8b8e05f07cdb3146d9f6d1776d45f1b7045b7491
[linux-3.10.git] / 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(sysctl_overcommit_memory);
159 EXPORT_SYMBOL(sysctl_overcommit_ratio);
160 EXPORT_SYMBOL(sysctl_max_map_count);
161 EXPORT_SYMBOL(vm_committed_space);
162 EXPORT_SYMBOL(__vm_enough_memory);
163
164 /*
165  * Requires inode->i_mapping->i_mmap_lock
166  */
167 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
168                 struct file *file, struct address_space *mapping)
169 {
170         if (vma->vm_flags & VM_DENYWRITE)
171                 atomic_inc(&file->f_dentry->d_inode->i_writecount);
172         if (vma->vm_flags & VM_SHARED)
173                 mapping->i_mmap_writable--;
174
175         flush_dcache_mmap_lock(mapping);
176         if (unlikely(vma->vm_flags & VM_NONLINEAR))
177                 list_del_init(&vma->shared.vm_set.list);
178         else
179                 vma_prio_tree_remove(vma, &mapping->i_mmap);
180         flush_dcache_mmap_unlock(mapping);
181 }
182
183 /*
184  * Remove one vm structure and free it.
185  */
186 static void remove_vm_struct(struct vm_area_struct *vma)
187 {
188         struct file *file = vma->vm_file;
189
190         might_sleep();
191         if (file) {
192                 struct address_space *mapping = file->f_mapping;
193                 spin_lock(&mapping->i_mmap_lock);
194                 __remove_shared_vm_struct(vma, file, mapping);
195                 spin_unlock(&mapping->i_mmap_lock);
196         }
197         if (vma->vm_ops && vma->vm_ops->close)
198                 vma->vm_ops->close(vma);
199         if (file)
200                 fput(file);
201         anon_vma_unlink(vma);
202         mpol_free(vma_policy(vma));
203         kmem_cache_free(vm_area_cachep, vma);
204 }
205
206 asmlinkage unsigned long sys_brk(unsigned long brk)
207 {
208         unsigned long rlim, retval;
209         unsigned long newbrk, oldbrk;
210         struct mm_struct *mm = current->mm;
211
212         down_write(&mm->mmap_sem);
213
214         if (brk < mm->end_code)
215                 goto out;
216         newbrk = PAGE_ALIGN(brk);
217         oldbrk = PAGE_ALIGN(mm->brk);
218         if (oldbrk == newbrk)
219                 goto set_brk;
220
221         /* Always allow shrinking brk. */
222         if (brk <= mm->brk) {
223                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
224                         goto set_brk;
225                 goto out;
226         }
227
228         /* Check against rlimit.. */
229         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
230         if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
231                 goto out;
232
233         /* Check against existing mmap mappings. */
234         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
235                 goto out;
236
237         /* Ok, looks good - let it rip. */
238         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
239                 goto out;
240 set_brk:
241         mm->brk = brk;
242 out:
243         retval = mm->brk;
244         up_write(&mm->mmap_sem);
245         return retval;
246 }
247
248 #ifdef DEBUG_MM_RB
249 static int browse_rb(struct rb_root *root)
250 {
251         int i = 0, j;
252         struct rb_node *nd, *pn = NULL;
253         unsigned long prev = 0, pend = 0;
254
255         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
256                 struct vm_area_struct *vma;
257                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
258                 if (vma->vm_start < prev)
259                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
260                 if (vma->vm_start < pend)
261                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
262                 if (vma->vm_start > vma->vm_end)
263                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
264                 i++;
265                 pn = nd;
266         }
267         j = 0;
268         for (nd = pn; nd; nd = rb_prev(nd)) {
269                 j++;
270         }
271         if (i != j)
272                 printk("backwards %d, forwards %d\n", j, i), i = 0;
273         return i;
274 }
275
276 void validate_mm(struct mm_struct *mm)
277 {
278         int bug = 0;
279         int i = 0;
280         struct vm_area_struct *tmp = mm->mmap;
281         while (tmp) {
282                 tmp = tmp->vm_next;
283                 i++;
284         }
285         if (i != mm->map_count)
286                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
287         i = browse_rb(&mm->mm_rb);
288         if (i != mm->map_count)
289                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
290         if (bug)
291                 BUG();
292 }
293 #else
294 #define validate_mm(mm) do { } while (0)
295 #endif
296
297 static struct vm_area_struct *
298 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
299                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
300                 struct rb_node ** rb_parent)
301 {
302         struct vm_area_struct * vma;
303         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
304
305         __rb_link = &mm->mm_rb.rb_node;
306         rb_prev = __rb_parent = NULL;
307         vma = NULL;
308
309         while (*__rb_link) {
310                 struct vm_area_struct *vma_tmp;
311
312                 __rb_parent = *__rb_link;
313                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
314
315                 if (vma_tmp->vm_end > addr) {
316                         vma = vma_tmp;
317                         if (vma_tmp->vm_start <= addr)
318                                 return vma;
319                         __rb_link = &__rb_parent->rb_left;
320                 } else {
321                         rb_prev = __rb_parent;
322                         __rb_link = &__rb_parent->rb_right;
323                 }
324         }
325
326         *pprev = NULL;
327         if (rb_prev)
328                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
329         *rb_link = __rb_link;
330         *rb_parent = __rb_parent;
331         return vma;
332 }
333
334 static inline void
335 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
336                 struct vm_area_struct *prev, struct rb_node *rb_parent)
337 {
338         if (prev) {
339                 vma->vm_next = prev->vm_next;
340                 prev->vm_next = vma;
341         } else {
342                 mm->mmap = vma;
343                 if (rb_parent)
344                         vma->vm_next = rb_entry(rb_parent,
345                                         struct vm_area_struct, vm_rb);
346                 else
347                         vma->vm_next = NULL;
348         }
349 }
350
351 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
352                 struct rb_node **rb_link, struct rb_node *rb_parent)
353 {
354         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
355         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
356 }
357
358 static inline void __vma_link_file(struct vm_area_struct *vma)
359 {
360         struct file * file;
361
362         file = vma->vm_file;
363         if (file) {
364                 struct address_space *mapping = file->f_mapping;
365
366                 if (vma->vm_flags & VM_DENYWRITE)
367                         atomic_dec(&file->f_dentry->d_inode->i_writecount);
368                 if (vma->vm_flags & VM_SHARED)
369                         mapping->i_mmap_writable++;
370
371                 flush_dcache_mmap_lock(mapping);
372                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
373                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
374                 else
375                         vma_prio_tree_insert(vma, &mapping->i_mmap);
376                 flush_dcache_mmap_unlock(mapping);
377         }
378 }
379
380 static void
381 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
382         struct vm_area_struct *prev, struct rb_node **rb_link,
383         struct rb_node *rb_parent)
384 {
385         __vma_link_list(mm, vma, prev, rb_parent);
386         __vma_link_rb(mm, vma, rb_link, rb_parent);
387         __anon_vma_link(vma);
388 }
389
390 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
391                         struct vm_area_struct *prev, struct rb_node **rb_link,
392                         struct rb_node *rb_parent)
393 {
394         struct address_space *mapping = NULL;
395
396         if (vma->vm_file)
397                 mapping = vma->vm_file->f_mapping;
398
399         if (mapping) {
400                 spin_lock(&mapping->i_mmap_lock);
401                 vma->vm_truncate_count = mapping->truncate_count;
402         }
403         anon_vma_lock(vma);
404
405         __vma_link(mm, vma, prev, rb_link, rb_parent);
406         __vma_link_file(vma);
407
408         anon_vma_unlock(vma);
409         if (mapping)
410                 spin_unlock(&mapping->i_mmap_lock);
411
412         mm->map_count++;
413         validate_mm(mm);
414 }
415
416 /*
417  * Helper for vma_adjust in the split_vma insert case:
418  * insert vm structure into list and rbtree and anon_vma,
419  * but it has already been inserted into prio_tree earlier.
