linux/mm/hugetlb.c
<<
>>
Prefs
   1/*
   2 * Generic hugetlb support.
   3 * (C) Nadia Yvette Chambers, April 2004
   4 */
   5#include <linux/list.h>
   6#include <linux/init.h>
   7#include <linux/module.h>
   8#include <linux/mm.h>
   9#include <linux/seq_file.h>
  10#include <linux/sysctl.h>
  11#include <linux/highmem.h>
  12#include <linux/mmu_notifier.h>
  13#include <linux/nodemask.h>
  14#include <linux/pagemap.h>
  15#include <linux/mempolicy.h>
  16#include <linux/cpuset.h>
  17#include <linux/mutex.h>
  18#include <linux/bootmem.h>
  19#include <linux/sysfs.h>
  20#include <linux/slab.h>
  21#include <linux/rmap.h>
  22#include <linux/swap.h>
  23#include <linux/swapops.h>
  24
  25#include <asm/page.h>
  26#include <asm/pgtable.h>
  27#include <asm/tlb.h>
  28
  29#include <linux/io.h>
  30#include <linux/hugetlb.h>
  31#include <linux/hugetlb_cgroup.h>
  32#include <linux/node.h>
  33#include "internal.h"
  34
  35const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
  36static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
  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, nr_huge_pages, and free_huge_pages
  52 */
  53DEFINE_SPINLOCK(hugetlb_lock);
  54
  55static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
  56{
  57        bool free = (spool->count == 0) && (spool->used_hpages == 0);
  58
  59        spin_unlock(&spool->lock);
  60
  61        /* If no pages are used, and no other handles to the subpool
  62         * remain, free the subpool the subpool remain */
  63        if (free)
  64                kfree(spool);
  65}
  66
  67struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
  68{
  69        struct hugepage_subpool *spool;
  70
  71        spool = kmalloc(sizeof(*spool), GFP_KERNEL);
  72        if (!spool)
  73                return NULL;
  74
  75        spin_lock_init(&spool->lock);
  76        spool->count = 1;
  77        spool->max_hpages = nr_blocks;
  78        spool->used_hpages = 0;
  79
  80        return spool;
  81}
  82
  83void hugepage_put_subpool(struct hugepage_subpool *spool)
  84{
  85        spin_lock(&spool->lock);
  86        BUG_ON(!spool->count);
  87        spool->count--;
  88        unlock_or_release_subpool(spool);
  89}
  90
  91static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
  92                                      long delta)
  93{
  94        int ret = 0;
  95
  96        if (!spool)
  97                return 0;
  98
  99        spin_lock(&spool->lock);
 100        if ((spool->used_hpages + delta) <= spool->max_hpages) {
 101                spool->used_hpages += delta;
 102        } else {
 103                ret = -ENOMEM;
 104        }
 105        spin_unlock(&spool->lock);
 106
 107        return ret;
 108}
 109
 110static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
 111                                       long delta)
 112{
 113        if (!spool)
 114                return;
 115
 116        spin_lock(&spool->lock);
 117        spool->used_hpages -= delta;
 118        /* If hugetlbfs_put_super couldn't free spool due to
 119        * an outstanding quota reference, free it now. */
 120        unlock_or_release_subpool(spool);
 121}
 122
 123static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
 124{
 125        return HUGETLBFS_SB(inode->i_sb)->spool;
 126}
 127
 128static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
 129{
 130        return subpool_inode(file_inode(vma->vm_file));
 131}
 132
 133/*
 134 * Region tracking -- allows tracking of reservations and instantiated pages
 135 *                    across the pages in a mapping.
 136 *
 137 * The region data structures are protected by a combination of the mmap_sem
 138 * and the hugetlb_instantion_mutex.  To access or modify a region the caller
 139 * must either hold the mmap_sem for write, or the mmap_sem for read and
 140 * the hugetlb_instantiation mutex:
 141 *
 142 *      down_write(&mm->mmap_sem);
 143 * or
 144 *      down_read(&mm->mmap_sem);
 145 *      mutex_lock(&hugetlb_instantiation_mutex);
 146 */
 147struct file_region {
 148        struct list_head link;
 149        long from;
 150        long to;
 151};
 152
 153static long region_add(struct list_head *head, long f, long t)
 154{
 155        struct file_region *rg, *nrg, *trg;
 156
 157        /* Locate the region we are either in or before. */
 158        list_for_each_entry(rg, head, link)
 159                if (f <= rg->to)
 160                        break;
 161
 162        /* Round our left edge to the current segment if it encloses us. */
 163        if (f > rg->from)
 164                f = rg->from;
 165
 166        /* Check for and consume any regions we now overlap with. */
 167        nrg = rg;
 168        list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
 169                if (&rg->link == head)
 170                        break;
 171                if (rg->from > t)
 172                        break;
 173
 174                /* If this area reaches higher then extend our area to
 175                 * include it completely.  If this is not the first area
 176                 * which we intend to reuse, free it. */
 177                if (rg->to > t)
 178                        t = rg->to;
 179                if (rg != nrg) {
 180                        list_del(&rg->link);
 181                        kfree(rg);
 182                }
 183        }
 184        nrg->from = f;
 185        nrg->to = t;
 186        return 0;
 187}
 188
 189static long region_chg(struct list_head *head, long f, long t)
 190{
 191        struct file_region *rg, *nrg;
 192        long chg = 0;
 193
 194        /* Locate the region we are before or in. */
 195        list_for_each_entry(rg, head, link)
 196                if (f <= rg->to)
 197                        break;
 198
 199        /* If we are below the current region then a new region is required.
 200         * Subtle, allocate a new region at the position but make it zero
 201         * size such that we can guarantee to record the reservation. */
 202        if (&rg->link == head || t < rg->from) {
 203                nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
 204                if (!nrg)
 205                        return -ENOMEM;
 206                nrg->from = f;
 207                nrg->to   = f;
 208                INIT_LIST_HEAD(&nrg->link);
 209                list_add(&nrg->link, rg->link.prev);
 210
 211                return t - f;
 212        }
 213
 214        /* Round our left edge to the current segment if it encloses us. */
 215        if (f > rg->from)
 216                f = rg->from;
 217        chg = t - f;
 218
 219        /* Check for and consume any regions we now overlap with. */
 220        list_for_each_entry(rg, rg->link.prev, link) {
 221                if (&rg->link == head)
 222                        break;
 223                if (rg->from > t)
 224                        return chg;
 225
 226                /* We overlap with this area, if it extends further than
 227                 * us then we must extend ourselves.  Account for its
 228                 * existing reservation. */
 229                if (rg->to > t) {
 230                        chg += rg->to - t;
 231                        t = rg->to;
 232                }
 233                chg -= rg->to - rg->from;
 234        }
 235        return chg;
 236}
 237
 238static long region_truncate(struct list_head *head, long end)
 239{
 240        struct file_region *rg, *trg;
 241        long chg = 0;
 242
 243        /* Locate the region we are either in or before. */
 244        list_for_each_entry(rg, head, link)
 245                if (end <= rg->to)
 246                        break;
 247        if (&rg->link == head)
 248                return 0;
 249
 250        /* If we are in the middle of a region then adjust it. */
 251        if (end > rg->from) {
 252                chg = rg->to - end;
 253                rg->to = end;
 254                rg = list_entry(rg->link.next, typeof(*rg), link);
 255        }
 256
 257        /* Drop any remaining regions. */
 258        list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
 259                if (&rg->link == head)
 260                        break;
 261                chg += rg->to - rg->from;
 262                list_del(&rg->link);
 263                kfree(rg);
 264        }
 265        return chg;
 266}
 267
 268static long region_count(struct list_head *head, long f, long t)
 269{
 270        struct file_region *rg;
 271        long chg = 0;
 272
 273        /* Locate each segment we overlap with, and count that overlap. */
 274        list_for_each_entry(rg, head, link) {
 275                long seg_from;
 276                long seg_to;
 277
 278                if (rg->to <= f)
 279                        continue;
 280                if (rg->from >= t)
 281                        break;
 282
 283                seg_from = max(rg->from, f);
 284                seg_to = min(rg->to, t);
 285
 286                chg += seg_to - seg_from;
 287        }
 288
 289        return chg;
 290}
 291
 292/*
 293 * Convert the address within this vma to the page offset within
 294 * the mapping, in pagecache page units; huge pages here.
 295 */
 296static pgoff_t vma_hugecache_offset(struct hstate *h,
 297                        struct vm_area_struct *vma, unsigned long address)
 298{
 299        return ((address - vma->vm_start) >> huge_page_shift(h)) +
 300                        (vma->vm_pgoff >> huge_page_order(h));
 301}
 302
 303pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
 304                                     unsigned long address)
 305{
 306        return vma_hugecache_offset(hstate_vma(vma), vma, address);
 307}
 308
 309/*
 310 * Return the size of the pages allocated when backing a VMA. In the majority
 311 * cases this will be same size as used by the page table entries.
 312 */
 313unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
 314{
 315        struct hstate *hstate;
 316
 317        if (!is_vm_hugetlb_page(vma))
 318                return PAGE_SIZE;
 319
 320        hstate = hstate_vma(vma);
 321
 322        return 1UL << (hstate->order + PAGE_SHIFT);
 323}
 324EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
 325
 326/*
 327 * Return the page size being used by the MMU to back a VMA. In the majority
 328 * of cases, the page size used by the kernel matches the MMU size. On
 329 * architectures where it differs, an architecture-specific version of this
 330 * function is required.
 331 */
 332#ifndef vma_mmu_pagesize
 333unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
 334{
 335        return vma_kernel_pagesize(vma);
 336}
 337#endif
 338
 339/*
 340 * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
 341 * bits of the reservation map pointer, which are always clear due to
 342 * alignment.
 343 */
 344#define HPAGE_RESV_OWNER    (1UL << 0)
 345#define HPAGE_RESV_UNMAPPED (1UL << 1)
 346#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
 347
 348/*
 349 * These helpers are used to track how many pages are reserved for
 350 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
 351 * is guaranteed to have their future faults succeed.
 352 *
 353 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
 354 * the reserve counters are updated with the hugetlb_lock held. It is safe
 355 * to reset the VMA at fork() time as it is not in use yet and there is no
 356 * chance of the global counters getting corrupted as a result of the values.
 357 *
 358 * The private mapping reservation is represented in a subtly different
 359 * manner to a shared mapping.  A shared mapping has a region map associated
 360 * with the underlying file, this region map represents the backing file
 361 * pages which have ever had a reservation assigned which this persists even
 362 * after the page is instantiated.  A private mapping has a region map
 363 * associated with the original mmap which is attached to all VMAs which
 364 * reference it, this region map represents those offsets which have consumed
 365 * reservation ie. where pages have been instantiated.
 366 */
 367static unsigned long get_vma_private_data(struct vm_area_struct *vma)
 368{
 369        return (unsigned long)vma->vm_private_data;
 370}
 371
 372static void set_vma_private_data(struct vm_area_struct *vma,
 373                                                        unsigned long value)
 374{
 375        vma->vm_private_data = (void *)value;
 376}
 377
 378struct resv_map {
 379        struct kref refs;
 380        struct list_head regions;
 381};
 382
 383static struct resv_map *resv_map_alloc(void)
 384{
 385        struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
 386        if (!resv_map)
 387                return NULL;
 388
 389        kref_init(&resv_map->refs);
 390        INIT_LIST_HEAD(&resv_map->regions);
 391
 392        return resv_map;
 393}
 394
 395static void resv_map_release(struct kref *ref)
 396{
 397        struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
 398
 399        /* Clear out any active regions before we release the map. */
 400        region_truncate(&resv_map->regions, 0);
 401        kfree(resv_map);
 402}
 403
 404static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
 405{
 406        VM_BUG_ON(!is_vm_hugetlb_page(vma));
 407        if (!(vma->vm_flags & VM_MAYSHARE))
 408                return (struct resv_map *)(get_vma_private_data(vma) &
 409                                                        ~HPAGE_RESV_MASK);
 410        return NULL;
 411}
 412
 413static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
 414{
 415        VM_BUG_ON(!is_vm_hugetlb_page(vma));
 416        VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
 417
 418        set_vma_private_data(vma, (get_vma_private_data(vma) &
 419                                HPAGE_RESV_MASK) | (unsigned long)map);
 420}
 421
 422static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
 423{
 424        VM_BUG_ON(!is_vm_hugetlb_page(vma));
 425        VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
 426
 427        set_vma_private_data(vma, get_vma_private_data(vma) | flags);
 428}
 429
 430static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
 431{
 432        VM_BUG_ON(!is_vm_hugetlb_page(vma));
 433
 434        return (get_vma_private_data(vma) & flag) != 0;
 435}
 436
 437/* Decrement the reserved pages in the hugepage pool by one */
 438static void decrement_hugepage_resv_vma(struct hstate *h,
 439                        struct vm_area_struct *vma)
 440{
 441        if (vma->vm_flags & VM_NORESERVE)
 442                return;
 443
 444        if (vma->vm_flags & VM_MAYSHARE) {
 445                /* Shared mappings always use reserves */
 446                h->resv_huge_pages--;
 447        } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
 448                /*
 449                 * Only the process that called mmap() has reserves for
 450                 * private mappings.
