Merge branch 'akpm' (incoming from Andrew)
[linux-3.10.git] / 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 #include <linux/sched/sysctl.h>
33
34 #include <asm/uaccess.h>
35 #include <asm/tlb.h>
36 #include <asm/tlbflush.h>
37 #include <asm/mmu_context.h>
38 #include "internal.h"
39
40 #if 0
41 #define kenter(FMT, ...) \
42         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
43 #define kleave(FMT, ...) \
44         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
45 #define kdebug(FMT, ...) \
46         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
47 #else
48 #define kenter(FMT, ...) \
49         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
50 #define kleave(FMT, ...) \
51         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
52 #define kdebug(FMT, ...) \
53         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
54 #endif
55
56 void *high_memory;
57 struct page *mem_map;
58 unsigned long max_mapnr;
59 unsigned long num_physpages;
60 unsigned long highest_memmap_pfn;
61 struct percpu_counter vm_committed_as;
62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
63 int sysctl_overcommit_ratio = 50; /* default is 50% */
64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
65 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
66 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
67 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
68 int heap_stack_gap = 0;
69
70 atomic_long_t mmap_pages_allocated;
71
72 /*
73  * The global memory commitment made in the system can be a metric
74  * that can be used to drive ballooning decisions when Linux is hosted
75  * as a guest. On Hyper-V, the host implements a policy engine for dynamically
76  * balancing memory across competing virtual machines that are hosted.
77  * Several metrics drive this policy engine including the guest reported
78  * memory commitment.
79  */
80 unsigned long vm_memory_committed(void)
81 {
82         return percpu_counter_read_positive(&vm_committed_as);
83 }
84
85 EXPORT_SYMBOL_GPL(vm_memory_committed);
86
87 EXPORT_SYMBOL(mem_map);
88 EXPORT_SYMBOL(num_physpages);
89
90 /* list of mapped, potentially shareable regions */
91 static struct kmem_cache *vm_region_jar;
92 struct rb_root nommu_region_tree = RB_ROOT;
93 DECLARE_RWSEM(nommu_region_sem);
94
95 const struct vm_operations_struct generic_file_vm_ops = {
96 };
97
98 /*
99  * Return the total memory allocated for this pointer, not
100  * just what the caller asked for.
101  *
102  * Doesn't have to be accurate, i.e. may have races.
103  */
104 unsigned int kobjsize(const void *objp)
105 {
106         struct page *page;
107
108         /*
109          * If the object we have should not have ksize performed on it,
110          * return size of 0
111          */
112         if (!objp || !virt_addr_valid(objp))
113                 return 0;
114
115         page = virt_to_head_page(objp);
116
117         /*
118          * If the allocator sets PageSlab, we know the pointer came from
119          * kmalloc().
120          */
121         if (PageSlab(page))
122                 return ksize(objp);
123
124         /*
125          * If it's not a compound page, see if we have a matching VMA
126          * region. This test is intentionally done in reverse order,
127          * so if there's no VMA, we still fall through and hand back
128          * PAGE_SIZE for 0-order pages.
129          */
130         if (!PageCompound(page)) {
131                 struct vm_area_struct *vma;
132
133                 vma = find_vma(current->mm, (unsigned long)objp);
134                 if (vma)
135                         return vma->vm_end - vma->vm_start;
136         }
137
138         /*
139          * The ksize() function is only guaranteed to work for pointers
140          * returned by kmalloc(). So handle arbitrary pointers here.
141          */
142         return PAGE_SIZE << compound_order(page);
143 }
144
145 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
146                       unsigned long start, unsigned long nr_pages,
147                       unsigned int foll_flags, struct page **pages,
148                       struct vm_area_struct **vmas, int *nonblocking)
149 {
150         struct vm_area_struct *vma;
151         unsigned long vm_flags;
152         int i;
153
154         /* calculate required read or write permissions.
155          * If FOLL_FORCE is set, we only require the "MAY" flags.
156          */
157         vm_flags  = (foll_flags & FOLL_WRITE) ?
158                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
159         vm_flags &= (foll_flags & FOLL_FORCE) ?
160                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
161
162         for (i = 0; i < nr_pages; i++) {
163                 vma = find_vma(mm, start);
164                 if (!vma)
165                         goto finish_or_fault;
166
167                 /* protect what we can, including chardevs */
168                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
169                     !(vm_flags & vma->vm_flags))
170                         goto finish_or_fault;
171
172                 if (pages) {
173                         pages[i] = virt_to_page(start);
174                         if (pages[i])
175                                 page_cache_get(pages[i]);
176                 }
177                 if (vmas)
178                         vmas[i] = vma;
179                 start = (start + PAGE_SIZE) & PAGE_MASK;
180         }
181
182         return i;
183
184 finish_or_fault:
185         return i ? : -EFAULT;
186 }
187
188 /*
189  * get a list of pages in an address range belonging to the specified process
190  * and indicate the VMA that covers each page
191  * - this is potentially dodgy as we may end incrementing the page count of a
192  *   slab page or a secondary page from a compound page
193  * - don't permit access to VMAs that don't support it, such as I/O mappings
194  */
195 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
196                     unsigned long start, unsigned long nr_pages,
197                     int write, int force, struct page **pages,
198                     struct vm_area_struct **vmas)
199 {
200         int flags = 0;
201
202         if (write)
203                 flags |= FOLL_WRITE;
204         if (force)
205                 flags |= FOLL_FORCE;
206
207         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
208                                 NULL);
209 }
210 EXPORT_SYMBOL(get_user_pages);
211
212 /**
213  * follow_pfn - look up PFN at a user virtual address
214  * @vma: memory mapping
215  * @address: user virtual address
216  * @pfn: location to store found PFN
217  *
218  * Only IO mappings and raw PFN mappings are allowed.
219  *
220  * Returns zero and the pfn at @pfn on success, -ve otherwise.
221  */
222 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
223         unsigned long *pfn)
224 {
225         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
226                 return -EINVAL;
227
228         *pfn = address >> PAGE_SHIFT;
229         return 0;
230 }
231 EXPORT_SYMBOL(follow_pfn);
232
233 LIST_HEAD(vmap_area_list);
234
235 void vfree(const void *addr)
236 {
237         kfree(addr);
238 }
239 EXPORT_SYMBOL(vfree);
240
241 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
242 {
243         /*
244          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
245          * returns only a logical address.
246          */
247         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
248 }
249 EXPORT_SYMBOL(__vmalloc);
250
251 void *vmalloc_user(unsigned long size)
252 {
253         void *ret;
254
255         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
256                         PAGE_KERNEL);
257         if (ret) {
258                 struct vm_area_struct *vma;
259
260                 down_write(&current->mm->mmap_sem);
261                 vma = find_vma(current->mm, (unsigned long)ret);
262                 if (vma)
263                         vma->vm_flags |= VM_USERMAP;
264                 up_write(&current->mm->mmap_sem);
265         }
266
267         return ret;
268 }
269 EXPORT_SYMBOL(vmalloc_user);
270
271 struct page *vmalloc_to_page(const void *addr)
272 {
273         return virt_to_page(addr);
274 }
275 EXPORT_SYMBOL(vmalloc_to_page);
276
277 unsigned long vmalloc_to_pfn(const void *addr)
278 {
279         return page_to_pfn(virt_to_page(addr));
280 }
281 EXPORT_SYMBOL(vmalloc_to_pfn);
282
283 long vread(char *buf, char *addr, unsigned long count)
284 {
285         memcpy(buf, addr, count);
286         return count;
287 }
288
289 long vwrite(char *buf, char *addr, unsigned long count)
290 {
291         /* Don't allow overflow */
292         if ((unsigned long) addr + count < count)
293                 count = -(unsigned long) addr;
294
295         memcpy(addr, buf, count);
296         return(count);
297 }
298
299 /*
300  *      vmalloc  -  allocate virtually continguos memory
301  *
302  *      @size:          allocation size
303  *
304  *      Allocate enough pages to cover @size from the page level
305  *      allocator and map them into continguos kernel virtual space.
