Simplify and comment on anon_vma re-use for anon_vma_prepare()
[linux-2.6.git] / mm / mmap.c
1 /*
2  * mm/mmap.c
3  *
4  * Written by obz.
5  *
6  * Address space accounting code        <alan@lxorguk.ukuu.org.uk>
7  */
8
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
11 #include <linux/mm.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
20 #include <linux/fs.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
29 #include <linux/mmu_notifier.h>
30 #include <linux/perf_event.h>
31
32 #include <asm/uaccess.h>
33 #include <asm/cacheflush.h>
34 #include <asm/tlb.h>
35 #include <asm/mmu_context.h>
36
37 #include "internal.h"
38
39 #ifndef arch_mmap_check
40 #define arch_mmap_check(addr, len, flags)       (0)
41 #endif
42
43 #ifndef arch_rebalance_pgtables
44 #define arch_rebalance_pgtables(addr, len)              (addr)
45 #endif
46
47 static void unmap_region(struct mm_struct *mm,
48                 struct vm_area_struct *vma, struct vm_area_struct *prev,
49                 unsigned long start, unsigned long end);
50
51 /*
52  * WARNING: the debugging will use recursive algorithms so never enable this
53  * unless you know what you are doing.
54  */
55 #undef DEBUG_MM_RB
56
57 /* description of effects of mapping type and prot in current implementation.
58  * this is due to the limited x86 page protection hardware.  The expected
59  * behavior is in parens:
60  *
61  * map_type     prot
62  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
63  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
64  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
65  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
66  *              
67  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
68  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
69  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
70  *
71  */
72 pgprot_t protection_map[16] = {
73         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
74         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
75 };
76
77 pgprot_t vm_get_page_prot(unsigned long vm_flags)
78 {
79         return __pgprot(pgprot_val(protection_map[vm_flags &
80                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
81                         pgprot_val(arch_vm_get_page_prot(vm_flags)));
82 }
83 EXPORT_SYMBOL(vm_get_page_prot);
84
85 int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
86 int sysctl_overcommit_ratio = 50;       /* default is 50% */
87 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
88 struct percpu_counter vm_committed_as;
89
90 /*
91  * Check that a process has enough memory to allocate a new virtual
92  * mapping. 0 means there is enough memory for the allocation to
93  * succeed and -ENOMEM implies there is not.
94  *
95  * We currently support three overcommit policies, which are set via the
96  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
97  *
98  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
99  * Additional code 2002 Jul 20 by Robert Love.
100  *
101  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
102  *
103  * Note this is a helper function intended to be used by LSMs which
104  * wish to use this logic.
105  */
106 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
107 {
108         unsigned long free, allowed;
109
110         vm_acct_memory(pages);
111
112         /*
113          * Sometimes we want to use more memory than we have
114          */
115         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
116                 return 0;
117
118         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
119                 unsigned long n;
120
121                 free = global_page_state(NR_FILE_PAGES);
122                 free += nr_swap_pages;
123
124                 /*
125                  * Any slabs which are created with the
126                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
127                  * which are reclaimable, under pressure.  The dentry
128                  * cache and most inode caches should fall into this
129                  */
130                 free += global_page_state(NR_SLAB_RECLAIMABLE);
131
132                 /*
133                  * Leave the last 3% for root
134                  */
135                 if (!cap_sys_admin)
136                         free -= free / 32;
137
138                 if (free > pages)
139                         return 0;
140
141                 /*
142                  * nr_free_pages() is very expensive on large systems,
143                  * only call if we're about to fail.
144                  */
145                 n = nr_free_pages();
146
147                 /*
148                  * Leave reserved pages. The pages are not for anonymous pages.
149                  */
150                 if (n <= totalreserve_pages)
151                         goto error;
152                 else
153                         n -= totalreserve_pages;
154
155                 /*
156                  * Leave the last 3% for root
157                  */
158                 if (!cap_sys_admin)
159                         n -= n / 32;
160                 free += n;
161
162                 if (free > pages)
163                         return 0;
164
165                 goto error;
166         }
167
168         allowed = (totalram_pages - hugetlb_total_pages())
169                 * sysctl_overcommit_ratio / 100;
170         /*
171          * Leave the last 3% for root
172          */
173         if (!cap_sys_admin)
174                 allowed -= allowed / 32;
175         allowed += total_swap_pages;
176
177         /* Don't let a single process grow too big:
178            leave 3% of the size of this process for other processes */
179         if (mm)
180                 allowed -= mm->total_vm / 32;
181
182         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
183                 return 0;
184 error:
185         vm_unacct_memory(pages);
186
187         return -ENOMEM;
188 }
189
190 /*
191  * Requires inode->i_mapping->i_mmap_lock
192  */
193 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
194                 struct file *file, struct address_space *mapping)
195 {
196         if (vma->vm_flags & VM_DENYWRITE)
197                 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
198         if (vma->vm_flags & VM_SHARED)
199                 mapping->i_mmap_writable--;
200
201         flush_dcache_mmap_lock(mapping);
202         if (unlikely(vma->vm_flags & VM_NONLINEAR))
203                 list_del_init(&vma->shared.vm_set.list);
204         else
205                 vma_prio_tree_remove(vma, &mapping->i_mmap);
206         flush_dcache_mmap_unlock(mapping);
207 }
208
209 /*
210  * Unlink a file-based vm structure from its prio_tree, to hide
211  * vma from rmap and vmtruncate before freeing its page tables.
212  */
213 void unlink_file_vma(struct vm_area_struct *vma)
214 {
215         struct file *file = vma->vm_file;
216
217         if (file) {
218                 struct address_space *mapping = file->f_mapping;
219                 spin_lock(&mapping->i_mmap_lock);
220                 __remove_shared_vm_struct(vma, file, mapping);
221                 spin_unlock(&mapping->i_mmap_lock);
222         }
223 }
224
225 /*
226  * Close a vm structure and free it, returning the next.
227  */
228 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
229 {
230         struct vm_area_struct *next = vma->vm_next;
231
232         might_sleep();
233         if (vma->vm_ops && vma->vm_ops->close)
234                 vma->vm_ops->close(vma);
235         if (vma->vm_file) {
236                 fput(vma->vm_file);
237                 if (vma->vm_flags & VM_EXECUTABLE)
238                         removed_exe_file_vma(vma->vm_mm);
239         }
240         mpol_put(vma_policy(vma));
241         kmem_cache_free(vm_area_cachep, vma);
242         return next;
243 }
244
245 SYSCALL_DEFINE1(brk, unsigned long, brk)
246 {
247         unsigned long rlim, retval;
248         unsigned long newbrk, oldbrk;
249         struct mm_struct *mm = current->mm;
250         unsigned long min_brk;
251
252         down_write(&mm->mmap_sem);
253
254 #ifdef CONFIG_COMPAT_BRK
255         min_brk = mm->end_code;
256 #else
257         min_brk = mm->start_brk;
258 #endif
259         if (brk < min_brk)
260                 goto out;
261
262         /*
263          * Check against rlimit here. If this check is done later after the test
264          * of oldbrk with newbrk then it can escape the test and let the data
265          * segment grow beyond its set limit the in case where the limit is
266          * not page aligned -Ram Gupta
267          */
268         rlim = rlimit(RLIMIT_DATA);
269         if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
270                         (mm->end_data - mm->start_data) > rlim)
271                 goto out;
272
273         newbrk = PAGE_ALIGN(brk);
274         oldbrk = PAGE_ALIGN(mm->brk);
275         if (oldbrk == newbrk)
276                 goto set_brk;
277
278         /* Always allow shrinking brk. */
279         if (brk <= mm->brk) {
280                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
281                         goto set_brk;
282                 goto out;
283         }
284
285         /* Check against existing mmap mappings. */
286         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
287                 goto out;
288
289         /* Ok, looks good - let it rip. */
290         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
291                 goto out;
292 set_brk:
293         mm->brk = brk;
294 out:
295         retval = mm->brk;
296         up_write(&mm->mmap_sem);
297         return retval;
298 }
299
300 #ifdef DEBUG_MM_RB
301 static int browse_rb(struct rb_root *root)
302 {
303         int i = 0, j;
304         struct rb_node *nd, *pn = NULL;
305         unsigned long prev = 0, pend = 0;
306
307         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
308                 struct vm_area_struct *vma;
309                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
310                 if (vma->vm_start < prev)
311                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
312                 if (vma->vm_start < pend)
313                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
314                 if (vma->vm_start > vma->vm_end)
315                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
316                 i++;
317                 pn = nd;
318                 prev = vma->vm_start;
319                 pend = vma->vm_end;
320         }
321         j = 0;
322         for (nd = pn; nd; nd = rb_prev(nd)) {
323                 j++;
324         }
325         if (i != j)
326                 printk("backwards %d, forwards %d\n", j, i), i = 0;
327         return i;
328 }
329
330 void validate_mm(struct mm_struct *mm)
331 {
332         int bug = 0;
333         int i = 0;
334         struct vm_area_struct *tmp = mm->mmap;
335         while (tmp) {
336                 tmp = tmp->vm_next;
337                 i++;
338         }
339         if (i != mm->map_count)
340                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
341         i = browse_rb(&mm->mm_rb);
342         if (i != mm->map_count)
343                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
344         BUG_ON(bug);
345 }
346 #else
347 #define validate_mm(mm) do { } while (0)
348 #endif
349
350 static struct vm_area_struct *
351 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
352                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
353                 struct rb_node ** rb_parent)
354 {
355         struct vm_area_struct * vma;
356         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
357
358         __rb_link = &mm->mm_rb.rb_node;
359         rb_prev = __rb_parent = NULL;
360         vma = NULL;
361
362         while (*__rb_link) {
363                 struct vm_area_struct *vma_tmp;
364
365                 __rb_parent = *__rb_link;
366                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
367
368                 if (vma_tmp->vm_end > addr) {
369                         vma = vma_tmp;
370                         if (vma_tmp->vm_start <= addr)
371                                 break;
372                         __rb_link = &__rb_parent->rb_left;
373                 } else {
374                         rb_prev = __rb_parent;
375                         __rb_link = &__rb_parent->rb_right;
376                 }
377         }
378
379         *pprev = NULL;
380         if (rb_prev)
381                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
382         *rb_link = __rb_link;
383         *rb_parent = __rb_parent;
384         return vma;
385 }
386
387 static inline void
388 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
389                 struct vm_area_struct *prev, struct rb_node *rb_parent)
390 {
391         if (prev) {
392                 vma->vm_next = prev->vm_next;
393                 prev->vm_next = vma;
394         } else {
395                 mm->mmap = vma;
396                 if (rb_parent)
397                         vma->vm_next = rb_entry(rb_parent,
398                                         struct vm_area_struct, vm_rb);
399                 else
400                         vma->vm_next = NULL;
401         }
402 }
403
404 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
405                 struct rb_node **rb_link, struct rb_node *rb_parent)
406 {
407         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
408         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
409 }
410
411 static void __vma_link_file(struct vm_area_struct *vma)
412 {
413         struct file *file;
414
415         file = vma->vm_file;
416         if (file) {
417                 struct address_space *mapping = file->f_mapping;
418
419                 if (vma->vm_flags & VM_DENYWRITE)
420                         atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
421                 if (vma->vm_flags & VM_SHARED)
422                         mapping->i_mmap_writable++;
423
424                 flush_dcache_mmap_lock(mapping);
425                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
426                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
427                 else
428                         vma_prio_tree_insert(vma, &mapping->i_mmap);
429                 flush_dcache_mmap_unlock(mapping);
430         }
431 }
432
433 static void
434 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
435         struct vm_area_struct *prev, struct rb_node **rb_link,
436         struct rb_node *rb_parent)
437 {
438         __vma_link_list(mm, vma, prev, rb_parent);
439         __vma_link_rb(mm, vma, rb_link, rb_parent);
440 }
441
442 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
443                         struct vm_area_struct *prev, struct rb_node **rb_link,
444                         struct rb_node *rb_parent)
445 {
446         struct address_space *mapping = NULL;
447
448         if (vma->vm_file)
449                 mapping = vma->vm_file->f_mapping;
450
451         if (mapping) {
452                 spin_lock(&mapping->i_mmap_lock);
453                 vma->vm_truncate_count = mapping->truncate_count;
454         }
455         anon_vma_lock(vma);
456
457         __vma_link(mm, vma, prev, rb_link, rb_parent);
458         __vma_link_file(vma);
459
460         anon_vma_unlock(vma);
461         if (mapping)
462                 spin_unlock(&mapping->i_mmap_lock);
463
464         mm->map_count++;
465         validate_mm(mm);
466 }
467
468 /*
469  * Helper for vma_adjust in the split_vma insert case:
470  * insert vm structure into list and rbtree and anon_vma,
471  * but it has already been inserted into prio_tree earlier.
