mm/nommu.c

   1 /*
   2  *  linux/mm/nommu.c
   3  *
   4  *  Replacement code for mm functions to support CPU's that don't
   5  *  have any form of memory management unit (thus no virtual memory).
   6  *
   7  *  See Documentation/nommu-mmap.txt
   8  *
   9  *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  10  *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  11  *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  12  *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  13  *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  14  */
  15
  16 #include <linux/export.h>
  17 #include <linux/mm.h>
  18 #include <linux/mman.h>
  19 #include <linux/swap.h>
  20 #include <linux/file.h>
  21 #include <linux/highmem.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/slab.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mount.h>
  28 #include <linux/personality.h>
  29 #include <linux/security.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/audit.h>
  32
  33 #include <asm/uaccess.h>
  34 #include <asm/tlb.h>
  35 #include <asm/tlbflush.h>
  36 #include <asm/mmu_context.h>
  37 #include "internal.h"
  38
  39 #if 0
  40 #define kenter(FMT, ...) \
  41         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  42 #define kleave(FMT, ...) \
  43         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  44 #define kdebug(FMT, ...) \
  45         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
  46 #else
  47 #define kenter(FMT, ...) \
  48         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  49 #define kleave(FMT, ...) \
  50         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  51 #define kdebug(FMT, ...) \
  52         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
  53 #endif
  54
  55 void *high_memory;
  56 struct page *mem_map;
  57 unsigned long max_mapnr;
  58 unsigned long num_physpages;
  59 unsigned long highest_memmap_pfn;
  60 struct percpu_counter vm_committed_as;
  61 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  62 int sysctl_overcommit_ratio = 50; /* default is 50% */
  63 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  64 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  65 int heap_stack_gap = 0;
  66
  67 atomic_long_t mmap_pages_allocated;
  68
  69 EXPORT_SYMBOL(mem_map);
  70 EXPORT_SYMBOL(num_physpages);
  71
  72 /* list of mapped, potentially shareable regions */
  73 static struct kmem_cache *vm_region_jar;
  74 struct rb_root nommu_region_tree = RB_ROOT;
  75 DECLARE_RWSEM(nommu_region_sem);
  76
  77 const struct vm_operations_struct generic_file_vm_ops = {
  78 };
  79
  80 /*
  81  * Return the total memory allocated for this pointer, not
  82  * just what the caller asked for.
  83  *
  84  * Doesn't have to be accurate, i.e. may have races.
  85  */
  86 unsigned int kobjsize(const void *objp)
  87 {
  88         struct page *page;
  89
  90         /*
  91          * If the object we have should not have ksize performed on it,
  92          * return size of 0
  93          */
  94         if (!objp || !virt_addr_valid(objp))
  95                 return 0;
  96
  97         page = virt_to_head_page(objp);
  98
  99         /*
 100          * If the allocator sets PageSlab, we know the pointer came from
 101          * kmalloc().
 102          */
 103         if (PageSlab(page))
 104                 return ksize(objp);
 105
 106         /*
 107          * If it's not a compound page, see if we have a matching VMA
 108          * region. This test is intentionally done in reverse order,
 109          * so if there's no VMA, we still fall through and hand back
 110          * PAGE_SIZE for 0-order pages.
 111          */
 112         if (!PageCompound(page)) {
 113                 struct vm_area_struct *vma;
 114
 115                 vma = find_vma(current->mm, (unsigned long)objp);
 116                 if (vma)
 117                         return vma->vm_end - vma->vm_start;
 118         }
 119
 120         /*
 121          * The ksize() function is only guaranteed to work for pointers
 122          * returned by kmalloc(). So handle arbitrary pointers here.
 123          */
 124         return PAGE_SIZE << compound_order(page);
 125 }
 126
 127 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 128                      unsigned long start, int nr_pages, unsigned int foll_flags,
 129                      struct page **pages, struct vm_area_struct **vmas,
 130                      int *retry)
 131 {
 132         struct vm_area_struct *vma;
 133         unsigned long vm_flags;
 134         int i;
 135
 136         /* calculate required read or write permissions.
 137          * If FOLL_FORCE is set, we only require the "MAY" flags.
 138          */
 139         vm_flags  = (foll_flags & FOLL_WRITE) ?
 140                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 141         vm_flags &= (foll_flags & FOLL_FORCE) ?
 142                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 143
 144         for (i = 0; i < nr_pages; i++) {
 145                 vma = find_vma(mm, start);
 146                 if (!vma)
 147                         goto finish_or_fault;
 148
 149                 /* protect what we can, including chardevs */
 150                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
 151                     !(vm_flags & vma->vm_flags))
 152                         goto finish_or_fault;
 153
 154                 if (pages) {
 155                         pages[i] = virt_to_page(start);
 156                         if (pages[i])
 157                                 page_cache_get(pages[i]);
 158                 }
 159                 if (vmas)
 160                         vmas[i] = vma;
 161                 start = (start + PAGE_SIZE) & PAGE_MASK;
 162         }
 163
 164         return i;
 165
 166 finish_or_fault:
 167         return i ? : -EFAULT;
 168 }
 169
 170 /*
 171  * get a list of pages in an address range belonging to the specified process
 172  * and indicate the VMA that covers each page
 173  * - this is potentially dodgy as we may end incrementing the page count of a
 174  *   slab page or a secondary page from a compound page
 175  * - don't permit access to VMAs that don't support it, such as I/O mappings
 176  */
 177 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 178         unsigned long start, int nr_pages, int write, int force,
 179         struct page **pages, struct vm_area_struct **vmas)
 180 {
 181         int flags = 0;
 182
 183         if (write)
 184                 flags |= FOLL_WRITE;
 185         if (force)
 186                 flags |= FOLL_FORCE;
 187
 188         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
 189                                 NULL);
 190 }
 191 EXPORT_SYMBOL(get_user_pages);
 192
 193 /**
 194  * follow_pfn - look up PFN at a user virtual address
 195  * @vma: memory mapping
 196  * @address: user virtual address
 197  * @pfn: location to store found PFN
 198  *
 199  * Only IO mappings and raw PFN mappings are allowed.
 200  *
 201  * Returns zero and the pfn at @pfn on success, -ve otherwise.
 202  */
 203 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 204         unsigned long *pfn)
 205 {
 206         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 207                 return -EINVAL;
 208
 209         *pfn = address >> PAGE_SHIFT;
 210         return 0;
 211 }
 212 EXPORT_SYMBOL(follow_pfn);
 213
 214 DEFINE_RWLOCK(vmlist_lock);
 215 struct vm_struct *vmlist;
 216
 217 void vfree(const void *addr)
 218 {
 219         kfree(addr);
 220 }
 221 EXPORT_SYMBOL(vfree);
 222
 223 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 224 {
 225         /*
 226          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 227          * returns only a logical address.
 228          */
 229         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 230 }
 231 EXPORT_SYMBOL(__vmalloc);
 232
 233 void *vmalloc_user(unsigned long size)
 234 {
 235         void *ret;
 236
 237         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 238                         PAGE_KERNEL);
 239         if (ret) {
 240                 struct vm_area_struct *vma;
 241
 242                 down_write(&current->mm->mmap_sem);
 243                 vma = find_vma(current->mm, (unsigned long)ret);
 244                 if (vma)
 245                         vma->vm_flags |= VM_USERMAP;
 246                 up_write(&current->mm->mmap_sem);
 247         }
 248
 249         return ret;
 250 }
 251 EXPORT_SYMBOL(vmalloc_user);
 252
 253 struct page *vmalloc_to_page(const void *addr)
 254 {
 255         return virt_to_page(addr);
 256 }
 257 EXPORT_SYMBOL(vmalloc_to_page);
 258
 259 unsigned long vmalloc_to_pfn(const void *addr)
 260 {
 261         return page_to_pfn(virt_to_page(addr));
 262 }
 263 EXPORT_SYMBOL(vmalloc_to_pfn);
 264
 265 long vread(char *buf, char *addr, unsigned long count)
 266 {
 267         memcpy(buf, addr, count);
 268         return count;
 269 }
 270
 271 long vwrite(char *buf, char *addr, unsigned long count)
 272 {
 273         /* Don't allow overflow */
 274         if ((unsigned long) addr + count < count)
 275                 count = -(unsigned long) addr;
 276
 277         memcpy(addr, buf, count);
 278         return(count);
 279 }
 280
 281 /*
 282  *      vmalloc  -  allocate virtually continguos memory
 283  *
 284  *      @size:          allocation size
 285  *
 286  *      Allocate enough pages to cover @size from the page level
 287  *      allocator and map them into continguos kernel virtual space.
