\n" 2198 "Hugepagesize: %8lu kB\n", 2199 h->nr_huge_pages, 2200 h->free_huge_pages, 2201 h->resv_huge_pages, 2202 h->surplus_huge_pages, 2203 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 2204 } 2205 2206 int hugetlb_report_node_meminfo(int nid, char *buf) 2207 { 2208 struct hstate *h = &default_hstate; 2209 return sprintf(buf, 2210 "Node %d HugePages_Total: %5u\n" 2211 "Node %d HugePages_Free: %5u\n" 2212 "Node %d HugePages_Surp: %5u\n", 2213 nid, h->nr_huge_pages_node[nid], 2214 nid, h->free_huge_pages_node[nid], 2215 nid, h->surplus_huge_pages_node[nid]); 2216 } 2217 2218 void hugetlb_show_meminfo(void) 2219 { 2220 struct hstate *h; 2221 int nid; 2222 2223 for_each_node_state(nid, N_MEMORY) 2224 for_each_hstate(h) 2225 pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n", 2226 nid, 2227 h->nr_huge_pages_node[nid], 2228 h->free_huge_pages_node[nid], 2229 h->surplus_huge_pages_node[nid], 2230 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); 2231 } 2232 2233 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ 2234 unsigned long hugetlb_total_pages(void) 2235 { 2236 struct hstate *h; 2237 unsigned long nr_total_pages = 0; 2238 2239 for_each_hstate(h) 2240 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h); 2241 return nr_total_pages; 2242 } 2243 2244 static int hugetlb_acct_memory(struct hstate *h, long delta) 2245 { 2246 int ret = -ENOMEM; 2247 2248 spin_lock(&hugetlb_lock); 2249 /* 2250 * When cpuset is configured, it breaks the strict hugetlb page 2251 * reservation as the accounting is done on a global variable. Such 2252 * reservation is completely rubbish in the presence of cpuset because 2253 * the reservation is not checked against page availability for the 2254 * current cpuset. Application can still potentially OOM'ed by kernel 2255 * with lack of free htlb page in cpuset that the task is in. 2256 * Attempt to enforce strict accounting with cpuset is almost 2257 * impossible (or too ugly) because cpuset is too fluid that 2258 * task or memory node can be dynamically moved between cpusets. 2259 * 2260 * The change of semantics for shared hugetlb mapping with cpuset is 2261 * undesirable. However, in order to preserve some of the semantics, 2262 * we fall back to check against current free page availability as 2263 * a best attempt and hopefully to minimize the impact of changing 2264 * semantics that cpuset has. 2265 */ 2266 if (delta > 0) { 2267 if (gather_surplus_pages(h, delta) < 0) 2268 goto out; 2269 2270 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { 2271 return_unused_surplus_pages(h, delta); 2272 goto out; 2273 } 2274 } 2275 2276 ret = 0; 2277 if (delta < 0) 2278 return_unused_surplus_pages(h, (unsigned long) -delta); 2279 2280 out: 2281 spin_unlock(&hugetlb_lock); 2282 return ret; 2283 } 2284 2285 static void hugetlb_vm_op_open(struct vm_area_struct *vma) 2286 { 2287 struct resv_map *resv = vma_resv_map(vma); 2288 2289 /* 2290 * This new VMA should share its siblings reservation map if present. 2291 * The VMA will only ever have a valid reservation map pointer where 2292 * it is being copied for another still existing VMA. As that VMA 2293 * has a reference to the reservation map it cannot disappear until 2294 * after this open call completes. It is therefore safe to take a 2295 * new reference here without additional locking. 2296 */ 2297 if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 2298 kref_get(&resv->refs); 2299 } 2300 2301 static void hugetlb_vm_op_close(struct vm_area_struct *vma) 2302 { 2303 struct hstate *h = hstate_vma(vma); 2304 struct resv_map *resv = vma_resv_map(vma); 2305 struct hugepage_subpool *spool = subpool_vma(vma); 2306 unsigned long reserve, start, end; 2307 2308 if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 2309 return; 2310 2311 start = vma_hugecache_offset(h, vma, vma->vm_start); 2312 end = vma_hugecache_offset(h, vma, vma->vm_end); 2313 2314 reserve = (end - start) - region_count(resv, start, end); 2315 2316 kref_put(&resv->refs, resv_map_release); 2317 2318 if (reserve) { 2319 hugetlb_acct_memory(h, -reserve); 2320 hugepage_subpool_put_pages(spool, reserve); 2321 } 2322 } 2323 2324 /* 2325 * We cannot handle pagefaults against hugetlb pages at all. They cause 2326 * handle_mm_fault() to try to instantiate regular-sized pages in the 2327 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get 2328 * this far. 2329 */ 2330 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 2331 { 2332 BUG(); 2333 return 0; 2334 } 2335 2336 const struct vm_operations_struct hugetlb_vm_ops = { 2337 .fault = hugetlb_vm_op_fault, 2338 .open = hugetlb_vm_op_open, 2339 .close = hugetlb_vm_op_close, 2340 }; 2341 2342 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, 2343 int writable) 2344 { 2345 pte_t entry; 2346 2347 if (writable) { 2348 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page, 2349 vma->vm_page_prot))); 2350 } else { 2351 entry = huge_pte_wrprotect(mk_huge_pte(page, 2352 vma->vm_page_prot)); 2353 } 2354 entry = pte_mkyoung(entry); 2355 entry = pte_mkhuge(entry); 2356 entry = arch_make_huge_pte(entry, vma, page, writable); 2357 2358 return entry; 2359 } 2360 2361 static void set_huge_ptep_writable(struct vm_area_struct *vma, 2362 unsigned long address, pte_t *ptep) 2363 { 2364 pte_t entry; 2365 2366 entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep))); 2367 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) 2368 update_mmu_cache(vma, address, ptep); 