mm: get rid of the most spurious find_vma_prev() users
[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 #include <linux/audit.h>
32 #include <linux/khugepaged.h>
33
34 #include <asm/uaccess.h>
35 #include <asm/cacheflush.h>
36 #include <asm/tlb.h>
37 #include <asm/mmu_context.h>
38
39 #include "internal.h"
40
41 #ifndef arch_mmap_check
42 #define arch_mmap_check(addr, len, flags)       (0)
43 #endif
44
45 #ifndef arch_rebalance_pgtables
46 #define arch_rebalance_pgtables(addr, len)              (addr)
47 #endif
48
49 static void unmap_region(struct mm_struct *mm,
50                 struct vm_area_struct *vma, struct vm_area_struct *prev,
51                 unsigned long start, unsigned long end);
52
53 /*
54  * WARNING: the debugging will use recursive algorithms so never enable this
55  * unless you know what you are doing.
56  */
57 #undef DEBUG_MM_RB
58
59 /* description of effects of mapping type and prot in current implementation.
60  * this is due to the limited x86 page protection hardware.  The expected
61  * behavior is in parens:
62  *
63  * map_type     prot
64  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
65  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
66  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
67  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
68  *              
69  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
70  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
71  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
72  *
73  */
74 pgprot_t protection_map[16] = {
75         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
76         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
77 };
78
79 pgprot_t vm_get_page_prot(unsigned long vm_flags)
80 {
81         return __pgprot(pgprot_val(protection_map[vm_flags &
82                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
83                         pgprot_val(arch_vm_get_page_prot(vm_flags)));
84 }
85 EXPORT_SYMBOL(vm_get_page_prot);
86
87 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
88 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
89 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
90 /*
91  * Make sure vm_committed_as in one cacheline and not cacheline shared with
92  * other variables. It can be updated by several CPUs frequently.
93  */
94 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
95
96 /*
97  * Check that a process has enough memory to allocate a new virtual
98  * mapping. 0 means there is enough memory for the allocation to
99  * succeed and -ENOMEM implies there is not.
100  *
101  * We currently support three overcommit policies, which are set via the
102  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
103  *
104  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
105  * Additional code 2002 Jul 20 by Robert Love.
106  *
107  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
108  *
109  * Note this is a helper function intended to be used by LSMs which
110  * wish to use this logic.
111  */
112 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
113 {
114         unsigned long free, allowed;
115
116         vm_acct_memory(pages);
117
118         /*
119          * Sometimes we want to use more memory than we have
120          */
121         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
122                 return 0;
123
124         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
125                 unsigned long n;
126
127                 free = global_page_state(NR_FILE_PAGES);
128                 free += nr_swap_pages;
129
130                 /*
131                  * Any slabs which are created with the
132                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
133                  * which are reclaimable, under pressure.  The dentry
134                  * cache and most inode caches should fall into this
135                  */
136                 free += global_page_state(NR_SLAB_RECLAIMABLE);
137
138                 /*
139                  * Leave the last 3% for root
140                  */
141                 if (!cap_sys_admin)
142                         free -= free / 32;
143
144                 if (free > pages)
145                         return 0;
146
147                 /*
148                  * nr_free_pages() is very expensive on large systems,
149                  * only call if we're about to fail.
150                  */
151                 n = nr_free_pages();
152
153                 /*
154                  * Leave reserved pages. The pages are not for anonymous pages.
155                  */
156                 if (n <= totalreserve_pages)
157                         goto error;
158                 else
159                         n -= totalreserve_pages;
160
161                 /*
162                  * Leave the last 3% for root
163                  */
164                 if (!cap_sys_admin)
165                         n -= n / 32;
166                 free += n;
167
168                 if (free > pages)
169                         return 0;
170
171                 goto error;
172         }
173
174         allowed = (totalram_pages - hugetlb_total_pages())
175                 * sysctl_overcommit_ratio / 100;
176         /*
177          * Leave the last 3% for root
178          */
179         if (!cap_sys_admin)
180                 allowed -= allowed / 32;
181         allowed += total_swap_pages;
182
183         /* Don't let a single process grow too big:
184            leave 3% of the size of this process for other processes */
185         if (mm)
186                 allowed -= mm->total_vm / 32;
187
188         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
189                 return 0;
190 error:
191         vm_unacct_memory(pages);
192
193         return -ENOMEM;
194 }
195
196 /*
197  * Requires inode->i_mapping->i_mmap_mutex
198  */
199 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
200                 struct file *file, struct address_space *mapping)
201 {
202         if (vma->vm_flags & VM_DENYWRITE)
203                 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
204         if (vma->vm_flags & VM_SHARED)
205                 mapping->i_mmap_writable--;
206
207         flush_dcache_mmap_lock(mapping);
208         if (unlikely(vma->vm_flags & VM_NONLINEAR))
209                 list_del_init(&vma->shared.vm_set.list);
210         else
211                 vma_prio_tree_remove(vma, &mapping->i_mmap);
212         flush_dcache_mmap_unlock(mapping);
213 }
214
215 /*
216  * Unlink a file-based vm structure from its prio_tree, to hide
217  * vma from rmap and vmtruncate before freeing its page tables.
218  */
219 void unlink_file_vma(struct vm_area_struct *vma)
220 {
221         struct file *file = vma->vm_file;
222
223         if (file) {
224                 struct address_space *mapping = file->f_mapping;
225                 mutex_lock(&mapping->i_mmap_mutex);
226                 __remove_shared_vm_struct(vma, file, mapping);
227                 mutex_unlock(&mapping->i_mmap_mutex);
228         }
229 }
230
231 /*
232  * Close a vm structure and free it, returning the next.
233  */
234 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
235 {
236         struct vm_area_struct *next = vma->vm_next;
237
238         might_sleep();
239         if (vma->vm_ops && vma->vm_ops->close)
240                 vma->vm_ops->close(vma);
241         if (vma->vm_file) {
242                 fput(vma->vm_file);
243                 if (vma->vm_flags & VM_EXECUTABLE)
244                         removed_exe_file_vma(vma->vm_mm);
245         }
246         mpol_put(vma_policy(vma));
247         kmem_cache_free(vm_area_cachep, vma);
248         return next;
249 }
250
251 SYSCALL_DEFINE1(brk, unsigned long, brk)
252 {
253         unsigned long rlim, retval;
254         unsigned long newbrk, oldbrk;
255         struct mm_struct *mm = current->mm;
256         unsigned long min_brk;
257
258         down_write(&mm->mmap_sem);
259
260 #ifdef CONFIG_COMPAT_BRK
261         /*
262          * CONFIG_COMPAT_BRK can still be overridden by setting
263          * randomize_va_space to 2, which will still cause mm->start_brk
264          * to be arbitrarily shifted
265          */
266         if (current->brk_randomized)
267                 min_brk = mm->start_brk;
268         else
269                 min_brk = mm->end_data;
270 #else
271         min_brk = mm->start_brk;
272 #endif
273         if (brk < min_brk)
274                 goto out;
275
276         /*
277          * Check against rlimit here. If this check is done later after the test
278          * of oldbrk with newbrk then it can escape the test and let the data
279          * segment grow beyond its set limit the in case where the limit is
280          * not page aligned -Ram Gupta
281          */
282         rlim = rlimit(RLIMIT_DATA);
283         if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
284                         (mm->end_data - mm->start_data) > rlim)
285                 goto out;
286
287         newbrk = PAGE_ALIGN(brk);
288         oldbrk = PAGE_ALIGN(mm->brk);
289         if (oldbrk == newbrk)
290                 goto set_brk;
291
292         /* Always allow shrinking brk. */
293         if (brk <= mm->brk) {
294                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
295                         goto set_brk;
296                 goto out;
297         }
298
299         /* Check against existing mmap mappings. */
300         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
301                 goto out;
302
303         /* Ok, looks good - let it rip. */
304         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
305                 goto out;
306 set_brk:
307         mm->brk = brk;
308 out:
309         retval = mm->brk;
310         up_write(&mm->mmap_sem);
311         return retval;
312 }
313
314 #ifdef DEBUG_MM_RB
315 static int browse_rb(struct rb_root *root)
316 {
317         int i = 0, j;
318         struct rb_node *nd, *pn = NULL;
319         unsigned long prev = 0, pend = 0;
320
321         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
322                 struct vm_area_struct *vma;
323                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
324                 if (vma->vm_start < prev)
325                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
326                 if (vma->vm_start < pend)
327                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
328                 if (vma->vm_start > vma->vm_end)
329                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
330                 i++;
331                 pn = nd;
332                 prev = vma->vm_start;
333                 pend = vma->vm_end;
334         }
335         j = 0;
336         for (nd = pn; nd; nd = rb_prev(nd)) {
337                 j++;
338         }
339         if (i != j)
340                 printk("backwards %d, forwards %d\n", j, i), i = 0;
341         return i;
342 }
343
344 void validate_mm(struct mm_struct *mm)
345 {
346         int bug = 0;
347         int i = 0;
348         struct vm_area_struct *tmp = mm->mmap;
349         while (tmp) {
350                 tmp = tmp->vm_next;
351                 i++;
352         }
353         if (i != mm->map_count)
354                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
355         i = browse_rb(&mm->mm_rb);
356         if (i != mm->map_count)
357                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
358         BUG_ON(bug);
359 }
360 #else
361 #define validate_mm(mm) do { } while (0)
362 #endif
363
364 static struct vm_area_struct *
365 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
366                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
367                 struct rb_node ** rb_parent)
368 {
369         struct vm_area_struct * vma;
370         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
371
372         __rb_link = &mm->mm_rb.rb_node;
373         rb_prev = __rb_parent = NULL;
374         vma = NULL;
375
376         while (*__rb_link) {
377                 struct vm_area_struct *vma_tmp;
378
379                 __rb_parent = *__rb_link;
380                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
381
382                 if (vma_tmp->vm_end > addr) {
383                         vma = vma_tmp;
384                         if (vma_tmp->vm_start <= addr)
385                                 break;
386                         __rb_link = &__rb_parent->rb_left;
387                 } else {
388                         rb_prev = __rb_parent;
389                         __rb_link = &__rb_parent->rb_right;
390                 }
391         }
392
393         *pprev = NULL;
394         if (rb_prev)
395                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
396         *rb_link = __rb_link;
397         *rb_parent = __rb_parent;
398         return vma;
399 }
400
401 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
402                 struct rb_node **rb_link, struct rb_node *rb_parent)
403 {
404         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
405         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
406 }
407
408 static void __vma_link_file(struct vm_area_struct *vma)
409 {
410         struct file *file;
411
412         file = vma->vm_file;
413         if (file) {
414                 struct address_space *mapping = file->f_mapping;
415
416                 if (vma->vm_flags & VM_DENYWRITE)
417                         atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
418                 if (vma->vm_flags & VM_SHARED)
419                         mapping->i_mmap_writable++;
420
421                 flush_dcache_mmap_lock(mapping);
422                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
423                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
424                 else
425                         vma_prio_tree_insert(vma, &mapping->i_mmap);
426                 flush_dcache_mmap_unlock(mapping);
427         }
428 }
429
430 static void
431 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
432         struct vm_area_struct *prev, struct rb_node **rb_link,
433         struct rb_node *rb_parent)
434 {
435         __vma_link_list(mm, vma, prev, rb_parent);
436         __vma_link_rb(mm, vma, rb_link, rb_parent);
437 }
438
439 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
440                         struct vm_area_struct *prev, struct rb_node **rb_link,
441                         struct rb_node *rb_parent)
442 {
443         struct address_space *mapping = NULL;
444
445         if (vma->vm_file)
446                 mapping = vma->vm_file->f_mapping;
447
448         if (mapping)
449                 mutex_lock(&mapping->i_mmap_mutex);
450
451         __vma_link(mm, vma, prev, rb_link, rb_parent);
452         __vma_link_file(vma);
453
454         if (mapping)
455                 mutex_unlock(&mapping->i_mmap_mutex);
456
457         mm->map_count++;
458         validate_mm(mm);
459 }
460
461 /*
462  * Helper for vma_adjust in the split_vma insert case:
463  * insert vm structure into list and rbtree and anon_vma,
464  * but it has already been inserted into prio_tree earlier.