 451                 */
 452                h->resv_huge_pages--;
 453        }
 454}
 455
 456/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
 457void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
 458{
 459        VM_BUG_ON(!is_vm_hugetlb_page(vma));
 460        if (!(vma->vm_flags & VM_MAYSHARE))
 461                vma->vm_private_data = (void *)0;
 462}
 463
 464/* Returns true if the VMA has associated reserve pages */
 465static int vma_has_reserves(struct vm_area_struct *vma)
 466{
 467        if (vma->vm_flags & VM_MAYSHARE)
 468                return 1;
 469        if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
 470                return 1;
 471        return 0;
 472}
 473
 474static void copy_gigantic_page(struct page *dst, struct page *src)
 475{
 476        int i;
 477        struct hstate *h = page_hstate(src);
 478        struct page *dst_base = dst;
 479        struct page *src_base = src;
 480
 481        for (i = 0; i < pages_per_huge_page(h); ) {
 482                cond_resched();
 483                copy_highpage(dst, src);
 484
 485                i++;
 486                dst = mem_map_next(dst, dst_base, i);
 487                src = mem_map_next(src, src_base, i);
 488        }
 489}
 490
 491void copy_huge_page(struct page *dst, struct page *src)
 492{
 493        int i;
 494        struct hstate *h = page_hstate(src);
 495
 496        if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
 497                copy_gigantic_page(dst, src);
 498                return;
 499        }
 500
 501        might_sleep();
 502        for (i = 0; i < pages_per_huge_page(h); i++) {
 503                cond_resched();
 504                copy_highpage(dst + i, src + i);
 505        }
 506}
 507
 508static void enqueue_huge_page(struct hstate *h, struct page *page)
 509{
 510        int nid = page_to_nid(page);
 511        list_move(&page->lru, &h->hugepage_freelists[nid]);
 512        h->free_huge_pages++;
 513        h->free_huge_pages_node[nid]++;
 514}
 515
 516static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
 517{
 518        struct page *page;
 519
 520        if (list_empty(&h->hugepage_freelists[nid]))
 521                return NULL;
 522        page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
 523        list_move(&page->lru, &h->hugepage_activelist);
 524        set_page_refcounted(page);
 525        h->free_huge_pages--;
 526        h->free_huge_pages_node[nid]--;
 527        return page;
 528}
 529
 530static struct page *dequeue_huge_page_vma(struct hstate *h,
 531                                struct vm_area_struct *vma,
 532                                unsigned long address, int avoid_reserve)
 533{
 534        struct page *page = NULL;
 535        struct mempolicy *mpol;
 536        nodemask_t *nodemask;
 537        struct zonelist *zonelist;
 538        struct zone *zone;
 539        struct zoneref *z;
 540        unsigned int cpuset_mems_cookie;
 541
 542retry_cpuset:
 543        cpuset_mems_cookie = get_mems_allowed();
 544        zonelist = huge_zonelist(vma, address,
 545                                        htlb_alloc_mask, &mpol, &nodemask);
 546        /*
 547         * A child process with MAP_PRIVATE mappings created by their parent
 548         * have no page reserves. This check ensures that reservations are
 549         * not "stolen". The child may still get SIGKILLed
 550         */
 551        if (!vma_has_reserves(vma) &&
 552                        h->free_huge_pages - h->resv_huge_pages == 0)
 553                goto err;
 554
 555        /* If reserves cannot be used, ensure enough pages are in the pool */
 556        if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
 557                goto err;
 558
 559        for_each_zone_zonelist_nodemask(zone, z, zonelist,
 560                                                MAX_NR_ZONES - 1, nodemask) {
 561                if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
 562                        page = dequeue_huge_page_node(h, zone_to_nid(zone));
 563                        if (page) {
 564                                if (!avoid_reserve)
 565                                        decrement_hugepage_resv_vma(h, vma);
 566                                break;
 567                        }
 568                }
 569        }
 570
 571        mpol_cond_put(mpol);
 572        if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
 573                goto retry_cpuset;
 574        return page;
 575
 576err:
 577        mpol_cond_put(mpol);
 578        return NULL;
 579}
 580
 581static void update_and_free_page(struct hstate *h, struct page *page)
 582{
 583        int i;
 584
 585        VM_BUG_ON(h->order >= MAX_ORDER);
 586
 587        h->nr_huge_pages--;
 588        h->nr_huge_pages_node[page_to_nid(page)]--;
 589        for (i = 0; i < pages_per_huge_page(h); i++) {
 590                page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
 591                                1 << PG_referenced | 1 << PG_dirty |
 592                                1 << PG_active | 1 << PG_reserved |
 593                                1 << PG_private | 1 << PG_writeback);
 594        }
 595        VM_BUG_ON(hugetlb_cgroup_from_page(page));
 596        set_compound_page_dtor(page, NULL);
 597        set_page_refcounted(page);
 598        arch_release_hugepage(page);
 599        __free_pages(page, huge_page_order(h));
 600}
 601
 602struct hstate *size_to_hstate(unsigned long size)
 603{
 604        struct hstate *h;
 605
 606        for_each_hstate(h) {
 607                if (huge_page_size(h) == size)
 608                        return h;
 609        }
 610        return NULL;
 611}
 612
 613static void free_huge_page(struct page *page)
 614{
 615        /*
 616         * Can't pass hstate in here because it is called from the
 617         * compound page destructor.
 618         */
 619        struct hstate *h = page_hstate(page);
 620        int nid = page_to_nid(page);
 621        struct hugepage_subpool *spool =
 622                (struct hugepage_subpool *)page_private(page);
 623
 624        set_page_private(page, 0);
 625        page->mapping = NULL;
 626        BUG_ON(page_count(page));
 627        BUG_ON(page_mapcount(page));
 628
 629        spin_lock(&hugetlb_lock);
 630        hugetlb_cgroup_uncharge_page(hstate_index(h),
 631                                     pages_per_huge_page(h), page);
 632        if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
 633                /* remove the page from active list */
 634                list_del(&page->lru);
 635                update_and_free_page(h, page);
 636                h->surplus_huge_pages--;
 637                h->surplus_huge_pages_node[nid]--;
 638        } else {
 639                arch_clear_hugepage_flags(page);
 640                enqueue_huge_page(h, page);
 641        }
 642        spin_unlock(&hugetlb_lock);
 643        hugepage_subpool_put_pages(spool, 1);
 644}
 645
 646static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
 647{
 648        INIT_LIST_HEAD(&page->lru);
 649        set_compound_page_dtor(page, free_huge_page);
 650        spin_lock(&hugetlb_lock);
 651        set_hugetlb_cgroup(page, NULL);
 652        h->nr_huge_pages++;
 653        h->nr_huge_pages_node[nid]++;
 654        spin_unlock(&hugetlb_lock);
 655        put_page(page); /* free it into the hugepage allocator */
 656}
 657
 658static void prep_compound_gigantic_page(struct page *page, unsigned long order)
 659{
 660        int i;
 661        int nr_pages = 1 << order;
 662        struct page *p = page + 1;
 663
 664        /* we rely on prep_new_huge_page to set the destructor */
 665        set_compound_order(page, order);
 666        __SetPageHead(page);
 667        for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
 668                __SetPageTail(p);
 669                set_page_count(p, 0);
 670                p->first_page = page;
 671        }
 672}
 673
 674/*
 675 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
 676 * transparent huge pages.  See the PageTransHuge() documentation for more
 677 * details.
 678 */
 679int PageHuge(struct page *page)
 680{
 681        compound_page_dtor *dtor;
 682
 683        if (!PageCompound(page))
 684                return 0;
 685
 686        page = compound_head(page);
 687        dtor = get_compound_page_dtor(page);
 688
 689        return dtor == free_huge_page;
 690}
 691EXPORT_SYMBOL_GPL(PageHuge);
 692
 693static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
 694{
 695        struct page *page;
 696
 697        if (h->order >= MAX_ORDER)
 698                return NULL;
 699
 700        page = alloc_pages_exact_node(nid,
 701                htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
 702                                                __GFP_REPEAT|__GFP_NOWARN,
 703                huge_page_order(h));
 704        if (page) {
 705                if (arch_prepare_hugepage(page)) {
 706                        __free_pages(page, huge_page_order(h));
 707                        return NULL;
 708                }
 709                prep_new_huge_page(h, page, nid);
 710        }
 711
 712        return page;
 713}
 714
 715/*
 716 * common helper functions for hstate_next_node_to_{alloc|free}.
 717 * We may have allocated or freed a huge page based on a different
 718 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
 719 * be outside of *nodes_allowed.  Ensure that we use an allowed
 720 * node for alloc or free.
 721 */
 722static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
 723{
 724        nid = next_node(nid, *nodes_allowed);
 725        if (nid == MAX_NUMNODES)
 726                nid = first_node(*nodes_allowed);
 727        VM_BUG_ON(nid >= MAX_NUMNODES);
 728
 729        return nid;
 730}
 731
 732static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
 733{
 734        if (!node_isset(nid, *nodes_allowed))
 735                nid = next_node_allowed(nid, nodes_allowed);
 736        return nid;
 737}
 738
 739/*
 740 * returns the previously saved node ["this node"] from which to
 741 * allocate a persistent huge page for the pool and advance the
 742 * next node from which to allocate, handling wrap at end of node
 743 * mask.
 744 */
 745static int hstate_next_node_to_alloc(struct hstate *h,
 746                                        nodemask_t *nodes_allowed)
 747{
 748        int nid;
 749
 750        VM_BUG_ON(!nodes_allowed);
 751
 752        nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
 753        h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
 754
 755        return nid;
 756}
 757
 758static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
 759{
 760        struct page *page;
 761        int start_nid;
 762        int next_nid;
 763        int ret = 0;
 764
 765        start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
 766        next_nid = start_nid;
 767
 768        do {
 769                page = alloc_fresh_huge_page_node(h, next_nid);
 770                if (page) {
 771                        ret = 1;
 772                        break;
 773                }
 774                next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
 775        } while (next_nid != start_nid);
 776
 777        if (ret)
 778                count_vm_event(HTLB_BUDDY_PGALLOC);
 779        else
 780                count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 781
 782        return ret;
 783}
 784
 785/*
 786 * helper for free_pool_huge_page() - return the previously saved
 787 * node ["this node"] from which to free a huge page.  Advance the
 788 * next node id whether or not we find a free huge page to free so
 789 * that the next attempt to free addresses the next node.
 790 */
 791static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
 792{
 793        int nid;
 794
 795        VM_BUG_ON(!nodes_allowed);
 796
 797        nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
 798        h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
 799
 800        return nid;
 801}
 802
 803/*
 804 * Free huge page from pool from next node to free.
 805 * Attempt to keep persistent huge pages more or less
 806 * balanced over allowed nodes.
 807 * Called with hugetlb_lock locked.
 808 */
 809static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 810                                                         bool acct_surplus)
 811{
 812        int start_nid;
 813        int next_nid;
 814        int ret = 0;
 815
 816        start_nid = hstate_next_node_to_free(h, nodes_allowed);
 817        next_nid = start_nid;
 818
 819        do {
 820                /*
 821                 * If we're returning unused surplus pages, only examine
 822                 * nodes with surplus pages.
 823                 */
 824                if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
 825                    !list_empty(&h->hugepage_freelists[next_nid])) {
 826                        struct page *page =
 827                                list_entry(h->hugepage_freelists[next_nid].next,
 828                                          struct page, lru);
 829                        list_del(&page->lru);
 830                        h->free_huge_pages--;
 831                        h->free_huge_pages_node[next_nid]--;
 832                        if (acct_surplus) {
 833                                h->surplus_huge_pages--;
 834                                h->surplus_huge_pages_node[next_nid]--;
 835                        }
 836                        update_and_free_page(h, page);
 837                        ret = 1;
 838                        break;
 839                }
 840                next_nid = hstate_next_node_to_free(h, nodes_allowed);
 841        } while (next_nid != start_nid);
 842
 843        return ret;
 844}
 845
 846static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
 847{
 848        struct page *page;
 849        unsigned int r_nid;
 850
 851        if (h->order >= MAX_ORDER)
 852                return NULL;
 853
 854        /*
 855         * Assume we will successfully allocate the surplus page to
 856         * prevent racing processes from causing the surplus to exceed
 857         * overcommit
 858         *
 859         * This however introduces a different race, where a process B
 860         * tries to grow the static hugepage pool while alloc_pages() is
 861         * called by process A. B will only examine the per-node
 862         * counters in determining if surplus huge pages can be
 863         * converted to normal huge pages in adjust_pool_surplus(). A
 864         * won't be able to increment the per-node counter, until the
 865         * lock is dropped by B, but B doesn't drop hugetlb_lock until
 866         * no more huge pages can be converted from surplus to normal
 867         * state (and doesn't try to convert again). Thus, we have a
 868         * case where a surplus huge page exists, the pool is grown, and
 869         * the surplus huge page still exists after, even though it
 870         * should just have been converted to a normal huge page. This
 871         * does not leak memory, though, as the hugepage will be freed
 872         * once it is out of use. It also does not allow the counters to
 873         * go out of whack in adjust_pool_surplus() as we don't modify
 874         * the node values until we've gotten the hugepage and only the
 875         * per-node value is checked there.