2369 } 2370 2371 2372 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, 2373 struct vm_area_struct *vma) 2374 { 2375 pte_t *src_pte, *dst_pte, entry; 2376 struct page *ptepage; 2377 unsigned long addr; 2378 int cow; 2379 struct hstate *h = hstate_vma(vma); 2380 unsigned long sz = huge_page_size(h); 2381 unsigned long mmun_start; /* For mmu_notifiers */ 2382 unsigned long mmun_end; /* For mmu_notifiers */ 2383 int ret = 0; 2384 2385 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 2386 2387 mmun_start = vma->vm_start; 2388 mmun_end = vma->vm_end; 2389 if (cow) 2390 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end); 2391 2392 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { 2393 spinlock_t *src_ptl, *dst_ptl; 2394 src_pte = huge_pte_offset(src, addr); 2395 if (!src_pte) 2396 continue; 2397 dst_pte = huge_pte_alloc(dst, addr, sz); 2398 if (!dst_pte) { 2399 ret = -ENOMEM; 2400 break; 2401 } 2402 2403 /* If the pagetables are shared don't copy or take references */ 2404 if (dst_pte == src_pte) 2405 continue; 2406 2407 dst_ptl = huge_pte_lock(h, dst, dst_pte); 2408 src_ptl = huge_pte_lockptr(h, src, src_pte); 2409 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 2410 if (!huge_pte_none(huge_ptep_get(src_pte))) { 2411 if (cow) 2412 huge_ptep_set_wrprotect(src, addr, src_pte); 2413 entry = huge_ptep_get(src_pte); 2414 ptepage = pte_page(entry); 2415 get_page(ptepage); 2416 page_dup_rmap(ptepage); 2417 set_huge_pte_at(dst, addr, dst_pte, entry); 2418 } 2419 spin_unlock(src_ptl); 2420 spin_unlock(dst_ptl); 2421 } 2422 2423 if (cow) 2424 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end); 2425 2426 return ret; 2427 } 2428 2429 static int is_hugetlb_entry_migration(pte_t pte) 2430 { 2431 swp_entry_t swp; 2432 2433 if (huge_pte_none(pte) || pte_present(pte)) 2434 return 0; 2435 swp = pte_to_swp_entry(pte); 2436 if (non_swap_entry(swp) && is_migration_entry(swp)) 2437 return 1; 2438 else 2439 return 0; 2440 } 2441 2442 static int is_hugetlb_entry_hwpoisoned(pte_t pte) 2443 { 2444 swp_entry_t swp; 2445 2446 if (huge_pte_none(pte) || pte_present(pte)) 2447 return 0; 2448 swp = pte_to_swp_entry(pte); 2449 if (non_swap_entry(swp) && is_hwpoison_entry(swp)) 2450 return 1; 2451 else 2452 return 0; 2453 } 2454 2455 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, 2456 unsigned long start, unsigned long end, 2457 struct page *ref_page) 2458 { 2459 int force_flush = 0; 2460 struct mm_struct *mm = vma->vm_mm; 2461 unsigned long address; 2462 pte_t *ptep; 2463 pte_t pte; 2464 spinlock_t *ptl; 2465 struct page *page; 2466 struct hstate *h = hstate_vma(vma); 2467 unsigned long sz = huge_page_size(h); 2468 const unsigned long mmun_start = start; /* For mmu_notifiers */ 2469 const unsigned long mmun_end = end; /* For mmu_notifiers */ 2470 2471 WARN_ON(!is_vm_hugetlb_page(vma)); 2472 BUG_ON(start & ~huge_page_mask(h)); 2473 BUG_ON(end & ~huge_page_mask(h)); 2474 2475 tlb_start_vma(tlb, vma); 2476 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2477 again: 2478 for (address = start; address < end; address += sz) { 2479 ptep = huge_pte_offset(mm, address); 2480 if (!ptep) 2481 continue; 2482 2483 ptl = huge_pte_lock(h, mm, ptep); 2484 if (huge_pmd_unshare(mm, &address, ptep)) 2485 goto unlock; 2486 2487 pte = huge_ptep_get(ptep); 2488 if (huge_pte_none(pte)) 2489 goto unlock; 2490 2491 /* 2492 * HWPoisoned hugepage is already unmapped and dropped reference 2493 */ 2494 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) { 2495 huge_pte_clear(mm, address, ptep); 2496 goto unlock; 2497 } 2498 2499 page = pte_page(pte); 2500 /* 2501 * If a reference page is supplied, it is because a specific 2502 * page is being unmapped, not a range. Ensure the page we 2503 * are about to unmap is the actual page of interest. 2504 */ 2505 if (ref_page) { 2506 if (page != ref_page) 2507 goto unlock; 2508 2509 /* 2510 * Mark the VMA as having unmapped its page so that 2511 * future faults in this VMA will fail rather than 2512 * looking like data was lost 2513 */ 2514 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); 2515 } 2516 2517 pte = huge_ptep_get_and_clear(mm, address, ptep); 2518 tlb_remove_tlb_entry(tlb, ptep, address); 2519 if (huge_pte_dirty(pte)) 2520 set_page_dirty(page); 2521 2522 page_remove_rmap(page); 2523 force_flush = !__tlb_remove_page(tlb, page); 2524 if (force_flush) { 2525 spin_unlock(ptl); 2526 break; 2527 } 2528 /* Bail out after unmapping reference page if supplied */ 2529 if (ref_page) { 2530 spin_unlock(ptl); 2531 break; 2532 } 2533 unlock: 2534 spin_unlock(ptl); 2535 } 2536 /* 2537 * mmu_gather ran out of room to batch pages, we break out of 2538 * the PTE lock to avoid doing the potential expensive TLB invalidate 2539 * and page-free while holding it. 2540 */ 2541 if (force_flush) { 2542 force_flush = 0; 2543 tlb_flush_mmu(tlb); 2544 if (address < end && !ref_page) 2545 goto again; 2546 } 2547 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2548 tlb_end_vma(tlb, vma); 2549 } 2550 2551 void __unmap_hugepage_range_final(struct mmu_gather *tlb, 2552 struct vm_area_struct *vma, unsigned long start, 2553 unsigned long end, struct page *ref_page) 2554 { 2555 __unmap_hugepage_range(tlb, vma, start, end, ref_page); 2556 2557 /* 2558 * Clear this flag so that x86's huge_pmd_share page_table_shareable 2559 * test will fail on a vma being torn down, and not grab a page table 2560 * on its way out. We're lucky