mm/memory.c

   1 /*
   2  *  linux/mm/memory.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   5  */
   6
   7 /*
   8  * demand-loading started 01.12.91 - seems it is high on the list of
   9  * things wanted, and it should be easy to implement. - Linus
  10  */
  11
  12 /*
  13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
  14  * pages started 02.12.91, seems to work. - Linus.
  15  *
  16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
  17  * would have taken more than the 6M I have free, but it worked well as
  18  * far as I could see.
  19  *
  20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
  21  */
  22
  23 /*
  24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
  25  * thought has to go into this. Oh, well..
  26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
  27  *              Found it. Everything seems to work now.
  28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
  29  */
  30
  31 /*
  32  * 05.04.94  -  Multi-page memory management added for v1.1.
  33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
  34  *
  35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
  36  *              (Gerhard.Wichert@pdb.siemens.de)
  37  *
  38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
  39  */
  40
  41 #include <linux/kernel_stat.h>
  42 #include <linux/mm.h>
  43 #include <linux/hugetlb.h>
  44 #include <linux/mman.h>
  45 #include <linux/swap.h>
  46 #include <linux/highmem.h>
  47 #include <linux/pagemap.h>
  48 #include <linux/rmap.h>
  49 #include <linux/module.h>
  50 #include <linux/delayacct.h>
  51 #include <linux/init.h>
  52 #include <linux/writeback.h>
  53 #include <linux/memcontrol.h>
  54 #include <linux/mmu_notifier.h>
  55 #include <linux/kallsyms.h>
  56 #include <linux/swapops.h>
  57 #include <linux/elf.h>
  58
  59 #include <asm/pgalloc.h>
  60 #include <asm/uaccess.h>
  61 #include <asm/tlb.h>
  62 #include <asm/tlbflush.h>
  63 #include <asm/pgtable.h>
  64
  65 #include "internal.h"
  66
  67 #ifndef CONFIG_NEED_MULTIPLE_NODES
  68 /* use the per-pgdat data instead for discontigmem - mbligh */
  69 unsigned long max_mapnr;
  70 struct page *mem_map;
  71
  72 EXPORT_SYMBOL(max_mapnr);
  73 EXPORT_SYMBOL(mem_map);
  74 #endif
  75
  76 unsigned long num_physpages;
  77 /*
  78  * A number of key systems in x86 including ioremap() rely on the assumption
  79  * that high_memory defines the upper bound on direct map memory, then end
  80  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  81  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  82  * and ZONE_HIGHMEM.
  83  */
  84 void * high_memory;
  85
  86 EXPORT_SYMBOL(num_physpages);
  87 EXPORT_SYMBOL(high_memory);
  88
  89 /*
  90  * Randomize the address space (stacks, mmaps, brk, etc.).
  91  *
  92  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
  93  *   as ancient (libc5 based) binaries can segfault. )
  94  */
  95 int randomize_va_space __read_mostly =
  96 #ifdef CONFIG_COMPAT_BRK
  97                                         1;
  98 #else
  99                                         2;
 100 #endif
 101
 102 static int __init disable_randmaps(char *s)
 103 {
 104         randomize_va_space = 0;
 105         return 1;
 106 }
 107 __setup("norandmaps", disable_randmaps);
 108
 109
 110 /*
 111  * If a p?d_bad entry is found while walking page tables, report
 112  * the error, before resetting entry to p?d_none.  Usually (but
 113  * very seldom) called out from the p?d_none_or_clear_bad macros.
 114  */
 115
 116 void pgd_clear_bad(pgd_t *pgd)
 117 {
 118         pgd_ERROR(*pgd);
 119         pgd_clear(pgd);
 120 }
 121
 122 void pud_clear_bad(pud_t *pud)
 123 {
 124         pud_ERROR(*pud);
 125         pud_clear(pud);
 126 }
 127
 128 void pmd_clear_bad(pmd_t *pmd)
 129 {
 130         pmd_ERROR(*pmd);
 131         pmd_clear(pmd);
 132 }
 133
 134 /*
 135  * Note: this doesn't free the actual pages themselves. That
 136  * has been handled earlier when unmapping all the memory regions.
 137  */
 138 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
 139 {
 140         pgtable_t token = pmd_pgtable(*pmd);
 141         pmd_clear(pmd);
 142         pte_free_tlb(tlb, token);
 143         tlb->mm->nr_ptes--;
 144 }
 145
 146 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 147                                 unsigned long addr, unsigned long end,
 148                                 unsigned long floor, unsigned long ceiling)
 149 {
 150         pmd_t *pmd;
 151         unsigned long next;
 152         unsigned long start;
 153
 154         start = addr;
 155         pmd = pmd_offset(pud, addr);
 156         do {
 157                 next = pmd_addr_end(addr, end);
 158                 if (pmd_none_or_clear_bad(pmd))
 159                         continue;
 160                 free_pte_range(tlb, pmd);
 161         } while (pmd++, addr = next, addr != end);
 162
 163         start &= PUD_MASK;
 164         if (start < floor)
 165                 return;
 166         if (ceiling) {
 167                 ceiling &= PUD_MASK;
 168                 if (!ceiling)
 169                         return;
 170         }
 171         if (end - 1 > ceiling - 1)
 172                 return;
 173
 174         pmd = pmd_offset(pud, start);
 175         pud_clear(pud);
 176         pmd_free_tlb(tlb, pmd);
 177 }
 178
 179 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 180                                 unsigned long addr, unsigned long end,
 181                                 unsigned long floor, unsigned long ceiling)
 182 {
 183         pud_t *pud;
 184         unsigned long next;
 185         unsigned long start;
 186
 187         start = addr;
 188         pud = pud_offset(pgd, addr);
 189         do {
 190                 next = pud_addr_end(addr, end);
 191                 if (pud_none_or_clear_bad(pud))
 192                         continue;
 193                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 194         } while (pud++, addr = next, addr != end);
 195
 196         start &= PGDIR_MASK;
 197         if (start < floor)
 198                 return;
 199         if (ceiling) {
 200                 ceiling &= PGDIR_MASK;
 201                 if (!ceiling)
 202                         return;
 203         }
 204         if (end - 1 > ceiling - 1)
 205                 return;
 206
 207         pud = pud_offset(pgd, start);
 208         pgd_clear(pgd);
 209         pud_free_tlb(tlb, pud);
 210 }
 211
 212 /*
 213  * This function frees user-level page tables of a process.
 214  *
 215  * Must be called with pagetable lock held.
 216  */
 217 void free_pgd_range(struct mmu_gather *tlb,
 218                         unsigned long addr, unsigned long end,
 219                         unsigned long floor, unsigned long ceiling)
 220 {
 221         pgd_t *pgd;
 222         unsigned long next;
 223         unsigned long start;
 224
 225         /*
 226          * The next few lines have given us lots of grief...
 227          *
 228          * Why are we testing PMD* at this top level?  Because often
 229          * there will be no work to do at all, and we'd prefer not to
 230          * go all the way down to the bottom just to discover that.
 231          *
 232          * Why all these "- 1"s?  Because 0 represents both the bottom
 233          * of the address space and the top of it (using -1 for the
 234          * top wouldn't help much: the masks would do the wrong thing).
 235          * The rule is that addr 0 and floor 0 refer to the bottom of
 236          * the address space, but end 0 and ceiling 0 refer to the top
 237          * Comparisons need to use "end - 1" and "ceiling - 1" (though
 238          * that end 0 case should be mythical).
 239          *
 240          * Wherever addr is brought up or ceiling brought down, we must
 241          * be careful to reject "the opposite 0" before it confuses the
 242          * subsequent tests.  But what about where end is brought down
 243          * by PMD_SIZE below? no, end can't go down to 0 there.
 244          *
 245          * Whereas we round start (addr) and ceiling down, by different
 246          * masks at different levels, in order to test whether a table
 247          * now has no other vmas using it, so can be freed, we don't
 248          * bother to round floor or end up - the tests don't need that.
 249          */
 250
 251         addr &= PMD_MASK;
 252         if (addr < floor) {
 253                 addr += PMD_SIZE;
 254                 if (!addr)
 255                         return;
 256         }
 257         if (ceiling) {
 258                 ceiling &= PMD_MASK;
 259                 if (!ceiling)
 260                         return;
 261         }
 262         if (end - 1 > ceiling - 1)
 263                 end -= PMD_SIZE;
 264         if (addr > end - 1)
 265                 return;
 266
 267         start = addr;
 268         pgd = pgd_offset(tlb->mm, addr);
 269         do {
 270                 next = pgd_addr_end(addr, end);
 271                 if (pgd_none_or_clear_bad(pgd))
 272                         continue;
 273                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 274         } while (pgd++, addr = next, addr != end);
 275 }
 276
 277 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 278                 unsigned long floor, unsigned long ceiling)
 279 {
 280         while (vma) {
 281                 struct vm_area_struct *next = vma->vm_next;
 282                 unsigned long addr = vma->vm_start;
 283
 284                 /*
 285                  * Hide vma from rmap and vmtruncate before freeing pgtables
 286                  */
 287                 anon_vma_unlink(vma);
 288                 unlink_file_vma(vma);
 289
 290                 if (is_vm_hugetlb_page(vma)) {
 291                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 292                                 floor, next? next->vm_start: ceiling);
 293                 } else {
 294                         /*
 295                          * Optimization: gather nearby vmas into one call down
 296                          */
 297                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 298                                && !is_vm_hugetlb_page(next)) {
 299                                 vma = next;
 300                                 next = vma->vm_next;
 301                                 anon_vma_unlink(vma);
 302                                 unlink_file_vma(vma);
 303                         }
 304                         free_pgd_range(tlb, addr, vma->vm_end,
 305                                 floor, next? next->vm_start: ceiling);
 306                 }
 307                 vma = next;
 308         }
 309 }
 310
 311 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 312 {
 313         pgtable_t new = pte_alloc_one(mm, address);
 314         if (!new)
 315                 return -ENOMEM;
 316
 317         /*
 318          * Ensure all pte setup (eg. pte page lock and page clearing) are
 319          * visible before the pte is made visible to other CPUs by being
 320          * put into page tables.
 321          *
 322          * The other side of the story is the pointer chasing in the page
 323          * table walking code (when walking the page table without locking;
 324          * ie. most of the time). Fortunately, these data accesses consist
 325          * of a chain of data-dependent loads, meaning most CPUs (alpha
 326          * being the notable exception) will already guarantee loads are
 327          * seen in-order. See the alpha page table accessors for the
 328          * smp_read_barrier_depends() barriers in page table walking code.
 329          */
 330         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 331
 332         spin_lock(&mm->page_table_lock);
 333         if (!pmd_present(*pmd)) {       /* Has another populated it ? */
 334                 mm->nr_ptes++;
 335                 pmd_populate(mm, pmd, new);
 336                 new = NULL;
 337         }
 338         spin_unlock(&mm->page_table_lock);
 339         if (new)
 340                 pte_free(mm, new);
 341         return 0;
 342 }
 343
 344 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 345 {
 346         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 347         if (!new)
 348                 return -ENOMEM;
 349
 350         smp_wmb(); /* See comment in __pte_alloc */
 351
 352         spin_lock(&init_mm.page_table_lock);
 353         if (!pmd_present(*pmd)) {       /* Has another populated it ? */
 354                 pmd_populate_kernel(&init_mm, pmd, new);
 355                 new = NULL;
 356         }
 357         spin_unlock(&init_mm.page_table_lock);
 358         if (new)
 359                 pte_free_kernel(&init_mm, new);
 360         return 0;
 361 }
 362
 363 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
 364 {
 365         if (file_rss)
 366                 add_mm_counter(mm, file_rss, file_rss);
 367         if (anon_rss)
 368                 add_mm_counter(mm, anon_rss, anon_rss);
 369 }
 370
 371 /*
 372  * This function is called to print an error when a bad pte
 373  * is found. For example, we might have a PFN-mapped pte in
 374  * a region that doesn't allow it.
 375  *
 376  * The calling function must still handle the error.
 377  */
 378 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 379                           pte_t pte, struct page *page)
 380 {
 381         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
 382         pud_t *pud = pud_offset(pgd, addr);
 383         pmd_t *pmd = pmd_offset(pud, addr);
 384         struct address_space *mapping;
 385         pgoff_t index;
 386         static unsigned long resume;
 387         static unsigned long nr_shown;
 388         static unsigned long nr_unshown;
 389
 390         /*
 391          * Allow a burst of 60 reports, then keep quiet for that minute;
 392          * or allow a steady drip of one report per second.
 393          */
 394         if (nr_shown == 60) {
 395                 if (time_before(jiffies, resume)) {
 396                         nr_unshown++;
 397                         return;
 398                 }
 399                 if (nr_unshown) {
 400                         printk(KERN_ALERT
 401                                 "BUG: Bad page map: %lu messages suppressed\n",
 402                                 nr_unshown);
 403                         nr_unshown = 0;
 404                 }
 405                 nr_shown = 0;
 406         }
 407         if (nr_shown++ == 0)
 408                 resume = jiffies + 60 * HZ;
 409
 410         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 411         index = linear_page_index(vma, addr);
 412
 413         printk(KERN_ALERT
 414                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
 415                 current->comm,
 416                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
 417         if (page) {
 418                 printk(KERN_ALERT
 419                 "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
 420                 page, (void *)page->flags, page_count(page),
 421                 page_mapcount(page), page->mapping, page->index);
 422         }
 423         printk(KERN_ALERT
 424                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
 425                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
 426         /*
 427          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 428          */
 429         if (vma->vm_ops)
 430                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
 431                                 (unsigned long)vma->vm_ops->fault);
 432         if (vma->vm_file && vma->vm_file->f_op)
 433                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
 434                                 (unsigned long)vma->vm_file->f_op->mmap);
 435         dump_stack();
 436         add_taint(TAINT_BAD_PAGE);
 437 }
 438
 439 static inline int is_cow_mapping(unsigned int flags)
 440 {
 441         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 442 }
 443
 444 /*
 445  * vm_normal_page -- This function gets the "struct page" associated with a pte.
