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