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
  85/*
  86 * A number of key systems in x86 including ioremap() rely on the assumption
  87 * that high_memory defines the upper bound on direct map memory, then end
  88 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  89 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  90 * and ZONE_HIGHMEM.
  91 */
  92void * high_memory;
  93
  94EXPORT_SYMBOL(high_memory);
  95
  96/*
  97 * Randomize the address space (stacks, mmaps, brk, etc.).
  98 *
  99 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 100 *   as ancient (libc5 based) binaries can segfault. )
 101 */
 102int randomize_va_space __read_mostly =
 103#ifdef CONFIG_COMPAT_BRK
 104                                        1;
 105#else
 106                                        2;
 107#endif
 108
 109static int __init disable_randmaps(char *s)
 110{
 111        randomize_va_space = 0;
 112        return 1;
 113}
 114__setup("norandmaps", disable_randmaps);
 115
 116unsigned long zero_pfn __read_mostly;
 117unsigned long highest_memmap_pfn __read_mostly;
 118
 119/*
 120 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 121 */
 122static int __init init_zero_pfn(void)
 123{
 124        zero_pfn = page_to_pfn(ZERO_PAGE(0));
 125        return 0;
 126}
 127core_initcall(init_zero_pfn);
 128
 129
 130#if defined(SPLIT_RSS_COUNTING)
 131
 132void sync_mm_rss(struct mm_struct *mm)
 133{
 134        int i;
 135
 136        for (i = 0; i < NR_MM_COUNTERS; i++) {
 137                if (current->rss_stat.count[i]) {
 138                        add_mm_counter(mm, i, current->rss_stat.count[i]);
 139                        current->rss_stat.count[i] = 0;
 140                }
 141        }
 142        current->rss_stat.events = 0;
 143}
 144
 145static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
 146{
 147        struct task_struct *task = current;
 148
 149        if (likely(task->mm == mm))
 150                task->rss_stat.count[member] += val;
 151        else
 152                add_mm_counter(mm, member, val);
 153}
 154#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
 155#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
 156
 157/* sync counter once per 64 page faults */
 158#define TASK_RSS_EVENTS_THRESH  (64)
 159static void check_sync_rss_stat(struct task_struct *task)
 160{
 161        if (unlikely(task != current))
 162                return;
 163        if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
 164                sync_mm_rss(task->mm);
 165}
 166#else /* SPLIT_RSS_COUNTING */
 167
 168#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
 169#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
 170
 171static void check_sync_rss_stat(struct task_struct *task)
 172{
 173}
 174
 175#endif /* SPLIT_RSS_COUNTING */
 176
 177#ifdef HAVE_GENERIC_MMU_GATHER
 178
 179static int tlb_next_batch(struct mmu_gather *tlb)
 180{
 181        struct mmu_gather_batch *batch;
 182
 183        batch = tlb->active;
 184        if (batch->next) {
 185                tlb->active = batch->next;
 186                return 1;
 187        }
 188
 189        if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
 190                return 0;
 191
 192        batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 193        if (!batch)
 194                return 0;
 195
 196        tlb->batch_count++;
 197        batch->next = NULL;
 198        batch->nr   = 0;
 199        batch->max  = MAX_GATHER_BATCH;
 200
 201        tlb->active->next = batch;
 202        tlb->active = batch;
 203
 204        return 1;
 205}
 206
 207/* tlb_gather_mmu
 208 *      Called to initialize an (on-stack) mmu_gather structure for page-table
 209 *      tear-down from @mm. The @fullmm argument is used when @mm is without
 210 *      users and we're going to destroy the full address space (exit/execve).
 211 */
 212void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
 213{
 214        tlb->mm = mm;
 215
 216        /* Is it from 0 to ~0? */
 217        tlb->fullmm     = !(start | (end+1));
 218        tlb->need_flush_all = 0;
 219        tlb->start      = start;
 220        tlb->end        = end;
 221        tlb->need_flush = 0;
 222        tlb->local.next = NULL;
 223        tlb->local.nr   = 0;
 224        tlb->local.max  = ARRAY_SIZE(tlb->__pages);
 225        tlb->active     = &tlb->local;
 226        tlb->batch_count = 0;
 227
 228#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 229        tlb->batch = NULL;
 230#endif
 231}
 232
 233void tlb_flush_mmu(struct mmu_gather *tlb)
 234{
 235        struct mmu_gather_batch *batch;
 236
 237        if (!tlb->need_flush)
 238                return;
 239        tlb->need_flush = 0;
 240        tlb_flush(tlb);
 241#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 242        tlb_table_flush(tlb);
 243#endif
 244
 245        for (batch = &tlb->local; batch; batch = batch->next) {
 246                free_pages_and_swap_cache(batch->pages, batch->nr);
 247                batch->nr = 0;
 248        }
 249        tlb->active = &tlb->local;
 250}
 251
 252/* tlb_finish_mmu
 253 *      Called at the end of the shootdown operation to free up any resources
 254 *      that were required.
 255 */
 256void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 257{
 258        struct mmu_gather_batch *batch, *next;
 259
 260        tlb_flush_mmu(tlb);
 261
 262        /* keep the page table cache within bounds */
 263        check_pgt_cache();
 264
 265        for (batch = tlb->local.next; batch; batch = next) {
 266                next = batch->next;
 267                free_pages((unsigned long)batch, 0);
 268        }
 269        tlb->local.next = NULL;
 270}
 271
 272/* __tlb_remove_page
 273 *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 274 *      handling the additional races in SMP caused by other CPUs caching valid
 275 *      mappings in their TLBs. Returns the number of free page slots left.
 276 *      When out of page slots we must call tlb_flush_mmu().
 277 */
 278int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 279{
 280        struct mmu_gather_batch *batch;
 281
 282        VM_BUG_ON(!tlb->need_flush);
 283
 284        batch = tlb->active;
 285        batch->pages[batch->nr++] = page;
 286        if (batch->nr == batch->max) {
 287                if (!tlb_next_batch(tlb))
 288                        return 0;
 289                batch = tlb->active;
 290        }
 291        VM_BUG_ON(batch->nr > batch->max);
 292
 293        return batch->max - batch->nr;
 294}
 295
 296#endif /* HAVE_GENERIC_MMU_GATHER */
 297
 298#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 299
 300/*
 301 * See the comment near struct mmu_table_batch.
 302 */
 303
 304static void tlb_remove_table_smp_sync(void *arg)
 305{
 306        /* Simply deliver the interrupt */
 307}
 308
 309static void tlb_remove_table_one(void *table)
 310{
 311        /*
 312         * This isn't an RCU grace period and hence the page-tables cannot be
 313         * assumed to be actually RCU-freed.
 314         *
 315         * It is however sufficient for software page-table walkers that rely on
 316         * IRQ disabling. See the comment near struct mmu_table_batch.
 317         */
 318        smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
 319        __tlb_remove_table(table);
 320}
 321
 322static void tlb_remove_table_rcu(struct rcu_head *head)
 323{
 324        struct mmu_table_batch *batch;
 325        int i;
 326
 327        batch = container_of(head, struct mmu_table_batch, rcu);
 328
 329        for (i = 0; i < batch->nr; i++)
 330                __tlb_remove_table(batch->tables[i]);
 331
 332        free_page((unsigned long)batch);
 333}
 334
 335void tlb_table_flush(struct mmu_gather *tlb)
 336{
 337        struct mmu_table_batch **batch = &tlb->batch;
 338
 339        if (*batch) {
 340                call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
 341                *batch = NULL;
 342        }
 343}
 344
 345void tlb_remove_table(struct mmu_gather *tlb, void *table)
 346{
 347        struct mmu_table_batch **batch = &tlb->batch;
 348
 349        tlb->need_flush = 1;
 350
 351        /*
 352         * When there's less then two users of this mm there cannot be a
 353         * concurrent page-table walk.
 354         */
 355        if (atomic_read(&tlb->mm->mm_users) < 2) {
 356                __tlb_remove_table(table);
 357                return;
 358        }
 359
 360        if (*batch == NULL) {
 361                *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
 362                if (*batch == NULL) {
 363                        tlb_remove_table_one(table);
 364                        return;
 365                }
 366                (*batch)->nr = 0;
 367        }
 368        (*batch)->tables[(*batch)->nr++] = table;
 369        if ((*batch)->nr == MAX_TABLE_BATCH)
 370                tlb_table_flush(tlb);
 371}
 372
 373#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
 374
 375/*
 376 * Note: this doesn't free the actual pages themselves. That
 377 * has been handled earlier when unmapping all the memory regions.
 378 */
 379static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 380                           unsigned long addr)
 381{
 382        pgtable_t token = pmd_pgtable(*pmd);
 383        pmd_clear(pmd);
 384        pte_free_tlb(tlb, token, addr);
 385        tlb->mm->nr_ptes--;
 386}
 387
 388static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 389                                unsigned long addr, unsigned long end,
 390                                unsigned long floor, unsigned long ceiling)
 391{
 392        pmd_t *pmd;
 393        unsigned long next;
 394        unsigned long start;
 395
 396        start = addr;
 397        pmd = pmd_offset(pud, addr);
 398        do {
 399                next = pmd_addr_end(addr, end);
 400                if (pmd_none_or_clear_bad(pmd))
 401                        continue;
 402                free_pte_range(tlb, pmd, addr);
 403        } while (pmd++, addr = next, addr != end);
 404
 405        start &= PUD_MASK;
 406        if (start < floor)
 407                return;
 408        if (ceiling) {
 409                ceiling &= PUD_MASK;
 410                if (!ceiling)
 411                        return;
 412        }
 413        if (end - 1 > ceiling - 1)
 414                return;
 415
 416        pmd = pmd_offset(pud, start);
 417        pud_clear(pud);
 418        pmd_free_tlb(tlb, pmd, start);
 419}
 420
 421static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 422                                unsigned long addr, unsigned long end,
 423                                unsigned long floor, unsigned long ceiling)
 424{
 425        pud_t *pud;
 426        unsigned long next;
 427        unsigned long start;
 428
 429        start = addr;
 430        pud = pud_offset(pgd, addr);
 431        do {
 432                next = pud_addr_end(addr, end);
 433                if (pud_none_or_clear_bad(pud))
 434                        continue;
 435                free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 436        } while (pud++, addr = next, addr != end);
 437
 438        start &= PGDIR_MASK;
 439        if (start < floor)
 440                return;
 441        if (ceiling) {
 442                ceiling &= PGDIR_MASK;
 443                if (!ceiling)
 444                        return;
 445        }
 446        if (end - 1 > ceiling - 1)
 447                return;
 448
 449        pud = pud_offset(pgd, start);
 450        pgd_clear(pgd);
 451        pud_free_tlb(tlb, pud, start);
 452}
 453
 454/*
 455 * This function frees user-level page tables of a process.
 456 *
 457 * Must be called with pagetable lock held.
 458 */
 459void free_pgd_range(struct mmu_gather *tlb,
 460                        unsigned long addr, unsigned long end,
 461                        unsigned long floor, unsigned long ceiling)
 462{
 463        pgd_t *pgd;
 464        unsigned long next;
 465
 466        /*
 467         * The next few lines have given us lots of grief...
 468         *
 469         * Why are we testing PMD* at this top level?  Because often
 470         * there will be no work to do at all, and we'd prefer not to
 471         * go all the way down to the bottom just to discover that.
 472         *
 473         * Why all these "- 1"s?  Because 0 represents both the bottom
 474         * of the address space and the top of it (using -1 for the
 475         * top wouldn't help much: the masks would do the wrong thing).
 476         * The rule is that addr 0 and floor 0 refer to the bottom of
 477         * the address space, but end 0 and ceiling 0 refer to the top
 478         * Comparisons need to use "end - 1" and "ceiling - 1" (though
 479         * that end 0 case should be mythical).
 480         *
 481         * Wherever addr is brought up or ceiling brought down, we must
 482         * be careful to reject "the opposite 0" before it confuses the
 483         * subsequent tests.  But what about where end is brought down
 484         * by PMD_SIZE below? no, end can't go down to 0 there.
 485         *
 486         * Whereas we round start (addr) and ceiling down, by different
 487         * masks at different levels, in order to test whether a table
 488         * now has no other vmas using it, so can be freed, we don't
 489         * bother to round floor or end up - the tests don't need that.
 490         */
 491
 492        addr &= PMD_MASK;
 493        if (addr < floor) {
 494                addr += PMD_SIZE;
 495                if (!addr)
 496                        return;
 497        }
 498        if (ceiling) {
 499                ceiling &= PMD_MASK;
 500                if (!ceiling)
 501                        return;
 502        }
 503        if (end - 1 > ceiling - 1)
 504                end -= PMD_SIZE;
 505        if (addr > end - 1)
 506                return;
 507
 508        pgd = pgd_offset(tlb->mm, addr);
 509        do {
 510                next = pgd_addr_end(addr, end);
 511                if (pgd_none_or_clear_bad(pgd))
 512                        continue;
 513                free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 514        } while (pgd++, addr = next, addr != end);
 515}
 516
 517void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 518                unsigned long floor, unsigned long ceiling)
 519{
 520        while (vma) {
 521                struct vm_area_struct *next = vma->vm_next;
 522                unsigned long addr = vma->vm_start;
 523
 524                /*
 525                 * Hide vma from rmap and truncate_pagecache before freeing
 526                 * pgtables
 527                 */
 528                unlink_anon_vmas(vma);
 529                unlink_file_vma(vma);
 530
 531                if (is_vm_hugetlb_page(vma)) {
 532                        hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 533                                floor, next? next->vm_start: ceiling);
 534                } else {
 535                        /*
 536                         * Optimization: gather nearby vmas into one call down
 537                         */
 538                        while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 539                               && !is_vm_hugetlb_page(next)) {
 540                                vma = next;
 541                                next = vma->vm_next;
 542                                unlink_anon_vmas(vma);
 543                                unlink_file_vma(vma);
 544                        }
 545                        free_pgd_range(tlb, addr, vma->vm_end,
 546                                floor, next? next->vm_start: ceiling);
 547                }
 548                vma = next;
 549        }
 550}
 551
 552int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 553                pmd_t *pmd, unsigned long address)
 554{
 555        pgtable_t new = pte_alloc_one(mm, address);
 556        int wait_split_huge_page;
 557        if (!new)
 558                return -ENOMEM;
 559
 560        /*
 561         * Ensure all pte setup (eg. pte page lock and page clearing) are
 562         * visible before the pte is made visible to other CPUs by being
 563         * put into page tables.
 564         *
 565         * The other side of the story is the pointer chasing in the page
 566         * table walking code (when walking the page table without locking;
 567         * ie. most of the time). Fortunately, these data accesses consist
 568         * of a chain of data-dependent loads, meaning most CPUs (alpha
 569         * being the notable exception) will already guarantee loads are
 570         * seen in-order. See the alpha page table accessors for the
 571         * smp_read_barrier_depends() barriers in page table walking code.
 572         */
 573        smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 574
 575        spin_lock(&mm->page_table_lock);
 576        wait_split_huge_page = 0;
 577        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 578                mm->nr_ptes++;
 579                pmd_populate(mm, pmd, new);
 580                new = NULL;
 581        } else if (unlikely(pmd_trans_splitting(*pmd)))
 582                wait_split_huge_page = 1;
 583        spin_unlock(&mm->page_table_lock);
 584        if (new)
 585                pte_free(mm, new);
 586        if (wait_split_huge_page)
 587                wait_split_huge_page(vma->anon_vma, pmd);
 588        return 0;
 589}
 590
 591int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 592{
 593        pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 594        if (!new)
 595                return -ENOMEM;
 596
 597        smp_wmb(); /* See comment in __pte_alloc */
 598
 599        spin_lock(&init_mm.page_table_lock);
 600        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 601                pmd_populate_kernel(&init_mm, pmd, new);
 602                new = NULL;
 603        } else
 604                VM_BUG_ON(pmd_trans_splitting(*pmd));
 605        spin_unlock(&init_mm.page_table_lock);
 606        if (new)
 607                pte_free_kernel(&init_mm, new);
 608        return 0;
 609}
 610
 611static inline void init_rss_vec(int *rss)
 612{
 613        memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
 614}
 615
 616static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
 617{
 618        int i;
 619
 620        if (current->mm == mm)
 621                sync_mm_rss(mm);
 622        for (i = 0; i < NR_MM_COUNTERS; i++)
 623                if (rss[i])
 624                        add_mm_counter(mm, i, rss[i]);
 625}
 626
 627/*
 628 * This function is called to print an error when a bad pte
 629 * is found. For example, we might have a PFN-mapped pte in
 630 * a region that doesn't allow it.
 631 *
 632 * The calling function must still handle the error.
 633 */
 634static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 635                          pte_t pte, struct page *page)
 636{
 637        pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
 638        pud_t *pud = pud_offset(pgd, addr);
 639        pmd_t *pmd = pmd_offset(pud, addr);
 640        struct address_space *mapping;
 641        pgoff_t index;
 642        static unsigned long resume;
 643        static unsigned long nr_shown;
 644        static unsigned long nr_unshown;
 645
 646        /*
 647         * Allow a burst of 60 reports, then keep quiet for that minute;
 648         * or allow a steady drip of one report per second.
