[PATCH] mm: fix bug in brk()
[linux-2.6-block.git] / mm / mmap.c
1 /*
2  * mm/mmap.c
3  *
4  * Written by obz.
5  *
6  * Address space accounting code        <alan@redhat.com>
7  */
8
9 #include <linux/slab.h>
10 #include <linux/mm.h>
11 #include <linux/shm.h>
12 #include <linux/mman.h>
13 #include <linux/pagemap.h>
14 #include <linux/swap.h>
15 #include <linux/syscalls.h>
16 #include <linux/capability.h>
17 #include <linux/init.h>
18 #include <linux/file.h>
19 #include <linux/fs.h>
20 #include <linux/personality.h>
21 #include <linux/security.h>
22 #include <linux/hugetlb.h>
23 #include <linux/profile.h>
24 #include <linux/module.h>
25 #include <linux/mount.h>
26 #include <linux/mempolicy.h>
27 #include <linux/rmap.h>
28
29 #include <asm/uaccess.h>
30 #include <asm/cacheflush.h>
31 #include <asm/tlb.h>
32
33 static void unmap_region(struct mm_struct *mm,
34                 struct vm_area_struct *vma, struct vm_area_struct *prev,
35                 unsigned long start, unsigned long end);
36
37 /*
38  * WARNING: the debugging will use recursive algorithms so never enable this
39  * unless you know what you are doing.
40  */
41 #undef DEBUG_MM_RB
42
43 /* description of effects of mapping type and prot in current implementation.
44  * this is due to the limited x86 page protection hardware.  The expected
45  * behavior is in parens:
46  *
47  * map_type     prot
48  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
49  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
50  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
51  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
52  *              
53  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
54  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
55  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
56  *
57  */
58 pgprot_t protection_map[16] = {
59         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
60         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
61 };
62
63 int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
64 int sysctl_overcommit_ratio = 50;       /* default is 50% */
65 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
66 atomic_t vm_committed_space = ATOMIC_INIT(0);
67
68 /*
69  * Check that a process has enough memory to allocate a new virtual
70  * mapping. 0 means there is enough memory for the allocation to
71  * succeed and -ENOMEM implies there is not.
72  *
73  * We currently support three overcommit policies, which are set via the
74  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
75  *
76  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
77  * Additional code 2002 Jul 20 by Robert Love.
78  *
79  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
80  *
81  * Note this is a helper function intended to be used by LSMs which
82  * wish to use this logic.
83  */
84 int __vm_enough_memory(long pages, int cap_sys_admin)
85 {
86         unsigned long free, allowed;
87
88         vm_acct_memory(pages);
89
90         /*
91          * Sometimes we want to use more memory than we have
92          */
93         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
94                 return 0;
95
96         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
97                 unsigned long n;
98
99                 free = get_page_cache_size();
100                 free += nr_swap_pages;
101
102                 /*
103                  * Any slabs which are created with the
104                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
105                  * which are reclaimable, under pressure.  The dentry
106                  * cache and most inode caches should fall into this
107                  */
108                 free += atomic_read(&slab_reclaim_pages);
109
110                 /*
111                  * Leave the last 3% for root
112                  */
113                 if (!cap_sys_admin)
114                         free -= free / 32;
115
116                 if (free > pages)
117                         return 0;
118
119                 /*
120                  * nr_free_pages() is very expensive on large systems,
121                  * only call if we're about to fail.
122                  */
123                 n = nr_free_pages();
124                 if (!cap_sys_admin)
125                         n -= n / 32;
126                 free += n;
127
128                 if (free > pages)
129                         return 0;
130                 vm_unacct_memory(pages);
131                 return -ENOMEM;
132         }
133
134         allowed = (totalram_pages - hugetlb_total_pages())
135                 * sysctl_overcommit_ratio / 100;
136         /*
137          * Leave the last 3% for root
138          */
139         if (!cap_sys_admin)
140                 allowed -= allowed / 32;
141         allowed += total_swap_pages;
142
143         /* Don't let a single process grow too big:
144            leave 3% of the size of this process for other processes */
145         allowed -= current->mm->total_vm / 32;
146
147         /*
148          * cast `allowed' as a signed long because vm_committed_space
149          * sometimes has a negative value
150          */
151         if (atomic_read(&vm_committed_space) < (long)allowed)
152                 return 0;
153
154         vm_unacct_memory(pages);
155
156         return -ENOMEM;
157 }
158
159 EXPORT_SYMBOL(__vm_enough_memory);
160
161 /*
162  * Requires inode->i_mapping->i_mmap_lock
163  */
164 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
165                 struct file *file, struct address_space *mapping)
166 {
167         if (vma->vm_flags & VM_DENYWRITE)
168                 atomic_inc(&file->f_dentry->d_inode->i_writecount);
169         if (vma->vm_flags & VM_SHARED)
170                 mapping->i_mmap_writable--;
171
172         flush_dcache_mmap_lock(mapping);
173         if (unlikely(vma->vm_flags & VM_NONLINEAR))
174                 list_del_init(&vma->shared.vm_set.list);
175         else
176                 vma_prio_tree_remove(vma, &mapping->i_mmap);
177         flush_dcache_mmap_unlock(mapping);
178 }
179
180 /*
181  * Unlink a file-based vm structure from its prio_tree, to hide
182  * vma from rmap and vmtruncate before freeing its page tables.
183  */
184 void unlink_file_vma(struct vm_area_struct *vma)
185 {
186         struct file *file = vma->vm_file;
187
188         if (file) {
189                 struct address_space *mapping = file->f_mapping;
190                 spin_lock(&mapping->i_mmap_lock);
191                 __remove_shared_vm_struct(vma, file, mapping);
192                 spin_unlock(&mapping->i_mmap_lock);
193         }
194 }
195
196 /*
197  * Close a vm structure and free it, returning the next.