465  */
466 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
467 {
468         struct vm_area_struct *__vma, *prev;
469         struct rb_node **rb_link, *rb_parent;
470
471         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
472         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
473         __vma_link(mm, vma, prev, rb_link, rb_parent);
474         mm->map_count++;
475 }
476
477 static inline void
478 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
479                 struct vm_area_struct *prev)
480 {
481         struct vm_area_struct *next = vma->vm_next;
482
483         prev->vm_next = next;
484         if (next)
485                 next->vm_prev = prev;
486         rb_erase(&vma->vm_rb, &mm->mm_rb);
487         if (mm->mmap_cache == vma)
488                 mm->mmap_cache = prev;
489 }
490
491 /*
492  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
493  * is already present in an i_mmap tree without adjusting the tree.
494  * The following helper function should be used when such adjustments
495  * are necessary.  The "insert" vma (if any) is to be inserted
496  * before we drop the necessary locks.
497  */
498 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
499         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
500 {
501         struct mm_struct *mm = vma->vm_mm;
502         struct vm_area_struct *next = vma->vm_next;
503         struct vm_area_struct *importer = NULL;
504         struct address_space *mapping = NULL;
505         struct prio_tree_root *root = NULL;
506         struct anon_vma *anon_vma = NULL;
507         struct file *file = vma->vm_file;
508         long adjust_next = 0;
509         int remove_next = 0;
510
511         if (next && !insert) {
512                 struct vm_area_struct *exporter = NULL;
513
514                 if (end >= next->vm_end) {
515                         /*
516                          * vma expands, overlapping all the next, and
517                          * perhaps the one after too (mprotect case 6).
518                          */
519 again:                  remove_next = 1 + (end > next->vm_end);
520                         end = next->vm_end;
521                         exporter = next;
522                         importer = vma;
523                 } else if (end > next->vm_start) {
524                         /*
525                          * vma expands, overlapping part of the next:
526                          * mprotect case 5 shifting the boundary up.
527                          */
528                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
529                         exporter = next;
530                         importer = vma;
531                 } else if (end < vma->vm_end) {
532                         /*
533                          * vma shrinks, and !insert tells it's not
534                          * split_vma inserting another: so it must be
535                          * mprotect case 4 shifting the boundary down.
536                          */
537                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
538                         exporter = vma;
539                         importer = next;
540                 }
541
542                 /*
543                  * Easily overlooked: when mprotect shifts the boundary,
544                  * make sure the expanding vma has anon_vma set if the
545                  * shrinking vma had, to cover any anon pages imported.
546                  */
547                 if (exporter && exporter->anon_vma && !importer->anon_vma) {
548                         if (anon_vma_clone(importer, exporter))
549                                 return -ENOMEM;
550                         importer->anon_vma = exporter->anon_vma;
551                 }
552         }
553
554         if (file) {
555                 mapping = file->f_mapping;
556                 if (!(vma->vm_flags & VM_NONLINEAR))
557                         root = &mapping->i_mmap;
558                 mutex_lock(&mapping->i_mmap_mutex);
559                 if (insert) {
560                         /*
561                          * Put into prio_tree now, so instantiated pages
562                          * are visible to arm/parisc __flush_dcache_page
563                          * throughout; but we cannot insert into address
564                          * space until vma start or end is updated.
565                          */
566                         __vma_link_file(insert);
567                 }
568         }
569
570         vma_adjust_trans_huge(vma, start, end, adjust_next);
571
572         /*
573          * When changing only vma->vm_end, we don't really need anon_vma
574          * lock. This is a fairly rare case by itself, but the anon_vma
575          * lock may be shared between many sibling processes.  Skipping
576          * the lock for brk adjustments makes a difference sometimes.
577          */
578         if (vma->anon_vma && (importer || start != vma->vm_start)) {
579                 anon_vma = vma->anon_vma;
580                 anon_vma_lock(anon_vma);
581         }
582
583         if (root) {
584                 flush_dcache_mmap_lock(mapping);
585                 vma_prio_tree_remove(vma, root);
586                 if (adjust_next)
587                         vma_prio_tree_remove(next, root);
588         }
589
590         vma->vm_start = start;
591         vma->vm_end = end;
592         vma->vm_pgoff = pgoff;
593         if (adjust_next) {
594                 next->vm_start += adjust_next << PAGE_SHIFT;
595                 next->vm_pgoff += adjust_next;
596         }
597
598         if (root) {
599                 if (adjust_next)
600                         vma_prio_tree_insert(next, root);
601                 vma_prio_tree_insert(vma, root);
602                 flush_dcache_mmap_unlock(mapping);
603         }
604
605         if (remove_next) {
606                 /*
607                  * vma_merge has merged next into vma, and needs
608                  * us to remove next before dropping the locks.
609                  */
610                 __vma_unlink(mm, next, vma);
611                 if (file)
612                         __remove_shared_vm_struct(next, file, mapping);
613         } else if (insert) {
614                 /*
615                  * split_vma has split insert from vma, and needs
616                  * us to insert it before dropping the locks
617                  * (it may either follow vma or precede it).
618                  */
619                 __insert_vm_struct(mm, insert);
620         }
621
622         if (anon_vma)
623                 anon_vma_unlock(anon_vma);
624         if (mapping)
625                 mutex_unlock(&mapping->i_mmap_mutex);
626
627         if (remove_next) {
628                 if (file) {
629                         fput(file);
630                         if (next->vm_flags & VM_EXECUTABLE)
631                                 removed_exe_file_vma(mm);
632                 }
633                 if (next->anon_vma)
634                         anon_vma_merge(vma, next);
635                 mm->map_count--;
636                 mpol_put(vma_policy(next));
637                 kmem_cache_free(vm_area_cachep, next);
638                 /*
639                  * In mprotect's case 6 (see comments on vma_merge),
640                  * we must remove another next too. It would clutter
641                  * up the code too much to do both in one go.
642                  */
643                 if (remove_next == 2) {
644                         next = vma->vm_next;
645                         goto again;
646                 }
647         }
648
649         validate_mm(mm);
650
651         return 0;
652 }
653
654 /*
655  * If the vma has a ->close operation then the driver probably needs to release
656  * per-vma resources, so we don't attempt to merge those.
657  */
658 static inline int is_mergeable_vma(struct vm_area_struct *vma,
659                         struct file *file, unsigned long vm_flags)
660 {
661         /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
662         if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
663                 return 0;
664         if (vma->vm_file != file)
665                 return 0;
666         if (vma->vm_ops && vma->vm_ops->close)
667                 return 0;
668         return 1;
669 }
670
671 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
672                                         struct anon_vma *anon_vma2,
673                                         struct vm_area_struct *vma)
674 {
675         /*
676          * The list_is_singular() test is to avoid merging VMA cloned from
677          * parents. This can improve scalability caused by anon_vma lock.
