mmap: remove unnecessary lock from __vma_link
[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
456         __vma_link(mm, vma, prev, rb_link, rb_parent);
457         __vma_link_file(vma);
458
459         if (mapping)
460                 spin_unlock(&mapping->i_mmap_lock);
461
462         mm->map_count++;
463         validate_mm(mm);
464 }
465
466 /*
467  * Helper for vma_adjust in the split_vma insert case:
468  * insert vm structure into list and rbtree and anon_vma,
469  * but it has already been inserted into prio_tree earlier.
470  */
471 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
472 {
473         struct vm_area_struct *__vma, *prev;
474         struct rb_node **rb_link, *rb_parent;
475
476         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
477         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
478         __vma_link(mm, vma, prev, rb_link, rb_parent);
479         mm->map_count++;
480 }
481
482 static inline void
483 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
484                 struct vm_area_struct *prev)
485 {
486         prev->vm_next = vma->vm_next;
487         rb_erase(&vma->vm_rb, &mm->mm_rb);
488         if (mm->mmap_cache == vma)
489                 mm->mmap_cache = prev;
490 }
491
492 /*
493  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
494  * is already present in an i_mmap tree without adjusting the tree.
495  * The following helper function should be used when such adjustments
496  * are necessary.  The "insert" vma (if any) is to be inserted
497  * before we drop the necessary locks.
498  */
499 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
500         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
501 {
502         struct mm_struct *mm = vma->vm_mm;
503         struct vm_area_struct *next = vma->vm_next;
504         struct vm_area_struct *importer = NULL;
505         struct address_space *mapping = NULL;
506         struct prio_tree_root *root = NULL;
507         struct anon_vma *anon_vma = NULL;
508         struct file *file = vma->vm_file;
509         long adjust_next = 0;
510         int remove_next = 0;
511
512         if (next && !insert) {
513                 struct vm_area_struct *exporter = NULL;
514
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                         exporter = next;
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                         exporter = next;
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                         exporter = vma;
540                         importer = next;
541                 }
542
543                 /*
544                  * Easily overlooked: when mprotect shifts the boundary,
545                  * make sure the expanding vma has anon_vma set if the
546                  * shrinking vma had, to cover any anon pages imported.
547                  */
548                 if (exporter && exporter->anon_vma && !importer->anon_vma) {
549                         if (anon_vma_clone(importer, exporter))
550                                 return -ENOMEM;
551                         importer->anon_vma = exporter->anon_vma;
552                 }
553         }
554
555         if (file) {
556                 mapping = file->f_mapping;
557                 if (!(vma->vm_flags & VM_NONLINEAR))
558                         root = &mapping->i_mmap;
559                 spin_lock(&mapping->i_mmap_lock);
560                 if (importer &&
561                     vma->vm_truncate_count != next->vm_truncate_count) {
562                         /*
563                          * unmap_mapping_range might be in progress:
564                          * ensure that the expanding vma is rescanned.
565                          */
566                         importer->vm_truncate_count = 0;
567                 }
568                 if (insert) {
569                         insert->vm_truncate_count = vma->vm_truncate_count;
570                         /*
571                          * Put into prio_tree now, so instantiated pages
572                          * are visible to arm/parisc __flush_dcache_page
573                          * throughout; but we cannot insert into address
574                          * space until vma start or end is updated.
575                          */
576                         __vma_link_file(insert);
577                 }
578         }
579
580         /*
581          * When changing only vma->vm_end, we don't really need anon_vma
582          * lock. This is a fairly rare case by itself, but the anon_vma
583          * lock may be shared between many sibling processes.  Skipping
584          * the lock for brk adjustments makes a difference sometimes.
585          */
586         if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
587                 anon_vma = vma->anon_vma;
588                 anon_vma_lock(anon_vma);
589         }
590
591         if (root) {
592                 flush_dcache_mmap_lock(mapping);
593                 vma_prio_tree_remove(vma, root);
594                 if (adjust_next)
595                         vma_prio_tree_remove(next, root);
596         }
597
598         vma->vm_start = start;
599         vma->vm_end = end;
600         vma->vm_pgoff = pgoff;
601         if (adjust_next) {
602                 next->vm_start += adjust_next << PAGE_SHIFT;
603                 next->vm_pgoff += adjust_next;
604         }
605
606         if (root) {
607                 if (adjust_next)
608                         vma_prio_tree_insert(next, root);
609                 vma_prio_tree_insert(vma, root);
610                 flush_dcache_mmap_unlock(mapping);
611         }
612
613         if (remove_next) {
614                 /*
615                  * vma_merge has merged next into vma, and needs
616                  * us to remove next before dropping the locks.
617                  */
618                 __vma_unlink(mm, next, vma);
619                 if (file)
620                         __remove_shared_vm_struct(next, file, mapping);
621         } else if (insert) {
622                 /*
623                  * split_vma has split insert from vma, and needs
624                  * us to insert it before dropping the locks
625                  * (it may either follow vma or precede it).
626                  */
627                 __insert_vm_struct(mm, insert);
628         }
629
630         if (anon_vma)
631                 anon_vma_unlock(anon_vma);
632         if (mapping)
633                 spin_unlock(&mapping->i_mmap_lock);
634
635         if (remove_next) {
636                 if (file) {
637                         fput(file);
638                         if (next->vm_flags & VM_EXECUTABLE)
639                                 removed_exe_file_vma(mm);
640                 }
641                 if (next->anon_vma)
642                         anon_vma_merge(vma, next);
643                 mm->map_count--;
644                 mpol_put(vma_policy(next));
645                 kmem_cache_free(vm_area_cachep, next);
646                 /*
647                  * In mprotect's case 6 (see comments on vma_merge),
648                  * we must remove another next too. It would clutter
649                  * up the code too much to do both in one go.
650                  */
651                 if (remove_next == 2) {
652                         next = vma->vm_next;
653                         goto again;
654                 }
655         }
656
657         validate_mm(mm);
658
659         return 0;
660 }
661
662 /*
663  * If the vma has a ->close operation then the driver probably needs to release
664  * per-vma resources, so we don't attempt to merge those.
665  */
666 static inline int is_mergeable_vma(struct vm_area_struct *vma,
667                         struct file *file, unsigned long vm_flags)
668 {
669         /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
670         if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
671                 return 0;
672         if (vma->vm_file != file)
673                 return 0;
674         if (vma->vm_ops && vma->vm_ops->close)
675                 return 0;
676         return 1;
677 }
678
679 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
680                                         struct anon_vma *anon_vma2)
681 {
682         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
683 }
684
685 /*
686  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
687  * in front of (at a lower virtual address and file offset than) the vma.
688  *
689  * We cannot merge two vmas if they have differently assigned (non-NULL)
690  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
691  *
692  * We don't check here for the merged mmap wrapping around the end of pagecache
693  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
694  * wrap, nor mmaps which cover the final page at index -1UL.
695  */
696 static int
697 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
698         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
699 {
700         if (is_mergeable_vma(vma, file, vm_flags) &&
701             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
702                 if (vma->vm_pgoff == vm_pgoff)
703                         return 1;
704         }
705         return 0;
706 }
707
708 /*
709  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
710  * beyond (at a higher virtual address and file offset than) the vma.
711  *
712  * We cannot merge two vmas if they have differently assigned (non-NULL)
713  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
714  */
715 static int
716 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
717         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
718 {
719         if (is_mergeable_vma(vma, file, vm_flags) &&
720             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
721                 pgoff_t vm_pglen;
722                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
723                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
724                         return 1;
725         }
726         return 0;
727 }
728
729 /*
730  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
731  * whether that can be merged with its predecessor or its successor.
732  * Or both (it neatly fills a hole).
733  *
734  * In most cases - when called for mmap, brk or mremap - [addr,end) is
735  * certain not to be mapped by the time vma_merge is called; but when
736  * called for mprotect, it is certain to be already mapped (either at
737  * an offset within prev, or at the start of next), and the flags of
738  * this area are about to be changed to vm_flags - and the no-change
739  * case has already been eliminated.
740  *
741  * The following mprotect cases have to be considered, where AAAA is
742  * the area passed down from mprotect_fixup, never extending beyond one
743  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
744  *
745  *     AAAA             AAAA                AAAA          AAAA
746  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
747  *    cannot merge    might become    might become    might become
748  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
749  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
750  *    mremap move:                                    PPPPNNNNNNNN 8
751  *        AAAA
752  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
753  *    might become    case 1 below    case 2 below    case 3 below
754  *
755  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
756  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
757  */
758 struct vm_area_struct *vma_merge(struct mm_struct *mm,
759                         struct vm_area_struct *prev, unsigned long addr,
760                         unsigned long end, unsigned long vm_flags,
761                         struct anon_vma *anon_vma, struct file *file,
762                         pgoff_t pgoff, struct mempolicy *policy)
763 {
764         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
765         struct vm_area_struct *area, *next;
766         int err;
767
768         /*
769          * We later require that vma->vm_flags == vm_flags,
770          * so this tests vma->vm_flags & VM_SPECIAL, too.