 288  *
 289  *      For tight control over page level allocator and protection flags
 290  *      use __vmalloc() instead.
 291  */
 292 void *vmalloc(unsigned long size)
 293 {
 294        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 295 }
 296 EXPORT_SYMBOL(vmalloc);
 297
 298 /*
 299  *      vzalloc - allocate virtually continguos memory with zero fill
 300  *
 301  *      @size:          allocation size
 302  *
 303  *      Allocate enough pages to cover @size from the page level
 304  *      allocator and map them into continguos kernel virtual space.
 305  *      The memory allocated is set to zero.
 306  *
 307  *      For tight control over page level allocator and protection flags
 308  *      use __vmalloc() instead.
 309  */
 310 void *vzalloc(unsigned long size)
 311 {
 312         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 313                         PAGE_KERNEL);
 314 }
 315 EXPORT_SYMBOL(vzalloc);
 316
 317 /**
 318  * vmalloc_node - allocate memory on a specific node
 319  * @size:       allocation size
 320  * @node:       numa node
 321  *
 322  * Allocate enough pages to cover @size from the page level
 323  * allocator and map them into contiguous kernel virtual space.
 324  *
 325  * For tight control over page level allocator and protection flags
 326  * use __vmalloc() instead.
 327  */
 328 void *vmalloc_node(unsigned long size, int node)
 329 {
 330         return vmalloc(size);
 331 }
 332 EXPORT_SYMBOL(vmalloc_node);
 333
 334 /**
 335  * vzalloc_node - allocate memory on a specific node with zero fill
 336  * @size:       allocation size
 337  * @node:       numa node
 338  *
 339  * Allocate enough pages to cover @size from the page level
 340  * allocator and map them into contiguous kernel virtual space.
 341  * The memory allocated is set to zero.
 342  *
 343  * For tight control over page level allocator and protection flags
 344  * use __vmalloc() instead.
 345  */
 346 void *vzalloc_node(unsigned long size, int node)
 347 {
 348         return vzalloc(size);
 349 }
 350 EXPORT_SYMBOL(vzalloc_node);
 351
 352 #ifndef PAGE_KERNEL_EXEC
 353 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 354 #endif
 355
 356 /**
 357  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 358  *      @size:          allocation size
 359  *
 360  *      Kernel-internal function to allocate enough pages to cover @size
 361  *      the page level allocator and map them into contiguous and
 362  *      executable kernel virtual space.
 363  *
 364  *      For tight control over page level allocator and protection flags
 365  *      use __vmalloc() instead.
 366  */
 367
 368 void *vmalloc_exec(unsigned long size)
 369 {
 370         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 371 }
 372
 373 /**
 374  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 375  *      @size:          allocation size
 376  *
 377  *      Allocate enough 32bit PA addressable pages to cover @size from the
 378  *      page level allocator and map them into continguos kernel virtual space.
 379  */
 380 void *vmalloc_32(unsigned long size)
 381 {
 382         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 383 }
 384 EXPORT_SYMBOL(vmalloc_32);
 385
 386 /**
 387  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 388  *      @size:          allocation size
 389  *
 390  * The resulting memory area is 32bit addressable and zeroed so it can be
 391  * mapped to userspace without leaking data.
 392  *
 393  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 394  * remap_vmalloc_range() are permissible.
 395  */
 396 void *vmalloc_32_user(unsigned long size)
 397 {
 398         /*
 399          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 400          * but for now this can simply use vmalloc_user() directly.
 401          */
 402         return vmalloc_user(size);
 403 }
 404 EXPORT_SYMBOL(vmalloc_32_user);
 405
 406 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 407 {
 408         BUG();
 409         return NULL;
 410 }
 411 EXPORT_SYMBOL(vmap);
 412
 413 void vunmap(const void *addr)
 414 {
 415         BUG();
 416 }
 417 EXPORT_SYMBOL(vunmap);
 418
 419 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 420 {
 421         BUG();
 422         return NULL;
 423 }
 424 EXPORT_SYMBOL(vm_map_ram);
 425
 426 void vm_unmap_ram(const void *mem, unsigned int count)
 427 {
 428         BUG();
 429 }
 430 EXPORT_SYMBOL(vm_unmap_ram);
 431
 432 void vm_unmap_aliases(void)
 433 {
 434 }
 435 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 436
 437 /*
 438  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 439  * have one.
 440  */
 441 void  __attribute__((weak)) vmalloc_sync_all(void)
 442 {
 443 }
 444
 445 /**
 446  *      alloc_vm_area - allocate a range of kernel address space
 447  *      @size:          size of the area
 448  *
 449  *      Returns:        NULL on failure, vm_struct on success
 450  *
 451  *      This function reserves a range of kernel address space, and
 452  *      allocates pagetables to map that range.  No actual mappings
 453  *      are created.  If the kernel address space is not shared
 454  *      between processes, it syncs the pagetable across all
 455  *      processes.
 456  */
 457 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 458 {
 459         BUG();
 460         return NULL;
 461 }
 462 EXPORT_SYMBOL_GPL(alloc_vm_area);
 463
 464 void free_vm_area(struct vm_struct *area)
 465 {
 466         BUG();
 467 }
 468 EXPORT_SYMBOL_GPL(free_vm_area);
 469
 470 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 471                    struct page *page)
 472 {
 473         return -EINVAL;
 474 }
 475 EXPORT_SYMBOL(vm_insert_page);
 476
 477 /*
 478  *  sys_brk() for the most part doesn't need the global kernel
 479  *  lock, except when an application is doing something nasty
 480  *  like trying to un-brk an area that has already been mapped
 481  *  to a regular file.  in this case, the unmapping will need
 482  *  to invoke file system routines that need the global lock.
 483  */
 484 SYSCALL_DEFINE1(brk, unsigned long, brk)
 485 {
 486         struct mm_struct *mm = current->mm;
 487
 488         if (brk < mm->start_brk || brk > mm->context.end_brk)
 489                 return mm->brk;
 490
 491         if (mm->brk == brk)
 492                 return mm->brk;
 493
 494         /*
 495          * Always allow shrinking brk
 496          */
 497         if (brk <= mm->brk) {
 498                 mm->brk = brk;
 499                 return brk;
 500         }
 501
 502         /*
 503          * Ok, looks good - let it rip.