 649         */
 650        if (nr_shown == 60) {
 651                if (time_before(jiffies, resume)) {
 652                        nr_unshown++;
 653                        return;
 654                }
 655                if (nr_unshown) {
 656                        printk(KERN_ALERT
 657                                "BUG: Bad page map: %lu messages suppressed\n",
 658                                nr_unshown);
 659                        nr_unshown = 0;
 660                }
 661                nr_shown = 0;
 662        }
 663        if (nr_shown++ == 0)
 664                resume = jiffies + 60 * HZ;
 665
 666        mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 667        index = linear_page_index(vma, addr);
 668
 669        printk(KERN_ALERT
 670                "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
 671                current->comm,
 672                (long long)pte_val(pte), (long long)pmd_val(*pmd));
 673        if (page)
 674                dump_page(page);
 675        printk(KERN_ALERT
 676                "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
 677                (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
 678        /*
 679         * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 680         */
 681        if (vma->vm_ops)
 682                printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
 683                       vma->vm_ops->fault);
 684        if (vma->vm_file && vma->vm_file->f_op)
 685                printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
 686                       vma->vm_file->f_op->mmap);
 687        dump_stack();
 688        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 689}
 690
 691static inline bool is_cow_mapping(vm_flags_t flags)
 692{
 693        return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 694}
 695
 696/*
 697 * vm_normal_page -- This function gets the "struct page" associated with a pte.
 698 *
 699 * "Special" mappings do not wish to be associated with a "struct page" (either
 700 * it doesn't exist, or it exists but they don't want to touch it). In this
 701 * case, NULL is returned here. "Normal" mappings do have a struct page.
 702 *
 703 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 704 * pte bit, in which case this function is trivial. Secondly, an architecture
 705 * may not have a spare pte bit, which requires a more complicated scheme,
 706 * described below.
 707 *
 708 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 709 * special mapping (even if there are underlying and valid "struct pages").
 710 * COWed pages of a VM_PFNMAP are always normal.
 711 *
 712 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 713 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
 714 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 715 * mapping will always honor the rule
 716 *
 717 *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 718 *
 719 * And for normal mappings this is false.
 720 *
 721 * This restricts such mappings to be a linear translation from virtual address
 722 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 723 * as the vma is not a COW mapping; in that case, we know that all ptes are
 724 * special (because none can have been COWed).
 725 *
 726 *
 727 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
 728 *
 729 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 730 * page" backing, however the difference is that _all_ pages with a struct
 731 * page (that is, those where pfn_valid is true) are refcounted and considered
 732 * normal pages by the VM. The disadvantage is that pages are refcounted
 733 * (which can be slower and simply not an option for some PFNMAP users). The
 734 * advantage is that we don't have to follow the strict linearity rule of
 735 * PFNMAP mappings in order to support COWable mappings.
 736 *
 737 */
 738#ifdef __HAVE_ARCH_PTE_SPECIAL
 739# define HAVE_PTE_SPECIAL 1
 740#else
 741# define HAVE_PTE_SPECIAL 0
 742#endif
 743struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 744                                pte_t pte)
 745{
 746        unsigned long pfn = pte_pfn(pte);
 747
 748        if (HAVE_PTE_SPECIAL) {
 749                if (likely(!pte_special(pte)))
 750                        goto check_pfn;
 751                if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
 752                        return NULL;
 753                if (!is_zero_pfn(pfn))
 754                        print_bad_pte(vma, addr, pte, NULL);
 755                return NULL;
 756        }
 757
 758        /* !HAVE_PTE_SPECIAL case follows: */
 759
 760        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 761                if (vma->vm_flags & VM_MIXEDMAP) {
 762                        if (!pfn_valid(pfn))
 763                                return NULL;
 764                        goto out;
 765                } else {
 766                        unsigned long off;
 767                        off = (addr - vma->vm_start) >> PAGE_SHIFT;
 768                        if (pfn == vma->vm_pgoff + off)
 769                                return NULL;
 770                        if (!is_cow_mapping(vma->vm_flags))
 771                                return NULL;
 772                }
 773        }
 774
 775        if (is_zero_pfn(pfn))
 776                return NULL;
 777check_pfn:
 778        if (unlikely(pfn > highest_memmap_pfn)) {
 779                print_bad_pte(vma, addr, pte, NULL);
 780                return NULL;
 781        }
 782
 783        /*
 784         * NOTE! We still have PageReserved() pages in the page tables.
 785         * eg. VDSO mappings can cause them to exist.
 786         */
 787out:
 788        return pfn_to_page(pfn);
 789}
 790
 791/*
 792 * copy one vm_area from one task to the other. Assumes the page tables
 793 * already present in the new task to be cleared in the whole range
 794 * covered by this vma.
 795 */
 796
 797static inline unsigned long
 798copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 799                pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 800                unsigned long addr, int *rss)
 801{
 802        unsigned long vm_flags = vma->vm_flags;
 803        pte_t pte = *src_pte;
 804        struct page *page;
 805
 806        /* pte contains position in swap or file, so copy. */
 807        if (unlikely(!pte_present(pte))) {
 808                if (!pte_file(pte)) {
 809                        swp_entry_t entry = pte_to_swp_entry(pte);
 810
 811                        if (swap_duplicate(entry) < 0)
 812                                return entry.val;
 813
 814                        /* make sure dst_mm is on swapoff's mmlist. */
 815                        if (unlikely(list_empty(&dst_mm->mmlist))) {
 816                                spin_lock(&mmlist_lock);
 817                                if (list_empty(&dst_mm->mmlist))
 818                                        list_add(&dst_mm->mmlist,
 819                                                 &src_mm->mmlist);
 820                                spin_unlock(&mmlist_lock);
 821                        }
 822                        if (likely(!non_swap_entry(entry)))
 823                                rss[MM_SWAPENTS]++;
 824                        else if (is_migration_entry(entry)) {
 825                                page = migration_entry_to_page(entry);
 826
 827                                if (PageAnon(page))
 828                                        rss[MM_ANONPAGES]++;
 829                                else
 830                                        rss[MM_FILEPAGES]++;
 831
 832                                if (is_write_migration_entry(entry) &&
 833                                    is_cow_mapping(vm_flags)) {
 834                                        /*
 835                                         * COW mappings require pages in both
 836                                         * parent and child to be set to read.
 837                                         */
 838                                        make_migration_entry_read(&entry);
 839                                        pte = swp_entry_to_pte(entry);
 840                                        if (pte_swp_soft_dirty(*src_pte))
 841                                                pte = pte_swp_mksoft_dirty(pte);
 842                                        set_pte_at(src_mm, addr, src_pte, pte);
 843                                }
 844                        }
 845                }
 846                goto out_set_pte;
 847        }
 848
 849        /*
 850         * If it's a COW mapping, write protect it both
 851         * in the parent and the child
 852         */
 853        if (is_cow_mapping(vm_flags)) {
 854                ptep_set_wrprotect(src_mm, addr, src_pte);
 855                pte = pte_wrprotect(pte);
 856        }
 857
 858        /*
 859         * If it's a shared mapping, mark it clean in
 860         * the child
 861         */
 862        if (vm_flags & VM_SHARED)
 863                pte = pte_mkclean(pte);
 864        pte = pte_mkold(pte);
 865
 866        page = vm_normal_page(vma, addr, pte);
 867        if (page) {
 868                get_page(page);
 869                page_dup_rmap(page);
 870                if (PageAnon(page))
 871                        rss[MM_ANONPAGES]++;
 872                else
 873                        rss[MM_FILEPAGES]++;
 874        }
 875
 876out_set_pte:
 877        set_pte_at(dst_mm, addr, dst_pte, pte);
 878        return 0;
 879}
 880
 881int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 882                   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 883                   unsigned long addr, unsigned long end)
 884{
 885        pte_t *orig_src_pte, *orig_dst_pte;
 886        pte_t *src_pte, *dst_pte;
 887        spinlock_t *src_ptl, *dst_ptl;
 888        int progress = 0;
 889        int rss[NR_MM_COUNTERS];
 890        swp_entry_t entry = (swp_entry_t){0};
 891
 892again:
 893        init_rss_vec(rss);
 894
 895        dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 896        if (!dst_pte)
 897                return -ENOMEM;
 898        src_pte = pte_offset_map(src_pmd, addr);
 899        src_ptl = pte_lockptr(src_mm, src_pmd);
 900        spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 901        orig_src_pte = src_pte;
 902        orig_dst_pte = dst_pte;
 903        arch_enter_lazy_mmu_mode();
 904
 905        do {
 906                /*
 907                 * We are holding two locks at this point - either of them
 908                 * could generate latencies in another task on another CPU.
 909                 */
 910                if (progress >= 32) {
 911                        progress = 0;
 912                        if (need_resched() ||
 913                            spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
 914                                break;
 915                }
 916                if (pte_none(*src_pte)) {
 917                        progress++;
 918                        continue;
 919                }
 920                entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
 921                                                        vma, addr, rss);
 922                if (entry.val)
 923                        break;
 924                progress += 8;
 925        } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 926
 927        arch_leave_lazy_mmu_mode();
 928        spin_unlock(src_ptl);
 929        pte_unmap(orig_src_pte);
 930        add_mm_rss_vec(dst_mm, rss);
 931        pte_unmap_unlock(orig_dst_pte, dst_ptl);
 932        cond_resched();
 933
 934        if (entry.val) {
 935                if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
 936                        return -ENOMEM;
 937                progress = 0;
 938        }
 939        if (addr != end)
 940                goto again;
 941        return 0;
 942}
 943
 944static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 945                pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 946                unsigned long addr, unsigned long end)
 947{
 948        pmd_t *src_pmd, *dst_pmd;
 949        unsigned long next;
 950
 951        dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 952        if (!dst_pmd)
 953                return -ENOMEM;
 954        src_pmd = pmd_offset(src_pud, addr);
 955        do {
 956                next = pmd_addr_end(addr, end);
 957                if (pmd_trans_huge(*src_pmd)) {
 958                        int err;
 959                        VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
 960                        err = copy_huge_pmd(dst_mm, src_mm,
 961                                            dst_pmd, src_pmd, addr, vma);
 962                        if (err == -ENOMEM)
 963                                return -ENOMEM;
 964                        if (!err)
 965                                continue;
 966                        /* fall through */
 967                }
 968                if (pmd_none_or_clear_bad(src_pmd))
 969                        continue;
 970                if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
 971                                                vma, addr, next))
 972                        return -ENOMEM;
 973        } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 974        return 0;
 975}
 976
 977static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 978                pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
 979                unsigned long addr, unsigned long end)
 980{
 981        pud_t *src_pud, *dst_pud;
 982        unsigned long next;
 983
 984        dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
 985        if (!dst_pud)
 986                return -ENOMEM;
 987        src_pud = pud_offset(src_pgd, addr);
 988        do {
 989                next = pud_addr_end(addr, end);
 990                if (pud_none_or_clear_bad(src_pud))
 991                        continue;
 992                if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
 993                                                vma, addr, next))
 994                        return -ENOMEM;
 995        } while (dst_pud++, src_pud++, addr = next, addr != end);
 996        return 0;
 997}
 998
 999int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1000                struct vm_area_struct *vma)
1001{
1002        pgd_t *src_pgd, *dst_pgd;
1003        unsigned long next;
1004        unsigned long addr = vma->vm_start;
1005        unsigned long end = vma->vm_end;
1006        unsigned long mmun_start;       /* For mmu_notifiers */
1007        unsigned long mmun_end;         /* For mmu_notifiers */
1008        bool is_cow;
1009        int ret;
1010
1011        /*
1012         * Don't copy ptes where a page fault will fill them correctly.
1013         * Fork becomes much lighter when there are big shared or private
1014         * readonly mappings. The tradeoff is that copy_page_range is more
1015         * efficient than faulting.
1016         */
1017        if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
1018                               VM_PFNMAP | VM_MIXEDMAP))) {
1019                if (!vma->anon_vma)
1020                        return 0;
1021        }
1022
1023        if (is_vm_hugetlb_page(vma))
1024                return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1025
1026        if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1027                /*
1028                 * We do not free on error cases below as remove_vma
1029                 * gets called on error from higher level routine
1030                 */
1031                ret = track_pfn_copy(vma);
1032                if (ret)
1033                        return ret;
1034        }
1035
1036        /*
1037         * We need to invalidate the secondary MMU mappings only when
1038         * there could be a permission downgrade on the ptes of the
1039         * parent mm. And a permission downgrade will only happen if
1040         * is_cow_mapping() returns true.
1041         */
1042        is_cow = is_cow_mapping(vma->vm_flags);
1043        mmun_start = addr;
1044        mmun_end   = end;
1045        if (is_cow)
1046                mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1047                                                    mmun_end);
1048
1049        ret = 0;
1050        dst_pgd = pgd_offset(dst_mm, addr);
1051        src_pgd = pgd_offset(src_mm, addr);
1052        do {
1053                next = pgd_addr_end(addr, end);
1054                if (pgd_none_or_clear_bad(src_pgd))
1055                        continue;
1056                if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1057                                            vma, addr, next))) {
1058                        ret = -ENOMEM;
1059                        break;
1060                }
1061        } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1062
1063        if (is_cow)
1064                mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1065        return ret;
1066}
1067
1068static unsigned long zap_pte_range(struct mmu_gather *tlb,
1069                                struct vm_area_struct *vma, pmd_t *pmd,
1070                                unsigned long addr, unsigned long end,
1071                                struct zap_details *details)
1072{
1073        struct mm_struct *mm = tlb->mm;
1074        int force_flush = 0;
1075        int rss[NR_MM_COUNTERS];
1076        spinlock_t *ptl;
1077        pte_t *start_pte;
1078        pte_t *pte;
1079
1080again:
1081        init_rss_vec(rss);
1082        start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1083        pte = start_pte;
1084        arch_enter_lazy_mmu_mode();
1085        do {
1086                pte_t ptent = *pte;
1087                if (pte_none(ptent)) {
1088                        continue;
1089                }
1090
1091                if (pte_present(ptent)) {
1092                        struct page *page;
1093
1094                        page = vm_normal_page(vma, addr, ptent);
1095                        if (unlikely(details) && page) {
1096                                /*
1097                                 * unmap_shared_mapping_pages() wants to
1098                                 * invalidate cache without truncating:
1099                                 * unmap shared but keep private pages.
1100                                 */
1101                                if (details->check_mapping &&
1102                                    details->check_mapping != page->mapping)
1103                                        continue;
1104                                /*
1105                                 * Each page->index must be checked when
1106                                 * invalidating or truncating nonlinear.
1107                                 */
1108                                if (details->nonlinear_vma &&
1109                                    (page->index < details->first_index ||
1110                                     page->index > details->last_index))
1111                                        continue;
1112                        }
1113                        ptent = ptep_get_and_clear_full(mm, addr, pte,
1114                                                        tlb->fullmm);
1115                        tlb_remove_tlb_entry(tlb, pte, addr);
1116                        if (unlikely(!page))
1117                                continue;
1118                        if (unlikely(details) && details->nonlinear_vma
1119                            && linear_page_index(details->nonlinear_vma,
1120                                                addr) != page->index) {
1121                                pte_t ptfile = pgoff_to_pte(page->index);
1122                                if (pte_soft_dirty(ptent))
1123                                        pte_file_mksoft_dirty(ptfile);
1124                                set_pte_at(mm, addr, pte, ptfile);
1125                        }
1126                        if (PageAnon(page))
1127                                rss[MM_ANONPAGES]--;
1128                        else {
1129                                if (pte_dirty(ptent))
1130                                        set_page_dirty(page);
1131                                if (pte_young(ptent) &&
1132                                    likely(!(vma->vm_flags & VM_SEQ_READ)))
1133                                        mark_page_accessed(page);
1134                                rss[MM_FILEPAGES]--;
1135                        }
1136                        page_remove_rmap(page);
1137                        if (unlikely(page_mapcount(page) < 0))
1138                                print_bad_pte(vma, addr, ptent, page);
1139                        force_flush = !__tlb_remove_page(tlb, page);
1140                        if (force_flush)
1141                                break;
1142                        continue;
1143                }
1144                /*
1145                 * If details->check_mapping, we leave swap entries;
1146                 * if details->nonlinear_vma, we leave file entries.
1147                 */
1148                if (unlikely(details))
1149                        continue;
1150                if (pte_file(ptent)) {
1151                        if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1152                                print_bad_pte(vma, addr, ptent, NULL);
1153                } else {
1154                        swp_entry_t entry = pte_to_swp_entry(ptent);
1155
1156                        if (!non_swap_entry(entry))
1157                                rss[MM_SWAPENTS]--;
1158                        else if (is_migration_entry(entry)) {
1159                                struct page *page;
1160
1161                                page = migration_entry_to_page(entry);
1162
1163                                if (PageAnon(page))
1164                                        rss[MM_ANONPAGES]--;
1165                                else
1166                                        rss[MM_FILEPAGES]--;
1167                        }
1168                        if (unlikely(!free_swap_and_cache(entry)))
1169                                print_bad_pte(vma, addr, ptent, NULL);
1170                }
1171                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1172        } while (pte++, addr += PAGE_SIZE, addr != end);
1173
1174        add_mm_rss_vec(mm, rss);
1175        arch_leave_lazy_mmu_mode();
1176        pte_unmap_unlock(start_pte, ptl);
1177
1178        /*
1179         * mmu_gather ran out of room to batch pages, we break out of
1180         * the PTE lock to avoid doing the potential expensive TLB invalidate
1181         * and page-free while holding it.