771          */
772         if (vm_flags & VM_SPECIAL)
773                 return NULL;
774
775         if (prev)
776                 next = prev->vm_next;
777         else
778                 next = mm->mmap;
779         area = next;
780         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
781                 next = next->vm_next;
782
783         /*
784          * Can it merge with the predecessor?
785          */
786         if (prev && prev->vm_end == addr &&
787                         mpol_equal(vma_policy(prev), policy) &&
788                         can_vma_merge_after(prev, vm_flags,
789                                                 anon_vma, file, pgoff)) {
790                 /*
791                  * OK, it can.  Can we now merge in the successor as well?
792                  */
793                 if (next && end == next->vm_start &&
794                                 mpol_equal(policy, vma_policy(next)) &&
795                                 can_vma_merge_before(next, vm_flags,
796                                         anon_vma, file, pgoff+pglen) &&
797                                 is_mergeable_anon_vma(prev->anon_vma,
798                                                       next->anon_vma)) {
799                                                         /* cases 1, 6 */
800                         err = vma_adjust(prev, prev->vm_start,
801                                 next->vm_end, prev->vm_pgoff, NULL);
802                 } else                                  /* cases 2, 5, 7 */
803                         err = vma_adjust(prev, prev->vm_start,
804                                 end, prev->vm_pgoff, NULL);
805                 if (err)
806                         return NULL;
807                 return prev;
808         }
809
810         /*
811          * Can this new request be merged in front of next?
812          */
813         if (next && end == next->vm_start &&
814                         mpol_equal(policy, vma_policy(next)) &&
815                         can_vma_merge_before(next, vm_flags,
816                                         anon_vma, file, pgoff+pglen)) {
817                 if (prev && addr < prev->vm_end)        /* case 4 */
818                         err = vma_adjust(prev, prev->vm_start,
819                                 addr, prev->vm_pgoff, NULL);
820                 else                                    /* cases 3, 8 */
821                         err = vma_adjust(area, addr, next->vm_end,
822                                 next->vm_pgoff - pglen, NULL);
823                 if (err)
824                         return NULL;
825                 return area;
826         }
827
828         return NULL;
829 }
830
831 /*
832  * Rough compatbility check to quickly see if it's even worth looking
833  * at sharing an anon_vma.
834  *
835  * They need to have the same vm_file, and the flags can only differ
836  * in things that mprotect may change.
837  *
838  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
839  * we can merge the two vma's. For example, we refuse to merge a vma if
840  * there is a vm_ops->close() function, because that indicates that the
841  * driver is doing some kind of reference counting. But that doesn't
842  * really matter for the anon_vma sharing case.
843  */
844 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
845 {
846         return a->vm_end == b->vm_start &&
847                 mpol_equal(vma_policy(a), vma_policy(b)) &&
848                 a->vm_file == b->vm_file &&
849                 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
850                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
851 }
852
853 /*
854  * Do some basic sanity checking to see if we can re-use the anon_vma
855  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
856  * the same as 'old', the other will be the new one that is trying
857  * to share the anon_vma.
858  *
859  * NOTE! This runs with mm_sem held for reading, so it is possible that
860  * the anon_vma of 'old' is concurrently in the process of being set up
861  * by another page fault trying to merge _that_. But that's ok: if it
862  * is being set up, that automatically means that it will be a singleton
863  * acceptable for merging, so we can do all of this optimistically. But
864  * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
865  *
866  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
867  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
868  * is to return an anon_vma that is "complex" due to having gone through
869  * a fork).
870  *
871  * We also make sure that the two vma's are compatible (adjacent,
872  * and with the same memory policies). That's all stable, even with just
873  * a read lock on the mm_sem.
874  */
875 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
876 {
877         if (anon_vma_compatible(a, b)) {
878                 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
879
880                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
881                         return anon_vma;
882         }
883         return NULL;
884 }
885
886 /*
887  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
888  * neighbouring vmas for a suitable anon_vma, before it goes off
889  * to allocate a new anon_vma.  It checks because a repetitive
890  * sequence of mprotects and faults may otherwise lead to distinct
891  * anon_vmas being allocated, preventing vma merge in subsequent
892  * mprotect.
893  */
894 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
895 {
896         struct anon_vma *anon_vma;
897         struct vm_area_struct *near;
898
899         near = vma->vm_next;
900         if (!near)
901                 goto try_prev;
902
903         anon_vma = reusable_anon_vma(near, vma, near);
904         if (anon_vma)
905                 return anon_vma;
906 try_prev:
907         /*
908          * It is potentially slow to have to call find_vma_prev here.
909          * But it's only on the first write fault on the vma, not
910          * every time, and we could devise a way to avoid it later
911          * (e.g. stash info in next's anon_vma_node when assigning
912          * an anon_vma, or when trying vma_merge).  Another time.
913          */
914         BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
915         if (!near)
916                 goto none;
917
918         anon_vma = reusable_anon_vma(near, near, vma);
919         if (anon_vma)
920                 return anon_vma;
921 none:
922         /*
923          * There's no absolute need to look only at touching neighbours:
924          * we could search further afield for "compatible" anon_vmas.
925          * But it would probably just be a waste of time searching,
926          * or lead to too many vmas hanging off the same anon_vma.
927          * We're trying to allow mprotect remerging later on,
928          * not trying to minimize memory used for anon_vmas.
929          */
930         return NULL;
931 }
932
933 #ifdef CONFIG_PROC_FS
934 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
935                                                 struct file *file, long pages)
936 {
937         const unsigned long stack_flags
938                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
939
940         if (file) {
941                 mm->shared_vm += pages;
942                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
943                         mm->exec_vm += pages;
944         } else if (flags & stack_flags)
945                 mm->stack_vm += pages;
946         if (flags & (VM_RESERVED|VM_IO))
947                 mm->reserved_vm += pages;
948 }
949 #endif /* CONFIG_PROC_FS */
950
951 /*
952  * The caller must hold down_write(&current->mm->mmap_sem).
953  */
954
955 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
956                         unsigned long len, unsigned long prot,
957                         unsigned long flags, unsigned long pgoff)
958 {
959         struct mm_struct * mm = current->mm;
960         struct inode *inode;
961         unsigned int vm_flags;
962         int error;
963         unsigned long reqprot = prot;
964
965         /*
966          * Does the application expect PROT_READ to imply PROT_EXEC?
967          *
968          * (the exception is when the underlying filesystem is noexec
969          *  mounted, in which case we dont add PROT_EXEC.)
970          */
971         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
972                 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
973                         prot |= PROT_EXEC;
974
975         if (!len)
976                 return -EINVAL;
977
978         if (!(flags & MAP_FIXED))
979                 addr = round_hint_to_min(addr);
980
981         /* Careful about overflows.. */
982         len = PAGE_ALIGN(len);
983         if (!len)
984                 return -ENOMEM;
985
986         /* offset overflow? */
987         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
988                return -EOVERFLOW;
989
990         /* Too many mappings? */
991         if (mm->map_count > sysctl_max_map_count)
992                 return -ENOMEM;
993
994         /* Obtain the address to map to. we verify (or select) it and ensure
995          * that it represents a valid section of the address space.
996          */
997         addr = get_unmapped_area(file, addr, len, pgoff, flags);
998         if (addr & ~PAGE_MASK)
999                 return addr;
1000
1001         /* Do simple checking here so the lower-level routines won't have
1002          * to. we assume access permissions have been handled by the open
1003          * of the memory object, so we don't do any here.
1004          */
1005         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1006                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1007
1008         if (flags & MAP_LOCKED)
1009                 if (!can_do_mlock())
1010                         return -EPERM;
1011
1012         /* mlock MCL_FUTURE? */
1013         if (vm_flags & VM_LOCKED) {
1014                 unsigned long locked, lock_limit;
1015                 locked = len >> PAGE_SHIFT;
1016                 locked += mm->locked_vm;
1017                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1018                 lock_limit >>= PAGE_SHIFT;
1019                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1020                         return -EAGAIN;
1021         }
1022
1023         inode = file ? file->f_path.dentry->d_inode : NULL;
1024
1025         if (file) {
1026                 switch (flags & MAP_TYPE) {
1027                 case MAP_SHARED:
1028                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1029                                 return -EACCES;
1030
1031                         /*
1032                          * Make sure we don't allow writing to an append-only
1033                          * file..
