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