420  */
421 static void
422 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
423 {
424         struct vm_area_struct * __vma, * prev;
425         struct rb_node ** rb_link, * rb_parent;
426
427         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
428         if (__vma && __vma->vm_start < vma->vm_end)
429                 BUG();
430         __vma_link(mm, vma, prev, rb_link, rb_parent);
431         mm->map_count++;
432 }
433
434 static inline void
435 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
436                 struct vm_area_struct *prev)
437 {
438         prev->vm_next = vma->vm_next;
439         rb_erase(&vma->vm_rb, &mm->mm_rb);
440         if (mm->mmap_cache == vma)
441                 mm->mmap_cache = prev;
442 }
443
444 /*
445  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
446  * is already present in an i_mmap tree without adjusting the tree.
447  * The following helper function should be used when such adjustments
448  * are necessary.  The "insert" vma (if any) is to be inserted
449  * before we drop the necessary locks.
450  */
451 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
452         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
453 {
454         struct mm_struct *mm = vma->vm_mm;
455         struct vm_area_struct *next = vma->vm_next;
456         struct vm_area_struct *importer = NULL;
457         struct address_space *mapping = NULL;
458         struct prio_tree_root *root = NULL;
459         struct file *file = vma->vm_file;
460         struct anon_vma *anon_vma = NULL;
461         long adjust_next = 0;
462         int remove_next = 0;
463
464         if (next && !insert) {
465                 if (end >= next->vm_end) {
466                         /*
467                          * vma expands, overlapping all the next, and
468                          * perhaps the one after too (mprotect case 6).
469                          */
470 again:                  remove_next = 1 + (end > next->vm_end);
471                         end = next->vm_end;
472                         anon_vma = next->anon_vma;
473                         importer = vma;
474                 } else if (end > next->vm_start) {
475                         /*
476                          * vma expands, overlapping part of the next:
477                          * mprotect case 5 shifting the boundary up.
478                          */
479                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
480                         anon_vma = next->anon_vma;
481                         importer = vma;
482                 } else if (end < vma->vm_end) {
483                         /*
484                          * vma shrinks, and !insert tells it's not
485                          * split_vma inserting another: so it must be
486                          * mprotect case 4 shifting the boundary down.
487                          */
488                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
489                         anon_vma = next->anon_vma;
490                         importer = next;
491                 }
492         }
493
494         if (file) {
495                 mapping = file->f_mapping;
496                 if (!(vma->vm_flags & VM_NONLINEAR))
497                         root = &mapping->i_mmap;
498                 spin_lock(&mapping->i_mmap_lock);
499                 if (importer &&
500                     vma->vm_truncate_count != next->vm_truncate_count) {
501                         /*
502                          * unmap_mapping_range might be in progress:
503                          * ensure that the expanding vma is rescanned.
504                          */
505                         importer->vm_truncate_count = 0;
506                 }
507                 if (insert) {
508                         insert->vm_truncate_count = vma->vm_truncate_count;
509                         /*
510                          * Put into prio_tree now, so instantiated pages
511                          * are visible to arm/parisc __flush_dcache_page
512                          * throughout; but we cannot insert into address
513                          * space until vma start or end is updated.
514                          */
515                         __vma_link_file(insert);
516                 }
517         }
518
519         /*
520          * When changing only vma->vm_end, we don't really need
521          * anon_vma lock: but is that case worth optimizing out?
522          */
523         if (vma->anon_vma)
524                 anon_vma = vma->anon_vma;
525         if (anon_vma) {
526                 spin_lock(&anon_vma->lock);
527                 /*
528                  * Easily overlooked: when mprotect shifts the boundary,
529                  * make sure the expanding vma has anon_vma set if the
530                  * shrinking vma had, to cover any anon pages imported.
531                  */
532                 if (importer && !importer->anon_vma) {
533                         importer->anon_vma = anon_vma;
534                         __anon_vma_link(importer);
535                 }
536         }
537
538         if (root) {
539                 flush_dcache_mmap_lock(mapping);
540                 vma_prio_tree_remove(vma, root);
541                 if (adjust_next)
542                         vma_prio_tree_remove(next, root);
543         }
544
545         vma->vm_start = start;
546         vma->vm_end = end;
547         vma->vm_pgoff = pgoff;
548         if (adjust_next) {
549                 next->vm_start += adjust_next << PAGE_SHIFT;
550                 next->vm_pgoff += adjust_next;
551         }
552
553         if (root) {
554                 if (adjust_next)
555                         vma_prio_tree_insert(next, root);
556                 vma_prio_tree_insert(vma, root);
557                 flush_dcache_mmap_unlock(mapping);
558         }
559
560         if (remove_next) {
561                 /*
562                  * vma_merge has merged next into vma, and needs
563                  * us to remove next before dropping the locks.
564                  */
565                 __vma_unlink(mm, next, vma);
566                 if (file)
567                         __remove_shared_vm_struct(next, file, mapping);
568                 if (next->anon_vma)
569                         __anon_vma_merge(vma, next);
570         } else if (insert) {
571                 /*
572                  * split_vma has split insert from vma, and needs
573                  * us to insert it before dropping the locks
574                  * (it may either follow vma or precede it).
575                  */
576                 __insert_vm_struct(mm, insert);
577         }
578
579         if (anon_vma)
580                 spin_unlock(&anon_vma->lock);
581         if (mapping)
582                 spin_unlock(&mapping->i_mmap_lock);
583
584         if (remove_next) {
585                 if (file)
586                         fput(file);
587                 mm->map_count--;
588                 mpol_free(vma_policy(next));
589                 kmem_cache_free(vm_area_cachep, next);
590                 /*
591                  * In mprotect's case 6 (see comments on vma_merge),
592                  * we must remove another next too. It would clutter
593                  * up the code too much to do both in one go.
594                  */
595                 if (remove_next == 2) {
596                         next = vma->vm_next;
597                         goto again;
598                 }
599         }
600
601         validate_mm(mm);
602 }
603
604 /*
605  * If the vma has a ->close operation then the driver probably needs to release
606  * per-vma resources, so we don't attempt to merge those.
607  */
608 #define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)
609
610 static inline int is_mergeable_vma(struct vm_area_struct *vma,
611                         struct file *file, unsigned long vm_flags)
612 {
613         if (vma->vm_flags != vm_flags)
614                 return 0;
615         if (vma->vm_file != file)
616                 return 0;
617         if (vma->vm_ops && vma->vm_ops->close)
618                 return 0;
619         return 1;
620 }
621
622 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
623                                         struct anon_vma *anon_vma2)
624 {
625         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
626 }
627
628 /*
629  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
630  * in front of (at a lower virtual address and file offset than) the vma.
631  *
632  * We cannot merge two vmas if they have differently assigned (non-NULL)
633  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
634  *
635  * We don't check here for the merged mmap wrapping around the end of pagecache
636  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
637  * wrap, nor mmaps which cover the final page at index -1UL.
638  */
639 static int
640 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
641         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
642 {
643         if (is_mergeable_vma(vma, file, vm_flags) &&
644             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
645                 if (vma->vm_pgoff == vm_pgoff)
646                         return 1;
647         }
648         return 0;
649 }
650
651 /*
652  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
653  * beyond (at a higher virtual address and file offset than) the vma.
