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