mm/hugetlb.c

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