654  *
655  * We cannot merge two vmas if they have differently assigned (non-NULL)
656  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
657  */
658 static int
659 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
660         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
661 {
662         if (is_mergeable_vma(vma, file, vm_flags) &&
663             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
664                 pgoff_t vm_pglen;
665                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
666                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
667                         return 1;
668         }
669         return 0;
670 }
671
672 /*
673  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
674  * whether that can be merged with its predecessor or its successor.
675  * Or both (it neatly fills a hole).
676  *
677  * In most cases - when called for mmap, brk or mremap - [addr,end) is
678  * certain not to be mapped by the time vma_merge is called; but when
679  * called for mprotect, it is certain to be already mapped (either at
680  * an offset within prev, or at the start of next), and the flags of
681  * this area are about to be changed to vm_flags - and the no-change
682  * case has already been eliminated.
683  *
684  * The following mprotect cases have to be considered, where AAAA is
685  * the area passed down from mprotect_fixup, never extending beyond one
686  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
687  *
688  *     AAAA             AAAA                AAAA          AAAA
689  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
690  *    cannot merge    might become    might become    might become
691  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
692  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
693  *    mremap move:                                    PPPPNNNNNNNN 8
694  *        AAAA
695  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
696  *    might become    case 1 below    case 2 below    case 3 below
697  *
698  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
699  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
700  */
701 struct vm_area_struct *vma_merge(struct mm_struct *mm,
702                         struct vm_area_struct *prev, unsigned long addr,
703                         unsigned long end, unsigned long vm_flags,
704                         struct anon_vma *anon_vma, struct file *file,
705                         pgoff_t pgoff, struct mempolicy *policy)
706 {
707         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
708         struct vm_area_struct *area, *next;
709
710         /*
711          * We later require that vma->vm_flags == vm_flags,
712          * so this tests vma->vm_flags & VM_SPECIAL, too.
713          */
714         if (vm_flags & VM_SPECIAL)
715                 return NULL;
716
717         if (prev)
718                 next = prev->vm_next;
719         else
720                 next = mm->mmap;
721         area = next;
722         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
723                 next = next->vm_next;
724
725         /*
726          * Can it merge with the predecessor?
727          */
728         if (prev && prev->vm_end == addr &&
729                         mpol_equal(vma_policy(prev), policy) &&
730                         can_vma_merge_after(prev, vm_flags,
731                                                 anon_vma, file, pgoff)) {
732                 /*
733                  * OK, it can.  Can we now merge in the successor as well?
734                  */
735                 if (next && end == next->vm_start &&
736                                 mpol_equal(policy, vma_policy(next)) &&
737                                 can_vma_merge_before(next, vm_flags,
738                                         anon_vma, file, pgoff+pglen) &&
739                                 is_mergeable_anon_vma(prev->anon_vma,
740                                                       next->anon_vma)) {
741                                                         /* cases 1, 6 */
742                         vma_adjust(prev, prev->vm_start,
743                                 next->vm_end, prev->vm_pgoff, NULL);
744                 } else                                  /* cases 2, 5, 7 */
745                         vma_adjust(prev, prev->vm_start,
746                                 end, prev->vm_pgoff, NULL);
747                 return prev;
748         }
749
750         /*
751          * Can this new request be merged in front of next?
752          */
753         if (next && end == next->vm_start &&
754                         mpol_equal(policy, vma_policy(next)) &&
755                         can_vma_merge_before(next, vm_flags,
756                                         anon_vma, file, pgoff+pglen)) {
757                 if (prev && addr < prev->vm_end)        /* case 4 */
758                         vma_adjust(prev, prev->vm_start,
759                                 addr, prev->vm_pgoff, NULL);
760                 else                                    /* cases 3, 8 */
761                         vma_adjust(area, addr, next->vm_end,
762                                 next->vm_pgoff - pglen, NULL);
763                 return area;
764         }
765
766         return NULL;
767 }
768
769 /*
770  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
771  * neighbouring vmas for a suitable anon_vma, before it goes off
772  * to allocate a new anon_vma.  It checks because a repetitive
773  * sequence of mprotects and faults may otherwise lead to distinct
774  * anon_vmas being allocated, preventing vma merge in subsequent
775  * mprotect.
776  */
777 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
778 {
779         struct vm_area_struct *near;
780         unsigned long vm_flags;
781
782         near = vma->vm_next;
783         if (!near)
784                 goto try_prev;
785
786         /*
787          * Since only mprotect tries to remerge vmas, match flags
788          * which might be mprotected into each other later on.
789          * Neither mlock nor madvise tries to remerge at present,
790          * so leave their flags as obstructing a merge.
791          */
792         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
793         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
794
795         if (near->anon_vma && vma->vm_end == near->vm_start &&
796                         mpol_equal(vma_policy(vma), vma_policy(near)) &&
797                         can_vma_merge_before(near, vm_flags,
798                                 NULL, vma->vm_file, vma->vm_pgoff +
799                                 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
800                 return near->anon_vma;
801 try_prev:
802         /*
803          * It is potentially slow to have to call find_vma_prev here.
804          * But it's only on the first write fault on the vma, not
805          * every time, and we could devise a way to avoid it later
806          * (e.g. stash info in next's anon_vma_node when assigning
807          * an anon_vma, or when trying vma_merge).  Another time.
808          */
809         if (find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma)
810                 BUG();
811         if (!near)
812                 goto none;
813
814         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
815         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
816
817         if (near->anon_vma && near->vm_end == vma->vm_start &&
818                         mpol_equal(vma_policy(near), vma_policy(vma)) &&
819                         can_vma_merge_after(near, vm_flags,
820                                 NULL, vma->vm_file, vma->vm_pgoff))
821                 return near->anon_vma;
822 none:
823         /*
824          * There's no absolute need to look only at touching neighbours:
825          * we could search further afield for "compatible" anon_vmas.
826          * But it would probably just be a waste of time searching,
827          * or lead to too many vmas hanging off the same anon_vma.
828          * We're trying to allow mprotect remerging later on,
829          * not trying to minimize memory used for anon_vmas.
830          */
831         return NULL;
832 }
833
834 #ifdef CONFIG_PROC_FS
835 void __vm_stat_account(struct mm_struct *mm, unsigned long flags,
836                                                 struct file *file, long pages)
837 {
838         const unsigned long stack_flags
839                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
840
841 #ifdef CONFIG_HUGETLB
842         if (flags & VM_HUGETLB) {
843                 if (!(flags & VM_DONTCOPY))
844                         mm->shared_vm += pages;
845                 return;
846         }
847 #endif /* CONFIG_HUGETLB */
848
849         if (file) {
850                 mm->shared_vm += pages;
851                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
852                         mm->exec_vm += pages;
853         } else if (flags & stack_flags)
854                 mm->stack_vm += pages;
855         if (flags & (VM_RESERVED|VM_IO))
856                 mm->reserved_vm += pages;
857 }
858 #endif /* CONFIG_PROC_FS */
859
860 /*
861  * The caller must hold down_write(current->mm->mmap_sem).
862  */
863
864 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
865                         unsigned long len, unsigned long prot,
866                         unsigned long flags, unsigned long pgoff)
867 {
868         struct mm_struct * mm = current->mm;
869         struct vm_area_struct * vma, * prev;
870         struct inode *inode;
871         unsigned int vm_flags;
872         int correct_wcount = 0;
873         int error;
874         struct rb_node ** rb_link, * rb_parent;
875         int accountable = 1;
876         unsigned long charged = 0, reqprot = prot;
877
878         if (file) {
879                 if (is_file_hugepages(file))
880                         accountable = 0;
881
882                 if (!file->f_op || !file->f_op->mmap)
883                         return -ENODEV;
884
885                 if ((prot & PROT_EXEC) &&
886                     (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
887                         return -EPERM;
888         }
889         /*
890          * Does the application expect PROT_READ to imply PROT_EXEC?