 876         */
 877        spin_lock(&hugetlb_lock);
 878        if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
 879                spin_unlock(&hugetlb_lock);
 880                return NULL;
 881        } else {
 882                h->nr_huge_pages++;
 883                h->surplus_huge_pages++;
 884        }
 885        spin_unlock(&hugetlb_lock);
 886
 887        if (nid == NUMA_NO_NODE)
 888                page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
 889                                   __GFP_REPEAT|__GFP_NOWARN,
 890                                   huge_page_order(h));
 891        else
 892                page = alloc_pages_exact_node(nid,
 893                        htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
 894                        __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
 895
 896        if (page && arch_prepare_hugepage(page)) {
 897                __free_pages(page, huge_page_order(h));
 898                page = NULL;
 899        }
 900
 901        spin_lock(&hugetlb_lock);
 902        if (page) {
 903                INIT_LIST_HEAD(&page->lru);
 904                r_nid = page_to_nid(page);
 905                set_compound_page_dtor(page, free_huge_page);
 906                set_hugetlb_cgroup(page, NULL);
 907                /*
 908                 * We incremented the global counters already
 909                 */
 910                h->nr_huge_pages_node[r_nid]++;
 911                h->surplus_huge_pages_node[r_nid]++;
 912                __count_vm_event(HTLB_BUDDY_PGALLOC);
 913        } else {
 914                h->nr_huge_pages--;
 915                h->surplus_huge_pages--;
 916                __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 917        }
 918        spin_unlock(&hugetlb_lock);
 919
 920        return page;
 921}
 922
 923/*
 924 * This allocation function is useful in the context where vma is irrelevant.
 925 * E.g. soft-offlining uses this function because it only cares physical
 926 * address of error page.
 927 */
 928struct page *alloc_huge_page_node(struct hstate *h, int nid)
 929{
 930        struct page *page;
 931
 932        spin_lock(&hugetlb_lock);
 933        page = dequeue_huge_page_node(h, nid);
 934        spin_unlock(&hugetlb_lock);
 935
 936        if (!page)
 937                page = alloc_buddy_huge_page(h, nid);
 938
 939        return page;
 940}
 941
 942/*
 943 * Increase the hugetlb pool such that it can accommodate a reservation
 944 * of size 'delta'.
 945 */
 946static int gather_surplus_pages(struct hstate *h, int delta)
 947{
 948        struct list_head surplus_list;
 949        struct page *page, *tmp;
 950        int ret, i;
 951        int needed, allocated;
 952        bool alloc_ok = true;
 953
 954        needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
 955        if (needed <= 0) {
 956                h->resv_huge_pages += delta;
 957                return 0;
 958        }
 959
 960        allocated = 0;
 961        INIT_LIST_HEAD(&surplus_list);
 962
 963        ret = -ENOMEM;
 964retry:
 965        spin_unlock(&hugetlb_lock);
 966        for (i = 0; i < needed; i++) {
 967                page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
 968                if (!page) {
 969                        alloc_ok = false;
 970                        break;
 971                }
 972                list_add(&page->lru, &surplus_list);
 973        }
 974        allocated += i;
 975
 976        /*
 977         * After retaking hugetlb_lock, we need to recalculate 'needed'
 978         * because either resv_huge_pages or free_huge_pages may have changed.
 979         */
 980        spin_lock(&hugetlb_lock);
 981        needed = (h->resv_huge_pages + delta) -
 982                        (h->free_huge_pages + allocated);
 983        if (needed > 0) {
 984                if (alloc_ok)
 985                        goto retry;
 986                /*
 987                 * We were not able to allocate enough pages to
 988                 * satisfy the entire reservation so we free what
 989                 * we've allocated so far.
 990                 */
 991                goto free;
 992        }
 993        /*
 994         * The surplus_list now contains _at_least_ the number of extra pages
 995         * needed to accommodate the reservation.  Add the appropriate number
 996         * of pages to the hugetlb pool and free the extras back to the buddy
 997         * allocator.  Commit the entire reservation here to prevent another
 998         * process from stealing the pages as they are added to the pool but
 999         * before they are reserved.
1000         */
1001        needed += allocated;
1002        h->resv_huge_pages += delta;
1003        ret = 0;
1004
1005        /* Free the needed pages to the hugetlb pool */
1006        list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1007                if ((--needed) < 0)
1008                        break;
1009                /*
1010                 * This page is now managed by the hugetlb allocator and has
1011                 * no users -- drop the buddy allocator's reference.
1012                 */
1013                put_page_testzero(page);
1014                VM_BUG_ON(page_count(page));
1015                enqueue_huge_page(h, page);
1016        }
1017free:
1018        spin_unlock(&hugetlb_lock);
1019
1020        /* Free unnecessary surplus pages to the buddy allocator */
1021        if (!list_empty(&surplus_list)) {
1022                list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1023                        put_page(page);
1024                }
1025        }
1026        spin_lock(&hugetlb_lock);
1027
1028        return ret;
1029}
1030
1031/*
1032 * When releasing a hugetlb pool reservation, any surplus pages that were
1033 * allocated to satisfy the reservation must be explicitly freed if they were
1034 * never used.
1035 * Called with hugetlb_lock held.
1036 */
1037static void return_unused_surplus_pages(struct hstate *h,
1038                                        unsigned long unused_resv_pages)
1039{
1040        unsigned long nr_pages;
1041
1042        /* Uncommit the reservation */
1043        h->resv_huge_pages -= unused_resv_pages;
1044
1045        /* Cannot return gigantic pages currently */
1046        if (h->order >= MAX_ORDER)
1047                return;
1048
1049        nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1050
1051        /*
1052         * We want to release as many surplus pages as possible, spread
1053         * evenly across all nodes with memory. Iterate across these nodes
1054         * until we can no longer free unreserved surplus pages. This occurs
1055         * when the nodes with surplus pages have no free pages.
1056         * free_pool_huge_page() will balance the the freed pages across the
1057         * on-line nodes with memory and will handle the hstate accounting.
1058         */
1059        while (nr_pages--) {
1060                if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1061                        break;
1062        }
1063}
1064
1065/*
1066 * Determine if the huge page at addr within the vma has an associated
1067 * reservation.  Where it does not we will need to logically increase
1068 * reservation and actually increase subpool usage before an allocation
1069 * can occur.  Where any new reservation would be required the
1070 * reservation change is prepared, but not committed.  Once the page
1071 * has been allocated from the subpool and instantiated the change should
1072 * be committed via vma_commit_reservation.  No action is required on
1073 * failure.
1074 */
1075static long vma_needs_reservation(struct hstate *h,
1076                        struct vm_area_struct *vma, unsigned long addr)
1077{
1078        struct address_space *mapping = vma->vm_file->f_mapping;
1079        struct inode *inode = mapping->host;
1080
1081        if (vma->vm_flags & VM_MAYSHARE) {
1082                pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1083                return region_chg(&inode->i_mapping->private_list,
1084                                                        idx, idx + 1);
1085
1086        } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1087                return 1;
1088
1089        } else  {
1090                long err;
1091                pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1092                struct resv_map *reservations = vma_resv_map(vma);
1093
1094                err = region_chg(&reservations->regions, idx, idx + 1);
1095                if (err < 0)
1096                        return err;
1097                return 0;
1098        }
1099}
1100static void vma_commit_reservation(struct hstate *h,
1101                        struct vm_area_struct *vma, unsigned long addr)
1102{
1103        struct address_space *mapping = vma->vm_file->f_mapping;
1104        struct inode *inode = mapping->host;
1105
1106        if (vma->vm_flags & VM_MAYSHARE) {
1107                pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1108                region_add(&inode->i_mapping->private_list, idx, idx + 1);
1109
1110        } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1111                pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1112                struct resv_map *reservations = vma_resv_map(vma);
1113
1114                /* Mark this page used in the map. */
1115                region_add(&reservations->regions, idx, idx + 1);
1116        }
1117}
1118
1119static struct page *alloc_huge_page(struct vm_area_struct *vma,
1120                                    unsigned long addr, int avoid_reserve)
1121{
1122        struct hugepage_subpool *spool = subpool_vma(vma);
1123        struct hstate *h = hstate_vma(vma);
1124        struct page *page;
1125        long chg;
1126        int ret, idx;
1127        struct hugetlb_cgroup *h_cg;
1128
1129        idx = hstate_index(h);
1130        /*
1131         * Processes that did not create the mapping will have no
1132         * reserves and will not have accounted against subpool
1133         * limit. Check that the subpool limit can be made before
1134         * satisfying the allocation MAP_NORESERVE mappings may also
1135         * need pages and subpool limit allocated allocated if no reserve
1136         * mapping overlaps.
1137         */
1138        chg = vma_needs_reservation(h, vma, addr);
1139        if (chg < 0)
1140                return ERR_PTR(-ENOMEM);
1141        if (chg)
1142                if (hugepage_subpool_get_pages(spool, chg))
1143                        return ERR_PTR(-ENOSPC);
1144
1145        ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1146        if (ret) {
1147                hugepage_subpool_put_pages(spool, chg);
1148                return ERR_PTR(-ENOSPC);
1149        }
1150        spin_lock(&hugetlb_lock);
1151        page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
1152        if (page) {
1153                /* update page cgroup details */
1154                hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
1155                                             h_cg, page);
1156                spin_unlock(&hugetlb_lock);
1157        } else {
1158                spin_unlock(&hugetlb_lock);
1159                page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
1160                if (!page) {
1161                        hugetlb_cgroup_uncharge_cgroup(idx,
1162                                                       pages_per_huge_page(h),
1163                                                       h_cg);
1164                        hugepage_subpool_put_pages(spool, chg);
1165                        return ERR_PTR(-ENOSPC);
1166                }
1167                spin_lock(&hugetlb_lock);
1168                hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
1169                                             h_cg, page);
1170                list_move(&page->lru, &h->hugepage_activelist);
1171                spin_unlock(&hugetlb_lock);
1172        }
1173
1174        set_page_private(page, (unsigned long)spool);
1175
1176        vma_commit_reservation(h, vma, addr);
1177        return page;
1178}
1179
1180int __weak alloc_bootmem_huge_page(struct hstate *h)
1181{
1182        struct huge_bootmem_page *m;
1183        int nr_nodes = nodes_weight(node_states[N_MEMORY]);
1184
1185        while (nr_nodes) {
1186                void *addr;
1187
1188                addr = __alloc_bootmem_node_nopanic(
1189                                NODE_DATA(hstate_next_node_to_alloc(h,
1190                                                &node_states[N_MEMORY])),
1191                                huge_page_size(h), huge_page_size(h), 0);
1192
1193                if (addr) {
1194                        /*
1195                         * Use the beginning of the huge page to store the
1196                         * huge_bootmem_page struct (until gather_bootmem
1197                         * puts them into the mem_map).
1198                         */
1199                        m = addr;
1200                        goto found;
1201                }
1202                nr_nodes--;
1203        }
1204        return 0;
1205
1206found:
1207        BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1208        /* Put them into a private list first because mem_map is not up yet */
1209        list_add(&m->list, &huge_boot_pages);
1210        m->hstate = h;
1211        return 1;
1212}
1213
1214static void prep_compound_huge_page(struct page *page, int order)
1215{
1216        if (unlikely(order > (MAX_ORDER - 1)))
1217                prep_compound_gigantic_page(page, order);
1218        else
1219                prep_compound_page(page, order);
1220}
1221
1222/* Put bootmem huge pages into the standard lists after mem_map is up */
1223static void __init gather_bootmem_prealloc(void)
1224{
1225        struct huge_bootmem_page *m;
1226
1227        list_for_each_entry(m, &huge_boot_pages, list) {
1228                struct hstate *h = m->hstate;
1229                struct page *page;
1230
1231#ifdef CONFIG_HIGHMEM
1232                page = pfn_to_page(m->phys >> PAGE_SHIFT);
1233                free_bootmem_late((unsigned long)m,
1234                                  sizeof(struct huge_bootmem_page));
1235#else
1236                page = virt_to_page(m);
1237#endif
1238                __ClearPageReserved(page);
1239                WARN_ON(page_count(page) != 1);
1240                prep_compound_huge_page(page, h->order);
1241                prep_new_huge_page(h, page, page_to_nid(page));
1242                /*
1243                 * If we had gigantic hugepages allocated at boot time, we need
1244                 * to restore the 'stolen' pages to totalram_pages in order to
1245                 * fix confusing memory reports from free(1) and another
1246                 * side-effects, like CommitLimit going negative.