678          */
679         if ((!anon_vma1 || !anon_vma2) && (!vma ||
680                 list_is_singular(&vma->anon_vma_chain)))
681                 return 1;
682         return 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, 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, 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, NULL)) {
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                 khugepaged_enter_vma_merge(prev);
808                 return prev;
809         }
810
811         /*
812          * Can this new request be merged in front of next?
813          */
814         if (next && end == next->vm_start &&
815                         mpol_equal(policy, vma_policy(next)) &&
816                         can_vma_merge_before(next, vm_flags,
817                                         anon_vma, file, pgoff+pglen)) {
818                 if (prev && addr < prev->vm_end)        /* case 4 */
819                         err = vma_adjust(prev, prev->vm_start,
820                                 addr, prev->vm_pgoff, NULL);
821                 else                                    /* cases 3, 8 */
822                         err = vma_adjust(area, addr, next->vm_end,
823                                 next->vm_pgoff - pglen, NULL);
824                 if (err)
825                         return NULL;
826                 khugepaged_enter_vma_merge(area);
827                 return area;
828         }
829
830         return NULL;
831 }
832
833 /*
834  * Rough compatbility check to quickly see if it's even worth looking
835  * at sharing an anon_vma.
836  *
837  * They need to have the same vm_file, and the flags can only differ
838  * in things that mprotect may change.
839  *
840  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
841  * we can merge the two vma's. For example, we refuse to merge a vma if
842  * there is a vm_ops->close() function, because that indicates that the
843  * driver is doing some kind of reference counting. But that doesn't
844  * really matter for the anon_vma sharing case.
845  */
846 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
847 {
848         return a->vm_end == b->vm_start &&
849                 mpol_equal(vma_policy(a), vma_policy(b)) &&
850                 a->vm_file == b->vm_file &&
851                 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
852                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
853 }
854
855 /*
856  * Do some basic sanity checking to see if we can re-use the anon_vma
857  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
858  * the same as 'old', the other will be the new one that is trying
859  * to share the anon_vma.
860  *
861  * NOTE! This runs with mm_sem held for reading, so it is possible that
862  * the anon_vma of 'old' is concurrently in the process of being set up
863  * by another page fault trying to merge _that_. But that's ok: if it
864  * is being set up, that automatically means that it will be a singleton
865  * acceptable for merging, so we can do all of this optimistically. But
866  * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
867  *
868  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
869  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
870  * is to return an anon_vma that is "complex" due to having gone through
871  * a fork).
872  *
873  * We also make sure that the two vma's are compatible (adjacent,
874  * and with the same memory policies). That's all stable, even with just
875  * a read lock on the mm_sem.
876  */
877 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
878 {
879         if (anon_vma_compatible(a, b)) {
880                 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
881
882                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
883                         return anon_vma;
884         }
885         return NULL;
886 }
887
888 /*
889  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
890  * neighbouring vmas for a suitable anon_vma, before it goes off
891  * to allocate a new anon_vma.  It checks because a repetitive
892  * sequence of mprotects and faults may otherwise lead to distinct
893  * anon_vmas being allocated, preventing vma merge in subsequent
894  * mprotect.
895  */
896 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
897 {
898         struct anon_vma *anon_vma;
899         struct vm_area_struct *near;
900
901         near = vma->vm_next;
902         if (!near)
903                 goto try_prev;
904
905         anon_vma = reusable_anon_vma(near, vma, near);
906         if (anon_vma)
907                 return anon_vma;
908 try_prev:
909         near = vma->vm_prev;
910         if (!near)
911                 goto none;
912
913         anon_vma = reusable_anon_vma(near, near, vma);
914         if (anon_vma)
915                 return anon_vma;
916 none:
917         /*
918          * There's no absolute need to look only at touching neighbours:
919          * we could search further afield for "compatible" anon_vmas.
920          * But it would probably just be a waste of time searching,
921          * or lead to too many vmas hanging off the same anon_vma.
922          * We're trying to allow mprotect remerging later on,
923          * not trying to minimize memory used for anon_vmas.
924          */
925         return NULL;
926 }
927
928 #ifdef CONFIG_PROC_FS
929 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
930                                                 struct file *file, long pages)
931 {
932         const unsigned long stack_flags
933                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
934
935         if (file) {
936                 mm->shared_vm += pages;
937                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
938                         mm->exec_vm += pages;
939         } else if (flags & stack_flags)
940                 mm->stack_vm += pages;
941         if (flags & (VM_RESERVED|VM_IO))
942                 mm->reserved_vm += pages;
943 }
944 #endif /* CONFIG_PROC_FS */
945
946 /*
947  * The caller must hold down_write(&current->mm->mmap_sem).
948  */
949
950 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
951                         unsigned long len, unsigned long prot,
952                         unsigned long flags, unsigned long pgoff)
953 {
954         struct mm_struct * mm = current->mm;
955         struct inode *inode;
956         vm_flags_t vm_flags;
957         int error;
958         unsigned long reqprot = prot;
959
960         /*
961          * Does the application expect PROT_READ to imply PROT_EXEC?
962          *
963          * (the exception is when the underlying filesystem is noexec
964          *  mounted, in which case we dont add PROT_EXEC.)
965          */
966         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
967                 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
968                         prot |= PROT_EXEC;
969
970         if (!len)
971                 return -EINVAL;
972
973         if (!(flags & MAP_FIXED))
974                 addr = round_hint_to_min(addr);
975
976         /* Careful about overflows.. */
977         len = PAGE_ALIGN(len);
978         if (!len)
979                 return -ENOMEM;
980
981         /* offset overflow? */
982         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
983                return -EOVERFLOW;
984
985         /* Too many mappings? */
986         if (mm->map_count > sysctl_max_map_count)
987                 return -ENOMEM;
988
989         /* Obtain the address to map to. we verify (or select) it and ensure
990          * that it represents a valid section of the address space.
991          */
992         addr = get_unmapped_area(file, addr, len, pgoff, flags);
993         if (addr & ~PAGE_MASK)
994                 return addr;
995
996         /* Do simple checking here so the lower-level routines won't have
997          * to. we assume access permissions have been handled by the open
998          * of the memory object, so we don't do any here.
999          */
1000         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1001                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1002
1003         if (flags & MAP_LOCKED)
1004                 if (!can_do_mlock())
1005                         return -EPERM;
1006
1007         /* mlock MCL_FUTURE? */
1008         if (vm_flags & VM_LOCKED) {
1009                 unsigned long locked, lock_limit;
1010                 locked = len >> PAGE_SHIFT;
1011                 locked += mm->locked_vm;
1012                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1013                 lock_limit >>= PAGE_SHIFT;
1014                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1015                         return -EAGAIN;
1016         }
1017
1018         inode = file ? file->f_path.dentry->d_inode : NULL;
1019
1020         if (file) {
1021                 switch (flags & MAP_TYPE) {
1022                 case MAP_SHARED:
1023                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1024                                 return -EACCES;
1025
1026                         /*
1027                          * Make sure we don't allow writing to an append-only
1028                          * file..
1029                          */
1030                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1031                                 return -EACCES;
1032
1033                         /*
1034                          * Make sure there are no mandatory locks on the file.
1035                          */
1036                         if (locks_verify_locked(inode))
1037                                 return -EAGAIN;
1038
1039                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1040                         if (!(file->f_mode & FMODE_WRITE))
1041                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1042
1043                         /* fall through */
1044                 case MAP_PRIVATE:
1045                         if (!(file->f_mode & FMODE_READ))
1046                                 return -EACCES;
1047                         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1048                                 if (vm_flags & VM_EXEC)
1049                                         return -EPERM;
1050                                 vm_flags &= ~VM_MAYEXEC;
1051                         }
1052
1053                         if (!file->f_op || !file->f_op->mmap)
1054                                 return -ENODEV;
1055                         break;
1056
1057                 default:
1058                         return -EINVAL;
1059                 }
1060         } else {
1061                 switch (flags & MAP_TYPE) {
1062                 case MAP_SHARED:
1063                         /*
1064                          * Ignore pgoff.
1065                          */
1066                         pgoff = 0;
1067                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1068                         break;
1069                 case MAP_PRIVATE:
1070                         /*
1071                          * Set pgoff according to addr for anon_vma.
1072                          */
1073                         pgoff = addr >> PAGE_SHIFT;
1074                         break;
1075                 default:
1076                         return -EINVAL;
1077                 }
1078         }
1079
1080         error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1081         if (error)
1082                 return error;
1083
1084         return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1085 }
1086 EXPORT_SYMBOL(do_mmap_pgoff);
1087
1088 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1089                 unsigned long, prot, unsigned long, flags,
1090                 unsigned long, fd, unsigned long, pgoff)
1091 {
1092         struct file *file = NULL;
1093         unsigned long retval = -EBADF;
1094
1095         if (!(flags & MAP_ANONYMOUS)) {
1096                 audit_mmap_fd(fd, flags);
1097                 if (unlikely(flags & MAP_HUGETLB))
1098                         return -EINVAL;
1099                 file = fget(fd);
1100                 if (!file)
1101                         goto out;
1102         } else if (flags & MAP_HUGETLB) {
1103                 struct user_struct *user = NULL;
1104                 /*
1105                  * VM_NORESERVE is used because the reservations will be
1106                  * taken when vm_ops->mmap() is called
1107                  * A dummy user value is used because we are not locking
1108                  * memory so no accounting is necessary
1109                  */
1110                 len = ALIGN(len, huge_page_size(&default_hstate));
1111                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1112                                                 &user, HUGETLB_ANONHUGE_INODE);
1113                 if (IS_ERR(file))
1114                         return PTR_ERR(file);
1115         }
1116
1117         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1118
1119         down_write(&current->mm->mmap_sem);
1120         retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1121         up_write(&current->mm->mmap_sem);
1122
1123         if (file)
1124                 fput(file);
1125 out:
1126         return retval;
1127 }
1128
1129 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1130 struct mmap_arg_struct {
1131         unsigned long addr;
1132         unsigned long len;
1133         unsigned long prot;
1134         unsigned long flags;
1135         unsigned long fd;
1136         unsigned long offset;
1137 };
1138
1139 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1140 {
1141         struct mmap_arg_struct a;
1142
1143         if (copy_from_user(&a, arg, sizeof(a)))
1144                 return -EFAULT;
1145         if (a.offset & ~PAGE_MASK)
1146                 return -EINVAL;
1147
1148         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1149                               a.offset >> PAGE_SHIFT);
1150 }
1151 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1152
1153 /*
1154  * Some shared mappigns will want the pages marked read-only
1155  * to track write events. If so, we'll downgrade vm_page_prot
1156  * to the private version (using protection_map[] without the
1157  * VM_SHARED bit).
