linux/mm/hugetlb.c
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   1/*
   2 * Generic hugetlb support.
   3 * (C) Nadia Yvette Chambers, April 2004
   4 */
   5#include <linux/list.h>
   6#include <linux/init.h>
   7#include <linux/module.h>
   8#include <linux/mm.h>
   9#include <linux/seq_file.h>
  10#include <linux/sysctl.h>
  11#include <linux/highmem.h>
  12#include <linux/mmu_notifier.h>
  13#include <linux/nodemask.h>
  14#include <linux/pagemap.h>
  15#include <linux/mempolicy.h>
  16#include <linux/cpuset.h>
  17#include <linux/mutex.h>
  18#include <linux/bootmem.h>
  19#include <linux/sysfs.h>
  20#include <linux/slab.h>
  21#include <linux/rmap.h>
  22#include <linux/swap.h>
  23#include <linux/swapops.h>
  24
  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(vma->vm_file->f_dentry->d_inode);
 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                printk(KERN_INFO "HugeTLB registered %s page size, "
1297                                 "pre-allocated %ld pages\n",
1298                        memfmt(buf, huge_page_size(h)),
1299                        h->free_huge_pages);
1300        }
1301}
1302
1303#ifdef CONFIG_HIGHMEM
1304static void try_to_free_low(struct hstate *h, unsigned long count,
1305                                                nodemask_t *nodes_allowed)
1306{
1307        int i;
1308
1309        if (h->order >= MAX_ORDER)
1310                return;
1311
1312        for_each_node_mask(i, *nodes_allowed) {
1313                struct page *page, *next;
1314                struct list_head *freel = &h->hugepage_freelists[i];
1315                list_for_each_entry_safe(page, next, freel, lru) {
1316                        if (count >= h->nr_huge_pages)
1317                                return;
1318                        if (PageHighMem(page))
1319                                continue;
1320                        list_del(&page->lru);
1321                        update_and_free_page(h, page);
1322                        h->free_huge_pages--;
1323                        h->free_huge_pages_node[page_to_nid(page)]--;
1324                }
1325        }
1326}
1327#else
1328static inline void try_to_free_low(struct hstate *h, unsigned long count,
1329                                                nodemask_t *nodes_allowed)
1330{
1331}
1332#endif
1333
1334/*
1335 * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1336 * balanced by operating on them in a round-robin fashion.
1337 * Returns 1 if an adjustment was made.
1338 */
1339static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1340                                int delta)
1341{
1342        int start_nid, next_nid;
1343        int ret = 0;
1344
1345        VM_BUG_ON(delta != -1 && delta != 1);
1346
1347        if (delta < 0)
1348                start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1349        else
1350                start_nid = hstate_next_node_to_free(h, nodes_allowed);
1351        next_nid = start_nid;
1352
1353        do {
1354                int nid = next_nid;
1355                if (delta < 0)  {
1356                        /*
1357                         * To shrink on this node, there must be a surplus page
1358                         */
1359                        if (!h->surplus_huge_pages_node[nid]) {
1360                                next_nid = hstate_next_node_to_alloc(h,
1361                                                                nodes_allowed);
1362                                continue;
1363                        }
1364                }
1365                if (delta > 0) {
1366                        /*
1367                         * Surplus cannot exceed the total number of pages
1368                         */
1369                        if (h->surplus_huge_pages_node[nid] >=
1370                                                h->nr_huge_pages_node[nid]) {
1371                                next_nid = hstate_next_node_to_free(h,
1372                                                                nodes_allowed);
1373                                continue;
1374                        }
1375                }
1376
1377                h->surplus_huge_pages += delta;
1378                h->surplus_huge_pages_node[nid] += delta;
1379                ret = 1;
1380                break;
1381        } while (next_nid != start_nid);
1382
1383        return ret;
1384}
1385
1386#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1387static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1388                                                nodemask_t *nodes_allowed)
1389{
1390        unsigned long min_count, ret;
1391
1392        if (h->order >= MAX_ORDER)
1393                return h->max_huge_pages;
1394
1395        /*
1396         * Increase the pool size
1397         * First take pages out of surplus state.  Then make up the
1398         * remaining difference by allocating fresh huge pages.
1399         *
1400         * We might race with alloc_buddy_huge_page() here and be unable
1401         * to convert a surplus huge page to a normal huge page. That is
1402         * not critical, though, it just means the overall size of the
1403         * pool might be one hugepage larger than it needs to be, but
1404         * within all the constraints specified by the sysctls.
1405         */
1406        spin_lock(&hugetlb_lock);
1407        while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1408                if (!adjust_pool_surplus(h, nodes_allowed, -1))
1409                        break;
1410        }
1411
1412        while (count > persistent_huge_pages(h)) {
1413                /*
1414                 * If this allocation races such that we no longer need the
1415                 * page, free_huge_page will handle it by freeing the page
1416                 * and reducing the surplus.
1417                 */
1418                spin_unlock(&hugetlb_lock);
1419                ret = alloc_fresh_huge_page(h, nodes_allowed);
1420                spin_lock(&hugetlb_lock);
1421                if (!ret)
1422                        goto out;
1423
1424                /* Bail for signals. Probably ctrl-c from user */
1425                if (signal_pending(current))
1426                        goto out;
1427        }
1428
1429        /*
1430         * Decrease the pool size
1431         * First return free pages to the buddy allocator (being careful
1432         * to keep enough around to satisfy reservations).  Then place
1433         * pages into surplus state as needed so the pool will shrink
1434         * to the desired size as pages become free.
1435         *
1436         * By placing pages into the surplus state independent of the
1437         * overcommit value, we are allowing the surplus pool size to
1438         * exceed overcommit. There are few sane options here. Since
1439         * alloc_buddy_huge_page() is checking the global counter,
1440         * though, we'll note that we're not allowed to exceed surplus
1441         * and won't grow the pool anywhere else. Not until one of the
1442         * sysctls are changed, or the surplus pages go out of use.