that the flag has such an appropriate 2561 * name, and can in fact be safely cleared here. We could clear it 2562 * before the __unmap_hugepage_range above, but all that's necessary 2563 * is to clear it before releasing the i_mmap_mutex. This works 2564 * because in the context this is called, the VMA is about to be 2565 * destroyed and the i_mmap_mutex is held. 2566 */ 2567 vma->vm_flags &= ~VM_MAYSHARE; 2568 } 2569 2570 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, 2571 unsigned long end, struct page *ref_page) 2572 { 2573 struct mm_struct *mm; 2574 struct mmu_gather tlb; 2575 2576 mm = vma->vm_mm; 2577 2578 tlb_gather_mmu(&tlb, mm, start, end); 2579 __unmap_hugepage_range(&tlb, vma, start, end, ref_page); 2580 tlb_finish_mmu(&tlb, start, end); 2581 } 2582 2583 /* 2584 * This is called when the original mapper is failing to COW a MAP_PRIVATE 2585 * mappping it owns the reserve page for. The intention is to unmap the page 2586 * from other VMAs and let the children be SIGKILLed if they are faulting the 2587 * same region. 2588 */ 2589 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, 2590 struct page *page, unsigned long address) 2591 { 2592 struct hstate *h = hstate_vma(vma); 2593 struct vm_area_struct *iter_vma; 2594 struct address_space *mapping; 2595 pgoff_t pgoff; 2596 2597 /* 2598 * vm_pgoff is in PAGE_SIZE units, hence the different calculation 2599 * from page cache lookup which is in HPAGE_SIZE units. 2600 */ 2601 address = address & huge_page_mask(h); 2602 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + 2603 vma->vm_pgoff; 2604 mapping = file_inode(vma->vm_file)->i_mapping; 2605 2606 /* 2607 * Take the mapping lock for the duration of the table walk. As 2608 * this mapping should be shared between all the VMAs, 2609 * __unmap_hugepage_range() is called as the lock is already held 2610 */ 2611 mutex_lock(&mapping->i_mmap_mutex); 2612 vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) { 2613 /* Do not unmap the current VMA */ 2614 if (iter_vma == vma) 2615 continue; 2616 2617 /* 2618 * Unmap the page from other VMAs without their own reserves. 2619 * They get marked to be SIGKILLed if they fault in these 2620 * areas. This is because a future no-page fault on this VMA 2621 * could insert a zeroed page instead of the data existing 2622 * from the time of fork. This would look like data corruption 2623 */ 2624 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2625 unmap_hugepage_range(iter_vma, address, 2626 address + huge_page_size(h), page); 2627 } 2628 mutex_unlock(&mapping->i_mmap_mutex); 2629 2630 return 1; 2631 } 2632 2633 /* 2634 * Hugetlb_cow() should be called with page lock of the original hugepage held. 2635 * Called with hugetlb_instantiation_mutex held and pte_page locked so we 2636 * cannot race with other handlers or page migration. 2637 * Keep the pte_same checks anyway to make transition from the mutex easier. 2638 */ 2639 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, 2640 unsigned long address, pte_t *ptep, pte_t pte, 2641 struct page *pagecache_page, spinlock_t *ptl) 2642 { 2643 struct hstate *h = hstate_vma(vma); 2644 struct page *old_page, *new_page; 2645 int outside_reserve = 0; 2646 unsigned long mmun_start; /* For mmu_notifiers */ 2647 unsigned long mmun_end; /* For mmu_notifiers */ 2648 2649 old_page = pte_page(pte); 2650 2651 retry_avoidcopy: 2652 /* If no-one else is actually using this page, avoid the copy 2653 * and just make the page writable */ 2654 if (page_mapcount(old_page) == 1 && PageAnon(old_page)) { 2655 page_move_anon_rmap(old_page, vma, address); 2656 set_huge_ptep_writable(vma, address, ptep); 2657 return 0; 2658 } 2659 2660 /* 2661 * If the process that created a MAP_PRIVATE mapping is about to 2662 * perform a COW due to a shared page count, attempt to satisfy 2663 * the allocation without using the existing reserves. The pagecache 2664 * page is used to determine if the reserve at this address was 2665 * consumed or not. If reserves were used, a partial faulted mapping 2666 * at the time of fork() could consume its reserves on COW instead 2667 * of the full address range. 2668 */ 2669 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && 2670 old_page != pagecache_page) 2671 outside_reserve = 1; 2672 2673 page_cache_get(old_page); 2674 2675 /* Drop page table lock as buddy allocator may be called */ 2676 spin_unlock(ptl); 2677 new_page = alloc_huge_page(vma, address, outside_reserve); 2678 2679 if (IS_ERR(new_page)) { 2680 long err = PTR_ERR(new_page); 2681 page_cache_release(old_page); 2682 2683 /* 2684 * If a process owning a MAP_PRIVATE mapping fails to COW, 2685 * it is due to references held by a child and an insufficient 2686 * huge page pool. To guarantee the original mappers 2687 * reliability, unmap the page from child processes. The child 2688 * may get SIGKILLed if it later faults. 2689 */ 2690 if (outside_reserve) { 2691 BUG_ON(huge_pte_none(pte)); 2692 if (unmap_ref_private(mm, vma, old_page, address)) { 2693 BUG_ON(huge_pte_none(pte)); 2694 spin_lock(ptl); 2695 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2696 if (likely(ptep && 2697 pte_same(huge_ptep_get(ptep), pte))) 2698 goto retry_avoidcopy; 2699 /* 2700 * race occurs while re-acquiring page table 2701 * lock, and our job is done. 2702 */ 2703 return 0; 2704 } 2705 WARN_ON_ONCE(1); 2706 } 2707 2708 /* Caller expects lock to be held */ 2709 spin_lock(ptl); 2710 if (err == -ENOMEM) 2711 return VM_FAULT_OOM; 2712 else 2713 return VM_FAULT_SIGBUS; 2714 } 2715 2716 /* 2717 * When the original hugepage is shared one, it does not have 2718 * anon_vma prepared. 