1247                 */
1248                if (h->order > (MAX_ORDER - 1))
1249                        totalram_pages += 1 << h->order;
1250        }
1251}
1252
1253static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1254{
1255        unsigned long i;
1256
1257        for (i = 0; i < h->max_huge_pages; ++i) {
1258                if (h->order >= MAX_ORDER) {
1259                        if (!alloc_bootmem_huge_page(h))
1260                                break;
1261                } else if (!alloc_fresh_huge_page(h,
1262                                         &node_states[N_MEMORY]))
1263                        break;
1264        }
1265        h->max_huge_pages = i;
1266}
1267
1268static void __init hugetlb_init_hstates(void)
1269{
1270        struct hstate *h;
1271
1272        for_each_hstate(h) {
1273                /* oversize hugepages were init'ed in early boot */
1274                if (h->order < MAX_ORDER)
1275                        hugetlb_hstate_alloc_pages(h);
1276        }
1277}
1278
1279static char * __init memfmt(char *buf, unsigned long n)
1280{
1281        if (n >= (1UL << 30))
1282                sprintf(buf, "%lu GB", n >> 30);
1283        else if (n >= (1UL << 20))
1284                sprintf(buf, "%lu MB", n >> 20);
1285        else
1286                sprintf(buf, "%lu KB", n >> 10);
1287        return buf;
1288}
1289
1290static void __init report_hugepages(void)
1291{
1292        struct hstate *h;
1293
1294        for_each_hstate(h) {
1295                char buf[32];
1296                pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
1297                        memfmt(buf, huge_page_size(h)),
1298                        h->free_huge_pages);
1299        }
1300}
1301
1302#ifdef CONFIG_HIGHMEM
1303static void try_to_free_low(struct hstate *h, unsigned long count,
1304                                                nodemask_t *nodes_allowed)
1305{
1306        int i;
1307
1308        if (h->order >= MAX_ORDER)
1309                return;
1310
1311        for_each_node_mask(i, *nodes_allowed) {
1312                struct page *page, *next;
1313                struct list_head *freel = &h->hugepage_freelists[i];
1314                list_for_each_entry_safe(page, next, freel, lru) {
1315                        if (count >= h->nr_huge_pages)
1316                                return;
1317                        if (PageHighMem(page))
1318                                continue;
1319                        list_del(&page->lru);
1320                        update_and_free_page(h, page);
1321                        h->free_huge_pages--;
1322                        h->free_huge_pages_node[page_to_nid(page)]--;
1323                }
1324        }
1325}
1326#else
1327static inline void try_to_free_low(struct hstate *h, unsigned long count,
1328                                                nodemask_t *nodes_allowed)
1329{
1330}
1331#endif
1332
1333/*
1334 * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1335 * balanced by operating on them in a round-robin fashion.
1336 * Returns 1 if an adjustment was made.
1337 */
1338static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1339                                int delta)
1340{
1341        int start_nid, next_nid;
1342        int ret = 0;
1343
1344        VM_BUG_ON(delta != -1 && delta != 1);
1345
1346        if (delta < 0)
1347                start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1348        else
1349                start_nid = hstate_next_node_to_free(h, nodes_allowed);
1350        next_nid = start_nid;
1351
1352        do {
1353                int nid = next_nid;
1354                if (delta < 0)  {
1355                        /*
1356                         * To shrink on this node, there must be a surplus page
1357                         */
1358                        if (!h->surplus_huge_pages_node[nid]) {
1359                                next_nid = hstate_next_node_to_alloc(h,
1360                                                                nodes_allowed);
1361                                continue;
1362                        }
1363                }
1364                if (delta > 0) {
1365                        /*
1366                         * Surplus cannot exceed the total number of pages
1367                         */
1368                        if (h->surplus_huge_pages_node[nid] >=
1369                                                h->nr_huge_pages_node[nid]) {
1370                                next_nid = hstate_next_node_to_free(h,
1371                                                                nodes_allowed);
1372                                continue;
1373                        }
1374                }
1375
1376                h->surplus_huge_pages += delta;
1377                h->surplus_huge_pages_node[nid] += delta;
1378                ret = 1;
1379                break;
1380        } while (next_nid != start_nid);
1381
1382        return ret;
1383}
1384
1385#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1386static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1387                                                nodemask_t *nodes_allowed)
1388{
1389        unsigned long min_count, ret;
1390
1391        if (h->order >= MAX_ORDER)
1392                return h->max_huge_pages;
1393
1394        /*
1395         * Increase the pool size
1396         * First take pages out of surplus state.  Then make up the
1397         * remaining difference by allocating fresh huge pages.
1398         *
1399         * We might race with alloc_buddy_huge_page() here and be unable
1400         * to convert a surplus huge page to a normal huge page. That is
1401         * not critical, though, it just means the overall size of the
1402         * pool might be one hugepage larger than it needs to be, but
1403         * within all the constraints specified by the sysctls.
1404         */
1405        spin_lock(&hugetlb_lock);
1406        while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1407                if (!adjust_pool_surplus(h, nodes_allowed, -1))
1408                        break;
1409        }
1410
1411        while (count > persistent_huge_pages(h)) {
1412                /*
1413                 * If this allocation races such that we no longer need the
1414                 * page, free_huge_page will handle it by freeing the page
1415                 * and reducing the surplus.
1416                 */
1417                spin_unlock(&hugetlb_lock);
1418                ret = alloc_fresh_huge_page(h, nodes_allowed);
1419                spin_lock(&hugetlb_lock);
1420                if (!ret)
1421                        goto out;
1422
1423                /* Bail for signals. Probably ctrl-c from user */
1424                if (signal_pending(current))
1425                        goto out;
1426        }
1427
1428        /*
1429         * Decrease the pool size
1430         * First return free pages to the buddy allocator (being careful
1431         * to keep enough around to satisfy reservations).  Then place
1432         * pages into surplus state as needed so the pool will shrink
1433         * to the desired size as pages become free.
1434         *
1435         * By placing pages into the surplus state independent of the
1436         * overcommit value, we are allowing the surplus pool size to
1437         * exceed overcommit. There are few sane options here. Since
1438         * alloc_buddy_huge_page() is checking the global counter,
1439         * though, we'll note that we're not allowed to exceed surplus
1440         * and won't grow the pool anywhere else. Not until one of the
1441         * sysctls are changed, or the surplus pages go out of use.
1442         */
1443        min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1444        min_count = max(count, min_count);
1445        try_to_free_low(h, min_count, nodes_allowed);
1446        while (min_count < persistent_huge_pages(h)) {
1447                if (!free_pool_huge_page(h, nodes_allowed, 0))
1448                        break;
1449        }
1450        while (count < persistent_huge_pages(h)) {
1451                if (!adjust_pool_surplus(h, nodes_allowed, 1))
1452                        break;
1453        }
1454out:
1455        ret = persistent_huge_pages(h);
1456        spin_unlock(&hugetlb_lock);
1457        return ret;
1458}
1459
1460#define HSTATE_ATTR_RO(_name) \
1461        static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1462
1463#define HSTATE_ATTR(_name) \
1464        static struct kobj_attribute _name##_attr = \
1465                __ATTR(_name, 0644, _name##_show, _name##_store)
1466
1467static struct kobject *hugepages_kobj;
1468static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1469
1470static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1471
1472static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1473{
1474        int i;
1475
1476        for (i = 0; i < HUGE_MAX_HSTATE; i++)
1477                if (hstate_kobjs[i] == kobj) {
1478                        if (nidp)
1479                                *nidp = NUMA_NO_NODE;
1480                        return &hstates[i];
1481                }
1482
1483        return kobj_to_node_hstate(kobj, nidp);
1484}
1485
1486static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1487                                        struct kobj_attribute *attr, char *buf)
1488{
1489        struct hstate *h;
1490        unsigned long nr_huge_pages;
1491        int nid;
1492
1493        h = kobj_to_hstate(kobj, &nid);
1494        if (nid == NUMA_NO_NODE)
1495                nr_huge_pages = h->nr_huge_pages;
1496        else
1497                nr_huge_pages = h->nr_huge_pages_node[nid];
1498
1499        return sprintf(buf, "%lu\n", nr_huge_pages);
1500}
1501
1502static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1503                        struct kobject *kobj, struct kobj_attribute *attr,
1504                        const char *buf, size_t len)
1505{
1506        int err;
1507        int nid;
1508        unsigned long count;
1509        struct hstate *h;
1510        NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1511
1512        err = strict_strtoul(buf, 10, &count);
1513        if (err)
1514                goto out;
1515
1516        h = kobj_to_hstate(kobj, &nid);
1517        if (h->order >= MAX_ORDER) {
1518                err = -EINVAL;
1519                goto out;
1520        }
1521
1522        if (nid == NUMA_NO_NODE) {
1523                /*
1524                 * global hstate attribute
1525                 */
1526                if (!(obey_mempolicy &&
1527                                init_nodemask_of_mempolicy(nodes_allowed))) {
1528                        NODEMASK_FREE(nodes_allowed);
1529                        nodes_allowed = &node_states[N_MEMORY];
1530                }
1531        } else if (nodes_allowed) {
1532                /*
1533                 * per node hstate attribute: adjust count to global,
1534                 * but restrict alloc/free to the specified node.
1535                 */
1536                count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1537                init_nodemask_of_node(nodes_allowed, nid);
1538        } else
1539                nodes_allowed = &node_states[N_MEMORY];
1540
1541        h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1542
1543        if (nodes_allowed != &node_states[N_MEMORY])
1544                NODEMASK_FREE(nodes_allowed);
1545
1546        return len;
1547out:
1548        NODEMASK_FREE(nodes_allowed);
1549        return err;
1550}
1551
1552static ssize_t nr_hugepages_show(struct kobject *kobj,
1553                                       struct kobj_attribute *attr, char *buf)
1554{
1555        return nr_hugepages_show_common(kobj, attr, buf);
1556}
1557
1558static ssize_t nr_hugepages_store(struct kobject *kobj,
1559               struct kobj_attribute *attr, const char *buf, size_t len)
1560{
1561        return nr_hugepages_store_common(false, kobj, attr, buf, len);
1562}
1563HSTATE_ATTR(nr_hugepages);
1564
1565#ifdef CONFIG_NUMA
1566
1567/*
1568 * hstate attribute for optionally mempolicy-based constraint on persistent
1569 * huge page alloc/free.