1182         */
1183        if (force_flush) {
1184                unsigned long old_end;
1185
1186                force_flush = 0;
1187
1188                /*
1189                 * Flush the TLB just for the previous segment,
1190                 * then update the range to be the remaining
1191                 * TLB range.
1192                 */
1193                old_end = tlb->end;
1194                tlb->end = addr;
1195
1196                tlb_flush_mmu(tlb);
1197
1198                tlb->start = addr;
1199                tlb->end = old_end;
1200
1201                if (addr != end)
1202                        goto again;
1203        }
1204
1205        return addr;
1206}
1207
1208static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1209                                struct vm_area_struct *vma, pud_t *pud,
1210                                unsigned long addr, unsigned long end,
1211                                struct zap_details *details)
1212{
1213        pmd_t *pmd;
1214        unsigned long next;
1215
1216        pmd = pmd_offset(pud, addr);
1217        do {
1218                next = pmd_addr_end(addr, end);
1219                if (pmd_trans_huge(*pmd)) {
1220                        if (next - addr != HPAGE_PMD_SIZE) {
1221#ifdef CONFIG_DEBUG_VM
1222                                if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1223                                        pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1224                                                __func__, addr, end,
1225                                                vma->vm_start,
1226                                                vma->vm_end);
1227                                        BUG();
1228                                }
1229#endif
1230                                split_huge_page_pmd(vma, addr, pmd);
1231                        } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1232                                goto next;
1233                        /* fall through */
1234                }
1235                /*
1236                 * Here there can be other concurrent MADV_DONTNEED or
1237                 * trans huge page faults running, and if the pmd is
1238                 * none or trans huge it can change under us. This is
1239                 * because MADV_DONTNEED holds the mmap_sem in read
1240                 * mode.
1241                 */
1242                if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1243                        goto next;
1244                next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1245next:
1246                cond_resched();
1247        } while (pmd++, addr = next, addr != end);
1248
1249        return addr;
1250}
1251
1252static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1253                                struct vm_area_struct *vma, pgd_t *pgd,
1254                                unsigned long addr, unsigned long end,
1255                                struct zap_details *details)
1256{
1257        pud_t *pud;
1258        unsigned long next;
1259
1260        pud = pud_offset(pgd, addr);
1261        do {
1262                next = pud_addr_end(addr, end);
1263                if (pud_none_or_clear_bad(pud))
1264                        continue;
1265                next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1266        } while (pud++, addr = next, addr != end);
1267
1268        return addr;
1269}
1270
1271static void unmap_page_range(struct mmu_gather *tlb,
1272                             struct vm_area_struct *vma,
1273                             unsigned long addr, unsigned long end,
1274                             struct zap_details *details)
1275{
1276        pgd_t *pgd;
1277        unsigned long next;
1278
1279        if (details && !details->check_mapping && !details->nonlinear_vma)
1280                details = NULL;
1281
1282        BUG_ON(addr >= end);
1283        mem_cgroup_uncharge_start();
1284        tlb_start_vma(tlb, vma);
1285        pgd = pgd_offset(vma->vm_mm, addr);
1286        do {
1287                next = pgd_addr_end(addr, end);
1288                if (pgd_none_or_clear_bad(pgd))
1289                        continue;
1290                next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1291        } while (pgd++, addr = next, addr != end);
1292        tlb_end_vma(tlb, vma);
1293        mem_cgroup_uncharge_end();
1294}
1295
1296
1297static void unmap_single_vma(struct mmu_gather *tlb,
1298                struct vm_area_struct *vma, unsigned long start_addr,
1299                unsigned long end_addr,
1300                struct zap_details *details)
1301{
1302        unsigned long start = max(vma->vm_start, start_addr);
1303        unsigned long end;
1304
1305        if (start >= vma->vm_end)
1306                return;
1307        end = min(vma->vm_end, end_addr);
1308        if (end <= vma->vm_start)
1309                return;
1310
1311        if (vma->vm_file)
1312                uprobe_munmap(vma, start, end);
1313
1314        if (unlikely(vma->vm_flags & VM_PFNMAP))
1315                untrack_pfn(vma, 0, 0);
1316
1317        if (start != end) {
1318                if (unlikely(is_vm_hugetlb_page(vma))) {
1319                        /*
1320                         * It is undesirable to test vma->vm_file as it
1321                         * should be non-null for valid hugetlb area.
1322                         * However, vm_file will be NULL in the error
1323                         * cleanup path of do_mmap_pgoff. When
1324                         * hugetlbfs ->mmap method fails,
1325                         * do_mmap_pgoff() nullifies vma->vm_file
1326                         * before calling this function to clean up.
1327                         * Since no pte has actually been setup, it is
1328                         * safe to do nothing in this case.
1329                         */
1330                        if (vma->vm_file) {
1331                                mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1332                                __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1333                                mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1334                        }
1335                } else
1336                        unmap_page_range(tlb, vma, start, end, details);
1337        }
1338}
1339
1340/**
1341 * unmap_vmas - unmap a range of memory covered by a list of vma's
1342 * @tlb: address of the caller's struct mmu_gather
1343 * @vma: the starting vma
1344 * @start_addr: virtual address at which to start unmapping
1345 * @end_addr: virtual address at which to end unmapping
1346 *
1347 * Unmap all pages in the vma list.
1348 *
1349 * Only addresses between `start' and `end' will be unmapped.
1350 *
1351 * The VMA list must be sorted in ascending virtual address order.
1352 *
1353 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1354 * range after unmap_vmas() returns.  So the only responsibility here is to
1355 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1356 * drops the lock and schedules.
1357 */
1358void unmap_vmas(struct mmu_gather *tlb,
1359                struct vm_area_struct *vma, unsigned long start_addr,
1360                unsigned long end_addr)
1361{
1362        struct mm_struct *mm = vma->vm_mm;
1363
1364        mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1365        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1366                unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1367        mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1368}
1369
1370/**
1371 * zap_page_range - remove user pages in a given range
1372 * @vma: vm_area_struct holding the applicable pages
1373 * @start: starting address of pages to zap
1374 * @size: number of bytes to zap
1375 * @details: details of nonlinear truncation or shared cache invalidation
1376 *
1377 * Caller must protect the VMA list
1378 */
1379void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1380                unsigned long size, struct zap_details *details)
1381{
1382        struct mm_struct *mm = vma->vm_mm;
1383        struct mmu_gather tlb;
1384        unsigned long end = start + size;
1385
1386        lru_add_drain();
1387        tlb_gather_mmu(&tlb, mm, start, end);
1388        update_hiwater_rss(mm);
1389        mmu_notifier_invalidate_range_start(mm, start, end);
1390        for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1391                unmap_single_vma(&tlb, vma, start, end, details);
1392        mmu_notifier_invalidate_range_end(mm, start, end);
1393        tlb_finish_mmu(&tlb, start, end);
1394}
1395
1396/**
1397 * zap_page_range_single - remove user pages in a given range
1398 * @vma: vm_area_struct holding the applicable pages
1399 * @address: starting address of pages to zap
1400 * @size: number of bytes to zap
1401 * @details: details of nonlinear truncation or shared cache invalidation
1402 *
1403 * The range must fit into one VMA.
1404 */
1405static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1406                unsigned long size, struct zap_details *details)
1407{
1408        struct mm_struct *mm = vma->vm_mm;
1409        struct mmu_gather tlb;
1410        unsigned long end = address + size;
1411
1412        lru_add_drain();
1413        tlb_gather_mmu(&tlb, mm, address, end);
1414        update_hiwater_rss(mm);
1415        mmu_notifier_invalidate_range_start(mm, address, end);
1416        unmap_single_vma(&tlb, vma, address, end, details);
1417        mmu_notifier_invalidate_range_end(mm, address, end);
1418        tlb_finish_mmu(&tlb, address, end);
1419}
1420
1421/**
1422 * zap_vma_ptes - remove ptes mapping the vma
1423 * @vma: vm_area_struct holding ptes to be zapped
1424 * @address: starting address of pages to zap
1425 * @size: number of bytes to zap
1426 *
1427 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1428 *
1429 * The entire address range must be fully contained within the vma.
1430 *
1431 * Returns 0 if successful.
1432 */
1433int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1434                unsigned long size)
1435{
1436        if (address < vma->vm_start || address + size > vma->vm_end ||
1437                        !(vma->vm_flags & VM_PFNMAP))
1438                return -1;
1439        zap_page_range_single(vma, address, size, NULL);
1440        return 0;
1441}
1442EXPORT_SYMBOL_GPL(zap_vma_ptes);
1443
1444/**
1445 * follow_page_mask - look up a page descriptor from a user-virtual address
1446 * @vma: vm_area_struct mapping @address
1447 * @address: virtual address to look up
1448 * @flags: flags modifying lookup behaviour
1449 * @page_mask: on output, *page_mask is set according to the size of the page
1450 *
1451 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1452 *
1453 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1454 * an error pointer if there is a mapping to something not represented
1455 * by a page descriptor (see also vm_normal_page()).
1456 */
1457struct page *follow_page_mask(struct vm_area_struct *vma,
1458                              unsigned long address, unsigned int flags,
1459                              unsigned int *page_mask)
1460{
1461        pgd_t *pgd;
1462        pud_t *pud;
1463        pmd_t *pmd;
1464        pte_t *ptep, pte;
1465        spinlock_t *ptl;
1466        struct page *page;
1467        struct mm_struct *mm = vma->vm_mm;
1468
1469        *page_mask = 0;
1470
1471        page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1472        if (!IS_ERR(page)) {
1473                BUG_ON(flags & FOLL_GET);
1474                goto out;
1475        }
1476
1477        page = NULL;
1478        pgd = pgd_offset(mm, address);
1479        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1480                goto no_page_table;
1481
1482        pud = pud_offset(pgd, address);
1483        if (pud_none(*pud))
1484                goto no_page_table;
1485        if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1486                if (flags & FOLL_GET)
1487                        goto out;
1488                page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1489                goto out;
1490        }
1491        if (unlikely(pud_bad(*pud)))
1492                goto no_page_table;
1493
1494        pmd = pmd_offset(pud, address);
1495        if (pmd_none(*pmd))
1496                goto no_page_table;
1497        if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1498                page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1499                if (flags & FOLL_GET) {
1500                        /*
1501                         * Refcount on tail pages are not well-defined and
1502                         * shouldn't be taken. The caller should handle a NULL
1503                         * return when trying to follow tail pages.
1504                         */
1505                        if (PageHead(page))
1506                                get_page(page);
1507                        else {
1508                                page = NULL;
1509                                goto out;
1510                        }
1511                }
1512                goto out;
1513        }
1514        if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1515                goto no_page_table;
1516        if (pmd_trans_huge(*pmd)) {
1517                if (flags & FOLL_SPLIT) {
1518                        split_huge_page_pmd(vma, address, pmd);
1519                        goto split_fallthrough;
1520                }
1521                spin_lock(&mm->page_table_lock);
1522                if (likely(pmd_trans_huge(*pmd))) {
1523                        if (unlikely(pmd_trans_splitting(*pmd))) {
1524                                spin_unlock(&mm->page_table_lock);
1525                                wait_split_huge_page(vma->anon_vma, pmd);
1526                        } else {
1527                                page = follow_trans_huge_pmd(vma, address,
1528                                                             pmd, flags);
1529                                spin_unlock(&mm->page_table_lock);
1530                                *page_mask = HPAGE_PMD_NR - 1;
1531                                goto out;
1532                        }
1533                } else
1534                        spin_unlock(&mm->page_table_lock);
1535                /* fall through */
1536        }
1537split_fallthrough:
1538        if (unlikely(pmd_bad(*pmd)))
1539                goto no_page_table;
1540
1541        ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1542
1543        pte = *ptep;
1544        if (!pte_present(pte)) {
1545                swp_entry_t entry;
1546                /*
1547                 * KSM's break_ksm() relies upon recognizing a ksm page
1548                 * even while it is being migrated, so for that case we
1549                 * need migration_entry_wait().
1550                 */
1551                if (likely(!(flags & FOLL_MIGRATION)))
1552                        goto no_page;
1553                if (pte_none(pte) || pte_file(pte))
1554                        goto no_page;
1555                entry = pte_to_swp_entry(pte);
1556                if (!is_migration_entry(entry))
1557                        goto no_page;
1558                pte_unmap_unlock(ptep, ptl);
1559                migration_entry_wait(mm, pmd, address);
1560                goto split_fallthrough;
1561        }
1562        if ((flags & FOLL_NUMA) && pte_numa(pte))
1563                goto no_page;
1564        if ((flags & FOLL_WRITE) && !pte_write(pte))
1565                goto unlock;
1566
1567        page = vm_normal_page(vma, address, pte);
1568        if (unlikely(!page)) {
1569                if ((flags & FOLL_DUMP) ||
1570                    !is_zero_pfn(pte_pfn(pte)))
1571                        goto bad_page;
1572                page = pte_page(pte);
1573        }
1574
1575        if (flags & FOLL_GET)
1576                get_page_foll(page);
1577        if (flags & FOLL_TOUCH) {
1578                if ((flags & FOLL_WRITE) &&
1579                    !pte_dirty(pte) && !PageDirty(page))
1580                        set_page_dirty(page);
1581                /*
1582                 * pte_mkyoung() would be more correct here, but atomic care
1583                 * is needed to avoid losing the dirty bit: it is easier to use
1584                 * mark_page_accessed().
1585                 */
1586                mark_page_accessed(page);
1587        }
1588        if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1589                /*
1590                 * The preliminary mapping check is mainly to avoid the
1591                 * pointless overhead of lock_page on the ZERO_PAGE
1592                 * which might bounce very badly if there is contention.
1593                 *
1594                 * If the page is already locked, we don't need to
1595                 * handle it now - vmscan will handle it later if and
1596                 * when it attempts to reclaim the page.
1597                 */
1598                if (page->mapping && trylock_page(page)) {
1599                        lru_add_drain();  /* push cached pages to LRU */
1600                        /*
1601                         * Because we lock page here, and migration is
1602                         * blocked by the pte's page reference, and we
1603                         * know the page is still mapped, we don't even
1604                         * need to check for file-cache page truncation.
1605                         */
1606                        mlock_vma_page(page);
1607                        unlock_page(page);
1608                }
1609        }
1610unlock:
1611        pte_unmap_unlock(ptep, ptl);
1612out:
1613        return page;
1614
1615bad_page:
1616        pte_unmap_unlock(ptep, ptl);
1617        return ERR_PTR(-EFAULT);
1618
1619no_page:
1620        pte_unmap_unlock(ptep, ptl);
1621        if (!pte_none(pte))
1622                return page;
1623
1624no_page_table:
1625        /*
1626         * When core dumping an enormous anonymous area that nobody
1627         * has touched so far, we don't want to allocate unnecessary pages or
1628         * page tables.  Return error instead of NULL to skip handle_mm_fault,
1629         * then get_dump_page() will return NULL to leave a hole in the dump.
1630         * But we can only make this optimization where a hole would surely
1631         * be zero-filled if handle_mm_fault() actually did handle it.
1632         */
1633        if ((flags & FOLL_DUMP) &&
1634            (!vma->vm_ops || !vma->vm_ops->fault))
1635                return ERR_PTR(-EFAULT);
1636        return page;
1637}
1638
1639static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1640{
1641        return stack_guard_page_start(vma, addr) ||
1642               stack_guard_page_end(vma, addr+PAGE_SIZE);
1643}
1644
1645/**
1646 * __get_user_pages() - pin user pages in memory
1647 * @tsk:        task_struct of target task
1648 * @mm:         mm_struct of target mm
1649 * @start:      starting user address
1650 * @nr_pages:   number of pages from start to pin
1651 * @gup_flags:  flags modifying pin behaviour
1652 * @pages:      array that receives pointers to the pages pinned.
1653 *              Should be at least nr_pages long. Or NULL, if caller
1654 *              only intends to ensure the pages are faulted in.
1655 * @vmas:       array of pointers to vmas corresponding to each page.
1656 *              Or NULL if the caller does not require them.
1657 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1658 *
1659 * Returns number of pages pinned. This may be fewer than the number
1660 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1661 * were pinned, returns -errno. Each page returned must be released
1662 * with a put_page() call when it is finished with. vmas will only
1663 * remain valid while mmap_sem is held.
1664 *
1665 * Must be called with mmap_sem held for read or write.
1666 *
1667 * __get_user_pages walks a process's page tables and takes a reference to
1668 * each struct page that each user address corresponds to at a given
1669 * instant. That is, it takes the page that would be accessed if a user
1670 * thread accesses the given user virtual address at that instant.
1671 *
1672 * This does not guarantee that the page exists in the user mappings when
1673 * __get_user_pages returns, and there may even be a completely different
1674 * page there in some cases (eg. if mmapped pagecache has been invalidated
1675 * and subsequently re faulted). However it does guarantee that the page
1676 * won't be freed completely. And mostly callers simply care that the page
1677 * contains data that was valid *at some point in time*. Typically, an IO
1678 * or similar operation cannot guarantee anything stronger anyway because
1679 * locks can't be held over the syscall boundary.
1680 *
1681 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1682 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1683 * appropriate) must be called after the page is finished with, and
1684 * before put_page is called.
