Merge ../linux-2.6
[linux-2.6] / mm / mmap.c
1 /*
2  * mm/mmap.c
3  *
4  * Written by obz.
5  *
6  * Address space accounting code        <alan@redhat.com>
7  */
8
9 #include <linux/slab.h>
10 #include <linux/mm.h>
11 #include <linux/shm.h>
12 #include <linux/mman.h>
13 #include <linux/pagemap.h>
14 #include <linux/swap.h>
15 #include <linux/syscalls.h>
16 #include <linux/init.h>
17 #include <linux/file.h>
18 #include <linux/fs.h>
19 #include <linux/personality.h>
20 #include <linux/security.h>
21 #include <linux/hugetlb.h>
22 #include <linux/profile.h>
23 #include <linux/module.h>
24 #include <linux/mount.h>
25 #include <linux/mempolicy.h>
26 #include <linux/rmap.h>
27
28 #include <asm/uaccess.h>
29 #include <asm/cacheflush.h>
30 #include <asm/tlb.h>
31
32 static void unmap_region(struct mm_struct *mm,
33                 struct vm_area_struct *vma, struct vm_area_struct *prev,
34                 unsigned long start, unsigned long end);
35
36 /*
37  * WARNING: the debugging will use recursive algorithms so never enable this
38  * unless you know what you are doing.
39  */
40 #undef DEBUG_MM_RB
41
42 /* description of effects of mapping type and prot in current implementation.
43  * this is due to the limited x86 page protection hardware.  The expected
44  * behavior is in parens:
45  *
46  * map_type     prot
47  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
48  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
49  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
50  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
51  *              
52  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
53  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
54  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
55  *
56  */
57 pgprot_t protection_map[16] = {
58         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
59         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
60 };
61
62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
63 int sysctl_overcommit_ratio = 50;       /* default is 50% */
64 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
65 atomic_t vm_committed_space = ATOMIC_INIT(0);
66
67 /*
68  * Check that a process has enough memory to allocate a new virtual
69  * mapping. 0 means there is enough memory for the allocation to
70  * succeed and -ENOMEM implies there is not.
71  *
72  * We currently support three overcommit policies, which are set via the
73  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
74  *
75  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
76  * Additional code 2002 Jul 20 by Robert Love.
77  *
78  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
79  *
80  * Note this is a helper function intended to be used by LSMs which
81  * wish to use this logic.
82  */
83 int __vm_enough_memory(long pages, int cap_sys_admin)
84 {
85         unsigned long free, allowed;
86
87         vm_acct_memory(pages);
88
89         /*
90          * Sometimes we want to use more memory than we have
91          */
92         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
93                 return 0;
94
95         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
96                 unsigned long n;
97
98                 free = get_page_cache_size();
99                 free += nr_swap_pages;
100
101                 /*
102                  * Any slabs which are created with the
103                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
104                  * which are reclaimable, under pressure.  The dentry
105                  * cache and most inode caches should fall into this
106                  */
107                 free += atomic_read(&slab_reclaim_pages);
108
109                 /*
110                  * Leave the last 3% for root
111                  */
112                 if (!cap_sys_admin)
113                         free -= free / 32;
114
115                 if (free > pages)
116                         return 0;
117
118                 /*
119                  * nr_free_pages() is very expensive on large systems,
120                  * only call if we're about to fail.
121                  */
122                 n = nr_free_pages();
123                 if (!cap_sys_admin)
124                         n -= n / 32;
125                 free += n;
126
127                 if (free > pages)
128                         return 0;
129                 vm_unacct_memory(pages);
130                 return -ENOMEM;
131         }
132
133         allowed = (totalram_pages - hugetlb_total_pages())
134                 * sysctl_overcommit_ratio / 100;
135         /*
136          * Leave the last 3% for root
137          */
138         if (!cap_sys_admin)
139                 allowed -= allowed / 32;
140         allowed += total_swap_pages;
141
142         /* Don't let a single process grow too big:
143            leave 3% of the size of this process for other processes */
144         allowed -= current->mm->total_vm / 32;
145
146         /*
147          * cast `allowed' as a signed long because vm_committed_space
148          * sometimes has a negative value
149          */
150         if (atomic_read(&vm_committed_space) < (long)allowed)
151                 return 0;
152
153         vm_unacct_memory(pages);
154
155         return -ENOMEM;
156 }
157
158 EXPORT_SYMBOL(__vm_enough_memory);
159
160 /*
161  * Requires inode->i_mapping->i_mmap_lock
162  */
163 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
164                 struct file *file, struct address_space *mapping)
165 {
166         if (vma->vm_flags & VM_DENYWRITE)
167                 atomic_inc(&file->f_dentry->d_inode->i_writecount);
168         if (vma->vm_flags & VM_SHARED)
169                 mapping->i_mmap_writable--;
170
171         flush_dcache_mmap_lock(mapping);
172         if (unlikely(vma->vm_flags & VM_NONLINEAR))
173                 list_del_init(&vma->shared.vm_set.list);
174         else
175                 vma_prio_tree_remove(vma, &mapping->i_mmap);
176         flush_dcache_mmap_unlock(mapping);
177 }
178
179 /*
180  * Unlink a file-based vm structure from its prio_tree, to hide
181  * vma from rmap and vmtruncate before freeing its page tables.
182  */
183 void unlink_file_vma(struct vm_area_struct *vma)
184 {
185         struct file *file = vma->vm_file;
186
187         if (file) {
188                 struct address_space *mapping = file->f_mapping;
189                 spin_lock(&mapping->i_mmap_lock);
190                 __remove_shared_vm_struct(vma, file, mapping);
191                 spin_unlock(&mapping->i_mmap_lock);
192         }
193 }
194
195 /*
196  * Close a vm structure and free it, returning the next.