1158  */
1159 int vma_wants_writenotify(struct vm_area_struct *vma)
1160 {
1161         vm_flags_t vm_flags = vma->vm_flags;
1162
1163         /* If it was private or non-writable, the write bit is already clear */
1164         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1165                 return 0;
1166
1167         /* The backer wishes to know when pages are first written to? */
1168         if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1169                 return 1;
1170
1171         /* The open routine did something to the protections already? */
1172         if (pgprot_val(vma->vm_page_prot) !=
1173             pgprot_val(vm_get_page_prot(vm_flags)))
1174                 return 0;
1175
1176         /* Specialty mapping? */
1177         if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1178                 return 0;
1179
1180         /* Can the mapping track the dirty pages? */
1181         return vma->vm_file && vma->vm_file->f_mapping &&
1182                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1183 }
1184
1185 /*
1186  * We account for memory if it's a private writeable mapping,
1187  * not hugepages and VM_NORESERVE wasn't set.
1188  */
1189 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1190 {
1191         /*
1192          * hugetlb has its own accounting separate from the core VM
1193          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1194          */
1195         if (file && is_file_hugepages(file))
1196                 return 0;
1197
1198         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1199 }
1200
1201 unsigned long mmap_region(struct file *file, unsigned long addr,
1202                           unsigned long len, unsigned long flags,
1203                           vm_flags_t vm_flags, unsigned long pgoff)
1204 {
1205         struct mm_struct *mm = current->mm;
1206         struct vm_area_struct *vma, *prev;
1207         int correct_wcount = 0;
1208         int error;
1209         struct rb_node **rb_link, *rb_parent;
1210         unsigned long charged = 0;
1211         struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1212
1213         /* Clear old maps */
1214         error = -ENOMEM;
1215 munmap_back:
1216         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1217         if (vma && vma->vm_start < addr + len) {
1218                 if (do_munmap(mm, addr, len))
1219                         return -ENOMEM;
1220                 goto munmap_back;
1221         }
1222
1223         /* Check against address space limit. */
1224         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1225                 return -ENOMEM;
1226
1227         /*
1228          * Set 'VM_NORESERVE' if we should not account for the
1229          * memory use of this mapping.
1230          */
1231         if ((flags & MAP_NORESERVE)) {
1232                 /* We honor MAP_NORESERVE if allowed to overcommit */
1233                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1234                         vm_flags |= VM_NORESERVE;
1235
1236                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1237                 if (file && is_file_hugepages(file))
1238                         vm_flags |= VM_NORESERVE;
1239         }
1240
1241         /*
1242          * Private writable mapping: check memory availability
1243          */
1244         if (accountable_mapping(file, vm_flags)) {
1245                 charged = len >> PAGE_SHIFT;
1246                 if (security_vm_enough_memory(charged))
1247                         return -ENOMEM;
1248                 vm_flags |= VM_ACCOUNT;
1249         }
1250
1251         /*
1252          * Can we just expand an old mapping?
1253          */
1254         vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1255         if (vma)
1256                 goto out;
1257
1258         /*
1259          * Determine the object being mapped and call the appropriate
1260          * specific mapper. the address has already been validated, but
1261          * not unmapped, but the maps are removed from the list.
1262          */
1263         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1264         if (!vma) {
1265                 error = -ENOMEM;
1266                 goto unacct_error;
1267         }
1268
1269         vma->vm_mm = mm;
1270         vma->vm_start = addr;
1271         vma->vm_end = addr + len;
1272         vma->vm_flags = vm_flags;
1273         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1274         vma->vm_pgoff = pgoff;
1275         INIT_LIST_HEAD(&vma->anon_vma_chain);
1276
1277         if (file) {
1278                 error = -EINVAL;
1279                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1280                         goto free_vma;
1281                 if (vm_flags & VM_DENYWRITE) {
1282                         error = deny_write_access(file);
1283                         if (error)
1284                                 goto free_vma;
1285                         correct_wcount = 1;
1286                 }
1287                 vma->vm_file = file;
1288                 get_file(file);
1289                 error = file->f_op->mmap(file, vma);
1290                 if (error)
1291                         goto unmap_and_free_vma;
1292                 if (vm_flags & VM_EXECUTABLE)
1293                         added_exe_file_vma(mm);
1294
1295                 /* Can addr have changed??
1296                  *
1297                  * Answer: Yes, several device drivers can do it in their
1298                  *         f_op->mmap method. -DaveM
1299                  */
1300                 addr = vma->vm_start;
1301                 pgoff = vma->vm_pgoff;
1302                 vm_flags = vma->vm_flags;
1303         } else if (vm_flags & VM_SHARED) {
1304                 error = shmem_zero_setup(vma);
1305                 if (error)
1306                         goto free_vma;
1307         }
1308
1309         if (vma_wants_writenotify(vma)) {
1310                 pgprot_t pprot = vma->vm_page_prot;
1311
1312                 /* Can vma->vm_page_prot have changed??
1313                  *
1314                  * Answer: Yes, drivers may have changed it in their
1315                  *         f_op->mmap method.
1316                  *
1317                  * Ensures that vmas marked as uncached stay that way.
1318                  */
1319                 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1320                 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1321                         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1322         }
1323
1324         vma_link(mm, vma, prev, rb_link, rb_parent);
1325         file = vma->vm_file;
1326
1327         /* Once vma denies write, undo our temporary denial count */
1328         if (correct_wcount)
1329                 atomic_inc(&inode->i_writecount);
1330 out:
1331         perf_event_mmap(vma);
1332
1333         mm->total_vm += len >> PAGE_SHIFT;
1334         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1335         if (vm_flags & VM_LOCKED) {
1336                 if (!mlock_vma_pages_range(vma, addr, addr + len))
1337                         mm->locked_vm += (len >> PAGE_SHIFT);
1338         } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1339                 make_pages_present(addr, addr + len);
1340         return addr;
1341
1342 unmap_and_free_vma:
1343         if (correct_wcount)
1344                 atomic_inc(&inode->i_writecount);
1345         vma->vm_file = NULL;
1346         fput(file);
1347
1348         /* Undo any partial mapping done by a device driver. */
1349         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1350         charged = 0;
1351 free_vma:
1352         kmem_cache_free(vm_area_cachep, vma);
1353 unacct_error:
1354         if (charged)
1355                 vm_unacct_memory(charged);
1356         return error;
1357 }
1358
1359 /* Get an address range which is currently unmapped.
1360  * For shmat() with addr=0.
1361  *
1362  * Ugly calling convention alert:
1363  * Return value with the low bits set means error value,
1364  * ie
1365  *      if (ret & ~PAGE_MASK)
1366  *              error = ret;
1367  *
1368  * This function "knows" that -ENOMEM has the bits set.
1369  */
1370 #ifndef HAVE_ARCH_UNMAPPED_AREA
1371 unsigned long
1372 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1373                 unsigned long len, unsigned long pgoff, unsigned long flags)
1374 {
1375         struct mm_struct *mm = current->mm;
1376         struct vm_area_struct *vma;
1377         unsigned long start_addr;
1378
1379         if (len > TASK_SIZE)
1380                 return -ENOMEM;
1381
1382         if (flags & MAP_FIXED)
1383                 return addr;
1384
1385         if (addr) {
1386                 addr = PAGE_ALIGN(addr);
1387                 vma = find_vma(mm, addr);
1388                 if (TASK_SIZE - len >= addr &&
1389                     (!vma || addr + len <= vma->vm_start))
1390                         return addr;
1391         }
1392         if (len > mm->cached_hole_size) {
1393                 start_addr = addr = mm->free_area_cache;
1394         } else {
1395                 start_addr = addr = TASK_UNMAPPED_BASE;
1396                 mm->cached_hole_size = 0;
1397         }
1398
1399 full_search:
1400         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1401                 /* At this point:  (!vma || addr < vma->vm_end). */
1402                 if (TASK_SIZE - len < addr) {
1403                         /*
1404                          * Start a new search - just in case we missed
1405                          * some holes.