198  */
199 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
200 {
201         struct vm_area_struct *next = vma->vm_next;
202
203         might_sleep();
204         if (vma->vm_ops && vma->vm_ops->close)
205                 vma->vm_ops->close(vma);
206         if (vma->vm_file)
207                 fput(vma->vm_file);
208         mpol_free(vma_policy(vma));
209         kmem_cache_free(vm_area_cachep, vma);
210         return next;
211 }
212
213 asmlinkage unsigned long sys_brk(unsigned long brk)
214 {
215         unsigned long rlim, retval;
216         unsigned long newbrk, oldbrk;
217         struct mm_struct *mm = current->mm;
218
219         down_write(&mm->mmap_sem);
220
221         if (brk < mm->end_code)
222                 goto out;
223
224         /*
225          * Check against rlimit here. If this check is done later after the test
226          * of oldbrk with newbrk then it can escape the test and let the data
227          * segment grow beyond its set limit the in case where the limit is
228          * not page aligned -Ram Gupta
229          */
230         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
231         if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
232                 goto out;
233
234         newbrk = PAGE_ALIGN(brk);
235         oldbrk = PAGE_ALIGN(mm->brk);
236         if (oldbrk == newbrk)
237                 goto set_brk;
238
239         /* Always allow shrinking brk. */
240         if (brk <= mm->brk) {
241                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
242                         goto set_brk;
243                 goto out;
244         }
245
246         /* Check against existing mmap mappings. */
247         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
248                 goto out;
249
250         /* Ok, looks good - let it rip. */
251         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
252                 goto out;
253 set_brk:
254         mm->brk = brk;
255 out:
256         retval = mm->brk;
257         up_write(&mm->mmap_sem);
258         return retval;
259 }
260
261 #ifdef DEBUG_MM_RB
262 static int browse_rb(struct rb_root *root)
263 {
264         int i = 0, j;
265         struct rb_node *nd, *pn = NULL;
266         unsigned long prev = 0, pend = 0;
267
268         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
269                 struct vm_area_struct *vma;
270                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
271                 if (vma->vm_start < prev)
272                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
273                 if (vma->vm_start < pend)
274                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
275                 if (vma->vm_start > vma->vm_end)
276                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
277                 i++;
278                 pn = nd;
279         }
280         j = 0;
281         for (nd = pn; nd; nd = rb_prev(nd)) {
282                 j++;
283         }
284         if (i != j)
285                 printk("backwards %d, forwards %d\n", j, i), i = 0;
286         return i;
287 }
288
289 void validate_mm(struct mm_struct *mm)
290 {
291         int bug = 0;
292         int i = 0;
293         struct vm_area_struct *tmp = mm->mmap;
294         while (tmp) {
295                 tmp = tmp->vm_next;
296                 i++;
297         }
298         if (i != mm->map_count)
299                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
300         i = browse_rb(&mm->mm_rb);
301         if (i != mm->map_count)
302                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
303         BUG_ON(bug);
304 }
305 #else
306 #define validate_mm(mm) do { } while (0)
307 #endif
308
309 static struct vm_area_struct *
310 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
311                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
312                 struct rb_node ** rb_parent)
313 {
314         struct vm_area_struct * vma;
315         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
316
317         __rb_link = &mm->mm_rb.rb_node;
318         rb_prev = __rb_parent = NULL;
319         vma = NULL;
320
321         while (*__rb_link) {
322                 struct vm_area_struct *vma_tmp;
323
324                 __rb_parent = *__rb_link;
325                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
326
327                 if (vma_tmp->vm_end > addr) {
328                         vma = vma_tmp;
329                         if (vma_tmp->vm_start <= addr)
330                                 return vma;
331                         __rb_link = &__rb_parent->rb_left;
332                 } else {
333                         rb_prev = __rb_parent;
334                         __rb_link = &__rb_parent->rb_right;
335                 }
336         }
337
338         *pprev = NULL;
339         if (rb_prev)
340                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
341         *rb_link = __rb_link;
342         *rb_parent = __rb_parent;
343         return vma;
344 }
345
346 static inline void
347 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
348                 struct vm_area_struct *prev, struct rb_node *rb_parent)
349 {
350         if (prev) {
351                 vma->vm_next = prev->vm_next;
352                 prev->vm_next = vma;
353         } else {
354                 mm->mmap = vma;
355                 if (rb_parent)
356                         vma->vm_next = rb_entry(rb_parent,
357                                         struct vm_area_struct, vm_rb);
358                 else
359                         vma->vm_next = NULL;
360         }
361 }
362
363 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
364                 struct rb_node **rb_link, struct rb_node *rb_parent)
365 {
366         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
367         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
368 }
369
370 static inline void __vma_link_file(struct vm_area_struct *vma)
371 {
372         struct file * file;
373
374         file = vma->vm_file;
375         if (file) {
376                 struct address_space *mapping = file->f_mapping;
377
378                 if (vma->vm_flags & VM_DENYWRITE)
379                         atomic_dec(&file->f_dentry->d_inode->i_writecount);
380                 if (vma->vm_flags & VM_SHARED)
381                         mapping->i_mmap_writable++;
382
383                 flush_dcache_mmap_lock(mapping);
384                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
385                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
386                 else
387                         vma_prio_tree_insert(vma, &mapping->i_mmap);
388                 flush_dcache_mmap_unlock(mapping);
389         }
390 }
391
392 static void
393 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
394         struct vm_area_struct *prev, struct rb_node **rb_link,
395         struct rb_node *rb_parent)
396 {
397         __vma_link_list(mm, vma, prev, rb_parent);
398         __vma_link_rb(mm, vma, rb_link, rb_parent);
399         __anon_vma_link(vma);
400 }
401
402 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
403                         struct vm_area_struct *prev, struct rb_node **rb_link,
404                         struct rb_node *rb_parent)
405 {
406         struct address_space *mapping = NULL;
407
408         if (vma->vm_file)
409                 mapping = vma->vm_file->f_mapping;
410
411         if (mapping) {
412                 spin_lock(&mapping->i_mmap_lock);
413                 vma->vm_truncate_count = mapping->truncate_count;
414         }
415         anon_vma_lock(vma);
416
417         __vma_link(mm, vma, prev, rb_link, rb_parent);
418         __vma_link_file(vma);
419
420         anon_vma_unlock(vma);
421         if (mapping)
422                 spin_unlock(&mapping->i_mmap_lock);
423
424         mm->map_count++;
425         validate_mm(mm);
426 }
427
428 /*
429  * Helper for vma_adjust in the split_vma insert case:
430  * insert vm structure into list and rbtree and anon_vma,
431  * but it has already been inserted into prio_tree earlier.
432  */
433 static void
434 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
435 {
436         struct vm_area_struct * __vma, * prev;
437         struct rb_node ** rb_link, * rb_parent;
438
439         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
440         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
441         __vma_link(mm, vma, prev, rb_link, rb_parent);
442         mm->map_count++;
443 }
444
445 static inline void
446 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
447                 struct vm_area_struct *prev)
448 {
449         prev->vm_next = vma->vm_next;
450         rb_erase(&vma->vm_rb, &mm->mm_rb);
451         if (mm->mmap_cache == vma)
452                 mm->mmap_cache = prev;
453 }
454
455 /*
456  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
457  * is already present in an i_mmap tree without adjusting the tree.
458  * The following helper function should be used when such adjustments
459  * are necessary.  The "insert" vma (if any) is to be inserted
460  * before we drop the necessary locks.
461  */
462 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
463         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
464 {
465         struct mm_struct *mm = vma->vm_mm;
466         struct vm_area_struct *next = vma->vm_next;
467         struct vm_area_struct *importer = NULL;
468         struct address_space *mapping = NULL;
469         struct prio_tree_root *root = NULL;
470         struct file *file = vma->vm_file;
471         struct anon_vma *anon_vma = NULL;
472         long adjust_next = 0;
473         int remove_next = 0;
474
475         if (next && !insert) {
476                 if (end >= next->vm_end) {
477                         /*
478                          * vma expands, overlapping all the next, and
479                          * perhaps the one after too (mprotect case 6).
480                          */
481 again:                  remove_next = 1 + (end > next->vm_end);
482                         end = next->vm_end;
483                         anon_vma = next->anon_vma;
484                         importer = vma;
485                 } else if (end > next->vm_start) {
486                         /*
487                          * vma expands, overlapping part of the next:
488                          * mprotect case 5 shifting the boundary up.
489                          */
490                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
491                         anon_vma = next->anon_vma;
492                         importer = vma;
493                 } else if (end < vma->vm_end) {
494                         /*
495                          * vma shrinks, and !insert tells it's not
496                          * split_vma inserting another: so it must be
497                          * mprotect case 4 shifting the boundary down.
498                          */
499                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
500                         anon_vma = next->anon_vma;
501                         importer = next;
502                 }
503         }
504
505         if (file) {
506                 mapping = file->f_mapping;
507                 if (!(vma->vm_flags & VM_NONLINEAR))
508                         root = &mapping->i_mmap;
509                 spin_lock(&mapping->i_mmap_lock);
510                 if (importer &&
511                     vma->vm_truncate_count != next->vm_truncate_count) {
512                         /*
513                          * unmap_mapping_range might be in progress:
514                          * ensure that the expanding vma is rescanned.
515                          */
516                         importer->vm_truncate_count = 0;
517                 }
518                 if (insert) {
519                         insert->vm_truncate_count = vma->vm_truncate_count;
520                         /*
521                          * Put into prio_tree now, so instantiated pages
522                          * are visible to arm/parisc __flush_dcache_page
523                          * throughout; but we cannot insert into address
524                          * space until vma start or end is updated.
525                          */
526                         __vma_link_file(insert);
527                 }
528         }
529
530         /*
531          * When changing only vma->vm_end, we don't really need
532          * anon_vma lock: but is that case worth optimizing out?
533          */
534         if (vma->anon_vma)
535                 anon_vma = vma->anon_vma;
536         if (anon_vma) {
537                 spin_lock(&anon_vma->lock);
538                 /*
539                  * Easily overlooked: when mprotect shifts the boundary,
540                  * make sure the expanding vma has anon_vma set if the
541                  * shrinking vma had, to cover any anon pages imported.
