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/sched/mm.h>
  44#include <linux/sched/coredump.h>
  45#include <linux/sched/numa_balancing.h>
  46#include <linux/sched/task.h>
  47#include <linux/hugetlb.h>
  48#include <linux/mman.h>
  49#include <linux/swap.h>
  50#include <linux/highmem.h>
  51#include <linux/pagemap.h>
  52#include <linux/memremap.h>
  53#include <linux/ksm.h>
  54#include <linux/rmap.h>
  55#include <linux/export.h>
  56#include <linux/delayacct.h>
  57#include <linux/init.h>
  58#include <linux/pfn_t.h>
  59#include <linux/writeback.h>
  60#include <linux/memcontrol.h>
  61#include <linux/mmu_notifier.h>
  62#include <linux/kallsyms.h>
  63#include <linux/swapops.h>
  64#include <linux/elf.h>
  65#include <linux/gfp.h>
  66#include <linux/migrate.h>
  67#include <linux/string.h>
  68#include <linux/dma-debug.h>
  69#include <linux/debugfs.h>
  70#include <linux/userfaultfd_k.h>
  71#include <linux/dax.h>
  72#include <linux/oom.h>
  73
  74#include <asm/io.h>
  75#include <asm/mmu_context.h>
  76#include <asm/pgalloc.h>
  77#include <linux/uaccess.h>
  78#include <asm/tlb.h>
  79#include <asm/tlbflush.h>
  80#include <asm/pgtable.h>
  81
  82#include "internal.h"
  83
  84#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
  85#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
  86#endif
  87
  88#ifndef CONFIG_NEED_MULTIPLE_NODES
  89/* use the per-pgdat data instead for discontigmem - mbligh */
  90unsigned long max_mapnr;
  91EXPORT_SYMBOL(max_mapnr);
  92
  93struct page *mem_map;
  94EXPORT_SYMBOL(mem_map);
  95#endif
  96
  97/*
  98 * A number of key systems in x86 including ioremap() rely on the assumption
  99 * that high_memory defines the upper bound on direct map memory, then end
 100 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 101 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 102 * and ZONE_HIGHMEM.
 103 */
 104void *high_memory;
 105EXPORT_SYMBOL(high_memory);
 106
 107/*
 108 * Randomize the address space (stacks, mmaps, brk, etc.).
 109 *
 110 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 111 *   as ancient (libc5 based) binaries can segfault. )
 112 */
 113int randomize_va_space __read_mostly =
 114#ifdef CONFIG_COMPAT_BRK
 115                                        1;
 116#else
 117                                        2;
 118#endif
 119
 120static int __init disable_randmaps(char *s)
 121{
 122        randomize_va_space = 0;
 123        return 1;
 124}
 125__setup("norandmaps", disable_randmaps);
 126
 127unsigned long zero_pfn __read_mostly;
 128EXPORT_SYMBOL(zero_pfn);
 129
 130unsigned long highest_memmap_pfn __read_mostly;
 131
 132/*
 133 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 134 */
 135static int __init init_zero_pfn(void)
 136{
 137        zero_pfn = page_to_pfn(ZERO_PAGE(0));
 138        return 0;
 139}
 140core_initcall(init_zero_pfn);
 141
 142
 143#if defined(SPLIT_RSS_COUNTING)
 144
 145void sync_mm_rss(struct mm_struct *mm)
 146{
 147        int i;
 148
 149        for (i = 0; i < NR_MM_COUNTERS; i++) {
 150                if (current->rss_stat.count[i]) {
 151                        add_mm_counter(mm, i, current->rss_stat.count[i]);
 152                        current->rss_stat.count[i] = 0;
 153                }
 154        }
 155        current->rss_stat.events = 0;
 156}
 157
 158static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
 159{
 160        struct task_struct *task = current;
 161
 162        if (likely(task->mm == mm))
 163                task->rss_stat.count[member] += val;
 164        else
 165                add_mm_counter(mm, member, val);
 166}
 167#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
 168#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
 169
 170/* sync counter once per 64 page faults */
 171#define TASK_RSS_EVENTS_THRESH  (64)
 172static void check_sync_rss_stat(struct task_struct *task)
 173{
 174        if (unlikely(task != current))
 175                return;
 176        if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
 177                sync_mm_rss(task->mm);
 178}
 179#else /* SPLIT_RSS_COUNTING */
 180
 181#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
 182#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
 183
 184static void check_sync_rss_stat(struct task_struct *task)
 185{
 186}
 187
 188#endif /* SPLIT_RSS_COUNTING */
 189
 190#ifdef HAVE_GENERIC_MMU_GATHER
 191
 192static bool tlb_next_batch(struct mmu_gather *tlb)
 193{
 194        struct mmu_gather_batch *batch;
 195
 196        batch = tlb->active;
 197        if (batch->next) {
 198                tlb->active = batch->next;
 199                return true;
 200        }
 201
 202        if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
 203                return false;
 204
 205        batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 206        if (!batch)
 207                return false;
 208
 209        tlb->batch_count++;
 210        batch->next = NULL;
 211        batch->nr   = 0;
 212        batch->max  = MAX_GATHER_BATCH;
 213
 214        tlb->active->next = batch;
 215        tlb->active = batch;
 216
 217        return true;
 218}
 219
 220void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
 221                                unsigned long start, unsigned long end)
 222{
 223        tlb->mm = mm;
 224
 225        /* Is it from 0 to ~0? */
 226        tlb->fullmm     = !(start | (end+1));
 227        tlb->need_flush_all = 0;
 228        tlb->local.next = NULL;
 229        tlb->local.nr   = 0;
 230        tlb->local.max  = ARRAY_SIZE(tlb->__pages);
 231        tlb->active     = &tlb->local;
 232        tlb->batch_count = 0;
 233
 234#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 235        tlb->batch = NULL;
 236#endif
 237        tlb->page_size = 0;
 238
 239        __tlb_reset_range(tlb);
 240}
 241
 242static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
 243{
 244        if (!tlb->end)
 245                return;
 246
 247        tlb_flush(tlb);
 248        mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
 249#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 250        tlb_table_flush(tlb);
 251#endif
 252        __tlb_reset_range(tlb);
 253}
 254
 255static void tlb_flush_mmu_free(struct mmu_gather *tlb)
 256{
 257        struct mmu_gather_batch *batch;
 258
 259        for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
 260                free_pages_and_swap_cache(batch->pages, batch->nr);
 261                batch->nr = 0;
 262        }
 263        tlb->active = &tlb->local;
 264}
 265
 266void tlb_flush_mmu(struct mmu_gather *tlb)
 267{
 268        tlb_flush_mmu_tlbonly(tlb);
 269        tlb_flush_mmu_free(tlb);
 270}
 271
 272/* tlb_finish_mmu
 273 *      Called at the end of the shootdown operation to free up any resources
 274 *      that were required.
 275 */
 276void arch_tlb_finish_mmu(struct mmu_gather *tlb,
 277                unsigned long start, unsigned long end, bool force)
 278{
 279        struct mmu_gather_batch *batch, *next;
 280
 281        if (force)
 282                __tlb_adjust_range(tlb, start, end - start);
 283
 284        tlb_flush_mmu(tlb);
 285
 286        /* keep the page table cache within bounds */
 287        check_pgt_cache();
 288
 289        for (batch = tlb->local.next; batch; batch = next) {
 290                next = batch->next;
 291                free_pages((unsigned long)batch, 0);
 292        }
 293        tlb->local.next = NULL;
 294}
 295
 296/* __tlb_remove_page
 297 *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 298 *      handling the additional races in SMP caused by other CPUs caching valid
 299 *      mappings in their TLBs. Returns the number of free page slots left.
 300 *      When out of page slots we must call tlb_flush_mmu().
 301 *returns true if the caller should flush.
 302 */
 303bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
 304{
 305        struct mmu_gather_batch *batch;
 306
 307        VM_BUG_ON(!tlb->end);
 308        VM_WARN_ON(tlb->page_size != page_size);
 309
 310        batch = tlb->active;
 311        /*
 312         * Add the page and check if we are full. If so
 313         * force a flush.
 314         */
 315        batch->pages[batch->nr++] = page;
 316        if (batch->nr == batch->max) {
 317                if (!tlb_next_batch(tlb))
 318                        return true;
 319                batch = tlb->active;
 320        }
 321        VM_BUG_ON_PAGE(batch->nr > batch->max, page);
 322
 323        return false;
 324}
 325
 326#endif /* HAVE_GENERIC_MMU_GATHER */
 327
 328#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 329
 330/*
 331 * See the comment near struct mmu_table_batch.
 332 */
 333
 334static void tlb_remove_table_smp_sync(void *arg)
 335{
 336        /* Simply deliver the interrupt */
 337}
 338
 339static void tlb_remove_table_one(void *table)
 340{
 341        /*
 342         * This isn't an RCU grace period and hence the page-tables cannot be
 343         * assumed to be actually RCU-freed.
 344         *
 345         * It is however sufficient for software page-table walkers that rely on
 346         * IRQ disabling. See the comment near struct mmu_table_batch.
 347         */
 348        smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
 349        __tlb_remove_table(table);
 350}
 351
 352static void tlb_remove_table_rcu(struct rcu_head *head)
 353{
 354        struct mmu_table_batch *batch;
 355        int i;
 356
 357        batch = container_of(head, struct mmu_table_batch, rcu);
 358
 359        for (i = 0; i < batch->nr; i++)
 360                __tlb_remove_table(batch->tables[i]);
 361
 362        free_page((unsigned long)batch);
 363}
 364
 365void tlb_table_flush(struct mmu_gather *tlb)
 366{
 367        struct mmu_table_batch **batch = &tlb->batch;
 368
 369        if (*batch) {
 370                call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
 371                *batch = NULL;
 372        }
 373}
 374
 375void tlb_remove_table(struct mmu_gather *tlb, void *table)
 376{
 377        struct mmu_table_batch **batch = &tlb->batch;
 378
 379        /*
 380         * When there's less then two users of this mm there cannot be a
 381         * concurrent page-table walk.
 382         */
 383        if (atomic_read(&tlb->mm->mm_users) < 2) {
 384                __tlb_remove_table(table);
 385                return;
 386        }
 387
 388        if (*batch == NULL) {
 389                *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
 390                if (*batch == NULL) {
 391                        tlb_remove_table_one(table);
 392                        return;
 393                }
 394                (*batch)->nr = 0;
 395        }
 396        (*batch)->tables[(*batch)->nr++] = table;
 397        if ((*batch)->nr == MAX_TABLE_BATCH)
 398                tlb_table_flush(tlb);
 399}
 400
 401#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
 402
 403/* tlb_gather_mmu
 404 *      Called to initialize an (on-stack) mmu_gather structure for page-table
 405 *      tear-down from @mm. The @fullmm argument is used when @mm is without
 406 *      users and we're going to destroy the full address space (exit/execve).
 407 */
 408void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
 409                        unsigned long start, unsigned long end)
 410{
 411        arch_tlb_gather_mmu(tlb, mm, start, end);
 412        inc_tlb_flush_pending(tlb->mm);
 413}
 414
 415void tlb_finish_mmu(struct mmu_gather *tlb,
 416                unsigned long start, unsigned long end)
 417{
 418        /*
 419         * If there are parallel threads are doing PTE changes on same range
 420         * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
 421         * flush by batching, a thread has stable TLB entry can fail to flush
 422         * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
 423         * forcefully if we detect parallel PTE batching threads.
 424         */
 425        bool force = mm_tlb_flush_nested(tlb->mm);
 426
 427        arch_tlb_finish_mmu(tlb, start, end, force);
 428        dec_tlb_flush_pending(tlb->mm);
 429}
 430
 431/*
 432 * Note: this doesn't free the actual pages themselves. That
 433 * has been handled earlier when unmapping all the memory regions.
 434 */
 435static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 436                           unsigned long addr)
 437{
 438        pgtable_t token = pmd_pgtable(*pmd);
 439        pmd_clear(pmd);
 440        pte_free_tlb(tlb, token, addr);
 441        atomic_long_dec(&tlb->mm->nr_ptes);
 442}
 443
 444static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 445                                unsigned long addr, unsigned long end,
 446                                unsigned long floor, unsigned long ceiling)
 447{
 448        pmd_t *pmd;
 449        unsigned long next;
 450        unsigned long start;
 451
 452        start = addr;
 453        pmd = pmd_offset(pud, addr);
 454        do {
 455                next = pmd_addr_end(addr, end);
 456                if (pmd_none_or_clear_bad(pmd))
 457                        continue;
 458                free_pte_range(tlb, pmd, addr);
 459        } while (pmd++, addr = next, addr != end);
 460
 461        start &= PUD_MASK;
 462        if (start < floor)
 463                return;
 464        if (ceiling) {
 465                ceiling &= PUD_MASK;
 466                if (!ceiling)
 467                        return;
 468        }
 469        if (end - 1 > ceiling - 1)
 470                return;
 471
 472        pmd = pmd_offset(pud, start);
 473        pud_clear(pud);
 474        pmd_free_tlb(tlb, pmd, start);
 475        mm_dec_nr_pmds(tlb->mm);
 476}
 477
 478static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
 479                                unsigned long addr, unsigned long end,
 480                                unsigned long floor, unsigned long ceiling)
 481{
 482        pud_t *pud;
 483        unsigned long next;
 484        unsigned long start;
 485
 486        start = addr;
 487        pud = pud_offset(p4d, addr);
 488        do {
 489                next = pud_addr_end(addr, end);
 490                if (pud_none_or_clear_bad(pud))
 491                        continue;
 492                free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 493        } while (pud++, addr = next, addr != end);
 494
 495        start &= P4D_MASK;
 496        if (start < floor)
 497                return;
 498        if (ceiling) {
 499                ceiling &= P4D_MASK;
 500                if (!ceiling)
 501                        return;
 502        }
 503        if (end - 1 > ceiling - 1)
 504                return;
 505
 506        pud = pud_offset(p4d, start);
 507        p4d_clear(p4d);
 508        pud_free_tlb(tlb, pud, start);
 509}
 510
 511static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
 512                                unsigned long addr, unsigned long end,
 513                                unsigned long floor, unsigned long ceiling)
 514{
 515        p4d_t *p4d;
 516        unsigned long next;
 517        unsigned long start;
 518
 519        start = addr;
 520        p4d = p4d_offset(pgd, addr);
 521        do {
 522                next = p4d_addr_end(addr, end);
 523                if (p4d_none_or_clear_bad(p4d))
 524                        continue;
 525                free_pud_range(tlb, p4d, addr, next, floor, ceiling);
 526        } while (p4d++, addr = next, addr != end);
 527
 528        start &= PGDIR_MASK;
 529        if (start < floor)
 530                return;
 531        if (ceiling) {
 532                ceiling &= PGDIR_MASK;
 533                if (!ceiling)
 534                        return;
 535        }
 536        if (end - 1 > ceiling - 1)
 537                return;
 538
 539        p4d = p4d_offset(pgd, start);
 540        pgd_clear(pgd);
 541        p4d_free_tlb(tlb, p4d, start);
 542}
 543
 544/*
 545 * This function frees user-level page tables of a process.
 546 */
 547void free_pgd_range(struct mmu_gather *tlb,
 548                        unsigned long addr, unsigned long end,
 549                        unsigned long floor, unsigned long ceiling)
 550{
 551        pgd_t *pgd;
 552        unsigned long next;
 553
 554        /*
 555         * The next few lines have given us lots of grief...
 556         *
 557         * Why are we testing PMD* at this top level?  Because often
 558         * there will be no work to do at all, and we'd prefer not to
 559         * go all the way down to the bottom just to discover that.
 560         *
 561         * Why all these "- 1"s?  Because 0 represents both the bottom
 562         * of the address space and the top of it (using -1 for the
 563         * top wouldn't help much: the masks would do the wrong thing).
 564         * The rule is that addr 0 and floor 0 refer to the bottom of
 565         * the address space, but end 0 and ceiling 0 refer to the top
 566         * Comparisons need to use "end - 1" and "ceiling - 1" (though
 567         * that end 0 case should be mythical).
 568         *
 569         * Wherever addr is brought up or ceiling brought down, we must
 570         * be careful to reject "the opposite 0" before it confuses the
 571         * subsequent tests.  But what about where end is brought down
 572         * by PMD_SIZE below? no, end can't go down to 0 there.
 573         *
 574         * Whereas we round start (addr) and ceiling down, by different
 575         * masks at different levels, in order to test whether a table
 576         * now has no other vmas using it, so can be freed, we don't
 577         * bother to round floor or end up - the tests don't need that.
 578         */
 579
 580        addr &= PMD_MASK;
 581        if (addr < floor) {
 582                addr += PMD_SIZE;
 583                if (!addr)
 584                        return;
 585        }
 586        if (ceiling) {
 587                ceiling &= PMD_MASK;
 588                if (!ceiling)
 589                        return;
 590        }
 591        if (end - 1 > ceiling - 1)
 592                end -= PMD_SIZE;
 593        if (addr > end - 1)
 594                return;
 595        /*
 596         * We add page table cache pages with PAGE_SIZE,
 597         * (see pte_free_tlb()), flush the tlb if we need
 598         */
 599        tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
 600        pgd = pgd_offset(tlb->mm, addr);
 601        do {
 602                next = pgd_addr_end(addr, end);
 603                if (pgd_none_or_clear_bad(pgd))
 604                        continue;
 605                free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
 606        } while (pgd++, addr = next, addr != end);
 607}
 608
 609void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 610                unsigned long floor, unsigned long ceiling)
 611{
 612        while (vma) {
 613                struct vm_area_struct *next = vma->vm_next;
 614                unsigned long addr = vma->vm_start;
 615
 616                /*
 617                 * Hide vma from rmap and truncate_pagecache before freeing
 618                 * pgtables
 619                 */
 620                unlink_anon_vmas(vma);
 621                unlink_file_vma(vma);
 622
 623                if (is_vm_hugetlb_page(vma)) {
 624                        hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 625                                floor, next ? next->vm_start : ceiling);
 626                } else {
 627                        /*
 628                         * Optimization: gather nearby vmas into one call down
 629                         */
 630                        while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 631                               && !is_vm_hugetlb_page(next)) {
 632                                vma = next;
 633                                next = vma->vm_next;
 634                                unlink_anon_vmas(vma);
 635                                unlink_file_vma(vma);
 636                        }
 637                        free_pgd_range(tlb, addr, vma->vm_end,
 638                                floor, next ? next->vm_start : ceiling);
 639                }
 640                vma = next;
 641        }
 642}
 643
 644int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 645{
 646        spinlock_t *ptl;
 647        pgtable_t new = pte_alloc_one(mm, address);
 648        if (!new)
 649                return -ENOMEM;
 650
 651        /*
 652         * Ensure all pte setup (eg. pte page lock and page clearing) are
 653         * visible before the pte is made visible to other CPUs by being
 654         * put into page tables.
