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