197  */
198 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
199 {
200         struct vm_area_struct *next = vma->vm_next;
201
202         might_sleep();
203         if (vma->vm_ops && vma->vm_ops->close)
204                 vma->vm_ops->close(vma);
205         if (vma->vm_file)
206                 fput(vma->vm_file);
207         mpol_free(vma_policy(vma));
208         kmem_cache_free(vm_area_cachep, vma);
209         return next;
210 }
211
212 asmlinkage unsigned long sys_brk(unsigned long brk)
213 {
214         unsigned long rlim, retval;
215         unsigned long newbrk, oldbrk;
216         struct mm_struct *mm = current->mm;
217
218         down_write(&mm->mmap_sem);
219
220         if (brk < mm->end_code)
221                 goto out;
222         newbrk = PAGE_ALIGN(brk);
223         oldbrk = PAGE_ALIGN(mm->brk);
224         if (oldbrk == newbrk)
225                 goto set_brk;
226
227         /* Always allow shrinking brk. */
228         if (brk <= mm->brk) {
229                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
230                         goto set_brk;
231                 goto out;
232         }
233
234         /* Check against rlimit.. */
235         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
236         if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
237                 goto out;
238
239         /* Check against existing mmap mappings. */
240         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
241                 goto out;
242
243         /* Ok, looks good - let it rip. */
244         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
245                 goto out;
246 set_brk:
247         mm->brk = brk;
248 out:
249         retval = mm->brk;
250         up_write(&mm->mmap_sem);
251         return retval;
252 }
253
254 #ifdef DEBUG_MM_RB
255 static int browse_rb(struct rb_root *root)
256 {
257         int i = 0, j;
258         struct rb_node *nd, *pn = NULL;
259         unsigned long prev = 0, pend = 0;
260
261         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
262                 struct vm_area_struct *vma;
263                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
264                 if (vma->vm_start < prev)
265                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
266                 if (vma->vm_start < pend)
267                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
268                 if (vma->vm_start > vma->vm_end)
269                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
270                 i++;
271                 pn = nd;
272         }
273         j = 0;
274         for (nd = pn; nd; nd = rb_prev(nd)) {
275                 j++;
276         }
277         if (i != j)
278                 printk("backwards %d, forwards %d\n", j, i), i = 0;
279         return i;
280 }
281
282 void validate_mm(struct mm_struct *mm)
283 {
284         int bug = 0;
285         int i = 0;
286         struct vm_area_struct *tmp = mm->mmap;
287         while (tmp) {
288                 tmp = tmp->vm_next;
289                 i++;
290         }
291         if (i != mm->map_count)
292                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
293         i = browse_rb(&mm->mm_rb);
294         if (i != mm->map_count)
295                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
296         if (bug)
297                 BUG();
298 }
299 #else
300 #define validate_mm(mm) do { } while (0)
301 #endif
302
303 static struct vm_area_struct *
304 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
305                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
306                 struct rb_node ** rb_parent)
307 {
308         struct vm_area_struct * vma;
309         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
310
311         __rb_link = &mm->mm_rb.rb_node;
312         rb_prev = __rb_parent = NULL;
313         vma = NULL;
314
315         while (*__rb_link) {
316                 struct vm_area_struct *vma_tmp;
317
318                 __rb_parent = *__rb_link;
319                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
320
321                 if (vma_tmp->vm_end > addr) {
322                         vma = vma_tmp;
323                         if (vma_tmp->vm_start <= addr)
324                                 return vma;
325                         __rb_link = &__rb_parent->rb_left;
326                 } else {
327                         rb_prev = __rb_parent;
328                         __rb_link = &__rb_parent->rb_right;
329                 }
330         }
331
332         *pprev = NULL;
333         if (rb_prev)
334                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
335         *rb_link = __rb_link;
336         *rb_parent = __rb_parent;
337         return vma;
338 }
339
340 static inline void
341 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
342                 struct vm_area_struct *prev, struct rb_node *rb_parent)
343 {
344         if (prev) {
345                 vma->vm_next = prev->vm_next;
346                 prev->vm_next = vma;
347         } else {
348                 mm->mmap = vma;
349                 if (rb_parent)
350                         vma->vm_next = rb_entry(rb_parent,
351                                         struct vm_area_struct, vm_rb);
352                 else
353                         vma->vm_next = NULL;
354         }
355 }
356
357 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
358                 struct rb_node **rb_link, struct rb_node *rb_parent)
359 {
360         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
361         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
362 }
363
364 static inline void __vma_link_file(struct vm_area_struct *vma)
365 {
366         struct file * file;
367
368         file = vma->vm_file;
369         if (file) {
370                 struct address_space *mapping = file->f_mapping;
371
372                 if (vma->vm_flags & VM_DENYWRITE)
373                         atomic_dec(&file->f_dentry->d_inode->i_writecount);
374                 if (vma->vm_flags & VM_SHARED)
375                         mapping->i_mmap_writable++;
376
377                 flush_dcache_mmap_lock(mapping);
378                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
379                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
380                 else
381                         vma_prio_tree_insert(vma, &mapping->i_mmap);
382                 flush_dcache_mmap_unlock(mapping);
383         }
384 }
385
386 static void
387 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
388         struct vm_area_struct *prev, struct rb_node **rb_link,
389         struct rb_node *rb_parent)
390 {
391         __vma_link_list(mm, vma, prev, rb_parent);
392         __vma_link_rb(mm, vma, rb_link, rb_parent);
393         __anon_vma_link(vma);
394 }
395
396 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
397                         struct vm_area_struct *prev, struct rb_node **rb_link,
398                         struct rb_node *rb_parent)
399 {
400         struct address_space *mapping = NULL;
401
402         if (vma->vm_file)
403                 mapping = vma->vm_file->f_mapping;
404
405         if (mapping) {
406                 spin_lock(&mapping->i_mmap_lock);
407                 vma->vm_truncate_count = mapping->truncate_count;
408         }
409         anon_vma_lock(vma);
410
411         __vma_link(mm, vma, prev, rb_link, rb_parent);
412         __vma_link_file(vma);
413
414         anon_vma_unlock(vma);
415         if (mapping)
416                 spin_unlock(&mapping->i_mmap_lock);
417
418         mm->map_count++;
419         validate_mm(mm);
420 }
421
422 /*
423  * Helper for vma_adjust in the split_vma insert case:
424  * insert vm structure into list and rbtree and anon_vma,
425  * but it has already been inserted into prio_tree earlier.
426  */
427 static void
428 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
429 {
430         struct vm_area_struct * __vma, * prev;
431         struct rb_node ** rb_link, * rb_parent;
432
433         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
434         if (__vma && __vma->vm_start < vma->vm_end)
435                 BUG();
436         __vma_link(mm, vma, prev, rb_link, rb_parent);
437         mm->map_count++;
438 }
439
440 static inline void
441 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
442                 struct vm_area_struct *prev)
443 {
444         prev->vm_next = vma->vm_next;
445         rb_erase(&vma->vm_rb, &mm->mm_rb);
446         if (mm->mmap_cache == vma)
447                 mm->mmap_cache = prev;
448 }
449
450 /*
451  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
452  * is already present in an i_mmap tree without adjusting the tree.
453  * The following helper function should be used when such adjustments
454  * are necessary.  The "insert" vma (if any) is to be inserted
455  * before we drop the necessary locks.
456  */
457 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
458         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
459 {
460         struct mm_struct *mm = vma->vm_mm;
461         struct vm_area_struct *next = vma->vm_next;
462         struct vm_area_struct *importer = NULL;
463         struct address_space *mapping = NULL;
464         struct prio_tree_root *root = NULL;
465         struct file *file = vma->vm_file;
466         struct anon_vma *anon_vma = NULL;
467         long adjust_next = 0;
468         int remove_next = 0;
469
470         if (next && !insert) {
471                 if (end >= next->vm_end) {
472                         /*
473                          * vma expands, overlapping all the next, and
474                          * perhaps the one after too (mprotect case 6).
475                          */
476 again:                  remove_next = 1 + (end > next->vm_end);
477                         end = next->vm_end;
478                         anon_vma = next->anon_vma;
479                         importer = vma;
480                 } else if (end > next->vm_start) {
481                         /*
482                          * vma expands, overlapping part of the next:
483                          * mprotect case 5 shifting the boundary up.
484                          */
485                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
486                         anon_vma = next->anon_vma;
487                         importer = vma;
488                 } else if (end < vma->vm_end) {
489                         /*
490                          * vma shrinks, and !insert tells it's not
491                          * split_vma inserting another: so it must be
492                          * mprotect case 4 shifting the boundary down.
493                          */
494                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
495                         anon_vma = next->anon_vma;
496                         importer = next;
497                 }
498         }
499
500         if (file) {
501                 mapping = file->f_mapping;
502                 if (!(vma->vm_flags & VM_NONLINEAR))
503                         root = &mapping->i_mmap;
504                 spin_lock(&mapping->i_mmap_lock);
505                 if (importer &&
506                     vma->vm_truncate_count != next->vm_truncate_count) {
507                         /*
508                          * unmap_mapping_range might be in progress:
509                          * ensure that the expanding vma is rescanned.
510                          */
511                         importer->vm_truncate_count = 0;
512                 }
513                 if (insert) {
514                         insert->vm_truncate_count = vma->vm_truncate_count;
515                         /*
516                          * Put into prio_tree now, so instantiated pages
517                          * are visible to arm/parisc __flush_dcache_page
518                          * throughout; but we cannot insert into address
519                          * space until vma start or end is updated.
520                          */
521                         __vma_link_file(insert);
522                 }
523         }
524
525         /*
526          * When changing only vma->vm_end, we don't really need
527          * anon_vma lock: but is that case worth optimizing out?
528          */
529         if (vma->anon_vma)
530                 anon_vma = vma->anon_vma;
531         if (anon_vma) {
532                 spin_lock(&anon_vma->lock);
533                 /*
534                  * Easily overlooked: when mprotect shifts the boundary,
535                  * make sure the expanding vma has anon_vma set if the
536                  * shrinking vma had, to cover any anon pages imported.
