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/init.h>
  51
  52 #include <asm/pgalloc.h>
  53 #include <asm/uaccess.h>
  54 #include <asm/tlb.h>
  55 #include <asm/tlbflush.h>
  56 #include <asm/pgtable.h>
  57
  58 #include <linux/swapops.h>
  59 #include <linux/elf.h>
  60
  61 #ifndef CONFIG_NEED_MULTIPLE_NODES
  62 /* use the per-pgdat data instead for discontigmem - mbligh */
  63 unsigned long max_mapnr;
  64 struct page *mem_map;
  65
  66 EXPORT_SYMBOL(max_mapnr);
  67 EXPORT_SYMBOL(mem_map);
  68 #endif
  69
  70 unsigned long num_physpages;
  71 /*
  72  * A number of key systems in x86 including ioremap() rely on the assumption
  73  * that high_memory defines the upper bound on direct map memory, then end
  74  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  75  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  76  * and ZONE_HIGHMEM.
  77  */
  78 void * high_memory;
  79 unsigned long vmalloc_earlyreserve;
  80
  81 EXPORT_SYMBOL(num_physpages);
  82 EXPORT_SYMBOL(high_memory);
  83 EXPORT_SYMBOL(vmalloc_earlyreserve);
  84
  85 /*
  86  * If a p?d_bad entry is found while walking page tables, report
  87  * the error, before resetting entry to p?d_none.  Usually (but
  88  * very seldom) called out from the p?d_none_or_clear_bad macros.
  89  */
  90
  91 void pgd_clear_bad(pgd_t *pgd)
  92 {
  93         pgd_ERROR(*pgd);
  94         pgd_clear(pgd);
  95 }
  96
  97 void pud_clear_bad(pud_t *pud)
  98 {
  99         pud_ERROR(*pud);
 100         pud_clear(pud);
 101 }
 102
 103 void pmd_clear_bad(pmd_t *pmd)
 104 {
 105         pmd_ERROR(*pmd);
 106         pmd_clear(pmd);
 107 }
 108
 109 /*
 110  * Note: this doesn't free the actual pages themselves. That
 111  * has been handled earlier when unmapping all the memory regions.
 112  */
 113 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
 114 {
 115         struct page *page = pmd_page(*pmd);
 116         pmd_clear(pmd);
 117         pte_lock_deinit(page);
 118         pte_free_tlb(tlb, page);
 119         dec_page_state(nr_page_table_pages);
 120         tlb->mm->nr_ptes--;
 121 }
 122
 123 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 124                                 unsigned long addr, unsigned long end,
 125                                 unsigned long floor, unsigned long ceiling)
 126 {
 127         pmd_t *pmd;
 128         unsigned long next;
 129         unsigned long start;
 130
 131         start = addr;
 132         pmd = pmd_offset(pud, addr);
 133         do {
 134                 next = pmd_addr_end(addr, end);
 135                 if (pmd_none_or_clear_bad(pmd))
 136                         continue;
 137                 free_pte_range(tlb, pmd);
 138         } while (pmd++, addr = next, addr != end);
 139
 140         start &= PUD_MASK;
 141         if (start < floor)
 142                 return;
 143         if (ceiling) {
 144                 ceiling &= PUD_MASK;
 145                 if (!ceiling)
 146                         return;
 147         }
 148         if (end - 1 > ceiling - 1)
 149                 return;
 150
 151         pmd = pmd_offset(pud, start);
 152         pud_clear(pud);
 153         pmd_free_tlb(tlb, pmd);
 154 }
 155
 156 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 157                                 unsigned long addr, unsigned long end,
 158                                 unsigned long floor, unsigned long ceiling)
 159 {
 160         pud_t *pud;
 161         unsigned long next;
 162         unsigned long start;
 163
 164         start = addr;
 165         pud = pud_offset(pgd, addr);
 166         do {
 167                 next = pud_addr_end(addr, end);
 168                 if (pud_none_or_clear_bad(pud))
 169                         continue;
 170                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 171         } while (pud++, addr = next, addr != end);
 172
 173         start &= PGDIR_MASK;
 174         if (start < floor)
 175                 return;
 176         if (ceiling) {
 177                 ceiling &= PGDIR_MASK;
 178                 if (!ceiling)
 179                         return;
 180         }
 181         if (end - 1 > ceiling - 1)
 182                 return;
 183
 184         pud = pud_offset(pgd, start);
 185         pgd_clear(pgd);
 186         pud_free_tlb(tlb, pud);
 187 }
 188
 189 /*
 190  * This function frees user-level page tables of a process.
 191  *
 192  * Must be called with pagetable lock held.
 193  */
 194 void free_pgd_range(struct mmu_gather **tlb,
 195                         unsigned long addr, unsigned long end,
 196                         unsigned long floor, unsigned long ceiling)
 197 {
 198         pgd_t *pgd;
 199         unsigned long next;
 200         unsigned long start;
 201
 202         /*
 203          * The next few lines have given us lots of grief...
 204          *
 205          * Why are we testing PMD* at this top level?  Because often
 206          * there will be no work to do at all, and we'd prefer not to
 207          * go all the way down to the bottom just to discover that.
 208          *
 209          * Why all these "- 1"s?  Because 0 represents both the bottom
 210          * of the address space and the top of it (using -1 for the
 211          * top wouldn't help much: the masks would do the wrong thing).
 212          * The rule is that addr 0 and floor 0 refer to the bottom of
 213          * the address space, but end 0 and ceiling 0 refer to the top
 214          * Comparisons need to use "end - 1" and "ceiling - 1" (though
 215          * that end 0 case should be mythical).
 216          *
 217          * Wherever addr is brought up or ceiling brought down, we must
 218          * be careful to reject "the opposite 0" before it confuses the
 219          * subsequent tests.  But what about where end is brought down
 220          * by PMD_SIZE below? no, end can't go down to 0 there.
 221          *
 222          * Whereas we round start (addr) and ceiling down, by different
 223          * masks at different levels, in order to test whether a table
 224          * now has no other vmas using it, so can be freed, we don't
 225          * bother to round floor or end up - the tests don't need that.
 226          */
 227
 228         addr &= PMD_MASK;
 229         if (addr < floor) {
 230                 addr += PMD_SIZE;
 231                 if (!addr)
 232                         return;
 233         }
 234         if (ceiling) {
 235                 ceiling &= PMD_MASK;
 236                 if (!ceiling)
 237                         return;
 238         }
 239         if (end - 1 > ceiling - 1)
 240                 end -= PMD_SIZE;
 241         if (addr > end - 1)
 242                 return;
 243
 244         start = addr;
 245         pgd = pgd_offset((*tlb)->mm, addr);
 246         do {
 247                 next = pgd_addr_end(addr, end);
 248                 if (pgd_none_or_clear_bad(pgd))
 249                         continue;
 250                 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
 251         } while (pgd++, addr = next, addr != end);
 252
 253         if (!(*tlb)->fullmm)
 254                 flush_tlb_pgtables((*tlb)->mm, start, end);
 255 }
 256
 257 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
 258                 unsigned long floor, unsigned long ceiling)
 259 {
 260         while (vma) {
 261                 struct vm_area_struct *next = vma->vm_next;
 262                 unsigned long addr = vma->vm_start;
 263
 264                 /*
 265                  * Hide vma from rmap and vmtruncate before freeing pgtables
 266                  */
 267                 anon_vma_unlink(vma);
 268                 unlink_file_vma(vma);
 269
 270                 if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) {
 271                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 272                                 floor, next? next->vm_start: ceiling);
 273                 } else {
 274                         /*
 275                          * Optimization: gather nearby vmas into one call down
 276                          */
 277                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 278                           && !is_hugepage_only_range(vma->vm_mm, next->vm_start,
 279                                                         HPAGE_SIZE)) {
 280                                 vma = next;
 281                                 next = vma->vm_next;
 282                                 anon_vma_unlink(vma);
 283                                 unlink_file_vma(vma);
 284                         }
 285                         free_pgd_range(tlb, addr, vma->vm_end,
 286                                 floor, next? next->vm_start: ceiling);
 287                 }
 288                 vma = next;
 289         }
 290 }
 291
 292 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 293 {
 294         struct page *new = pte_alloc_one(mm, address);
 295         if (!new)
 296                 return -ENOMEM;
 297
 298         pte_lock_init(new);
 299         spin_lock(&mm->page_table_lock);
 300         if (pmd_present(*pmd)) {        /* Another has populated it */
 301                 pte_lock_deinit(new);
 302                 pte_free(new);
 303         } else {
 304                 mm->nr_ptes++;
 305                 inc_page_state(nr_page_table_pages);
 306                 pmd_populate(mm, pmd, new);
 307         }
 308         spin_unlock(&mm->page_table_lock);
 309         return 0;
 310 }
 311
 312 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 313 {
 314         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 315         if (!new)
 316                 return -ENOMEM;
 317
 318         spin_lock(&init_mm.page_table_lock);
 319         if (pmd_present(*pmd))          /* Another has populated it */
 320                 pte_free_kernel(new);
 321         else
 322                 pmd_populate_kernel(&init_mm, pmd, new);
 323         spin_unlock(&init_mm.page_table_lock);
 324         return 0;
 325 }
 326
 327 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
 328 {
 329         if (file_rss)
 330                 add_mm_counter(mm, file_rss, file_rss);
 331         if (anon_rss)
 332                 add_mm_counter(mm, anon_rss, anon_rss);
 333 }
 334
 335 /*
 336  * This function is called to print an error when a bad pte
 337  * is found. For example, we might have a PFN-mapped pte in
 338  * a region that doesn't allow it.
 339  *
 340  * The calling function must still handle the error.
 341  */
 342 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
 343 {
 344         printk(KERN_ERR "Bad pte = %08llx, process = %s, "
 345                         "vm_flags = %lx, vaddr = %lx\n",
 346                 (long long)pte_val(pte),
 347                 (vma->vm_mm == current->mm ? current->comm : "???"),
 348                 vma->vm_flags, vaddr);
 349         dump_stack();
 350 }
 351
 352 static inline int is_cow_mapping(unsigned int flags)
 353 {
 354         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 355 }
 356
 357 /*
 358  * This function gets the "struct page" associated with a pte.