2719 */ 2720 if (unlikely(anon_vma_prepare(vma))) { 2721 page_cache_release(new_page); 2722 page_cache_release(old_page); 2723 /* Caller expects lock to be held */ 2724 spin_lock(ptl); 2725 return VM_FAULT_OOM; 2726 } 2727 2728 copy_user_huge_page(new_page, old_page, address, vma, 2729 pages_per_huge_page(h)); 2730 __SetPageUptodate(new_page); 2731 2732 mmun_start = address & huge_page_mask(h); 2733 mmun_end = mmun_start + huge_page_size(h); 2734 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2735 /* 2736 * Retake the page table lock to check for racing updates 2737 * before the page tables are altered 2738 */ 2739 spin_lock(ptl); 2740 ptep = huge_pte_offset(mm, address & huge_page_mask(h)); 2741 if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) { 2742 ClearPagePrivate(new_page); 2743 2744 /* Break COW */ 2745 huge_ptep_clear_flush(vma, address, ptep); 2746 set_huge_pte_at(mm, address, ptep, 2747 make_huge_pte(vma, new_page, 1)); 2748 page_remove_rmap(old_page); 2749 hugepage_add_new_anon_rmap(new_page, vma, address); 2750 /* Make the old page be freed below */ 2751 new_page = old_page; 2752 } 2753 spin_unlock(ptl); 2754 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2755 page_cache_release(new_page); 2756 page_cache_release(old_page); 2757 2758 /* Caller expects lock to be held */ 2759 spin_lock(ptl); 2760 return 0; 2761 } 2762 2763 /* Return the pagecache page at a given address within a VMA */ 2764 static struct page *hugetlbfs_pagecache_page(struct hstate *h, 2765 struct vm_area_struct *vma, unsigned long address) 2766 { 2767 struct address_space *mapping; 2768 pgoff_t idx; 2769 2770 mapping = vma->vm_file->f_mapping; 2771 idx = vma_hugecache_offset(h, vma, address); 2772 2773 return find_lock_page(mapping, idx); 2774 } 2775 2776 /* 2777 * Return whether there is a pagecache page to back given address within VMA. 2778 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. 2779 */ 2780 static bool hugetlbfs_pagecache_present(struct hstate *h, 2781 struct vm_area_struct *vma, unsigned long address) 2782 { 2783 struct address_space *mapping; 2784 pgoff_t idx; 2785 struct page *page; 2786 2787 mapping = vma->vm_file->f_mapping; 2788 idx = vma_hugecache_offset(h, vma, address); 2789 2790 page = find_get_page(mapping, idx); 2791 if (page) 2792 put_page(page); 2793 return page != NULL; 2794 } 2795 2796 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2797 struct address_space *mapping, pgoff_t idx, 2798 unsigned long address, pte_t *ptep, unsigned int flags) 2799 { 2800 struct hstate *h = hstate_vma(vma); 2801 int ret = VM_FAULT_SIGBUS; 2802 int anon_rmap = 0; 2803 unsigned long size; 2804 struct page *page; 2805 pte_t new_pte; 2806 spinlock_t *ptl; 2807 2808 /* 2809 * Currently, we are forced to kill the process in the event the 2810 * original mapper has unmapped pages from the child due to a failed 2811 * COW. Warn that such a situation has occurred as it may not be obvious 2812 */ 2813 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { 2814 pr_warning("PID %d killed due to inadequate hugepage pool\n", 2815 current->pid); 2816 return ret; 2817 } 2818 2819 /* 2820 * Use page lock to guard against racing truncation 2821 * before we get page_table_lock. 2822 */ 2823 retry: 2824 page = find_lock_page(mapping, idx); 2825 if (!page) { 2826 size = i_size_read(mapping->host) >> huge_page_shift(h); 2827 if (idx >= size) 2828 goto out; 2829 page = alloc_huge_page(vma, address, 0); 2830 if (IS_ERR(page)) { 2831 ret = PTR_ERR(page); 2832 if (ret == -ENOMEM) 2833 ret = VM_FAULT_OOM; 2834 else 2835 ret = VM_FAULT_SIGBUS; 2836 goto out; 2837 } 2838 clear_huge_page(page, address, pages_per_huge_page(h)); 2839 __SetPageUptodate(page); 2840 2841 if (vma->vm_flags & VM_MAYSHARE) { 2842 int err; 2843 struct inode *inode = mapping->host; 2844 2845 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); 2846 if (err) { 2847 put_page(page); 2848 if (err == -EEXIST) 2849 goto retry; 2850 goto out; 2851 } 2852 ClearPagePrivate(page); 2853 2854 spin_lock(&inode->i_lock); 2855 inode->i_blocks += blocks_per_huge_page(h); 2856 spin_unlock(&inode->i_lock); 2857 } else { 2858 lock_page(page); 2859 if (unlikely(anon_vma_prepare(vma))) { 2860 ret = VM_FAULT_OOM; 2861 goto backout_unlocked; 2862 } 2863 anon_rmap = 1; 2864 } 2865 } else { 2866 /* 2867 * If memory error occurs between mmap() and fault, some process 2868 * don't have hwpoisoned swap entry for errored virtual address. 2869 * So we need to block hugepage fault by PG_hwpoison bit check. 2870 */ 2871 if (unlikely(PageHWPoison(page))) { 2872 ret = VM_FAULT_HWPOISON | 2873 VM_FAULT_SET_HINDEX(hstate_index(h)); 2874 goto backout_unlocked; 2875 } 2876 } 2877 2878 /* 2879 * If we are going to COW a private mapping later, we examine the 2880 * pending reservations for this page now. This will ensure that 2881 * any allocations necessary to record that reservation occur outside 2882 * the spinlock. 