891          *
892          * (the exception is when the underlying filesystem is noexec
893          *  mounted, in which case we dont add PROT_EXEC.)
894          */
895         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
896                 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
897                         prot |= PROT_EXEC;
898
899         if (!len)
900                 return -EINVAL;
901
902         /* Careful about overflows.. */
903         len = PAGE_ALIGN(len);
904         if (!len || len > TASK_SIZE)
905                 return -ENOMEM;
906
907         /* offset overflow? */
908         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
909                return -EOVERFLOW;
910
911         /* Too many mappings? */
912         if (mm->map_count > sysctl_max_map_count)
913                 return -ENOMEM;
914
915         /* Obtain the address to map to. we verify (or select) it and ensure
916          * that it represents a valid section of the address space.
917          */
918         addr = get_unmapped_area(file, addr, len, pgoff, flags);
919         if (addr & ~PAGE_MASK)
920                 return addr;
921
922         /* Do simple checking here so the lower-level routines won't have
923          * to. we assume access permissions have been handled by the open
924          * of the memory object, so we don't do any here.
925          */
926         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
927                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
928
929         if (flags & MAP_LOCKED) {
930                 if (!can_do_mlock())
931                         return -EPERM;
932                 vm_flags |= VM_LOCKED;
933         }
934         /* mlock MCL_FUTURE? */
935         if (vm_flags & VM_LOCKED) {
936                 unsigned long locked, lock_limit;
937                 locked = len >> PAGE_SHIFT;
938                 locked += mm->locked_vm;
939                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
940                 lock_limit >>= PAGE_SHIFT;
941                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
942                         return -EAGAIN;
943         }
944
945         inode = file ? file->f_dentry->d_inode : NULL;
946
947         if (file) {
948                 switch (flags & MAP_TYPE) {
949                 case MAP_SHARED:
950                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
951                                 return -EACCES;
952
953                         /*
954                          * Make sure we don't allow writing to an append-only
955                          * file..
956                          */
957                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
958                                 return -EACCES;
959
960                         /*
961                          * Make sure there are no mandatory locks on the file.
962                          */
963                         if (locks_verify_locked(inode))
964                                 return -EAGAIN;
965
966                         vm_flags |= VM_SHARED | VM_MAYSHARE;
967                         if (!(file->f_mode & FMODE_WRITE))
968                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
969
970                         /* fall through */
971                 case MAP_PRIVATE:
972                         if (!(file->f_mode & FMODE_READ))
973                                 return -EACCES;
974                         break;
975
976                 default:
977                         return -EINVAL;
978                 }
979         } else {
980                 switch (flags & MAP_TYPE) {
981                 case MAP_SHARED:
982                         vm_flags |= VM_SHARED | VM_MAYSHARE;
983                         break;
984                 case MAP_PRIVATE:
985                         /*
986                          * Set pgoff according to addr for anon_vma.
987                          */
988                         pgoff = addr >> PAGE_SHIFT;
989                         break;
990                 default:
991                         return -EINVAL;
992                 }
993         }
994
995         error = security_file_mmap(file, reqprot, prot, flags);
996         if (error)
997                 return error;
998                 
999         /* Clear old maps */
1000         error = -ENOMEM;
1001 munmap_back:
1002         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1003         if (vma && vma->vm_start < addr + len) {
1004                 if (do_munmap(mm, addr, len))
1005                         return -ENOMEM;
1006                 goto munmap_back;
1007         }
1008
1009         /* Check against address space limit. */
1010         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1011                 return -ENOMEM;
1012
1013         if (accountable && (!(flags & MAP_NORESERVE) ||
1014                             sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1015                 if (vm_flags & VM_SHARED) {
1016                         /* Check memory availability in shmem_file_setup? */
1017                         vm_flags |= VM_ACCOUNT;
1018                 } else if (vm_flags & VM_WRITE) {
1019                         /*
1020                          * Private writable mapping: check memory availability
1021                          */
1022                         charged = len >> PAGE_SHIFT;
1023                         if (security_vm_enough_memory(charged))
1024                                 return -ENOMEM;
1025                         vm_flags |= VM_ACCOUNT;
1026                 }
1027         }
1028
1029         /*
1030          * Can we just expand an old private anonymous mapping?
1031          * The VM_SHARED test is necessary because shmem_zero_setup
1032          * will create the file object for a shared anonymous map below.
1033          */
1034         if (!file && !(vm_flags & VM_SHARED) &&
1035             vma_merge(mm, prev, addr, addr + len, vm_flags,
1036                                         NULL, NULL, pgoff, NULL))
1037                 goto out;
1038
1039         /*
1040          * Determine the object being mapped and call the appropriate
1041          * specific mapper. the address has already been validated, but
1042          * not unmapped, but the maps are removed from the list.
1043          */
1044         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1045         if (!vma) {
1046                 error = -ENOMEM;
1047                 goto unacct_error;
1048         }
1049         memset(vma, 0, sizeof(*vma));
1050
1051         vma->vm_mm = mm;
1052         vma->vm_start = addr;
1053         vma->vm_end = addr + len;
1054         vma->vm_flags = vm_flags;
1055         vma->vm_page_prot = protection_map[vm_flags & 0x0f];
1056         vma->vm_pgoff = pgoff;
1057
1058         if (file) {
1059                 error = -EINVAL;
1060                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1061                         goto free_vma;
1062                 if (vm_flags & VM_DENYWRITE) {
1063                         error = deny_write_access(file);
1064                         if (error)
1065                                 goto free_vma;
1066                         correct_wcount = 1;
1067                 }
1068                 vma->vm_file = file;
1069                 get_file(file);
1070                 error = file->f_op->mmap(file, vma);
1071                 if (error)
1072                         goto unmap_and_free_vma;
1073         } else if (vm_flags & VM_SHARED) {
1074                 error = shmem_zero_setup(vma);
1075                 if (error)
1076                         goto free_vma;
1077         }
1078
1079         /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1080          * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1081          * that memory reservation must be checked; but that reservation
1082          * belongs to shared memory object, not to vma: so now clear it.
1083          */
1084         if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1085                 vma->vm_flags &= ~VM_ACCOUNT;
1086
1087         /* Can addr have changed??
1088          *
1089          * Answer: Yes, several device drivers can do it in their
1090          *         f_op->mmap method. -DaveM
1091          */
1092         addr = vma->vm_start;
1093         pgoff = vma->vm_pgoff;
1094         vm_flags = vma->vm_flags;
1095
1096         if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1097                         vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1098                 file = vma->vm_file;
1099                 vma_link(mm, vma, prev, rb_link, rb_parent);
1100                 if (correct_wcount)
1101                         atomic_inc(&inode->i_writecount);
1102         } else {
1103                 if (file) {
1104                         if (correct_wcount)
1105                                 atomic_inc(&inode->i_writecount);
1106                         fput(file);
1107                 }
1108                 mpol_free(vma_policy(vma));
1109                 kmem_cache_free(vm_area_cachep, vma);
1110         }
1111 out:    
1112         mm->total_vm += len >> PAGE_SHIFT;
1113         __vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1114         if (vm_flags & VM_LOCKED) {
1115                 mm->locked_vm += len >> PAGE_SHIFT;
1116                 make_pages_present(addr, addr + len);
1117         }
1118         if (flags & MAP_POPULATE) {
1119                 up_write(&mm->mmap_sem);
1120                 sys_remap_file_pages(addr, len, 0,
1121                                         pgoff, flags & MAP_NONBLOCK);
1122                 down_write(&mm->mmap_sem);
1123         }
1124         return addr;
1125
1126 unmap_and_free_vma:
1127         if (correct_wcount)
1128                 atomic_inc(&inode->i_writecount);
1129         vma->vm_file = NULL;
1130         fput(file);
1131
1132         /* Undo any partial mapping done by a device driver. */
1133         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1134         charged = 0;
1135 free_vma:
1136         kmem_cache_free(vm_area_cachep, vma);
1137 unacct_error:
1138         if (charged)
1139                 vm_unacct_memory(charged);
1140         return error;
1141 }
1142
1143 EXPORT_SYMBOL(do_mmap_pgoff);
1144
1145 /* Get an address range which is currently unmapped.