 655         *
 656         * The other side of the story is the pointer chasing in the page
 657         * table walking code (when walking the page table without locking;
 658         * ie. most of the time). Fortunately, these data accesses consist
 659         * of a chain of data-dependent loads, meaning most CPUs (alpha
 660         * being the notable exception) will already guarantee loads are
 661         * seen in-order. See the alpha page table accessors for the
 662         * smp_read_barrier_depends() barriers in page table walking code.
 663         */
 664        smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 665
 666        ptl = pmd_lock(mm, pmd);
 667        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 668                atomic_long_inc(&mm->nr_ptes);
 669                pmd_populate(mm, pmd, new);
 670                new = NULL;
 671        }
 672        spin_unlock(ptl);
 673        if (new)
 674                pte_free(mm, new);
 675        return 0;
 676}
 677
 678int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 679{
 680        pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 681        if (!new)
 682                return -ENOMEM;
 683
 684        smp_wmb(); /* See comment in __pte_alloc */
 685
 686        spin_lock(&init_mm.page_table_lock);
 687        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 688                pmd_populate_kernel(&init_mm, pmd, new);
 689                new = NULL;
 690        }
 691        spin_unlock(&init_mm.page_table_lock);
 692        if (new)
 693                pte_free_kernel(&init_mm, new);
 694        return 0;
 695}
 696
 697static inline void init_rss_vec(int *rss)
 698{
 699        memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
 700}
 701
 702static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
 703{
 704        int i;
 705
 706        if (current->mm == mm)
 707                sync_mm_rss(mm);
 708        for (i = 0; i < NR_MM_COUNTERS; i++)
 709                if (rss[i])
 710                        add_mm_counter(mm, i, rss[i]);
 711}
 712
 713/*
 714 * This function is called to print an error when a bad pte
 715 * is found. For example, we might have a PFN-mapped pte in
 716 * a region that doesn't allow it.
 717 *
 718 * The calling function must still handle the error.
 719 */
 720static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 721                          pte_t pte, struct page *page)
 722{
 723        pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
 724        p4d_t *p4d = p4d_offset(pgd, addr);
 725        pud_t *pud = pud_offset(p4d, addr);
 726        pmd_t *pmd = pmd_offset(pud, addr);
 727        struct address_space *mapping;
 728        pgoff_t index;
 729        static unsigned long resume;
 730        static unsigned long nr_shown;
 731        static unsigned long nr_unshown;
 732
 733        /*
 734         * Allow a burst of 60 reports, then keep quiet for that minute;
 735         * or allow a steady drip of one report per second.
 736         */
 737        if (nr_shown == 60) {
 738                if (time_before(jiffies, resume)) {
 739                        nr_unshown++;
 740                        return;
 741                }
 742                if (nr_unshown) {
 743                        pr_alert("BUG: Bad page map: %lu messages suppressed\n",
 744                                 nr_unshown);
 745                        nr_unshown = 0;
 746                }
 747                nr_shown = 0;
 748        }
 749        if (nr_shown++ == 0)
 750                resume = jiffies + 60 * HZ;
 751
 752        mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 753        index = linear_page_index(vma, addr);
 754
 755        pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
 756                 current->comm,
 757                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
 758        if (page)
 759                dump_page(page, "bad pte");
 760        pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
 761                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
 762        /*
 763         * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 764         */
 765        pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
 766                 vma->vm_file,
 767                 vma->vm_ops ? vma->vm_ops->fault : NULL,
 768                 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
 769                 mapping ? mapping->a_ops->readpage : NULL);
 770        dump_stack();
 771        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 772}
 773
 774/*
 775 * vm_normal_page -- This function gets the "struct page" associated with a pte.
 776 *
 777 * "Special" mappings do not wish to be associated with a "struct page" (either
 778 * it doesn't exist, or it exists but they don't want to touch it). In this
 779 * case, NULL is returned here. "Normal" mappings do have a struct page.
 780 *
 781 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 782 * pte bit, in which case this function is trivial. Secondly, an architecture
 783 * may not have a spare pte bit, which requires a more complicated scheme,
 784 * described below.
 785 *
 786 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 787 * special mapping (even if there are underlying and valid "struct pages").
 788 * COWed pages of a VM_PFNMAP are always normal.
 789 *
 790 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 791 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
 792 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 793 * mapping will always honor the rule
 794 *
 795 *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 796 *
 797 * And for normal mappings this is false.
 798 *
 799 * This restricts such mappings to be a linear translation from virtual address
 800 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 801 * as the vma is not a COW mapping; in that case, we know that all ptes are
 802 * special (because none can have been COWed).
 803 *
 804 *
 805 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
 806 *
 807 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 808 * page" backing, however the difference is that _all_ pages with a struct
 809 * page (that is, those where pfn_valid is true) are refcounted and considered
 810 * normal pages by the VM. The disadvantage is that pages are refcounted
 811 * (which can be slower and simply not an option for some PFNMAP users). The
 812 * advantage is that we don't have to follow the strict linearity rule of
 813 * PFNMAP mappings in order to support COWable mappings.
 814 *
 815 */
 816#ifdef __HAVE_ARCH_PTE_SPECIAL
 817# define HAVE_PTE_SPECIAL 1
 818#else
 819# define HAVE_PTE_SPECIAL 0
 820#endif
 821struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 822                             pte_t pte, bool with_public_device)
 823{
 824        unsigned long pfn = pte_pfn(pte);
 825
 826        if (HAVE_PTE_SPECIAL) {
 827                if (likely(!pte_special(pte)))
 828                        goto check_pfn;
 829                if (vma->vm_ops && vma->vm_ops->find_special_page)
 830                        return vma->vm_ops->find_special_page(vma, addr);
 831                if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
 832                        return NULL;
 833                if (is_zero_pfn(pfn))
 834                        return NULL;
 835
 836                /*
 837                 * Device public pages are special pages (they are ZONE_DEVICE
 838                 * pages but different from persistent memory). They behave
 839                 * allmost like normal pages. The difference is that they are
 840                 * not on the lru and thus should never be involve with any-
 841                 * thing that involve lru manipulation (mlock, numa balancing,
 842                 * ...).
 843                 *
 844                 * This is why we still want to return NULL for such page from
 845                 * vm_normal_page() so that we do not have to special case all
 846                 * call site of vm_normal_page().
 847                 */
 848                if (likely(pfn <= highest_memmap_pfn)) {
 849                        struct page *page = pfn_to_page(pfn);
 850
 851                        if (is_device_public_page(page)) {
 852                                if (with_public_device)
 853                                        return page;
 854                                return NULL;
 855                        }
 856                }
 857                print_bad_pte(vma, addr, pte, NULL);
 858                return NULL;
 859        }
 860
 861        /* !HAVE_PTE_SPECIAL case follows: */
 862
 863        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 864                if (vma->vm_flags & VM_MIXEDMAP) {
 865                        if (!pfn_valid(pfn))
 866                                return NULL;
 867                        goto out;
 868                } else {
 869                        unsigned long off;
 870                        off = (addr - vma->vm_start) >> PAGE_SHIFT;
 871                        if (pfn == vma->vm_pgoff + off)
 872                                return NULL;
 873                        if (!is_cow_mapping(vma->vm_flags))
 874                                return NULL;
 875                }
 876        }
 877
 878        if (is_zero_pfn(pfn))
 879                return NULL;
 880check_pfn:
 881        if (unlikely(pfn > highest_memmap_pfn)) {
 882                print_bad_pte(vma, addr, pte, NULL);
 883                return NULL;
 884        }
 885
 886        /*
 887         * NOTE! We still have PageReserved() pages in the page tables.
 888         * eg. VDSO mappings can cause them to exist.
 889         */
 890out:
 891        return pfn_to_page(pfn);
 892}
 893
 894#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 895struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
 896                                pmd_t pmd)
 897{
 898        unsigned long pfn = pmd_pfn(pmd);
 899
 900        /*
 901         * There is no pmd_special() but there may be special pmds, e.g.
 902         * in a direct-access (dax) mapping, so let's just replicate the
 903         * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
 904         */
 905        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 906                if (vma->vm_flags & VM_MIXEDMAP) {
 907                        if (!pfn_valid(pfn))
 908                                return NULL;
 909                        goto out;
 910                } else {
 911                        unsigned long off;
 912                        off = (addr - vma->vm_start) >> PAGE_SHIFT;
 913                        if (pfn == vma->vm_pgoff + off)
 914                                return NULL;
 915                        if (!is_cow_mapping(vma->vm_flags))
 916                                return NULL;
 917                }
 918        }
 919
 920        if (is_zero_pfn(pfn))
 921                return NULL;
 922        if (unlikely(pfn > highest_memmap_pfn))
 923                return NULL;
 924
 925        /*
 926         * NOTE! We still have PageReserved() pages in the page tables.
 927         * eg. VDSO mappings can cause them to exist.
 928         */
 929out:
 930        return pfn_to_page(pfn);
 931}
 932#endif
 933
 934/*
 935 * copy one vm_area from one task to the other. Assumes the page tables
 936 * already present in the new task to be cleared in the whole range
 937 * covered by this vma.
 938 */
 939
 940static inline unsigned long
 941copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 942                pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 943                unsigned long addr, int *rss)
 944{
 945        unsigned long vm_flags = vma->vm_flags;
 946        pte_t pte = *src_pte;
 947        struct page *page;
 948
 949        /* pte contains position in swap or file, so copy. */
 950        if (unlikely(!pte_present(pte))) {
 951                swp_entry_t entry = pte_to_swp_entry(pte);
 952
 953                if (likely(!non_swap_entry(entry))) {
 954                        if (swap_duplicate(entry) < 0)
 955                                return entry.val;
 956
 957                        /* make sure dst_mm is on swapoff's mmlist. */
 958                        if (unlikely(list_empty(&dst_mm->mmlist))) {
 959                                spin_lock(&mmlist_lock);
 960                                if (list_empty(&dst_mm->mmlist))
 961                                        list_add(&dst_mm->mmlist,
 962                                                        &src_mm->mmlist);
 963                                spin_unlock(&mmlist_lock);
 964                        }
 965                        rss[MM_SWAPENTS]++;
 966                } else if (is_migration_entry(entry)) {
 967                        page = migration_entry_to_page(entry);
 968
 969                        rss[mm_counter(page)]++;
 970
 971                        if (is_write_migration_entry(entry) &&
 972                                        is_cow_mapping(vm_flags)) {
 973                                /*
 974                                 * COW mappings require pages in both
 975                                 * parent and child to be set to read.
 976                                 */
 977                                make_migration_entry_read(&entry);
 978                                pte = swp_entry_to_pte(entry);
 979                                if (pte_swp_soft_dirty(*src_pte))
 980                                        pte = pte_swp_mksoft_dirty(pte);
 981                                set_pte_at(src_mm, addr, src_pte, pte);
 982                        }
 983                } else if (is_device_private_entry(entry)) {
 984                        page = device_private_entry_to_page(entry);
 985
 986                        /*
 987                         * Update rss count even for unaddressable pages, as
 988                         * they should treated just like normal pages in this
 989                         * respect.
 990                         *
 991                         * We will likely want to have some new rss counters
 992                         * for unaddressable pages, at some point. But for now
 993                         * keep things as they are.
 994                         */
 995                        get_page(page);
 996                        rss[mm_counter(page)]++;
 997                        page_dup_rmap(page, false);
 998
 999                        /*
1000                         * We do not preserve soft-dirty information, because so
1001                         * far, checkpoint/restore is the only feature that
1002                         * requires that. And checkpoint/restore does not work
1003                         * when a device driver is involved (you cannot easily
1004                         * save and restore device driver state).
1005                         */
1006                        if (is_write_device_private_entry(entry) &&
1007                            is_cow_mapping(vm_flags)) {
1008                                make_device_private_entry_read(&entry);
1009                                pte = swp_entry_to_pte(entry);
1010                                set_pte_at(src_mm, addr, src_pte, pte);
1011                        }
1012                }
1013                goto out_set_pte;
1014        }
1015
1016        /*
1017         * If it's a COW mapping, write protect it both
1018         * in the parent and the child
1019         */
1020        if (is_cow_mapping(vm_flags)) {
1021                ptep_set_wrprotect(src_mm, addr, src_pte);
1022                pte = pte_wrprotect(pte);
1023        }
1024
1025        /*
1026         * If it's a shared mapping, mark it clean in
1027         * the child
1028         */
1029        if (vm_flags & VM_SHARED)
1030                pte = pte_mkclean(pte);
1031        pte = pte_mkold(pte);
1032
1033        page = vm_normal_page(vma, addr, pte);
1034        if (page) {
1035                get_page(page);
1036                page_dup_rmap(page, false);
1037                rss[mm_counter(page)]++;
1038        } else if (pte_devmap(pte)) {
1039                page = pte_page(pte);
1040
1041                /*
1042                 * Cache coherent device memory behave like regular page and
1043                 * not like persistent memory page. For more informations see
1044                 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
1045                 */
1046                if (is_device_public_page(page)) {
1047                        get_page(page);
1048                        page_dup_rmap(page, false);
1049                        rss[mm_counter(page)]++;
1050                }
1051        }
1052
1053out_set_pte:
1054        set_pte_at(dst_mm, addr, dst_pte, pte);
1055        return 0;
1056}
1057
1058static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1059                   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
1060                   unsigned long addr, unsigned long end)
1061{
1062        pte_t *orig_src_pte, *orig_dst_pte;
1063        pte_t *src_pte, *dst_pte;
1064        spinlock_t *src_ptl, *dst_ptl;
1065        int progress = 0;
1066        int rss[NR_MM_COUNTERS];
1067        swp_entry_t entry = (swp_entry_t){0};
1068
1069again:
1070        init_rss_vec(rss);
1071
1072        dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1073        if (!dst_pte)
1074                return -ENOMEM;
1075        src_pte = pte_offset_map(src_pmd, addr);
1076        src_ptl = pte_lockptr(src_mm, src_pmd);
1077        spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1078        orig_src_pte = src_pte;
1079        orig_dst_pte = dst_pte;
1080        arch_enter_lazy_mmu_mode();
1081
1082        do {
1083                /*
1084                 * We are holding two locks at this point - either of them
1085                 * could generate latencies in another task on another CPU.
1086                 */
1087                if (progress >= 32) {
1088                        progress = 0;
1089                        if (need_resched() ||
1090                            spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1091                                break;
1092                }
1093                if (pte_none(*src_pte)) {
1094                        progress++;
1095                        continue;
1096                }
1097                entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1098                                                        vma, addr, rss);
1099                if (entry.val)
1100                        break;
1101                progress += 8;
1102        } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1103
1104        arch_leave_lazy_mmu_mode();
1105        spin_unlock(src_ptl);
1106        pte_unmap(orig_src_pte);
1107        add_mm_rss_vec(dst_mm, rss);
1108        pte_unmap_unlock(orig_dst_pte, dst_ptl);
1109        cond_resched();
1110
1111        if (entry.val) {
1112                if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1113                        return -ENOMEM;
1114                progress = 0;
1115        }
1116        if (addr != end)
1117                goto again;
1118        return 0;
1119}
1120
1121static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1122                pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1123                unsigned long addr, unsigned long end)
1124{
1125        pmd_t *src_pmd, *dst_pmd;
1126        unsigned long next;
1127
1128        dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1129        if (!dst_pmd)
1130                return -ENOMEM;
1131        src_pmd = pmd_offset(src_pud, addr);
1132        do {
1133                next = pmd_addr_end(addr, end);
1134                if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1135                        || pmd_devmap(*src_pmd)) {
1136                        int err;
1137                        VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1138                        err = copy_huge_pmd(dst_mm, src_mm,
1139                                            dst_pmd, src_pmd, addr, vma);
1140                        if (err == -ENOMEM)
1141                                return -ENOMEM;
1142                        if (!err)
1143                                continue;
1144                        /* fall through */
1145                }
1146                if (pmd_none_or_clear_bad(src_pmd))
1147                        continue;
1148                if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1149                                                vma, addr, next))
1150                        return -ENOMEM;
1151        } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1152        return 0;
1153}
1154
1155static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1156                p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1157                unsigned long addr, unsigned long end)
1158{
1159        pud_t *src_pud, *dst_pud;
1160        unsigned long next;
1161
1162        dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1163        if (!dst_pud)
1164                return -ENOMEM;
1165        src_pud = pud_offset(src_p4d, addr);
1166        do {
1167                next = pud_addr_end(addr, end);
1168                if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1169                        int err;
1170
1171                        VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1172                        err = copy_huge_pud(dst_mm, src_mm,
1173                                            dst_pud, src_pud, addr, vma);
1174                        if (err == -ENOMEM)
1175                                return -ENOMEM;
1176                        if (!err)
1177                                continue;
1178                        /* fall through */
1179                }
1180                if (pud_none_or_clear_bad(src_pud))
1181                        continue;
1182                if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1183                                                vma, addr, next))
1184                        return -ENOMEM;
1185        } while (dst_pud++, src_pud++, addr = next, addr != end);
1186        return 0;
1187}
1188
1189static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1190                pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1191                unsigned long addr, unsigned long end)
1192{
1193        p4d_t *src_p4d, *dst_p4d;
1194        unsigned long next;
1195
1196        dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1197        if (!dst_p4d)
1198                return -ENOMEM;
1199        src_p4d = p4d_offset(src_pgd, addr);
1200        do {
1201                next = p4d_addr_end(addr, end);
1202                if (p4d_none_or_clear_bad(src_p4d))
1203                        continue;
1204                if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1205                                                vma, addr, next))
1206                        return -ENOMEM;
1207        } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1208        return 0;
1209}
1210
1211int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1212                struct vm_area_struct *vma)
1213{
1214        pgd_t *src_pgd, *dst_pgd;
1215        unsigned long next;
1216        unsigned long addr = vma->vm_start;
1217        unsigned long end = vma->vm_end;
1218        unsigned long mmun_start;       /* For mmu_notifiers */
1219        unsigned long mmun_end;         /* For mmu_notifiers */
1220        bool is_cow;
1221        int ret;
1222
1223        /*
1224         * Don't copy ptes where a page fault will fill them correctly.