1570 */
1571static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1572                                       struct kobj_attribute *attr, char *buf)
1573{
1574        return nr_hugepages_show_common(kobj, attr, buf);
1575}
1576
1577static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1578               struct kobj_attribute *attr, const char *buf, size_t len)
1579{
1580        return nr_hugepages_store_common(true, kobj, attr, buf, len);
1581}
1582HSTATE_ATTR(nr_hugepages_mempolicy);
1583#endif
1584
1585
1586static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1587                                        struct kobj_attribute *attr, char *buf)
1588{
1589        struct hstate *h = kobj_to_hstate(kobj, NULL);
1590        return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1591}
1592
1593static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1594                struct kobj_attribute *attr, const char *buf, size_t count)
1595{
1596        int err;
1597        unsigned long input;
1598        struct hstate *h = kobj_to_hstate(kobj, NULL);
1599
1600        if (h->order >= MAX_ORDER)
1601                return -EINVAL;
1602
1603        err = strict_strtoul(buf, 10, &input);
1604        if (err)
1605                return err;
1606
1607        spin_lock(&hugetlb_lock);
1608        h->nr_overcommit_huge_pages = input;
1609        spin_unlock(&hugetlb_lock);
1610
1611        return count;
1612}
1613HSTATE_ATTR(nr_overcommit_hugepages);
1614
1615static ssize_t free_hugepages_show(struct kobject *kobj,
1616                                        struct kobj_attribute *attr, char *buf)
1617{
1618        struct hstate *h;
1619        unsigned long free_huge_pages;
1620        int nid;
1621
1622        h = kobj_to_hstate(kobj, &nid);
1623        if (nid == NUMA_NO_NODE)
1624                free_huge_pages = h->free_huge_pages;
1625        else
1626                free_huge_pages = h->free_huge_pages_node[nid];
1627
1628        return sprintf(buf, "%lu\n", free_huge_pages);
1629}
1630HSTATE_ATTR_RO(free_hugepages);
1631
1632static ssize_t resv_hugepages_show(struct kobject *kobj,
1633                                        struct kobj_attribute *attr, char *buf)
1634{
1635        struct hstate *h = kobj_to_hstate(kobj, NULL);
1636        return sprintf(buf, "%lu\n", h->resv_huge_pages);
1637}
1638HSTATE_ATTR_RO(resv_hugepages);
1639
1640static ssize_t surplus_hugepages_show(struct kobject *kobj,
1641                                        struct kobj_attribute *attr, char *buf)
1642{
1643        struct hstate *h;
1644        unsigned long surplus_huge_pages;
1645        int nid;
1646
1647        h = kobj_to_hstate(kobj, &nid);
1648        if (nid == NUMA_NO_NODE)
1649                surplus_huge_pages = h->surplus_huge_pages;
1650        else
1651                surplus_huge_pages = h->surplus_huge_pages_node[nid];
1652
1653        return sprintf(buf, "%lu\n", surplus_huge_pages);
1654}
1655HSTATE_ATTR_RO(surplus_hugepages);
1656
1657static struct attribute *hstate_attrs[] = {
1658        &nr_hugepages_attr.attr,
1659        &nr_overcommit_hugepages_attr.attr,
1660        &free_hugepages_attr.attr,
1661        &resv_hugepages_attr.attr,
1662        &surplus_hugepages_attr.attr,
1663#ifdef CONFIG_NUMA
1664        &nr_hugepages_mempolicy_attr.attr,
1665#endif
1666        NULL,
1667};
1668
1669static struct attribute_group hstate_attr_group = {
1670        .attrs = hstate_attrs,
1671};
1672
1673static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1674                                    struct kobject **hstate_kobjs,
1675                                    struct attribute_group *hstate_attr_group)
1676{
1677        int retval;
1678        int hi = hstate_index(h);
1679
1680        hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1681        if (!hstate_kobjs[hi])
1682                return -ENOMEM;
1683
1684        retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1685        if (retval)
1686                kobject_put(hstate_kobjs[hi]);
1687
1688        return retval;
1689}
1690
1691static void __init hugetlb_sysfs_init(void)
1692{
1693        struct hstate *h;
1694        int err;
1695
1696        hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1697        if (!hugepages_kobj)
1698                return;
1699
1700        for_each_hstate(h) {
1701                err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1702                                         hstate_kobjs, &hstate_attr_group);
1703                if (err)
1704                        pr_err("Hugetlb: Unable to add hstate %s", h->name);
1705        }
1706}
1707
1708#ifdef CONFIG_NUMA
1709
1710/*
1711 * node_hstate/s - associate per node hstate attributes, via their kobjects,
1712 * with node devices in node_devices[] using a parallel array.  The array
1713 * index of a node device or _hstate == node id.
1714 * This is here to avoid any static dependency of the node device driver, in
1715 * the base kernel, on the hugetlb module.
1716 */
1717struct node_hstate {
1718        struct kobject          *hugepages_kobj;
1719        struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1720};
1721struct node_hstate node_hstates[MAX_NUMNODES];
1722
1723/*
1724 * A subset of global hstate attributes for node devices
1725 */
1726static struct attribute *per_node_hstate_attrs[] = {
1727        &nr_hugepages_attr.attr,
1728        &free_hugepages_attr.attr,
1729        &surplus_hugepages_attr.attr,
1730        NULL,
1731};
1732
1733static struct attribute_group per_node_hstate_attr_group = {
1734        .attrs = per_node_hstate_attrs,
1735};
1736
1737/*
1738 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
1739 * Returns node id via non-NULL nidp.
1740 */
1741static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1742{
1743        int nid;
1744
1745        for (nid = 0; nid < nr_node_ids; nid++) {
1746                struct node_hstate *nhs = &node_hstates[nid];
1747                int i;
1748                for (i = 0; i < HUGE_MAX_HSTATE; i++)
1749                        if (nhs->hstate_kobjs[i] == kobj) {
1750                                if (nidp)
1751                                        *nidp = nid;
1752                                return &hstates[i];
1753                        }
1754        }
1755
1756        BUG();
1757        return NULL;
1758}
1759
1760/*
1761 * Unregister hstate attributes from a single node device.
1762 * No-op if no hstate attributes attached.
1763 */
1764void hugetlb_unregister_node(struct node *node)
1765{
1766        struct hstate *h;
1767        struct node_hstate *nhs = &node_hstates[node->dev.id];
1768
1769        if (!nhs->hugepages_kobj)
1770                return;         /* no hstate attributes */
1771
1772        for_each_hstate(h) {
1773                int idx = hstate_index(h);
1774                if (nhs->hstate_kobjs[idx]) {
1775                        kobject_put(nhs->hstate_kobjs[idx]);
1776                        nhs->hstate_kobjs[idx] = NULL;
1777                }
1778        }
1779
1780        kobject_put(nhs->hugepages_kobj);
1781        nhs->hugepages_kobj = NULL;
1782}
1783
1784/*
1785 * hugetlb module exit:  unregister hstate attributes from node devices
1786 * that have them.
1787 */
1788static void hugetlb_unregister_all_nodes(void)
1789{
1790        int nid;
1791
1792        /*
1793         * disable node device registrations.
1794         */
1795        register_hugetlbfs_with_node(NULL, NULL);
1796
1797        /*
1798         * remove hstate attributes from any nodes that have them.
1799         */
1800        for (nid = 0; nid < nr_node_ids; nid++)
1801                hugetlb_unregister_node(node_devices[nid]);
1802}
1803
1804/*
1805 * Register hstate attributes for a single node device.
1806 * No-op if attributes already registered.
1807 */
1808void hugetlb_register_node(struct node *node)
1809{
1810        struct hstate *h;
1811        struct node_hstate *nhs = &node_hstates[node->dev.id];
1812        int err;
1813
1814        if (nhs->hugepages_kobj)
1815                return;         /* already allocated */
1816
1817        nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1818                                                        &node->dev.kobj);
1819        if (!nhs->hugepages_kobj)
1820                return;
1821
1822        for_each_hstate(h) {
1823                err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1824                                                nhs->hstate_kobjs,
1825                                                &per_node_hstate_attr_group);
1826                if (err) {
1827                        pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
1828                                h->name, node->dev.id);
1829                        hugetlb_unregister_node(node);
1830                        break;
1831                }
1832        }
1833}
1834
1835/*
1836 * hugetlb init time:  register hstate attributes for all registered node
1837 * devices of nodes that have memory.  All on-line nodes should have
1838 * registered their associated device by this time.
1839 */
1840static void hugetlb_register_all_nodes(void)
1841{
1842        int nid;
1843
1844        for_each_node_state(nid, N_MEMORY) {
1845                struct node *node = node_devices[nid];
1846                if (node->dev.id == nid)
1847                        hugetlb_register_node(node);
1848        }
1849
1850        /*
1851         * Let the node device driver know we're here so it can
1852         * [un]register hstate attributes on node hotplug.
1853         */
1854        register_hugetlbfs_with_node(hugetlb_register_node,
1855                                     hugetlb_unregister_node);
1856}
1857#else   /* !CONFIG_NUMA */
1858
1859static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1860{
1861        BUG();
1862        if (nidp)
1863                *nidp = -1;
1864        return NULL;
1865}
1866
1867static void hugetlb_unregister_all_nodes(void) { }
1868
1869static void hugetlb_register_all_nodes(void) { }
1870
1871#endif
1872
1873static void __exit hugetlb_exit(void)
1874{
1875        struct hstate *h;
1876
1877        hugetlb_unregister_all_nodes();
1878
1879        for_each_hstate(h) {
1880                kobject_put(hstate_kobjs[hstate_index(h)]);
1881        }
1882
1883        kobject_put(hugepages_kobj);
1884}
1885module_exit(hugetlb_exit);
1886
1887static int __init hugetlb_init(void)
1888{
1889        /* Some platform decide whether they support huge pages at boot
1890         * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1891         * there is no such support
1892         */
1893        if (HPAGE_SHIFT == 0)
1894                return 0;
1895
1896        if (!size_to_hstate(default_hstate_size)) {
1897                default_hstate_size = HPAGE_SIZE;
1898                if (!size_to_hstate(default_hstate_size))
1899                        hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1900        }
1901        default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
1902        if (default_hstate_max_huge_pages)
1903                default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1904
1905        hugetlb_init_hstates();
1906        gather_bootmem_prealloc();
1907        report_hugepages();
1908
1909        hugetlb_sysfs_init();
1910        hugetlb_register_all_nodes();
1911        hugetlb_cgroup_file_init();
1912
1913        return 0;
1914}
1915module_init(hugetlb_init);
1916
1917/* Should be called on processing a hugepagesz=... option */
1918void __init hugetlb_add_hstate(unsigned order)
1919{
1920        struct hstate *h;
1921        unsigned long i;
1922
1923        if (size_to_hstate(PAGE_SIZE << order)) {
1924                pr_warning("hugepagesz= specified twice, ignoring\n");
1925                return;
1926        }
1927        BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
1928        BUG_ON(order == 0);
1929        h = &hstates[hugetlb_max_hstate++];
1930        h->order = order;
1931        h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1932        h->nr_huge_pages = 0;
1933        h->free_huge_pages = 0;
1934        for (i = 0; i < MAX_NUMNODES; ++i)
1935                INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1936        INIT_LIST_HEAD(&h->hugepage_activelist);
1937        h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
1938        h->next_nid_to_free = first_node(node_states[N_MEMORY]);
1939        snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1940                                        huge_page_size(h)/1024);
1941
1942        parsed_hstate = h;
1943}
1944
1945static int __init hugetlb_nrpages_setup(char *s)
1946{
1947        unsigned long *mhp;
1948        static unsigned long *last_mhp;
1949
1950        /*
1951         * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
1952         * so this hugepages= parameter goes to the "default hstate".
1953         */
1954        if (!hugetlb_max_hstate)
1955                mhp = &default_hstate_max_huge_pages;
1956        else
1957                mhp = &parsed_hstate->max_huge_pages;
1958
1959        if (mhp == last_mhp) {
1960                pr_warning("hugepages= specified twice without "
1961                           "interleaving hugepagesz=, ignoring\n");
1962                return 1;
1963        }
1964
1965        if (sscanf(s, "%lu", mhp) <= 0)
1966                *mhp = 0;
1967
1968        /*
1969         * Global state is always initialized later in hugetlb_init.
1970         * But we need to allocate >= MAX_ORDER hstates here early to still
1971         * use the bootmem allocator.