1034                          */
1035                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1036                                 return -EACCES;
1037
1038                         /*
1039                          * Make sure there are no mandatory locks on the file.
1040                          */
1041                         if (locks_verify_locked(inode))
1042                                 return -EAGAIN;
1043
1044                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1045                         if (!(file->f_mode & FMODE_WRITE))
1046                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1047
1048                         /* fall through */
1049                 case MAP_PRIVATE:
1050                         if (!(file->f_mode & FMODE_READ))
1051                                 return -EACCES;
1052                         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1053                                 if (vm_flags & VM_EXEC)
1054                                         return -EPERM;
1055                                 vm_flags &= ~VM_MAYEXEC;
1056                         }
1057
1058                         if (!file->f_op || !file->f_op->mmap)
1059                                 return -ENODEV;
1060                         break;
1061
1062                 default:
1063                         return -EINVAL;
1064                 }
1065         } else {
1066                 switch (flags & MAP_TYPE) {
1067                 case MAP_SHARED:
1068                         /*
1069                          * Ignore pgoff.
1070                          */
1071                         pgoff = 0;
1072                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1073                         break;
1074                 case MAP_PRIVATE:
1075                         /*
1076                          * Set pgoff according to addr for anon_vma.
1077                          */
1078                         pgoff = addr >> PAGE_SHIFT;
1079                         break;
1080                 default:
1081                         return -EINVAL;
1082                 }
1083         }
1084
1085         error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1086         if (error)
1087                 return error;
1088
1089         return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1090 }
1091 EXPORT_SYMBOL(do_mmap_pgoff);
1092
1093 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1094                 unsigned long, prot, unsigned long, flags,
1095                 unsigned long, fd, unsigned long, pgoff)
1096 {
1097         struct file *file = NULL;
1098         unsigned long retval = -EBADF;
1099
1100         if (!(flags & MAP_ANONYMOUS)) {
1101                 if (unlikely(flags & MAP_HUGETLB))
1102                         return -EINVAL;
1103                 file = fget(fd);
1104                 if (!file)
1105                         goto out;
1106         } else if (flags & MAP_HUGETLB) {
1107                 struct user_struct *user = NULL;
1108                 /*
1109                  * VM_NORESERVE is used because the reservations will be
1110                  * taken when vm_ops->mmap() is called
1111                  * A dummy user value is used because we are not locking
1112                  * memory so no accounting is necessary
1113                  */
1114                 len = ALIGN(len, huge_page_size(&default_hstate));
1115                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1116                                                 &user, HUGETLB_ANONHUGE_INODE);
1117                 if (IS_ERR(file))
1118                         return PTR_ERR(file);
1119         }
1120
1121         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1122
1123         down_write(&current->mm->mmap_sem);
1124         retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1125         up_write(&current->mm->mmap_sem);
1126
1127         if (file)
1128                 fput(file);
1129 out:
1130         return retval;
1131 }
1132
1133 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1134 struct mmap_arg_struct {
1135         unsigned long addr;
1136         unsigned long len;
1137         unsigned long prot;
1138         unsigned long flags;
1139         unsigned long fd;
1140         unsigned long offset;
1141 };
1142
1143 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1144 {
1145         struct mmap_arg_struct a;
1146
1147         if (copy_from_user(&a, arg, sizeof(a)))
1148                 return -EFAULT;
1149         if (a.offset & ~PAGE_MASK)
1150                 return -EINVAL;
1151
1152         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1153                               a.offset >> PAGE_SHIFT);
1154 }
1155 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1156
1157 /*
1158  * Some shared mappigns will want the pages marked read-only
1159  * to track write events. If so, we'll downgrade vm_page_prot
1160  * to the private version (using protection_map[] without the
1161  * VM_SHARED bit).
1162  */
1163 int vma_wants_writenotify(struct vm_area_struct *vma)
1164 {
1165         unsigned int vm_flags = vma->vm_flags;
1166
1167         /* If it was private or non-writable, the write bit is already clear */
1168         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1169                 return 0;
1170
1171         /* The backer wishes to know when pages are first written to? */
1172         if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1173                 return 1;
1174
1175         /* The open routine did something to the protections already? */
1176         if (pgprot_val(vma->vm_page_prot) !=
1177             pgprot_val(vm_get_page_prot(vm_flags)))
1178                 return 0;
1179
1180         /* Specialty mapping? */
1181         if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1182                 return 0;
1183
1184         /* Can the mapping track the dirty pages? */
1185         return vma->vm_file && vma->vm_file->f_mapping &&
1186                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1187 }
1188
1189 /*
1190  * We account for memory if it's a private writeable mapping,
1191  * not hugepages and VM_NORESERVE wasn't set.
1192  */
1193 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1194 {
1195         /*
1196          * hugetlb has its own accounting separate from the core VM
1197          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1198          */
1199         if (file && is_file_hugepages(file))
1200                 return 0;
1201
1202         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1203 }
1204
1205 unsigned long mmap_region(struct file *file, unsigned long addr,
1206                           unsigned long len, unsigned long flags,
1207                           unsigned int vm_flags, unsigned long pgoff)
1208 {
1209         struct mm_struct *mm = current->mm;
1210         struct vm_area_struct *vma, *prev;
1211         int correct_wcount = 0;
1212         int error;
1213         struct rb_node **rb_link, *rb_parent;
1214         unsigned long charged = 0;
1215         struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1216
1217         /* Clear old maps */
1218         error = -ENOMEM;
1219 munmap_back:
1220         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1221         if (vma && vma->vm_start < addr + len) {
1222                 if (do_munmap(mm, addr, len))
1223                         return -ENOMEM;
1224                 goto munmap_back;
1225         }
1226
1227         /* Check against address space limit. */
1228         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1229                 return -ENOMEM;
1230
1231         /*
1232          * Set 'VM_NORESERVE' if we should not account for the
1233          * memory use of this mapping.
1234          */
1235         if ((flags & MAP_NORESERVE)) {
1236                 /* We honor MAP_NORESERVE if allowed to overcommit */
1237                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1238                         vm_flags |= VM_NORESERVE;
1239
1240                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1241                 if (file && is_file_hugepages(file))
1242                         vm_flags |= VM_NORESERVE;
1243         }
1244
1245         /*
1246          * Private writable mapping: check memory availability
1247          */
1248         if (accountable_mapping(file, vm_flags)) {
1249                 charged = len >> PAGE_SHIFT;
1250                 if (security_vm_enough_memory(charged))
1251                         return -ENOMEM;
1252                 vm_flags |= VM_ACCOUNT;
1253         }
1254
1255         /*
1256          * Can we just expand an old mapping?
1257          */
1258         vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1259         if (vma)
1260                 goto out;
1261
1262         /*
1263          * Determine the object being mapped and call the appropriate
1264          * specific mapper. the address has already been validated, but
1265          * not unmapped, but the maps are removed from the list.
1266          */
1267         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1268         if (!vma) {
1269                 error = -ENOMEM;
1270                 goto unacct_error;
1271         }
1272
1273         vma->vm_mm = mm;
1274         vma->vm_start = addr;
1275         vma->vm_end = addr + len;
1276         vma->vm_flags = vm_flags;
1277         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1278         vma->vm_pgoff = pgoff;
1279         INIT_LIST_HEAD(&vma->anon_vma_chain);
1280
1281         if (file) {
1282                 error = -EINVAL;
1283                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1284                         goto free_vma;
1285                 if (vm_flags & VM_DENYWRITE) {
1286                         error = deny_write_access(file);
1287                         if (error)
1288                                 goto free_vma;
1289                         correct_wcount = 1;
1290                 }
1291                 vma->vm_file = file;
1292                 get_file(file);
1293                 error = file->f_op->mmap(file, vma);
1294                 if (error)
1295                         goto unmap_and_free_vma;
1296                 if (vm_flags & VM_EXECUTABLE)
1297                         added_exe_file_vma(mm);
1298
1299                 /* Can addr have changed??
1300                  *
1301                  * Answer: Yes, several device drivers can do it in their
1302                  *         f_op->mmap method. -DaveM
1303                  */
1304                 addr = vma->vm_start;
1305                 pgoff = vma->vm_pgoff;
1306                 vm_flags = vma->vm_flags;
1307         } else if (vm_flags & VM_SHARED) {
1308                 error = shmem_zero_setup(vma);
1309                 if (error)
1310                         goto free_vma;
1311         }
1312
1313         if (vma_wants_writenotify(vma)) {
1314                 pgprot_t pprot = vma->vm_page_prot;
1315
1316                 /* Can vma->vm_page_prot have changed??
