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
  53 #include <asm/pgalloc.h>
  54 #include <asm/uaccess.h>
  55 #include <asm/tlb.h>
  56 #include <asm/tlbflush.h>
  57 #include <asm/pgtable.h>
  58
  59 #include <linux/swapops.h>
  60 #include <linux/elf.h>
  61
  62 #ifndef CONFIG_NEED_MULTIPLE_NODES
  63 /* use the per-pgdat data instead for discontigmem - mbligh */
  64 unsigned long max_mapnr;
  65 struct page *mem_map;
  66
  67 EXPORT_SYMBOL(max_mapnr);
  68 EXPORT_SYMBOL(mem_map);
  69 #endif
  70
  71 unsigned long num_physpages;
  72 /*
  73  * A number of key systems in x86 including ioremap() rely on the assumption
  74  * that high_memory defines the upper bound on direct map memory, then end
  75  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  76  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  77  * and ZONE_HIGHMEM.
  78  */
  79 void * high_memory;
  80 unsigned long vmalloc_earlyreserve;
  81
  82 EXPORT_SYMBOL(num_physpages);
  83 EXPORT_SYMBOL(high_memory);
  84 EXPORT_SYMBOL(vmalloc_earlyreserve);
  85
  86 int randomize_va_space __read_mostly = 1;
  87
  88 static int __init disable_randmaps(char *s)
  89 {
  90         randomize_va_space = 0;
  91         return 1;
  92 }
  93 __setup("norandmaps", disable_randmaps);
  94
  95
  96 /*
  97  * If a p?d_bad entry is found while walking page tables, report
  98  * the error, before resetting entry to p?d_none.  Usually (but
  99  * very seldom) called out from the p?d_none_or_clear_bad macros.
 100  */
 101
 102 void pgd_clear_bad(pgd_t *pgd)
 103 {
 104         pgd_ERROR(*pgd);
 105         pgd_clear(pgd);
 106 }
 107
 108 void pud_clear_bad(pud_t *pud)
 109 {
 110         pud_ERROR(*pud);
 111         pud_clear(pud);
 112 }
 113
 114 void pmd_clear_bad(pmd_t *pmd)
 115 {
 116         pmd_ERROR(*pmd);
 117         pmd_clear(pmd);
 118 }
 119
 120 /*
 121  * Note: this doesn't free the actual pages themselves. That
 122  * has been handled earlier when unmapping all the memory regions.
 123  */
 124 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
 125 {
 126         struct page *page = pmd_page(*pmd);
 127         pmd_clear(pmd);
 128         pte_lock_deinit(page);
 129         pte_free_tlb(tlb, page);
 130         dec_zone_page_state(page, NR_PAGETABLE);
 131         tlb->mm->nr_ptes--;
 132 }
 133
 134 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 135                                 unsigned long addr, unsigned long end,
 136                                 unsigned long floor, unsigned long ceiling)
 137 {
 138         pmd_t *pmd;
 139         unsigned long next;
 140         unsigned long start;
 141
 142         start = addr;
 143         pmd = pmd_offset(pud, addr);
 144         do {
 145                 next = pmd_addr_end(addr, end);
 146                 if (pmd_none_or_clear_bad(pmd))
 147                         continue;
 148                 free_pte_range(tlb, pmd);
 149         } while (pmd++, addr = next, addr != end);
 150
 151         start &= PUD_MASK;
 152         if (start < floor)
 153                 return;
 154         if (ceiling) {
 155                 ceiling &= PUD_MASK;
 156                 if (!ceiling)
 157                         return;
 158         }
 159         if (end - 1 > ceiling - 1)
 160                 return;
 161
 162         pmd = pmd_offset(pud, start);
 163         pud_clear(pud);
 164         pmd_free_tlb(tlb, pmd);
 165 }
 166
 167 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 168                                 unsigned long addr, unsigned long end,
 169                                 unsigned long floor, unsigned long ceiling)
 170 {
 171         pud_t *pud;
 172         unsigned long next;
 173         unsigned long start;
 174
 175         start = addr;
 176         pud = pud_offset(pgd, addr);
 177         do {
 178                 next = pud_addr_end(addr, end);
 179                 if (pud_none_or_clear_bad(pud))
 180                         continue;
 181                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 182         } while (pud++, addr = next, addr != end);
 183
 184         start &= PGDIR_MASK;
 185         if (start < floor)
 186                 return;
 187         if (ceiling) {
 188                 ceiling &= PGDIR_MASK;
 189                 if (!ceiling)
 190                         return;
 191         }
 192         if (end - 1 > ceiling - 1)
 193                 return;
 194
 195         pud = pud_offset(pgd, start);
 196         pgd_clear(pgd);
 197         pud_free_tlb(tlb, pud);
 198 }
 199
 200 /*
 201  * This function frees user-level page tables of a process.
 202  *
 203  * Must be called with pagetable lock held.
 204  */
 205 void free_pgd_range(struct mmu_gather **tlb,
 206                         unsigned long addr, unsigned long end,
 207                         unsigned long floor, unsigned long ceiling)
 208 {
 209         pgd_t *pgd;
 210         unsigned long next;
 211         unsigned long start;
 212
 213         /*
 214          * The next few lines have given us lots of grief...
 215          *
 216          * Why are we testing PMD* at this top level?  Because often
 217          * there will be no work to do at all, and we'd prefer not to
 218          * go all the way down to the bottom just to discover that.
 219          *
 220          * Why all these "- 1"s?  Because 0 represents both the bottom
 221          * of the address space and the top of it (using -1 for the
 222          * top wouldn't help much: the masks would do the wrong thing).
 223          * The rule is that addr 0 and floor 0 refer to the bottom of
 224          * the address space, but end 0 and ceiling 0 refer to the top
 225          * Comparisons need to use "end - 1" and "ceiling - 1" (though
 226          * that end 0 case should be mythical).
 227          *
 228          * Wherever addr is brought up or ceiling brought down, we must
 229          * be careful to reject "the opposite 0" before it confuses the
 230          * subsequent tests.  But what about where end is brought down
 231          * by PMD_SIZE below? no, end can't go down to 0 there.
 232          *
 233          * Whereas we round start (addr) and ceiling down, by different
 234          * masks at different levels, in order to test whether a table
 235          * now has no other vmas using it, so can be freed, we don't
 236          * bother to round floor or end up - the tests don't need that.
 237          */
 238
 239         addr &= PMD_MASK;
 240         if (addr < floor) {
 241                 addr += PMD_SIZE;
 242                 if (!addr)
 243                         return;
 244         }
 245         if (ceiling) {
 246                 ceiling &= PMD_MASK;
 247                 if (!ceiling)
 248                         return;
 249         }
 250         if (end - 1 > ceiling - 1)
 251                 end -= PMD_SIZE;
 252         if (addr > end - 1)
 253                 return;
 254
 255         start = addr;
 256         pgd = pgd_offset((*tlb)->mm, addr);
 257         do {
 258                 next = pgd_addr_end(addr, end);
 259                 if (pgd_none_or_clear_bad(pgd))
 260                         continue;
 261                 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
 262         } while (pgd++, addr = next, addr != end);
 263
 264         if (!(*tlb)->fullmm)
 265                 flush_tlb_pgtables((*tlb)->mm, start, end);
 266 }
 267
 268 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
 269                 unsigned long floor, unsigned long ceiling)
 270 {
 271         while (vma) {
 272                 struct vm_area_struct *next = vma->vm_next;
 273                 unsigned long addr = vma->vm_start;
 274
 275                 /*
 276                  * Hide vma from rmap and vmtruncate before freeing pgtables
 277                  */
 278                 anon_vma_unlink(vma);
 279                 unlink_file_vma(vma);
 280
 281                 if (is_vm_hugetlb_page(vma)) {
 282                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 283                                 floor, next? next->vm_start: ceiling);
 284                 } else {
 285                         /*
 286                          * Optimization: gather nearby vmas into one call down
 287                          */
 288                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 289                                && !is_vm_hugetlb_page(next)) {
 290                                 vma = next;
 291                                 next = vma->vm_next;
 292                                 anon_vma_unlink(vma);
 293                                 unlink_file_vma(vma);
 294                         }
 295                         free_pgd_range(tlb, addr, vma->vm_end,
 296                                 floor, next? next->vm_start: ceiling);
 297                 }
 298                 vma = next;
 299         }
 300 }
 301
 302 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 303 {
 304         struct page *new = pte_alloc_one(mm, address);
 305         if (!new)
 306                 return -ENOMEM;
 307
 308         pte_lock_init(new);
 309         spin_lock(&mm->page_table_lock);
 310         if (pmd_present(*pmd)) {        /* Another has populated it */
 311                 pte_lock_deinit(new);
 312                 pte_free(new);
 313         } else {
 314                 mm->nr_ptes++;
 315                 inc_zone_page_state(new, NR_PAGETABLE);
 316                 pmd_populate(mm, pmd, new);
 317         }
 318         spin_unlock(&mm->page_table_lock);
 319         return 0;
 320 }
 321
 322 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 323 {
 324         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 325         if (!new)
 326                 return -ENOMEM;
 327
 328         spin_lock(&init_mm.page_table_lock);
 329         if (pmd_present(*pmd))          /* Another has populated it */
 330                 pte_free_kernel(new);
 331         else
 332                 pmd_populate_kernel(&init_mm, pmd, new);
 333         spin_unlock(&init_mm.page_table_lock);
 334         return 0;
 335 }
 336
 337 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
 338 {
 339         if (file_rss)
 340                 add_mm_counter(mm, file_rss, file_rss);
 341         if (anon_rss)
 342                 add_mm_counter(mm, anon_rss, anon_rss);
 343 }
 344
 345 /*
 346  * This function is called to print an error when a bad pte
 347  * is found. For example, we might have a PFN-mapped pte in
 348  * a region that doesn't allow it.
 349  *
 350  * The calling function must still handle the error.
 351  */
 352 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
 353 {
 354         printk(KERN_ERR "Bad pte = %08llx, process = %s, "
 355                         "vm_flags = %lx, vaddr = %lx\n",
 356                 (long long)pte_val(pte),
 357                 (vma->vm_mm == current->mm ? current->comm : "???"),
 358                 vma->vm_flags, vaddr);
 359         dump_stack();
 360 }
 361
 362 static inline int is_cow_mapping(unsigned int flags)
 363 {
 364         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 365 }
 366
 367 /*
 368  * This function gets the "struct page" associated with a pte.