1443         */
1444        min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1445        min_count = max(count, min_count);
1446        try_to_free_low(h, min_count, nodes_allowed);
1447        while (min_count < persistent_huge_pages(h)) {
1448                if (!free_pool_huge_page(h, nodes_allowed, 0))
1449                        break;
1450        }
1451        while (count < persistent_huge_pages(h)) {
1452                if (!adjust_pool_surplus(h, nodes_allowed, 1))
1453                        break;
1454        }
1455out:
1456        ret = persistent_huge_pages(h);
1457        spin_unlock(&hugetlb_lock);
1458        return ret;
1459}
1460
1461#define HSTATE_ATTR_RO(_name) \
1462        static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1463
1464#define HSTATE_ATTR(_name) \
1465        static struct kobj_attribute _name##_attr = \
1466                __ATTR(_name, 0644, _name##_show, _name##_store)
1467
1468static struct kobject *hugepages_kobj;
1469static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1470
1471static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1472
1473static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1474{
1475        int i;
1476
1477        for (i = 0; i < HUGE_MAX_HSTATE; i++)
1478                if (hstate_kobjs[i] == kobj) {
1479                        if (nidp)
1480                                *nidp = NUMA_NO_NODE;
1481                        return &hstates[i];
1482                }
1483
1484        return kobj_to_node_hstate(kobj, nidp);
1485}
1486
1487static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1488                                        struct kobj_attribute *attr, char *buf)
1489{
1490        struct hstate *h;
1491        unsigned long nr_huge_pages;
1492        int nid;
1493
1494        h = kobj_to_hstate(kobj, &nid);
1495        if (nid == NUMA_NO_NODE)
1496                nr_huge_pages = h->nr_huge_pages;
1497        else
1498                nr_huge_pages = h->nr_huge_pages_node[nid];
1499
1500        return sprintf(buf, "%lu\n", nr_huge_pages);
1501}
1502
1503static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1504                        struct kobject *kobj, struct kobj_attribute *attr,
1505                        const char *buf, size_t len)
1506{
1507        int err;
1508        int nid;
1509        unsigned long count;
1510        struct hstate *h;
1511        NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1512
1513        err = strict_strtoul(buf, 10, &count);
1514        if (err)
1515                goto out;
1516
1517        h = kobj_to_hstate(kobj, &nid);
1518        if (h->order >= MAX_ORDER) {
1519                err = -EINVAL;
1520                goto out;
1521        }
1522
1523        if (nid == NUMA_NO_NODE) {
1524                /*
1525                 * global hstate attribute
1526                 */
1527                if (!(obey_mempolicy &&
1528                                init_nodemask_of_mempolicy(nodes_allowed))) {
1529                        NODEMASK_FREE(nodes_allowed);
1530                        nodes_allowed = &node_states[N_MEMORY];
1531                }
1532        } else if (nodes_allowed) {
1533                /*
1534                 * per node hstate attribute: adjust count to global,
1535                 * but restrict alloc/free to the specified node.
1536                 */
1537                count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1538                init_nodemask_of_node(nodes_allowed, nid);
1539        } else
1540                nodes_allowed = &node_states[N_MEMORY];
1541
1542        h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1543
1544        if (nodes_allowed != &node_states[N_MEMORY])
1545                NODEMASK_FREE(nodes_allowed);
1546
1547        return len;
1548out:
1549        NODEMASK_FREE(nodes_allowed);
1550        return err;
1551}
1552
1553static ssize_t nr_hugepages_show(struct kobject *kobj,
1554                                       struct kobj_attribute *attr, char *buf)
1555{
1556        return nr_hugepages_show_common(kobj, attr, buf);
1557}
1558
1559static ssize_t nr_hugepages_store(struct kobject *kobj,
1560               struct kobj_attribute *attr, const char *buf, size_t len)
1561{
1562        return nr_hugepages_store_common(false, kobj, attr, buf, len);
1563}
1564HSTATE_ATTR(nr_hugepages);
1565
1566#ifdef CONFIG_NUMA
1567
1568/*
1569 * hstate attribute for optionally mempolicy-based constraint on persistent
1570 * huge page alloc/free.
1571 */
1572static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1573                                       struct kobj_attribute *attr, char *buf)
1574{
1575        return nr_hugepages_show_common(kobj, attr, buf);
1576}
1577
1578static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1579               struct kobj_attribute *attr, const char *buf, size_t len)
1580{
1581        return nr_hugepages_store_common(true, kobj, attr, buf, len);
1582}
1583HSTATE_ATTR(nr_hugepages_mempolicy);
1584#endif
1585
1586
1587static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1588                                        struct kobj_attribute *attr, char *buf)
1589{
1590        struct hstate *h = kobj_to_hstate(kobj, NULL);
1591        return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1592}
1593
1594static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1595                struct kobj_attribute *attr, const char *buf, size_t count)
1596{
1597        int err;
1598        unsigned long input;
1599        struct hstate *h = kobj_to_hstate(kobj, NULL);
1600
1601        if (h->order >= MAX_ORDER)
1602                return -EINVAL;
1603
1604        err = strict_strtoul(buf, 10, &input);
1605        if (err)
1606                return err;
1607
1608        spin_lock(&hugetlb_lock);
1609        h->nr_overcommit_huge_pages = input;
1610        spin_unlock(&hugetlb_lock);
1611
1612        return count;
1613}
1614HSTATE_ATTR(nr_overcommit_hugepages);
1615
1616static ssize_t free_hugepages_show(struct kobject *kobj,
1617                                        struct kobj_attribute *attr, char *buf)
1618{
1619        struct hstate *h;
1620        unsigned long free_huge_pages;
1621        int nid;
1622
1623        h = kobj_to_hstate(kobj, &nid);
1624        if (nid == NUMA_NO_NODE)
1625                free_huge_pages = h->free_huge_pages;
1626        else
1627                free_huge_pages = h->free_huge_pages_node[nid];
1628
1629        return sprintf(buf, "%lu\n", free_huge_pages);
1630}
1631HSTATE_ATTR_RO(free_hugepages);
1632
1633static ssize_t resv_hugepages_show(struct kobject *kobj,
1634                                        struct kobj_attribute *attr, char *buf)
1635{
1636        struct hstate *h = kobj_to_hstate(kobj, NULL);
1637        return sprintf(buf, "%lu\n", h->resv_huge_pages);
1638}
1639HSTATE_ATTR_RO(resv_hugepages);
1640
1641static ssize_t surplus_hugepages_show(struct kobject *kobj,
1642                                        struct kobj_attribute *attr, char *buf)
1643{
1644        struct hstate *h;
1645        unsigned long surplus_huge_pages;
1646        int nid;
1647
1648        h = kobj_to_hstate(kobj, &nid);
1649        if (nid == NUMA_NO_NODE)
1650                surplus_huge_pages = h->surplus_huge_pages;
1651        else
1652                surplus_huge_pages = h->surplus_huge_pages_node[nid];
1653
1654        return sprintf(buf, "%lu\n", surplus_huge_pages);
1655}
1656HSTATE_ATTR_RO(surplus_hugepages);
1657
1658static struct attribute *hstate_attrs[] = {
1659        &nr_hugepages_attr.attr,
1660        &nr_overcommit_hugepages_attr.attr,
1661        &free_hugepages_attr.attr,
1662        &resv_hugepages_attr.attr,
1663        &surplus_hugepages_attr.attr,
1664#ifdef CONFIG_NUMA
1665        &nr_hugepages_mempolicy_attr.attr,
1666#endif
1667        NULL,
1668};
1669
1670static struct attribute_group hstate_attr_group = {
1671        .attrs = hstate_attrs,
1672};
1673
1674static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1675                                    struct kobject **hstate_kobjs,
1676                                    struct attribute_group *hstate_attr_group)
1677{
1678        int retval;
1679        int hi = hstate_index(h);
1680
1681        hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1682        if (!hstate_kobjs[hi])
1683                return -ENOMEM;
1684
1685        retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1686        if (retval)
1687                kobject_put(hstate_kobjs[hi]);
1688
1689        return retval;
1690}
1691
1692static void __init hugetlb_sysfs_init(void)
1693{
1694        struct hstate *h;
1695        int err;
1696
1697        hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1698        if (!hugepages_kobj)
1699                return;
1700
1701        for_each_hstate(h) {
1702                err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1703                                         hstate_kobjs, &hstate_attr_group);
1704                if (err)
1705                        printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1706                                                                h->name);
1707        }
1708}
1709
1710#ifdef CONFIG_NUMA
1711
1712/*
1713 * node_hstate/s - associate per node hstate attributes, via their kobjects,
1714 * with node devices in node_devices[] using a parallel array.  The array
1715 * index of a node device or _hstate == node id.