 446  *
 447  * "Special" mappings do not wish to be associated with a "struct page" (either
 448  * it doesn't exist, or it exists but they don't want to touch it). In this
 449  * case, NULL is returned here. "Normal" mappings do have a struct page.
 450  *
 451  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 452  * pte bit, in which case this function is trivial. Secondly, an architecture
 453  * may not have a spare pte bit, which requires a more complicated scheme,
 454  * described below.
 455  *
 456  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 457  * special mapping (even if there are underlying and valid "struct pages").
 458  * COWed pages of a VM_PFNMAP are always normal.
 459  *
 460  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 461  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
 462  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 463  * mapping will always honor the rule
 464  *
 465  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 466  *
 467  * And for normal mappings this is false.
 468  *
 469  * This restricts such mappings to be a linear translation from virtual address
 470  * to pfn. To get around this restriction, we allow arbitrary mappings so long
 471  * as the vma is not a COW mapping; in that case, we know that all ptes are
 472  * special (because none can have been COWed).
 473  *
 474  *
 475  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
 476  *
 477  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 478  * page" backing, however the difference is that _all_ pages with a struct
 479  * page (that is, those where pfn_valid is true) are refcounted and considered
 480  * normal pages by the VM. The disadvantage is that pages are refcounted
 481  * (which can be slower and simply not an option for some PFNMAP users). The
 482  * advantage is that we don't have to follow the strict linearity rule of
 483  * PFNMAP mappings in order to support COWable mappings.
 484  *
 485  */
 486 #ifdef __HAVE_ARCH_PTE_SPECIAL
 487 # define HAVE_PTE_SPECIAL 1
 488 #else
 489 # define HAVE_PTE_SPECIAL 0
 490 #endif
 491 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 492                                 pte_t pte)
 493 {
 494         unsigned long pfn = pte_pfn(pte);
 495
 496         if (HAVE_PTE_SPECIAL) {
 497                 if (likely(!pte_special(pte)))
 498                         goto check_pfn;
 499                 if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
 500                         print_bad_pte(vma, addr, pte, NULL);
 501                 return NULL;
 502         }
 503
 504         /* !HAVE_PTE_SPECIAL case follows: */
 505
 506         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 507                 if (vma->vm_flags & VM_MIXEDMAP) {
 508                         if (!pfn_valid(pfn))
 509                                 return NULL;
 510                         goto out;
 511                 } else {
 512                         unsigned long off;
 513                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
 514                         if (pfn == vma->vm_pgoff + off)
 515                                 return NULL;
 516                         if (!is_cow_mapping(vma->vm_flags))
 517                                 return NULL;
 518                 }
 519         }
 520
 521 check_pfn:
 522         if (unlikely(pfn > highest_memmap_pfn)) {
 523                 print_bad_pte(vma, addr, pte, NULL);
 524                 return NULL;
 525         }
 526
 527         /*
 528          * NOTE! We still have PageReserved() pages in the page tables.
 529          * eg. VDSO mappings can cause them to exist.
 530          */
 531 out:
 532         return pfn_to_page(pfn);
 533 }
 534
 535 /*
 536  * copy one vm_area from one task to the other. Assumes the page tables
 537  * already present in the new task to be cleared in the whole range
 538  * covered by this vma.
 539  */
 540
 541 static inline void
 542 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 543                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 544                 unsigned long addr, int *rss)
 545 {
 546         unsigned long vm_flags = vma->vm_flags;
 547         pte_t pte = *src_pte;
 548         struct page *page;
 549
 550         /* pte contains position in swap or file, so copy. */
 551         if (unlikely(!pte_present(pte))) {
 552                 if (!pte_file(pte)) {
 553                         swp_entry_t entry = pte_to_swp_entry(pte);
 554
 555                         swap_duplicate(entry);
 556                         /* make sure dst_mm is on swapoff's mmlist. */
 557                         if (unlikely(list_empty(&dst_mm->mmlist))) {
 558                                 spin_lock(&mmlist_lock);
 559                                 if (list_empty(&dst_mm->mmlist))
 560                                         list_add(&dst_mm->mmlist,
 561                                                  &src_mm->mmlist);
 562                                 spin_unlock(&mmlist_lock);
 563                         }
 564                         if (is_write_migration_entry(entry) &&
 565                                         is_cow_mapping(vm_flags)) {
 566                                 /*
 567                                  * COW mappings require pages in both parent
 568                                  * and child to be set to read.
 569                                  */
 570                                 make_migration_entry_read(&entry);
 571                                 pte = swp_entry_to_pte(entry);
 572                                 set_pte_at(src_mm, addr, src_pte, pte);
 573                         }
 574                 }
 575                 goto out_set_pte;
 576         }
 577
 578         /*
 579          * If it's a COW mapping, write protect it both
 580          * in the parent and the child
 581          */
 582         if (is_cow_mapping(vm_flags)) {
 583                 ptep_set_wrprotect(src_mm, addr, src_pte);
 584                 pte = pte_wrprotect(pte);
 585         }
 586
 587         /*
 588          * If it's a shared mapping, mark it clean in
 589          * the child
 590          */
 591         if (vm_flags & VM_SHARED)
 592                 pte = pte_mkclean(pte);
 593         pte = pte_mkold(pte);
 594
 595         page = vm_normal_page(vma, addr, pte);
 596         if (page) {
 597                 get_page(page);
 598                 page_dup_rmap(page, vma, addr);
 599                 rss[!!PageAnon(page)]++;
 600         }
 601
 602 out_set_pte:
 603         set_pte_at(dst_mm, addr, dst_pte, pte);
 604 }
 605
 606 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 607                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 608                 unsigned long addr, unsigned long end)
 609 {
 610         pte_t *src_pte, *dst_pte;
 611         spinlock_t *src_ptl, *dst_ptl;
 612         int progress = 0;
 613         int rss[2];
 614
 615 again:
 616         rss[1] = rss[0] = 0;
 617         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 618         if (!dst_pte)
 619                 return -ENOMEM;
 620         src_pte = pte_offset_map_nested(src_pmd, addr);
 621         src_ptl = pte_lockptr(src_mm, src_pmd);
 622         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 623         arch_enter_lazy_mmu_mode();
 624
 625         do {
 626                 /*
 627                  * We are holding two locks at this point - either of them
 628                  * could generate latencies in another task on another CPU.
 629                  */
 630                 if (progress >= 32) {
 631                         progress = 0;
 632                         if (need_resched() ||
 633                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
 634                                 break;
 635                 }
 636                 if (pte_none(*src_pte)) {
 637                         progress++;
 638                         continue;
 639                 }
 640                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
 641                 progress += 8;
 642         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 643
 644         arch_leave_lazy_mmu_mode();
 645         spin_unlock(src_ptl);
 646         pte_unmap_nested(src_pte - 1);
 647         add_mm_rss(dst_mm, rss[0], rss[1]);
 648         pte_unmap_unlock(dst_pte - 1, dst_ptl);
 649         cond_resched();
 650         if (addr != end)
 651                 goto again;
 652         return 0;
 653 }
 654
 655 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 656                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 657                 unsigned long addr, unsigned long end)
 658 {
 659         pmd_t *src_pmd, *dst_pmd;
 660         unsigned long next;
 661
 662         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 663         if (!dst_pmd)
 664                 return -ENOMEM;
 665         src_pmd = pmd_offset(src_pud, addr);
 666         do {
 667                 next = pmd_addr_end(addr, end);
 668                 if (pmd_none_or_clear_bad(src_pmd))
 669                         continue;
 670                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
 671                                                 vma, addr, next))
 672                         return -ENOMEM;
 673         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 674         return 0;
 675 }
 676
 677 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 678                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
 679                 unsigned long addr, unsigned long end)
 680 {
 681         pud_t *src_pud, *dst_pud;
 682         unsigned long next;
 683
 684         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
 685         if (!dst_pud)
 686                 return -ENOMEM;
 687         src_pud = pud_offset(src_pgd, addr);
 688         do {
 689                 next = pud_addr_end(addr, end);
 690                 if (pud_none_or_clear_bad(src_pud))
 691                         continue;
 692                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
 693                                                 vma, addr, next))
 694                         return -ENOMEM;
 695         } while (dst_pud++, src_pud++, addr = next, addr != end);
 696         return 0;
 697 }
 698
 699 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 700                 struct vm_area_struct *vma)
 701 {
 702         pgd_t *src_pgd, *dst_pgd;
 703         unsigned long next;
 704         unsigned long addr = vma->vm_start;
 705         unsigned long end = vma->vm_end;
 706         int ret;
 707
 708         /*
 709          * Don't copy ptes where a page fault will fill them correctly.
 710          * Fork becomes much lighter when there are big shared or private
 711          * readonly mappings. The tradeoff is that copy_page_range is more
 712          * efficient than faulting.
 713          */
 714         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
 715                 if (!vma->anon_vma)
 716                         return 0;
 717         }
 718
 719         if (is_vm_hugetlb_page(vma))
 720                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 721
 722         if (unlikely(is_pfn_mapping(vma))) {
 723                 /*
 724                  * We do not free on error cases below as remove_vma
 725                  * gets called on error from higher level routine
 726                  */
 727                 ret = track_pfn_vma_copy(vma);
 728                 if (ret)
 729                         return ret;
 730         }
 731
 732         /*
 733          * We need to invalidate the secondary MMU mappings only when
 734          * there could be a permission downgrade on the ptes of the
 735          * parent mm. And a permission downgrade will only happen if
 736          * is_cow_mapping() returns true.
 737          */
 738         if (is_cow_mapping(vma->vm_flags))
 739                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
 740
 741         ret = 0;
 742         dst_pgd = pgd_offset(dst_mm, addr);
 743         src_pgd = pgd_offset(src_mm, addr);
 744         do {
 745                 next = pgd_addr_end(addr, end);
 746                 if (pgd_none_or_clear_bad(src_pgd))
 747                         continue;
 748                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
 749                                             vma, addr, next))) {
 750                         ret = -ENOMEM;
 751                         break;
 752                 }
 753         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
 754
 755         if (is_cow_mapping(vma->vm_flags))
 756                 mmu_notifier_invalidate_range_end(src_mm,
 757                                                   vma->vm_start, end);
 758         return ret;
 759 }
 760
 761 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 762                                 struct vm_area_struct *vma, pmd_t *pmd,
 763                                 unsigned long addr, unsigned long end,
 764                                 long *zap_work, struct zap_details *details)
 765 {
 766         struct mm_struct *mm = tlb->mm;
 767         pte_t *pte;
 768         spinlock_t *ptl;
 769         int file_rss = 0;
 770         int anon_rss = 0;
 771
 772         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 773         arch_enter_lazy_mmu_mode();
 774         do {
 775                 pte_t ptent = *pte;
 776                 if (pte_none(ptent)) {
 777                         (*zap_work)--;
 778                         continue;
 779                 }
 780
 781                 (*zap_work) -= PAGE_SIZE;
 782
 783                 if (pte_present(ptent)) {
 784                         struct page *page;
 785
 786                         page = vm_normal_page(vma, addr, ptent);
 787                         if (unlikely(details) && page) {
 788                                 /*
 789                                  * unmap_shared_mapping_pages() wants to
 790                                  * invalidate cache without truncating:
 791                                  * unmap shared but keep private pages.
 792                                  */
 793                                 if (details->check_mapping &&
 794                                     details->check_mapping != page->mapping)
 795                                         continue;
 796                                 /*
 797                                  * Each page->index must be checked when
 798                                  * invalidating or truncating nonlinear.
 799                                  */
 800                                 if (details->nonlinear_vma &&
 801                                     (page->index < details->first_index ||
 802                                      page->index > details->last_index))
 803                                         continue;
 804                         }
 805                         ptent = ptep_get_and_clear_full(mm, addr, pte,
 806                                                         tlb->fullmm);
 807                         tlb_remove_tlb_entry(tlb, pte, addr);
 808                         if (unlikely(!page))
 809                                 continue;
 810                         if (unlikely(details) && details->nonlinear_vma
 811                             && linear_page_index(details->nonlinear_vma,
 812                                                 addr) != page->index)
 813                                 set_pte_at(mm, addr, pte,
 814                                            pgoff_to_pte(page->index));
 815                         if (PageAnon(page))
 816                                 anon_rss--;
 817                         else {
 818                                 if (pte_dirty(ptent))
 819                                         set_page_dirty(page);
 820                                 if (pte_young(ptent) &&
 821                                     likely(!VM_SequentialReadHint(vma)))
 822                                         mark_page_accessed(page);
 823                                 file_rss--;
 824                         }
 825                         page_remove_rmap(page);
 826                         if (unlikely(page_mapcount(page) < 0))
 827                                 print_bad_pte(vma, addr, ptent, page);
 828                         tlb_remove_page(tlb, page);
 829                         continue;
 830                 }
 831                 /*
 832                  * If details->check_mapping, we leave swap entries;
 833                  * if details->nonlinear_vma, we leave file entries.