 369  *
 370  * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
 371  * will have each page table entry just pointing to a raw page frame
 372  * number, and as far as the VM layer is concerned, those do not have
 373  * pages associated with them - even if the PFN might point to memory
 374  * that otherwise is perfectly fine and has a "struct page".
 375  *
 376  * The way we recognize those mappings is through the rules set up
 377  * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
 378  * and the vm_pgoff will point to the first PFN mapped: thus every
 379  * page that is a raw mapping will always honor the rule
 380  *
 381  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 382  *
 383  * and if that isn't true, the page has been COW'ed (in which case it
 384  * _does_ have a "struct page" associated with it even if it is in a
 385  * VM_PFNMAP range).
 386  */
 387 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 388 {
 389         unsigned long pfn = pte_pfn(pte);
 390
 391         if (unlikely(vma->vm_flags & VM_PFNMAP)) {
 392                 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
 393                 if (pfn == vma->vm_pgoff + off)
 394                         return NULL;
 395                 if (!is_cow_mapping(vma->vm_flags))
 396                         return NULL;
 397         }
 398
 399         /*
 400          * Add some anal sanity checks for now. Eventually,
 401          * we should just do "return pfn_to_page(pfn)", but
 402          * in the meantime we check that we get a valid pfn,
 403          * and that the resulting page looks ok.
 404          */
 405         if (unlikely(!pfn_valid(pfn))) {
 406                 print_bad_pte(vma, pte, addr);
 407                 return NULL;
 408         }
 409
 410         /*
 411          * NOTE! We still have PageReserved() pages in the page
 412          * tables.
 413          *
 414          * The PAGE_ZERO() pages and various VDSO mappings can
 415          * cause them to exist.
 416          */
 417         return pfn_to_page(pfn);
 418 }
 419
 420 /*
 421  * copy one vm_area from one task to the other. Assumes the page tables
 422  * already present in the new task to be cleared in the whole range
 423  * covered by this vma.
 424  */
 425
 426 static inline void
 427 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 428                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 429                 unsigned long addr, int *rss)
 430 {
 431         unsigned long vm_flags = vma->vm_flags;
 432         pte_t pte = *src_pte;
 433         struct page *page;
 434
 435         /* pte contains position in swap or file, so copy. */
 436         if (unlikely(!pte_present(pte))) {
 437                 if (!pte_file(pte)) {
 438                         swp_entry_t entry = pte_to_swp_entry(pte);
 439
 440                         swap_duplicate(entry);
 441                         /* make sure dst_mm is on swapoff's mmlist. */
 442                         if (unlikely(list_empty(&dst_mm->mmlist))) {
 443                                 spin_lock(&mmlist_lock);
 444                                 if (list_empty(&dst_mm->mmlist))
 445                                         list_add(&dst_mm->mmlist,
 446                                                  &src_mm->mmlist);
 447                                 spin_unlock(&mmlist_lock);
 448                         }
 449                         if (is_write_migration_entry(entry) &&
 450                                         is_cow_mapping(vm_flags)) {
 451                                 /*
 452                                  * COW mappings require pages in both parent
 453                                  * and child to be set to read.
 454                                  */
 455                                 make_migration_entry_read(&entry);
 456                                 pte = swp_entry_to_pte(entry);
 457                                 set_pte_at(src_mm, addr, src_pte, pte);
 458                         }
 459                 }
 460                 goto out_set_pte;
 461         }
 462
 463         /*
 464          * If it's a COW mapping, write protect it both
 465          * in the parent and the child
 466          */
 467         if (is_cow_mapping(vm_flags)) {
 468                 ptep_set_wrprotect(src_mm, addr, src_pte);
 469                 pte = *src_pte;
 470         }
 471
 472         /*
 473          * If it's a shared mapping, mark it clean in
 474          * the child
 475          */
 476         if (vm_flags & VM_SHARED)
 477                 pte = pte_mkclean(pte);
 478         pte = pte_mkold(pte);
 479
 480         page = vm_normal_page(vma, addr, pte);
 481         if (page) {
 482                 get_page(page);
 483                 page_dup_rmap(page);
 484                 rss[!!PageAnon(page)]++;
 485         }
 486
 487 out_set_pte:
 488         set_pte_at(dst_mm, addr, dst_pte, pte);
 489 }
 490
 491 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 492                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 493                 unsigned long addr, unsigned long end)
 494 {
 495         pte_t *src_pte, *dst_pte;
 496         spinlock_t *src_ptl, *dst_ptl;
 497         int progress = 0;
 498         int rss[2];
 499
 500 again:
 501         rss[1] = rss[0] = 0;
 502         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 503         if (!dst_pte)
 504                 return -ENOMEM;
 505         src_pte = pte_offset_map_nested(src_pmd, addr);
 506         src_ptl = pte_lockptr(src_mm, src_pmd);
 507         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 508
 509         do {
 510                 /*
 511                  * We are holding two locks at this point - either of them
 512                  * could generate latencies in another task on another CPU.
 513                  */
 514                 if (progress >= 32) {
 515                         progress = 0;
 516                         if (need_resched() ||
 517                             need_lockbreak(src_ptl) ||
 518                             need_lockbreak(dst_ptl))
 519                                 break;
 520                 }
 521                 if (pte_none(*src_pte)) {
 522                         progress++;
 523                         continue;
 524                 }
 525                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
 526                 progress += 8;
 527         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 528
 529         spin_unlock(src_ptl);
 530         pte_unmap_nested(src_pte - 1);
 531         add_mm_rss(dst_mm, rss[0], rss[1]);
 532         pte_unmap_unlock(dst_pte - 1, dst_ptl);
 533         cond_resched();
 534         if (addr != end)
 535                 goto again;
 536         return 0;
 537 }
 538
 539 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 540                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 541                 unsigned long addr, unsigned long end)
 542 {
 543         pmd_t *src_pmd, *dst_pmd;
 544         unsigned long next;
 545
 546         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 547         if (!dst_pmd)
 548                 return -ENOMEM;
 549         src_pmd = pmd_offset(src_pud, addr);
 550         do {
 551                 next = pmd_addr_end(addr, end);
 552                 if (pmd_none_or_clear_bad(src_pmd))
 553                         continue;
 554                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
 555                                                 vma, addr, next))
 556                         return -ENOMEM;
 557         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 558         return 0;
 559 }
 560
 561 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 562                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
 563                 unsigned long addr, unsigned long end)
 564 {
 565         pud_t *src_pud, *dst_pud;
 566         unsigned long next;
 567
 568         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
 569         if (!dst_pud)
 570                 return -ENOMEM;
 571         src_pud = pud_offset(src_pgd, addr);
 572         do {
 573                 next = pud_addr_end(addr, end);
 574                 if (pud_none_or_clear_bad(src_pud))
 575                         continue;
 576                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
 577                                                 vma, addr, next))
 578                         return -ENOMEM;
 579         } while (dst_pud++, src_pud++, addr = next, addr != end);
 580         return 0;
 581 }
 582
 583 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 584                 struct vm_area_struct *vma)
 585 {
 586         pgd_t *src_pgd, *dst_pgd;
 587         unsigned long next;
 588         unsigned long addr = vma->vm_start;
 589         unsigned long end = vma->vm_end;
 590
 591         /*
 592          * Don't copy ptes where a page fault will fill them correctly.
 593          * Fork becomes much lighter when there are big shared or private
 594          * readonly mappings. The tradeoff is that copy_page_range is more
 595          * efficient than faulting.
 596          */
 597         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
 598                 if (!vma->anon_vma)
 599                         return 0;
 600         }
 601
 602         if (is_vm_hugetlb_page(vma))
 603                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 604
 605         dst_pgd = pgd_offset(dst_mm, addr);
 606         src_pgd = pgd_offset(src_mm, addr);
 607         do {
 608                 next = pgd_addr_end(addr, end);
 609                 if (pgd_none_or_clear_bad(src_pgd))
 610                         continue;
 611                 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
 612                                                 vma, addr, next))
 613                         return -ENOMEM;
 614         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
 615         return 0;
 616 }
 617
 618 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 619                                 struct vm_area_struct *vma, pmd_t *pmd,
 620                                 unsigned long addr, unsigned long end,
 621                                 long *zap_work, struct zap_details *details)
 622 {
 623         struct mm_struct *mm = tlb->mm;
 624         pte_t *pte;
 625         spinlock_t *ptl;
 626         int file_rss = 0;
 627         int anon_rss = 0;
 628
 629         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 630         do {
 631                 pte_t ptent = *pte;
 632                 if (pte_none(ptent)) {
 633                         (*zap_work)--;
 634                         continue;
 635                 }
 636
 637                 (*zap_work) -= PAGE_SIZE;
 638
 639                 if (pte_present(ptent)) {
 640                         struct page *page;
 641
 642                         page = vm_normal_page(vma, addr, ptent);
 643                         if (unlikely(details) && page) {
 644                                 /*
 645                                  * unmap_shared_mapping_pages() wants to
 646                                  * invalidate cache without truncating:
 647                                  * unmap shared but keep private pages.
 648                                  */
 649                                 if (details->check_mapping &&
 650                                     details->check_mapping != page->mapping)
 651                                         continue;
 652                                 /*
 653                                  * Each page->index must be checked when
 654                                  * invalidating or truncating nonlinear.
 655                                  */
 656                                 if (details->nonlinear_vma &&
 657                                     (page->index < details->first_index ||
 658                                      page->index > details->last_index))
 659                                         continue;
 660                         }
 661                         ptent = ptep_get_and_clear_full(mm, addr, pte,
 662                                                         tlb->fullmm);
 663                         tlb_remove_tlb_entry(tlb, pte, addr);
 664                         if (unlikely(!page))
 665                                 continue;
 666                         if (unlikely(details) && details->nonlinear_vma
 667                             && linear_page_index(details->nonlinear_vma,
 668                                                 addr) != page->index)
 669                                 set_pte_at(mm, addr, pte,
 670                                            pgoff_to_pte(page->index));
 671                         if (PageAnon(page))
 672                                 anon_rss--;
 673                         else {
 674                                 if (pte_dirty(ptent))
 675                                         set_page_dirty(page);
 676                                 if (pte_young(ptent))
 677                                         mark_page_accessed(page);
 678                                 file_rss--;
 679                         }
 680                         page_remove_rmap(page);
 681                         tlb_remove_page(tlb, page);
 682                         continue;
 683                 }
 684                 /*
 685                  * If details->check_mapping, we leave swap entries;
 686                  * if details->nonlinear_vma, we leave file entries.