472  */
473 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
474 {
475         struct vm_area_struct *__vma, *prev;
476         struct rb_node **rb_link, *rb_parent;
477
478         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
479         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
480         __vma_link(mm, vma, prev, rb_link, rb_parent);
481         mm->map_count++;
482 }
483
484 static inline void
485 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
486                 struct vm_area_struct *prev)
487 {
488         prev->vm_next = vma->vm_next;
489         rb_erase(&vma->vm_rb, &mm->mm_rb);
490         if (mm->mmap_cache == vma)
491                 mm->mmap_cache = prev;
492 }
493
494 /*
495  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
496  * is already present in an i_mmap tree without adjusting the tree.
497  * The following helper function should be used when such adjustments
498  * are necessary.  The "insert" vma (if any) is to be inserted
499  * before we drop the necessary locks.
500  */
501 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
502         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
503 {
504         struct mm_struct *mm = vma->vm_mm;
505         struct vm_area_struct *next = vma->vm_next;
506         struct vm_area_struct *importer = NULL;
507         struct address_space *mapping = NULL;
508         struct prio_tree_root *root = NULL;
509         struct file *file = vma->vm_file;
510         struct anon_vma *anon_vma = NULL;
511         long adjust_next = 0;
512         int remove_next = 0;
513
514         if (next && !insert) {
515                 if (end >= next->vm_end) {
516                         /*
517                          * vma expands, overlapping all the next, and
518                          * perhaps the one after too (mprotect case 6).
519                          */
520 again:                  remove_next = 1 + (end > next->vm_end);
521                         end = next->vm_end;
522                         anon_vma = next->anon_vma;
523                         importer = vma;
524                 } else if (end > next->vm_start) {
525                         /*
526                          * vma expands, overlapping part of the next:
527                          * mprotect case 5 shifting the boundary up.
528                          */
529                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
530                         anon_vma = next->anon_vma;
531                         importer = vma;
532                 } else if (end < vma->vm_end) {
533                         /*
534                          * vma shrinks, and !insert tells it's not
535                          * split_vma inserting another: so it must be
536                          * mprotect case 4 shifting the boundary down.
537                          */
538                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
539                         anon_vma = next->anon_vma;
540                         importer = next;
541                 }
542         }
543
544         /*
545          * When changing only vma->vm_end, we don't really need anon_vma lock.
546          */
547         if (vma->anon_vma && (insert || importer || start != vma->vm_start))
548                 anon_vma = vma->anon_vma;
549         if (anon_vma) {
550                 /*
551                  * Easily overlooked: when mprotect shifts the boundary,
552                  * make sure the expanding vma has anon_vma set if the
553                  * shrinking vma had, to cover any anon pages imported.
554                  */
555                 if (importer && !importer->anon_vma) {
556                         /* Block reverse map lookups until things are set up. */
557                         if (anon_vma_clone(importer, vma)) {
558                                 return -ENOMEM;
559                         }
560                         importer->anon_vma = anon_vma;
561                 }
562         }
563
564         if (file) {
565                 mapping = file->f_mapping;
566                 if (!(vma->vm_flags & VM_NONLINEAR))
567                         root = &mapping->i_mmap;
568                 spin_lock(&mapping->i_mmap_lock);
569                 if (importer &&
570                     vma->vm_truncate_count != next->vm_truncate_count) {
571                         /*
572                          * unmap_mapping_range might be in progress:
573                          * ensure that the expanding vma is rescanned.
574                          */
575                         importer->vm_truncate_count = 0;
576                 }
577                 if (insert) {
578                         insert->vm_truncate_count = vma->vm_truncate_count;
579                         /*
580                          * Put into prio_tree now, so instantiated pages
581                          * are visible to arm/parisc __flush_dcache_page
582                          * throughout; but we cannot insert into address
583                          * space until vma start or end is updated.
584                          */
585                         __vma_link_file(insert);
586                 }
587         }
588
589         if (root) {
590                 flush_dcache_mmap_lock(mapping);
591                 vma_prio_tree_remove(vma, root);
592                 if (adjust_next)
593                         vma_prio_tree_remove(next, root);
594         }
595
596         vma->vm_start = start;
597         vma->vm_end = end;
598         vma->vm_pgoff = pgoff;
599         if (adjust_next) {
600                 next->vm_start += adjust_next << PAGE_SHIFT;
601                 next->vm_pgoff += adjust_next;
602         }
603
604         if (root) {
605                 if (adjust_next)
606                         vma_prio_tree_insert(next, root);
607                 vma_prio_tree_insert(vma, root);
608                 flush_dcache_mmap_unlock(mapping);
609         }
610
611         if (remove_next) {
612                 /*
613                  * vma_merge has merged next into vma, and needs
614                  * us to remove next before dropping the locks.
615                  */
616                 __vma_unlink(mm, next, vma);
617                 if (file)
618                         __remove_shared_vm_struct(next, file, mapping);
619         } else if (insert) {
620                 /*
621                  * split_vma has split insert from vma, and needs
622                  * us to insert it before dropping the locks
623                  * (it may either follow vma or precede it).
624                  */
625                 __insert_vm_struct(mm, insert);
626         }
627
628         if (mapping)
629                 spin_unlock(&mapping->i_mmap_lock);
630
631         if (remove_next) {
632                 if (file) {
633                         fput(file);
634                         if (next->vm_flags & VM_EXECUTABLE)
635                                 removed_exe_file_vma(mm);
636                 }
637                 if (next->anon_vma)
638                         anon_vma_merge(vma, next);
639                 mm->map_count--;
640                 mpol_put(vma_policy(next));
641                 kmem_cache_free(vm_area_cachep, next);
642                 /*
643                  * In mprotect's case 6 (see comments on vma_merge),
644                  * we must remove another next too. It would clutter
645                  * up the code too much to do both in one go.
646                  */
647                 if (remove_next == 2) {
648                         next = vma->vm_next;
649                         goto again;
650                 }
651         }
652
653         validate_mm(mm);
654
655         return 0;
656 }
657
658 /*
659  * If the vma has a ->close operation then the driver probably needs to release
660  * per-vma resources, so we don't attempt to merge those.
661  */
662 static inline int is_mergeable_vma(struct vm_area_struct *vma,
663                         struct file *file, unsigned long vm_flags)
664 {
665         /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
666         if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
667                 return 0;
668         if (vma->vm_file != file)
669                 return 0;
670         if (vma->vm_ops && vma->vm_ops->close)
671                 return 0;
672         return 1;
673 }
674
675 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
676                                         struct anon_vma *anon_vma2)
677 {
678         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
679 }
680
681 /*
682  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
683  * in front of (at a lower virtual address and file offset than) the vma.
684  *
685  * We cannot merge two vmas if they have differently assigned (non-NULL)
686  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
687  *
688  * We don't check here for the merged mmap wrapping around the end of pagecache
689  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
690  * wrap, nor mmaps which cover the final page at index -1UL.
691  */
692 static int
693 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
694         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
695 {
696         if (is_mergeable_vma(vma, file, vm_flags) &&
697             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
698                 if (vma->vm_pgoff == vm_pgoff)
699                         return 1;
700         }
701         return 0;
702 }
703
704 /*
705  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
706  * beyond (at a higher virtual address and file offset than) the vma.