1716 * This is here to avoid any static dependency of the node device driver, in
1717 * the base kernel, on the hugetlb module.
1718 */
1719struct node_hstate {
1720        struct kobject          *hugepages_kobj;
1721        struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1722};
1723struct node_hstate node_hstates[MAX_NUMNODES];
1724
1725/*
1726 * A subset of global hstate attributes for node devices
1727 */
1728static struct attribute *per_node_hstate_attrs[] = {
1729        &nr_hugepages_attr.attr,
1730        &free_hugepages_attr.attr,
1731        &surplus_hugepages_attr.attr,
1732        NULL,
1733};
1734
1735static struct attribute_group per_node_hstate_attr_group = {
1736        .attrs = per_node_hstate_attrs,
1737};
1738
1739/*
1740 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
1741 * Returns node id via non-NULL nidp.
1742 */
1743static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1744{
1745        int nid;
1746
1747        for (nid = 0; nid < nr_node_ids; nid++) {
1748                struct node_hstate *nhs = &node_hstates[nid];
1749                int i;
1750                for (i = 0; i < HUGE_MAX_HSTATE; i++)
1751                        if (nhs->hstate_kobjs[i] == kobj) {
1752                                if (nidp)
1753                                        *nidp = nid;
1754                                return &hstates[i];
1755                        }
1756        }
1757
1758        BUG();
1759        return NULL;
1760}
1761
1762/*
1763 * Unregister hstate attributes from a single node device.
1764 * No-op if no hstate attributes attached.
1765 */
1766void hugetlb_unregister_node(struct node *node)
1767{
1768        struct hstate *h;
1769        struct node_hstate *nhs = &node_hstates[node->dev.id];
1770
1771        if (!nhs->hugepages_kobj)
1772                return;         /* no hstate attributes */
1773
1774        for_each_hstate(h) {
1775                int idx = hstate_index(h);
1776                if (nhs->hstate_kobjs[idx]) {
1777                        kobject_put(nhs->hstate_kobjs[idx]);
1778                        nhs->hstate_kobjs[idx] = NULL;
1779                }
1780        }
1781
1782        kobject_put(nhs->hugepages_kobj);
1783        nhs->hugepages_kobj = NULL;
1784}
1785
1786/*
1787 * hugetlb module exit:  unregister hstate attributes from node devices
1788 * that have them.
1789 */
1790static void hugetlb_unregister_all_nodes(void)
1791{
1792        int nid;
1793
1794        /*
1795         * disable node device registrations.
1796         */
1797        register_hugetlbfs_with_node(NULL, NULL);
1798
1799        /*
1800         * remove hstate attributes from any nodes that have them.
1801         */
1802        for (nid = 0; nid < nr_node_ids; nid++)
1803                hugetlb_unregister_node(node_devices[nid]);
1804}
1805
1806/*
1807 * Register hstate attributes for a single node device.
1808 * No-op if attributes already registered.
1809 */
1810void hugetlb_register_node(struct node *node)
1811{
1812        struct hstate *h;
1813        struct node_hstate *nhs = &node_hstates[node->dev.id];
1814        int err;
1815
1816        if (nhs->hugepages_kobj)
1817                return;         /* already allocated */
1818
1819        nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1820                                                        &node->dev.kobj);
1821        if (!nhs->hugepages_kobj)
1822                return;
1823
1824        for_each_hstate(h) {
1825                err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1826                                                nhs->hstate_kobjs,
1827                                                &per_node_hstate_attr_group);
1828                if (err) {
1829                        printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1830                                        " for node %d\n",
1831                                                h->name, node->dev.id);
1832                        hugetlb_unregister_node(node);
1833                        break;
1834                }
1835        }
1836}
1837
1838/*
1839 * hugetlb init time:  register hstate attributes for all registered node
1840 * devices of nodes that have memory.  All on-line nodes should have
1841 * registered their associated device by this time.
1842 */
1843static void hugetlb_register_all_nodes(void)
1844{
1845        int nid;
1846
1847        for_each_node_state(nid, N_MEMORY) {
1848                struct node *node = node_devices[nid];
1849                if (node->dev.id == nid)
1850                        hugetlb_register_node(node);
1851        }
1852
1853        /*
1854         * Let the node device driver know we're here so it can
1855         * [un]register hstate attributes on node hotplug.
1856         */
1857        register_hugetlbfs_with_node(hugetlb_register_node,
1858                                     hugetlb_unregister_node);
1859}
1860#else   /* !CONFIG_NUMA */
1861
1862static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1863{
1864        BUG();
1865        if (nidp)
1866                *nidp = -1;
1867        return NULL;
1868}
1869
1870static void hugetlb_unregister_all_nodes(void) { }
1871
1872static void hugetlb_register_all_nodes(void) { }
1873
1874#endif
1875
1876static void __exit hugetlb_exit(void)
1877{
1878        struct hstate *h;
1879
1880        hugetlb_unregister_all_nodes();
1881
1882        for_each_hstate(h) {
1883                kobject_put(hstate_kobjs[hstate_index(h)]);
1884        }
1885
1886        kobject_put(hugepages_kobj);
1887}
1888module_exit(hugetlb_exit);
1889
1890static int __init hugetlb_init(void)
1891{
1892        /* Some platform decide whether they support huge pages at boot
1893         * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1894         * there is no such support
1895         */
1896        if (HPAGE_SHIFT == 0)
1897                return 0;
1898
1899        if (!size_to_hstate(default_hstate_size)) {
1900                default_hstate_size = HPAGE_SIZE;
1901                if (!size_to_hstate(default_hstate_size))
1902                        hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1903        }
1904        default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
1905        if (default_hstate_max_huge_pages)
1906                default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1907
1908        hugetlb_init_hstates();
1909        gather_bootmem_prealloc();
1910        report_hugepages();
1911
1912        hugetlb_sysfs_init();
1913        hugetlb_register_all_nodes();
1914        hugetlb_cgroup_file_init();
1915
1916        return 0;
1917}
1918module_init(hugetlb_init);
1919
1920/* Should be called on processing a hugepagesz=... option */
1921void __init hugetlb_add_hstate(unsigned order)
1922{
1923        struct hstate *h;
1924        unsigned long i;
1925
1926        if (size_to_hstate(PAGE_SIZE << order)) {
1927                printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1928                return;
1929        }
1930        BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
1931        BUG_ON(order == 0);
1932        h = &hstates[hugetlb_max_hstate++];
1933        h->order = order;
1934        h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1935        h->nr_huge_pages = 0;
1936        h->free_huge_pages = 0;
1937        for (i = 0; i < MAX_NUMNODES; ++i)
1938                INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1939        INIT_LIST_HEAD(&h->hugepage_activelist);
1940        h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
1941        h->next_nid_to_free = first_node(node_states[N_MEMORY]);
1942        snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1943                                        huge_page_size(h)/1024);
1944
1945        parsed_hstate = h;
1946}
1947
1948static int __init hugetlb_nrpages_setup(char *s)
1949{
1950        unsigned long *mhp;
1951        static unsigned long *last_mhp;
1952
1953        /*
1954         * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
1955         * so this hugepages= parameter goes to the "default hstate".