1685 *
1686 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1687 * or mmap_sem contention, and if waiting is needed to pin all pages,
1688 * *@nonblocking will be set to 0.
1689 *
1690 * In most cases, get_user_pages or get_user_pages_fast should be used
1691 * instead of __get_user_pages. __get_user_pages should be used only if
1692 * you need some special @gup_flags.
1693 */
1694long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1695                unsigned long start, unsigned long nr_pages,
1696                unsigned int gup_flags, struct page **pages,
1697                struct vm_area_struct **vmas, int *nonblocking)
1698{
1699        long i;
1700        unsigned long vm_flags;
1701        unsigned int page_mask;
1702
1703        if (!nr_pages)
1704                return 0;
1705
1706        VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1707
1708        /* 
1709         * Require read or write permissions.
1710         * If FOLL_FORCE is set, we only require the "MAY" flags.
1711         */
1712        vm_flags  = (gup_flags & FOLL_WRITE) ?
1713                        (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1714        vm_flags &= (gup_flags & FOLL_FORCE) ?
1715                        (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1716
1717        /*
1718         * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
1719         * would be called on PROT_NONE ranges. We must never invoke
1720         * handle_mm_fault on PROT_NONE ranges or the NUMA hinting
1721         * page faults would unprotect the PROT_NONE ranges if
1722         * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
1723         * bitflag. So to avoid that, don't set FOLL_NUMA if
1724         * FOLL_FORCE is set.
1725         */
1726        if (!(gup_flags & FOLL_FORCE))
1727                gup_flags |= FOLL_NUMA;
1728
1729        i = 0;
1730
1731        do {
1732                struct vm_area_struct *vma;
1733
1734                vma = find_extend_vma(mm, start);
1735                if (!vma && in_gate_area(mm, start)) {
1736                        unsigned long pg = start & PAGE_MASK;
1737                        pgd_t *pgd;
1738                        pud_t *pud;
1739                        pmd_t *pmd;
1740                        pte_t *pte;
1741
1742                        /* user gate pages are read-only */
1743                        if (gup_flags & FOLL_WRITE)
1744                                return i ? : -EFAULT;
1745                        if (pg > TASK_SIZE)
1746                                pgd = pgd_offset_k(pg);
1747                        else
1748                                pgd = pgd_offset_gate(mm, pg);
1749                        BUG_ON(pgd_none(*pgd));
1750                        pud = pud_offset(pgd, pg);
1751                        BUG_ON(pud_none(*pud));
1752                        pmd = pmd_offset(pud, pg);
1753                        if (pmd_none(*pmd))
1754                                return i ? : -EFAULT;
1755                        VM_BUG_ON(pmd_trans_huge(*pmd));
1756                        pte = pte_offset_map(pmd, pg);
1757                        if (pte_none(*pte)) {
1758                                pte_unmap(pte);
1759                                return i ? : -EFAULT;
1760                        }
1761                        vma = get_gate_vma(mm);
1762                        if (pages) {
1763                                struct page *page;
1764
1765                                page = vm_normal_page(vma, start, *pte);
1766                                if (!page) {
1767                                        if (!(gup_flags & FOLL_DUMP) &&
1768                                             is_zero_pfn(pte_pfn(*pte)))
1769                                                page = pte_page(*pte);
1770                                        else {
1771                                                pte_unmap(pte);
1772                                                return i ? : -EFAULT;
1773                                        }
1774                                }
1775                                pages[i] = page;
1776                                get_page(page);
1777                        }
1778                        pte_unmap(pte);
1779                        page_mask = 0;
1780                        goto next_page;
1781                }
1782
1783                if (!vma ||
1784                    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1785                    !(vm_flags & vma->vm_flags))
1786                        return i ? : -EFAULT;
1787
1788                if (is_vm_hugetlb_page(vma)) {
1789                        i = follow_hugetlb_page(mm, vma, pages, vmas,
1790                                        &start, &nr_pages, i, gup_flags);
1791                        continue;
1792                }
1793
1794                do {
1795                        struct page *page;
1796                        unsigned int foll_flags = gup_flags;
1797                        unsigned int page_increm;
1798
1799                        /*
1800                         * If we have a pending SIGKILL, don't keep faulting
1801                         * pages and potentially allocating memory.
1802                         */
1803                        if (unlikely(fatal_signal_pending(current)))
1804                                return i ? i : -ERESTARTSYS;
1805
1806                        cond_resched();
1807                        while (!(page = follow_page_mask(vma, start,
1808                                                foll_flags, &page_mask))) {
1809                                int ret;
1810                                unsigned int fault_flags = 0;
1811
1812                                /* For mlock, just skip the stack guard page. */
1813                                if (foll_flags & FOLL_MLOCK) {
1814                                        if (stack_guard_page(vma, start))
1815                                                goto next_page;
1816                                }
1817                                if (foll_flags & FOLL_WRITE)
1818                                        fault_flags |= FAULT_FLAG_WRITE;
1819                                if (nonblocking)
1820                                        fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1821                                if (foll_flags & FOLL_NOWAIT)
1822                                        fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1823
1824                                ret = handle_mm_fault(mm, vma, start,
1825                                                        fault_flags);
1826
1827                                if (ret & VM_FAULT_ERROR) {
1828                                        if (ret & VM_FAULT_OOM)
1829                                                return i ? i : -ENOMEM;
1830                                        if (ret & (VM_FAULT_HWPOISON |
1831                                                   VM_FAULT_HWPOISON_LARGE)) {
1832                                                if (i)
1833                                                        return i;
1834                                                else if (gup_flags & FOLL_HWPOISON)
1835                                                        return -EHWPOISON;
1836                                                else
1837                                                        return -EFAULT;
1838                                        }
1839                                        if (ret & VM_FAULT_SIGBUS)
1840                                                return i ? i : -EFAULT;
1841                                        BUG();
1842                                }
1843
1844                                if (tsk) {
1845                                        if (ret & VM_FAULT_MAJOR)
1846                                                tsk->maj_flt++;
1847                                        else
1848                                                tsk->min_flt++;
1849                                }
1850
1851                                if (ret & VM_FAULT_RETRY) {
1852                                        if (nonblocking)
1853                                                *nonblocking = 0;
1854                                        return i;
1855                                }
1856
1857                                /*
1858                                 * The VM_FAULT_WRITE bit tells us that
1859                                 * do_wp_page has broken COW when necessary,
1860                                 * even if maybe_mkwrite decided not to set
1861                                 * pte_write. We can thus safely do subsequent
1862                                 * page lookups as if they were reads. But only
1863                                 * do so when looping for pte_write is futile:
1864                                 * in some cases userspace may also be wanting
1865                                 * to write to the gotten user page, which a
1866                                 * read fault here might prevent (a readonly
1867                                 * page might get reCOWed by userspace write).
1868                                 */
1869                                if ((ret & VM_FAULT_WRITE) &&
1870                                    !(vma->vm_flags & VM_WRITE))
1871                                        foll_flags &= ~FOLL_WRITE;
1872
1873                                cond_resched();
1874                        }
1875                        if (IS_ERR(page))
1876                                return i ? i : PTR_ERR(page);
1877                        if (pages) {
1878                                pages[i] = page;
1879
1880                                flush_anon_page(vma, page, start);
1881                                flush_dcache_page(page);
1882                                page_mask = 0;
1883                        }
1884next_page:
1885                        if (vmas) {
1886                                vmas[i] = vma;
1887                                page_mask = 0;
1888                        }
1889                        page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
1890                        if (page_increm > nr_pages)
1891                                page_increm = nr_pages;
1892                        i += page_increm;
1893                        start += page_increm * PAGE_SIZE;
1894                        nr_pages -= page_increm;
1895                } while (nr_pages && start < vma->vm_end);
1896        } while (nr_pages);
1897        return i;
1898}
1899EXPORT_SYMBOL(__get_user_pages);
1900
1901/*
1902 * fixup_user_fault() - manually resolve a user page fault
1903 * @tsk:        the task_struct to use for page fault accounting, or
1904 *              NULL if faults are not to be recorded.
1905 * @mm:         mm_struct of target mm
1906 * @address:    user address
1907 * @fault_flags:flags to pass down to handle_mm_fault()
1908 *
1909 * This is meant to be called in the specific scenario where for locking reasons
1910 * we try to access user memory in atomic context (within a pagefault_disable()
1911 * section), this returns -EFAULT, and we want to resolve the user fault before
1912 * trying again.
1913 *
1914 * Typically this is meant to be used by the futex code.
1915 *
1916 * The main difference with get_user_pages() is that this function will
1917 * unconditionally call handle_mm_fault() which will in turn perform all the
1918 * necessary SW fixup of the dirty and young bits in the PTE, while
1919 * handle_mm_fault() only guarantees to update these in the struct page.
1920 *
1921 * This is important for some architectures where those bits also gate the
1922 * access permission to the page because they are maintained in software.  On
1923 * such architectures, gup() will not be enough to make a subsequent access
1924 * succeed.
1925 *
1926 * This should be called with the mm_sem held for read.
1927 */
1928int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1929                     unsigned long address, unsigned int fault_flags)
1930{
1931        struct vm_area_struct *vma;
1932        int ret;
1933
1934        vma = find_extend_vma(mm, address);
1935        if (!vma || address < vma->vm_start)
1936                return -EFAULT;
1937
1938        ret = handle_mm_fault(mm, vma, address, fault_flags);
1939        if (ret & VM_FAULT_ERROR) {
1940                if (ret & VM_FAULT_OOM)
1941                        return -ENOMEM;
1942                if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1943                        return -EHWPOISON;
1944                if (ret & VM_FAULT_SIGBUS)
1945                        return -EFAULT;
1946                BUG();
1947        }
1948        if (tsk) {
1949                if (ret & VM_FAULT_MAJOR)
1950                        tsk->maj_flt++;
1951                else
1952                        tsk->min_flt++;
1953        }
1954        return 0;
1955}
1956
1957/*
1958 * get_user_pages() - pin user pages in memory
1959 * @tsk:        the task_struct to use for page fault accounting, or
1960 *              NULL if faults are not to be recorded.
1961 * @mm:         mm_struct of target mm
1962 * @start:      starting user address
1963 * @nr_pages:   number of pages from start to pin
1964 * @write:      whether pages will be written to by the caller
1965 * @force:      whether to force write access even if user mapping is
1966 *              readonly. This will result in the page being COWed even
1967 *              in MAP_SHARED mappings. You do not want this.
1968 * @pages:      array that receives pointers to the pages pinned.
1969 *              Should be at least nr_pages long. Or NULL, if caller
1970 *              only intends to ensure the pages are faulted in.
1971 * @vmas:       array of pointers to vmas corresponding to each page.
1972 *              Or NULL if the caller does not require them.
1973 *
1974 * Returns number of pages pinned. This may be fewer than the number
1975 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1976 * were pinned, returns -errno. Each page returned must be released
1977 * with a put_page() call when it is finished with. vmas will only
1978 * remain valid while mmap_sem is held.
1979 *
1980 * Must be called with mmap_sem held for read or write.
1981 *
1982 * get_user_pages walks a process's page tables and takes a reference to
1983 * each struct page that each user address corresponds to at a given
1984 * instant. That is, it takes the page that would be accessed if a user
1985 * thread accesses the given user virtual address at that instant.
1986 *
1987 * This does not guarantee that the page exists in the user mappings when
1988 * get_user_pages returns, and there may even be a completely different
1989 * page there in some cases (eg. if mmapped pagecache has been invalidated
1990 * and subsequently re faulted). However it does guarantee that the page
1991 * won't be freed completely. And mostly callers simply care that the page
1992 * contains data that was valid *at some point in time*. Typically, an IO
1993 * or similar operation cannot guarantee anything stronger anyway because
1994 * locks can't be held over the syscall boundary.
1995 *
1996 * If write=0, the page must not be written to. If the page is written to,
1997 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1998 * after the page is finished with, and before put_page is called.
1999 *
2000 * get_user_pages is typically used for fewer-copy IO operations, to get a
2001 * handle on the memory by some means other than accesses via the user virtual
2002 * addresses. The pages may be submitted for DMA to devices or accessed via
2003 * their kernel linear mapping (via the kmap APIs). Care should be taken to
2004 * use the correct cache flushing APIs.
2005 *
2006 * See also get_user_pages_fast, for performance critical applications.
2007 */
2008long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
2009                unsigned long start, unsigned long nr_pages, int write,
2010                int force, struct page **pages, struct vm_area_struct **vmas)
2011{
2012        int flags = FOLL_TOUCH;
2013
2014        if (pages)
2015                flags |= FOLL_GET;
2016        if (write)
2017                flags |= FOLL_WRITE;
2018        if (force)
2019                flags |= FOLL_FORCE;
2020
2021        return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
2022                                NULL);
2023}
2024EXPORT_SYMBOL(get_user_pages);
2025
2026/**
2027 * get_dump_page() - pin user page in memory while writing it to core dump
2028 * @addr: user address
2029 *
2030 * Returns struct page pointer of user page pinned for dump,
2031 * to be freed afterwards by page_cache_release() or put_page().
2032 *
2033 * Returns NULL on any kind of failure - a hole must then be inserted into
2034 * the corefile, to preserve alignment with its headers; and also returns
2035 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
2036 * allowing a hole to be left in the corefile to save diskspace.
2037 *
2038 * Called without mmap_sem, but after all other threads have been killed.
2039 */
2040#ifdef CONFIG_ELF_CORE
2041struct page *get_dump_page(unsigned long addr)
2042{
2043        struct vm_area_struct *vma;
2044        struct page *page;
2045
2046        if (__get_user_pages(current, current->mm, addr, 1,
2047                             FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
2048                             NULL) < 1)
2049                return NULL;
2050        flush_cache_page(vma, addr, page_to_pfn(page));
2051        return page;
2052}
2053#endif /* CONFIG_ELF_CORE */
2054
2055pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
2056                        spinlock_t **ptl)
2057{
2058        pgd_t * pgd = pgd_offset(mm, addr);
2059        pud_t * pud = pud_alloc(mm, pgd, addr);
2060        if (pud) {
2061                pmd_t * pmd = pmd_alloc(mm, pud, addr);
2062                if (pmd) {
2063                        VM_BUG_ON(pmd_trans_huge(*pmd));
2064                        return pte_alloc_map_lock(mm, pmd, addr, ptl);
2065                }
2066        }
2067        return NULL;
2068}
2069
2070/*
2071 * This is the old fallback for page remapping.
2072 *
2073 * For historical reasons, it only allows reserved pages. Only
2074 * old drivers should use this, and they needed to mark their
2075 * pages reserved for the old functions anyway.
2076 */
2077static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2078                        struct page *page, pgprot_t prot)
2079{
2080        struct mm_struct *mm = vma->vm_mm;
2081        int retval;
2082        pte_t *pte;
2083        spinlock_t *ptl;
2084
2085        retval = -EINVAL;
2086        if (PageAnon(page))
2087                goto out;
2088        retval = -ENOMEM;
2089        flush_dcache_page(page);
2090        pte = get_locked_pte(mm, addr, &ptl);
2091        if (!pte)
2092                goto out;
2093        retval = -EBUSY;
2094        if (!pte_none(*pte))
2095                goto out_unlock;
2096
2097        /* Ok, finally just insert the thing.. */
2098        get_page(page);
2099        inc_mm_counter_fast(mm, MM_FILEPAGES);
2100        page_add_file_rmap(page);
2101        set_pte_at(mm, addr, pte, mk_pte(page, prot));
2102
2103        retval = 0;
2104        pte_unmap_unlock(pte, ptl);
2105        return retval;
2106out_unlock:
2107        pte_unmap_unlock(pte, ptl);
2108out:
2109        return retval;
2110}
2111
2112/**
2113 * vm_insert_page - insert single page into user vma
2114 * @vma: user vma to map to
2115 * @addr: target user address of this page
2116 * @page: source kernel page
2117 *
2118 * This allows drivers to insert individual pages they've allocated
2119 * into a user vma.
2120 *
2121 * The page has to be a nice clean _individual_ kernel allocation.
2122 * If you allocate a compound page, you need to have marked it as
2123 * such (__GFP_COMP), or manually just split the page up yourself
2124 * (see split_page()).
2125 *
2126 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2127 * took an arbitrary page protection parameter. This doesn't allow
2128 * that. Your vma protection will have to be set up correctly, which
2129 * means that if you want a shared writable mapping, you'd better
2130 * ask for a shared writable mapping!
2131 *
2132 * The page does not need to be reserved.
2133 *
2134 * Usually this function is called from f_op->mmap() handler
2135 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
2136 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2137 * function from other places, for example from page-fault handler.
