linux/mm/memory.c
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   1/*
   2 *  linux/mm/memory.c
   3 *
   4 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   5 */
   6
   7/*
   8 * demand-loading started 01.12.91 - seems it is high on the list of
   9 * things wanted, and it should be easy to implement. - Linus
  10 */
  11
  12/*
  13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
  14 * pages started 02.12.91, seems to work. - Linus.
  15 *
  16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
  17 * would have taken more than the 6M I have free, but it worked well as
  18 * far as I could see.
  19 *
  20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
  21 */
  22
  23/*
  24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
  25 * thought has to go into this. Oh, well..
  26 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
  27 *              Found it. Everything seems to work now.
  28 * 20.12.91  -  Ok, making the swap-device changeable like the root.
  29 */
  30
  31/*
  32 * 05.04.94  -  Multi-page memory management added for v1.1.
  33 *              Idea by Alex Bligh (alex@cconcepts.co.uk)
  34 *
  35 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
  36 *              (Gerhard.Wichert@pdb.siemens.de)
  37 *
  38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
  39 */
  40
  41#include <linux/kernel_stat.h>
  42#include <linux/mm.h>
  43#include <linux/hugetlb.h>
  44#include <linux/mman.h>
  45#include <linux/swap.h>
  46#include <linux/highmem.h>
  47#include <linux/pagemap.h>
  48#include <linux/ksm.h>
  49#include <linux/rmap.h>
  50#include <linux/export.h>
  51#include <linux/delayacct.h>
  52#include <linux/init.h>
  53#include <linux/writeback.h>
  54#include <linux/memcontrol.h>
  55#include <linux/mmu_notifier.h>
  56#include <linux/kallsyms.h>
  57#include <linux/swapops.h>
  58#include <linux/elf.h>
  59#include <linux/gfp.h>
  60#include <linux/migrate.h>
  61#include <linux/string.h>
  62
  63#include <asm/io.h>
  64#include <asm/pgalloc.h>
  65#include <asm/uaccess.h>
  66#include <asm/tlb.h>
  67#include <asm/tlbflush.h>
  68#include <asm/pgtable.h>
  69
  70#include "internal.h"
  71
  72#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
  73#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_nid.
  74#endif
  75
  76#ifndef CONFIG_NEED_MULTIPLE_NODES
  77/* use the per-pgdat data instead for discontigmem - mbligh */
  78unsigned long max_mapnr;
  79struct page *mem_map;
  80
  81EXPORT_SYMBOL(max_mapnr);
  82EXPORT_SYMBOL(mem_map);
  83#endif
  84
  85unsigned long num_physpages;
  86/*
  87 * A number of key systems in x86 including ioremap() rely on the assumption
  88 * that high_memory defines the upper bound on direct map memory, then end
  89 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  90 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  91 * and ZONE_HIGHMEM.
  92 */
  93void * high_memory;
  94
  95EXPORT_SYMBOL(num_physpages);
  96EXPORT_SYMBOL(high_memory);
  97
  98/*
  99 * Randomize the address space (stacks, mmaps, brk, etc.).
 100 *
 101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 102 *   as ancient (libc5 based) binaries can segfault. )
 103 */
 104int randomize_va_space __read_mostly =
 105#ifdef CONFIG_COMPAT_BRK
 106                                        1;
 107#else
 108                                        2;
 109#endif
 110
 111static int __init disable_randmaps(char *s)
 112{
 113        randomize_va_space = 0;
 114        return 1;
 115}
 116__setup("norandmaps", disable_randmaps);
 117
 118unsigned long zero_pfn __read_mostly;
 119unsigned long highest_memmap_pfn __read_mostly;
 120
 121/*
 122 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 123 */
 124static int __init init_zero_pfn(void)
 125{
 126        zero_pfn = page_to_pfn(ZERO_PAGE(0));
 127        return 0;
 128}
 129core_initcall(init_zero_pfn);
 130
 131
 132#if defined(SPLIT_RSS_COUNTING)
 133
 134void sync_mm_rss(struct mm_struct *mm)
 135{
 136        int i;
 137
 138        for (i = 0; i < NR_MM_COUNTERS; i++) {
 139                if (current->rss_stat.count[i]) {
 140                        add_mm_counter(mm, i, current->rss_stat.count[i]);
 141                        current->rss_stat.count[i] = 0;
 142                }
 143        }
 144        current->rss_stat.events = 0;
 145}
 146
 147static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
 148{
 149        struct task_struct *task = current;
 150
 151        if (likely(task->mm == mm))
 152                task->rss_stat.count[member] += val;
 153        else
 154                add_mm_counter(mm, member, val);
 155}
 156#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
 157#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
 158
 159/* sync counter once per 64 page faults */
 160#define TASK_RSS_EVENTS_THRESH  (64)
 161static void check_sync_rss_stat(struct task_struct *task)
 162{
 163        if (unlikely(task != current))
 164                return;
 165        if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
 166                sync_mm_rss(task->mm);
 167}
 168#else /* SPLIT_RSS_COUNTING */
 169
 170#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
 171#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
 172
 173static void check_sync_rss_stat(struct task_struct *task)
 174{
 175}
 176
 177#endif /* SPLIT_RSS_COUNTING */
 178
 179#ifdef HAVE_GENERIC_MMU_GATHER
 180
 181static int tlb_next_batch(struct mmu_gather *tlb)
 182{
 183        struct mmu_gather_batch *batch;
 184
 185        batch = tlb->active;
 186        if (batch->next) {
 187                tlb->active = batch->next;
 188                return 1;
 189        }
 190
 191        if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
 192                return 0;
 193
 194        batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 195        if (!batch)
 196                return 0;
 197
 198        tlb->batch_count++;
 199        batch->next = NULL;
 200        batch->nr   = 0;
 201        batch->max  = MAX_GATHER_BATCH;
 202
 203        tlb->active->next = batch;
 204        tlb->active = batch;
 205
 206        return 1;
 207}
 208
 209/* tlb_gather_mmu
 210 *      Called to initialize an (on-stack) mmu_gather structure for page-table
 211 *      tear-down from @mm. The @fullmm argument is used when @mm is without
 212 *      users and we're going to destroy the full address space (exit/execve).
 213 */
 214void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
 215{
 216        tlb->mm = mm;
 217
 218        tlb->fullmm     = fullmm;
 219        tlb->need_flush_all = 0;
 220        tlb->start      = -1UL;
 221        tlb->end        = 0;
 222        tlb->need_flush = 0;
 223        tlb->local.next = NULL;
 224        tlb->local.nr   = 0;
 225        tlb->local.max  = ARRAY_SIZE(tlb->__pages);
 226        tlb->active     = &tlb->local;
 227        tlb->batch_count = 0;
 228
 229#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 230        tlb->batch = NULL;
 231#endif
 232}
 233
 234void tlb_flush_mmu(struct mmu_gather *tlb)
 235{
 236        struct mmu_gather_batch *batch;
 237
 238        if (!tlb->need_flush)
 239                return;
 240        tlb->need_flush = 0;
 241        tlb_flush(tlb);
 242#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 243        tlb_table_flush(tlb);
 244#endif
 245
 246        for (batch = &tlb->local; batch; batch = batch->next) {
 247                free_pages_and_swap_cache(batch->pages, batch->nr);
 248                batch->nr = 0;
 249        }
 250        tlb->active = &tlb->local;
 251}
 252
 253/* tlb_finish_mmu
 254 *      Called at the end of the shootdown operation to free up any resources
 255 *      that were required.
 256 */
 257void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 258{
 259        struct mmu_gather_batch *batch, *next;
 260
 261        tlb->start = start;
 262        tlb->end   = end;
 263        tlb_flush_mmu(tlb);
 264
 265        /* keep the page table cache within bounds */
 266        check_pgt_cache();
 267
 268        for (batch = tlb->local.next; batch; batch = next) {
 269                next = batch->next;
 270                free_pages((unsigned long)batch, 0);
 271        }
 272        tlb->local.next = NULL;
 273}
 274
 275/* __tlb_remove_page
 276 *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 277 *      handling the additional races in SMP caused by other CPUs caching valid
 278 *      mappings in their TLBs. Returns the number of free page slots left.
 279 *      When out of page slots we must call tlb_flush_mmu().
 280 */
 281int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 282{
 283        struct mmu_gather_batch *batch;
 284
 285        VM_BUG_ON(!tlb->need_flush);
 286
 287        batch = tlb->active;
 288        batch->pages[batch->nr++] = page;
 289        if (batch->nr == batch->max) {
 290                if (!tlb_next_batch(tlb))
 291                        return 0;
 292                batch = tlb->active;
 293        }
 294        VM_BUG_ON(batch->nr > batch->max);
 295
 296        return batch->max - batch->nr;
 297}
 298
 299#endif /* HAVE_GENERIC_MMU_GATHER */
 300
 301#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 302
 303/*
 304 * See the comment near struct mmu_table_batch.
 305 */
 306
 307static void tlb_remove_table_smp_sync(void *arg)
 308{
 309        /* Simply deliver the interrupt */
 310}
 311
 312static void tlb_remove_table_one(void *table)
 313{
 314        /*
 315         * This isn't an RCU grace period and hence the page-tables cannot be
 316         * assumed to be actually RCU-freed.
 317         *
 318         * It is however sufficient for software page-table walkers that rely on
 319         * IRQ disabling. See the comment near struct mmu_table_batch.
 320         */
 321        smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
 322        __tlb_remove_table(table);
 323}
 324
 325static void tlb_remove_table_rcu(struct rcu_head *head)
 326{
 327        struct mmu_table_batch *batch;
 328        int i;
 329
 330        batch = container_of(head, struct mmu_table_batch, rcu);
 331
 332        for (i = 0; i < batch->nr; i++)
 333                __tlb_remove_table(batch->tables[i]);
 334
 335        free_page((unsigned long)batch);
 336}
 337
 338void tlb_table_flush(struct mmu_gather *tlb)
 339{
 340        struct mmu_table_batch **batch = &tlb->batch;
 341
 342        if (*batch) {
 343                call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
 344                *batch = NULL;
 345        }
 346}
 347
 348void tlb_remove_table(struct mmu_gather *tlb, void *table)
 349{
 350        struct mmu_table_batch **batch = &tlb->batch;
 351
 352        tlb->need_flush = 1;
 353
 354        /*
 355         * When there's less then two users of this mm there cannot be a
 356         * concurrent page-table walk.
 357         */
 358        if (atomic_read(&tlb->mm->mm_users) < 2) {
 359                __tlb_remove_table(table);
 360                return;
 361        }
 362
 363        if (*batch == NULL) {
 364                *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
 365                if (*batch == NULL) {
 366                        tlb_remove_table_one(table);
 367                        return;
 368                }
 369                (*batch)->nr = 0;
 370        }
 371        (*batch)->tables[(*batch)->nr++] = table;
 372        if ((*batch)->nr == MAX_TABLE_BATCH)
 373                tlb_table_flush(tlb);
 374}
 375
 376#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
 377
 378/*
 379 * If a p?d_bad entry is found while walking page tables, report
 380 * the error, before resetting entry to p?d_none.  Usually (but
 381 * very seldom) called out from the p?d_none_or_clear_bad macros.
 382 */
 383
 384void pgd_clear_bad(pgd_t *pgd)
 385{
 386        pgd_ERROR(*pgd);
 387        pgd_clear(pgd);
 388}
 389
 390void pud_clear_bad(pud_t *pud)
 391{
 392        pud_ERROR(*pud);
 393        pud_clear(pud);
 394}
 395
 396void pmd_clear_bad(pmd_t *pmd)
 397{
 398        pmd_ERROR(*pmd);
 399        pmd_clear(pmd);
 400}
 401
 402/*
 403 * Note: this doesn't free the actual pages themselves. That
 404 * has been handled earlier when unmapping all the memory regions.
 405 */
 406static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 407                           unsigned long addr)
 408{
 409        pgtable_t token = pmd_pgtable(*pmd);
 410        pmd_clear(pmd);
 411        pte_free_tlb(tlb, token, addr);
 412        tlb->mm->nr_ptes--;
 413}
 414
 415static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 416                                unsigned long addr, unsigned long end,
 417                                unsigned long floor, unsigned long ceiling)
 418{
 419        pmd_t *pmd;
 420        unsigned long next;
 421        unsigned long start;
 422
 423        start = addr;
 424        pmd = pmd_offset(pud, addr);
 425        do {
 426                next = pmd_addr_end(addr, end);
 427                if (pmd_none_or_clear_bad(pmd))
 428                        continue;
 429                free_pte_range(tlb, pmd, addr);
 430        } while (pmd++, addr = next, addr != end);
 431
 432        start &= PUD_MASK;
 433        if (start < floor)
 434                return;
 435        if (ceiling) {
 436                ceiling &= PUD_MASK;
 437                if (!ceiling)
 438                        return;
 439        }
 440        if (end - 1 > ceiling - 1)
 441                return;
 442
 443        pmd = pmd_offset(pud, start);
 444        pud_clear(pud);
 445        pmd_free_tlb(tlb, pmd, start);
 446}
 447
 448static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 449                                unsigned long addr, unsigned long end,
 450                                unsigned long floor, unsigned long ceiling)
 451{
 452        pud_t *pud;
 453        unsigned long next;
 454        unsigned long start;
 455
 456        start = addr;
 457        pud = pud_offset(pgd, addr);
 458        do {
 459                next = pud_addr_end(addr, end);
 460                if (pud_none_or_clear_bad(pud))
 461                        continue;
 462                free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 463        } while (pud++, addr = next, addr != end);
 464
 465        start &= PGDIR_MASK;
 466        if (start < floor)
 467                return;
 468        if (ceiling) {
 469                ceiling &= PGDIR_MASK;
 470                if (!ceiling)
 471                        return;
 472        }
 473        if (end - 1 > ceiling - 1)
 474                return;
 475
 476        pud = pud_offset(pgd, start);
 477        pgd_clear(pgd);
 478        pud_free_tlb(tlb, pud, start);
 479}
 480
 481/*
 482 * This function frees user-level page tables of a process.
 483 *
 484 * Must be called with pagetable lock held.
 485 */
 486void free_pgd_range(struct mmu_gather *tlb,
 487                        unsigned long addr, unsigned long end,
 488                        unsigned long floor, unsigned long ceiling)
 489{
 490        pgd_t *pgd;
 491        unsigned long next;
 492
 493        /*
 494         * The next few lines have given us lots of grief...
 495         *
 496         * Why are we testing PMD* at this top level?  Because often
 497         * there will be no work to do at all, and we'd prefer not to
 498         * go all the way down to the bottom just to discover that.
 499         *
 500         * Why all these "- 1"s?  Because 0 represents both the bottom
 501         * of the address space and the top of it (using -1 for the
 502         * top wouldn't help much: the masks would do the wrong thing).
 503         * The rule is that addr 0 and floor 0 refer to the bottom of
 504         * the address space, but end 0 and ceiling 0 refer to the top
 505         * Comparisons need to use "end - 1" and "ceiling - 1" (though
 506         * that end 0 case should be mythical).
 507         *
 508         * Wherever addr is brought up or ceiling brought down, we must
 509         * be careful to reject "the opposite 0" before it confuses the
 510         * subsequent tests.  But what about where end is brought down
 511         * by PMD_SIZE below? no, end can't go down to 0 there.
 512         *
 513         * Whereas we round start (addr) and ceiling down, by different
 514         * masks at different levels, in order to test whether a table
 515         * now has no other vmas using it, so can be freed, we don't
 516         * bother to round floor or end up - the tests don't need that.
 517         */
 518
 519        addr &= PMD_MASK;
 520        if (addr < floor) {
 521                addr += PMD_SIZE;
 522                if (!addr)
 523                        return;
 524        }
 525        if (ceiling) {
 526                ceiling &= PMD_MASK;
 527                if (!ceiling)
 528                        return;
 529        }
 530        if (end - 1 > ceiling - 1)
 531                end -= PMD_SIZE;
 532        if (addr > end - 1)
 533                return;
 534
 535        pgd = pgd_offset(tlb->mm, addr);
 536        do {
 537                next = pgd_addr_end(addr, end);
 538                if (pgd_none_or_clear_bad(pgd))
 539                        continue;
 540                free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 541        } while (pgd++, addr = next, addr != end);
 542}
 543
 544void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 545                unsigned long floor, unsigned long ceiling)
 546{
 547        while (vma) {
 548                struct vm_area_struct *next = vma->vm_next;
 549                unsigned long addr = vma->vm_start;
 550
 551                /*
 552                 * Hide vma from rmap and truncate_pagecache before freeing
 553                 * pgtables
 554                 */
 555                unlink_anon_vmas(vma);
 556                unlink_file_vma(vma);
 557
 558                if (is_vm_hugetlb_page(vma)) {
 559                        hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 560                                floor, next? next->vm_start: ceiling);
 561                } else {
 562                        /*
 563                         * Optimization: gather nearby vmas into one call down
 564                         */
 565                        while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 566                               && !is_vm_hugetlb_page(next)) {
 567                                vma = next;
 568                                next = vma->vm_next;
 569                                unlink_anon_vmas(vma);
 570                                unlink_file_vma(vma);
 571                        }
 572                        free_pgd_range(tlb, addr, vma->vm_end,
 573                                floor, next? next->vm_start: ceiling);
 574                }
 575                vma = next;
 576        }
 577}
 578
 579int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 580                pmd_t *pmd, unsigned long address)
 581{
 582        pgtable_t new = pte_alloc_one(mm, address);
 583        int wait_split_huge_page;
 584        if (!new)
 585                return -ENOMEM;
 586
 587        /*
 588         * Ensure all pte setup (eg. pte page lock and page clearing) are
 589         * visible before the pte is made visible to other CPUs by being
 590         * put into page tables.