1972         */
1973        if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
1974                hugetlb_hstate_alloc_pages(parsed_hstate);
1975
1976        last_mhp = mhp;
1977
1978        return 1;
1979}
1980__setup("hugepages=", hugetlb_nrpages_setup);
1981
1982static int __init hugetlb_default_setup(char *s)
1983{
1984        default_hstate_size = memparse(s, &s);
1985        return 1;
1986}
1987__setup("default_hugepagesz=", hugetlb_default_setup);
1988
1989static unsigned int cpuset_mems_nr(unsigned int *array)
1990{
1991        int node;
1992        unsigned int nr = 0;
1993
1994        for_each_node_mask(node, cpuset_current_mems_allowed)
1995                nr += array[node];
1996
1997        return nr;
1998}
1999
2000#ifdef CONFIG_SYSCTL
2001static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2002                         struct ctl_table *table, int write,
2003                         void __user *buffer, size_t *length, loff_t *ppos)
2004{
2005        struct hstate *h = &default_hstate;
2006        unsigned long tmp;
2007        int ret;
2008
2009        tmp = h->max_huge_pages;
2010
2011        if (write && h->order >= MAX_ORDER)
2012                return -EINVAL;
2013
2014        table->data = &tmp;
2015        table->maxlen = sizeof(unsigned long);
2016        ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2017        if (ret)
2018                goto out;
2019
2020        if (write) {
2021                NODEMASK_ALLOC(nodemask_t, nodes_allowed,
2022                                                GFP_KERNEL | __GFP_NORETRY);
2023                if (!(obey_mempolicy &&
2024                               init_nodemask_of_mempolicy(nodes_allowed))) {
2025                        NODEMASK_FREE(nodes_allowed);
2026                        nodes_allowed = &node_states[N_MEMORY];
2027                }
2028                h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
2029
2030                if (nodes_allowed != &node_states[N_MEMORY])
2031                        NODEMASK_FREE(nodes_allowed);
2032        }
2033out:
2034        return ret;
2035}
2036
2037int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2038                          void __user *buffer, size_t *length, loff_t *ppos)
2039{
2040
2041        return hugetlb_sysctl_handler_common(false, table, write,
2042                                                        buffer, length, ppos);
2043}
2044
2045#ifdef CONFIG_NUMA
2046int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2047                          void __user *buffer, size_t *length, loff_t *ppos)
2048{
2049        return hugetlb_sysctl_handler_common(true, table, write,
2050                                                        buffer, length, ppos);
2051}
2052#endif /* CONFIG_NUMA */
2053
2054int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
2055                        void __user *buffer,
2056                        size_t *length, loff_t *ppos)
2057{
2058        proc_dointvec(table, write, buffer, length, ppos);
2059        if (hugepages_treat_as_movable)
2060                htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
2061        else
2062                htlb_alloc_mask = GFP_HIGHUSER;
2063        return 0;
2064}
2065
2066int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2067                        void __user *buffer,
2068                        size_t *length, loff_t *ppos)
2069{
2070        struct hstate *h = &default_hstate;
2071        unsigned long tmp;
2072        int ret;
2073
2074        tmp = h->nr_overcommit_huge_pages;
2075
2076        if (write && h->order >= MAX_ORDER)
2077                return -EINVAL;
2078
2079        table->data = &tmp;
2080        table->maxlen = sizeof(unsigned long);
2081        ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2082        if (ret)
2083                goto out;
2084
2085        if (write) {
2086                spin_lock(&hugetlb_lock);
2087                h->nr_overcommit_huge_pages = tmp;
2088                spin_unlock(&hugetlb_lock);
2089        }
2090out:
2091        return ret;
2092}
2093
2094#endif /* CONFIG_SYSCTL */
2095
2096void hugetlb_report_meminfo(struct seq_file *m)
2097{
2098        struct hstate *h = &default_hstate;
2099        seq_printf(m,
2100                        "HugePages_Total:   %5lu\n"
2101                        "HugePages_Free:    %5lu\n"
2102                        "HugePages_Rsvd:    %5lu\n"
2103                        "HugePages_Surp:    %5lu\n"
2104                        "Hugepagesize:   %8lu kB\n",
2105                        h->nr_huge_pages,
2106                        h->free_huge_pages,
2107                        h->resv_huge_pages,
2108                        h->surplus_huge_pages,
2109                        1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2110}
2111
2112int hugetlb_report_node_meminfo(int nid, char *buf)
2113{
2114        struct hstate *h = &default_hstate;
2115        return sprintf(buf,
2116                "Node %d HugePages_Total: %5u\n"
2117                "Node %d HugePages_Free:  %5u\n"
2118                "Node %d HugePages_Surp:  %5u\n",
2119                nid, h->nr_huge_pages_node[nid],
2120                nid, h->free_huge_pages_node[nid],
2121                nid, h->surplus_huge_pages_node[nid]);
2122}
2123
2124/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2125unsigned long hugetlb_total_pages(void)
2126{
2127        struct hstate *h;
2128        unsigned long nr_total_pages = 0;
2129
2130        for_each_hstate(h)
2131                nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
2132        return nr_total_pages;
2133}
2134
2135static int hugetlb_acct_memory(struct hstate *h, long delta)
2136{
2137        int ret = -ENOMEM;
2138
2139        spin_lock(&hugetlb_lock);
2140        /*
2141         * When cpuset is configured, it breaks the strict hugetlb page
2142         * reservation as the accounting is done on a global variable. Such
2143         * reservation is completely rubbish in the presence of cpuset because
2144         * the reservation is not checked against page availability for the
2145         * current cpuset. Application can still potentially OOM'ed by kernel
2146         * with lack of free htlb page in cpuset that the task is in.
2147         * Attempt to enforce strict accounting with cpuset is almost
2148         * impossible (or too ugly) because cpuset is too fluid that
2149         * task or memory node can be dynamically moved between cpusets.
2150         *
2151         * The change of semantics for shared hugetlb mapping with cpuset is
2152         * undesirable. However, in order to preserve some of the semantics,
2153         * we fall back to check against current free page availability as
2154         * a best attempt and hopefully to minimize the impact of changing
2155         * semantics that cpuset has.
2156         */
2157        if (delta > 0) {
2158                if (gather_surplus_pages(h, delta) < 0)
2159                        goto out;
2160
2161                if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2162                        return_unused_surplus_pages(h, delta);
2163                        goto out;
2164                }
2165        }
2166
2167        ret = 0;
2168        if (delta < 0)
2169                return_unused_surplus_pages(h, (unsigned long) -delta);
2170
2171out:
2172        spin_unlock(&hugetlb_lock);
2173        return ret;
2174}
2175
2176static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2177{
2178        struct resv_map *reservations = vma_resv_map(vma);
2179
2180        /*
2181         * This new VMA should share its siblings reservation map if present.
2182         * The VMA will only ever have a valid reservation map pointer where
2183         * it is being copied for another still existing VMA.  As that VMA
2184         * has a reference to the reservation map it cannot disappear until
2185         * after this open call completes.  It is therefore safe to take a
2186         * new reference here without additional locking.
2187         */
2188        if (reservations)
2189                kref_get(&reservations->refs);
2190}
2191
2192static void resv_map_put(struct vm_area_struct *vma)
2193{
2194        struct resv_map *reservations = vma_resv_map(vma);
2195
2196        if (!reservations)
2197                return;
2198        kref_put(&reservations->refs, resv_map_release);
2199}
2200
2201static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2202{
2203        struct hstate *h = hstate_vma(vma);
2204        struct resv_map *reservations = vma_resv_map(vma);
2205        struct hugepage_subpool *spool = subpool_vma(vma);
2206        unsigned long reserve;
2207        unsigned long start;
2208        unsigned long end;
2209
2210        if (reservations) {
2211                start = vma_hugecache_offset(h, vma, vma->vm_start);
2212                end = vma_hugecache_offset(h, vma, vma->vm_end);
2213
2214                reserve = (end - start) -
2215                        region_count(&reservations->regions, start, end);
2216
2217                resv_map_put(vma);
2218
2219                if (reserve) {
2220                        hugetlb_acct_memory(h, -reserve);
2221                        hugepage_subpool_put_pages(spool, reserve);
2222                }
2223        }
2224}
2225
2226/*
2227 * We cannot handle pagefaults against hugetlb pages at all.  They cause
2228 * handle_mm_fault() to try to instantiate regular-sized pages in the
2229 * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2230 * this far.
2231 */
2232static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2233{
2234        BUG();
2235        return 0;
2236}
2237
2238const struct vm_operations_struct hugetlb_vm_ops = {
2239        .fault = hugetlb_vm_op_fault,
2240        .open = hugetlb_vm_op_open,
2241        .close = hugetlb_vm_op_close,
2242};
2243
2244static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2245                                int writable)
2246{
2247        pte_t entry;
2248
2249        if (writable) {
2250                entry =
2251                    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2252        } else {
2253                entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2254        }
2255        entry = pte_mkyoung(entry);
2256        entry = pte_mkhuge(entry);
2257        entry = arch_make_huge_pte(entry, vma, page, writable);
2258
2259        return entry;
2260}
2261
2262static void set_huge_ptep_writable(struct vm_area_struct *vma,
2263                                   unsigned long address, pte_t *ptep)
2264{
2265        pte_t entry;
2266
2267        entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2268        if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
2269                update_mmu_cache(vma, address, ptep);
2270}
2271
2272
2273int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2274                            struct vm_area_struct *vma)
2275{
2276        pte_t *src_pte, *dst_pte, entry;
2277        struct page *ptepage;
2278        unsigned long addr;
2279        int cow;
2280        struct hstate *h = hstate_vma(vma);
2281        unsigned long sz = huge_page_size(h);
2282
2283        cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2284
2285        for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2286                src_pte = huge_pte_offset(src, addr);
2287                if (!src_pte)
2288                        continue;
2289                dst_pte = huge_pte_alloc(dst, addr, sz);
2290                if (!dst_pte)
2291                        goto nomem;
2292
2293                /* If the pagetables are shared don't copy or take references */
2294                if (dst_pte == src_pte)
2295                        continue;
2296
2297                spin_lock(&dst->page_table_lock);
2298                spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2299                if (!huge_pte_none(huge_ptep_get(src_pte))) {
2300                        if (cow)
2301                                huge_ptep_set_wrprotect(src, addr, src_pte);
2302                        entry = huge_ptep_get(src_pte);
2303                        ptepage = pte_page(entry);
2304                        get_page(ptepage);
2305                        page_dup_rmap(ptepage);
2306                        set_huge_pte_at(dst, addr, dst_pte, entry);
2307                }
2308                spin_unlock(&src->page_table_lock);
2309                spin_unlock(&dst->page_table_lock);
2310        }
2311        return 0;
2312
2313nomem:
2314        return -ENOMEM;
2315}
2316
2317static int is_hugetlb_entry_migration(pte_t pte)
2318{
2319        swp_entry_t swp;
2320
2321        if (huge_pte_none(pte) || pte_present(pte))
2322                return 0;
2323        swp = pte_to_swp_entry(pte);
2324        if (non_swap_entry(swp) && is_migration_entry(swp))
2325                return 1;
2326        else
2327                return 0;
2328}
2329
2330static int is_hugetlb_entry_hwpoisoned(pte_t pte)
2331{
2332        swp_entry_t swp;
2333
2334        if (huge_pte_none(pte) || pte_present(pte))
2335                return 0;
2336        swp = pte_to_swp_entry(pte);
2337        if (non_swap_entry(swp) && is_hwpoison_entry(swp))
2338                return 1;
2339        else
2340                return 0;
2341}
2342
2343void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
2344                            unsigned long start, unsigned long end,
2345                            struct page *ref_page)
2346{
2347        int force_flush = 0;
2348        struct mm_struct *mm = vma->vm_mm;
2349        unsigned long address;
2350        pte_t *ptep;
2351        pte_t pte;
2352        struct page *page;
2353        struct hstate *h = hstate_vma(vma);
2354        unsigned long sz = huge_page_size(h);
2355        const unsigned long mmun_start = start; /* For mmu_notifiers */
2356        const unsigned long mmun_end   = end;   /* For mmu_notifiers */
2357
2358        WARN_ON(!is_vm_hugetlb_page(vma));
2359        BUG_ON(start & ~huge_page_mask(h));
2360        BUG_ON(end & ~huge_page_mask(h));
2361
2362        tlb_start_vma(tlb, vma);
2363        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2364again:
2365        spin_lock(&mm->page_table_lock);
2366        for (address = start; address < end; address += sz) {
2367                ptep = huge_pte_offset(mm, address);
2368                if (!ptep)
2369                        continue;
2370
2371                if (huge_pmd_unshare(mm, &address, ptep))
2372                        continue;
2373
2374                pte = huge_ptep_get(ptep);
2375                if (huge_pte_none(pte))
2376                        continue;
2377
2378                /*
2379                 * HWPoisoned hugepage is already unmapped and dropped reference
2380                 */
2381                if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
2382                        pte_clear(mm, address, ptep);
2383                        continue;
2384                }
2385
2386                page = pte_page(pte);
2387                /*
2388                 * If a reference page is supplied, it is because a specific
2389                 * page is being unmapped, not a range. Ensure the page we
2390                 * are about to unmap is the actual page of interest.
2391                 */
2392                if (ref_page) {
2393                        if (page != ref_page)
2394                                continue;
2395
2396                        /*
2397                         * Mark the VMA as having unmapped its page so that
2398                         * future faults in this VMA will fail rather than
2399                         * looking like data was lost
2400                         */
2401                        set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2402                }
2403
2404                pte = huge_ptep_get_and_clear(mm, address, ptep);
2405                tlb_remove_tlb_entry(tlb, ptep, address);
2406                if (pte_dirty(pte))
2407                        set_page_dirty(page);
2408
2409                page_remove_rmap(page);
2410                force_flush = !__tlb_remove_page(tlb, page);
2411                if (force_flush)
2412                        break;
2413                /* Bail out after unmapping reference page if supplied */
2414                if (ref_page)
2415                        break;
2416        }
2417        spin_unlock(&mm->page_table_lock);
2418        /*
2419         * mmu_gather ran out of room to batch pages, we break out of
2420         * the PTE lock to avoid doing the potential expensive TLB invalidate
2421         * and page-free while holding it.
2422         */
2423        if (force_flush) {
2424                force_flush = 0;
2425                tlb_flush_mmu(tlb);
2426                if (address < end && !ref_page)
2427                        goto again;
2428        }
2429        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2430        tlb_end_vma(tlb, vma);
2431}
2432
2433void __unmap_hugepage_range_final(struct mmu_gather *tlb,
2434                          struct vm_area_struct *vma, unsigned long start,
2435                          unsigned long end, struct page *ref_page)
2436{
2437        __unmap_hugepage_range(tlb, vma, start, end, ref_page);
2438
2439        /*
2440         * Clear this flag so that x86's huge_pmd_share page_table_shareable
2441         * test will fail on a vma being torn down, and not grab a page table
2442         * on its way out.  We're lucky that the flag has such an appropriate
2443         * name, and can in fact be safely cleared here. We could clear it
2444         * before the __unmap_hugepage_range above, but all that's necessary
2445         * is to clear it before releasing the i_mmap_mutex. This works
2446         * because in the context this is called, the VMA is about to be
2447         * destroyed and the i_mmap_mutex is held.