 504          */
 505         flush_icache_range(mm->brk, brk);
 506         return mm->brk = brk;
 507 }
 508
 509 /*
 510  * initialise the VMA and region record slabs
 511  */
 512 void __init mmap_init(void)
 513 {
 514         int ret;
 515
 516         ret = percpu_counter_init(&vm_committed_as, 0);
 517         VM_BUG_ON(ret);
 518         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
 519 }
 520
 521 /*
 522  * validate the region tree
 523  * - the caller must hold the region lock
 524  */
 525 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
 526 static noinline void validate_nommu_regions(void)
 527 {
 528         struct vm_region *region, *last;
 529         struct rb_node *p, *lastp;
 530
 531         lastp = rb_first(&nommu_region_tree);
 532         if (!lastp)
 533                 return;
 534
 535         last = rb_entry(lastp, struct vm_region, vm_rb);
 536         BUG_ON(unlikely(last->vm_end <= last->vm_start));
 537         BUG_ON(unlikely(last->vm_top < last->vm_end));
 538
 539         while ((p = rb_next(lastp))) {
 540                 region = rb_entry(p, struct vm_region, vm_rb);
 541                 last = rb_entry(lastp, struct vm_region, vm_rb);
 542
 543                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
 544                 BUG_ON(unlikely(region->vm_top < region->vm_end));
 545                 BUG_ON(unlikely(region->vm_start < last->vm_top));
 546
 547                 lastp = p;
 548         }
 549 }
 550 #else
 551 static void validate_nommu_regions(void)
 552 {
 553 }
 554 #endif
 555
 556 /*
 557  * add a region into the global tree
 558  */
 559 static void add_nommu_region(struct vm_region *region)
 560 {
 561         struct vm_region *pregion;
 562         struct rb_node **p, *parent;
 563
 564         validate_nommu_regions();
 565
 566         parent = NULL;
 567         p = &nommu_region_tree.rb_node;
 568         while (*p) {
 569                 parent = *p;
 570                 pregion = rb_entry(parent, struct vm_region, vm_rb);
 571                 if (region->vm_start < pregion->vm_start)
 572                         p = &(*p)->rb_left;
 573                 else if (region->vm_start > pregion->vm_start)
 574                         p = &(*p)->rb_right;
 575                 else if (pregion == region)
 576                         return;
 577                 else
 578                         BUG();
 579         }
 580
 581         rb_link_node(&region->vm_rb, parent, p);
 582         rb_insert_color(&region->vm_rb, &nommu_region_tree);
 583
 584         validate_nommu_regions();
 585 }
 586
 587 /*
 588  * delete a region from the global tree
 589  */
 590 static void delete_nommu_region(struct vm_region *region)
 591 {
 592         BUG_ON(!nommu_region_tree.rb_node);
 593
 594         validate_nommu_regions();
 595         rb_erase(&region->vm_rb, &nommu_region_tree);
 596         validate_nommu_regions();
 597 }
 598
 599 /*
 600  * free a contiguous series of pages
 601  */
 602 static void free_page_series(unsigned long from, unsigned long to)
 603 {
 604         for (; from < to; from += PAGE_SIZE) {
 605                 struct page *page = virt_to_page(from);
 606
 607                 kdebug("- free %lx", from);
 608                 atomic_long_dec(&mmap_pages_allocated);
 609                 if (page_count(page) != 1)
 610                         kdebug("free page %p: refcount not one: %d",
 611                                page, page_count(page));
 612                 put_page(page);
 613         }
 614 }
 615
 616 /*
 617  * release a reference to a region
 618  * - the caller must hold the region semaphore for writing, which this releases
 619  * - the region may not have been added to the tree yet, in which case vm_top
 620  *   will equal vm_start
 621  */
 622 static void __put_nommu_region(struct vm_region *region)
 623         __releases(nommu_region_sem)
 624 {
 625         kenter("%p{%d}", region, region->vm_usage);
 626
 627         BUG_ON(!nommu_region_tree.rb_node);
 628
 629         if (--region->vm_usage == 0) {
 630                 if (region->vm_top > region->vm_start)
 631                         delete_nommu_region(region);
 632                 up_write(&nommu_region_sem);
 633
 634                 if (region->vm_file)
 635                         fput(region->vm_file);
 636
 637                 /* IO memory and memory shared directly out of the pagecache
 638                  * from ramfs/tmpfs mustn't be released here */
 639                 if (region->vm_flags & VM_MAPPED_COPY) {
 640                         kdebug("free series");
 641                         free_page_series(region->vm_start, region->vm_top);
 642                 }
 643                 kmem_cache_free(vm_region_jar, region);
 644         } else {
 645                 up_write(&nommu_region_sem);
 646         }
 647 }
 648
 649 /*
 650  * release a reference to a region
 651  */
 652 static void put_nommu_region(struct vm_region *region)
 653 {
 654         down_write(&nommu_region_sem);
 655         __put_nommu_region(region);
 656 }
 657
 658 /*
 659  * update protection on a vma
 660  */
 661 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
 662 {
 663 #ifdef CONFIG_MPU
 664         struct mm_struct *mm = vma->vm_mm;
 665         long start = vma->vm_start & PAGE_MASK;
 666         while (start < vma->vm_end) {
 667                 protect_page(mm, start, flags);
 668                 start += PAGE_SIZE;
 669         }
 670         update_protections(mm);
 671 #endif
 672 }
 673
 674 /*
 675  * add a VMA into a process's mm_struct in the appropriate place in the list
 676  * and tree and add to the address space's page tree also if not an anonymous
 677  * page
 678  * - should be called with mm->mmap_sem held writelocked
 679  */
 680 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 681 {
 682         struct vm_area_struct *pvma, *prev;
 683         struct address_space *mapping;
 684         struct rb_node **p, *parent, *rb_prev;
 685
 686         kenter(",%p", vma);
 687
 688         BUG_ON(!vma->vm_region);
 689
 690         mm->map_count++;
 691         vma->vm_mm = mm;
 692
 693         protect_vma(vma, vma->vm_flags);
 694
 695         /* add the VMA to the mapping */
 696         if (vma->vm_file) {
 697                 mapping = vma->vm_file->f_mapping;
 698
 699                 mutex_lock(&mapping->i_mmap_mutex);
 700                 flush_dcache_mmap_lock(mapping);
 701                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 702                 flush_dcache_mmap_unlock(mapping);
 703                 mutex_unlock(&mapping->i_mmap_mutex);
 704         }
 705
 706         /* add the VMA to the tree */
 707         parent = rb_prev = NULL;
 708         p = &mm->mm_rb.rb_node;
 709         while (*p) {
 710                 parent = *p;
 711                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 712
 713                 /* sort by: start addr, end addr, VMA struct addr in that order
 714                  * (the latter is necessary as we may get identical VMAs) */
 715                 if (vma->vm_start < pvma->vm_start)
 716                         p = &(*p)->rb_left;
 717                 else if (vma->vm_start > pvma->vm_start) {
 718                         rb_prev = parent;
 719                         p = &(*p)->rb_right;
 720                 } else if (vma->vm_end < pvma->vm_end)
 721                         p = &(*p)->rb_left;
 722                 else if (vma->vm_end > pvma->vm_end) {
 723                         rb_prev = parent;
 724                         p = &(*p)->rb_right;
 725                 } else if (vma < pvma)
 726                         p = &(*p)->rb_left;
 727                 else if (vma > pvma) {
 728                         rb_prev = parent;
 729                         p = &(*p)->rb_right;
 730                 } else
 731                         BUG();
 732         }
 733
 734         rb_link_node(&vma->vm_rb, parent, p);
 735         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 736
 737         /* add VMA to the VMA list also */
 738         prev = NULL;
 739         if (rb_prev)
 740                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 741
 742         __vma_link_list(mm, vma, prev, parent);
 743 }
 744
 745 /*
 746  * delete a VMA from its owning mm_struct and address space
 747  */
 748 static void delete_vma_from_mm(struct vm_area_struct *vma)
 749 {
 750         struct address_space *mapping;
 751         struct mm_struct *mm = vma->vm_mm;
 752
 753         kenter("%p", vma);
 754
 755         protect_vma(vma, 0);
 756
 757         mm->map_count--;
 758         if (mm->mmap_cache == vma)
 759                 mm->mmap_cache = NULL;
 760
 761         /* remove the VMA from the mapping */
 762         if (vma->vm_file) {
 763                 mapping = vma->vm_file->f_mapping;
 764
 765                 mutex_lock(&mapping->i_mmap_mutex);
 766                 flush_dcache_mmap_lock(mapping);
 767                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 768                 flush_dcache_mmap_unlock(mapping);
 769                 mutex_unlock(&mapping->i_mmap_mutex);
 770         }
 771
 772         /* remove from the MM's tree and list */
 773         rb_erase(&vma->vm_rb, &mm->mm_rb);
 774
 775         if (vma->vm_prev)
 776                 vma->vm_prev->vm_next = vma->vm_next;
 777         else
 778                 mm->mmap = vma->vm_next;
 779
 780         if (vma->vm_next)
 781                 vma->vm_next->vm_prev = vma->vm_prev;
 782 }
 783
 784 /*
 785  * destroy a VMA record
 786  */
 787 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 788 {
 789         kenter("%p", vma);
 790         if (vma->vm_ops && vma->vm_ops->close)
 791                 vma->vm_ops->close(vma);
 792         if (vma->vm_file) {
 793                 fput(vma->vm_file);
 794                 if (vma->vm_flags & VM_EXECUTABLE)