 359  *
 360  * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
 361  * will have each page table entry just pointing to a raw page frame
 362  * number, and as far as the VM layer is concerned, those do not have
 363  * pages associated with them - even if the PFN might point to memory
 364  * that otherwise is perfectly fine and has a "struct page".
 365  *
 366  * The way we recognize those mappings is through the rules set up
 367  * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
 368  * and the vm_pgoff will point to the first PFN mapped: thus every
 369  * page that is a raw mapping will always honor the rule
 370  *
 371  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 372  *
 373  * and if that isn't true, the page has been COW'ed (in which case it
 374  * _does_ have a "struct page" associated with it even if it is in a
 375  * VM_PFNMAP range).
 376  */
 377 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 378 {
 379         unsigned long pfn = pte_pfn(pte);
 380
 381         if (vma->vm_flags & VM_PFNMAP) {
 382                 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
 383                 if (pfn == vma->vm_pgoff + off)
 384                         return NULL;
 385                 if (!is_cow_mapping(vma->vm_flags))
 386                         return NULL;
 387         }
 388
 389         /*
 390          * Add some anal sanity checks for now. Eventually,
 391          * we should just do "return pfn_to_page(pfn)", but
 392          * in the meantime we check that we get a valid pfn,
 393          * and that the resulting page looks ok.
 394          *
 395          * Remove this test eventually!
 396          */
 397         if (unlikely(!pfn_valid(pfn))) {
 398                 print_bad_pte(vma, pte, addr);
 399                 return NULL;
 400         }
 401
 402         /*
 403          * NOTE! We still have PageReserved() pages in the page
 404          * tables.
 405          *
 406          * The PAGE_ZERO() pages and various VDSO mappings can
 407          * cause them to exist.
 408          */
 409         return pfn_to_page(pfn);
 410 }
 411
 412 /*
 413  * copy one vm_area from one task to the other. Assumes the page tables
 414  * already present in the new task to be cleared in the whole range
 415  * covered by this vma.
 416  */
 417
 418 static inline void
 419 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 420                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 421                 unsigned long addr, int *rss)
 422 {
 423         unsigned long vm_flags = vma->vm_flags;
 424         pte_t pte = *src_pte;
 425         struct page *page;
 426
 427         /* pte contains position in swap or file, so copy. */
 428         if (unlikely(!pte_present(pte))) {
 429                 if (!pte_file(pte)) {
 430                         swap_duplicate(pte_to_swp_entry(pte));
 431                         /* make sure dst_mm is on swapoff's mmlist. */
 432                         if (unlikely(list_empty(&dst_mm->mmlist))) {
 433                                 spin_lock(&mmlist_lock);
 434                                 if (list_empty(&dst_mm->mmlist))
 435                                         list_add(&dst_mm->mmlist,
 436                                                  &src_mm->mmlist);
 437                                 spin_unlock(&mmlist_lock);
 438                         }
 439                 }
 440                 goto out_set_pte;
 441         }
 442
 443         /*
 444          * If it's a COW mapping, write protect it both
 445          * in the parent and the child
 446          */
 447         if (is_cow_mapping(vm_flags)) {
 448                 ptep_set_wrprotect(src_mm, addr, src_pte);
 449                 pte = *src_pte;
 450         }
 451
 452         /*
 453          * If it's a shared mapping, mark it clean in
 454          * the child
 455          */
 456         if (vm_flags & VM_SHARED)
 457                 pte = pte_mkclean(pte);
 458         pte = pte_mkold(pte);
 459
 460         page = vm_normal_page(vma, addr, pte);
 461         if (page) {
 462                 get_page(page);
 463                 page_dup_rmap(page);
 464                 rss[!!PageAnon(page)]++;
 465         }
 466
 467 out_set_pte:
 468         set_pte_at(dst_mm, addr, dst_pte, pte);
 469 }
 470
 471 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 472                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 473                 unsigned long addr, unsigned long end)
 474 {
 475         pte_t *src_pte, *dst_pte;
 476         spinlock_t *src_ptl, *dst_ptl;
 477         int progress = 0;
 478         int rss[2];
 479
 480 again:
 481         rss[1] = rss[0] = 0;
 482         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 483         if (!dst_pte)
 484                 return -ENOMEM;
 485         src_pte = pte_offset_map_nested(src_pmd, addr);
 486         src_ptl = pte_lockptr(src_mm, src_pmd);
 487         spin_lock(src_ptl);
 488
 489         do {
 490                 /*
 491                  * We are holding two locks at this point - either of them
 492                  * could generate latencies in another task on another CPU.
 493                  */
 494                 if (progress >= 32) {
 495                         progress = 0;
 496                         if (need_resched() ||
 497                             need_lockbreak(src_ptl) ||
 498                             need_lockbreak(dst_ptl))
 499                                 break;
 500                 }
 501                 if (pte_none(*src_pte)) {
 502                         progress++;
 503                         continue;
 504                 }
 505                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
 506                 progress += 8;
 507         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 508
 509         spin_unlock(src_ptl);
 510         pte_unmap_nested(src_pte - 1);
 511         add_mm_rss(dst_mm, rss[0], rss[1]);
 512         pte_unmap_unlock(dst_pte - 1, dst_ptl);
 513         cond_resched();
 514         if (addr != end)
 515                 goto again;
 516         return 0;
 517 }
 518
 519 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 520                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 521                 unsigned long addr, unsigned long end)
 522 {
 523         pmd_t *src_pmd, *dst_pmd;
 524         unsigned long next;
 525
 526         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 527         if (!dst_pmd)
 528                 return -ENOMEM;
 529         src_pmd = pmd_offset(src_pud, addr);
 530         do {
 531                 next = pmd_addr_end(addr, end);
 532                 if (pmd_none_or_clear_bad(src_pmd))
 533                         continue;
 534                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
 535                                                 vma, addr, next))
 536                         return -ENOMEM;
 537         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 538         return 0;
 539 }
 540
 541 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 542                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
 543                 unsigned long addr, unsigned long end)
 544 {
 545         pud_t *src_pud, *dst_pud;
 546         unsigned long next;
 547
 548         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
 549         if (!dst_pud)
 550                 return -ENOMEM;
 551         src_pud = pud_offset(src_pgd, addr);
 552         do {
 553                 next = pud_addr_end(addr, end);
 554                 if (pud_none_or_clear_bad(src_pud))
 555                         continue;
 556                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
 557                                                 vma, addr, next))
 558                         return -ENOMEM;
 559         } while (dst_pud++, src_pud++, addr = next, addr != end);
 560         return 0;
 561 }
 562
 563 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 564                 struct vm_area_struct *vma)
 565 {
 566         pgd_t *src_pgd, *dst_pgd;
 567         unsigned long next;
 568         unsigned long addr = vma->vm_start;
 569         unsigned long end = vma->vm_end;
 570
 571         /*
 572          * Don't copy ptes where a page fault will fill them correctly.
 573          * Fork becomes much lighter when there are big shared or private
 574          * readonly mappings. The tradeoff is that copy_page_range is more
 575          * efficient than faulting.
 576          */
 577         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
 578                 if (!vma->anon_vma)
 579                         return 0;
 580         }
 581
 582         if (is_vm_hugetlb_page(vma))
 583                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 584
 585         dst_pgd = pgd_offset(dst_mm, addr);
 586         src_pgd = pgd_offset(src_mm, addr);
 587         do {
 588                 next = pgd_addr_end(addr, end);
 589                 if (pgd_none_or_clear_bad(src_pgd))
 590                         continue;
 591                 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
 592                                                 vma, addr, next))
 593                         return -ENOMEM;
 594         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
 595         return 0;
 596 }
 597
 598 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 599                                 struct vm_area_struct *vma, pmd_t *pmd,
 600                                 unsigned long addr, unsigned long end,
 601                                 long *zap_work, struct zap_details *details)
 602 {
 603         struct mm_struct *mm = tlb->mm;
 604         pte_t *pte;
 605         spinlock_t *ptl;
 606         int file_rss = 0;
 607         int anon_rss = 0;
 608
 609         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 610         do {
 611                 pte_t ptent = *pte;
 612                 if (pte_none(ptent)) {
 613                         (*zap_work)--;
 614                         continue;
 615                 }
 616                 if (pte_present(ptent)) {
 617                         struct page *page;
 618
 619                         (*zap_work) -= PAGE_SIZE;
 620
 621                         page = vm_normal_page(vma, addr, ptent);
 622                         if (unlikely(details) && page) {
 623                                 /*
 624                                  * unmap_shared_mapping_pages() wants to
 625                                  * invalidate cache without truncating:
 626                                  * unmap shared but keep private pages.
 627                                  */
 628                                 if (details->check_mapping &&
 629                                     details->check_mapping != page->mapping)
 630                                         continue;
 631                                 /*
 632                                  * Each page->index must be checked when
 633                                  * invalidating or truncating nonlinear.
 634                                  */
 635                                 if (details->nonlinear_vma &&
 636                                     (page->index < details->first_index ||
 637                                      page->index > details->last_index))
 638                                         continue;
 639                         }
 640                         ptent = ptep_get_and_clear_full(mm, addr, pte,
 641                                                         tlb->fullmm);
 642                         tlb_remove_tlb_entry(tlb, pte, addr);
 643                         if (unlikely(!page))
 644                                 continue;
 645                         if (unlikely(details) && details->nonlinear_vma
 646                             && linear_page_index(details->nonlinear_vma,
 647                                                 addr) != page->index)
 648                                 set_pte_at(mm, addr, pte,
 649                                            pgoff_to_pte(page->index));
 650                         if (PageAnon(page))
 651                                 anon_rss--;
 652                         else {
 653                                 if (pte_dirty(ptent))
 654                                         set_page_dirty(page);
 655                                 if (pte_young(ptent))
 656                                         mark_page_accessed(page);
 657                                 file_rss--;
 658                         }
 659                         page_remove_rmap(page);
 660                         tlb_remove_page(tlb, page);
 661                         continue;
 662                 }
 663                 /*
 664                  * If details->check_mapping, we leave swap entries;
 665                  * if details->nonlinear_vma, we leave file entries.