 687                  */
 688                 if (unlikely(details))
 689                         continue;
 690                 if (!pte_file(ptent))
 691                         free_swap_and_cache(pte_to_swp_entry(ptent));
 692                 pte_clear_full(mm, addr, pte, tlb->fullmm);
 693         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
 694
 695         add_mm_rss(mm, file_rss, anon_rss);
 696         pte_unmap_unlock(pte - 1, ptl);
 697
 698         return addr;
 699 }
 700
 701 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 702                                 struct vm_area_struct *vma, pud_t *pud,
 703                                 unsigned long addr, unsigned long end,
 704                                 long *zap_work, struct zap_details *details)
 705 {
 706         pmd_t *pmd;
 707         unsigned long next;
 708
 709         pmd = pmd_offset(pud, addr);
 710         do {
 711                 next = pmd_addr_end(addr, end);
 712                 if (pmd_none_or_clear_bad(pmd)) {
 713                         (*zap_work)--;
 714                         continue;
 715                 }
 716                 next = zap_pte_range(tlb, vma, pmd, addr, next,
 717                                                 zap_work, details);
 718         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
 719
 720         return addr;
 721 }
 722
 723 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 724                                 struct vm_area_struct *vma, pgd_t *pgd,
 725                                 unsigned long addr, unsigned long end,
 726                                 long *zap_work, struct zap_details *details)
 727 {
 728         pud_t *pud;
 729         unsigned long next;
 730
 731         pud = pud_offset(pgd, addr);
 732         do {
 733                 next = pud_addr_end(addr, end);
 734                 if (pud_none_or_clear_bad(pud)) {
 735                         (*zap_work)--;
 736                         continue;
 737                 }
 738                 next = zap_pmd_range(tlb, vma, pud, addr, next,
 739                                                 zap_work, details);
 740         } while (pud++, addr = next, (addr != end && *zap_work > 0));
 741
 742         return addr;
 743 }
 744
 745 static unsigned long unmap_page_range(struct mmu_gather *tlb,
 746                                 struct vm_area_struct *vma,
 747                                 unsigned long addr, unsigned long end,
 748                                 long *zap_work, struct zap_details *details)
 749 {
 750         pgd_t *pgd;
 751         unsigned long next;
 752
 753         if (details && !details->check_mapping && !details->nonlinear_vma)
 754                 details = NULL;
 755
 756         BUG_ON(addr >= end);
 757         tlb_start_vma(tlb, vma);
 758         pgd = pgd_offset(vma->vm_mm, addr);
 759         do {
 760                 next = pgd_addr_end(addr, end);
 761                 if (pgd_none_or_clear_bad(pgd)) {
 762                         (*zap_work)--;
 763                         continue;
 764                 }
 765                 next = zap_pud_range(tlb, vma, pgd, addr, next,
 766                                                 zap_work, details);
 767         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
 768         tlb_end_vma(tlb, vma);
 769
 770         return addr;
 771 }
 772
 773 #ifdef CONFIG_PREEMPT
 774 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
 775 #else
 776 /* No preempt: go for improved straight-line efficiency */
 777 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
 778 #endif
 779
 780 /**
 781  * unmap_vmas - unmap a range of memory covered by a list of vma's
 782  * @tlbp: address of the caller's struct mmu_gather
 783  * @vma: the starting vma
 784  * @start_addr: virtual address at which to start unmapping
 785  * @end_addr: virtual address at which to end unmapping
 786  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 787  * @details: details of nonlinear truncation or shared cache invalidation
 788  *
 789  * Returns the end address of the unmapping (restart addr if interrupted).
 790  *
 791  * Unmap all pages in the vma list.
 792  *
 793  * We aim to not hold locks for too long (for scheduling latency reasons).
 794  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
 795  * return the ending mmu_gather to the caller.
 796  *
 797  * Only addresses between `start' and `end' will be unmapped.
 798  *
 799  * The VMA list must be sorted in ascending virtual address order.
 800  *
 801  * unmap_vmas() assumes that the caller will flush the whole unmapped address
 802  * range after unmap_vmas() returns.  So the only responsibility here is to
 803  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 804  * drops the lock and schedules.
 805  */
 806 unsigned long unmap_vmas(struct mmu_gather **tlbp,
 807                 struct vm_area_struct *vma, unsigned long start_addr,
 808                 unsigned long end_addr, unsigned long *nr_accounted,
 809                 struct zap_details *details)
 810 {
 811         long zap_work = ZAP_BLOCK_SIZE;
 812         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
 813         int tlb_start_valid = 0;
 814         unsigned long start = start_addr;
 815         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
 816         int fullmm = (*tlbp)->fullmm;
 817
 818         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
 819                 unsigned long end;
 820
 821                 start = max(vma->vm_start, start_addr);
 822                 if (start >= vma->vm_end)
 823                         continue;
 824                 end = min(vma->vm_end, end_addr);
 825                 if (end <= vma->vm_start)
 826                         continue;
 827
 828                 if (vma->vm_flags & VM_ACCOUNT)
 829                         *nr_accounted += (end - start) >> PAGE_SHIFT;
 830
 831                 while (start != end) {
 832                         if (!tlb_start_valid) {
 833                                 tlb_start = start;
 834                                 tlb_start_valid = 1;
 835                         }
 836
 837                         if (unlikely(is_vm_hugetlb_page(vma))) {
 838                                 unmap_hugepage_range(vma, start, end);
 839                                 zap_work -= (end - start) /
 840                                                 (HPAGE_SIZE / PAGE_SIZE);
 841                                 start = end;
 842                         } else
 843                                 start = unmap_page_range(*tlbp, vma,
 844                                                 start, end, &zap_work, details);
 845
 846                         if (zap_work > 0) {
 847                                 BUG_ON(start != end);
 848                                 break;
 849                         }
 850
 851                         tlb_finish_mmu(*tlbp, tlb_start, start);
 852
 853                         if (need_resched() ||
 854                                 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
 855                                 if (i_mmap_lock) {
 856                                         *tlbp = NULL;
 857                                         goto out;
 858                                 }
 859                                 cond_resched();
 860                         }
 861
 862                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
 863                         tlb_start_valid = 0;
 864                         zap_work = ZAP_BLOCK_SIZE;
 865                 }
 866         }
 867 out:
 868         return start;   /* which is now the end (or restart) address */
 869 }
 870
 871 /**
 872  * zap_page_range - remove user pages in a given range
 873  * @vma: vm_area_struct holding the applicable pages
 874  * @address: starting address of pages to zap
 875  * @size: number of bytes to zap
 876  * @details: details of nonlinear truncation or shared cache invalidation
 877  */
 878 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
 879                 unsigned long size, struct zap_details *details)
 880 {
 881         struct mm_struct *mm = vma->vm_mm;
 882         struct mmu_gather *tlb;
 883         unsigned long end = address + size;
 884         unsigned long nr_accounted = 0;
 885
 886         lru_add_drain();
 887         tlb = tlb_gather_mmu(mm, 0);
 888         update_hiwater_rss(mm);
 889         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
 890         if (tlb)
 891                 tlb_finish_mmu(tlb, address, end);
 892         return end;
 893 }
 894
 895 /*
 896  * Do a quick page-table lookup for a single page.
 897  */
 898 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 899                         unsigned int flags)
 900 {
 901         pgd_t *pgd;
 902         pud_t *pud;
 903         pmd_t *pmd;
 904         pte_t *ptep, pte;
 905         spinlock_t *ptl;
 906         struct page *page;
 907         struct mm_struct *mm = vma->vm_mm;
 908
 909         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
 910         if (!IS_ERR(page)) {
 911                 BUG_ON(flags & FOLL_GET);
 912                 goto out;
 913         }
 914
 915         page = NULL;
 916         pgd = pgd_offset(mm, address);
 917         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
 918                 goto no_page_table;
 919
 920         pud = pud_offset(pgd, address);
 921         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
 922                 goto no_page_table;
 923
 924         pmd = pmd_offset(pud, address);
 925         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
 926                 goto no_page_table;
 927
 928         if (pmd_huge(*pmd)) {
 929                 BUG_ON(flags & FOLL_GET);
 930                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
 931                 goto out;
 932         }
 933
 934         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
 935         if (!ptep)
 936                 goto out;
 937
 938         pte = *ptep;
 939         if (!pte_present(pte))
 940                 goto unlock;
 941         if ((flags & FOLL_WRITE) && !pte_write(pte))
 942                 goto unlock;
 943         page = vm_normal_page(vma, address, pte);
 944         if (unlikely(!page))
 945                 goto unlock;
 946
 947         if (flags & FOLL_GET)
 948                 get_page(page);
 949         if (flags & FOLL_TOUCH) {
 950                 if ((flags & FOLL_WRITE) &&
 951                     !pte_dirty(pte) && !PageDirty(page))
 952                         set_page_dirty(page);
 953                 mark_page_accessed(page);
 954         }
 955 unlock:
 956         pte_unmap_unlock(ptep, ptl);
 957 out:
 958         return page;
 959
 960 no_page_table:
 961         /*
 962          * When core dumping an enormous anonymous area that nobody
 963          * has touched so far, we don't want to allocate page tables.
 964          */
 965         if (flags & FOLL_ANON) {
 966                 page = ZERO_PAGE(address);
 967                 if (flags & FOLL_GET)
 968                         get_page(page);
 969                 BUG_ON(flags & FOLL_WRITE);
 970         }
 971         return page;
 972 }
 973
 974 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 975                 unsigned long start, int len, int write, int force,
 976                 struct page **pages, struct vm_area_struct **vmas)
 977 {
 978         int i;
 979         unsigned int vm_flags;
 980
 981         /*
 982          * Require read or write permissions.
 983          * If 'force' is set, we only require the "MAY" flags.