2138 */
2139int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2140                        struct page *page)
2141{
2142        if (addr < vma->vm_start || addr >= vma->vm_end)
2143                return -EFAULT;
2144        if (!page_count(page))
2145                return -EINVAL;
2146        if (!(vma->vm_flags & VM_MIXEDMAP)) {
2147                BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
2148                BUG_ON(vma->vm_flags & VM_PFNMAP);
2149                vma->vm_flags |= VM_MIXEDMAP;
2150        }
2151        return insert_page(vma, addr, page, vma->vm_page_prot);
2152}
2153EXPORT_SYMBOL(vm_insert_page);
2154
2155static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2156                        unsigned long pfn, pgprot_t prot)
2157{
2158        struct mm_struct *mm = vma->vm_mm;
2159        int retval;
2160        pte_t *pte, entry;
2161        spinlock_t *ptl;
2162
2163        retval = -ENOMEM;
2164        pte = get_locked_pte(mm, addr, &ptl);
2165        if (!pte)
2166                goto out;
2167        retval = -EBUSY;
2168        if (!pte_none(*pte))
2169                goto out_unlock;
2170
2171        /* Ok, finally just insert the thing.. */
2172        entry = pte_mkspecial(pfn_pte(pfn, prot));
2173        set_pte_at(mm, addr, pte, entry);
2174        update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2175
2176        retval = 0;
2177out_unlock:
2178        pte_unmap_unlock(pte, ptl);
2179out:
2180        return retval;
2181}
2182
2183/**
2184 * vm_insert_pfn - insert single pfn into user vma
2185 * @vma: user vma to map to
2186 * @addr: target user address of this page
2187 * @pfn: source kernel pfn
2188 *
2189 * Similar to vm_insert_page, this allows drivers to insert individual pages
2190 * they've allocated into a user vma. Same comments apply.
2191 *
2192 * This function should only be called from a vm_ops->fault handler, and
2193 * in that case the handler should return NULL.
2194 *
2195 * vma cannot be a COW mapping.
2196 *
2197 * As this is called only for pages that do not currently exist, we
2198 * do not need to flush old virtual caches or the TLB.
2199 */
2200int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2201                        unsigned long pfn)
2202{
2203        int ret;
2204        pgprot_t pgprot = vma->vm_page_prot;
2205        /*
2206         * Technically, architectures with pte_special can avoid all these
2207         * restrictions (same for remap_pfn_range).  However we would like
2208         * consistency in testing and feature parity among all, so we should
2209         * try to keep these invariants in place for everybody.
2210         */
2211        BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2212        BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2213                                                (VM_PFNMAP|VM_MIXEDMAP));
2214        BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2215        BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2216
2217        if (addr < vma->vm_start || addr >= vma->vm_end)
2218                return -EFAULT;
2219        if (track_pfn_insert(vma, &pgprot, pfn))
2220                return -EINVAL;
2221
2222        ret = insert_pfn(vma, addr, pfn, pgprot);
2223
2224        return ret;
2225}
2226EXPORT_SYMBOL(vm_insert_pfn);
2227
2228int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2229                        unsigned long pfn)
2230{
2231        BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2232
2233        if (addr < vma->vm_start || addr >= vma->vm_end)
2234                return -EFAULT;
2235
2236        /*
2237         * If we don't have pte special, then we have to use the pfn_valid()
2238         * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2239         * refcount the page if pfn_valid is true (hence insert_page rather
2240         * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2241         * without pte special, it would there be refcounted as a normal page.
2242         */
2243        if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2244                struct page *page;
2245
2246                page = pfn_to_page(pfn);
2247                return insert_page(vma, addr, page, vma->vm_page_prot);
2248        }
2249        return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2250}
2251EXPORT_SYMBOL(vm_insert_mixed);
2252
2253/*
2254 * maps a range of physical memory into the requested pages. the old
2255 * mappings are removed. any references to nonexistent pages results
2256 * in null mappings (currently treated as "copy-on-access")
2257 */
2258static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2259                        unsigned long addr, unsigned long end,
2260                        unsigned long pfn, pgprot_t prot)
2261{
2262        pte_t *pte;
2263        spinlock_t *ptl;
2264
2265        pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2266        if (!pte)
2267                return -ENOMEM;
2268        arch_enter_lazy_mmu_mode();
2269        do {
2270                BUG_ON(!pte_none(*pte));
2271                set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2272                pfn++;
2273        } while (pte++, addr += PAGE_SIZE, addr != end);
2274        arch_leave_lazy_mmu_mode();
2275        pte_unmap_unlock(pte - 1, ptl);
2276        return 0;
2277}
2278
2279static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2280                        unsigned long addr, unsigned long end,
2281                        unsigned long pfn, pgprot_t prot)
2282{
2283        pmd_t *pmd;
2284        unsigned long next;
2285
2286        pfn -= addr >> PAGE_SHIFT;
2287        pmd = pmd_alloc(mm, pud, addr);
2288        if (!pmd)
2289                return -ENOMEM;
2290        VM_BUG_ON(pmd_trans_huge(*pmd));
2291        do {
2292                next = pmd_addr_end(addr, end);
2293                if (remap_pte_range(mm, pmd, addr, next,
2294                                pfn + (addr >> PAGE_SHIFT), prot))
2295                        return -ENOMEM;
2296        } while (pmd++, addr = next, addr != end);
2297        return 0;
2298}
2299
2300static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2301                        unsigned long addr, unsigned long end,
2302                        unsigned long pfn, pgprot_t prot)
2303{
2304        pud_t *pud;
2305        unsigned long next;
2306
2307        pfn -= addr >> PAGE_SHIFT;
2308        pud = pud_alloc(mm, pgd, addr);
2309        if (!pud)
2310                return -ENOMEM;
2311        do {
2312                next = pud_addr_end(addr, end);
2313                if (remap_pmd_range(mm, pud, addr, next,
2314                                pfn + (addr >> PAGE_SHIFT), prot))
2315                        return -ENOMEM;
2316        } while (pud++, addr = next, addr != end);
2317        return 0;
2318}
2319
2320/**
2321 * remap_pfn_range - remap kernel memory to userspace
2322 * @vma: user vma to map to
2323 * @addr: target user address to start at
2324 * @pfn: physical address of kernel memory
2325 * @size: size of map area
2326 * @prot: page protection flags for this mapping
2327 *
2328 *  Note: this is only safe if the mm semaphore is held when called.
2329 */
2330int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2331                    unsigned long pfn, unsigned long size, pgprot_t prot)
2332{
2333        pgd_t *pgd;
2334        unsigned long next;
2335        unsigned long end = addr + PAGE_ALIGN(size);
2336        struct mm_struct *mm = vma->vm_mm;
2337        int err;
2338
2339        /*
2340         * Physically remapped pages are special. Tell the
2341         * rest of the world about it:
2342         *   VM_IO tells people not to look at these pages
2343         *      (accesses can have side effects).
2344         *   VM_PFNMAP tells the core MM that the base pages are just
2345         *      raw PFN mappings, and do not have a "struct page" associated
2346         *      with them.
2347         *   VM_DONTEXPAND
2348         *      Disable vma merging and expanding with mremap().
2349         *   VM_DONTDUMP
2350         *      Omit vma from core dump, even when VM_IO turned off.
2351         *
2352         * There's a horrible special case to handle copy-on-write
2353         * behaviour that some programs depend on. We mark the "original"
2354         * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2355         * See vm_normal_page() for details.
2356         */
2357        if (is_cow_mapping(vma->vm_flags)) {
2358                if (addr != vma->vm_start || end != vma->vm_end)
2359                        return -EINVAL;
2360                vma->vm_pgoff = pfn;
2361        }
2362
2363        err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2364        if (err)
2365                return -EINVAL;
2366
2367        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2368
2369        BUG_ON(addr >= end);
2370        pfn -= addr >> PAGE_SHIFT;
2371        pgd = pgd_offset(mm, addr);
2372        flush_cache_range(vma, addr, end);
2373        do {
2374                next = pgd_addr_end(addr, end);
2375                err = remap_pud_range(mm, pgd, addr, next,
2376                                pfn + (addr >> PAGE_SHIFT), prot);
2377                if (err)
2378                        break;
2379        } while (pgd++, addr = next, addr != end);
2380
2381        if (err)
2382                untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2383
2384        return err;
2385}
2386EXPORT_SYMBOL(remap_pfn_range);
2387
2388/**
2389 * vm_iomap_memory - remap memory to userspace
2390 * @vma: user vma to map to
2391 * @start: start of area
2392 * @len: size of area
2393 *
2394 * This is a simplified io_remap_pfn_range() for common driver use. The
2395 * driver just needs to give us the physical memory range to be mapped,
2396 * we'll figure out the rest from the vma information.
2397 *
2398 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2399 * whatever write-combining details or similar.
2400 */
2401int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2402{
2403        unsigned long vm_len, pfn, pages;
2404
2405        /* Check that the physical memory area passed in looks valid */
2406        if (start + len < start)
2407                return -EINVAL;
2408        /*
2409         * You *really* shouldn't map things that aren't page-aligned,
2410         * but we've historically allowed it because IO memory might
2411         * just have smaller alignment.
2412         */
2413        len += start & ~PAGE_MASK;
2414        pfn = start >> PAGE_SHIFT;
2415        pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2416        if (pfn + pages < pfn)
2417                return -EINVAL;
2418
2419        /* We start the mapping 'vm_pgoff' pages into the area */
2420        if (vma->vm_pgoff > pages)
2421                return -EINVAL;
2422        pfn += vma->vm_pgoff;
2423        pages -= vma->vm_pgoff;
2424
2425        /* Can we fit all of the mapping? */
2426        vm_len = vma->vm_end - vma->vm_start;
2427        if (vm_len >> PAGE_SHIFT > pages)
2428                return -EINVAL;
2429
2430        /* Ok, let it rip */
2431        return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2432}
2433EXPORT_SYMBOL(vm_iomap_memory);
2434
2435static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2436                                     unsigned long addr, unsigned long end,
2437                                     pte_fn_t fn, void *data)
2438{
2439        pte_t *pte;
2440        int err;
2441        pgtable_t token;
2442        spinlock_t *uninitialized_var(ptl);
2443
2444        pte = (mm == &init_mm) ?
2445                pte_alloc_kernel(pmd, addr) :
2446                pte_alloc_map_lock(mm, pmd, addr, &ptl);
2447        if (!pte)
2448                return -ENOMEM;
2449
2450        BUG_ON(pmd_huge(*pmd));
2451
2452        arch_enter_lazy_mmu_mode();
2453
2454        token = pmd_pgtable(*pmd);
2455
2456        do {
2457                err = fn(pte++, token, addr, data);
2458                if (err)
2459                        break;
2460        } while (addr += PAGE_SIZE, addr != end);
2461
2462        arch_leave_lazy_mmu_mode();
2463
2464        if (mm != &init_mm)
2465                pte_unmap_unlock(pte-1, ptl);
2466        return err;
2467}
2468
2469static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2470                                     unsigned long addr, unsigned long end,
2471                                     pte_fn_t fn, void *data)
2472{
2473        pmd_t *pmd;
2474        unsigned long next;
2475        int err;
2476
2477        BUG_ON(pud_huge(*pud));
2478
2479        pmd = pmd_alloc(mm, pud, addr);
2480        if (!pmd)
2481                return -ENOMEM;
2482        do {
2483                next = pmd_addr_end(addr, end);
2484                err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2485                if (err)
2486                        break;
2487        } while (pmd++, addr = next, addr != end);
2488        return err;
2489}
2490
2491static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2492                                     unsigned long addr, unsigned long end,
2493                                     pte_fn_t fn, void *data)
2494{
2495        pud_t *pud;
2496        unsigned long next;
2497        int err;
2498
2499        pud = pud_alloc(mm, pgd, addr);
2500        if (!pud)
2501                return -ENOMEM;
2502        do {
2503                next = pud_addr_end(addr, end);
2504                err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2505                if (err)
2506                        break;
2507        } while (pud++, addr = next, addr != end);
2508        return err;
2509}
2510
2511/*
2512 * Scan a region of virtual memory, filling in page tables as necessary
2513 * and calling a provided function on each leaf page table.
2514 */
2515int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2516                        unsigned long size, pte_fn_t fn, void *data)
2517{
2518        pgd_t *pgd;
2519        unsigned long next;
2520        unsigned long end = addr + size;
2521        int err;
2522
2523        BUG_ON(addr >= end);
2524        pgd = pgd_offset(mm, addr);
2525        do {
2526                next = pgd_addr_end(addr, end);
2527                err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2528                if (err)
2529                        break;
2530        } while (pgd++, addr = next, addr != end);
2531
2532        return err;
2533}
2534EXPORT_SYMBOL_GPL(apply_to_page_range);
2535
2536/*
2537 * handle_pte_fault chooses page fault handler according to an entry
2538 * which was read non-atomically.  Before making any commitment, on
2539 * those architectures or configurations (e.g. i386 with PAE) which
2540 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2541 * must check under lock before unmapping the pte and proceeding
2542 * (but do_wp_page is only called after already making such a check;
2543 * and do_anonymous_page can safely check later on).
2544 */
2545static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2546                                pte_t *page_table, pte_t orig_pte)
2547{
2548        int same = 1;
2549#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2550        if (sizeof(pte_t) > sizeof(unsigned long)) {
2551                spinlock_t *ptl = pte_lockptr(mm, pmd);
2552                spin_lock(ptl);
2553                same = pte_same(*page_table, orig_pte);
2554                spin_unlock(ptl);
2555        }
2556#endif
2557        pte_unmap(page_table);
2558        return same;
2559}
2560
2561static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2562{
2563        /*
2564         * If the source page was a PFN mapping, we don't have
2565         * a "struct page" for it. We do a best-effort copy by
2566         * just copying from the original user address. If that
2567         * fails, we just zero-fill it. Live with it.
2568         */
2569        if (unlikely(!src)) {
2570                void *kaddr = kmap_atomic(dst);
2571                void __user *uaddr = (void __user *)(va & PAGE_MASK);
2572
2573                /*
2574                 * This really shouldn't fail, because the page is there
2575                 * in the page tables. But it might just be unreadable,
2576                 * in which case we just give up and fill the result with
2577                 * zeroes.
2578                 */
2579                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2580                        clear_page(kaddr);
2581                kunmap_atomic(kaddr);
2582                flush_dcache_page(dst);
2583        } else
2584                copy_user_highpage(dst, src, va, vma);
2585}
2586
2587/*
2588 * This routine handles present pages, when users try to write
2589 * to a shared page. It is done by copying the page to a new address
2590 * and decrementing the shared-page counter for the old page.
2591 *
2592 * Note that this routine assumes that the protection checks have been
2593 * done by the caller (the low-level page fault routine in most cases).
2594 * Thus we can safely just mark it writable once we've done any necessary
2595 * COW.
2596 *
2597 * We also mark the page dirty at this point even though the page will
2598 * change only once the write actually happens. This avoids a few races,
2599 * and potentially makes it more efficient.
2600 *
2601 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2602 * but allow concurrent faults), with pte both mapped and locked.
2603 * We return with mmap_sem still held, but pte unmapped and unlocked.
2604 */
2605static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2606                unsigned long address, pte_t *page_table, pmd_t *pmd,
2607                spinlock_t *ptl, pte_t orig_pte)
2608        __releases(ptl)
2609{
2610        struct page *old_page, *new_page = NULL;
2611        pte_t entry;
2612        int ret = 0;
2613        int page_mkwrite = 0;
2614        struct page *dirty_page = NULL;
2615        unsigned long mmun_start = 0;   /* For mmu_notifiers */
2616        unsigned long mmun_end = 0;     /* For mmu_notifiers */
2617
2618        old_page = vm_normal_page(vma, address, orig_pte);
2619        if (!old_page) {
2620                /*
2621                 * VM_MIXEDMAP !pfn_valid() case
2622                 *
2623                 * We should not cow pages in a shared writeable mapping.
2624                 * Just mark the pages writable as we can't do any dirty
2625                 * accounting on raw pfn maps.
2626                 */
2627                if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2628                                     (VM_WRITE|VM_SHARED))
2629                        goto reuse;
2630                goto gotten;
2631        }
2632
2633        /*
2634         * Take out anonymous pages first, anonymous shared vmas are
2635         * not dirty accountable.
2636         */
2637        if (PageAnon(old_page) && !PageKsm(old_page)) {
2638                if (!trylock_page(old_page)) {
2639                        page_cache_get(old_page);
2640                        pte_unmap_unlock(page_table, ptl);
2641                        lock_page(old_page);
2642                        page_table = pte_offset_map_lock(mm, pmd, address,
2643                                                         &ptl);
2644                        if (!pte_same(*page_table, orig_pte)) {
2645                                unlock_page(old_page);
2646                                goto unlock;
2647                        }
2648                        page_cache_release(old_page);
2649                }
2650                if (reuse_swap_page(old_page)) {
2651                        /*
2652                         * The page is all ours.  Move it to our anon_vma so
2653                         * the rmap code will not search our parent or siblings.
2654                         * Protected against the rmap code by the page lock.
2655                         */
2656                        page_move_anon_rmap(old_page, vma, address);
2657                        unlock_page(old_page);
2658                        goto reuse;
2659                }
2660                unlock_page(old_page);
2661        } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2662                                        (VM_WRITE|VM_SHARED))) {
2663                /*
2664                 * Only catch write-faults on shared writable pages,
2665                 * read-only shared pages can get COWed by
2666                 * get_user_pages(.write=1, .force=1).
2667                 */
2668                if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2669                        struct vm_fault vmf;
2670                        int tmp;
2671
2672                        vmf.virtual_address = (void __user *)(address &
2673                                                                PAGE_MASK);
2674                        vmf.pgoff = old_page->index;
2675                        vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2676                        vmf.page = old_page;
2677
2678                        /*
2679                         * Notify the address space that the page is about to
2680                         * become writable so that it can prohibit this or wait
2681                         * for the page to get into an appropriate state.