1225         * Fork becomes much lighter when there are big shared or private
1226         * readonly mappings. The tradeoff is that copy_page_range is more
1227         * efficient than faulting.
1228         */
1229        if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1230                        !vma->anon_vma)
1231                return 0;
1232
1233        if (is_vm_hugetlb_page(vma))
1234                return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1235
1236        if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1237                /*
1238                 * We do not free on error cases below as remove_vma
1239                 * gets called on error from higher level routine
1240                 */
1241                ret = track_pfn_copy(vma);
1242                if (ret)
1243                        return ret;
1244        }
1245
1246        /*
1247         * We need to invalidate the secondary MMU mappings only when
1248         * there could be a permission downgrade on the ptes of the
1249         * parent mm. And a permission downgrade will only happen if
1250         * is_cow_mapping() returns true.
1251         */
1252        is_cow = is_cow_mapping(vma->vm_flags);
1253        mmun_start = addr;
1254        mmun_end   = end;
1255        if (is_cow)
1256                mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1257                                                    mmun_end);
1258
1259        ret = 0;
1260        dst_pgd = pgd_offset(dst_mm, addr);
1261        src_pgd = pgd_offset(src_mm, addr);
1262        do {
1263                next = pgd_addr_end(addr, end);
1264                if (pgd_none_or_clear_bad(src_pgd))
1265                        continue;
1266                if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1267                                            vma, addr, next))) {
1268                        ret = -ENOMEM;
1269                        break;
1270                }
1271        } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1272
1273        if (is_cow)
1274                mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1275        return ret;
1276}
1277
1278static unsigned long zap_pte_range(struct mmu_gather *tlb,
1279                                struct vm_area_struct *vma, pmd_t *pmd,
1280                                unsigned long addr, unsigned long end,
1281                                struct zap_details *details)
1282{
1283        struct mm_struct *mm = tlb->mm;
1284        int force_flush = 0;
1285        int rss[NR_MM_COUNTERS];
1286        spinlock_t *ptl;
1287        pte_t *start_pte;
1288        pte_t *pte;
1289        swp_entry_t entry;
1290
1291        tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1292again:
1293        init_rss_vec(rss);
1294        start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1295        pte = start_pte;
1296        flush_tlb_batched_pending(mm);
1297        arch_enter_lazy_mmu_mode();
1298        do {
1299                pte_t ptent = *pte;
1300                if (pte_none(ptent))
1301                        continue;
1302
1303                if (pte_present(ptent)) {
1304                        struct page *page;
1305
1306                        page = _vm_normal_page(vma, addr, ptent, true);
1307                        if (unlikely(details) && page) {
1308                                /*
1309                                 * unmap_shared_mapping_pages() wants to
1310                                 * invalidate cache without truncating:
1311                                 * unmap shared but keep private pages.
1312                                 */
1313                                if (details->check_mapping &&
1314                                    details->check_mapping != page_rmapping(page))
1315                                        continue;
1316                        }
1317                        ptent = ptep_get_and_clear_full(mm, addr, pte,
1318                                                        tlb->fullmm);
1319                        tlb_remove_tlb_entry(tlb, pte, addr);
1320                        if (unlikely(!page))
1321                                continue;
1322
1323                        if (!PageAnon(page)) {
1324                                if (pte_dirty(ptent)) {
1325                                        force_flush = 1;
1326                                        set_page_dirty(page);
1327                                }
1328                                if (pte_young(ptent) &&
1329                                    likely(!(vma->vm_flags & VM_SEQ_READ)))
1330                                        mark_page_accessed(page);
1331                        }
1332                        rss[mm_counter(page)]--;
1333                        page_remove_rmap(page, false);
1334                        if (unlikely(page_mapcount(page) < 0))
1335                                print_bad_pte(vma, addr, ptent, page);
1336                        if (unlikely(__tlb_remove_page(tlb, page))) {
1337                                force_flush = 1;
1338                                addr += PAGE_SIZE;
1339                                break;
1340                        }
1341                        continue;
1342                }
1343
1344                entry = pte_to_swp_entry(ptent);
1345                if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1346                        struct page *page = device_private_entry_to_page(entry);
1347
1348                        if (unlikely(details && details->check_mapping)) {
1349                                /*
1350                                 * unmap_shared_mapping_pages() wants to
1351                                 * invalidate cache without truncating:
1352                                 * unmap shared but keep private pages.
1353                                 */
1354                                if (details->check_mapping !=
1355                                    page_rmapping(page))
1356                                        continue;
1357                        }
1358
1359                        pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1360                        rss[mm_counter(page)]--;
1361                        page_remove_rmap(page, false);
1362                        put_page(page);
1363                        continue;
1364                }
1365
1366                /* If details->check_mapping, we leave swap entries. */
1367                if (unlikely(details))
1368                        continue;
1369
1370                entry = pte_to_swp_entry(ptent);
1371                if (!non_swap_entry(entry))
1372                        rss[MM_SWAPENTS]--;
1373                else if (is_migration_entry(entry)) {
1374                        struct page *page;
1375
1376                        page = migration_entry_to_page(entry);
1377                        rss[mm_counter(page)]--;
1378                }
1379                if (unlikely(!free_swap_and_cache(entry)))
1380                        print_bad_pte(vma, addr, ptent, NULL);
1381                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1382        } while (pte++, addr += PAGE_SIZE, addr != end);
1383
1384        add_mm_rss_vec(mm, rss);
1385        arch_leave_lazy_mmu_mode();
1386
1387        /* Do the actual TLB flush before dropping ptl */
1388        if (force_flush)
1389                tlb_flush_mmu_tlbonly(tlb);
1390        pte_unmap_unlock(start_pte, ptl);
1391
1392        /*
1393         * If we forced a TLB flush (either due to running out of
1394         * batch buffers or because we needed to flush dirty TLB
1395         * entries before releasing the ptl), free the batched
1396         * memory too. Restart if we didn't do everything.
1397         */
1398        if (force_flush) {
1399                force_flush = 0;
1400                tlb_flush_mmu_free(tlb);
1401                if (addr != end)
1402                        goto again;
1403        }
1404
1405        return addr;
1406}
1407
1408static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1409                                struct vm_area_struct *vma, pud_t *pud,
1410                                unsigned long addr, unsigned long end,
1411                                struct zap_details *details)
1412{
1413        pmd_t *pmd;
1414        unsigned long next;
1415
1416        pmd = pmd_offset(pud, addr);
1417        do {
1418                next = pmd_addr_end(addr, end);
1419                if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1420                        if (next - addr != HPAGE_PMD_SIZE) {
1421                                VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1422                                    !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1423                                __split_huge_pmd(vma, pmd, addr, false, NULL);
1424                        } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1425                                goto next;
1426                        /* fall through */
1427                }
1428                /*
1429                 * Here there can be other concurrent MADV_DONTNEED or
1430                 * trans huge page faults running, and if the pmd is
1431                 * none or trans huge it can change under us. This is
1432                 * because MADV_DONTNEED holds the mmap_sem in read
1433                 * mode.
1434                 */
1435                if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1436                        goto next;
1437                next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1438next:
1439                cond_resched();
1440        } while (pmd++, addr = next, addr != end);
1441
1442        return addr;
1443}
1444
1445static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1446                                struct vm_area_struct *vma, p4d_t *p4d,
1447                                unsigned long addr, unsigned long end,
1448                                struct zap_details *details)
1449{
1450        pud_t *pud;
1451        unsigned long next;
1452
1453        pud = pud_offset(p4d, addr);
1454        do {
1455                next = pud_addr_end(addr, end);
1456                if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1457                        if (next - addr != HPAGE_PUD_SIZE) {
1458                                VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1459                                split_huge_pud(vma, pud, addr);
1460                        } else if (zap_huge_pud(tlb, vma, pud, addr))
1461                                goto next;
1462                        /* fall through */
1463                }
1464                if (pud_none_or_clear_bad(pud))
1465                        continue;
1466                next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1467next:
1468                cond_resched();
1469        } while (pud++, addr = next, addr != end);
1470
1471        return addr;
1472}
1473
1474static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1475                                struct vm_area_struct *vma, pgd_t *pgd,
1476                                unsigned long addr, unsigned long end,
1477                                struct zap_details *details)
1478{
1479        p4d_t *p4d;
1480        unsigned long next;
1481
1482        p4d = p4d_offset(pgd, addr);
1483        do {
1484                next = p4d_addr_end(addr, end);
1485                if (p4d_none_or_clear_bad(p4d))
1486                        continue;
1487                next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1488        } while (p4d++, addr = next, addr != end);
1489
1490        return addr;
1491}
1492
1493void unmap_page_range(struct mmu_gather *tlb,
1494                             struct vm_area_struct *vma,
1495                             unsigned long addr, unsigned long end,
1496                             struct zap_details *details)
1497{
1498        pgd_t *pgd;
1499        unsigned long next;
1500
1501        BUG_ON(addr >= end);
1502        tlb_start_vma(tlb, vma);
1503        pgd = pgd_offset(vma->vm_mm, addr);
1504        do {
1505                next = pgd_addr_end(addr, end);
1506                if (pgd_none_or_clear_bad(pgd))
1507                        continue;
1508                next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1509        } while (pgd++, addr = next, addr != end);
1510        tlb_end_vma(tlb, vma);
1511}
1512
1513
1514static void unmap_single_vma(struct mmu_gather *tlb,
1515                struct vm_area_struct *vma, unsigned long start_addr,
1516                unsigned long end_addr,
1517                struct zap_details *details)
1518{
1519        unsigned long start = max(vma->vm_start, start_addr);
1520        unsigned long end;
1521
1522        if (start >= vma->vm_end)
1523                return;
1524        end = min(vma->vm_end, end_addr);
1525        if (end <= vma->vm_start)
1526                return;
1527
1528        if (vma->vm_file)
1529                uprobe_munmap(vma, start, end);
1530
1531        if (unlikely(vma->vm_flags & VM_PFNMAP))
1532                untrack_pfn(vma, 0, 0);
1533
1534        if (start != end) {
1535                if (unlikely(is_vm_hugetlb_page(vma))) {
1536                        /*
1537                         * It is undesirable to test vma->vm_file as it
1538                         * should be non-null for valid hugetlb area.
1539                         * However, vm_file will be NULL in the error
1540                         * cleanup path of mmap_region. When
1541                         * hugetlbfs ->mmap method fails,
1542                         * mmap_region() nullifies vma->vm_file
1543                         * before calling this function to clean up.
1544                         * Since no pte has actually been setup, it is
1545                         * safe to do nothing in this case.
1546                         */
1547                        if (vma->vm_file) {
1548                                i_mmap_lock_write(vma->vm_file->f_mapping);
1549                                __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1550                                i_mmap_unlock_write(vma->vm_file->f_mapping);
1551                        }
1552                } else
1553                        unmap_page_range(tlb, vma, start, end, details);
1554        }
1555}
1556
1557/**
1558 * unmap_vmas - unmap a range of memory covered by a list of vma's
1559 * @tlb: address of the caller's struct mmu_gather
1560 * @vma: the starting vma
1561 * @start_addr: virtual address at which to start unmapping
1562 * @end_addr: virtual address at which to end unmapping
1563 *
1564 * Unmap all pages in the vma list.
1565 *
1566 * Only addresses between `start' and `end' will be unmapped.
1567 *
1568 * The VMA list must be sorted in ascending virtual address order.
1569 *
1570 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1571 * range after unmap_vmas() returns.  So the only responsibility here is to
1572 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1573 * drops the lock and schedules.
1574 */
1575void unmap_vmas(struct mmu_gather *tlb,
1576                struct vm_area_struct *vma, unsigned long start_addr,
1577                unsigned long end_addr)
1578{
1579        struct mm_struct *mm = vma->vm_mm;
1580
1581        mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1582        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1583                unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1584        mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1585}
1586
1587/**
1588 * zap_page_range - remove user pages in a given range
1589 * @vma: vm_area_struct holding the applicable pages
1590 * @start: starting address of pages to zap
1591 * @size: number of bytes to zap
1592 *
1593 * Caller must protect the VMA list
1594 */
1595void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1596                unsigned long size)
1597{
1598        struct mm_struct *mm = vma->vm_mm;
1599        struct mmu_gather tlb;
1600        unsigned long end = start + size;
1601
1602        lru_add_drain();
1603        tlb_gather_mmu(&tlb, mm, start, end);
1604        update_hiwater_rss(mm);
1605        mmu_notifier_invalidate_range_start(mm, start, end);
1606        for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
1607                unmap_single_vma(&tlb, vma, start, end, NULL);
1608
1609                /*
1610                 * zap_page_range does not specify whether mmap_sem should be
1611                 * held for read or write. That allows parallel zap_page_range
1612                 * operations to unmap a PTE and defer a flush meaning that
1613                 * this call observes pte_none and fails to flush the TLB.
1614                 * Rather than adding a complex API, ensure that no stale
1615                 * TLB entries exist when this call returns.
1616                 */
1617                flush_tlb_range(vma, start, end);
1618        }
1619
1620        mmu_notifier_invalidate_range_end(mm, start, end);
1621        tlb_finish_mmu(&tlb, start, end);
1622}
1623
1624/**
1625 * zap_page_range_single - remove user pages in a given range
1626 * @vma: vm_area_struct holding the applicable pages
1627 * @address: starting address of pages to zap
1628 * @size: number of bytes to zap
1629 * @details: details of shared cache invalidation
1630 *
1631 * The range must fit into one VMA.
1632 */
1633static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1634                unsigned long size, struct zap_details *details)
1635{
1636        struct mm_struct *mm = vma->vm_mm;
1637        struct mmu_gather tlb;
1638        unsigned long end = address + size;
1639
1640        lru_add_drain();
1641        tlb_gather_mmu(&tlb, mm, address, end);
1642        update_hiwater_rss(mm);
1643        mmu_notifier_invalidate_range_start(mm, address, end);
1644        unmap_single_vma(&tlb, vma, address, end, details);
1645        mmu_notifier_invalidate_range_end(mm, address, end);
1646        tlb_finish_mmu(&tlb, address, end);
1647}
1648
1649/**
1650 * zap_vma_ptes - remove ptes mapping the vma
1651 * @vma: vm_area_struct holding ptes to be zapped
1652 * @address: starting address of pages to zap
1653 * @size: number of bytes to zap
1654 *
1655 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1656 *
1657 * The entire address range must be fully contained within the vma.
1658 *
1659 * Returns 0 if successful.
1660 */
1661int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1662                unsigned long size)
1663{
1664        if (address < vma->vm_start || address + size > vma->vm_end ||
1665                        !(vma->vm_flags & VM_PFNMAP))
1666                return -1;
1667        zap_page_range_single(vma, address, size, NULL);
1668        return 0;
1669}
1670EXPORT_SYMBOL_GPL(zap_vma_ptes);
1671
1672pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1673                        spinlock_t **ptl)
1674{
1675        pgd_t *pgd;
1676        p4d_t *p4d;
1677        pud_t *pud;
1678        pmd_t *pmd;
1679
1680        pgd = pgd_offset(mm, addr);
1681        p4d = p4d_alloc(mm, pgd, addr);
1682        if (!p4d)
1683                return NULL;
1684        pud = pud_alloc(mm, p4d, addr);
1685        if (!pud)
1686                return NULL;
1687        pmd = pmd_alloc(mm, pud, addr);
1688        if (!pmd)
1689                return NULL;
1690
1691        VM_BUG_ON(pmd_trans_huge(*pmd));
1692        return pte_alloc_map_lock(mm, pmd, addr, ptl);
1693}
1694
1695/*
1696 * This is the old fallback for page remapping.
1697 *
1698 * For historical reasons, it only allows reserved pages. Only
1699 * old drivers should use this, and they needed to mark their
1700 * pages reserved for the old functions anyway.
1701 */
1702static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1703                        struct page *page, pgprot_t prot)
1704{
1705        struct mm_struct *mm = vma->vm_mm;
1706        int retval;
1707        pte_t *pte;
1708        spinlock_t *ptl;
1709
1710        retval = -EINVAL;
1711        if (PageAnon(page))
1712                goto out;
1713        retval = -ENOMEM;
1714        flush_dcache_page(page);
1715        pte = get_locked_pte(mm, addr, &ptl);
1716        if (!pte)
1717                goto out;
1718        retval = -EBUSY;
1719        if (!pte_none(*pte))
1720                goto out_unlock;
1721
1722        /* Ok, finally just insert the thing.. */
1723        get_page(page);
1724        inc_mm_counter_fast(mm, mm_counter_file(page));
1725        page_add_file_rmap(page, false);
1726        set_pte_at(mm, addr, pte, mk_pte(page, prot));
1727
1728        retval = 0;
1729        pte_unmap_unlock(pte, ptl);
1730        return retval;
1731out_unlock:
1732        pte_unmap_unlock(pte, ptl);
1733out:
1734        return retval;
1735}
1736
1737/**
1738 * vm_insert_page - insert single page into user vma
1739 * @vma: user vma to map to
1740 * @addr: target user address of this page
1741 * @page: source kernel page
1742 *
1743 * This allows drivers to insert individual pages they've allocated
1744 * into a user vma.
1745 *
1746 * The page has to be a nice clean _individual_ kernel allocation.
1747 * If you allocate a compound page, you need to have marked it as
1748 * such (__GFP_COMP), or manually just split the page up yourself
1749 * (see split_page()).
1750 *
1751 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1752 * took an arbitrary page protection parameter. This doesn't allow
1753 * that. Your vma protection will have to be set up correctly, which
1754 * means that if you want a shared writable mapping, you'd better
1755 * ask for a shared writable mapping!
1756 *
1757 * The page does not need to be reserved.
1758 *
1759 * Usually this function is called from f_op->mmap() handler
1760 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1761 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1762 * function from other places, for example from page-fault handler.