 834                  */
 835                 if (unlikely(details))
 836                         continue;
 837                 if (pte_file(ptent)) {
 838                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
 839                                 print_bad_pte(vma, addr, ptent, NULL);
 840                 } else if
 841                   (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
 842                         print_bad_pte(vma, addr, ptent, NULL);
 843                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 844         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
 845
 846         add_mm_rss(mm, file_rss, anon_rss);
 847         arch_leave_lazy_mmu_mode();
 848         pte_unmap_unlock(pte - 1, ptl);
 849
 850         return addr;
 851 }
 852
 853 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 854                                 struct vm_area_struct *vma, pud_t *pud,
 855                                 unsigned long addr, unsigned long end,
 856                                 long *zap_work, struct zap_details *details)
 857 {
 858         pmd_t *pmd;
 859         unsigned long next;
 860
 861         pmd = pmd_offset(pud, addr);
 862         do {
 863                 next = pmd_addr_end(addr, end);
 864                 if (pmd_none_or_clear_bad(pmd)) {
 865                         (*zap_work)--;
 866                         continue;
 867                 }
 868                 next = zap_pte_range(tlb, vma, pmd, addr, next,
 869                                                 zap_work, details);
 870         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
 871
 872         return addr;
 873 }
 874
 875 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 876                                 struct vm_area_struct *vma, pgd_t *pgd,
 877                                 unsigned long addr, unsigned long end,
 878                                 long *zap_work, struct zap_details *details)
 879 {
 880         pud_t *pud;
 881         unsigned long next;
 882
 883         pud = pud_offset(pgd, addr);
 884         do {
 885                 next = pud_addr_end(addr, end);
 886                 if (pud_none_or_clear_bad(pud)) {
 887                         (*zap_work)--;
 888                         continue;
 889                 }
 890                 next = zap_pmd_range(tlb, vma, pud, addr, next,
 891                                                 zap_work, details);
 892         } while (pud++, addr = next, (addr != end && *zap_work > 0));
 893
 894         return addr;
 895 }
 896
 897 static unsigned long unmap_page_range(struct mmu_gather *tlb,
 898                                 struct vm_area_struct *vma,
 899                                 unsigned long addr, unsigned long end,
 900                                 long *zap_work, struct zap_details *details)
 901 {
 902         pgd_t *pgd;
 903         unsigned long next;
 904
 905         if (details && !details->check_mapping && !details->nonlinear_vma)
 906                 details = NULL;
 907
 908         BUG_ON(addr >= end);
 909         tlb_start_vma(tlb, vma);
 910         pgd = pgd_offset(vma->vm_mm, addr);
 911         do {
 912                 next = pgd_addr_end(addr, end);
 913                 if (pgd_none_or_clear_bad(pgd)) {
 914                         (*zap_work)--;
 915                         continue;
 916                 }
 917                 next = zap_pud_range(tlb, vma, pgd, addr, next,
 918                                                 zap_work, details);
 919         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
 920         tlb_end_vma(tlb, vma);
 921
 922         return addr;
 923 }
 924
 925 #ifdef CONFIG_PREEMPT
 926 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
 927 #else
 928 /* No preempt: go for improved straight-line efficiency */
 929 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
 930 #endif
 931
 932 /**
 933  * unmap_vmas - unmap a range of memory covered by a list of vma's
 934  * @tlbp: address of the caller's struct mmu_gather
 935  * @vma: the starting vma
 936  * @start_addr: virtual address at which to start unmapping
 937  * @end_addr: virtual address at which to end unmapping
 938  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 939  * @details: details of nonlinear truncation or shared cache invalidation
 940  *
 941  * Returns the end address of the unmapping (restart addr if interrupted).
 942  *
 943  * Unmap all pages in the vma list.
 944  *
 945  * We aim to not hold locks for too long (for scheduling latency reasons).
 946  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
 947  * return the ending mmu_gather to the caller.
 948  *
 949  * Only addresses between `start' and `end' will be unmapped.
 950  *
 951  * The VMA list must be sorted in ascending virtual address order.
 952  *
 953  * unmap_vmas() assumes that the caller will flush the whole unmapped address
 954  * range after unmap_vmas() returns.  So the only responsibility here is to
 955  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 956  * drops the lock and schedules.
 957  */
 958 unsigned long unmap_vmas(struct mmu_gather **tlbp,
 959                 struct vm_area_struct *vma, unsigned long start_addr,
 960                 unsigned long end_addr, unsigned long *nr_accounted,
 961                 struct zap_details *details)
 962 {
 963         long zap_work = ZAP_BLOCK_SIZE;
 964         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
 965         int tlb_start_valid = 0;
 966         unsigned long start = start_addr;
 967         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
 968         int fullmm = (*tlbp)->fullmm;
 969         struct mm_struct *mm = vma->vm_mm;
 970
 971         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
 972         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
 973                 unsigned long end;
 974
 975                 start = max(vma->vm_start, start_addr);
 976                 if (start >= vma->vm_end)
 977                         continue;
 978                 end = min(vma->vm_end, end_addr);
 979                 if (end <= vma->vm_start)
 980                         continue;
 981
 982                 if (vma->vm_flags & VM_ACCOUNT)
 983                         *nr_accounted += (end - start) >> PAGE_SHIFT;
 984
 985                 if (unlikely(is_pfn_mapping(vma)))
 986                         untrack_pfn_vma(vma, 0, 0);
 987
 988                 while (start != end) {
 989                         if (!tlb_start_valid) {
 990                                 tlb_start = start;
 991                                 tlb_start_valid = 1;
 992                         }
 993
 994                         if (unlikely(is_vm_hugetlb_page(vma))) {
 995                                 /*
 996                                  * It is undesirable to test vma->vm_file as it
 997                                  * should be non-null for valid hugetlb area.
 998                                  * However, vm_file will be NULL in the error
 999                                  * cleanup path of do_mmap_pgoff. When
1000                                  * hugetlbfs ->mmap method fails,
1001                                  * do_mmap_pgoff() nullifies vma->vm_file
1002                                  * before calling this function to clean up.
1003                                  * Since no pte has actually been setup, it is
1004                                  * safe to do nothing in this case.
1005                                  */
1006                                 if (vma->vm_file) {
1007                                         unmap_hugepage_range(vma, start, end, NULL);
1008                                         zap_work -= (end - start) /
1009                                         pages_per_huge_page(hstate_vma(vma));
1010                                 }
1011
1012                                 start = end;
1013                         } else
1014                                 start = unmap_page_range(*tlbp, vma,
1015                                                 start, end, &zap_work, details);
1016
1017                         if (zap_work > 0) {
1018                                 BUG_ON(start != end);
1019                                 break;
1020                         }
1021
1022                         tlb_finish_mmu(*tlbp, tlb_start, start);
1023
1024                         if (need_resched() ||
1025                                 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1026                                 if (i_mmap_lock) {
1027                                         *tlbp = NULL;
1028                                         goto out;
1029                                 }
1030                                 cond_resched();
1031                         }
1032
1033                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1034                         tlb_start_valid = 0;
1035                         zap_work = ZAP_BLOCK_SIZE;
1036                 }
1037         }
1038 out:
1039         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1040         return start;   /* which is now the end (or restart) address */
1041 }
1042
1043 /**
1044  * zap_page_range - remove user pages in a given range
1045  * @vma: vm_area_struct holding the applicable pages
1046  * @address: starting address of pages to zap
1047  * @size: number of bytes to zap
1048  * @details: details of nonlinear truncation or shared cache invalidation
1049  */
1050 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1051                 unsigned long size, struct zap_details *details)
1052 {
1053         struct mm_struct *mm = vma->vm_mm;
1054         struct mmu_gather *tlb;
1055         unsigned long end = address + size;
1056         unsigned long nr_accounted = 0;
1057
1058         lru_add_drain();
1059         tlb = tlb_gather_mmu(mm, 0);
1060         update_hiwater_rss(mm);
1061         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1062         if (tlb)
1063                 tlb_finish_mmu(tlb, address, end);
1064         return end;
1065 }
1066
1067 /**
1068  * zap_vma_ptes - remove ptes mapping the vma
1069  * @vma: vm_area_struct holding ptes to be zapped
1070  * @address: starting address of pages to zap
1071  * @size: number of bytes to zap
1072  *
1073  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1074  *
1075  * The entire address range must be fully contained within the vma.
1076  *
1077  * Returns 0 if successful.
1078  */
1079 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1080                 unsigned long size)
1081 {
1082         if (address < vma->vm_start || address + size > vma->vm_end ||
1083                         !(vma->vm_flags & VM_PFNMAP))
1084                 return -1;
1085         zap_page_range(vma, address, size, NULL);
1086         return 0;
1087 }
1088 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1089
1090 /*
1091  * Do a quick page-table lookup for a single page.
1092  */
1093 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1094                         unsigned int flags)
1095 {
1096         pgd_t *pgd;
1097         pud_t *pud;
1098         pmd_t *pmd;
1099         pte_t *ptep, pte;
1100         spinlock_t *ptl;
1101         struct page *page;
1102         struct mm_struct *mm = vma->vm_mm;
1103
1104         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1105         if (!IS_ERR(page)) {
1106                 BUG_ON(flags & FOLL_GET);
1107                 goto out;
1108         }
1109
1110         page = NULL;
1111         pgd = pgd_offset(mm, address);
1112         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1113                 goto no_page_table;
1114
1115         pud = pud_offset(pgd, address);
1116         if (pud_none(*pud))
1117                 goto no_page_table;
1118         if (pud_huge(*pud)) {
1119                 BUG_ON(flags & FOLL_GET);
1120                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1121                 goto out;
1122         }
1123         if (unlikely(pud_bad(*pud)))
1124                 goto no_page_table;
1125
1126         pmd = pmd_offset(pud, address);
1127         if (pmd_none(*pmd))
1128                 goto no_page_table;
1129         if (pmd_huge(*pmd)) {
1130                 BUG_ON(flags & FOLL_GET);
1131                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1132                 goto out;
1133         }
1134         if (unlikely(pmd_bad(*pmd)))
1135                 goto no_page_table;
1136
1137         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1138
1139         pte = *ptep;
1140         if (!pte_present(pte))
1141                 goto no_page;
1142         if ((flags & FOLL_WRITE) && !pte_write(pte))
1143                 goto unlock;
1144         page = vm_normal_page(vma, address, pte);
1145         if (unlikely(!page))
1146                 goto bad_page;
1147
1148         if (flags & FOLL_GET)
1149                 get_page(page);
1150         if (flags & FOLL_TOUCH) {
1151                 if ((flags & FOLL_WRITE) &&
1152                     !pte_dirty(pte) && !PageDirty(page))
1153                         set_page_dirty(page);
1154                 /*
1155                  * pte_mkyoung() would be more correct here, but atomic care
1156                  * is needed to avoid losing the dirty bit: it is easier to use
1157                  * mark_page_accessed().
1158                  */
1159                 mark_page_accessed(page);
1160         }
1161 unlock:
1162         pte_unmap_unlock(ptep, ptl);
1163 out:
1164         return page;
1165
1166 bad_page:
1167         pte_unmap_unlock(ptep, ptl);
1168         return ERR_PTR(-EFAULT);
1169
1170 no_page:
1171         pte_unmap_unlock(ptep, ptl);
1172         if (!pte_none(pte))
1173                 return page;
1174         /* Fall through to ZERO_PAGE handling */
1175 no_page_table:
1176         /*
1177          * When core dumping an enormous anonymous area that nobody
1178          * has touched so far, we don't want to allocate page tables.
1179          */
1180         if (flags & FOLL_ANON) {
1181                 page = ZERO_PAGE(0);
1182                 if (flags & FOLL_GET)
1183                         get_page(page);
1184                 BUG_ON(flags & FOLL_WRITE);
1185         }
1186         return page;
1187 }
1188
1189 /* Can we do the FOLL_ANON optimization? */
1190 static inline int use_zero_page(struct vm_area_struct *vma)
1191 {
1192         /*
1193          * We don't want to optimize FOLL_ANON for make_pages_present()
1194          * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
1195          * we want to get the page from the page tables to make sure
1196          * that we serialize and update with any other user of that
1197          * mapping.
1198          */
1199         if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
1200                 return 0;
1201         /*
1202          * And if we have a fault routine, it's not an anonymous region.
1203          */
1204         return !vma->vm_ops || !vma->vm_ops->fault;
1205 }
1206
1207
1208
1209 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1210                      unsigned long start, int len, int flags,
1211                 struct page **pages, struct vm_area_struct **vmas)
1212 {
1213         int i;
1214         unsigned int vm_flags = 0;
1215         int write = !!(flags & GUP_FLAGS_WRITE);
1216         int force = !!(flags & GUP_FLAGS_FORCE);
1217         int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
1218         int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL);
1219
1220         if (len <= 0)
1221                 return 0;
1222         /*
1223          * Require read or write permissions.