2883 */ 2884 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) 2885 if (vma_needs_reservation(h, vma, address) < 0) { 2886 ret = VM_FAULT_OOM; 2887 goto backout_unlocked; 2888 } 2889 2890 ptl = huge_pte_lockptr(h, mm, ptep); 2891 spin_lock(ptl); 2892 size = i_size_read(mapping->host) >> huge_page_shift(h); 2893 if (idx >= size) 2894 goto backout; 2895 2896 ret = 0; 2897 if (!huge_pte_none(huge_ptep_get(ptep))) 2898 goto backout; 2899 2900 if (anon_rmap) { 2901 ClearPagePrivate(page); 2902 hugepage_add_new_anon_rmap(page, vma, address); 2903 } else 2904 page_dup_rmap(page); 2905 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) 2906 && (vma->vm_flags & VM_SHARED))); 2907 set_huge_pte_at(mm, address, ptep, new_pte); 2908 2909 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 2910 /* Optimization, do the COW without a second fault */ 2911 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl); 2912 } 2913 2914 spin_unlock(ptl); 2915 unlock_page(page); 2916 out: 2917 return ret; 2918 2919 backout: 2920 spin_unlock(ptl); 2921 backout_unlocked: 2922 unlock_page(page); 2923 put_page(page); 2924 goto out; 2925 } 2926 2927 #ifdef CONFIG_SMP 2928 static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm, 2929 struct vm_area_struct *vma, 2930 struct address_space *mapping, 2931 pgoff_t idx, unsigned long address) 2932 { 2933 unsigned long key[2]; 2934 u32 hash; 2935 2936 if (vma->vm_flags & VM_SHARED) { 2937 key[0] = (unsigned long) mapping; 2938 key[1] = idx; 2939 } else { 2940 key[0] = (unsigned long) mm; 2941 key[1] = address >> huge_page_shift(h); 2942 } 2943 2944 hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0); 2945 2946 return hash & (num_fault_mutexes - 1); 2947 } 2948 #else 2949 /* 2950 * For uniprocesor systems we always use a single mutex, so just 2951 * return 0 and avoid the hashing overhead. 2952 */ 2953 static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm, 2954 struct vm_area_struct *vma, 2955 struct address_space *mapping, 2956 pgoff_t idx, unsigned long address) 2957 { 2958 return 0; 2959 } 2960 #endif 2961 2962 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2963 unsigned long address, unsigned int flags) 2964 { 2965 pte_t *ptep, entry; 2966 spinlock_t *ptl; 2967 int ret; 2968 u32 hash; 2969 pgoff_t idx; 2970 struct page *page = NULL; 2971 struct page *pagecache_page = NULL; 2972 struct hstate *h = hstate_vma(vma); 2973 struct address_space *mapping; 2974 2975 address &= huge_page_mask(h); 2976 2977 ptep = huge_pte_offset(mm, address); 2978 if (ptep) { 2979 entry = huge_ptep_get(ptep); 2980 if (unlikely(is_hugetlb_entry_migration(entry))) { 2981 migration_entry_wait_huge(vma, mm, ptep); 2982 return 0; 2983 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) 2984 return VM_FAULT_HWPOISON_LARGE | 2985 VM_FAULT_SET_HINDEX(hstate_index(h)); 2986 } 2987 2988 ptep = huge_pte_alloc(mm, address, huge_page_size(h)); 2989 if (!ptep) 2990 return VM_FAULT_OOM; 2991 2992 mapping = vma->vm_file->f_mapping; 2993 idx = vma_hugecache_offset(h, vma, address); 2994 2995 /* 2996 * Serialize hugepage allocation and instantiation, so that we don't 2997 * get spurious allocation failures if two CPUs race to instantiate 2998 * the same page in the page cache. 2999 */ 3000 hash = fault_mutex_hash(h, mm, vma, mapping, idx, address); 3001 mutex_lock(&htlb_fault_mutex_table[hash]); 3002 3003 entry = huge_ptep_get(ptep); 3004 if (huge_pte_none(entry)) { 3005 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags); 3006 goto out_mutex; 3007 } 3008 3009 ret = 0; 3010 3011 /* 3012 * If we are going to COW the mapping later, we examine the pending 3013 * reservations for this page now. This will ensure that any 3014 * allocations necessary to record that reservation occur outside the 3015 * spinlock. For private mappings, we also lookup the pagecache 3016 * page now as it is used to determine if a reservation has been 3017 * consumed. 3018 */ 3019 if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { 3020 if (vma_needs_reservation(h, vma, address) < 0) { 3021 ret = VM_FAULT_OOM; 3022 goto out_mutex; 3023 } 3024 3025 if (!(vma->vm_flags & VM_MAYSHARE)) 3026 pagecache_page = hugetlbfs_pagecache_page(h, 3027 vma, address); 3028 } 3029 3030 /* 3031 * hugetlb_cow() requires page locks of pte_page(entry) and 3032 * pagecache_page, so here we need take the former one 3033 * when page != pagecache_page or !pagecache_page. 3034 * Note that locking order is always pagecache_page -> page, 3035 * so no worry about deadlock. 3036 */ 3037 page = pte_page(entry); 3038 get_page(page); 3039 if (page != pagecache_page) 3040 lock_page(page); 3041 3042 ptl = huge_pte_lockptr(h, mm, ptep); 3043 spin_lock(ptl); 3044 /* Check for a racing update before calling hugetlb_cow */ 3045 if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) 3046 goto out_ptl; 3047 3048 3049 if (flags & FAULT_FLAG_WRITE) { 3050 if (!huge_pte_write(entry)) { 3051 ret = hugetlb_cow(mm, vma, address, ptep, entry, 3052 pagecache_page, ptl); 3053 goto out_ptl; 3054 } 3055 entry = huge_pte_mkdirty(entry); 3056 } 3057 entry = pte_mkyoung(entry); 3058 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 3059 flags & FAULT_FLAG_WRITE)) 3060 update_mmu_cache(vma, address, ptep); 3061 3062 out_ptl: 3063 spin_unlock(ptl); 3064 3065 if (pagecache_page) { 3066 unlock_page(pagecache_page); 3067 put_page(pagecache_page); 3068 } 3069 if (page != pagecache_page) 3070 unlock_page(page); 3071 put_page(page); 3072 3073 out_mutex: 3074 mutex_unlock(&htlb_fault_mutex_table[hash]); 3075 return ret; 3076 } 3077 3078 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 3079 struct page **pages, struct vm_area_struct **vmas, 3080 unsigned long *position, unsigned long *nr_pages, 3081 long i, unsigned int flags) 3082 { 3083 unsigned long