1763 */
1764int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1765                        struct page *page)
1766{
1767        if (addr < vma->vm_start || addr >= vma->vm_end)
1768                return -EFAULT;
1769        if (!page_count(page))
1770                return -EINVAL;
1771        if (!(vma->vm_flags & VM_MIXEDMAP)) {
1772                BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1773                BUG_ON(vma->vm_flags & VM_PFNMAP);
1774                vma->vm_flags |= VM_MIXEDMAP;
1775        }
1776        return insert_page(vma, addr, page, vma->vm_page_prot);
1777}
1778EXPORT_SYMBOL(vm_insert_page);
1779
1780static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1781                        pfn_t pfn, pgprot_t prot, bool mkwrite)
1782{
1783        struct mm_struct *mm = vma->vm_mm;
1784        int retval;
1785        pte_t *pte, entry;
1786        spinlock_t *ptl;
1787
1788        retval = -ENOMEM;
1789        pte = get_locked_pte(mm, addr, &ptl);
1790        if (!pte)
1791                goto out;
1792        retval = -EBUSY;
1793        if (!pte_none(*pte)) {
1794                if (mkwrite) {
1795                        /*
1796                         * For read faults on private mappings the PFN passed
1797                         * in may not match the PFN we have mapped if the
1798                         * mapped PFN is a writeable COW page.  In the mkwrite
1799                         * case we are creating a writable PTE for a shared
1800                         * mapping and we expect the PFNs to match.
1801                         */
1802                        if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))
1803                                goto out_unlock;
1804                        entry = *pte;
1805                        goto out_mkwrite;
1806                } else
1807                        goto out_unlock;
1808        }
1809
1810        /* Ok, finally just insert the thing.. */
1811        if (pfn_t_devmap(pfn))
1812                entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1813        else
1814                entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1815
1816out_mkwrite:
1817        if (mkwrite) {
1818                entry = pte_mkyoung(entry);
1819                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1820        }
1821
1822        set_pte_at(mm, addr, pte, entry);
1823        update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1824
1825        retval = 0;
1826out_unlock:
1827        pte_unmap_unlock(pte, ptl);
1828out:
1829        return retval;
1830}
1831
1832/**
1833 * vm_insert_pfn - insert single pfn into user vma
1834 * @vma: user vma to map to
1835 * @addr: target user address of this page
1836 * @pfn: source kernel pfn
1837 *
1838 * Similar to vm_insert_page, this allows drivers to insert individual pages
1839 * they've allocated into a user vma. Same comments apply.
1840 *
1841 * This function should only be called from a vm_ops->fault handler, and
1842 * in that case the handler should return NULL.
1843 *
1844 * vma cannot be a COW mapping.
1845 *
1846 * As this is called only for pages that do not currently exist, we
1847 * do not need to flush old virtual caches or the TLB.
1848 */
1849int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1850                        unsigned long pfn)
1851{
1852        return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1853}
1854EXPORT_SYMBOL(vm_insert_pfn);
1855
1856/**
1857 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1858 * @vma: user vma to map to
1859 * @addr: target user address of this page
1860 * @pfn: source kernel pfn
1861 * @pgprot: pgprot flags for the inserted page
1862 *
1863 * This is exactly like vm_insert_pfn, except that it allows drivers to
1864 * to override pgprot on a per-page basis.
1865 *
1866 * This only makes sense for IO mappings, and it makes no sense for
1867 * cow mappings.  In general, using multiple vmas is preferable;
1868 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1869 * impractical.
1870 */
1871int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1872                        unsigned long pfn, pgprot_t pgprot)
1873{
1874        int ret;
1875        /*
1876         * Technically, architectures with pte_special can avoid all these
1877         * restrictions (same for remap_pfn_range).  However we would like
1878         * consistency in testing and feature parity among all, so we should
1879         * try to keep these invariants in place for everybody.
1880         */
1881        BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1882        BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1883                                                (VM_PFNMAP|VM_MIXEDMAP));
1884        BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1885        BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1886
1887        if (addr < vma->vm_start || addr >= vma->vm_end)
1888                return -EFAULT;
1889
1890        track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1891
1892        ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1893                        false);
1894
1895        return ret;
1896}
1897EXPORT_SYMBOL(vm_insert_pfn_prot);
1898
1899static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1900                        pfn_t pfn, bool mkwrite)
1901{
1902        pgprot_t pgprot = vma->vm_page_prot;
1903
1904        BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1905
1906        if (addr < vma->vm_start || addr >= vma->vm_end)
1907                return -EFAULT;
1908
1909        track_pfn_insert(vma, &pgprot, pfn);
1910
1911        /*
1912         * If we don't have pte special, then we have to use the pfn_valid()
1913         * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1914         * refcount the page if pfn_valid is true (hence insert_page rather
1915         * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1916         * without pte special, it would there be refcounted as a normal page.
1917         */
1918        if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1919                struct page *page;
1920
1921                /*
1922                 * At this point we are committed to insert_page()
1923                 * regardless of whether the caller specified flags that
1924                 * result in pfn_t_has_page() == false.
1925                 */
1926                page = pfn_to_page(pfn_t_to_pfn(pfn));
1927                return insert_page(vma, addr, page, pgprot);
1928        }
1929        return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1930}
1931
1932int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1933                        pfn_t pfn)
1934{
1935        return __vm_insert_mixed(vma, addr, pfn, false);
1936
1937}
1938EXPORT_SYMBOL(vm_insert_mixed);
1939
1940int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
1941                        pfn_t pfn)
1942{
1943        return __vm_insert_mixed(vma, addr, pfn, true);
1944}
1945EXPORT_SYMBOL(vm_insert_mixed_mkwrite);
1946
1947/*
1948 * maps a range of physical memory into the requested pages. the old
1949 * mappings are removed. any references to nonexistent pages results
1950 * in null mappings (currently treated as "copy-on-access")
1951 */
1952static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1953                        unsigned long addr, unsigned long end,
1954                        unsigned long pfn, pgprot_t prot)
1955{
1956        pte_t *pte;
1957        spinlock_t *ptl;
1958
1959        pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1960        if (!pte)
1961                return -ENOMEM;
1962        arch_enter_lazy_mmu_mode();
1963        do {
1964                BUG_ON(!pte_none(*pte));
1965                set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1966                pfn++;
1967        } while (pte++, addr += PAGE_SIZE, addr != end);
1968        arch_leave_lazy_mmu_mode();
1969        pte_unmap_unlock(pte - 1, ptl);
1970        return 0;
1971}
1972
1973static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1974                        unsigned long addr, unsigned long end,
1975                        unsigned long pfn, pgprot_t prot)
1976{
1977        pmd_t *pmd;
1978        unsigned long next;
1979
1980        pfn -= addr >> PAGE_SHIFT;
1981        pmd = pmd_alloc(mm, pud, addr);
1982        if (!pmd)
1983                return -ENOMEM;
1984        VM_BUG_ON(pmd_trans_huge(*pmd));
1985        do {
1986                next = pmd_addr_end(addr, end);
1987                if (remap_pte_range(mm, pmd, addr, next,
1988                                pfn + (addr >> PAGE_SHIFT), prot))
1989                        return -ENOMEM;
1990        } while (pmd++, addr = next, addr != end);
1991        return 0;
1992}
1993
1994static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1995                        unsigned long addr, unsigned long end,
1996                        unsigned long pfn, pgprot_t prot)
1997{
1998        pud_t *pud;
1999        unsigned long next;
2000
2001        pfn -= addr >> PAGE_SHIFT;
2002        pud = pud_alloc(mm, p4d, addr);
2003        if (!pud)
2004                return -ENOMEM;
2005        do {
2006                next = pud_addr_end(addr, end);
2007                if (remap_pmd_range(mm, pud, addr, next,
2008                                pfn + (addr >> PAGE_SHIFT), prot))
2009                        return -ENOMEM;
2010        } while (pud++, addr = next, addr != end);
2011        return 0;
2012}
2013
2014static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2015                        unsigned long addr, unsigned long end,
2016                        unsigned long pfn, pgprot_t prot)
2017{
2018        p4d_t *p4d;
2019        unsigned long next;
2020
2021        pfn -= addr >> PAGE_SHIFT;
2022        p4d = p4d_alloc(mm, pgd, addr);
2023        if (!p4d)
2024                return -ENOMEM;
2025        do {
2026                next = p4d_addr_end(addr, end);
2027                if (remap_pud_range(mm, p4d, addr, next,
2028                                pfn + (addr >> PAGE_SHIFT), prot))
2029                        return -ENOMEM;
2030        } while (p4d++, addr = next, addr != end);
2031        return 0;
2032}
2033
2034/**
2035 * remap_pfn_range - remap kernel memory to userspace
2036 * @vma: user vma to map to
2037 * @addr: target user address to start at
2038 * @pfn: physical address of kernel memory
2039 * @size: size of map area
2040 * @prot: page protection flags for this mapping
2041 *
2042 *  Note: this is only safe if the mm semaphore is held when called.
2043 */
2044int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2045                    unsigned long pfn, unsigned long size, pgprot_t prot)
2046{
2047        pgd_t *pgd;
2048        unsigned long next;
2049        unsigned long end = addr + PAGE_ALIGN(size);
2050        struct mm_struct *mm = vma->vm_mm;
2051        unsigned long remap_pfn = pfn;
2052        int err;
2053
2054        /*
2055         * Physically remapped pages are special. Tell the
2056         * rest of the world about it:
2057         *   VM_IO tells people not to look at these pages
2058         *      (accesses can have side effects).
2059         *   VM_PFNMAP tells the core MM that the base pages are just
2060         *      raw PFN mappings, and do not have a "struct page" associated
2061         *      with them.
2062         *   VM_DONTEXPAND
2063         *      Disable vma merging and expanding with mremap().
2064         *   VM_DONTDUMP
2065         *      Omit vma from core dump, even when VM_IO turned off.
2066         *
2067         * There's a horrible special case to handle copy-on-write
2068         * behaviour that some programs depend on. We mark the "original"
2069         * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2070         * See vm_normal_page() for details.
2071         */
2072        if (is_cow_mapping(vma->vm_flags)) {
2073                if (addr != vma->vm_start || end != vma->vm_end)
2074                        return -EINVAL;
2075                vma->vm_pgoff = pfn;
2076        }
2077
2078        err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2079        if (err)
2080                return -EINVAL;
2081
2082        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2083
2084        BUG_ON(addr >= end);
2085        pfn -= addr >> PAGE_SHIFT;
2086        pgd = pgd_offset(mm, addr);
2087        flush_cache_range(vma, addr, end);
2088        do {
2089                next = pgd_addr_end(addr, end);
2090                err = remap_p4d_range(mm, pgd, addr, next,
2091                                pfn + (addr >> PAGE_SHIFT), prot);
2092                if (err)
2093                        break;
2094        } while (pgd++, addr = next, addr != end);
2095
2096        if (err)
2097                untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2098
2099        return err;
2100}
2101EXPORT_SYMBOL(remap_pfn_range);
2102
2103/**
2104 * vm_iomap_memory - remap memory to userspace
2105 * @vma: user vma to map to
2106 * @start: start of area
2107 * @len: size of area
2108 *
2109 * This is a simplified io_remap_pfn_range() for common driver use. The
2110 * driver just needs to give us the physical memory range to be mapped,
2111 * we'll figure out the rest from the vma information.
2112 *
2113 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2114 * whatever write-combining details or similar.
2115 */
2116int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2117{
2118        unsigned long vm_len, pfn, pages;
2119
2120        /* Check that the physical memory area passed in looks valid */
2121        if (start + len < start)
2122                return -EINVAL;
2123        /*
2124         * You *really* shouldn't map things that aren't page-aligned,
2125         * but we've historically allowed it because IO memory might
2126         * just have smaller alignment.
2127         */
2128        len += start & ~PAGE_MASK;
2129        pfn = start >> PAGE_SHIFT;
2130        pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2131        if (pfn + pages < pfn)
2132                return -EINVAL;
2133
2134        /* We start the mapping 'vm_pgoff' pages into the area */
2135        if (vma->vm_pgoff > pages)
2136                return -EINVAL;
2137        pfn += vma->vm_pgoff;
2138        pages -= vma->vm_pgoff;
2139
2140        /* Can we fit all of the mapping? */
2141        vm_len = vma->vm_end - vma->vm_start;
2142        if (vm_len >> PAGE_SHIFT > pages)
2143                return -EINVAL;
2144
2145        /* Ok, let it rip */
2146        return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2147}
2148EXPORT_SYMBOL(vm_iomap_memory);
2149
2150static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2151                                     unsigned long addr, unsigned long end,
2152                                     pte_fn_t fn, void *data)
2153{
2154        pte_t *pte;
2155        int err;
2156        pgtable_t token;
2157        spinlock_t *uninitialized_var(ptl);
2158
2159        pte = (mm == &init_mm) ?
2160                pte_alloc_kernel(pmd, addr) :
2161                pte_alloc_map_lock(mm, pmd, addr, &ptl);
2162        if (!pte)
2163                return -ENOMEM;
2164
2165        BUG_ON(pmd_huge(*pmd));
2166
2167        arch_enter_lazy_mmu_mode();
2168
2169        token = pmd_pgtable(*pmd);
2170
2171        do {
2172                err = fn(pte++, token, addr, data);
2173                if (err)
2174                        break;
2175        } while (addr += PAGE_SIZE, addr != end);
2176
2177        arch_leave_lazy_mmu_mode();
2178
2179        if (mm != &init_mm)
2180                pte_unmap_unlock(pte-1, ptl);
2181        return err;
2182}
2183
2184static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2185                                     unsigned long addr, unsigned long end,
2186                                     pte_fn_t fn, void *data)
2187{
2188        pmd_t *pmd;
2189        unsigned long next;
2190        int err;
2191
2192        BUG_ON(pud_huge(*pud));
2193
2194        pmd = pmd_alloc(mm, pud, addr);
2195        if (!pmd)
2196                return -ENOMEM;
2197        do {
2198                next = pmd_addr_end(addr, end);
2199                err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2200                if (err)
2201                        break;
2202        } while (pmd++, addr = next, addr != end);
2203        return err;
2204}
2205
2206static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2207                                     unsigned long addr, unsigned long end,
2208                                     pte_fn_t fn, void *data)
2209{
2210        pud_t *pud;
2211        unsigned long next;
2212        int err;
2213
2214        pud = pud_alloc(mm, p4d, addr);
2215        if (!pud)
2216                return -ENOMEM;
2217        do {
2218                next = pud_addr_end(addr, end);
2219                err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2220                if (err)
2221                        break;
2222        } while (pud++, addr = next, addr != end);
2223        return err;
2224}
2225
2226static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2227                                     unsigned long addr, unsigned long end,
2228                                     pte_fn_t fn, void *data)
2229{
2230        p4d_t *p4d;
2231        unsigned long next;
2232        int err;
2233
2234        p4d = p4d_alloc(mm, pgd, addr);
2235        if (!p4d)
2236                return -ENOMEM;
2237        do {
2238                next = p4d_addr_end(addr, end);
2239                err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2240                if (err)
2241                        break;
2242        } while (p4d++, addr = next, addr != end);
2243        return err;
2244}
2245
2246/*
2247 * Scan a region of virtual memory, filling in page tables as necessary
2248 * and calling a provided function on each leaf page table.
2249 */
2250int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2251                        unsigned long size, pte_fn_t fn, void *data)
2252{
2253        pgd_t *pgd;
2254        unsigned long next;
2255        unsigned long end = addr + size;
2256        int err;
2257
2258        if (WARN_ON(addr >= end))
2259                return -EINVAL;
2260
2261        pgd = pgd_offset(mm, addr);
2262        do {
2263                next = pgd_addr_end(addr, end);
2264                err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2265                if (err)
2266                        break;
2267        } while (pgd++, addr = next, addr != end);
2268
2269        return err;
2270}
2271EXPORT_SYMBOL_GPL(apply_to_page_range);
2272
2273/*
2274 * handle_pte_fault chooses page fault handler according to an entry which was
2275 * read non-atomically.  Before making any commitment, on those architectures
2276 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2277 * parts, do_swap_page must check under lock before unmapping the pte and
2278 * proceeding (but do_wp_page is only called after already making such a check;
2279 * and do_anonymous_page can safely check later on).
2280 */
2281static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2282                                pte_t *page_table, pte_t orig_pte)
2283{
2284        int same = 1;
2285#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2286        if (sizeof(pte_t) > sizeof(unsigned long)) {
2287                spinlock_t *ptl = pte_lockptr(mm, pmd);
2288                spin_lock(ptl);
2289                same = pte_same(*page_table, orig_pte);
2290                spin_unlock(ptl);
2291        }
2292#endif
2293        pte_unmap(page_table);
2294        return same;
2295}
2296
2297static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2298{
2299        debug_dma_assert_idle(src);
2300
2301        /*
2302         * If the source page was a PFN mapping, we don't have
2303         * a "struct page" for it. We do a best-effort copy by
2304         * just copying from the original user address. If that
2305         * fails, we just zero-fill it. Live with it.
2306         */
2307        if (unlikely(!src)) {
2308                void *kaddr = kmap_atomic(dst);
2309                void __user *uaddr = (void __user *)(va & PAGE_MASK);
2310
2311                /*
2312                 * This really shouldn't fail, because the page is there
2313                 * in the page tables. But it might just be unreadable,
2314                 * in which case we just give up and fill the result with
2315                 * zeroes.
2316                 */
2317                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2318                        clear_page(kaddr);
2319                kunmap_atomic(kaddr);
2320                flush_dcache_page(dst);
2321        } else
2322                copy_user_highpage(dst, src, va, vma);
2323}
2324
2325static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2326{
2327        struct file *vm_file = vma->vm_file;
2328
2329        if (vm_file)
2330                return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2331
2332        /*
2333         * Special mappings (e.g. VDSO) do not have any file so fake
2334         * a default GFP_KERNEL for them.
2335         */
2336        return GFP_KERNEL;
2337}
2338
2339/*
2340 * Notify the address space that the page is about to become writable so that
2341 * it can prohibit this or wait for the page to get into an appropriate state.
2342 *
2343 * We do this without the lock held, so that it can sleep if it needs to.