1224          * If 'force' is set, we only require the "MAY" flags.
1225          */
1226         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1227         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1228         i = 0;
1229
1230         do {
1231                 struct vm_area_struct *vma;
1232                 unsigned int foll_flags;
1233
1234                 vma = find_extend_vma(mm, start);
1235                 if (!vma && in_gate_area(tsk, start)) {
1236                         unsigned long pg = start & PAGE_MASK;
1237                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1238                         pgd_t *pgd;
1239                         pud_t *pud;
1240                         pmd_t *pmd;
1241                         pte_t *pte;
1242
1243                         /* user gate pages are read-only */
1244                         if (!ignore && write)
1245                                 return i ? : -EFAULT;
1246                         if (pg > TASK_SIZE)
1247                                 pgd = pgd_offset_k(pg);
1248                         else
1249                                 pgd = pgd_offset_gate(mm, pg);
1250                         BUG_ON(pgd_none(*pgd));
1251                         pud = pud_offset(pgd, pg);
1252                         BUG_ON(pud_none(*pud));
1253                         pmd = pmd_offset(pud, pg);
1254                         if (pmd_none(*pmd))
1255                                 return i ? : -EFAULT;
1256                         pte = pte_offset_map(pmd, pg);
1257                         if (pte_none(*pte)) {
1258                                 pte_unmap(pte);
1259                                 return i ? : -EFAULT;
1260                         }
1261                         if (pages) {
1262                                 struct page *page = vm_normal_page(gate_vma, start, *pte);
1263                                 pages[i] = page;
1264                                 if (page)
1265                                         get_page(page);
1266                         }
1267                         pte_unmap(pte);
1268                         if (vmas)
1269                                 vmas[i] = gate_vma;
1270                         i++;
1271                         start += PAGE_SIZE;
1272                         len--;
1273                         continue;
1274                 }
1275
1276                 if (!vma ||
1277                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1278                     (!ignore && !(vm_flags & vma->vm_flags)))
1279                         return i ? : -EFAULT;
1280
1281                 if (is_vm_hugetlb_page(vma)) {
1282                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1283                                                 &start, &len, i, write);
1284                         continue;
1285                 }
1286
1287                 foll_flags = FOLL_TOUCH;
1288                 if (pages)
1289                         foll_flags |= FOLL_GET;
1290                 if (!write && use_zero_page(vma))
1291                         foll_flags |= FOLL_ANON;
1292
1293                 do {
1294                         struct page *page;
1295
1296                         /*
1297                          * If we have a pending SIGKILL, don't keep faulting
1298                          * pages and potentially allocating memory, unless
1299                          * current is handling munlock--e.g., on exit. In
1300                          * that case, we are not allocating memory.  Rather,
1301                          * we're only unlocking already resident/mapped pages.
1302                          */
1303                         if (unlikely(!ignore_sigkill &&
1304                                         fatal_signal_pending(current)))
1305                                 return i ? i : -ERESTARTSYS;
1306
1307                         if (write)
1308                                 foll_flags |= FOLL_WRITE;
1309
1310                         cond_resched();
1311                         while (!(page = follow_page(vma, start, foll_flags))) {
1312                                 int ret;
1313                                 ret = handle_mm_fault(mm, vma, start,
1314                                                 foll_flags & FOLL_WRITE);
1315                                 if (ret & VM_FAULT_ERROR) {
1316                                         if (ret & VM_FAULT_OOM)
1317                                                 return i ? i : -ENOMEM;
1318                                         else if (ret & VM_FAULT_SIGBUS)
1319                                                 return i ? i : -EFAULT;
1320                                         BUG();
1321                                 }
1322                                 if (ret & VM_FAULT_MAJOR)
1323                                         tsk->maj_flt++;
1324                                 else
1325                                         tsk->min_flt++;
1326
1327                                 /*
1328                                  * The VM_FAULT_WRITE bit tells us that
1329                                  * do_wp_page has broken COW when necessary,
1330                                  * even if maybe_mkwrite decided not to set
1331                                  * pte_write. We can thus safely do subsequent
1332                                  * page lookups as if they were reads. But only
1333                                  * do so when looping for pte_write is futile:
1334                                  * in some cases userspace may also be wanting
1335                                  * to write to the gotten user page, which a
1336                                  * read fault here might prevent (a readonly
1337                                  * page might get reCOWed by userspace write).
1338                                  */
1339                                 if ((ret & VM_FAULT_WRITE) &&
1340                                     !(vma->vm_flags & VM_WRITE))
1341                                         foll_flags &= ~FOLL_WRITE;
1342
1343                                 cond_resched();
1344                         }
1345                         if (IS_ERR(page))
1346                                 return i ? i : PTR_ERR(page);
1347                         if (pages) {
1348                                 pages[i] = page;
1349
1350                                 flush_anon_page(vma, page, start);
1351                                 flush_dcache_page(page);
1352                         }
1353                         if (vmas)
1354                                 vmas[i] = vma;
1355                         i++;
1356                         start += PAGE_SIZE;
1357                         len--;
1358                 } while (len && start < vma->vm_end);
1359         } while (len);
1360         return i;
1361 }
1362
1363 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1364                 unsigned long start, int len, int write, int force,
1365                 struct page **pages, struct vm_area_struct **vmas)
1366 {
1367         int flags = 0;
1368
1369         if (write)
1370                 flags |= GUP_FLAGS_WRITE;
1371         if (force)
1372                 flags |= GUP_FLAGS_FORCE;
1373
1374         return __get_user_pages(tsk, mm,
1375                                 start, len, flags,
1376                                 pages, vmas);
1377 }
1378
1379 EXPORT_SYMBOL(get_user_pages);
1380
1381 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1382                         spinlock_t **ptl)
1383 {
1384         pgd_t * pgd = pgd_offset(mm, addr);
1385         pud_t * pud = pud_alloc(mm, pgd, addr);
1386         if (pud) {
1387                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1388                 if (pmd)
1389                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1390         }
1391         return NULL;
1392 }
1393
1394 /*
1395  * This is the old fallback for page remapping.
1396  *
1397  * For historical reasons, it only allows reserved pages. Only
1398  * old drivers should use this, and they needed to mark their
1399  * pages reserved for the old functions anyway.
1400  */
1401 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1402                         struct page *page, pgprot_t prot)
1403 {
1404         struct mm_struct *mm = vma->vm_mm;
1405         int retval;
1406         pte_t *pte;
1407         spinlock_t *ptl;
1408
1409         retval = -EINVAL;
1410         if (PageAnon(page))
1411                 goto out;
1412         retval = -ENOMEM;
1413         flush_dcache_page(page);
1414         pte = get_locked_pte(mm, addr, &ptl);
1415         if (!pte)
1416                 goto out;
1417         retval = -EBUSY;
1418         if (!pte_none(*pte))
1419                 goto out_unlock;
1420
1421         /* Ok, finally just insert the thing.. */
1422         get_page(page);
1423         inc_mm_counter(mm, file_rss);
1424         page_add_file_rmap(page);
1425         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1426
1427         retval = 0;
1428         pte_unmap_unlock(pte, ptl);
1429         return retval;
1430 out_unlock:
1431         pte_unmap_unlock(pte, ptl);
1432 out:
1433         return retval;
1434 }
1435
1436 /**
1437  * vm_insert_page - insert single page into user vma
1438  * @vma: user vma to map to
1439  * @addr: target user address of this page
1440  * @page: source kernel page
1441  *
1442  * This allows drivers to insert individual pages they've allocated
1443  * into a user vma.
1444  *
1445  * The page has to be a nice clean _individual_ kernel allocation.
1446  * If you allocate a compound page, you need to have marked it as
1447  * such (__GFP_COMP), or manually just split the page up yourself
1448  * (see split_page()).
1449  *
1450  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1451  * took an arbitrary page protection parameter. This doesn't allow
1452  * that. Your vma protection will have to be set up correctly, which
1453  * means that if you want a shared writable mapping, you'd better
1454  * ask for a shared writable mapping!
1455  *
1456  * The page does not need to be reserved.
1457  */
1458 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1459                         struct page *page)
1460 {
1461         if (addr < vma->vm_start || addr >= vma->vm_end)
1462                 return -EFAULT;
1463         if (!page_count(page))
1464                 return -EINVAL;
1465         vma->vm_flags |= VM_INSERTPAGE;
1466         return insert_page(vma, addr, page, vma->vm_page_prot);
1467 }
1468 EXPORT_SYMBOL(vm_insert_page);
1469
1470 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1471                         unsigned long pfn, pgprot_t prot)
1472 {
1473         struct mm_struct *mm = vma->vm_mm;
1474         int retval;
1475         pte_t *pte, entry;
1476         spinlock_t *ptl;
1477
1478         retval = -ENOMEM;
1479         pte = get_locked_pte(mm, addr, &ptl);
1480         if (!pte)
1481                 goto out;
1482         retval = -EBUSY;
1483         if (!pte_none(*pte))
1484                 goto out_unlock;
1485
1486         /* Ok, finally just insert the thing.. */
1487         entry = pte_mkspecial(pfn_pte(pfn, prot));
1488         set_pte_at(mm, addr, pte, entry);
1489         update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */
1490
1491         retval = 0;
1492 out_unlock:
1493         pte_unmap_unlock(pte, ptl);
1494 out:
1495         return retval;
1496 }
1497
1498 /**
1499  * vm_insert_pfn - insert single pfn into user vma
1500  * @vma: user vma to map to
1501  * @addr: target user address of this page
1502  * @pfn: source kernel pfn
1503  *
1504  * Similar to vm_inert_page, this allows drivers to insert individual pages
1505  * they've allocated into a user vma. Same comments apply.
1506  *
1507  * This function should only be called from a vm_ops->fault handler, and
1508  * in that case the handler should return NULL.
1509  *
1510  * vma cannot be a COW mapping.
1511  *
1512  * As this is called only for pages that do not currently exist, we
1513  * do not need to flush old virtual caches or the TLB.
1514  */
1515 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1516                         unsigned long pfn)
1517 {
1518         int ret;
1519         pgprot_t pgprot = vma->vm_page_prot;
1520         /*
1521          * Technically, architectures with pte_special can avoid all these
1522          * restrictions (same for remap_pfn_range).  However we would like
1523          * consistency in testing and feature parity among all, so we should
1524          * try to keep these invariants in place for everybody.
1525          */
1526         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1527         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1528                                                 (VM_PFNMAP|VM_MIXEDMAP));
1529         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1530         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1531
1532         if (addr < vma->vm_start || addr >= vma->vm_end)
1533                 return -EFAULT;
1534         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1535                 return -EINVAL;
1536
1537         ret = insert_pfn(vma, addr, pfn, pgprot);
1538
1539         if (ret)
1540                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1541
1542         return ret;
1543 }
1544 EXPORT_SYMBOL(vm_insert_pfn);
1545
1546 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1547                         unsigned long pfn)
1548 {
1549         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1550
1551         if (addr < vma->vm_start || addr >= vma->vm_end)
1552                 return -EFAULT;
1553
1554         /*
1555          * If we don't have pte special, then we have to use the pfn_valid()
1556          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1557          * refcount the page if pfn_valid is true (hence insert_page rather
1558          * than insert_pfn).
1559          */
1560         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1561                 struct page *page;
1562
1563                 page = pfn_to_page(pfn);
1564                 return insert_page(vma, addr, page, vma->vm_page_prot);
1565         }
1566         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1567 }
1568 EXPORT_SYMBOL(vm_insert_mixed);
1569
1570 /*
1571  * maps a range of physical memory into the requested pages. the old
1572  * mappings are removed. any references to nonexistent pages results
1573  * in null mappings (currently treated as "copy-on-access")
1574  */
1575 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1576                         unsigned long addr, unsigned long end,
1577                         unsigned long pfn, pgprot_t prot)
1578 {
1579         pte_t *pte;
1580         spinlock_t *ptl;
1581
1582         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1583         if (!pte)
1584                 return -ENOMEM;
1585         arch_enter_lazy_mmu_mode();
1586         do {
1587                 BUG_ON(!pte_none(*pte));
1588                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1589                 pfn++;
1590         } while (pte++, addr += PAGE_SIZE, addr != end);
1591         arch_leave_lazy_mmu_mode();
1592         pte_unmap_unlock(pte - 1, ptl);
1593         return 0;
1594 }
1595
1596 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1597                         unsigned long addr, unsigned long end,
1598                         unsigned long pfn, pgprot_t prot)
1599 {
1600         pmd_t *pmd;
1601         unsigned long next;
1602
1603         pfn -= addr >> PAGE_SHIFT;
1604         pmd = pmd_alloc(mm, pud, addr);
1605         if (!pmd)
1606                 return -ENOMEM;
1607         do {
1608                 next = pmd_addr_end(addr, end);
1609                 if (remap_pte_range(mm, pmd, addr, next,
1610                                 pfn + (addr >> PAGE_SHIFT), prot))
1611                         return -ENOMEM;
1612         } while (pmd++, addr = next, addr != end);
1613         return 0;
1614 }
1615
1616 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1617                         unsigned long addr, unsigned long end,
1618                         unsigned long pfn, pgprot_t prot)
1619 {
1620         pud_t *pud;
1621         unsigned long next;
1622
1623         pfn -= addr >> PAGE_SHIFT;
1624         pud = pud_alloc(mm, pgd, addr);
1625         if (!pud)
1626                 return -ENOMEM;
1627         do {
1628                 next = pud_addr_end(addr, end);
1629                 if (remap_pmd_range(mm, pud, addr, next,
1630                                 pfn + (addr >> PAGE_SHIFT), prot))
1631                         return -ENOMEM;
1632         } while (pud++, addr = next, addr != end);
1633         return 0;
1634 }
1635
1636 /**
1637  * remap_pfn_range - remap kernel memory to userspace
1638  * @vma: user vma to map to
1639  * @addr: target user address to start at
1640  * @pfn: physical address of kernel memory
1641  * @size: size of map area
1642  * @prot: page protection flags for this mapping
1643  *
1644  *  Note: this is only safe if the mm semaphore is held when called.