 984          */
 985         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 986         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 987         i = 0;
 988
 989         do {
 990                 struct vm_area_struct *vma;
 991                 unsigned int foll_flags;
 992
 993                 vma = find_extend_vma(mm, start);
 994                 if (!vma && in_gate_area(tsk, start)) {
 995                         unsigned long pg = start & PAGE_MASK;
 996                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
 997                         pgd_t *pgd;
 998                         pud_t *pud;
 999                         pmd_t *pmd;
1000                         pte_t *pte;
1001                         if (write) /* user gate pages are read-only */
1002                                 return i ? : -EFAULT;
1003                         if (pg > TASK_SIZE)
1004                                 pgd = pgd_offset_k(pg);
1005                         else
1006                                 pgd = pgd_offset_gate(mm, pg);
1007                         BUG_ON(pgd_none(*pgd));
1008                         pud = pud_offset(pgd, pg);
1009                         BUG_ON(pud_none(*pud));
1010                         pmd = pmd_offset(pud, pg);
1011                         if (pmd_none(*pmd))
1012                                 return i ? : -EFAULT;
1013                         pte = pte_offset_map(pmd, pg);
1014                         if (pte_none(*pte)) {
1015                                 pte_unmap(pte);
1016                                 return i ? : -EFAULT;
1017                         }
1018                         if (pages) {
1019                                 struct page *page = vm_normal_page(gate_vma, start, *pte);
1020                                 pages[i] = page;
1021                                 if (page)
1022                                         get_page(page);
1023                         }
1024                         pte_unmap(pte);
1025                         if (vmas)
1026                                 vmas[i] = gate_vma;
1027                         i++;
1028                         start += PAGE_SIZE;
1029                         len--;
1030                         continue;
1031                 }
1032
1033                 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1034                                 || !(vm_flags & vma->vm_flags))
1035                         return i ? : -EFAULT;
1036
1037                 if (is_vm_hugetlb_page(vma)) {
1038                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1039                                                 &start, &len, i);
1040                         continue;
1041                 }
1042
1043                 foll_flags = FOLL_TOUCH;
1044                 if (pages)
1045                         foll_flags |= FOLL_GET;
1046                 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1047                     (!vma->vm_ops || !vma->vm_ops->nopage))
1048                         foll_flags |= FOLL_ANON;
1049
1050                 do {
1051                         struct page *page;
1052
1053                         if (write)
1054                                 foll_flags |= FOLL_WRITE;
1055
1056                         cond_resched();
1057                         while (!(page = follow_page(vma, start, foll_flags))) {
1058                                 int ret;
1059                                 ret = __handle_mm_fault(mm, vma, start,
1060                                                 foll_flags & FOLL_WRITE);
1061                                 /*
1062                                  * The VM_FAULT_WRITE bit tells us that do_wp_page has
1063                                  * broken COW when necessary, even if maybe_mkwrite
1064                                  * decided not to set pte_write. We can thus safely do
1065                                  * subsequent page lookups as if they were reads.
1066                                  */
1067                                 if (ret & VM_FAULT_WRITE)
1068                                         foll_flags &= ~FOLL_WRITE;
1069
1070                                 switch (ret & ~VM_FAULT_WRITE) {
1071                                 case VM_FAULT_MINOR:
1072                                         tsk->min_flt++;
1073                                         break;
1074                                 case VM_FAULT_MAJOR:
1075                                         tsk->maj_flt++;
1076                                         break;
1077                                 case VM_FAULT_SIGBUS:
1078                                         return i ? i : -EFAULT;
1079                                 case VM_FAULT_OOM:
1080                                         return i ? i : -ENOMEM;
1081                                 default:
1082                                         BUG();
1083                                 }
1084                         }
1085                         if (pages) {
1086                                 pages[i] = page;
1087
1088                                 flush_anon_page(page, start);
1089                                 flush_dcache_page(page);
1090                         }
1091                         if (vmas)
1092                                 vmas[i] = vma;
1093                         i++;
1094                         start += PAGE_SIZE;
1095                         len--;
1096                 } while (len && start < vma->vm_end);
1097         } while (len);
1098         return i;
1099 }
1100 EXPORT_SYMBOL(get_user_pages);
1101
1102 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1103                         unsigned long addr, unsigned long end, pgprot_t prot)
1104 {
1105         pte_t *pte;
1106         spinlock_t *ptl;
1107
1108         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1109         if (!pte)
1110                 return -ENOMEM;
1111         do {
1112                 struct page *page = ZERO_PAGE(addr);
1113                 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1114                 page_cache_get(page);
1115                 page_add_file_rmap(page);
1116                 inc_mm_counter(mm, file_rss);
1117                 BUG_ON(!pte_none(*pte));
1118                 set_pte_at(mm, addr, pte, zero_pte);
1119         } while (pte++, addr += PAGE_SIZE, addr != end);
1120         pte_unmap_unlock(pte - 1, ptl);
1121         return 0;
1122 }
1123
1124 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1125                         unsigned long addr, unsigned long end, pgprot_t prot)
1126 {
1127         pmd_t *pmd;
1128         unsigned long next;
1129
1130         pmd = pmd_alloc(mm, pud, addr);
1131         if (!pmd)
1132                 return -ENOMEM;
1133         do {
1134                 next = pmd_addr_end(addr, end);
1135                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1136                         return -ENOMEM;
1137         } while (pmd++, addr = next, addr != end);
1138         return 0;
1139 }
1140
1141 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1142                         unsigned long addr, unsigned long end, pgprot_t prot)
1143 {
1144         pud_t *pud;
1145         unsigned long next;
1146
1147         pud = pud_alloc(mm, pgd, addr);
1148         if (!pud)
1149                 return -ENOMEM;
1150         do {
1151                 next = pud_addr_end(addr, end);
1152                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1153                         return -ENOMEM;
1154         } while (pud++, addr = next, addr != end);
1155         return 0;
1156 }
1157
1158 int zeromap_page_range(struct vm_area_struct *vma,
1159                         unsigned long addr, unsigned long size, pgprot_t prot)
1160 {
1161         pgd_t *pgd;
1162         unsigned long next;
1163         unsigned long end = addr + size;
1164         struct mm_struct *mm = vma->vm_mm;
1165         int err;
1166
1167         BUG_ON(addr >= end);
1168         pgd = pgd_offset(mm, addr);
1169         flush_cache_range(vma, addr, end);
1170         do {
1171                 next = pgd_addr_end(addr, end);
1172                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1173                 if (err)
1174                         break;
1175         } while (pgd++, addr = next, addr != end);
1176         return err;
1177 }
1178
1179 pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1180 {
1181         pgd_t * pgd = pgd_offset(mm, addr);
1182         pud_t * pud = pud_alloc(mm, pgd, addr);
1183         if (pud) {
1184                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1185                 if (pmd)
1186                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1187         }
1188         return NULL;
1189 }
1190
1191 /*
1192  * This is the old fallback for page remapping.
1193  *
1194  * For historical reasons, it only allows reserved pages. Only
1195  * old drivers should use this, and they needed to mark their
1196  * pages reserved for the old functions anyway.
1197  */
1198 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1199 {
1200         int retval;
1201         pte_t *pte;
1202         spinlock_t *ptl;
1203
1204         retval = -EINVAL;
1205         if (PageAnon(page))
1206                 goto out;
1207         retval = -ENOMEM;
1208         flush_dcache_page(page);
1209         pte = get_locked_pte(mm, addr, &ptl);
1210         if (!pte)
1211                 goto out;
1212         retval = -EBUSY;
1213         if (!pte_none(*pte))
1214                 goto out_unlock;
1215
1216         /* Ok, finally just insert the thing.. */
1217         get_page(page);
1218         inc_mm_counter(mm, file_rss);
1219         page_add_file_rmap(page);
1220         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1221
1222         retval = 0;
1223 out_unlock:
1224         pte_unmap_unlock(pte, ptl);
1225 out:
1226         return retval;
1227 }
1228
1229 /*
1230  * This allows drivers to insert individual pages they've allocated
1231  * into a user vma.
1232  *
1233  * The page has to be a nice clean _individual_ kernel allocation.
1234  * If you allocate a compound page, you need to have marked it as
1235  * such (__GFP_COMP), or manually just split the page up yourself
1236  * (see split_page()).
1237  *
1238  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1239  * took an arbitrary page protection parameter. This doesn't allow
1240  * that. Your vma protection will have to be set up correctly, which
1241  * means that if you want a shared writable mapping, you'd better
1242  * ask for a shared writable mapping!
1243  *
1244  * The page does not need to be reserved.
1245  */
1246 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1247 {
1248         if (addr < vma->vm_start || addr >= vma->vm_end)
1249                 return -EFAULT;
1250         if (!page_count(page))
1251                 return -EINVAL;
1252         vma->vm_flags |= VM_INSERTPAGE;
1253         return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1254 }
1255 EXPORT_SYMBOL(vm_insert_page);
1256
1257 /*
1258  * maps a range of physical memory into the requested pages. the old
1259  * mappings are removed. any references to nonexistent pages results
1260  * in null mappings (currently treated as "copy-on-access")
1261  */
1262 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1263                         unsigned long addr, unsigned long end,
1264                         unsigned long pfn, pgprot_t prot)
1265 {
1266         pte_t *pte;
1267         spinlock_t *ptl;
1268
1269         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1270         if (!pte)
1271                 return -ENOMEM;
1272         do {
1273                 BUG_ON(!pte_none(*pte));
1274                 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1275                 pfn++;
1276         } while (pte++, addr += PAGE_SIZE, addr != end);
1277         pte_unmap_unlock(pte - 1, ptl);
1278         return 0;
1279 }
1280
1281 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1282                         unsigned long addr, unsigned long end,
1283                         unsigned long pfn, pgprot_t prot)
1284 {
1285         pmd_t *pmd;
1286         unsigned long next;
1287
1288         pfn -= addr >> PAGE_SHIFT;
1289         pmd = pmd_alloc(mm, pud, addr);
1290         if (!pmd)
1291                 return -ENOMEM;
1292         do {
1293                 next = pmd_addr_end(addr, end);
1294                 if (remap_pte_range(mm, pmd, addr, next,
1295                                 pfn + (addr >> PAGE_SHIFT), prot))
1296                         return -ENOMEM;
1297         } while (pmd++, addr = next, addr != end);
1298         return 0;
1299 }
1300
1301 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1302                         unsigned long addr, unsigned long end,
1303                         unsigned long pfn, pgprot_t prot)
1304 {
1305         pud_t *pud;
1306         unsigned long next;
1307
1308         pfn -= addr >> PAGE_SHIFT;
1309         pud = pud_alloc(mm, pgd, addr);
1310         if (!pud)
1311                 return -ENOMEM;
1312         do {
1313                 next = pud_addr_end(addr, end);
1314                 if (remap_pmd_range(mm, pud, addr, next,
1315                                 pfn + (addr >> PAGE_SHIFT), prot))
1316                         return -ENOMEM;
1317         } while (pud++, addr = next, addr != end);
1318         return 0;
1319 }
1320
1321 /*  Note: this is only safe if the mm semaphore is held when called. */
1322 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1323                     unsigned long pfn, unsigned long size, pgprot_t prot)
1324 {
1325         pgd_t *pgd;
1326         unsigned long next;
1327         unsigned long end = addr + PAGE_ALIGN(size);
1328         struct mm_struct *mm = vma->vm_mm;
1329         int err;
1330
1331         /*
1332          * Physically remapped pages are special. Tell the
1333          * rest of the world about it:
1334          *   VM_IO tells people not to look at these pages
1335          *      (accesses can have side effects).