537                  */
538                 if (importer && !importer->anon_vma) {
539                         importer->anon_vma = anon_vma;
540                         __anon_vma_link(importer);
541                 }
542         }
543
544         if (root) {
545                 flush_dcache_mmap_lock(mapping);
546                 vma_prio_tree_remove(vma, root);
547                 if (adjust_next)
548                         vma_prio_tree_remove(next, root);
549         }
550
551         vma->vm_start = start;
552         vma->vm_end = end;
553         vma->vm_pgoff = pgoff;
554         if (adjust_next) {
555                 next->vm_start += adjust_next << PAGE_SHIFT;
556                 next->vm_pgoff += adjust_next;
557         }
558
559         if (root) {
560                 if (adjust_next)
561                         vma_prio_tree_insert(next, root);
562                 vma_prio_tree_insert(vma, root);
563                 flush_dcache_mmap_unlock(mapping);
564         }
565
566         if (remove_next) {
567                 /*
568                  * vma_merge has merged next into vma, and needs
569                  * us to remove next before dropping the locks.
570                  */
571                 __vma_unlink(mm, next, vma);
572                 if (file)
573                         __remove_shared_vm_struct(next, file, mapping);
574                 if (next->anon_vma)
575                         __anon_vma_merge(vma, next);
576         } else if (insert) {
577                 /*
578                  * split_vma has split insert from vma, and needs
579                  * us to insert it before dropping the locks
580                  * (it may either follow vma or precede it).
581                  */
582                 __insert_vm_struct(mm, insert);
583         }
584
585         if (anon_vma)
586                 spin_unlock(&anon_vma->lock);
587         if (mapping)
588                 spin_unlock(&mapping->i_mmap_lock);
589
590         if (remove_next) {
591                 if (file)
592                         fput(file);
593                 mm->map_count--;
594                 mpol_free(vma_policy(next));
595                 kmem_cache_free(vm_area_cachep, next);
596                 /*
597                  * In mprotect's case 6 (see comments on vma_merge),
598                  * we must remove another next too. It would clutter
599                  * up the code too much to do both in one go.
600                  */
601                 if (remove_next == 2) {
602                         next = vma->vm_next;
603                         goto again;
604                 }
605         }
606
607         validate_mm(mm);
608 }
609
610 /*
611  * If the vma has a ->close operation then the driver probably needs to release
612  * per-vma resources, so we don't attempt to merge those.
613  */
614 #define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)
615
616 static inline int is_mergeable_vma(struct vm_area_struct *vma,
617                         struct file *file, unsigned long vm_flags)
618 {
619         if (vma->vm_flags != vm_flags)
620                 return 0;
621         if (vma->vm_file != file)
622                 return 0;
623         if (vma->vm_ops && vma->vm_ops->close)
624                 return 0;
625         return 1;
626 }
627
628 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
629                                         struct anon_vma *anon_vma2)
630 {
631         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
632 }
633
634 /*
635  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
636  * in front of (at a lower virtual address and file offset than) the vma.
637  *
638  * We cannot merge two vmas if they have differently assigned (non-NULL)
639  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
640  *
641  * We don't check here for the merged mmap wrapping around the end of pagecache
642  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
643  * wrap, nor mmaps which cover the final page at index -1UL.
644  */
645 static int
646 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
647         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
648 {
649         if (is_mergeable_vma(vma, file, vm_flags) &&
650             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
651                 if (vma->vm_pgoff == vm_pgoff)
652                         return 1;
653         }
654         return 0;
655 }
656
657 /*
658  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
659  * beyond (at a higher virtual address and file offset than) the vma.
660  *
661  * We cannot merge two vmas if they have differently assigned (non-NULL)
662  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
663  */
664 static int
665 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
666         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
667 {
668         if (is_mergeable_vma(vma, file, vm_flags) &&
669             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
670                 pgoff_t vm_pglen;
671                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
672                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
673                         return 1;
674         }
675         return 0;
676 }
677
678 /*
679  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
680  * whether that can be merged with its predecessor or its successor.
681  * Or both (it neatly fills a hole).
682  *
683  * In most cases - when called for mmap, brk or mremap - [addr,end) is
684  * certain not to be mapped by the time vma_merge is called; but when
685  * called for mprotect, it is certain to be already mapped (either at
686  * an offset within prev, or at the start of next), and the flags of
687  * this area are about to be changed to vm_flags - and the no-change
688  * case has already been eliminated.
689  *
690  * The following mprotect cases have to be considered, where AAAA is
691  * the area passed down from mprotect_fixup, never extending beyond one
692  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
693  *
694  *     AAAA             AAAA                AAAA          AAAA
695  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
696  *    cannot merge    might become    might become    might become
697  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
698  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
699  *    mremap move:                                    PPPPNNNNNNNN 8
700  *        AAAA
701  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
702  *    might become    case 1 below    case 2 below    case 3 below
703  *
704  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
705  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
706  */
707 struct vm_area_struct *vma_merge(struct mm_struct *mm,
708                         struct vm_area_struct *prev, unsigned long addr,
709                         unsigned long end, unsigned long vm_flags,
710                         struct anon_vma *anon_vma, struct file *file,
711                         pgoff_t pgoff, struct mempolicy *policy)
712 {
713         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
714         struct vm_area_struct *area, *next;
715
716         /*
717          * We later require that vma->vm_flags == vm_flags,
718          * so this tests vma->vm_flags & VM_SPECIAL, too.
719          */
720         if (vm_flags & VM_SPECIAL)
721                 return NULL;
722
723         if (prev)
724                 next = prev->vm_next;
725         else
726                 next = mm->mmap;
727         area = next;
728         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
729                 next = next->vm_next;
730
731         /*
732          * Can it merge with the predecessor?
733          */
734         if (prev && prev->vm_end == addr &&
735                         mpol_equal(vma_policy(prev), policy) &&
736                         can_vma_merge_after(prev, vm_flags,
737                                                 anon_vma, file, pgoff)) {
738                 /*
739                  * OK, it can.  Can we now merge in the successor as well?
740                  */
741                 if (next && end == next->vm_start &&
742                                 mpol_equal(policy, vma_policy(next)) &&
743                                 can_vma_merge_before(next, vm_flags,
744                                         anon_vma, file, pgoff+pglen) &&
745                                 is_mergeable_anon_vma(prev->anon_vma,
746                                                       next->anon_vma)) {
747                                                         /* cases 1, 6 */
748                         vma_adjust(prev, prev->vm_start,
749                                 next->vm_end, prev->vm_pgoff, NULL);
750                 } else                                  /* cases 2, 5, 7 */
751                         vma_adjust(prev, prev->vm_start,
752                                 end, prev->vm_pgoff, NULL);
753                 return prev;
754         }
755
756         /*
757          * Can this new request be merged in front of next?
758          */
759         if (next && end == next->vm_start &&
760                         mpol_equal(policy, vma_policy(next)) &&
761                         can_vma_merge_before(next, vm_flags,
762                                         anon_vma, file, pgoff+pglen)) {
763                 if (prev && addr < prev->vm_end)        /* case 4 */
764                         vma_adjust(prev, prev->vm_start,
765                                 addr, prev->vm_pgoff, NULL);
766                 else                                    /* cases 3, 8 */
767                         vma_adjust(area, addr, next->vm_end,
768                                 next->vm_pgoff - pglen, NULL);
769                 return area;
770         }
771
772         return NULL;
773 }
774
775 /*
776  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
777  * neighbouring vmas for a suitable anon_vma, before it goes off
778  * to allocate a new anon_vma.  It checks because a repetitive
779  * sequence of mprotects and faults may otherwise lead to distinct
780  * anon_vmas being allocated, preventing vma merge in subsequent
781  * mprotect.
782  */
783 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
784 {
785         struct vm_area_struct *near;
786         unsigned long vm_flags;
787
788         near = vma->vm_next;
789         if (!near)
790                 goto try_prev;
791
792         /*
793          * Since only mprotect tries to remerge vmas, match flags
794          * which might be mprotected into each other later on.
795          * Neither mlock nor madvise tries to remerge at present,
796          * so leave their flags as obstructing a merge.
797          */
798         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
799         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
800
801         if (near->anon_vma && vma->vm_end == near->vm_start &&
802                         mpol_equal(vma_policy(vma), vma_policy(near)) &&
803                         can_vma_merge_before(near, vm_flags,
804                                 NULL, vma->vm_file, vma->vm_pgoff +
805                                 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
806                 return near->anon_vma;
807 try_prev:
808         /*
809          * It is potentially slow to have to call find_vma_prev here.