1956         */
1957        if (!hugetlb_max_hstate)
1958                mhp = &default_hstate_max_huge_pages;
1959        else
1960                mhp = &parsed_hstate->max_huge_pages;
1961
1962        if (mhp == last_mhp) {
1963                printk(KERN_WARNING "hugepages= specified twice without "
1964                        "interleaving hugepagesz=, ignoring\n");
1965                return 1;
1966        }
1967
1968        if (sscanf(s, "%lu", mhp) <= 0)
1969                *mhp = 0;
1970
1971        /*
1972         * Global state is always initialized later in hugetlb_init.
1973         * But we need to allocate >= MAX_ORDER hstates here early to still
1974         * use the bootmem allocator.
1975         */
1976        if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
1977                hugetlb_hstate_alloc_pages(parsed_hstate);
1978
1979        last_mhp = mhp;
1980
1981        return 1;
1982}
1983__setup("hugepages=", hugetlb_nrpages_setup);
1984
1985static int __init hugetlb_default_setup(char *s)
1986{
1987        default_hstate_size = memparse(s, &s);
1988        return 1;
1989}
1990__setup("default_hugepagesz=", hugetlb_default_setup);
1991
1992static unsigned int cpuset_mems_nr(unsigned int *array)
1993{
1994        int node;
1995        unsigned int nr = 0;
1996
1997        for_each_node_mask(node, cpuset_current_mems_allowed)
1998                nr += array[node];
1999
2000        return nr;
2001}
2002
2003#ifdef CONFIG_SYSCTL
2004static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2005                         struct ctl_table *table, int write,
2006                         void __user *buffer, size_t *length, loff_t *ppos)
2007{
2008        struct hstate *h = &default_hstate;
2009        unsigned long tmp;
2010        int ret;
2011
2012        tmp = h->max_huge_pages;
2013
2014        if (write && h->order >= MAX_ORDER)
2015                return -EINVAL;
2016
2017        table->data = &tmp;
2018        table->maxlen = sizeof(unsigned long);
2019        ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2020        if (ret)
2021                goto out;
2022
2023        if (write) {
2024                NODEMASK_ALLOC(nodemask_t, nodes_allowed,
2025                                                GFP_KERNEL | __GFP_NORETRY);
2026                if (!(obey_mempolicy &&
2027                               init_nodemask_of_mempolicy(nodes_allowed))) {
2028                        NODEMASK_FREE(nodes_allowed);
2029                        nodes_allowed = &node_states[N_MEMORY];
2030                }
2031                h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
2032
2033                if (nodes_allowed != &node_states[N_MEMORY])
2034                        NODEMASK_FREE(nodes_allowed);
2035        }
2036out:
2037        return ret;
2038}
2039
2040int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2041                          void __user *buffer, size_t *length, loff_t *ppos)
2042{
2043
2044        return hugetlb_sysctl_handler_common(false, table, write,
2045                                                        buffer, length, ppos);
2046}
2047
2048#ifdef CONFIG_NUMA
2049int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2050                          void __user *buffer, size_t *length, loff_t *ppos)
2051{
2052        return hugetlb_sysctl_handler_common(true, table, write,
2053                                                        buffer, length, ppos);
2054}
2055#endif /* CONFIG_NUMA */
2056
2057int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
2058                        void __user *buffer,
2059                        size_t *length, loff_t *ppos)
2060{
2061        proc_dointvec(table, write, buffer, length, ppos);
2062        if (hugepages_treat_as_movable)
2063                htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
2064        else
2065                htlb_alloc_mask = GFP_HIGHUSER;
2066        return 0;
2067}
2068
2069int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2070                        void __user *buffer,
2071                        size_t *length, loff_t *ppos)
2072{
2073        struct hstate *h = &default_hstate;
2074        unsigned long tmp;
2075        int ret;
2076
2077        tmp = h->nr_overcommit_huge_pages;
2078
2079        if (write && h->order >= MAX_ORDER)
2080                return -EINVAL;
2081
2082        table->data = &tmp;
2083        table->maxlen = sizeof(unsigned long);
2084        ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2085        if (ret)
2086                goto out;
2087
2088        if (write) {
2089                spin_lock(&hugetlb_lock);
2090                h->nr_overcommit_huge_pages = tmp;
2091                spin_unlock(&hugetlb_lock);
2092        }
2093out:
2094        return ret;
2095}
2096
2097#endif /* CONFIG_SYSCTL */
2098
2099void hugetlb_report_meminfo(struct seq_file *m)
2100{
2101        struct hstate *h = &default_hstate;
2102        seq_printf(m,
2103                        "HugePages_Total:   %5lu\n"
2104                        "HugePages_Free:    %5lu\n"
2105                        "HugePages_Rsvd:    %5lu\n"
2106                        "HugePages_Surp:    %5lu\n"
2107                        "Hugepagesize:   %8lu kB\n",
2108                        h->nr_huge_pages,
2109                        h->free_huge_pages,
2110                        h->resv_huge_pages,
2111                        h->surplus_huge_pages,
2112                        1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2113}
2114
2115int hugetlb_report_node_meminfo(int nid, char *buf)
2116{
2117        struct hstate *h = &default_hstate;
2118        return sprintf(buf,
2119                "Node %d HugePages_Total: %5u\n"
2120                "Node %d HugePages_Free:  %5u\n"
2121                "Node %d HugePages_Surp:  %5u\n",
2122                nid, h->nr_huge_pages_node[nid],
2123                nid, h->free_huge_pages_node[nid],
2124                nid, h->surplus_huge_pages_node[nid]);
2125}
2126
2127/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2128unsigned long hugetlb_total_pages(void)
2129{
2130        struct hstate *h = &default_hstate;
2131        return h->nr_huge_pages * pages_per_huge_page(h);
2132}
2133
2134static int hugetlb_acct_memory(struct hstate *h, long delta)
2135{
2136        int ret = -ENOMEM;
2137
2138        spin_lock(&hugetlb_lock);
2139        /*
2140         * When cpuset is configured, it breaks the strict hugetlb page
2141         * reservation as the accounting is done on a global variable. Such
2142         * reservation is completely rubbish in the presence of cpuset because
2143         * the reservation is not checked against page availability for the
2144         * current cpuset. Application can still potentially OOM'ed by kernel
2145         * with lack of free htlb page in cpuset that the task is in.