707  *
708  * We cannot merge two vmas if they have differently assigned (non-NULL)
709  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
710  */
711 static int
712 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
713         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
714 {
715         if (is_mergeable_vma(vma, file, vm_flags) &&
716             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
717                 pgoff_t vm_pglen;
718                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
719                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
720                         return 1;
721         }
722         return 0;
723 }
724
725 /*
726  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
727  * whether that can be merged with its predecessor or its successor.
728  * Or both (it neatly fills a hole).
729  *
730  * In most cases - when called for mmap, brk or mremap - [addr,end) is
731  * certain not to be mapped by the time vma_merge is called; but when
732  * called for mprotect, it is certain to be already mapped (either at
733  * an offset within prev, or at the start of next), and the flags of
734  * this area are about to be changed to vm_flags - and the no-change
735  * case has already been eliminated.
736  *
737  * The following mprotect cases have to be considered, where AAAA is
738  * the area passed down from mprotect_fixup, never extending beyond one
739  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
740  *
741  *     AAAA             AAAA                AAAA          AAAA
742  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
743  *    cannot merge    might become    might become    might become
744  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
745  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
746  *    mremap move:                                    PPPPNNNNNNNN 8
747  *        AAAA
748  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
749  *    might become    case 1 below    case 2 below    case 3 below
750  *
751  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
752  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
753  */
754 struct vm_area_struct *vma_merge(struct mm_struct *mm,
755                         struct vm_area_struct *prev, unsigned long addr,
756                         unsigned long end, unsigned long vm_flags,
757                         struct anon_vma *anon_vma, struct file *file,
758                         pgoff_t pgoff, struct mempolicy *policy)
759 {
760         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
761         struct vm_area_struct *area, *next;
762         int err;
763
764         /*
765          * We later require that vma->vm_flags == vm_flags,
766          * so this tests vma->vm_flags & VM_SPECIAL, too.
767          */
768         if (vm_flags & VM_SPECIAL)
769                 return NULL;
770
771         if (prev)
772                 next = prev->vm_next;
773         else
774                 next = mm->mmap;
775         area = next;
776         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
777                 next = next->vm_next;
778
779         /*
780          * Can it merge with the predecessor?
781          */
782         if (prev && prev->vm_end == addr &&
783                         mpol_equal(vma_policy(prev), policy) &&
784                         can_vma_merge_after(prev, vm_flags,
785                                                 anon_vma, file, pgoff)) {
786                 /*
787                  * OK, it can.  Can we now merge in the successor as well?
788                  */
789                 if (next && end == next->vm_start &&
790                                 mpol_equal(policy, vma_policy(next)) &&
791                                 can_vma_merge_before(next, vm_flags,
792                                         anon_vma, file, pgoff+pglen) &&
793                                 is_mergeable_anon_vma(prev->anon_vma,
794                                                       next->anon_vma)) {
795                                                         /* cases 1, 6 */
796                         err = vma_adjust(prev, prev->vm_start,
797                                 next->vm_end, prev->vm_pgoff, NULL);
798                 } else                                  /* cases 2, 5, 7 */
799                         err = vma_adjust(prev, prev->vm_start,
800                                 end, prev->vm_pgoff, NULL);
801                 if (err)
802                         return NULL;
803                 return prev;
804         }
805
806         /*
807          * Can this new request be merged in front of next?
808          */
809         if (next && end == next->vm_start &&
810                         mpol_equal(policy, vma_policy(next)) &&
811                         can_vma_merge_before(next, vm_flags,
812                                         anon_vma, file, pgoff+pglen)) {
813                 if (prev && addr < prev->vm_end)        /* case 4 */
814                         err = vma_adjust(prev, prev->vm_start,
815                                 addr, prev->vm_pgoff, NULL);
816                 else                                    /* cases 3, 8 */
817                         err = vma_adjust(area, addr, next->vm_end,
818                                 next->vm_pgoff - pglen, NULL);
819                 if (err)
820                         return NULL;
821                 return area;
822         }
823
824         return NULL;
825 }
826
827 /*
828  * Rough compatbility check to quickly see if it's even worth looking
829  * at sharing an anon_vma.
830  *
831  * They need to have the same vm_file, and the flags can only differ
832  * in things that mprotect may change.
833  *
834  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
835  * we can merge the two vma's. For example, we refuse to merge a vma if
836  * there is a vm_ops->close() function, because that indicates that the
837  * driver is doing some kind of reference counting. But that doesn't
838  * really matter for the anon_vma sharing case.
839  */
840 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
841 {
842         return a->vm_end == b->vm_start &&
843                 mpol_equal(vma_policy(a), vma_policy(b)) &&
844                 a->vm_file == b->vm_file &&
845                 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
846                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
847 }
848
849 /*
850  * Do some basic sanity checking to see if we can re-use the anon_vma
851  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
852  * the same as 'old', the other will be the new one that is trying
853  * to share the anon_vma.
854  *
855  * NOTE! This runs with mm_sem held for reading, so it is possible that
856  * the anon_vma of 'old' is concurrently in the process of being set up
857  * by another page fault trying to merge _that_. But that's ok: if it
858  * is being set up, that automatically means that it will be a singleton
859  * acceptable for merging, so we can do all of this optimistically. But
860  * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
861  *
862  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
863  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
864  * is to return an anon_vma that is "complex" due to having gone through
865  * a fork).
866  *
867  * We also make sure that the two vma's are compatible (adjacent,
868  * and with the same memory policies). That's all stable, even with just
869  * a read lock on the mm_sem.
870  */
871 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
872 {
873         if (anon_vma_compatible(a, b)) {
874                 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
875
876                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
877                         return anon_vma;
878         }
879         return NULL;
880 }
881
882 /*
883  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
884  * neighbouring vmas for a suitable anon_vma, before it goes off
885  * to allocate a new anon_vma.  It checks because a repetitive
886  * sequence of mprotects and faults may otherwise lead to distinct
887  * anon_vmas being allocated, preventing vma merge in subsequent
888  * mprotect.
889  */
890 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
891 {
892         struct anon_vma *anon_vma;
893         struct vm_area_struct *near;
894
895         near = vma->vm_next;
896         if (!near)
897                 goto try_prev;
898
899         anon_vma = reusable_anon_vma(near, vma, near);
900         if (anon_vma)
901                 return anon_vma;
902 try_prev:
903         /*
904          * It is potentially slow to have to call find_vma_prev here.
905          * But it's only on the first write fault on the vma, not
906          * every time, and we could devise a way to avoid it later
907          * (e.g. stash info in next's anon_vma_node when assigning
908          * an anon_vma, or when trying vma_merge).  Another time.
909          */
910         BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
911         if (!near)
912                 goto none;
913
914         anon_vma = reusable_anon_vma(near, near, vma);
915         if (anon_vma)
916                 return anon_vma;
917 none:
918         /*
919          * There's no absolute need to look only at touching neighbours:
920          * we could search further afield for "compatible" anon_vmas.
921          * But it would probably just be a waste of time searching,
922          * or lead to too many vmas hanging off the same anon_vma.
923          * We're trying to allow mprotect remerging later on,
924          * not trying to minimize memory used for anon_vmas.
925          */
926         return NULL;
927 }
928
929 #ifdef CONFIG_PROC_FS
930 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
931                                                 struct file *file, long pages)
932 {
933         const unsigned long stack_flags
934                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
935
936         if (file) {
937                 mm->shared_vm += pages;
938                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
939                         mm->exec_vm += pages;
940         } else if (flags & stack_flags)
941                 mm->stack_vm += pages;
942         if (flags & (VM_RESERVED|VM_IO))
943                 mm->reserved_vm += pages;
944 }
945 #endif /* CONFIG_PROC_FS */
946
947 /*
948  * The caller must hold down_write(&current->mm->mmap_sem).
949  */
950
951 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
952                         unsigned long len, unsigned long prot,
953                         unsigned long flags, unsigned long pgoff)
954 {
955         struct mm_struct * mm = current->mm;
956         struct inode *inode;
957         unsigned int vm_flags;
958         int error;
959         unsigned long reqprot = prot;
960
961         /*
962          * Does the application expect PROT_READ to imply PROT_EXEC?
963          *
964          * (the exception is when the underlying filesystem is noexec
965          *  mounted, in which case we dont add PROT_EXEC.)
966          */
967         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
968                 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
969                         prot |= PROT_EXEC;
970
971         if (!len)
972                 return -EINVAL;
973
974         if (!(flags & MAP_FIXED))
975                 addr = round_hint_to_min(addr);
976
977         /* Careful about overflows.. */
978         len = PAGE_ALIGN(len);
979         if (!len)
980                 return -ENOMEM;
981
982         /* offset overflow? */
983         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
984                return -EOVERFLOW;
985
986         /* Too many mappings? */
987         if (mm->map_count > sysctl_max_map_count)
988                 return -ENOMEM;
989
990         /* Obtain the address to map to. we verify (or select) it and ensure
991          * that it represents a valid section of the address space.
992          */
993         addr = get_unmapped_area(file, addr, len, pgoff, flags);
994         if (addr & ~PAGE_MASK)
995                 return addr;
996
997         /* Do simple checking here so the lower-level routines won't have
998          * to. we assume access permissions have been handled by the open
999          * of the memory object, so we don't do any here.
1000          */
1001         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1002                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1003
1004         if (flags & MAP_LOCKED)
1005                 if (!can_do_mlock())
1006                         return -EPERM;
1007
1008         /* mlock MCL_FUTURE? */
1009         if (vm_flags & VM_LOCKED) {
1010                 unsigned long locked, lock_limit;
1011                 locked = len >> PAGE_SHIFT;
1012                 locked += mm->locked_vm;
1013                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1014                 lock_limit >>= PAGE_SHIFT;
1015                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1016                         return -EAGAIN;
1017         }
1018
1019         inode = file ? file->f_path.dentry->d_inode : NULL;
1020
1021         if (file) {
1022                 switch (flags & MAP_TYPE) {
1023                 case MAP_SHARED:
1024                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1025                                 return -EACCES;
1026
1027                         /*
1028                          * Make sure we don't allow writing to an append-only
1029                          * file..
1030                          */
1031                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1032                                 return -EACCES;
1033
1034                         /*
1035                          * Make sure there are no mandatory locks on the file.