1336          *   VM_RESERVED is specified all over the place, because
1337          *      in 2.4 it kept swapout's vma scan off this vma; but
1338          *      in 2.6 the LRU scan won't even find its pages, so this
1339          *      flag means no more than count its pages in reserved_vm,
1340          *      and omit it from core dump, even when VM_IO turned off.
1341          *   VM_PFNMAP tells the core MM that the base pages are just
1342          *      raw PFN mappings, and do not have a "struct page" associated
1343          *      with them.
1344          *
1345          * There's a horrible special case to handle copy-on-write
1346          * behaviour that some programs depend on. We mark the "original"
1347          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1348          */
1349         if (is_cow_mapping(vma->vm_flags)) {
1350                 if (addr != vma->vm_start || end != vma->vm_end)
1351                         return -EINVAL;
1352                 vma->vm_pgoff = pfn;
1353         }
1354
1355         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1356
1357         BUG_ON(addr >= end);
1358         pfn -= addr >> PAGE_SHIFT;
1359         pgd = pgd_offset(mm, addr);
1360         flush_cache_range(vma, addr, end);
1361         do {
1362                 next = pgd_addr_end(addr, end);
1363                 err = remap_pud_range(mm, pgd, addr, next,
1364                                 pfn + (addr >> PAGE_SHIFT), prot);
1365                 if (err)
1366                         break;
1367         } while (pgd++, addr = next, addr != end);
1368         return err;
1369 }
1370 EXPORT_SYMBOL(remap_pfn_range);
1371
1372 /*
1373  * handle_pte_fault chooses page fault handler according to an entry
1374  * which was read non-atomically.  Before making any commitment, on
1375  * those architectures or configurations (e.g. i386 with PAE) which
1376  * might give a mix of unmatched parts, do_swap_page and do_file_page
1377  * must check under lock before unmapping the pte and proceeding
1378  * (but do_wp_page is only called after already making such a check;
1379  * and do_anonymous_page and do_no_page can safely check later on).
1380  */
1381 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1382                                 pte_t *page_table, pte_t orig_pte)
1383 {
1384         int same = 1;
1385 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1386         if (sizeof(pte_t) > sizeof(unsigned long)) {
1387                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1388                 spin_lock(ptl);
1389                 same = pte_same(*page_table, orig_pte);
1390                 spin_unlock(ptl);
1391         }
1392 #endif
1393         pte_unmap(page_table);
1394         return same;
1395 }
1396
1397 /*
1398  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1399  * servicing faults for write access.  In the normal case, do always want
1400  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1401  * that do not have writing enabled, when used by access_process_vm.
1402  */
1403 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1404 {
1405         if (likely(vma->vm_flags & VM_WRITE))
1406                 pte = pte_mkwrite(pte);
1407         return pte;
1408 }
1409
1410 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1411 {
1412         /*
1413          * If the source page was a PFN mapping, we don't have
1414          * a "struct page" for it. We do a best-effort copy by
1415          * just copying from the original user address. If that
1416          * fails, we just zero-fill it. Live with it.
1417          */
1418         if (unlikely(!src)) {
1419                 void *kaddr = kmap_atomic(dst, KM_USER0);
1420                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1421
1422                 /*
1423                  * This really shouldn't fail, because the page is there
1424                  * in the page tables. But it might just be unreadable,
1425                  * in which case we just give up and fill the result with
1426                  * zeroes.
1427                  */
1428                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1429                         memset(kaddr, 0, PAGE_SIZE);
1430                 kunmap_atomic(kaddr, KM_USER0);
1431                 return;
1432
1433         }
1434         copy_user_highpage(dst, src, va);
1435 }
1436
1437 /*
1438  * This routine handles present pages, when users try to write
1439  * to a shared page. It is done by copying the page to a new address
1440  * and decrementing the shared-page counter for the old page.
1441  *
1442  * Note that this routine assumes that the protection checks have been
1443  * done by the caller (the low-level page fault routine in most cases).
1444  * Thus we can safely just mark it writable once we've done any necessary
1445  * COW.
1446  *
1447  * We also mark the page dirty at this point even though the page will
1448  * change only once the write actually happens. This avoids a few races,
1449  * and potentially makes it more efficient.
1450  *
1451  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1452  * but allow concurrent faults), with pte both mapped and locked.
1453  * We return with mmap_sem still held, but pte unmapped and unlocked.
1454  */
1455 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1456                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1457                 spinlock_t *ptl, pte_t orig_pte)
1458 {
1459         struct page *old_page, *new_page;
1460         pte_t entry;
1461         int reuse = 0, ret = VM_FAULT_MINOR;
1462         struct page *dirty_page = NULL;
1463
1464         old_page = vm_normal_page(vma, address, orig_pte);
1465         if (!old_page)
1466                 goto gotten;
1467
1468         /*
1469          * Only catch write-faults on shared writable pages, read-only
1470          * shared pages can get COWed by get_user_pages(.write=1, .force=1).
1471          */
1472         if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1473                                         (VM_WRITE|VM_SHARED))) {
1474                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1475                         /*
1476                          * Notify the address space that the page is about to
1477                          * become writable so that it can prohibit this or wait
1478                          * for the page to get into an appropriate state.
1479                          *
1480                          * We do this without the lock held, so that it can
1481                          * sleep if it needs to.
1482                          */
1483                         page_cache_get(old_page);
1484                         pte_unmap_unlock(page_table, ptl);
1485
1486                         if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1487                                 goto unwritable_page;
1488
1489                         page_cache_release(old_page);
1490
1491                         /*
1492                          * Since we dropped the lock we need to revalidate
1493                          * the PTE as someone else may have changed it.  If
1494                          * they did, we just return, as we can count on the
1495                          * MMU to tell us if they didn't also make it writable.
1496                          */
1497                         page_table = pte_offset_map_lock(mm, pmd, address,
1498                                                          &ptl);
1499                         if (!pte_same(*page_table, orig_pte))
1500                                 goto unlock;
1501                 }
1502                 dirty_page = old_page;
1503                 get_page(dirty_page);
1504                 reuse = 1;
1505         } else if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
1506                 reuse = can_share_swap_page(old_page);
1507                 unlock_page(old_page);
1508         }
1509
1510         if (reuse) {
1511                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1512                 entry = pte_mkyoung(orig_pte);
1513                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1514                 ptep_set_access_flags(vma, address, page_table, entry, 1);
1515                 update_mmu_cache(vma, address, entry);
1516                 lazy_mmu_prot_update(entry);
1517                 ret |= VM_FAULT_WRITE;
1518                 goto unlock;
1519         }
1520
1521         /*
1522          * Ok, we need to copy. Oh, well..
1523          */
1524         page_cache_get(old_page);
1525 gotten:
1526         pte_unmap_unlock(page_table, ptl);
1527
1528         if (unlikely(anon_vma_prepare(vma)))
1529                 goto oom;
1530         if (old_page == ZERO_PAGE(address)) {
1531                 new_page = alloc_zeroed_user_highpage(vma, address);
1532                 if (!new_page)
1533                         goto oom;
1534         } else {
1535                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1536                 if (!new_page)
1537                         goto oom;
1538                 cow_user_page(new_page, old_page, address);
1539         }
1540
1541         /*
1542          * Re-check the pte - we dropped the lock
1543          */
1544         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1545         if (likely(pte_same(*page_table, orig_pte))) {
1546                 if (old_page) {
1547                         page_remove_rmap(old_page);
1548                         if (!PageAnon(old_page)) {
1549                                 dec_mm_counter(mm, file_rss);
1550                                 inc_mm_counter(mm, anon_rss);
1551                         }
1552                 } else
1553                         inc_mm_counter(mm, anon_rss);
1554                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1555                 entry = mk_pte(new_page, vma->vm_page_prot);
1556                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1557                 lazy_mmu_prot_update(entry);
1558                 ptep_establish(vma, address, page_table, entry);
1559                 update_mmu_cache(vma, address, entry);
1560                 lru_cache_add_active(new_page);
1561                 page_add_new_anon_rmap(new_page, vma, address);
1562
1563                 /* Free the old page.. */
1564                 new_page = old_page;
1565                 ret |= VM_FAULT_WRITE;
1566         }
1567         if (new_page)
1568                 page_cache_release(new_page);
1569         if (old_page)
1570                 page_cache_release(old_page);
1571 unlock:
1572         pte_unmap_unlock(page_table, ptl);
1573         if (dirty_page) {
1574                 set_page_dirty(dirty_page);
1575                 put_page(dirty_page);
1576         }
1577         return ret;
1578 oom:
1579         if (old_page)
1580                 page_cache_release(old_page);
1581         return VM_FAULT_OOM;
1582
1583 unwritable_page:
1584         page_cache_release(old_page);
1585         return VM_FAULT_SIGBUS;
1586 }
1587
1588 /*
1589  * Helper functions for unmap_mapping_range().
1590  *
1591  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1592  *
1593  * We have to restart searching the prio_tree whenever we drop the lock,
1594  * since the iterator is only valid while the lock is held, and anyway
1595  * a later vma might be split and reinserted earlier while lock dropped.
1596  *
1597  * The list of nonlinear vmas could be handled more efficiently, using
1598  * a placeholder, but handle it in the same way until a need is shown.
1599  * It is important to search the prio_tree before nonlinear list: a vma
1600  * may become nonlinear and be shifted from prio_tree to nonlinear list
1601  * while the lock is dropped; but never shifted from list to prio_tree.