542                  */
543                 if (importer && !importer->anon_vma) {
544                         importer->anon_vma = anon_vma;
545                         __anon_vma_link(importer);
546                 }
547         }
548
549         if (root) {
550                 flush_dcache_mmap_lock(mapping);
551                 vma_prio_tree_remove(vma, root);
552                 if (adjust_next)
553                         vma_prio_tree_remove(next, root);
554         }
555
556         vma->vm_start = start;
557         vma->vm_end = end;
558         vma->vm_pgoff = pgoff;
559         if (adjust_next) {
560                 next->vm_start += adjust_next << PAGE_SHIFT;
561                 next->vm_pgoff += adjust_next;
562         }
563
564         if (root) {
565                 if (adjust_next)
566                         vma_prio_tree_insert(next, root);
567                 vma_prio_tree_insert(vma, root);
568                 flush_dcache_mmap_unlock(mapping);
569         }
570
571         if (remove_next) {
572                 /*
573                  * vma_merge has merged next into vma, and needs
574                  * us to remove next before dropping the locks.
575                  */
576                 __vma_unlink(mm, next, vma);
577                 if (file)
578                         __remove_shared_vm_struct(next, file, mapping);
579                 if (next->anon_vma)
580                         __anon_vma_merge(vma, next);
581         } else if (insert) {
582                 /*
583                  * split_vma has split insert from vma, and needs
584                  * us to insert it before dropping the locks
585                  * (it may either follow vma or precede it).
586                  */
587                 __insert_vm_struct(mm, insert);
588         }
589
590         if (anon_vma)
591                 spin_unlock(&anon_vma->lock);
592         if (mapping)
593                 spin_unlock(&mapping->i_mmap_lock);
594
595         if (remove_next) {
596                 if (file)
597                         fput(file);
598                 mm->map_count--;
599                 mpol_free(vma_policy(next));
600                 kmem_cache_free(vm_area_cachep, next);
601                 /*
602                  * In mprotect's case 6 (see comments on vma_merge),
603                  * we must remove another next too. It would clutter
604                  * up the code too much to do both in one go.
605                  */
606                 if (remove_next == 2) {
607                         next = vma->vm_next;
608                         goto again;
609                 }
610         }
611
612         validate_mm(mm);
613 }
614
615 /*
616  * If the vma has a ->close operation then the driver probably needs to release
617  * per-vma resources, so we don't attempt to merge those.
618  */
619 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
620
621 static inline int is_mergeable_vma(struct vm_area_struct *vma,
622                         struct file *file, unsigned long vm_flags)
623 {
624         if (vma->vm_flags != vm_flags)
625                 return 0;
626         if (vma->vm_file != file)
627                 return 0;
628         if (vma->vm_ops && vma->vm_ops->close)
629                 return 0;
630         return 1;
631 }
632
633 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
634                                         struct anon_vma *anon_vma2)
635 {
636         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
637 }
638
639 /*
640  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
641  * in front of (at a lower virtual address and file offset than) the vma.
642  *
643  * We cannot merge two vmas if they have differently assigned (non-NULL)
644  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
645  *
646  * We don't check here for the merged mmap wrapping around the end of pagecache
647  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
648  * wrap, nor mmaps which cover the final page at index -1UL.
649  */
650 static int
651 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
652         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
653 {
654         if (is_mergeable_vma(vma, file, vm_flags) &&
655             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
656                 if (vma->vm_pgoff == vm_pgoff)
657                         return 1;
658         }
659         return 0;
660 }
661
662 /*
663  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
664  * beyond (at a higher virtual address and file offset than) the vma.
665  *
666  * We cannot merge two vmas if they have differently assigned (non-NULL)
667  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
668  */
669 static int
670 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
671         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
672 {
673         if (is_mergeable_vma(vma, file, vm_flags) &&
674             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
675                 pgoff_t vm_pglen;
676                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
677                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
678                         return 1;
679         }
680         return 0;
681 }
682
683 /*
684  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
685  * whether that can be merged with its predecessor or its successor.
686  * Or both (it neatly fills a hole).
687  *
688  * In most cases - when called for mmap, brk or mremap - [addr,end) is
689  * certain not to be mapped by the time vma_merge is called; but when
690  * called for mprotect, it is certain to be already mapped (either at
691  * an offset within prev, or at the start of next), and the flags of
692  * this area are about to be changed to vm_flags - and the no-change
693  * case has already been eliminated.
694  *
695  * The following mprotect cases have to be considered, where AAAA is
696  * the area passed down from mprotect_fixup, never extending beyond one
697  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
698  *
699  *     AAAA             AAAA                AAAA          AAAA
700  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
701  *    cannot merge    might become    might become    might become
702  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
703  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
704  *    mremap move:                                    PPPPNNNNNNNN 8
705  *        AAAA
706  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
707  *    might become    case 1 below    case 2 below    case 3 below
708  *
709  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
710  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
711  */
712 struct vm_area_struct *vma_merge(struct mm_struct *mm,
713                         struct vm_area_struct *prev, unsigned long addr,
714                         unsigned long end, unsigned long vm_flags,
715                         struct anon_vma *anon_vma, struct file *file,
716                         pgoff_t pgoff, struct mempolicy *policy)
717 {
718         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
719         struct vm_area_struct *area, *next;
720
721         /*
722          * We later require that vma->vm_flags == vm_flags,
723          * so this tests vma->vm_flags & VM_SPECIAL, too.
724          */
725         if (vm_flags & VM_SPECIAL)
726                 return NULL;
727
728         if (prev)
729                 next = prev->vm_next;
730         else
731                 next = mm->mmap;
732         area = next;
733         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
734                 next = next->vm_next;
735
736         /*
737          * Can it merge with the predecessor?
738          */
739         if (prev && prev->vm_end == addr &&
740                         mpol_equal(vma_policy(prev), policy) &&
741                         can_vma_merge_after(prev, vm_flags,
742                                                 anon_vma, file, pgoff)) {
743                 /*
744                  * OK, it can.  Can we now merge in the successor as well?
745                  */
746                 if (next && end == next->vm_start &&
747                                 mpol_equal(policy, vma_policy(next)) &&
748                                 can_vma_merge_before(next, vm_flags,
749                                         anon_vma, file, pgoff+pglen) &&
750                                 is_mergeable_anon_vma(prev->anon_vma,
751                                                       next->anon_vma)) {
752                                                         /* cases 1, 6 */
753                         vma_adjust(prev, prev->vm_start,
754                                 next->vm_end, prev->vm_pgoff, NULL);
755                 } else                                  /* cases 2, 5, 7 */
756                         vma_adjust(prev, prev->vm_start,
757                                 end, prev->vm_pgoff, NULL);
758                 return prev;
759         }
760
761         /*
762          * Can this new request be merged in front of next?
763          */
764         if (next && end == next->vm_start &&
765                         mpol_equal(policy, vma_policy(next)) &&
766                         can_vma_merge_before(next, vm_flags,
767                                         anon_vma, file, pgoff+pglen)) {
768                 if (prev && addr < prev->vm_end)        /* case 4 */
769                         vma_adjust(prev, prev->vm_start,
770                                 addr, prev->vm_pgoff, NULL);
771                 else                                    /* cases 3, 8 */
772                         vma_adjust(area, addr, next->vm_end,
773                                 next->vm_pgoff - pglen, NULL);
774                 return area;
775         }
776
777         return NULL;
778 }
779
780 /*
781  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
782  * neighbouring vmas for a suitable anon_vma, before it goes off
783  * to allocate a new anon_vma.  It checks because a repetitive
784  * sequence of mprotects and faults may otherwise lead to distinct
785  * anon_vmas being allocated, preventing vma merge in subsequent
786  * mprotect.
787  */
788 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
789 {
790         struct vm_area_struct *near;
791         unsigned long vm_flags;
792
793         near = vma->vm_next;
794         if (!near)
795                 goto try_prev;
796
797         /*
798          * Since only mprotect tries to remerge vmas, match flags
799          * which might be mprotected into each other later on.