 795                         removed_exe_file_vma(mm);
 796         }
 797         put_nommu_region(vma->vm_region);
 798         kmem_cache_free(vm_area_cachep, vma);
 799 }
 800
 801 /*
 802  * look up the first VMA in which addr resides, NULL if none
 803  * - should be called with mm->mmap_sem at least held readlocked
 804  */
 805 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 806 {
 807         struct vm_area_struct *vma;
 808
 809         /* check the cache first */
 810         vma = mm->mmap_cache;
 811         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
 812                 return vma;
 813
 814         /* trawl the list (there may be multiple mappings in which addr
 815          * resides) */
 816         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 817                 if (vma->vm_start > addr)
 818                         return NULL;
 819                 if (vma->vm_end > addr) {
 820                         mm->mmap_cache = vma;
 821                         return vma;
 822                 }
 823         }
 824
 825         return NULL;
 826 }
 827 EXPORT_SYMBOL(find_vma);
 828
 829 /*
 830  * find a VMA
 831  * - we don't extend stack VMAs under NOMMU conditions
 832  */
 833 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 834 {
 835         return find_vma(mm, addr);
 836 }
 837
 838 /*
 839  * expand a stack to a given address
 840  * - not supported under NOMMU conditions
 841  */
 842 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 843 {
 844         return -ENOMEM;
 845 }
 846
 847 /*
 848  * look up the first VMA exactly that exactly matches addr
 849  * - should be called with mm->mmap_sem at least held readlocked
 850  */
 851 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 852                                              unsigned long addr,
 853                                              unsigned long len)
 854 {
 855         struct vm_area_struct *vma;
 856         unsigned long end = addr + len;
 857
 858         /* check the cache first */
 859         vma = mm->mmap_cache;
 860         if (vma && vma->vm_start == addr && vma->vm_end == end)
 861                 return vma;
 862
 863         /* trawl the list (there may be multiple mappings in which addr
 864          * resides) */
 865         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 866                 if (vma->vm_start < addr)
 867                         continue;
 868                 if (vma->vm_start > addr)
 869                         return NULL;
 870                 if (vma->vm_end == end) {
 871                         mm->mmap_cache = vma;
 872                         return vma;
 873                 }
 874         }
 875
 876         return NULL;
 877 }
 878
 879 /*
 880  * determine whether a mapping should be permitted and, if so, what sort of
 881  * mapping we're capable of supporting
 882  */
 883 static int validate_mmap_request(struct file *file,
 884                                  unsigned long addr,
 885                                  unsigned long len,
 886                                  unsigned long prot,
 887                                  unsigned long flags,
 888                                  unsigned long pgoff,
 889                                  unsigned long *_capabilities)
 890 {
 891         unsigned long capabilities, rlen;
 892         int ret;
 893
 894         /* do the simple checks first */
 895         if (flags & MAP_FIXED) {
 896                 printk(KERN_DEBUG
 897                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 898                        current->pid);
 899                 return -EINVAL;
 900         }
 901
 902         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 903             (flags & MAP_TYPE) != MAP_SHARED)
 904                 return -EINVAL;
 905
 906         if (!len)
 907                 return -EINVAL;
 908
 909         /* Careful about overflows.. */
 910         rlen = PAGE_ALIGN(len);
 911         if (!rlen || rlen > TASK_SIZE)
 912                 return -ENOMEM;
 913
 914         /* offset overflow? */
 915         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 916                 return -EOVERFLOW;
 917
 918         if (file) {
 919                 /* validate file mapping requests */
 920                 struct address_space *mapping;
 921
 922                 /* files must support mmap */
 923                 if (!file->f_op || !file->f_op->mmap)
 924                         return -ENODEV;
 925
 926                 /* work out if what we've got could possibly be shared
 927                  * - we support chardevs that provide their own "memory"
 928                  * - we support files/blockdevs that are memory backed
 929                  */
 930                 mapping = file->f_mapping;
 931                 if (!mapping)
 932                         mapping = file->f_path.dentry->d_inode->i_mapping;
 933
 934                 capabilities = 0;
 935                 if (mapping && mapping->backing_dev_info)
 936                         capabilities = mapping->backing_dev_info->capabilities;
 937
 938                 if (!capabilities) {
 939                         /* no explicit capabilities set, so assume some
 940                          * defaults */
 941                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 942                         case S_IFREG:
 943                         case S_IFBLK:
 944                                 capabilities = BDI_CAP_MAP_COPY;
 945                                 break;
 946
 947                         case S_IFCHR:
 948                                 capabilities =
 949                                         BDI_CAP_MAP_DIRECT |
 950                                         BDI_CAP_READ_MAP |
 951                                         BDI_CAP_WRITE_MAP;
 952                                 break;
 953
 954                         default:
 955                                 return -EINVAL;
 956                         }
 957                 }
 958
 959                 /* eliminate any capabilities that we can't support on this
 960                  * device */
 961                 if (!file->f_op->get_unmapped_area)
 962                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 963                 if (!file->f_op->read)
 964                         capabilities &= ~BDI_CAP_MAP_COPY;
 965
 966                 /* The file shall have been opened with read permission. */
 967                 if (!(file->f_mode & FMODE_READ))
 968                         return -EACCES;
 969
 970                 if (flags & MAP_SHARED) {
 971                         /* do checks for writing, appending and locking */
 972                         if ((prot & PROT_WRITE) &&
 973                             !(file->f_mode & FMODE_WRITE))
 974                                 return -EACCES;
 975
 976                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 977                             (file->f_mode & FMODE_WRITE))
 978                                 return -EACCES;
 979
 980                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 981                                 return -EAGAIN;
 982
 983                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 984                                 return -ENODEV;
 985
 986                         /* we mustn't privatise shared mappings */
 987                         capabilities &= ~BDI_CAP_MAP_COPY;
 988                 }
 989                 else {
 990                         /* we're going to read the file into private memory we
 991                          * allocate */
 992                         if (!(capabilities & BDI_CAP_MAP_COPY))
 993                                 return -ENODEV;
 994
 995                         /* we don't permit a private writable mapping to be
 996                          * shared with the backing device */
 997                         if (prot & PROT_WRITE)
 998                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 999                 }
1000
1001                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1002                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1003                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1004                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1005                             ) {
1006                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1007                                 if (flags & MAP_SHARED) {
1008                                         printk(KERN_WARNING
1009                                                "MAP_SHARED not completely supported on !MMU\n");
1010                                         return -EINVAL;
1011                                 }
1012                         }
1013                 }
1014
1015                 /* handle executable mappings and implied executable
1016                  * mappings */
1017                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1018                         if (prot & PROT_EXEC)
1019                                 return -EPERM;
1020                 }
1021                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1022                         /* handle implication of PROT_EXEC by PROT_READ */
1023                         if (current->personality & READ_IMPLIES_EXEC) {
1024                                 if (capabilities & BDI_CAP_EXEC_MAP)
1025                                         prot |= PROT_EXEC;
1026                         }
1027                 }
1028                 else if ((prot & PROT_READ) &&
1029                          (prot & PROT_EXEC) &&
1030                          !(capabilities & BDI_CAP_EXEC_MAP)
1031                          ) {
1032                         /* backing file is not executable, try to copy */