1036                          */
1037                         if (locks_verify_locked(inode))
1038                                 return -EAGAIN;
1039
1040                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1041                         if (!(file->f_mode & FMODE_WRITE))
1042                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1043
1044                         /* fall through */
1045                 case MAP_PRIVATE:
1046                         if (!(file->f_mode & FMODE_READ))
1047                                 return -EACCES;
1048                         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1049                                 if (vm_flags & VM_EXEC)
1050                                         return -EPERM;
1051                                 vm_flags &= ~VM_MAYEXEC;
1052                         }
1053
1054                         if (!file->f_op || !file->f_op->mmap)
1055                                 return -ENODEV;
1056                         break;
1057
1058                 default:
1059                         return -EINVAL;
1060                 }
1061         } else {
1062                 switch (flags & MAP_TYPE) {
1063                 case MAP_SHARED:
1064                         /*
1065                          * Ignore pgoff.
1066                          */
1067                         pgoff = 0;
1068                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1069                         break;
1070                 case MAP_PRIVATE:
1071                         /*
1072                          * Set pgoff according to addr for anon_vma.
1073                          */
1074                         pgoff = addr >> PAGE_SHIFT;
1075                         break;
1076                 default:
1077                         return -EINVAL;
1078                 }
1079         }
1080
1081         error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1082         if (error)
1083                 return error;
1084
1085         return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1086 }
1087 EXPORT_SYMBOL(do_mmap_pgoff);
1088
1089 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1090                 unsigned long, prot, unsigned long, flags,
1091                 unsigned long, fd, unsigned long, pgoff)
1092 {
1093         struct file *file = NULL;
1094         unsigned long retval = -EBADF;
1095
1096         if (!(flags & MAP_ANONYMOUS)) {
1097                 if (unlikely(flags & MAP_HUGETLB))
1098                         return -EINVAL;
1099                 file = fget(fd);
1100                 if (!file)
1101                         goto out;
1102         } else if (flags & MAP_HUGETLB) {
1103                 struct user_struct *user = NULL;
1104                 /*
1105                  * VM_NORESERVE is used because the reservations will be
1106                  * taken when vm_ops->mmap() is called
1107                  * A dummy user value is used because we are not locking
1108                  * memory so no accounting is necessary
1109                  */
1110                 len = ALIGN(len, huge_page_size(&default_hstate));
1111                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1112                                                 &user, HUGETLB_ANONHUGE_INODE);
1113                 if (IS_ERR(file))
1114                         return PTR_ERR(file);
1115         }
1116
1117         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1118
1119         down_write(&current->mm->mmap_sem);
1120         retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1121         up_write(&current->mm->mmap_sem);
1122
1123         if (file)
1124                 fput(file);
1125 out:
1126         return retval;
1127 }
1128
1129 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1130 struct mmap_arg_struct {
1131         unsigned long addr;
1132         unsigned long len;
1133         unsigned long prot;
1134         unsigned long flags;
1135         unsigned long fd;
1136         unsigned long offset;
1137 };
1138
1139 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1140 {
1141         struct mmap_arg_struct a;
1142
1143         if (copy_from_user(&a, arg, sizeof(a)))
1144                 return -EFAULT;
1145         if (a.offset & ~PAGE_MASK)
1146                 return -EINVAL;
1147
1148         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1149                               a.offset >> PAGE_SHIFT);
1150 }
1151 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1152
1153 /*
1154  * Some shared mappigns will want the pages marked read-only
1155  * to track write events. If so, we'll downgrade vm_page_prot
1156  * to the private version (using protection_map[] without the
1157  * VM_SHARED bit).
1158  */
1159 int vma_wants_writenotify(struct vm_area_struct *vma)
1160 {
1161         unsigned int vm_flags = vma->vm_flags;
1162
1163         /* If it was private or non-writable, the write bit is already clear */
1164         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1165                 return 0;
1166
1167         /* The backer wishes to know when pages are first written to? */
1168         if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1169                 return 1;
1170
1171         /* The open routine did something to the protections already? */
1172         if (pgprot_val(vma->vm_page_prot) !=
1173             pgprot_val(vm_get_page_prot(vm_flags)))
1174                 return 0;
1175
1176         /* Specialty mapping? */
1177         if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1178                 return 0;
1179
1180         /* Can the mapping track the dirty pages? */
1181         return vma->vm_file && vma->vm_file->f_mapping &&
1182                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1183 }
1184
1185 /*
1186  * We account for memory if it's a private writeable mapping,
1187  * not hugepages and VM_NORESERVE wasn't set.
1188  */
1189 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1190 {
1191         /*
1192          * hugetlb has its own accounting separate from the core VM
1193          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1194          */
1195         if (file && is_file_hugepages(file))
1196                 return 0;
1197
1198         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1199 }
1200
1201 unsigned long mmap_region(struct file *file, unsigned long addr,
1202                           unsigned long len, unsigned long flags,
1203                           unsigned int vm_flags, unsigned long pgoff)
1204 {
1205         struct mm_struct *mm = current->mm;
1206         struct vm_area_struct *vma, *prev;
1207         int correct_wcount = 0;
1208         int error;
1209         struct rb_node **rb_link, *rb_parent;
1210         unsigned long charged = 0;
1211         struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1212
1213         /* Clear old maps */
1214         error = -ENOMEM;
1215 munmap_back:
1216         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1217         if (vma && vma->vm_start < addr + len) {
1218                 if (do_munmap(mm, addr, len))
1219                         return -ENOMEM;
1220                 goto munmap_back;
1221         }
1222
1223         /* Check against address space limit. */
1224         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1225                 return -ENOMEM;
1226
1227         /*
1228          * Set 'VM_NORESERVE' if we should not account for the
1229          * memory use of this mapping.
1230          */
1231         if ((flags & MAP_NORESERVE)) {
1232                 /* We honor MAP_NORESERVE if allowed to overcommit */
1233                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1234                         vm_flags |= VM_NORESERVE;
1235
1236                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1237                 if (file && is_file_hugepages(file))
1238                         vm_flags |= VM_NORESERVE;
1239         }
1240
1241         /*
1242          * Private writable mapping: check memory availability
1243          */
1244         if (accountable_mapping(file, vm_flags)) {
1245                 charged = len >> PAGE_SHIFT;
1246                 if (security_vm_enough_memory(charged))
1247                         return -ENOMEM;
1248                 vm_flags |= VM_ACCOUNT;
1249         }
1250
1251         /*
1252          * Can we just expand an old mapping?
1253          */
1254         vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1255         if (vma)
1256                 goto out;
1257
1258         /*
1259          * Determine the object being mapped and call the appropriate
1260          * specific mapper. the address has already been validated, but
1261          * not unmapped, but the maps are removed from the list.
1262          */
1263         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1264         if (!vma) {
1265                 error = -ENOMEM;
1266                 goto unacct_error;
1267         }
1268
1269         vma->vm_mm = mm;
1270         vma->vm_start = addr;
1271         vma->vm_end = addr + len;
1272         vma->vm_flags = vm_flags;
1273         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1274         vma->vm_pgoff = pgoff;
1275         INIT_LIST_HEAD(&vma->anon_vma_chain);
1276
1277         if (file) {
1278                 error = -EINVAL;
1279                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1280                         goto free_vma;
1281                 if (vm_flags & VM_DENYWRITE) {
1282                         error = deny_write_access(file);
1283                         if (error)
1284                                 goto free_vma;
1285                         correct_wcount = 1;
1286                 }
1287                 vma->vm_file = file;
1288                 get_file(file);
1289                 error = file->f_op->mmap(file, vma);
1290                 if (error)
1291                         goto unmap_and_free_vma;
1292                 if (vm_flags & VM_EXECUTABLE)
1293                         added_exe_file_vma(mm);
1294
1295                 /* Can addr have changed??
1296                  *
1297                  * Answer: Yes, several device drivers can do it in their
1298                  *         f_op->mmap method. -DaveM
1299                  */
1300                 addr = vma->vm_start;
1301                 pgoff = vma->vm_pgoff;
1302                 vm_flags = vma->vm_flags;
1303         } else if (vm_flags & VM_SHARED) {
1304                 error = shmem_zero_setup(vma);
1305                 if (error)
1306                         goto free_vma;
1307         }
1308
1309         if (vma_wants_writenotify(vma)) {
1310                 pgprot_t pprot = vma->vm_page_prot;
1311
1312                 /* Can vma->vm_page_prot have changed??
1313                  *
1314                  * Answer: Yes, drivers may have changed it in their
1315                  *         f_op->mmap method.
1316                  *
1317                  * Ensures that vmas marked as uncached stay that way.
1318                  */
1319                 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1320                 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1321                         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1322         }
1323
1324         vma_link(mm, vma, prev, rb_link, rb_parent);
1325         file = vma->vm_file;
1326
1327         /* Once vma denies write, undo our temporary denial count */
1328         if (correct_wcount)
1329                 atomic_inc(&inode->i_writecount);
1330 out:
1331         perf_event_mmap(vma);
1332
1333         mm->total_vm += len >> PAGE_SHIFT;
1334         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1335         if (vm_flags & VM_LOCKED) {
1336                 if (!mlock_vma_pages_range(vma, addr, addr + len))
1337                         mm->locked_vm += (len >> PAGE_SHIFT);
1338         } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1339                 make_pages_present(addr, addr + len);
1340         return addr;
1341
1342 unmap_and_free_vma:
1343         if (correct_wcount)
1344                 atomic_inc(&inode->i_writecount);
1345         vma->vm_file = NULL;
1346         fput(file);
1347
1348         /* Undo any partial mapping done by a device driver. */
1349         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1350         charged = 0;
1351 free_vma:
1352         kmem_cache_free(vm_area_cachep, vma);
1353 unacct_error:
1354         if (charged)
1355                 vm_unacct_memory(charged);
1356         return error;
1357 }
1358
1359 /* Get an address range which is currently unmapped.
1360  * For shmat() with addr=0.
1361  *
1362  * Ugly calling convention alert:
1363  * Return value with the low bits set means error value,
1364  * ie
1365  *      if (ret & ~PAGE_MASK)
1366  *              error = ret;
1367  *
1368  * This function "knows" that -ENOMEM has the bits set.