1645  */
1646 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1647                     unsigned long pfn, unsigned long size, pgprot_t prot)
1648 {
1649         pgd_t *pgd;
1650         unsigned long next;
1651         unsigned long end = addr + PAGE_ALIGN(size);
1652         struct mm_struct *mm = vma->vm_mm;
1653         int err;
1654
1655         /*
1656          * Physically remapped pages are special. Tell the
1657          * rest of the world about it:
1658          *   VM_IO tells people not to look at these pages
1659          *      (accesses can have side effects).
1660          *   VM_RESERVED is specified all over the place, because
1661          *      in 2.4 it kept swapout's vma scan off this vma; but
1662          *      in 2.6 the LRU scan won't even find its pages, so this
1663          *      flag means no more than count its pages in reserved_vm,
1664          *      and omit it from core dump, even when VM_IO turned off.
1665          *   VM_PFNMAP tells the core MM that the base pages are just
1666          *      raw PFN mappings, and do not have a "struct page" associated
1667          *      with them.
1668          *
1669          * There's a horrible special case to handle copy-on-write
1670          * behaviour that some programs depend on. We mark the "original"
1671          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1672          */
1673         if (addr == vma->vm_start && end == vma->vm_end) {
1674                 vma->vm_pgoff = pfn;
1675                 vma->vm_flags |= VM_PFN_AT_MMAP;
1676         } else if (is_cow_mapping(vma->vm_flags))
1677                 return -EINVAL;
1678
1679         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1680
1681         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1682         if (err) {
1683                 /*
1684                  * To indicate that track_pfn related cleanup is not
1685                  * needed from higher level routine calling unmap_vmas
1686                  */
1687                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1688                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
1689                 return -EINVAL;
1690         }
1691
1692         BUG_ON(addr >= end);
1693         pfn -= addr >> PAGE_SHIFT;
1694         pgd = pgd_offset(mm, addr);
1695         flush_cache_range(vma, addr, end);
1696         do {
1697                 next = pgd_addr_end(addr, end);
1698                 err = remap_pud_range(mm, pgd, addr, next,
1699                                 pfn + (addr >> PAGE_SHIFT), prot);
1700                 if (err)
1701                         break;
1702         } while (pgd++, addr = next, addr != end);
1703
1704         if (err)
1705                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
1706
1707         return err;
1708 }
1709 EXPORT_SYMBOL(remap_pfn_range);
1710
1711 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1712                                      unsigned long addr, unsigned long end,
1713                                      pte_fn_t fn, void *data)
1714 {
1715         pte_t *pte;
1716         int err;
1717         pgtable_t token;
1718         spinlock_t *uninitialized_var(ptl);
1719
1720         pte = (mm == &init_mm) ?
1721                 pte_alloc_kernel(pmd, addr) :
1722                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1723         if (!pte)
1724                 return -ENOMEM;
1725
1726         BUG_ON(pmd_huge(*pmd));
1727
1728         arch_enter_lazy_mmu_mode();
1729
1730         token = pmd_pgtable(*pmd);
1731
1732         do {
1733                 err = fn(pte, token, addr, data);
1734                 if (err)
1735                         break;
1736         } while (pte++, addr += PAGE_SIZE, addr != end);
1737
1738         arch_leave_lazy_mmu_mode();
1739
1740         if (mm != &init_mm)
1741                 pte_unmap_unlock(pte-1, ptl);
1742         return err;
1743 }
1744
1745 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1746                                      unsigned long addr, unsigned long end,
1747                                      pte_fn_t fn, void *data)
1748 {
1749         pmd_t *pmd;
1750         unsigned long next;
1751         int err;
1752
1753         BUG_ON(pud_huge(*pud));
1754
1755         pmd = pmd_alloc(mm, pud, addr);
1756         if (!pmd)
1757                 return -ENOMEM;
1758         do {
1759                 next = pmd_addr_end(addr, end);
1760                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1761                 if (err)
1762                         break;
1763         } while (pmd++, addr = next, addr != end);
1764         return err;
1765 }
1766
1767 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1768                                      unsigned long addr, unsigned long end,
1769                                      pte_fn_t fn, void *data)
1770 {
1771         pud_t *pud;
1772         unsigned long next;
1773         int err;
1774
1775         pud = pud_alloc(mm, pgd, addr);
1776         if (!pud)
1777                 return -ENOMEM;
1778         do {
1779                 next = pud_addr_end(addr, end);
1780                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1781                 if (err)
1782                         break;
1783         } while (pud++, addr = next, addr != end);
1784         return err;
1785 }
1786
1787 /*
1788  * Scan a region of virtual memory, filling in page tables as necessary
1789  * and calling a provided function on each leaf page table.
1790  */
1791 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1792                         unsigned long size, pte_fn_t fn, void *data)
1793 {
1794         pgd_t *pgd;
1795         unsigned long next;
1796         unsigned long start = addr, end = addr + size;
1797         int err;
1798
1799         BUG_ON(addr >= end);
1800         mmu_notifier_invalidate_range_start(mm, start, end);
1801         pgd = pgd_offset(mm, addr);
1802         do {
1803                 next = pgd_addr_end(addr, end);
1804                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1805                 if (err)
1806                         break;
1807         } while (pgd++, addr = next, addr != end);
1808         mmu_notifier_invalidate_range_end(mm, start, end);
1809         return err;
1810 }
1811 EXPORT_SYMBOL_GPL(apply_to_page_range);
1812
1813 /*
1814  * handle_pte_fault chooses page fault handler according to an entry
1815  * which was read non-atomically.  Before making any commitment, on
1816  * those architectures or configurations (e.g. i386 with PAE) which
1817  * might give a mix of unmatched parts, do_swap_page and do_file_page
1818  * must check under lock before unmapping the pte and proceeding
1819  * (but do_wp_page is only called after already making such a check;
1820  * and do_anonymous_page and do_no_page can safely check later on).
1821  */
1822 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1823                                 pte_t *page_table, pte_t orig_pte)
1824 {
1825         int same = 1;
1826 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1827         if (sizeof(pte_t) > sizeof(unsigned long)) {
1828                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1829                 spin_lock(ptl);
1830                 same = pte_same(*page_table, orig_pte);
1831                 spin_unlock(ptl);
1832         }
1833 #endif
1834         pte_unmap(page_table);
1835         return same;
1836 }
1837
1838 /*
1839  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1840  * servicing faults for write access.  In the normal case, do always want
1841  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1842  * that do not have writing enabled, when used by access_process_vm.
1843  */
1844 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1845 {
1846         if (likely(vma->vm_flags & VM_WRITE))
1847                 pte = pte_mkwrite(pte);
1848         return pte;
1849 }
1850
1851 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1852 {
1853         /*
1854          * If the source page was a PFN mapping, we don't have
1855          * a "struct page" for it. We do a best-effort copy by
1856          * just copying from the original user address. If that
1857          * fails, we just zero-fill it. Live with it.
1858          */
1859         if (unlikely(!src)) {
1860                 void *kaddr = kmap_atomic(dst, KM_USER0);
1861                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1862
1863                 /*
1864                  * This really shouldn't fail, because the page is there
1865                  * in the page tables. But it might just be unreadable,
1866                  * in which case we just give up and fill the result with
1867                  * zeroes.
1868                  */
1869                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1870                         memset(kaddr, 0, PAGE_SIZE);
1871                 kunmap_atomic(kaddr, KM_USER0);
1872                 flush_dcache_page(dst);
1873         } else
1874                 copy_user_highpage(dst, src, va, vma);
1875 }
1876
1877 /*
1878  * This routine handles present pages, when users try to write
1879  * to a shared page. It is done by copying the page to a new address
1880  * and decrementing the shared-page counter for the old page.
1881  *
1882  * Note that this routine assumes that the protection checks have been
1883  * done by the caller (the low-level page fault routine in most cases).
1884  * Thus we can safely just mark it writable once we've done any necessary
1885  * COW.
1886  *
1887  * We also mark the page dirty at this point even though the page will
1888  * change only once the write actually happens. This avoids a few races,
1889  * and potentially makes it more efficient.
1890  *
1891  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1892  * but allow concurrent faults), with pte both mapped and locked.
1893  * We return with mmap_sem still held, but pte unmapped and unlocked.
1894  */
1895 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1896                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1897                 spinlock_t *ptl, pte_t orig_pte)
1898 {
1899         struct page *old_page, *new_page;
1900         pte_t entry;
1901         int reuse = 0, ret = 0;
1902         int page_mkwrite = 0;
1903         struct page *dirty_page = NULL;
1904
1905         old_page = vm_normal_page(vma, address, orig_pte);
1906         if (!old_page) {
1907                 /*
1908                  * VM_MIXEDMAP !pfn_valid() case
1909                  *
1910                  * We should not cow pages in a shared writeable mapping.
1911                  * Just mark the pages writable as we can't do any dirty
1912                  * accounting on raw pfn maps.
1913                  */
1914                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1915                                      (VM_WRITE|VM_SHARED))
1916                         goto reuse;
1917                 goto gotten;
1918         }
1919
1920         /*
1921          * Take out anonymous pages first, anonymous shared vmas are
1922          * not dirty accountable.
1923          */
1924         if (PageAnon(old_page)) {
1925                 if (!trylock_page(old_page)) {
1926                         page_cache_get(old_page);
1927                         pte_unmap_unlock(page_table, ptl);
1928                         lock_page(old_page);
1929                         page_table = pte_offset_map_lock(mm, pmd, address,
1930                                                          &ptl);
1931                         if (!pte_same(*page_table, orig_pte)) {
1932                                 unlock_page(old_page);
1933                                 page_cache_release(old_page);
1934                                 goto unlock;
1935                         }
1936                         page_cache_release(old_page);
1937                 }
1938                 reuse = reuse_swap_page(old_page);
1939                 unlock_page(old_page);
1940         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1941                                         (VM_WRITE|VM_SHARED))) {
1942                 /*
1943                  * Only catch write-faults on shared writable pages,
1944                  * read-only shared pages can get COWed by
1945                  * get_user_pages(.write=1, .force=1).
1946                  */
1947                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1948                         struct vm_fault vmf;
1949                         int tmp;
1950
1951                         vmf.virtual_address = (void __user *)(address &
1952                                                                 PAGE_MASK);
1953                         vmf.pgoff = old_page->index;
1954                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
1955                         vmf.page = old_page;
1956
1957                         /*
1958                          * Notify the address space that the page is about to
1959                          * become writable so that it can prohibit this or wait
1960                          * for the page to get into an appropriate state.
1961                          *
1962                          * We do this without the lock held, so that it can
1963                          * sleep if it needs to.
1964                          */
1965                         page_cache_get(old_page);
1966                         pte_unmap_unlock(page_table, ptl);
1967
1968                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
1969                         if (unlikely(tmp &
1970                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
1971                                 ret = tmp;
1972                                 goto unwritable_page;
1973                         }
1974
1975                         /*
1976                          * Since we dropped the lock we need to revalidate
1977                          * the PTE as someone else may have changed it.  If
1978                          * they did, we just return, as we can count on the
1979                          * MMU to tell us if they didn't also make it writable.
1980                          */
1981                         page_table = pte_offset_map_lock(mm, pmd, address,
1982                                                          &ptl);
1983                         page_cache_release(old_page);
1984                         if (!pte_same(*page_table, orig_pte))
1985                                 goto unlock;
1986
1987                         page_mkwrite = 1;
1988                 }
1989                 dirty_page = old_page;
1990                 get_page(dirty_page);
1991                 reuse = 1;
1992         }
1993
1994         if (reuse) {
1995 reuse:
1996                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1997                 entry = pte_mkyoung(orig_pte);
1998                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1999                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2000                         update_mmu_cache(vma, address, entry);
2001                 ret |= VM_FAULT_WRITE;
2002                 goto unlock;
2003         }
2004
2005         /*
2006          * Ok, we need to copy. Oh, well..
2007          */
2008         page_cache_get(old_page);
2009 gotten:
2010         pte_unmap_unlock(page_table, ptl);
2011
2012         if (unlikely(anon_vma_prepare(vma)))
2013                 goto oom;
2014         VM_BUG_ON(old_page == ZERO_PAGE(0));
2015         new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2016         if (!new_page)
2017                 goto oom;
2018         /*
2019          * Don't let another task, with possibly unlocked vma,
2020          * keep the mlocked page.