2344 */
2345static int do_page_mkwrite(struct vm_fault *vmf)
2346{
2347        int ret;
2348        struct page *page = vmf->page;
2349        unsigned int old_flags = vmf->flags;
2350
2351        vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2352
2353        ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2354        /* Restore original flags so that caller is not surprised */
2355        vmf->flags = old_flags;
2356        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2357                return ret;
2358        if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2359                lock_page(page);
2360                if (!page->mapping) {
2361                        unlock_page(page);
2362                        return 0; /* retry */
2363                }
2364                ret |= VM_FAULT_LOCKED;
2365        } else
2366                VM_BUG_ON_PAGE(!PageLocked(page), page);
2367        return ret;
2368}
2369
2370/*
2371 * Handle dirtying of a page in shared file mapping on a write fault.
2372 *
2373 * The function expects the page to be locked and unlocks it.
2374 */
2375static void fault_dirty_shared_page(struct vm_area_struct *vma,
2376                                    struct page *page)
2377{
2378        struct address_space *mapping;
2379        bool dirtied;
2380        bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2381
2382        dirtied = set_page_dirty(page);
2383        VM_BUG_ON_PAGE(PageAnon(page), page);
2384        /*
2385         * Take a local copy of the address_space - page.mapping may be zeroed
2386         * by truncate after unlock_page().   The address_space itself remains
2387         * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
2388         * release semantics to prevent the compiler from undoing this copying.
2389         */
2390        mapping = page_rmapping(page);
2391        unlock_page(page);
2392
2393        if ((dirtied || page_mkwrite) && mapping) {
2394                /*
2395                 * Some device drivers do not set page.mapping
2396                 * but still dirty their pages
2397                 */
2398                balance_dirty_pages_ratelimited(mapping);
2399        }
2400
2401        if (!page_mkwrite)
2402                file_update_time(vma->vm_file);
2403}
2404
2405/*
2406 * Handle write page faults for pages that can be reused in the current vma
2407 *
2408 * This can happen either due to the mapping being with the VM_SHARED flag,
2409 * or due to us being the last reference standing to the page. In either
2410 * case, all we need to do here is to mark the page as writable and update
2411 * any related book-keeping.
2412 */
2413static inline void wp_page_reuse(struct vm_fault *vmf)
2414        __releases(vmf->ptl)
2415{
2416        struct vm_area_struct *vma = vmf->vma;
2417        struct page *page = vmf->page;
2418        pte_t entry;
2419        /*
2420         * Clear the pages cpupid information as the existing
2421         * information potentially belongs to a now completely
2422         * unrelated process.
2423         */
2424        if (page)
2425                page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2426
2427        flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2428        entry = pte_mkyoung(vmf->orig_pte);
2429        entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2430        if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2431                update_mmu_cache(vma, vmf->address, vmf->pte);
2432        pte_unmap_unlock(vmf->pte, vmf->ptl);
2433}
2434
2435/*
2436 * Handle the case of a page which we actually need to copy to a new page.
2437 *
2438 * Called with mmap_sem locked and the old page referenced, but
2439 * without the ptl held.
2440 *
2441 * High level logic flow:
2442 *
2443 * - Allocate a page, copy the content of the old page to the new one.
2444 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2445 * - Take the PTL. If the pte changed, bail out and release the allocated page
2446 * - If the pte is still the way we remember it, update the page table and all
2447 *   relevant references. This includes dropping the reference the page-table
2448 *   held to the old page, as well as updating the rmap.
2449 * - In any case, unlock the PTL and drop the reference we took to the old page.
2450 */
2451static int wp_page_copy(struct vm_fault *vmf)
2452{
2453        struct vm_area_struct *vma = vmf->vma;
2454        struct mm_struct *mm = vma->vm_mm;
2455        struct page *old_page = vmf->page;
2456        struct page *new_page = NULL;
2457        pte_t entry;
2458        int page_copied = 0;
2459        const unsigned long mmun_start = vmf->address & PAGE_MASK;
2460        const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2461        struct mem_cgroup *memcg;
2462
2463        if (unlikely(anon_vma_prepare(vma)))
2464                goto oom;
2465
2466        if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2467                new_page = alloc_zeroed_user_highpage_movable(vma,
2468                                                              vmf->address);
2469                if (!new_page)
2470                        goto oom;
2471        } else {
2472                new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2473                                vmf->address);
2474                if (!new_page)
2475                        goto oom;
2476                cow_user_page(new_page, old_page, vmf->address, vma);
2477        }
2478
2479        if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2480                goto oom_free_new;
2481
2482        __SetPageUptodate(new_page);
2483
2484        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2485
2486        /*
2487         * Re-check the pte - we dropped the lock
2488         */
2489        vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2490        if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2491                if (old_page) {
2492                        if (!PageAnon(old_page)) {
2493                                dec_mm_counter_fast(mm,
2494                                                mm_counter_file(old_page));
2495                                inc_mm_counter_fast(mm, MM_ANONPAGES);
2496                        }
2497                } else {
2498                        inc_mm_counter_fast(mm, MM_ANONPAGES);
2499                }
2500                flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2501                entry = mk_pte(new_page, vma->vm_page_prot);
2502                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2503                /*
2504                 * Clear the pte entry and flush it first, before updating the
2505                 * pte with the new entry. This will avoid a race condition
2506                 * seen in the presence of one thread doing SMC and another
2507                 * thread doing COW.
2508                 */
2509                ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2510                page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2511                mem_cgroup_commit_charge(new_page, memcg, false, false);
2512                lru_cache_add_active_or_unevictable(new_page, vma);
2513                /*
2514                 * We call the notify macro here because, when using secondary
2515                 * mmu page tables (such as kvm shadow page tables), we want the
2516                 * new page to be mapped directly into the secondary page table.
2517                 */
2518                set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2519                update_mmu_cache(vma, vmf->address, vmf->pte);
2520                if (old_page) {
2521                        /*
2522                         * Only after switching the pte to the new page may
2523                         * we remove the mapcount here. Otherwise another
2524                         * process may come and find the rmap count decremented
2525                         * before the pte is switched to the new page, and
2526                         * "reuse" the old page writing into it while our pte
2527                         * here still points into it and can be read by other
2528                         * threads.
2529                         *
2530                         * The critical issue is to order this
2531                         * page_remove_rmap with the ptp_clear_flush above.
2532                         * Those stores are ordered by (if nothing else,)
2533                         * the barrier present in the atomic_add_negative
2534                         * in page_remove_rmap.
2535                         *
2536                         * Then the TLB flush in ptep_clear_flush ensures that
2537                         * no process can access the old page before the
2538                         * decremented mapcount is visible. And the old page
2539                         * cannot be reused until after the decremented
2540                         * mapcount is visible. So transitively, TLBs to
2541                         * old page will be flushed before it can be reused.
2542                         */
2543                        page_remove_rmap(old_page, false);
2544                }
2545
2546                /* Free the old page.. */
2547                new_page = old_page;
2548                page_copied = 1;
2549        } else {
2550                mem_cgroup_cancel_charge(new_page, memcg, false);
2551        }
2552
2553        if (new_page)
2554                put_page(new_page);
2555
2556        pte_unmap_unlock(vmf->pte, vmf->ptl);
2557        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2558        if (old_page) {
2559                /*
2560                 * Don't let another task, with possibly unlocked vma,
2561                 * keep the mlocked page.
2562                 */
2563                if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2564                        lock_page(old_page);    /* LRU manipulation */
2565                        if (PageMlocked(old_page))
2566                                munlock_vma_page(old_page);
2567                        unlock_page(old_page);
2568                }
2569                put_page(old_page);
2570        }
2571        return page_copied ? VM_FAULT_WRITE : 0;
2572oom_free_new:
2573        put_page(new_page);
2574oom:
2575        if (old_page)
2576                put_page(old_page);
2577        return VM_FAULT_OOM;
2578}
2579
2580/**
2581 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2582 *                        writeable once the page is prepared
2583 *
2584 * @vmf: structure describing the fault
2585 *
2586 * This function handles all that is needed to finish a write page fault in a
2587 * shared mapping due to PTE being read-only once the mapped page is prepared.
2588 * It handles locking of PTE and modifying it. The function returns
2589 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2590 * lock.
2591 *
2592 * The function expects the page to be locked or other protection against
2593 * concurrent faults / writeback (such as DAX radix tree locks).
2594 */
2595int finish_mkwrite_fault(struct vm_fault *vmf)
2596{
2597        WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2598        vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2599                                       &vmf->ptl);
2600        /*
2601         * We might have raced with another page fault while we released the
2602         * pte_offset_map_lock.
2603         */
2604        if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2605                pte_unmap_unlock(vmf->pte, vmf->ptl);
2606                return VM_FAULT_NOPAGE;
2607        }
2608        wp_page_reuse(vmf);
2609        return 0;
2610}
2611
2612/*
2613 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2614 * mapping
2615 */
2616static int wp_pfn_shared(struct vm_fault *vmf)
2617{
2618        struct vm_area_struct *vma = vmf->vma;
2619
2620        if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2621                int ret;
2622
2623                pte_unmap_unlock(vmf->pte, vmf->ptl);
2624                vmf->flags |= FAULT_FLAG_MKWRITE;
2625                ret = vma->vm_ops->pfn_mkwrite(vmf);
2626                if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2627                        return ret;
2628                return finish_mkwrite_fault(vmf);
2629        }
2630        wp_page_reuse(vmf);
2631        return VM_FAULT_WRITE;
2632}
2633
2634static int wp_page_shared(struct vm_fault *vmf)
2635        __releases(vmf->ptl)
2636{
2637        struct vm_area_struct *vma = vmf->vma;
2638
2639        get_page(vmf->page);
2640
2641        if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2642                int tmp;
2643
2644                pte_unmap_unlock(vmf->pte, vmf->ptl);
2645                tmp = do_page_mkwrite(vmf);
2646                if (unlikely(!tmp || (tmp &
2647                                      (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2648                        put_page(vmf->page);
2649                        return tmp;
2650                }
2651                tmp = finish_mkwrite_fault(vmf);
2652                if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2653                        unlock_page(vmf->page);
2654                        put_page(vmf->page);
2655                        return tmp;
2656                }
2657        } else {
2658                wp_page_reuse(vmf);
2659                lock_page(vmf->page);
2660        }
2661        fault_dirty_shared_page(vma, vmf->page);
2662        put_page(vmf->page);
2663
2664        return VM_FAULT_WRITE;
2665}
2666
2667/*
2668 * This routine handles present pages, when users try to write
2669 * to a shared page. It is done by copying the page to a new address
2670 * and decrementing the shared-page counter for the old page.
2671 *
2672 * Note that this routine assumes that the protection checks have been
2673 * done by the caller (the low-level page fault routine in most cases).
2674 * Thus we can safely just mark it writable once we've done any necessary
2675 * COW.
2676 *
2677 * We also mark the page dirty at this point even though the page will
2678 * change only once the write actually happens. This avoids a few races,
2679 * and potentially makes it more efficient.
2680 *
2681 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2682 * but allow concurrent faults), with pte both mapped and locked.
2683 * We return with mmap_sem still held, but pte unmapped and unlocked.
2684 */
2685static int do_wp_page(struct vm_fault *vmf)
2686        __releases(vmf->ptl)
2687{
2688        struct vm_area_struct *vma = vmf->vma;
2689
2690        vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2691        if (!vmf->page) {
2692                /*
2693                 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2694                 * VM_PFNMAP VMA.
2695                 *
2696                 * We should not cow pages in a shared writeable mapping.
2697                 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2698                 */
2699                if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2700                                     (VM_WRITE|VM_SHARED))
2701                        return wp_pfn_shared(vmf);
2702
2703                pte_unmap_unlock(vmf->pte, vmf->ptl);
2704                return wp_page_copy(vmf);
2705        }
2706
2707        /*
2708         * Take out anonymous pages first, anonymous shared vmas are
2709         * not dirty accountable.
2710         */
2711        if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2712                int total_map_swapcount;
2713                if (!trylock_page(vmf->page)) {
2714                        get_page(vmf->page);
2715                        pte_unmap_unlock(vmf->pte, vmf->ptl);
2716                        lock_page(vmf->page);
2717                        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2718                                        vmf->address, &vmf->ptl);
2719                        if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2720                                unlock_page(vmf->page);
2721                                pte_unmap_unlock(vmf->pte, vmf->ptl);
2722                                put_page(vmf->page);
2723                                return 0;
2724                        }
2725                        put_page(vmf->page);
2726                }
2727                if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2728                        if (total_map_swapcount == 1) {
2729                                /*
2730                                 * The page is all ours. Move it to
2731                                 * our anon_vma so the rmap code will
2732                                 * not search our parent or siblings.
2733                                 * Protected against the rmap code by
2734                                 * the page lock.
2735                                 */
2736                                page_move_anon_rmap(vmf->page, vma);
2737                        }
2738                        unlock_page(vmf->page);
2739                        wp_page_reuse(vmf);
2740                        return VM_FAULT_WRITE;
2741                }
2742                unlock_page(vmf->page);
2743        } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2744                                        (VM_WRITE|VM_SHARED))) {
2745                return wp_page_shared(vmf);
2746        }
2747
2748        /*
2749         * Ok, we need to copy. Oh, well..
2750         */
2751        get_page(vmf->page);
2752
2753        pte_unmap_unlock(vmf->pte, vmf->ptl);
2754        return wp_page_copy(vmf);
2755}
2756
2757static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2758                unsigned long start_addr, unsigned long end_addr,
2759                struct zap_details *details)
2760{
2761        zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2762}
2763
2764static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2765                                            struct zap_details *details)
2766{
2767        struct vm_area_struct *vma;
2768        pgoff_t vba, vea, zba, zea;
2769
2770        vma_interval_tree_foreach(vma, root,
2771                        details->first_index, details->last_index) {
2772
2773                vba = vma->vm_pgoff;
2774                vea = vba + vma_pages(vma) - 1;
2775                zba = details->first_index;
2776                if (zba < vba)
2777                        zba = vba;
2778                zea = details->last_index;
2779                if (zea > vea)
2780                        zea = vea;
2781
2782                unmap_mapping_range_vma(vma,
2783                        ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2784                        ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2785                                details);
2786        }
2787}
2788
2789/**
2790 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2791 * address_space corresponding to the specified page range in the underlying
2792 * file.
2793 *
2794 * @mapping: the address space containing mmaps to be unmapped.
2795 * @holebegin: byte in first page to unmap, relative to the start of
2796 * the underlying file.  This will be rounded down to a PAGE_SIZE
2797 * boundary.  Note that this is different from truncate_pagecache(), which
2798 * must keep the partial page.  In contrast, we must get rid of
2799 * partial pages.
2800 * @holelen: size of prospective hole in bytes.  This will be rounded
2801 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2802 * end of the file.
2803 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2804 * but 0 when invalidating pagecache, don't throw away private data.
2805 */
2806void unmap_mapping_range(struct address_space *mapping,
2807                loff_t const holebegin, loff_t const holelen, int even_cows)
2808{
2809        struct zap_details details = { };
2810        pgoff_t hba = holebegin >> PAGE_SHIFT;
2811        pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2812
2813        /* Check for overflow. */
2814        if (sizeof(holelen) > sizeof(hlen)) {
2815                long long holeend =
2816                        (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2817                if (holeend & ~(long long)ULONG_MAX)
2818                        hlen = ULONG_MAX - hba + 1;
2819        }
2820
2821        details.check_mapping = even_cows ? NULL : mapping;
2822        details.first_index = hba;
2823        details.last_index = hba + hlen - 1;
2824        if (details.last_index < details.first_index)
2825                details.last_index = ULONG_MAX;
2826
2827        i_mmap_lock_write(mapping);
2828        if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2829                unmap_mapping_range_tree(&mapping->i_mmap, &details);
2830        i_mmap_unlock_write(mapping);
2831}
2832EXPORT_SYMBOL(unmap_mapping_range);
2833
2834/*
2835 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2836 * but allow concurrent faults), and pte mapped but not yet locked.
2837 * We return with pte unmapped and unlocked.
2838 *
2839 * We return with the mmap_sem locked or unlocked in the same cases
2840 * as does filemap_fault().
2841 */
2842int do_swap_page(struct vm_fault *vmf)
2843{
2844        struct vm_area_struct *vma = vmf->vma;
2845        struct page *page = NULL, *swapcache;
2846        struct mem_cgroup *memcg;
2847        struct vma_swap_readahead swap_ra;
2848        swp_entry_t entry;
2849        pte_t pte;
2850        int locked;
2851        int exclusive = 0;
2852        int ret = 0;
2853        bool vma_readahead = swap_use_vma_readahead();
2854
2855        if (vma_readahead)
2856                page = swap_readahead_detect(vmf, &swap_ra);
2857        if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) {
2858                if (page)
2859                        put_page(page);
2860                goto out;
2861        }
2862
2863        entry = pte_to_swp_entry(vmf->orig_pte);
2864        if (unlikely(non_swap_entry(entry))) {
2865                if (is_migration_entry(entry)) {
2866                        migration_entry_wait(vma->vm_mm, vmf->pmd,
2867                                             vmf->address);
2868                } else if (is_device_private_entry(entry)) {
2869                        /*
2870                         * For un-addressable device memory we call the pgmap
2871                         * fault handler callback. The callback must migrate
2872                         * the page back to some CPU accessible page.
2873                         */
2874                        ret = device_private_entry_fault(vma, vmf->address, entry,
2875                                                 vmf->flags, vmf->pmd);
2876                } else if (is_hwpoison_entry(entry)) {
2877                        ret = VM_FAULT_HWPOISON;
2878                } else {
2879                        print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2880                        ret = VM_FAULT_SIGBUS;
2881                }
2882                goto out;
2883        }
2884        delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2885        if (!page)
2886                page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
2887                                         vmf->address);
2888        if (!page) {
2889                if (vma_readahead)
2890                        page = do_swap_page_readahead(entry,
2891                                GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
2892                else
2893                        page = swapin_readahead(entry,
2894                                GFP_HIGHUSER_MOVABLE, vma, vmf->address);
2895                if (!page) {
2896                        /*
2897                         * Back out if somebody else faulted in this pte
2898                         * while we released the pte lock.