2682                         *
2683                         * We do this without the lock held, so that it can
2684                         * sleep if it needs to.
2685                         */
2686                        page_cache_get(old_page);
2687                        pte_unmap_unlock(page_table, ptl);
2688
2689                        tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2690                        if (unlikely(tmp &
2691                                        (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2692                                ret = tmp;
2693                                goto unwritable_page;
2694                        }
2695                        if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2696                                lock_page(old_page);
2697                                if (!old_page->mapping) {
2698                                        ret = 0; /* retry the fault */
2699                                        unlock_page(old_page);
2700                                        goto unwritable_page;
2701                                }
2702                        } else
2703                                VM_BUG_ON(!PageLocked(old_page));
2704
2705                        /*
2706                         * Since we dropped the lock we need to revalidate
2707                         * the PTE as someone else may have changed it.  If
2708                         * they did, we just return, as we can count on the
2709                         * MMU to tell us if they didn't also make it writable.
2710                         */
2711                        page_table = pte_offset_map_lock(mm, pmd, address,
2712                                                         &ptl);
2713                        if (!pte_same(*page_table, orig_pte)) {
2714                                unlock_page(old_page);
2715                                goto unlock;
2716                        }
2717
2718                        page_mkwrite = 1;
2719                }
2720                dirty_page = old_page;
2721                get_page(dirty_page);
2722
2723reuse:
2724                flush_cache_page(vma, address, pte_pfn(orig_pte));
2725                entry = pte_mkyoung(orig_pte);
2726                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2727                if (ptep_set_access_flags(vma, address, page_table, entry,1))
2728                        update_mmu_cache(vma, address, page_table);
2729                pte_unmap_unlock(page_table, ptl);
2730                ret |= VM_FAULT_WRITE;
2731
2732                if (!dirty_page)
2733                        return ret;
2734
2735                /*
2736                 * Yes, Virginia, this is actually required to prevent a race
2737                 * with clear_page_dirty_for_io() from clearing the page dirty
2738                 * bit after it clear all dirty ptes, but before a racing
2739                 * do_wp_page installs a dirty pte.
2740                 *
2741                 * __do_fault is protected similarly.
2742                 */
2743                if (!page_mkwrite) {
2744                        wait_on_page_locked(dirty_page);
2745                        set_page_dirty_balance(dirty_page, page_mkwrite);
2746                        /* file_update_time outside page_lock */
2747                        if (vma->vm_file)
2748                                file_update_time(vma->vm_file);
2749                }
2750                put_page(dirty_page);
2751                if (page_mkwrite) {
2752                        struct address_space *mapping = dirty_page->mapping;
2753
2754                        set_page_dirty(dirty_page);
2755                        unlock_page(dirty_page);
2756                        page_cache_release(dirty_page);
2757                        if (mapping)    {
2758                                /*
2759                                 * Some device drivers do not set page.mapping
2760                                 * but still dirty their pages
2761                                 */
2762                                balance_dirty_pages_ratelimited(mapping);
2763                        }
2764                }
2765
2766                return ret;
2767        }
2768
2769        /*
2770         * Ok, we need to copy. Oh, well..
2771         */
2772        page_cache_get(old_page);
2773gotten:
2774        pte_unmap_unlock(page_table, ptl);
2775
2776        if (unlikely(anon_vma_prepare(vma)))
2777                goto oom;
2778
2779        if (is_zero_pfn(pte_pfn(orig_pte))) {
2780                new_page = alloc_zeroed_user_highpage_movable(vma, address);
2781                if (!new_page)
2782                        goto oom;
2783        } else {
2784                new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2785                if (!new_page)
2786                        goto oom;
2787                cow_user_page(new_page, old_page, address, vma);
2788        }
2789        __SetPageUptodate(new_page);
2790
2791        if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2792                goto oom_free_new;
2793
2794        mmun_start  = address & PAGE_MASK;
2795        mmun_end    = mmun_start + PAGE_SIZE;
2796        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2797
2798        /*
2799         * Re-check the pte - we dropped the lock
2800         */
2801        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2802        if (likely(pte_same(*page_table, orig_pte))) {
2803                if (old_page) {
2804                        if (!PageAnon(old_page)) {
2805                                dec_mm_counter_fast(mm, MM_FILEPAGES);
2806                                inc_mm_counter_fast(mm, MM_ANONPAGES);
2807                        }
2808                } else
2809                        inc_mm_counter_fast(mm, MM_ANONPAGES);
2810                flush_cache_page(vma, address, pte_pfn(orig_pte));
2811                entry = mk_pte(new_page, vma->vm_page_prot);
2812                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2813                /*
2814                 * Clear the pte entry and flush it first, before updating the
2815                 * pte with the new entry. This will avoid a race condition
2816                 * seen in the presence of one thread doing SMC and another
2817                 * thread doing COW.
2818                 */
2819                ptep_clear_flush(vma, address, page_table);
2820                page_add_new_anon_rmap(new_page, vma, address);
2821                /*
2822                 * We call the notify macro here because, when using secondary
2823                 * mmu page tables (such as kvm shadow page tables), we want the
2824                 * new page to be mapped directly into the secondary page table.
2825                 */
2826                set_pte_at_notify(mm, address, page_table, entry);
2827                update_mmu_cache(vma, address, page_table);
2828                if (old_page) {
2829                        /*
2830                         * Only after switching the pte to the new page may
2831                         * we remove the mapcount here. Otherwise another
2832                         * process may come and find the rmap count decremented
2833                         * before the pte is switched to the new page, and
2834                         * "reuse" the old page writing into it while our pte
2835                         * here still points into it and can be read by other
2836                         * threads.
2837                         *
2838                         * The critical issue is to order this
2839                         * page_remove_rmap with the ptp_clear_flush above.
2840                         * Those stores are ordered by (if nothing else,)
2841                         * the barrier present in the atomic_add_negative
2842                         * in page_remove_rmap.
2843                         *
2844                         * Then the TLB flush in ptep_clear_flush ensures that
2845                         * no process can access the old page before the
2846                         * decremented mapcount is visible. And the old page
2847                         * cannot be reused until after the decremented
2848                         * mapcount is visible. So transitively, TLBs to
2849                         * old page will be flushed before it can be reused.
2850                         */
2851                        page_remove_rmap(old_page);
2852                }
2853
2854                /* Free the old page.. */
2855                new_page = old_page;
2856                ret |= VM_FAULT_WRITE;
2857        } else
2858                mem_cgroup_uncharge_page(new_page);
2859
2860        if (new_page)
2861                page_cache_release(new_page);
2862unlock:
2863        pte_unmap_unlock(page_table, ptl);
2864        if (mmun_end > mmun_start)
2865                mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2866        if (old_page) {
2867                /*
2868                 * Don't let another task, with possibly unlocked vma,
2869                 * keep the mlocked page.
2870                 */
2871                if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2872                        lock_page(old_page);    /* LRU manipulation */
2873                        munlock_vma_page(old_page);
2874                        unlock_page(old_page);
2875                }
2876                page_cache_release(old_page);
2877        }
2878        return ret;
2879oom_free_new:
2880        page_cache_release(new_page);
2881oom:
2882        if (old_page)
2883                page_cache_release(old_page);
2884        return VM_FAULT_OOM;
2885
2886unwritable_page:
2887        page_cache_release(old_page);
2888        return ret;
2889}
2890
2891static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2892                unsigned long start_addr, unsigned long end_addr,
2893                struct zap_details *details)
2894{
2895        zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2896}
2897
2898static inline void unmap_mapping_range_tree(struct rb_root *root,
2899                                            struct zap_details *details)
2900{
2901        struct vm_area_struct *vma;
2902        pgoff_t vba, vea, zba, zea;
2903
2904        vma_interval_tree_foreach(vma, root,
2905                        details->first_index, details->last_index) {
2906
2907                vba = vma->vm_pgoff;
2908                vea = vba + vma_pages(vma) - 1;
2909                /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2910                zba = details->first_index;
2911                if (zba < vba)
2912                        zba = vba;
2913                zea = details->last_index;
2914                if (zea > vea)
2915                        zea = vea;
2916
2917                unmap_mapping_range_vma(vma,
2918                        ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2919                        ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2920                                details);
2921        }
2922}
2923
2924static inline void unmap_mapping_range_list(struct list_head *head,
2925                                            struct zap_details *details)
2926{
2927        struct vm_area_struct *vma;
2928
2929        /*
2930         * In nonlinear VMAs there is no correspondence between virtual address
2931         * offset and file offset.  So we must perform an exhaustive search
2932         * across *all* the pages in each nonlinear VMA, not just the pages
2933         * whose virtual address lies outside the file truncation point.
2934         */
2935        list_for_each_entry(vma, head, shared.nonlinear) {
2936                details->nonlinear_vma = vma;
2937                unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2938        }
2939}
2940
2941/**
2942 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2943 * @mapping: the address space containing mmaps to be unmapped.
2944 * @holebegin: byte in first page to unmap, relative to the start of
2945 * the underlying file.  This will be rounded down to a PAGE_SIZE
2946 * boundary.  Note that this is different from truncate_pagecache(), which
2947 * must keep the partial page.  In contrast, we must get rid of
2948 * partial pages.
2949 * @holelen: size of prospective hole in bytes.  This will be rounded
2950 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2951 * end of the file.
2952 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2953 * but 0 when invalidating pagecache, don't throw away private data.
2954 */
2955void unmap_mapping_range(struct address_space *mapping,
2956                loff_t const holebegin, loff_t const holelen, int even_cows)
2957{
2958        struct zap_details details;
2959        pgoff_t hba = holebegin >> PAGE_SHIFT;
2960        pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2961
2962        /* Check for overflow. */
2963        if (sizeof(holelen) > sizeof(hlen)) {
2964                long long holeend =
2965                        (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2966                if (holeend & ~(long long)ULONG_MAX)
2967                        hlen = ULONG_MAX - hba + 1;
2968        }
2969
2970        details.check_mapping = even_cows? NULL: mapping;
2971        details.nonlinear_vma = NULL;
2972        details.first_index = hba;
2973        details.last_index = hba + hlen - 1;
2974        if (details.last_index < details.first_index)
2975                details.last_index = ULONG_MAX;
2976
2977
2978        mutex_lock(&mapping->i_mmap_mutex);
2979        if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2980                unmap_mapping_range_tree(&mapping->i_mmap, &details);
2981        if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2982                unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2983        mutex_unlock(&mapping->i_mmap_mutex);
2984}
2985EXPORT_SYMBOL(unmap_mapping_range);
2986
2987/*
2988 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2989 * but allow concurrent faults), and pte mapped but not yet locked.
2990 * We return with mmap_sem still held, but pte unmapped and unlocked.
2991 */
2992static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2993                unsigned long address, pte_t *page_table, pmd_t *pmd,
2994                unsigned int flags, pte_t orig_pte)
2995{
2996        spinlock_t *ptl;
2997        struct page *page, *swapcache;
2998        swp_entry_t entry;
2999        pte_t pte;
3000        int locked;
3001        struct mem_cgroup *ptr;
3002        int exclusive = 0;
3003        int ret = 0;
3004
3005        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3006                goto out;
3007
3008        entry = pte_to_swp_entry(orig_pte);
3009        if (unlikely(non_swap_entry(entry))) {
3010                if (is_migration_entry(entry)) {
3011                        migration_entry_wait(mm, pmd, address);
3012                } else if (is_hwpoison_entry(entry)) {
3013                        ret = VM_FAULT_HWPOISON;
3014                } else {
3015                        print_bad_pte(vma, address, orig_pte, NULL);
3016                        ret = VM_FAULT_SIGBUS;
3017                }
3018                goto out;
3019        }
3020        delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3021        page = lookup_swap_cache(entry);
3022        if (!page) {
3023                page = swapin_readahead(entry,
3024                                        GFP_HIGHUSER_MOVABLE, vma, address);
3025                if (!page) {
3026                        /*
3027                         * Back out if somebody else faulted in this pte
3028                         * while we released the pte lock.
3029                         */
3030                        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3031                        if (likely(pte_same(*page_table, orig_pte)))
3032                                ret = VM_FAULT_OOM;
3033                        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3034                        goto unlock;
3035                }
3036
3037                /* Had to read the page from swap area: Major fault */
3038                ret = VM_FAULT_MAJOR;
3039                count_vm_event(PGMAJFAULT);
3040                mem_cgroup_count_vm_event(mm, PGMAJFAULT);
3041        } else if (PageHWPoison(page)) {
3042                /*
3043                 * hwpoisoned dirty swapcache pages are kept for killing
3044                 * owner processes (which may be unknown at hwpoison time)
3045                 */
3046                ret = VM_FAULT_HWPOISON;
3047                delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3048                swapcache = page;
3049                goto out_release;
3050        }
3051
3052        swapcache = page;
3053        locked = lock_page_or_retry(page, mm, flags);
3054
3055        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3056        if (!locked) {
3057                ret |= VM_FAULT_RETRY;
3058                goto out_release;
3059        }
3060
3061        /*
3062         * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3063         * release the swapcache from under us.  The page pin, and pte_same
3064         * test below, are not enough to exclude that.  Even if it is still
3065         * swapcache, we need to check that the page's swap has not changed.
3066         */
3067        if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
3068                goto out_page;
3069
3070        page = ksm_might_need_to_copy(page, vma, address);
3071        if (unlikely(!page)) {
3072                ret = VM_FAULT_OOM;
3073                page = swapcache;
3074                goto out_page;
3075        }
3076
3077        if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3078                ret = VM_FAULT_OOM;
3079                goto out_page;
3080        }
3081
3082        /*
3083         * Back out if somebody else already faulted in this pte.
3084         */
3085        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3086        if (unlikely(!pte_same(*page_table, orig_pte)))
3087                goto out_nomap;
3088
3089        if (unlikely(!PageUptodate(page))) {
3090                ret = VM_FAULT_SIGBUS;
3091                goto out_nomap;
3092        }
3093
3094        /*
3095         * The page isn't present yet, go ahead with the fault.
3096         *
3097         * Be careful about the sequence of operations here.
3098         * To get its accounting right, reuse_swap_page() must be called
3099         * while the page is counted on swap but not yet in mapcount i.e.
3100         * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3101         * must be called after the swap_free(), or it will never succeed.
3102         * Because delete_from_swap_page() may be called by reuse_swap_page(),
3103         * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3104         * in page->private. In this case, a record in swap_cgroup  is silently
3105         * discarded at swap_free().
3106         */
3107
3108        inc_mm_counter_fast(mm, MM_ANONPAGES);
3109        dec_mm_counter_fast(mm, MM_SWAPENTS);
3110        pte = mk_pte(page, vma->vm_page_prot);
3111        if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3112                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3113                flags &= ~FAULT_FLAG_WRITE;
3114                ret |= VM_FAULT_WRITE;
3115                exclusive = 1;
3116        }
3117        flush_icache_page(vma, page);
3118        if (pte_swp_soft_dirty(orig_pte))
3119                pte = pte_mksoft_dirty(pte);
3120        set_pte_at(mm, address, page_table, pte);
3121        if (page == swapcache)
3122                do_page_add_anon_rmap(page, vma, address, exclusive);
3123        else /* ksm created a completely new copy */
3124                page_add_new_anon_rmap(page, vma, address);
3125        /* It's better to call commit-charge after rmap is established */
3126        mem_cgroup_commit_charge_swapin(page, ptr);
3127
3128        swap_free(entry);
3129        if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3130                try_to_free_swap(page);
3131        unlock_page(page);
3132        if (page != swapcache) {
3133                /*
3134                 * Hold the lock to avoid the swap entry to be reused
3135                 * until we take the PT lock for the pte_same() check
3136                 * (to avoid false positives from pte_same). For
3137                 * further safety release the lock after the swap_free
3138                 * so that the swap count won't change under a
3139                 * parallel locked swapcache.
3140                 */
3141                unlock_page(swapcache);
3142                page_cache_release(swapcache);
3143        }
3144
3145        if (flags & FAULT_FLAG_WRITE) {
3146                ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3147                if (ret & VM_FAULT_ERROR)
3148                        ret &= VM_FAULT_ERROR;
3149                goto out;
3150        }
3151
3152        /* No need to invalidate - it was non-present before */
3153        update_mmu_cache(vma, address, page_table);
3154unlock:
3155        pte_unmap_unlock(page_table, ptl);
3156out:
3157        return ret;
3158out_nomap:
3159        mem_cgroup_cancel_charge_swapin(ptr);
3160        pte_unmap_unlock(page_table, ptl);
3161out_page:
3162        unlock_page(page);
3163out_release:
3164        page_cache_release(page);
3165        if (page != swapcache) {
3166                unlock_page(swapcache);
3167                page_cache_release(swapcache);
3168        }
3169        return ret;
3170}
3171
3172/*
3173 * This is like a special single-page "expand_{down|up}wards()",
3174 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3175 * doesn't hit another vma.
3176 */
3177static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3178{
3179        address &= PAGE_MASK;
3180        if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3181                struct vm_area_struct *prev = vma->vm_prev;
3182
3183                /*
3184                 * Is there a mapping abutting this one below?
3185                 *
3186                 * That's only ok if it's the same stack mapping
3187                 * that has gotten split..