306  *
307  *      For tight control over page level allocator and protection flags
308  *      use __vmalloc() instead.
309  */
310 void *vmalloc(unsigned long size)
311 {
312        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
313 }
314 EXPORT_SYMBOL(vmalloc);
315
316 /*
317  *      vzalloc - allocate virtually continguos memory with zero fill
318  *
319  *      @size:          allocation size
320  *
321  *      Allocate enough pages to cover @size from the page level
322  *      allocator and map them into continguos kernel virtual space.
323  *      The memory allocated is set to zero.
324  *
325  *      For tight control over page level allocator and protection flags
326  *      use __vmalloc() instead.
327  */
328 void *vzalloc(unsigned long size)
329 {
330         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
331                         PAGE_KERNEL);
332 }
333 EXPORT_SYMBOL(vzalloc);
334
335 /**
336  * vmalloc_node - allocate memory on a specific node
337  * @size:       allocation size
338  * @node:       numa node
339  *
340  * Allocate enough pages to cover @size from the page level
341  * allocator and map them into contiguous kernel virtual space.
342  *
343  * For tight control over page level allocator and protection flags
344  * use __vmalloc() instead.
345  */
346 void *vmalloc_node(unsigned long size, int node)
347 {
348         return vmalloc(size);
349 }
350 EXPORT_SYMBOL(vmalloc_node);
351
352 /**
353  * vzalloc_node - allocate memory on a specific node with zero fill
354  * @size:       allocation size
355  * @node:       numa node
356  *
357  * Allocate enough pages to cover @size from the page level
358  * allocator and map them into contiguous kernel virtual space.
359  * The memory allocated is set to zero.
360  *
361  * For tight control over page level allocator and protection flags
362  * use __vmalloc() instead.
363  */
364 void *vzalloc_node(unsigned long size, int node)
365 {
366         return vzalloc(size);
367 }
368 EXPORT_SYMBOL(vzalloc_node);
369
370 #ifndef PAGE_KERNEL_EXEC
371 # define PAGE_KERNEL_EXEC PAGE_KERNEL
372 #endif
373
374 /**
375  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
376  *      @size:          allocation size
377  *
378  *      Kernel-internal function to allocate enough pages to cover @size
379  *      the page level allocator and map them into contiguous and
380  *      executable kernel virtual space.
381  *
382  *      For tight control over page level allocator and protection flags
383  *      use __vmalloc() instead.
384  */
385
386 void *vmalloc_exec(unsigned long size)
387 {
388         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
389 }
390
391 /**
392  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
393  *      @size:          allocation size
394  *
395  *      Allocate enough 32bit PA addressable pages to cover @size from the
396  *      page level allocator and map them into continguos kernel virtual space.
397  */
398 void *vmalloc_32(unsigned long size)
399 {
400         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
401 }
402 EXPORT_SYMBOL(vmalloc_32);
403
404 /**
405  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
406  *      @size:          allocation size
407  *
408  * The resulting memory area is 32bit addressable and zeroed so it can be
409  * mapped to userspace without leaking data.
410  *
411  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
412  * remap_vmalloc_range() are permissible.
413  */
414 void *vmalloc_32_user(unsigned long size)
415 {
416         /*
417          * We'll have to sort out the ZONE_DMA bits for 64-bit,
418          * but for now this can simply use vmalloc_user() directly.
419          */
420         return vmalloc_user(size);
421 }
422 EXPORT_SYMBOL(vmalloc_32_user);
423
424 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
425 {
426         BUG();
427         return NULL;
428 }
429 EXPORT_SYMBOL(vmap);
430
431 void vunmap(const void *addr)
432 {
433         BUG();
434 }
435 EXPORT_SYMBOL(vunmap);
436
437 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
438 {
439         BUG();
440         return NULL;
441 }
442 EXPORT_SYMBOL(vm_map_ram);
443
444 void vm_unmap_ram(const void *mem, unsigned int count)
445 {
446         BUG();
447 }
448 EXPORT_SYMBOL(vm_unmap_ram);
449
450 void vm_unmap_aliases(void)
451 {
452 }
453 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
454
455 /*
456  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
457  * have one.
458  */
459 void  __attribute__((weak)) vmalloc_sync_all(void)
460 {
461 }
462
463 /**
464  *      alloc_vm_area - allocate a range of kernel address space
465  *      @size:          size of the area
466  *
467  *      Returns:        NULL on failure, vm_struct on success
468  *
469  *      This function reserves a range of kernel address space, and
470  *      allocates pagetables to map that range.  No actual mappings
471  *      are created.  If the kernel address space is not shared
472  *      between processes, it syncs the pagetable across all
473  *      processes.
474  */
475 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
476 {
477         BUG();
478         return NULL;
479 }
480 EXPORT_SYMBOL_GPL(alloc_vm_area);
481
482 void free_vm_area(struct vm_struct *area)
483 {
484         BUG();
485 }
486 EXPORT_SYMBOL_GPL(free_vm_area);
487
488 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
489                    struct page *page)
490 {
491         return -EINVAL;
492 }
493 EXPORT_SYMBOL(vm_insert_page);
494
495 /*
496  *  sys_brk() for the most part doesn't need the global kernel
497  *  lock, except when an application is doing something nasty
498  *  like trying to un-brk an area that has already been mapped
499  *  to a regular file.  in this case, the unmapping will need
500  *  to invoke file system routines that need the global lock.
501  */
502 SYSCALL_DEFINE1(brk, unsigned long, brk)
503 {
504         struct mm_struct *mm = current->mm;
505
506         if (brk < mm->start_brk || brk > mm->context.end_brk)
507                 return mm->brk;
508
509         if (mm->brk == brk)
510                 return mm->brk;
511
512         /*
513          * Always allow shrinking brk
514          */
515         if (brk <= mm->brk) {
516                 mm->brk = brk;
517                 return brk;
518         }
519
520         /*
521          * Ok, looks good - let it rip.