810          * But it's only on the first write fault on the vma, not
811          * every time, and we could devise a way to avoid it later
812          * (e.g. stash info in next's anon_vma_node when assigning
813          * an anon_vma, or when trying vma_merge).  Another time.
814          */
815         if (find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma)
816                 BUG();
817         if (!near)
818                 goto none;
819
820         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
821         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
822
823         if (near->anon_vma && near->vm_end == vma->vm_start &&
824                         mpol_equal(vma_policy(near), vma_policy(vma)) &&
825                         can_vma_merge_after(near, vm_flags,
826                                 NULL, vma->vm_file, vma->vm_pgoff))
827                 return near->anon_vma;
828 none:
829         /*
830          * There's no absolute need to look only at touching neighbours:
831          * we could search further afield for "compatible" anon_vmas.
832          * But it would probably just be a waste of time searching,
833          * or lead to too many vmas hanging off the same anon_vma.
834          * We're trying to allow mprotect remerging later on,
835          * not trying to minimize memory used for anon_vmas.
836          */
837         return NULL;
838 }
839
840 #ifdef CONFIG_PROC_FS
841 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
842                                                 struct file *file, long pages)
843 {
844         const unsigned long stack_flags
845                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
846
847 #ifdef CONFIG_HUGETLB
848         if (flags & VM_HUGETLB) {
849                 if (!(flags & VM_DONTCOPY))
850                         mm->shared_vm += pages;
851                 return;
852         }
853 #endif /* CONFIG_HUGETLB */
854
855         if (file) {
856                 mm->shared_vm += pages;
857                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
858                         mm->exec_vm += pages;
859         } else if (flags & stack_flags)
860                 mm->stack_vm += pages;
861         if (flags & (VM_RESERVED|VM_IO))
862                 mm->reserved_vm += pages;
863 }
864 #endif /* CONFIG_PROC_FS */
865
866 /*
867  * The caller must hold down_write(current->mm->mmap_sem).
868  */
869
870 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
871                         unsigned long len, unsigned long prot,
872                         unsigned long flags, unsigned long pgoff)
873 {
874         struct mm_struct * mm = current->mm;
875         struct vm_area_struct * vma, * prev;
876         struct inode *inode;
877         unsigned int vm_flags;
878         int correct_wcount = 0;
879         int error;
880         struct rb_node ** rb_link, * rb_parent;
881         int accountable = 1;
882         unsigned long charged = 0, reqprot = prot;
883
884         if (file) {
885                 if (is_file_hugepages(file))
886                         accountable = 0;
887
888                 if (!file->f_op || !file->f_op->mmap)
889                         return -ENODEV;
890
891                 if ((prot & PROT_EXEC) &&
892                     (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
893                         return -EPERM;
894         }
895         /*
896          * Does the application expect PROT_READ to imply PROT_EXEC?
897          *
898          * (the exception is when the underlying filesystem is noexec
899          *  mounted, in which case we dont add PROT_EXEC.)
900          */
901         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
902                 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
903                         prot |= PROT_EXEC;
904
905         if (!len)
906                 return -EINVAL;
907
908         /* Careful about overflows.. */
909         len = PAGE_ALIGN(len);
910         if (!len || len > TASK_SIZE)
911                 return -ENOMEM;
912
913         /* offset overflow? */
914         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
915                return -EOVERFLOW;
916
917         /* Too many mappings? */
918         if (mm->map_count > sysctl_max_map_count)
919                 return -ENOMEM;
920
921         /* Obtain the address to map to. we verify (or select) it and ensure
922          * that it represents a valid section of the address space.
923          */
924         addr = get_unmapped_area(file, addr, len, pgoff, flags);
925         if (addr & ~PAGE_MASK)
926                 return addr;
927
928         /* Do simple checking here so the lower-level routines won't have
929          * to. we assume access permissions have been handled by the open
930          * of the memory object, so we don't do any here.
931          */
932         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
933                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
934
935         if (flags & MAP_LOCKED) {
936                 if (!can_do_mlock())
937                         return -EPERM;
938                 vm_flags |= VM_LOCKED;
939         }
940         /* mlock MCL_FUTURE? */
941         if (vm_flags & VM_LOCKED) {
942                 unsigned long locked, lock_limit;
943                 locked = len >> PAGE_SHIFT;
944                 locked += mm->locked_vm;
945                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
946                 lock_limit >>= PAGE_SHIFT;
947                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
948                         return -EAGAIN;
949         }
950
951         inode = file ? file->f_dentry->d_inode : NULL;
952
953         if (file) {
954                 switch (flags & MAP_TYPE) {
955                 case MAP_SHARED:
956                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
957                                 return -EACCES;
958
959                         /*
960                          * Make sure we don't allow writing to an append-only
961                          * file..
962                          */
963                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
964                                 return -EACCES;
965
966                         /*
967                          * Make sure there are no mandatory locks on the file.
968                          */
969                         if (locks_verify_locked(inode))
970                                 return -EAGAIN;
971
972                         vm_flags |= VM_SHARED | VM_MAYSHARE;
973                         if (!(file->f_mode & FMODE_WRITE))
974                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
975
976                         /* fall through */
977                 case MAP_PRIVATE:
978                         if (!(file->f_mode & FMODE_READ))
979                                 return -EACCES;
980                         break;
981
982                 default:
983                         return -EINVAL;
984                 }
985         } else {
986                 switch (flags & MAP_TYPE) {
987                 case MAP_SHARED:
988                         vm_flags |= VM_SHARED | VM_MAYSHARE;
989                         break;
990                 case MAP_PRIVATE:
991                         /*
992                          * Set pgoff according to addr for anon_vma.
993                          */
994                         pgoff = addr >> PAGE_SHIFT;
995                         break;
996                 default:
997                         return -EINVAL;
998                 }
999         }
1000
1001         error = security_file_mmap(file, reqprot, prot, flags);
1002         if (error)
1003                 return error;
1004                 
1005         /* Clear old maps */
1006         error = -ENOMEM;
1007 munmap_back:
1008         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1009         if (vma && vma->vm_start < addr + len) {
1010                 if (do_munmap(mm, addr, len))
1011                         return -ENOMEM;
1012                 goto munmap_back;
1013         }
1014
1015         /* Check against address space limit. */
1016         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1017                 return -ENOMEM;
1018
1019         if (accountable && (!(flags & MAP_NORESERVE) ||
1020                             sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1021                 if (vm_flags & VM_SHARED) {
1022                         /* Check memory availability in shmem_file_setup? */
1023                         vm_flags |= VM_ACCOUNT;
1024                 } else if (vm_flags & VM_WRITE) {
1025                         /*
1026                          * Private writable mapping: check memory availability
1027                          */
1028                         charged = len >> PAGE_SHIFT;
1029                         if (security_vm_enough_memory(charged))
1030                                 return -ENOMEM;
1031                         vm_flags |= VM_ACCOUNT;
1032                 }
1033         }
1034
1035         /*
1036          * Can we just expand an old private anonymous mapping?
1037          * The VM_SHARED test is necessary because shmem_zero_setup
1038          * will create the file object for a shared anonymous map below.
1039          */
1040         if (!file && !(vm_flags & VM_SHARED) &&
1041             vma_merge(mm, prev, addr, addr + len, vm_flags,
1042                                         NULL, NULL, pgoff, NULL))
1043                 goto out;
1044
1045         /*
1046          * Determine the object being mapped and call the appropriate
1047          * specific mapper. the address has already been validated, but
1048          * not unmapped, but the maps are removed from the list.