800          * Neither mlock nor madvise tries to remerge at present,
801          * so leave their flags as obstructing a merge.
802          */
803         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
804         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
805
806         if (near->anon_vma && vma->vm_end == near->vm_start &&
807                         mpol_equal(vma_policy(vma), vma_policy(near)) &&
808                         can_vma_merge_before(near, vm_flags,
809                                 NULL, vma->vm_file, vma->vm_pgoff +
810                                 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
811                 return near->anon_vma;
812 try_prev:
813         /*
814          * It is potentially slow to have to call find_vma_prev here.
815          * But it's only on the first write fault on the vma, not
816          * every time, and we could devise a way to avoid it later
817          * (e.g. stash info in next's anon_vma_node when assigning
818          * an anon_vma, or when trying vma_merge).  Another time.
819          */
820         BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
821         if (!near)
822                 goto none;
823
824         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
825         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
826
827         if (near->anon_vma && near->vm_end == vma->vm_start &&
828                         mpol_equal(vma_policy(near), vma_policy(vma)) &&
829                         can_vma_merge_after(near, vm_flags,
830                                 NULL, vma->vm_file, vma->vm_pgoff))
831                 return near->anon_vma;
832 none:
833         /*
834          * There's no absolute need to look only at touching neighbours:
835          * we could search further afield for "compatible" anon_vmas.
836          * But it would probably just be a waste of time searching,
837          * or lead to too many vmas hanging off the same anon_vma.
838          * We're trying to allow mprotect remerging later on,
839          * not trying to minimize memory used for anon_vmas.
840          */
841         return NULL;
842 }
843
844 #ifdef CONFIG_PROC_FS
845 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
846                                                 struct file *file, long pages)
847 {
848         const unsigned long stack_flags
849                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
850
851         if (file) {
852                 mm->shared_vm += pages;
853                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
854                         mm->exec_vm += pages;
855         } else if (flags & stack_flags)
856                 mm->stack_vm += pages;
857         if (flags & (VM_RESERVED|VM_IO))
858                 mm->reserved_vm += pages;
859 }
860 #endif /* CONFIG_PROC_FS */
861
862 /*
863  * The caller must hold down_write(current->mm->mmap_sem).
864  */
865
866 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
867                         unsigned long len, unsigned long prot,
868                         unsigned long flags, unsigned long pgoff)
869 {
870         struct mm_struct * mm = current->mm;
871         struct vm_area_struct * vma, * prev;
872         struct inode *inode;
873         unsigned int vm_flags;
874         int correct_wcount = 0;
875         int error;
876         struct rb_node ** rb_link, * rb_parent;
877         int accountable = 1;
878         unsigned long charged = 0, reqprot = prot;
879
880         if (file) {
881                 if (is_file_hugepages(file))
882                         accountable = 0;
883
884                 if (!file->f_op || !file->f_op->mmap)
885                         return -ENODEV;
886
887                 if ((prot & PROT_EXEC) &&
888                     (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
889                         return -EPERM;
890         }
891         /*
892          * Does the application expect PROT_READ to imply PROT_EXEC?
893          *
894          * (the exception is when the underlying filesystem is noexec
895          *  mounted, in which case we dont add PROT_EXEC.)
896          */
897         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
898                 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
899                         prot |= PROT_EXEC;
900
901         if (!len)
902                 return -EINVAL;
903
904         /* Careful about overflows.. */
905         len = PAGE_ALIGN(len);
906         if (!len || len > TASK_SIZE)
907                 return -ENOMEM;
908
909         /* offset overflow? */
910         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
911                return -EOVERFLOW;
912
913         /* Too many mappings? */
914         if (mm->map_count > sysctl_max_map_count)
915                 return -ENOMEM;
916
917         /* Obtain the address to map to. we verify (or select) it and ensure
918          * that it represents a valid section of the address space.
919          */
920         addr = get_unmapped_area(file, addr, len, pgoff, flags);
921         if (addr & ~PAGE_MASK)
922                 return addr;
923
924         /* Do simple checking here so the lower-level routines won't have
925          * to. we assume access permissions have been handled by the open
926          * of the memory object, so we don't do any here.
927          */
928         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
929                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
930
931         if (flags & MAP_LOCKED) {
932                 if (!can_do_mlock())
933                         return -EPERM;
934                 vm_flags |= VM_LOCKED;
935         }
936         /* mlock MCL_FUTURE? */
937         if (vm_flags & VM_LOCKED) {
938                 unsigned long locked, lock_limit;
939                 locked = len >> PAGE_SHIFT;
940                 locked += mm->locked_vm;
941                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
942                 lock_limit >>= PAGE_SHIFT;
943                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
944                         return -EAGAIN;
945         }
946
947         inode = file ? file->f_dentry->d_inode : NULL;
948
949         if (file) {
950                 switch (flags & MAP_TYPE) {
951                 case MAP_SHARED:
952                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
953                                 return -EACCES;
954
955                         /*
956                          * Make sure we don't allow writing to an append-only
957                          * file..
958                          */
959                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
960                                 return -EACCES;
961
962                         /*
963                          * Make sure there are no mandatory locks on the file.
964                          */
965                         if (locks_verify_locked(inode))
966                                 return -EAGAIN;
967
968                         vm_flags |= VM_SHARED | VM_MAYSHARE;
969                         if (!(file->f_mode & FMODE_WRITE))
970                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
971
972                         /* fall through */
973                 case MAP_PRIVATE:
974                         if (!(file->f_mode & FMODE_READ))
975                                 return -EACCES;
976                         break;
977
978                 default:
979                         return -EINVAL;
980                 }
981         } else {
982                 switch (flags & MAP_TYPE) {
983                 case MAP_SHARED:
984                         vm_flags |= VM_SHARED | VM_MAYSHARE;
985                         break;
986                 case MAP_PRIVATE:
987                         /*
988                          * Set pgoff according to addr for anon_vma.
989                          */
990                         pgoff = addr >> PAGE_SHIFT;
991                         break;
992                 default:
993                         return -EINVAL;
994                 }
995         }
996
997         error = security_file_mmap(file, reqprot, prot, flags);
998         if (error)
999                 return error;
1000                 
1001         /* Clear old maps */
1002         error = -ENOMEM;
1003 munmap_back:
1004         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1005         if (vma && vma->vm_start < addr + len) {
1006                 if (do_munmap(mm, addr, len))
1007                         return -ENOMEM;
1008                 goto munmap_back;
1009         }
1010
1011         /* Check against address space limit. */
1012         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1013                 return -ENOMEM;
1014
1015         if (accountable && (!(flags & MAP_NORESERVE) ||
1016                             sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1017                 if (vm_flags & VM_SHARED) {
1018                         /* Check memory availability in shmem_file_setup? */
1019                         vm_flags |= VM_ACCOUNT;
1020                 } else if (vm_flags & VM_WRITE) {
1021                         /*
1022                          * Private writable mapping: check memory availability
1023                          */
1024                         charged = len >> PAGE_SHIFT;
1025                         if (security_vm_enough_memory(charged))
1026                                 return -ENOMEM;
1027                         vm_flags |= VM_ACCOUNT;
1028                 }
1029         }
1030
1031         /*
1032          * Can we just expand an old private anonymous mapping?
1033          * The VM_SHARED test is necessary because shmem_zero_setup
1034          * will create the file object for a shared anonymous map below.
1035          */
1036         if (!file && !(vm_flags & VM_SHARED) &&
1037             vma_merge(mm, prev, addr, addr + len, vm_flags,
1038                                         NULL, NULL, pgoff, NULL))
1039                 goto out;
1040
1041         /*
1042          * Determine the object being mapped and call the appropriate
1043          * specific mapper. the address has already been validated, but
1044          * not unmapped, but the maps are removed from the list.