1406                          */
1407                         if (start_addr != TASK_UNMAPPED_BASE) {
1408                                 addr = TASK_UNMAPPED_BASE;
1409                                 start_addr = addr;
1410                                 mm->cached_hole_size = 0;
1411                                 goto full_search;
1412                         }
1413                         return -ENOMEM;
1414                 }
1415                 if (!vma || addr + len <= vma->vm_start) {
1416                         /*
1417                          * Remember the place where we stopped the search:
1418                          */
1419                         mm->free_area_cache = addr + len;
1420                         return addr;
1421                 }
1422                 if (addr + mm->cached_hole_size < vma->vm_start)
1423                         mm->cached_hole_size = vma->vm_start - addr;
1424                 addr = vma->vm_end;
1425         }
1426 }
1427 #endif  
1428
1429 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1430 {
1431         /*
1432          * Is this a new hole at the lowest possible address?
1433          */
1434         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1435                 mm->free_area_cache = addr;
1436                 mm->cached_hole_size = ~0UL;
1437         }
1438 }
1439
1440 /*
1441  * This mmap-allocator allocates new areas top-down from below the
1442  * stack's low limit (the base):
1443  */
1444 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1445 unsigned long
1446 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1447                           const unsigned long len, const unsigned long pgoff,
1448                           const unsigned long flags)
1449 {
1450         struct vm_area_struct *vma;
1451         struct mm_struct *mm = current->mm;
1452         unsigned long addr = addr0;
1453
1454         /* requested length too big for entire address space */
1455         if (len > TASK_SIZE)
1456                 return -ENOMEM;
1457
1458         if (flags & MAP_FIXED)
1459                 return addr;
1460
1461         /* requesting a specific address */
1462         if (addr) {
1463                 addr = PAGE_ALIGN(addr);
1464                 vma = find_vma(mm, addr);
1465                 if (TASK_SIZE - len >= addr &&
1466                                 (!vma || addr + len <= vma->vm_start))
1467                         return addr;
1468         }
1469
1470         /* check if free_area_cache is useful for us */
1471         if (len <= mm->cached_hole_size) {
1472                 mm->cached_hole_size = 0;
1473                 mm->free_area_cache = mm->mmap_base;
1474         }
1475
1476         /* either no address requested or can't fit in requested address hole */
1477         addr = mm->free_area_cache;
1478
1479         /* make sure it can fit in the remaining address space */
1480         if (addr > len) {
1481                 vma = find_vma(mm, addr-len);
1482                 if (!vma || addr <= vma->vm_start)
1483                         /* remember the address as a hint for next time */
1484                         return (mm->free_area_cache = addr-len);
1485         }
1486
1487         if (mm->mmap_base < len)
1488                 goto bottomup;
1489
1490         addr = mm->mmap_base-len;
1491
1492         do {
1493                 /*
1494                  * Lookup failure means no vma is above this address,
1495                  * else if new region fits below vma->vm_start,
1496                  * return with success:
1497                  */
1498                 vma = find_vma(mm, addr);
1499                 if (!vma || addr+len <= vma->vm_start)
1500                         /* remember the address as a hint for next time */
1501                         return (mm->free_area_cache = addr);
1502
1503                 /* remember the largest hole we saw so far */
1504                 if (addr + mm->cached_hole_size < vma->vm_start)
1505                         mm->cached_hole_size = vma->vm_start - addr;
1506
1507                 /* try just below the current vma->vm_start */
1508                 addr = vma->vm_start-len;
1509         } while (len < vma->vm_start);
1510
1511 bottomup:
1512         /*
1513          * A failed mmap() very likely causes application failure,
1514          * so fall back to the bottom-up function here. This scenario
1515          * can happen with large stack limits and large mmap()
1516          * allocations.
1517          */
1518         mm->cached_hole_size = ~0UL;
1519         mm->free_area_cache = TASK_UNMAPPED_BASE;
1520         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1521         /*
1522          * Restore the topdown base:
1523          */
1524         mm->free_area_cache = mm->mmap_base;
1525         mm->cached_hole_size = ~0UL;
1526
1527         return addr;
1528 }
1529 #endif
1530
1531 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1532 {
1533         /*
1534          * Is this a new hole at the highest possible address?
1535          */
1536         if (addr > mm->free_area_cache)
1537                 mm->free_area_cache = addr;
1538
1539         /* dont allow allocations above current base */
1540         if (mm->free_area_cache > mm->mmap_base)
1541                 mm->free_area_cache = mm->mmap_base;
1542 }
1543
1544 unsigned long
1545 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1546                 unsigned long pgoff, unsigned long flags)
1547 {
1548         unsigned long (*get_area)(struct file *, unsigned long,
1549                                   unsigned long, unsigned long, unsigned long);
1550
1551         unsigned long error = arch_mmap_check(addr, len, flags);
1552         if (error)
1553                 return error;
1554
1555         /* Careful about overflows.. */
1556         if (len > TASK_SIZE)
1557                 return -ENOMEM;
1558
1559         get_area = current->mm->get_unmapped_area;
1560         if (file && file->f_op && file->f_op->get_unmapped_area)
1561                 get_area = file->f_op->get_unmapped_area;
1562         addr = get_area(file, addr, len, pgoff, flags);
1563         if (IS_ERR_VALUE(addr))
1564                 return addr;
1565
1566         if (addr > TASK_SIZE - len)
1567                 return -ENOMEM;
1568         if (addr & ~PAGE_MASK)
1569                 return -EINVAL;
1570
1571         return arch_rebalance_pgtables(addr, len);
1572 }
1573
1574 EXPORT_SYMBOL(get_unmapped_area);
1575
1576 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1577 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1578 {
1579         struct vm_area_struct *vma = NULL;
1580
1581         if (mm) {
1582                 /* Check the cache first. */
1583                 /* (Cache hit rate is typically around 35%.) */
1584                 vma = mm->mmap_cache;
1585                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1586                         struct rb_node * rb_node;
1587
1588                         rb_node = mm->mm_rb.rb_node;
1589                         vma = NULL;
1590
1591                         while (rb_node) {
1592                                 struct vm_area_struct * vma_tmp;
1593
1594                                 vma_tmp = rb_entry(rb_node,
1595                                                 struct vm_area_struct, vm_rb);
1596
1597                                 if (vma_tmp->vm_end > addr) {
1598                                         vma = vma_tmp;
1599                                         if (vma_tmp->vm_start <= addr)
1600                                                 break;
1601                                         rb_node = rb_node->rb_left;
1602                                 } else
1603                                         rb_node = rb_node->rb_right;
1604                         }
1605                         if (vma)
1606                                 mm->mmap_cache = vma;
1607                 }
1608         }
1609         return vma;
1610 }
1611
1612 EXPORT_SYMBOL(find_vma);
1613
1614 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1615 struct vm_area_struct *
1616 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1617                         struct vm_area_struct **pprev)
1618 {
1619         struct vm_area_struct *vma = NULL, *prev = NULL;
1620         struct rb_node *rb_node;
1621         if (!mm)
1622                 goto out;
1623
1624         /* Guard against addr being lower than the first VMA */
1625         vma = mm->mmap;
1626
1627         /* Go through the RB tree quickly. */
1628         rb_node = mm->mm_rb.rb_node;
1629
1630         while (rb_node) {
1631                 struct vm_area_struct *vma_tmp;
1632                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1633
1634                 if (addr < vma_tmp->vm_end) {
1635                         rb_node = rb_node->rb_left;
1636                 } else {
1637                         prev = vma_tmp;
1638                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1639                                 break;
1640                         rb_node = rb_node->rb_right;
1641                 }
1642         }
1643
1644 out:
1645         *pprev = prev;
1646         return prev ? prev->vm_next : vma;
1647 }
1648
1649 /*
1650  * Verify that the stack growth is acceptable and
1651  * update accounting. This is shared with both the
1652  * grow-up and grow-down cases.
1653  */
1654 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1655 {
1656         struct mm_struct *mm = vma->vm_mm;
1657         struct rlimit *rlim = current->signal->rlim;
1658         unsigned long new_start;
1659
1660         /* address space limit tests */
1661         if (!may_expand_vm(mm, grow))
1662                 return -ENOMEM;
1663
1664         /* Stack limit test */
1665         if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1666                 return -ENOMEM;
1667
1668         /* mlock limit tests */
1669         if (vma->vm_flags & VM_LOCKED) {
1670                 unsigned long locked;
1671                 unsigned long limit;
1672                 locked = mm->locked_vm + grow;
1673                 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1674                 limit >>= PAGE_SHIFT;
1675                 if (locked > limit && !capable(CAP_IPC_LOCK))
1676                         return -ENOMEM;
1677         }
1678
1679         /* Check to ensure the stack will not grow into a hugetlb-only region */
1680         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1681                         vma->vm_end - size;
1682         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1683                 return -EFAULT;
1684
1685         /*
1686          * Overcommit..  This must be the final test, as it will
1687          * update security statistics.
1688          */
1689         if (security_vm_enough_memory_mm(mm, grow))
1690                 return -ENOMEM;
1691
1692         /* Ok, everything looks good - let it rip */
1693         mm->total_vm += grow;
1694         if (vma->vm_flags & VM_LOCKED)
1695                 mm->locked_vm += grow;
1696         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1697         return 0;
1698 }
1699
1700 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1701 /*
1702  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1703  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1704  */
1705 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1706 {
1707         int error;
1708
1709         if (!(vma->vm_flags & VM_GROWSUP))
1710                 return -EFAULT;
1711
1712         /*
1713          * We must make sure the anon_vma is allocated
1714          * so that the anon_vma locking is not a noop.
1715          */
1716         if (unlikely(anon_vma_prepare(vma)))
1717                 return -ENOMEM;
1718         vma_lock_anon_vma(vma);
1719
1720         /*
1721          * vma->vm_start/vm_end cannot change under us because the caller
1722          * is required to hold the mmap_sem in read mode.  We need the
1723          * anon_vma lock to serialize against concurrent expand_stacks.