 666                  */
 667                 if (unlikely(details))
 668                         continue;
 669                 if (!pte_file(ptent))
 670                         free_swap_and_cache(pte_to_swp_entry(ptent));
 671                 pte_clear_full(mm, addr, pte, tlb->fullmm);
 672         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
 673
 674         add_mm_rss(mm, file_rss, anon_rss);
 675         pte_unmap_unlock(pte - 1, ptl);
 676
 677         return addr;
 678 }
 679
 680 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 681                                 struct vm_area_struct *vma, pud_t *pud,
 682                                 unsigned long addr, unsigned long end,
 683                                 long *zap_work, struct zap_details *details)
 684 {
 685         pmd_t *pmd;
 686         unsigned long next;
 687
 688         pmd = pmd_offset(pud, addr);
 689         do {
 690                 next = pmd_addr_end(addr, end);
 691                 if (pmd_none_or_clear_bad(pmd)) {
 692                         (*zap_work)--;
 693                         continue;
 694                 }
 695                 next = zap_pte_range(tlb, vma, pmd, addr, next,
 696                                                 zap_work, details);
 697         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
 698
 699         return addr;
 700 }
 701
 702 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 703                                 struct vm_area_struct *vma, pgd_t *pgd,
 704                                 unsigned long addr, unsigned long end,
 705                                 long *zap_work, struct zap_details *details)
 706 {
 707         pud_t *pud;
 708         unsigned long next;
 709
 710         pud = pud_offset(pgd, addr);
 711         do {
 712                 next = pud_addr_end(addr, end);
 713                 if (pud_none_or_clear_bad(pud)) {
 714                         (*zap_work)--;
 715                         continue;
 716                 }
 717                 next = zap_pmd_range(tlb, vma, pud, addr, next,
 718                                                 zap_work, details);
 719         } while (pud++, addr = next, (addr != end && *zap_work > 0));
 720
 721         return addr;
 722 }
 723
 724 static unsigned long unmap_page_range(struct mmu_gather *tlb,
 725                                 struct vm_area_struct *vma,
 726                                 unsigned long addr, unsigned long end,
 727                                 long *zap_work, struct zap_details *details)
 728 {
 729         pgd_t *pgd;
 730         unsigned long next;
 731
 732         if (details && !details->check_mapping && !details->nonlinear_vma)
 733                 details = NULL;
 734
 735         BUG_ON(addr >= end);
 736         tlb_start_vma(tlb, vma);
 737         pgd = pgd_offset(vma->vm_mm, addr);
 738         do {
 739                 next = pgd_addr_end(addr, end);
 740                 if (pgd_none_or_clear_bad(pgd)) {
 741                         (*zap_work)--;
 742                         continue;
 743                 }
 744                 next = zap_pud_range(tlb, vma, pgd, addr, next,
 745                                                 zap_work, details);
 746         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
 747         tlb_end_vma(tlb, vma);
 748
 749         return addr;
 750 }
 751
 752 #ifdef CONFIG_PREEMPT
 753 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
 754 #else
 755 /* No preempt: go for improved straight-line efficiency */
 756 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
 757 #endif
 758
 759 /**
 760  * unmap_vmas - unmap a range of memory covered by a list of vma's
 761  * @tlbp: address of the caller's struct mmu_gather
 762  * @vma: the starting vma
 763  * @start_addr: virtual address at which to start unmapping
 764  * @end_addr: virtual address at which to end unmapping
 765  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 766  * @details: details of nonlinear truncation or shared cache invalidation
 767  *
 768  * Returns the end address of the unmapping (restart addr if interrupted).
 769  *
 770  * Unmap all pages in the vma list.
 771  *
 772  * We aim to not hold locks for too long (for scheduling latency reasons).
 773  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
 774  * return the ending mmu_gather to the caller.
 775  *
 776  * Only addresses between `start' and `end' will be unmapped.
 777  *
 778  * The VMA list must be sorted in ascending virtual address order.
 779  *
 780  * unmap_vmas() assumes that the caller will flush the whole unmapped address
 781  * range after unmap_vmas() returns.  So the only responsibility here is to
 782  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 783  * drops the lock and schedules.
 784  */
 785 unsigned long unmap_vmas(struct mmu_gather **tlbp,
 786                 struct vm_area_struct *vma, unsigned long start_addr,
 787                 unsigned long end_addr, unsigned long *nr_accounted,
 788                 struct zap_details *details)
 789 {
 790         long zap_work = ZAP_BLOCK_SIZE;
 791         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
 792         int tlb_start_valid = 0;
 793         unsigned long start = start_addr;
 794         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
 795         int fullmm = (*tlbp)->fullmm;
 796
 797         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
 798                 unsigned long end;
 799
 800                 start = max(vma->vm_start, start_addr);
 801                 if (start >= vma->vm_end)
 802                         continue;
 803                 end = min(vma->vm_end, end_addr);
 804                 if (end <= vma->vm_start)
 805                         continue;
 806
 807                 if (vma->vm_flags & VM_ACCOUNT)
 808                         *nr_accounted += (end - start) >> PAGE_SHIFT;
 809
 810                 while (start != end) {
 811                         if (!tlb_start_valid) {
 812                                 tlb_start = start;
 813                                 tlb_start_valid = 1;
 814                         }
 815
 816                         if (unlikely(is_vm_hugetlb_page(vma))) {
 817                                 unmap_hugepage_range(vma, start, end);
 818                                 zap_work -= (end - start) /
 819                                                 (HPAGE_SIZE / PAGE_SIZE);
 820                                 start = end;
 821                         } else
 822                                 start = unmap_page_range(*tlbp, vma,
 823                                                 start, end, &zap_work, details);
 824
 825                         if (zap_work > 0) {
 826                                 BUG_ON(start != end);
 827                                 break;
 828                         }
 829
 830                         tlb_finish_mmu(*tlbp, tlb_start, start);
 831
 832                         if (need_resched() ||
 833                                 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
 834                                 if (i_mmap_lock) {
 835                                         *tlbp = NULL;
 836                                         goto out;
 837                                 }
 838                                 cond_resched();
 839                         }
 840
 841                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
 842                         tlb_start_valid = 0;
 843                         zap_work = ZAP_BLOCK_SIZE;
 844                 }
 845         }
 846 out:
 847         return start;   /* which is now the end (or restart) address */
 848 }
 849
 850 /**
 851  * zap_page_range - remove user pages in a given range
 852  * @vma: vm_area_struct holding the applicable pages
 853  * @address: starting address of pages to zap
 854  * @size: number of bytes to zap
 855  * @details: details of nonlinear truncation or shared cache invalidation
 856  */
 857 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
 858                 unsigned long size, struct zap_details *details)
 859 {
 860         struct mm_struct *mm = vma->vm_mm;
 861         struct mmu_gather *tlb;
 862         unsigned long end = address + size;
 863         unsigned long nr_accounted = 0;
 864
 865         lru_add_drain();
 866         tlb = tlb_gather_mmu(mm, 0);
 867         update_hiwater_rss(mm);
 868         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
 869         if (tlb)
 870                 tlb_finish_mmu(tlb, address, end);
 871         return end;
 872 }
 873
 874 /*
 875  * Do a quick page-table lookup for a single page.
 876  */
 877 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 878                         unsigned int flags)
 879 {
 880         pgd_t *pgd;
 881         pud_t *pud;
 882         pmd_t *pmd;
 883         pte_t *ptep, pte;
 884         spinlock_t *ptl;
 885         struct page *page;
 886         struct mm_struct *mm = vma->vm_mm;
 887
 888         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
 889         if (!IS_ERR(page)) {
 890                 BUG_ON(flags & FOLL_GET);
 891                 goto out;
 892         }
 893
 894         page = NULL;
 895         pgd = pgd_offset(mm, address);
 896         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
 897                 goto no_page_table;
 898
 899         pud = pud_offset(pgd, address);
 900         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
 901                 goto no_page_table;
 902
 903         pmd = pmd_offset(pud, address);
 904         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
 905                 goto no_page_table;
 906
 907         if (pmd_huge(*pmd)) {
 908                 BUG_ON(flags & FOLL_GET);
 909                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
 910                 goto out;
 911         }
 912
 913         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
 914         if (!ptep)
 915                 goto out;
 916
 917         pte = *ptep;
 918         if (!pte_present(pte))
 919                 goto unlock;
 920         if ((flags & FOLL_WRITE) && !pte_write(pte))
 921                 goto unlock;
 922         page = vm_normal_page(vma, address, pte);
 923         if (unlikely(!page))
 924                 goto unlock;
 925
 926         if (flags & FOLL_GET)
 927                 get_page(page);
 928         if (flags & FOLL_TOUCH) {
 929                 if ((flags & FOLL_WRITE) &&
 930                     !pte_dirty(pte) && !PageDirty(page))
 931                         set_page_dirty(page);
 932                 mark_page_accessed(page);
 933         }
 934 unlock:
 935         pte_unmap_unlock(ptep, ptl);
 936 out:
 937         return page;
 938
 939 no_page_table:
 940         /*
 941          * When core dumping an enormous anonymous area that nobody
 942          * has touched so far, we don't want to allocate page tables.
 943          */
 944         if (flags & FOLL_ANON) {
 945                 page = ZERO_PAGE(address);
 946                 if (flags & FOLL_GET)
 947                         get_page(page);
 948                 BUG_ON(flags & FOLL_WRITE);
 949         }
 950         return page;
 951 }
 952
 953 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 954                 unsigned long start, int len, int write, int force,
 955                 struct page **pages, struct vm_area_struct **vmas)
 956 {
 957         int i;
 958         unsigned int vm_flags;
 959
 960         /*
 961          * Require read or write permissions.
 962          * If 'force' is set, we only require the "MAY" flags.