1049          */
1050         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1051         if (!vma) {
1052                 error = -ENOMEM;
1053                 goto unacct_error;
1054         }
1055         memset(vma, 0, sizeof(*vma));
1056
1057         vma->vm_mm = mm;
1058         vma->vm_start = addr;
1059         vma->vm_end = addr + len;
1060         vma->vm_flags = vm_flags;
1061         vma->vm_page_prot = protection_map[vm_flags & 0x0f];
1062         vma->vm_pgoff = pgoff;
1063
1064         if (file) {
1065                 error = -EINVAL;
1066                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1067                         goto free_vma;
1068                 if (vm_flags & VM_DENYWRITE) {
1069                         error = deny_write_access(file);
1070                         if (error)
1071                                 goto free_vma;
1072                         correct_wcount = 1;
1073                 }
1074                 vma->vm_file = file;
1075                 get_file(file);
1076                 error = file->f_op->mmap(file, vma);
1077                 if (error)
1078                         goto unmap_and_free_vma;
1079                 if ((vma->vm_flags & (VM_SHARED | VM_WRITE | VM_RESERVED))
1080                                                 == (VM_WRITE | VM_RESERVED)) {
1081                         printk(KERN_WARNING "program %s is using MAP_PRIVATE, "
1082                                 "PROT_WRITE mmap of VM_RESERVED memory, which "
1083                                 "is deprecated. Please report this to "
1084                                 "linux-kernel@vger.kernel.org\n",current->comm);
1085                         if (vma->vm_ops && vma->vm_ops->close)
1086                                 vma->vm_ops->close(vma);
1087                         error = -EACCES;
1088                         goto unmap_and_free_vma;
1089                 }
1090         } else if (vm_flags & VM_SHARED) {
1091                 error = shmem_zero_setup(vma);
1092                 if (error)
1093                         goto free_vma;
1094         }
1095
1096         /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1097          * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1098          * that memory reservation must be checked; but that reservation
1099          * belongs to shared memory object, not to vma: so now clear it.
1100          */
1101         if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1102                 vma->vm_flags &= ~VM_ACCOUNT;
1103
1104         /* Can addr have changed??
1105          *
1106          * Answer: Yes, several device drivers can do it in their
1107          *         f_op->mmap method. -DaveM
1108          */
1109         addr = vma->vm_start;
1110         pgoff = vma->vm_pgoff;
1111         vm_flags = vma->vm_flags;
1112
1113         if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1114                         vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1115                 file = vma->vm_file;
1116                 vma_link(mm, vma, prev, rb_link, rb_parent);
1117                 if (correct_wcount)
1118                         atomic_inc(&inode->i_writecount);
1119         } else {
1120                 if (file) {
1121                         if (correct_wcount)
1122                                 atomic_inc(&inode->i_writecount);
1123                         fput(file);
1124                 }
1125                 mpol_free(vma_policy(vma));
1126                 kmem_cache_free(vm_area_cachep, vma);
1127         }
1128 out:    
1129         mm->total_vm += len >> PAGE_SHIFT;
1130         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1131         if (vm_flags & VM_LOCKED) {
1132                 mm->locked_vm += len >> PAGE_SHIFT;
1133                 make_pages_present(addr, addr + len);
1134         }
1135         if (flags & MAP_POPULATE) {
1136                 up_write(&mm->mmap_sem);
1137                 sys_remap_file_pages(addr, len, 0,
1138                                         pgoff, flags & MAP_NONBLOCK);
1139                 down_write(&mm->mmap_sem);
1140         }
1141         return addr;
1142
1143 unmap_and_free_vma:
1144         if (correct_wcount)
1145                 atomic_inc(&inode->i_writecount);
1146         vma->vm_file = NULL;
1147         fput(file);
1148
1149         /* Undo any partial mapping done by a device driver. */
1150         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1151         charged = 0;
1152 free_vma:
1153         kmem_cache_free(vm_area_cachep, vma);
1154 unacct_error:
1155         if (charged)
1156                 vm_unacct_memory(charged);
1157         return error;
1158 }
1159
1160 EXPORT_SYMBOL(do_mmap_pgoff);
1161
1162 /* Get an address range which is currently unmapped.
1163  * For shmat() with addr=0.
1164  *
1165  * Ugly calling convention alert:
1166  * Return value with the low bits set means error value,
1167  * ie
1168  *      if (ret & ~PAGE_MASK)
1169  *              error = ret;
1170  *
1171  * This function "knows" that -ENOMEM has the bits set.
1172  */
1173 #ifndef HAVE_ARCH_UNMAPPED_AREA
1174 unsigned long
1175 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1176                 unsigned long len, unsigned long pgoff, unsigned long flags)
1177 {
1178         struct mm_struct *mm = current->mm;
1179         struct vm_area_struct *vma;
1180         unsigned long start_addr;
1181
1182         if (len > TASK_SIZE)
1183                 return -ENOMEM;
1184
1185         if (addr) {
1186                 addr = PAGE_ALIGN(addr);
1187                 vma = find_vma(mm, addr);
1188                 if (TASK_SIZE - len >= addr &&
1189                     (!vma || addr + len <= vma->vm_start))
1190                         return addr;
1191         }
1192         if (len > mm->cached_hole_size) {
1193                 start_addr = addr = mm->free_area_cache;
1194         } else {
1195                 start_addr = addr = TASK_UNMAPPED_BASE;
1196                 mm->cached_hole_size = 0;
1197         }
1198
1199 full_search:
1200         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1201                 /* At this point:  (!vma || addr < vma->vm_end). */
1202                 if (TASK_SIZE - len < addr) {
1203                         /*
1204                          * Start a new search - just in case we missed
1205                          * some holes.
1206                          */
1207                         if (start_addr != TASK_UNMAPPED_BASE) {
1208                                 addr = TASK_UNMAPPED_BASE;
1209                                 start_addr = addr;
1210                                 mm->cached_hole_size = 0;
1211                                 goto full_search;
1212                         }
1213                         return -ENOMEM;
1214                 }
1215                 if (!vma || addr + len <= vma->vm_start) {
1216                         /*
1217                          * Remember the place where we stopped the search:
1218                          */
1219                         mm->free_area_cache = addr + len;
1220                         return addr;
1221                 }
1222                 if (addr + mm->cached_hole_size < vma->vm_start)
1223                         mm->cached_hole_size = vma->vm_start - addr;
1224                 addr = vma->vm_end;
1225         }
1226 }
1227 #endif  
1228
1229 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1230 {
1231         /*
1232          * Is this a new hole at the lowest possible address?
1233          */
1234         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1235                 mm->free_area_cache = addr;
1236                 mm->cached_hole_size = ~0UL;
1237         }
1238 }
1239
1240 /*
1241  * This mmap-allocator allocates new areas top-down from below the
1242  * stack's low limit (the base):
1243  */
1244 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1245 unsigned long
1246 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1247                           const unsigned long len, const unsigned long pgoff,
1248                           const unsigned long flags)
1249 {
1250         struct vm_area_struct *vma;
1251         struct mm_struct *mm = current->mm;
1252         unsigned long addr = addr0;
1253
1254         /* requested length too big for entire address space */
1255         if (len > TASK_SIZE)
1256                 return -ENOMEM;
1257
1258         /* requesting a specific address */
1259         if (addr) {
1260                 addr = PAGE_ALIGN(addr);
1261                 vma = find_vma(mm, addr);
1262                 if (TASK_SIZE - len >= addr &&
1263                                 (!vma || addr + len <= vma->vm_start))
1264                         return addr;
1265         }
1266
1267         /* check if free_area_cache is useful for us */
1268         if (len <= mm->cached_hole_size) {
1269                 mm->cached_hole_size = 0;
1270                 mm->free_area_cache = mm->mmap_base;
1271         }
1272
1273         /* either no address requested or can't fit in requested address hole */
1274         addr = mm->free_area_cache;
1275
1276         /* make sure it can fit in the remaining address space */
1277         if (addr > len) {
1278                 vma = find_vma(mm, addr-len);
1279                 if (!vma || addr <= vma->vm_start)
1280                         /* remember the address as a hint for next time */
1281                         return (mm->free_area_cache = addr-len);
1282         }
1283
1284         if (mm->mmap_base < len)
1285                 goto bottomup;
1286
1287         addr = mm->mmap_base-len;
1288
1289         do {
1290                 /*
1291                  * Lookup failure means no vma is above this address,
1292                  * else if new region fits below vma->vm_start,
1293                  * return with success:
1294                  */
1295                 vma = find_vma(mm, addr);
1296                 if (!vma || addr+len <= vma->vm_start)
1297                         /* remember the address as a hint for next time */
1298                         return (mm->free_area_cache = addr);
1299
1300                 /* remember the largest hole we saw so far */
1301                 if (addr + mm->cached_hole_size < vma->vm_start)
1302                         mm->cached_hole_size = vma->vm_start - addr;
1303
1304                 /* try just below the current vma->vm_start */
1305                 addr = vma->vm_start-len;
1306         } while (len < vma->vm_start);
1307
1308 bottomup:
1309         /*
1310          * A failed mmap() very likely causes application failure,
1311          * so fall back to the bottom-up function here. This scenario
1312          * can happen with large stack limits and large mmap()
1313          * allocations.