1369  */
1370 #ifndef HAVE_ARCH_UNMAPPED_AREA
1371 unsigned long
1372 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1373                 unsigned long len, unsigned long pgoff, unsigned long flags)
1374 {
1375         struct mm_struct *mm = current->mm;
1376         struct vm_area_struct *vma;
1377         unsigned long start_addr;
1378
1379         if (len > TASK_SIZE)
1380                 return -ENOMEM;
1381
1382         if (flags & MAP_FIXED)
1383                 return addr;
1384
1385         if (addr) {
1386                 addr = PAGE_ALIGN(addr);
1387                 vma = find_vma(mm, addr);
1388                 if (TASK_SIZE - len >= addr &&
1389                     (!vma || addr + len <= vma->vm_start))
1390                         return addr;
1391         }
1392         if (len > mm->cached_hole_size) {
1393                 start_addr = addr = mm->free_area_cache;
1394         } else {
1395                 start_addr = addr = TASK_UNMAPPED_BASE;
1396                 mm->cached_hole_size = 0;
1397         }
1398
1399 full_search:
1400         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1401                 /* At this point:  (!vma || addr < vma->vm_end). */
1402                 if (TASK_SIZE - len < addr) {
1403                         /*
1404                          * Start a new search - just in case we missed
1405                          * some holes.
1406                          */
1407                         if (start_addr != TASK_UNMAPPED_BASE) {
1408                                 addr = TASK_UNMAPPED_BASE;
1409                                 start_addr = addr;
1410                                 mm->cached_hole_size = 0;
1411                                 goto full_search;
1412                         }
1413                         return -ENOMEM;
1414                 }
1415                 if (!vma || addr + len <= vma->vm_start) {
1416                         /*
1417                          * Remember the place where we stopped the search:
1418                          */
1419                         mm->free_area_cache = addr + len;
1420                         return addr;
1421                 }
1422                 if (addr + mm->cached_hole_size < vma->vm_start)
1423                         mm->cached_hole_size = vma->vm_start - addr;
1424                 addr = vma->vm_end;
1425         }
1426 }
1427 #endif  
1428
1429 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1430 {
1431         /*
1432          * Is this a new hole at the lowest possible address?
1433          */
1434         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1435                 mm->free_area_cache = addr;
1436                 mm->cached_hole_size = ~0UL;
1437         }
1438 }
1439
1440 /*
1441  * This mmap-allocator allocates new areas top-down from below the
1442  * stack's low limit (the base):
1443  */
1444 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1445 unsigned long
1446 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1447                           const unsigned long len, const unsigned long pgoff,
1448                           const unsigned long flags)
1449 {
1450         struct vm_area_struct *vma;
1451         struct mm_struct *mm = current->mm;
1452         unsigned long addr = addr0;
1453
1454         /* requested length too big for entire address space */
1455         if (len > TASK_SIZE)
1456                 return -ENOMEM;
1457
1458         if (flags & MAP_FIXED)
1459                 return addr;
1460
1461         /* requesting a specific address */
1462         if (addr) {
1463                 addr = PAGE_ALIGN(addr);
1464                 vma = find_vma(mm, addr);
1465                 if (TASK_SIZE - len >= addr &&
1466                                 (!vma || addr + len <= vma->vm_start))
1467                         return addr;
1468         }
1469
1470         /* check if free_area_cache is useful for us */
1471         if (len <= mm->cached_hole_size) {
1472                 mm->cached_hole_size = 0;
1473                 mm->free_area_cache = mm->mmap_base;
1474         }
1475
1476         /* either no address requested or can't fit in requested address hole */
1477         addr = mm->free_area_cache;
1478
1479         /* make sure it can fit in the remaining address space */
1480         if (addr > len) {
1481                 vma = find_vma(mm, addr-len);
1482                 if (!vma || addr <= vma->vm_start)
1483                         /* remember the address as a hint for next time */
1484                         return (mm->free_area_cache = addr-len);
1485         }
1486
1487         if (mm->mmap_base < len)
1488                 goto bottomup;
1489
1490         addr = mm->mmap_base-len;
1491
1492         do {
1493                 /*
1494                  * Lookup failure means no vma is above this address,
1495                  * else if new region fits below vma->vm_start,
1496                  * return with success:
1497                  */
1498                 vma = find_vma(mm, addr);
1499                 if (!vma || addr+len <= vma->vm_start)
1500                         /* remember the address as a hint for next time */
1501                         return (mm->free_area_cache = addr);
1502
1503                 /* remember the largest hole we saw so far */
1504                 if (addr + mm->cached_hole_size < vma->vm_start)
1505                         mm->cached_hole_size = vma->vm_start - addr;
1506
1507                 /* try just below the current vma->vm_start */
1508                 addr = vma->vm_start-len;
1509         } while (len < vma->vm_start);
1510
1511 bottomup:
1512         /*
1513          * A failed mmap() very likely causes application failure,
1514          * so fall back to the bottom-up function here. This scenario
1515          * can happen with large stack limits and large mmap()
1516          * allocations.
1517          */
1518         mm->cached_hole_size = ~0UL;
1519         mm->free_area_cache = TASK_UNMAPPED_BASE;
1520         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1521         /*
1522          * Restore the topdown base:
1523          */
1524         mm->free_area_cache = mm->mmap_base;
1525         mm->cached_hole_size = ~0UL;
1526
1527         return addr;
1528 }
1529 #endif
1530
1531 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1532 {
1533         /*
1534          * Is this a new hole at the highest possible address?
1535          */
1536         if (addr > mm->free_area_cache)
1537                 mm->free_area_cache = addr;
1538
1539         /* dont allow allocations above current base */
1540         if (mm->free_area_cache > mm->mmap_base)
1541                 mm->free_area_cache = mm->mmap_base;
1542 }
1543
1544 unsigned long
1545 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1546                 unsigned long pgoff, unsigned long flags)
1547 {
1548         unsigned long (*get_area)(struct file *, unsigned long,
1549                                   unsigned long, unsigned long, unsigned long);
1550
1551         unsigned long error = arch_mmap_check(addr, len, flags);
1552         if (error)
1553                 return error;
1554
1555         /* Careful about overflows.. */
1556         if (len > TASK_SIZE)
1557                 return -ENOMEM;
1558
1559         get_area = current->mm->get_unmapped_area;
1560         if (file && file->f_op && file->f_op->get_unmapped_area)
1561                 get_area = file->f_op->get_unmapped_area;
1562         addr = get_area(file, addr, len, pgoff, flags);
1563         if (IS_ERR_VALUE(addr))
1564                 return addr;
1565
1566         if (addr > TASK_SIZE - len)
1567                 return -ENOMEM;
1568         if (addr & ~PAGE_MASK)
1569                 return -EINVAL;
1570
1571         return arch_rebalance_pgtables(addr, len);
1572 }
1573
1574 EXPORT_SYMBOL(get_unmapped_area);
1575
1576 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1577 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1578 {
1579         struct vm_area_struct *vma = NULL;
1580
1581         if (mm) {
1582                 /* Check the cache first. */
1583                 /* (Cache hit rate is typically around 35%.) */
1584                 vma = mm->mmap_cache;
1585                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1586                         struct rb_node * rb_node;
1587
1588                         rb_node = mm->mm_rb.rb_node;
1589                         vma = NULL;
1590
1591                         while (rb_node) {
1592                                 struct vm_area_struct * vma_tmp;
1593
1594                                 vma_tmp = rb_entry(rb_node,
1595                                                 struct vm_area_struct, vm_rb);
1596
1597                                 if (vma_tmp->vm_end > addr) {
1598                                         vma = vma_tmp;
1599                                         if (vma_tmp->vm_start <= addr)
1600                                                 break;
1601                                         rb_node = rb_node->rb_left;
1602                                 } else
1603                                         rb_node = rb_node->rb_right;
1604                         }
1605                         if (vma)
1606                                 mm->mmap_cache = vma;
1607                 }
1608         }
1609         return vma;
1610 }
1611
1612 EXPORT_SYMBOL(find_vma);
1613
1614 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1615 struct vm_area_struct *
1616 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1617                         struct vm_area_struct **pprev)
1618 {
1619         struct vm_area_struct *vma = NULL, *prev = NULL;
1620         struct rb_node *rb_node;
1621         if (!mm)
1622                 goto out;
1623
1624         /* Guard against addr being lower than the first VMA */
1625         vma = mm->mmap;
1626
1627         /* Go through the RB tree quickly. */
1628         rb_node = mm->mm_rb.rb_node;
1629
1630         while (rb_node) {
1631                 struct vm_area_struct *vma_tmp;
1632                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1633
1634                 if (addr < vma_tmp->vm_end) {
1635                         rb_node = rb_node->rb_left;
1636                 } else {
1637                         prev = vma_tmp;
1638                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1639                                 break;
1640                         rb_node = rb_node->rb_right;
1641                 }
1642         }
1643
1644 out:
1645         *pprev = prev;
1646         return prev ? prev->vm_next : vma;
1647 }
1648
1649 /*
1650  * Verify that the stack growth is acceptable and
1651  * update accounting. This is shared with both the
1652  * grow-up and grow-down cases.
1653  */
1654 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1655 {
1656         struct mm_struct *mm = vma->vm_mm;
1657         struct rlimit *rlim = current->signal->rlim;
1658         unsigned long new_start;
1659
1660         /* address space limit tests */
1661         if (!may_expand_vm(mm, grow))
1662                 return -ENOMEM;
1663
1664         /* Stack limit test */
1665         if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1666                 return -ENOMEM;
1667
1668         /* mlock limit tests */
1669         if (vma->vm_flags & VM_LOCKED) {
1670                 unsigned long locked;
1671                 unsigned long limit;
1672                 locked = mm->locked_vm + grow;
1673                 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1674                 limit >>= PAGE_SHIFT;
1675                 if (locked > limit && !capable(CAP_IPC_LOCK))
1676                         return -ENOMEM;
1677         }
1678
1679         /* Check to ensure the stack will not grow into a hugetlb-only region */
1680         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1681                         vma->vm_end - size;
1682         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1683                 return -EFAULT;
1684
1685         /*
1686          * Overcommit..  This must be the final test, as it will
1687          * update security statistics.