1045          */
1046         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1047         if (!vma) {
1048                 error = -ENOMEM;
1049                 goto unacct_error;
1050         }
1051
1052         vma->vm_mm = mm;
1053         vma->vm_start = addr;
1054         vma->vm_end = addr + len;
1055         vma->vm_flags = vm_flags;
1056         vma->vm_page_prot = protection_map[vm_flags & 0x0f];
1057         vma->vm_pgoff = pgoff;
1058
1059         if (file) {
1060                 error = -EINVAL;
1061                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1062                         goto free_vma;
1063                 if (vm_flags & VM_DENYWRITE) {
1064                         error = deny_write_access(file);
1065                         if (error)
1066                                 goto free_vma;
1067                         correct_wcount = 1;
1068                 }
1069                 vma->vm_file = file;
1070                 get_file(file);
1071                 error = file->f_op->mmap(file, vma);
1072                 if (error)
1073                         goto unmap_and_free_vma;
1074         } else if (vm_flags & VM_SHARED) {
1075                 error = shmem_zero_setup(vma);
1076                 if (error)
1077                         goto free_vma;
1078         }
1079
1080         /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1081          * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1082          * that memory reservation must be checked; but that reservation
1083          * belongs to shared memory object, not to vma: so now clear it.
1084          */
1085         if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1086                 vma->vm_flags &= ~VM_ACCOUNT;
1087
1088         /* Can addr have changed??
1089          *
1090          * Answer: Yes, several device drivers can do it in their
1091          *         f_op->mmap method. -DaveM
1092          */
1093         addr = vma->vm_start;
1094         pgoff = vma->vm_pgoff;
1095         vm_flags = vma->vm_flags;
1096
1097         if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1098                         vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1099                 file = vma->vm_file;
1100                 vma_link(mm, vma, prev, rb_link, rb_parent);
1101                 if (correct_wcount)
1102                         atomic_inc(&inode->i_writecount);
1103         } else {
1104                 if (file) {
1105                         if (correct_wcount)
1106                                 atomic_inc(&inode->i_writecount);
1107                         fput(file);
1108                 }
1109                 mpol_free(vma_policy(vma));
1110                 kmem_cache_free(vm_area_cachep, vma);
1111         }
1112 out:    
1113         mm->total_vm += len >> PAGE_SHIFT;
1114         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1115         if (vm_flags & VM_LOCKED) {
1116                 mm->locked_vm += len >> PAGE_SHIFT;
1117                 make_pages_present(addr, addr + len);
1118         }
1119         if (flags & MAP_POPULATE) {
1120                 up_write(&mm->mmap_sem);
1121                 sys_remap_file_pages(addr, len, 0,
1122                                         pgoff, flags & MAP_NONBLOCK);
1123                 down_write(&mm->mmap_sem);
1124         }
1125         return addr;
1126
1127 unmap_and_free_vma:
1128         if (correct_wcount)
1129                 atomic_inc(&inode->i_writecount);
1130         vma->vm_file = NULL;
1131         fput(file);
1132
1133         /* Undo any partial mapping done by a device driver. */
1134         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1135         charged = 0;
1136 free_vma:
1137         kmem_cache_free(vm_area_cachep, vma);
1138 unacct_error:
1139         if (charged)
1140                 vm_unacct_memory(charged);
1141         return error;
1142 }
1143
1144 EXPORT_SYMBOL(do_mmap_pgoff);
1145
1146 /* Get an address range which is currently unmapped.
1147  * For shmat() with addr=0.
1148  *
1149  * Ugly calling convention alert:
1150  * Return value with the low bits set means error value,
1151  * ie
1152  *      if (ret & ~PAGE_MASK)
1153  *              error = ret;
1154  *
1155  * This function "knows" that -ENOMEM has the bits set.
1156  */
1157 #ifndef HAVE_ARCH_UNMAPPED_AREA
1158 unsigned long
1159 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1160                 unsigned long len, unsigned long pgoff, unsigned long flags)
1161 {
1162         struct mm_struct *mm = current->mm;
1163         struct vm_area_struct *vma;
1164         unsigned long start_addr;
1165
1166         if (len > TASK_SIZE)
1167                 return -ENOMEM;
1168
1169         if (addr) {
1170                 addr = PAGE_ALIGN(addr);
1171                 vma = find_vma(mm, addr);
1172                 if (TASK_SIZE - len >= addr &&
1173                     (!vma || addr + len <= vma->vm_start))
1174                         return addr;
1175         }
1176         if (len > mm->cached_hole_size) {
1177                 start_addr = addr = mm->free_area_cache;
1178         } else {
1179                 start_addr = addr = TASK_UNMAPPED_BASE;
1180                 mm->cached_hole_size = 0;
1181         }
1182
1183 full_search:
1184         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1185                 /* At this point:  (!vma || addr < vma->vm_end). */
1186                 if (TASK_SIZE - len < addr) {
1187                         /*
1188                          * Start a new search - just in case we missed
1189                          * some holes.
1190                          */
1191                         if (start_addr != TASK_UNMAPPED_BASE) {
1192                                 addr = TASK_UNMAPPED_BASE;
1193                                 start_addr = addr;
1194                                 mm->cached_hole_size = 0;
1195                                 goto full_search;
1196                         }
1197                         return -ENOMEM;
1198                 }
1199                 if (!vma || addr + len <= vma->vm_start) {
1200                         /*
1201                          * Remember the place where we stopped the search:
1202                          */
1203                         mm->free_area_cache = addr + len;
1204                         return addr;
1205                 }
1206                 if (addr + mm->cached_hole_size < vma->vm_start)
1207                         mm->cached_hole_size = vma->vm_start - addr;
1208                 addr = vma->vm_end;
1209         }
1210 }
1211 #endif  
1212
1213 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1214 {
1215         /*
1216          * Is this a new hole at the lowest possible address?
1217          */
1218         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1219                 mm->free_area_cache = addr;
1220                 mm->cached_hole_size = ~0UL;
1221         }
1222 }
1223
1224 /*
1225  * This mmap-allocator allocates new areas top-down from below the
1226  * stack's low limit (the base):
1227  */
1228 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1229 unsigned long
1230 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1231                           const unsigned long len, const unsigned long pgoff,
1232                           const unsigned long flags)
1233 {
1234         struct vm_area_struct *vma;
1235         struct mm_struct *mm = current->mm;
1236         unsigned long addr = addr0;
1237
1238         /* requested length too big for entire address space */
1239         if (len > TASK_SIZE)
1240                 return -ENOMEM;
1241
1242         /* requesting a specific address */
1243         if (addr) {
1244                 addr = PAGE_ALIGN(addr);
1245                 vma = find_vma(mm, addr);
1246                 if (TASK_SIZE - len >= addr &&
1247                                 (!vma || addr + len <= vma->vm_start))
1248                         return addr;
1249         }
1250
1251         /* check if free_area_cache is useful for us */
1252         if (len <= mm->cached_hole_size) {
1253                 mm->cached_hole_size = 0;
1254                 mm->free_area_cache = mm->mmap_base;
1255         }
1256
1257         /* either no address requested or can't fit in requested address hole */
1258         addr = mm->free_area_cache;
1259
1260         /* make sure it can fit in the remaining address space */
1261         if (addr > len) {
1262                 vma = find_vma(mm, addr-len);
1263                 if (!vma || addr <= vma->vm_start)
1264                         /* remember the address as a hint for next time */
1265                         return (mm->free_area_cache = addr-len);
1266         }
1267
1268         if (mm->mmap_base < len)
1269                 goto bottomup;
1270
1271         addr = mm->mmap_base-len;
1272
1273         do {
1274                 /*
1275                  * Lookup failure means no vma is above this address,
1276                  * else if new region fits below vma->vm_start,
1277                  * return with success:
1278                  */
1279                 vma = find_vma(mm, addr);
1280                 if (!vma || addr+len <= vma->vm_start)
1281                         /* remember the address as a hint for next time */
1282                         return (mm->free_area_cache = addr);
1283
1284                 /* remember the largest hole we saw so far */
1285                 if (addr + mm->cached_hole_size < vma->vm_start)
1286                         mm->cached_hole_size = vma->vm_start - addr;
1287
1288                 /* try just below the current vma->vm_start */
1289                 addr = vma->vm_start-len;
1290         } while (len < vma->vm_start);
1291
1292 bottomup:
1293         /*
1294          * A failed mmap() very likely causes application failure,
1295          * so fall back to the bottom-up function here. This scenario
1296          * can happen with large stack limits and large mmap()
1297          * allocations.