1724          * Also guard against wrapping around to address 0.
1725          */
1726         if (address < PAGE_ALIGN(address+4))
1727                 address = PAGE_ALIGN(address+4);
1728         else {
1729                 vma_unlock_anon_vma(vma);
1730                 return -ENOMEM;
1731         }
1732         error = 0;
1733
1734         /* Somebody else might have raced and expanded it already */
1735         if (address > vma->vm_end) {
1736                 unsigned long size, grow;
1737
1738                 size = address - vma->vm_start;
1739                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1740
1741                 error = -ENOMEM;
1742                 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1743                         error = acct_stack_growth(vma, size, grow);
1744                         if (!error) {
1745                                 vma->vm_end = address;
1746                                 perf_event_mmap(vma);
1747                         }
1748                 }
1749         }
1750         vma_unlock_anon_vma(vma);
1751         khugepaged_enter_vma_merge(vma);
1752         return error;
1753 }
1754 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1755
1756 /*
1757  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1758  */
1759 int expand_downwards(struct vm_area_struct *vma,
1760                                    unsigned long address)
1761 {
1762         int error;
1763
1764         /*
1765          * We must make sure the anon_vma is allocated
1766          * so that the anon_vma locking is not a noop.
1767          */
1768         if (unlikely(anon_vma_prepare(vma)))
1769                 return -ENOMEM;
1770
1771         address &= PAGE_MASK;
1772         error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1773         if (error)
1774                 return error;
1775
1776         vma_lock_anon_vma(vma);
1777
1778         /*
1779          * vma->vm_start/vm_end cannot change under us because the caller
1780          * is required to hold the mmap_sem in read mode.  We need the
1781          * anon_vma lock to serialize against concurrent expand_stacks.
1782          */
1783
1784         /* Somebody else might have raced and expanded it already */
1785         if (address < vma->vm_start) {
1786                 unsigned long size, grow;
1787
1788                 size = vma->vm_end - address;
1789                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1790
1791                 error = -ENOMEM;
1792                 if (grow <= vma->vm_pgoff) {
1793                         error = acct_stack_growth(vma, size, grow);
1794                         if (!error) {
1795                                 vma->vm_start = address;
1796                                 vma->vm_pgoff -= grow;
1797                                 perf_event_mmap(vma);
1798                         }
1799                 }
1800         }
1801         vma_unlock_anon_vma(vma);
1802         khugepaged_enter_vma_merge(vma);
1803         return error;
1804 }
1805
1806 #ifdef CONFIG_STACK_GROWSUP
1807 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1808 {
1809         return expand_upwards(vma, address);
1810 }
1811
1812 struct vm_area_struct *
1813 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1814 {
1815         struct vm_area_struct *vma, *prev;
1816
1817         addr &= PAGE_MASK;
1818         vma = find_vma_prev(mm, addr, &prev);
1819         if (vma && (vma->vm_start <= addr))
1820                 return vma;
1821         if (!prev || expand_stack(prev, addr))
1822                 return NULL;
1823         if (prev->vm_flags & VM_LOCKED) {
1824                 mlock_vma_pages_range(prev, addr, prev->vm_end);
1825         }
1826         return prev;
1827 }
1828 #else
1829 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1830 {
1831         return expand_downwards(vma, address);
1832 }
1833
1834 struct vm_area_struct *
1835 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1836 {
1837         struct vm_area_struct * vma;
1838         unsigned long start;
1839
1840         addr &= PAGE_MASK;
1841         vma = find_vma(mm,addr);
1842         if (!vma)
1843                 return NULL;
1844         if (vma->vm_start <= addr)
1845                 return vma;
1846         if (!(vma->vm_flags & VM_GROWSDOWN))
1847                 return NULL;
1848         start = vma->vm_start;
1849         if (expand_stack(vma, addr))
1850                 return NULL;
1851         if (vma->vm_flags & VM_LOCKED) {
1852                 mlock_vma_pages_range(vma, addr, start);
1853         }
1854         return vma;
1855 }
1856 #endif
1857
1858 /*
1859  * Ok - we have the memory areas we should free on the vma list,
1860  * so release them, and do the vma updates.
1861  *
1862  * Called with the mm semaphore held.
1863  */
1864 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1865 {
1866         /* Update high watermark before we lower total_vm */
1867         update_hiwater_vm(mm);
1868         do {
1869                 long nrpages = vma_pages(vma);
1870
1871                 mm->total_vm -= nrpages;
1872                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1873                 vma = remove_vma(vma);
1874         } while (vma);
1875         validate_mm(mm);
1876 }
1877
1878 /*
1879  * Get rid of page table information in the indicated region.
1880  *
1881  * Called with the mm semaphore held.
1882  */
1883 static void unmap_region(struct mm_struct *mm,
1884                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1885                 unsigned long start, unsigned long end)
1886 {
1887         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1888         struct mmu_gather tlb;
1889         unsigned long nr_accounted = 0;
1890
1891         lru_add_drain();
1892         tlb_gather_mmu(&tlb, mm, 0);
1893         update_hiwater_rss(mm);
1894         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1895         vm_unacct_memory(nr_accounted);
1896         free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
1897                                  next ? next->vm_start : 0);
1898         tlb_finish_mmu(&tlb, start, end);
1899 }
1900
1901 /*
1902  * Create a list of vma's touched by the unmap, removing them from the mm's
1903  * vma list as we go..
1904  */
1905 static void
1906 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1907         struct vm_area_struct *prev, unsigned long end)
1908 {
1909         struct vm_area_struct **insertion_point;
1910         struct vm_area_struct *tail_vma = NULL;
1911         unsigned long addr;
1912
1913         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1914         vma->vm_prev = NULL;
1915         do {
1916                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1917                 mm->map_count--;
1918                 tail_vma = vma;
1919                 vma = vma->vm_next;
1920         } while (vma && vma->vm_start < end);
1921         *insertion_point = vma;
1922         if (vma)
1923                 vma->vm_prev = prev;
1924         tail_vma->vm_next = NULL;
1925         if (mm->unmap_area == arch_unmap_area)
1926                 addr = prev ? prev->vm_end : mm->mmap_base;
1927         else
1928                 addr = vma ?  vma->vm_start : mm->mmap_base;
1929         mm->unmap_area(mm, addr);
1930         mm->mmap_cache = NULL;          /* Kill the cache. */
1931 }
1932
1933 /*
1934  * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1935  * munmap path where it doesn't make sense to fail.
1936  */
1937 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1938               unsigned long addr, int new_below)
1939 {
1940         struct mempolicy *pol;
1941         struct vm_area_struct *new;
1942         int err = -ENOMEM;
1943
1944         if (is_vm_hugetlb_page(vma) && (addr &
1945                                         ~(huge_page_mask(hstate_vma(vma)))))
1946                 return -EINVAL;
1947
1948         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1949         if (!new)
1950                 goto out_err;
1951
1952         /* most fields are the same, copy all, and then fixup */
1953         *new = *vma;
1954
1955         INIT_LIST_HEAD(&new->anon_vma_chain);
1956
1957         if (new_below)
1958                 new->vm_end = addr;
1959         else {
1960                 new->vm_start = addr;
1961                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1962         }
1963
1964         pol = mpol_dup(vma_policy(vma));
1965         if (IS_ERR(pol)) {
1966                 err = PTR_ERR(pol);
1967                 goto out_free_vma;
1968         }
1969         vma_set_policy(new, pol);
1970
1971         if (anon_vma_clone(new, vma))
1972                 goto out_free_mpol;
1973
1974         if (new->vm_file) {
1975                 get_file(new->vm_file);
1976                 if (vma->vm_flags & VM_EXECUTABLE)
1977                         added_exe_file_vma(mm);
1978         }
1979
1980         if (new->vm_ops && new->vm_ops->open)
1981                 new->vm_ops->open(new);
1982
1983         if (new_below)
1984                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1985                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1986         else
1987                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1988
1989         /* Success. */
1990         if (!err)
1991                 return 0;
1992
1993         /* Clean everything up if vma_adjust failed. */
1994         if (new->vm_ops && new->vm_ops->close)
1995                 new->vm_ops->close(new);
1996         if (new->vm_file) {
1997                 if (vma->vm_flags & VM_EXECUTABLE)
1998                         removed_exe_file_vma(mm);
1999                 fput(new->vm_file);
2000         }
2001         unlink_anon_vmas(new);
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(mm, start);
2041         if (!vma)
2042                 return 0;
2043         prev = vma->vm_prev;
2044         /* we have  start < vma->vm_end  */
2045
2046         /* if it doesn't overlap, we have nothing.. */
2047         end = start + len;
2048         if (vma->vm_start >= end)
2049                 return 0;
2050
2051         /*
2052          * If we need to split any vma, do it now to save pain later.
2053          *
2054          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2055          * unmapped vm_area_struct will remain in use: so lower split_vma
2056          * places tmp vma above, and higher split_vma places tmp vma below.
2057          */
2058         if (start > vma->vm_start) {
2059                 int error;
2060
2061                 /*
2062                  * Make sure that map_count on return from munmap() will
2063                  * not exceed its limit; but let map_count go just above
2064                  * its limit temporarily, to help free resources as expected.