1688          */
1689         if (security_vm_enough_memory_mm(mm, grow))
1690                 return -ENOMEM;
1691
1692         /* Ok, everything looks good - let it rip */
1693         mm->total_vm += grow;
1694         if (vma->vm_flags & VM_LOCKED)
1695                 mm->locked_vm += grow;
1696         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1697         return 0;
1698 }
1699
1700 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1701 /*
1702  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1703  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1704  */
1705 #ifndef CONFIG_IA64
1706 static
1707 #endif
1708 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1709 {
1710         int error;
1711
1712         if (!(vma->vm_flags & VM_GROWSUP))
1713                 return -EFAULT;
1714
1715         /*
1716          * We must make sure the anon_vma is allocated
1717          * so that the anon_vma locking is not a noop.
1718          */
1719         if (unlikely(anon_vma_prepare(vma)))
1720                 return -ENOMEM;
1721         anon_vma_lock(vma);
1722
1723         /*
1724          * vma->vm_start/vm_end cannot change under us because the caller
1725          * is required to hold the mmap_sem in read mode.  We need the
1726          * anon_vma lock to serialize against concurrent expand_stacks.
1727          * Also guard against wrapping around to address 0.
1728          */
1729         if (address < PAGE_ALIGN(address+4))
1730                 address = PAGE_ALIGN(address+4);
1731         else {
1732                 anon_vma_unlock(vma);
1733                 return -ENOMEM;
1734         }
1735         error = 0;
1736
1737         /* Somebody else might have raced and expanded it already */
1738         if (address > vma->vm_end) {
1739                 unsigned long size, grow;
1740
1741                 size = address - vma->vm_start;
1742                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1743
1744                 error = acct_stack_growth(vma, size, grow);
1745                 if (!error)
1746                         vma->vm_end = address;
1747         }
1748         anon_vma_unlock(vma);
1749         return error;
1750 }
1751 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1752
1753 /*
1754  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1755  */
1756 static int expand_downwards(struct vm_area_struct *vma,
1757                                    unsigned long address)
1758 {
1759         int error;
1760
1761         /*
1762          * We must make sure the anon_vma is allocated
1763          * so that the anon_vma locking is not a noop.
1764          */
1765         if (unlikely(anon_vma_prepare(vma)))
1766                 return -ENOMEM;
1767
1768         address &= PAGE_MASK;
1769         error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1770         if (error)
1771                 return error;
1772
1773         anon_vma_lock(vma);
1774
1775         /*
1776          * vma->vm_start/vm_end cannot change under us because the caller
1777          * is required to hold the mmap_sem in read mode.  We need the
1778          * anon_vma lock to serialize against concurrent expand_stacks.
1779          */
1780
1781         /* Somebody else might have raced and expanded it already */
1782         if (address < vma->vm_start) {
1783                 unsigned long size, grow;
1784
1785                 size = vma->vm_end - address;
1786                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1787
1788                 error = acct_stack_growth(vma, size, grow);
1789                 if (!error) {
1790                         vma->vm_start = address;
1791                         vma->vm_pgoff -= grow;
1792                 }
1793         }
1794         anon_vma_unlock(vma);
1795         return error;
1796 }
1797
1798 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1799 {
1800         return expand_downwards(vma, address);
1801 }
1802
1803 #ifdef CONFIG_STACK_GROWSUP
1804 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1805 {
1806         return expand_upwards(vma, address);
1807 }
1808
1809 struct vm_area_struct *
1810 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1811 {
1812         struct vm_area_struct *vma, *prev;
1813
1814         addr &= PAGE_MASK;
1815         vma = find_vma_prev(mm, addr, &prev);
1816         if (vma && (vma->vm_start <= addr))
1817                 return vma;
1818         if (!prev || expand_stack(prev, addr))
1819                 return NULL;
1820         if (prev->vm_flags & VM_LOCKED) {
1821                 mlock_vma_pages_range(prev, addr, prev->vm_end);
1822         }
1823         return prev;
1824 }
1825 #else
1826 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1827 {
1828         return expand_downwards(vma, address);
1829 }
1830
1831 struct vm_area_struct *
1832 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1833 {
1834         struct vm_area_struct * vma;
1835         unsigned long start;
1836
1837         addr &= PAGE_MASK;
1838         vma = find_vma(mm,addr);
1839         if (!vma)
1840                 return NULL;
1841         if (vma->vm_start <= addr)
1842                 return vma;
1843         if (!(vma->vm_flags & VM_GROWSDOWN))
1844                 return NULL;
1845         start = vma->vm_start;
1846         if (expand_stack(vma, addr))
1847                 return NULL;
1848         if (vma->vm_flags & VM_LOCKED) {
1849                 mlock_vma_pages_range(vma, addr, start);
1850         }
1851         return vma;
1852 }
1853 #endif
1854
1855 /*
1856  * Ok - we have the memory areas we should free on the vma list,
1857  * so release them, and do the vma updates.
1858  *
1859  * Called with the mm semaphore held.
1860  */
1861 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1862 {
1863         /* Update high watermark before we lower total_vm */
1864         update_hiwater_vm(mm);
1865         do {
1866                 long nrpages = vma_pages(vma);
1867
1868                 mm->total_vm -= nrpages;
1869                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1870                 vma = remove_vma(vma);
1871         } while (vma);
1872         validate_mm(mm);
1873 }
1874
1875 /*
1876  * Get rid of page table information in the indicated region.
1877  *
1878  * Called with the mm semaphore held.
1879  */
1880 static void unmap_region(struct mm_struct *mm,
1881                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1882                 unsigned long start, unsigned long end)
1883 {
1884         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1885         struct mmu_gather *tlb;
1886         unsigned long nr_accounted = 0;
1887
1888         lru_add_drain();
1889         tlb = tlb_gather_mmu(mm, 0);
1890         update_hiwater_rss(mm);
1891         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1892         vm_unacct_memory(nr_accounted);
1893         free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1894                                  next? next->vm_start: 0);
1895         tlb_finish_mmu(tlb, start, end);
1896 }
1897
1898 /*
1899  * Create a list of vma's touched by the unmap, removing them from the mm's
1900  * vma list as we go..
1901  */
1902 static void
1903 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1904         struct vm_area_struct *prev, unsigned long end)
1905 {
1906         struct vm_area_struct **insertion_point;
1907         struct vm_area_struct *tail_vma = NULL;
1908         unsigned long addr;
1909
1910         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1911         do {
1912                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1913                 mm->map_count--;
1914                 tail_vma = vma;
1915                 vma = vma->vm_next;
1916         } while (vma && vma->vm_start < end);
1917         *insertion_point = vma;
1918         tail_vma->vm_next = NULL;
1919         if (mm->unmap_area == arch_unmap_area)
1920                 addr = prev ? prev->vm_end : mm->mmap_base;
1921         else
1922                 addr = vma ?  vma->vm_start : mm->mmap_base;
1923         mm->unmap_area(mm, addr);
1924         mm->mmap_cache = NULL;          /* Kill the cache. */
1925 }
1926
1927 /*
1928  * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1929  * munmap path where it doesn't make sense to fail.
1930  */
1931 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1932               unsigned long addr, int new_below)
1933 {
1934         struct mempolicy *pol;
1935         struct vm_area_struct *new;
1936         int err = -ENOMEM;
1937
1938         if (is_vm_hugetlb_page(vma) && (addr &
1939                                         ~(huge_page_mask(hstate_vma(vma)))))
1940                 return -EINVAL;
1941
1942         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1943         if (!new)
1944                 goto out_err;
1945
1946         /* most fields are the same, copy all, and then fixup */
1947         *new = *vma;
1948
1949         INIT_LIST_HEAD(&new->anon_vma_chain);
1950
1951         if (new_below)
1952                 new->vm_end = addr;
1953         else {
1954                 new->vm_start = addr;
1955                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1956         }
1957
1958         pol = mpol_dup(vma_policy(vma));
1959         if (IS_ERR(pol)) {
1960                 err = PTR_ERR(pol);
1961                 goto out_free_vma;
1962         }
1963         vma_set_policy(new, pol);
1964
1965         if (anon_vma_clone(new, vma))
1966                 goto out_free_mpol;
1967
1968         if (new->vm_file) {
1969                 get_file(new->vm_file);
1970                 if (vma->vm_flags & VM_EXECUTABLE)
1971                         added_exe_file_vma(mm);
1972         }
1973
1974         if (new->vm_ops && new->vm_ops->open)
1975                 new->vm_ops->open(new);
1976
1977         if (new_below)
1978                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1979                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1980         else
1981                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1982
1983         /* Success. */
1984         if (!err)
1985                 return 0;
1986
1987         /* Clean everything up if vma_adjust failed. */
1988         new->vm_ops->close(new);
1989         if (new->vm_file) {
1990                 if (vma->vm_flags & VM_EXECUTABLE)
1991                         removed_exe_file_vma(mm);
1992                 fput(new->vm_file);
1993         }
1994  out_free_mpol:
1995         mpol_put(pol);
1996  out_free_vma:
1997         kmem_cache_free(vm_area_cachep, new);
1998  out_err:
1999         return err;
2000 }
2001
2002 /*
2003  * Split a vma into two pieces at address 'addr', a new vma is allocated
2004  * either for the first part or the tail.
2005  */
2006 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2007               unsigned long addr, int new_below)
2008 {
2009         if (mm->map_count >= sysctl_max_map_count)
2010                 return -ENOMEM;
2011
2012         return __split_vma(mm, vma, addr, new_below);
2013 }
2014
2015 /* Munmap is split into 2 main parts -- this part which finds
2016  * what needs doing, and the areas themselves, which do the
2017  * work.  This now handles partial unmappings.