2146         * Attempt to enforce strict accounting with cpuset is almost
2147         * impossible (or too ugly) because cpuset is too fluid that
2148         * task or memory node can be dynamically moved between cpusets.
2149         *
2150         * The change of semantics for shared hugetlb mapping with cpuset is
2151         * undesirable. However, in order to preserve some of the semantics,
2152         * we fall back to check against current free page availability as
2153         * a best attempt and hopefully to minimize the impact of changing
2154         * semantics that cpuset has.
2155         */
2156        if (delta > 0) {
2157                if (gather_surplus_pages(h, delta) < 0)
2158                        goto out;
2159
2160                if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2161                        return_unused_surplus_pages(h, delta);
2162                        goto out;
2163                }
2164        }
2165
2166        ret = 0;
2167        if (delta < 0)
2168                return_unused_surplus_pages(h, (unsigned long) -delta);
2169
2170out:
2171        spin_unlock(&hugetlb_lock);
2172        return ret;
2173}
2174
2175static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2176{
2177        struct resv_map *reservations = vma_resv_map(vma);
2178
2179        /*
2180         * This new VMA should share its siblings reservation map if present.
2181         * The VMA will only ever have a valid reservation map pointer where
2182         * it is being copied for another still existing VMA.  As that VMA
2183         * has a reference to the reservation map it cannot disappear until
2184         * after this open call completes.  It is therefore safe to take a
2185         * new reference here without additional locking.
2186         */
2187        if (reservations)
2188                kref_get(&reservations->refs);
2189}
2190
2191static void resv_map_put(struct vm_area_struct *vma)
2192{
2193        struct resv_map *reservations = vma_resv_map(vma);
2194
2195        if (!reservations)
2196                return;
2197        kref_put(&reservations->refs, resv_map_release);
2198}
2199
2200static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2201{
2202        struct hstate *h = hstate_vma(vma);
2203        struct resv_map *reservations = vma_resv_map(vma);
2204        struct hugepage_subpool *spool = subpool_vma(vma);
2205        unsigned long reserve;
2206        unsigned long start;
2207        unsigned long end;
2208
2209        if (reservations) {
2210                start = vma_hugecache_offset(h, vma, vma->vm_start);
2211                end = vma_hugecache_offset(h, vma, vma->vm_end);
2212
2213                reserve = (end - start) -
2214                        region_count(&reservations->regions, start, end);
2215
2216                resv_map_put(vma);
2217
2218                if (reserve) {
2219                        hugetlb_acct_memory(h, -reserve);
2220                        hugepage_subpool_put_pages(spool, reserve);
2221                }
2222        }
2223}
2224
2225/*
2226 * We cannot handle pagefaults against hugetlb pages at all.  They cause
2227 * handle_mm_fault() to try to instantiate regular-sized pages in the
2228 * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2229 * this far.
2230 */
2231static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2232{
2233        BUG();
2234        return 0;
2235}
2236
2237const struct vm_operations_struct hugetlb_vm_ops = {
2238        .fault = hugetlb_vm_op_fault,
2239        .open = hugetlb_vm_op_open,
2240        .close = hugetlb_vm_op_close,
2241};
2242
2243static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2244                                int writable)
2245{
2246        pte_t entry;
2247
2248        if (writable) {
2249                entry =
2250                    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2251        } else {
2252                entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2253        }
2254        entry = pte_mkyoung(entry);
2255        entry = pte_mkhuge(entry);
2256        entry = arch_make_huge_pte(entry, vma, page, writable);
2257
2258        return entry;
2259}
2260
2261static void set_huge_ptep_writable(struct vm_area_struct *vma,
2262                                   unsigned long address, pte_t *ptep)
2263{
2264        pte_t entry;
2265
2266        entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2267        if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
2268                update_mmu_cache(vma, address, ptep);
2269}
2270
2271
2272int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2273                            struct vm_area_struct *vma)
2274{
2275        pte_t *src_pte, *dst_pte, entry;
2276        struct page *ptepage;
2277        unsigned long addr;
2278        int cow;
2279        struct hstate *h = hstate_vma(vma);
2280        unsigned long sz = huge_page_size(h);
2281
2282        cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2283
2284        for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2285                src_pte = huge_pte_offset(src, addr);
2286                if (!src_pte)
2287                        continue;
2288                dst_pte = huge_pte_alloc(dst, addr, sz);
2289                if (!dst_pte)
2290                        goto nomem;
2291
2292                /* If the pagetables are shared don't copy or take references */
2293                if (dst_pte == src_pte)
2294                        continue;
2295
2296                spin_lock(&dst->page_table_lock);
2297                spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2298                if (!huge_pte_none(huge_ptep_get(src_pte))) {
2299                        if (cow)
2300                                huge_ptep_set_wrprotect(src, addr, src_pte);
2301                        entry = huge_ptep_get(src_pte);
2302                        ptepage = pte_page(entry);
2303                        get_page(ptepage);
2304                        page_dup_rmap(ptepage);
2305                        set_huge_pte_at(dst, addr, dst_pte, entry);
2306                }
2307                spin_unlock(&src->page_table_lock);
2308                spin_unlock(&dst->page_table_lock);
2309        }
2310        return 0;
2311
2312nomem:
2313        return -ENOMEM;
2314}
2315
2316static int is_hugetlb_entry_migration(pte_t pte)
2317{
2318        swp_entry_t swp;
2319
2320        if (huge_pte_none(pte) || pte_present(pte))
2321                return 0;
2322        swp = pte_to_swp_entry(pte);
2323        if (non_swap_entry(swp) && is_migration_entry(swp))
2324                return 1;
2325        else
2326                return 0;
2327}
2328
2329static int is_hugetlb_entry_hwpoisoned(pte_t pte)
2330{
2331        swp_entry_t swp;
2332
2333        if (huge_pte_none(pte) || pte_present(pte))
2334                return 0;
2335        swp = pte_to_swp_entry(pte);
2336        if (non_swap_entry(swp) && is_hwpoison_entry(swp))
2337                return 1;
2338        else
2339                return 0;
2340}
2341
2342void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
2343                            unsigned long start, unsigned long end,
2344                            struct page *ref_page)
2345{
2346        int force_flush = 0;
2347        struct mm_struct *mm = vma->vm_mm;
2348        unsigned long address;
2349        pte_t *ptep;
2350        pte_t pte;
2351        struct page *page;
2352        struct hstate *h = hstate_vma(vma);
2353        unsigned long sz = huge_page_size(h);
2354        const unsigned long mmun_start = start; /* For mmu_notifiers */
2355        const unsigned long mmun_end   = end;   /* For mmu_notifiers */
2356
2357        WARN_ON(!is_vm_hugetlb_page(vma));
2358        BUG_ON(start & ~huge_page_mask(h));
2359        BUG_ON(end & ~huge_page_mask(h));
2360
2361        tlb_start_vma(tlb, vma);
2362        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2363again:
2364        spin_lock(&mm->page_table_lock);
2365        for (address = start; address < end; address += sz) {
2366                ptep = huge_pte_offset(mm, address);
2367                if (!ptep)
2368                        continue;
2369
2370                if (huge_pmd_unshare(mm, &address, ptep))
2371                        continue;
2372
2373                pte = huge_ptep_get(ptep);
2374                if (huge_pte_none(pte))
2375                        continue;
2376
2377                /*
2378                 * HWPoisoned hugepage is already unmapped and dropped reference
2379                 */
2380                if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
2381                        pte_clear(mm, address, ptep);
2382                        continue;
2383                }
2384
2385                page = pte_page(pte);
2386                /*
2387                 * If a reference page is supplied, it is because a specific
2388                 * page is being unmapped, not a range. Ensure the page we
2389                 * are about to unmap is the actual page of interest.