 591         *
 592         * The other side of the story is the pointer chasing in the page
 593         * table walking code (when walking the page table without locking;
 594         * ie. most of the time). Fortunately, these data accesses consist
 595         * of a chain of data-dependent loads, meaning most CPUs (alpha
 596         * being the notable exception) will already guarantee loads are
 597         * seen in-order. See the alpha page table accessors for the
 598         * smp_read_barrier_depends() barriers in page table walking code.
 599         */
 600        smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 601
 602        spin_lock(&mm->page_table_lock);
 603        wait_split_huge_page = 0;
 604        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 605                mm->nr_ptes++;
 606                pmd_populate(mm, pmd, new);
 607                new = NULL;
 608        } else if (unlikely(pmd_trans_splitting(*pmd)))
 609                wait_split_huge_page = 1;
 610        spin_unlock(&mm->page_table_lock);
 611        if (new)
 612                pte_free(mm, new);
 613        if (wait_split_huge_page)
 614                wait_split_huge_page(vma->anon_vma, pmd);
 615        return 0;
 616}
 617
 618int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 619{
 620        pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 621        if (!new)
 622                return -ENOMEM;
 623
 624        smp_wmb(); /* See comment in __pte_alloc */
 625
 626        spin_lock(&init_mm.page_table_lock);
 627        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 628                pmd_populate_kernel(&init_mm, pmd, new);
 629                new = NULL;
 630        } else
 631                VM_BUG_ON(pmd_trans_splitting(*pmd));
 632        spin_unlock(&init_mm.page_table_lock);
 633        if (new)
 634                pte_free_kernel(&init_mm, new);
 635        return 0;
 636}
 637
 638static inline void init_rss_vec(int *rss)
 639{
 640        memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
 641}
 642
 643static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
 644{
 645        int i;
 646
 647        if (current->mm == mm)
 648                sync_mm_rss(mm);
 649        for (i = 0; i < NR_MM_COUNTERS; i++)
 650                if (rss[i])
 651                        add_mm_counter(mm, i, rss[i]);
 652}
 653
 654/*
 655 * This function is called to print an error when a bad pte
 656 * is found. For example, we might have a PFN-mapped pte in
 657 * a region that doesn't allow it.
 658 *
 659 * The calling function must still handle the error.
 660 */
 661static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 662                          pte_t pte, struct page *page)
 663{
 664        pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
 665        pud_t *pud = pud_offset(pgd, addr);
 666        pmd_t *pmd = pmd_offset(pud, addr);
 667        struct address_space *mapping;
 668        pgoff_t index;
 669        static unsigned long resume;
 670        static unsigned long nr_shown;
 671        static unsigned long nr_unshown;
 672
 673        /*
 674         * Allow a burst of 60 reports, then keep quiet for that minute;
 675         * or allow a steady drip of one report per second.
 676         */
 677        if (nr_shown == 60) {
 678                if (time_before(jiffies, resume)) {
 679                        nr_unshown++;
 680                        return;
 681                }
 682                if (nr_unshown) {
 683                        printk(KERN_ALERT
 684                                "BUG: Bad page map: %lu messages suppressed\n",
 685                                nr_unshown);
 686                        nr_unshown = 0;
 687                }
 688                nr_shown = 0;
 689        }
 690        if (nr_shown++ == 0)
 691                resume = jiffies + 60 * HZ;
 692
 693        mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 694        index = linear_page_index(vma, addr);
 695
 696        printk(KERN_ALERT
 697                "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
 698                current->comm,
 699                (long long)pte_val(pte), (long long)pmd_val(*pmd));
 700        if (page)
 701                dump_page(page);
 702        printk(KERN_ALERT
 703                "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
 704                (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
 705        /*
 706         * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 707         */
 708        if (vma->vm_ops)
 709                printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
 710                       vma->vm_ops->fault);
 711        if (vma->vm_file && vma->vm_file->f_op)
 712                printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
 713                       vma->vm_file->f_op->mmap);
 714        dump_stack();
 715        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 716}
 717
 718static inline bool is_cow_mapping(vm_flags_t flags)
 719{
 720        return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 721}
 722
 723/*
 724 * vm_normal_page -- This function gets the "struct page" associated with a pte.
 725 *
 726 * "Special" mappings do not wish to be associated with a "struct page" (either
 727 * it doesn't exist, or it exists but they don't want to touch it). In this
 728 * case, NULL is returned here. "Normal" mappings do have a struct page.
 729 *
 730 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 731 * pte bit, in which case this function is trivial. Secondly, an architecture
 732 * may not have a spare pte bit, which requires a more complicated scheme,
 733 * described below.
 734 *
 735 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 736 * special mapping (even if there are underlying and valid "struct pages").
 737 * COWed pages of a VM_PFNMAP are always normal.
 738 *
 739 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 740 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
 741 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 742 * mapping will always honor the rule
 743 *
 744 *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 745 *
 746 * And for normal mappings this is false.
 747 *
 748 * This restricts such mappings to be a linear translation from virtual address
 749 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 750 * as the vma is not a COW mapping; in that case, we know that all ptes are
 751 * special (because none can have been COWed).
 752 *
 753 *
 754 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
 755 *
 756 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 757 * page" backing, however the difference is that _all_ pages with a struct
 758 * page (that is, those where pfn_valid is true) are refcounted and considered
 759 * normal pages by the VM. The disadvantage is that pages are refcounted
 760 * (which can be slower and simply not an option for some PFNMAP users). The
 761 * advantage is that we don't have to follow the strict linearity rule of
 762 * PFNMAP mappings in order to support COWable mappings.
 763 *
 764 */
 765#ifdef __HAVE_ARCH_PTE_SPECIAL
 766# define HAVE_PTE_SPECIAL 1
 767#else
 768# define HAVE_PTE_SPECIAL 0
 769#endif
 770struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 771                                pte_t pte)
 772{
 773        unsigned long pfn = pte_pfn(pte);
 774
 775        if (HAVE_PTE_SPECIAL) {
 776                if (likely(!pte_special(pte)))
 777                        goto check_pfn;
 778                if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
 779                        return NULL;
 780                if (!is_zero_pfn(pfn))
 781                        print_bad_pte(vma, addr, pte, NULL);
 782                return NULL;
 783        }
 784
 785        /* !HAVE_PTE_SPECIAL case follows: */
 786
 787        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 788                if (vma->vm_flags & VM_MIXEDMAP) {
 789                        if (!pfn_valid(pfn))
 790                                return NULL;
 791                        goto out;
 792                } else {
 793                        unsigned long off;
 794                        off = (addr - vma->vm_start) >> PAGE_SHIFT;
 795                        if (pfn == vma->vm_pgoff + off)
 796                                return NULL;
 797                        if (!is_cow_mapping(vma->vm_flags))
 798                                return NULL;
 799                }
 800        }
 801
 802        if (is_zero_pfn(pfn))
 803                return NULL;
 804check_pfn:
 805        if (unlikely(pfn > highest_memmap_pfn)) {
 806                print_bad_pte(vma, addr, pte, NULL);
 807                return NULL;
 808        }
 809
 810        /*
 811         * NOTE! We still have PageReserved() pages in the page tables.
 812         * eg. VDSO mappings can cause them to exist.
 813         */
 814out:
 815        return pfn_to_page(pfn);
 816}
 817
 818/*
 819 * copy one vm_area from one task to the other. Assumes the page tables
 820 * already present in the new task to be cleared in the whole range
 821 * covered by this vma.
 822 */
 823
 824static inline unsigned long
 825copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 826                pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 827                unsigned long addr, int *rss)
 828{
 829        unsigned long vm_flags = vma->vm_flags;
 830        pte_t pte = *src_pte;
 831        struct page *page;
 832
 833        /* pte contains position in swap or file, so copy. */
 834        if (unlikely(!pte_present(pte))) {
 835                if (!pte_file(pte)) {
 836                        swp_entry_t entry = pte_to_swp_entry(pte);
 837
 838                        if (swap_duplicate(entry) < 0)
 839                                return entry.val;
 840
 841                        /* make sure dst_mm is on swapoff's mmlist. */
 842                        if (unlikely(list_empty(&dst_mm->mmlist))) {
 843                                spin_lock(&mmlist_lock);
 844                                if (list_empty(&dst_mm->mmlist))
 845                                        list_add(&dst_mm->mmlist,
 846                                                 &src_mm->mmlist);
 847                                spin_unlock(&mmlist_lock);
 848                        }
 849                        if (likely(!non_swap_entry(entry)))
 850                                rss[MM_SWAPENTS]++;
 851                        else if (is_migration_entry(entry)) {
 852                                page = migration_entry_to_page(entry);
 853
 854                                if (PageAnon(page))
 855                                        rss[MM_ANONPAGES]++;
 856                                else
 857                                        rss[MM_FILEPAGES]++;
 858
 859                                if (is_write_migration_entry(entry) &&
 860                                    is_cow_mapping(vm_flags)) {
 861                                        /*
 862                                         * COW mappings require pages in both
 863                                         * parent and child to be set to read.
 864                                         */
 865                                        make_migration_entry_read(&entry);
 866                                        pte = swp_entry_to_pte(entry);
 867                                        set_pte_at(src_mm, addr, src_pte, pte);
 868                                }
 869                        }
 870                }
 871                goto out_set_pte;
 872        }
 873
 874        /*
 875         * If it's a COW mapping, write protect it both
 876         * in the parent and the child
 877         */
 878        if (is_cow_mapping(vm_flags)) {
 879                ptep_set_wrprotect(src_mm, addr, src_pte);
 880                pte = pte_wrprotect(pte);
 881        }
 882
 883        /*
 884         * If it's a shared mapping, mark it clean in
 885         * the child
 886         */
 887        if (vm_flags & VM_SHARED)
 888                pte = pte_mkclean(pte);
 889        pte = pte_mkold(pte);
 890
 891        page = vm_normal_page(vma, addr, pte);
 892        if (page) {
 893                get_page(page);
 894                page_dup_rmap(page);
 895                if (PageAnon(page))
 896                        rss[MM_ANONPAGES]++;
 897                else
 898                        rss[MM_FILEPAGES]++;
 899        }
 900
 901out_set_pte:
 902        set_pte_at(dst_mm, addr, dst_pte, pte);
 903        return 0;
 904}
 905
 906int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 907                   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 908                   unsigned long addr, unsigned long end)
 909{
 910        pte_t *orig_src_pte, *orig_dst_pte;
 911        pte_t *src_pte, *dst_pte;
 912        spinlock_t *src_ptl, *dst_ptl;
 913        int progress = 0;
 914        int rss[NR_MM_COUNTERS];
 915        swp_entry_t entry = (swp_entry_t){0};
 916
 917again:
 918        init_rss_vec(rss);
 919
 920        dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 921        if (!dst_pte)
 922                return -ENOMEM;
 923        src_pte = pte_offset_map(src_pmd, addr);
 924        src_ptl = pte_lockptr(src_mm, src_pmd);
 925        spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 926        orig_src_pte = src_pte;
 927        orig_dst_pte = dst_pte;
 928        arch_enter_lazy_mmu_mode();
 929
 930        do {
 931                /*
 932                 * We are holding two locks at this point - either of them
 933                 * could generate latencies in another task on another CPU.
 934                 */
 935                if (progress >= 32) {
 936                        progress = 0;
 937                        if (need_resched() ||
 938                            spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
 939                                break;
 940                }
 941                if (pte_none(*src_pte)) {
 942                        progress++;
 943                        continue;
 944                }
 945                entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
 946                                                        vma, addr, rss);
 947                if (entry.val)
 948                        break;
 949                progress += 8;
 950        } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 951
 952        arch_leave_lazy_mmu_mode();
 953        spin_unlock(src_ptl);
 954        pte_unmap(orig_src_pte);
 955        add_mm_rss_vec(dst_mm, rss);
 956        pte_unmap_unlock(orig_dst_pte, dst_ptl);
 957        cond_resched();
 958
 959        if (entry.val) {
 960                if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
 961                        return -ENOMEM;
 962                progress = 0;
 963        }
 964        if (addr != end)
 965                goto again;
 966        return 0;
 967}
 968
 969static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 970                pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 971                unsigned long addr, unsigned long end)
 972{
 973        pmd_t *src_pmd, *dst_pmd;
 974        unsigned long next;
 975
 976        dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 977        if (!dst_pmd)
 978                return -ENOMEM;
 979        src_pmd = pmd_offset(src_pud, addr);
 980        do {
 981                next = pmd_addr_end(addr, end);
 982                if (pmd_trans_huge(*src_pmd)) {
 983                        int err;
 984                        VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
 985                        err = copy_huge_pmd(dst_mm, src_mm,
 986                                            dst_pmd, src_pmd, addr, vma);
 987                        if (err == -ENOMEM)
 988                                return -ENOMEM;
 989                        if (!err)
 990                                continue;
 991                        /* fall through */
 992                }
 993                if (pmd_none_or_clear_bad(src_pmd))
 994                        continue;
 995                if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
 996                                                vma, addr, next))
 997                        return -ENOMEM;
 998        } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 999        return 0;
1000}
1001
1002static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1003                pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1004                unsigned long addr, unsigned long end)
1005{
1006        pud_t *src_pud, *dst_pud;
1007        unsigned long next;
1008
1009        dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1010        if (!dst_pud)
1011                return -ENOMEM;
1012        src_pud = pud_offset(src_pgd, addr);
1013        do {
1014                next = pud_addr_end(addr, end);
1015                if (pud_none_or_clear_bad(src_pud))
1016                        continue;
1017                if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1018                                                vma, addr, next))
1019                        return -ENOMEM;
1020        } while (dst_pud++, src_pud++, addr = next, addr != end);
1021        return 0;
1022}
1023
1024int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1025                struct vm_area_struct *vma)
1026{
1027        pgd_t *src_pgd, *dst_pgd;
1028        unsigned long next;
1029        unsigned long addr = vma->vm_start;
1030        unsigned long end = vma->vm_end;
1031        unsigned long mmun_start;       /* For mmu_notifiers */
1032        unsigned long mmun_end;         /* For mmu_notifiers */
1033        bool is_cow;
1034        int ret;
1035
1036        /*
1037         * Don't copy ptes where a page fault will fill them correctly.
1038         * Fork becomes much lighter when there are big shared or private
1039         * readonly mappings. The tradeoff is that copy_page_range is more
1040         * efficient than faulting.
1041         */
1042        if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
1043                               VM_PFNMAP | VM_MIXEDMAP))) {
1044                if (!vma->anon_vma)
1045                        return 0;
1046        }
1047
1048        if (is_vm_hugetlb_page(vma))
1049                return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1050
1051        if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1052                /*
1053                 * We do not free on error cases below as remove_vma
1054                 * gets called on error from higher level routine
1055                 */
1056                ret = track_pfn_copy(vma);
1057                if (ret)
1058                        return ret;
1059        }
1060
1061        /*
1062         * We need to invalidate the secondary MMU mappings only when
1063         * there could be a permission downgrade on the ptes of the
1064         * parent mm. And a permission downgrade will only happen if
1065         * is_cow_mapping() returns true.
1066         */
1067        is_cow = is_cow_mapping(vma->vm_flags);
1068        mmun_start = addr;
1069        mmun_end   = end;
1070        if (is_cow)
1071                mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1072                                                    mmun_end);
1073
1074        ret = 0;
1075        dst_pgd = pgd_offset(dst_mm, addr);
1076        src_pgd = pgd_offset(src_mm, addr);
1077        do {
1078                next = pgd_addr_end(addr, end);
1079                if (pgd_none_or_clear_bad(src_pgd))
1080                        continue;
1081                if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1082                                            vma, addr, next))) {
1083                        ret = -ENOMEM;
1084                        break;
1085                }
1086        } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1087
1088        if (is_cow)
1089                mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1090        return ret;
1091}
1092
1093static unsigned long zap_pte_range(struct mmu_gather *tlb,
1094                                struct vm_area_struct *vma, pmd_t *pmd,
1095                                unsigned long addr, unsigned long end,
1096                                struct zap_details *details)
1097{
1098        struct mm_struct *mm = tlb->mm;
1099        int force_flush = 0;
1100        int rss[NR_MM_COUNTERS];
1101        spinlock_t *ptl;
1102        pte_t *start_pte;
1103        pte_t *pte;
1104
1105again:
1106        init_rss_vec(rss);
1107        start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1108        pte = start_pte;
1109        arch_enter_lazy_mmu_mode();
1110        do {
1111                pte_t ptent = *pte;
1112                if (pte_none(ptent)) {
1113                        continue;
1114                }
1115
1116                if (pte_present(ptent)) {
1117                        struct page *page;
1118
1119                        page = vm_normal_page(vma, addr, ptent);
1120                        if (unlikely(details) && page) {
1121                                /*
1122                                 * unmap_shared_mapping_pages() wants to
1123                                 * invalidate cache without truncating:
1124                                 * unmap shared but keep private pages.
1125                                 */
1126                                if (details->check_mapping &&
1127                                    details->check_mapping != page->mapping)
1128                                        continue;
1129                                /*
1130                                 * Each page->index must be checked when
1131                                 * invalidating or truncating nonlinear.