pfn_offset; 3084 unsigned long vaddr = *position; 3085 unsigned long remainder = *nr_pages; 3086 struct hstate *h = hstate_vma(vma); 3087 3088 while (vaddr < vma->vm_end && remainder) { 3089 pte_t *pte; 3090 spinlock_t *ptl = NULL; 3091 int absent; 3092 struct page *page; 3093 3094 /* 3095 * Some archs (sparc64, sh*) have multiple pte_ts to 3096 * each hugepage. We have to make sure we get the 3097 * first, for the page indexing below to work. 3098 * 3099 * Note that page table lock is not held when pte is null. 3100 */ 3101 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); 3102 if (pte) 3103 ptl = huge_pte_lock(h, mm, pte); 3104 absent = !pte || huge_pte_none(huge_ptep_get(pte)); 3105 3106 /* 3107 * When coredumping, it suits get_dump_page if we just return 3108 * an error where there's an empty slot with no huge pagecache 3109 * to back it. This way, we avoid allocating a hugepage, and 3110 * the sparse dumpfile avoids allocating disk blocks, but its 3111 * huge holes still show up with zeroes where they need to be. 3112 */ 3113 if (absent && (flags & FOLL_DUMP) && 3114 !hugetlbfs_pagecache_present(h, vma, vaddr)) { 3115 if (pte) 3116 spin_unlock(ptl); 3117 remainder = 0; 3118 break; 3119 } 3120 3121 /* 3122 * We need call hugetlb_fault for both hugepages under migration 3123 * (in which case hugetlb_fault waits for the migration,) and 3124 * hwpoisoned hugepages (in which case we need to prevent the 3125 * caller from accessing to them.) In order to do this, we use 3126 * here is_swap_pte instead of is_hugetlb_entry_migration and 3127 * is_hugetlb_entry_hwpoisoned. This is because it simply covers 3128 * both cases, and because we can't follow correct pages 3129 * directly from any kind of swap entries. 3130 */ 3131 if (absent || is_swap_pte(huge_ptep_get(pte)) || 3132 ((flags & FOLL_WRITE) && 3133 !huge_pte_write(huge_ptep_get(pte)))) { 3134 int ret; 3135 3136 if (pte) 3137 spin_unlock(ptl); 3138 ret = hugetlb_fault(mm, vma, vaddr, 3139 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); 3140 if (!(ret & VM_FAULT_ERROR)) 3141 continue; 3142 3143 remainder = 0; 3144 break; 3145 } 3146 3147 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; 3148 page = pte_page(huge_ptep_get(pte)); 3149 same_page: 3150 if (pages) { 3151 pages[i] = mem_map_offset(page, pfn_offset); 3152 get_page_foll(pages[i]); 3153 } 3154 3155 if (vmas) 3156 vmas[i] = vma; 3157 3158 vaddr += PAGE_SIZE; 3159 ++pfn_offset; 3160 --remainder; 3161 ++i; 3162 if (vaddr < vma->vm_end && remainder && 3163 pfn_offset < pages_per_huge_page(h)) { 3164 /* 3165 * We use pfn_offset to avoid touching the pageframes 3166 * of this compound page. 3167 */ 3168 goto same_page; 3169 } 3170 spin_unlock(ptl); 3171 } 3172 *nr_pages = remainder; 3173 *position = vaddr; 3174 3175 return i ? i : -EFAULT; 3176 } 3177 3178 unsigned long hugetlb_change_protection(struct vm_area_struct *vma, 3179 unsigned long address, unsigned long end, pgprot_t newprot) 3180 { 3181 struct mm_struct *mm = vma->vm_mm; 3182 unsigned long start = address; 3183 pte_t *ptep; 3184 pte_t pte; 3185 struct hstate *h = hstate_vma(vma); 3186 unsigned long pages = 0; 3187 3188 BUG_ON(address >= end); 3189 flush_cache_range(vma, address, end); 3190 3191 mmu_notifier_invalidate_range_start(mm, start, end); 3192 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 3193 for (; address < end; address += huge_page_size(h)) { 3194 spinlock_t *ptl; 3195 ptep = huge_pte_offset(mm, address); 3196 if (!ptep) 3197 continue; 3198 ptl = huge_pte_lock(h, mm, ptep); 3199 if (huge_pmd_unshare(mm, &address, ptep)) { 3200 pages++; 3201 spin_unlock(ptl); 3202 continue; 3203 } 3204 if (!huge_pte_none(huge_ptep_get(ptep))) { 3205 pte = huge_ptep_get_and_clear(mm, address, ptep); 3206 pte = pte_mkhuge(huge_pte_modify(pte, newprot)); 3207 pte = arch_make_huge_pte(pte, vma, NULL, 0); 3208 set_huge_pte_at(mm, address, ptep, pte); 3209 pages++; 3210 } 3211 spin_unlock(ptl); 3212 } 3213 /* 3214 * Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare 3215 * may have cleared our pud entry and done put_page on the page table: 3216 * once we release i_mmap_mutex, another task can do the final put_page 3217 * and that page table be reused and filled with junk. 3218 */ 3219 flush_tlb_range(vma, start, end); 3220 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 3221 mmu_notifier_invalidate_range_end(mm, start, end); 3222 3223 return pages << h->order; 3224 } 3225 3226 int hugetlb_reserve_pages(struct inode *inode, 3227 long from, long to, 3228 struct vm_area_struct *vma, 3229 vm_flags_t vm_flags) 3230 { 3231 long ret, chg; 3232 struct hstate *h = hstate_inode(inode); 3233 struct hugepage_subpool *spool = subpool_inode(inode); 3234 struct resv_map *resv_map; 3235 3236 /* 3237 * Only apply hugepage reservation if asked. At fault time, an 3238 * attempt will be made for VM_NORESERVE to allocate a page 3239 * without using reserves 3240 */ 3241 if (vm_flags & VM_NORESERVE) 3242 return 0; 3243 3244 /* 3245 * Shared mappings base their reservation on the number of pages that 3246 * are already allocated on behalf of the file. Private mappings need 3247 * to reserve the full area even if read-only as mprotect() may be 3248 * called to make the mapping read-write. Assume !vma is a shm mapping 3249 */ 3250 if (!vma || vma->vm_flags & VM_MAYSHARE) { 3251 resv_map = inode_resv_map(inode); 3252 3253 chg = region_chg(resv_map, from, to); 3254 3255 } else { 3256 resv_map = resv_map_alloc(); 3257 if (!resv_map) 3258 return -ENOMEM; 3259 3260 chg = to - from; 3261 3262 set_vma_resv_map(vma, resv_map); 3263 set_vma_resv_flags(vma, HPAGE_RESV_OWNER); 3264 } 3265 3266 if (chg < 0) { 3267 ret = chg; 3268 goto out_err; 3269 } 3270 3271 /* There must be enough pages in the subpool for the mapping */ 3272 if (hugepage_subpool_get_pages(spool, chg)) { 3273 ret = -ENOSPC; 3274 goto out_err; 3275 } 3276 3277 /* 3278 * Check enough hugepages are available for the reservation. 