1317                  *
1318                  * Answer: Yes, drivers may have changed it in their
1319                  *         f_op->mmap method.
1320                  *
1321                  * Ensures that vmas marked as uncached stay that way.
1322                  */
1323                 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1324                 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1325                         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1326         }
1327
1328         vma_link(mm, vma, prev, rb_link, rb_parent);
1329         file = vma->vm_file;
1330
1331         /* Once vma denies write, undo our temporary denial count */
1332         if (correct_wcount)
1333                 atomic_inc(&inode->i_writecount);
1334 out:
1335         perf_event_mmap(vma);
1336
1337         mm->total_vm += len >> PAGE_SHIFT;
1338         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1339         if (vm_flags & VM_LOCKED) {
1340                 if (!mlock_vma_pages_range(vma, addr, addr + len))
1341                         mm->locked_vm += (len >> PAGE_SHIFT);
1342         } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1343                 make_pages_present(addr, addr + len);
1344         return addr;
1345
1346 unmap_and_free_vma:
1347         if (correct_wcount)
1348                 atomic_inc(&inode->i_writecount);
1349         vma->vm_file = NULL;
1350         fput(file);
1351
1352         /* Undo any partial mapping done by a device driver. */
1353         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1354         charged = 0;
1355 free_vma:
1356         kmem_cache_free(vm_area_cachep, vma);
1357 unacct_error:
1358         if (charged)
1359                 vm_unacct_memory(charged);
1360         return error;
1361 }
1362
1363 /* Get an address range which is currently unmapped.
1364  * For shmat() with addr=0.
1365  *
1366  * Ugly calling convention alert:
1367  * Return value with the low bits set means error value,
1368  * ie
1369  *      if (ret & ~PAGE_MASK)
1370  *              error = ret;
1371  *
1372  * This function "knows" that -ENOMEM has the bits set.
1373  */
1374 #ifndef HAVE_ARCH_UNMAPPED_AREA
1375 unsigned long
1376 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1377                 unsigned long len, unsigned long pgoff, unsigned long flags)
1378 {
1379         struct mm_struct *mm = current->mm;
1380         struct vm_area_struct *vma;
1381         unsigned long start_addr;
1382
1383         if (len > TASK_SIZE)
1384                 return -ENOMEM;
1385
1386         if (flags & MAP_FIXED)
1387                 return addr;
1388
1389         if (addr) {
1390                 addr = PAGE_ALIGN(addr);
1391                 vma = find_vma(mm, addr);
1392                 if (TASK_SIZE - len >= addr &&
1393                     (!vma || addr + len <= vma->vm_start))
1394                         return addr;
1395         }
1396         if (len > mm->cached_hole_size) {
1397                 start_addr = addr = mm->free_area_cache;
1398         } else {
1399                 start_addr = addr = TASK_UNMAPPED_BASE;
1400                 mm->cached_hole_size = 0;
1401         }
1402
1403 full_search:
1404         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1405                 /* At this point:  (!vma || addr < vma->vm_end). */
1406                 if (TASK_SIZE - len < addr) {
1407                         /*
1408                          * Start a new search - just in case we missed
1409                          * some holes.
1410                          */
1411                         if (start_addr != TASK_UNMAPPED_BASE) {
1412                                 addr = TASK_UNMAPPED_BASE;
1413                                 start_addr = addr;
1414                                 mm->cached_hole_size = 0;
1415                                 goto full_search;
1416                         }
1417                         return -ENOMEM;
1418                 }
1419                 if (!vma || addr + len <= vma->vm_start) {
1420                         /*
1421                          * Remember the place where we stopped the search:
1422                          */
1423                         mm->free_area_cache = addr + len;
1424                         return addr;
1425                 }
1426                 if (addr + mm->cached_hole_size < vma->vm_start)
1427                         mm->cached_hole_size = vma->vm_start - addr;
1428                 addr = vma->vm_end;
1429         }
1430 }
1431 #endif  
1432
1433 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1434 {
1435         /*
1436          * Is this a new hole at the lowest possible address?
1437          */
1438         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1439                 mm->free_area_cache = addr;
1440                 mm->cached_hole_size = ~0UL;
1441         }
1442 }
1443
1444 /*
1445  * This mmap-allocator allocates new areas top-down from below the
1446  * stack's low limit (the base):
1447  */
1448 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1449 unsigned long
1450 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1451                           const unsigned long len, const unsigned long pgoff,
1452                           const unsigned long flags)
1453 {
1454         struct vm_area_struct *vma;
1455         struct mm_struct *mm = current->mm;
1456         unsigned long addr = addr0;
1457
1458         /* requested length too big for entire address space */
1459         if (len > TASK_SIZE)
1460                 return -ENOMEM;
1461
1462         if (flags & MAP_FIXED)
1463                 return addr;
1464
1465         /* requesting a specific address */
1466         if (addr) {
1467                 addr = PAGE_ALIGN(addr);
1468                 vma = find_vma(mm, addr);
1469                 if (TASK_SIZE - len >= addr &&
1470                                 (!vma || addr + len <= vma->vm_start))
1471                         return addr;
1472         }
1473
1474         /* check if free_area_cache is useful for us */
1475         if (len <= mm->cached_hole_size) {
1476                 mm->cached_hole_size = 0;
1477                 mm->free_area_cache = mm->mmap_base;
1478         }
1479
1480         /* either no address requested or can't fit in requested address hole */
1481         addr = mm->free_area_cache;
1482
1483         /* make sure it can fit in the remaining address space */
1484         if (addr > len) {
1485                 vma = find_vma(mm, addr-len);
1486                 if (!vma || addr <= vma->vm_start)
1487                         /* remember the address as a hint for next time */
1488                         return (mm->free_area_cache = addr-len);
1489         }
1490
1491         if (mm->mmap_base < len)
1492                 goto bottomup;
1493
1494         addr = mm->mmap_base-len;
1495
1496         do {
1497                 /*
1498                  * Lookup failure means no vma is above this address,
1499                  * else if new region fits below vma->vm_start,
1500                  * return with success:
1501                  */
1502                 vma = find_vma(mm, addr);
1503                 if (!vma || addr+len <= vma->vm_start)
1504                         /* remember the address as a hint for next time */
1505                         return (mm->free_area_cache = addr);
1506
1507                 /* remember the largest hole we saw so far */
1508                 if (addr + mm->cached_hole_size < vma->vm_start)
1509                         mm->cached_hole_size = vma->vm_start - addr;
1510
1511                 /* try just below the current vma->vm_start */
1512                 addr = vma->vm_start-len;
1513         } while (len < vma->vm_start);
1514
1515 bottomup:
1516         /*
1517          * A failed mmap() very likely causes application failure,
1518          * so fall back to the bottom-up function here. This scenario
1519          * can happen with large stack limits and large mmap()
1520          * allocations.
1521          */
1522         mm->cached_hole_size = ~0UL;
1523         mm->free_area_cache = TASK_UNMAPPED_BASE;
1524         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1525         /*
1526          * Restore the topdown base:
1527          */
1528         mm->free_area_cache = mm->mmap_base;
1529         mm->cached_hole_size = ~0UL;
1530
1531         return addr;
1532 }
1533 #endif
1534
1535 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1536 {
1537         /*
1538          * Is this a new hole at the highest possible address?