522          */
523         flush_icache_range(mm->brk, brk);
524         return mm->brk = brk;
525 }
526
527 /*
528  * initialise the VMA and region record slabs
529  */
530 void __init mmap_init(void)
531 {
532         int ret;
533
534         ret = percpu_counter_init(&vm_committed_as, 0);
535         VM_BUG_ON(ret);
536         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
537 }
538
539 /*
540  * validate the region tree
541  * - the caller must hold the region lock
542  */
543 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
544 static noinline void validate_nommu_regions(void)
545 {
546         struct vm_region *region, *last;
547         struct rb_node *p, *lastp;
548
549         lastp = rb_first(&nommu_region_tree);
550         if (!lastp)
551                 return;
552
553         last = rb_entry(lastp, struct vm_region, vm_rb);
554         BUG_ON(unlikely(last->vm_end <= last->vm_start));
555         BUG_ON(unlikely(last->vm_top < last->vm_end));
556
557         while ((p = rb_next(lastp))) {
558                 region = rb_entry(p, struct vm_region, vm_rb);
559                 last = rb_entry(lastp, struct vm_region, vm_rb);
560
561                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
562                 BUG_ON(unlikely(region->vm_top < region->vm_end));
563                 BUG_ON(unlikely(region->vm_start < last->vm_top));
564
565                 lastp = p;
566         }
567 }
568 #else
569 static void validate_nommu_regions(void)
570 {
571 }
572 #endif
573
574 /*
575  * add a region into the global tree
576  */
577 static void add_nommu_region(struct vm_region *region)
578 {
579         struct vm_region *pregion;
580         struct rb_node **p, *parent;
581
582         validate_nommu_regions();
583
584         parent = NULL;
585         p = &nommu_region_tree.rb_node;
586         while (*p) {
587                 parent = *p;
588                 pregion = rb_entry(parent, struct vm_region, vm_rb);
589                 if (region->vm_start < pregion->vm_start)
590                         p = &(*p)->rb_left;
591                 else if (region->vm_start > pregion->vm_start)
592                         p = &(*p)->rb_right;
593                 else if (pregion == region)
594                         return;
595                 else
596                         BUG();
597         }
598
599         rb_link_node(&region->vm_rb, parent, p);
600         rb_insert_color(&region->vm_rb, &nommu_region_tree);
601
602         validate_nommu_regions();
603 }
604
605 /*
606  * delete a region from the global tree
607  */
608 static void delete_nommu_region(struct vm_region *region)
609 {
610         BUG_ON(!nommu_region_tree.rb_node);
611
612         validate_nommu_regions();
613         rb_erase(&region->vm_rb, &nommu_region_tree);
614         validate_nommu_regions();
615 }
616
617 /*
618  * free a contiguous series of pages
619  */
620 static void free_page_series(unsigned long from, unsigned long to)
621 {
622         for (; from < to; from += PAGE_SIZE) {
623                 struct page *page = virt_to_page(from);
624
625                 kdebug("- free %lx", from);
626                 atomic_long_dec(&mmap_pages_allocated);
627                 if (page_count(page) != 1)
628                         kdebug("free page %p: refcount not one: %d",
629                                page, page_count(page));
630                 put_page(page);
631         }
632 }
633
634 /*
635  * release a reference to a region
636  * - the caller must hold the region semaphore for writing, which this releases
637  * - the region may not have been added to the tree yet, in which case vm_top
638  *   will equal vm_start
639  */
640 static void __put_nommu_region(struct vm_region *region)
641         __releases(nommu_region_sem)
642 {
643         kenter("%p{%d}", region, region->vm_usage);
644
645         BUG_ON(!nommu_region_tree.rb_node);
646
647         if (--region->vm_usage == 0) {
648                 if (region->vm_top > region->vm_start)
649                         delete_nommu_region(region);
650                 up_write(&nommu_region_sem);
651
652                 if (region->vm_file)
653                         fput(region->vm_file);
654
655                 /* IO memory and memory shared directly out of the pagecache
656                  * from ramfs/tmpfs mustn't be released here */
657                 if (region->vm_flags & VM_MAPPED_COPY) {
658                         kdebug("free series");
659                         free_page_series(region->vm_start, region->vm_top);
660                 }
661                 kmem_cache_free(vm_region_jar, region);
662         } else {
663                 up_write(&nommu_region_sem);
664         }
665 }
666
667 /*
668  * release a reference to a region
669  */
670 static void put_nommu_region(struct vm_region *region)
671 {
672         down_write(&nommu_region_sem);
673         __put_nommu_region(region);
674 }
675
676 /*
677  * update protection on a vma
678  */
679 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
680 {
681 #ifdef CONFIG_MPU
682         struct mm_struct *mm = vma->vm_mm;
683         long start = vma->vm_start & PAGE_MASK;
684         while (start < vma->vm_end) {
685                 protect_page(mm, start, flags);
686                 start += PAGE_SIZE;
687         }
688         update_protections(mm);
689 #endif
690 }
691
692 /*
693  * add a VMA into a process's mm_struct in the appropriate place in the list
694  * and tree and add to the address space's page tree also if not an anonymous
695  * page
696  * - should be called with mm->mmap_sem held writelocked
697  */
698 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
699 {
700         struct vm_area_struct *pvma, *prev;
701         struct address_space *mapping;
702         struct rb_node **p, *parent, *rb_prev;
703
704         kenter(",%p", vma);
705
706         BUG_ON(!vma->vm_region);
707
708         mm->map_count++;
709         vma->vm_mm = mm;
710
711         protect_vma(vma, vma->vm_flags);
712
713         /* add the VMA to the mapping */
714         if (vma->vm_file) {
715                 mapping = vma->vm_file->f_mapping;
716
717                 mutex_lock(&mapping->i_mmap_mutex);
718                 flush_dcache_mmap_lock(mapping);
719                 vma_interval_tree_insert(vma, &mapping->i_mmap);
720                 flush_dcache_mmap_unlock(mapping);
721                 mutex_unlock(&mapping->i_mmap_mutex);
722         }
723
724         /* add the VMA to the tree */
725         parent = rb_prev = NULL;
726         p = &mm->mm_rb.rb_node;
727         while (*p) {
728                 parent = *p;
729                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
730
731                 /* sort by: start addr, end addr, VMA struct addr in that order
732                  * (the latter is necessary as we may get identical VMAs) */
733                 if (vma->vm_start < pvma->vm_start)
734                         p = &(*p)->rb_left;
735                 else if (vma->vm_start > pvma->vm_start) {
736                         rb_prev = parent;
737                         p = &(*p)->rb_right;
738                 } else if (vma->vm_end < pvma->vm_end)
739                         p = &(*p)->rb_left;
740                 else if (vma->vm_end > pvma->vm_end) {
741                         rb_prev = parent;
742                         p = &(*p)->rb_right;
743                 } else if (vma < pvma)
744                         p = &(*p)->rb_left;
745                 else if (vma > pvma) {
746                         rb_prev = parent;
747                         p = &(*p)->rb_right;
748                 } else
749                         BUG();
750         }
751
752         rb_link_node(&vma->vm_rb, parent, p);
753         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
754
755         /* add VMA to the VMA list also */
756         prev = NULL;
757         if (rb_prev)
758                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
759
760         __vma_link_list(mm, vma, prev, parent);
761 }
762
763 /*
764  * delete a VMA from its owning mm_struct and address space
765  */
766 static void delete_vma_from_mm(struct vm_area_struct *vma)
767 {
768         struct address_space *mapping;
769         struct mm_struct *mm = vma->vm_mm;
770
771         kenter("%p", vma);
772
773         protect_vma(vma, 0);
774
775         mm->map_count--;
776         if (mm->mmap_cache == vma)
777                 mm->mmap_cache = NULL;
778
779         /* remove the VMA from the mapping */
780         if (vma->vm_file) {
781                 mapping = vma->vm_file->f_mapping;
782
783                 mutex_lock(&mapping->i_mmap_mutex);
784                 flush_dcache_mmap_lock(mapping);
785                 vma_interval_tree_remove(vma, &mapping->i_mmap);
786                 flush_dcache_mmap_unlock(mapping);
787                 mutex_unlock(&mapping->i_mmap_mutex);
788         }
789
790         /* remove from the MM's tree and list */
791         rb_erase(&vma->vm_rb, &mm->mm_rb);
792
793         if (vma->vm_prev)
794                 vma->vm_prev->vm_next = vma->vm_next;
795         else
796                 mm->mmap = vma->vm_next;
797
798         if (vma->vm_next)
799                 vma->vm_next->vm_prev = vma->vm_prev;
800 }
801
802 /*
803  * destroy a VMA record
804  */
805 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
806 {
807         kenter("%p", vma);
808         if (vma->vm_ops && vma->vm_ops->close)
809                 vma->vm_ops->close(vma);
810         if (vma->vm_file)
811                 fput(vma->vm_file);
812         put_nommu_region(vma->vm_region);
813         kmem_cache_free(vm_area_cachep, vma);
814 }
815
816 /*
817  * look up the first VMA in which addr resides, NULL if none
818  * - should be called with mm->mmap_sem at least held readlocked
819  */
820 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
821 {
822         struct vm_area_struct *vma;
823
824         /* check the cache first */
825         vma = ACCESS_ONCE(mm->mmap_cache);
826         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
827                 return vma;
828
829         /* trawl the list (there may be multiple mappings in which addr