2390                 */
2391                if (ref_page) {
2392                        if (page != ref_page)
2393                                continue;
2394
2395                        /*
2396                         * Mark the VMA as having unmapped its page so that
2397                         * future faults in this VMA will fail rather than
2398                         * looking like data was lost
2399                         */
2400                        set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2401                }
2402
2403                pte = huge_ptep_get_and_clear(mm, address, ptep);
2404                tlb_remove_tlb_entry(tlb, ptep, address);
2405                if (pte_dirty(pte))
2406                        set_page_dirty(page);
2407
2408                page_remove_rmap(page);
2409                force_flush = !__tlb_remove_page(tlb, page);
2410                if (force_flush)
2411                        break;
2412                /* Bail out after unmapping reference page if supplied */
2413                if (ref_page)
2414                        break;
2415        }
2416        spin_unlock(&mm->page_table_lock);
2417        /*
2418         * mmu_gather ran out of room to batch pages, we break out of
2419         * the PTE lock to avoid doing the potential expensive TLB invalidate
2420         * and page-free while holding it.
2421         */
2422        if (force_flush) {
2423                force_flush = 0;
2424                tlb_flush_mmu(tlb);
2425                if (address < end && !ref_page)
2426                        goto again;
2427        }
2428        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2429        tlb_end_vma(tlb, vma);
2430}
2431
2432void __unmap_hugepage_range_final(struct mmu_gather *tlb,
2433                          struct vm_area_struct *vma, unsigned long start,
2434                          unsigned long end, struct page *ref_page)
2435{
2436        __unmap_hugepage_range(tlb, vma, start, end, ref_page);
2437
2438        /*
2439         * Clear this flag so that x86's huge_pmd_share page_table_shareable
2440         * test will fail on a vma being torn down, and not grab a page table
2441         * on its way out.  We're lucky that the flag has such an appropriate
2442         * name, and can in fact be safely cleared here. We could clear it
2443         * before the __unmap_hugepage_range above, but all that's necessary
2444         * is to clear it before releasing the i_mmap_mutex. This works
2445         * because in the context this is called, the VMA is about to be
2446         * destroyed and the i_mmap_mutex is held.
2447         */
2448        vma->vm_flags &= ~VM_MAYSHARE;
2449}
2450
2451void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2452                          unsigned long end, struct page *ref_page)
2453{
2454        struct mm_struct *mm;
2455        struct mmu_gather tlb;
2456
2457        mm = vma->vm_mm;
2458
2459        tlb_gather_mmu(&tlb, mm, 0);
2460        __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
2461        tlb_finish_mmu(&tlb, start, end);
2462}
2463
2464/*
2465 * This is called when the original mapper is failing to COW a MAP_PRIVATE
2466 * mappping it owns the reserve page for. The intention is to unmap the page
2467 * from other VMAs and let the children be SIGKILLed if they are faulting the
2468 * same region.
2469 */
2470static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2471                                struct page *page, unsigned long address)
2472{
2473        struct hstate *h = hstate_vma(vma);
2474        struct vm_area_struct *iter_vma;
2475        struct address_space *mapping;
2476        pgoff_t pgoff;
2477
2478        /*
2479         * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2480         * from page cache lookup which is in HPAGE_SIZE units.
2481         */
2482        address = address & huge_page_mask(h);
2483        pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
2484                        vma->vm_pgoff;
2485        mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
2486
2487        /*
2488         * Take the mapping lock for the duration of the table walk. As
2489         * this mapping should be shared between all the VMAs,
2490         * __unmap_hugepage_range() is called as the lock is already held
2491         */
2492        mutex_lock(&mapping->i_mmap_mutex);
2493        vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
2494                /* Do not unmap the current VMA */
2495                if (iter_vma == vma)
2496                        continue;
2497
2498                /*
2499                 * Unmap the page from other VMAs without their own reserves.
2500                 * They get marked to be SIGKILLed if they fault in these
2501                 * areas. This is because a future no-page fault on this VMA
2502                 * could insert a zeroed page instead of the data existing
2503                 * from the time of fork. This would look like data corruption
2504                 */
2505                if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2506                        unmap_hugepage_range(iter_vma, address,
2507                                             address + huge_page_size(h), page);
2508        }
2509        mutex_unlock(&mapping->i_mmap_mutex);
2510
2511        return 1;
2512}
2513
2514/*
2515 * Hugetlb_cow() should be called with page lock of the original hugepage held.
2516 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
2517 * cannot race with other handlers or page migration.
2518 * Keep the pte_same checks anyway to make transition from the mutex easier.