1132                                 */
1133                                if (details->nonlinear_vma &&
1134                                    (page->index < details->first_index ||
1135                                     page->index > details->last_index))
1136                                        continue;
1137                        }
1138                        ptent = ptep_get_and_clear_full(mm, addr, pte,
1139                                                        tlb->fullmm);
1140                        tlb_remove_tlb_entry(tlb, pte, addr);
1141                        if (unlikely(!page))
1142                                continue;
1143                        if (unlikely(details) && details->nonlinear_vma
1144                            && linear_page_index(details->nonlinear_vma,
1145                                                addr) != page->index)
1146                                set_pte_at(mm, addr, pte,
1147                                           pgoff_to_pte(page->index));
1148                        if (PageAnon(page))
1149                                rss[MM_ANONPAGES]--;
1150                        else {
1151                                if (pte_dirty(ptent))
1152                                        set_page_dirty(page);
1153                                if (pte_young(ptent) &&
1154                                    likely(!VM_SequentialReadHint(vma)))
1155                                        mark_page_accessed(page);
1156                                rss[MM_FILEPAGES]--;
1157                        }
1158                        page_remove_rmap(page);
1159                        if (unlikely(page_mapcount(page) < 0))
1160                                print_bad_pte(vma, addr, ptent, page);
1161                        force_flush = !__tlb_remove_page(tlb, page);
1162                        if (force_flush)
1163                                break;
1164                        continue;
1165                }
1166                /*
1167                 * If details->check_mapping, we leave swap entries;
1168                 * if details->nonlinear_vma, we leave file entries.
1169                 */
1170                if (unlikely(details))
1171                        continue;
1172                if (pte_file(ptent)) {
1173                        if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1174                                print_bad_pte(vma, addr, ptent, NULL);
1175                } else {
1176                        swp_entry_t entry = pte_to_swp_entry(ptent);
1177
1178                        if (!non_swap_entry(entry))
1179                                rss[MM_SWAPENTS]--;
1180                        else if (is_migration_entry(entry)) {
1181                                struct page *page;
1182
1183                                page = migration_entry_to_page(entry);
1184
1185                                if (PageAnon(page))
1186                                        rss[MM_ANONPAGES]--;
1187                                else
1188                                        rss[MM_FILEPAGES]--;
1189                        }
1190                        if (unlikely(!free_swap_and_cache(entry)))
1191                                print_bad_pte(vma, addr, ptent, NULL);
1192                }
1193                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1194        } while (pte++, addr += PAGE_SIZE, addr != end);
1195
1196        add_mm_rss_vec(mm, rss);
1197        arch_leave_lazy_mmu_mode();
1198        pte_unmap_unlock(start_pte, ptl);
1199
1200        /*
1201         * mmu_gather ran out of room to batch pages, we break out of
1202         * the PTE lock to avoid doing the potential expensive TLB invalidate
1203         * and page-free while holding it.
1204         */
1205        if (force_flush) {
1206                force_flush = 0;
1207
1208#ifdef HAVE_GENERIC_MMU_GATHER
1209                tlb->start = addr;
1210                tlb->end = end;
1211#endif
1212                tlb_flush_mmu(tlb);
1213                if (addr != end)
1214                        goto again;
1215        }
1216
1217        return addr;
1218}
1219
1220static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1221                                struct vm_area_struct *vma, pud_t *pud,
1222                                unsigned long addr, unsigned long end,
1223                                struct zap_details *details)
1224{
1225        pmd_t *pmd;
1226        unsigned long next;
1227
1228        pmd = pmd_offset(pud, addr);
1229        do {
1230                next = pmd_addr_end(addr, end);
1231                if (pmd_trans_huge(*pmd)) {
1232                        if (next - addr != HPAGE_PMD_SIZE) {
1233#ifdef CONFIG_DEBUG_VM
1234                                if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1235                                        pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1236                                                __func__, addr, end,
1237                                                vma->vm_start,
1238                                                vma->vm_end);
1239                                        BUG();
1240                                }
1241#endif
1242                                split_huge_page_pmd(vma, addr, pmd);
1243                        } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1244                                goto next;
1245                        /* fall through */
1246                }
1247                /*
1248                 * Here there can be other concurrent MADV_DONTNEED or
1249                 * trans huge page faults running, and if the pmd is
1250                 * none or trans huge it can change under us. This is
1251                 * because MADV_DONTNEED holds the mmap_sem in read
1252                 * mode.
1253                 */
1254                if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1255                        goto next;
1256                next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1257next:
1258                cond_resched();
1259        } while (pmd++, addr = next, addr != end);
1260
1261        return addr;
1262}
1263
1264static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1265                                struct vm_area_struct *vma, pgd_t *pgd,
1266                                unsigned long addr, unsigned long end,
1267                                struct zap_details *details)
1268{
1269        pud_t *pud;
1270        unsigned long next;
1271
1272        pud = pud_offset(pgd, addr);
1273        do {
1274                next = pud_addr_end(addr, end);
1275                if (pud_none_or_clear_bad(pud))
1276                        continue;
1277                next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1278        } while (pud++, addr = next, addr != end);
1279
1280        return addr;
1281}
1282
1283static void unmap_page_range(struct mmu_gather *tlb,
1284                             struct vm_area_struct *vma,
1285                             unsigned long addr, unsigned long end,
1286                             struct zap_details *details)
1287{
1288        pgd_t *pgd;
1289        unsigned long next;
1290
1291        if (details && !details->check_mapping && !details->nonlinear_vma)
1292                details = NULL;
1293
1294        BUG_ON(addr >= end);
1295        mem_cgroup_uncharge_start();
1296        tlb_start_vma(tlb, vma);
1297        pgd = pgd_offset(vma->vm_mm, addr);
1298        do {
1299                next = pgd_addr_end(addr, end);
1300                if (pgd_none_or_clear_bad(pgd))
1301                        continue;
1302                next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1303        } while (pgd++, addr = next, addr != end);
1304        tlb_end_vma(tlb, vma);
1305        mem_cgroup_uncharge_end();
1306}
1307
1308
1309static void unmap_single_vma(struct mmu_gather *tlb,
1310                struct vm_area_struct *vma, unsigned long start_addr,
1311                unsigned long end_addr,
1312                struct zap_details *details)
1313{
1314        unsigned long start = max(vma->vm_start, start_addr);
1315        unsigned long end;
1316
1317        if (start >= vma->vm_end)
1318                return;
1319        end = min(vma->vm_end, end_addr);
1320        if (end <= vma->vm_start)
1321                return;
1322
1323        if (vma->vm_file)
1324                uprobe_munmap(vma, start, end);
1325
1326        if (unlikely(vma->vm_flags & VM_PFNMAP))
1327                untrack_pfn(vma, 0, 0);
1328
1329        if (start != end) {
1330                if (unlikely(is_vm_hugetlb_page(vma))) {
1331                        /*
1332                         * It is undesirable to test vma->vm_file as it
1333                         * should be non-null for valid hugetlb area.
1334                         * However, vm_file will be NULL in the error
1335                         * cleanup path of do_mmap_pgoff. When
1336                         * hugetlbfs ->mmap method fails,
1337                         * do_mmap_pgoff() nullifies vma->vm_file
1338                         * before calling this function to clean up.
1339                         * Since no pte has actually been setup, it is
1340                         * safe to do nothing in this case.
1341                         */
1342                        if (vma->vm_file) {
1343                                mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1344                                __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1345                                mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1346                        }
1347                } else
1348                        unmap_page_range(tlb, vma, start, end, details);
1349        }
1350}
1351
1352/**
1353 * unmap_vmas - unmap a range of memory covered by a list of vma's
1354 * @tlb: address of the caller's struct mmu_gather
1355 * @vma: the starting vma
1356 * @start_addr: virtual address at which to start unmapping
1357 * @end_addr: virtual address at which to end unmapping
1358 *
1359 * Unmap all pages in the vma list.
1360 *
1361 * Only addresses between `start' and `end' will be unmapped.
1362 *
1363 * The VMA list must be sorted in ascending virtual address order.
1364 *
1365 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1366 * range after unmap_vmas() returns.  So the only responsibility here is to
1367 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1368 * drops the lock and schedules.
1369 */
1370void unmap_vmas(struct mmu_gather *tlb,
1371                struct vm_area_struct *vma, unsigned long start_addr,
1372                unsigned long end_addr)
1373{
1374        struct mm_struct *mm = vma->vm_mm;
1375
1376        mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1377        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1378                unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1379        mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1380}
1381
1382/**
1383 * zap_page_range - remove user pages in a given range
1384 * @vma: vm_area_struct holding the applicable pages
1385 * @start: starting address of pages to zap
1386 * @size: number of bytes to zap
1387 * @details: details of nonlinear truncation or shared cache invalidation
1388 *
1389 * Caller must protect the VMA list
1390 */
1391void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1392                unsigned long size, struct zap_details *details)
1393{
1394        struct mm_struct *mm = vma->vm_mm;
1395        struct mmu_gather tlb;
1396        unsigned long end = start + size;
1397
1398        lru_add_drain();
1399        tlb_gather_mmu(&tlb, mm, 0);
1400        update_hiwater_rss(mm);
1401        mmu_notifier_invalidate_range_start(mm, start, end);
1402        for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1403                unmap_single_vma(&tlb, vma, start, end, details);
1404        mmu_notifier_invalidate_range_end(mm, start, end);
1405        tlb_finish_mmu(&tlb, start, end);
1406}
1407
1408/**
1409 * zap_page_range_single - remove user pages in a given range
1410 * @vma: vm_area_struct holding the applicable pages
1411 * @address: starting address of pages to zap
1412 * @size: number of bytes to zap
1413 * @details: details of nonlinear truncation or shared cache invalidation
1414 *
1415 * The range must fit into one VMA.
1416 */
1417static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1418                unsigned long size, struct zap_details *details)
1419{
1420        struct mm_struct *mm = vma->vm_mm;
1421        struct mmu_gather tlb;
1422        unsigned long end = address + size;
1423
1424        lru_add_drain();
1425        tlb_gather_mmu(&tlb, mm, 0);
1426        update_hiwater_rss(mm);
1427        mmu_notifier_invalidate_range_start(mm, address, end);
1428        unmap_single_vma(&tlb, vma, address, end, details);
1429        mmu_notifier_invalidate_range_end(mm, address, end);
1430        tlb_finish_mmu(&tlb, address, end);
1431}
1432
1433/**
1434 * zap_vma_ptes - remove ptes mapping the vma
1435 * @vma: vm_area_struct holding ptes to be zapped
1436 * @address: starting address of pages to zap
1437 * @size: number of bytes to zap
1438 *
1439 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1440 *
1441 * The entire address range must be fully contained within the vma.
1442 *
1443 * Returns 0 if successful.
1444 */
1445int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1446                unsigned long size)
1447{
1448        if (address < vma->vm_start || address + size > vma->vm_end ||
1449                        !(vma->vm_flags & VM_PFNMAP))
1450                return -1;
1451        zap_page_range_single(vma, address, size, NULL);
1452        return 0;
1453}
1454EXPORT_SYMBOL_GPL(zap_vma_ptes);
1455
1456/**
1457 * follow_page_mask - look up a page descriptor from a user-virtual address
1458 * @vma: vm_area_struct mapping @address
1459 * @address: virtual address to look up
1460 * @flags: flags modifying lookup behaviour
1461 * @page_mask: on output, *page_mask is set according to the size of the page
1462 *
1463 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1464 *
1465 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1466 * an error pointer if there is a mapping to something not represented
1467 * by a page descriptor (see also vm_normal_page()).
1468 */
1469struct page *follow_page_mask(struct vm_area_struct *vma,
1470                              unsigned long address, unsigned int flags,
1471                              unsigned int *page_mask)
1472{
1473        pgd_t *pgd;
1474        pud_t *pud;
1475        pmd_t *pmd;
1476        pte_t *ptep, pte;
1477        spinlock_t *ptl;
1478        struct page *page;
1479        struct mm_struct *mm = vma->vm_mm;
1480
1481        *page_mask = 0;
1482
1483        page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1484        if (!IS_ERR(page)) {
1485                BUG_ON(flags & FOLL_GET);
1486                goto out;
1487        }
1488
1489        page = NULL;
1490        pgd = pgd_offset(mm, address);
1491        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1492                goto no_page_table;
1493
1494        pud = pud_offset(pgd, address);
1495        if (pud_none(*pud))
1496                goto no_page_table;
1497        if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1498                BUG_ON(flags & FOLL_GET);
1499                page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1500                goto out;
1501        }
1502        if (unlikely(pud_bad(*pud)))
1503                goto no_page_table;
1504
1505        pmd = pmd_offset(pud, address);
1506        if (pmd_none(*pmd))
1507                goto no_page_table;
1508        if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1509                BUG_ON(flags & FOLL_GET);
1510                page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1511                goto out;
1512        }
1513        if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1514                goto no_page_table;
1515        if (pmd_trans_huge(*pmd)) {
1516                if (flags & FOLL_SPLIT) {
1517                        split_huge_page_pmd(vma, address, pmd);
1518                        goto split_fallthrough;
1519                }
1520                spin_lock(&mm->page_table_lock);
1521                if (likely(pmd_trans_huge(*pmd))) {
1522                        if (unlikely(pmd_trans_splitting(*pmd))) {
1523                                spin_unlock(&mm->page_table_lock);
1524                                wait_split_huge_page(vma->anon_vma, pmd);
1525                        } else {
1526                                page = follow_trans_huge_pmd(vma, address,
1527                                                             pmd, flags);
1528                                spin_unlock(&mm->page_table_lock);
1529                                *page_mask = HPAGE_PMD_NR - 1;
1530                                goto out;
1531                        }
1532                } else
1533                        spin_unlock(&mm->page_table_lock);
1534                /* fall through */
1535        }
1536split_fallthrough:
1537        if (unlikely(pmd_bad(*pmd)))
1538                goto no_page_table;
1539
1540        ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1541
1542        pte = *ptep;
1543        if (!pte_present(pte)) {
1544                swp_entry_t entry;
1545                /*
1546                 * KSM's break_ksm() relies upon recognizing a ksm page
1547                 * even while it is being migrated, so for that case we
1548                 * need migration_entry_wait().
1549                 */
1550                if (likely(!(flags & FOLL_MIGRATION)))
1551                        goto no_page;
1552                if (pte_none(pte) || pte_file(pte))
1553                        goto no_page;
1554                entry = pte_to_swp_entry(pte);
1555                if (!is_migration_entry(entry))
1556                        goto no_page;
1557                pte_unmap_unlock(ptep, ptl);
1558                migration_entry_wait(mm, pmd, address);
1559                goto split_fallthrough;
1560        }
1561        if ((flags & FOLL_NUMA) && pte_numa(pte))
1562                goto no_page;
1563        if ((flags & FOLL_WRITE) && !pte_write(pte))
1564                goto unlock;
1565
1566        page = vm_normal_page(vma, address, pte);
1567        if (unlikely(!page)) {
1568                if ((flags & FOLL_DUMP) ||
1569                    !is_zero_pfn(pte_pfn(pte)))
1570                        goto bad_page;
1571                page = pte_page(pte);
1572        }
1573
1574        if (flags & FOLL_GET)
1575                get_page_foll(page);
1576        if (flags & FOLL_TOUCH) {
1577                if ((flags & FOLL_WRITE) &&
1578                    !pte_dirty(pte) && !PageDirty(page))
1579                        set_page_dirty(page);
1580                /*
1581                 * pte_mkyoung() would be more correct here, but atomic care
1582                 * is needed to avoid losing the dirty bit: it is easier to use
1583                 * mark_page_accessed().
1584                 */
1585                mark_page_accessed(page);
1586        }
1587        if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1588                /*
1589                 * The preliminary mapping check is mainly to avoid the
1590                 * pointless overhead of lock_page on the ZERO_PAGE
1591                 * which might bounce very badly if there is contention.
1592                 *
1593                 * If the page is already locked, we don't need to
1594                 * handle it now - vmscan will handle it later if and
1595                 * when it attempts to reclaim the page.
1596                 */
1597                if (page->mapping && trylock_page(page)) {
1598                        lru_add_drain();  /* push cached pages to LRU */
1599                        /*
1600                         * Because we lock page here, and migration is
1601                         * blocked by the pte's page reference, and we
1602                         * know the page is still mapped, we don't even
1603                         * need to check for file-cache page truncation.
1604                         */
1605                        mlock_vma_page(page);
1606                        unlock_page(page);
1607                }
1608        }
1609unlock:
1610        pte_unmap_unlock(ptep, ptl);
1611out:
1612        return page;
1613
1614bad_page:
1615        pte_unmap_unlock(ptep, ptl);
1616        return ERR_PTR(-EFAULT);
1617
1618no_page:
1619        pte_unmap_unlock(ptep, ptl);
1620        if (!pte_none(pte))
1621                return page;
1622
1623no_page_table:
1624        /*
1625         * When core dumping an enormous anonymous area that nobody
1626         * has touched so far, we don't want to allocate unnecessary pages or
1627         * page tables.  Return error instead of NULL to skip handle_mm_fault,
1628         * then get_dump_page() will return NULL to leave a hole in the dump.
1629         * But we can only make this optimization where a hole would surely
1630         * be zero-filled if handle_mm_fault() actually did handle it.
1631         */
1632        if ((flags & FOLL_DUMP) &&
1633            (!vma->vm_ops || !vma->vm_ops->fault))
1634                return ERR_PTR(-EFAULT);
1635        return page;
1636}
1637
1638static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1639{
1640        return stack_guard_page_start(vma, addr) ||
1641               stack_guard_page_end(vma, addr+PAGE_SIZE);
1642}
1643
1644/**
1645 * __get_user_pages() - pin user pages in memory
1646 * @tsk:        task_struct of target task
1647 * @mm:         mm_struct of target mm
1648 * @start:      starting user address
1649 * @nr_pages:   number of pages from start to pin
1650 * @gup_flags:  flags modifying pin behaviour
1651 * @pages:      array that receives pointers to the pages pinned.