3279 * Hand the pages back to the subpool if there are not 3280 */ 3281 ret = hugetlb_acct_memory(h, chg); 3282 if (ret < 0) { 3283 hugepage_subpool_put_pages(spool, chg); 3284 goto out_err; 3285 } 3286 3287 /* 3288 * Account for the reservations made. Shared mappings record regions 3289 * that have reservations as they are shared by multiple VMAs. 3290 * When the last VMA disappears, the region map says how much 3291 * the reservation was and the page cache tells how much of 3292 * the reservation was consumed. Private mappings are per-VMA and 3293 * only the consumed reservations are tracked. When the VMA 3294 * disappears, the original reservation is the VMA size and the 3295 * consumed reservations are stored in the map. Hence, nothing 3296 * else has to be done for private mappings here 3297 */ 3298 if (!vma || vma->vm_flags & VM_MAYSHARE) 3299 region_add(resv_map, from, to); 3300 return 0; 3301 out_err: 3302 if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) 3303 kref_put(&resv_map->refs, resv_map_release); 3304 return ret; 3305 } 3306 3307 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) 3308 { 3309 struct hstate *h = hstate_inode(inode); 3310 struct resv_map *resv_map = inode_resv_map(inode); 3311 long chg = 0; 3312 struct hugepage_subpool *spool = subpool_inode(inode); 3313 3314 if (resv_map) 3315 chg = region_truncate(resv_map, offset); 3316 spin_lock(&inode->i_lock); 3317 inode->i_blocks -= (blocks_per_huge_page(h) * freed); 3318 spin_unlock(&inode->i_lock); 3319 3320 hugepage_subpool_put_pages(spool, (chg - freed)); 3321 hugetlb_acct_memory(h, -(chg - freed)); 3322 } 3323 3324 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE 3325 static unsigned long page_table_shareable(struct vm_area_struct *svma, 3326 struct vm_area_struct *vma, 3327 unsigned long addr, pgoff_t idx) 3328 { 3329 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + 3330 svma->vm_start; 3331 unsigned long sbase = saddr & PUD_MASK; 3332 unsigned long s_end = sbase + PUD_SIZE; 3333 3334 /* Allow segments to share if only one is marked locked */ 3335 unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED; 3336 unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED; 3337 3338 /* 3339 * match the virtual addresses, permission and the alignment of the 3340 * page table page. 3341 */ 3342 if (pmd_index(addr) != pmd_index(saddr) || 3343 vm_flags != svm_flags || 3344 sbase < svma->vm_start || svma->vm_end < s_end) 3345 return 0; 3346 3347 return saddr; 3348 } 3349 3350 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr) 3351 { 3352 unsigned long base = addr & PUD_MASK; 3353 unsigned long end = base + PUD_SIZE; 3354 3355 /* 3356 * check on proper vm_flags and page table alignment 3357 */ 3358 if (vma->vm_flags & VM_MAYSHARE && 3359 vma->vm_start <= base && end <= vma->vm_end) 3360 return 1; 3361 return 0; 3362 } 3363 3364 /* 3365 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc() 3366 * and returns the corresponding pte. While this is not necessary for the 3367 * !shared pmd case because we can allocate the pmd later as well, it makes the 3368 * code much cleaner. pmd allocation is essential for the shared case because 3369 * pud has to be populated inside the same i_mmap_mutex section - otherwise 3370 * racing tasks could either miss the sharing (see huge_pte_offset) or select a 3371 * bad pmd for sharing. 3372 */ 3373 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) 3374 { 3375 struct vm_area_struct *vma = find_vma(mm, addr); 3376 struct address_space *mapping = vma->vm_file->f_mapping; 3377 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + 3378 vma->vm_pgoff; 3379 struct vm_area_struct *svma; 3380 unsigned long saddr; 3381 pte_t *spte = NULL; 3382 pte_t *pte; 3383 spinlock_t *ptl; 3384 3385 if (!vma_shareable(vma, addr)) 3386 return (pte_t *)pmd_alloc(mm, pud, addr); 3387 3388 mutex_lock(&mapping->i_mmap_mutex); 3389 vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) { 3390 if (svma == vma) 3391 continue; 3392 3393 saddr = page_table_shareable(svma, vma, addr, idx); 3394 if (saddr) { 3395 spte = huge_pte_offset(svma->vm_mm, saddr); 3396 if (spte) { 3397 get_page(virt_to_page(spte)); 3398 break; 3399 } 3400 } 3401 } 3402 3403 if (!spte) 3404 goto out; 3405 3406 ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte); 3407 spin_lock(ptl); 3408 if (pud_none(*pud)) 3409 pud_populate(mm, pud, 3410 (pmd_t *)((unsigned long)spte & PAGE_MASK)); 3411 else 3412 put_page(virt_to_page(spte)); 3413 spin_unlock(ptl); 3414 out: 3415 pte = (pte_t *)pmd_alloc(mm, pud, addr); 3416 mutex_unlock(&mapping->i_mmap_mutex); 3417 return pte; 3418 } 3419 3420 /* 3421 * unmap huge page backed by shared pte. 3422 * 3423 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared 3424 * indicated by page_count > 1, unmap is achieved by clearing pud and 3425 * decrementing the ref count. If count == 1, the pte page is not shared. 