1298          */
1299         mm->cached_hole_size = ~0UL;
1300         mm->free_area_cache = TASK_UNMAPPED_BASE;
1301         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1302         /*
1303          * Restore the topdown base:
1304          */
1305         mm->free_area_cache = mm->mmap_base;
1306         mm->cached_hole_size = ~0UL;
1307
1308         return addr;
1309 }
1310 #endif
1311
1312 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1313 {
1314         /*
1315          * Is this a new hole at the highest possible address?
1316          */
1317         if (addr > mm->free_area_cache)
1318                 mm->free_area_cache = addr;
1319
1320         /* dont allow allocations above current base */
1321         if (mm->free_area_cache > mm->mmap_base)
1322                 mm->free_area_cache = mm->mmap_base;
1323 }
1324
1325 unsigned long
1326 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1327                 unsigned long pgoff, unsigned long flags)
1328 {
1329         unsigned long ret;
1330
1331         if (!(flags & MAP_FIXED)) {
1332                 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1333
1334                 get_area = current->mm->get_unmapped_area;
1335                 if (file && file->f_op && file->f_op->get_unmapped_area)
1336                         get_area = file->f_op->get_unmapped_area;
1337                 addr = get_area(file, addr, len, pgoff, flags);
1338                 if (IS_ERR_VALUE(addr))
1339                         return addr;
1340         }
1341
1342         if (addr > TASK_SIZE - len)
1343                 return -ENOMEM;
1344         if (addr & ~PAGE_MASK)
1345                 return -EINVAL;
1346         if (file && is_file_hugepages(file))  {
1347                 /*
1348                  * Check if the given range is hugepage aligned, and
1349                  * can be made suitable for hugepages.
1350                  */
1351                 ret = prepare_hugepage_range(addr, len);
1352         } else {
1353                 /*
1354                  * Ensure that a normal request is not falling in a
1355                  * reserved hugepage range.  For some archs like IA-64,
1356                  * there is a separate region for hugepages.
1357                  */
1358                 ret = is_hugepage_only_range(current->mm, addr, len);
1359         }
1360         if (ret)
1361                 return -EINVAL;
1362         return addr;
1363 }
1364
1365 EXPORT_SYMBOL(get_unmapped_area);
1366
1367 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1368 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1369 {
1370         struct vm_area_struct *vma = NULL;
1371
1372         if (mm) {
1373                 /* Check the cache first. */
1374                 /* (Cache hit rate is typically around 35%.) */
1375                 vma = mm->mmap_cache;
1376                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1377                         struct rb_node * rb_node;
1378
1379                         rb_node = mm->mm_rb.rb_node;
1380                         vma = NULL;
1381
1382                         while (rb_node) {
1383                                 struct vm_area_struct * vma_tmp;
1384
1385                                 vma_tmp = rb_entry(rb_node,
1386                                                 struct vm_area_struct, vm_rb);
1387
1388                                 if (vma_tmp->vm_end > addr) {
1389                                         vma = vma_tmp;
1390                                         if (vma_tmp->vm_start <= addr)
1391                                                 break;
1392                                         rb_node = rb_node->rb_left;
1393                                 } else
1394                                         rb_node = rb_node->rb_right;
1395                         }
1396                         if (vma)
1397                                 mm->mmap_cache = vma;
1398                 }
1399         }
1400         return vma;
1401 }
1402
1403 EXPORT_SYMBOL(find_vma);
1404
1405 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1406 struct vm_area_struct *
1407 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1408                         struct vm_area_struct **pprev)
1409 {
1410         struct vm_area_struct *vma = NULL, *prev = NULL;
1411         struct rb_node * rb_node;
1412         if (!mm)
1413                 goto out;
1414
1415         /* Guard against addr being lower than the first VMA */
1416         vma = mm->mmap;
1417
1418         /* Go through the RB tree quickly. */
1419         rb_node = mm->mm_rb.rb_node;
1420
1421         while (rb_node) {
1422                 struct vm_area_struct *vma_tmp;
1423                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1424
1425                 if (addr < vma_tmp->vm_end) {
1426                         rb_node = rb_node->rb_left;
1427                 } else {
1428                         prev = vma_tmp;
1429                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1430                                 break;
1431                         rb_node = rb_node->rb_right;
1432                 }
1433         }
1434
1435 out:
1436         *pprev = prev;
1437         return prev ? prev->vm_next : vma;
1438 }
1439
1440 /*
1441  * Verify that the stack growth is acceptable and
1442  * update accounting. This is shared with both the
1443  * grow-up and grow-down cases.
1444  */
1445 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1446 {
1447         struct mm_struct *mm = vma->vm_mm;
1448         struct rlimit *rlim = current->signal->rlim;
1449
1450         /* address space limit tests */
1451         if (!may_expand_vm(mm, grow))
1452                 return -ENOMEM;
1453
1454         /* Stack limit test */
1455         if (size > rlim[RLIMIT_STACK].rlim_cur)
1456                 return -ENOMEM;
1457
1458         /* mlock limit tests */
1459         if (vma->vm_flags & VM_LOCKED) {
1460                 unsigned long locked;
1461                 unsigned long limit;
1462                 locked = mm->locked_vm + grow;
1463                 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1464                 if (locked > limit && !capable(CAP_IPC_LOCK))
1465                         return -ENOMEM;
1466         }
1467
1468         /*
1469          * Overcommit..  This must be the final test, as it will
1470          * update security statistics.
1471          */
1472         if (security_vm_enough_memory(grow))
1473                 return -ENOMEM;
1474
1475         /* Ok, everything looks good - let it rip */
1476         mm->total_vm += grow;
1477         if (vma->vm_flags & VM_LOCKED)
1478                 mm->locked_vm += grow;
1479         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1480         return 0;
1481 }
1482
1483 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1484 /*
1485  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1486  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1487  */
1488 #ifndef CONFIG_IA64
1489 static inline
1490 #endif
1491 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1492 {
1493         int error;
1494
1495         if (!(vma->vm_flags & VM_GROWSUP))
1496                 return -EFAULT;
1497
1498         /*
1499          * We must make sure the anon_vma is allocated
1500          * so that the anon_vma locking is not a noop.
1501          */
1502         if (unlikely(anon_vma_prepare(vma)))
1503                 return -ENOMEM;
1504         anon_vma_lock(vma);
1505
1506         /*
1507          * vma->vm_start/vm_end cannot change under us because the caller
1508          * is required to hold the mmap_sem in read mode.  We need the
1509          * anon_vma lock to serialize against concurrent expand_stacks.
1510          */
1511         address += 4 + PAGE_SIZE - 1;
1512         address &= PAGE_MASK;
1513         error = 0;
1514
1515         /* Somebody else might have raced and expanded it already */
1516         if (address > vma->vm_end) {
1517                 unsigned long size, grow;
1518
1519                 size = address - vma->vm_start;
1520                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1521
1522                 error = acct_stack_growth(vma, size, grow);
1523                 if (!error)
1524                         vma->vm_end = address;
1525         }
1526         anon_vma_unlock(vma);
1527         return error;
1528 }
1529 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1530
1531 #ifdef CONFIG_STACK_GROWSUP
1532 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1533 {
1534         return expand_upwards(vma, address);
1535 }
1536
1537 struct vm_area_struct *
1538 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1539 {
1540         struct vm_area_struct *vma, *prev;
1541
1542         addr &= PAGE_MASK;
1543         vma = find_vma_prev(mm, addr, &prev);
1544         if (vma && (vma->vm_start <= addr))
1545                 return vma;
1546         if (!prev || expand_stack(prev, addr))
1547                 return NULL;
1548         if (prev->vm_flags & VM_LOCKED) {
1549                 make_pages_present(addr, prev->vm_end);
1550         }
1551         return prev;
1552 }
1553 #else
1554 /*
1555  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1556  */
1557 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1558 {
1559         int error;
1560
1561         /*
1562          * We must make sure the anon_vma is allocated
1563          * so that the anon_vma locking is not a noop.