1652 *              Should be at least nr_pages long. Or NULL, if caller
1653 *              only intends to ensure the pages are faulted in.
1654 * @vmas:       array of pointers to vmas corresponding to each page.
1655 *              Or NULL if the caller does not require them.
1656 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1657 *
1658 * Returns number of pages pinned. This may be fewer than the number
1659 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1660 * were pinned, returns -errno. Each page returned must be released
1661 * with a put_page() call when it is finished with. vmas will only
1662 * remain valid while mmap_sem is held.
1663 *
1664 * Must be called with mmap_sem held for read or write.
1665 *
1666 * __get_user_pages walks a process's page tables and takes a reference to
1667 * each struct page that each user address corresponds to at a given
1668 * instant. That is, it takes the page that would be accessed if a user
1669 * thread accesses the given user virtual address at that instant.
1670 *
1671 * This does not guarantee that the page exists in the user mappings when
1672 * __get_user_pages returns, and there may even be a completely different
1673 * page there in some cases (eg. if mmapped pagecache has been invalidated
1674 * and subsequently re faulted). However it does guarantee that the page
1675 * won't be freed completely. And mostly callers simply care that the page
1676 * contains data that was valid *at some point in time*. Typically, an IO
1677 * or similar operation cannot guarantee anything stronger anyway because
1678 * locks can't be held over the syscall boundary.
1679 *
1680 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1681 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1682 * appropriate) must be called after the page is finished with, and
1683 * before put_page is called.
1684 *
1685 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1686 * or mmap_sem contention, and if waiting is needed to pin all pages,
1687 * *@nonblocking will be set to 0.
1688 *
1689 * In most cases, get_user_pages or get_user_pages_fast should be used
1690 * instead of __get_user_pages. __get_user_pages should be used only if
1691 * you need some special @gup_flags.
1692 */
1693long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1694                unsigned long start, unsigned long nr_pages,
1695                unsigned int gup_flags, struct page **pages,
1696                struct vm_area_struct **vmas, int *nonblocking)
1697{
1698        long i;
1699        unsigned long vm_flags;
1700        unsigned int page_mask;
1701
1702        if (!nr_pages)
1703                return 0;
1704
1705        VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1706
1707        /* 
1708         * Require read or write permissions.
1709         * If FOLL_FORCE is set, we only require the "MAY" flags.
1710         */
1711        vm_flags  = (gup_flags & FOLL_WRITE) ?
1712                        (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1713        vm_flags &= (gup_flags & FOLL_FORCE) ?
1714                        (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1715
1716        /*
1717         * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
1718         * would be called on PROT_NONE ranges. We must never invoke
1719         * handle_mm_fault on PROT_NONE ranges or the NUMA hinting
1720         * page faults would unprotect the PROT_NONE ranges if
1721         * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
1722         * bitflag. So to avoid that, don't set FOLL_NUMA if
1723         * FOLL_FORCE is set.
1724         */
1725        if (!(gup_flags & FOLL_FORCE))
1726                gup_flags |= FOLL_NUMA;
1727
1728        i = 0;
1729
1730        do {
1731                struct vm_area_struct *vma;
1732
1733                vma = find_extend_vma(mm, start);
1734                if (!vma && in_gate_area(mm, start)) {
1735                        unsigned long pg = start & PAGE_MASK;
1736                        pgd_t *pgd;
1737                        pud_t *pud;
1738                        pmd_t *pmd;
1739                        pte_t *pte;
1740
1741                        /* user gate pages are read-only */
1742                        if (gup_flags & FOLL_WRITE)
1743                                return i ? : -EFAULT;
1744                        if (pg > TASK_SIZE)
1745                                pgd = pgd_offset_k(pg);
1746                        else
1747                                pgd = pgd_offset_gate(mm, pg);
1748                        BUG_ON(pgd_none(*pgd));
1749                        pud = pud_offset(pgd, pg);
1750                        BUG_ON(pud_none(*pud));
1751                        pmd = pmd_offset(pud, pg);
1752                        if (pmd_none(*pmd))
1753                                return i ? : -EFAULT;
1754                        VM_BUG_ON(pmd_trans_huge(*pmd));
1755                        pte = pte_offset_map(pmd, pg);
1756                        if (pte_none(*pte)) {
1757                                pte_unmap(pte);
1758                                return i ? : -EFAULT;
1759                        }
1760                        vma = get_gate_vma(mm);
1761                        if (pages) {
1762                                struct page *page;
1763
1764                                page = vm_normal_page(vma, start, *pte);
1765                                if (!page) {
1766                                        if (!(gup_flags & FOLL_DUMP) &&
1767                                             is_zero_pfn(pte_pfn(*pte)))
1768                                                page = pte_page(*pte);
1769                                        else {
1770                                                pte_unmap(pte);
1771                                                return i ? : -EFAULT;
1772                                        }
1773                                }
1774                                pages[i] = page;
1775                                get_page(page);
1776                        }
1777                        pte_unmap(pte);
1778                        page_mask = 0;
1779                        goto next_page;
1780                }
1781
1782                if (!vma ||
1783                    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1784                    !(vm_flags & vma->vm_flags))
1785                        return i ? : -EFAULT;
1786
1787                if (is_vm_hugetlb_page(vma)) {
1788                        i = follow_hugetlb_page(mm, vma, pages, vmas,
1789                                        &start, &nr_pages, i, gup_flags);
1790                        continue;
1791                }
1792
1793                do {
1794                        struct page *page;
1795                        unsigned int foll_flags = gup_flags;
1796                        unsigned int page_increm;
1797
1798                        /*
1799                         * If we have a pending SIGKILL, don't keep faulting
1800                         * pages and potentially allocating memory.
1801                         */
1802                        if (unlikely(fatal_signal_pending(current)))
1803                                return i ? i : -ERESTARTSYS;
1804
1805                        cond_resched();
1806                        while (!(page = follow_page_mask(vma, start,
1807                                                foll_flags, &page_mask))) {
1808                                int ret;
1809                                unsigned int fault_flags = 0;
1810
1811                                /* For mlock, just skip the stack guard page. */
1812                                if (foll_flags & FOLL_MLOCK) {
1813                                        if (stack_guard_page(vma, start))
1814                                                goto next_page;
1815                                }
1816                                if (foll_flags & FOLL_WRITE)
1817                                        fault_flags |= FAULT_FLAG_WRITE;
1818                                if (nonblocking)
1819                                        fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1820                                if (foll_flags & FOLL_NOWAIT)
1821                                        fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1822
1823                                ret = handle_mm_fault(mm, vma, start,
1824                                                        fault_flags);
1825
1826                                if (ret & VM_FAULT_ERROR) {
1827                                        if (ret & VM_FAULT_OOM)
1828                                                return i ? i : -ENOMEM;
1829                                        if (ret & (VM_FAULT_HWPOISON |
1830                                                   VM_FAULT_HWPOISON_LARGE)) {
1831                                                if (i)
1832                                                        return i;
1833                                                else if (gup_flags & FOLL_HWPOISON)
1834                                                        return -EHWPOISON;
1835                                                else
1836                                                        return -EFAULT;
1837                                        }
1838                                        if (ret & VM_FAULT_SIGBUS)
1839                                                return i ? i : -EFAULT;
1840                                        BUG();
1841                                }
1842
1843                                if (tsk) {
1844                                        if (ret & VM_FAULT_MAJOR)
1845                                                tsk->maj_flt++;
1846                                        else
1847                                                tsk->min_flt++;
1848                                }
1849
1850                                if (ret & VM_FAULT_RETRY) {
1851                                        if (nonblocking)
1852                                                *nonblocking = 0;
1853                                        return i;
1854                                }
1855
1856                                /*
1857                                 * The VM_FAULT_WRITE bit tells us that
1858                                 * do_wp_page has broken COW when necessary,
1859                                 * even if maybe_mkwrite decided not to set
1860                                 * pte_write. We can thus safely do subsequent
1861                                 * page lookups as if they were reads. But only
1862                                 * do so when looping for pte_write is futile:
1863                                 * in some cases userspace may also be wanting
1864                                 * to write to the gotten user page, which a
1865                                 * read fault here might prevent (a readonly
1866                                 * page might get reCOWed by userspace write).
1867                                 */
1868                                if ((ret & VM_FAULT_WRITE) &&
1869                                    !(vma->vm_flags & VM_WRITE))
1870                                        foll_flags &= ~FOLL_WRITE;
1871
1872                                cond_resched();
1873                        }
1874                        if (IS_ERR(page))
1875                                return i ? i : PTR_ERR(page);
1876                        if (pages) {
1877                                pages[i] = page;
1878
1879                                flush_anon_page(vma, page, start);
1880                                flush_dcache_page(page);
1881                                page_mask = 0;
1882                        }
1883next_page:
1884                        if (vmas) {
1885                                vmas[i] = vma;
1886                                page_mask = 0;
1887                        }
1888                        page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
1889                        if (page_increm > nr_pages)
1890                                page_increm = nr_pages;
1891                        i += page_increm;
1892                        start += page_increm * PAGE_SIZE;
1893                        nr_pages -= page_increm;
1894                } while (nr_pages && start < vma->vm_end);
1895        } while (nr_pages);
1896        return i;
1897}
1898EXPORT_SYMBOL(__get_user_pages);
1899
1900/*
1901 * fixup_user_fault() - manually resolve a user page fault
1902 * @tsk:        the task_struct to use for page fault accounting, or
1903 *              NULL if faults are not to be recorded.
1904 * @mm:         mm_struct of target mm
1905 * @address:    user address
1906 * @fault_flags:flags to pass down to handle_mm_fault()
1907 *
1908 * This is meant to be called in the specific scenario where for locking reasons
1909 * we try to access user memory in atomic context (within a pagefault_disable()
1910 * section), this returns -EFAULT, and we want to resolve the user fault before
1911 * trying again.
1912 *
1913 * Typically this is meant to be used by the futex code.
1914 *
1915 * The main difference with get_user_pages() is that this function will
1916 * unconditionally call handle_mm_fault() which will in turn perform all the
1917 * necessary SW fixup of the dirty and young bits in the PTE, while
1918 * handle_mm_fault() only guarantees to update these in the struct page.
1919 *
1920 * This is important for some architectures where those bits also gate the
1921 * access permission to the page because they are maintained in software.  On
1922 * such architectures, gup() will not be enough to make a subsequent access
1923 * succeed.
1924 *
1925 * This should be called with the mm_sem held for read.
1926 */
1927int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1928                     unsigned long address, unsigned int fault_flags)
1929{
1930        struct vm_area_struct *vma;
1931        int ret;
1932
1933        vma = find_extend_vma(mm, address);
1934        if (!vma || address < vma->vm_start)
1935                return -EFAULT;
1936
1937        ret = handle_mm_fault(mm, vma, address, fault_flags);
1938        if (ret & VM_FAULT_ERROR) {
1939                if (ret & VM_FAULT_OOM)
1940                        return -ENOMEM;
1941                if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1942                        return -EHWPOISON;
1943                if (ret & VM_FAULT_SIGBUS)
1944                        return -EFAULT;
1945                BUG();
1946        }
1947        if (tsk) {
1948                if (ret & VM_FAULT_MAJOR)
1949                        tsk->maj_flt++;
1950                else
1951                        tsk->min_flt++;
1952        }
1953        return 0;
1954}
1955
1956/*
1957 * get_user_pages() - pin user pages in memory
1958 * @tsk:        the task_struct to use for page fault accounting, or
1959 *              NULL if faults are not to be recorded.
1960 * @mm:         mm_struct of target mm
1961 * @start:      starting user address
1962 * @nr_pages:   number of pages from start to pin
1963 * @write:      whether pages will be written to by the caller
1964 * @force:      whether to force write access even if user mapping is
1965 *              readonly. This will result in the page being COWed even
1966 *              in MAP_SHARED mappings. You do not want this.
1967 * @pages:      array that receives pointers to the pages pinned.
1968 *              Should be at least nr_pages long. Or NULL, if caller
1969 *              only intends to ensure the pages are faulted in.
1970 * @vmas:       array of pointers to vmas corresponding to each page.
1971 *              Or NULL if the caller does not require them.
1972 *
1973 * Returns number of pages pinned. This may be fewer than the number
1974 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1975 * were pinned, returns -errno. Each page returned must be released
1976 * with a put_page() call when it is finished with. vmas will only
1977 * remain valid while mmap_sem is held.
1978 *
1979 * Must be called with mmap_sem held for read or write.
1980 *
1981 * get_user_pages walks a process's page tables and takes a reference to
1982 * each struct page that each user address corresponds to at a given
1983 * instant. That is, it takes the page that would be accessed if a user
1984 * thread accesses the given user virtual address at that instant.
1985 *
1986 * This does not guarantee that the page exists in the user mappings when
1987 * get_user_pages returns, and there may even be a completely different
1988 * page there in some cases (eg. if mmapped pagecache has been invalidated
1989 * and subsequently re faulted). However it does guarantee that the page
1990 * won't be freed completely. And mostly callers simply care that the page
1991 * contains data that was valid *at some point in time*. Typically, an IO
1992 * or similar operation cannot guarantee anything stronger anyway because
1993 * locks can't be held over the syscall boundary.
1994 *
1995 * If write=0, the page must not be written to. If the page is written to,
1996 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1997 * after the page is finished with, and before put_page is called.
1998 *
1999 * get_user_pages is typically used for fewer-copy IO operations, to get a
2000 * handle on the memory by some means other than accesses via the user virtual
2001 * addresses. The pages may be submitted for DMA to devices or accessed via
2002 * their kernel linear mapping (via the kmap APIs). Care should be taken to
2003 * use the correct cache flushing APIs.
2004 *
2005 * See also get_user_pages_fast, for performance critical applications.
2006 */
2007long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
2008                unsigned long start, unsigned long nr_pages, int write,
2009                int force, struct page **pages, struct vm_area_struct **vmas)
2010{
2011        int flags = FOLL_TOUCH;
2012
2013        if (pages)
2014                flags |= FOLL_GET;
2015        if (write)
2016                flags |= FOLL_WRITE;
2017        if (force)
2018                flags |= FOLL_FORCE;
2019
2020        return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
2021                                NULL);
2022}
2023EXPORT_SYMBOL(get_user_pages);
2024
2025/**
2026 * get_dump_page() - pin user page in memory while writing it to core dump
2027 * @addr: user address
2028 *
2029 * Returns struct page pointer of user page pinned for dump,
2030 * to be freed afterwards by page_cache_release() or put_page().
2031 *
2032 * Returns NULL on any kind of failure - a hole must then be inserted into
2033 * the corefile, to preserve alignment with its headers; and also returns
2034 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
2035 * allowing a hole to be left in the corefile to save diskspace.
2036 *
2037 * Called without mmap_sem, but after all other threads have been killed.
2038 */
2039#ifdef CONFIG_ELF_CORE
2040struct page *get_dump_page(unsigned long addr)
2041{
2042        struct vm_area_struct *vma;
2043        struct page *page;
2044
2045        if (__get_user_pages(current, current->mm, addr, 1,
2046                             FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
2047                             NULL) < 1)
2048                return NULL;
2049        flush_cache_page(vma, addr, page_to_pfn(page));
2050        return page;
2051}
2052#endif /* CONFIG_ELF_CORE */
2053
2054pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
2055                        spinlock_t **ptl)
2056{
2057        pgd_t * pgd = pgd_offset(mm, addr);
2058        pud_t * pud = pud_alloc(mm, pgd, addr);
2059        if (pud) {
2060                pmd_t * pmd = pmd_alloc(mm, pud, addr);
2061                if (pmd) {
2062                        VM_BUG_ON(pmd_trans_huge(*pmd));
2063                        return pte_alloc_map_lock(mm, pmd, addr, ptl);
2064                }
2065        }
2066        return NULL;
2067}
2068
2069/*
2070 * This is the old fallback for page remapping.
2071 *
2072 * For historical reasons, it only allows reserved pages. Only
2073 * old drivers should use this, and they needed to mark their
2074 * pages reserved for the old functions anyway.
2075 */
2076static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2077                        struct page *page, pgprot_t prot)
2078{
2079        struct mm_struct *mm = vma->vm_mm;
2080        int retval;
2081        pte_t *pte;
2082        spinlock_t *ptl;
2083
2084        retval = -EINVAL;
2085        if (PageAnon(page))
2086                goto out;
2087        retval = -ENOMEM;
2088        flush_dcache_page(page);
2089        pte = get_locked_pte(mm, addr, &ptl);
2090        if (!pte)
2091                goto out;
2092        retval = -EBUSY;
2093        if (!pte_none(*pte))
2094                goto out_unlock;
2095
2096        /* Ok, finally just insert the thing.. */
2097        get_page(page);
2098        inc_mm_counter_fast(mm, MM_FILEPAGES);
2099        page_add_file_rmap(page);
2100        set_pte_at(mm, addr, pte, mk_pte(page, prot));
2101
2102        retval = 0;
2103        pte_unmap_unlock(pte, ptl);
2104        return retval;
2105out_unlock:
2106        pte_unmap_unlock(pte, ptl);
2107out:
2108        return retval;
2109}
2110
2111/**
2112 * vm_insert_page - insert single page into user vma
2113 * @vma: user vma to map to
2114 * @addr: target user address of this page
2115 * @page: source kernel page
2116 *
2117 * This allows drivers to insert individual pages they've allocated
2118 * into a user vma.
2119 *
2120 * The page has to be a nice clean _individual_ kernel allocation.
2121 * If you allocate a compound page, you need to have marked it as
2122 * such (__GFP_COMP), or manually just split the page up yourself
2123 * (see split_page()).