2018  * Jeremy Fitzhardinge <jeremy@goop.org>
2019  */
2020 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2021 {
2022         unsigned long end;
2023         struct vm_area_struct *vma, *prev, *last;
2024
2025         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2026                 return -EINVAL;
2027
2028         if ((len = PAGE_ALIGN(len)) == 0)
2029                 return -EINVAL;
2030
2031         /* Find the first overlapping VMA */
2032         vma = find_vma_prev(mm, start, &prev);
2033         if (!vma)
2034                 return 0;
2035         /* we have  start < vma->vm_end  */
2036
2037         /* if it doesn't overlap, we have nothing.. */
2038         end = start + len;
2039         if (vma->vm_start >= end)
2040                 return 0;
2041
2042         /*
2043          * If we need to split any vma, do it now to save pain later.
2044          *
2045          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2046          * unmapped vm_area_struct will remain in use: so lower split_vma
2047          * places tmp vma above, and higher split_vma places tmp vma below.
2048          */
2049         if (start > vma->vm_start) {
2050                 int error;
2051
2052                 /*
2053                  * Make sure that map_count on return from munmap() will
2054                  * not exceed its limit; but let map_count go just above
2055                  * its limit temporarily, to help free resources as expected.
2056                  */
2057                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2058                         return -ENOMEM;
2059
2060                 error = __split_vma(mm, vma, start, 0);
2061                 if (error)
2062                         return error;
2063                 prev = vma;
2064         }
2065
2066         /* Does it split the last one? */
2067         last = find_vma(mm, end);
2068         if (last && end > last->vm_start) {
2069                 int error = __split_vma(mm, last, end, 1);
2070                 if (error)
2071                         return error;
2072         }
2073         vma = prev? prev->vm_next: mm->mmap;
2074
2075         /*
2076          * unlock any mlock()ed ranges before detaching vmas
2077          */
2078         if (mm->locked_vm) {
2079                 struct vm_area_struct *tmp = vma;
2080                 while (tmp && tmp->vm_start < end) {
2081                         if (tmp->vm_flags & VM_LOCKED) {
2082                                 mm->locked_vm -= vma_pages(tmp);
2083                                 munlock_vma_pages_all(tmp);
2084                         }
2085                         tmp = tmp->vm_next;
2086                 }
2087         }
2088
2089         /*
2090          * Remove the vma's, and unmap the actual pages
2091          */
2092         detach_vmas_to_be_unmapped(mm, vma, prev, end);
2093         unmap_region(mm, vma, prev, start, end);
2094
2095         /* Fix up all other VM information */
2096         remove_vma_list(mm, vma);
2097
2098         return 0;
2099 }
2100
2101 EXPORT_SYMBOL(do_munmap);
2102
2103 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2104 {
2105         int ret;
2106         struct mm_struct *mm = current->mm;
2107
2108         profile_munmap(addr);
2109
2110         down_write(&mm->mmap_sem);
2111         ret = do_munmap(mm, addr, len);
2112         up_write(&mm->mmap_sem);
2113         return ret;
2114 }
2115
2116 static inline void verify_mm_writelocked(struct mm_struct *mm)
2117 {
2118 #ifdef CONFIG_DEBUG_VM
2119         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2120                 WARN_ON(1);
2121                 up_read(&mm->mmap_sem);
2122         }
2123 #endif
2124 }
2125
2126 /*
2127  *  this is really a simplified "do_mmap".  it only handles
2128  *  anonymous maps.  eventually we may be able to do some
2129  *  brk-specific accounting here.
2130  */
2131 unsigned long do_brk(unsigned long addr, unsigned long len)
2132 {
2133         struct mm_struct * mm = current->mm;
2134         struct vm_area_struct * vma, * prev;
2135         unsigned long flags;
2136         struct rb_node ** rb_link, * rb_parent;
2137         pgoff_t pgoff = addr >> PAGE_SHIFT;
2138         int error;
2139
2140         len = PAGE_ALIGN(len);
2141         if (!len)
2142                 return addr;
2143
2144         error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2145         if (error)
2146                 return error;
2147
2148         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2149
2150         error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2151         if (error & ~PAGE_MASK)
2152                 return error;
2153
2154         /*
2155          * mlock MCL_FUTURE?
2156          */
2157         if (mm->def_flags & VM_LOCKED) {
2158                 unsigned long locked, lock_limit;
2159                 locked = len >> PAGE_SHIFT;
2160                 locked += mm->locked_vm;
2161                 lock_limit = rlimit(RLIMIT_MEMLOCK);
2162                 lock_limit >>= PAGE_SHIFT;
2163                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2164                         return -EAGAIN;
2165         }
2166
2167         /*
2168          * mm->mmap_sem is required to protect against another thread
2169          * changing the mappings in case we sleep.
2170          */
2171         verify_mm_writelocked(mm);
2172
2173         /*
2174          * Clear old maps.  this also does some error checking for us
2175          */
2176  munmap_back:
2177         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2178         if (vma && vma->vm_start < addr + len) {
2179                 if (do_munmap(mm, addr, len))
2180                         return -ENOMEM;
2181                 goto munmap_back;
2182         }
2183
2184         /* Check against address space limits *after* clearing old maps... */
2185         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2186                 return -ENOMEM;
2187
2188         if (mm->map_count > sysctl_max_map_count)
2189                 return -ENOMEM;
2190
2191         if (security_vm_enough_memory(len >> PAGE_SHIFT))
2192                 return -ENOMEM;
2193
2194         /* Can we just expand an old private anonymous mapping? */
2195         vma = vma_merge(mm, prev, addr, addr + len, flags,
2196                                         NULL, NULL, pgoff, NULL);
2197         if (vma)
2198                 goto out;
2199
2200         /*
2201          * create a vma struct for an anonymous mapping
2202          */
2203         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2204         if (!vma) {
2205                 vm_unacct_memory(len >> PAGE_SHIFT);
2206                 return -ENOMEM;
2207         }
2208
2209         INIT_LIST_HEAD(&vma->anon_vma_chain);
2210         vma->vm_mm = mm;
2211         vma->vm_start = addr;
2212         vma->vm_end = addr + len;
2213         vma->vm_pgoff = pgoff;
2214         vma->vm_flags = flags;
2215         vma->vm_page_prot = vm_get_page_prot(flags);
2216         vma_link(mm, vma, prev, rb_link, rb_parent);
2217 out:
2218         mm->total_vm += len >> PAGE_SHIFT;
2219         if (flags & VM_LOCKED) {
2220                 if (!mlock_vma_pages_range(vma, addr, addr + len))
2221                         mm->locked_vm += (len >> PAGE_SHIFT);
2222         }
2223         return addr;
2224 }
2225
2226 EXPORT_SYMBOL(do_brk);
2227
2228 /* Release all mmaps. */
2229 void exit_mmap(struct mm_struct *mm)
2230 {
2231         struct mmu_gather *tlb;
2232         struct vm_area_struct *vma;
2233         unsigned long nr_accounted = 0;
2234         unsigned long end;
2235
2236         /* mm's last user has gone, and its about to be pulled down */
2237         mmu_notifier_release(mm);
2238
2239         if (mm->locked_vm) {
2240                 vma = mm->mmap;
2241                 while (vma) {
2242                         if (vma->vm_flags & VM_LOCKED)
2243                                 munlock_vma_pages_all(vma);
2244                         vma = vma->vm_next;
2245                 }
2246         }
2247
2248         arch_exit_mmap(mm);
2249
2250         vma = mm->mmap;
2251         if (!vma)       /* Can happen if dup_mmap() received an OOM */
2252                 return;
2253
2254         lru_add_drain();
2255         flush_cache_mm(mm);
2256         tlb = tlb_gather_mmu(mm, 1);
2257         /* update_hiwater_rss(mm) here? but nobody should be looking */
2258         /* Use -1 here to ensure all VMAs in the mm are unmapped */
2259         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2260         vm_unacct_memory(nr_accounted);
2261
2262         free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2263         tlb_finish_mmu(tlb, 0, end);
2264
2265         /*
2266          * Walk the list again, actually closing and freeing it,
2267          * with preemption enabled, without holding any MM locks.
2268          */
2269         while (vma)
2270                 vma = remove_vma(vma);
2271
2272         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2273 }
2274
2275 /* Insert vm structure into process list sorted by address
2276  * and into the inode's i_mmap tree.  If vm_file is non-NULL
2277  * then i_mmap_lock is taken here.
2278  */
2279 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2280 {
2281         struct vm_area_struct * __vma, * prev;
2282         struct rb_node ** rb_link, * rb_parent;
2283
2284         /*
2285          * The vm_pgoff of a purely anonymous vma should be irrelevant
2286          * until its first write fault, when page's anon_vma and index
2287          * are set.  But now set the vm_pgoff it will almost certainly
2288          * end up with (unless mremap moves it elsewhere before that
2289          * first wfault), so /proc/pid/maps tells a consistent story.
2290          *
2291          * By setting it to reflect the virtual start address of the
2292          * vma, merges and splits can happen in a seamless way, just
2293          * using the existing file pgoff checks and manipulations.
2294          * Similarly in do_mmap_pgoff and in do_brk.
2295          */
2296         if (!vma->vm_file) {
2297                 BUG_ON(vma->anon_vma);
2298                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2299         }
2300         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2301         if (__vma && __vma->vm_start < vma->vm_end)
2302                 return -ENOMEM;
2303         if ((vma->vm_flags & VM_ACCOUNT) &&
2304              security_vm_enough_memory_mm(mm, vma_pages(vma)))
2305                 return -ENOMEM;
2306         vma_link(mm, vma, prev, rb_link, rb_parent);
2307         return 0;
2308 }
2309
2310 /*
2311  * Copy the vma structure to a new location in the same mm,
2312  * prior to moving page table entries, to effect an mremap move.
2313  */
2314 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2315         unsigned long addr, unsigned long len, pgoff_t pgoff)
2316 {
2317         struct vm_area_struct *vma = *vmap;
2318         unsigned long vma_start = vma->vm_start;
2319         struct mm_struct *mm = vma->vm_mm;
2320         struct vm_area_struct *new_vma, *prev;
2321         struct rb_node **rb_link, *rb_parent;
2322         struct mempolicy *pol;
2323
2324         /*
2325          * If anonymous vma has not yet been faulted, update new pgoff
2326          * to match new location, to increase its chance of merging.