3188                 */
3189                if (prev && prev->vm_end == address)
3190                        return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3191
3192                expand_downwards(vma, address - PAGE_SIZE);
3193        }
3194        if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3195                struct vm_area_struct *next = vma->vm_next;
3196
3197                /* As VM_GROWSDOWN but s/below/above/ */
3198                if (next && next->vm_start == address + PAGE_SIZE)
3199                        return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3200
3201                expand_upwards(vma, address + PAGE_SIZE);
3202        }
3203        return 0;
3204}
3205
3206/*
3207 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3208 * but allow concurrent faults), and pte mapped but not yet locked.
3209 * We return with mmap_sem still held, but pte unmapped and unlocked.
3210 */
3211static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3212                unsigned long address, pte_t *page_table, pmd_t *pmd,
3213                unsigned int flags)
3214{
3215        struct page *page;
3216        spinlock_t *ptl;
3217        pte_t entry;
3218
3219        pte_unmap(page_table);
3220
3221        /* Check if we need to add a guard page to the stack */
3222        if (check_stack_guard_page(vma, address) < 0)
3223                return VM_FAULT_SIGBUS;
3224
3225        /* Use the zero-page for reads */
3226        if (!(flags & FAULT_FLAG_WRITE)) {
3227                entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3228                                                vma->vm_page_prot));
3229                page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3230                if (!pte_none(*page_table))
3231                        goto unlock;
3232                goto setpte;
3233        }
3234
3235        /* Allocate our own private page. */
3236        if (unlikely(anon_vma_prepare(vma)))
3237                goto oom;
3238        page = alloc_zeroed_user_highpage_movable(vma, address);
3239        if (!page)
3240                goto oom;
3241        /*
3242         * The memory barrier inside __SetPageUptodate makes sure that
3243         * preceeding stores to the page contents become visible before
3244         * the set_pte_at() write.
3245         */
3246        __SetPageUptodate(page);
3247
3248        if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3249                goto oom_free_page;
3250
3251        entry = mk_pte(page, vma->vm_page_prot);
3252        if (vma->vm_flags & VM_WRITE)
3253                entry = pte_mkwrite(pte_mkdirty(entry));
3254
3255        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3256        if (!pte_none(*page_table))
3257                goto release;
3258
3259        inc_mm_counter_fast(mm, MM_ANONPAGES);
3260        page_add_new_anon_rmap(page, vma, address);
3261setpte:
3262        set_pte_at(mm, address, page_table, entry);
3263
3264        /* No need to invalidate - it was non-present before */
3265        update_mmu_cache(vma, address, page_table);
3266unlock:
3267        pte_unmap_unlock(page_table, ptl);
3268        return 0;
3269release:
3270        mem_cgroup_uncharge_page(page);
3271        page_cache_release(page);
3272        goto unlock;
3273oom_free_page:
3274        page_cache_release(page);
3275oom:
3276        return VM_FAULT_OOM;
3277}
3278
3279/*
3280 * __do_fault() tries to create a new page mapping. It aggressively
3281 * tries to share with existing pages, but makes a separate copy if
3282 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3283 * the next page fault.
3284 *
3285 * As this is called only for pages that do not currently exist, we
3286 * do not need to flush old virtual caches or the TLB.
3287 *
3288 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3289 * but allow concurrent faults), and pte neither mapped nor locked.
3290 * We return with mmap_sem still held, but pte unmapped and unlocked.
3291 */
3292static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3293                unsigned long address, pmd_t *pmd,
3294                pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3295{
3296        pte_t *page_table;
3297        spinlock_t *ptl;
3298        struct page *page;
3299        struct page *cow_page;
3300        pte_t entry;
3301        int anon = 0;
3302        struct page *dirty_page = NULL;
3303        struct vm_fault vmf;
3304        int ret;
3305        int page_mkwrite = 0;
3306
3307        /*
3308         * If we do COW later, allocate page befor taking lock_page()
3309         * on the file cache page. This will reduce lock holding time.
3310         */
3311        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3312
3313                if (unlikely(anon_vma_prepare(vma)))
3314                        return VM_FAULT_OOM;
3315
3316                cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3317                if (!cow_page)
3318                        return VM_FAULT_OOM;
3319
3320                if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3321                        page_cache_release(cow_page);
3322                        return VM_FAULT_OOM;
3323                }
3324        } else
3325                cow_page = NULL;
3326
3327        vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3328        vmf.pgoff = pgoff;
3329        vmf.flags = flags;
3330        vmf.page = NULL;
3331
3332        ret = vma->vm_ops->fault(vma, &vmf);
3333        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3334                            VM_FAULT_RETRY)))
3335                goto uncharge_out;
3336
3337        if (unlikely(PageHWPoison(vmf.page))) {
3338                if (ret & VM_FAULT_LOCKED)
3339                        unlock_page(vmf.page);
3340                ret = VM_FAULT_HWPOISON;
3341                goto uncharge_out;
3342        }
3343
3344        /*
3345         * For consistency in subsequent calls, make the faulted page always
3346         * locked.
3347         */
3348        if (unlikely(!(ret & VM_FAULT_LOCKED)))
3349                lock_page(vmf.page);
3350        else
3351                VM_BUG_ON(!PageLocked(vmf.page));
3352
3353        /*
3354         * Should we do an early C-O-W break?
3355         */
3356        page = vmf.page;
3357        if (flags & FAULT_FLAG_WRITE) {
3358                if (!(vma->vm_flags & VM_SHARED)) {
3359                        page = cow_page;
3360                        anon = 1;
3361                        copy_user_highpage(page, vmf.page, address, vma);
3362                        __SetPageUptodate(page);
3363                } else {
3364                        /*
3365                         * If the page will be shareable, see if the backing
3366                         * address space wants to know that the page is about
3367                         * to become writable
3368                         */
3369                        if (vma->vm_ops->page_mkwrite) {
3370                                int tmp;
3371
3372                                unlock_page(page);
3373                                vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3374                                tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3375                                if (unlikely(tmp &
3376                                          (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3377                                        ret = tmp;
3378                                        goto unwritable_page;
3379                                }
3380                                if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3381                                        lock_page(page);
3382                                        if (!page->mapping) {
3383                                                ret = 0; /* retry the fault */
3384                                                unlock_page(page);
3385                                                goto unwritable_page;
3386                                        }
3387                                } else
3388                                        VM_BUG_ON(!PageLocked(page));
3389                                page_mkwrite = 1;
3390                        }
3391                }
3392
3393        }
3394
3395        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3396
3397        /*
3398         * This silly early PAGE_DIRTY setting removes a race
3399         * due to the bad i386 page protection. But it's valid
3400         * for other architectures too.
3401         *
3402         * Note that if FAULT_FLAG_WRITE is set, we either now have
3403         * an exclusive copy of the page, or this is a shared mapping,
3404         * so we can make it writable and dirty to avoid having to
3405         * handle that later.
3406         */
3407        /* Only go through if we didn't race with anybody else... */
3408        if (likely(pte_same(*page_table, orig_pte))) {
3409                flush_icache_page(vma, page);
3410                entry = mk_pte(page, vma->vm_page_prot);
3411                if (flags & FAULT_FLAG_WRITE)
3412                        entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3413                else if (pte_file(orig_pte) && pte_file_soft_dirty(orig_pte))
3414                        pte_mksoft_dirty(entry);
3415                if (anon) {
3416                        inc_mm_counter_fast(mm, MM_ANONPAGES);
3417                        page_add_new_anon_rmap(page, vma, address);
3418                } else {
3419                        inc_mm_counter_fast(mm, MM_FILEPAGES);
3420                        page_add_file_rmap(page);
3421                        if (flags & FAULT_FLAG_WRITE) {
3422                                dirty_page = page;
3423                                get_page(dirty_page);
3424                        }
3425                }
3426                set_pte_at(mm, address, page_table, entry);
3427
3428                /* no need to invalidate: a not-present page won't be cached */
3429                update_mmu_cache(vma, address, page_table);
3430        } else {
3431                if (cow_page)
3432                        mem_cgroup_uncharge_page(cow_page);
3433                if (anon)
3434                        page_cache_release(page);
3435                else
3436                        anon = 1; /* no anon but release faulted_page */
3437        }
3438
3439        pte_unmap_unlock(page_table, ptl);
3440
3441        if (dirty_page) {
3442                struct address_space *mapping = page->mapping;
3443                int dirtied = 0;
3444
3445                if (set_page_dirty(dirty_page))
3446                        dirtied = 1;
3447                unlock_page(dirty_page);
3448                put_page(dirty_page);
3449                if ((dirtied || page_mkwrite) && mapping) {
3450                        /*
3451                         * Some device drivers do not set page.mapping but still
3452                         * dirty their pages
3453                         */
3454                        balance_dirty_pages_ratelimited(mapping);
3455                }
3456
3457                /* file_update_time outside page_lock */
3458                if (vma->vm_file && !page_mkwrite)
3459                        file_update_time(vma->vm_file);
3460        } else {
3461                unlock_page(vmf.page);
3462                if (anon)
3463                        page_cache_release(vmf.page);
3464        }
3465
3466        return ret;
3467
3468unwritable_page:
3469        page_cache_release(page);
3470        return ret;
3471uncharge_out:
3472        /* fs's fault handler get error */
3473        if (cow_page) {
3474                mem_cgroup_uncharge_page(cow_page);
3475                page_cache_release(cow_page);
3476        }
3477        return ret;
3478}
3479
3480static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3481                unsigned long address, pte_t *page_table, pmd_t *pmd,
3482                unsigned int flags, pte_t orig_pte)
3483{
3484        pgoff_t pgoff = (((address & PAGE_MASK)
3485                        - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3486
3487        pte_unmap(page_table);
3488        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3489}
3490
3491/*
3492 * Fault of a previously existing named mapping. Repopulate the pte
3493 * from the encoded file_pte if possible. This enables swappable
3494 * nonlinear vmas.
3495 *
3496 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3497 * but allow concurrent faults), and pte mapped but not yet locked.
3498 * We return with mmap_sem still held, but pte unmapped and unlocked.
3499 */
3500static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3501                unsigned long address, pte_t *page_table, pmd_t *pmd,
3502                unsigned int flags, pte_t orig_pte)
3503{
3504        pgoff_t pgoff;
3505
3506        flags |= FAULT_FLAG_NONLINEAR;
3507
3508        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3509                return 0;
3510
3511        if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3512                /*
3513                 * Page table corrupted: show pte and kill process.
3514                 */
3515                print_bad_pte(vma, address, orig_pte, NULL);
3516                return VM_FAULT_SIGBUS;
3517        }
3518
3519        pgoff = pte_to_pgoff(orig_pte);
3520        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3521}
3522
3523int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3524                                unsigned long addr, int page_nid)
3525{
3526        get_page(page);
3527
3528        count_vm_numa_event(NUMA_HINT_FAULTS);
3529        if (page_nid == numa_node_id())
3530                count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3531
3532        return mpol_misplaced(page, vma, addr);
3533}
3534
3535int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3536                   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3537{
3538        struct page *page = NULL;
3539        spinlock_t *ptl;
3540        int page_nid = -1;
3541        int target_nid;
3542        bool migrated = false;
3543
3544        /*
3545        * The "pte" at this point cannot be used safely without
3546        * validation through pte_unmap_same(). It's of NUMA type but
3547        * the pfn may be screwed if the read is non atomic.
3548        *
3549        * ptep_modify_prot_start is not called as this is clearing
3550        * the _PAGE_NUMA bit and it is not really expected that there
3551        * would be concurrent hardware modifications to the PTE.
3552        */
3553        ptl = pte_lockptr(mm, pmd);
3554        spin_lock(ptl);
3555        if (unlikely(!pte_same(*ptep, pte))) {
3556                pte_unmap_unlock(ptep, ptl);
3557                goto out;
3558        }
3559
3560        pte = pte_mknonnuma(pte);
3561        set_pte_at(mm, addr, ptep, pte);
3562        update_mmu_cache(vma, addr, ptep);
3563
3564        page = vm_normal_page(vma, addr, pte);
3565        if (!page) {
3566                pte_unmap_unlock(ptep, ptl);
3567                return 0;
3568        }
3569
3570        page_nid = page_to_nid(page);
3571        target_nid = numa_migrate_prep(page, vma, addr, page_nid);
3572        pte_unmap_unlock(ptep, ptl);
3573        if (target_nid == -1) {
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                page_nid = target_nid;
3582
3583out:
3584        if (page_nid != -1)
3585                task_numa_fault(page_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
3601        spin_lock(&mm->page_table_lock);
3602        pmd = *pmdp;
3603        if (pmd_numa(pmd)) {
3604                set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd));
3605                numa = true;
3606        }
3607        spin_unlock(&mm->page_table_lock);
3608
3609        if (!numa)
3610                return 0;
3611
3612        /* we're in a page fault so some vma must be in the range */
3613        BUG_ON(!vma);
3614        BUG_ON(vma->vm_start >= _addr + PMD_SIZE);
3615        offset = max(_addr, vma->vm_start) & ~PMD_MASK;
3616        VM_BUG_ON(offset >= PMD_SIZE);
3617        orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl);
3618        pte += offset >> PAGE_SHIFT;
3619        for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
3620                pte_t pteval = *pte;
3621                struct page *page;
3622                int page_nid = -1;
3623                int target_nid;
3624                bool migrated = false;
3625
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                page_nid = page_to_nid(page);
3648                target_nid = numa_migrate_prep(page, vma, addr, page_nid);
3649                pte_unmap_unlock(pte, ptl);
3650                if (target_nid != -1) {
3651                        migrated = migrate_misplaced_page(page, target_nid);
3652                        if (migrated)
3653                                page_nid = target_nid;
3654                } else {
3655                        put_page(page);
3656                }
3657
3658                if (page_nid != -1)
3659                        task_numa_fault(page_nid, 1, migrated);
3660
3661                pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
3662        }
3663        pte_unmap_unlock(orig_pte, ptl);
3664
3665        return 0;
3666}
3667#else
3668static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3669                     unsigned long addr, pmd_t *pmdp)
3670{
3671        BUG();
3672        return 0;
3673}
3674#endif /* CONFIG_NUMA_BALANCING */
3675
3676/*
3677 * These routines also need to handle stuff like marking pages dirty
3678 * and/or accessed for architectures that don't do it in hardware (most
3679 * RISC architectures).  The early dirtying is also good on the i386.
3680 *
3681 * There is also a hook called "update_mmu_cache()" that architectures
3682 * with external mmu caches can use to update those (ie the Sparc or
3683 * PowerPC hashed page tables that act as extended TLBs).
3684 *
3685 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3686 * but allow concurrent faults), and pte mapped but not yet locked.
3687 * We return with mmap_sem still held, but pte unmapped and unlocked.
3688 */
3689static int handle_pte_fault(struct mm_struct *mm,
3690                     struct vm_area_struct *vma, unsigned long address,
3691                     pte_t *pte, pmd_t *pmd, unsigned int flags)
3692{
3693        pte_t entry;
3694        spinlock_t *ptl;
3695
3696        entry = *pte;
3697        if (!pte_present(entry)) {
3698                if (pte_none(entry)) {
3699                        if (vma->vm_ops) {
3700                                if (likely(vma->vm_ops->fault))
3701                                        return do_linear_fault(mm, vma, address,
3702                                                pte, pmd, flags, entry);
3703                        }
3704                        return do_anonymous_page(mm, vma, address,
3705                                                 pte, pmd, flags);
3706                }
3707                if (pte_file(entry))
3708                        return do_nonlinear_fault(mm, vma, address,
3709                                        pte, pmd, flags, entry);
3710                return do_swap_page(mm, vma, address,
3711                                        pte, pmd, flags, entry);
3712        }
3713
3714        if (pte_numa(entry))
3715                return do_numa_page(mm, vma, address, entry, pte, pmd);
3716
3717        ptl = pte_lockptr(mm, pmd);
3718        spin_lock(ptl);
3719        if (unlikely(!pte_same(*pte, entry)))
3720                goto unlock;
3721        if (flags & FAULT_FLAG_WRITE) {
3722                if (!pte_write(entry))
3723                        return do_wp_page(mm, vma, address,
3724                                        pte, pmd, ptl, entry);
3725                entry = pte_mkdirty(entry);
3726        }
3727        entry = pte_mkyoung(entry);
3728        if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3729                update_mmu_cache(vma, address, pte);
3730        } else {
3731                /*
3732                 * This is needed only for protection faults but the arch code
3733                 * is not yet telling us if this is a protection fault or not.
3734                 * This still avoids useless tlb flushes for .text page faults
3735                 * with threads.
3736                 */
3737                if (flags & FAULT_FLAG_WRITE)
3738                        flush_tlb_fix_spurious_fault(vma, address);
3739        }
3740unlock:
3741        pte_unmap_unlock(pte, ptl);
3742        return 0;
3743}
3744
3745/*
3746 * By the time we get here, we already hold the mm semaphore
3747 */
3748static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3749                             unsigned long address, unsigned int flags)
3750{
3751        pgd_t *pgd;
3752        pud_t *pud;
3753        pmd_t *pmd;
3754        pte_t *pte;
3755
3756        if (unlikely(is_vm_hugetlb_page(vma)))
3757                return hugetlb_fault(mm, vma, address, flags);
3758
3759retry:
3760        pgd = pgd_offset(mm, address);
3761        pud = pud_alloc(mm, pgd, address);
3762        if (!pud)
3763                return VM_FAULT_OOM;
3764        pmd = pmd_alloc(mm, pud, address);
3765        if (!pmd)
3766                return VM_FAULT_OOM;
3767        if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3768                int ret = VM_FAULT_FALLBACK;
3769                if (!vma->vm_ops)
3770                        ret = do_huge_pmd_anonymous_page(mm, vma, address,
3771                                        pmd, flags);
3772                if (!(ret & VM_FAULT_FALLBACK))
3773                        return ret;
3774        } else {
3775                pmd_t orig_pmd = *pmd;
3776                int ret;
3777
3778                barrier();
3779                if (pmd_trans_huge(orig_pmd)) {
3780                        unsigned int dirty = flags & FAULT_FLAG_WRITE;
3781
3782                        /*
3783                         * If the pmd is splitting, return and retry the
3784                         * the fault.  Alternative: wait until the split
3785                         * is done, and goto retry.