2899                         */
2900                        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2901                                        vmf->address, &vmf->ptl);
2902                        if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2903                                ret = VM_FAULT_OOM;
2904                        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2905                        goto unlock;
2906                }
2907
2908                /* Had to read the page from swap area: Major fault */
2909                ret = VM_FAULT_MAJOR;
2910                count_vm_event(PGMAJFAULT);
2911                count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2912        } else if (PageHWPoison(page)) {
2913                /*
2914                 * hwpoisoned dirty swapcache pages are kept for killing
2915                 * owner processes (which may be unknown at hwpoison time)
2916                 */
2917                ret = VM_FAULT_HWPOISON;
2918                delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2919                swapcache = page;
2920                goto out_release;
2921        }
2922
2923        swapcache = page;
2924        locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2925
2926        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2927        if (!locked) {
2928                ret |= VM_FAULT_RETRY;
2929                goto out_release;
2930        }
2931
2932        /*
2933         * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2934         * release the swapcache from under us.  The page pin, and pte_same
2935         * test below, are not enough to exclude that.  Even if it is still
2936         * swapcache, we need to check that the page's swap has not changed.
2937         */
2938        if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2939                goto out_page;
2940
2941        page = ksm_might_need_to_copy(page, vma, vmf->address);
2942        if (unlikely(!page)) {
2943                ret = VM_FAULT_OOM;
2944                page = swapcache;
2945                goto out_page;
2946        }
2947
2948        if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2949                                &memcg, false)) {
2950                ret = VM_FAULT_OOM;
2951                goto out_page;
2952        }
2953
2954        /*
2955         * Back out if somebody else already faulted in this pte.
2956         */
2957        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2958                        &vmf->ptl);
2959        if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2960                goto out_nomap;
2961
2962        if (unlikely(!PageUptodate(page))) {
2963                ret = VM_FAULT_SIGBUS;
2964                goto out_nomap;
2965        }
2966
2967        /*
2968         * The page isn't present yet, go ahead with the fault.
2969         *
2970         * Be careful about the sequence of operations here.
2971         * To get its accounting right, reuse_swap_page() must be called
2972         * while the page is counted on swap but not yet in mapcount i.e.
2973         * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2974         * must be called after the swap_free(), or it will never succeed.
2975         */
2976
2977        inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2978        dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2979        pte = mk_pte(page, vma->vm_page_prot);
2980        if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2981                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2982                vmf->flags &= ~FAULT_FLAG_WRITE;
2983                ret |= VM_FAULT_WRITE;
2984                exclusive = RMAP_EXCLUSIVE;
2985        }
2986        flush_icache_page(vma, page);
2987        if (pte_swp_soft_dirty(vmf->orig_pte))
2988                pte = pte_mksoft_dirty(pte);
2989        set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2990        vmf->orig_pte = pte;
2991        if (page == swapcache) {
2992                do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2993                mem_cgroup_commit_charge(page, memcg, true, false);
2994                activate_page(page);
2995        } else { /* ksm created a completely new copy */
2996                page_add_new_anon_rmap(page, vma, vmf->address, false);
2997                mem_cgroup_commit_charge(page, memcg, false, false);
2998                lru_cache_add_active_or_unevictable(page, vma);
2999        }
3000
3001        swap_free(entry);
3002        if (mem_cgroup_swap_full(page) ||
3003            (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3004                try_to_free_swap(page);
3005        unlock_page(page);
3006        if (page != swapcache) {
3007                /*
3008                 * Hold the lock to avoid the swap entry to be reused
3009                 * until we take the PT lock for the pte_same() check
3010                 * (to avoid false positives from pte_same). For
3011                 * further safety release the lock after the swap_free
3012                 * so that the swap count won't change under a
3013                 * parallel locked swapcache.
3014                 */
3015                unlock_page(swapcache);
3016                put_page(swapcache);
3017        }
3018
3019        if (vmf->flags & FAULT_FLAG_WRITE) {
3020                ret |= do_wp_page(vmf);
3021                if (ret & VM_FAULT_ERROR)
3022                        ret &= VM_FAULT_ERROR;
3023                goto out;
3024        }
3025
3026        /* No need to invalidate - it was non-present before */
3027        update_mmu_cache(vma, vmf->address, vmf->pte);
3028unlock:
3029        pte_unmap_unlock(vmf->pte, vmf->ptl);
3030out:
3031        return ret;
3032out_nomap:
3033        mem_cgroup_cancel_charge(page, memcg, false);
3034        pte_unmap_unlock(vmf->pte, vmf->ptl);
3035out_page:
3036        unlock_page(page);
3037out_release:
3038        put_page(page);
3039        if (page != swapcache) {
3040                unlock_page(swapcache);
3041                put_page(swapcache);
3042        }
3043        return ret;
3044}
3045
3046/*
3047 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3048 * but allow concurrent faults), and pte mapped but not yet locked.
3049 * We return with mmap_sem still held, but pte unmapped and unlocked.
3050 */
3051static int do_anonymous_page(struct vm_fault *vmf)
3052{
3053        struct vm_area_struct *vma = vmf->vma;
3054        struct mem_cgroup *memcg;
3055        struct page *page;
3056        int ret = 0;
3057        pte_t entry;
3058
3059        /* File mapping without ->vm_ops ? */
3060        if (vma->vm_flags & VM_SHARED)
3061                return VM_FAULT_SIGBUS;
3062
3063        /*
3064         * Use pte_alloc() instead of pte_alloc_map().  We can't run
3065         * pte_offset_map() on pmds where a huge pmd might be created
3066         * from a different thread.
3067         *
3068         * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
3069         * parallel threads are excluded by other means.
3070         *
3071         * Here we only have down_read(mmap_sem).
3072         */
3073        if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
3074                return VM_FAULT_OOM;
3075
3076        /* See the comment in pte_alloc_one_map() */
3077        if (unlikely(pmd_trans_unstable(vmf->pmd)))
3078                return 0;
3079
3080        /* Use the zero-page for reads */
3081        if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3082                        !mm_forbids_zeropage(vma->vm_mm)) {
3083                entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3084                                                vma->vm_page_prot));
3085                vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3086                                vmf->address, &vmf->ptl);
3087                if (!pte_none(*vmf->pte))
3088                        goto unlock;
3089                ret = check_stable_address_space(vma->vm_mm);
3090                if (ret)
3091                        goto unlock;
3092                /* Deliver the page fault to userland, check inside PT lock */
3093                if (userfaultfd_missing(vma)) {
3094                        pte_unmap_unlock(vmf->pte, vmf->ptl);
3095                        return handle_userfault(vmf, VM_UFFD_MISSING);
3096                }
3097                goto setpte;
3098        }
3099
3100        /* Allocate our own private page. */
3101        if (unlikely(anon_vma_prepare(vma)))
3102                goto oom;
3103        page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3104        if (!page)
3105                goto oom;
3106
3107        if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
3108                goto oom_free_page;
3109
3110        /*
3111         * The memory barrier inside __SetPageUptodate makes sure that
3112         * preceeding stores to the page contents become visible before
3113         * the set_pte_at() write.
3114         */
3115        __SetPageUptodate(page);
3116
3117        entry = mk_pte(page, vma->vm_page_prot);
3118        if (vma->vm_flags & VM_WRITE)
3119                entry = pte_mkwrite(pte_mkdirty(entry));
3120
3121        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3122                        &vmf->ptl);
3123        if (!pte_none(*vmf->pte))
3124                goto release;
3125
3126        ret = check_stable_address_space(vma->vm_mm);
3127        if (ret)
3128                goto release;
3129
3130        /* Deliver the page fault to userland, check inside PT lock */
3131        if (userfaultfd_missing(vma)) {
3132                pte_unmap_unlock(vmf->pte, vmf->ptl);
3133                mem_cgroup_cancel_charge(page, memcg, false);
3134                put_page(page);
3135                return handle_userfault(vmf, VM_UFFD_MISSING);
3136        }
3137
3138        inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3139        page_add_new_anon_rmap(page, vma, vmf->address, false);
3140        mem_cgroup_commit_charge(page, memcg, false, false);
3141        lru_cache_add_active_or_unevictable(page, vma);
3142setpte:
3143        set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3144
3145        /* No need to invalidate - it was non-present before */
3146        update_mmu_cache(vma, vmf->address, vmf->pte);
3147unlock:
3148        pte_unmap_unlock(vmf->pte, vmf->ptl);
3149        return ret;
3150release:
3151        mem_cgroup_cancel_charge(page, memcg, false);
3152        put_page(page);
3153        goto unlock;
3154oom_free_page:
3155        put_page(page);
3156oom:
3157        return VM_FAULT_OOM;
3158}
3159
3160/*
3161 * The mmap_sem must have been held on entry, and may have been
3162 * released depending on flags and vma->vm_ops->fault() return value.
3163 * See filemap_fault() and __lock_page_retry().
3164 */
3165static int __do_fault(struct vm_fault *vmf)
3166{
3167        struct vm_area_struct *vma = vmf->vma;
3168        int ret;
3169
3170        ret = vma->vm_ops->fault(vmf);
3171        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3172                            VM_FAULT_DONE_COW)))
3173                return ret;
3174
3175        if (unlikely(PageHWPoison(vmf->page))) {
3176                if (ret & VM_FAULT_LOCKED)
3177                        unlock_page(vmf->page);
3178                put_page(vmf->page);
3179                vmf->page = NULL;
3180                return VM_FAULT_HWPOISON;
3181        }
3182
3183        if (unlikely(!(ret & VM_FAULT_LOCKED)))
3184                lock_page(vmf->page);
3185        else
3186                VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3187
3188        return ret;
3189}
3190
3191/*
3192 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3193 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3194 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3195 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3196 */
3197static int pmd_devmap_trans_unstable(pmd_t *pmd)
3198{
3199        return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3200}
3201
3202static int pte_alloc_one_map(struct vm_fault *vmf)
3203{
3204        struct vm_area_struct *vma = vmf->vma;
3205
3206        if (!pmd_none(*vmf->pmd))
3207                goto map_pte;
3208        if (vmf->prealloc_pte) {
3209                vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3210                if (unlikely(!pmd_none(*vmf->pmd))) {
3211                        spin_unlock(vmf->ptl);
3212                        goto map_pte;
3213                }
3214
3215                atomic_long_inc(&vma->vm_mm->nr_ptes);
3216                pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3217                spin_unlock(vmf->ptl);
3218                vmf->prealloc_pte = NULL;
3219        } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3220                return VM_FAULT_OOM;
3221        }
3222map_pte:
3223        /*
3224         * If a huge pmd materialized under us just retry later.  Use
3225         * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3226         * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3227         * under us and then back to pmd_none, as a result of MADV_DONTNEED
3228         * running immediately after a huge pmd fault in a different thread of
3229         * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3230         * All we have to ensure is that it is a regular pmd that we can walk
3231         * with pte_offset_map() and we can do that through an atomic read in
3232         * C, which is what pmd_trans_unstable() provides.
3233         */
3234        if (pmd_devmap_trans_unstable(vmf->pmd))
3235                return VM_FAULT_NOPAGE;
3236
3237        /*
3238         * At this point we know that our vmf->pmd points to a page of ptes
3239         * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3240         * for the duration of the fault.  If a racing MADV_DONTNEED runs and
3241         * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3242         * be valid and we will re-check to make sure the vmf->pte isn't
3243         * pte_none() under vmf->ptl protection when we return to
3244         * alloc_set_pte().
3245         */
3246        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3247                        &vmf->ptl);
3248        return 0;
3249}
3250
3251#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3252
3253#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3254static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3255                unsigned long haddr)
3256{
3257        if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3258                        (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3259                return false;
3260        if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3261                return false;
3262        return true;
3263}
3264
3265static void deposit_prealloc_pte(struct vm_fault *vmf)
3266{
3267        struct vm_area_struct *vma = vmf->vma;
3268
3269        pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3270        /*
3271         * We are going to consume the prealloc table,
3272         * count that as nr_ptes.
3273         */
3274        atomic_long_inc(&vma->vm_mm->nr_ptes);
3275        vmf->prealloc_pte = NULL;
3276}
3277
3278static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3279{
3280        struct vm_area_struct *vma = vmf->vma;
3281        bool write = vmf->flags & FAULT_FLAG_WRITE;
3282        unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3283        pmd_t entry;
3284        int i, ret;
3285
3286        if (!transhuge_vma_suitable(vma, haddr))
3287                return VM_FAULT_FALLBACK;
3288
3289        ret = VM_FAULT_FALLBACK;
3290        page = compound_head(page);
3291
3292        /*
3293         * Archs like ppc64 need additonal space to store information
3294         * related to pte entry. Use the preallocated table for that.
3295         */
3296        if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3297                vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3298                if (!vmf->prealloc_pte)
3299                        return VM_FAULT_OOM;
3300                smp_wmb(); /* See comment in __pte_alloc() */
3301        }
3302
3303        vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3304        if (unlikely(!pmd_none(*vmf->pmd)))
3305                goto out;
3306
3307        for (i = 0; i < HPAGE_PMD_NR; i++)
3308                flush_icache_page(vma, page + i);
3309
3310        entry = mk_huge_pmd(page, vma->vm_page_prot);
3311        if (write)
3312                entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3313
3314        add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3315        page_add_file_rmap(page, true);
3316        /*
3317         * deposit and withdraw with pmd lock held
3318         */
3319        if (arch_needs_pgtable_deposit())
3320                deposit_prealloc_pte(vmf);
3321
3322        set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3323
3324        update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3325
3326        /* fault is handled */
3327        ret = 0;
3328        count_vm_event(THP_FILE_MAPPED);
3329out:
3330        spin_unlock(vmf->ptl);
3331        return ret;
3332}
3333#else
3334static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3335{
3336        BUILD_BUG();
3337        return 0;
3338}
3339#endif
3340
3341/**
3342 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3343 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3344 *
3345 * @vmf: fault environment
3346 * @memcg: memcg to charge page (only for private mappings)
3347 * @page: page to map
3348 *
3349 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3350 * return.
3351 *
3352 * Target users are page handler itself and implementations of
3353 * vm_ops->map_pages.
3354 */
3355int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3356                struct page *page)
3357{
3358        struct vm_area_struct *vma = vmf->vma;
3359        bool write = vmf->flags & FAULT_FLAG_WRITE;
3360        pte_t entry;
3361        int ret;
3362
3363        if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3364                        IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3365                /* THP on COW? */
3366                VM_BUG_ON_PAGE(memcg, page);
3367
3368                ret = do_set_pmd(vmf, page);
3369                if (ret != VM_FAULT_FALLBACK)
3370                        return ret;
3371        }
3372
3373        if (!vmf->pte) {
3374                ret = pte_alloc_one_map(vmf);
3375                if (ret)
3376                        return ret;
3377        }
3378
3379        /* Re-check under ptl */
3380        if (unlikely(!pte_none(*vmf->pte)))
3381                return VM_FAULT_NOPAGE;
3382
3383        flush_icache_page(vma, page);
3384        entry = mk_pte(page, vma->vm_page_prot);
3385        if (write)
3386                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3387        /* copy-on-write page */
3388        if (write && !(vma->vm_flags & VM_SHARED)) {
3389                inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3390                page_add_new_anon_rmap(page, vma, vmf->address, false);
3391                mem_cgroup_commit_charge(page, memcg, false, false);
3392                lru_cache_add_active_or_unevictable(page, vma);
3393        } else {
3394                inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3395                page_add_file_rmap(page, false);
3396        }
3397        set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3398
3399        /* no need to invalidate: a not-present page won't be cached */
3400        update_mmu_cache(vma, vmf->address, vmf->pte);
3401
3402        return 0;
3403}
3404
3405
3406/**
3407 * finish_fault - finish page fault once we have prepared the page to fault
3408 *
3409 * @vmf: structure describing the fault
3410 *
3411 * This function handles all that is needed to finish a page fault once the
3412 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3413 * given page, adds reverse page mapping, handles memcg charges and LRU
3414 * addition. The function returns 0 on success, VM_FAULT_ code in case of
3415 * error.
3416 *
3417 * The function expects the page to be locked and on success it consumes a
3418 * reference of a page being mapped (for the PTE which maps it).
3419 */
3420int finish_fault(struct vm_fault *vmf)
3421{
3422        struct page *page;
3423        int ret = 0;
3424
3425        /* Did we COW the page? */
3426        if ((vmf->flags & FAULT_FLAG_WRITE) &&
3427            !(vmf->vma->vm_flags & VM_SHARED))
3428                page = vmf->cow_page;
3429        else
3430                page = vmf->page;
3431
3432        /*
3433         * check even for read faults because we might have lost our CoWed
3434         * page
3435         */
3436        if (!(vmf->vma->vm_flags & VM_SHARED))
3437                ret = check_stable_address_space(vmf->vma->vm_mm);
3438        if (!ret)
3439                ret = alloc_set_pte(vmf, vmf->memcg, page);
3440        if (vmf->pte)
3441                pte_unmap_unlock(vmf->pte, vmf->ptl);
3442        return ret;
3443}
3444
3445static unsigned long fault_around_bytes __read_mostly =
3446        rounddown_pow_of_two(65536);
3447
3448#ifdef CONFIG_DEBUG_FS
3449static int fault_around_bytes_get(void *data, u64 *val)
3450{
3451        *val = fault_around_bytes;
3452        return 0;
3453}
3454
3455/*
3456 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3457 * rounded down to nearest page order. It's what do_fault_around() expects to
3458 * see.
3459 */
3460static int fault_around_bytes_set(void *data, u64 val)
3461{
3462        if (val / PAGE_SIZE > PTRS_PER_PTE)
3463                return -EINVAL;
3464        if (val > PAGE_SIZE)
3465                fault_around_bytes = rounddown_pow_of_two(val);
3466        else
3467                fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3468        return 0;
3469}
3470DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3471                fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3472
3473static int __init fault_around_debugfs(void)
3474{
3475        void *ret;
3476
3477        ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3478                        &fault_around_bytes_fops);
3479        if (!ret)
3480                pr_warn("Failed to create fault_around_bytes in debugfs");
3481        return 0;
3482}
3483late_initcall(fault_around_debugfs);
3484#endif
3485
3486/*
3487 * do_fault_around() tries to map few pages around the fault address. The hope
3488 * is that the pages will be needed soon and this will lower the number of
3489 * faults to handle.
3490 *
3491 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3492 * not ready to be mapped: not up-to-date, locked, etc.
3493 *
3494 * This function is called with the page table lock taken. In the split ptlock
3495 * case the page table lock only protects only those entries which belong to
3496 * the page table corresponding to the fault address.
3497 *
3498 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3499 * only once.
3500 *
3501 * fault_around_pages() defines how many pages we'll try to map.
3502 * do_fault_around() expects it to return a power of two less than or equal to
3503 * PTRS_PER_PTE.