1033                         capabilities &= ~BDI_CAP_MAP_DIRECT;
1034                 }
1035         }
1036         else {
1037                 /* anonymous mappings are always memory backed and can be
1038                  * privately mapped
1039                  */
1040                 capabilities = BDI_CAP_MAP_COPY;
1041
1042                 /* handle PROT_EXEC implication by PROT_READ */
1043                 if ((prot & PROT_READ) &&
1044                     (current->personality & READ_IMPLIES_EXEC))
1045                         prot |= PROT_EXEC;
1046         }
1047
1048         /* allow the security API to have its say */
1049         ret = security_mmap_addr(addr);
1050         if (ret < 0)
1051                 return ret;
1052
1053         /* looks okay */
1054         *_capabilities = capabilities;
1055         return 0;
1056 }
1057
1058 /*
1059  * we've determined that we can make the mapping, now translate what we
1060  * now know into VMA flags
1061  */
1062 static unsigned long determine_vm_flags(struct file *file,
1063                                         unsigned long prot,
1064                                         unsigned long flags,
1065                                         unsigned long capabilities)
1066 {
1067         unsigned long vm_flags;
1068
1069         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1070         /* vm_flags |= mm->def_flags; */
1071
1072         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1073                 /* attempt to share read-only copies of mapped file chunks */
1074                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1075                 if (file && !(prot & PROT_WRITE))
1076                         vm_flags |= VM_MAYSHARE;
1077         } else {
1078                 /* overlay a shareable mapping on the backing device or inode
1079                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1080                  * romfs/cramfs */
1081                 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1082                 if (flags & MAP_SHARED)
1083                         vm_flags |= VM_SHARED;
1084         }
1085
1086         /* refuse to let anyone share private mappings with this process if
1087          * it's being traced - otherwise breakpoints set in it may interfere
1088          * with another untraced process
1089          */
1090         if ((flags & MAP_PRIVATE) && current->ptrace)
1091                 vm_flags &= ~VM_MAYSHARE;
1092
1093         return vm_flags;
1094 }
1095
1096 /*
1097  * set up a shared mapping on a file (the driver or filesystem provides and
1098  * pins the storage)
1099  */
1100 static int do_mmap_shared_file(struct vm_area_struct *vma)
1101 {
1102         int ret;
1103
1104         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1105         if (ret == 0) {
1106                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1107                 return 0;
1108         }
1109         if (ret != -ENOSYS)
1110                 return ret;
1111
1112         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1113          * opposed to tried but failed) so we can only give a suitable error as
1114          * it's not possible to make a private copy if MAP_SHARED was given */
1115         return -ENODEV;
1116 }
1117
1118 /*
1119  * set up a private mapping or an anonymous shared mapping
1120  */
1121 static int do_mmap_private(struct vm_area_struct *vma,
1122                            struct vm_region *region,
1123                            unsigned long len,
1124                            unsigned long capabilities)
1125 {
1126         struct page *pages;
1127         unsigned long total, point, n;
1128         void *base;
1129         int ret, order;
1130
1131         /* invoke the file's mapping function so that it can keep track of
1132          * shared mappings on devices or memory
1133          * - VM_MAYSHARE will be set if it may attempt to share
1134          */
1135         if (capabilities & BDI_CAP_MAP_DIRECT) {
1136                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1137                 if (ret == 0) {
1138                         /* shouldn't return success if we're not sharing */
1139                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1140                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1141                         return 0;
1142                 }
1143                 if (ret != -ENOSYS)
1144                         return ret;
1145
1146                 /* getting an ENOSYS error indicates that direct mmap isn't
1147                  * possible (as opposed to tried but failed) so we'll try to
1148                  * make a private copy of the data and map that instead */
1149         }
1150
1151
1152         /* allocate some memory to hold the mapping
1153          * - note that this may not return a page-aligned address if the object
1154          *   we're allocating is smaller than a page
1155          */
1156         order = get_order(len);
1157         kdebug("alloc order %d for %lx", order, len);
1158
1159         pages = alloc_pages(GFP_KERNEL, order);
1160         if (!pages)
1161                 goto enomem;
1162
1163         total = 1 << order;
1164         atomic_long_add(total, &mmap_pages_allocated);
1165
1166         point = len >> PAGE_SHIFT;
1167
1168         /* we allocated a power-of-2 sized page set, so we may want to trim off
1169          * the excess */
1170         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1171                 while (total > point) {
1172                         order = ilog2(total - point);
1173                         n = 1 << order;
1174                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1175                         atomic_long_sub(n, &mmap_pages_allocated);
1176                         total -= n;
1177                         set_page_refcounted(pages + total);
1178                         __free_pages(pages + total, order);
1179                 }
1180         }
1181
1182         for (point = 1; point < total; point++)
1183                 set_page_refcounted(&pages[point]);
1184
1185         base = page_address(pages);
1186         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1187         region->vm_start = (unsigned long) base;
1188         region->vm_end   = region->vm_start + len;
1189         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1190
1191         vma->vm_start = region->vm_start;
1192         vma->vm_end   = region->vm_start + len;
1193
1194         if (vma->vm_file) {
1195                 /* read the contents of a file into the copy */
1196                 mm_segment_t old_fs;
1197                 loff_t fpos;
1198
1199                 fpos = vma->vm_pgoff;
1200                 fpos <<= PAGE_SHIFT;
1201
1202                 old_fs = get_fs();
1203                 set_fs(KERNEL_DS);
1204                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1205                 set_fs(old_fs);
1206
1207                 if (ret < 0)
1208                         goto error_free;
1209
1210                 /* clear the last little bit */
1211                 if (ret < len)
1212                         memset(base + ret, 0, len - ret);
1213
1214         }
1215
1216         return 0;
1217
1218 error_free:
1219         free_page_series(region->vm_start, region->vm_top);
1220         region->vm_start = vma->vm_start = 0;
1221         region->vm_end   = vma->vm_end = 0;
1222         region->vm_top   = 0;
1223         return ret;
1224
1225 enomem:
1226         printk("Allocation of length %lu from process %d (%s) failed\n",
1227                len, current->pid, current->comm);
1228         show_free_areas(0);
1229         return -ENOMEM;
1230 }
1231
1232 /*
1233  * handle mapping creation for uClinux
1234  */
1235 unsigned long do_mmap_pgoff(struct file *file,
1236                             unsigned long addr,
1237                             unsigned long len,
1238                             unsigned long prot,
1239                             unsigned long flags,
1240                             unsigned long pgoff)
1241 {
1242         struct vm_area_struct *vma;
1243         struct vm_region *region;
1244         struct rb_node *rb;
1245         unsigned long capabilities, vm_flags, result;
1246         int ret;
1247
1248         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1249
1250         /* decide whether we should attempt the mapping, and if so what sort of
1251          * mapping */
1252         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1253                                     &capabilities);
1254         if (ret < 0) {
1255                 kleave(" = %d [val]", ret);
1256                 return ret;
1257         }
1258
1259         /* we ignore the address hint */
1260         addr = 0;
1261         len = PAGE_ALIGN(len);
1262
1263         /* we've determined that we can make the mapping, now translate what we
1264          * now know into VMA flags */
1265         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1266
1267         /* we're going to need to record the mapping */
1268         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1269         if (!region)
1270                 goto error_getting_region;
1271
1272         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1273         if (!vma)
1274                 goto error_getting_vma;
1275
1276         region->vm_usage = 1;
1277         region->vm_flags = vm_flags;
1278         region->vm_pgoff = pgoff;
1279
1280         INIT_LIST_HEAD(&vma->anon_vma_chain);
1281         vma->vm_flags = vm_flags;
1282         vma->vm_pgoff = pgoff;
1283
1284         if (file) {
1285                 region->vm_file = file;
1286                 get_file(file);
1287                 vma->vm_file = file;
1288                 get_file(file);
1289                 if (vm_flags & VM_EXECUTABLE) {