1314          */
1315         mm->cached_hole_size = ~0UL;
1316         mm->free_area_cache = TASK_UNMAPPED_BASE;
1317         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1318         /*
1319          * Restore the topdown base:
1320          */
1321         mm->free_area_cache = mm->mmap_base;
1322         mm->cached_hole_size = ~0UL;
1323
1324         return addr;
1325 }
1326 #endif
1327
1328 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1329 {
1330         /*
1331          * Is this a new hole at the highest possible address?
1332          */
1333         if (addr > mm->free_area_cache)
1334                 mm->free_area_cache = addr;
1335
1336         /* dont allow allocations above current base */
1337         if (mm->free_area_cache > mm->mmap_base)
1338                 mm->free_area_cache = mm->mmap_base;
1339 }
1340
1341 unsigned long
1342 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1343                 unsigned long pgoff, unsigned long flags)
1344 {
1345         unsigned long ret;
1346
1347         if (!(flags & MAP_FIXED)) {
1348                 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1349
1350                 get_area = current->mm->get_unmapped_area;
1351                 if (file && file->f_op && file->f_op->get_unmapped_area)
1352                         get_area = file->f_op->get_unmapped_area;
1353                 addr = get_area(file, addr, len, pgoff, flags);
1354                 if (IS_ERR_VALUE(addr))
1355                         return addr;
1356         }
1357
1358         if (addr > TASK_SIZE - len)
1359                 return -ENOMEM;
1360         if (addr & ~PAGE_MASK)
1361                 return -EINVAL;
1362         if (file && is_file_hugepages(file))  {
1363                 /*
1364                  * Check if the given range is hugepage aligned, and
1365                  * can be made suitable for hugepages.
1366                  */
1367                 ret = prepare_hugepage_range(addr, len);
1368         } else {
1369                 /*
1370                  * Ensure that a normal request is not falling in a
1371                  * reserved hugepage range.  For some archs like IA-64,
1372                  * there is a separate region for hugepages.
1373                  */
1374                 ret = is_hugepage_only_range(current->mm, addr, len);
1375         }
1376         if (ret)
1377                 return -EINVAL;
1378         return addr;
1379 }
1380
1381 EXPORT_SYMBOL(get_unmapped_area);
1382
1383 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1384 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1385 {
1386         struct vm_area_struct *vma = NULL;
1387
1388         if (mm) {
1389                 /* Check the cache first. */
1390                 /* (Cache hit rate is typically around 35%.) */
1391                 vma = mm->mmap_cache;
1392                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1393                         struct rb_node * rb_node;
1394
1395                         rb_node = mm->mm_rb.rb_node;
1396                         vma = NULL;
1397
1398                         while (rb_node) {
1399                                 struct vm_area_struct * vma_tmp;
1400
1401                                 vma_tmp = rb_entry(rb_node,
1402                                                 struct vm_area_struct, vm_rb);
1403
1404                                 if (vma_tmp->vm_end > addr) {
1405                                         vma = vma_tmp;
1406                                         if (vma_tmp->vm_start <= addr)
1407                                                 break;
1408                                         rb_node = rb_node->rb_left;
1409                                 } else
1410                                         rb_node = rb_node->rb_right;
1411                         }
1412                         if (vma)
1413                                 mm->mmap_cache = vma;
1414                 }
1415         }
1416         return vma;
1417 }
1418
1419 EXPORT_SYMBOL(find_vma);
1420
1421 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1422 struct vm_area_struct *
1423 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1424                         struct vm_area_struct **pprev)
1425 {
1426         struct vm_area_struct *vma = NULL, *prev = NULL;
1427         struct rb_node * rb_node;
1428         if (!mm)
1429                 goto out;
1430
1431         /* Guard against addr being lower than the first VMA */
1432         vma = mm->mmap;
1433
1434         /* Go through the RB tree quickly. */
1435         rb_node = mm->mm_rb.rb_node;
1436
1437         while (rb_node) {
1438                 struct vm_area_struct *vma_tmp;
1439                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1440
1441                 if (addr < vma_tmp->vm_end) {
1442                         rb_node = rb_node->rb_left;
1443                 } else {
1444                         prev = vma_tmp;
1445                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1446                                 break;
1447                         rb_node = rb_node->rb_right;
1448                 }
1449         }
1450
1451 out:
1452         *pprev = prev;
1453         return prev ? prev->vm_next : vma;
1454 }
1455
1456 /*
1457  * Verify that the stack growth is acceptable and
1458  * update accounting. This is shared with both the
1459  * grow-up and grow-down cases.
1460  */
1461 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1462 {
1463         struct mm_struct *mm = vma->vm_mm;
1464         struct rlimit *rlim = current->signal->rlim;
1465
1466         /* address space limit tests */
1467         if (!may_expand_vm(mm, grow))
1468                 return -ENOMEM;
1469
1470         /* Stack limit test */
1471         if (size > rlim[RLIMIT_STACK].rlim_cur)
1472                 return -ENOMEM;
1473
1474         /* mlock limit tests */
1475         if (vma->vm_flags & VM_LOCKED) {
1476                 unsigned long locked;
1477                 unsigned long limit;
1478                 locked = mm->locked_vm + grow;
1479                 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1480                 if (locked > limit && !capable(CAP_IPC_LOCK))
1481                         return -ENOMEM;
1482         }
1483
1484         /*
1485          * Overcommit..  This must be the final test, as it will
1486          * update security statistics.
1487          */
1488         if (security_vm_enough_memory(grow))
1489                 return -ENOMEM;
1490
1491         /* Ok, everything looks good - let it rip */
1492         mm->total_vm += grow;
1493         if (vma->vm_flags & VM_LOCKED)
1494                 mm->locked_vm += grow;
1495         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1496         return 0;
1497 }
1498
1499 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1500 /*
1501  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1502  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1503  */
1504 #ifdef CONFIG_STACK_GROWSUP
1505 static inline
1506 #endif
1507 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1508 {
1509         int error;
1510
1511         if (!(vma->vm_flags & VM_GROWSUP))
1512                 return -EFAULT;
1513
1514         /*
1515          * We must make sure the anon_vma is allocated
1516          * so that the anon_vma locking is not a noop.
1517          */
1518         if (unlikely(anon_vma_prepare(vma)))
1519                 return -ENOMEM;
1520         anon_vma_lock(vma);
1521
1522         /*
1523          * vma->vm_start/vm_end cannot change under us because the caller
1524          * is required to hold the mmap_sem in read mode.  We need the
1525          * anon_vma lock to serialize against concurrent expand_stacks.
1526          */
1527         address += 4 + PAGE_SIZE - 1;
1528         address &= PAGE_MASK;
1529         error = 0;
1530
1531         /* Somebody else might have raced and expanded it already */
1532         if (address > vma->vm_end) {
1533                 unsigned long size, grow;
1534
1535                 size = address - vma->vm_start;
1536                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1537
1538                 error = acct_stack_growth(vma, size, grow);
1539                 if (!error)
1540                         vma->vm_end = address;
1541         }
1542         anon_vma_unlock(vma);
1543         return error;
1544 }
1545 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1546
1547 #ifdef CONFIG_STACK_GROWSUP
1548 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1549 {
1550         return expand_upwards(vma, address);
1551 }
1552
1553 struct vm_area_struct *
1554 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1555 {
1556         struct vm_area_struct *vma, *prev;
1557
1558         addr &= PAGE_MASK;
1559         vma = find_vma_prev(mm, addr, &prev);
1560         if (vma && (vma->vm_start <= addr))
1561                 return vma;
1562         if (!prev || expand_stack(prev, addr))
1563                 return NULL;
1564         if (prev->vm_flags & VM_LOCKED) {
1565                 make_pages_present(addr, prev->vm_end);
1566         }
1567         return prev;
1568 }
1569 #else
1570 /*
1571  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1572  */
1573 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1574 {
1575         int error;
1576
1577         /*
1578          * We must make sure the anon_vma is allocated
1579          * so that the anon_vma locking is not a noop.