2124 *
2125 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2126 * took an arbitrary page protection parameter. This doesn't allow
2127 * that. Your vma protection will have to be set up correctly, which
2128 * means that if you want a shared writable mapping, you'd better
2129 * ask for a shared writable mapping!
2130 *
2131 * The page does not need to be reserved.
2132 *
2133 * Usually this function is called from f_op->mmap() handler
2134 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
2135 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2136 * function from other places, for example from page-fault handler.
2137 */
2138int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2139                        struct page *page)
2140{
2141        if (addr < vma->vm_start || addr >= vma->vm_end)
2142                return -EFAULT;
2143        if (!page_count(page))
2144                return -EINVAL;
2145        if (!(vma->vm_flags & VM_MIXEDMAP)) {
2146                BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
2147                BUG_ON(vma->vm_flags & VM_PFNMAP);
2148                vma->vm_flags |= VM_MIXEDMAP;
2149        }
2150        return insert_page(vma, addr, page, vma->vm_page_prot);
2151}
2152EXPORT_SYMBOL(vm_insert_page);
2153
2154static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2155                        unsigned long pfn, pgprot_t prot)
2156{
2157        struct mm_struct *mm = vma->vm_mm;
2158        int retval;
2159        pte_t *pte, entry;
2160        spinlock_t *ptl;
2161
2162        retval = -ENOMEM;
2163        pte = get_locked_pte(mm, addr, &ptl);
2164        if (!pte)
2165                goto out;
2166        retval = -EBUSY;
2167        if (!pte_none(*pte))
2168                goto out_unlock;
2169
2170        /* Ok, finally just insert the thing.. */
2171        entry = pte_mkspecial(pfn_pte(pfn, prot));
2172        set_pte_at(mm, addr, pte, entry);
2173        update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2174
2175        retval = 0;
2176out_unlock:
2177        pte_unmap_unlock(pte, ptl);
2178out:
2179        return retval;
2180}
2181
2182/**
2183 * vm_insert_pfn - insert single pfn into user vma
2184 * @vma: user vma to map to
2185 * @addr: target user address of this page
2186 * @pfn: source kernel pfn
2187 *
2188 * Similar to vm_insert_page, this allows drivers to insert individual pages
2189 * they've allocated into a user vma. Same comments apply.
2190 *
2191 * This function should only be called from a vm_ops->fault handler, and
2192 * in that case the handler should return NULL.
2193 *
2194 * vma cannot be a COW mapping.
2195 *
2196 * As this is called only for pages that do not currently exist, we
2197 * do not need to flush old virtual caches or the TLB.
2198 */
2199int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2200                        unsigned long pfn)
2201{
2202        int ret;
2203        pgprot_t pgprot = vma->vm_page_prot;
2204        /*
2205         * Technically, architectures with pte_special can avoid all these
2206         * restrictions (same for remap_pfn_range).  However we would like
2207         * consistency in testing and feature parity among all, so we should
2208         * try to keep these invariants in place for everybody.
2209         */
2210        BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2211        BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2212                                                (VM_PFNMAP|VM_MIXEDMAP));
2213        BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2214        BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2215
2216        if (addr < vma->vm_start || addr >= vma->vm_end)
2217                return -EFAULT;
2218        if (track_pfn_insert(vma, &pgprot, pfn))
2219                return -EINVAL;
2220
2221        ret = insert_pfn(vma, addr, pfn, pgprot);
2222
2223        return ret;
2224}
2225EXPORT_SYMBOL(vm_insert_pfn);
2226
2227int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2228                        unsigned long pfn)
2229{
2230        BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2231
2232        if (addr < vma->vm_start || addr >= vma->vm_end)
2233                return -EFAULT;
2234
2235        /*
2236         * If we don't have pte special, then we have to use the pfn_valid()
2237         * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2238         * refcount the page if pfn_valid is true (hence insert_page rather
2239         * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2240         * without pte special, it would there be refcounted as a normal page.
2241         */
2242        if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2243                struct page *page;
2244
2245                page = pfn_to_page(pfn);
2246                return insert_page(vma, addr, page, vma->vm_page_prot);
2247        }
2248        return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2249}
2250EXPORT_SYMBOL(vm_insert_mixed);
2251
2252/*
2253 * maps a range of physical memory into the requested pages. the old
2254 * mappings are removed. any references to nonexistent pages results
2255 * in null mappings (currently treated as "copy-on-access")
2256 */
2257static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2258                        unsigned long addr, unsigned long end,
2259                        unsigned long pfn, pgprot_t prot)
2260{
2261        pte_t *pte;
2262        spinlock_t *ptl;
2263
2264        pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2265        if (!pte)
2266                return -ENOMEM;
2267        arch_enter_lazy_mmu_mode();
2268        do {
2269                BUG_ON(!pte_none(*pte));
2270                set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2271                pfn++;
2272        } while (pte++, addr += PAGE_SIZE, addr != end);
2273        arch_leave_lazy_mmu_mode();
2274        pte_unmap_unlock(pte - 1, ptl);
2275        return 0;
2276}
2277
2278static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2279                        unsigned long addr, unsigned long end,
2280                        unsigned long pfn, pgprot_t prot)
2281{
2282        pmd_t *pmd;
2283        unsigned long next;
2284
2285        pfn -= addr >> PAGE_SHIFT;
2286        pmd = pmd_alloc(mm, pud, addr);
2287        if (!pmd)
2288                return -ENOMEM;
2289        VM_BUG_ON(pmd_trans_huge(*pmd));
2290        do {
2291                next = pmd_addr_end(addr, end);
2292                if (remap_pte_range(mm, pmd, addr, next,
2293                                pfn + (addr >> PAGE_SHIFT), prot))
2294                        return -ENOMEM;
2295        } while (pmd++, addr = next, addr != end);
2296        return 0;
2297}
2298
2299static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2300                        unsigned long addr, unsigned long end,
2301                        unsigned long pfn, pgprot_t prot)
2302{
2303        pud_t *pud;
2304        unsigned long next;
2305
2306        pfn -= addr >> PAGE_SHIFT;
2307        pud = pud_alloc(mm, pgd, addr);
2308        if (!pud)
2309                return -ENOMEM;
2310        do {
2311                next = pud_addr_end(addr, end);
2312                if (remap_pmd_range(mm, pud, addr, next,
2313                                pfn + (addr >> PAGE_SHIFT), prot))
2314                        return -ENOMEM;
2315        } while (pud++, addr = next, addr != end);
2316        return 0;
2317}
2318
2319/**
2320 * remap_pfn_range - remap kernel memory to userspace
2321 * @vma: user vma to map to
2322 * @addr: target user address to start at
2323 * @pfn: physical address of kernel memory
2324 * @size: size of map area
2325 * @prot: page protection flags for this mapping
2326 *
2327 *  Note: this is only safe if the mm semaphore is held when called.
2328 */
2329int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2330                    unsigned long pfn, unsigned long size, pgprot_t prot)
2331{
2332        pgd_t *pgd;
2333        unsigned long next;
2334        unsigned long end = addr + PAGE_ALIGN(size);
2335        struct mm_struct *mm = vma->vm_mm;
2336        int err;
2337
2338        /*
2339         * Physically remapped pages are special. Tell the
2340         * rest of the world about it:
2341         *   VM_IO tells people not to look at these pages
2342         *      (accesses can have side effects).
2343         *   VM_PFNMAP tells the core MM that the base pages are just
2344         *      raw PFN mappings, and do not have a "struct page" associated
2345         *      with them.
2346         *   VM_DONTEXPAND
2347         *      Disable vma merging and expanding with mremap().
2348         *   VM_DONTDUMP
2349         *      Omit vma from core dump, even when VM_IO turned off.
2350         *
2351         * There's a horrible special case to handle copy-on-write
2352         * behaviour that some programs depend on. We mark the "original"
2353         * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2354         * See vm_normal_page() for details.
2355         */
2356        if (is_cow_mapping(vma->vm_flags)) {
2357                if (addr != vma->vm_start || end != vma->vm_end)
2358                        return -EINVAL;
2359                vma->vm_pgoff = pfn;
2360        }
2361
2362        err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2363        if (err)
2364                return -EINVAL;
2365
2366        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2367
2368        BUG_ON(addr >= end);
2369        pfn -= addr >> PAGE_SHIFT;
2370        pgd = pgd_offset(mm, addr);
2371        flush_cache_range(vma, addr, end);
2372        do {
2373                next = pgd_addr_end(addr, end);
2374                err = remap_pud_range(mm, pgd, addr, next,
2375                                pfn + (addr >> PAGE_SHIFT), prot);
2376                if (err)
2377                        break;
2378        } while (pgd++, addr = next, addr != end);
2379
2380        if (err)
2381                untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2382
2383        return err;
2384}
2385EXPORT_SYMBOL(remap_pfn_range);
2386
2387/**
2388 * vm_iomap_memory - remap memory to userspace
2389 * @vma: user vma to map to
2390 * @start: start of area
2391 * @len: size of area
2392 *
2393 * This is a simplified io_remap_pfn_range() for common driver use. The
2394 * driver just needs to give us the physical memory range to be mapped,
2395 * we'll figure out the rest from the vma information.
2396 *
2397 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2398 * whatever write-combining details or similar.
2399 */
2400int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2401{
2402        unsigned long vm_len, pfn, pages;
2403
2404        /* Check that the physical memory area passed in looks valid */
2405        if (start + len < start)
2406                return -EINVAL;
2407        /*
2408         * You *really* shouldn't map things that aren't page-aligned,
2409         * but we've historically allowed it because IO memory might
2410         * just have smaller alignment.
2411         */
2412        len += start & ~PAGE_MASK;
2413        pfn = start >> PAGE_SHIFT;
2414        pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2415        if (pfn + pages < pfn)
2416                return -EINVAL;
2417
2418        /* We start the mapping 'vm_pgoff' pages into the area */
2419        if (vma->vm_pgoff > pages)
2420                return -EINVAL;
2421        pfn += vma->vm_pgoff;
2422        pages -= vma->vm_pgoff;
2423
2424        /* Can we fit all of the mapping? */
2425        vm_len = vma->vm_end - vma->vm_start;
2426        if (vm_len >> PAGE_SHIFT > pages)
2427                return -EINVAL;
2428
2429        /* Ok, let it rip */
2430        return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2431}
2432EXPORT_SYMBOL(vm_iomap_memory);
2433
2434static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2435                                     unsigned long addr, unsigned long end,
2436                                     pte_fn_t fn, void *data)
2437{
2438        pte_t *pte;
2439        int err;
2440        pgtable_t token;
2441        spinlock_t *uninitialized_var(ptl);
2442
2443        pte = (mm == &init_mm) ?
2444                pte_alloc_kernel(pmd, addr) :
2445                pte_alloc_map_lock(mm, pmd, addr, &ptl);
2446        if (!pte)
2447                return -ENOMEM;
2448
2449        BUG_ON(pmd_huge(*pmd));
2450
2451        arch_enter_lazy_mmu_mode();
2452
2453        token = pmd_pgtable(*pmd);
2454
2455        do {
2456                err = fn(pte++, token, addr, data);
2457                if (err)
2458                        break;
2459        } while (addr += PAGE_SIZE, addr != end);
2460
2461        arch_leave_lazy_mmu_mode();
2462
2463        if (mm != &init_mm)
2464                pte_unmap_unlock(pte-1, ptl);
2465        return err;
2466}
2467
2468static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2469                                     unsigned long addr, unsigned long end,
2470                                     pte_fn_t fn, void *data)
2471{
2472        pmd_t *pmd;
2473        unsigned long next;
2474        int err;
2475
2476        BUG_ON(pud_huge(*pud));
2477
2478        pmd = pmd_alloc(mm, pud, addr);
2479        if (!pmd)
2480                return -ENOMEM;
2481        do {
2482                next = pmd_addr_end(addr, end);
2483                err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2484                if (err)
2485                        break;
2486        } while (pmd++, addr = next, addr != end);
2487        return err;
2488}
2489
2490static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2491                                     unsigned long addr, unsigned long end,
2492                                     pte_fn_t fn, void *data)
2493{
2494        pud_t *pud;
2495        unsigned long next;
2496        int err;
2497
2498        pud = pud_alloc(mm, pgd, addr);
2499        if (!pud)
2500                return -ENOMEM;
2501        do {
2502                next = pud_addr_end(addr, end);
2503                err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2504                if (err)
2505                        break;
2506        } while (pud++, addr = next, addr != end);
2507        return err;
2508}
2509
2510/*
2511 * Scan a region of virtual memory, filling in page tables as necessary
2512 * and calling a provided function on each leaf page table.
2513 */
2514int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2515                        unsigned long size, pte_fn_t fn, void *data)
2516{
2517        pgd_t *pgd;
2518        unsigned long next;
2519        unsigned long end = addr + size;
2520        int err;
2521
2522        BUG_ON(addr >= end);
2523        pgd = pgd_offset(mm, addr);
2524        do {
2525                next = pgd_addr_end(addr, end);
2526                err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2527                if (err)
2528                        break;
2529        } while (pgd++, addr = next, addr != end);
2530
2531        return err;
2532}
2533EXPORT_SYMBOL_GPL(apply_to_page_range);
2534
2535/*
2536 * handle_pte_fault chooses page fault handler according to an entry
2537 * which was read non-atomically.  Before making any commitment, on
2538 * those architectures or configurations (e.g. i386 with PAE) which
2539 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2540 * must check under lock before unmapping the pte and proceeding
2541 * (but do_wp_page is only called after already making such a check;
2542 * and do_anonymous_page can safely check later on).
2543 */
2544static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2545                                pte_t *page_table, pte_t orig_pte)
2546{
2547        int same = 1;
2548#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2549        if (sizeof(pte_t) > sizeof(unsigned long)) {
2550                spinlock_t *ptl = pte_lockptr(mm, pmd);
2551                spin_lock(ptl);
2552                same = pte_same(*page_table, orig_pte);
2553                spin_unlock(ptl);
2554        }
2555#endif
2556        pte_unmap(page_table);
2557        return same;
2558}
2559
2560static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2561{
2562        /*
2563         * If the source page was a PFN mapping, we don't have
2564         * a "struct page" for it. We do a best-effort copy by
2565         * just copying from the original user address. If that
2566         * fails, we just zero-fill it. Live with it.
2567         */
2568        if (unlikely(!src)) {
2569                void *kaddr = kmap_atomic(dst);
2570                void __user *uaddr = (void __user *)(va & PAGE_MASK);
2571
2572                /*
2573                 * This really shouldn't fail, because the page is there
2574                 * in the page tables. But it might just be unreadable,
2575                 * in which case we just give up and fill the result with
2576                 * zeroes.
2577                 */
2578                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2579                        clear_page(kaddr);
2580                kunmap_atomic(kaddr);
2581                flush_dcache_page(dst);
2582        } else
2583                copy_user_highpage(dst, src, va, vma);
2584}
2585
2586/*
2587 * This routine handles present pages, when users try to write
2588 * to a shared page. It is done by copying the page to a new address
2589 * and decrementing the shared-page counter for the old page.
2590 *
2591 * Note that this routine assumes that the protection checks have been
2592 * done by the caller (the low-level page fault routine in most cases).
2593 * Thus we can safely just mark it writable once we've done any necessary
2594 * COW.
2595 *
2596 * We also mark the page dirty at this point even though the page will
2597 * change only once the write actually happens. This avoids a few races,
2598 * and potentially makes it more efficient.
2599 *
2600 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2601 * but allow concurrent faults), with pte both mapped and locked.
2602 * We return with mmap_sem still held, but pte unmapped and unlocked.
2603 */
2604static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2605                unsigned long address, pte_t *page_table, pmd_t *pmd,
2606                spinlock_t *ptl, pte_t orig_pte)
2607        __releases(ptl)
2608{
2609        struct page *old_page, *new_page = NULL;
2610        pte_t entry;
2611        int ret = 0;
2612        int page_mkwrite = 0;
2613        struct page *dirty_page = NULL;
2614        unsigned long mmun_start = 0;   /* For mmu_notifiers */
2615        unsigned long mmun_end = 0;     /* For mmu_notifiers */
2616
2617        old_page = vm_normal_page(vma, address, orig_pte);
2618        if (!old_page) {
2619                /*
2620                 * VM_MIXEDMAP !pfn_valid() case
2621                 *
2622                 * We should not cow pages in a shared writeable mapping.
2623                 * Just mark the pages writable as we can't do any dirty
2624                 * accounting on raw pfn maps.
2625                 */
2626                if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2627                                     (VM_WRITE|VM_SHARED))
2628                        goto reuse;
2629                goto gotten;
2630        }
2631
2632        /*
2633         * Take out anonymous pages first, anonymous shared vmas are
2634         * not dirty accountable.
2635         */
2636        if (PageAnon(old_page) && !PageKsm(old_page)) {
2637                if (!trylock_page(old_page)) {
2638                        page_cache_get(old_page);
2639                        pte_unmap_unlock(page_table, ptl);
2640                        lock_page(old_page);
2641                        page_table = pte_offset_map_lock(mm, pmd, address,
2642                                                         &ptl);
2643                        if (!pte_same(*page_table, orig_pte)) {
2644                                unlock_page(old_page);
2645                                goto unlock;
2646                        }
2647                        page_cache_release(old_page);
2648                }
2649                if (reuse_swap_page(old_page)) {
2650                        /*
2651                         * The page is all ours.  Move it to our anon_vma so
2652                         * the rmap code will not search our parent or siblings.
2653                         * Protected against the rmap code by the page lock.
2654                         */
2655                        page_move_anon_rmap(old_page, vma, address);
2656                        unlock_page(old_page);
2657                        goto reuse;
2658                }
2659                unlock_page(old_page);
2660        } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2661                                        (VM_WRITE|VM_SHARED))) {
2662                /*
2663                 * Only catch write-faults on shared writable pages,
2664                 * read-only shared pages can get COWed by
2665                 * get_user_pages(.write=1, .force=1).