1290                         added_exe_file_vma(current->mm);
1291                         vma->vm_mm = current->mm;
1292                 }
1293         }
1294
1295         down_write(&nommu_region_sem);
1296
1297         /* if we want to share, we need to check for regions created by other
1298          * mmap() calls that overlap with our proposed mapping
1299          * - we can only share with a superset match on most regular files
1300          * - shared mappings on character devices and memory backed files are
1301          *   permitted to overlap inexactly as far as we are concerned for in
1302          *   these cases, sharing is handled in the driver or filesystem rather
1303          *   than here
1304          */
1305         if (vm_flags & VM_MAYSHARE) {
1306                 struct vm_region *pregion;
1307                 unsigned long pglen, rpglen, pgend, rpgend, start;
1308
1309                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1310                 pgend = pgoff + pglen;
1311
1312                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1313                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1314
1315                         if (!(pregion->vm_flags & VM_MAYSHARE))
1316                                 continue;
1317
1318                         /* search for overlapping mappings on the same file */
1319                         if (pregion->vm_file->f_path.dentry->d_inode !=
1320                             file->f_path.dentry->d_inode)
1321                                 continue;
1322
1323                         if (pregion->vm_pgoff >= pgend)
1324                                 continue;
1325
1326                         rpglen = pregion->vm_end - pregion->vm_start;
1327                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1328                         rpgend = pregion->vm_pgoff + rpglen;
1329                         if (pgoff >= rpgend)
1330                                 continue;
1331
1332                         /* handle inexactly overlapping matches between
1333                          * mappings */
1334                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1335                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1336                                 /* new mapping is not a subset of the region */
1337                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1338                                         goto sharing_violation;
1339                                 continue;
1340                         }
1341
1342                         /* we've found a region we can share */
1343                         pregion->vm_usage++;
1344                         vma->vm_region = pregion;
1345                         start = pregion->vm_start;
1346                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1347                         vma->vm_start = start;
1348                         vma->vm_end = start + len;
1349
1350                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1351                                 kdebug("share copy");
1352                                 vma->vm_flags |= VM_MAPPED_COPY;
1353                         } else {
1354                                 kdebug("share mmap");
1355                                 ret = do_mmap_shared_file(vma);
1356                                 if (ret < 0) {
1357                                         vma->vm_region = NULL;
1358                                         vma->vm_start = 0;
1359                                         vma->vm_end = 0;
1360                                         pregion->vm_usage--;
1361                                         pregion = NULL;
1362                                         goto error_just_free;
1363                                 }
1364                         }
1365                         fput(region->vm_file);
1366                         kmem_cache_free(vm_region_jar, region);
1367                         region = pregion;
1368                         result = start;
1369                         goto share;
1370                 }
1371
1372                 /* obtain the address at which to make a shared mapping
1373                  * - this is the hook for quasi-memory character devices to
1374                  *   tell us the location of a shared mapping
1375                  */
1376                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1377                         addr = file->f_op->get_unmapped_area(file, addr, len,
1378                                                              pgoff, flags);
1379                         if (IS_ERR_VALUE(addr)) {
1380                                 ret = addr;
1381                                 if (ret != -ENOSYS)
1382                                         goto error_just_free;
1383
1384                                 /* the driver refused to tell us where to site
1385                                  * the mapping so we'll have to attempt to copy
1386                                  * it */
1387                                 ret = -ENODEV;
1388                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1389                                         goto error_just_free;
1390
1391                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1392                         } else {
1393                                 vma->vm_start = region->vm_start = addr;
1394                                 vma->vm_end = region->vm_end = addr + len;
1395                         }
1396                 }
1397         }
1398
1399         vma->vm_region = region;
1400
1401         /* set up the mapping
1402          * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1403          */
1404         if (file && vma->vm_flags & VM_SHARED)
1405                 ret = do_mmap_shared_file(vma);
1406         else
1407                 ret = do_mmap_private(vma, region, len, capabilities);
1408         if (ret < 0)
1409                 goto error_just_free;
1410         add_nommu_region(region);
1411
1412         /* clear anonymous mappings that don't ask for uninitialized data */
1413         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1414                 memset((void *)region->vm_start, 0,
1415                        region->vm_end - region->vm_start);
1416
1417         /* okay... we have a mapping; now we have to register it */
1418         result = vma->vm_start;
1419
1420         current->mm->total_vm += len >> PAGE_SHIFT;
1421
1422 share:
1423         add_vma_to_mm(current->mm, vma);
1424
1425         /* we flush the region from the icache only when the first executable
1426          * mapping of it is made  */
1427         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1428                 flush_icache_range(region->vm_start, region->vm_end);
1429                 region->vm_icache_flushed = true;
1430         }
1431
1432         up_write(&nommu_region_sem);
1433
1434         kleave(" = %lx", result);
1435         return result;
1436
1437 error_just_free:
1438         up_write(&nommu_region_sem);
1439 error:
1440         if (region->vm_file)
1441                 fput(region->vm_file);
1442         kmem_cache_free(vm_region_jar, region);
1443         if (vma->vm_file)
1444                 fput(vma->vm_file);
1445         if (vma->vm_flags & VM_EXECUTABLE)
1446                 removed_exe_file_vma(vma->vm_mm);
1447         kmem_cache_free(vm_area_cachep, vma);
1448         kleave(" = %d", ret);
1449         return ret;
1450
1451 sharing_violation:
1452         up_write(&nommu_region_sem);
1453         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1454         ret = -EINVAL;
1455         goto error;
1456
1457 error_getting_vma:
1458         kmem_cache_free(vm_region_jar, region);
1459         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1460                " from process %d failed\n",
1461                len, current->pid);
1462         show_free_areas(0);
1463         return -ENOMEM;
1464
1465 error_getting_region:
1466         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1467                " from process %d failed\n",
1468                len, current->pid);
1469         show_free_areas(0);
1470         return -ENOMEM;
1471 }
1472
1473 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1474                 unsigned long, prot, unsigned long, flags,
1475                 unsigned long, fd, unsigned long, pgoff)
1476 {
1477         struct file *file = NULL;
1478         unsigned long retval = -EBADF;
1479
1480         audit_mmap_fd(fd, flags);
1481         if (!(flags & MAP_ANONYMOUS)) {
1482                 file = fget(fd);
1483                 if (!file)
1484                         goto out;
1485         }
1486
1487         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1488
1489         ret = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1490
1491         if (file)
1492                 fput(file);
1493 out:
1494         return retval;
1495 }
1496
1497 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1498 struct mmap_arg_struct {
1499         unsigned long addr;
1500         unsigned long len;
1501         unsigned long prot;
1502         unsigned long flags;
1503         unsigned long fd;
1504         unsigned long offset;
1505 };
1506
1507 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1508 {
1509         struct mmap_arg_struct a;
1510
1511         if (copy_from_user(&a, arg, sizeof(a)))
1512                 return -EFAULT;
1513         if (a.offset & ~PAGE_MASK)
1514                 return -EINVAL;
1515
1516         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1517                               a.offset >> PAGE_SHIFT);
1518 }
1519 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1520
1521 /*
1522  * split a vma into two pieces at address 'addr', a new vma is allocated either
1523  * for the first part or the tail.