1539          */
1540         if (addr > mm->free_area_cache)
1541                 mm->free_area_cache = addr;
1542
1543         /* dont allow allocations above current base */
1544         if (mm->free_area_cache > mm->mmap_base)
1545                 mm->free_area_cache = mm->mmap_base;
1546 }
1547
1548 unsigned long
1549 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1550                 unsigned long pgoff, unsigned long flags)
1551 {
1552         unsigned long (*get_area)(struct file *, unsigned long,
1553                                   unsigned long, unsigned long, unsigned long);
1554
1555         unsigned long error = arch_mmap_check(addr, len, flags);
1556         if (error)
1557                 return error;
1558
1559         /* Careful about overflows.. */
1560         if (len > TASK_SIZE)
1561                 return -ENOMEM;
1562
1563         get_area = current->mm->get_unmapped_area;
1564         if (file && file->f_op && file->f_op->get_unmapped_area)
1565                 get_area = file->f_op->get_unmapped_area;
1566         addr = get_area(file, addr, len, pgoff, flags);
1567         if (IS_ERR_VALUE(addr))
1568                 return addr;
1569
1570         if (addr > TASK_SIZE - len)
1571                 return -ENOMEM;
1572         if (addr & ~PAGE_MASK)
1573                 return -EINVAL;
1574
1575         return arch_rebalance_pgtables(addr, len);
1576 }
1577
1578 EXPORT_SYMBOL(get_unmapped_area);
1579
1580 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1581 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1582 {
1583         struct vm_area_struct *vma = NULL;
1584
1585         if (mm) {
1586                 /* Check the cache first. */
1587                 /* (Cache hit rate is typically around 35%.) */
1588                 vma = mm->mmap_cache;
1589                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1590                         struct rb_node * rb_node;
1591
1592                         rb_node = mm->mm_rb.rb_node;
1593                         vma = NULL;
1594
1595                         while (rb_node) {
1596                                 struct vm_area_struct * vma_tmp;
1597
1598                                 vma_tmp = rb_entry(rb_node,
1599                                                 struct vm_area_struct, vm_rb);
1600
1601                                 if (vma_tmp->vm_end > addr) {
1602                                         vma = vma_tmp;
1603                                         if (vma_tmp->vm_start <= addr)
1604                                                 break;
1605                                         rb_node = rb_node->rb_left;
1606                                 } else
1607                                         rb_node = rb_node->rb_right;
1608                         }
1609                         if (vma)
1610                                 mm->mmap_cache = vma;
1611                 }
1612         }
1613         return vma;
1614 }
1615
1616 EXPORT_SYMBOL(find_vma);
1617
1618 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1619 struct vm_area_struct *
1620 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1621                         struct vm_area_struct **pprev)
1622 {
1623         struct vm_area_struct *vma = NULL, *prev = NULL;
1624         struct rb_node *rb_node;
1625         if (!mm)
1626                 goto out;
1627
1628         /* Guard against addr being lower than the first VMA */
1629         vma = mm->mmap;
1630
1631         /* Go through the RB tree quickly. */
1632         rb_node = mm->mm_rb.rb_node;
1633
1634         while (rb_node) {
1635                 struct vm_area_struct *vma_tmp;
1636                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1637
1638                 if (addr < vma_tmp->vm_end) {
1639                         rb_node = rb_node->rb_left;
1640                 } else {
1641                         prev = vma_tmp;
1642                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1643                                 break;
1644                         rb_node = rb_node->rb_right;
1645                 }
1646         }
1647
1648 out:
1649         *pprev = prev;
1650         return prev ? prev->vm_next : vma;
1651 }
1652
1653 /*
1654  * Verify that the stack growth is acceptable and
1655  * update accounting. This is shared with both the
1656  * grow-up and grow-down cases.
1657  */
1658 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1659 {
1660         struct mm_struct *mm = vma->vm_mm;
1661         struct rlimit *rlim = current->signal->rlim;
1662         unsigned long new_start;
1663
1664         /* address space limit tests */
1665         if (!may_expand_vm(mm, grow))
1666                 return -ENOMEM;
1667
1668         /* Stack limit test */
1669         if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1670                 return -ENOMEM;
1671
1672         /* mlock limit tests */
1673         if (vma->vm_flags & VM_LOCKED) {
1674                 unsigned long locked;
1675                 unsigned long limit;
1676                 locked = mm->locked_vm + grow;
1677                 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1678                 limit >>= PAGE_SHIFT;
1679                 if (locked > limit && !capable(CAP_IPC_LOCK))
1680                         return -ENOMEM;
1681         }
1682
1683         /* Check to ensure the stack will not grow into a hugetlb-only region */
1684         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1685                         vma->vm_end - size;
1686         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1687                 return -EFAULT;
1688
1689         /*
1690          * Overcommit..  This must be the final test, as it will
1691          * update security statistics.
1692          */
1693         if (security_vm_enough_memory_mm(mm, grow))
1694                 return -ENOMEM;
1695
1696         /* Ok, everything looks good - let it rip */
1697         mm->total_vm += grow;
1698         if (vma->vm_flags & VM_LOCKED)
1699                 mm->locked_vm += grow;
1700         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1701         return 0;
1702 }
1703
1704 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1705 /*
1706  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1707  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1708  */
1709 #ifndef CONFIG_IA64
1710 static
1711 #endif
1712 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1713 {
1714         int error;
1715
1716         if (!(vma->vm_flags & VM_GROWSUP))
1717                 return -EFAULT;
1718
1719         /*
1720          * We must make sure the anon_vma is allocated
1721          * so that the anon_vma locking is not a noop.
1722          */
1723         if (unlikely(anon_vma_prepare(vma)))
1724                 return -ENOMEM;
1725         vma_lock_anon_vma(vma);
1726
1727         /*
1728          * vma->vm_start/vm_end cannot change under us because the caller
1729          * is required to hold the mmap_sem in read mode.  We need the
1730          * anon_vma lock to serialize against concurrent expand_stacks.
1731          * Also guard against wrapping around to address 0.
1732          */
1733         if (address < PAGE_ALIGN(address+4))
1734                 address = PAGE_ALIGN(address+4);
1735         else {
1736                 vma_unlock_anon_vma(vma);
1737                 return -ENOMEM;
1738         }
1739         error = 0;
1740
1741         /* Somebody else might have raced and expanded it already */
1742         if (address > vma->vm_end) {
1743                 unsigned long size, grow;
1744
1745                 size = address - vma->vm_start;
1746                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1747
1748                 error = acct_stack_growth(vma, size, grow);
1749                 if (!error) {
1750                         vma->vm_end = address;
1751                         perf_event_mmap(vma);
1752                 }
1753         }
1754         vma_unlock_anon_vma(vma);
1755         return error;
1756 }
1757 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1758
1759 /*
1760  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1761  */
1762 static int expand_downwards(struct vm_area_struct *vma,
1763                                    unsigned long address)
1764 {
1765         int error;
1766
1767         /*
1768          * We must make sure the anon_vma is allocated
1769          * so that the anon_vma locking is not a noop.
1770          */
1771         if (unlikely(anon_vma_prepare(vma)))
1772                 return -ENOMEM;
1773
1774         address &= PAGE_MASK;
1775         error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1776         if (error)
1777                 return error;
1778
1779         vma_lock_anon_vma(vma);
1780
1781         /*
1782          * vma->vm_start/vm_end cannot change under us because the caller
1783          * is required to hold the mmap_sem in read mode.  We need the
1784          * anon_vma lock to serialize against concurrent expand_stacks.
1785          */
1786
1787         /* Somebody else might have raced and expanded it already */
1788         if (address < vma->vm_start) {
1789                 unsigned long size, grow;
1790
1791                 size = vma->vm_end - address;
1792                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1793
1794                 error = acct_stack_growth(vma, size, grow);
1795                 if (!error) {
1796                         vma->vm_start = address;
1797                         vma->vm_pgoff -= grow;
1798                         perf_event_mmap(vma);
1799                 }
1800         }
1801         vma_unlock_anon_vma(vma);
1802         return error;
1803 }
1804
1805 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1806 {
1807         return expand_downwards(vma, address);
1808 }
1809
1810 #ifdef CONFIG_STACK_GROWSUP
1811 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1812 {
1813         return expand_upwards(vma, address);
1814 }
1815
1816 struct vm_area_struct *
1817 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1818 {
1819         struct vm_area_struct *vma, *prev;
1820
1821         addr &= PAGE_MASK;
1822         vma = find_vma_prev(mm, addr, &prev);
1823         if (vma && (vma->vm_start <= addr))
1824                 return vma;
1825         if (!prev || expand_stack(prev, addr))
1826                 return NULL;
1827         if (prev->vm_flags & VM_LOCKED) {
1828                 mlock_vma_pages_range(prev, addr, prev->vm_end);
1829         }
1830         return prev;
1831 }
1832 #else
1833 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1834 {
1835         return expand_downwards(vma, address);
1836 }
1837
1838 struct vm_area_struct *
1839 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1840 {
1841         struct vm_area_struct * vma;
1842         unsigned long start;
1843
1844         addr &= PAGE_MASK;
1845         vma = find_vma(mm,addr);
1846         if (!vma)
1847                 return NULL;
1848         if (vma->vm_start <= addr)
1849                 return vma;
1850         if (!(vma->vm_flags & VM_GROWSDOWN))
1851                 return NULL;
1852         start = vma->vm_start;
1853         if (expand_stack(vma, addr))
1854                 return NULL;
1855         if (vma->vm_flags & VM_LOCKED) {
1856                 mlock_vma_pages_range(vma, addr, start);
1857         }
1858         return vma;
1859 }
1860 #endif
1861
1862 /*
1863  * Ok - we have the memory areas we should free on the vma list,
1864  * so release them, and do the vma updates.