2327          */
2328         if (!vma->vm_file && !vma->anon_vma)
2329                 pgoff = addr >> PAGE_SHIFT;
2330
2331         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2332         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2333                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2334         if (new_vma) {
2335                 /*
2336                  * Source vma may have been merged into new_vma
2337                  */
2338                 if (vma_start >= new_vma->vm_start &&
2339                     vma_start < new_vma->vm_end)
2340                         *vmap = new_vma;
2341         } else {
2342                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2343                 if (new_vma) {
2344                         *new_vma = *vma;
2345                         pol = mpol_dup(vma_policy(vma));
2346                         if (IS_ERR(pol))
2347                                 goto out_free_vma;
2348                         INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2349                         if (anon_vma_clone(new_vma, vma))
2350                                 goto out_free_mempol;
2351                         vma_set_policy(new_vma, pol);
2352                         new_vma->vm_start = addr;
2353                         new_vma->vm_end = addr + len;
2354                         new_vma->vm_pgoff = pgoff;
2355                         if (new_vma->vm_file) {
2356                                 get_file(new_vma->vm_file);
2357                                 if (vma->vm_flags & VM_EXECUTABLE)
2358                                         added_exe_file_vma(mm);
2359                         }
2360                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2361                                 new_vma->vm_ops->open(new_vma);
2362                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2363                 }
2364         }
2365         return new_vma;
2366
2367  out_free_mempol:
2368         mpol_put(pol);
2369  out_free_vma:
2370         kmem_cache_free(vm_area_cachep, new_vma);
2371         return NULL;
2372 }
2373
2374 /*
2375  * Return true if the calling process may expand its vm space by the passed
2376  * number of pages
2377  */
2378 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2379 {
2380         unsigned long cur = mm->total_vm;       /* pages */
2381         unsigned long lim;
2382
2383         lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2384
2385         if (cur + npages > lim)
2386                 return 0;
2387         return 1;
2388 }
2389
2390
2391 static int special_mapping_fault(struct vm_area_struct *vma,
2392                                 struct vm_fault *vmf)
2393 {
2394         pgoff_t pgoff;
2395         struct page **pages;
2396
2397         /*
2398          * special mappings have no vm_file, and in that case, the mm
2399          * uses vm_pgoff internally. So we have to subtract it from here.
2400          * We are allowed to do this because we are the mm; do not copy
2401          * this code into drivers!
2402          */
2403         pgoff = vmf->pgoff - vma->vm_pgoff;
2404
2405         for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2406                 pgoff--;
2407
2408         if (*pages) {
2409                 struct page *page = *pages;
2410                 get_page(page);
2411                 vmf->page = page;
2412                 return 0;
2413         }
2414
2415         return VM_FAULT_SIGBUS;
2416 }
2417
2418 /*
2419  * Having a close hook prevents vma merging regardless of flags.
2420  */
2421 static void special_mapping_close(struct vm_area_struct *vma)
2422 {
2423 }
2424
2425 static const struct vm_operations_struct special_mapping_vmops = {
2426         .close = special_mapping_close,
2427         .fault = special_mapping_fault,
2428 };
2429
2430 /*
2431  * Called with mm->mmap_sem held for writing.
2432  * Insert a new vma covering the given region, with the given flags.
2433  * Its pages are supplied by the given array of struct page *.
2434  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2435  * The region past the last page supplied will always produce SIGBUS.
2436  * The array pointer and the pages it points to are assumed to stay alive
2437  * for as long as this mapping might exist.
2438  */
2439 int install_special_mapping(struct mm_struct *mm,
2440                             unsigned long addr, unsigned long len,
2441                             unsigned long vm_flags, struct page **pages)
2442 {
2443         struct vm_area_struct *vma;
2444
2445         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2446         if (unlikely(vma == NULL))
2447                 return -ENOMEM;
2448
2449         INIT_LIST_HEAD(&vma->anon_vma_chain);
2450         vma->vm_mm = mm;
2451         vma->vm_start = addr;
2452         vma->vm_end = addr + len;
2453
2454         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2455         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2456
2457         vma->vm_ops = &special_mapping_vmops;
2458         vma->vm_private_data = pages;
2459
2460         if (unlikely(insert_vm_struct(mm, vma))) {
2461                 kmem_cache_free(vm_area_cachep, vma);
2462                 return -ENOMEM;
2463         }
2464
2465         mm->total_vm += len >> PAGE_SHIFT;
2466
2467         perf_event_mmap(vma);
2468
2469         return 0;
2470 }
2471
2472 static DEFINE_MUTEX(mm_all_locks_mutex);
2473
2474 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2475 {
2476         if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2477                 /*
2478                  * The LSB of head.next can't change from under us
2479                  * because we hold the mm_all_locks_mutex.
2480                  */
2481                 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2482                 /*
2483                  * We can safely modify head.next after taking the
2484                  * anon_vma->lock. If some other vma in this mm shares
2485                  * the same anon_vma we won't take it again.
2486                  *
2487                  * No need of atomic instructions here, head.next
2488                  * can't change from under us thanks to the
2489                  * anon_vma->lock.
2490                  */
2491                 if (__test_and_set_bit(0, (unsigned long *)
2492                                        &anon_vma->head.next))
2493                         BUG();
2494         }
2495 }
2496
2497 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2498 {
2499         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2500                 /*
2501                  * AS_MM_ALL_LOCKS can't change from under us because
2502                  * we hold the mm_all_locks_mutex.
2503                  *
2504                  * Operations on ->flags have to be atomic because
2505                  * even if AS_MM_ALL_LOCKS is stable thanks to the
2506                  * mm_all_locks_mutex, there may be other cpus
2507                  * changing other bitflags in parallel to us.
2508                  */
2509                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2510                         BUG();
2511                 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2512         }
2513 }
2514
2515 /*
2516  * This operation locks against the VM for all pte/vma/mm related
2517  * operations that could ever happen on a certain mm. This includes
2518  * vmtruncate, try_to_unmap, and all page faults.
2519  *
2520  * The caller must take the mmap_sem in write mode before calling
2521  * mm_take_all_locks(). The caller isn't allowed to release the
2522  * mmap_sem until mm_drop_all_locks() returns.
2523  *
2524  * mmap_sem in write mode is required in order to block all operations
2525  * that could modify pagetables and free pages without need of
2526  * altering the vma layout (for example populate_range() with
2527  * nonlinear vmas). It's also needed in write mode to avoid new
2528  * anon_vmas to be associated with existing vmas.
2529  *
2530  * A single task can't take more than one mm_take_all_locks() in a row
2531  * or it would deadlock.
2532  *
2533  * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2534  * mapping->flags avoid to take the same lock twice, if more than one
2535  * vma in this mm is backed by the same anon_vma or address_space.
2536  *
2537  * We can take all the locks in random order because the VM code
2538  * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2539  * takes more than one of them in a row. Secondly we're protected
2540  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2541  *
2542  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2543  * that may have to take thousand of locks.
2544  *
2545  * mm_take_all_locks() can fail if it's interrupted by signals.
2546  */
2547 int mm_take_all_locks(struct mm_struct *mm)
2548 {
2549         struct vm_area_struct *vma;
2550         struct anon_vma_chain *avc;
2551         int ret = -EINTR;
2552
2553         BUG_ON(down_read_trylock(&mm->mmap_sem));
2554
2555         mutex_lock(&mm_all_locks_mutex);
2556
2557         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2558                 if (signal_pending(current))
2559                         goto out_unlock;
2560                 if (vma->vm_file && vma->vm_file->f_mapping)
2561                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
2562         }
2563
2564         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2565                 if (signal_pending(current))
2566                         goto out_unlock;
2567                 if (vma->anon_vma)
2568                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2569                                 vm_lock_anon_vma(mm, avc->anon_vma);
2570         }
2571
2572         ret = 0;
2573
2574 out_unlock:
2575         if (ret)
2576                 mm_drop_all_locks(mm);
2577
2578         return ret;
2579 }
2580
2581 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2582 {
2583         if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2584                 /*
2585                  * The LSB of head.next can't change to 0 from under
2586                  * us because we hold the mm_all_locks_mutex.
2587                  *
2588                  * We must however clear the bitflag before unlocking
2589                  * the vma so the users using the anon_vma->head will
2590                  * never see our bitflag.
2591                  *
2592                  * No need of atomic instructions here, head.next
2593                  * can't change from under us until we release the
2594                  * anon_vma->lock.
2595                  */
2596                 if (!__test_and_clear_bit(0, (unsigned long *)
2597                                           &anon_vma->head.next))
2598                         BUG();
2599                 spin_unlock(&anon_vma->lock);
2600         }
2601 }
2602
2603 static void vm_unlock_mapping(struct address_space *mapping)
2604 {
2605         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2606                 /*
2607                  * AS_MM_ALL_LOCKS can't change to 0 from under us
2608                  * because we hold the mm_all_locks_mutex.
2609                  */
2610                 spin_unlock(&mapping->i_mmap_lock);
2611                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2612                                         &mapping->flags))
2613                         BUG();
2614         }
2615 }
2616
2617 /*
2618  * The mmap_sem cannot be released by the caller until
2619  * mm_drop_all_locks() returns.
2620  */
2621 void mm_drop_all_locks(struct mm_struct *mm)
2622 {
2623         struct vm_area_struct *vma;
2624         struct anon_vma_chain *avc;
2625
2626         BUG_ON(down_read_trylock(&mm->mmap_sem));
2627         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2628
2629         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2630                 if (vma->anon_vma)
2631                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2632                                 vm_unlock_anon_vma(avc->anon_vma);
2633                 if (vma->vm_file && vma->vm_file->f_mapping)
2634                         vm_unlock_mapping(vma->vm_file->f_mapping);
2635         }
2636
2637         mutex_unlock(&mm_all_locks_mutex);
2638 }
2639
2640 /*
2641  * initialise the VMA slab
2642  */
2643 void __init mmap_init(void)
2644 {
2645         int ret;
2646
2647         ret = percpu_counter_init(&vm_committed_as, 0);
2648         VM_BUG_ON(ret);
2649 }