830          * resides) */
831         for (vma = mm->mmap; vma; vma = vma->vm_next) {
832                 if (vma->vm_start > addr)
833                         return NULL;
834                 if (vma->vm_end > addr) {
835                         mm->mmap_cache = vma;
836                         return vma;
837                 }
838         }
839
840         return NULL;
841 }
842 EXPORT_SYMBOL(find_vma);
843
844 /*
845  * find a VMA
846  * - we don't extend stack VMAs under NOMMU conditions
847  */
848 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
849 {
850         return find_vma(mm, addr);
851 }
852
853 /*
854  * expand a stack to a given address
855  * - not supported under NOMMU conditions
856  */
857 int expand_stack(struct vm_area_struct *vma, unsigned long address)
858 {
859         return -ENOMEM;
860 }
861
862 /*
863  * look up the first VMA exactly that exactly matches addr
864  * - should be called with mm->mmap_sem at least held readlocked
865  */
866 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
867                                              unsigned long addr,
868                                              unsigned long len)
869 {
870         struct vm_area_struct *vma;
871         unsigned long end = addr + len;
872
873         /* check the cache first */
874         vma = mm->mmap_cache;
875         if (vma && vma->vm_start == addr && vma->vm_end == end)
876                 return vma;
877
878         /* trawl the list (there may be multiple mappings in which addr
879          * resides) */
880         for (vma = mm->mmap; vma; vma = vma->vm_next) {
881                 if (vma->vm_start < addr)
882                         continue;
883                 if (vma->vm_start > addr)
884                         return NULL;
885                 if (vma->vm_end == end) {
886                         mm->mmap_cache = vma;
887                         return vma;
888                 }
889         }
890
891         return NULL;
892 }
893
894 /*
895  * determine whether a mapping should be permitted and, if so, what sort of
896  * mapping we're capable of supporting
897  */
898 static int validate_mmap_request(struct file *file,
899                                  unsigned long addr,
900                                  unsigned long len,
901                                  unsigned long prot,
902                                  unsigned long flags,
903                                  unsigned long pgoff,
904                                  unsigned long *_capabilities)
905 {
906         unsigned long capabilities, rlen;
907         int ret;
908
909         /* do the simple checks first */
910         if (flags & MAP_FIXED) {
911                 printk(KERN_DEBUG
912                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
913                        current->pid);
914                 return -EINVAL;
915         }
916
917         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
918             (flags & MAP_TYPE) != MAP_SHARED)
919                 return -EINVAL;
920
921         if (!len)
922                 return -EINVAL;
923
924         /* Careful about overflows.. */
925         rlen = PAGE_ALIGN(len);
926         if (!rlen || rlen > TASK_SIZE)
927                 return -ENOMEM;
928
929         /* offset overflow? */
930         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
931                 return -EOVERFLOW;
932
933         if (file) {
934                 /* validate file mapping requests */
935                 struct address_space *mapping;
936
937                 /* files must support mmap */
938                 if (!file->f_op || !file->f_op->mmap)
939                         return -ENODEV;
940
941                 /* work out if what we've got could possibly be shared
942                  * - we support chardevs that provide their own "memory"
943                  * - we support files/blockdevs that are memory backed
944                  */
945                 mapping = file->f_mapping;
946                 if (!mapping)
947                         mapping = file_inode(file)->i_mapping;
948
949                 capabilities = 0;
950                 if (mapping && mapping->backing_dev_info)
951                         capabilities = mapping->backing_dev_info->capabilities;
952
953                 if (!capabilities) {
954                         /* no explicit capabilities set, so assume some
955                          * defaults */
956                         switch (file_inode(file)->i_mode & S_IFMT) {
957                         case S_IFREG:
958                         case S_IFBLK:
959                                 capabilities = BDI_CAP_MAP_COPY;
960                                 break;
961
962                         case S_IFCHR:
963                                 capabilities =
964                                         BDI_CAP_MAP_DIRECT |
965                                         BDI_CAP_READ_MAP |
966                                         BDI_CAP_WRITE_MAP;
967                                 break;
968
969                         default:
970                                 return -EINVAL;
971                         }
972                 }
973
974                 /* eliminate any capabilities that we can't support on this
975                  * device */
976                 if (!file->f_op->get_unmapped_area)
977                         capabilities &= ~BDI_CAP_MAP_DIRECT;
978                 if (!file->f_op->read)
979                         capabilities &= ~BDI_CAP_MAP_COPY;
980
981                 /* The file shall have been opened with read permission. */
982                 if (!(file->f_mode & FMODE_READ))
983                         return -EACCES;
984
985                 if (flags & MAP_SHARED) {
986                         /* do checks for writing, appending and locking */
987                         if ((prot & PROT_WRITE) &&
988                             !(file->f_mode & FMODE_WRITE))
989                                 return -EACCES;
990
991                         if (IS_APPEND(file_inode(file)) &&
992                             (file->f_mode & FMODE_WRITE))
993                                 return -EACCES;
994
995                         if (locks_verify_locked(file_inode(file)))
996                                 return -EAGAIN;
997
998                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
999                                 return -ENODEV;
1000
1001                         /* we mustn't privatise shared mappings */
1002                         capabilities &= ~BDI_CAP_MAP_COPY;
1003                 }
1004                 else {
1005                         /* we're going to read the file into private memory we
1006                          * allocate */
1007                         if (!(capabilities & BDI_CAP_MAP_COPY))
1008                                 return -ENODEV;
1009
1010                         /* we don't permit a private writable mapping to be
1011                          * shared with the backing device */
1012                         if (prot & PROT_WRITE)
1013                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1014                 }
1015
1016                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1017                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1018                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1019                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1020                             ) {
1021                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1022                                 if (flags & MAP_SHARED) {
1023                                         printk(KERN_WARNING
1024                                                "MAP_SHARED not completely supported on !MMU\n");
1025                                         return -EINVAL;
1026                                 }
1027                         }
1028                 }
1029
1030                 /* handle executable mappings and implied executable
1031                  * mappings */
1032                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1033                         if (prot & PROT_EXEC)
1034                                 return -EPERM;
1035                 }
1036                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1037                         /* handle implication of PROT_EXEC by PROT_READ */
1038                         if (current->personality & READ_IMPLIES_EXEC) {
1039                                 if (capabilities & BDI_CAP_EXEC_MAP)
1040                                         prot |= PROT_EXEC;
1041                         }
1042                 }
1043                 else if ((prot & PROT_READ) &&
1044                          (prot & PROT_EXEC) &&
1045                          !(capabilities & BDI_CAP_EXEC_MAP)
1046                          ) {
1047                         /* backing file is not executable, try to copy */
1048                         capabilities &= ~BDI_CAP_MAP_DIRECT;
1049                 }
1050         }
1051         else {
1052                 /* anonymous mappings are always memory backed and can be
1053                  * privately mapped
1054                  */
1055                 capabilities = BDI_CAP_MAP_COPY;
1056
1057                 /* handle PROT_EXEC implication by PROT_READ */
1058                 if ((prot & PROT_READ) &&
1059                     (current->personality & READ_IMPLIES_EXEC))
1060                         prot |= PROT_EXEC;
1061         }
1062
1063         /* allow the security API to have its say */
1064         ret = security_mmap_addr(addr);
1065         if (ret < 0)
1066                 return ret;
1067
1068         /* looks okay */
1069         *_capabilities = capabilities;
1070         return 0;
1071 }
1072
1073 /*
1074  * we've determined that we can make the mapping, now translate what we
1075  * now know into VMA flags
1076  */
1077 static unsigned long determine_vm_flags(struct file *file,
1078                                         unsigned long prot,
1079                                         unsigned long flags,