1865  *
1866  * Called with the mm semaphore held.
1867  */
1868 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1869 {
1870         /* Update high watermark before we lower total_vm */
1871         update_hiwater_vm(mm);
1872         do {
1873                 long nrpages = vma_pages(vma);
1874
1875                 mm->total_vm -= nrpages;
1876                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1877                 vma = remove_vma(vma);
1878         } while (vma);
1879         validate_mm(mm);
1880 }
1881
1882 /*
1883  * Get rid of page table information in the indicated region.
1884  *
1885  * Called with the mm semaphore held.
1886  */
1887 static void unmap_region(struct mm_struct *mm,
1888                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1889                 unsigned long start, unsigned long end)
1890 {
1891         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1892         struct mmu_gather *tlb;
1893         unsigned long nr_accounted = 0;
1894
1895         lru_add_drain();
1896         tlb = tlb_gather_mmu(mm, 0);
1897         update_hiwater_rss(mm);
1898         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1899         vm_unacct_memory(nr_accounted);
1900         free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1901                                  next? next->vm_start: 0);
1902         tlb_finish_mmu(tlb, start, end);
1903 }
1904
1905 /*
1906  * Create a list of vma's touched by the unmap, removing them from the mm's
1907  * vma list as we go..
1908  */
1909 static void
1910 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1911         struct vm_area_struct *prev, unsigned long end)
1912 {
1913         struct vm_area_struct **insertion_point;
1914         struct vm_area_struct *tail_vma = NULL;
1915         unsigned long addr;
1916
1917         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1918         do {
1919                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1920                 mm->map_count--;
1921                 tail_vma = vma;
1922                 vma = vma->vm_next;
1923         } while (vma && vma->vm_start < end);
1924         *insertion_point = vma;
1925         tail_vma->vm_next = NULL;
1926         if (mm->unmap_area == arch_unmap_area)
1927                 addr = prev ? prev->vm_end : mm->mmap_base;
1928         else
1929                 addr = vma ?  vma->vm_start : mm->mmap_base;
1930         mm->unmap_area(mm, addr);
1931         mm->mmap_cache = NULL;          /* Kill the cache. */
1932 }
1933
1934 /*
1935  * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1936  * munmap path where it doesn't make sense to fail.
1937  */
1938 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1939               unsigned long addr, int new_below)
1940 {
1941         struct mempolicy *pol;
1942         struct vm_area_struct *new;
1943         int err = -ENOMEM;
1944
1945         if (is_vm_hugetlb_page(vma) && (addr &
1946                                         ~(huge_page_mask(hstate_vma(vma)))))
1947                 return -EINVAL;
1948
1949         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1950         if (!new)
1951                 goto out_err;
1952
1953         /* most fields are the same, copy all, and then fixup */
1954         *new = *vma;
1955
1956         INIT_LIST_HEAD(&new->anon_vma_chain);
1957
1958         if (new_below)
1959                 new->vm_end = addr;
1960         else {
1961                 new->vm_start = addr;
1962                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1963         }
1964
1965         pol = mpol_dup(vma_policy(vma));
1966         if (IS_ERR(pol)) {
1967                 err = PTR_ERR(pol);
1968                 goto out_free_vma;
1969         }
1970         vma_set_policy(new, pol);
1971
1972         if (anon_vma_clone(new, vma))
1973                 goto out_free_mpol;
1974
1975         if (new->vm_file) {
1976                 get_file(new->vm_file);
1977                 if (vma->vm_flags & VM_EXECUTABLE)
1978                         added_exe_file_vma(mm);
1979         }
1980
1981         if (new->vm_ops && new->vm_ops->open)
1982                 new->vm_ops->open(new);
1983
1984         if (new_below)
1985                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1986                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1987         else
1988                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1989
1990         /* Success. */
1991         if (!err)
1992                 return 0;
1993
1994         /* Clean everything up if vma_adjust failed. */
1995         if (new->vm_ops && new->vm_ops->close)
1996                 new->vm_ops->close(new);
1997         if (new->vm_file) {
1998                 if (vma->vm_flags & VM_EXECUTABLE)
1999                         removed_exe_file_vma(mm);
2000                 fput(new->vm_file);
2001         }
2002  out_free_mpol:
2003         mpol_put(pol);
2004  out_free_vma:
2005         kmem_cache_free(vm_area_cachep, new);
2006  out_err:
2007         return err;
2008 }
2009
2010 /*
2011  * Split a vma into two pieces at address 'addr', a new vma is allocated
2012  * either for the first part or the tail.
2013  */
2014 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2015               unsigned long addr, int new_below)
2016 {
2017         if (mm->map_count >= sysctl_max_map_count)
2018                 return -ENOMEM;
2019
2020         return __split_vma(mm, vma, addr, new_below);
2021 }
2022
2023 /* Munmap is split into 2 main parts -- this part which finds
2024  * what needs doing, and the areas themselves, which do the
2025  * work.  This now handles partial unmappings.
2026  * Jeremy Fitzhardinge <jeremy@goop.org>
2027  */
2028 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2029 {
2030         unsigned long end;
2031         struct vm_area_struct *vma, *prev, *last;
2032
2033         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2034                 return -EINVAL;
2035
2036         if ((len = PAGE_ALIGN(len)) == 0)
2037                 return -EINVAL;
2038
2039         /* Find the first overlapping VMA */
2040         vma = find_vma_prev(mm, start, &prev);
2041         if (!vma)
2042                 return 0;
2043         /* we have  start < vma->vm_end  */
2044
2045         /* if it doesn't overlap, we have nothing.. */
2046         end = start + len;
2047         if (vma->vm_start >= end)
2048                 return 0;
2049
2050         /*
2051          * If we need to split any vma, do it now to save pain later.
2052          *
2053          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2054          * unmapped vm_area_struct will remain in use: so lower split_vma
2055          * places tmp vma above, and higher split_vma places tmp vma below.
2056          */
2057         if (start > vma->vm_start) {
2058                 int error;
2059
2060                 /*
2061                  * Make sure that map_count on return from munmap() will
2062                  * not exceed its limit; but let map_count go just above
2063                  * its limit temporarily, to help free resources as expected.
2064                  */
2065                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2066                         return -ENOMEM;
2067
2068                 error = __split_vma(mm, vma, start, 0);
2069                 if (error)
2070                         return error;
2071                 prev = vma;
2072         }
2073
2074         /* Does it split the last one? */
2075         last = find_vma(mm, end);
2076         if (last && end > last->vm_start) {
2077                 int error = __split_vma(mm, last, end, 1);
2078                 if (error)
2079                         return error;
2080         }
2081         vma = prev? prev->vm_next: mm->mmap;
2082
2083         /*
2084          * unlock any mlock()ed ranges before detaching vmas
2085          */
2086         if (mm->locked_vm) {
2087                 struct vm_area_struct *tmp = vma;
2088                 while (tmp && tmp->vm_start < end) {
2089                         if (tmp->vm_flags & VM_LOCKED) {
2090                                 mm->locked_vm -= vma_pages(tmp);
2091                                 munlock_vma_pages_all(tmp);
2092                         }
2093                         tmp = tmp->vm_next;
2094                 }
2095         }
2096
2097         /*
2098          * Remove the vma's, and unmap the actual pages
2099          */
2100         detach_vmas_to_be_unmapped(mm, vma, prev, end);
2101         unmap_region(mm, vma, prev, start, end);
2102
2103         /* Fix up all other VM information */
2104         remove_vma_list(mm, vma);
2105
2106         return 0;
2107 }
2108
2109 EXPORT_SYMBOL(do_munmap);
2110
2111 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2112 {
2113         int ret;
2114         struct mm_struct *mm = current->mm;
2115
2116         profile_munmap(addr);
2117
2118         down_write(&mm->mmap_sem);
2119         ret = do_munmap(mm, addr, len);
2120         up_write(&mm->mmap_sem);
2121         return ret;
2122 }
2123
2124 static inline void verify_mm_writelocked(struct mm_struct *mm)
2125 {
2126 #ifdef CONFIG_DEBUG_VM
2127         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2128                 WARN_ON(1);
2129                 up_read(&mm->mmap_sem);
2130         }
2131 #endif
2132 }
2133
2134 /*
2135  *  this is really a simplified "do_mmap".  it only handles
2136  *  anonymous maps.  eventually we may be able to do some
2137  *  brk-specific accounting here.