2065                  */
2066                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2067                         return -ENOMEM;
2068
2069                 error = __split_vma(mm, vma, start, 0);
2070                 if (error)
2071                         return error;
2072                 prev = vma;
2073         }
2074
2075         /* Does it split the last one? */
2076         last = find_vma(mm, end);
2077         if (last && end > last->vm_start) {
2078                 int error = __split_vma(mm, last, end, 1);
2079                 if (error)
2080                         return error;
2081         }
2082         vma = prev? prev->vm_next: mm->mmap;
2083
2084         /*
2085          * unlock any mlock()ed ranges before detaching vmas
2086          */
2087         if (mm->locked_vm) {
2088                 struct vm_area_struct *tmp = vma;
2089                 while (tmp && tmp->vm_start < end) {
2090                         if (tmp->vm_flags & VM_LOCKED) {
2091                                 mm->locked_vm -= vma_pages(tmp);
2092                                 munlock_vma_pages_all(tmp);
2093                         }
2094                         tmp = tmp->vm_next;
2095                 }
2096         }
2097
2098         /*
2099          * Remove the vma's, and unmap the actual pages
2100          */
2101         detach_vmas_to_be_unmapped(mm, vma, prev, end);
2102         unmap_region(mm, vma, prev, start, end);
2103
2104         /* Fix up all other VM information */
2105         remove_vma_list(mm, vma);
2106
2107         return 0;
2108 }
2109
2110 EXPORT_SYMBOL(do_munmap);
2111
2112 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2113 {
2114         int ret;
2115         struct mm_struct *mm = current->mm;
2116
2117         profile_munmap(addr);
2118
2119         down_write(&mm->mmap_sem);
2120         ret = do_munmap(mm, addr, len);
2121         up_write(&mm->mmap_sem);
2122         return ret;
2123 }
2124
2125 static inline void verify_mm_writelocked(struct mm_struct *mm)
2126 {
2127 #ifdef CONFIG_DEBUG_VM
2128         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2129                 WARN_ON(1);
2130                 up_read(&mm->mmap_sem);
2131         }
2132 #endif
2133 }
2134
2135 /*
2136  *  this is really a simplified "do_mmap".  it only handles
2137  *  anonymous maps.  eventually we may be able to do some
2138  *  brk-specific accounting here.
2139  */
2140 unsigned long do_brk(unsigned long addr, unsigned long len)
2141 {
2142         struct mm_struct * mm = current->mm;
2143         struct vm_area_struct * vma, * prev;
2144         unsigned long flags;
2145         struct rb_node ** rb_link, * rb_parent;
2146         pgoff_t pgoff = addr >> PAGE_SHIFT;
2147         int error;
2148
2149         len = PAGE_ALIGN(len);
2150         if (!len)
2151                 return addr;
2152
2153         error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2154         if (error)
2155                 return error;
2156
2157         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2158
2159         error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2160         if (error & ~PAGE_MASK)
2161                 return error;
2162
2163         /*
2164          * mlock MCL_FUTURE?
2165          */
2166         if (mm->def_flags & VM_LOCKED) {
2167                 unsigned long locked, lock_limit;
2168                 locked = len >> PAGE_SHIFT;
2169                 locked += mm->locked_vm;
2170                 lock_limit = rlimit(RLIMIT_MEMLOCK);
2171                 lock_limit >>= PAGE_SHIFT;
2172                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2173                         return -EAGAIN;
2174         }
2175
2176         /*
2177          * mm->mmap_sem is required to protect against another thread
2178          * changing the mappings in case we sleep.
2179          */
2180         verify_mm_writelocked(mm);
2181
2182         /*
2183          * Clear old maps.  this also does some error checking for us
2184          */
2185  munmap_back:
2186         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2187         if (vma && vma->vm_start < addr + len) {
2188                 if (do_munmap(mm, addr, len))
2189                         return -ENOMEM;
2190                 goto munmap_back;
2191         }
2192
2193         /* Check against address space limits *after* clearing old maps... */
2194         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2195                 return -ENOMEM;
2196
2197         if (mm->map_count > sysctl_max_map_count)
2198                 return -ENOMEM;
2199
2200         if (security_vm_enough_memory(len >> PAGE_SHIFT))
2201                 return -ENOMEM;
2202
2203         /* Can we just expand an old private anonymous mapping? */
2204         vma = vma_merge(mm, prev, addr, addr + len, flags,
2205                                         NULL, NULL, pgoff, NULL);
2206         if (vma)
2207                 goto out;
2208
2209         /*
2210          * create a vma struct for an anonymous mapping
2211          */
2212         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2213         if (!vma) {
2214                 vm_unacct_memory(len >> PAGE_SHIFT);
2215                 return -ENOMEM;
2216         }
2217
2218         INIT_LIST_HEAD(&vma->anon_vma_chain);
2219         vma->vm_mm = mm;
2220         vma->vm_start = addr;
2221         vma->vm_end = addr + len;
2222         vma->vm_pgoff = pgoff;
2223         vma->vm_flags = flags;
2224         vma->vm_page_prot = vm_get_page_prot(flags);
2225         vma_link(mm, vma, prev, rb_link, rb_parent);
2226 out:
2227         perf_event_mmap(vma);
2228         mm->total_vm += len >> PAGE_SHIFT;
2229         if (flags & VM_LOCKED) {
2230                 if (!mlock_vma_pages_range(vma, addr, addr + len))
2231                         mm->locked_vm += (len >> PAGE_SHIFT);
2232         }
2233         return addr;
2234 }
2235
2236 EXPORT_SYMBOL(do_brk);
2237
2238 /* Release all mmaps. */
2239 void exit_mmap(struct mm_struct *mm)
2240 {
2241         struct mmu_gather tlb;
2242         struct vm_area_struct *vma;
2243         unsigned long nr_accounted = 0;
2244         unsigned long end;
2245
2246         /* mm's last user has gone, and its about to be pulled down */
2247         mmu_notifier_release(mm);
2248
2249         if (mm->locked_vm) {
2250                 vma = mm->mmap;
2251                 while (vma) {
2252                         if (vma->vm_flags & VM_LOCKED)
2253                                 munlock_vma_pages_all(vma);
2254                         vma = vma->vm_next;
2255                 }
2256         }
2257
2258         arch_exit_mmap(mm);
2259
2260         vma = mm->mmap;
2261         if (!vma)       /* Can happen if dup_mmap() received an OOM */
2262                 return;
2263
2264         lru_add_drain();
2265         flush_cache_mm(mm);
2266         tlb_gather_mmu(&tlb, mm, 1);
2267         /* update_hiwater_rss(mm) here? but nobody should be looking */
2268         /* Use -1 here to ensure all VMAs in the mm are unmapped */
2269         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2270         vm_unacct_memory(nr_accounted);
2271
2272         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2273         tlb_finish_mmu(&tlb, 0, end);
2274
2275         /*
2276          * Walk the list again, actually closing and freeing it,
2277          * with preemption enabled, without holding any MM locks.
2278          */
2279         while (vma)
2280                 vma = remove_vma(vma);
2281
2282         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2283 }
2284
2285 /* Insert vm structure into process list sorted by address
2286  * and into the inode's i_mmap tree.  If vm_file is non-NULL
2287  * then i_mmap_mutex is taken here.
2288  */
2289 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2290 {
2291         struct vm_area_struct * __vma, * prev;
2292         struct rb_node ** rb_link, * rb_parent;
2293
2294         /*
2295          * The vm_pgoff of a purely anonymous vma should be irrelevant
2296          * until its first write fault, when page's anon_vma and index
2297          * are set.  But now set the vm_pgoff it will almost certainly
2298          * end up with (unless mremap moves it elsewhere before that
2299          * first wfault), so /proc/pid/maps tells a consistent story.
2300          *
2301          * By setting it to reflect the virtual start address of the
2302          * vma, merges and splits can happen in a seamless way, just
2303          * using the existing file pgoff checks and manipulations.
2304          * Similarly in do_mmap_pgoff and in do_brk.
2305          */
2306         if (!vma->vm_file) {
2307                 BUG_ON(vma->anon_vma);
2308                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2309         }
2310         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2311         if (__vma && __vma->vm_start < vma->vm_end)
2312                 return -ENOMEM;
2313         if ((vma->vm_flags & VM_ACCOUNT) &&
2314              security_vm_enough_memory_mm(mm, vma_pages(vma)))
2315                 return -ENOMEM;
2316         vma_link(mm, vma, prev, rb_link, rb_parent);
2317         return 0;
2318 }
2319
2320 /*
2321  * Copy the vma structure to a new location in the same mm,
2322  * prior to moving page table entries, to effect an mremap move.
2323  */
2324 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2325         unsigned long addr, unsigned long len, pgoff_t pgoff)
2326 {
2327         struct vm_area_struct *vma = *vmap;
2328         unsigned long vma_start = vma->vm_start;
2329         struct mm_struct *mm = vma->vm_mm;
2330         struct vm_area_struct *new_vma, *prev;
2331         struct rb_node **rb_link, *rb_parent;
2332         struct mempolicy *pol;
2333
2334         /*
2335          * If anonymous vma has not yet been faulted, update new pgoff
2336          * to match new location, to increase its chance of merging.