 963          */
 964         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 965         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 966         i = 0;
 967
 968         do {
 969                 struct vm_area_struct *vma;
 970                 unsigned int foll_flags;
 971
 972                 vma = find_extend_vma(mm, start);
 973                 if (!vma && in_gate_area(tsk, start)) {
 974                         unsigned long pg = start & PAGE_MASK;
 975                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
 976                         pgd_t *pgd;
 977                         pud_t *pud;
 978                         pmd_t *pmd;
 979                         pte_t *pte;
 980                         if (write) /* user gate pages are read-only */
 981                                 return i ? : -EFAULT;
 982                         if (pg > TASK_SIZE)
 983                                 pgd = pgd_offset_k(pg);
 984                         else
 985                                 pgd = pgd_offset_gate(mm, pg);
 986                         BUG_ON(pgd_none(*pgd));
 987                         pud = pud_offset(pgd, pg);
 988                         BUG_ON(pud_none(*pud));
 989                         pmd = pmd_offset(pud, pg);
 990                         if (pmd_none(*pmd))
 991                                 return i ? : -EFAULT;
 992                         pte = pte_offset_map(pmd, pg);
 993                         if (pte_none(*pte)) {
 994                                 pte_unmap(pte);
 995                                 return i ? : -EFAULT;
 996                         }
 997                         if (pages) {
 998                                 struct page *page = vm_normal_page(gate_vma, start, *pte);
 999                                 pages[i] = page;
1000                                 if (page)
1001                                         get_page(page);
1002                         }
1003                         pte_unmap(pte);
1004                         if (vmas)
1005                                 vmas[i] = gate_vma;
1006                         i++;
1007                         start += PAGE_SIZE;
1008                         len--;
1009                         continue;
1010                 }
1011
1012                 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1013                                 || !(vm_flags & vma->vm_flags))
1014                         return i ? : -EFAULT;
1015
1016                 if (is_vm_hugetlb_page(vma)) {
1017                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1018                                                 &start, &len, i);
1019                         continue;
1020                 }
1021
1022                 foll_flags = FOLL_TOUCH;
1023                 if (pages)
1024                         foll_flags |= FOLL_GET;
1025                 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1026                     (!vma->vm_ops || !vma->vm_ops->nopage))
1027                         foll_flags |= FOLL_ANON;
1028
1029                 do {
1030                         struct page *page;
1031
1032                         if (write)
1033                                 foll_flags |= FOLL_WRITE;
1034
1035                         cond_resched();
1036                         while (!(page = follow_page(vma, start, foll_flags))) {
1037                                 int ret;
1038                                 ret = __handle_mm_fault(mm, vma, start,
1039                                                 foll_flags & FOLL_WRITE);
1040                                 /*
1041                                  * The VM_FAULT_WRITE bit tells us that do_wp_page has
1042                                  * broken COW when necessary, even if maybe_mkwrite
1043                                  * decided not to set pte_write. We can thus safely do
1044                                  * subsequent page lookups as if they were reads.
1045                                  */
1046                                 if (ret & VM_FAULT_WRITE)
1047                                         foll_flags &= ~FOLL_WRITE;
1048
1049                                 switch (ret & ~VM_FAULT_WRITE) {
1050                                 case VM_FAULT_MINOR:
1051                                         tsk->min_flt++;
1052                                         break;
1053                                 case VM_FAULT_MAJOR:
1054                                         tsk->maj_flt++;
1055                                         break;
1056                                 case VM_FAULT_SIGBUS:
1057                                         return i ? i : -EFAULT;
1058                                 case VM_FAULT_OOM:
1059                                         return i ? i : -ENOMEM;
1060                                 default:
1061                                         BUG();
1062                                 }
1063                         }
1064                         if (pages) {
1065                                 pages[i] = page;
1066                                 flush_dcache_page(page);
1067                         }
1068                         if (vmas)
1069                                 vmas[i] = vma;
1070                         i++;
1071                         start += PAGE_SIZE;
1072                         len--;
1073                 } while (len && start < vma->vm_end);
1074         } while (len);
1075         return i;
1076 }
1077 EXPORT_SYMBOL(get_user_pages);
1078
1079 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1080                         unsigned long addr, unsigned long end, pgprot_t prot)
1081 {
1082         pte_t *pte;
1083         spinlock_t *ptl;
1084
1085         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1086         if (!pte)
1087                 return -ENOMEM;
1088         do {
1089                 struct page *page = ZERO_PAGE(addr);
1090                 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1091                 page_cache_get(page);
1092                 page_add_file_rmap(page);
1093                 inc_mm_counter(mm, file_rss);
1094                 BUG_ON(!pte_none(*pte));
1095                 set_pte_at(mm, addr, pte, zero_pte);
1096         } while (pte++, addr += PAGE_SIZE, addr != end);
1097         pte_unmap_unlock(pte - 1, ptl);
1098         return 0;
1099 }
1100
1101 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1102                         unsigned long addr, unsigned long end, pgprot_t prot)
1103 {
1104         pmd_t *pmd;
1105         unsigned long next;
1106
1107         pmd = pmd_alloc(mm, pud, addr);
1108         if (!pmd)
1109                 return -ENOMEM;
1110         do {
1111                 next = pmd_addr_end(addr, end);
1112                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1113                         return -ENOMEM;
1114         } while (pmd++, addr = next, addr != end);
1115         return 0;
1116 }
1117
1118 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1119                         unsigned long addr, unsigned long end, pgprot_t prot)
1120 {
1121         pud_t *pud;
1122         unsigned long next;
1123
1124         pud = pud_alloc(mm, pgd, addr);
1125         if (!pud)
1126                 return -ENOMEM;
1127         do {
1128                 next = pud_addr_end(addr, end);
1129                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1130                         return -ENOMEM;
1131         } while (pud++, addr = next, addr != end);
1132         return 0;
1133 }
1134
1135 int zeromap_page_range(struct vm_area_struct *vma,
1136                         unsigned long addr, unsigned long size, pgprot_t prot)
1137 {
1138         pgd_t *pgd;
1139         unsigned long next;
1140         unsigned long end = addr + size;
1141         struct mm_struct *mm = vma->vm_mm;
1142         int err;
1143
1144         BUG_ON(addr >= end);
1145         pgd = pgd_offset(mm, addr);
1146         flush_cache_range(vma, addr, end);
1147         do {
1148                 next = pgd_addr_end(addr, end);
1149                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1150                 if (err)
1151                         break;
1152         } while (pgd++, addr = next, addr != end);
1153         return err;
1154 }
1155
1156 pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1157 {
1158         pgd_t * pgd = pgd_offset(mm, addr);
1159         pud_t * pud = pud_alloc(mm, pgd, addr);
1160         if (pud) {
1161                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1162                 if (pmd)
1163                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1164         }
1165         return NULL;
1166 }
1167
1168 /*
1169  * This is the old fallback for page remapping.
1170  *
1171  * For historical reasons, it only allows reserved pages. Only
1172  * old drivers should use this, and they needed to mark their
1173  * pages reserved for the old functions anyway.
1174  */
1175 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1176 {
1177         int retval;
1178         pte_t *pte;
1179         spinlock_t *ptl;
1180
1181         retval = -EINVAL;
1182         if (PageAnon(page))
1183                 goto out;
1184         retval = -ENOMEM;
1185         flush_dcache_page(page);
1186         pte = get_locked_pte(mm, addr, &ptl);
1187         if (!pte)
1188                 goto out;
1189         retval = -EBUSY;
1190         if (!pte_none(*pte))
1191                 goto out_unlock;
1192
1193         /* Ok, finally just insert the thing.. */
1194         get_page(page);
1195         inc_mm_counter(mm, file_rss);
1196         page_add_file_rmap(page);
1197         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1198
1199         retval = 0;
1200 out_unlock:
1201         pte_unmap_unlock(pte, ptl);
1202 out:
1203         return retval;
1204 }
1205
1206 /*
1207  * This allows drivers to insert individual pages they've allocated
1208  * into a user vma.
1209  *
1210  * The page has to be a nice clean _individual_ kernel allocation.
1211  * If you allocate a compound page, you need to have marked it as
1212  * such (__GFP_COMP), or manually just split the page up yourself
1213  * (which is mainly an issue of doing "set_page_count(page, 1)" for
1214  * each sub-page, and then freeing them one by one when you free
1215  * them rather than freeing it as a compound page).
1216  *
1217  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1218  * took an arbitrary page protection parameter. This doesn't allow
1219  * that. Your vma protection will have to be set up correctly, which
1220  * means that if you want a shared writable mapping, you'd better
1221  * ask for a shared writable mapping!
1222  *
1223  * The page does not need to be reserved.