1580          */
1581         if (unlikely(anon_vma_prepare(vma)))
1582                 return -ENOMEM;
1583         anon_vma_lock(vma);
1584
1585         /*
1586          * vma->vm_start/vm_end cannot change under us because the caller
1587          * is required to hold the mmap_sem in read mode.  We need the
1588          * anon_vma lock to serialize against concurrent expand_stacks.
1589          */
1590         address &= PAGE_MASK;
1591         error = 0;
1592
1593         /* Somebody else might have raced and expanded it already */
1594         if (address < vma->vm_start) {
1595                 unsigned long size, grow;
1596
1597                 size = vma->vm_end - address;
1598                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1599
1600                 error = acct_stack_growth(vma, size, grow);
1601                 if (!error) {
1602                         vma->vm_start = address;
1603                         vma->vm_pgoff -= grow;
1604                 }
1605         }
1606         anon_vma_unlock(vma);
1607         return error;
1608 }
1609
1610 struct vm_area_struct *
1611 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1612 {
1613         struct vm_area_struct * vma;
1614         unsigned long start;
1615
1616         addr &= PAGE_MASK;
1617         vma = find_vma(mm,addr);
1618         if (!vma)
1619                 return NULL;
1620         if (vma->vm_start <= addr)
1621                 return vma;
1622         if (!(vma->vm_flags & VM_GROWSDOWN))
1623                 return NULL;
1624         start = vma->vm_start;
1625         if (expand_stack(vma, addr))
1626                 return NULL;
1627         if (vma->vm_flags & VM_LOCKED) {
1628                 make_pages_present(addr, start);
1629         }
1630         return vma;
1631 }
1632 #endif
1633
1634 /*
1635  * Ok - we have the memory areas we should free on the vma list,
1636  * so release them, and do the vma updates.
1637  *
1638  * Called with the mm semaphore held.
1639  */
1640 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1641 {
1642         /* Update high watermark before we lower total_vm */
1643         update_hiwater_vm(mm);
1644         do {
1645                 long nrpages = vma_pages(vma);
1646
1647                 mm->total_vm -= nrpages;
1648                 if (vma->vm_flags & VM_LOCKED)
1649                         mm->locked_vm -= nrpages;
1650                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1651                 vma = remove_vma(vma);
1652         } while (vma);
1653         validate_mm(mm);
1654 }
1655
1656 /*
1657  * Get rid of page table information in the indicated region.
1658  *
1659  * Called with the mm semaphore held.
1660  */
1661 static void unmap_region(struct mm_struct *mm,
1662                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1663                 unsigned long start, unsigned long end)
1664 {
1665         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1666         struct mmu_gather *tlb;
1667         unsigned long nr_accounted = 0;
1668
1669         lru_add_drain();
1670         tlb = tlb_gather_mmu(mm, 0);
1671         update_hiwater_rss(mm);
1672         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1673         vm_unacct_memory(nr_accounted);
1674         free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1675                                  next? next->vm_start: 0);
1676         tlb_finish_mmu(tlb, start, end);
1677 }
1678
1679 /*
1680  * Create a list of vma's touched by the unmap, removing them from the mm's
1681  * vma list as we go..
1682  */
1683 static void
1684 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1685         struct vm_area_struct *prev, unsigned long end)
1686 {
1687         struct vm_area_struct **insertion_point;
1688         struct vm_area_struct *tail_vma = NULL;
1689         unsigned long addr;
1690
1691         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1692         do {
1693                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1694                 mm->map_count--;
1695                 tail_vma = vma;
1696                 vma = vma->vm_next;
1697         } while (vma && vma->vm_start < end);
1698         *insertion_point = vma;
1699         tail_vma->vm_next = NULL;
1700         if (mm->unmap_area == arch_unmap_area)
1701                 addr = prev ? prev->vm_end : mm->mmap_base;
1702         else
1703                 addr = vma ?  vma->vm_start : mm->mmap_base;
1704         mm->unmap_area(mm, addr);
1705         mm->mmap_cache = NULL;          /* Kill the cache. */
1706 }
1707
1708 /*
1709  * Split a vma into two pieces at address 'addr', a new vma is allocated
1710  * either for the first part or the the tail.
1711  */
1712 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1713               unsigned long addr, int new_below)
1714 {
1715         struct mempolicy *pol;
1716         struct vm_area_struct *new;
1717
1718         if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1719                 return -EINVAL;
1720
1721         if (mm->map_count >= sysctl_max_map_count)
1722                 return -ENOMEM;
1723
1724         new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1725         if (!new)
1726                 return -ENOMEM;
1727
1728         /* most fields are the same, copy all, and then fixup */
1729         *new = *vma;
1730
1731         if (new_below)
1732                 new->vm_end = addr;
1733         else {
1734                 new->vm_start = addr;
1735                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1736         }
1737
1738         pol = mpol_copy(vma_policy(vma));
1739         if (IS_ERR(pol)) {
1740                 kmem_cache_free(vm_area_cachep, new);
1741                 return PTR_ERR(pol);
1742         }
1743         vma_set_policy(new, pol);
1744
1745         if (new->vm_file)
1746                 get_file(new->vm_file);
1747
1748         if (new->vm_ops && new->vm_ops->open)
1749                 new->vm_ops->open(new);
1750
1751         if (new_below)
1752                 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1753                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1754         else
1755                 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1756
1757         return 0;
1758 }
1759
1760 /* Munmap is split into 2 main parts -- this part which finds
1761  * what needs doing, and the areas themselves, which do the
1762  * work.  This now handles partial unmappings.
1763  * Jeremy Fitzhardinge <jeremy@goop.org>
1764  */
1765 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1766 {
1767         unsigned long end;
1768         struct vm_area_struct *vma, *prev, *last;
1769
1770         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1771                 return -EINVAL;
1772
1773         if ((len = PAGE_ALIGN(len)) == 0)
1774                 return -EINVAL;
1775
1776         /* Find the first overlapping VMA */
1777         vma = find_vma_prev(mm, start, &prev);
1778         if (!vma)
1779                 return 0;
1780         /* we have  start < vma->vm_end  */
1781
1782         /* if it doesn't overlap, we have nothing.. */
1783         end = start + len;
1784         if (vma->vm_start >= end)
1785                 return 0;
1786
1787         /*
1788          * If we need to split any vma, do it now to save pain later.
1789          *
1790          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1791          * unmapped vm_area_struct will remain in use: so lower split_vma
1792          * places tmp vma above, and higher split_vma places tmp vma below.
1793          */
1794         if (start > vma->vm_start) {
1795                 int error = split_vma(mm, vma, start, 0);
1796                 if (error)
1797                         return error;
1798                 prev = vma;
1799         }
1800
1801         /* Does it split the last one? */
1802         last = find_vma(mm, end);
1803         if (last && end > last->vm_start) {
1804                 int error = split_vma(mm, last, end, 1);
1805                 if (error)
1806                         return error;
1807         }
1808         vma = prev? prev->vm_next: mm->mmap;
1809
1810         /*
1811          * Remove the vma's, and unmap the actual pages
1812          */
1813         detach_vmas_to_be_unmapped(mm, vma, prev, end);
1814         unmap_region(mm, vma, prev, start, end);
1815
1816         /* Fix up all other VM information */
1817         remove_vma_list(mm, vma);
1818
1819         return 0;
1820 }
1821
1822 EXPORT_SYMBOL(do_munmap);
1823
1824 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1825 {
1826         int ret;
1827         struct mm_struct *mm = current->mm;
1828
1829         profile_munmap(addr);
1830
1831         down_write(&mm->mmap_sem);
1832         ret = do_munmap(mm, addr, len);
1833         up_write(&mm->mmap_sem);
1834         return ret;
1835 }
1836
1837 static inline void verify_mm_writelocked(struct mm_struct *mm)
1838 {
1839 #ifdef CONFIG_DEBUG_VM
1840         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1841                 WARN_ON(1);
1842                 up_read(&mm->mmap_sem);
1843         }
1844 #endif
1845 }
1846
1847 /*
1848  *  this is really a simplified "do_mmap".  it only handles
1849  *  anonymous maps.  eventually we may be able to do some
1850  *  brk-specific accounting here.