3504 *
3505 * The virtual address of the area that we map is naturally aligned to the
3506 * fault_around_pages() value (and therefore to page order).  This way it's
3507 * easier to guarantee that we don't cross page table boundaries.
3508 */
3509static int do_fault_around(struct vm_fault *vmf)
3510{
3511        unsigned long address = vmf->address, nr_pages, mask;
3512        pgoff_t start_pgoff = vmf->pgoff;
3513        pgoff_t end_pgoff;
3514        int off, ret = 0;
3515
3516        nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3517        mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3518
3519        vmf->address = max(address & mask, vmf->vma->vm_start);
3520        off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3521        start_pgoff -= off;
3522
3523        /*
3524         *  end_pgoff is either end of page table or end of vma
3525         *  or fault_around_pages() from start_pgoff, depending what is nearest.
3526         */
3527        end_pgoff = start_pgoff -
3528                ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3529                PTRS_PER_PTE - 1;
3530        end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3531                        start_pgoff + nr_pages - 1);
3532
3533        if (pmd_none(*vmf->pmd)) {
3534                vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3535                                                  vmf->address);
3536                if (!vmf->prealloc_pte)
3537                        goto out;
3538                smp_wmb(); /* See comment in __pte_alloc() */
3539        }
3540
3541        vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3542
3543        /* Huge page is mapped? Page fault is solved */
3544        if (pmd_trans_huge(*vmf->pmd)) {
3545                ret = VM_FAULT_NOPAGE;
3546                goto out;
3547        }
3548
3549        /* ->map_pages() haven't done anything useful. Cold page cache? */
3550        if (!vmf->pte)
3551                goto out;
3552
3553        /* check if the page fault is solved */
3554        vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3555        if (!pte_none(*vmf->pte))
3556                ret = VM_FAULT_NOPAGE;
3557        pte_unmap_unlock(vmf->pte, vmf->ptl);
3558out:
3559        vmf->address = address;
3560        vmf->pte = NULL;
3561        return ret;
3562}
3563
3564static int do_read_fault(struct vm_fault *vmf)
3565{
3566        struct vm_area_struct *vma = vmf->vma;
3567        int ret = 0;
3568
3569        /*
3570         * Let's call ->map_pages() first and use ->fault() as fallback
3571         * if page by the offset is not ready to be mapped (cold cache or
3572         * something).
3573         */
3574        if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3575                ret = do_fault_around(vmf);
3576                if (ret)
3577                        return ret;
3578        }
3579
3580        ret = __do_fault(vmf);
3581        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3582                return ret;
3583
3584        ret |= finish_fault(vmf);
3585        unlock_page(vmf->page);
3586        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3587                put_page(vmf->page);
3588        return ret;
3589}
3590
3591static int do_cow_fault(struct vm_fault *vmf)
3592{
3593        struct vm_area_struct *vma = vmf->vma;
3594        int ret;
3595
3596        if (unlikely(anon_vma_prepare(vma)))
3597                return VM_FAULT_OOM;
3598
3599        vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3600        if (!vmf->cow_page)
3601                return VM_FAULT_OOM;
3602
3603        if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3604                                &vmf->memcg, false)) {
3605                put_page(vmf->cow_page);
3606                return VM_FAULT_OOM;
3607        }
3608
3609        ret = __do_fault(vmf);
3610        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3611                goto uncharge_out;
3612        if (ret & VM_FAULT_DONE_COW)
3613                return ret;
3614
3615        copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3616        __SetPageUptodate(vmf->cow_page);
3617
3618        ret |= finish_fault(vmf);
3619        unlock_page(vmf->page);
3620        put_page(vmf->page);
3621        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3622                goto uncharge_out;
3623        return ret;
3624uncharge_out:
3625        mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3626        put_page(vmf->cow_page);
3627        return ret;
3628}
3629
3630static int do_shared_fault(struct vm_fault *vmf)
3631{
3632        struct vm_area_struct *vma = vmf->vma;
3633        int ret, tmp;
3634
3635        ret = __do_fault(vmf);
3636        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3637                return ret;
3638
3639        /*
3640         * Check if the backing address space wants to know that the page is
3641         * about to become writable
3642         */
3643        if (vma->vm_ops->page_mkwrite) {
3644                unlock_page(vmf->page);
3645                tmp = do_page_mkwrite(vmf);
3646                if (unlikely(!tmp ||
3647                                (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3648                        put_page(vmf->page);
3649                        return tmp;
3650                }
3651        }
3652
3653        ret |= finish_fault(vmf);
3654        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3655                                        VM_FAULT_RETRY))) {
3656                unlock_page(vmf->page);
3657                put_page(vmf->page);
3658                return ret;
3659        }
3660
3661        fault_dirty_shared_page(vma, vmf->page);
3662        return ret;
3663}
3664
3665/*
3666 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3667 * but allow concurrent faults).
3668 * The mmap_sem may have been released depending on flags and our
3669 * return value.  See filemap_fault() and __lock_page_or_retry().
3670 */
3671static int do_fault(struct vm_fault *vmf)
3672{
3673        struct vm_area_struct *vma = vmf->vma;
3674        int ret;
3675
3676        /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3677        if (!vma->vm_ops->fault)
3678                ret = VM_FAULT_SIGBUS;
3679        else if (!(vmf->flags & FAULT_FLAG_WRITE))
3680                ret = do_read_fault(vmf);
3681        else if (!(vma->vm_flags & VM_SHARED))
3682                ret = do_cow_fault(vmf);
3683        else
3684                ret = do_shared_fault(vmf);
3685
3686        /* preallocated pagetable is unused: free it */
3687        if (vmf->prealloc_pte) {
3688                pte_free(vma->vm_mm, vmf->prealloc_pte);
3689                vmf->prealloc_pte = NULL;
3690        }
3691        return ret;
3692}
3693
3694static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3695                                unsigned long addr, int page_nid,
3696                                int *flags)
3697{
3698        get_page(page);
3699
3700        count_vm_numa_event(NUMA_HINT_FAULTS);
3701        if (page_nid == numa_node_id()) {
3702                count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3703                *flags |= TNF_FAULT_LOCAL;
3704        }
3705
3706        return mpol_misplaced(page, vma, addr);
3707}
3708
3709static int do_numa_page(struct vm_fault *vmf)
3710{
3711        struct vm_area_struct *vma = vmf->vma;
3712        struct page *page = NULL;
3713        int page_nid = -1;
3714        int last_cpupid;
3715        int target_nid;
3716        bool migrated = false;
3717        pte_t pte;
3718        bool was_writable = pte_savedwrite(vmf->orig_pte);
3719        int flags = 0;
3720
3721        /*
3722         * The "pte" at this point cannot be used safely without
3723         * validation through pte_unmap_same(). It's of NUMA type but
3724         * the pfn may be screwed if the read is non atomic.
3725         */
3726        vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3727        spin_lock(vmf->ptl);
3728        if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3729                pte_unmap_unlock(vmf->pte, vmf->ptl);
3730                goto out;
3731        }
3732
3733        /*
3734         * Make it present again, Depending on how arch implementes non
3735         * accessible ptes, some can allow access by kernel mode.
3736         */
3737        pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3738        pte = pte_modify(pte, vma->vm_page_prot);
3739        pte = pte_mkyoung(pte);
3740        if (was_writable)
3741                pte = pte_mkwrite(pte);
3742        ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3743        update_mmu_cache(vma, vmf->address, vmf->pte);
3744
3745        page = vm_normal_page(vma, vmf->address, pte);
3746        if (!page) {
3747                pte_unmap_unlock(vmf->pte, vmf->ptl);
3748                return 0;
3749        }
3750
3751        /* TODO: handle PTE-mapped THP */
3752        if (PageCompound(page)) {
3753                pte_unmap_unlock(vmf->pte, vmf->ptl);
3754                return 0;
3755        }
3756
3757        /*
3758         * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3759         * much anyway since they can be in shared cache state. This misses
3760         * the case where a mapping is writable but the process never writes
3761         * to it but pte_write gets cleared during protection updates and
3762         * pte_dirty has unpredictable behaviour between PTE scan updates,
3763         * background writeback, dirty balancing and application behaviour.
3764         */
3765        if (!pte_write(pte))
3766                flags |= TNF_NO_GROUP;
3767
3768        /*
3769         * Flag if the page is shared between multiple address spaces. This
3770         * is later used when determining whether to group tasks together
3771         */
3772        if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3773                flags |= TNF_SHARED;
3774
3775        last_cpupid = page_cpupid_last(page);
3776        page_nid = page_to_nid(page);
3777        target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3778                        &flags);
3779        pte_unmap_unlock(vmf->pte, vmf->ptl);
3780        if (target_nid == -1) {
3781                put_page(page);
3782                goto out;
3783        }
3784
3785        /* Migrate to the requested node */
3786        migrated = migrate_misplaced_page(page, vma, target_nid);
3787        if (migrated) {
3788                page_nid = target_nid;
3789                flags |= TNF_MIGRATED;
3790        } else
3791                flags |= TNF_MIGRATE_FAIL;
3792
3793out:
3794        if (page_nid != -1)
3795                task_numa_fault(last_cpupid, page_nid, 1, flags);
3796        return 0;
3797}
3798
3799static inline int create_huge_pmd(struct vm_fault *vmf)
3800{
3801        if (vma_is_anonymous(vmf->vma))
3802                return do_huge_pmd_anonymous_page(vmf);
3803        if (vmf->vma->vm_ops->huge_fault)
3804                return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3805        return VM_FAULT_FALLBACK;
3806}
3807
3808static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3809{
3810        if (vma_is_anonymous(vmf->vma))
3811                return do_huge_pmd_wp_page(vmf, orig_pmd);
3812        if (vmf->vma->vm_ops->huge_fault)
3813                return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3814
3815        /* COW handled on pte level: split pmd */
3816        VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3817        __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3818
3819        return VM_FAULT_FALLBACK;
3820}
3821
3822static inline bool vma_is_accessible(struct vm_area_struct *vma)
3823{
3824        return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3825}
3826
3827static int create_huge_pud(struct vm_fault *vmf)
3828{
3829#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3830        /* No support for anonymous transparent PUD pages yet */
3831        if (vma_is_anonymous(vmf->vma))
3832                return VM_FAULT_FALLBACK;
3833        if (vmf->vma->vm_ops->huge_fault)
3834                return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3835#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3836        return VM_FAULT_FALLBACK;
3837}
3838
3839static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3840{
3841#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3842        /* No support for anonymous transparent PUD pages yet */
3843        if (vma_is_anonymous(vmf->vma))
3844                return VM_FAULT_FALLBACK;
3845        if (vmf->vma->vm_ops->huge_fault)
3846                return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3847#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3848        return VM_FAULT_FALLBACK;
3849}
3850
3851/*
3852 * These routines also need to handle stuff like marking pages dirty
3853 * and/or accessed for architectures that don't do it in hardware (most
3854 * RISC architectures).  The early dirtying is also good on the i386.
3855 *
3856 * There is also a hook called "update_mmu_cache()" that architectures
3857 * with external mmu caches can use to update those (ie the Sparc or
3858 * PowerPC hashed page tables that act as extended TLBs).
3859 *
3860 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3861 * concurrent faults).
3862 *
3863 * The mmap_sem may have been released depending on flags and our return value.
3864 * See filemap_fault() and __lock_page_or_retry().
3865 */
3866static int handle_pte_fault(struct vm_fault *vmf)
3867{
3868        pte_t entry;
3869
3870        if (unlikely(pmd_none(*vmf->pmd))) {
3871                /*
3872                 * Leave __pte_alloc() until later: because vm_ops->fault may
3873                 * want to allocate huge page, and if we expose page table
3874                 * for an instant, it will be difficult to retract from
3875                 * concurrent faults and from rmap lookups.
3876                 */
3877                vmf->pte = NULL;
3878        } else {
3879                /* See comment in pte_alloc_one_map() */
3880                if (pmd_devmap_trans_unstable(vmf->pmd))
3881                        return 0;
3882                /*
3883                 * A regular pmd is established and it can't morph into a huge
3884                 * pmd from under us anymore at this point because we hold the
3885                 * mmap_sem read mode and khugepaged takes it in write mode.
3886                 * So now it's safe to run pte_offset_map().
3887                 */
3888                vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3889                vmf->orig_pte = *vmf->pte;
3890
3891                /*
3892                 * some architectures can have larger ptes than wordsize,
3893                 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3894                 * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3895                 * atomic accesses.  The code below just needs a consistent
3896                 * view for the ifs and we later double check anyway with the
3897                 * ptl lock held. So here a barrier will do.
3898                 */
3899                barrier();
3900                if (pte_none(vmf->orig_pte)) {
3901                        pte_unmap(vmf->pte);
3902                        vmf->pte = NULL;
3903                }
3904        }
3905
3906        if (!vmf->pte) {
3907                if (vma_is_anonymous(vmf->vma))
3908                        return do_anonymous_page(vmf);
3909                else
3910                        return do_fault(vmf);
3911        }
3912
3913        if (!pte_present(vmf->orig_pte))
3914                return do_swap_page(vmf);
3915
3916        if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3917                return do_numa_page(vmf);
3918
3919        vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3920        spin_lock(vmf->ptl);
3921        entry = vmf->orig_pte;
3922        if (unlikely(!pte_same(*vmf->pte, entry)))
3923                goto unlock;
3924        if (vmf->flags & FAULT_FLAG_WRITE) {
3925                if (!pte_write(entry))
3926                        return do_wp_page(vmf);
3927                entry = pte_mkdirty(entry);
3928        }
3929        entry = pte_mkyoung(entry);
3930        if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3931                                vmf->flags & FAULT_FLAG_WRITE)) {
3932                update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3933        } else {
3934                /*
3935                 * This is needed only for protection faults but the arch code
3936                 * is not yet telling us if this is a protection fault or not.
3937                 * This still avoids useless tlb flushes for .text page faults
3938                 * with threads.
3939                 */
3940                if (vmf->flags & FAULT_FLAG_WRITE)
3941                        flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3942        }
3943unlock:
3944        pte_unmap_unlock(vmf->pte, vmf->ptl);
3945        return 0;
3946}
3947
3948/*
3949 * By the time we get here, we already hold the mm semaphore
3950 *
3951 * The mmap_sem may have been released depending on flags and our
3952 * return value.  See filemap_fault() and __lock_page_or_retry().
3953 */
3954static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3955                unsigned int flags)
3956{
3957        struct vm_fault vmf = {
3958                .vma = vma,
3959                .address = address & PAGE_MASK,
3960                .flags = flags,
3961                .pgoff = linear_page_index(vma, address),
3962                .gfp_mask = __get_fault_gfp_mask(vma),
3963        };
3964        unsigned int dirty = flags & FAULT_FLAG_WRITE;
3965        struct mm_struct *mm = vma->vm_mm;
3966        pgd_t *pgd;
3967        p4d_t *p4d;
3968        int ret;
3969
3970        pgd = pgd_offset(mm, address);
3971        p4d = p4d_alloc(mm, pgd, address);
3972        if (!p4d)
3973                return VM_FAULT_OOM;
3974
3975        vmf.pud = pud_alloc(mm, p4d, address);
3976        if (!vmf.pud)
3977                return VM_FAULT_OOM;
3978        if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
3979                ret = create_huge_pud(&vmf);
3980                if (!(ret & VM_FAULT_FALLBACK))
3981                        return ret;
3982        } else {
3983                pud_t orig_pud = *vmf.pud;
3984
3985                barrier();
3986                if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3987
3988                        /* NUMA case for anonymous PUDs would go here */
3989
3990                        if (dirty && !pud_write(orig_pud)) {
3991                                ret = wp_huge_pud(&vmf, orig_pud);
3992                                if (!(ret & VM_FAULT_FALLBACK))
3993                                        return ret;
3994                        } else {
3995                                huge_pud_set_accessed(&vmf, orig_pud);
3996                                return 0;
3997                        }
3998                }
3999        }
4000
4001        vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4002        if (!vmf.pmd)
4003                return VM_FAULT_OOM;
4004        if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
4005                ret = create_huge_pmd(&vmf);
4006                if (!(ret & VM_FAULT_FALLBACK))
4007                        return ret;
4008        } else {
4009                pmd_t orig_pmd = *vmf.pmd;
4010
4011                barrier();
4012                if (unlikely(is_swap_pmd(orig_pmd))) {
4013                        VM_BUG_ON(thp_migration_supported() &&
4014                                          !is_pmd_migration_entry(orig_pmd));
4015                        if (is_pmd_migration_entry(orig_pmd))
4016                                pmd_migration_entry_wait(mm, vmf.pmd);
4017                        return 0;
4018                }
4019                if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4020                        if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4021                                return do_huge_pmd_numa_page(&vmf, orig_pmd);
4022
4023                        if (dirty && !pmd_write(orig_pmd)) {
4024                                ret = wp_huge_pmd(&vmf, orig_pmd);
4025                                if (!(ret & VM_FAULT_FALLBACK))
4026                                        return ret;
4027                        } else {
4028                                huge_pmd_set_accessed(&vmf, orig_pmd);
4029                                return 0;
4030                        }
4031                }
4032        }
4033
4034        return handle_pte_fault(&vmf);
4035}
4036
4037/*
4038 * By the time we get here, we already hold the mm semaphore
4039 *
4040 * The mmap_sem may have been released depending on flags and our
4041 * return value.  See filemap_fault() and __lock_page_or_retry().
4042 */
4043int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4044                unsigned int flags)
4045{
4046        int ret;
4047
4048        __set_current_state(TASK_RUNNING);
4049
4050        count_vm_event(PGFAULT);
4051        count_memcg_event_mm(vma->vm_mm, PGFAULT);
4052
4053        /* do counter updates before entering really critical section. */
4054        check_sync_rss_stat(current);
4055
4056        if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4057                                            flags & FAULT_FLAG_INSTRUCTION,
4058                                            flags & FAULT_FLAG_REMOTE))
4059                return VM_FAULT_SIGSEGV;
4060
4061        /*
4062         * Enable the memcg OOM handling for faults triggered in user
4063         * space.  Kernel faults are handled more gracefully.