1564          */
1565         if (unlikely(anon_vma_prepare(vma)))
1566                 return -ENOMEM;
1567         anon_vma_lock(vma);
1568
1569         /*
1570          * vma->vm_start/vm_end cannot change under us because the caller
1571          * is required to hold the mmap_sem in read mode.  We need the
1572          * anon_vma lock to serialize against concurrent expand_stacks.
1573          */
1574         address &= PAGE_MASK;
1575         error = 0;
1576
1577         /* Somebody else might have raced and expanded it already */
1578         if (address < vma->vm_start) {
1579                 unsigned long size, grow;
1580
1581                 size = vma->vm_end - address;
1582                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1583
1584                 error = acct_stack_growth(vma, size, grow);
1585                 if (!error) {
1586                         vma->vm_start = address;
1587                         vma->vm_pgoff -= grow;
1588                 }
1589         }
1590         anon_vma_unlock(vma);
1591         return error;
1592 }
1593
1594 struct vm_area_struct *
1595 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1596 {
1597         struct vm_area_struct * vma;
1598         unsigned long start;
1599
1600         addr &= PAGE_MASK;
1601         vma = find_vma(mm,addr);
1602         if (!vma)
1603                 return NULL;
1604         if (vma->vm_start <= addr)
1605                 return vma;
1606         if (!(vma->vm_flags & VM_GROWSDOWN))
1607                 return NULL;
1608         start = vma->vm_start;
1609         if (expand_stack(vma, addr))
1610                 return NULL;
1611         if (vma->vm_flags & VM_LOCKED) {
1612                 make_pages_present(addr, start);
1613         }
1614         return vma;
1615 }
1616 #endif
1617
1618 /*
1619  * Ok - we have the memory areas we should free on the vma list,
1620  * so release them, and do the vma updates.
1621  *
1622  * Called with the mm semaphore held.
1623  */
1624 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1625 {
1626         /* Update high watermark before we lower total_vm */
1627         update_hiwater_vm(mm);
1628         do {
1629                 long nrpages = vma_pages(vma);
1630
1631                 mm->total_vm -= nrpages;
1632                 if (vma->vm_flags & VM_LOCKED)
1633                         mm->locked_vm -= nrpages;
1634                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1635                 vma = remove_vma(vma);
1636         } while (vma);
1637         validate_mm(mm);
1638 }
1639
1640 /*
1641  * Get rid of page table information in the indicated region.
1642  *
1643  * Called with the mm semaphore held.
1644  */
1645 static void unmap_region(struct mm_struct *mm,
1646                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1647                 unsigned long start, unsigned long end)
1648 {
1649         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1650         struct mmu_gather *tlb;
1651         unsigned long nr_accounted = 0;
1652
1653         lru_add_drain();
1654         tlb = tlb_gather_mmu(mm, 0);
1655         update_hiwater_rss(mm);
1656         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1657         vm_unacct_memory(nr_accounted);
1658         free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1659                                  next? next->vm_start: 0);
1660         tlb_finish_mmu(tlb, start, end);
1661 }
1662
1663 /*
1664  * Create a list of vma's touched by the unmap, removing them from the mm's
1665  * vma list as we go..
1666  */
1667 static void
1668 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1669         struct vm_area_struct *prev, unsigned long end)
1670 {
1671         struct vm_area_struct **insertion_point;
1672         struct vm_area_struct *tail_vma = NULL;
1673         unsigned long addr;
1674
1675         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1676         do {
1677                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1678                 mm->map_count--;
1679                 tail_vma = vma;
1680                 vma = vma->vm_next;
1681         } while (vma && vma->vm_start < end);
1682         *insertion_point = vma;
1683         tail_vma->vm_next = NULL;
1684         if (mm->unmap_area == arch_unmap_area)
1685                 addr = prev ? prev->vm_end : mm->mmap_base;
1686         else
1687                 addr = vma ?  vma->vm_start : mm->mmap_base;
1688         mm->unmap_area(mm, addr);
1689         mm->mmap_cache = NULL;          /* Kill the cache. */
1690 }
1691
1692 /*
1693  * Split a vma into two pieces at address 'addr', a new vma is allocated
1694  * either for the first part or the the tail.
1695  */
1696 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1697               unsigned long addr, int new_below)
1698 {
1699         struct mempolicy *pol;
1700         struct vm_area_struct *new;
1701
1702         if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1703                 return -EINVAL;
1704
1705         if (mm->map_count >= sysctl_max_map_count)
1706                 return -ENOMEM;
1707
1708         new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1709         if (!new)
1710                 return -ENOMEM;
1711
1712         /* most fields are the same, copy all, and then fixup */
1713         *new = *vma;
1714
1715         if (new_below)
1716                 new->vm_end = addr;
1717         else {
1718                 new->vm_start = addr;
1719                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1720         }
1721
1722         pol = mpol_copy(vma_policy(vma));
1723         if (IS_ERR(pol)) {
1724                 kmem_cache_free(vm_area_cachep, new);
1725                 return PTR_ERR(pol);
1726         }
1727         vma_set_policy(new, pol);
1728
1729         if (new->vm_file)
1730                 get_file(new->vm_file);
1731
1732         if (new->vm_ops && new->vm_ops->open)
1733                 new->vm_ops->open(new);
1734
1735         if (new_below)
1736                 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1737                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1738         else
1739                 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1740
1741         return 0;
1742 }
1743
1744 /* Munmap is split into 2 main parts -- this part which finds
1745  * what needs doing, and the areas themselves, which do the
1746  * work.  This now handles partial unmappings.
1747  * Jeremy Fitzhardinge <jeremy@goop.org>
1748  */
1749 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1750 {
1751         unsigned long end;
1752         struct vm_area_struct *vma, *prev, *last;
1753
1754         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1755                 return -EINVAL;
1756
1757         if ((len = PAGE_ALIGN(len)) == 0)
1758                 return -EINVAL;
1759
1760         /* Find the first overlapping VMA */
1761         vma = find_vma_prev(mm, start, &prev);
1762         if (!vma)
1763                 return 0;
1764         /* we have  start < vma->vm_end  */
1765
1766         /* if it doesn't overlap, we have nothing.. */
1767         end = start + len;
1768         if (vma->vm_start >= end)
1769                 return 0;
1770
1771         /*
1772          * If we need to split any vma, do it now to save pain later.
1773          *
1774          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1775          * unmapped vm_area_struct will remain in use: so lower split_vma
1776          * places tmp vma above, and higher split_vma places tmp vma below.
1777          */
1778         if (start > vma->vm_start) {
1779                 int error = split_vma(mm, vma, start, 0);
1780                 if (error)
1781                         return error;
1782                 prev = vma;
1783         }
1784
1785         /* Does it split the last one? */
1786         last = find_vma(mm, end);
1787         if (last && end > last->vm_start) {
1788                 int error = split_vma(mm, last, end, 1);
1789                 if (error)
1790                         return error;
1791         }
1792         vma = prev? prev->vm_next: mm->mmap;
1793
1794         /*
1795          * Remove the vma's, and unmap the actual pages
1796          */
1797         detach_vmas_to_be_unmapped(mm, vma, prev, end);
1798         unmap_region(mm, vma, prev, start, end);
1799
1800         /* Fix up all other VM information */
1801         remove_vma_list(mm, vma);
1802
1803         return 0;
1804 }
1805
1806 EXPORT_SYMBOL(do_munmap);
1807
1808 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1809 {
1810         int ret;
1811         struct mm_struct *mm = current->mm;
1812
1813         profile_munmap(addr);
1814
1815         down_write(&mm->mmap_sem);
1816         ret = do_munmap(mm, addr, len);
1817         up_write(&mm->mmap_sem);
1818         return ret;
1819 }
1820
1821 static inline void verify_mm_writelocked(struct mm_struct *mm)
1822 {
1823 #ifdef CONFIG_DEBUG_VM
1824         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1825                 WARN_ON(1);
1826                 up_read(&mm->mmap_sem);
1827         }
1828 #endif
1829 }
1830
1831 /*
1832  *  this is really a simplified "do_mmap".  it only handles
1833  *  anonymous maps.  eventually we may be able to do some
1834  *  brk-specific accounting here.