2021          */
2022         if ((vma->vm_flags & VM_LOCKED) && old_page) {
2023                 lock_page(old_page);    /* for LRU manipulation */
2024                 clear_page_mlock(old_page);
2025                 unlock_page(old_page);
2026         }
2027         cow_user_page(new_page, old_page, address, vma);
2028         __SetPageUptodate(new_page);
2029
2030         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2031                 goto oom_free_new;
2032
2033         /*
2034          * Re-check the pte - we dropped the lock
2035          */
2036         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2037         if (likely(pte_same(*page_table, orig_pte))) {
2038                 if (old_page) {
2039                         if (!PageAnon(old_page)) {
2040                                 dec_mm_counter(mm, file_rss);
2041                                 inc_mm_counter(mm, anon_rss);
2042                         }
2043                 } else
2044                         inc_mm_counter(mm, anon_rss);
2045                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2046                 entry = mk_pte(new_page, vma->vm_page_prot);
2047                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2048                 /*
2049                  * Clear the pte entry and flush it first, before updating the
2050                  * pte with the new entry. This will avoid a race condition
2051                  * seen in the presence of one thread doing SMC and another
2052                  * thread doing COW.
2053                  */
2054                 ptep_clear_flush_notify(vma, address, page_table);
2055                 page_add_new_anon_rmap(new_page, vma, address);
2056                 set_pte_at(mm, address, page_table, entry);
2057                 update_mmu_cache(vma, address, entry);
2058                 if (old_page) {
2059                         /*
2060                          * Only after switching the pte to the new page may
2061                          * we remove the mapcount here. Otherwise another
2062                          * process may come and find the rmap count decremented
2063                          * before the pte is switched to the new page, and
2064                          * "reuse" the old page writing into it while our pte
2065                          * here still points into it and can be read by other
2066                          * threads.
2067                          *
2068                          * The critical issue is to order this
2069                          * page_remove_rmap with the ptp_clear_flush above.
2070                          * Those stores are ordered by (if nothing else,)
2071                          * the barrier present in the atomic_add_negative
2072                          * in page_remove_rmap.
2073                          *
2074                          * Then the TLB flush in ptep_clear_flush ensures that
2075                          * no process can access the old page before the
2076                          * decremented mapcount is visible. And the old page
2077                          * cannot be reused until after the decremented
2078                          * mapcount is visible. So transitively, TLBs to
2079                          * old page will be flushed before it can be reused.
2080                          */
2081                         page_remove_rmap(old_page);
2082                 }
2083
2084                 /* Free the old page.. */
2085                 new_page = old_page;
2086                 ret |= VM_FAULT_WRITE;
2087         } else
2088                 mem_cgroup_uncharge_page(new_page);
2089
2090         if (new_page)
2091                 page_cache_release(new_page);
2092         if (old_page)
2093                 page_cache_release(old_page);
2094 unlock:
2095         pte_unmap_unlock(page_table, ptl);
2096         if (dirty_page) {
2097                 if (vma->vm_file)
2098                         file_update_time(vma->vm_file);
2099
2100                 /*
2101                  * Yes, Virginia, this is actually required to prevent a race
2102                  * with clear_page_dirty_for_io() from clearing the page dirty
2103                  * bit after it clear all dirty ptes, but before a racing
2104                  * do_wp_page installs a dirty pte.
2105                  *
2106                  * do_no_page is protected similarly.
2107                  */
2108                 wait_on_page_locked(dirty_page);
2109                 set_page_dirty_balance(dirty_page, page_mkwrite);
2110                 put_page(dirty_page);
2111         }
2112         return ret;
2113 oom_free_new:
2114         page_cache_release(new_page);
2115 oom:
2116         if (old_page)
2117                 page_cache_release(old_page);
2118         return VM_FAULT_OOM;
2119
2120 unwritable_page:
2121         page_cache_release(old_page);
2122         return ret;
2123 }
2124
2125 /*
2126  * Helper functions for unmap_mapping_range().
2127  *
2128  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2129  *
2130  * We have to restart searching the prio_tree whenever we drop the lock,
2131  * since the iterator is only valid while the lock is held, and anyway
2132  * a later vma might be split and reinserted earlier while lock dropped.
2133  *
2134  * The list of nonlinear vmas could be handled more efficiently, using
2135  * a placeholder, but handle it in the same way until a need is shown.
2136  * It is important to search the prio_tree before nonlinear list: a vma
2137  * may become nonlinear and be shifted from prio_tree to nonlinear list
2138  * while the lock is dropped; but never shifted from list to prio_tree.
2139  *
2140  * In order to make forward progress despite restarting the search,
2141  * vm_truncate_count is used to mark a vma as now dealt with, so we can
2142  * quickly skip it next time around.  Since the prio_tree search only
2143  * shows us those vmas affected by unmapping the range in question, we
2144  * can't efficiently keep all vmas in step with mapping->truncate_count:
2145  * so instead reset them all whenever it wraps back to 0 (then go to 1).
2146  * mapping->truncate_count and vma->vm_truncate_count are protected by
2147  * i_mmap_lock.
2148  *
2149  * In order to make forward progress despite repeatedly restarting some
2150  * large vma, note the restart_addr from unmap_vmas when it breaks out:
2151  * and restart from that address when we reach that vma again.  It might
2152  * have been split or merged, shrunk or extended, but never shifted: so
2153  * restart_addr remains valid so long as it remains in the vma's range.
2154  * unmap_mapping_range forces truncate_count to leap over page-aligned
2155  * values so we can save vma's restart_addr in its truncate_count field.
2156  */
2157 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2158
2159 static void reset_vma_truncate_counts(struct address_space *mapping)
2160 {
2161         struct vm_area_struct *vma;
2162         struct prio_tree_iter iter;
2163
2164         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2165                 vma->vm_truncate_count = 0;
2166         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2167                 vma->vm_truncate_count = 0;
2168 }
2169
2170 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2171                 unsigned long start_addr, unsigned long end_addr,
2172                 struct zap_details *details)
2173 {
2174         unsigned long restart_addr;
2175         int need_break;
2176
2177         /*
2178          * files that support invalidating or truncating portions of the
2179          * file from under mmaped areas must have their ->fault function
2180          * return a locked page (and set VM_FAULT_LOCKED in the return).
2181          * This provides synchronisation against concurrent unmapping here.
2182          */
2183
2184 again:
2185         restart_addr = vma->vm_truncate_count;
2186         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2187                 start_addr = restart_addr;
2188                 if (start_addr >= end_addr) {
2189                         /* Top of vma has been split off since last time */
2190                         vma->vm_truncate_count = details->truncate_count;
2191                         return 0;
2192                 }
2193         }
2194
2195         restart_addr = zap_page_range(vma, start_addr,
2196                                         end_addr - start_addr, details);
2197         need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2198
2199         if (restart_addr >= end_addr) {
2200                 /* We have now completed this vma: mark it so */
2201                 vma->vm_truncate_count = details->truncate_count;
2202                 if (!need_break)
2203                         return 0;
2204         } else {
2205                 /* Note restart_addr in vma's truncate_count field */
2206                 vma->vm_truncate_count = restart_addr;
2207                 if (!need_break)
2208                         goto again;
2209         }
2210
2211         spin_unlock(details->i_mmap_lock);
2212         cond_resched();
2213         spin_lock(details->i_mmap_lock);
2214         return -EINTR;
2215 }
2216
2217 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2218                                             struct zap_details *details)
2219 {
2220         struct vm_area_struct *vma;
2221         struct prio_tree_iter iter;
2222         pgoff_t vba, vea, zba, zea;
2223
2224 restart:
2225         vma_prio_tree_foreach(vma, &iter, root,
2226                         details->first_index, details->last_index) {
2227                 /* Skip quickly over those we have already dealt with */
2228                 if (vma->vm_truncate_count == details->truncate_count)
2229                         continue;
2230
2231                 vba = vma->vm_pgoff;
2232                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2233                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2234                 zba = details->first_index;
2235                 if (zba < vba)
2236                         zba = vba;
2237                 zea = details->last_index;
2238                 if (zea > vea)
2239                         zea = vea;
2240
2241                 if (unmap_mapping_range_vma(vma,
2242                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2243                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2244                                 details) < 0)
2245                         goto restart;
2246         }
2247 }
2248
2249 static inline void unmap_mapping_range_list(struct list_head *head,
2250                                             struct zap_details *details)
2251 {
2252         struct vm_area_struct *vma;
2253
2254         /*
2255          * In nonlinear VMAs there is no correspondence between virtual address
2256          * offset and file offset.  So we must perform an exhaustive search
2257          * across *all* the pages in each nonlinear VMA, not just the pages
2258          * whose virtual address lies outside the file truncation point.
2259          */
2260 restart:
2261         list_for_each_entry(vma, head, shared.vm_set.list) {
2262                 /* Skip quickly over those we have already dealt with */
2263                 if (vma->vm_truncate_count == details->truncate_count)
2264                         continue;
2265                 details->nonlinear_vma = vma;
2266                 if (unmap_mapping_range_vma(vma, vma->vm_start,
2267                                         vma->vm_end, details) < 0)
2268                         goto restart;
2269         }
2270 }
2271
2272 /**
2273  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2274  * @mapping: the address space containing mmaps to be unmapped.
2275  * @holebegin: byte in first page to unmap, relative to the start of
2276  * the underlying file.  This will be rounded down to a PAGE_SIZE
2277  * boundary.  Note that this is different from vmtruncate(), which
2278  * must keep the partial page.  In contrast, we must get rid of
2279  * partial pages.
2280  * @holelen: size of prospective hole in bytes.  This will be rounded
2281  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2282  * end of the file.
2283  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2284  * but 0 when invalidating pagecache, don't throw away private data.
2285  */
2286 void unmap_mapping_range(struct address_space *mapping,
2287                 loff_t const holebegin, loff_t const holelen, int even_cows)
2288 {
2289         struct zap_details details;
2290         pgoff_t hba = holebegin >> PAGE_SHIFT;
2291         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2292
2293         /* Check for overflow. */
2294         if (sizeof(holelen) > sizeof(hlen)) {
2295                 long long holeend =
2296                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2297                 if (holeend & ~(long long)ULONG_MAX)
2298                         hlen = ULONG_MAX - hba + 1;
2299         }
2300
2301         details.check_mapping = even_cows? NULL: mapping;
2302         details.nonlinear_vma = NULL;
2303         details.first_index = hba;
2304         details.last_index = hba + hlen - 1;
2305         if (details.last_index < details.first_index)
2306                 details.last_index = ULONG_MAX;
2307         details.i_mmap_lock = &mapping->i_mmap_lock;
2308
2309         spin_lock(&mapping->i_mmap_lock);
2310
2311         /* Protect against endless unmapping loops */
2312         mapping->truncate_count++;
2313         if (unlikely(is_restart_addr(mapping->truncate_count))) {
2314                 if (mapping->truncate_count == 0)
2315                         reset_vma_truncate_counts(mapping);
2316                 mapping->truncate_count++;
2317         }
2318         details.truncate_count = mapping->truncate_count;
2319
2320         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2321                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2322         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2323                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2324         spin_unlock(&mapping->i_mmap_lock);
2325 }
2326 EXPORT_SYMBOL(unmap_mapping_range);
2327
2328 /**
2329  * vmtruncate - unmap mappings "freed" by truncate() syscall
2330  * @inode: inode of the file used
2331  * @offset: file offset to start truncating
2332  *
2333  * NOTE! We have to be ready to update the memory sharing
2334  * between the file and the memory map for a potential last
2335  * incomplete page.  Ugly, but necessary.
2336  */
2337 int vmtruncate(struct inode * inode, loff_t offset)
2338 {
2339         if (inode->i_size < offset) {
2340                 unsigned long limit;
2341
2342                 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
2343                 if (limit != RLIM_INFINITY && offset > limit)
2344                         goto out_sig;
2345                 if (offset > inode->i_sb->s_maxbytes)
2346                         goto out_big;
2347                 i_size_write(inode, offset);
2348         } else {
2349                 struct address_space *mapping = inode->i_mapping;
2350
2351                 /*
2352                  * truncation of in-use swapfiles is disallowed - it would
2353                  * cause subsequent swapout to scribble on the now-freed
2354                  * blocks.
2355                  */
2356                 if (IS_SWAPFILE(inode))
2357                         return -ETXTBSY;
2358                 i_size_write(inode, offset);
2359
2360                 /*
2361                  * unmap_mapping_range is called twice, first simply for
2362                  * efficiency so that truncate_inode_pages does fewer
2363                  * single-page unmaps.  However after this first call, and
2364                  * before truncate_inode_pages finishes, it is possible for
2365                  * private pages to be COWed, which remain after
2366                  * truncate_inode_pages finishes, hence the second
2367                  * unmap_mapping_range call must be made for correctness.
2368                  */
2369                 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2370                 truncate_inode_pages(mapping, offset);
2371                 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2372         }
2373
2374         if (inode->i_op->truncate)
2375                 inode->i_op->truncate(inode);
2376         return 0;
2377
2378 out_sig:
2379         send_sig(SIGXFSZ, current, 0);
2380 out_big:
2381         return -EFBIG;
2382 }
2383 EXPORT_SYMBOL(vmtruncate);
2384
2385 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2386 {
2387         struct address_space *mapping = inode->i_mapping;
2388
2389         /*
2390          * If the underlying filesystem is not going to provide
2391          * a way to truncate a range of blocks (punch a hole) -
2392          * we should return failure right now.