1602  *
1603  * In order to make forward progress despite restarting the search,
1604  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1605  * quickly skip it next time around.  Since the prio_tree search only
1606  * shows us those vmas affected by unmapping the range in question, we
1607  * can't efficiently keep all vmas in step with mapping->truncate_count:
1608  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1609  * mapping->truncate_count and vma->vm_truncate_count are protected by
1610  * i_mmap_lock.
1611  *
1612  * In order to make forward progress despite repeatedly restarting some
1613  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1614  * and restart from that address when we reach that vma again.  It might
1615  * have been split or merged, shrunk or extended, but never shifted: so
1616  * restart_addr remains valid so long as it remains in the vma's range.
1617  * unmap_mapping_range forces truncate_count to leap over page-aligned
1618  * values so we can save vma's restart_addr in its truncate_count field.
1619  */
1620 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1621
1622 static void reset_vma_truncate_counts(struct address_space *mapping)
1623 {
1624         struct vm_area_struct *vma;
1625         struct prio_tree_iter iter;
1626
1627         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1628                 vma->vm_truncate_count = 0;
1629         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1630                 vma->vm_truncate_count = 0;
1631 }
1632
1633 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1634                 unsigned long start_addr, unsigned long end_addr,
1635                 struct zap_details *details)
1636 {
1637         unsigned long restart_addr;
1638         int need_break;
1639
1640 again:
1641         restart_addr = vma->vm_truncate_count;
1642         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1643                 start_addr = restart_addr;
1644                 if (start_addr >= end_addr) {
1645                         /* Top of vma has been split off since last time */
1646                         vma->vm_truncate_count = details->truncate_count;
1647                         return 0;
1648                 }
1649         }
1650
1651         restart_addr = zap_page_range(vma, start_addr,
1652                                         end_addr - start_addr, details);
1653         need_break = need_resched() ||
1654                         need_lockbreak(details->i_mmap_lock);
1655
1656         if (restart_addr >= end_addr) {
1657                 /* We have now completed this vma: mark it so */
1658                 vma->vm_truncate_count = details->truncate_count;
1659                 if (!need_break)
1660                         return 0;
1661         } else {
1662                 /* Note restart_addr in vma's truncate_count field */
1663                 vma->vm_truncate_count = restart_addr;
1664                 if (!need_break)
1665                         goto again;
1666         }
1667
1668         spin_unlock(details->i_mmap_lock);
1669         cond_resched();
1670         spin_lock(details->i_mmap_lock);
1671         return -EINTR;
1672 }
1673
1674 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1675                                             struct zap_details *details)
1676 {
1677         struct vm_area_struct *vma;
1678         struct prio_tree_iter iter;
1679         pgoff_t vba, vea, zba, zea;
1680
1681 restart:
1682         vma_prio_tree_foreach(vma, &iter, root,
1683                         details->first_index, details->last_index) {
1684                 /* Skip quickly over those we have already dealt with */
1685                 if (vma->vm_truncate_count == details->truncate_count)
1686                         continue;
1687
1688                 vba = vma->vm_pgoff;
1689                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1690                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1691                 zba = details->first_index;
1692                 if (zba < vba)
1693                         zba = vba;
1694                 zea = details->last_index;
1695                 if (zea > vea)
1696                         zea = vea;
1697
1698                 if (unmap_mapping_range_vma(vma,
1699                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1700                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1701                                 details) < 0)
1702                         goto restart;
1703         }
1704 }
1705
1706 static inline void unmap_mapping_range_list(struct list_head *head,
1707                                             struct zap_details *details)
1708 {
1709         struct vm_area_struct *vma;
1710
1711         /*
1712          * In nonlinear VMAs there is no correspondence between virtual address
1713          * offset and file offset.  So we must perform an exhaustive search
1714          * across *all* the pages in each nonlinear VMA, not just the pages
1715          * whose virtual address lies outside the file truncation point.
1716          */
1717 restart:
1718         list_for_each_entry(vma, head, shared.vm_set.list) {
1719                 /* Skip quickly over those we have already dealt with */
1720                 if (vma->vm_truncate_count == details->truncate_count)
1721                         continue;
1722                 details->nonlinear_vma = vma;
1723                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1724                                         vma->vm_end, details) < 0)
1725                         goto restart;
1726         }
1727 }
1728
1729 /**
1730  * unmap_mapping_range - unmap the portion of all mmaps
1731  * in the specified address_space corresponding to the specified
1732  * page range in the underlying file.
1733  * @mapping: the address space containing mmaps to be unmapped.
1734  * @holebegin: byte in first page to unmap, relative to the start of
1735  * the underlying file.  This will be rounded down to a PAGE_SIZE
1736  * boundary.  Note that this is different from vmtruncate(), which
1737  * must keep the partial page.  In contrast, we must get rid of
1738  * partial pages.
1739  * @holelen: size of prospective hole in bytes.  This will be rounded
1740  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1741  * end of the file.
1742  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1743  * but 0 when invalidating pagecache, don't throw away private data.
1744  */
1745 void unmap_mapping_range(struct address_space *mapping,
1746                 loff_t const holebegin, loff_t const holelen, int even_cows)
1747 {
1748         struct zap_details details;
1749         pgoff_t hba = holebegin >> PAGE_SHIFT;
1750         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1751
1752         /* Check for overflow. */
1753         if (sizeof(holelen) > sizeof(hlen)) {
1754                 long long holeend =
1755                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1756                 if (holeend & ~(long long)ULONG_MAX)
1757                         hlen = ULONG_MAX - hba + 1;
1758         }
1759
1760         details.check_mapping = even_cows? NULL: mapping;
1761         details.nonlinear_vma = NULL;
1762         details.first_index = hba;
1763         details.last_index = hba + hlen - 1;
1764         if (details.last_index < details.first_index)
1765                 details.last_index = ULONG_MAX;
1766         details.i_mmap_lock = &mapping->i_mmap_lock;
1767
1768         spin_lock(&mapping->i_mmap_lock);
1769
1770         /* serialize i_size write against truncate_count write */
1771         smp_wmb();
1772         /* Protect against page faults, and endless unmapping loops */
1773         mapping->truncate_count++;
1774         /*
1775          * For archs where spin_lock has inclusive semantics like ia64
1776          * this smp_mb() will prevent to read pagetable contents
1777          * before the truncate_count increment is visible to
1778          * other cpus.
1779          */
1780         smp_mb();
1781         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1782                 if (mapping->truncate_count == 0)
1783                         reset_vma_truncate_counts(mapping);
1784                 mapping->truncate_count++;
1785         }
1786         details.truncate_count = mapping->truncate_count;
1787
1788         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1789                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1790         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1791                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1792         spin_unlock(&mapping->i_mmap_lock);
1793 }
1794 EXPORT_SYMBOL(unmap_mapping_range);
1795
1796 /*
1797  * Handle all mappings that got truncated by a "truncate()"
1798  * system call.
1799  *
1800  * NOTE! We have to be ready to update the memory sharing
1801  * between the file and the memory map for a potential last
1802  * incomplete page.  Ugly, but necessary.
1803  */
1804 int vmtruncate(struct inode * inode, loff_t offset)
1805 {
1806         struct address_space *mapping = inode->i_mapping;
1807         unsigned long limit;
1808
1809         if (inode->i_size < offset)
1810                 goto do_expand;
1811         /*
1812          * truncation of in-use swapfiles is disallowed - it would cause
1813          * subsequent swapout to scribble on the now-freed blocks.
1814          */
1815         if (IS_SWAPFILE(inode))
1816                 goto out_busy;
1817         i_size_write(inode, offset);
1818         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1819         truncate_inode_pages(mapping, offset);
1820         goto out_truncate;
1821
1822 do_expand:
1823         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1824         if (limit != RLIM_INFINITY && offset > limit)
1825                 goto out_sig;
1826         if (offset > inode->i_sb->s_maxbytes)
1827                 goto out_big;
1828         i_size_write(inode, offset);
1829
1830 out_truncate:
1831         if (inode->i_op && inode->i_op->truncate)
1832                 inode->i_op->truncate(inode);
1833         return 0;
1834 out_sig:
1835         send_sig(SIGXFSZ, current, 0);
1836 out_big:
1837         return -EFBIG;
1838 out_busy:
1839         return -ETXTBSY;
1840 }
1841 EXPORT_SYMBOL(vmtruncate);
1842
1843 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1844 {
1845         struct address_space *mapping = inode->i_mapping;
1846
1847         /*
1848          * If the underlying filesystem is not going to provide
1849          * a way to truncate a range of blocks (punch a hole) -
1850          * we should return failure right now.
1851          */
1852         if (!inode->i_op || !inode->i_op->truncate_range)
1853                 return -ENOSYS;
1854
1855         mutex_lock(&inode->i_mutex);
1856         down_write(&inode->i_alloc_sem);
1857         unmap_mapping_range(mapping, offset, (end - offset), 1);
1858         truncate_inode_pages_range(mapping, offset, end);
1859         inode->i_op->truncate_range(inode, offset, end);
1860         up_write(&inode->i_alloc_sem);
1861         mutex_unlock(&inode->i_mutex);
1862
1863         return 0;
1864 }
1865 EXPORT_UNUSED_SYMBOL(vmtruncate_range);  /*  June 2006  */
1866
1867 /*
1868  * Primitive swap readahead code. We simply read an aligned block of
1869  * (1 << page_cluster) entries in the swap area. This method is chosen
1870  * because it doesn't cost us any seek time.  We also make sure to queue
1871  * the 'original' request together with the readahead ones...
1872  *
1873  * This has been extended to use the NUMA policies from the mm triggering
1874  * the readahead.
1875  *
1876  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1877  */
1878 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1879 {
1880 #ifdef CONFIG_NUMA
1881         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1882 #endif
1883         int i, num;
1884         struct page *new_page;
1885         unsigned long offset;
1886
1887         /*
1888          * Get the number of handles we should do readahead io to.
1889          */
1890         num = valid_swaphandles(entry, &offset);
1891         for (i = 0; i < num; offset++, i++) {
1892                 /* Ok, do the async read-ahead now */
1893                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1894                                                            offset), vma, addr);
1895                 if (!new_page)
1896                         break;
1897                 page_cache_release(new_page);
1898 #ifdef CONFIG_NUMA
1899                 /*
1900                  * Find the next applicable VMA for the NUMA policy.