2448         */
2449        vma->vm_flags &= ~VM_MAYSHARE;
2450}
2451
2452void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2453                          unsigned long end, struct page *ref_page)
2454{
2455        struct mm_struct *mm;
2456        struct mmu_gather tlb;
2457
2458        mm = vma->vm_mm;
2459
2460        tlb_gather_mmu(&tlb, mm, 0);
2461        __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
2462        tlb_finish_mmu(&tlb, start, end);
2463}
2464
2465/*
2466 * This is called when the original mapper is failing to COW a MAP_PRIVATE
2467 * mappping it owns the reserve page for. The intention is to unmap the page
2468 * from other VMAs and let the children be SIGKILLed if they are faulting the
2469 * same region.
2470 */
2471static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2472                                struct page *page, unsigned long address)
2473{
2474        struct hstate *h = hstate_vma(vma);
2475        struct vm_area_struct *iter_vma;
2476        struct address_space *mapping;
2477        pgoff_t pgoff;
2478
2479        /*
2480         * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2481         * from page cache lookup which is in HPAGE_SIZE units.
2482         */
2483        address = address & huge_page_mask(h);
2484        pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
2485                        vma->vm_pgoff;
2486        mapping = file_inode(vma->vm_file)->i_mapping;
2487
2488        /*
2489         * Take the mapping lock for the duration of the table walk. As
2490         * this mapping should be shared between all the VMAs,
2491         * __unmap_hugepage_range() is called as the lock is already held
2492         */
2493        mutex_lock(&mapping->i_mmap_mutex);
2494        vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
2495                /* Do not unmap the current VMA */
2496                if (iter_vma == vma)
2497                        continue;
2498
2499                /*
2500                 * Unmap the page from other VMAs without their own reserves.
2501                 * They get marked to be SIGKILLed if they fault in these
2502                 * areas. This is because a future no-page fault on this VMA
2503                 * could insert a zeroed page instead of the data existing
2504                 * from the time of fork. This would look like data corruption
2505                 */
2506                if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2507                        unmap_hugepage_range(iter_vma, address,
2508                                             address + huge_page_size(h), page);
2509        }
2510        mutex_unlock(&mapping->i_mmap_mutex);
2511
2512        return 1;
2513}
2514
2515/*
2516 * Hugetlb_cow() should be called with page lock of the original hugepage held.
2517 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
2518 * cannot race with other handlers or page migration.
2519 * Keep the pte_same checks anyway to make transition from the mutex easier.
2520 */
2521static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2522                        unsigned long address, pte_t *ptep, pte_t pte,
2523                        struct page *pagecache_page)
2524{
2525        struct hstate *h = hstate_vma(vma);
2526        struct page *old_page, *new_page;
2527        int avoidcopy;
2528        int outside_reserve = 0;
2529        unsigned long mmun_start;       /* For mmu_notifiers */
2530        unsigned long mmun_end;         /* For mmu_notifiers */
2531
2532        old_page = pte_page(pte);
2533
2534retry_avoidcopy:
2535        /* If no-one else is actually using this page, avoid the copy
2536         * and just make the page writable */
2537        avoidcopy = (page_mapcount(old_page) == 1);
2538        if (avoidcopy) {
2539                if (PageAnon(old_page))
2540                        page_move_anon_rmap(old_page, vma, address);
2541                set_huge_ptep_writable(vma, address, ptep);
2542                return 0;
2543        }
2544
2545        /*
2546         * If the process that created a MAP_PRIVATE mapping is about to
2547         * perform a COW due to a shared page count, attempt to satisfy
2548         * the allocation without using the existing reserves. The pagecache
2549         * page is used to determine if the reserve at this address was
2550         * consumed or not. If reserves were used, a partial faulted mapping
2551         * at the time of fork() could consume its reserves on COW instead
2552         * of the full address range.
2553         */
2554        if (!(vma->vm_flags & VM_MAYSHARE) &&
2555                        is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2556                        old_page != pagecache_page)
2557                outside_reserve = 1;
2558
2559        page_cache_get(old_page);
2560
2561        /* Drop page_table_lock as buddy allocator may be called */
2562        spin_unlock(&mm->page_table_lock);
2563        new_page = alloc_huge_page(vma, address, outside_reserve);
2564
2565        if (IS_ERR(new_page)) {
2566                long err = PTR_ERR(new_page);
2567                page_cache_release(old_page);
2568
2569                /*
2570                 * If a process owning a MAP_PRIVATE mapping fails to COW,
2571                 * it is due to references held by a child and an insufficient
2572                 * huge page pool. To guarantee the original mappers
2573                 * reliability, unmap the page from child processes. The child
2574                 * may get SIGKILLed if it later faults.
2575                 */
2576                if (outside_reserve) {
2577                        BUG_ON(huge_pte_none(pte));
2578                        if (unmap_ref_private(mm, vma, old_page, address)) {
2579                                BUG_ON(huge_pte_none(pte));
2580                                spin_lock(&mm->page_table_lock);
2581                                ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2582                                if (likely(pte_same(huge_ptep_get(ptep), pte)))
2583                                        goto retry_avoidcopy;
2584                                /*
2585                                 * race occurs while re-acquiring page_table_lock, and
2586                                 * our job is done.
2587                                 */
2588                                return 0;
2589                        }
2590                        WARN_ON_ONCE(1);
2591                }
2592
2593                /* Caller expects lock to be held */
2594                spin_lock(&mm->page_table_lock);
2595                if (err == -ENOMEM)
2596                        return VM_FAULT_OOM;
2597                else
2598                        return VM_FAULT_SIGBUS;
2599        }
2600
2601        /*
2602         * When the original hugepage is shared one, it does not have
2603         * anon_vma prepared.
2604         */
2605        if (unlikely(anon_vma_prepare(vma))) {
2606                page_cache_release(new_page);
2607                page_cache_release(old_page);
2608                /* Caller expects lock to be held */
2609                spin_lock(&mm->page_table_lock);
2610                return VM_FAULT_OOM;
2611        }
2612
2613        copy_user_huge_page(new_page, old_page, address, vma,
2614                            pages_per_huge_page(h));
2615        __SetPageUptodate(new_page);
2616
2617        mmun_start = address & huge_page_mask(h);
2618        mmun_end = mmun_start + huge_page_size(h);
2619        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2620        /*
2621         * Retake the page_table_lock to check for racing updates
2622         * before the page tables are altered
2623         */
2624        spin_lock(&mm->page_table_lock);
2625        ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2626        if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2627                /* Break COW */
2628                huge_ptep_clear_flush(vma, address, ptep);
2629                set_huge_pte_at(mm, address, ptep,
2630                                make_huge_pte(vma, new_page, 1));
2631                page_remove_rmap(old_page);
2632                hugepage_add_new_anon_rmap(new_page, vma, address);
2633                /* Make the old page be freed below */
2634                new_page = old_page;
2635        }
2636        spin_unlock(&mm->page_table_lock);
2637        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2638        /* Caller expects lock to be held */
2639        spin_lock(&mm->page_table_lock);
2640        page_cache_release(new_page);
2641        page_cache_release(old_page);
2642        return 0;
2643}
2644
2645/* Return the pagecache page at a given address within a VMA */
2646static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2647                        struct vm_area_struct *vma, unsigned long address)
2648{
2649        struct address_space *mapping;
2650        pgoff_t idx;
2651
2652        mapping = vma->vm_file->f_mapping;
2653        idx = vma_hugecache_offset(h, vma, address);
2654
2655        return find_lock_page(mapping, idx);
2656}
2657
2658/*
2659 * Return whether there is a pagecache page to back given address within VMA.
2660 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2661 */
2662static bool hugetlbfs_pagecache_present(struct hstate *h,
2663                        struct vm_area_struct *vma, unsigned long address)
2664{
2665        struct address_space *mapping;
2666        pgoff_t idx;
2667        struct page *page;
2668
2669        mapping = vma->vm_file->f_mapping;
2670        idx = vma_hugecache_offset(h, vma, address);
2671
2672        page = find_get_page(mapping, idx);
2673        if (page)
2674                put_page(page);
2675        return page != NULL;
2676}
2677
2678static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2679                        unsigned long address, pte_t *ptep, unsigned int flags)
2680{
2681        struct hstate *h = hstate_vma(vma);
2682        int ret = VM_FAULT_SIGBUS;
2683        int anon_rmap = 0;
2684        pgoff_t idx;
2685        unsigned long size;
2686        struct page *page;
2687        struct address_space *mapping;
2688        pte_t new_pte;
2689
2690        /*
2691         * Currently, we are forced to kill the process in the event the
2692         * original mapper has unmapped pages from the child due to a failed
2693         * COW. Warn that such a situation has occurred as it may not be obvious
2694         */
2695        if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2696                pr_warning("PID %d killed due to inadequate hugepage pool\n",
2697                           current->pid);
2698                return ret;
2699        }
2700
2701        mapping = vma->vm_file->f_mapping;
2702        idx = vma_hugecache_offset(h, vma, address);
2703
2704        /*
2705         * Use page lock to guard against racing truncation
2706         * before we get page_table_lock.
2707         */
2708retry:
2709        page = find_lock_page(mapping, idx);
2710        if (!page) {
2711                size = i_size_read(mapping->host) >> huge_page_shift(h);
2712                if (idx >= size)
2713                        goto out;
2714                page = alloc_huge_page(vma, address, 0);
2715                if (IS_ERR(page)) {
2716                        ret = PTR_ERR(page);
2717                        if (ret == -ENOMEM)
2718                                ret = VM_FAULT_OOM;
2719                        else
2720                                ret = VM_FAULT_SIGBUS;
2721                        goto out;
2722                }
2723                clear_huge_page(page, address, pages_per_huge_page(h));
2724                __SetPageUptodate(page);
2725
2726                if (vma->vm_flags & VM_MAYSHARE) {
2727                        int err;
2728                        struct inode *inode = mapping->host;
2729
2730                        err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2731                        if (err) {
2732                                put_page(page);
2733                                if (err == -EEXIST)
2734                                        goto retry;
2735                                goto out;
2736                        }
2737
2738                        spin_lock(&inode->i_lock);
2739                        inode->i_blocks += blocks_per_huge_page(h);
2740                        spin_unlock(&inode->i_lock);
2741                } else {
2742                        lock_page(page);
2743                        if (unlikely(anon_vma_prepare(vma))) {
2744                                ret = VM_FAULT_OOM;
2745                                goto backout_unlocked;
2746                        }
2747                        anon_rmap = 1;
2748                }
2749        } else {
2750                /*
2751                 * If memory error occurs between mmap() and fault, some process
2752                 * don't have hwpoisoned swap entry for errored virtual address.
2753                 * So we need to block hugepage fault by PG_hwpoison bit check.
2754                 */
2755                if (unlikely(PageHWPoison(page))) {
2756                        ret = VM_FAULT_HWPOISON |
2757                                VM_FAULT_SET_HINDEX(hstate_index(h));
2758                        goto backout_unlocked;
2759                }
2760        }
2761
2762        /*
2763         * If we are going to COW a private mapping later, we examine the
2764         * pending reservations for this page now. This will ensure that
2765         * any allocations necessary to record that reservation occur outside
2766         * the spinlock.
2767         */
2768        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2769                if (vma_needs_reservation(h, vma, address) < 0) {
2770                        ret = VM_FAULT_OOM;
2771                        goto backout_unlocked;
2772                }
2773
2774        spin_lock(&mm->page_table_lock);
2775        size = i_size_read(mapping->host) >> huge_page_shift(h);
2776        if (idx >= size)
2777                goto backout;
2778
2779        ret = 0;
2780        if (!huge_pte_none(huge_ptep_get(ptep)))
2781                goto backout;
2782
2783        if (anon_rmap)
2784                hugepage_add_new_anon_rmap(page, vma, address);
2785        else
2786                page_dup_rmap(page);
2787        new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2788                                && (vma->vm_flags & VM_SHARED)));
2789        set_huge_pte_at(mm, address, ptep, new_pte);
2790
2791        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2792                /* Optimization, do the COW without a second fault */
2793                ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2794        }
2795
2796        spin_unlock(&mm->page_table_lock);
2797        unlock_page(page);
2798out:
2799        return ret;
2800
2801backout:
2802        spin_unlock(&mm->page_table_lock);
2803backout_unlocked:
2804        unlock_page(page);
2805        put_page(page);
2806        goto out;
2807}
2808
2809int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2810                        unsigned long address, unsigned int flags)
2811{
2812        pte_t *ptep;
2813        pte_t entry;
2814        int ret;
2815        struct page *page = NULL;
2816        struct page *pagecache_page = NULL;
2817        static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2818        struct hstate *h = hstate_vma(vma);
2819
2820        address &= huge_page_mask(h);
2821
2822        ptep = huge_pte_offset(mm, address);
2823        if (ptep) {
2824                entry = huge_ptep_get(ptep);
2825                if (unlikely(is_hugetlb_entry_migration(entry))) {
2826                        migration_entry_wait(mm, (pmd_t *)ptep, address);
2827                        return 0;
2828                } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
2829                        return VM_FAULT_HWPOISON_LARGE |
2830                                VM_FAULT_SET_HINDEX(hstate_index(h));
2831        }
2832
2833        ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2834        if (!ptep)
2835                return VM_FAULT_OOM;
2836
2837        /*
2838         * Serialize hugepage allocation and instantiation, so that we don't
2839         * get spurious allocation failures if two CPUs race to instantiate
2840         * the same page in the page cache.