2393          */
2394         if (!inode->i_op->truncate_range)
2395                 return -ENOSYS;
2396
2397         mutex_lock(&inode->i_mutex);
2398         down_write(&inode->i_alloc_sem);
2399         unmap_mapping_range(mapping, offset, (end - offset), 1);
2400         truncate_inode_pages_range(mapping, offset, end);
2401         unmap_mapping_range(mapping, offset, (end - offset), 1);
2402         inode->i_op->truncate_range(inode, offset, end);
2403         up_write(&inode->i_alloc_sem);
2404         mutex_unlock(&inode->i_mutex);
2405
2406         return 0;
2407 }
2408
2409 /*
2410  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2411  * but allow concurrent faults), and pte mapped but not yet locked.
2412  * We return with mmap_sem still held, but pte unmapped and unlocked.
2413  */
2414 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2415                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2416                 int write_access, pte_t orig_pte)
2417 {
2418         spinlock_t *ptl;
2419         struct page *page;
2420         swp_entry_t entry;
2421         pte_t pte;
2422         struct mem_cgroup *ptr = NULL;
2423         int ret = 0;
2424
2425         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2426                 goto out;
2427
2428         entry = pte_to_swp_entry(orig_pte);
2429         if (is_migration_entry(entry)) {
2430                 migration_entry_wait(mm, pmd, address);
2431                 goto out;
2432         }
2433         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2434         page = lookup_swap_cache(entry);
2435         if (!page) {
2436                 grab_swap_token(); /* Contend for token _before_ read-in */
2437                 page = swapin_readahead(entry,
2438                                         GFP_HIGHUSER_MOVABLE, vma, address);
2439                 if (!page) {
2440                         /*
2441                          * Back out if somebody else faulted in this pte
2442                          * while we released the pte lock.
2443                          */
2444                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2445                         if (likely(pte_same(*page_table, orig_pte)))
2446                                 ret = VM_FAULT_OOM;
2447                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2448                         goto unlock;
2449                 }
2450
2451                 /* Had to read the page from swap area: Major fault */
2452                 ret = VM_FAULT_MAJOR;
2453                 count_vm_event(PGMAJFAULT);
2454         }
2455
2456         lock_page(page);
2457         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2458
2459         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2460                 ret = VM_FAULT_OOM;
2461                 unlock_page(page);
2462                 goto out;
2463         }
2464
2465         /*
2466          * Back out if somebody else already faulted in this pte.
2467          */
2468         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2469         if (unlikely(!pte_same(*page_table, orig_pte)))
2470                 goto out_nomap;
2471
2472         if (unlikely(!PageUptodate(page))) {
2473                 ret = VM_FAULT_SIGBUS;
2474                 goto out_nomap;
2475         }
2476
2477         /*
2478          * The page isn't present yet, go ahead with the fault.
2479          *
2480          * Be careful about the sequence of operations here.
2481          * To get its accounting right, reuse_swap_page() must be called
2482          * while the page is counted on swap but not yet in mapcount i.e.
2483          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2484          * must be called after the swap_free(), or it will never succeed.
2485          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2486          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2487          * in page->private. In this case, a record in swap_cgroup  is silently
2488          * discarded at swap_free().
2489          */
2490
2491         inc_mm_counter(mm, anon_rss);
2492         pte = mk_pte(page, vma->vm_page_prot);
2493         if (write_access && reuse_swap_page(page)) {
2494                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2495                 write_access = 0;
2496         }
2497         flush_icache_page(vma, page);
2498         set_pte_at(mm, address, page_table, pte);
2499         page_add_anon_rmap(page, vma, address);
2500         /* It's better to call commit-charge after rmap is established */
2501         mem_cgroup_commit_charge_swapin(page, ptr);
2502
2503         swap_free(entry);
2504         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2505                 try_to_free_swap(page);
2506         unlock_page(page);
2507
2508         if (write_access) {
2509                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2510                 if (ret & VM_FAULT_ERROR)
2511                         ret &= VM_FAULT_ERROR;
2512                 goto out;
2513         }
2514
2515         /* No need to invalidate - it was non-present before */
2516         update_mmu_cache(vma, address, pte);
2517 unlock:
2518         pte_unmap_unlock(page_table, ptl);
2519 out:
2520         return ret;
2521 out_nomap:
2522         mem_cgroup_cancel_charge_swapin(ptr);
2523         pte_unmap_unlock(page_table, ptl);
2524         unlock_page(page);
2525         page_cache_release(page);
2526         return ret;
2527 }
2528
2529 /*
2530  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2531  * but allow concurrent faults), and pte mapped but not yet locked.
2532  * We return with mmap_sem still held, but pte unmapped and unlocked.
2533  */
2534 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2535                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2536                 int write_access)
2537 {
2538         struct page *page;
2539         spinlock_t *ptl;
2540         pte_t entry;
2541
2542         /* Allocate our own private page. */
2543         pte_unmap(page_table);
2544
2545         if (unlikely(anon_vma_prepare(vma)))
2546                 goto oom;
2547         page = alloc_zeroed_user_highpage_movable(vma, address);
2548         if (!page)
2549                 goto oom;
2550         __SetPageUptodate(page);
2551
2552         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2553                 goto oom_free_page;
2554
2555         entry = mk_pte(page, vma->vm_page_prot);
2556         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2557
2558         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2559         if (!pte_none(*page_table))
2560                 goto release;
2561         inc_mm_counter(mm, anon_rss);
2562         page_add_new_anon_rmap(page, vma, address);
2563         set_pte_at(mm, address, page_table, entry);
2564
2565         /* No need to invalidate - it was non-present before */
2566         update_mmu_cache(vma, address, entry);
2567 unlock:
2568         pte_unmap_unlock(page_table, ptl);
2569         return 0;
2570 release:
2571         mem_cgroup_uncharge_page(page);
2572         page_cache_release(page);
2573         goto unlock;
2574 oom_free_page:
2575         page_cache_release(page);
2576 oom:
2577         return VM_FAULT_OOM;
2578 }
2579
2580 /*
2581  * __do_fault() tries to create a new page mapping. It aggressively
2582  * tries to share with existing pages, but makes a separate copy if
2583  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2584  * the next page fault.
2585  *
2586  * As this is called only for pages that do not currently exist, we
2587  * do not need to flush old virtual caches or the TLB.
2588  *
2589  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2590  * but allow concurrent faults), and pte neither mapped nor locked.
2591  * We return with mmap_sem still held, but pte unmapped and unlocked.
2592  */
2593 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2594                 unsigned long address, pmd_t *pmd,
2595                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2596 {
2597         pte_t *page_table;
2598         spinlock_t *ptl;
2599         struct page *page;
2600         pte_t entry;
2601         int anon = 0;
2602         int charged = 0;
2603         struct page *dirty_page = NULL;
2604         struct vm_fault vmf;
2605         int ret;
2606         int page_mkwrite = 0;
2607
2608         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2609         vmf.pgoff = pgoff;
2610         vmf.flags = flags;
2611         vmf.page = NULL;
2612
2613         ret = vma->vm_ops->fault(vma, &vmf);
2614         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2615                 return ret;
2616
2617         /*
2618          * For consistency in subsequent calls, make the faulted page always
2619          * locked.
2620          */
2621         if (unlikely(!(ret & VM_FAULT_LOCKED)))
2622                 lock_page(vmf.page);
2623         else
2624                 VM_BUG_ON(!PageLocked(vmf.page));
2625
2626         /*
2627          * Should we do an early C-O-W break?
2628          */
2629         page = vmf.page;
2630         if (flags & FAULT_FLAG_WRITE) {
2631                 if (!(vma->vm_flags & VM_SHARED)) {
2632                         anon = 1;
2633                         if (unlikely(anon_vma_prepare(vma))) {
2634                                 ret = VM_FAULT_OOM;
2635                                 goto out;
2636                         }
2637                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2638                                                 vma, address);
2639                         if (!page) {
2640                                 ret = VM_FAULT_OOM;
2641                                 goto out;
2642                         }
2643                         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2644                                 ret = VM_FAULT_OOM;
2645                                 page_cache_release(page);
2646                                 goto out;
2647                         }
2648                         charged = 1;
2649                         /*
2650                          * Don't let another task, with possibly unlocked vma,
2651                          * keep the mlocked page.
2652                          */
2653                         if (vma->vm_flags & VM_LOCKED)
2654                                 clear_page_mlock(vmf.page);
2655                         copy_user_highpage(page, vmf.page, address, vma);
2656                         __SetPageUptodate(page);
2657                 } else {
2658                         /*
2659                          * If the page will be shareable, see if the backing
2660                          * address space wants to know that the page is about
2661                          * to become writable
2662                          */
2663                         if (vma->vm_ops->page_mkwrite) {
2664                                 int tmp;
2665
2666                                 unlock_page(page);
2667                                 vmf.flags |= FAULT_FLAG_MKWRITE;
2668                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2669                                 if (unlikely(tmp &
2670                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2671                                         ret = tmp;
2672                                         anon = 1; /* no anon but release vmf.page */
2673                                         goto out_unlocked;
2674                                 }
2675                                 lock_page(page);
2676                                 /*
2677                                  * XXX: this is not quite right (racy vs
2678                                  * invalidate) to unlock and relock the page
2679                                  * like this, however a better fix requires
2680                                  * reworking page_mkwrite locking API, which
2681                                  * is better done later.
2682                                  */
2683                                 if (!page->mapping) {
2684                                         ret = 0;
2685                                         anon = 1; /* no anon but release vmf.page */
2686                                         goto out;
2687                                 }
2688                                 page_mkwrite = 1;
2689                         }
2690                 }
2691
2692         }
2693
2694         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2695
2696         /*
2697          * This silly early PAGE_DIRTY setting removes a race
2698          * due to the bad i386 page protection. But it's valid
2699          * for other architectures too.
2700          *
2701          * Note that if write_access is true, we either now have
2702          * an exclusive copy of the page, or this is a shared mapping,
2703          * so we can make it writable and dirty to avoid having to
2704          * handle that later.
2705          */
2706         /* Only go through if we didn't race with anybody else... */
2707         if (likely(pte_same(*page_table, orig_pte))) {
2708                 flush_icache_page(vma, page);
2709                 entry = mk_pte(page, vma->vm_page_prot);
2710                 if (flags & FAULT_FLAG_WRITE)
2711                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2712                 if (anon) {
2713                         inc_mm_counter(mm, anon_rss);
2714                         page_add_new_anon_rmap(page, vma, address);
2715                 } else {
2716                         inc_mm_counter(mm, file_rss);
2717                         page_add_file_rmap(page);
2718                         if (flags & FAULT_FLAG_WRITE) {
2719                                 dirty_page = page;
2720                                 get_page(dirty_page);
2721                         }
2722                 }
2723                 set_pte_at(mm, address, page_table, entry);
2724
2725                 /* no need to invalidate: a not-present page won't be cached */
2726                 update_mmu_cache(vma, address, entry);
2727         } else {
2728                 if (charged)
2729                         mem_cgroup_uncharge_page(page);
2730                 if (anon)
2731                         page_cache_release(page);
2732                 else
2733                         anon = 1; /* no anon but release faulted_page */
2734         }
2735
2736         pte_unmap_unlock(page_table, ptl);
2737
2738 out:
2739         unlock_page(vmf.page);
2740 out_unlocked:
2741         if (anon)
2742                 page_cache_release(vmf.page);
2743         else if (dirty_page) {
2744                 if (vma->vm_file)
2745                         file_update_time(vma->vm_file);
2746
2747                 set_page_dirty_balance(dirty_page, page_mkwrite);
2748                 put_page(dirty_page);
2749         }
2750
2751         return ret;
2752 }
2753
2754 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2755                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2756                 int write_access, pte_t orig_pte)
2757 {
2758         pgoff_t pgoff = (((address & PAGE_MASK)
2759                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2760         unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
2761
2762         pte_unmap(page_table);
2763         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2764 }
2765
2766 /*
2767  * Fault of a previously existing named mapping. Repopulate the pte
2768  * from the encoded file_pte if possible. This enables swappable
2769  * nonlinear vmas.
2770  *
2771  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2772  * but allow concurrent faults), and pte mapped but not yet locked.
2773  * We return with mmap_sem still held, but pte unmapped and unlocked.
2774  */
2775 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2776                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2777                 int write_access, pte_t orig_pte)
2778 {
2779         unsigned int flags = FAULT_FLAG_NONLINEAR |
2780                                 (write_access ? FAULT_FLAG_WRITE : 0);
2781         pgoff_t pgoff;
2782
2783         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2784                 return 0;
2785
2786         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2787                 /*
2788                  * Page table corrupted: show pte and kill process.
2789                  */
2790                 print_bad_pte(vma, address, orig_pte, NULL);
2791                 return VM_FAULT_OOM;
2792         }
2793
2794         pgoff = pte_to_pgoff(orig_pte);
2795         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2796 }
2797
2798 /*
2799  * These routines also need to handle stuff like marking pages dirty
2800  * and/or accessed for architectures that don't do it in hardware (most
2801  * RISC architectures).  The early dirtying is also good on the i386.
2802  *
2803  * There is also a hook called "update_mmu_cache()" that architectures
2804  * with external mmu caches can use to update those (ie the Sparc or
2805  * PowerPC hashed page tables that act as extended TLBs).