4064         */
4065        if (flags & FAULT_FLAG_USER)
4066                mem_cgroup_oom_enable();
4067
4068        if (unlikely(is_vm_hugetlb_page(vma)))
4069                ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4070        else
4071                ret = __handle_mm_fault(vma, address, flags);
4072
4073        if (flags & FAULT_FLAG_USER) {
4074                mem_cgroup_oom_disable();
4075                /*
4076                 * The task may have entered a memcg OOM situation but
4077                 * if the allocation error was handled gracefully (no
4078                 * VM_FAULT_OOM), there is no need to kill anything.
4079                 * Just clean up the OOM state peacefully.
4080                 */
4081                if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4082                        mem_cgroup_oom_synchronize(false);
4083        }
4084
4085        return ret;
4086}
4087EXPORT_SYMBOL_GPL(handle_mm_fault);
4088
4089#ifndef __PAGETABLE_P4D_FOLDED
4090/*
4091 * Allocate p4d page table.
4092 * We've already handled the fast-path in-line.
4093 */
4094int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4095{
4096        p4d_t *new = p4d_alloc_one(mm, address);
4097        if (!new)
4098                return -ENOMEM;
4099
4100        smp_wmb(); /* See comment in __pte_alloc */
4101
4102        spin_lock(&mm->page_table_lock);
4103        if (pgd_present(*pgd))          /* Another has populated it */
4104                p4d_free(mm, new);
4105        else
4106                pgd_populate(mm, pgd, new);
4107        spin_unlock(&mm->page_table_lock);
4108        return 0;
4109}
4110#endif /* __PAGETABLE_P4D_FOLDED */
4111
4112#ifndef __PAGETABLE_PUD_FOLDED
4113/*
4114 * Allocate page upper directory.
4115 * We've already handled the fast-path in-line.
4116 */
4117int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4118{
4119        pud_t *new = pud_alloc_one(mm, address);
4120        if (!new)
4121                return -ENOMEM;
4122
4123        smp_wmb(); /* See comment in __pte_alloc */
4124
4125        spin_lock(&mm->page_table_lock);
4126#ifndef __ARCH_HAS_5LEVEL_HACK
4127        if (p4d_present(*p4d))          /* Another has populated it */
4128                pud_free(mm, new);
4129        else
4130                p4d_populate(mm, p4d, new);
4131#else
4132        if (pgd_present(*p4d))          /* Another has populated it */
4133                pud_free(mm, new);
4134        else
4135                pgd_populate(mm, p4d, new);
4136#endif /* __ARCH_HAS_5LEVEL_HACK */
4137        spin_unlock(&mm->page_table_lock);
4138        return 0;
4139}
4140#endif /* __PAGETABLE_PUD_FOLDED */
4141
4142#ifndef __PAGETABLE_PMD_FOLDED
4143/*
4144 * Allocate page middle directory.
4145 * We've already handled the fast-path in-line.
4146 */
4147int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4148{
4149        spinlock_t *ptl;
4150        pmd_t *new = pmd_alloc_one(mm, address);
4151        if (!new)
4152                return -ENOMEM;
4153
4154        smp_wmb(); /* See comment in __pte_alloc */
4155
4156        ptl = pud_lock(mm, pud);
4157#ifndef __ARCH_HAS_4LEVEL_HACK
4158        if (!pud_present(*pud)) {
4159                mm_inc_nr_pmds(mm);
4160                pud_populate(mm, pud, new);
4161        } else  /* Another has populated it */
4162                pmd_free(mm, new);
4163#else
4164        if (!pgd_present(*pud)) {
4165                mm_inc_nr_pmds(mm);
4166                pgd_populate(mm, pud, new);
4167        } else /* Another has populated it */
4168                pmd_free(mm, new);
4169#endif /* __ARCH_HAS_4LEVEL_HACK */
4170        spin_unlock(ptl);
4171        return 0;
4172}
4173#endif /* __PAGETABLE_PMD_FOLDED */
4174
4175static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4176                            unsigned long *start, unsigned long *end,
4177                            pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4178{
4179        pgd_t *pgd;
4180        p4d_t *p4d;
4181        pud_t *pud;
4182        pmd_t *pmd;
4183        pte_t *ptep;
4184
4185        pgd = pgd_offset(mm, address);
4186        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4187                goto out;
4188
4189        p4d = p4d_offset(pgd, address);
4190        if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4191                goto out;
4192
4193        pud = pud_offset(p4d, address);
4194        if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4195                goto out;
4196
4197        pmd = pmd_offset(pud, address);
4198        VM_BUG_ON(pmd_trans_huge(*pmd));
4199
4200        if (pmd_huge(*pmd)) {
4201                if (!pmdpp)
4202                        goto out;
4203
4204                if (start && end) {
4205                        *start = address & PMD_MASK;
4206                        *end = *start + PMD_SIZE;
4207                        mmu_notifier_invalidate_range_start(mm, *start, *end);
4208                }
4209                *ptlp = pmd_lock(mm, pmd);
4210                if (pmd_huge(*pmd)) {
4211                        *pmdpp = pmd;
4212                        return 0;
4213                }
4214                spin_unlock(*ptlp);
4215                if (start && end)
4216                        mmu_notifier_invalidate_range_end(mm, *start, *end);
4217        }
4218
4219        if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4220                goto out;
4221
4222        if (start && end) {
4223                *start = address & PAGE_MASK;
4224                *end = *start + PAGE_SIZE;
4225                mmu_notifier_invalidate_range_start(mm, *start, *end);
4226        }
4227        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4228        if (!pte_present(*ptep))
4229                goto unlock;
4230        *ptepp = ptep;
4231        return 0;
4232unlock:
4233        pte_unmap_unlock(ptep, *ptlp);
4234        if (start && end)
4235                mmu_notifier_invalidate_range_end(mm, *start, *end);
4236out:
4237        return -EINVAL;
4238}
4239
4240static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4241                             pte_t **ptepp, spinlock_t **ptlp)
4242{
4243        int res;
4244
4245        /* (void) is needed to make gcc happy */
4246        (void) __cond_lock(*ptlp,
4247                           !(res = __follow_pte_pmd(mm, address, NULL, NULL,
4248                                                    ptepp, NULL, ptlp)));
4249        return res;
4250}
4251
4252int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4253                             unsigned long *start, unsigned long *end,
4254                             pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4255{
4256        int res;
4257
4258        /* (void) is needed to make gcc happy */
4259        (void) __cond_lock(*ptlp,
4260                           !(res = __follow_pte_pmd(mm, address, start, end,
4261                                                    ptepp, pmdpp, ptlp)));
4262        return res;
4263}
4264EXPORT_SYMBOL(follow_pte_pmd);
4265
4266/**
4267 * follow_pfn - look up PFN at a user virtual address
4268 * @vma: memory mapping
4269 * @address: user virtual address
4270 * @pfn: location to store found PFN
4271 *
4272 * Only IO mappings and raw PFN mappings are allowed.
4273 *
4274 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4275 */
4276int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4277        unsigned long *pfn)
4278{
4279        int ret = -EINVAL;
4280        spinlock_t *ptl;
4281        pte_t *ptep;
4282
4283        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4284                return ret;
4285
4286        ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4287        if (ret)
4288                return ret;
4289        *pfn = pte_pfn(*ptep);
4290        pte_unmap_unlock(ptep, ptl);
4291        return 0;
4292}
4293EXPORT_SYMBOL(follow_pfn);
4294
4295#ifdef CONFIG_HAVE_IOREMAP_PROT
4296int follow_phys(struct vm_area_struct *vma,
4297                unsigned long address, unsigned int flags,
4298                unsigned long *prot, resource_size_t *phys)
4299{
4300        int ret = -EINVAL;
4301        pte_t *ptep, pte;
4302        spinlock_t *ptl;
4303
4304        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4305                goto out;
4306
4307        if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4308                goto out;
4309        pte = *ptep;
4310
4311        if ((flags & FOLL_WRITE) && !pte_write(pte))
4312                goto unlock;
4313
4314        *prot = pgprot_val(pte_pgprot(pte));
4315        *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4316
4317        ret = 0;
4318unlock:
4319        pte_unmap_unlock(ptep, ptl);
4320out:
4321        return ret;
4322}
4323
4324int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4325                        void *buf, int len, int write)
4326{
4327        resource_size_t phys_addr;
4328        unsigned long prot = 0;
4329        void __iomem *maddr;
4330        int offset = addr & (PAGE_SIZE-1);
4331
4332        if (follow_phys(vma, addr, write, &prot, &phys_addr))
4333                return -EINVAL;
4334
4335        maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4336        if (write)
4337                memcpy_toio(maddr + offset, buf, len);
4338        else
4339                memcpy_fromio(buf, maddr + offset, len);
4340        iounmap(maddr);
4341
4342        return len;
4343}
4344EXPORT_SYMBOL_GPL(generic_access_phys);
4345#endif
4346
4347/*
4348 * Access another process' address space as given in mm.  If non-NULL, use the
4349 * given task for page fault accounting.
4350 */
4351int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4352                unsigned long addr, void *buf, int len, unsigned int gup_flags)
4353{
4354        struct vm_area_struct *vma;
4355        void *old_buf = buf;
4356        int write = gup_flags & FOLL_WRITE;
4357
4358        down_read(&mm->mmap_sem);
4359        /* ignore errors, just check how much was successfully transferred */
4360        while (len) {
4361                int bytes, ret, offset;
4362                void *maddr;
4363                struct page *page = NULL;
4364
4365                ret = get_user_pages_remote(tsk, mm, addr, 1,
4366                                gup_flags, &page, &vma, NULL);
4367                if (ret <= 0) {
4368#ifndef CONFIG_HAVE_IOREMAP_PROT
4369                        break;
4370#else
4371                        /*
4372                         * Check if this is a VM_IO | VM_PFNMAP VMA, which
4373                         * we can access using slightly different code.
4374                         */
4375                        vma = find_vma(mm, addr);
4376                        if (!vma || vma->vm_start > addr)
4377                                break;
4378                        if (vma->vm_ops && vma->vm_ops->access)
4379                                ret = vma->vm_ops->access(vma, addr, buf,
4380                                                          len, write);
4381                        if (ret <= 0)
4382                                break;
4383                        bytes = ret;
4384#endif
4385                } else {
4386                        bytes = len;
4387                        offset = addr & (PAGE_SIZE-1);
4388                        if (bytes > PAGE_SIZE-offset)
4389                                bytes = PAGE_SIZE-offset;
4390
4391                        maddr = kmap(page);
4392                        if (write) {
4393                                copy_to_user_page(vma, page, addr,
4394                                                  maddr + offset, buf, bytes);
4395                                set_page_dirty_lock(page);
4396                        } else {
4397                                copy_from_user_page(vma, page, addr,
4398                                                    buf, maddr + offset, bytes);
4399                        }
4400                        kunmap(page);
4401                        put_page(page);
4402                }
4403                len -= bytes;
4404                buf += bytes;
4405                addr += bytes;
4406        }
4407        up_read(&mm->mmap_sem);
4408
4409        return buf - old_buf;
4410}
4411
4412/**
4413 * access_remote_vm - access another process' address space
4414 * @mm:         the mm_struct of the target address space
4415 * @addr:       start address to access
4416 * @buf:        source or destination buffer
4417 * @len:        number of bytes to transfer
4418 * @gup_flags:  flags modifying lookup behaviour
4419 *
4420 * The caller must hold a reference on @mm.
4421 */
4422int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4423                void *buf, int len, unsigned int gup_flags)
4424{
4425        return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4426}
4427
4428/*
4429 * Access another process' address space.
4430 * Source/target buffer must be kernel space,
4431 * Do not walk the page table directly, use get_user_pages
4432 */
4433int access_process_vm(struct task_struct *tsk, unsigned long addr,
4434                void *buf, int len, unsigned int gup_flags)
4435{
4436        struct mm_struct *mm;
4437        int ret;
4438
4439        mm = get_task_mm(tsk);
4440        if (!mm)
4441                return 0;
4442
4443        ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4444
4445        mmput(mm);
4446
4447        return ret;
4448}
4449EXPORT_SYMBOL_GPL(access_process_vm);
4450
4451/*
4452 * Print the name of a VMA.
4453 */
4454void print_vma_addr(char *prefix, unsigned long ip)
4455{
4456        struct mm_struct *mm = current->mm;
4457        struct vm_area_struct *vma;
4458
4459        /*
4460         * Do not print if we are in atomic
4461         * contexts (in exception stacks, etc.):
4462         */
4463        if (preempt_count())
4464                return;
4465
4466        down_read(&mm->mmap_sem);
4467        vma = find_vma(mm, ip);
4468        if (vma && vma->vm_file) {
4469                struct file *f = vma->vm_file;
4470                char *buf = (char *)__get_free_page(GFP_KERNEL);
4471                if (buf) {
4472                        char *p;
4473
4474                        p = file_path(f, buf, PAGE_SIZE);
4475                        if (IS_ERR(p))
4476                                p = "?";
4477                        printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4478                                        vma->vm_start,
4479                                        vma->vm_end - vma->vm_start);
4480                        free_page((unsigned long)buf);
4481                }
4482        }
4483        up_read(&mm->mmap_sem);
4484}
4485
4486#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4487void __might_fault(const char *file, int line)
4488{
4489        /*
4490         * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4491         * holding the mmap_sem, this is safe because kernel memory doesn't
4492         * get paged out, therefore we'll never actually fault, and the
4493         * below annotations will generate false positives.
4494         */
4495        if (uaccess_kernel())
4496                return;
4497        if (pagefault_disabled())
4498                return;
4499        __might_sleep(file, line, 0);
4500#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4501        if (current->mm)
4502                might_lock_read(&current->mm->mmap_sem);
4503#endif
4504}
4505EXPORT_SYMBOL(__might_fault);
4506#endif
4507
4508#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4509static void clear_gigantic_page(struct page *page,
4510                                unsigned long addr,
4511                                unsigned int pages_per_huge_page)
4512{
4513        int i;
4514        struct page *p = page;
4515
4516        might_sleep();
4517        for (i = 0; i < pages_per_huge_page;
4518             i++, p = mem_map_next(p, page, i)) {
4519                cond_resched();
4520                clear_user_highpage(p, addr + i * PAGE_SIZE);
4521        }
4522}
4523void clear_huge_page(struct page *page,
4524                     unsigned long addr_hint, unsigned int pages_per_huge_page)
4525{
4526        int i, n, base, l;
4527        unsigned long addr = addr_hint &
4528                ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4529
4530        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4531                clear_gigantic_page(page, addr, pages_per_huge_page);
4532                return;
4533        }
4534
4535        /* Clear sub-page to access last to keep its cache lines hot */
4536        might_sleep();
4537        n = (addr_hint - addr) / PAGE_SIZE;
4538        if (2 * n <= pages_per_huge_page) {
4539                /* If sub-page to access in first half of huge page */
4540                base = 0;
4541                l = n;
4542                /* Clear sub-pages at the end of huge page */
4543                for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4544                        cond_resched();
4545                        clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4546                }
4547        } else {
4548                /* If sub-page to access in second half of huge page */
4549                base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4550                l = pages_per_huge_page - n;
4551                /* Clear sub-pages at the begin of huge page */
4552                for (i = 0; i < base; i++) {
4553                        cond_resched();
4554                        clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4555                }
4556        }
4557        /*
4558         * Clear remaining sub-pages in left-right-left-right pattern
4559         * towards the sub-page to access
4560         */
4561        for (i = 0; i < l; i++) {
4562                int left_idx = base + i;
4563                int right_idx = base + 2 * l - 1 - i;
4564
4565                cond_resched();
4566                clear_user_highpage(page + left_idx,
4567                                    addr + left_idx * PAGE_SIZE);
4568                cond_resched();
4569                clear_user_highpage(page + right_idx,
4570                                    addr + right_idx * PAGE_SIZE);
4571        }
4572}
4573
4574static void copy_user_gigantic_page(struct page *dst, struct page *src,
4575                                    unsigned long addr,
4576                                    struct vm_area_struct *vma,
4577                                    unsigned int pages_per_huge_page)
4578{
4579        int i;
4580        struct page *dst_base = dst;
4581        struct page *src_base = src;
4582
4583        for (i = 0; i < pages_per_huge_page; ) {
4584                cond_resched();
4585                copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4586
4587                i++;
4588                dst = mem_map_next(dst, dst_base, i);
4589                src = mem_map_next(src, src_base, i);
4590        }
4591}
4592
4593void copy_user_huge_page(struct page *dst, struct page *src,
4594                         unsigned long addr, struct vm_area_struct *vma,
4595                         unsigned int pages_per_huge_page)
4596{
4597        int i;
4598
4599        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4600                copy_user_gigantic_page(dst, src, addr, vma,
4601                                        pages_per_huge_page);
4602                return;
4603        }
4604
4605        might_sleep();
4606        for (i = 0; i < pages_per_huge_page; i++) {
4607                cond_resched();
4608                copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4609        }
4610}
4611
4612long copy_huge_page_from_user(struct page *dst_page,
4613                                const void __user *usr_src,
4614                                unsigned int pages_per_huge_page,
4615                                bool allow_pagefault)
4616{
4617        void *src = (void *)usr_src;
4618        void *page_kaddr;
4619        unsigned long i, rc = 0;
4620        unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4621
4622        for (i = 0; i < pages_per_huge_page; i++) {
4623                if (allow_pagefault)
4624                        page_kaddr = kmap(dst_page + i);
4625                else
4626                        page_kaddr = kmap_atomic(dst_page + i);
4627                rc = copy_from_user(page_kaddr,
4628                                (const void __user *)(src + i * PAGE_SIZE),
4629                                PAGE_SIZE);
4630                if (allow_pagefault)
4631                        kunmap(dst_page + i);
4632                else
4633                        kunmap_atomic(page_kaddr);
4634
4635                ret_val -= (PAGE_SIZE - rc);
4636                if (rc)
4637                        break;
4638
4639                cond_resched();
4640        }
4641        return ret_val;
4642}
4643#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4644
4645#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4646
4647static struct kmem_cache *page_ptl_cachep;
4648
4649void __init ptlock_cache_init(void)
4650{
4651        page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4652                        SLAB_PANIC, NULL);
4653}
4654
4655bool ptlock_alloc(struct page *page)
4656{
4657        spinlock_t *ptl;
4658
4659        ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4660        if (!ptl)
4661                return false;
4662        page->ptl = ptl;
4663        return true;
4664}
4665
4666void ptlock_free(struct page *page)
4667{
4668        kmem_cache_free(page_ptl_cachep, page->ptl);
4669}
4670#endif
4671