1901                  */
1902                 addr += PAGE_SIZE;
1903                 if (addr == 0)
1904                         vma = NULL;
1905                 if (vma) {
1906                         if (addr >= vma->vm_end) {
1907                                 vma = next_vma;
1908                                 next_vma = vma ? vma->vm_next : NULL;
1909                         }
1910                         if (vma && addr < vma->vm_start)
1911                                 vma = NULL;
1912                 } else {
1913                         if (next_vma && addr >= next_vma->vm_start) {
1914                                 vma = next_vma;
1915                                 next_vma = vma->vm_next;
1916                         }
1917                 }
1918 #endif
1919         }
1920         lru_add_drain();        /* Push any new pages onto the LRU now */
1921 }
1922
1923 /*
1924  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1925  * but allow concurrent faults), and pte mapped but not yet locked.
1926  * We return with mmap_sem still held, but pte unmapped and unlocked.
1927  */
1928 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1929                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1930                 int write_access, pte_t orig_pte)
1931 {
1932         spinlock_t *ptl;
1933         struct page *page;
1934         swp_entry_t entry;
1935         pte_t pte;
1936         int ret = VM_FAULT_MINOR;
1937
1938         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1939                 goto out;
1940
1941         entry = pte_to_swp_entry(orig_pte);
1942         if (is_migration_entry(entry)) {
1943                 migration_entry_wait(mm, pmd, address);
1944                 goto out;
1945         }
1946         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
1947         page = lookup_swap_cache(entry);
1948         if (!page) {
1949                 swapin_readahead(entry, address, vma);
1950                 page = read_swap_cache_async(entry, vma, address);
1951                 if (!page) {
1952                         /*
1953                          * Back out if somebody else faulted in this pte
1954                          * while we released the pte lock.
1955                          */
1956                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1957                         if (likely(pte_same(*page_table, orig_pte)))
1958                                 ret = VM_FAULT_OOM;
1959                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1960                         goto unlock;
1961                 }
1962
1963                 /* Had to read the page from swap area: Major fault */
1964                 ret = VM_FAULT_MAJOR;
1965                 count_vm_event(PGMAJFAULT);
1966                 grab_swap_token();
1967         }
1968
1969         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1970         mark_page_accessed(page);
1971         lock_page(page);
1972
1973         /*
1974          * Back out if somebody else already faulted in this pte.
1975          */
1976         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1977         if (unlikely(!pte_same(*page_table, orig_pte)))
1978                 goto out_nomap;
1979
1980         if (unlikely(!PageUptodate(page))) {
1981                 ret = VM_FAULT_SIGBUS;
1982                 goto out_nomap;
1983         }
1984
1985         /* The page isn't present yet, go ahead with the fault. */
1986
1987         inc_mm_counter(mm, anon_rss);
1988         pte = mk_pte(page, vma->vm_page_prot);
1989         if (write_access && can_share_swap_page(page)) {
1990                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1991                 write_access = 0;
1992         }
1993
1994         flush_icache_page(vma, page);
1995         set_pte_at(mm, address, page_table, pte);
1996         page_add_anon_rmap(page, vma, address);
1997
1998         swap_free(entry);
1999         if (vm_swap_full())
2000                 remove_exclusive_swap_page(page);
2001         unlock_page(page);
2002
2003         if (write_access) {
2004                 if (do_wp_page(mm, vma, address,
2005                                 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
2006                         ret = VM_FAULT_OOM;
2007                 goto out;
2008         }
2009
2010         /* No need to invalidate - it was non-present before */
2011         update_mmu_cache(vma, address, pte);
2012         lazy_mmu_prot_update(pte);
2013 unlock:
2014         pte_unmap_unlock(page_table, ptl);
2015 out:
2016         return ret;
2017 out_nomap:
2018         pte_unmap_unlock(page_table, ptl);
2019         unlock_page(page);
2020         page_cache_release(page);
2021         return ret;
2022 }
2023
2024 /*
2025  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2026  * but allow concurrent faults), and pte mapped but not yet locked.
2027  * We return with mmap_sem still held, but pte unmapped and unlocked.
2028  */
2029 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2030                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2031                 int write_access)
2032 {
2033         struct page *page;
2034         spinlock_t *ptl;
2035         pte_t entry;
2036
2037         if (write_access) {
2038                 /* Allocate our own private page. */
2039                 pte_unmap(page_table);
2040
2041                 if (unlikely(anon_vma_prepare(vma)))
2042                         goto oom;
2043                 page = alloc_zeroed_user_highpage(vma, address);
2044                 if (!page)
2045                         goto oom;
2046
2047                 entry = mk_pte(page, vma->vm_page_prot);
2048                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2049
2050                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2051                 if (!pte_none(*page_table))
2052                         goto release;
2053                 inc_mm_counter(mm, anon_rss);
2054                 lru_cache_add_active(page);
2055                 page_add_new_anon_rmap(page, vma, address);
2056         } else {
2057                 /* Map the ZERO_PAGE - vm_page_prot is readonly */
2058                 page = ZERO_PAGE(address);
2059                 page_cache_get(page);
2060                 entry = mk_pte(page, vma->vm_page_prot);
2061
2062                 ptl = pte_lockptr(mm, pmd);
2063                 spin_lock(ptl);
2064                 if (!pte_none(*page_table))
2065                         goto release;
2066                 inc_mm_counter(mm, file_rss);
2067                 page_add_file_rmap(page);
2068         }
2069
2070         set_pte_at(mm, address, page_table, entry);
2071
2072         /* No need to invalidate - it was non-present before */
2073         update_mmu_cache(vma, address, entry);
2074         lazy_mmu_prot_update(entry);
2075 unlock:
2076         pte_unmap_unlock(page_table, ptl);
2077         return VM_FAULT_MINOR;
2078 release:
2079         page_cache_release(page);
2080         goto unlock;
2081 oom:
2082         return VM_FAULT_OOM;
2083 }
2084
2085 /*
2086  * do_no_page() tries to create a new page mapping. It aggressively
2087  * tries to share with existing pages, but makes a separate copy if
2088  * the "write_access" parameter is true in order to avoid the next
2089  * page fault.
2090  *
2091  * As this is called only for pages that do not currently exist, we
2092  * do not need to flush old virtual caches or the TLB.
2093  *
2094  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2095  * but allow concurrent faults), and pte mapped but not yet locked.
2096  * We return with mmap_sem still held, but pte unmapped and unlocked.
2097  */
2098 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2099                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2100                 int write_access)
2101 {
2102         spinlock_t *ptl;
2103         struct page *new_page;
2104         struct address_space *mapping = NULL;
2105         pte_t entry;
2106         unsigned int sequence = 0;
2107         int ret = VM_FAULT_MINOR;
2108         int anon = 0;
2109         struct page *dirty_page = NULL;
2110
2111         pte_unmap(page_table);
2112         BUG_ON(vma->vm_flags & VM_PFNMAP);
2113
2114         if (vma->vm_file) {
2115                 mapping = vma->vm_file->f_mapping;
2116                 sequence = mapping->truncate_count;
2117                 smp_rmb(); /* serializes i_size against truncate_count */
2118         }
2119 retry:
2120         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2121         /*
2122          * No smp_rmb is needed here as long as there's a full
2123          * spin_lock/unlock sequence inside the ->nopage callback
2124          * (for the pagecache lookup) that acts as an implicit
2125          * smp_mb() and prevents the i_size read to happen
2126          * after the next truncate_count read.
2127          */
2128
2129         /* no page was available -- either SIGBUS or OOM */
2130         if (new_page == NOPAGE_SIGBUS)
2131                 return VM_FAULT_SIGBUS;
2132         if (new_page == NOPAGE_OOM)
2133                 return VM_FAULT_OOM;
2134
2135         /*
2136          * Should we do an early C-O-W break?
2137          */
2138         if (write_access) {
2139                 if (!(vma->vm_flags & VM_SHARED)) {
2140                         struct page *page;
2141
2142                         if (unlikely(anon_vma_prepare(vma)))
2143                                 goto oom;
2144                         page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2145                         if (!page)
2146                                 goto oom;
2147                         copy_user_highpage(page, new_page, address);
2148                         page_cache_release(new_page);
2149                         new_page = page;
2150                         anon = 1;
2151
2152                 } else {
2153                         /* if the page will be shareable, see if the backing
2154                          * address space wants to know that the page is about
2155                          * to become writable */
2156                         if (vma->vm_ops->page_mkwrite &&
2157                             vma->vm_ops->page_mkwrite(vma, new_page) < 0
2158                             ) {
2159                                 page_cache_release(new_page);
2160                                 return VM_FAULT_SIGBUS;
2161                         }
2162                 }
2163         }
2164
2165         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2166         /*
2167          * For a file-backed vma, someone could have truncated or otherwise
2168          * invalidated this page.  If unmap_mapping_range got called,
2169          * retry getting the page.
2170          */
2171         if (mapping && unlikely(sequence != mapping->truncate_count)) {
2172                 pte_unmap_unlock(page_table, ptl);
2173                 page_cache_release(new_page);
2174                 cond_resched();
2175                 sequence = mapping->truncate_count;
2176                 smp_rmb();
2177                 goto retry;
2178         }
2179
2180         /*
2181          * This silly early PAGE_DIRTY setting removes a race
2182          * due to the bad i386 page protection. But it's valid
2183          * for other architectures too.
2184          *
2185          * Note that if write_access is true, we either now have
2186          * an exclusive copy of the page, or this is a shared mapping,
2187          * so we can make it writable and dirty to avoid having to
2188          * handle that later.
2189          */
2190         /* Only go through if we didn't race with anybody else... */
2191         if (pte_none(*page_table)) {
2192                 flush_icache_page(vma, new_page);
2193                 entry = mk_pte(new_page, vma->vm_page_prot);
2194                 if (write_access)
2195                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2196                 set_pte_at(mm, address, page_table, entry);
2197                 if (anon) {
2198                         inc_mm_counter(mm, anon_rss);
2199                         lru_cache_add_active(new_page);
2200                         page_add_new_anon_rmap(new_page, vma, address);
2201                 } else {
2202                         inc_mm_counter(mm, file_rss);
2203                         page_add_file_rmap(new_page);
2204                         if (write_access) {
2205                                 dirty_page = new_page;
2206                                 get_page(dirty_page);
2207                         }
2208                 }
2209         } else {
2210                 /* One of our sibling threads was faster, back out. */
2211                 page_cache_release(new_page);
2212                 goto unlock;
2213         }
2214
2215         /* no need to invalidate: a not-present page shouldn't be cached */
2216         update_mmu_cache(vma, address, entry);
2217         lazy_mmu_prot_update(entry);
2218 unlock:
2219         pte_unmap_unlock(page_table, ptl);
2220         if (dirty_page) {
2221                 set_page_dirty(dirty_page);
2222                 put_page(dirty_page);
2223         }
2224         return ret;
2225 oom:
2226         page_cache_release(new_page);
2227         return VM_FAULT_OOM;
2228 }
2229
2230 /*
2231  * Fault of a previously existing named mapping. Repopulate the pte
2232  * from the encoded file_pte if possible. This enables swappable
2233  * nonlinear vmas.