1224  */
1225 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1226 {
1227         if (addr < vma->vm_start || addr >= vma->vm_end)
1228                 return -EFAULT;
1229         if (!page_count(page))
1230                 return -EINVAL;
1231         vma->vm_flags |= VM_INSERTPAGE;
1232         return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1233 }
1234 EXPORT_SYMBOL(vm_insert_page);
1235
1236 /*
1237  * maps a range of physical memory into the requested pages. the old
1238  * mappings are removed. any references to nonexistent pages results
1239  * in null mappings (currently treated as "copy-on-access")
1240  */
1241 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1242                         unsigned long addr, unsigned long end,
1243                         unsigned long pfn, pgprot_t prot)
1244 {
1245         pte_t *pte;
1246         spinlock_t *ptl;
1247
1248         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1249         if (!pte)
1250                 return -ENOMEM;
1251         do {
1252                 BUG_ON(!pte_none(*pte));
1253                 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1254                 pfn++;
1255         } while (pte++, addr += PAGE_SIZE, addr != end);
1256         pte_unmap_unlock(pte - 1, ptl);
1257         return 0;
1258 }
1259
1260 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1261                         unsigned long addr, unsigned long end,
1262                         unsigned long pfn, pgprot_t prot)
1263 {
1264         pmd_t *pmd;
1265         unsigned long next;
1266
1267         pfn -= addr >> PAGE_SHIFT;
1268         pmd = pmd_alloc(mm, pud, addr);
1269         if (!pmd)
1270                 return -ENOMEM;
1271         do {
1272                 next = pmd_addr_end(addr, end);
1273                 if (remap_pte_range(mm, pmd, addr, next,
1274                                 pfn + (addr >> PAGE_SHIFT), prot))
1275                         return -ENOMEM;
1276         } while (pmd++, addr = next, addr != end);
1277         return 0;
1278 }
1279
1280 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1281                         unsigned long addr, unsigned long end,
1282                         unsigned long pfn, pgprot_t prot)
1283 {
1284         pud_t *pud;
1285         unsigned long next;
1286
1287         pfn -= addr >> PAGE_SHIFT;
1288         pud = pud_alloc(mm, pgd, addr);
1289         if (!pud)
1290                 return -ENOMEM;
1291         do {
1292                 next = pud_addr_end(addr, end);
1293                 if (remap_pmd_range(mm, pud, addr, next,
1294                                 pfn + (addr >> PAGE_SHIFT), prot))
1295                         return -ENOMEM;
1296         } while (pud++, addr = next, addr != end);
1297         return 0;
1298 }
1299
1300 /*  Note: this is only safe if the mm semaphore is held when called. */
1301 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1302                     unsigned long pfn, unsigned long size, pgprot_t prot)
1303 {
1304         pgd_t *pgd;
1305         unsigned long next;
1306         unsigned long end = addr + PAGE_ALIGN(size);
1307         struct mm_struct *mm = vma->vm_mm;
1308         int err;
1309
1310         /*
1311          * Physically remapped pages are special. Tell the
1312          * rest of the world about it:
1313          *   VM_IO tells people not to look at these pages
1314          *      (accesses can have side effects).
1315          *   VM_RESERVED is specified all over the place, because
1316          *      in 2.4 it kept swapout's vma scan off this vma; but
1317          *      in 2.6 the LRU scan won't even find its pages, so this
1318          *      flag means no more than count its pages in reserved_vm,
1319          *      and omit it from core dump, even when VM_IO turned off.
1320          *   VM_PFNMAP tells the core MM that the base pages are just
1321          *      raw PFN mappings, and do not have a "struct page" associated
1322          *      with them.
1323          *
1324          * There's a horrible special case to handle copy-on-write
1325          * behaviour that some programs depend on. We mark the "original"
1326          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1327          */
1328         if (is_cow_mapping(vma->vm_flags)) {
1329                 if (addr != vma->vm_start || end != vma->vm_end)
1330                         return -EINVAL;
1331                 vma->vm_pgoff = pfn;
1332         }
1333
1334         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1335
1336         BUG_ON(addr >= end);
1337         pfn -= addr >> PAGE_SHIFT;
1338         pgd = pgd_offset(mm, addr);
1339         flush_cache_range(vma, addr, end);
1340         do {
1341                 next = pgd_addr_end(addr, end);
1342                 err = remap_pud_range(mm, pgd, addr, next,
1343                                 pfn + (addr >> PAGE_SHIFT), prot);
1344                 if (err)
1345                         break;
1346         } while (pgd++, addr = next, addr != end);
1347         return err;
1348 }
1349 EXPORT_SYMBOL(remap_pfn_range);
1350
1351 /*
1352  * handle_pte_fault chooses page fault handler according to an entry
1353  * which was read non-atomically.  Before making any commitment, on
1354  * those architectures or configurations (e.g. i386 with PAE) which
1355  * might give a mix of unmatched parts, do_swap_page and do_file_page
1356  * must check under lock before unmapping the pte and proceeding
1357  * (but do_wp_page is only called after already making such a check;
1358  * and do_anonymous_page and do_no_page can safely check later on).
1359  */
1360 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1361                                 pte_t *page_table, pte_t orig_pte)
1362 {
1363         int same = 1;
1364 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1365         if (sizeof(pte_t) > sizeof(unsigned long)) {
1366                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1367                 spin_lock(ptl);
1368                 same = pte_same(*page_table, orig_pte);
1369                 spin_unlock(ptl);
1370         }
1371 #endif
1372         pte_unmap(page_table);
1373         return same;
1374 }
1375
1376 /*
1377  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1378  * servicing faults for write access.  In the normal case, do always want
1379  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1380  * that do not have writing enabled, when used by access_process_vm.
1381  */
1382 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1383 {
1384         if (likely(vma->vm_flags & VM_WRITE))
1385                 pte = pte_mkwrite(pte);
1386         return pte;
1387 }
1388
1389 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1390 {
1391         /*
1392          * If the source page was a PFN mapping, we don't have
1393          * a "struct page" for it. We do a best-effort copy by
1394          * just copying from the original user address. If that
1395          * fails, we just zero-fill it. Live with it.
1396          */
1397         if (unlikely(!src)) {
1398                 void *kaddr = kmap_atomic(dst, KM_USER0);
1399                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1400
1401                 /*
1402                  * This really shouldn't fail, because the page is there
1403                  * in the page tables. But it might just be unreadable,
1404                  * in which case we just give up and fill the result with
1405                  * zeroes.
1406                  */
1407                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1408                         memset(kaddr, 0, PAGE_SIZE);
1409                 kunmap_atomic(kaddr, KM_USER0);
1410                 return;
1411
1412         }
1413         copy_user_highpage(dst, src, va);
1414 }
1415
1416 /*
1417  * This routine handles present pages, when users try to write
1418  * to a shared page. It is done by copying the page to a new address
1419  * and decrementing the shared-page counter for the old page.
1420  *
1421  * Note that this routine assumes that the protection checks have been
1422  * done by the caller (the low-level page fault routine in most cases).
1423  * Thus we can safely just mark it writable once we've done any necessary
1424  * COW.
1425  *
1426  * We also mark the page dirty at this point even though the page will
1427  * change only once the write actually happens. This avoids a few races,
1428  * and potentially makes it more efficient.
1429  *
1430  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1431  * but allow concurrent faults), with pte both mapped and locked.
1432  * We return with mmap_sem still held, but pte unmapped and unlocked.
1433  */
1434 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1435                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1436                 spinlock_t *ptl, pte_t orig_pte)
1437 {
1438         struct page *old_page, *new_page;
1439         pte_t entry;
1440         int ret = VM_FAULT_MINOR;
1441
1442         old_page = vm_normal_page(vma, address, orig_pte);
1443         if (!old_page)
1444                 goto gotten;
1445
1446         if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
1447                 int reuse = can_share_swap_page(old_page);
1448                 unlock_page(old_page);
1449                 if (reuse) {
1450                         flush_cache_page(vma, address, pte_pfn(orig_pte));
1451                         entry = pte_mkyoung(orig_pte);
1452                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1453                         ptep_set_access_flags(vma, address, page_table, entry, 1);
1454                         update_mmu_cache(vma, address, entry);
1455                         lazy_mmu_prot_update(entry);
1456                         ret |= VM_FAULT_WRITE;
1457                         goto unlock;
1458                 }
1459         }
1460
1461         /*
1462          * Ok, we need to copy. Oh, well..
1463          */
1464         page_cache_get(old_page);
1465 gotten:
1466         pte_unmap_unlock(page_table, ptl);
1467
1468         if (unlikely(anon_vma_prepare(vma)))
1469                 goto oom;
1470         if (old_page == ZERO_PAGE(address)) {
1471                 new_page = alloc_zeroed_user_highpage(vma, address);
1472                 if (!new_page)
1473                         goto oom;
1474         } else {
1475                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1476                 if (!new_page)
1477                         goto oom;
1478                 cow_user_page(new_page, old_page, address);
1479         }
1480
1481         /*
1482          * Re-check the pte - we dropped the lock
1483          */
1484         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1485         if (likely(pte_same(*page_table, orig_pte))) {
1486                 if (old_page) {
1487                         page_remove_rmap(old_page);
1488                         if (!PageAnon(old_page)) {
1489                                 dec_mm_counter(mm, file_rss);
1490                                 inc_mm_counter(mm, anon_rss);
1491                         }
1492                 } else
1493                         inc_mm_counter(mm, anon_rss);
1494                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1495                 entry = mk_pte(new_page, vma->vm_page_prot);
1496                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1497                 ptep_establish(vma, address, page_table, entry);
1498                 update_mmu_cache(vma, address, entry);
1499                 lazy_mmu_prot_update(entry);
1500                 lru_cache_add_active(new_page);
1501                 page_add_new_anon_rmap(new_page, vma, address);
1502
1503                 /* Free the old page.. */
1504                 new_page = old_page;
1505                 ret |= VM_FAULT_WRITE;
1506         }
1507         if (new_page)
1508                 page_cache_release(new_page);
1509         if (old_page)
1510                 page_cache_release(old_page);
1511 unlock:
1512         pte_unmap_unlock(page_table, ptl);
1513         return ret;
1514 oom:
1515         if (old_page)
1516                 page_cache_release(old_page);
1517         return VM_FAULT_OOM;
1518 }
1519
1520 /*
1521  * Helper functions for unmap_mapping_range().
1522  *
1523  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1524  *
1525  * We have to restart searching the prio_tree whenever we drop the lock,
1526  * since the iterator is only valid while the lock is held, and anyway
1527  * a later vma might be split and reinserted earlier while lock dropped.
1528  *
1529  * The list of nonlinear vmas could be handled more efficiently, using
1530  * a placeholder, but handle it in the same way until a need is shown.
1531  * It is important to search the prio_tree before nonlinear list: a vma
1532  * may become nonlinear and be shifted from prio_tree to nonlinear list
1533  * while the lock is dropped; but never shifted from list to prio_tree.
1534  *
1535  * In order to make forward progress despite restarting the search,
1536  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1537  * quickly skip it next time around.  Since the prio_tree search only
1538  * shows us those vmas affected by unmapping the range in question, we
1539  * can't efficiently keep all vmas in step with mapping->truncate_count:
1540  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1541  * mapping->truncate_count and vma->vm_truncate_count are protected by
1542  * i_mmap_lock.