1080                                         unsigned long capabilities)
1081 {
1082         unsigned long vm_flags;
1083
1084         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1085         /* vm_flags |= mm->def_flags; */
1086
1087         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1088                 /* attempt to share read-only copies of mapped file chunks */
1089                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1090                 if (file && !(prot & PROT_WRITE))
1091                         vm_flags |= VM_MAYSHARE;
1092         } else {
1093                 /* overlay a shareable mapping on the backing device or inode
1094                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1095                  * romfs/cramfs */
1096                 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1097                 if (flags & MAP_SHARED)
1098                         vm_flags |= VM_SHARED;
1099         }
1100
1101         /* refuse to let anyone share private mappings with this process if
1102          * it's being traced - otherwise breakpoints set in it may interfere
1103          * with another untraced process
1104          */
1105         if ((flags & MAP_PRIVATE) && current->ptrace)
1106                 vm_flags &= ~VM_MAYSHARE;
1107
1108         return vm_flags;
1109 }
1110
1111 /*
1112  * set up a shared mapping on a file (the driver or filesystem provides and
1113  * pins the storage)
1114  */
1115 static int do_mmap_shared_file(struct vm_area_struct *vma)
1116 {
1117         int ret;
1118
1119         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1120         if (ret == 0) {
1121                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1122                 return 0;
1123         }
1124         if (ret != -ENOSYS)
1125                 return ret;
1126
1127         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1128          * opposed to tried but failed) so we can only give a suitable error as
1129          * it's not possible to make a private copy if MAP_SHARED was given */
1130         return -ENODEV;
1131 }
1132
1133 /*
1134  * set up a private mapping or an anonymous shared mapping
1135  */
1136 static int do_mmap_private(struct vm_area_struct *vma,
1137                            struct vm_region *region,
1138                            unsigned long len,
1139                            unsigned long capabilities)
1140 {
1141         struct page *pages;
1142         unsigned long total, point, n;
1143         void *base;
1144         int ret, order;
1145
1146         /* invoke the file's mapping function so that it can keep track of
1147          * shared mappings on devices or memory
1148          * - VM_MAYSHARE will be set if it may attempt to share
1149          */
1150         if (capabilities & BDI_CAP_MAP_DIRECT) {
1151                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1152                 if (ret == 0) {
1153                         /* shouldn't return success if we're not sharing */
1154                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1155                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1156                         return 0;
1157                 }
1158                 if (ret != -ENOSYS)
1159                         return ret;
1160
1161                 /* getting an ENOSYS error indicates that direct mmap isn't
1162                  * possible (as opposed to tried but failed) so we'll try to
1163                  * make a private copy of the data and map that instead */
1164         }
1165
1166
1167         /* allocate some memory to hold the mapping
1168          * - note that this may not return a page-aligned address if the object
1169          *   we're allocating is smaller than a page
1170          */
1171         order = get_order(len);
1172         kdebug("alloc order %d for %lx", order, len);
1173
1174         pages = alloc_pages(GFP_KERNEL, order);
1175         if (!pages)
1176                 goto enomem;
1177
1178         total = 1 << order;
1179         atomic_long_add(total, &mmap_pages_allocated);
1180
1181         point = len >> PAGE_SHIFT;
1182
1183         /* we allocated a power-of-2 sized page set, so we may want to trim off
1184          * the excess */
1185         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1186                 while (total > point) {
1187                         order = ilog2(total - point);
1188                         n = 1 << order;
1189                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1190                         atomic_long_sub(n, &mmap_pages_allocated);
1191                         total -= n;
1192                         set_page_refcounted(pages + total);
1193                         __free_pages(pages + total, order);
1194                 }
1195         }
1196
1197         for (point = 1; point < total; point++)
1198                 set_page_refcounted(&pages[point]);
1199
1200         base = page_address(pages);
1201         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1202         region->vm_start = (unsigned long) base;
1203         region->vm_end   = region->vm_start + len;
1204         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1205
1206         vma->vm_start = region->vm_start;
1207         vma->vm_end   = region->vm_start + len;
1208
1209         if (vma->vm_file) {
1210                 /* read the contents of a file into the copy */
1211                 mm_segment_t old_fs;
1212                 loff_t fpos;
1213
1214                 fpos = vma->vm_pgoff;
1215                 fpos <<= PAGE_SHIFT;
1216
1217                 old_fs = get_fs();
1218                 set_fs(KERNEL_DS);
1219                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1220                 set_fs(old_fs);
1221
1222                 if (ret < 0)
1223                         goto error_free;
1224
1225                 /* clear the last little bit */
1226                 if (ret < len)
1227                         memset(base + ret, 0, len - ret);
1228
1229         }
1230
1231         return 0;
1232
1233 error_free:
1234         free_page_series(region->vm_start, region->vm_top);
1235         region->vm_start = vma->vm_start = 0;
1236         region->vm_end   = vma->vm_end = 0;
1237         region->vm_top   = 0;
1238         return ret;
1239
1240 enomem:
1241         printk("Allocation of length %lu from process %d (%s) failed\n",
1242                len, current->pid, current->comm);
1243         show_free_areas(0);
1244         return -ENOMEM;
1245 }
1246
1247 /*
1248  * handle mapping creation for uClinux
1249  */
1250 unsigned long do_mmap_pgoff(struct file *file,
1251                             unsigned long addr,
1252                             unsigned long len,
1253                             unsigned long prot,
1254                             unsigned long flags,
1255                             unsigned long pgoff,
1256                             unsigned long *populate)
1257 {
1258         struct vm_area_struct *vma;
1259         struct vm_region *region;
1260         struct rb_node *rb;
1261         unsigned long capabilities, vm_flags, result;
1262         int ret;
1263
1264         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1265
1266         *populate = 0;
1267
1268         /* decide whether we should attempt the mapping, and if so what sort of
1269          * mapping */
1270         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1271                                     &capabilities);
1272         if (ret < 0) {
1273                 kleave(" = %d [val]", ret);
1274                 return ret;
1275         }
1276
1277         /* we ignore the address hint */
1278         addr = 0;
1279         len = PAGE_ALIGN(len);
1280
1281         /* we've determined that we can make the mapping, now translate what we
1282          * now know into VMA flags */
1283         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1284
1285         /* we're going to need to record the mapping */
1286         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1287         if (!region)
1288                 goto error_getting_region;
1289
1290         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1291         if (!vma)
1292                 goto error_getting_vma;
1293
1294         region->vm_usage = 1;
1295         region->vm_flags = vm_flags;
1296         region->vm_pgoff = pgoff;
1297
1298         INIT_LIST_HEAD(&vma->anon_vma_chain);
1299         vma->vm_flags = vm_flags;
1300         vma->vm_pgoff = pgoff;
1301
1302         if (file) {
1303                 region->vm_file = get_file(file);
1304                 vma->vm_file = get_file(file);
1305         }
1306
1307         down_write(&nommu_region_sem);
1308
1309         /* if we want to share, we need to check for regions created by other
1310          * mmap() calls that overlap with our proposed mapping
1311          * - we can only share with a superset match on most regular files
1312          * - shared mappings on character devices and memory backed files are
1313          *   permitted to overlap inexactly as far as we are concerned for in
1314          *   these cases, sharing is handled in the driver or filesystem rather
1315          *   than here
1316          */
1317         if (vm_flags & VM_MAYSHARE) {
1318                 struct vm_region *pregion;
1319                 unsigned long pglen, rpglen, pgend, rpgend, start;
1320
1321                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1322                 pgend = pgoff + pglen;
1323
1324                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1325                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1326
1327                         if (!(pregion->vm_flags & VM_MAYSHARE))
1328                                 continue;
1329
1330                         /* search for overlapping mappings on the same file */
1331                         if (file_inode(pregion->vm_file) !=
1332                             file_inode(file))
1333                                 continue;
1334
1335                         if (pregion->vm_pgoff >= pgend)