2519 */
2520static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2521                        unsigned long address, pte_t *ptep, pte_t pte,
2522                        struct page *pagecache_page)
2523{
2524        struct hstate *h = hstate_vma(vma);
2525        struct page *old_page, *new_page;
2526        int avoidcopy;
2527        int outside_reserve = 0;
2528        unsigned long mmun_start;       /* For mmu_notifiers */
2529        unsigned long mmun_end;         /* For mmu_notifiers */
2530
2531        old_page = pte_page(pte);
2532
2533retry_avoidcopy:
2534        /* If no-one else is actually using this page, avoid the copy
2535         * and just make the page writable */
2536        avoidcopy = (page_mapcount(old_page) == 1);
2537        if (avoidcopy) {
2538                if (PageAnon(old_page))
2539                        page_move_anon_rmap(old_page, vma, address);
2540                set_huge_ptep_writable(vma, address, ptep);
2541                return 0;
2542        }
2543
2544        /*
2545         * If the process that created a MAP_PRIVATE mapping is about to
2546         * perform a COW due to a shared page count, attempt to satisfy
2547         * the allocation without using the existing reserves. The pagecache
2548         * page is used to determine if the reserve at this address was
2549         * consumed or not. If reserves were used, a partial faulted mapping
2550         * at the time of fork() could consume its reserves on COW instead
2551         * of the full address range.
2552         */
2553        if (!(vma->vm_flags & VM_MAYSHARE) &&
2554                        is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2555                        old_page != pagecache_page)
2556                outside_reserve = 1;
2557
2558        page_cache_get(old_page);
2559
2560        /* Drop page_table_lock as buddy allocator may be called */
2561        spin_unlock(&mm->page_table_lock);
2562        new_page = alloc_huge_page(vma, address, outside_reserve);
2563
2564        if (IS_ERR(new_page)) {
2565                long err = PTR_ERR(new_page);
2566                page_cache_release(old_page);
2567
2568                /*
2569                 * If a process owning a MAP_PRIVATE mapping fails to COW,
2570                 * it is due to references held by a child and an insufficient
2571                 * huge page pool. To guarantee the original mappers
2572                 * reliability, unmap the page from child processes. The child
2573                 * may get SIGKILLed if it later faults.
2574                 */
2575                if (outside_reserve) {
2576                        BUG_ON(huge_pte_none(pte));
2577                        if (unmap_ref_private(mm, vma, old_page, address)) {
2578                                BUG_ON(huge_pte_none(pte));
2579                                spin_lock(&mm->page_table_lock);
2580                                ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2581                                if (likely(pte_same(huge_ptep_get(ptep), pte)))
2582                                        goto retry_avoidcopy;
2583                                /*
2584                                 * race occurs while re-acquiring page_table_lock, and
2585                                 * our job is done.
2586                                 */
2587                                return 0;
2588                        }
2589                        WARN_ON_ONCE(1);
2590                }
2591
2592                /* Caller expects lock to be held */
2593                spin_lock(&mm->page_table_lock);
2594                if (err == -ENOMEM)
2595                        return VM_FAULT_OOM;
2596                else
2597                        return VM_FAULT_SIGBUS;
2598        }
2599
2600        /*
2601         * When the original hugepage is shared one, it does not have
2602         * anon_vma prepared.
2603         */
2604        if (unlikely(anon_vma_prepare(vma))) {
2605                page_cache_release(new_page);
2606                page_cache_release(old_page);
2607                /* Caller expects lock to be held */
2608                spin_lock(&mm->page_table_lock);
2609                return VM_FAULT_OOM;
2610        }
2611
2612        copy_user_huge_page(new_page, old_page, address, vma,
2613                            pages_per_huge_page(h));
2614        __SetPageUptodate(new_page);
2615
2616        mmun_start = address & huge_page_mask(h);
2617        mmun_end = mmun_start + huge_page_size(h);
2618        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2619        /*
2620         * Retake the page_table_lock to check for racing updates
2621         * before the page tables are altered
2622         */
2623        spin_lock(&mm->page_table_lock);
2624        ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2625        if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2626                /* Break COW */
2627                huge_ptep_clear_flush(vma, address, ptep);
2628                set_huge_pte_at(mm, address, ptep,
2629                                make_huge_pte(vma, new_page, 1));
2630                page_remove_rmap(old_page);
2631                hugepage_add_new_anon_rmap(new_page, vma, address);
2632                /* Make the old page be freed below */
2633                new_page = old_page;
2634        }
2635        spin_unlock(&mm->page_table_lock);
2636        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2637        /* Caller expects lock to be held */
2638        spin_lock(&mm->page_table_lock);
2639        page_cache_release(new_page);
2640        page_cache_release(old_page);
2641        return 0;
2642}
2643
2644/* Return the pagecache page at a given address within a VMA */
2645static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2646                        struct vm_area_struct *vma, unsigned long address)
2647{
2648        struct address_space *mapping;
2649        pgoff_t idx;
2650
2651        mapping = vma->vm_file->f_mapping;
2652        idx = vma_hugecache_offset(h, vma, address);
2653
2654        return find_lock_page(mapping, idx);
2655}
2656
2657/*
2658 * Return whether there is a pagecache page to back given address within VMA.
2659 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2660 */
2661static bool hugetlbfs_pagecache_present(struct hstate *h,
2662                        struct vm_area_struct *vma, unsigned long address)
2663{
2664        struct address_space *mapping;
2665        pgoff_t idx;
2666        struct page *page;
2667
2668        mapping = vma->vm_file->f_mapping;
2669        idx = vma_hugecache_offset(h, vma, address);
2670
2671        page = find_get_page(mapping, idx);
2672        if (page)
2673                put_page(page);
2674        return page != NULL;
2675}
2676
2677static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2678                        unsigned long address, pte_t *ptep, unsigned int flags)
2679{
2680        struct hstate *h = hstate_vma(vma);
2681        int ret = VM_FAULT_SIGBUS;
2682        int anon_rmap = 0;
2683        pgoff_t idx;
2684        unsigned long size;
2685        struct page *page;
2686        struct address_space *mapping;
2687        pte_t new_pte;
2688
2689        /*
2690         * Currently, we are forced to kill the process in the event the
2691         * original mapper has unmapped pages from the child due to a failed
2692         * COW. Warn that such a situation has occurred as it may not be obvious
2693         */
2694        if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2695                printk(KERN_WARNING
2696                        "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
2927int 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, int *length, int i,
2930                        unsigned int flags)
2931{
2932        unsigned long pfn_offset;
2933        unsigned long vaddr = *position;
2934        int remainder = *length;
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                if (absent ||
2965                    ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2966                        int ret;
2967
2968                        spin_unlock(&mm->page_table_lock);
2969                        ret = hugetlb_fault(mm, vma, vaddr,
2970                                (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2971                        spin_lock(&mm->page_table_lock);
2972                        if (!(ret & VM_FAULT_ERROR))
2973                                continue;
2974
2975                        remainder = 0;
2976                        break;
2977                }
2978
2979                pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2980                page = pte_page(huge_ptep_get(pte));
2981same_page:
2982                if (pages) {
2983                        pages[i] = mem_map_offset(page, pfn_offset);
2984                        get_page(pages[i]);
2985                }
2986
2987                if (vmas)
2988                        vmas[i] = vma;
2989
2990                vaddr += PAGE_SIZE;
2991                ++pfn_offset;
2992                --remainder;
2993                ++i;
2994                if (vaddr < vma->vm_end && remainder &&
2995                                pfn_offset < pages_per_huge_page(h)) {
2996                        /*
2997                         * We use pfn_offset to avoid touching the pageframes
2998                         * of this compound page.