2666                 */
2667                if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2668                        struct vm_fault vmf;
2669                        int tmp;
2670
2671                        vmf.virtual_address = (void __user *)(address &
2672                                                                PAGE_MASK);
2673                        vmf.pgoff = old_page->index;
2674                        vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2675                        vmf.page = old_page;
2676
2677                        /*
2678                         * Notify the address space that the page is about to
2679                         * become writable so that it can prohibit this or wait
2680                         * for the page to get into an appropriate state.
2681                         *
2682                         * We do this without the lock held, so that it can
2683                         * sleep if it needs to.
2684                         */
2685                        page_cache_get(old_page);
2686                        pte_unmap_unlock(page_table, ptl);
2687
2688                        tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2689                        if (unlikely(tmp &
2690                                        (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2691                                ret = tmp;
2692                                goto unwritable_page;
2693                        }
2694                        if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2695                                lock_page(old_page);
2696                                if (!old_page->mapping) {
2697                                        ret = 0; /* retry the fault */
2698                                        unlock_page(old_page);
2699                                        goto unwritable_page;
2700                                }
2701                        } else
2702                                VM_BUG_ON(!PageLocked(old_page));
2703
2704                        /*
2705                         * Since we dropped the lock we need to revalidate
2706                         * the PTE as someone else may have changed it.  If
2707                         * they did, we just return, as we can count on the
2708                         * MMU to tell us if they didn't also make it writable.
2709                         */
2710                        page_table = pte_offset_map_lock(mm, pmd, address,
2711                                                         &ptl);
2712                        if (!pte_same(*page_table, orig_pte)) {
2713                                unlock_page(old_page);
2714                                goto unlock;
2715                        }
2716
2717                        page_mkwrite = 1;
2718                }
2719                dirty_page = old_page;
2720                get_page(dirty_page);
2721
2722reuse:
2723                flush_cache_page(vma, address, pte_pfn(orig_pte));
2724                entry = pte_mkyoung(orig_pte);
2725                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2726                if (ptep_set_access_flags(vma, address, page_table, entry,1))
2727                        update_mmu_cache(vma, address, page_table);
2728                pte_unmap_unlock(page_table, ptl);
2729                ret |= VM_FAULT_WRITE;
2730
2731                if (!dirty_page)
2732                        return ret;
2733
2734                /*
2735                 * Yes, Virginia, this is actually required to prevent a race
2736                 * with clear_page_dirty_for_io() from clearing the page dirty
2737                 * bit after it clear all dirty ptes, but before a racing
2738                 * do_wp_page installs a dirty pte.
2739                 *
2740                 * __do_fault is protected similarly.
2741                 */
2742                if (!page_mkwrite) {
2743                        wait_on_page_locked(dirty_page);
2744                        set_page_dirty_balance(dirty_page, page_mkwrite);
2745                        /* file_update_time outside page_lock */
2746                        if (vma->vm_file)
2747                                file_update_time(vma->vm_file);
2748                }
2749                put_page(dirty_page);
2750                if (page_mkwrite) {
2751                        struct address_space *mapping = dirty_page->mapping;
2752
2753                        set_page_dirty(dirty_page);
2754                        unlock_page(dirty_page);
2755                        page_cache_release(dirty_page);
2756                        if (mapping)    {
2757                                /*
2758                                 * Some device drivers do not set page.mapping
2759                                 * but still dirty their pages
2760                                 */
2761                                balance_dirty_pages_ratelimited(mapping);
2762                        }
2763                }
2764
2765                return ret;
2766        }
2767
2768        /*
2769         * Ok, we need to copy. Oh, well..
2770         */
2771        page_cache_get(old_page);
2772gotten:
2773        pte_unmap_unlock(page_table, ptl);
2774
2775        if (unlikely(anon_vma_prepare(vma)))
2776                goto oom;
2777
2778        if (is_zero_pfn(pte_pfn(orig_pte))) {
2779                new_page = alloc_zeroed_user_highpage_movable(vma, address);
2780                if (!new_page)
2781                        goto oom;
2782        } else {
2783                new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2784                if (!new_page)
2785                        goto oom;
2786                cow_user_page(new_page, old_page, address, vma);
2787        }
2788        __SetPageUptodate(new_page);
2789
2790        if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2791                goto oom_free_new;
2792
2793        mmun_start  = address & PAGE_MASK;
2794        mmun_end    = mmun_start + PAGE_SIZE;
2795        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2796
2797        /*
2798         * Re-check the pte - we dropped the lock
2799         */
2800        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2801        if (likely(pte_same(*page_table, orig_pte))) {
2802                if (old_page) {
2803                        if (!PageAnon(old_page)) {
2804                                dec_mm_counter_fast(mm, MM_FILEPAGES);
2805                                inc_mm_counter_fast(mm, MM_ANONPAGES);
2806                        }
2807                } else
2808                        inc_mm_counter_fast(mm, MM_ANONPAGES);
2809                flush_cache_page(vma, address, pte_pfn(orig_pte));
2810                entry = mk_pte(new_page, vma->vm_page_prot);
2811                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2812                /*
2813                 * Clear the pte entry and flush it first, before updating the
2814                 * pte with the new entry. This will avoid a race condition
2815                 * seen in the presence of one thread doing SMC and another
2816                 * thread doing COW.
2817                 */
2818                ptep_clear_flush(vma, address, page_table);
2819                page_add_new_anon_rmap(new_page, vma, address);
2820                /*
2821                 * We call the notify macro here because, when using secondary
2822                 * mmu page tables (such as kvm shadow page tables), we want the
2823                 * new page to be mapped directly into the secondary page table.
2824                 */
2825                set_pte_at_notify(mm, address, page_table, entry);
2826                update_mmu_cache(vma, address, page_table);
2827                if (old_page) {
2828                        /*
2829                         * Only after switching the pte to the new page may
2830                         * we remove the mapcount here. Otherwise another
2831                         * process may come and find the rmap count decremented
2832                         * before the pte is switched to the new page, and
2833                         * "reuse" the old page writing into it while our pte
2834                         * here still points into it and can be read by other
2835                         * threads.
2836                         *
2837                         * The critical issue is to order this
2838                         * page_remove_rmap with the ptp_clear_flush above.
2839                         * Those stores are ordered by (if nothing else,)
2840                         * the barrier present in the atomic_add_negative
2841                         * in page_remove_rmap.
2842                         *
2843                         * Then the TLB flush in ptep_clear_flush ensures that
2844                         * no process can access the old page before the
2845                         * decremented mapcount is visible. And the old page
2846                         * cannot be reused until after the decremented
2847                         * mapcount is visible. So transitively, TLBs to
2848                         * old page will be flushed before it can be reused.
2849                         */
2850                        page_remove_rmap(old_page);
2851                }
2852
2853                /* Free the old page.. */
2854                new_page = old_page;
2855                ret |= VM_FAULT_WRITE;
2856        } else
2857                mem_cgroup_uncharge_page(new_page);
2858
2859        if (new_page)
2860                page_cache_release(new_page);
2861unlock:
2862        pte_unmap_unlock(page_table, ptl);
2863        if (mmun_end > mmun_start)
2864                mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2865        if (old_page) {
2866                /*
2867                 * Don't let another task, with possibly unlocked vma,
2868                 * keep the mlocked page.
2869                 */
2870                if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2871                        lock_page(old_page);    /* LRU manipulation */
2872                        munlock_vma_page(old_page);
2873                        unlock_page(old_page);
2874                }
2875                page_cache_release(old_page);
2876        }
2877        return ret;
2878oom_free_new:
2879        page_cache_release(new_page);
2880oom:
2881        if (old_page)
2882                page_cache_release(old_page);
2883        return VM_FAULT_OOM;
2884
2885unwritable_page:
2886        page_cache_release(old_page);
2887        return ret;
2888}
2889
2890static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2891                unsigned long start_addr, unsigned long end_addr,
2892                struct zap_details *details)
2893{
2894        zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2895}
2896
2897static inline void unmap_mapping_range_tree(struct rb_root *root,
2898                                            struct zap_details *details)
2899{
2900        struct vm_area_struct *vma;
2901        pgoff_t vba, vea, zba, zea;
2902
2903        vma_interval_tree_foreach(vma, root,
2904                        details->first_index, details->last_index) {
2905
2906                vba = vma->vm_pgoff;
2907                vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2908                /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2909                zba = details->first_index;
2910                if (zba < vba)
2911                        zba = vba;
2912                zea = details->last_index;
2913                if (zea > vea)
2914                        zea = vea;
2915
2916                unmap_mapping_range_vma(vma,
2917                        ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2918                        ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2919                                details);
2920        }
2921}
2922
2923static inline void unmap_mapping_range_list(struct list_head *head,
2924                                            struct zap_details *details)
2925{
2926        struct vm_area_struct *vma;
2927
2928        /*
2929         * In nonlinear VMAs there is no correspondence between virtual address
2930         * offset and file offset.  So we must perform an exhaustive search
2931         * across *all* the pages in each nonlinear VMA, not just the pages
2932         * whose virtual address lies outside the file truncation point.
2933         */
2934        list_for_each_entry(vma, head, shared.nonlinear) {
2935                details->nonlinear_vma = vma;
2936                unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2937        }
2938}
2939
2940/**
2941 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2942 * @mapping: the address space containing mmaps to be unmapped.
2943 * @holebegin: byte in first page to unmap, relative to the start of
2944 * the underlying file.  This will be rounded down to a PAGE_SIZE
2945 * boundary.  Note that this is different from truncate_pagecache(), which
2946 * must keep the partial page.  In contrast, we must get rid of
2947 * partial pages.
2948 * @holelen: size of prospective hole in bytes.  This will be rounded
2949 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2950 * end of the file.
2951 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2952 * but 0 when invalidating pagecache, don't throw away private data.
2953 */
2954void unmap_mapping_range(struct address_space *mapping,
2955                loff_t const holebegin, loff_t const holelen, int even_cows)
2956{
2957        struct zap_details details;
2958        pgoff_t hba = holebegin >> PAGE_SHIFT;
2959        pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2960
2961        /* Check for overflow. */
2962        if (sizeof(holelen) > sizeof(hlen)) {
2963                long long holeend =
2964                        (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2965                if (holeend & ~(long long)ULONG_MAX)
2966                        hlen = ULONG_MAX - hba + 1;
2967        }
2968
2969        details.check_mapping = even_cows? NULL: mapping;
2970        details.nonlinear_vma = NULL;
2971        details.first_index = hba;
2972        details.last_index = hba + hlen - 1;
2973        if (details.last_index < details.first_index)
2974                details.last_index = ULONG_MAX;
2975
2976
2977        mutex_lock(&mapping->i_mmap_mutex);
2978        if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2979                unmap_mapping_range_tree(&mapping->i_mmap, &details);
2980        if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2981                unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2982        mutex_unlock(&mapping->i_mmap_mutex);
2983}
2984EXPORT_SYMBOL(unmap_mapping_range);
2985
2986/*
2987 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2988 * but allow concurrent faults), and pte mapped but not yet locked.
2989 * We return with mmap_sem still held, but pte unmapped and unlocked.
2990 */
2991static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2992                unsigned long address, pte_t *page_table, pmd_t *pmd,
2993                unsigned int flags, pte_t orig_pte)
2994{
2995        spinlock_t *ptl;
2996        struct page *page, *swapcache;
2997        swp_entry_t entry;
2998        pte_t pte;
2999        int locked;
3000        struct mem_cgroup *ptr;
3001        int exclusive = 0;
3002        int ret = 0;
3003
3004        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3005                goto out;
3006
3007        entry = pte_to_swp_entry(orig_pte);
3008        if (unlikely(non_swap_entry(entry))) {
3009                if (is_migration_entry(entry)) {
3010                        migration_entry_wait(mm, pmd, address);
3011                } else if (is_hwpoison_entry(entry)) {
3012                        ret = VM_FAULT_HWPOISON;
3013                } else {
3014                        print_bad_pte(vma, address, orig_pte, NULL);
3015                        ret = VM_FAULT_SIGBUS;
3016                }
3017                goto out;
3018        }
3019        delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3020        page = lookup_swap_cache(entry);
3021        if (!page) {
3022                page = swapin_readahead(entry,
3023                                        GFP_HIGHUSER_MOVABLE, vma, address);
3024                if (!page) {
3025                        /*
3026                         * Back out if somebody else faulted in this pte
3027                         * while we released the pte lock.
3028                         */
3029                        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3030                        if (likely(pte_same(*page_table, orig_pte)))
3031                                ret = VM_FAULT_OOM;
3032                        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3033                        goto unlock;
3034                }
3035
3036                /* Had to read the page from swap area: Major fault */
3037                ret = VM_FAULT_MAJOR;
3038                count_vm_event(PGMAJFAULT);
3039                mem_cgroup_count_vm_event(mm, PGMAJFAULT);
3040        } else if (PageHWPoison(page)) {
3041                /*
3042                 * hwpoisoned dirty swapcache pages are kept for killing
3043                 * owner processes (which may be unknown at hwpoison time)
3044                 */
3045                ret = VM_FAULT_HWPOISON;
3046                delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3047                swapcache = page;
3048                goto out_release;
3049        }
3050
3051        swapcache = page;
3052        locked = lock_page_or_retry(page, mm, flags);
3053
3054        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3055        if (!locked) {
3056                ret |= VM_FAULT_RETRY;
3057                goto out_release;
3058        }
3059
3060        /*
3061         * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3062         * release the swapcache from under us.  The page pin, and pte_same
3063         * test below, are not enough to exclude that.  Even if it is still
3064         * swapcache, we need to check that the page's swap has not changed.
3065         */
3066        if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
3067                goto out_page;
3068
3069        page = ksm_might_need_to_copy(page, vma, address);
3070        if (unlikely(!page)) {
3071                ret = VM_FAULT_OOM;
3072                page = swapcache;
3073                goto out_page;
3074        }
3075
3076        if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3077                ret = VM_FAULT_OOM;
3078                goto out_page;
3079        }
3080
3081        /*
3082         * Back out if somebody else already faulted in this pte.
3083         */
3084        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3085        if (unlikely(!pte_same(*page_table, orig_pte)))
3086                goto out_nomap;
3087
3088        if (unlikely(!PageUptodate(page))) {
3089                ret = VM_FAULT_SIGBUS;
3090                goto out_nomap;
3091        }
3092
3093        /*
3094         * The page isn't present yet, go ahead with the fault.
3095         *
3096         * Be careful about the sequence of operations here.
3097         * To get its accounting right, reuse_swap_page() must be called
3098         * while the page is counted on swap but not yet in mapcount i.e.
3099         * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3100         * must be called after the swap_free(), or it will never succeed.
3101         * Because delete_from_swap_page() may be called by reuse_swap_page(),
3102         * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3103         * in page->private. In this case, a record in swap_cgroup  is silently
3104         * discarded at swap_free().
3105         */
3106
3107        inc_mm_counter_fast(mm, MM_ANONPAGES);
3108        dec_mm_counter_fast(mm, MM_SWAPENTS);
3109        pte = mk_pte(page, vma->vm_page_prot);
3110        if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3111                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3112                flags &= ~FAULT_FLAG_WRITE;
3113                ret |= VM_FAULT_WRITE;
3114                exclusive = 1;
3115        }
3116        flush_icache_page(vma, page);
3117        set_pte_at(mm, address, page_table, pte);
3118        if (page == swapcache)
3119                do_page_add_anon_rmap(page, vma, address, exclusive);
3120        else /* ksm created a completely new copy */
3121                page_add_new_anon_rmap(page, vma, address);
3122        /* It's better to call commit-charge after rmap is established */
3123        mem_cgroup_commit_charge_swapin(page, ptr);
3124
3125        swap_free(entry);
3126        if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3127                try_to_free_swap(page);
3128        unlock_page(page);
3129        if (page != swapcache) {
3130                /*
3131                 * Hold the lock to avoid the swap entry to be reused
3132                 * until we take the PT lock for the pte_same() check
3133                 * (to avoid false positives from pte_same). For
3134                 * further safety release the lock after the swap_free
3135                 * so that the swap count won't change under a
3136                 * parallel locked swapcache.
3137                 */
3138                unlock_page(swapcache);
3139                page_cache_release(swapcache);
3140        }
3141
3142        if (flags & FAULT_FLAG_WRITE) {
3143                ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3144                if (ret & VM_FAULT_ERROR)
3145                        ret &= VM_FAULT_ERROR;
3146                goto out;
3147        }
3148
3149        /* No need to invalidate - it was non-present before */
3150        update_mmu_cache(vma, address, page_table);
3151unlock:
3152        pte_unmap_unlock(page_table, ptl);
3153out:
3154        return ret;
3155out_nomap:
3156        mem_cgroup_cancel_charge_swapin(ptr);
3157        pte_unmap_unlock(page_table, ptl);
3158out_page:
3159        unlock_page(page);
3160out_release:
3161        page_cache_release(page);
3162        if (page != swapcache) {
3163                unlock_page(swapcache);
3164                page_cache_release(swapcache);
3165        }
3166        return ret;
3167}
3168
3169/*
3170 * This is like a special single-page "expand_{down|up}wards()",
3171 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3172 * doesn't hit another vma.
3173 */
3174static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3175{
3176        address &= PAGE_MASK;
3177        if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3178                struct vm_area_struct *prev = vma->vm_prev;
3179
3180                /*
3181                 * Is there a mapping abutting this one below?
3182                 *
3183                 * That's only ok if it's the same stack mapping
3184                 * that has gotten split..