1336                                 continue;
1337
1338                         rpglen = pregion->vm_end - pregion->vm_start;
1339                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1340                         rpgend = pregion->vm_pgoff + rpglen;
1341                         if (pgoff >= rpgend)
1342                                 continue;
1343
1344                         /* handle inexactly overlapping matches between
1345                          * mappings */
1346                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1347                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1348                                 /* new mapping is not a subset of the region */
1349                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1350                                         goto sharing_violation;
1351                                 continue;
1352                         }
1353
1354                         /* we've found a region we can share */
1355                         pregion->vm_usage++;
1356                         vma->vm_region = pregion;
1357                         start = pregion->vm_start;
1358                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1359                         vma->vm_start = start;
1360                         vma->vm_end = start + len;
1361
1362                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1363                                 kdebug("share copy");
1364                                 vma->vm_flags |= VM_MAPPED_COPY;
1365                         } else {
1366                                 kdebug("share mmap");
1367                                 ret = do_mmap_shared_file(vma);
1368                                 if (ret < 0) {
1369                                         vma->vm_region = NULL;
1370                                         vma->vm_start = 0;
1371                                         vma->vm_end = 0;
1372                                         pregion->vm_usage--;
1373                                         pregion = NULL;
1374                                         goto error_just_free;
1375                                 }
1376                         }
1377                         fput(region->vm_file);
1378                         kmem_cache_free(vm_region_jar, region);
1379                         region = pregion;
1380                         result = start;
1381                         goto share;
1382                 }
1383
1384                 /* obtain the address at which to make a shared mapping
1385                  * - this is the hook for quasi-memory character devices to
1386                  *   tell us the location of a shared mapping
1387                  */
1388                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1389                         addr = file->f_op->get_unmapped_area(file, addr, len,
1390                                                              pgoff, flags);
1391                         if (IS_ERR_VALUE(addr)) {
1392                                 ret = addr;
1393                                 if (ret != -ENOSYS)
1394                                         goto error_just_free;
1395
1396                                 /* the driver refused to tell us where to site
1397                                  * the mapping so we'll have to attempt to copy
1398                                  * it */
1399                                 ret = -ENODEV;
1400                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1401                                         goto error_just_free;
1402
1403                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1404                         } else {
1405                                 vma->vm_start = region->vm_start = addr;
1406                                 vma->vm_end = region->vm_end = addr + len;
1407                         }
1408                 }
1409         }
1410
1411         vma->vm_region = region;
1412
1413         /* set up the mapping
1414          * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1415          */
1416         if (file && vma->vm_flags & VM_SHARED)
1417                 ret = do_mmap_shared_file(vma);
1418         else
1419                 ret = do_mmap_private(vma, region, len, capabilities);
1420         if (ret < 0)
1421                 goto error_just_free;
1422         add_nommu_region(region);
1423
1424         /* clear anonymous mappings that don't ask for uninitialized data */
1425         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1426                 memset((void *)region->vm_start, 0,
1427                        region->vm_end - region->vm_start);
1428
1429         /* okay... we have a mapping; now we have to register it */
1430         result = vma->vm_start;
1431
1432         current->mm->total_vm += len >> PAGE_SHIFT;
1433
1434 share:
1435         add_vma_to_mm(current->mm, vma);
1436
1437         /* we flush the region from the icache only when the first executable
1438          * mapping of it is made  */
1439         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1440                 flush_icache_range(region->vm_start, region->vm_end);
1441                 region->vm_icache_flushed = true;
1442         }
1443
1444         up_write(&nommu_region_sem);
1445
1446         kleave(" = %lx", result);
1447         return result;
1448
1449 error_just_free:
1450         up_write(&nommu_region_sem);
1451 error:
1452         if (region->vm_file)
1453                 fput(region->vm_file);
1454         kmem_cache_free(vm_region_jar, region);
1455         if (vma->vm_file)
1456                 fput(vma->vm_file);
1457         kmem_cache_free(vm_area_cachep, vma);
1458         kleave(" = %d", ret);
1459         return ret;
1460
1461 sharing_violation:
1462         up_write(&nommu_region_sem);
1463         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1464         ret = -EINVAL;
1465         goto error;
1466
1467 error_getting_vma:
1468         kmem_cache_free(vm_region_jar, region);
1469         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1470                " from process %d failed\n",
1471                len, current->pid);
1472         show_free_areas(0);
1473         return -ENOMEM;
1474
1475 error_getting_region:
1476         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1477                " from process %d failed\n",
1478                len, current->pid);
1479         show_free_areas(0);
1480         return -ENOMEM;
1481 }
1482
1483 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1484                 unsigned long, prot, unsigned long, flags,
1485                 unsigned long, fd, unsigned long, pgoff)
1486 {
1487         struct file *file = NULL;
1488         unsigned long retval = -EBADF;
1489
1490         audit_mmap_fd(fd, flags);
1491         if (!(flags & MAP_ANONYMOUS)) {
1492                 file = fget(fd);
1493                 if (!file)
1494                         goto out;
1495         }
1496
1497         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1498
1499         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1500
1501         if (file)
1502                 fput(file);
1503 out:
1504         return retval;
1505 }
1506
1507 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1508 struct mmap_arg_struct {
1509         unsigned long addr;
1510         unsigned long len;
1511         unsigned long prot;
1512         unsigned long flags;
1513         unsigned long fd;
1514         unsigned long offset;
1515 };
1516
1517 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1518 {
1519         struct mmap_arg_struct a;
1520
1521         if (copy_from_user(&a, arg, sizeof(a)))
1522                 return -EFAULT;
1523         if (a.offset & ~PAGE_MASK)
1524                 return -EINVAL;
1525
1526         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1527                               a.offset >> PAGE_SHIFT);
1528 }
1529 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1530
1531 /*
1532  * split a vma into two pieces at address 'addr', a new vma is allocated either
1533  * for the first part or the tail.
1534  */
1535 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1536               unsigned long addr, int new_below)
1537 {
1538         struct vm_area_struct *new;
1539         struct vm_region *region;
1540         unsigned long npages;
1541
1542         kenter("");
1543
1544         /* we're only permitted to split anonymous regions (these should have
1545          * only a single usage on the region) */
1546         if (vma->vm_file)
1547                 return -ENOMEM;
1548
1549         if (mm->map_count >= sysctl_max_map_count)
1550                 return -ENOMEM;
1551
1552         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1553         if (!region)
1554                 return -ENOMEM;
1555
1556         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1557         if (!new) {
1558                 kmem_cache_free(vm_region_jar, region);
1559                 return -ENOMEM;
1560         }
1561
1562         /* most fields are the same, copy all, and then fixup */
1563         *new = *vma;
1564         *region = *vma->vm_region;
1565         new->vm_region = region;
1566
1567         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1568
1569         if (new_below) {
1570                 region->vm_top = region->vm_end = new->vm_end = addr;
1571         } else {
1572                 region->vm_start = new->vm_start = addr;
1573                 region->vm_pgoff = new->vm_pgoff += npages;
1574         }
1575
1576         if (new->vm_ops && new->vm_ops->open)
1577                 new->vm_ops->open(new);
1578
1579         delete_vma_from_mm(vma);
1580         down_write(&nommu_region_sem);
1581         delete_nommu_region(vma->vm_region);
1582         if (new_below) {
1583                 vma->vm_region->vm_start = vma->vm_start = addr;
1584                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1585         } else {
1586                 vma->vm_region->vm_end = vma->vm_end = addr;
1587                 vma->vm_region->vm_top = addr;