2234  *
2235  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2236  * but allow concurrent faults), and pte mapped but not yet locked.
2237  * We return with mmap_sem still held, but pte unmapped and unlocked.
2238  */
2239 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2240                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2241                 int write_access, pte_t orig_pte)
2242 {
2243         pgoff_t pgoff;
2244         int err;
2245
2246         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2247                 return VM_FAULT_MINOR;
2248
2249         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2250                 /*
2251                  * Page table corrupted: show pte and kill process.
2252                  */
2253                 print_bad_pte(vma, orig_pte, address);
2254                 return VM_FAULT_OOM;
2255         }
2256         /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2257
2258         pgoff = pte_to_pgoff(orig_pte);
2259         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2260                                         vma->vm_page_prot, pgoff, 0);
2261         if (err == -ENOMEM)
2262                 return VM_FAULT_OOM;
2263         if (err)
2264                 return VM_FAULT_SIGBUS;
2265         return VM_FAULT_MAJOR;
2266 }
2267
2268 /*
2269  * These routines also need to handle stuff like marking pages dirty
2270  * and/or accessed for architectures that don't do it in hardware (most
2271  * RISC architectures).  The early dirtying is also good on the i386.
2272  *
2273  * There is also a hook called "update_mmu_cache()" that architectures
2274  * with external mmu caches can use to update those (ie the Sparc or
2275  * PowerPC hashed page tables that act as extended TLBs).
2276  *
2277  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2278  * but allow concurrent faults), and pte mapped but not yet locked.
2279  * We return with mmap_sem still held, but pte unmapped and unlocked.
2280  */
2281 static inline int handle_pte_fault(struct mm_struct *mm,
2282                 struct vm_area_struct *vma, unsigned long address,
2283                 pte_t *pte, pmd_t *pmd, int write_access)
2284 {
2285         pte_t entry;
2286         pte_t old_entry;
2287         spinlock_t *ptl;
2288
2289         old_entry = entry = *pte;
2290         if (!pte_present(entry)) {
2291                 if (pte_none(entry)) {
2292                         if (!vma->vm_ops || !vma->vm_ops->nopage)
2293                                 return do_anonymous_page(mm, vma, address,
2294                                         pte, pmd, write_access);
2295                         return do_no_page(mm, vma, address,
2296                                         pte, pmd, write_access);
2297                 }
2298                 if (pte_file(entry))
2299                         return do_file_page(mm, vma, address,
2300                                         pte, pmd, write_access, entry);
2301                 return do_swap_page(mm, vma, address,
2302                                         pte, pmd, write_access, entry);
2303         }
2304
2305         ptl = pte_lockptr(mm, pmd);
2306         spin_lock(ptl);
2307         if (unlikely(!pte_same(*pte, entry)))
2308                 goto unlock;
2309         if (write_access) {
2310                 if (!pte_write(entry))
2311                         return do_wp_page(mm, vma, address,
2312                                         pte, pmd, ptl, entry);
2313                 entry = pte_mkdirty(entry);
2314         }
2315         entry = pte_mkyoung(entry);
2316         if (!pte_same(old_entry, entry)) {
2317                 ptep_set_access_flags(vma, address, pte, entry, write_access);
2318                 update_mmu_cache(vma, address, entry);
2319                 lazy_mmu_prot_update(entry);
2320         } else {
2321                 /*
2322                  * This is needed only for protection faults but the arch code
2323                  * is not yet telling us if this is a protection fault or not.
2324                  * This still avoids useless tlb flushes for .text page faults
2325                  * with threads.
2326                  */
2327                 if (write_access)
2328                         flush_tlb_page(vma, address);
2329         }
2330 unlock:
2331         pte_unmap_unlock(pte, ptl);
2332         return VM_FAULT_MINOR;
2333 }
2334
2335 /*
2336  * By the time we get here, we already hold the mm semaphore
2337  */
2338 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2339                 unsigned long address, int write_access)
2340 {
2341         pgd_t *pgd;
2342         pud_t *pud;
2343         pmd_t *pmd;
2344         pte_t *pte;
2345
2346         __set_current_state(TASK_RUNNING);
2347
2348         count_vm_event(PGFAULT);
2349
2350         if (unlikely(is_vm_hugetlb_page(vma)))
2351                 return hugetlb_fault(mm, vma, address, write_access);
2352
2353         pgd = pgd_offset(mm, address);
2354         pud = pud_alloc(mm, pgd, address);
2355         if (!pud)
2356                 return VM_FAULT_OOM;
2357         pmd = pmd_alloc(mm, pud, address);
2358         if (!pmd)
2359                 return VM_FAULT_OOM;
2360         pte = pte_alloc_map(mm, pmd, address);
2361         if (!pte)
2362                 return VM_FAULT_OOM;
2363
2364         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2365 }
2366
2367 EXPORT_SYMBOL_GPL(__handle_mm_fault);
2368
2369 #ifndef __PAGETABLE_PUD_FOLDED
2370 /*
2371  * Allocate page upper directory.
2372  * We've already handled the fast-path in-line.
2373  */
2374 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2375 {
2376         pud_t *new = pud_alloc_one(mm, address);
2377         if (!new)
2378                 return -ENOMEM;
2379
2380         spin_lock(&mm->page_table_lock);
2381         if (pgd_present(*pgd))          /* Another has populated it */
2382                 pud_free(new);
2383         else
2384                 pgd_populate(mm, pgd, new);
2385         spin_unlock(&mm->page_table_lock);
2386         return 0;
2387 }
2388 #else
2389 /* Workaround for gcc 2.96 */
2390 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2391 {
2392         return 0;
2393 }
2394 #endif /* __PAGETABLE_PUD_FOLDED */
2395
2396 #ifndef __PAGETABLE_PMD_FOLDED
2397 /*
2398  * Allocate page middle directory.
2399  * We've already handled the fast-path in-line.
2400  */
2401 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2402 {
2403         pmd_t *new = pmd_alloc_one(mm, address);
2404         if (!new)
2405                 return -ENOMEM;
2406
2407         spin_lock(&mm->page_table_lock);
2408 #ifndef __ARCH_HAS_4LEVEL_HACK
2409         if (pud_present(*pud))          /* Another has populated it */
2410                 pmd_free(new);
2411         else
2412                 pud_populate(mm, pud, new);
2413 #else
2414         if (pgd_present(*pud))          /* Another has populated it */
2415                 pmd_free(new);
2416         else
2417                 pgd_populate(mm, pud, new);
2418 #endif /* __ARCH_HAS_4LEVEL_HACK */
2419         spin_unlock(&mm->page_table_lock);
2420         return 0;
2421 }
2422 #else
2423 /* Workaround for gcc 2.96 */
2424 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2425 {
2426         return 0;
2427 }
2428 #endif /* __PAGETABLE_PMD_FOLDED */
2429
2430 int make_pages_present(unsigned long addr, unsigned long end)
2431 {
2432         int ret, len, write;
2433         struct vm_area_struct * vma;
2434
2435         vma = find_vma(current->mm, addr);
2436         if (!vma)
2437                 return -1;
2438         write = (vma->vm_flags & VM_WRITE) != 0;
2439         BUG_ON(addr >= end);
2440         BUG_ON(end > vma->vm_end);
2441         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2442         ret = get_user_pages(current, current->mm, addr,
2443                         len, write, 0, NULL, NULL);
2444         if (ret < 0)
2445                 return ret;
2446         return ret == len ? 0 : -1;
2447 }
2448
2449 /*
2450  * Map a vmalloc()-space virtual address to the physical page.
2451  */
2452 struct page * vmalloc_to_page(void * vmalloc_addr)
2453 {
2454         unsigned long addr = (unsigned long) vmalloc_addr;
2455         struct page *page = NULL;
2456         pgd_t *pgd = pgd_offset_k(addr);
2457         pud_t *pud;
2458         pmd_t *pmd;
2459         pte_t *ptep, pte;
2460
2461         if (!pgd_none(*pgd)) {
2462                 pud = pud_offset(pgd, addr);
2463                 if (!pud_none(*pud)) {
2464                         pmd = pmd_offset(pud, addr);
2465                         if (!pmd_none(*pmd)) {
2466                                 ptep = pte_offset_map(pmd, addr);
2467                                 pte = *ptep;
2468                                 if (pte_present(pte))
2469                                         page = pte_page(pte);
2470                                 pte_unmap(ptep);
2471                         }
2472                 }
2473         }
2474         return page;
2475 }
2476
2477 EXPORT_SYMBOL(vmalloc_to_page);
2478
2479 /*
2480  * Map a vmalloc()-space virtual address to the physical page frame number.
2481  */
2482 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2483 {
2484         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2485 }
2486
2487 EXPORT_SYMBOL(vmalloc_to_pfn);
2488
2489 #if !defined(__HAVE_ARCH_GATE_AREA)
2490
2491 #if defined(AT_SYSINFO_EHDR)
2492 static struct vm_area_struct gate_vma;
2493
2494 static int __init gate_vma_init(void)
2495 {
2496         gate_vma.vm_mm = NULL;
2497         gate_vma.vm_start = FIXADDR_USER_START;
2498         gate_vma.vm_end = FIXADDR_USER_END;
2499         gate_vma.vm_page_prot = PAGE_READONLY;
2500         gate_vma.vm_flags = 0;
2501         return 0;
2502 }
2503 __initcall(gate_vma_init);
2504 #endif
2505
2506 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2507 {
2508 #ifdef AT_SYSINFO_EHDR
2509         return &gate_vma;
2510 #else
2511         return NULL;
2512 #endif
2513 }
2514
2515 int in_gate_area_no_task(unsigned long addr)
2516 {
2517 #ifdef AT_SYSINFO_EHDR
2518         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2519                 return 1;
2520 #endif
2521         return 0;
2522 }
2523
2524 #endif  /* __HAVE_ARCH_GATE_AREA */