3185                 */
3186                if (prev && prev->vm_end == address)
3187                        return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3188
3189                expand_downwards(vma, address - PAGE_SIZE);
3190        }
3191        if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3192                struct vm_area_struct *next = vma->vm_next;
3193
3194                /* As VM_GROWSDOWN but s/below/above/ */
3195                if (next && next->vm_start == address + PAGE_SIZE)
3196                        return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3197
3198                expand_upwards(vma, address + PAGE_SIZE);
3199        }
3200        return 0;
3201}
3202
3203/*
3204 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3205 * but allow concurrent faults), and pte mapped but not yet locked.
3206 * We return with mmap_sem still held, but pte unmapped and unlocked.
3207 */
3208static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3209                unsigned long address, pte_t *page_table, pmd_t *pmd,
3210                unsigned int flags)
3211{
3212        struct page *page;
3213        spinlock_t *ptl;
3214        pte_t entry;
3215
3216        pte_unmap(page_table);
3217
3218        /* Check if we need to add a guard page to the stack */
3219        if (check_stack_guard_page(vma, address) < 0)
3220                return VM_FAULT_SIGBUS;
3221
3222        /* Use the zero-page for reads */
3223        if (!(flags & FAULT_FLAG_WRITE)) {
3224                entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3225                                                vma->vm_page_prot));
3226                page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3227                if (!pte_none(*page_table))
3228                        goto unlock;
3229                goto setpte;
3230        }
3231
3232        /* Allocate our own private page. */
3233        if (unlikely(anon_vma_prepare(vma)))
3234                goto oom;
3235        page = alloc_zeroed_user_highpage_movable(vma, address);
3236        if (!page)
3237                goto oom;
3238        /*
3239         * The memory barrier inside __SetPageUptodate makes sure that
3240         * preceeding stores to the page contents become visible before
3241         * the set_pte_at() write.
3242         */
3243        __SetPageUptodate(page);
3244
3245        if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3246                goto oom_free_page;
3247
3248        entry = mk_pte(page, vma->vm_page_prot);
3249        if (vma->vm_flags & VM_WRITE)
3250                entry = pte_mkwrite(pte_mkdirty(entry));
3251
3252        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3253        if (!pte_none(*page_table))
3254                goto release;
3255
3256        inc_mm_counter_fast(mm, MM_ANONPAGES);
3257        page_add_new_anon_rmap(page, vma, address);
3258setpte:
3259        set_pte_at(mm, address, page_table, entry);
3260
3261        /* No need to invalidate - it was non-present before */
3262        update_mmu_cache(vma, address, page_table);
3263unlock:
3264        pte_unmap_unlock(page_table, ptl);
3265        return 0;
3266release:
3267        mem_cgroup_uncharge_page(page);
3268        page_cache_release(page);
3269        goto unlock;
3270oom_free_page:
3271        page_cache_release(page);
3272oom:
3273        return VM_FAULT_OOM;
3274}
3275
3276/*
3277 * __do_fault() tries to create a new page mapping. It aggressively
3278 * tries to share with existing pages, but makes a separate copy if
3279 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3280 * the next page fault.
3281 *
3282 * As this is called only for pages that do not currently exist, we
3283 * do not need to flush old virtual caches or the TLB.
3284 *
3285 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3286 * but allow concurrent faults), and pte neither mapped nor locked.
3287 * We return with mmap_sem still held, but pte unmapped and unlocked.
3288 */
3289static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3290                unsigned long address, pmd_t *pmd,
3291                pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3292{
3293        pte_t *page_table;
3294        spinlock_t *ptl;
3295        struct page *page;
3296        struct page *cow_page;
3297        pte_t entry;
3298        int anon = 0;
3299        struct page *dirty_page = NULL;
3300        struct vm_fault vmf;
3301        int ret;
3302        int page_mkwrite = 0;
3303
3304        /*
3305         * If we do COW later, allocate page befor taking lock_page()
3306         * on the file cache page. This will reduce lock holding time.
3307         */
3308        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3309
3310                if (unlikely(anon_vma_prepare(vma)))
3311                        return VM_FAULT_OOM;
3312
3313                cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3314                if (!cow_page)
3315                        return VM_FAULT_OOM;
3316
3317                if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3318                        page_cache_release(cow_page);
3319                        return VM_FAULT_OOM;
3320                }
3321        } else
3322                cow_page = NULL;
3323
3324        vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3325        vmf.pgoff = pgoff;
3326        vmf.flags = flags;
3327        vmf.page = NULL;
3328
3329        ret = vma->vm_ops->fault(vma, &vmf);
3330        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3331                            VM_FAULT_RETRY)))
3332                goto uncharge_out;
3333
3334        if (unlikely(PageHWPoison(vmf.page))) {
3335                if (ret & VM_FAULT_LOCKED)
3336                        unlock_page(vmf.page);
3337                ret = VM_FAULT_HWPOISON;
3338                goto uncharge_out;
3339        }
3340
3341        /*
3342         * For consistency in subsequent calls, make the faulted page always
3343         * locked.
3344         */
3345        if (unlikely(!(ret & VM_FAULT_LOCKED)))
3346                lock_page(vmf.page);
3347        else
3348                VM_BUG_ON(!PageLocked(vmf.page));
3349
3350        /*
3351         * Should we do an early C-O-W break?
3352         */
3353        page = vmf.page;
3354        if (flags & FAULT_FLAG_WRITE) {
3355                if (!(vma->vm_flags & VM_SHARED)) {
3356                        page = cow_page;
3357                        anon = 1;
3358                        copy_user_highpage(page, vmf.page, address, vma);
3359                        __SetPageUptodate(page);
3360                } else {
3361                        /*
3362                         * If the page will be shareable, see if the backing
3363                         * address space wants to know that the page is about
3364                         * to become writable
3365                         */
3366                        if (vma->vm_ops->page_mkwrite) {
3367                                int tmp;
3368
3369                                unlock_page(page);
3370                                vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3371                                tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3372                                if (unlikely(tmp &
3373                                          (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3374                                        ret = tmp;
3375                                        goto unwritable_page;
3376                                }
3377                                if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3378                                        lock_page(page);
3379                                        if (!page->mapping) {
3380                                                ret = 0; /* retry the fault */
3381                                                unlock_page(page);
3382                                                goto unwritable_page;
3383                                        }
3384                                } else
3385                                        VM_BUG_ON(!PageLocked(page));
3386                                page_mkwrite = 1;
3387                        }
3388                }
3389
3390        }
3391
3392        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3393
3394        /*
3395         * This silly early PAGE_DIRTY setting removes a race
3396         * due to the bad i386 page protection. But it's valid
3397         * for other architectures too.
3398         *
3399         * Note that if FAULT_FLAG_WRITE is set, we either now have
3400         * an exclusive copy of the page, or this is a shared mapping,
3401         * so we can make it writable and dirty to avoid having to
3402         * handle that later.
3403         */
3404        /* Only go through if we didn't race with anybody else... */
3405        if (likely(pte_same(*page_table, orig_pte))) {
3406                flush_icache_page(vma, page);
3407                entry = mk_pte(page, vma->vm_page_prot);
3408                if (flags & FAULT_FLAG_WRITE)
3409                        entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3410                if (anon) {
3411                        inc_mm_counter_fast(mm, MM_ANONPAGES);
3412                        page_add_new_anon_rmap(page, vma, address);
3413                } else {
3414                        inc_mm_counter_fast(mm, MM_FILEPAGES);
3415                        page_add_file_rmap(page);
3416                        if (flags & FAULT_FLAG_WRITE) {
3417                                dirty_page = page;
3418                                get_page(dirty_page);
3419                        }
3420                }
3421                set_pte_at(mm, address, page_table, entry);
3422
3423                /* no need to invalidate: a not-present page won't be cached */
3424                update_mmu_cache(vma, address, page_table);
3425        } else {
3426                if (cow_page)
3427                        mem_cgroup_uncharge_page(cow_page);
3428                if (anon)
3429                        page_cache_release(page);
3430                else
3431                        anon = 1; /* no anon but release faulted_page */
3432        }
3433
3434        pte_unmap_unlock(page_table, ptl);
3435
3436        if (dirty_page) {
3437                struct address_space *mapping = page->mapping;
3438                int dirtied = 0;
3439
3440                if (set_page_dirty(dirty_page))
3441                        dirtied = 1;
3442                unlock_page(dirty_page);
3443                put_page(dirty_page);
3444                if ((dirtied || page_mkwrite) && mapping) {
3445                        /*
3446                         * Some device drivers do not set page.mapping but still
3447                         * dirty their pages
3448                         */
3449                        balance_dirty_pages_ratelimited(mapping);
3450                }
3451
3452                /* file_update_time outside page_lock */
3453                if (vma->vm_file && !page_mkwrite)
3454                        file_update_time(vma->vm_file);
3455        } else {
3456                unlock_page(vmf.page);
3457                if (anon)
3458                        page_cache_release(vmf.page);
3459        }
3460
3461        return ret;
3462
3463unwritable_page:
3464        page_cache_release(page);
3465        return ret;
3466uncharge_out:
3467        /* fs's fault handler get error */
3468        if (cow_page) {
3469                mem_cgroup_uncharge_page(cow_page);
3470                page_cache_release(cow_page);
3471        }
3472        return ret;
3473}
3474
3475static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3476                unsigned long address, pte_t *page_table, pmd_t *pmd,
3477                unsigned int flags, pte_t orig_pte)
3478{
3479        pgoff_t pgoff = (((address & PAGE_MASK)
3480                        - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3481
3482        pte_unmap(page_table);
3483        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3484}
3485
3486/*
3487 * Fault of a previously existing named mapping. Repopulate the pte
3488 * from the encoded file_pte if possible. This enables swappable
3489 * nonlinear vmas.
3490 *
3491 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3492 * but allow concurrent faults), and pte mapped but not yet locked.
3493 * We return with mmap_sem still held, but pte unmapped and unlocked.
3494 */
3495static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3496                unsigned long address, pte_t *page_table, pmd_t *pmd,
3497                unsigned int flags, pte_t orig_pte)
3498{
3499        pgoff_t pgoff;
3500
3501        flags |= FAULT_FLAG_NONLINEAR;
3502
3503        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3504                return 0;
3505
3506        if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3507                /*
3508                 * Page table corrupted: show pte and kill process.
3509                 */
3510                print_bad_pte(vma, address, orig_pte, NULL);
3511                return VM_FAULT_SIGBUS;
3512        }
3513
3514        pgoff = pte_to_pgoff(orig_pte);
3515        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3516}
3517
3518int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3519                                unsigned long addr, int current_nid)
3520{
3521        get_page(page);
3522
3523        count_vm_numa_event(NUMA_HINT_FAULTS);
3524        if (current_nid == numa_node_id())
3525                count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3526
3527        return mpol_misplaced(page, vma, addr);
3528}
3529
3530int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3531                   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3532{
3533        struct page *page = NULL;
3534        spinlock_t *ptl;
3535        int current_nid = -1;
3536        int target_nid;
3537        bool migrated = false;
3538
3539        /*
3540        * The "pte" at this point cannot be used safely without
3541        * validation through pte_unmap_same(). It's of NUMA type but
3542        * the pfn may be screwed if the read is non atomic.
3543        *
3544        * ptep_modify_prot_start is not called as this is clearing
3545        * the _PAGE_NUMA bit and it is not really expected that there
3546        * would be concurrent hardware modifications to the PTE.
3547        */
3548        ptl = pte_lockptr(mm, pmd);
3549        spin_lock(ptl);
3550        if (unlikely(!pte_same(*ptep, pte))) {
3551                pte_unmap_unlock(ptep, ptl);
3552                goto out;
3553        }
3554
3555        pte = pte_mknonnuma(pte);
3556        set_pte_at(mm, addr, ptep, pte);
3557        update_mmu_cache(vma, addr, ptep);
3558
3559        page = vm_normal_page(vma, addr, pte);
3560        if (!page) {
3561                pte_unmap_unlock(ptep, ptl);
3562                return 0;
3563        }
3564
3565        current_nid = page_to_nid(page);
3566        target_nid = numa_migrate_prep(page, vma, addr, current_nid);
3567        pte_unmap_unlock(ptep, ptl);
3568        if (target_nid == -1) {
3569                /*
3570                 * Account for the fault against the current node if it not
3571                 * being replaced regardless of where the page is located.
3572                 */
3573                current_nid = numa_node_id();
3574                put_page(page);
3575                goto out;
3576        }
3577
3578        /* Migrate to the requested node */
3579        migrated = migrate_misplaced_page(page, target_nid);
3580        if (migrated)
3581                current_nid = target_nid;
3582
3583out:
3584        if (current_nid != -1)
3585                task_numa_fault(current_nid, 1, migrated);
3586        return 0;
3587}
3588
3589/* NUMA hinting page fault entry point for regular pmds */
3590#ifdef CONFIG_NUMA_BALANCING
3591static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3592                     unsigned long addr, pmd_t *pmdp)
3593{
3594        pmd_t pmd;
3595        pte_t *pte, *orig_pte;
3596        unsigned long _addr = addr & PMD_MASK;
3597        unsigned long offset;
3598        spinlock_t *ptl;
3599        bool numa = false;
3600        int local_nid = numa_node_id();
3601
3602        spin_lock(&mm->page_table_lock);
3603        pmd = *pmdp;
3604        if (pmd_numa(pmd)) {
3605                set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd));
3606                numa = true;
3607        }
3608        spin_unlock(&mm->page_table_lock);
3609
3610        if (!numa)
3611                return 0;
3612
3613        /* we're in a page fault so some vma must be in the range */
3614        BUG_ON(!vma);
3615        BUG_ON(vma->vm_start >= _addr + PMD_SIZE);
3616        offset = max(_addr, vma->vm_start) & ~PMD_MASK;
3617        VM_BUG_ON(offset >= PMD_SIZE);
3618        orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl);
3619        pte += offset >> PAGE_SHIFT;
3620        for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
3621                pte_t pteval = *pte;
3622                struct page *page;
3623                int curr_nid = local_nid;
3624                int target_nid;
3625                bool migrated;
3626                if (!pte_present(pteval))
3627                        continue;
3628                if (!pte_numa(pteval))
3629                        continue;
3630                if (addr >= vma->vm_end) {
3631                        vma = find_vma(mm, addr);
3632                        /* there's a pte present so there must be a vma */
3633                        BUG_ON(!vma);
3634                        BUG_ON(addr < vma->vm_start);
3635                }
3636                if (pte_numa(pteval)) {
3637                        pteval = pte_mknonnuma(pteval);
3638                        set_pte_at(mm, addr, pte, pteval);
3639                }
3640                page = vm_normal_page(vma, addr, pteval);
3641                if (unlikely(!page))
3642                        continue;
3643                /* only check non-shared pages */
3644                if (unlikely(page_mapcount(page) != 1))
3645                        continue;
3646
3647                /*
3648                 * Note that the NUMA fault is later accounted to either
3649                 * the node that is currently running or where the page is
3650                 * migrated to.
3651                 */
3652                curr_nid = local_nid;
3653                target_nid = numa_migrate_prep(page, vma, addr,
3654                                               page_to_nid(page));
3655                if (target_nid == -1) {
3656                        put_page(page);
3657                        continue;
3658                }
3659
3660                /* Migrate to the requested node */
3661                pte_unmap_unlock(pte, ptl);
3662                migrated = migrate_misplaced_page(page, target_nid);
3663                if (migrated)
3664                        curr_nid = target_nid;
3665                task_numa_fault(curr_nid, 1, migrated);
3666
3667                pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
3668        }
3669        pte_unmap_unlock(orig_pte, ptl);
3670
3671        return 0;
3672}
3673#else
3674static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3675                     unsigned long addr, pmd_t *pmdp)
3676{
3677        BUG();
3678        return 0;
3679}
3680#endif /* CONFIG_NUMA_BALANCING */
3681
3682/*
3683 * These routines also need to handle stuff like marking pages dirty
3684 * and/or accessed for architectures that don't do it in hardware (most
3685 * RISC architectures).  The early dirtying is also good on the i386.
3686 *
3687 * There is also a hook called "update_mmu_cache()" that architectures
3688 * with external mmu caches can use to update those (ie the Sparc or
3689 * PowerPC hashed page tables that act as extended TLBs).
3690 *
3691 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3692 * but allow concurrent faults), and pte mapped but not yet locked.
3693 * We return with mmap_sem still held, but pte unmapped and unlocked.
3694 */
3695int handle_pte_fault(struct mm_struct *mm,
3696                     struct vm_area_struct *vma, unsigned long address,
3697                     pte_t *pte, pmd_t *pmd, unsigned int flags)
3698{
3699        pte_t entry;
3700        spinlock_t *ptl;
3701
3702        entry = *pte;
3703        if (!pte_present(entry)) {
3704                if (pte_none(entry)) {
3705                        if (vma->vm_ops) {
3706                                if (likely(vma->vm_ops->fault))
3707                                        return do_linear_fault(mm, vma, address,
3708                                                pte, pmd, flags, entry);
3709                        }
3710                        return do_anonymous_page(mm, vma, address,
3711                                                 pte, pmd, flags);
3712                }
3713                if (pte_file(entry))
3714                        return do_nonlinear_fault(mm, vma, address,
3715                                        pte, pmd, flags, entry);
3716                return do_swap_page(mm, vma, address,
3717                                        pte, pmd, flags, entry);
3718        }
3719
3720        if (pte_numa(entry))
3721                return do_numa_page(mm, vma, address, entry, pte, pmd);
3722
3723        ptl = pte_lockptr(mm, pmd);
3724        spin_lock(ptl);
3725        if (unlikely(!pte_same(*pte, entry)))
3726                goto unlock;
3727        if (flags & FAULT_FLAG_WRITE) {
3728                if (!pte_write(entry))
3729                        return do_wp_page(mm, vma, address,
3730                                        pte, pmd, ptl, entry);
3731                entry = pte_mkdirty(entry);
3732        }
3733        entry = pte_mkyoung(entry);
3734        if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3735                update_mmu_cache(vma, address, pte);
3736        } else {
3737                /*
3738                 * This is needed only for protection faults but the arch code
3739                 * is not yet telling us if this is a protection fault or not.