1588         }
1589         add_nommu_region(vma->vm_region);
1590         add_nommu_region(new->vm_region);
1591         up_write(&nommu_region_sem);
1592         add_vma_to_mm(mm, vma);
1593         add_vma_to_mm(mm, new);
1594         return 0;
1595 }
1596
1597 /*
1598  * shrink a VMA by removing the specified chunk from either the beginning or
1599  * the end
1600  */
1601 static int shrink_vma(struct mm_struct *mm,
1602                       struct vm_area_struct *vma,
1603                       unsigned long from, unsigned long to)
1604 {
1605         struct vm_region *region;
1606
1607         kenter("");
1608
1609         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1610          * and list */
1611         delete_vma_from_mm(vma);
1612         if (from > vma->vm_start)
1613                 vma->vm_end = from;
1614         else
1615                 vma->vm_start = to;
1616         add_vma_to_mm(mm, vma);
1617
1618         /* cut the backing region down to size */
1619         region = vma->vm_region;
1620         BUG_ON(region->vm_usage != 1);
1621
1622         down_write(&nommu_region_sem);
1623         delete_nommu_region(region);
1624         if (from > region->vm_start) {
1625                 to = region->vm_top;
1626                 region->vm_top = region->vm_end = from;
1627         } else {
1628                 region->vm_start = to;
1629         }
1630         add_nommu_region(region);
1631         up_write(&nommu_region_sem);
1632
1633         free_page_series(from, to);
1634         return 0;
1635 }
1636
1637 /*
1638  * release a mapping
1639  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1640  *   VMA, though it need not cover the whole VMA
1641  */
1642 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1643 {
1644         struct vm_area_struct *vma;
1645         unsigned long end;
1646         int ret;
1647
1648         kenter(",%lx,%zx", start, len);
1649
1650         len = PAGE_ALIGN(len);
1651         if (len == 0)
1652                 return -EINVAL;
1653
1654         end = start + len;
1655
1656         /* find the first potentially overlapping VMA */
1657         vma = find_vma(mm, start);
1658         if (!vma) {
1659                 static int limit = 0;
1660                 if (limit < 5) {
1661                         printk(KERN_WARNING
1662                                "munmap of memory not mmapped by process %d"
1663                                " (%s): 0x%lx-0x%lx\n",
1664                                current->pid, current->comm,
1665                                start, start + len - 1);
1666                         limit++;
1667                 }
1668                 return -EINVAL;
1669         }
1670
1671         /* we're allowed to split an anonymous VMA but not a file-backed one */
1672         if (vma->vm_file) {
1673                 do {
1674                         if (start > vma->vm_start) {
1675                                 kleave(" = -EINVAL [miss]");
1676                                 return -EINVAL;
1677                         }
1678                         if (end == vma->vm_end)
1679                                 goto erase_whole_vma;
1680                         vma = vma->vm_next;
1681                 } while (vma);
1682                 kleave(" = -EINVAL [split file]");
1683                 return -EINVAL;
1684         } else {
1685                 /* the chunk must be a subset of the VMA found */
1686                 if (start == vma->vm_start && end == vma->vm_end)
1687                         goto erase_whole_vma;
1688                 if (start < vma->vm_start || end > vma->vm_end) {
1689                         kleave(" = -EINVAL [superset]");
1690                         return -EINVAL;
1691                 }
1692                 if (start & ~PAGE_MASK) {
1693                         kleave(" = -EINVAL [unaligned start]");
1694                         return -EINVAL;
1695                 }
1696                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1697                         kleave(" = -EINVAL [unaligned split]");
1698                         return -EINVAL;
1699                 }
1700                 if (start != vma->vm_start && end != vma->vm_end) {
1701                         ret = split_vma(mm, vma, start, 1);
1702                         if (ret < 0) {
1703                                 kleave(" = %d [split]", ret);
1704                                 return ret;
1705                         }
1706                 }
1707                 return shrink_vma(mm, vma, start, end);
1708         }
1709
1710 erase_whole_vma:
1711         delete_vma_from_mm(vma);
1712         delete_vma(mm, vma);
1713         kleave(" = 0");
1714         return 0;
1715 }
1716 EXPORT_SYMBOL(do_munmap);
1717
1718 int vm_munmap(unsigned long addr, size_t len)
1719 {
1720         struct mm_struct *mm = current->mm;
1721         int ret;
1722
1723         down_write(&mm->mmap_sem);
1724         ret = do_munmap(mm, addr, len);
1725         up_write(&mm->mmap_sem);
1726         return ret;
1727 }
1728 EXPORT_SYMBOL(vm_munmap);
1729
1730 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1731 {
1732         return vm_munmap(addr, len);
1733 }
1734
1735 /*
1736  * release all the mappings made in a process's VM space
1737  */
1738 void exit_mmap(struct mm_struct *mm)
1739 {
1740         struct vm_area_struct *vma;
1741
1742         if (!mm)
1743                 return;
1744
1745         kenter("");
1746
1747         mm->total_vm = 0;
1748
1749         while ((vma = mm->mmap)) {
1750                 mm->mmap = vma->vm_next;
1751                 delete_vma_from_mm(vma);
1752                 delete_vma(mm, vma);
1753                 cond_resched();
1754         }
1755
1756         kleave("");
1757 }
1758
1759 unsigned long vm_brk(unsigned long addr, unsigned long len)
1760 {
1761         return -ENOMEM;
1762 }
1763
1764 /*
1765  * expand (or shrink) an existing mapping, potentially moving it at the same
1766  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1767  *
1768  * under NOMMU conditions, we only permit changing a mapping's size, and only
1769  * as long as it stays within the region allocated by do_mmap_private() and the
1770  * block is not shareable
1771  *
1772  * MREMAP_FIXED is not supported under NOMMU conditions
1773  */
1774 unsigned long do_mremap(unsigned long addr,
1775                         unsigned long old_len, unsigned long new_len,
1776                         unsigned long flags, unsigned long new_addr)
1777 {
1778         struct vm_area_struct *vma;
1779
1780         /* insanity checks first */
1781         old_len = PAGE_ALIGN(old_len);
1782         new_len = PAGE_ALIGN(new_len);
1783         if (old_len == 0 || new_len == 0)
1784                 return (unsigned long) -EINVAL;
1785
1786         if (addr & ~PAGE_MASK)
1787                 return -EINVAL;
1788
1789         if (flags & MREMAP_FIXED && new_addr != addr)
1790                 return (unsigned long) -EINVAL;
1791
1792         vma = find_vma_exact(current->mm, addr, old_len);
1793         if (!vma)
1794                 return (unsigned long) -EINVAL;
1795
1796         if (vma->vm_end != vma->vm_start + old_len)
1797                 return (unsigned long) -EFAULT;
1798
1799         if (vma->vm_flags & VM_MAYSHARE)
1800                 return (unsigned long) -EPERM;
1801
1802         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1803                 return (unsigned long) -ENOMEM;
1804
1805         /* all checks complete - do it */
1806         vma->vm_end = vma->vm_start + new_len;
1807         return vma->vm_start;
1808 }
1809 EXPORT_SYMBOL(do_mremap);
1810
1811 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1812                 unsigned long, new_len, unsigned long, flags,
1813                 unsigned long, new_addr)
1814 {
1815         unsigned long ret;
1816
1817         down_write(&current->mm->mmap_sem);
1818         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1819         up_write(&current->mm->mmap_sem);
1820         return ret;
1821 }
1822
1823 struct page *follow_page_mask(struct vm_area_struct *vma,
1824                               unsigned long address, unsigned int flags,
1825                               unsigned int *page_mask)
1826 {
1827         *page_mask = 0;
1828         return NULL;
1829 }
1830
1831 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1832                 unsigned long pfn, unsigned long size, pgprot_t prot)
1833 {
1834         if (addr != (pfn << PAGE_SHIFT))
1835                 return -EINVAL;
1836
1837         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1838         return 0;
1839 }
1840 EXPORT_SYMBOL(remap_pfn_range);
1841
1842 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1843 {
1844         unsigned long pfn = start >> PAGE_SHIFT;
1845         unsigned long vm_len = vma->vm_end - vma->vm_start;
1846
1847         pfn += vma->vm_pgoff;
1848         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1849 }
1850 EXPORT_SYMBOL(vm_iomap_memory);
1851
1852 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1853                         unsigned long pgoff)
1854 {
1855         unsigned int size = vma->vm_end - vma->vm_start;
1856
1857         if (!(vma->vm_flags & VM_USERMAP))
1858                 return -EINVAL;
1859
1860         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1861         vma->vm_end = vma->vm_start + size;
1862
1863         return 0;
1864 }
1865 EXPORT_SYMBOL(remap_vmalloc_range);
1866
1867 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1868         unsigned long len, unsigned long pgoff, unsigned long flags)
1869 {
1870         return -ENOMEM;
1871 }
1872
1873 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1874 {
1875 }
1876
1877 void unmap_mapping_range(struct address_space *mapping,
1878                          loff_t const holebegin, loff_t const holelen,
1879                          int even_cows)
1880 {
1881 }
1882 EXPORT_SYMBOL(unmap_mapping_range);
1883
1884 /*
1885  * Check that a process has enough memory to allocate a new virtual
1886  * mapping. 0 means there is enough memory for the allocation to
1887  * succeed and -ENOMEM implies there is not.