1146  * For shmat() with addr=0.
1147  *
1148  * Ugly calling convention alert:
1149  * Return value with the low bits set means error value,
1150  * ie
1151  *      if (ret & ~PAGE_MASK)
1152  *              error = ret;
1153  *
1154  * This function "knows" that -ENOMEM has the bits set.
1155  */
1156 #ifndef HAVE_ARCH_UNMAPPED_AREA
1157 unsigned long
1158 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1159                 unsigned long len, unsigned long pgoff, unsigned long flags)
1160 {
1161         struct mm_struct *mm = current->mm;
1162         struct vm_area_struct *vma;
1163         unsigned long start_addr;
1164
1165         if (len > TASK_SIZE)
1166                 return -ENOMEM;
1167
1168         if (addr) {
1169                 addr = PAGE_ALIGN(addr);
1170                 vma = find_vma(mm, addr);
1171                 if (TASK_SIZE - len >= addr &&
1172                     (!vma || addr + len <= vma->vm_start))
1173                         return addr;
1174         }
1175         if (len > mm->cached_hole_size) {
1176                 start_addr = addr = mm->free_area_cache;
1177         } else {
1178                 start_addr = addr = TASK_UNMAPPED_BASE;
1179                 mm->cached_hole_size = 0;
1180         }
1181
1182 full_search:
1183         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1184                 /* At this point:  (!vma || addr < vma->vm_end). */
1185                 if (TASK_SIZE - len < addr) {
1186                         /*
1187                          * Start a new search - just in case we missed
1188                          * some holes.
1189                          */
1190                         if (start_addr != TASK_UNMAPPED_BASE) {
1191                                 addr = TASK_UNMAPPED_BASE;
1192                                 start_addr = addr;
1193                                 mm->cached_hole_size = 0;
1194                                 goto full_search;
1195                         }
1196                         return -ENOMEM;
1197                 }
1198                 if (!vma || addr + len <= vma->vm_start) {
1199                         /*
1200                          * Remember the place where we stopped the search:
1201                          */
1202                         mm->free_area_cache = addr + len;
1203                         return addr;
1204                 }
1205                 if (addr + mm->cached_hole_size < vma->vm_start)
1206                         mm->cached_hole_size = vma->vm_start - addr;
1207                 addr = vma->vm_end;
1208         }
1209 }
1210 #endif  
1211
1212 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1213 {
1214         /*
1215          * Is this a new hole at the lowest possible address?
1216          */
1217         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1218                 mm->free_area_cache = addr;
1219                 mm->cached_hole_size = ~0UL;
1220         }
1221 }
1222
1223 /*
1224  * This mmap-allocator allocates new areas top-down from below the
1225  * stack's low limit (the base):
1226  */
1227 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1228 unsigned long
1229 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1230                           const unsigned long len, const unsigned long pgoff,
1231                           const unsigned long flags)
1232 {
1233         struct vm_area_struct *vma;
1234         struct mm_struct *mm = current->mm;
1235         unsigned long addr = addr0;
1236
1237         /* requested length too big for entire address space */
1238         if (len > TASK_SIZE)
1239                 return -ENOMEM;
1240
1241         /* requesting a specific address */
1242         if (addr) {
1243                 addr = PAGE_ALIGN(addr);
1244                 vma = find_vma(mm, addr);
1245                 if (TASK_SIZE - len >= addr &&
1246                                 (!vma || addr + len <= vma->vm_start))
1247                         return addr;
1248         }
1249
1250         /* check if free_area_cache is useful for us */
1251         if (len <= mm->cached_hole_size) {
1252                 mm->cached_hole_size = 0;
1253                 mm->free_area_cache = mm->mmap_base;
1254         }
1255
1256         /* either no address requested or can't fit in requested address hole */
1257         addr = mm->free_area_cache;
1258
1259         /* make sure it can fit in the remaining address space */
1260         if (addr > len) {
1261                 vma = find_vma(mm, addr-len);
1262                 if (!vma || addr <= vma->vm_start)
1263                         /* remember the address as a hint for next time */
1264                         return (mm->free_area_cache = addr-len);
1265         }
1266
1267         if (mm->mmap_base < len)
1268                 goto bottomup;
1269
1270         addr = mm->mmap_base-len;
1271
1272         do {
1273                 /*
1274                  * Lookup failure means no vma is above this address,
1275                  * else if new region fits below vma->vm_start,
1276                  * return with success:
1277                  */
1278                 vma = find_vma(mm, addr);
1279                 if (!vma || addr+len <= vma->vm_start)
1280                         /* remember the address as a hint for next time */
1281                         return (mm->free_area_cache = addr);
1282
1283                 /* remember the largest hole we saw so far */
1284                 if (addr + mm->cached_hole_size < vma->vm_start)
1285                         mm->cached_hole_size = vma->vm_start - addr;
1286
1287                 /* try just below the current vma->vm_start */
1288                 addr = vma->vm_start-len;
1289         } while (len < vma->vm_start);
1290
1291 bottomup:
1292         /*
1293          * A failed mmap() very likely causes application failure,
1294          * so fall back to the bottom-up function here. This scenario
1295          * can happen with large stack limits and large mmap()
1296          * allocations.
1297          */
1298         mm->cached_hole_size = ~0UL;
1299         mm->free_area_cache = TASK_UNMAPPED_BASE;
1300         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1301         /*
1302          * Restore the topdown base:
1303          */
1304         mm->free_area_cache = mm->mmap_base;
1305         mm->cached_hole_size = ~0UL;
1306
1307         return addr;
1308 }
1309 #endif
1310
1311 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1312 {
1313         /*
1314          * Is this a new hole at the highest possible address?
1315          */
1316         if (addr > mm->free_area_cache)
1317                 mm->free_area_cache = addr;
1318
1319         /* dont allow allocations above current base */
1320         if (mm->free_area_cache > mm->mmap_base)
1321                 mm->free_area_cache = mm->mmap_base;
1322 }
1323
1324 unsigned long
1325 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1326                 unsigned long pgoff, unsigned long flags)
1327 {
1328         unsigned long ret;
1329
1330         if (!(flags & MAP_FIXED)) {
1331                 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1332
1333                 get_area = current->mm->get_unmapped_area;
1334                 if (file && file->f_op && file->f_op->get_unmapped_area)
1335                         get_area = file->f_op->get_unmapped_area;
1336                 addr = get_area(file, addr, len, pgoff, flags);
1337                 if (IS_ERR_VALUE(addr))
1338                         return addr;
1339         }
1340
1341         if (addr > TASK_SIZE - len)
1342                 return -ENOMEM;
1343         if (addr & ~PAGE_MASK)
1344                 return -EINVAL;
1345         if (file && is_file_hugepages(file))  {
1346                 /*
1347                  * Check if the given range is hugepage aligned, and
1348                  * can be made suitable for hugepages.
1349                  */
1350                 ret = prepare_hugepage_range(addr, len);
1351         } else {
1352                 /*
1353                  * Ensure that a normal request is not falling in a
1354                  * reserved hugepage range.  For some archs like IA-64,
1355                  * there is a separate region for hugepages.