1835  */
1836 unsigned long do_brk(unsigned long addr, unsigned long len)
1837 {
1838         struct mm_struct * mm = current->mm;
1839         struct vm_area_struct * vma, * prev;
1840         unsigned long flags;
1841         struct rb_node ** rb_link, * rb_parent;
1842         pgoff_t pgoff = addr >> PAGE_SHIFT;
1843
1844         len = PAGE_ALIGN(len);
1845         if (!len)
1846                 return addr;
1847
1848         if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1849                 return -EINVAL;
1850
1851         /*
1852          * mlock MCL_FUTURE?
1853          */
1854         if (mm->def_flags & VM_LOCKED) {
1855                 unsigned long locked, lock_limit;
1856                 locked = len >> PAGE_SHIFT;
1857                 locked += mm->locked_vm;
1858                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1859                 lock_limit >>= PAGE_SHIFT;
1860                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1861                         return -EAGAIN;
1862         }
1863
1864         /*
1865          * mm->mmap_sem is required to protect against another thread
1866          * changing the mappings in case we sleep.
1867          */
1868         verify_mm_writelocked(mm);
1869
1870         /*
1871          * Clear old maps.  this also does some error checking for us
1872          */
1873  munmap_back:
1874         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1875         if (vma && vma->vm_start < addr + len) {
1876                 if (do_munmap(mm, addr, len))
1877                         return -ENOMEM;
1878                 goto munmap_back;
1879         }
1880
1881         /* Check against address space limits *after* clearing old maps... */
1882         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1883                 return -ENOMEM;
1884
1885         if (mm->map_count > sysctl_max_map_count)
1886                 return -ENOMEM;
1887
1888         if (security_vm_enough_memory(len >> PAGE_SHIFT))
1889                 return -ENOMEM;
1890
1891         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1892
1893         /* Can we just expand an old private anonymous mapping? */
1894         if (vma_merge(mm, prev, addr, addr + len, flags,
1895                                         NULL, NULL, pgoff, NULL))
1896                 goto out;
1897
1898         /*
1899          * create a vma struct for an anonymous mapping
1900          */
1901         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1902         if (!vma) {
1903                 vm_unacct_memory(len >> PAGE_SHIFT);
1904                 return -ENOMEM;
1905         }
1906
1907         vma->vm_mm = mm;
1908         vma->vm_start = addr;
1909         vma->vm_end = addr + len;
1910         vma->vm_pgoff = pgoff;
1911         vma->vm_flags = flags;
1912         vma->vm_page_prot = protection_map[flags & 0x0f];
1913         vma_link(mm, vma, prev, rb_link, rb_parent);
1914 out:
1915         mm->total_vm += len >> PAGE_SHIFT;
1916         if (flags & VM_LOCKED) {
1917                 mm->locked_vm += len >> PAGE_SHIFT;
1918                 make_pages_present(addr, addr + len);
1919         }
1920         return addr;
1921 }
1922
1923 EXPORT_SYMBOL(do_brk);
1924
1925 /* Release all mmaps. */
1926 void exit_mmap(struct mm_struct *mm)
1927 {
1928         struct mmu_gather *tlb;
1929         struct vm_area_struct *vma = mm->mmap;
1930         unsigned long nr_accounted = 0;
1931         unsigned long end;
1932
1933         lru_add_drain();
1934         flush_cache_mm(mm);
1935         tlb = tlb_gather_mmu(mm, 1);
1936         /* Don't update_hiwater_rss(mm) here, do_exit already did */
1937         /* Use -1 here to ensure all VMAs in the mm are unmapped */
1938         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
1939         vm_unacct_memory(nr_accounted);
1940         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
1941         tlb_finish_mmu(tlb, 0, end);
1942
1943         /*
1944          * Walk the list again, actually closing and freeing it,
1945          * with preemption enabled, without holding any MM locks.
1946          */
1947         while (vma)
1948                 vma = remove_vma(vma);
1949
1950         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
1951 }
1952
1953 /* Insert vm structure into process list sorted by address
1954  * and into the inode's i_mmap tree.  If vm_file is non-NULL
1955  * then i_mmap_lock is taken here.
1956  */
1957 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
1958 {
1959         struct vm_area_struct * __vma, * prev;
1960         struct rb_node ** rb_link, * rb_parent;
1961
1962         /*
1963          * The vm_pgoff of a purely anonymous vma should be irrelevant
1964          * until its first write fault, when page's anon_vma and index
1965          * are set.  But now set the vm_pgoff it will almost certainly
1966          * end up with (unless mremap moves it elsewhere before that
1967          * first wfault), so /proc/pid/maps tells a consistent story.
1968          *
1969          * By setting it to reflect the virtual start address of the
1970          * vma, merges and splits can happen in a seamless way, just
1971          * using the existing file pgoff checks and manipulations.
1972          * Similarly in do_mmap_pgoff and in do_brk.
1973          */
1974         if (!vma->vm_file) {
1975                 BUG_ON(vma->anon_vma);
1976                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
1977         }
1978         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
1979         if (__vma && __vma->vm_start < vma->vm_end)
1980                 return -ENOMEM;
1981         if ((vma->vm_flags & VM_ACCOUNT) &&
1982              security_vm_enough_memory(vma_pages(vma)))
1983                 return -ENOMEM;
1984         vma_link(mm, vma, prev, rb_link, rb_parent);
1985         return 0;
1986 }
1987
1988 /*
1989  * Copy the vma structure to a new location in the same mm,
1990  * prior to moving page table entries, to effect an mremap move.
1991  */
1992 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
1993         unsigned long addr, unsigned long len, pgoff_t pgoff)
1994 {
1995         struct vm_area_struct *vma = *vmap;
1996         unsigned long vma_start = vma->vm_start;
1997         struct mm_struct *mm = vma->vm_mm;
1998         struct vm_area_struct *new_vma, *prev;
1999         struct rb_node **rb_link, *rb_parent;
2000         struct mempolicy *pol;
2001
2002         /*
2003          * If anonymous vma has not yet been faulted, update new pgoff
2004          * to match new location, to increase its chance of merging.
2005          */
2006         if (!vma->vm_file && !vma->anon_vma)
2007                 pgoff = addr >> PAGE_SHIFT;
2008
2009         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2010         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2011                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2012         if (new_vma) {
2013                 /*
2014                  * Source vma may have been merged into new_vma
2015                  */
2016                 if (vma_start >= new_vma->vm_start &&
2017                     vma_start < new_vma->vm_end)
2018                         *vmap = new_vma;
2019         } else {
2020                 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
2021                 if (new_vma) {
2022                         *new_vma = *vma;
2023                         pol = mpol_copy(vma_policy(vma));
2024                         if (IS_ERR(pol)) {
2025                                 kmem_cache_free(vm_area_cachep, new_vma);
2026                                 return NULL;
2027                         }
2028                         vma_set_policy(new_vma, pol);
2029                         new_vma->vm_start = addr;
2030                         new_vma->vm_end = addr + len;
2031                         new_vma->vm_pgoff = pgoff;
2032                         if (new_vma->vm_file)
2033                                 get_file(new_vma->vm_file);
2034                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2035                                 new_vma->vm_ops->open(new_vma);
2036                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2037                 }
2038         }
2039         return new_vma;
2040 }
2041
2042 /*
2043  * Return true if the calling process may expand its vm space by the passed
2044  * number of pages
2045  */
2046 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2047 {
2048         unsigned long cur = mm->total_vm;       /* pages */
2049         unsigned long lim;
2050
2051         lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2052
2053         if (cur + npages > lim)
2054                 return 0;
2055         return 1;
2056 }