1524  */
1525 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1526               unsigned long addr, int new_below)
1527 {
1528         struct vm_area_struct *new;
1529         struct vm_region *region;
1530         unsigned long npages;
1531
1532         kenter("");
1533
1534         /* we're only permitted to split anonymous regions (these should have
1535          * only a single usage on the region) */
1536         if (vma->vm_file)
1537                 return -ENOMEM;
1538
1539         if (mm->map_count >= sysctl_max_map_count)
1540                 return -ENOMEM;
1541
1542         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1543         if (!region)
1544                 return -ENOMEM;
1545
1546         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1547         if (!new) {
1548                 kmem_cache_free(vm_region_jar, region);
1549                 return -ENOMEM;
1550         }
1551
1552         /* most fields are the same, copy all, and then fixup */
1553         *new = *vma;
1554         *region = *vma->vm_region;
1555         new->vm_region = region;
1556
1557         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1558
1559         if (new_below) {
1560                 region->vm_top = region->vm_end = new->vm_end = addr;
1561         } else {
1562                 region->vm_start = new->vm_start = addr;
1563                 region->vm_pgoff = new->vm_pgoff += npages;
1564         }
1565
1566         if (new->vm_ops && new->vm_ops->open)
1567                 new->vm_ops->open(new);
1568
1569         delete_vma_from_mm(vma);
1570         down_write(&nommu_region_sem);
1571         delete_nommu_region(vma->vm_region);
1572         if (new_below) {
1573                 vma->vm_region->vm_start = vma->vm_start = addr;
1574                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1575         } else {
1576                 vma->vm_region->vm_end = vma->vm_end = addr;
1577                 vma->vm_region->vm_top = addr;
1578         }
1579         add_nommu_region(vma->vm_region);
1580         add_nommu_region(new->vm_region);
1581         up_write(&nommu_region_sem);
1582         add_vma_to_mm(mm, vma);
1583         add_vma_to_mm(mm, new);
1584         return 0;
1585 }
1586
1587 /*
1588  * shrink a VMA by removing the specified chunk from either the beginning or
1589  * the end
1590  */
1591 static int shrink_vma(struct mm_struct *mm,
1592                       struct vm_area_struct *vma,
1593                       unsigned long from, unsigned long to)
1594 {
1595         struct vm_region *region;
1596
1597         kenter("");
1598
1599         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1600          * and list */
1601         delete_vma_from_mm(vma);
1602         if (from > vma->vm_start)
1603                 vma->vm_end = from;
1604         else
1605                 vma->vm_start = to;
1606         add_vma_to_mm(mm, vma);
1607
1608         /* cut the backing region down to size */
1609         region = vma->vm_region;
1610         BUG_ON(region->vm_usage != 1);
1611
1612         down_write(&nommu_region_sem);
1613         delete_nommu_region(region);
1614         if (from > region->vm_start) {
1615                 to = region->vm_top;
1616                 region->vm_top = region->vm_end = from;
1617         } else {
1618                 region->vm_start = to;
1619         }
1620         add_nommu_region(region);
1621         up_write(&nommu_region_sem);
1622
1623         free_page_series(from, to);
1624         return 0;
1625 }
1626
1627 /*
1628  * release a mapping
1629  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1630  *   VMA, though it need not cover the whole VMA
1631  */
1632 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1633 {
1634         struct vm_area_struct *vma;
1635         unsigned long end;
1636         int ret;
1637
1638         kenter(",%lx,%zx", start, len);
1639
1640         len = PAGE_ALIGN(len);
1641         if (len == 0)
1642                 return -EINVAL;
1643
1644         end = start + len;
1645
1646         /* find the first potentially overlapping VMA */
1647         vma = find_vma(mm, start);
1648         if (!vma) {
1649                 static int limit = 0;
1650                 if (limit < 5) {
1651                         printk(KERN_WARNING
1652                                "munmap of memory not mmapped by process %d"
1653                                " (%s): 0x%lx-0x%lx\n",
1654                                current->pid, current->comm,
1655                                start, start + len - 1);
1656                         limit++;
1657                 }
1658                 return -EINVAL;
1659         }
1660
1661         /* we're allowed to split an anonymous VMA but not a file-backed one */
1662         if (vma->vm_file) {
1663                 do {
1664                         if (start > vma->vm_start) {
1665                                 kleave(" = -EINVAL [miss]");
1666                                 return -EINVAL;
1667                         }
1668                         if (end == vma->vm_end)
1669                                 goto erase_whole_vma;
1670                         vma = vma->vm_next;
1671                 } while (vma);
1672                 kleave(" = -EINVAL [split file]");
1673                 return -EINVAL;
1674         } else {
1675                 /* the chunk must be a subset of the VMA found */
1676                 if (start == vma->vm_start && end == vma->vm_end)
1677                         goto erase_whole_vma;
1678                 if (start < vma->vm_start || end > vma->vm_end) {
1679                         kleave(" = -EINVAL [superset]");
1680                         return -EINVAL;
1681                 }
1682                 if (start & ~PAGE_MASK) {
1683                         kleave(" = -EINVAL [unaligned start]");
1684                         return -EINVAL;
1685                 }
1686                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1687                         kleave(" = -EINVAL [unaligned split]");
1688                         return -EINVAL;
1689                 }
1690                 if (start != vma->vm_start && end != vma->vm_end) {
1691                         ret = split_vma(mm, vma, start, 1);
1692                         if (ret < 0) {
1693                                 kleave(" = %d [split]", ret);
1694                                 return ret;
1695                         }
1696                 }
1697                 return shrink_vma(mm, vma, start, end);
1698         }
1699
1700 erase_whole_vma:
1701         delete_vma_from_mm(vma);
1702         delete_vma(mm, vma);
1703         kleave(" = 0");
1704         return 0;
1705 }
1706 EXPORT_SYMBOL(do_munmap);
1707
1708 int vm_munmap(unsigned long addr, size_t len)
1709 {
1710         struct mm_struct *mm = current->mm;
1711         int ret;
1712
1713         down_write(&mm->mmap_sem);
1714         ret = do_munmap(mm, addr, len);
1715         up_write(&mm->mmap_sem);
1716         return ret;
1717 }
1718 EXPORT_SYMBOL(vm_munmap);
1719
1720 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1721 {
1722         return vm_munmap(addr, len);
1723 }
1724
1725 /*
1726  * release all the mappings made in a process's VM space
1727  */
1728 void exit_mmap(struct mm_struct *mm)
1729 {
1730         struct vm_area_struct *vma;
1731
1732         if (!mm)
1733                 return;
1734
1735         kenter("");
1736
1737         mm->total_vm = 0;
1738
1739         while ((vma = mm->mmap)) {
1740                 mm->mmap = vma->vm_next;
1741                 delete_vma_from_mm(vma);
1742                 delete_vma(mm, vma);
1743                 cond_resched();
1744         }
1745
1746         kleave("");
1747 }
1748
1749 unsigned long vm_brk(unsigned long addr, unsigned long len)
1750 {
1751         return -ENOMEM;
1752 }
1753
1754 /*
1755  * expand (or shrink) an existing mapping, potentially moving it at the same
1756  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1757  *
1758  * under NOMMU conditions, we only permit changing a mapping's size, and only
1759  * as long as it stays within the region allocated by do_mmap_private() and the
1760  * block is not shareable
1761  *
1762  * MREMAP_FIXED is not supported under NOMMU conditions
1763  */
1764 unsigned long do_mremap(unsigned long addr,
1765                         unsigned long old_len, unsigned long new_len,
1766                         unsigned long flags, unsigned long new_addr)
1767 {
1768         struct vm_area_struct *vma;
1769
1770         /* insanity checks first */
1771         old_len = PAGE_ALIGN(old_len);
1772         new_len = PAGE_ALIGN(new_len);
1773         if (old_len == 0 || new_len == 0)
1774                 return (unsigned long) -EINVAL;
1775
1776         if (addr & ~PAGE_MASK)
1777                 return -EINVAL;
1778
1779         if (flags & MREMAP_FIXED && new_addr != addr)
1780                 return (unsigned long) -EINVAL;
1781
1782         vma = find_vma_exact(current->mm, addr, old_len);
1783         if (!vma)
1784                 return (unsigned long) -EINVAL;
1785
1786         if (vma->vm_end != vma->vm_start + old_len)
1787                 return (unsigned long) -EFAULT;
1788
1789         if (vma->vm_flags & VM_MAYSHARE)
1790                 return (unsigned long) -EPERM;
1791
1792         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1793                 return (unsigned long) -ENOMEM;
1794
1795         /* all checks complete - do it */
1796         vma->vm_end = vma->vm_start + new_len;
1797         return vma->vm_start;
1798 }
1799 EXPORT_SYMBOL(do_mremap);
1800
1801 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1802                 unsigned long, new_len, unsigned long, flags,
1803                 unsigned long, new_addr)
1804 {
1805         unsigned long ret;
1806
1807         down_write(&current->mm->mmap_sem);
1808         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1809         up_write(&current->mm->mmap_sem);
1810         return ret;
1811 }
1812
1813 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1814                         unsigned int foll_flags)
1815 {
1816         return NULL;
1817 }
1818
1819 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1820                 unsigned long pfn, unsigned long size, pgprot_t prot)
1821 {
1822         if (addr != (pfn << PAGE_SHIFT))
1823                 return -EINVAL;
1824
1825         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1826         return 0;
1827 }
1828 EXPORT_SYMBOL(remap_pfn_range);
1829
1830 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1831                         unsigned long pgoff)
1832 {
1833         unsigned int size = vma->vm_end - vma->vm_start;
1834
1835         if (!(vma->vm_flags & VM_USERMAP))
1836                 return -EINVAL;
1837
1838         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1839         vma->vm_end = vma->vm_start + size;
1840
1841         return 0;
1842 }
1843 EXPORT_SYMBOL(remap_vmalloc_range);
1844
1845 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1846         unsigned long len, unsigned long pgoff, unsigned long flags)
1847 {
1848         return -ENOMEM;
1849 }
1850
1851 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1852 {
1853 }
1854
1855 void unmap_mapping_range(struct address_space *mapping,
1856                          loff_t const holebegin, loff_t const holelen,
1857                          int even_cows)
1858 {
1859 }
1860 EXPORT_SYMBOL(unmap_mapping_range);
1861
1862 /*
1863  * Check that a process has enough memory to allocate a new virtual
1864  * mapping. 0 means there is enough memory for the allocation to
1865  * succeed and -ENOMEM implies there is not.