1543  *
1544  * In order to make forward progress despite repeatedly restarting some
1545  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1546  * and restart from that address when we reach that vma again.  It might
1547  * have been split or merged, shrunk or extended, but never shifted: so
1548  * restart_addr remains valid so long as it remains in the vma's range.
1549  * unmap_mapping_range forces truncate_count to leap over page-aligned
1550  * values so we can save vma's restart_addr in its truncate_count field.
1551  */
1552 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1553
1554 static void reset_vma_truncate_counts(struct address_space *mapping)
1555 {
1556         struct vm_area_struct *vma;
1557         struct prio_tree_iter iter;
1558
1559         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1560                 vma->vm_truncate_count = 0;
1561         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1562                 vma->vm_truncate_count = 0;
1563 }
1564
1565 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1566                 unsigned long start_addr, unsigned long end_addr,
1567                 struct zap_details *details)
1568 {
1569         unsigned long restart_addr;
1570         int need_break;
1571
1572 again:
1573         restart_addr = vma->vm_truncate_count;
1574         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1575                 start_addr = restart_addr;
1576                 if (start_addr >= end_addr) {
1577                         /* Top of vma has been split off since last time */
1578                         vma->vm_truncate_count = details->truncate_count;
1579                         return 0;
1580                 }
1581         }
1582
1583         restart_addr = zap_page_range(vma, start_addr,
1584                                         end_addr - start_addr, details);
1585         need_break = need_resched() ||
1586                         need_lockbreak(details->i_mmap_lock);
1587
1588         if (restart_addr >= end_addr) {
1589                 /* We have now completed this vma: mark it so */
1590                 vma->vm_truncate_count = details->truncate_count;
1591                 if (!need_break)
1592                         return 0;
1593         } else {
1594                 /* Note restart_addr in vma's truncate_count field */
1595                 vma->vm_truncate_count = restart_addr;
1596                 if (!need_break)
1597                         goto again;
1598         }
1599
1600         spin_unlock(details->i_mmap_lock);
1601         cond_resched();
1602         spin_lock(details->i_mmap_lock);
1603         return -EINTR;
1604 }
1605
1606 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1607                                             struct zap_details *details)
1608 {
1609         struct vm_area_struct *vma;
1610         struct prio_tree_iter iter;
1611         pgoff_t vba, vea, zba, zea;
1612
1613 restart:
1614         vma_prio_tree_foreach(vma, &iter, root,
1615                         details->first_index, details->last_index) {
1616                 /* Skip quickly over those we have already dealt with */
1617                 if (vma->vm_truncate_count == details->truncate_count)
1618                         continue;
1619
1620                 vba = vma->vm_pgoff;
1621                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1622                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1623                 zba = details->first_index;
1624                 if (zba < vba)
1625                         zba = vba;
1626                 zea = details->last_index;
1627                 if (zea > vea)
1628                         zea = vea;
1629
1630                 if (unmap_mapping_range_vma(vma,
1631                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1632                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1633                                 details) < 0)
1634                         goto restart;
1635         }
1636 }
1637
1638 static inline void unmap_mapping_range_list(struct list_head *head,
1639                                             struct zap_details *details)
1640 {
1641         struct vm_area_struct *vma;
1642
1643         /*
1644          * In nonlinear VMAs there is no correspondence between virtual address
1645          * offset and file offset.  So we must perform an exhaustive search
1646          * across *all* the pages in each nonlinear VMA, not just the pages
1647          * whose virtual address lies outside the file truncation point.
1648          */
1649 restart:
1650         list_for_each_entry(vma, head, shared.vm_set.list) {
1651                 /* Skip quickly over those we have already dealt with */
1652                 if (vma->vm_truncate_count == details->truncate_count)
1653                         continue;
1654                 details->nonlinear_vma = vma;
1655                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1656                                         vma->vm_end, details) < 0)
1657                         goto restart;
1658         }
1659 }
1660
1661 /**
1662  * unmap_mapping_range - unmap the portion of all mmaps
1663  * in the specified address_space corresponding to the specified
1664  * page range in the underlying file.
1665  * @mapping: the address space containing mmaps to be unmapped.
1666  * @holebegin: byte in first page to unmap, relative to the start of
1667  * the underlying file.  This will be rounded down to a PAGE_SIZE
1668  * boundary.  Note that this is different from vmtruncate(), which
1669  * must keep the partial page.  In contrast, we must get rid of
1670  * partial pages.
1671  * @holelen: size of prospective hole in bytes.  This will be rounded
1672  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1673  * end of the file.
1674  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1675  * but 0 when invalidating pagecache, don't throw away private data.
1676  */
1677 void unmap_mapping_range(struct address_space *mapping,
1678                 loff_t const holebegin, loff_t const holelen, int even_cows)
1679 {
1680         struct zap_details details;
1681         pgoff_t hba = holebegin >> PAGE_SHIFT;
1682         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1683
1684         /* Check for overflow. */
1685         if (sizeof(holelen) > sizeof(hlen)) {
1686                 long long holeend =
1687                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1688                 if (holeend & ~(long long)ULONG_MAX)
1689                         hlen = ULONG_MAX - hba + 1;
1690         }
1691
1692         details.check_mapping = even_cows? NULL: mapping;
1693         details.nonlinear_vma = NULL;
1694         details.first_index = hba;
1695         details.last_index = hba + hlen - 1;
1696         if (details.last_index < details.first_index)
1697                 details.last_index = ULONG_MAX;
1698         details.i_mmap_lock = &mapping->i_mmap_lock;
1699
1700         spin_lock(&mapping->i_mmap_lock);
1701
1702         /* serialize i_size write against truncate_count write */
1703         smp_wmb();
1704         /* Protect against page faults, and endless unmapping loops */
1705         mapping->truncate_count++;
1706         /*
1707          * For archs where spin_lock has inclusive semantics like ia64
1708          * this smp_mb() will prevent to read pagetable contents
1709          * before the truncate_count increment is visible to
1710          * other cpus.
1711          */
1712         smp_mb();
1713         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1714                 if (mapping->truncate_count == 0)
1715                         reset_vma_truncate_counts(mapping);
1716                 mapping->truncate_count++;
1717         }
1718         details.truncate_count = mapping->truncate_count;
1719
1720         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1721                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1722         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1723                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1724         spin_unlock(&mapping->i_mmap_lock);
1725 }
1726 EXPORT_SYMBOL(unmap_mapping_range);
1727
1728 /*
1729  * Handle all mappings that got truncated by a "truncate()"
1730  * system call.
1731  *
1732  * NOTE! We have to be ready to update the memory sharing
1733  * between the file and the memory map for a potential last
1734  * incomplete page.  Ugly, but necessary.
1735  */
1736 int vmtruncate(struct inode * inode, loff_t offset)
1737 {
1738         struct address_space *mapping = inode->i_mapping;
1739         unsigned long limit;
1740
1741         if (inode->i_size < offset)
1742                 goto do_expand;
1743         /*
1744          * truncation of in-use swapfiles is disallowed - it would cause
1745          * subsequent swapout to scribble on the now-freed blocks.
1746          */
1747         if (IS_SWAPFILE(inode))
1748                 goto out_busy;
1749         i_size_write(inode, offset);
1750         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1751         truncate_inode_pages(mapping, offset);
1752         goto out_truncate;
1753
1754 do_expand:
1755         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1756         if (limit != RLIM_INFINITY && offset > limit)
1757                 goto out_sig;
1758         if (offset > inode->i_sb->s_maxbytes)
1759                 goto out_big;
1760         i_size_write(inode, offset);
1761
1762 out_truncate:
1763         if (inode->i_op && inode->i_op->truncate)
1764                 inode->i_op->truncate(inode);
1765         return 0;
1766 out_sig:
1767         send_sig(SIGXFSZ, current, 0);
1768 out_big:
1769         return -EFBIG;
1770 out_busy:
1771         return -ETXTBSY;
1772 }
1773 EXPORT_SYMBOL(vmtruncate);
1774
1775 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1776 {
1777         struct address_space *mapping = inode->i_mapping;
1778
1779         /*
1780          * If the underlying filesystem is not going to provide
1781          * a way to truncate a range of blocks (punch a hole) -
1782          * we should return failure right now.
1783          */
1784         if (!inode->i_op || !inode->i_op->truncate_range)
1785                 return -ENOSYS;
1786
1787         mutex_lock(&inode->i_mutex);
1788         down_write(&inode->i_alloc_sem);
1789         unmap_mapping_range(mapping, offset, (end - offset), 1);
1790         truncate_inode_pages_range(mapping, offset, end);
1791         inode->i_op->truncate_range(inode, offset, end);
1792         up_write(&inode->i_alloc_sem);
1793         mutex_unlock(&inode->i_mutex);
1794
1795         return 0;
1796 }
1797 EXPORT_SYMBOL(vmtruncate_range);
1798
1799 /*
1800  * Primitive swap readahead code. We simply read an aligned block of
1801  * (1 << page_cluster) entries in the swap area. This method is chosen
1802  * because it doesn't cost us any seek time.  We also make sure to queue
1803  * the 'original' request together with the readahead ones...
1804  *
1805  * This has been extended to use the NUMA policies from the mm triggering
1806  * the readahead.
1807  *
1808  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1809  */
1810 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1811 {
1812 #ifdef CONFIG_NUMA
1813         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1814 #endif
1815         int i, num;
1816         struct page *new_page;
1817         unsigned long offset;
1818
1819         /*
1820          * Get the number of handles we should do readahead io to.
1821          */
1822         num = valid_swaphandles(entry, &offset);
1823         for (i = 0; i < num; offset++, i++) {
1824                 /* Ok, do the async read-ahead now */
1825                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1826                                                            offset), vma, addr);
1827                 if (!new_page)
1828                         break;
1829                 page_cache_release(new_page);
1830 #ifdef CONFIG_NUMA
1831                 /*
1832                  * Find the next applicable VMA for the NUMA policy.