1888  *
1889  * We currently support three overcommit policies, which are set via the
1890  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1891  *
1892  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1893  * Additional code 2002 Jul 20 by Robert Love.
1894  *
1895  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1896  *
1897  * Note this is a helper function intended to be used by LSMs which
1898  * wish to use this logic.
1899  */
1900 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1901 {
1902         unsigned long free, allowed, reserve;
1903
1904         vm_acct_memory(pages);
1905
1906         /*
1907          * Sometimes we want to use more memory than we have
1908          */
1909         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1910                 return 0;
1911
1912         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1913                 free = global_page_state(NR_FREE_PAGES);
1914                 free += global_page_state(NR_FILE_PAGES);
1915
1916                 /*
1917                  * shmem pages shouldn't be counted as free in this
1918                  * case, they can't be purged, only swapped out, and
1919                  * that won't affect the overall amount of available
1920                  * memory in the system.
1921                  */
1922                 free -= global_page_state(NR_SHMEM);
1923
1924                 free += get_nr_swap_pages();
1925
1926                 /*
1927                  * Any slabs which are created with the
1928                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1929                  * which are reclaimable, under pressure.  The dentry
1930                  * cache and most inode caches should fall into this
1931                  */
1932                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1933
1934                 /*
1935                  * Leave reserved pages. The pages are not for anonymous pages.
1936                  */
1937                 if (free <= totalreserve_pages)
1938                         goto error;
1939                 else
1940                         free -= totalreserve_pages;
1941
1942                 /*
1943                  * Reserve some for root
1944                  */
1945                 if (!cap_sys_admin)
1946                         free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1947
1948                 if (free > pages)
1949                         return 0;
1950
1951                 goto error;
1952         }
1953
1954         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1955         /*
1956          * Reserve some 3% for root
1957          */
1958         if (!cap_sys_admin)
1959                 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1960         allowed += total_swap_pages;
1961
1962         /*
1963          * Don't let a single process grow so big a user can't recover
1964          */
1965         if (mm) {
1966                 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
1967                 allowed -= min(mm->total_vm / 32, reserve);
1968         }
1969
1970         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1971                 return 0;
1972
1973 error:
1974         vm_unacct_memory(pages);
1975
1976         return -ENOMEM;
1977 }
1978
1979 int in_gate_area_no_mm(unsigned long addr)
1980 {
1981         return 0;
1982 }
1983
1984 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1985 {
1986         BUG();
1987         return 0;
1988 }
1989 EXPORT_SYMBOL(filemap_fault);
1990
1991 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
1992                              unsigned long size, pgoff_t pgoff)
1993 {
1994         BUG();
1995         return 0;
1996 }
1997 EXPORT_SYMBOL(generic_file_remap_pages);
1998
1999 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
2000                 unsigned long addr, void *buf, int len, int write)
2001 {
2002         struct vm_area_struct *vma;
2003
2004         down_read(&mm->mmap_sem);
2005
2006         /* the access must start within one of the target process's mappings */
2007         vma = find_vma(mm, addr);
2008         if (vma) {
2009                 /* don't overrun this mapping */
2010                 if (addr + len >= vma->vm_end)
2011                         len = vma->vm_end - addr;
2012
2013                 /* only read or write mappings where it is permitted */
2014                 if (write && vma->vm_flags & VM_MAYWRITE)
2015                         copy_to_user_page(vma, NULL, addr,
2016                                          (void *) addr, buf, len);
2017                 else if (!write && vma->vm_flags & VM_MAYREAD)
2018                         copy_from_user_page(vma, NULL, addr,
2019                                             buf, (void *) addr, len);
2020                 else
2021                         len = 0;
2022         } else {
2023                 len = 0;
2024         }
2025
2026         up_read(&mm->mmap_sem);
2027
2028         return len;
2029 }
2030
2031 /**
2032  * @access_remote_vm - access another process' address space
2033  * @mm:         the mm_struct of the target address space
2034  * @addr:       start address to access
2035  * @buf:        source or destination buffer
2036  * @len:        number of bytes to transfer
2037  * @write:      whether the access is a write
2038  *
2039  * The caller must hold a reference on @mm.
2040  */
2041 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2042                 void *buf, int len, int write)
2043 {
2044         return __access_remote_vm(NULL, mm, addr, buf, len, write);
2045 }
2046
2047 /*
2048  * Access another process' address space.
2049  * - source/target buffer must be kernel space
2050  */
2051 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2052 {
2053         struct mm_struct *mm;
2054
2055         if (addr + len < addr)
2056                 return 0;
2057
2058         mm = get_task_mm(tsk);
2059         if (!mm)
2060                 return 0;
2061
2062         len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2063
2064         mmput(mm);
2065         return len;
2066 }
2067
2068 /**
2069  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2070  * @inode: The inode to check
2071  * @size: The current filesize of the inode
2072  * @newsize: The proposed filesize of the inode
2073  *
2074  * Check the shared mappings on an inode on behalf of a shrinking truncate to
2075  * make sure that that any outstanding VMAs aren't broken and then shrink the
2076  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2077  * automatically grant mappings that are too large.
2078  */
2079 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2080                                 size_t newsize)
2081 {
2082         struct vm_area_struct *vma;
2083         struct vm_region *region;
2084         pgoff_t low, high;
2085         size_t r_size, r_top;
2086
2087         low = newsize >> PAGE_SHIFT;
2088         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2089
2090         down_write(&nommu_region_sem);
2091         mutex_lock(&inode->i_mapping->i_mmap_mutex);
2092
2093         /* search for VMAs that fall within the dead zone */
2094         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
2095                 /* found one - only interested if it's shared out of the page
2096                  * cache */
2097                 if (vma->vm_flags & VM_SHARED) {
2098                         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2099                         up_write(&nommu_region_sem);
2100                         return -ETXTBSY; /* not quite true, but near enough */
2101                 }
2102         }
2103
2104         /* reduce any regions that overlap the dead zone - if in existence,
2105          * these will be pointed to by VMAs that don't overlap the dead zone
2106          *
2107          * we don't check for any regions that start beyond the EOF as there
2108          * shouldn't be any
2109          */
2110         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
2111                                   0, ULONG_MAX) {
2112                 if (!(vma->vm_flags & VM_SHARED))
2113                         continue;
2114
2115                 region = vma->vm_region;
2116                 r_size = region->vm_top - region->vm_start;
2117                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2118
2119                 if (r_top > newsize) {
2120                         region->vm_top -= r_top - newsize;
2121                         if (region->vm_end > region->vm_top)
2122                                 region->vm_end = region->vm_top;
2123                 }
2124         }
2125
2126         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2127         up_write(&nommu_region_sem);
2128         return 0;
2129 }
2130
2131 /*
2132  * Initialise sysctl_user_reserve_kbytes.
2133  *
2134  * This is intended to prevent a user from starting a single memory hogging
2135  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
2136  * mode.
2137  *
2138  * The default value is min(3% of free memory, 128MB)
2139  * 128MB is enough to recover with sshd/login, bash, and top/kill.
2140  */
2141 static int __meminit init_user_reserve(void)
2142 {
2143         unsigned long free_kbytes;
2144
2145         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2146
2147         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
2148         return 0;
2149 }
2150 module_init(init_user_reserve)
2151
2152 /*
2153  * Initialise sysctl_admin_reserve_kbytes.
2154  *
2155  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
2156  * to log in and kill a memory hogging process.
2157  *
2158  * Systems with more than 256MB will reserve 8MB, enough to recover
2159  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
2160  * only reserve 3% of free pages by default.
2161  */
2162 static int __meminit init_admin_reserve(void)
2163 {
2164         unsigned long free_kbytes;
2165
2166         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2167
2168         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
2169         return 0;
2170 }
2171 module_init(init_admin_reserve)