2138  */
2139 unsigned long do_brk(unsigned long addr, unsigned long len)
2140 {
2141         struct mm_struct * mm = current->mm;
2142         struct vm_area_struct * vma, * prev;
2143         unsigned long flags;
2144         struct rb_node ** rb_link, * rb_parent;
2145         pgoff_t pgoff = addr >> PAGE_SHIFT;
2146         int error;
2147
2148         len = PAGE_ALIGN(len);
2149         if (!len)
2150                 return addr;
2151
2152         error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2153         if (error)
2154                 return error;
2155
2156         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2157
2158         error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2159         if (error & ~PAGE_MASK)
2160                 return error;
2161
2162         /*
2163          * mlock MCL_FUTURE?
2164          */
2165         if (mm->def_flags & VM_LOCKED) {
2166                 unsigned long locked, lock_limit;
2167                 locked = len >> PAGE_SHIFT;
2168                 locked += mm->locked_vm;
2169                 lock_limit = rlimit(RLIMIT_MEMLOCK);
2170                 lock_limit >>= PAGE_SHIFT;
2171                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2172                         return -EAGAIN;
2173         }
2174
2175         /*
2176          * mm->mmap_sem is required to protect against another thread
2177          * changing the mappings in case we sleep.
2178          */
2179         verify_mm_writelocked(mm);
2180
2181         /*
2182          * Clear old maps.  this also does some error checking for us
2183          */
2184  munmap_back:
2185         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2186         if (vma && vma->vm_start < addr + len) {
2187                 if (do_munmap(mm, addr, len))
2188                         return -ENOMEM;
2189                 goto munmap_back;
2190         }
2191
2192         /* Check against address space limits *after* clearing old maps... */
2193         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2194                 return -ENOMEM;
2195
2196         if (mm->map_count > sysctl_max_map_count)
2197                 return -ENOMEM;
2198
2199         if (security_vm_enough_memory(len >> PAGE_SHIFT))
2200                 return -ENOMEM;
2201
2202         /* Can we just expand an old private anonymous mapping? */
2203         vma = vma_merge(mm, prev, addr, addr + len, flags,
2204                                         NULL, NULL, pgoff, NULL);
2205         if (vma)
2206                 goto out;
2207
2208         /*
2209          * create a vma struct for an anonymous mapping
2210          */
2211         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2212         if (!vma) {
2213                 vm_unacct_memory(len >> PAGE_SHIFT);
2214                 return -ENOMEM;
2215         }
2216
2217         INIT_LIST_HEAD(&vma->anon_vma_chain);
2218         vma->vm_mm = mm;
2219         vma->vm_start = addr;
2220         vma->vm_end = addr + len;
2221         vma->vm_pgoff = pgoff;
2222         vma->vm_flags = flags;
2223         vma->vm_page_prot = vm_get_page_prot(flags);
2224         vma_link(mm, vma, prev, rb_link, rb_parent);
2225 out:
2226         perf_event_mmap(vma);
2227         mm->total_vm += len >> PAGE_SHIFT;
2228         if (flags & VM_LOCKED) {
2229                 if (!mlock_vma_pages_range(vma, addr, addr + len))
2230                         mm->locked_vm += (len >> PAGE_SHIFT);
2231         }
2232         return addr;
2233 }
2234
2235 EXPORT_SYMBOL(do_brk);
2236
2237 /* Release all mmaps. */
2238 void exit_mmap(struct mm_struct *mm)
2239 {
2240         struct mmu_gather *tlb;
2241         struct vm_area_struct *vma;
2242         unsigned long nr_accounted = 0;
2243         unsigned long end;
2244
2245         /* mm's last user has gone, and its about to be pulled down */
2246         mmu_notifier_release(mm);
2247
2248         if (mm->locked_vm) {
2249                 vma = mm->mmap;
2250                 while (vma) {
2251                         if (vma->vm_flags & VM_LOCKED)
2252                                 munlock_vma_pages_all(vma);
2253                         vma = vma->vm_next;
2254                 }
2255         }
2256
2257         arch_exit_mmap(mm);
2258
2259         vma = mm->mmap;
2260         if (!vma)       /* Can happen if dup_mmap() received an OOM */
2261                 return;
2262
2263         lru_add_drain();
2264         flush_cache_mm(mm);
2265         tlb = tlb_gather_mmu(mm, 1);
2266         /* update_hiwater_rss(mm) here? but nobody should be looking */
2267         /* Use -1 here to ensure all VMAs in the mm are unmapped */
2268         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2269         vm_unacct_memory(nr_accounted);
2270
2271         free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2272         tlb_finish_mmu(tlb, 0, end);
2273
2274         /*
2275          * Walk the list again, actually closing and freeing it,
2276          * with preemption enabled, without holding any MM locks.
2277          */
2278         while (vma)
2279                 vma = remove_vma(vma);
2280
2281         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2282 }
2283
2284 /* Insert vm structure into process list sorted by address
2285  * and into the inode's i_mmap tree.  If vm_file is non-NULL
2286  * then i_mmap_lock is taken here.
2287  */
2288 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2289 {
2290         struct vm_area_struct * __vma, * prev;
2291         struct rb_node ** rb_link, * rb_parent;
2292
2293         /*
2294          * The vm_pgoff of a purely anonymous vma should be irrelevant
2295          * until its first write fault, when page's anon_vma and index
2296          * are set.  But now set the vm_pgoff it will almost certainly
2297          * end up with (unless mremap moves it elsewhere before that
2298          * first wfault), so /proc/pid/maps tells a consistent story.
2299          *
2300          * By setting it to reflect the virtual start address of the
2301          * vma, merges and splits can happen in a seamless way, just
2302          * using the existing file pgoff checks and manipulations.
2303          * Similarly in do_mmap_pgoff and in do_brk.
2304          */
2305         if (!vma->vm_file) {
2306                 BUG_ON(vma->anon_vma);
2307                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2308         }
2309         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2310         if (__vma && __vma->vm_start < vma->vm_end)
2311                 return -ENOMEM;
2312         if ((vma->vm_flags & VM_ACCOUNT) &&
2313              security_vm_enough_memory_mm(mm, vma_pages(vma)))
2314                 return -ENOMEM;
2315         vma_link(mm, vma, prev, rb_link, rb_parent);
2316         return 0;
2317 }
2318
2319 /*
2320  * Copy the vma structure to a new location in the same mm,
2321  * prior to moving page table entries, to effect an mremap move.
2322  */
2323 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2324         unsigned long addr, unsigned long len, pgoff_t pgoff)
2325 {
2326         struct vm_area_struct *vma = *vmap;
2327         unsigned long vma_start = vma->vm_start;
2328         struct mm_struct *mm = vma->vm_mm;
2329         struct vm_area_struct *new_vma, *prev;
2330         struct rb_node **rb_link, *rb_parent;
2331         struct mempolicy *pol;
2332
2333         /*
2334          * If anonymous vma has not yet been faulted, update new pgoff
2335          * to match new location, to increase its chance of merging.
2336          */
2337         if (!vma->vm_file && !vma->anon_vma)
2338                 pgoff = addr >> PAGE_SHIFT;
2339
2340         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2341         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2342                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2343         if (new_vma) {
2344                 /*
2345                  * Source vma may have been merged into new_vma
2346                  */
2347                 if (vma_start >= new_vma->vm_start &&
2348                     vma_start < new_vma->vm_end)
2349                         *vmap = new_vma;
2350         } else {
2351                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2352                 if (new_vma) {
2353                         *new_vma = *vma;
2354                         pol = mpol_dup(vma_policy(vma));
2355                         if (IS_ERR(pol))
2356                                 goto out_free_vma;
2357                         INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2358                         if (anon_vma_clone(new_vma, vma))
2359                                 goto out_free_mempol;
2360                         vma_set_policy(new_vma, pol);
2361                         new_vma->vm_start = addr;
2362                         new_vma->vm_end = addr + len;
2363                         new_vma->vm_pgoff = pgoff;
2364                         if (new_vma->vm_file) {
2365                                 get_file(new_vma->vm_file);
2366                                 if (vma->vm_flags & VM_EXECUTABLE)
2367                                         added_exe_file_vma(mm);
2368                         }
2369                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2370                                 new_vma->vm_ops->open(new_vma);
2371                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2372                 }
2373         }
2374         return new_vma;
2375
2376  out_free_mempol:
2377         mpol_put(pol);
2378  out_free_vma:
2379         kmem_cache_free(vm_area_cachep, new_vma);
2380         return NULL;
2381 }
2382
2383 /*
2384  * Return true if the calling process may expand its vm space by the passed
2385  * number of pages
2386  */
2387 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2388 {
2389         unsigned long cur = mm->total_vm;       /* pages */
2390         unsigned long lim;
2391
2392         lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2393
2394         if (cur + npages > lim)
2395                 return 0;
2396         return 1;
2397 }
2398
2399
2400 static int special_mapping_fault(struct vm_area_struct *vma,
2401                                 struct vm_fault *vmf)
2402 {
2403         pgoff_t pgoff;
2404         struct page **pages;
2405
2406         /*
2407          * special mappings have no vm_file, and in that case, the mm
2408          * uses vm_pgoff internally. So we have to subtract it from here.