2841         */
2842        mutex_lock(&hugetlb_instantiation_mutex);
2843        entry = huge_ptep_get(ptep);
2844        if (huge_pte_none(entry)) {
2845                ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2846                goto out_mutex;
2847        }
2848
2849        ret = 0;
2850
2851        /*
2852         * If we are going to COW the mapping later, we examine the pending
2853         * reservations for this page now. This will ensure that any
2854         * allocations necessary to record that reservation occur outside the
2855         * spinlock. For private mappings, we also lookup the pagecache
2856         * page now as it is used to determine if a reservation has been
2857         * consumed.
2858         */
2859        if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2860                if (vma_needs_reservation(h, vma, address) < 0) {
2861                        ret = VM_FAULT_OOM;
2862                        goto out_mutex;
2863                }
2864
2865                if (!(vma->vm_flags & VM_MAYSHARE))
2866                        pagecache_page = hugetlbfs_pagecache_page(h,
2867                                                                vma, address);
2868        }
2869
2870        /*
2871         * hugetlb_cow() requires page locks of pte_page(entry) and
2872         * pagecache_page, so here we need take the former one
2873         * when page != pagecache_page or !pagecache_page.
2874         * Note that locking order is always pagecache_page -> page,
2875         * so no worry about deadlock.
2876         */
2877        page = pte_page(entry);
2878        get_page(page);
2879        if (page != pagecache_page)
2880                lock_page(page);
2881
2882        spin_lock(&mm->page_table_lock);
2883        /* Check for a racing update before calling hugetlb_cow */
2884        if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2885                goto out_page_table_lock;
2886
2887
2888        if (flags & FAULT_FLAG_WRITE) {
2889                if (!pte_write(entry)) {
2890                        ret = hugetlb_cow(mm, vma, address, ptep, entry,
2891                                                        pagecache_page);
2892                        goto out_page_table_lock;
2893                }
2894                entry = pte_mkdirty(entry);
2895        }
2896        entry = pte_mkyoung(entry);
2897        if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2898                                                flags & FAULT_FLAG_WRITE))
2899                update_mmu_cache(vma, address, ptep);
2900
2901out_page_table_lock:
2902        spin_unlock(&mm->page_table_lock);
2903
2904        if (pagecache_page) {
2905                unlock_page(pagecache_page);
2906                put_page(pagecache_page);
2907        }
2908        if (page != pagecache_page)
2909                unlock_page(page);
2910        put_page(page);
2911
2912out_mutex:
2913        mutex_unlock(&hugetlb_instantiation_mutex);
2914
2915        return ret;
2916}
2917
2918/* Can be overriden by architectures */
2919__attribute__((weak)) struct page *
2920follow_huge_pud(struct mm_struct *mm, unsigned long address,
2921               pud_t *pud, int write)
2922{
2923        BUG();
2924        return NULL;
2925}
2926
2927long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2928                         struct page **pages, struct vm_area_struct **vmas,
2929                         unsigned long *position, unsigned long *nr_pages,
2930                         long i, unsigned int flags)
2931{
2932        unsigned long pfn_offset;
2933        unsigned long vaddr = *position;
2934        unsigned long remainder = *nr_pages;
2935        struct hstate *h = hstate_vma(vma);
2936
2937        spin_lock(&mm->page_table_lock);
2938        while (vaddr < vma->vm_end && remainder) {
2939                pte_t *pte;
2940                int absent;
2941                struct page *page;
2942
2943                /*
2944                 * Some archs (sparc64, sh*) have multiple pte_ts to
2945                 * each hugepage.  We have to make sure we get the
2946                 * first, for the page indexing below to work.
2947                 */
2948                pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2949                absent = !pte || huge_pte_none(huge_ptep_get(pte));
2950
2951                /*
2952                 * When coredumping, it suits get_dump_page if we just return
2953                 * an error where there's an empty slot with no huge pagecache
2954                 * to back it.  This way, we avoid allocating a hugepage, and
2955                 * the sparse dumpfile avoids allocating disk blocks, but its
2956                 * huge holes still show up with zeroes where they need to be.
2957                 */
2958                if (absent && (flags & FOLL_DUMP) &&
2959                    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2960                        remainder = 0;
2961                        break;
2962                }
2963
2964                /*
2965                 * We need call hugetlb_fault for both hugepages under migration
2966                 * (in which case hugetlb_fault waits for the migration,) and
2967                 * hwpoisoned hugepages (in which case we need to prevent the
2968                 * caller from accessing to them.) In order to do this, we use
2969                 * here is_swap_pte instead of is_hugetlb_entry_migration and
2970                 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
2971                 * both cases, and because we can't follow correct pages
2972                 * directly from any kind of swap entries.
2973                 */
2974                if (absent || is_swap_pte(huge_ptep_get(pte)) ||
2975                    ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2976                        int ret;
2977
2978                        spin_unlock(&mm->page_table_lock);
2979                        ret = hugetlb_fault(mm, vma, vaddr,
2980                                (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2981                        spin_lock(&mm->page_table_lock);
2982                        if (!(ret & VM_FAULT_ERROR))
2983                                continue;
2984
2985                        remainder = 0;
2986                        break;
2987                }
2988
2989                pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2990                page = pte_page(huge_ptep_get(pte));
2991same_page:
2992                if (pages) {
2993                        pages[i] = mem_map_offset(page, pfn_offset);
2994                        get_page(pages[i]);
2995                }
2996
2997                if (vmas)
2998                        vmas[i] = vma;
2999
3000                vaddr += PAGE_SIZE;
3001                ++pfn_offset;
3002                --remainder;
3003                ++i;
3004                if (vaddr < vma->vm_end && remainder &&
3005                                pfn_offset < pages_per_huge_page(h)) {
3006                        /*
3007                         * We use pfn_offset to avoid touching the pageframes
3008                         * of this compound page.
3009                         */
3010                        goto same_page;
3011                }
3012        }
3013        spin_unlock(&mm->page_table_lock);
3014        *nr_pages = remainder;
3015        *position = vaddr;
3016
3017        return i ? i : -EFAULT;
3018}
3019
3020unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3021                unsigned long address, unsigned long end, pgprot_t newprot)
3022{
3023        struct mm_struct *mm = vma->vm_mm;
3024        unsigned long start = address;
3025        pte_t *ptep;
3026        pte_t pte;
3027        struct hstate *h = hstate_vma(vma);
3028        unsigned long pages = 0;
3029
3030        BUG_ON(address >= end);
3031        flush_cache_range(vma, address, end);
3032
3033        mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
3034        spin_lock(&mm->page_table_lock);
3035        for (; address < end; address += huge_page_size(h)) {
3036                ptep = huge_pte_offset(mm, address);
3037                if (!ptep)
3038                        continue;
3039                if (huge_pmd_unshare(mm, &address, ptep)) {
3040                        pages++;
3041                        continue;
3042                }
3043                if (!huge_pte_none(huge_ptep_get(ptep))) {
3044                        pte = huge_ptep_get_and_clear(mm, address, ptep);
3045                        pte = pte_mkhuge(pte_modify(pte, newprot));
3046                        pte = arch_make_huge_pte(pte, vma, NULL, 0);
3047                        set_huge_pte_at(mm, address, ptep, pte);
3048                        pages++;
3049                }
3050        }
3051        spin_unlock(&mm->page_table_lock);
3052        /*
3053         * Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare
3054         * may have cleared our pud entry and done put_page on the page table:
3055         * once we release i_mmap_mutex, another task can do the final put_page
3056         * and that page table be reused and filled with junk.
3057         */
3058        flush_tlb_range(vma, start, end);
3059        mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
3060
3061        return pages << h->order;
3062}
3063
3064int hugetlb_reserve_pages(struct inode *inode,
3065                                        long from, long to,
3066                                        struct vm_area_struct *vma,
3067                                        vm_flags_t vm_flags)
3068{
3069        long ret, chg;
3070        struct hstate *h = hstate_inode(inode);
3071        struct hugepage_subpool *spool = subpool_inode(inode);
3072
3073        /*
3074         * Only apply hugepage reservation if asked. At fault time, an
3075         * attempt will be made for VM_NORESERVE to allocate a page
3076         * without using reserves
3077         */
3078        if (vm_flags & VM_NORESERVE)
3079                return 0;
3080
3081        /*
3082         * Shared mappings base their reservation on the number of pages that
3083         * are already allocated on behalf of the file. Private mappings need
3084         * to reserve the full area even if read-only as mprotect() may be
3085         * called to make the mapping read-write. Assume !vma is a shm mapping
3086         */
3087        if (!vma || vma->vm_flags & VM_MAYSHARE)
3088                chg = region_chg(&inode->i_mapping->private_list, from, to);
3089        else {
3090                struct resv_map *resv_map = resv_map_alloc();
3091                if (!resv_map)
3092                        return -ENOMEM;
3093
3094                chg = to - from;
3095
3096                set_vma_resv_map(vma, resv_map);
3097                set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
3098        }
3099
3100        if (chg < 0) {
3101                ret = chg;
3102                goto out_err;
3103        }
3104
3105        /* There must be enough pages in the subpool for the mapping */
3106        if (hugepage_subpool_get_pages(spool, chg)) {
3107                ret = -ENOSPC;
3108                goto out_err;
3109        }
3110
3111        /*
3112         * Check enough hugepages are available for the reservation.
3113         * Hand the pages back to the subpool if there are not
3114         */
3115        ret = hugetlb_acct_memory(h, chg);
3116        if (ret < 0) {
3117                hugepage_subpool_put_pages(spool, chg);
3118                goto out_err;
3119        }
3120
3121        /*
3122         * Account for the reservations made. Shared mappings record regions
3123         * that have reservations as they are shared by multiple VMAs.
3124         * When the last VMA disappears, the region map says how much
3125         * the reservation was and the page cache tells how much of
3126         * the reservation was consumed. Private mappings are per-VMA and
3127         * only the consumed reservations are tracked. When the VMA
3128         * disappears, the original reservation is the VMA size and the
3129         * consumed reservations are stored in the map. Hence, nothing
3130         * else has to be done for private mappings here
3131         */
3132        if (!vma || vma->vm_flags & VM_MAYSHARE)
3133                region_add(&inode->i_mapping->private_list, from, to);
3134        return 0;
3135out_err:
3136        if (vma)
3137                resv_map_put(vma);
3138        return ret;
3139}
3140
3141void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
3142{
3143        struct hstate *h = hstate_inode(inode);
3144        long chg = region_truncate(&inode->i_mapping->private_list, offset);
3145        struct hugepage_subpool *spool = subpool_inode(inode);
3146
3147        spin_lock(&inode->i_lock);
3148        inode->i_blocks -= (blocks_per_huge_page(h) * freed);
3149        spin_unlock(&inode->i_lock);
3150
3151        hugepage_subpool_put_pages(spool, (chg - freed));
3152        hugetlb_acct_memory(h, -(chg - freed));
3153}
3154
3155#ifdef CONFIG_MEMORY_FAILURE
3156
3157/* Should be called in hugetlb_lock */
3158static int is_hugepage_on_freelist(struct page *hpage)
3159{
3160        struct page *page;
3161        struct page *tmp;
3162        struct hstate *h = page_hstate(hpage);
3163        int nid = page_to_nid(hpage);
3164
3165        list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
3166                if (page == hpage)
3167                        return 1;
3168        return 0;
3169}
3170
3171/*
3172 * This function is called from memory failure code.
3173 * Assume the caller holds page lock of the head page.
3174 */
3175int dequeue_hwpoisoned_huge_page(struct page *hpage)
3176{
3177        struct hstate *h = page_hstate(hpage);
3178        int nid = page_to_nid(hpage);
3179        int ret = -EBUSY;
3180
3181        spin_lock(&hugetlb_lock);
3182        if (is_hugepage_on_freelist(hpage)) {
3183                /*
3184                 * Hwpoisoned hugepage isn't linked to activelist or freelist,
3185                 * but dangling hpage->lru can trigger list-debug warnings
3186                 * (this happens when we call unpoison_memory() on it),
3187                 * so let it point to itself with list_del_init().
3188                 */
3189                list_del_init(&hpage->lru);
3190                set_page_refcounted(hpage);
3191                h->free_huge_pages--;
3192                h->free_huge_pages_node[nid]--;
3193                ret = 0;
3194        }
3195        spin_unlock(&hugetlb_lock);
3196        return ret;
3197}
3198#endif
3199
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.