3786                         */
3787                        if (pmd_trans_splitting(orig_pmd))
3788                                return 0;
3789
3790                        if (pmd_numa(orig_pmd))
3791                                return do_huge_pmd_numa_page(mm, vma, address,
3792                                                             orig_pmd, pmd);
3793
3794                        if (dirty && !pmd_write(orig_pmd)) {
3795                                ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3796                                                          orig_pmd);
3797                                /*
3798                                 * If COW results in an oom, the huge pmd will
3799                                 * have been split, so retry the fault on the
3800                                 * pte for a smaller charge.
3801                                 */
3802                                if (unlikely(ret & VM_FAULT_OOM))
3803                                        goto retry;
3804                                return ret;
3805                        } else {
3806                                huge_pmd_set_accessed(mm, vma, address, pmd,
3807                                                      orig_pmd, dirty);
3808                        }
3809
3810                        return 0;
3811                }
3812        }
3813
3814        if (pmd_numa(*pmd))
3815                return do_pmd_numa_page(mm, vma, address, pmd);
3816
3817        /*
3818         * Use __pte_alloc instead of pte_alloc_map, because we can't
3819         * run pte_offset_map on the pmd, if an huge pmd could
3820         * materialize from under us from a different thread.
3821         */
3822        if (unlikely(pmd_none(*pmd)) &&
3823            unlikely(__pte_alloc(mm, vma, pmd, address)))
3824                return VM_FAULT_OOM;
3825        /* if an huge pmd materialized from under us just retry later */
3826        if (unlikely(pmd_trans_huge(*pmd)))
3827                return 0;
3828        /*
3829         * A regular pmd is established and it can't morph into a huge pmd
3830         * from under us anymore at this point because we hold the mmap_sem
3831         * read mode and khugepaged takes it in write mode. So now it's
3832         * safe to run pte_offset_map().
3833         */
3834        pte = pte_offset_map(pmd, address);
3835
3836        return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3837}
3838
3839int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3840                    unsigned long address, unsigned int flags)
3841{
3842        int ret;
3843
3844        __set_current_state(TASK_RUNNING);
3845
3846        count_vm_event(PGFAULT);
3847        mem_cgroup_count_vm_event(mm, PGFAULT);
3848
3849        /* do counter updates before entering really critical section. */
3850        check_sync_rss_stat(current);
3851
3852        /*
3853         * Enable the memcg OOM handling for faults triggered in user
3854         * space.  Kernel faults are handled more gracefully.
3855         */
3856        if (flags & FAULT_FLAG_USER)
3857                mem_cgroup_oom_enable();
3858
3859        ret = __handle_mm_fault(mm, vma, address, flags);
3860
3861        if (flags & FAULT_FLAG_USER) {
3862                mem_cgroup_oom_disable();
3863                /*
3864                 * The task may have entered a memcg OOM situation but
3865                 * if the allocation error was handled gracefully (no
3866                 * VM_FAULT_OOM), there is no need to kill anything.
3867                 * Just clean up the OOM state peacefully.
3868                 */
3869                if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3870                        mem_cgroup_oom_synchronize(false);
3871        }
3872
3873        return ret;
3874}
3875
3876#ifndef __PAGETABLE_PUD_FOLDED
3877/*
3878 * Allocate page upper directory.
3879 * We've already handled the fast-path in-line.
3880 */
3881int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3882{
3883        pud_t *new = pud_alloc_one(mm, address);
3884        if (!new)
3885                return -ENOMEM;
3886
3887        smp_wmb(); /* See comment in __pte_alloc */
3888
3889        spin_lock(&mm->page_table_lock);
3890        if (pgd_present(*pgd))          /* Another has populated it */
3891                pud_free(mm, new);
3892        else
3893                pgd_populate(mm, pgd, new);
3894        spin_unlock(&mm->page_table_lock);
3895        return 0;
3896}
3897#endif /* __PAGETABLE_PUD_FOLDED */
3898
3899#ifndef __PAGETABLE_PMD_FOLDED
3900/*
3901 * Allocate page middle directory.
3902 * We've already handled the fast-path in-line.
3903 */
3904int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3905{
3906        pmd_t *new = pmd_alloc_one(mm, address);
3907        if (!new)
3908                return -ENOMEM;
3909
3910        smp_wmb(); /* See comment in __pte_alloc */
3911
3912        spin_lock(&mm->page_table_lock);
3913#ifndef __ARCH_HAS_4LEVEL_HACK
3914        if (pud_present(*pud))          /* Another has populated it */
3915                pmd_free(mm, new);
3916        else
3917                pud_populate(mm, pud, new);
3918#else
3919        if (pgd_present(*pud))          /* Another has populated it */
3920                pmd_free(mm, new);
3921        else
3922                pgd_populate(mm, pud, new);
3923#endif /* __ARCH_HAS_4LEVEL_HACK */
3924        spin_unlock(&mm->page_table_lock);
3925        return 0;
3926}
3927#endif /* __PAGETABLE_PMD_FOLDED */
3928
3929#if !defined(__HAVE_ARCH_GATE_AREA)
3930
3931#if defined(AT_SYSINFO_EHDR)
3932static struct vm_area_struct gate_vma;
3933
3934static int __init gate_vma_init(void)
3935{
3936        gate_vma.vm_mm = NULL;
3937        gate_vma.vm_start = FIXADDR_USER_START;
3938        gate_vma.vm_end = FIXADDR_USER_END;
3939        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3940        gate_vma.vm_page_prot = __P101;
3941
3942        return 0;
3943}
3944__initcall(gate_vma_init);
3945#endif
3946
3947struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3948{
3949#ifdef AT_SYSINFO_EHDR
3950        return &gate_vma;
3951#else
3952        return NULL;
3953#endif
3954}
3955
3956int in_gate_area_no_mm(unsigned long addr)
3957{
3958#ifdef AT_SYSINFO_EHDR
3959        if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3960                return 1;
3961#endif
3962        return 0;
3963}
3964
3965#endif  /* __HAVE_ARCH_GATE_AREA */
3966
3967static int __follow_pte(struct mm_struct *mm, unsigned long address,
3968                pte_t **ptepp, spinlock_t **ptlp)
3969{
3970        pgd_t *pgd;
3971        pud_t *pud;
3972        pmd_t *pmd;
3973        pte_t *ptep;
3974
3975        pgd = pgd_offset(mm, address);
3976        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3977                goto out;
3978
3979        pud = pud_offset(pgd, address);
3980        if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3981                goto out;
3982
3983        pmd = pmd_offset(pud, address);
3984        VM_BUG_ON(pmd_trans_huge(*pmd));
3985        if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3986                goto out;
3987
3988        /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3989        if (pmd_huge(*pmd))
3990                goto out;
3991
3992        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3993        if (!ptep)
3994                goto out;
3995        if (!pte_present(*ptep))
3996                goto unlock;
3997        *ptepp = ptep;
3998        return 0;
3999unlock:
4000        pte_unmap_unlock(ptep, *ptlp);
4001out:
4002        return -EINVAL;
4003}
4004
4005static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4006                             pte_t **ptepp, spinlock_t **ptlp)
4007{
4008        int res;
4009
4010        /* (void) is needed to make gcc happy */
4011        (void) __cond_lock(*ptlp,
4012                           !(res = __follow_pte(mm, address, ptepp, ptlp)));
4013        return res;
4014}
4015
4016/**
4017 * follow_pfn - look up PFN at a user virtual address
4018 * @vma: memory mapping
4019 * @address: user virtual address
4020 * @pfn: location to store found PFN
4021 *
4022 * Only IO mappings and raw PFN mappings are allowed.
4023 *
4024 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4025 */
4026int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4027        unsigned long *pfn)
4028{
4029        int ret = -EINVAL;
4030        spinlock_t *ptl;
4031        pte_t *ptep;
4032
4033        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4034                return ret;
4035
4036        ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4037        if (ret)
4038                return ret;
4039        *pfn = pte_pfn(*ptep);
4040        pte_unmap_unlock(ptep, ptl);
4041        return 0;
4042}
4043EXPORT_SYMBOL(follow_pfn);
4044
4045#ifdef CONFIG_HAVE_IOREMAP_PROT
4046int follow_phys(struct vm_area_struct *vma,
4047                unsigned long address, unsigned int flags,
4048                unsigned long *prot, resource_size_t *phys)
4049{
4050        int ret = -EINVAL;
4051        pte_t *ptep, pte;
4052        spinlock_t *ptl;
4053
4054        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4055                goto out;
4056
4057        if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4058                goto out;
4059        pte = *ptep;
4060
4061        if ((flags & FOLL_WRITE) && !pte_write(pte))
4062                goto unlock;
4063
4064        *prot = pgprot_val(pte_pgprot(pte));
4065        *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4066
4067        ret = 0;
4068unlock:
4069        pte_unmap_unlock(ptep, ptl);
4070out:
4071        return ret;
4072}
4073
4074int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4075                        void *buf, int len, int write)
4076{
4077        resource_size_t phys_addr;
4078        unsigned long prot = 0;
4079        void __iomem *maddr;
4080        int offset = addr & (PAGE_SIZE-1);
4081
4082        if (follow_phys(vma, addr, write, &prot, &phys_addr))
4083                return -EINVAL;
4084
4085        maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
4086        if (write)
4087                memcpy_toio(maddr + offset, buf, len);
4088        else
4089                memcpy_fromio(buf, maddr + offset, len);
4090        iounmap(maddr);
4091
4092        return len;
4093}
4094EXPORT_SYMBOL_GPL(generic_access_phys);
4095#endif
4096
4097/*
4098 * Access another process' address space as given in mm.  If non-NULL, use the
4099 * given task for page fault accounting.
4100 */
4101static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4102                unsigned long addr, void *buf, int len, int write)
4103{
4104        struct vm_area_struct *vma;
4105        void *old_buf = buf;
4106
4107        down_read(&mm->mmap_sem);
4108        /* ignore errors, just check how much was successfully transferred */
4109        while (len) {
4110                int bytes, ret, offset;
4111                void *maddr;
4112                struct page *page = NULL;
4113
4114                ret = get_user_pages(tsk, mm, addr, 1,
4115                                write, 1, &page, &vma);
4116                if (ret <= 0) {
4117                        /*
4118                         * Check if this is a VM_IO | VM_PFNMAP VMA, which
4119                         * we can access using slightly different code.
4120                         */
4121#ifdef CONFIG_HAVE_IOREMAP_PROT
4122                        vma = find_vma(mm, addr);
4123                        if (!vma || vma->vm_start > addr)
4124                                break;
4125                        if (vma->vm_ops && vma->vm_ops->access)
4126                                ret = vma->vm_ops->access(vma, addr, buf,
4127                                                          len, write);
4128                        if (ret <= 0)
4129#endif
4130                                break;
4131                        bytes = ret;
4132                } else {
4133                        bytes = len;
4134                        offset = addr & (PAGE_SIZE-1);
4135                        if (bytes > PAGE_SIZE-offset)
4136                                bytes = PAGE_SIZE-offset;
4137
4138                        maddr = kmap(page);
4139                        if (write) {
4140                                copy_to_user_page(vma, page, addr,
4141                                                  maddr + offset, buf, bytes);
4142                                set_page_dirty_lock(page);
4143                        } else {
4144                                copy_from_user_page(vma, page, addr,
4145                                                    buf, maddr + offset, bytes);
4146                        }
4147                        kunmap(page);
4148                        page_cache_release(page);
4149                }
4150                len -= bytes;
4151                buf += bytes;
4152                addr += bytes;
4153        }
4154        up_read(&mm->mmap_sem);
4155
4156        return buf - old_buf;
4157}
4158
4159/**
4160 * access_remote_vm - access another process' address space
4161 * @mm:         the mm_struct of the target address space
4162 * @addr:       start address to access
4163 * @buf:        source or destination buffer
4164 * @len:        number of bytes to transfer
4165 * @write:      whether the access is a write
4166 *
4167 * The caller must hold a reference on @mm.
4168 */
4169int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4170                void *buf, int len, int write)
4171{
4172        return __access_remote_vm(NULL, mm, addr, buf, len, write);
4173}
4174
4175/*
4176 * Access another process' address space.
4177 * Source/target buffer must be kernel space,
4178 * Do not walk the page table directly, use get_user_pages
4179 */
4180int access_process_vm(struct task_struct *tsk, unsigned long addr,
4181                void *buf, int len, int write)
4182{
4183        struct mm_struct *mm;
4184        int ret;
4185
4186        mm = get_task_mm(tsk);
4187        if (!mm)
4188                return 0;
4189
4190        ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
4191        mmput(mm);
4192
4193        return ret;
4194}
4195
4196/*
4197 * Print the name of a VMA.
4198 */
4199void print_vma_addr(char *prefix, unsigned long ip)
4200{
4201        struct mm_struct *mm = current->mm;
4202        struct vm_area_struct *vma;
4203
4204        /*
4205         * Do not print if we are in atomic
4206         * contexts (in exception stacks, etc.):
4207         */
4208        if (preempt_count())
4209                return;
4210
4211        down_read(&mm->mmap_sem);
4212        vma = find_vma(mm, ip);
4213        if (vma && vma->vm_file) {
4214                struct file *f = vma->vm_file;
4215                char *buf = (char *)__get_free_page(GFP_KERNEL);
4216                if (buf) {
4217                        char *p;
4218
4219                        p = d_path(&f->f_path, buf, PAGE_SIZE);
4220                        if (IS_ERR(p))
4221                                p = "?";
4222                        printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4223                                        vma->vm_start,
4224                                        vma->vm_end - vma->vm_start);
4225                        free_page((unsigned long)buf);
4226                }
4227        }
4228        up_read(&mm->mmap_sem);
4229}
4230
4231#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4232void might_fault(void)
4233{
4234        /*
4235         * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4236         * holding the mmap_sem, this is safe because kernel memory doesn't
4237         * get paged out, therefore we'll never actually fault, and the
4238         * below annotations will generate false positives.
4239         */
4240        if (segment_eq(get_fs(), KERNEL_DS))
4241                return;
4242
4243        /*
4244         * it would be nicer only to annotate paths which are not under
4245         * pagefault_disable, however that requires a larger audit and
4246         * providing helpers like get_user_atomic.
4247         */
4248        if (in_atomic())
4249                return;
4250
4251        __might_sleep(__FILE__, __LINE__, 0);
4252
4253        if (current->mm)
4254                might_lock_read(&current->mm->mmap_sem);
4255}
4256EXPORT_SYMBOL(might_fault);
4257#endif
4258
4259#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4260static void clear_gigantic_page(struct page *page,
4261                                unsigned long addr,
4262                                unsigned int pages_per_huge_page)
4263{
4264        int i;
4265        struct page *p = page;
4266
4267        might_sleep();
4268        for (i = 0; i < pages_per_huge_page;
4269             i++, p = mem_map_next(p, page, i)) {
4270                cond_resched();
4271                clear_user_highpage(p, addr + i * PAGE_SIZE);
4272        }
4273}
4274void clear_huge_page(struct page *page,
4275                     unsigned long addr, unsigned int pages_per_huge_page)
4276{
4277        int i;
4278
4279        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4280                clear_gigantic_page(page, addr, pages_per_huge_page);
4281                return;
4282        }
4283
4284        might_sleep();
4285        for (i = 0; i < pages_per_huge_page; i++) {
4286                cond_resched();
4287                clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4288        }
4289}
4290
4291static void copy_user_gigantic_page(struct page *dst, struct page *src,
4292                                    unsigned long addr,
4293                                    struct vm_area_struct *vma,
4294                                    unsigned int pages_per_huge_page)
4295{
4296        int i;
4297        struct page *dst_base = dst;
4298        struct page *src_base = src;
4299
4300        for (i = 0; i < pages_per_huge_page; ) {
4301                cond_resched();
4302                copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4303
4304                i++;
4305                dst = mem_map_next(dst, dst_base, i);
4306                src = mem_map_next(src, src_base, i);
4307        }
4308}
4309
4310void copy_user_huge_page(struct page *dst, struct page *src,
4311                         unsigned long addr, struct vm_area_struct *vma,
4312                         unsigned int pages_per_huge_page)
4313{
4314        int i;
4315
4316        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4317                copy_user_gigantic_page(dst, src, addr, vma,
4318                                        pages_per_huge_page);
4319                return;
4320        }
4321
4322        might_sleep();
4323        for (i = 0; i < pages_per_huge_page; i++) {
4324                cond_resched();
4325                copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4326        }
4327}
4328#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4329
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