2409          * We are allowed to do this because we are the mm; do not copy
2410          * this code into drivers!
2411          */
2412         pgoff = vmf->pgoff - vma->vm_pgoff;
2413
2414         for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2415                 pgoff--;
2416
2417         if (*pages) {
2418                 struct page *page = *pages;
2419                 get_page(page);
2420                 vmf->page = page;
2421                 return 0;
2422         }
2423
2424         return VM_FAULT_SIGBUS;
2425 }
2426
2427 /*
2428  * Having a close hook prevents vma merging regardless of flags.
2429  */
2430 static void special_mapping_close(struct vm_area_struct *vma)
2431 {
2432 }
2433
2434 static const struct vm_operations_struct special_mapping_vmops = {
2435         .close = special_mapping_close,
2436         .fault = special_mapping_fault,
2437 };
2438
2439 /*
2440  * Called with mm->mmap_sem held for writing.
2441  * Insert a new vma covering the given region, with the given flags.
2442  * Its pages are supplied by the given array of struct page *.
2443  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2444  * The region past the last page supplied will always produce SIGBUS.
2445  * The array pointer and the pages it points to are assumed to stay alive
2446  * for as long as this mapping might exist.
2447  */
2448 int install_special_mapping(struct mm_struct *mm,
2449                             unsigned long addr, unsigned long len,
2450                             unsigned long vm_flags, struct page **pages)
2451 {
2452         struct vm_area_struct *vma;
2453
2454         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2455         if (unlikely(vma == NULL))
2456                 return -ENOMEM;
2457
2458         INIT_LIST_HEAD(&vma->anon_vma_chain);
2459         vma->vm_mm = mm;
2460         vma->vm_start = addr;
2461         vma->vm_end = addr + len;
2462
2463         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2464         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2465
2466         vma->vm_ops = &special_mapping_vmops;
2467         vma->vm_private_data = pages;
2468
2469         if (unlikely(insert_vm_struct(mm, vma))) {
2470                 kmem_cache_free(vm_area_cachep, vma);
2471                 return -ENOMEM;
2472         }
2473
2474         mm->total_vm += len >> PAGE_SHIFT;
2475
2476         perf_event_mmap(vma);
2477
2478         return 0;
2479 }
2480
2481 static DEFINE_MUTEX(mm_all_locks_mutex);
2482
2483 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2484 {
2485         if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2486                 /*
2487                  * The LSB of head.next can't change from under us
2488                  * because we hold the mm_all_locks_mutex.
2489                  */
2490                 spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
2491                 /*
2492                  * We can safely modify head.next after taking the
2493                  * anon_vma->root->lock. If some other vma in this mm shares
2494                  * the same anon_vma we won't take it again.
2495                  *
2496                  * No need of atomic instructions here, head.next
2497                  * can't change from under us thanks to the
2498                  * anon_vma->root->lock.
2499                  */
2500                 if (__test_and_set_bit(0, (unsigned long *)
2501                                        &anon_vma->root->head.next))
2502                         BUG();
2503         }
2504 }
2505
2506 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2507 {
2508         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2509                 /*
2510                  * AS_MM_ALL_LOCKS can't change from under us because
2511                  * we hold the mm_all_locks_mutex.
2512                  *
2513                  * Operations on ->flags have to be atomic because
2514                  * even if AS_MM_ALL_LOCKS is stable thanks to the
2515                  * mm_all_locks_mutex, there may be other cpus
2516                  * changing other bitflags in parallel to us.
2517                  */
2518                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2519                         BUG();
2520                 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2521         }
2522 }
2523
2524 /*
2525  * This operation locks against the VM for all pte/vma/mm related
2526  * operations that could ever happen on a certain mm. This includes
2527  * vmtruncate, try_to_unmap, and all page faults.
2528  *
2529  * The caller must take the mmap_sem in write mode before calling
2530  * mm_take_all_locks(). The caller isn't allowed to release the
2531  * mmap_sem until mm_drop_all_locks() returns.
2532  *
2533  * mmap_sem in write mode is required in order to block all operations
2534  * that could modify pagetables and free pages without need of
2535  * altering the vma layout (for example populate_range() with
2536  * nonlinear vmas). It's also needed in write mode to avoid new
2537  * anon_vmas to be associated with existing vmas.
2538  *
2539  * A single task can't take more than one mm_take_all_locks() in a row
2540  * or it would deadlock.
2541  *
2542  * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2543  * mapping->flags avoid to take the same lock twice, if more than one
2544  * vma in this mm is backed by the same anon_vma or address_space.
2545  *
2546  * We can take all the locks in random order because the VM code
2547  * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2548  * takes more than one of them in a row. Secondly we're protected
2549  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2550  *
2551  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2552  * that may have to take thousand of locks.
2553  *
2554  * mm_take_all_locks() can fail if it's interrupted by signals.
2555  */
2556 int mm_take_all_locks(struct mm_struct *mm)
2557 {
2558         struct vm_area_struct *vma;
2559         struct anon_vma_chain *avc;
2560         int ret = -EINTR;
2561
2562         BUG_ON(down_read_trylock(&mm->mmap_sem));
2563
2564         mutex_lock(&mm_all_locks_mutex);
2565
2566         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2567                 if (signal_pending(current))
2568                         goto out_unlock;
2569                 if (vma->vm_file && vma->vm_file->f_mapping)
2570                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
2571         }
2572
2573         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2574                 if (signal_pending(current))
2575                         goto out_unlock;
2576                 if (vma->anon_vma)
2577                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2578                                 vm_lock_anon_vma(mm, avc->anon_vma);
2579         }
2580
2581         ret = 0;
2582
2583 out_unlock:
2584         if (ret)
2585                 mm_drop_all_locks(mm);
2586
2587         return ret;
2588 }
2589
2590 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2591 {
2592         if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2593                 /*
2594                  * The LSB of head.next can't change to 0 from under
2595                  * us because we hold the mm_all_locks_mutex.
2596                  *
2597                  * We must however clear the bitflag before unlocking
2598                  * the vma so the users using the anon_vma->head will
2599                  * never see our bitflag.
2600                  *
2601                  * No need of atomic instructions here, head.next
2602                  * can't change from under us until we release the
2603                  * anon_vma->root->lock.
2604                  */
2605                 if (!__test_and_clear_bit(0, (unsigned long *)
2606                                           &anon_vma->root->head.next))
2607                         BUG();
2608                 anon_vma_unlock(anon_vma);
2609         }
2610 }
2611
2612 static void vm_unlock_mapping(struct address_space *mapping)
2613 {
2614         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2615                 /*
2616                  * AS_MM_ALL_LOCKS can't change to 0 from under us
2617                  * because we hold the mm_all_locks_mutex.
2618                  */
2619                 spin_unlock(&mapping->i_mmap_lock);
2620                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2621                                         &mapping->flags))
2622                         BUG();
2623         }
2624 }
2625
2626 /*
2627  * The mmap_sem cannot be released by the caller until
2628  * mm_drop_all_locks() returns.
2629  */
2630 void mm_drop_all_locks(struct mm_struct *mm)
2631 {
2632         struct vm_area_struct *vma;
2633         struct anon_vma_chain *avc;
2634
2635         BUG_ON(down_read_trylock(&mm->mmap_sem));
2636         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2637
2638         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2639                 if (vma->anon_vma)
2640                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2641                                 vm_unlock_anon_vma(avc->anon_vma);
2642                 if (vma->vm_file && vma->vm_file->f_mapping)
2643                         vm_unlock_mapping(vma->vm_file->f_mapping);
2644         }
2645
2646         mutex_unlock(&mm_all_locks_mutex);
2647 }
2648
2649 /*
2650  * initialise the VMA slab
2651  */
2652 void __init mmap_init(void)
2653 {
2654         int ret;
2655
2656         ret = percpu_counter_init(&vm_committed_as, 0);
2657         VM_BUG_ON(ret);
2658 }