2999                         */
3000                        goto same_page;
3001                }
3002        }
3003        spin_unlock(&mm->page_table_lock);
3004        *length = remainder;
3005        *position = vaddr;
3006
3007        return i ? i : -EFAULT;
3008}
3009
3010unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3011                unsigned long address, unsigned long end, pgprot_t newprot)
3012{
3013        struct mm_struct *mm = vma->vm_mm;
3014        unsigned long start = address;
3015        pte_t *ptep;
3016        pte_t pte;
3017        struct hstate *h = hstate_vma(vma);
3018        unsigned long pages = 0;
3019
3020        BUG_ON(address >= end);
3021        flush_cache_range(vma, address, end);
3022
3023        mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
3024        spin_lock(&mm->page_table_lock);
3025        for (; address < end; address += huge_page_size(h)) {
3026                ptep = huge_pte_offset(mm, address);
3027                if (!ptep)
3028                        continue;
3029                if (huge_pmd_unshare(mm, &address, ptep)) {
3030                        pages++;
3031                        continue;
3032                }
3033                if (!huge_pte_none(huge_ptep_get(ptep))) {
3034                        pte = huge_ptep_get_and_clear(mm, address, ptep);
3035                        pte = pte_mkhuge(pte_modify(pte, newprot));
3036                        pte = arch_make_huge_pte(pte, vma, NULL, 0);
3037                        set_huge_pte_at(mm, address, ptep, pte);
3038                        pages++;
3039                }
3040        }
3041        spin_unlock(&mm->page_table_lock);
3042        /*
3043         * Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare
3044         * may have cleared our pud entry and done put_page on the page table:
3045         * once we release i_mmap_mutex, another task can do the final put_page
3046         * and that page table be reused and filled with junk.
3047         */
3048        flush_tlb_range(vma, start, end);
3049        mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
3050
3051        return pages << h->order;
3052}
3053
3054int hugetlb_reserve_pages(struct inode *inode,
3055                                        long from, long to,
3056                                        struct vm_area_struct *vma,
3057                                        vm_flags_t vm_flags)
3058{
3059        long ret, chg;
3060        struct hstate *h = hstate_inode(inode);
3061        struct hugepage_subpool *spool = subpool_inode(inode);
3062
3063        /*
3064         * Only apply hugepage reservation if asked. At fault time, an
3065         * attempt will be made for VM_NORESERVE to allocate a page
3066         * without using reserves
3067         */
3068        if (vm_flags & VM_NORESERVE)
3069                return 0;
3070
3071        /*
3072         * Shared mappings base their reservation on the number of pages that
3073         * are already allocated on behalf of the file. Private mappings need
3074         * to reserve the full area even if read-only as mprotect() may be
3075         * called to make the mapping read-write. Assume !vma is a shm mapping
3076         */
3077        if (!vma || vma->vm_flags & VM_MAYSHARE)
3078                chg = region_chg(&inode->i_mapping->private_list, from, to);
3079        else {
3080                struct resv_map *resv_map = resv_map_alloc();
3081                if (!resv_map)
3082                        return -ENOMEM;
3083
3084                chg = to - from;
3085
3086                set_vma_resv_map(vma, resv_map);
3087                set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
3088        }
3089
3090        if (chg < 0) {
3091                ret = chg;
3092                goto out_err;
3093        }
3094
3095        /* There must be enough pages in the subpool for the mapping */
3096        if (hugepage_subpool_get_pages(spool, chg)) {
3097                ret = -ENOSPC;
3098                goto out_err;
3099        }
3100
3101        /*
3102         * Check enough hugepages are available for the reservation.
3103         * Hand the pages back to the subpool if there are not
3104         */
3105        ret = hugetlb_acct_memory(h, chg);
3106        if (ret < 0) {
3107                hugepage_subpool_put_pages(spool, chg);
3108                goto out_err;
3109        }
3110
3111        /*
3112         * Account for the reservations made. Shared mappings record regions
3113         * that have reservations as they are shared by multiple VMAs.
3114         * When the last VMA disappears, the region map says how much
3115         * the reservation was and the page cache tells how much of
3116         * the reservation was consumed. Private mappings are per-VMA and
3117         * only the consumed reservations are tracked. When the VMA
3118         * disappears, the original reservation is the VMA size and the
3119         * consumed reservations are stored in the map. Hence, nothing
3120         * else has to be done for private mappings here
3121         */
3122        if (!vma || vma->vm_flags & VM_MAYSHARE)
3123                region_add(&inode->i_mapping->private_list, from, to);
3124        return 0;
3125out_err:
3126        if (vma)
3127                resv_map_put(vma);
3128        return ret;
3129}
3130
3131void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
3132{
3133        struct hstate *h = hstate_inode(inode);
3134        long chg = region_truncate(&inode->i_mapping->private_list, offset);
3135        struct hugepage_subpool *spool = subpool_inode(inode);
3136
3137        spin_lock(&inode->i_lock);
3138        inode->i_blocks -= (blocks_per_huge_page(h) * freed);
3139        spin_unlock(&inode->i_lock);
3140
3141        hugepage_subpool_put_pages(spool, (chg - freed));
3142        hugetlb_acct_memory(h, -(chg - freed));
3143}
3144
3145#ifdef CONFIG_MEMORY_FAILURE
3146
3147/* Should be called in hugetlb_lock */
3148static int is_hugepage_on_freelist(struct page *hpage)
3149{
3150        struct page *page;
3151        struct page *tmp;
3152        struct hstate *h = page_hstate(hpage);
3153        int nid = page_to_nid(hpage);
3154
3155        list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
3156                if (page == hpage)
3157                        return 1;
3158        return 0;
3159}
3160
3161/*
3162 * This function is called from memory failure code.
3163 * Assume the caller holds page lock of the head page.
3164 */
3165int dequeue_hwpoisoned_huge_page(struct page *hpage)
3166{
3167        struct hstate *h = page_hstate(hpage);
3168        int nid = page_to_nid(hpage);
3169        int ret = -EBUSY;
3170
3171        spin_lock(&hugetlb_lock);
3172        if (is_hugepage_on_freelist(hpage)) {
3173                /*
3174                 * Hwpoisoned hugepage isn't linked to activelist or freelist,
3175                 * but dangling hpage->lru can trigger list-debug warnings
3176                 * (this happens when we call unpoison_memory() on it),
3177                 * so let it point to itself with list_del_init().
3178                 */
3179                list_del_init(&hpage->lru);
3180                set_page_refcounted(hpage);
3181                h->free_huge_pages--;
3182                h->free_huge_pages_node[nid]--;
3183                ret = 0;
3184        }
3185        spin_unlock(&hugetlb_lock);
3186        return ret;
3187}
3188#endif
3189
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