1833                  */
1834                 addr += PAGE_SIZE;
1835                 if (addr == 0)
1836                         vma = NULL;
1837                 if (vma) {
1838                         if (addr >= vma->vm_end) {
1839                                 vma = next_vma;
1840                                 next_vma = vma ? vma->vm_next : NULL;
1841                         }
1842                         if (vma && addr < vma->vm_start)
1843                                 vma = NULL;
1844                 } else {
1845                         if (next_vma && addr >= next_vma->vm_start) {
1846                                 vma = next_vma;
1847                                 next_vma = vma->vm_next;
1848                         }
1849                 }
1850 #endif
1851         }
1852         lru_add_drain();        /* Push any new pages onto the LRU now */
1853 }
1854
1855 /*
1856  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1857  * but allow concurrent faults), and pte mapped but not yet locked.
1858  * We return with mmap_sem still held, but pte unmapped and unlocked.
1859  */
1860 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1861                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1862                 int write_access, pte_t orig_pte)
1863 {
1864         spinlock_t *ptl;
1865         struct page *page;
1866         swp_entry_t entry;
1867         pte_t pte;
1868         int ret = VM_FAULT_MINOR;
1869
1870         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1871                 goto out;
1872
1873         entry = pte_to_swp_entry(orig_pte);
1874         page = lookup_swap_cache(entry);
1875         if (!page) {
1876                 swapin_readahead(entry, address, vma);
1877                 page = read_swap_cache_async(entry, vma, address);
1878                 if (!page) {
1879                         /*
1880                          * Back out if somebody else faulted in this pte
1881                          * while we released the pte lock.
1882                          */
1883                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1884                         if (likely(pte_same(*page_table, orig_pte)))
1885                                 ret = VM_FAULT_OOM;
1886                         goto unlock;
1887                 }
1888
1889                 /* Had to read the page from swap area: Major fault */
1890                 ret = VM_FAULT_MAJOR;
1891                 inc_page_state(pgmajfault);
1892                 grab_swap_token();
1893         }
1894
1895         mark_page_accessed(page);
1896         lock_page(page);
1897
1898         /*
1899          * Back out if somebody else already faulted in this pte.
1900          */
1901         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1902         if (unlikely(!pte_same(*page_table, orig_pte)))
1903                 goto out_nomap;
1904
1905         if (unlikely(!PageUptodate(page))) {
1906                 ret = VM_FAULT_SIGBUS;
1907                 goto out_nomap;
1908         }
1909
1910         /* The page isn't present yet, go ahead with the fault. */
1911
1912         inc_mm_counter(mm, anon_rss);
1913         pte = mk_pte(page, vma->vm_page_prot);
1914         if (write_access && can_share_swap_page(page)) {
1915                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1916                 write_access = 0;
1917         }
1918
1919         flush_icache_page(vma, page);
1920         set_pte_at(mm, address, page_table, pte);
1921         page_add_anon_rmap(page, vma, address);
1922
1923         swap_free(entry);
1924         if (vm_swap_full())
1925                 remove_exclusive_swap_page(page);
1926         unlock_page(page);
1927
1928         if (write_access) {
1929                 if (do_wp_page(mm, vma, address,
1930                                 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
1931                         ret = VM_FAULT_OOM;
1932                 goto out;
1933         }
1934
1935         /* No need to invalidate - it was non-present before */
1936         update_mmu_cache(vma, address, pte);
1937         lazy_mmu_prot_update(pte);
1938 unlock:
1939         pte_unmap_unlock(page_table, ptl);
1940 out:
1941         return ret;
1942 out_nomap:
1943         pte_unmap_unlock(page_table, ptl);
1944         unlock_page(page);
1945         page_cache_release(page);
1946         return ret;
1947 }
1948
1949 /*
1950  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1951  * but allow concurrent faults), and pte mapped but not yet locked.
1952  * We return with mmap_sem still held, but pte unmapped and unlocked.
1953  */
1954 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1955                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1956                 int write_access)
1957 {
1958         struct page *page;
1959         spinlock_t *ptl;
1960         pte_t entry;
1961
1962         if (write_access) {
1963                 /* Allocate our own private page. */
1964                 pte_unmap(page_table);
1965
1966                 if (unlikely(anon_vma_prepare(vma)))
1967                         goto oom;
1968                 page = alloc_zeroed_user_highpage(vma, address);
1969                 if (!page)
1970                         goto oom;
1971
1972                 entry = mk_pte(page, vma->vm_page_prot);
1973                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1974
1975                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1976                 if (!pte_none(*page_table))
1977                         goto release;
1978                 inc_mm_counter(mm, anon_rss);
1979                 lru_cache_add_active(page);
1980                 page_add_new_anon_rmap(page, vma, address);
1981         } else {
1982                 /* Map the ZERO_PAGE - vm_page_prot is readonly */
1983                 page = ZERO_PAGE(address);
1984                 page_cache_get(page);
1985                 entry = mk_pte(page, vma->vm_page_prot);
1986
1987                 ptl = pte_lockptr(mm, pmd);
1988                 spin_lock(ptl);
1989                 if (!pte_none(*page_table))
1990                         goto release;
1991                 inc_mm_counter(mm, file_rss);
1992                 page_add_file_rmap(page);
1993         }
1994
1995         set_pte_at(mm, address, page_table, entry);
1996
1997         /* No need to invalidate - it was non-present before */
1998         update_mmu_cache(vma, address, entry);
1999         lazy_mmu_prot_update(entry);
2000 unlock:
2001         pte_unmap_unlock(page_table, ptl);
2002         return VM_FAULT_MINOR;
2003 release:
2004         page_cache_release(page);
2005         goto unlock;
2006 oom:
2007         return VM_FAULT_OOM;
2008 }
2009
2010 /*
2011  * do_no_page() tries to create a new page mapping. It aggressively
2012  * tries to share with existing pages, but makes a separate copy if
2013  * the "write_access" parameter is true in order to avoid the next
2014  * page fault.
2015  *
2016  * As this is called only for pages that do not currently exist, we
2017  * do not need to flush old virtual caches or the TLB.
2018  *
2019  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2020  * but allow concurrent faults), and pte mapped but not yet locked.
2021  * We return with mmap_sem still held, but pte unmapped and unlocked.
2022  */
2023 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2024                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2025                 int write_access)
2026 {
2027         spinlock_t *ptl;
2028         struct page *new_page;
2029         struct address_space *mapping = NULL;
2030         pte_t entry;
2031         unsigned int sequence = 0;
2032         int ret = VM_FAULT_MINOR;
2033         int anon = 0;
2034
2035         pte_unmap(page_table);
2036         BUG_ON(vma->vm_flags & VM_PFNMAP);
2037
2038         if (vma->vm_file) {
2039                 mapping = vma->vm_file->f_mapping;
2040                 sequence = mapping->truncate_count;
2041                 smp_rmb(); /* serializes i_size against truncate_count */
2042         }
2043 retry:
2044         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2045         /*
2046          * No smp_rmb is needed here as long as there's a full
2047          * spin_lock/unlock sequence inside the ->nopage callback
2048          * (for the pagecache lookup) that acts as an implicit
2049          * smp_mb() and prevents the i_size read to happen
2050          * after the next truncate_count read.
2051          */
2052
2053         /* no page was available -- either SIGBUS or OOM */
2054         if (new_page == NOPAGE_SIGBUS)
2055                 return VM_FAULT_SIGBUS;
2056         if (new_page == NOPAGE_OOM)
2057                 return VM_FAULT_OOM;
2058
2059         /*
2060          * Should we do an early C-O-W break?
2061          */
2062         if (write_access && !(vma->vm_flags & VM_SHARED)) {
2063                 struct page *page;
2064
2065                 if (unlikely(anon_vma_prepare(vma)))
2066                         goto oom;
2067                 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2068                 if (!page)
2069                         goto oom;
2070                 copy_user_highpage(page, new_page, address);
2071                 page_cache_release(new_page);
2072                 new_page = page;
2073                 anon = 1;
2074         }
2075
2076         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2077         /*
2078          * For a file-backed vma, someone could have truncated or otherwise
2079          * invalidated this page.  If unmap_mapping_range got called,
2080          * retry getting the page.
2081          */
2082         if (mapping && unlikely(sequence != mapping->truncate_count)) {
2083                 pte_unmap_unlock(page_table, ptl);
2084                 page_cache_release(new_page);
2085                 cond_resched();
2086                 sequence = mapping->truncate_count;
2087                 smp_rmb();
2088                 goto retry;
2089         }
2090
2091         /*
2092          * This silly early PAGE_DIRTY setting removes a race
2093          * due to the bad i386 page protection. But it's valid
2094          * for other architectures too.
2095          *
2096          * Note that if write_access is true, we either now have
2097          * an exclusive copy of the page, or this is a shared mapping,
2098          * so we can make it writable and dirty to avoid having to
2099          * handle that later.
2100          */
2101         /* Only go through if we didn't race with anybody else... */
2102         if (pte_none(*page_table)) {
2103                 flush_icache_page(vma, new_page);
2104                 entry = mk_pte(new_page, vma->vm_page_prot);
2105                 if (write_access)
2106                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2107                 set_pte_at(mm, address, page_table, entry);
2108                 if (anon) {
2109                         inc_mm_counter(mm, anon_rss);
2110                         lru_cache_add_active(new_page);
2111                         page_add_new_anon_rmap(new_page, vma, address);
2112                 } else {
2113                         inc_mm_counter(mm, file_rss);
2114                         page_add_file_rmap(new_page);
2115                 }
2116         } else {
2117                 /* One of our sibling threads was faster, back out. */
2118                 page_cache_release(new_page);
2119                 goto unlock;
2120         }
2121
2122         /* no need to invalidate: a not-present page shouldn't be cached */
2123         update_mmu_cache(vma, address, entry);
2124         lazy_mmu_prot_update(entry);
2125 unlock:
2126         pte_unmap_unlock(page_table, ptl);
2127         return ret;
2128 oom:
2129         page_cache_release(new_page);
2130         return VM_FAULT_OOM;
2131 }
2132
2133 /*
2134  * Fault of a previously existing named mapping. Repopulate the pte
2135  * from the encoded file_pte if possible. This enables swappable
2136  * nonlinear vmas.