2806  *
2807  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2808  * but allow concurrent faults), and pte mapped but not yet locked.
2809  * We return with mmap_sem still held, but pte unmapped and unlocked.
2810  */
2811 static inline int handle_pte_fault(struct mm_struct *mm,
2812                 struct vm_area_struct *vma, unsigned long address,
2813                 pte_t *pte, pmd_t *pmd, int write_access)
2814 {
2815         pte_t entry;
2816         spinlock_t *ptl;
2817
2818         entry = *pte;
2819         if (!pte_present(entry)) {
2820                 if (pte_none(entry)) {
2821                         if (vma->vm_ops) {
2822                                 if (likely(vma->vm_ops->fault))
2823                                         return do_linear_fault(mm, vma, address,
2824                                                 pte, pmd, write_access, entry);
2825                         }
2826                         return do_anonymous_page(mm, vma, address,
2827                                                  pte, pmd, write_access);
2828                 }
2829                 if (pte_file(entry))
2830                         return do_nonlinear_fault(mm, vma, address,
2831                                         pte, pmd, write_access, entry);
2832                 return do_swap_page(mm, vma, address,
2833                                         pte, pmd, write_access, entry);
2834         }
2835
2836         ptl = pte_lockptr(mm, pmd);
2837         spin_lock(ptl);
2838         if (unlikely(!pte_same(*pte, entry)))
2839                 goto unlock;
2840         if (write_access) {
2841                 if (!pte_write(entry))
2842                         return do_wp_page(mm, vma, address,
2843                                         pte, pmd, ptl, entry);
2844                 entry = pte_mkdirty(entry);
2845         }
2846         entry = pte_mkyoung(entry);
2847         if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2848                 update_mmu_cache(vma, address, entry);
2849         } else {
2850                 /*
2851                  * This is needed only for protection faults but the arch code
2852                  * is not yet telling us if this is a protection fault or not.
2853                  * This still avoids useless tlb flushes for .text page faults
2854                  * with threads.
2855                  */
2856                 if (write_access)
2857                         flush_tlb_page(vma, address);
2858         }
2859 unlock:
2860         pte_unmap_unlock(pte, ptl);
2861         return 0;
2862 }
2863
2864 /*
2865  * By the time we get here, we already hold the mm semaphore
2866  */
2867 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2868                 unsigned long address, int write_access)
2869 {
2870         pgd_t *pgd;
2871         pud_t *pud;
2872         pmd_t *pmd;
2873         pte_t *pte;
2874
2875         __set_current_state(TASK_RUNNING);
2876
2877         count_vm_event(PGFAULT);
2878
2879         if (unlikely(is_vm_hugetlb_page(vma)))
2880                 return hugetlb_fault(mm, vma, address, write_access);
2881
2882         pgd = pgd_offset(mm, address);
2883         pud = pud_alloc(mm, pgd, address);
2884         if (!pud)
2885                 return VM_FAULT_OOM;
2886         pmd = pmd_alloc(mm, pud, address);
2887         if (!pmd)
2888                 return VM_FAULT_OOM;
2889         pte = pte_alloc_map(mm, pmd, address);
2890         if (!pte)
2891                 return VM_FAULT_OOM;
2892
2893         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2894 }
2895
2896 #ifndef __PAGETABLE_PUD_FOLDED
2897 /*
2898  * Allocate page upper directory.
2899  * We've already handled the fast-path in-line.
2900  */
2901 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2902 {
2903         pud_t *new = pud_alloc_one(mm, address);
2904         if (!new)
2905                 return -ENOMEM;
2906
2907         smp_wmb(); /* See comment in __pte_alloc */
2908
2909         spin_lock(&mm->page_table_lock);
2910         if (pgd_present(*pgd))          /* Another has populated it */
2911                 pud_free(mm, new);
2912         else
2913                 pgd_populate(mm, pgd, new);
2914         spin_unlock(&mm->page_table_lock);
2915         return 0;
2916 }
2917 #endif /* __PAGETABLE_PUD_FOLDED */
2918
2919 #ifndef __PAGETABLE_PMD_FOLDED
2920 /*
2921  * Allocate page middle directory.
2922  * We've already handled the fast-path in-line.
2923  */
2924 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2925 {
2926         pmd_t *new = pmd_alloc_one(mm, address);
2927         if (!new)
2928                 return -ENOMEM;
2929
2930         smp_wmb(); /* See comment in __pte_alloc */
2931
2932         spin_lock(&mm->page_table_lock);
2933 #ifndef __ARCH_HAS_4LEVEL_HACK
2934         if (pud_present(*pud))          /* Another has populated it */
2935                 pmd_free(mm, new);
2936         else
2937                 pud_populate(mm, pud, new);
2938 #else
2939         if (pgd_present(*pud))          /* Another has populated it */
2940                 pmd_free(mm, new);
2941         else
2942                 pgd_populate(mm, pud, new);
2943 #endif /* __ARCH_HAS_4LEVEL_HACK */
2944         spin_unlock(&mm->page_table_lock);
2945         return 0;
2946 }
2947 #endif /* __PAGETABLE_PMD_FOLDED */
2948
2949 int make_pages_present(unsigned long addr, unsigned long end)
2950 {
2951         int ret, len, write;
2952         struct vm_area_struct * vma;
2953
2954         vma = find_vma(current->mm, addr);
2955         if (!vma)
2956                 return -ENOMEM;
2957         write = (vma->vm_flags & VM_WRITE) != 0;
2958         BUG_ON(addr >= end);
2959         BUG_ON(end > vma->vm_end);
2960         len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
2961         ret = get_user_pages(current, current->mm, addr,
2962                         len, write, 0, NULL, NULL);
2963         if (ret < 0)
2964                 return ret;
2965         return ret == len ? 0 : -EFAULT;
2966 }
2967
2968 #if !defined(__HAVE_ARCH_GATE_AREA)
2969
2970 #if defined(AT_SYSINFO_EHDR)
2971 static struct vm_area_struct gate_vma;
2972
2973 static int __init gate_vma_init(void)
2974 {
2975         gate_vma.vm_mm = NULL;
2976         gate_vma.vm_start = FIXADDR_USER_START;
2977         gate_vma.vm_end = FIXADDR_USER_END;
2978         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
2979         gate_vma.vm_page_prot = __P101;
2980         /*
2981          * Make sure the vDSO gets into every core dump.
2982          * Dumping its contents makes post-mortem fully interpretable later
2983          * without matching up the same kernel and hardware config to see
2984          * what PC values meant.
2985          */
2986         gate_vma.vm_flags |= VM_ALWAYSDUMP;
2987         return 0;
2988 }
2989 __initcall(gate_vma_init);
2990 #endif
2991
2992 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2993 {
2994 #ifdef AT_SYSINFO_EHDR
2995         return &gate_vma;
2996 #else
2997         return NULL;
2998 #endif
2999 }
3000
3001 int in_gate_area_no_task(unsigned long addr)
3002 {
3003 #ifdef AT_SYSINFO_EHDR
3004         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3005                 return 1;
3006 #endif
3007         return 0;
3008 }
3009
3010 #endif  /* __HAVE_ARCH_GATE_AREA */
3011
3012 #ifdef CONFIG_HAVE_IOREMAP_PROT
3013 int follow_phys(struct vm_area_struct *vma,
3014                 unsigned long address, unsigned int flags,
3015                 unsigned long *prot, resource_size_t *phys)
3016 {
3017         pgd_t *pgd;
3018         pud_t *pud;
3019         pmd_t *pmd;
3020         pte_t *ptep, pte;
3021         spinlock_t *ptl;
3022         resource_size_t phys_addr = 0;
3023         struct mm_struct *mm = vma->vm_mm;
3024         int ret = -EINVAL;
3025
3026         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3027                 goto out;
3028
3029         pgd = pgd_offset(mm, address);
3030         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3031                 goto out;
3032
3033         pud = pud_offset(pgd, address);
3034         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3035                 goto out;
3036
3037         pmd = pmd_offset(pud, address);
3038         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3039                 goto out;
3040
3041         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3042         if (pmd_huge(*pmd))
3043                 goto out;
3044
3045         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
3046         if (!ptep)
3047                 goto out;
3048
3049         pte = *ptep;
3050         if (!pte_present(pte))
3051                 goto unlock;
3052         if ((flags & FOLL_WRITE) && !pte_write(pte))
3053                 goto unlock;
3054         phys_addr = pte_pfn(pte);
3055         phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */
3056
3057         *prot = pgprot_val(pte_pgprot(pte));
3058         *phys = phys_addr;
3059         ret = 0;
3060
3061 unlock:
3062         pte_unmap_unlock(ptep, ptl);
3063 out:
3064         return ret;
3065 }
3066
3067 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3068                         void *buf, int len, int write)
3069 {
3070         resource_size_t phys_addr;
3071         unsigned long prot = 0;
3072         void __iomem *maddr;
3073         int offset = addr & (PAGE_SIZE-1);
3074
3075         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3076                 return -EINVAL;
3077
3078         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3079         if (write)
3080                 memcpy_toio(maddr + offset, buf, len);
3081         else
3082                 memcpy_fromio(buf, maddr + offset, len);
3083         iounmap(maddr);
3084
3085         return len;
3086 }
3087 #endif
3088
3089 /*
3090  * Access another process' address space.
3091  * Source/target buffer must be kernel space,
3092  * Do not walk the page table directly, use get_user_pages
3093  */
3094 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
3095 {
3096         struct mm_struct *mm;
3097         struct vm_area_struct *vma;
3098         void *old_buf = buf;
3099
3100         mm = get_task_mm(tsk);
3101         if (!mm)
3102                 return 0;
3103
3104         down_read(&mm->mmap_sem);
3105         /* ignore errors, just check how much was successfully transferred */
3106         while (len) {
3107                 int bytes, ret, offset;
3108                 void *maddr;
3109                 struct page *page = NULL;
3110
3111                 ret = get_user_pages(tsk, mm, addr, 1,
3112                                 write, 1, &page, &vma);
3113                 if (ret <= 0) {
3114                         /*
3115                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3116                          * we can access using slightly different code.
3117                          */
3118 #ifdef CONFIG_HAVE_IOREMAP_PROT
3119                         vma = find_vma(mm, addr);
3120                         if (!vma)
3121                                 break;
3122                         if (vma->vm_ops && vma->vm_ops->access)
3123                                 ret = vma->vm_ops->access(vma, addr, buf,
3124                                                           len, write);
3125                         if (ret <= 0)
3126 #endif
3127                                 break;
3128                         bytes = ret;
3129                 } else {
3130                         bytes = len;
3131                         offset = addr & (PAGE_SIZE-1);
3132                         if (bytes > PAGE_SIZE-offset)
3133                                 bytes = PAGE_SIZE-offset;
3134
3135                         maddr = kmap(page);
3136                         if (write) {
3137                                 copy_to_user_page(vma, page, addr,
3138                                                   maddr + offset, buf, bytes);
3139                                 set_page_dirty_lock(page);
3140                         } else {
3141                                 copy_from_user_page(vma, page, addr,
3142                                                     buf, maddr + offset, bytes);
3143                         }
3144                         kunmap(page);
3145                         page_cache_release(page);
3146                 }
3147                 len -= bytes;
3148                 buf += bytes;
3149                 addr += bytes;
3150         }
3151         up_read(&mm->mmap_sem);
3152         mmput(mm);
3153
3154         return buf - old_buf;
3155 }
3156
3157 /*
3158  * Print the name of a VMA.
3159  */
3160 void print_vma_addr(char *prefix, unsigned long ip)
3161 {
3162         struct mm_struct *mm = current->mm;
3163         struct vm_area_struct *vma;
3164
3165         /*
3166          * Do not print if we are in atomic
3167          * contexts (in exception stacks, etc.):
3168          */
3169         if (preempt_count())
3170                 return;
3171
3172         down_read(&mm->mmap_sem);
3173         vma = find_vma(mm, ip);
3174         if (vma && vma->vm_file) {
3175                 struct file *f = vma->vm_file;
3176                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3177                 if (buf) {
3178                         char *p, *s;
3179
3180                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3181                         if (IS_ERR(p))
3182                                 p = "?";
3183                         s = strrchr(p, '/');
3184                         if (s)
3185                                 p = s+1;
3186                         printk("%s%s[%lx+%lx]", prefix, p,
3187                                         vma->vm_start,
3188                                         vma->vm_end - vma->vm_start);
3189                         free_page((unsigned long)buf);
3190                 }
3191         }
3192         up_read(&current->mm->mmap_sem);
3193 }
3194
3195 #ifdef CONFIG_PROVE_LOCKING
3196 void might_fault(void)
3197 {
3198         /*
3199          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3200          * holding the mmap_sem, this is safe because kernel memory doesn't
3201          * get paged out, therefore we'll never actually fault, and the
3202          * below annotations will generate false positives.
3203          */
3204         if (segment_eq(get_fs(), KERNEL_DS))
3205                 return;
3206
3207         might_sleep();
3208         /*
3209          * it would be nicer only to annotate paths which are not under
3210          * pagefault_disable, however that requires a larger audit and
3211          * providing helpers like get_user_atomic.
3212          */
3213         if (!in_atomic() && current->mm)
3214                 might_lock_read(&current->mm->mmap_sem);
3215 }
3216 EXPORT_SYMBOL(might_fault);
3217 #endif