1851  */
1852 unsigned long do_brk(unsigned long addr, unsigned long len)
1853 {
1854         struct mm_struct * mm = current->mm;
1855         struct vm_area_struct * vma, * prev;
1856         unsigned long flags;
1857         struct rb_node ** rb_link, * rb_parent;
1858         pgoff_t pgoff = addr >> PAGE_SHIFT;
1859
1860         len = PAGE_ALIGN(len);
1861         if (!len)
1862                 return addr;
1863
1864         if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1865                 return -EINVAL;
1866
1867         /*
1868          * mlock MCL_FUTURE?
1869          */
1870         if (mm->def_flags & VM_LOCKED) {
1871                 unsigned long locked, lock_limit;
1872                 locked = len >> PAGE_SHIFT;
1873                 locked += mm->locked_vm;
1874                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1875                 lock_limit >>= PAGE_SHIFT;
1876                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1877                         return -EAGAIN;
1878         }
1879
1880         /*
1881          * mm->mmap_sem is required to protect against another thread
1882          * changing the mappings in case we sleep.
1883          */
1884         verify_mm_writelocked(mm);
1885
1886         /*
1887          * Clear old maps.  this also does some error checking for us
1888          */
1889  munmap_back:
1890         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1891         if (vma && vma->vm_start < addr + len) {
1892                 if (do_munmap(mm, addr, len))
1893                         return -ENOMEM;
1894                 goto munmap_back;
1895         }
1896
1897         /* Check against address space limits *after* clearing old maps... */
1898         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1899                 return -ENOMEM;
1900
1901         if (mm->map_count > sysctl_max_map_count)
1902                 return -ENOMEM;
1903
1904         if (security_vm_enough_memory(len >> PAGE_SHIFT))
1905                 return -ENOMEM;
1906
1907         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1908
1909         /* Can we just expand an old private anonymous mapping? */
1910         if (vma_merge(mm, prev, addr, addr + len, flags,
1911                                         NULL, NULL, pgoff, NULL))
1912                 goto out;
1913
1914         /*
1915          * create a vma struct for an anonymous mapping
1916          */
1917         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1918         if (!vma) {
1919                 vm_unacct_memory(len >> PAGE_SHIFT);
1920                 return -ENOMEM;
1921         }
1922         memset(vma, 0, sizeof(*vma));
1923
1924         vma->vm_mm = mm;
1925         vma->vm_start = addr;
1926         vma->vm_end = addr + len;
1927         vma->vm_pgoff = pgoff;
1928         vma->vm_flags = flags;
1929         vma->vm_page_prot = protection_map[flags & 0x0f];
1930         vma_link(mm, vma, prev, rb_link, rb_parent);
1931 out:
1932         mm->total_vm += len >> PAGE_SHIFT;
1933         if (flags & VM_LOCKED) {
1934                 mm->locked_vm += len >> PAGE_SHIFT;
1935                 make_pages_present(addr, addr + len);
1936         }
1937         return addr;
1938 }
1939
1940 EXPORT_SYMBOL(do_brk);
1941
1942 /* Release all mmaps. */
1943 void exit_mmap(struct mm_struct *mm)
1944 {
1945         struct mmu_gather *tlb;
1946         struct vm_area_struct *vma = mm->mmap;
1947         unsigned long nr_accounted = 0;
1948         unsigned long end;
1949
1950         lru_add_drain();
1951         flush_cache_mm(mm);
1952         tlb = tlb_gather_mmu(mm, 1);
1953         /* Don't update_hiwater_rss(mm) here, do_exit already did */
1954         /* Use -1 here to ensure all VMAs in the mm are unmapped */
1955         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
1956         vm_unacct_memory(nr_accounted);
1957         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
1958         tlb_finish_mmu(tlb, 0, end);
1959
1960         /*
1961          * Walk the list again, actually closing and freeing it,
1962          * with preemption enabled, without holding any MM locks.
1963          */
1964         while (vma)
1965                 vma = remove_vma(vma);
1966
1967         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
1968 }
1969
1970 /* Insert vm structure into process list sorted by address
1971  * and into the inode's i_mmap tree.  If vm_file is non-NULL
1972  * then i_mmap_lock is taken here.
1973  */
1974 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
1975 {
1976         struct vm_area_struct * __vma, * prev;
1977         struct rb_node ** rb_link, * rb_parent;
1978
1979         /*
1980          * The vm_pgoff of a purely anonymous vma should be irrelevant
1981          * until its first write fault, when page's anon_vma and index
1982          * are set.  But now set the vm_pgoff it will almost certainly
1983          * end up with (unless mremap moves it elsewhere before that
1984          * first wfault), so /proc/pid/maps tells a consistent story.
1985          *
1986          * By setting it to reflect the virtual start address of the
1987          * vma, merges and splits can happen in a seamless way, just
1988          * using the existing file pgoff checks and manipulations.
1989          * Similarly in do_mmap_pgoff and in do_brk.
1990          */
1991         if (!vma->vm_file) {
1992                 BUG_ON(vma->anon_vma);
1993                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
1994         }
1995         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
1996         if (__vma && __vma->vm_start < vma->vm_end)
1997                 return -ENOMEM;
1998         if ((vma->vm_flags & VM_ACCOUNT) &&
1999              security_vm_enough_memory(vma_pages(vma)))
2000                 return -ENOMEM;
2001         vma_link(mm, vma, prev, rb_link, rb_parent);
2002         return 0;
2003 }
2004
2005 /*
2006  * Copy the vma structure to a new location in the same mm,
2007  * prior to moving page table entries, to effect an mremap move.
2008  */
2009 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2010         unsigned long addr, unsigned long len, pgoff_t pgoff)
2011 {
2012         struct vm_area_struct *vma = *vmap;
2013         unsigned long vma_start = vma->vm_start;
2014         struct mm_struct *mm = vma->vm_mm;
2015         struct vm_area_struct *new_vma, *prev;
2016         struct rb_node **rb_link, *rb_parent;
2017         struct mempolicy *pol;
2018
2019         /*
2020          * If anonymous vma has not yet been faulted, update new pgoff
2021          * to match new location, to increase its chance of merging.
2022          */
2023         if (!vma->vm_file && !vma->anon_vma)
2024                 pgoff = addr >> PAGE_SHIFT;
2025
2026         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2027         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2028                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2029         if (new_vma) {
2030                 /*
2031                  * Source vma may have been merged into new_vma
2032                  */
2033                 if (vma_start >= new_vma->vm_start &&
2034                     vma_start < new_vma->vm_end)
2035                         *vmap = new_vma;
2036         } else {
2037                 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
2038                 if (new_vma) {
2039                         *new_vma = *vma;
2040                         pol = mpol_copy(vma_policy(vma));
2041                         if (IS_ERR(pol)) {
2042                                 kmem_cache_free(vm_area_cachep, new_vma);
2043                                 return NULL;
2044                         }
2045                         vma_set_policy(new_vma, pol);
2046                         new_vma->vm_start = addr;
2047                         new_vma->vm_end = addr + len;
2048                         new_vma->vm_pgoff = pgoff;
2049                         if (new_vma->vm_file)
2050                                 get_file(new_vma->vm_file);
2051                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2052                                 new_vma->vm_ops->open(new_vma);
2053                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2054                 }
2055         }
2056         return new_vma;
2057 }
2058
2059 /*
2060  * Return true if the calling process may expand its vm space by the passed
2061  * number of pages
2062  */
2063 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2064 {
2065         unsigned long cur = mm->total_vm;       /* pages */
2066         unsigned long lim;
2067
2068         lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2069
2070         if (cur + npages > lim)
2071                 return 0;
2072         return 1;
2073 }