3740                 * This still avoids useless tlb flushes for .text page faults
3741                 * with threads.
3742                 */
3743                if (flags & FAULT_FLAG_WRITE)
3744                        flush_tlb_fix_spurious_fault(vma, address);
3745        }
3746unlock:
3747        pte_unmap_unlock(pte, ptl);
3748        return 0;
3749}
3750
3751/*
3752 * By the time we get here, we already hold the mm semaphore
3753 */
3754int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3755                unsigned long address, unsigned int flags)
3756{
3757        pgd_t *pgd;
3758        pud_t *pud;
3759        pmd_t *pmd;
3760        pte_t *pte;
3761
3762        __set_current_state(TASK_RUNNING);
3763
3764        count_vm_event(PGFAULT);
3765        mem_cgroup_count_vm_event(mm, PGFAULT);
3766
3767        /* do counter updates before entering really critical section. */
3768        check_sync_rss_stat(current);
3769
3770        if (unlikely(is_vm_hugetlb_page(vma)))
3771                return hugetlb_fault(mm, vma, address, flags);
3772
3773retry:
3774        pgd = pgd_offset(mm, address);
3775        pud = pud_alloc(mm, pgd, address);
3776        if (!pud)
3777                return VM_FAULT_OOM;
3778        pmd = pmd_alloc(mm, pud, address);
3779        if (!pmd)
3780                return VM_FAULT_OOM;
3781        if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3782                if (!vma->vm_ops)
3783                        return do_huge_pmd_anonymous_page(mm, vma, address,
3784                                                          pmd, flags);
3785        } else {
3786                pmd_t orig_pmd = *pmd;
3787                int ret;
3788
3789                barrier();
3790                if (pmd_trans_huge(orig_pmd)) {
3791                        unsigned int dirty = flags & FAULT_FLAG_WRITE;
3792
3793                        /*
3794                         * If the pmd is splitting, return and retry the
3795                         * the fault.  Alternative: wait until the split
3796                         * is done, and goto retry.
3797                         */
3798                        if (pmd_trans_splitting(orig_pmd))
3799                                return 0;
3800
3801                        if (pmd_numa(orig_pmd))
3802                                return do_huge_pmd_numa_page(mm, vma, address,
3803                                                             orig_pmd, pmd);
3804
3805                        if (dirty && !pmd_write(orig_pmd)) {
3806                                ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3807                                                          orig_pmd);
3808                                /*
3809                                 * If COW results in an oom, the huge pmd will
3810                                 * have been split, so retry the fault on the
3811                                 * pte for a smaller charge.
3812                                 */
3813                                if (unlikely(ret & VM_FAULT_OOM))
3814                                        goto retry;
3815                                return ret;
3816                        } else {
3817                                huge_pmd_set_accessed(mm, vma, address, pmd,
3818                                                      orig_pmd, dirty);
3819                        }
3820
3821                        return 0;
3822                }
3823        }
3824
3825        if (pmd_numa(*pmd))
3826                return do_pmd_numa_page(mm, vma, address, pmd);
3827
3828        /*
3829         * Use __pte_alloc instead of pte_alloc_map, because we can't
3830         * run pte_offset_map on the pmd, if an huge pmd could
3831         * materialize from under us from a different thread.
3832         */
3833        if (unlikely(pmd_none(*pmd)) &&
3834            unlikely(__pte_alloc(mm, vma, pmd, address)))
3835                return VM_FAULT_OOM;
3836        /* if an huge pmd materialized from under us just retry later */
3837        if (unlikely(pmd_trans_huge(*pmd)))
3838                return 0;
3839        /*
3840         * A regular pmd is established and it can't morph into a huge pmd
3841         * from under us anymore at this point because we hold the mmap_sem
3842         * read mode and khugepaged takes it in write mode. So now it's
3843         * safe to run pte_offset_map().
3844         */
3845        pte = pte_offset_map(pmd, address);
3846
3847        return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3848}
3849
3850#ifndef __PAGETABLE_PUD_FOLDED
3851/*
3852 * Allocate page upper directory.
3853 * We've already handled the fast-path in-line.
3854 */
3855int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3856{
3857        pud_t *new = pud_alloc_one(mm, address);
3858        if (!new)
3859                return -ENOMEM;
3860
3861        smp_wmb(); /* See comment in __pte_alloc */
3862
3863        spin_lock(&mm->page_table_lock);
3864        if (pgd_present(*pgd))          /* Another has populated it */
3865                pud_free(mm, new);
3866        else
3867                pgd_populate(mm, pgd, new);
3868        spin_unlock(&mm->page_table_lock);
3869        return 0;
3870}
3871#endif /* __PAGETABLE_PUD_FOLDED */
3872
3873#ifndef __PAGETABLE_PMD_FOLDED
3874/*
3875 * Allocate page middle directory.
3876 * We've already handled the fast-path in-line.
3877 */
3878int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3879{
3880        pmd_t *new = pmd_alloc_one(mm, address);
3881        if (!new)
3882                return -ENOMEM;
3883
3884        smp_wmb(); /* See comment in __pte_alloc */
3885
3886        spin_lock(&mm->page_table_lock);
3887#ifndef __ARCH_HAS_4LEVEL_HACK
3888        if (pud_present(*pud))          /* Another has populated it */
3889                pmd_free(mm, new);
3890        else
3891                pud_populate(mm, pud, new);
3892#else
3893        if (pgd_present(*pud))          /* Another has populated it */
3894                pmd_free(mm, new);
3895        else
3896                pgd_populate(mm, pud, new);
3897#endif /* __ARCH_HAS_4LEVEL_HACK */
3898        spin_unlock(&mm->page_table_lock);
3899        return 0;
3900}
3901#endif /* __PAGETABLE_PMD_FOLDED */
3902
3903#if !defined(__HAVE_ARCH_GATE_AREA)
3904
3905#if defined(AT_SYSINFO_EHDR)
3906static struct vm_area_struct gate_vma;
3907
3908static int __init gate_vma_init(void)
3909{
3910        gate_vma.vm_mm = NULL;
3911        gate_vma.vm_start = FIXADDR_USER_START;
3912        gate_vma.vm_end = FIXADDR_USER_END;
3913        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3914        gate_vma.vm_page_prot = __P101;
3915
3916        return 0;
3917}
3918__initcall(gate_vma_init);
3919#endif
3920
3921struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3922{
3923#ifdef AT_SYSINFO_EHDR
3924        return &gate_vma;
3925#else
3926        return NULL;
3927#endif
3928}
3929
3930int in_gate_area_no_mm(unsigned long addr)
3931{
3932#ifdef AT_SYSINFO_EHDR
3933        if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3934                return 1;
3935#endif
3936        return 0;
3937}
3938
3939#endif  /* __HAVE_ARCH_GATE_AREA */
3940
3941static int __follow_pte(struct mm_struct *mm, unsigned long address,
3942                pte_t **ptepp, spinlock_t **ptlp)
3943{
3944        pgd_t *pgd;
3945        pud_t *pud;
3946        pmd_t *pmd;
3947        pte_t *ptep;
3948
3949        pgd = pgd_offset(mm, address);
3950        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3951                goto out;
3952
3953        pud = pud_offset(pgd, address);
3954        if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3955                goto out;
3956
3957        pmd = pmd_offset(pud, address);
3958        VM_BUG_ON(pmd_trans_huge(*pmd));
3959        if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3960                goto out;
3961
3962        /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3963        if (pmd_huge(*pmd))
3964                goto out;
3965
3966        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3967        if (!ptep)
3968                goto out;
3969        if (!pte_present(*ptep))
3970                goto unlock;
3971        *ptepp = ptep;
3972        return 0;
3973unlock:
3974        pte_unmap_unlock(ptep, *ptlp);
3975out:
3976        return -EINVAL;
3977}
3978
3979static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3980                             pte_t **ptepp, spinlock_t **ptlp)
3981{
3982        int res;
3983
3984        /* (void) is needed to make gcc happy */
3985        (void) __cond_lock(*ptlp,
3986                           !(res = __follow_pte(mm, address, ptepp, ptlp)));
3987        return res;
3988}
3989
3990/**
3991 * follow_pfn - look up PFN at a user virtual address
3992 * @vma: memory mapping
3993 * @address: user virtual address
3994 * @pfn: location to store found PFN
3995 *
3996 * Only IO mappings and raw PFN mappings are allowed.
3997 *
3998 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3999 */
4000int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4001        unsigned long *pfn)
4002{
4003        int ret = -EINVAL;
4004        spinlock_t *ptl;
4005        pte_t *ptep;
4006
4007        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4008                return ret;
4009
4010        ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4011        if (ret)
4012                return ret;
4013        *pfn = pte_pfn(*ptep);
4014        pte_unmap_unlock(ptep, ptl);
4015        return 0;
4016}
4017EXPORT_SYMBOL(follow_pfn);
4018
4019#ifdef CONFIG_HAVE_IOREMAP_PROT
4020int follow_phys(struct vm_area_struct *vma,
4021                unsigned long address, unsigned int flags,
4022                unsigned long *prot, resource_size_t *phys)
4023{
4024        int ret = -EINVAL;
4025        pte_t *ptep, pte;
4026        spinlock_t *ptl;
4027
4028        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4029                goto out;
4030
4031        if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4032                goto out;
4033        pte = *ptep;
4034
4035        if ((flags & FOLL_WRITE) && !pte_write(pte))
4036                goto unlock;
4037
4038        *prot = pgprot_val(pte_pgprot(pte));
4039        *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4040
4041        ret = 0;
4042unlock:
4043        pte_unmap_unlock(ptep, ptl);
4044out:
4045        return ret;
4046}
4047
4048int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4049                        void *buf, int len, int write)
4050{
4051        resource_size_t phys_addr;
4052        unsigned long prot = 0;
4053        void __iomem *maddr;
4054        int offset = addr & (PAGE_SIZE-1);
4055
4056        if (follow_phys(vma, addr, write, &prot, &phys_addr))
4057                return -EINVAL;
4058
4059        maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
4060        if (write)
4061                memcpy_toio(maddr + offset, buf, len);
4062        else
4063                memcpy_fromio(buf, maddr + offset, len);
4064        iounmap(maddr);
4065
4066        return len;
4067}
4068#endif
4069
4070/*
4071 * Access another process' address space as given in mm.  If non-NULL, use the
4072 * given task for page fault accounting.
4073 */
4074static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4075                unsigned long addr, void *buf, int len, int write)
4076{
4077        struct vm_area_struct *vma;
4078        void *old_buf = buf;
4079
4080        down_read(&mm->mmap_sem);
4081        /* ignore errors, just check how much was successfully transferred */
4082        while (len) {
4083                int bytes, ret, offset;
4084                void *maddr;
4085                struct page *page = NULL;
4086
4087                ret = get_user_pages(tsk, mm, addr, 1,
4088                                write, 1, &page, &vma);
4089                if (ret <= 0) {
4090                        /*
4091                         * Check if this is a VM_IO | VM_PFNMAP VMA, which
4092                         * we can access using slightly different code.
4093                         */
4094#ifdef CONFIG_HAVE_IOREMAP_PROT
4095                        vma = find_vma(mm, addr);
4096                        if (!vma || vma->vm_start > addr)
4097                                break;
4098                        if (vma->vm_ops && vma->vm_ops->access)
4099                                ret = vma->vm_ops->access(vma, addr, buf,
4100                                                          len, write);
4101                        if (ret <= 0)
4102#endif
4103                                break;
4104                        bytes = ret;
4105                } else {
4106                        bytes = len;
4107                        offset = addr & (PAGE_SIZE-1);
4108                        if (bytes > PAGE_SIZE-offset)
4109                                bytes = PAGE_SIZE-offset;
4110
4111                        maddr = kmap(page);
4112                        if (write) {
4113                                copy_to_user_page(vma, page, addr,
4114                                                  maddr + offset, buf, bytes);
4115                                set_page_dirty_lock(page);
4116                        } else {
4117                                copy_from_user_page(vma, page, addr,
4118                                                    buf, maddr + offset, bytes);
4119                        }
4120                        kunmap(page);
4121                        page_cache_release(page);
4122                }
4123                len -= bytes;
4124                buf += bytes;
4125                addr += bytes;
4126        }
4127        up_read(&mm->mmap_sem);
4128
4129        return buf - old_buf;
4130}
4131
4132/**
4133 * access_remote_vm - access another process' address space
4134 * @mm:         the mm_struct of the target address space
4135 * @addr:       start address to access
4136 * @buf:        source or destination buffer
4137 * @len:        number of bytes to transfer
4138 * @write:      whether the access is a write
4139 *
4140 * The caller must hold a reference on @mm.
4141 */
4142int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4143                void *buf, int len, int write)
4144{
4145        return __access_remote_vm(NULL, mm, addr, buf, len, write);
4146}
4147
4148/*
4149 * Access another process' address space.
4150 * Source/target buffer must be kernel space,
4151 * Do not walk the page table directly, use get_user_pages
4152 */
4153int access_process_vm(struct task_struct *tsk, unsigned long addr,
4154                void *buf, int len, int write)
4155{
4156        struct mm_struct *mm;
4157        int ret;
4158
4159        mm = get_task_mm(tsk);
4160        if (!mm)
4161                return 0;
4162
4163        ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
4164        mmput(mm);
4165
4166        return ret;
4167}
4168
4169/*
4170 * Print the name of a VMA.
4171 */
4172void print_vma_addr(char *prefix, unsigned long ip)
4173{
4174        struct mm_struct *mm = current->mm;
4175        struct vm_area_struct *vma;
4176
4177        /*
4178         * Do not print if we are in atomic
4179         * contexts (in exception stacks, etc.):
4180         */
4181        if (preempt_count())
4182                return;
4183
4184        down_read(&mm->mmap_sem);
4185        vma = find_vma(mm, ip);
4186        if (vma && vma->vm_file) {
4187                struct file *f = vma->vm_file;
4188                char *buf = (char *)__get_free_page(GFP_KERNEL);
4189                if (buf) {
4190                        char *p;
4191
4192                        p = d_path(&f->f_path, buf, PAGE_SIZE);
4193                        if (IS_ERR(p))
4194                                p = "?";
4195                        printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4196                                        vma->vm_start,
4197                                        vma->vm_end - vma->vm_start);
4198                        free_page((unsigned long)buf);
4199                }
4200        }
4201        up_read(&mm->mmap_sem);
4202}
4203
4204#ifdef CONFIG_PROVE_LOCKING
4205void might_fault(void)
4206{
4207        /*
4208         * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4209         * holding the mmap_sem, this is safe because kernel memory doesn't
4210         * get paged out, therefore we'll never actually fault, and the
4211         * below annotations will generate false positives.
4212         */
4213        if (segment_eq(get_fs(), KERNEL_DS))
4214                return;
4215
4216        might_sleep();
4217        /*
4218         * it would be nicer only to annotate paths which are not under
4219         * pagefault_disable, however that requires a larger audit and
4220         * providing helpers like get_user_atomic.
4221         */
4222        if (!in_atomic() && current->mm)
4223                might_lock_read(&current->mm->mmap_sem);
4224}
4225EXPORT_SYMBOL(might_fault);
4226#endif
4227
4228#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4229static void clear_gigantic_page(struct page *page,
4230                                unsigned long addr,
4231                                unsigned int pages_per_huge_page)
4232{
4233        int i;
4234        struct page *p = page;
4235
4236        might_sleep();
4237        for (i = 0; i < pages_per_huge_page;
4238             i++, p = mem_map_next(p, page, i)) {
4239                cond_resched();
4240                clear_user_highpage(p, addr + i * PAGE_SIZE);
4241        }
4242}
4243void clear_huge_page(struct page *page,
4244                     unsigned long addr, unsigned int pages_per_huge_page)
4245{
4246        int i;
4247
4248        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4249                clear_gigantic_page(page, addr, pages_per_huge_page);
4250                return;
4251        }
4252
4253        might_sleep();
4254        for (i = 0; i < pages_per_huge_page; i++) {
4255                cond_resched();
4256                clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4257        }
4258}
4259
4260static void copy_user_gigantic_page(struct page *dst, struct page *src,
4261                                    unsigned long addr,
4262                                    struct vm_area_struct *vma,
4263                                    unsigned int pages_per_huge_page)
4264{
4265        int i;
4266        struct page *dst_base = dst;
4267        struct page *src_base = src;
4268
4269        for (i = 0; i < pages_per_huge_page; ) {
4270                cond_resched();
4271                copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4272
4273                i++;
4274                dst = mem_map_next(dst, dst_base, i);
4275                src = mem_map_next(src, src_base, i);
4276        }
4277}
4278
4279void copy_user_huge_page(struct page *dst, struct page *src,
4280                         unsigned long addr, struct vm_area_struct *vma,
4281                         unsigned int pages_per_huge_page)
4282{
4283        int i;
4284
4285        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4286                copy_user_gigantic_page(dst, src, addr, vma,
4287                                        pages_per_huge_page);
4288                return;
4289        }
4290
4291        might_sleep();
4292        for (i = 0; i < pages_per_huge_page; i++) {
4293                cond_resched();
4294                copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4295        }
4296}
4297#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4298
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