2337          */
2338         if (!vma->vm_file && !vma->anon_vma)
2339                 pgoff = addr >> PAGE_SHIFT;
2340
2341         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2342         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2343                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2344         if (new_vma) {
2345                 /*
2346                  * Source vma may have been merged into new_vma
2347                  */
2348                 if (vma_start >= new_vma->vm_start &&
2349                     vma_start < new_vma->vm_end)
2350                         *vmap = new_vma;
2351         } else {
2352                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2353                 if (new_vma) {
2354                         *new_vma = *vma;
2355                         pol = mpol_dup(vma_policy(vma));
2356                         if (IS_ERR(pol))
2357                                 goto out_free_vma;
2358                         INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2359                         if (anon_vma_clone(new_vma, vma))
2360                                 goto out_free_mempol;
2361                         vma_set_policy(new_vma, pol);
2362                         new_vma->vm_start = addr;
2363                         new_vma->vm_end = addr + len;
2364                         new_vma->vm_pgoff = pgoff;
2365                         if (new_vma->vm_file) {
2366                                 get_file(new_vma->vm_file);
2367                                 if (vma->vm_flags & VM_EXECUTABLE)
2368                                         added_exe_file_vma(mm);
2369                         }
2370                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2371                                 new_vma->vm_ops->open(new_vma);
2372                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2373                 }
2374         }
2375         return new_vma;
2376
2377  out_free_mempol:
2378         mpol_put(pol);
2379  out_free_vma:
2380         kmem_cache_free(vm_area_cachep, new_vma);
2381         return NULL;
2382 }
2383
2384 /*
2385  * Return true if the calling process may expand its vm space by the passed
2386  * number of pages
2387  */
2388 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2389 {
2390         unsigned long cur = mm->total_vm;       /* pages */
2391         unsigned long lim;
2392
2393         lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2394
2395         if (cur + npages > lim)
2396                 return 0;
2397         return 1;
2398 }
2399
2400
2401 static int special_mapping_fault(struct vm_area_struct *vma,
2402                                 struct vm_fault *vmf)
2403 {
2404         pgoff_t pgoff;
2405         struct page **pages;
2406
2407         /*
2408          * special mappings have no vm_file, and in that case, the mm
2409          * uses vm_pgoff internally. So we have to subtract it from here.
2410          * We are allowed to do this because we are the mm; do not copy
2411          * this code into drivers!
2412          */
2413         pgoff = vmf->pgoff - vma->vm_pgoff;
2414
2415         for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2416                 pgoff--;
2417
2418         if (*pages) {
2419                 struct page *page = *pages;
2420                 get_page(page);
2421                 vmf->page = page;
2422                 return 0;
2423         }
2424
2425         return VM_FAULT_SIGBUS;
2426 }
2427
2428 /*
2429  * Having a close hook prevents vma merging regardless of flags.
2430  */
2431 static void special_mapping_close(struct vm_area_struct *vma)
2432 {
2433 }
2434
2435 static const struct vm_operations_struct special_mapping_vmops = {
2436         .close = special_mapping_close,
2437         .fault = special_mapping_fault,
2438 };
2439
2440 /*
2441  * Called with mm->mmap_sem held for writing.
2442  * Insert a new vma covering the given region, with the given flags.
2443  * Its pages are supplied by the given array of struct page *.
2444  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2445  * The region past the last page supplied will always produce SIGBUS.
2446  * The array pointer and the pages it points to are assumed to stay alive
2447  * for as long as this mapping might exist.
2448  */
2449 int install_special_mapping(struct mm_struct *mm,
2450                             unsigned long addr, unsigned long len,
2451                             unsigned long vm_flags, struct page **pages)
2452 {
2453         int ret;
2454         struct vm_area_struct *vma;
2455
2456         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2457         if (unlikely(vma == NULL))
2458                 return -ENOMEM;
2459
2460         INIT_LIST_HEAD(&vma->anon_vma_chain);
2461         vma->vm_mm = mm;
2462         vma->vm_start = addr;
2463         vma->vm_end = addr + len;
2464
2465         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2466         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2467
2468         vma->vm_ops = &special_mapping_vmops;
2469         vma->vm_private_data = pages;
2470
2471         ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2472         if (ret)
2473                 goto out;
2474
2475         ret = insert_vm_struct(mm, vma);
2476         if (ret)
2477                 goto out;
2478
2479         mm->total_vm += len >> PAGE_SHIFT;
2480
2481         perf_event_mmap(vma);
2482
2483         return 0;
2484
2485 out:
2486         kmem_cache_free(vm_area_cachep, vma);
2487         return ret;
2488 }
2489
2490 static DEFINE_MUTEX(mm_all_locks_mutex);
2491
2492 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2493 {
2494         if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2495                 /*
2496                  * The LSB of head.next can't change from under us
2497                  * because we hold the mm_all_locks_mutex.
2498                  */
2499                 mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
2500                 /*
2501                  * We can safely modify head.next after taking the
2502                  * anon_vma->root->mutex. If some other vma in this mm shares
2503                  * the same anon_vma we won't take it again.
2504                  *
2505                  * No need of atomic instructions here, head.next
2506                  * can't change from under us thanks to the
2507                  * anon_vma->root->mutex.
2508                  */
2509                 if (__test_and_set_bit(0, (unsigned long *)
2510                                        &anon_vma->root->head.next))
2511                         BUG();
2512         }
2513 }
2514
2515 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2516 {
2517         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2518                 /*
2519                  * AS_MM_ALL_LOCKS can't change from under us because
2520                  * we hold the mm_all_locks_mutex.
2521                  *
2522                  * Operations on ->flags have to be atomic because
2523                  * even if AS_MM_ALL_LOCKS is stable thanks to the
2524                  * mm_all_locks_mutex, there may be other cpus
2525                  * changing other bitflags in parallel to us.
2526                  */
2527                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2528                         BUG();
2529                 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2530         }
2531 }
2532
2533 /*
2534  * This operation locks against the VM for all pte/vma/mm related
2535  * operations that could ever happen on a certain mm. This includes
2536  * vmtruncate, try_to_unmap, and all page faults.
2537  *
2538  * The caller must take the mmap_sem in write mode before calling
2539  * mm_take_all_locks(). The caller isn't allowed to release the
2540  * mmap_sem until mm_drop_all_locks() returns.
2541  *
2542  * mmap_sem in write mode is required in order to block all operations
2543  * that could modify pagetables and free pages without need of
2544  * altering the vma layout (for example populate_range() with
2545  * nonlinear vmas). It's also needed in write mode to avoid new
2546  * anon_vmas to be associated with existing vmas.
2547  *
2548  * A single task can't take more than one mm_take_all_locks() in a row
2549  * or it would deadlock.
2550  *
2551  * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2552  * mapping->flags avoid to take the same lock twice, if more than one
2553  * vma in this mm is backed by the same anon_vma or address_space.
2554  *
2555  * We can take all the locks in random order because the VM code
2556  * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
2557  * takes more than one of them in a row. Secondly we're protected
2558  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2559  *
2560  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2561  * that may have to take thousand of locks.
2562  *
2563  * mm_take_all_locks() can fail if it's interrupted by signals.
2564  */
2565 int mm_take_all_locks(struct mm_struct *mm)
2566 {
2567         struct vm_area_struct *vma;
2568         struct anon_vma_chain *avc;
2569         int ret = -EINTR;
2570
2571         BUG_ON(down_read_trylock(&mm->mmap_sem));
2572
2573         mutex_lock(&mm_all_locks_mutex);
2574
2575         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2576                 if (signal_pending(current))
2577                         goto out_unlock;
2578                 if (vma->vm_file && vma->vm_file->f_mapping)
2579                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
2580         }
2581
2582         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2583                 if (signal_pending(current))
2584                         goto out_unlock;
2585                 if (vma->anon_vma)
2586                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2587                                 vm_lock_anon_vma(mm, avc->anon_vma);
2588         }
2589
2590         ret = 0;
2591
2592 out_unlock:
2593         if (ret)
2594                 mm_drop_all_locks(mm);
2595
2596         return ret;
2597 }
2598
2599 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2600 {
2601         if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2602                 /*
2603                  * The LSB of head.next can't change to 0 from under
2604                  * us because we hold the mm_all_locks_mutex.
2605                  *
2606                  * We must however clear the bitflag before unlocking
2607                  * the vma so the users using the anon_vma->head will
2608                  * never see our bitflag.
2609                  *
2610                  * No need of atomic instructions here, head.next
2611                  * can't change from under us until we release the
2612                  * anon_vma->root->mutex.
2613                  */
2614                 if (!__test_and_clear_bit(0, (unsigned long *)
2615                                           &anon_vma->root->head.next))
2616                         BUG();
2617                 anon_vma_unlock(anon_vma);
2618         }
2619 }
2620
2621 static void vm_unlock_mapping(struct address_space *mapping)
2622 {
2623         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2624                 /*
2625                  * AS_MM_ALL_LOCKS can't change to 0 from under us
2626                  * because we hold the mm_all_locks_mutex.
2627                  */
2628                 mutex_unlock(&mapping->i_mmap_mutex);
2629                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2630                                         &mapping->flags))
2631                         BUG();
2632         }
2633 }
2634
2635 /*
2636  * The mmap_sem cannot be released by the caller until
2637  * mm_drop_all_locks() returns.
2638  */
2639 void mm_drop_all_locks(struct mm_struct *mm)
2640 {
2641         struct vm_area_struct *vma;
2642         struct anon_vma_chain *avc;
2643
2644         BUG_ON(down_read_trylock(&mm->mmap_sem));
2645         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2646
2647         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2648                 if (vma->anon_vma)
2649                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2650                                 vm_unlock_anon_vma(avc->anon_vma);
2651                 if (vma->vm_file && vma->vm_file->f_mapping)
2652                         vm_unlock_mapping(vma->vm_file->f_mapping);
2653         }
2654
2655         mutex_unlock(&mm_all_locks_mutex);
2656 }
2657
2658 /*
2659  * initialise the VMA slab
2660  */
2661 void __init mmap_init(void)
2662 {
2663         int ret;
2664
2665         ret = percpu_counter_init(&vm_committed_as, 0);
2666         VM_BUG_ON(ret);
2667 }