1356                  */
1357                 ret = is_hugepage_only_range(current->mm, addr, len);
1358         }
1359         if (ret)
1360                 return -EINVAL;
1361         return addr;
1362 }
1363
1364 EXPORT_SYMBOL(get_unmapped_area);
1365
1366 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1367 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1368 {
1369         struct vm_area_struct *vma = NULL;
1370
1371         if (mm) {
1372                 /* Check the cache first. */
1373                 /* (Cache hit rate is typically around 35%.) */
1374                 vma = mm->mmap_cache;
1375                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1376                         struct rb_node * rb_node;
1377
1378                         rb_node = mm->mm_rb.rb_node;
1379                         vma = NULL;
1380
1381                         while (rb_node) {
1382                                 struct vm_area_struct * vma_tmp;
1383
1384                                 vma_tmp = rb_entry(rb_node,
1385                                                 struct vm_area_struct, vm_rb);
1386
1387                                 if (vma_tmp->vm_end > addr) {
1388                                         vma = vma_tmp;
1389                                         if (vma_tmp->vm_start <= addr)
1390                                                 break;
1391                                         rb_node = rb_node->rb_left;
1392                                 } else
1393                                         rb_node = rb_node->rb_right;
1394                         }
1395                         if (vma)
1396                                 mm->mmap_cache = vma;
1397                 }
1398         }
1399         return vma;
1400 }
1401
1402 EXPORT_SYMBOL(find_vma);
1403
1404 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1405 struct vm_area_struct *
1406 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1407                         struct vm_area_struct **pprev)
1408 {
1409         struct vm_area_struct *vma = NULL, *prev = NULL;
1410         struct rb_node * rb_node;
1411         if (!mm)
1412                 goto out;
1413
1414         /* Guard against addr being lower than the first VMA */
1415         vma = mm->mmap;
1416
1417         /* Go through the RB tree quickly. */
1418         rb_node = mm->mm_rb.rb_node;
1419
1420         while (rb_node) {
1421                 struct vm_area_struct *vma_tmp;
1422                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1423
1424                 if (addr < vma_tmp->vm_end) {
1425                         rb_node = rb_node->rb_left;
1426                 } else {
1427                         prev = vma_tmp;
1428                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1429                                 break;
1430                         rb_node = rb_node->rb_right;
1431                 }
1432         }
1433
1434 out:
1435         *pprev = prev;
1436         return prev ? prev->vm_next : vma;
1437 }
1438
1439 /*
1440  * Verify that the stack growth is acceptable and
1441  * update accounting. This is shared with both the
1442  * grow-up and grow-down cases.
1443  */
1444 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1445 {
1446         struct mm_struct *mm = vma->vm_mm;
1447         struct rlimit *rlim = current->signal->rlim;
1448
1449         /* address space limit tests */
1450         if (!may_expand_vm(mm, grow))
1451                 return -ENOMEM;
1452
1453         /* Stack limit test */
1454         if (size > rlim[RLIMIT_STACK].rlim_cur)
1455                 return -ENOMEM;
1456
1457         /* mlock limit tests */
1458         if (vma->vm_flags & VM_LOCKED) {
1459                 unsigned long locked;
1460                 unsigned long limit;
1461                 locked = mm->locked_vm + grow;
1462                 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1463                 if (locked > limit && !capable(CAP_IPC_LOCK))
1464                         return -ENOMEM;
1465         }
1466
1467         /*
1468          * Overcommit..  This must be the final test, as it will
1469          * update security statistics.
1470          */
1471         if (security_vm_enough_memory(grow))
1472                 return -ENOMEM;
1473
1474         /* Ok, everything looks good - let it rip */
1475         mm->total_vm += grow;
1476         if (vma->vm_flags & VM_LOCKED)
1477                 mm->locked_vm += grow;
1478         __vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1479         return 0;
1480 }
1481
1482 #ifdef CONFIG_STACK_GROWSUP
1483 /*
1484  * vma is the first one with address > vma->vm_end.  Have to extend vma.
1485  */
1486 int expand_stack(struct vm_area_struct * vma, unsigned long address)
1487 {
1488         int error;
1489
1490         if (!(vma->vm_flags & VM_GROWSUP))
1491                 return -EFAULT;
1492
1493         /*
1494          * We must make sure the anon_vma is allocated
1495          * so that the anon_vma locking is not a noop.
1496          */
1497         if (unlikely(anon_vma_prepare(vma)))
1498                 return -ENOMEM;
1499         anon_vma_lock(vma);
1500
1501         /*
1502          * vma->vm_start/vm_end cannot change under us because the caller
1503          * is required to hold the mmap_sem in read mode.  We need the
1504          * anon_vma lock to serialize against concurrent expand_stacks.
1505          */
1506         address += 4 + PAGE_SIZE - 1;
1507         address &= PAGE_MASK;
1508         error = 0;
1509
1510         /* Somebody else might have raced and expanded it already */
1511         if (address > vma->vm_end) {
1512                 unsigned long size, grow;
1513
1514                 size = address - vma->vm_start;
1515                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1516
1517                 error = acct_stack_growth(vma, size, grow);
1518                 if (!error)
1519                         vma->vm_end = address;
1520         }
1521         anon_vma_unlock(vma);
1522         return error;
1523 }
1524
1525 struct vm_area_struct *
1526 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1527 {
1528         struct vm_area_struct *vma, *prev;
1529
1530         addr &= PAGE_MASK;
1531         vma = find_vma_prev(mm, addr, &prev);
1532         if (vma && (vma->vm_start <= addr))
1533                 return vma;
1534         if (!prev || expand_stack(prev, addr))
1535                 return NULL;
1536         if (prev->vm_flags & VM_LOCKED) {
1537                 make_pages_present(addr, prev->vm_end);
1538         }
1539         return prev;
1540 }
1541 #else
1542 /*
1543  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1544  */
1545 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1546 {
1547         int error;
1548
1549         /*
1550          * We must make sure the anon_vma is allocated
1551          * so that the anon_vma locking is not a noop.
1552          */
1553         if (unlikely(anon_vma_prepare(vma)))
1554                 return -ENOMEM;
1555         anon_vma_lock(vma);
1556
1557         /*
1558          * vma->vm_start/vm_end cannot change under us because the caller
1559          * is required to hold the mmap_sem in read mode.  We need the
1560          * anon_vma lock to serialize against concurrent expand_stacks.
1561          */
1562         address &= PAGE_MASK;
1563         error = 0;
1564
1565         /* Somebody else might have raced and expanded it already */
1566         if (address < vma->vm_start) {
1567                 unsigned long size, grow;
1568
1569                 size = vma->vm_end - address;
1570                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1571
1572                 error = acct_stack_growth(vma, size, grow);
1573                 if (!error) {
1574                         vma->vm_start = address;
1575                         vma->vm_pgoff -= grow;
1576                 }
1577         }
1578         anon_vma_unlock(vma);
1579         return error;
1580 }
1581
1582 struct vm_area_struct *
1583 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1584 {
1585         struct vm_area_struct * vma;
1586         unsigned long start;
1587
1588         addr &= PAGE_MASK;
1589         vma = find_vma(mm,addr);
1590         if (!vma)
1591                 return NULL;
1592         if (vma->vm_start <= addr)
1593                 return vma;
1594         if (!(vma->vm_flags & VM_GROWSDOWN))
1595                 return NULL;
1596         start = vma->vm_start;
1597         if (expand_stack(vma, addr))
1598                 return NULL;
1599         if (vma->vm_flags & VM_LOCKED) {
1600                 make_pages_present(addr, start);
1601         }
1602         return vma;
1603 }
1604 #endif
1605
1606 /* Normal function to fix up a mapping
1607  * This function is the default for when an area has no specific
1608  * function.  This may be used as part of a more specific routine.