3426 * 3427 * called with page table lock held. 3428 * 3429 * returns: 1 successfully unmapped a shared pte page 3430 * 0 the underlying pte page is not shared, or it is the last user 3431 */ 3432 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) 3433 { 3434 pgd_t *pgd = pgd_offset(mm, *addr); 3435 pud_t *pud = pud_offset(pgd, *addr); 3436 3437 BUG_ON(page_count(virt_to_page(ptep)) == 0); 3438 if (page_count(virt_to_page(ptep)) == 1) 3439 return 0; 3440 3441 pud_clear(pud); 3442 put_page(virt_to_page(ptep)); 3443 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE; 3444 return 1; 3445 } 3446 #define want_pmd_share() (1) 3447 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ 3448 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) 3449 { 3450 return NULL; 3451 } 3452 #define want_pmd_share() (0) 3453 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ 3454 3455 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB 3456 pte_t *huge_pte_alloc(struct mm_struct *mm, 3457 unsigned long addr, unsigned long sz) 3458 { 3459 pgd_t *pgd; 3460 pud_t *pud; 3461 pte_t *pte = NULL; 3462 3463 pgd = pgd_offset(mm, addr); 3464 pud = pud_alloc(mm, pgd, addr); 3465 if (pud) { 3466 if (sz == PUD_SIZE) { 3467 pte = (pte_t *)pud; 3468 } else { 3469 BUG_ON(sz != PMD_SIZE); 3470 if (want_pmd_share() && pud_none(*pud)) 3471 pte = huge_pmd_share(mm, addr, pud); 3472 else 3473 pte = (pte_t *)pmd_alloc(mm, pud, addr); 3474 } 3475 } 3476 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); 3477 3478 return pte; 3479 } 3480 3481 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) 3482 { 3483 pgd_t *pgd; 3484 pud_t *pud; 3485 pmd_t *pmd = NULL; 3486 3487 pgd = pgd_offset(mm, addr); 3488 if (pgd_present(*pgd)) { 3489 pud = pud_offset(pgd, addr); 3490 if (pud_present(*pud)) { 3491 if (pud_huge(*pud)) 3492 return (pte_t *)pud; 3493 pmd = pmd_offset(pud, addr); 3494 } 3495 } 3496 return (pte_t *) pmd; 3497 } 3498 3499 struct page * 3500 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 3501 pmd_t *pmd, int write) 3502 { 3503 struct page *page; 3504 3505 page = pte_page(*(pte_t *)pmd); 3506 if (page) 3507 page += ((address & ~PMD_MASK) >> PAGE_SHIFT); 3508 return page; 3509 } 3510 3511 struct page * 3512 follow_huge_pud(struct mm_struct *mm, unsigned long address, 3513 pud_t *pud, int write) 3514 { 3515 struct page *page; 3516 3517 page = pte_page(*(pte_t *)pud); 3518 if (page) 3519 page += ((address & ~PUD_MASK) >> PAGE_SHIFT); 3520 return page; 3521 } 3522 3523 #else /* !CONFIG_ARCH_WANT_GENERAL_HUGETLB */ 3524 3525 /* Can be overriden by architectures */ 3526 struct page * __weak 3527 follow_huge_pud(struct mm_struct *mm, unsigned long address, 3528 pud_t *pud, int write) 3529 { 3530 BUG(); 3531 return NULL; 3532 } 3533 3534 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */ 3535 3536 #ifdef CONFIG_MEMORY_FAILURE 3537 3538 /* Should be called in hugetlb_lock */ 3539 static int is_hugepage_on_freelist(struct page *hpage) 3540 { 3541 struct page *page; 3542 struct page *tmp; 3543 struct hstate *h = page_hstate(hpage); 3544 int nid = page_to_nid(hpage); 3545 3546 list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) 3547 if (page == hpage) 3548 return 1; 3549 return 0; 3550 } 3551 3552 /* 3553 * This function is called from memory failure code. 3554 * Assume the caller holds page lock of the head page. 3555 */ 3556 int dequeue_hwpoisoned_huge_page(struct page *hpage) 3557 { 3558 struct hstate *h = page_hstate(hpage); 3559 int nid = page_to_nid(hpage); 3560 int ret = -EBUSY; 3561 3562 spin_lock(&hugetlb_lock); 3563 if (is_hugepage_on_freelist(hpage)) { 3564 /* 3565 * Hwpoisoned hugepage isn't linked to activelist or freelist, 3566 * but dangling hpage->lru can trigger list-debug warnings 3567 * (this happens when we call unpoison_memory() on it), 3568 * so let it point to itself with list_del_init(). 3569 */ 3570 list_del_init(&hpage->lru); 3571 set_page_refcounted(hpage); 3572 h->free_huge_pages--; 3573 h->free_huge_pages_node[nid]--; 3574 ret = 0; 3575 } 3576 spin_unlock(&hugetlb_lock); 3577 return ret; 3578 } 3579 #endif 3580 3581 bool isolate_huge_page(struct page *page, struct list_head *list) 3582 { 3583 VM_BUG_ON_PAGE(!PageHead(page), page); 3584 if (!get_page_unless_zero(page)) 3585 return false; 3586 spin_lock(&hugetlb_lock); 3587 list_move_tail(&page->lru, list); 3588 spin_unlock(&hugetlb_lock); 3589 return true; 3590 } 3591 3592 void putback_active_hugepage(struct page *page) 3593 { 3594 VM_BUG_ON_PAGE(!PageHead(page), page); 3595 spin_lock(&hugetlb_lock); 3596 list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist); 3597 spin_unlock(&hugetlb_lock); 3598 put_page(page); 3599 } 3600 3601 bool is_hugepage_active(struct page *page) 3602 { 3603 VM_BUG_ON_PAGE(!PageHuge(page), page); 3604 /* 3605 * This function can be called for a tail page because the caller, 3606 * scan_movable_pages, scans through a given pfn-range which typically 3607 * covers one memory block. In systems using gigantic hugepage (1GB 3608 * for x86_64,) a hugepage is larger than a memory block, and we don't 3609 * support migrating such large hugepages for now, so return false 3610 * when called for tail pages. 3611 */ 3612 if (PageTail(page)) 3613 return false; 3614 /* 3615 * Refcount of a hwpoisoned hugepages is 1, but they are not active, 3616 * so we should return false for them. 3617 */ 3618 if (unlikely(PageHWPoison(page))) 3619 return false; 3620 return page_count(page) > 0; 3621 } 3622