1866  *
1867  * We currently support three overcommit policies, which are set via the
1868  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1869  *
1870  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1871  * Additional code 2002 Jul 20 by Robert Love.
1872  *
1873  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1874  *
1875  * Note this is a helper function intended to be used by LSMs which
1876  * wish to use this logic.
1877  */
1878 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1879 {
1880         unsigned long free, allowed;
1881
1882         vm_acct_memory(pages);
1883
1884         /*
1885          * Sometimes we want to use more memory than we have
1886          */
1887         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1888                 return 0;
1889
1890         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1891                 free = global_page_state(NR_FREE_PAGES);
1892                 free += global_page_state(NR_FILE_PAGES);
1893
1894                 /*
1895                  * shmem pages shouldn't be counted as free in this
1896                  * case, they can't be purged, only swapped out, and
1897                  * that won't affect the overall amount of available
1898                  * memory in the system.
1899                  */
1900                 free -= global_page_state(NR_SHMEM);
1901
1902                 free += nr_swap_pages;
1903
1904                 /*
1905                  * Any slabs which are created with the
1906                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1907                  * which are reclaimable, under pressure.  The dentry
1908                  * cache and most inode caches should fall into this
1909                  */
1910                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1911
1912                 /*
1913                  * Leave reserved pages. The pages are not for anonymous pages.
1914                  */
1915                 if (free <= totalreserve_pages)
1916                         goto error;
1917                 else
1918                         free -= totalreserve_pages;
1919
1920                 /*
1921                  * Leave the last 3% for root
1922                  */
1923                 if (!cap_sys_admin)
1924                         free -= free / 32;
1925
1926                 if (free > pages)
1927                         return 0;
1928
1929                 goto error;
1930         }
1931
1932         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1933         /*
1934          * Leave the last 3% for root
1935          */
1936         if (!cap_sys_admin)
1937                 allowed -= allowed / 32;
1938         allowed += total_swap_pages;
1939
1940         /* Don't let a single process grow too big:
1941            leave 3% of the size of this process for other processes */
1942         if (mm)
1943                 allowed -= mm->total_vm / 32;
1944
1945         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1946                 return 0;
1947
1948 error:
1949         vm_unacct_memory(pages);
1950
1951         return -ENOMEM;
1952 }
1953
1954 int in_gate_area_no_mm(unsigned long addr)
1955 {
1956         return 0;
1957 }
1958
1959 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1960 {
1961         BUG();
1962         return 0;
1963 }
1964 EXPORT_SYMBOL(filemap_fault);
1965
1966 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1967                 unsigned long addr, void *buf, int len, int write)
1968 {
1969         struct vm_area_struct *vma;
1970
1971         down_read(&mm->mmap_sem);
1972
1973         /* the access must start within one of the target process's mappings */
1974         vma = find_vma(mm, addr);
1975         if (vma) {
1976                 /* don't overrun this mapping */
1977                 if (addr + len >= vma->vm_end)
1978                         len = vma->vm_end - addr;
1979
1980                 /* only read or write mappings where it is permitted */
1981                 if (write && vma->vm_flags & VM_MAYWRITE)
1982                         copy_to_user_page(vma, NULL, addr,
1983                                          (void *) addr, buf, len);
1984                 else if (!write && vma->vm_flags & VM_MAYREAD)
1985                         copy_from_user_page(vma, NULL, addr,
1986                                             buf, (void *) addr, len);
1987                 else
1988                         len = 0;
1989         } else {
1990                 len = 0;
1991         }
1992
1993         up_read(&mm->mmap_sem);
1994
1995         return len;
1996 }
1997
1998 /**
1999  * @access_remote_vm - access another process' address space
2000  * @mm:         the mm_struct of the target address space
2001  * @addr:       start address to access
2002  * @buf:        source or destination buffer
2003  * @len:        number of bytes to transfer
2004  * @write:      whether the access is a write
2005  *
2006  * The caller must hold a reference on @mm.
2007  */
2008 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2009                 void *buf, int len, int write)
2010 {
2011         return __access_remote_vm(NULL, mm, addr, buf, len, write);
2012 }
2013
2014 /*
2015  * Access another process' address space.
2016  * - source/target buffer must be kernel space
2017  */
2018 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2019 {
2020         struct mm_struct *mm;
2021
2022         if (addr + len < addr)
2023                 return 0;
2024
2025         mm = get_task_mm(tsk);
2026         if (!mm)
2027                 return 0;
2028
2029         len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2030
2031         mmput(mm);
2032         return len;
2033 }
2034
2035 /**
2036  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2037  * @inode: The inode to check
2038  * @size: The current filesize of the inode
2039  * @newsize: The proposed filesize of the inode
2040  *
2041  * Check the shared mappings on an inode on behalf of a shrinking truncate to
2042  * make sure that that any outstanding VMAs aren't broken and then shrink the
2043  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2044  * automatically grant mappings that are too large.
2045  */
2046 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2047                                 size_t newsize)
2048 {
2049         struct vm_area_struct *vma;
2050         struct prio_tree_iter iter;
2051         struct vm_region *region;
2052         pgoff_t low, high;
2053         size_t r_size, r_top;
2054
2055         low = newsize >> PAGE_SHIFT;
2056         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2057
2058         down_write(&nommu_region_sem);
2059         mutex_lock(&inode->i_mapping->i_mmap_mutex);
2060
2061         /* search for VMAs that fall within the dead zone */
2062         vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2063                               low, high) {
2064                 /* found one - only interested if it's shared out of the page
2065                  * cache */
2066                 if (vma->vm_flags & VM_SHARED) {
2067                         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2068                         up_write(&nommu_region_sem);
2069                         return -ETXTBSY; /* not quite true, but near enough */
2070                 }
2071         }
2072
2073         /* reduce any regions that overlap the dead zone - if in existence,
2074          * these will be pointed to by VMAs that don't overlap the dead zone
2075          *
2076          * we don't check for any regions that start beyond the EOF as there
2077          * shouldn't be any
2078          */
2079         vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2080                               0, ULONG_MAX) {
2081                 if (!(vma->vm_flags & VM_SHARED))
2082                         continue;
2083
2084                 region = vma->vm_region;
2085                 r_size = region->vm_top - region->vm_start;
2086                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2087
2088                 if (r_top > newsize) {
2089                         region->vm_top -= r_top - newsize;
2090                         if (region->vm_end > region->vm_top)
2091                                 region->vm_end = region->vm_top;
2092                 }
2093         }
2094
2095         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2096         up_write(&nommu_region_sem);
2097         return 0;
2098 }