1609  *
1610  * By the time this function is called, the area struct has been
1611  * removed from the process mapping list.
1612  */
1613 static void unmap_vma(struct mm_struct *mm, struct vm_area_struct *area)
1614 {
1615         size_t len = area->vm_end - area->vm_start;
1616
1617         area->vm_mm->total_vm -= len >> PAGE_SHIFT;
1618         if (area->vm_flags & VM_LOCKED)
1619                 area->vm_mm->locked_vm -= len >> PAGE_SHIFT;
1620         vm_stat_unaccount(area);
1621         remove_vm_struct(area);
1622 }
1623
1624 /*
1625  * Update the VMA and inode share lists.
1626  *
1627  * Ok - we have the memory areas we should free on the 'free' list,
1628  * so release them, and do the vma updates.
1629  */
1630 static void unmap_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1631 {
1632         do {
1633                 struct vm_area_struct *next = vma->vm_next;
1634                 unmap_vma(mm, vma);
1635                 vma = next;
1636         } while (vma);
1637         validate_mm(mm);
1638 }
1639
1640 /*
1641  * Get rid of page table information in the indicated region.
1642  *
1643  * Called with the page table lock held.
1644  */
1645 static void unmap_region(struct mm_struct *mm,
1646                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1647                 unsigned long start, unsigned long end)
1648 {
1649         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1650         struct mmu_gather *tlb;
1651         unsigned long nr_accounted = 0;
1652
1653         lru_add_drain();
1654         spin_lock(&mm->page_table_lock);
1655         tlb = tlb_gather_mmu(mm, 0);
1656         unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted, NULL);
1657         vm_unacct_memory(nr_accounted);
1658         free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1659                                  next? next->vm_start: 0);
1660         tlb_finish_mmu(tlb, start, end);
1661         spin_unlock(&mm->page_table_lock);
1662 }
1663
1664 /*
1665  * Create a list of vma's touched by the unmap, removing them from the mm's
1666  * vma list as we go..
1667  */
1668 static void
1669 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1670         struct vm_area_struct *prev, unsigned long end)
1671 {
1672         struct vm_area_struct **insertion_point;
1673         struct vm_area_struct *tail_vma = NULL;
1674         unsigned long addr;
1675
1676         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1677         do {
1678                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1679                 mm->map_count--;
1680                 tail_vma = vma;
1681                 vma = vma->vm_next;
1682         } while (vma && vma->vm_start < end);
1683         *insertion_point = vma;
1684         tail_vma->vm_next = NULL;
1685         if (mm->unmap_area == arch_unmap_area)
1686                 addr = prev ? prev->vm_end : mm->mmap_base;
1687         else
1688                 addr = vma ?  vma->vm_start : mm->mmap_base;
1689         mm->unmap_area(mm, addr);
1690         mm->mmap_cache = NULL;          /* Kill the cache. */
1691 }
1692
1693 /*
1694  * Split a vma into two pieces at address 'addr', a new vma is allocated
1695  * either for the first part or the the tail.
1696  */
1697 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1698               unsigned long addr, int new_below)
1699 {
1700         struct mempolicy *pol;
1701         struct vm_area_struct *new;
1702
1703         if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1704                 return -EINVAL;
1705
1706         if (mm->map_count >= sysctl_max_map_count)
1707                 return -ENOMEM;
1708
1709         new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1710         if (!new)
1711                 return -ENOMEM;
1712
1713         /* most fields are the same, copy all, and then fixup */
1714         *new = *vma;
1715
1716         if (new_below)
1717                 new->vm_end = addr;
1718         else {
1719                 new->vm_start = addr;
1720                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1721         }
1722
1723         pol = mpol_copy(vma_policy(vma));
1724         if (IS_ERR(pol)) {
1725                 kmem_cache_free(vm_area_cachep, new);
1726                 return PTR_ERR(pol);
1727         }
1728         vma_set_policy(new, pol);
1729
1730         if (new->vm_file)
1731                 get_file(new->vm_file);
1732
1733         if (new->vm_ops && new->vm_ops->open)
1734                 new->vm_ops->open(new);
1735
1736         if (new_below)
1737                 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1738                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1739         else
1740                 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1741
1742         return 0;
1743 }
1744
1745 /* Munmap is split into 2 main parts -- this part which finds
1746  * what needs doing, and the areas themselves, which do the
1747  * work.  This now handles partial unmappings.
1748  * Jeremy Fitzhardinge <jeremy@goop.org>
1749  */
1750 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1751 {
1752         unsigned long end;
1753         struct vm_area_struct *vma, *prev, *last;
1754
1755         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1756                 return -EINVAL;
1757
1758         if ((len = PAGE_ALIGN(len)) == 0)
1759                 return -EINVAL;
1760
1761         /* Find the first overlapping VMA */
1762         vma = find_vma_prev(mm, start, &prev);
1763         if (!vma)
1764                 return 0;
1765         /* we have  start < vma->vm_end  */
1766
1767         /* if it doesn't overlap, we have nothing.. */
1768         end = start + len;
1769         if (vma->vm_start >= end)
1770                 return 0;
1771
1772         /*
1773          * If we need to split any vma, do it now to save pain later.
1774          *
1775          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1776          * unmapped vm_area_struct will remain in use: so lower split_vma
1777          * places tmp vma above, and higher split_vma places tmp vma below.
1778          */
1779         if (start > vma->vm_start) {
1780                 int error = split_vma(mm, vma, start, 0);
1781                 if (error)
1782                         return error;
1783                 prev = vma;
1784         }
1785
1786         /* Does it split the last one? */
1787         last = find_vma(mm, end);
1788         if (last && end > last->vm_start) {
1789                 int error = split_vma(mm, last, end, 1);
1790                 if (error)
1791                         return error;
1792         }
1793         vma = prev? prev->vm_next: mm->mmap;
1794
1795         /*
1796          * Remove the vma's, and unmap the actual pages
1797          */
1798         detach_vmas_to_be_unmapped(mm, vma, prev, end);
1799         unmap_region(mm, vma, prev, start, end);
1800
1801         /* Fix up all other VM information */
1802         unmap_vma_list(mm, vma);
1803
1804         return 0;
1805 }
1806
1807 EXPORT_SYMBOL(do_munmap);
1808
1809 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1810 {
1811         int ret;
1812         struct mm_struct *mm = current->mm;
1813
1814         profile_munmap(addr);
1815
1816         down_write(&mm->mmap_sem);
1817         ret = do_munmap(mm, addr, len);
1818         up_write(&mm->mmap_sem);
1819         return ret;
1820 }
1821
1822 static inline void verify_mm_writelocked(struct mm_struct *mm)
1823 {
1824 #ifdef CONFIG_DEBUG_KERNEL
1825         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1826                 WARN_ON(1);
1827                 up_read(&mm->mmap_sem);
1828         }
1829 #endif
1830 }
1831
1832 /*
1833  *  this is really a simplified "do_mmap".  it only handles
1834  *  anonymous maps.  eventually we may be able to do some
1835  *  brk-specific accounting here.
1836  */
1837 unsigned long do_brk(unsigned long addr, unsigned long len)
1838 {
1839         struct mm_struct * mm = current->mm;
1840         struct vm_area_struct * vma, * prev;
1841         unsigned long flags;
1842         struct rb_node ** rb_link, * rb_parent;
1843         pgoff_t pgoff = addr >> PAGE_SHIFT;
1844
1845         len = PAGE_ALIGN(len);
1846         if (!len)
1847                 return addr;
1848
1849         if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1850                 return -EINVAL;
1851
1852         /*
1853          * mlock MCL_FUTURE?