2137  *
2138  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2139  * but allow concurrent faults), and pte mapped but not yet locked.
2140  * We return with mmap_sem still held, but pte unmapped and unlocked.
2141  */
2142 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2143                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2144                 int write_access, pte_t orig_pte)
2145 {
2146         pgoff_t pgoff;
2147         int err;
2148
2149         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2150                 return VM_FAULT_MINOR;
2151
2152         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2153                 /*
2154                  * Page table corrupted: show pte and kill process.
2155                  */
2156                 print_bad_pte(vma, orig_pte, address);
2157                 return VM_FAULT_OOM;
2158         }
2159         /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2160
2161         pgoff = pte_to_pgoff(orig_pte);
2162         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2163                                         vma->vm_page_prot, pgoff, 0);
2164         if (err == -ENOMEM)
2165                 return VM_FAULT_OOM;
2166         if (err)
2167                 return VM_FAULT_SIGBUS;
2168         return VM_FAULT_MAJOR;
2169 }
2170
2171 /*
2172  * These routines also need to handle stuff like marking pages dirty
2173  * and/or accessed for architectures that don't do it in hardware (most
2174  * RISC architectures).  The early dirtying is also good on the i386.
2175  *
2176  * There is also a hook called "update_mmu_cache()" that architectures
2177  * with external mmu caches can use to update those (ie the Sparc or
2178  * PowerPC hashed page tables that act as extended TLBs).
2179  *
2180  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2181  * but allow concurrent faults), and pte mapped but not yet locked.
2182  * We return with mmap_sem still held, but pte unmapped and unlocked.
2183  */
2184 static inline int handle_pte_fault(struct mm_struct *mm,
2185                 struct vm_area_struct *vma, unsigned long address,
2186                 pte_t *pte, pmd_t *pmd, int write_access)
2187 {
2188         pte_t entry;
2189         pte_t old_entry;
2190         spinlock_t *ptl;
2191
2192         old_entry = entry = *pte;
2193         if (!pte_present(entry)) {
2194                 if (pte_none(entry)) {
2195                         if (!vma->vm_ops || !vma->vm_ops->nopage)
2196                                 return do_anonymous_page(mm, vma, address,
2197                                         pte, pmd, write_access);
2198                         return do_no_page(mm, vma, address,
2199                                         pte, pmd, write_access);
2200                 }
2201                 if (pte_file(entry))
2202                         return do_file_page(mm, vma, address,
2203                                         pte, pmd, write_access, entry);
2204                 return do_swap_page(mm, vma, address,
2205                                         pte, pmd, write_access, entry);
2206         }
2207
2208         ptl = pte_lockptr(mm, pmd);
2209         spin_lock(ptl);
2210         if (unlikely(!pte_same(*pte, entry)))
2211                 goto unlock;
2212         if (write_access) {
2213                 if (!pte_write(entry))
2214                         return do_wp_page(mm, vma, address,
2215                                         pte, pmd, ptl, entry);
2216                 entry = pte_mkdirty(entry);
2217         }
2218         entry = pte_mkyoung(entry);
2219         if (!pte_same(old_entry, entry)) {
2220                 ptep_set_access_flags(vma, address, pte, entry, write_access);
2221                 update_mmu_cache(vma, address, entry);
2222                 lazy_mmu_prot_update(entry);
2223         } else {
2224                 /*
2225                  * This is needed only for protection faults but the arch code
2226                  * is not yet telling us if this is a protection fault or not.
2227                  * This still avoids useless tlb flushes for .text page faults
2228                  * with threads.
2229                  */
2230                 if (write_access)
2231                         flush_tlb_page(vma, address);
2232         }
2233 unlock:
2234         pte_unmap_unlock(pte, ptl);
2235         return VM_FAULT_MINOR;
2236 }
2237
2238 /*
2239  * By the time we get here, we already hold the mm semaphore
2240  */
2241 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2242                 unsigned long address, int write_access)
2243 {
2244         pgd_t *pgd;
2245         pud_t *pud;
2246         pmd_t *pmd;
2247         pte_t *pte;
2248
2249         __set_current_state(TASK_RUNNING);
2250
2251         inc_page_state(pgfault);
2252
2253         if (unlikely(is_vm_hugetlb_page(vma)))
2254                 return hugetlb_fault(mm, vma, address, write_access);
2255
2256         pgd = pgd_offset(mm, address);
2257         pud = pud_alloc(mm, pgd, address);
2258         if (!pud)
2259                 return VM_FAULT_OOM;
2260         pmd = pmd_alloc(mm, pud, address);
2261         if (!pmd)
2262                 return VM_FAULT_OOM;
2263         pte = pte_alloc_map(mm, pmd, address);
2264         if (!pte)
2265                 return VM_FAULT_OOM;
2266
2267         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2268 }
2269
2270 EXPORT_SYMBOL_GPL(__handle_mm_fault);
2271
2272 #ifndef __PAGETABLE_PUD_FOLDED
2273 /*
2274  * Allocate page upper directory.
2275  * We've already handled the fast-path in-line.
2276  */
2277 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2278 {
2279         pud_t *new = pud_alloc_one(mm, address);
2280         if (!new)
2281                 return -ENOMEM;
2282
2283         spin_lock(&mm->page_table_lock);
2284         if (pgd_present(*pgd))          /* Another has populated it */
2285                 pud_free(new);
2286         else
2287                 pgd_populate(mm, pgd, new);
2288         spin_unlock(&mm->page_table_lock);
2289         return 0;
2290 }
2291 #else
2292 /* Workaround for gcc 2.96 */
2293 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2294 {
2295         return 0;
2296 }
2297 #endif /* __PAGETABLE_PUD_FOLDED */
2298
2299 #ifndef __PAGETABLE_PMD_FOLDED
2300 /*
2301  * Allocate page middle directory.
2302  * We've already handled the fast-path in-line.
2303  */
2304 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2305 {
2306         pmd_t *new = pmd_alloc_one(mm, address);
2307         if (!new)
2308                 return -ENOMEM;
2309
2310         spin_lock(&mm->page_table_lock);
2311 #ifndef __ARCH_HAS_4LEVEL_HACK
2312         if (pud_present(*pud))          /* Another has populated it */
2313                 pmd_free(new);
2314         else
2315                 pud_populate(mm, pud, new);
2316 #else
2317         if (pgd_present(*pud))          /* Another has populated it */
2318                 pmd_free(new);
2319         else
2320                 pgd_populate(mm, pud, new);
2321 #endif /* __ARCH_HAS_4LEVEL_HACK */
2322         spin_unlock(&mm->page_table_lock);
2323         return 0;
2324 }
2325 #else
2326 /* Workaround for gcc 2.96 */
2327 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2328 {
2329         return 0;
2330 }
2331 #endif /* __PAGETABLE_PMD_FOLDED */
2332
2333 int make_pages_present(unsigned long addr, unsigned long end)
2334 {
2335         int ret, len, write;
2336         struct vm_area_struct * vma;
2337
2338         vma = find_vma(current->mm, addr);
2339         if (!vma)
2340                 return -1;
2341         write = (vma->vm_flags & VM_WRITE) != 0;
2342         if (addr >= end)
2343                 BUG();
2344         if (end > vma->vm_end)
2345                 BUG();
2346         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2347         ret = get_user_pages(current, current->mm, addr,
2348                         len, write, 0, NULL, NULL);
2349         if (ret < 0)
2350                 return ret;
2351         return ret == len ? 0 : -1;
2352 }
2353
2354 /*
2355  * Map a vmalloc()-space virtual address to the physical page.
2356  */
2357 struct page * vmalloc_to_page(void * vmalloc_addr)
2358 {
2359         unsigned long addr = (unsigned long) vmalloc_addr;
2360         struct page *page = NULL;
2361         pgd_t *pgd = pgd_offset_k(addr);
2362         pud_t *pud;
2363         pmd_t *pmd;
2364         pte_t *ptep, pte;
2365
2366         if (!pgd_none(*pgd)) {
2367                 pud = pud_offset(pgd, addr);
2368                 if (!pud_none(*pud)) {
2369                         pmd = pmd_offset(pud, addr);
2370                         if (!pmd_none(*pmd)) {
2371                                 ptep = pte_offset_map(pmd, addr);
2372                                 pte = *ptep;
2373                                 if (pte_present(pte))
2374                                         page = pte_page(pte);
2375                                 pte_unmap(ptep);
2376                         }
2377                 }
2378         }
2379         return page;
2380 }
2381
2382 EXPORT_SYMBOL(vmalloc_to_page);
2383
2384 /*
2385  * Map a vmalloc()-space virtual address to the physical page frame number.
2386  */
2387 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2388 {
2389         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2390 }
2391
2392 EXPORT_SYMBOL(vmalloc_to_pfn);
2393
2394 #if !defined(__HAVE_ARCH_GATE_AREA)
2395
2396 #if defined(AT_SYSINFO_EHDR)
2397 static struct vm_area_struct gate_vma;
2398
2399 static int __init gate_vma_init(void)
2400 {
2401         gate_vma.vm_mm = NULL;
2402         gate_vma.vm_start = FIXADDR_USER_START;
2403         gate_vma.vm_end = FIXADDR_USER_END;
2404         gate_vma.vm_page_prot = PAGE_READONLY;
2405         gate_vma.vm_flags = 0;
2406         return 0;
2407 }
2408 __initcall(gate_vma_init);
2409 #endif
2410
2411 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2412 {
2413 #ifdef AT_SYSINFO_EHDR
2414         return &gate_vma;
2415 #else
2416         return NULL;
2417 #endif
2418 }
2419
2420 int in_gate_area_no_task(unsigned long addr)
2421 {
2422 #ifdef AT_SYSINFO_EHDR
2423         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2424                 return 1;
2425 #endif
2426         return 0;
2427 }
2428
2429 #endif  /* __HAVE_ARCH_GATE_AREA */