1854          */
1855         if (mm->def_flags & VM_LOCKED) {
1856                 unsigned long locked, lock_limit;
1857                 locked = len >> PAGE_SHIFT;
1858                 locked += mm->locked_vm;
1859                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1860                 lock_limit >>= PAGE_SHIFT;
1861                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1862                         return -EAGAIN;
1863         }
1864
1865         /*
1866          * mm->mmap_sem is required to protect against another thread
1867          * changing the mappings in case we sleep.
1868          */
1869         verify_mm_writelocked(mm);
1870
1871         /*
1872          * Clear old maps.  this also does some error checking for us
1873          */
1874  munmap_back:
1875         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1876         if (vma && vma->vm_start < addr + len) {
1877                 if (do_munmap(mm, addr, len))
1878                         return -ENOMEM;
1879                 goto munmap_back;
1880         }
1881
1882         /* Check against address space limits *after* clearing old maps... */
1883         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1884                 return -ENOMEM;
1885
1886         if (mm->map_count > sysctl_max_map_count)
1887                 return -ENOMEM;
1888
1889         if (security_vm_enough_memory(len >> PAGE_SHIFT))
1890                 return -ENOMEM;
1891
1892         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1893
1894         /* Can we just expand an old private anonymous mapping? */
1895         if (vma_merge(mm, prev, addr, addr + len, flags,
1896                                         NULL, NULL, pgoff, NULL))
1897                 goto out;
1898
1899         /*
1900          * create a vma struct for an anonymous mapping
1901          */
1902         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1903         if (!vma) {
1904                 vm_unacct_memory(len >> PAGE_SHIFT);
1905                 return -ENOMEM;
1906         }
1907         memset(vma, 0, sizeof(*vma));
1908
1909         vma->vm_mm = mm;
1910         vma->vm_start = addr;
1911         vma->vm_end = addr + len;
1912         vma->vm_pgoff = pgoff;
1913         vma->vm_flags = flags;
1914         vma->vm_page_prot = protection_map[flags & 0x0f];
1915         vma_link(mm, vma, prev, rb_link, rb_parent);
1916 out:
1917         mm->total_vm += len >> PAGE_SHIFT;
1918         if (flags & VM_LOCKED) {
1919                 mm->locked_vm += len >> PAGE_SHIFT;
1920                 make_pages_present(addr, addr + len);
1921         }
1922         return addr;
1923 }
1924
1925 EXPORT_SYMBOL(do_brk);
1926
1927 /* Release all mmaps. */
1928 void exit_mmap(struct mm_struct *mm)
1929 {
1930         struct mmu_gather *tlb;
1931         struct vm_area_struct *vma = mm->mmap;
1932         unsigned long nr_accounted = 0;
1933         unsigned long end;
1934
1935         lru_add_drain();
1936
1937         spin_lock(&mm->page_table_lock);
1938
1939         flush_cache_mm(mm);
1940         tlb = tlb_gather_mmu(mm, 1);
1941         /* Use -1 here to ensure all VMAs in the mm are unmapped */
1942         end = unmap_vmas(&tlb, mm, vma, 0, -1, &nr_accounted, NULL);
1943         vm_unacct_memory(nr_accounted);
1944         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
1945         tlb_finish_mmu(tlb, 0, end);
1946
1947         mm->mmap = mm->mmap_cache = NULL;
1948         mm->mm_rb = RB_ROOT;
1949         set_mm_counter(mm, rss, 0);
1950         mm->total_vm = 0;
1951         mm->locked_vm = 0;
1952
1953         spin_unlock(&mm->page_table_lock);
1954
1955         /*
1956          * Walk the list again, actually closing and freeing it
1957          * without holding any MM locks.
1958          */
1959         while (vma) {
1960                 struct vm_area_struct *next = vma->vm_next;
1961                 remove_vm_struct(vma);
1962                 vma = next;
1963         }
1964
1965         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
1966 }
1967
1968 /* Insert vm structure into process list sorted by address
1969  * and into the inode's i_mmap tree.  If vm_file is non-NULL
1970  * then i_mmap_lock is taken here.
1971  */
1972 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
1973 {
1974         struct vm_area_struct * __vma, * prev;
1975         struct rb_node ** rb_link, * rb_parent;
1976
1977         /*
1978          * The vm_pgoff of a purely anonymous vma should be irrelevant
1979          * until its first write fault, when page's anon_vma and index
1980          * are set.  But now set the vm_pgoff it will almost certainly
1981          * end up with (unless mremap moves it elsewhere before that
1982          * first wfault), so /proc/pid/maps tells a consistent story.
1983          *
1984          * By setting it to reflect the virtual start address of the
1985          * vma, merges and splits can happen in a seamless way, just
1986          * using the existing file pgoff checks and manipulations.
1987          * Similarly in do_mmap_pgoff and in do_brk.
1988          */
1989         if (!vma->vm_file) {
1990                 BUG_ON(vma->anon_vma);
1991                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
1992         }
1993         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
1994         if (__vma && __vma->vm_start < vma->vm_end)
1995                 return -ENOMEM;
1996         if ((vma->vm_flags & VM_ACCOUNT) &&
1997              security_vm_enough_memory(vma_pages(vma)))
1998                 return -ENOMEM;
1999         vma_link(mm, vma, prev, rb_link, rb_parent);
2000         return 0;
2001 }
2002
2003 /*
2004  * Copy the vma structure to a new location in the same mm,
2005  * prior to moving page table entries, to effect an mremap move.
2006  */
2007 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2008         unsigned long addr, unsigned long len, pgoff_t pgoff)
2009 {
2010         struct vm_area_struct *vma = *vmap;
2011         unsigned long vma_start = vma->vm_start;
2012         struct mm_struct *mm = vma->vm_mm;
2013         struct vm_area_struct *new_vma, *prev;
2014         struct rb_node **rb_link, *rb_parent;
2015         struct mempolicy *pol;
2016
2017         /*
2018          * If anonymous vma has not yet been faulted, update new pgoff
2019          * to match new location, to increase its chance of merging.
2020          */
2021         if (!vma->vm_file && !vma->anon_vma)
2022                 pgoff = addr >> PAGE_SHIFT;
2023
2024         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2025         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2026                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2027         if (new_vma) {
2028                 /*
2029                  * Source vma may have been merged into new_vma
2030                  */
2031                 if (vma_start >= new_vma->vm_start &&
2032                     vma_start < new_vma->vm_end)
2033                         *vmap = new_vma;
2034         } else {
2035                 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
2036                 if (new_vma) {
2037                         *new_vma = *vma;
2038                         pol = mpol_copy(vma_policy(vma));
2039                         if (IS_ERR(pol)) {
2040                                 kmem_cache_free(vm_area_cachep, new_vma);
2041                                 return NULL;
2042                         }
2043                         vma_set_policy(new_vma, pol);
2044                         new_vma->vm_start = addr;
2045                         new_vma->vm_end = addr + len;
2046                         new_vma->vm_pgoff = pgoff;
2047                         if (new_vma->vm_file)
2048                                 get_file(new_vma->vm_file);
2049                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2050                                 new_vma->vm_ops->open(new_vma);
2051                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2052                 }
2053         }
2054         return new_vma;
2055 }
2056
2057 /*
2058  * Return true if the calling process may expand its vm space by the passed
2059  * number of pages
2060  */
2061 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2062 {
2063         unsigned long cur = mm->total_vm;       /* pages */
2064         unsigned long lim;
2065
2066         lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2067
2068         if (cur + npages > lim)
2069                 return 0;
2070         return 1;
2071 }