[GFS2] Fix up merge of Linus' kernel into GFS2
[linux-2.6] / 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 #ifndef arch_mmap_check
34 #define arch_mmap_check(addr, len, flags)       (0)
35 #endif
36
37 static void unmap_region(struct mm_struct *mm,
38                 struct vm_area_struct *vma, struct vm_area_struct *prev,
39                 unsigned long start, unsigned long end);
40
41 /*
42  * WARNING: the debugging will use recursive algorithms so never enable this
43  * unless you know what you are doing.
44  */
45 #undef DEBUG_MM_RB
46
47 /* description of effects of mapping type and prot in current implementation.
48  * this is due to the limited x86 page protection hardware.  The expected
49  * behavior is in parens:
50  *
51  * map_type     prot
52  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
53  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
54  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
55  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
56  *              
57  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
58  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
59  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
60  *
61  */
62 pgprot_t protection_map[16] = {
63         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
64         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
65 };
66
67 pgprot_t vm_get_page_prot(unsigned long vm_flags)
68 {
69         return protection_map[vm_flags &
70                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
71 }
72 EXPORT_SYMBOL(vm_get_page_prot);
73
74 int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
75 int sysctl_overcommit_ratio = 50;       /* default is 50% */
76 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
77 atomic_t vm_committed_space = ATOMIC_INIT(0);
78
79 /*
80  * Check that a process has enough memory to allocate a new virtual
81  * mapping. 0 means there is enough memory for the allocation to
82  * succeed and -ENOMEM implies there is not.
83  *
84  * We currently support three overcommit policies, which are set via the
85  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
86  *
87  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
88  * Additional code 2002 Jul 20 by Robert Love.
89  *
90  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
91  *
92  * Note this is a helper function intended to be used by LSMs which
93  * wish to use this logic.
94  */
95 int __vm_enough_memory(long pages, int cap_sys_admin)
96 {
97         unsigned long free, allowed;
98
99         vm_acct_memory(pages);
100
101         /*
102          * Sometimes we want to use more memory than we have
103          */
104         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
105                 return 0;
106
107         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
108                 unsigned long n;
109
110                 free = global_page_state(NR_FILE_PAGES);
111                 free += nr_swap_pages;
112
113                 /*
114                  * Any slabs which are created with the
115                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
116                  * which are reclaimable, under pressure.  The dentry
117                  * cache and most inode caches should fall into this
118                  */
119                 free += atomic_read(&slab_reclaim_pages);
120
121                 /*
122                  * Leave the last 3% for root
123                  */
124                 if (!cap_sys_admin)
125                         free -= free / 32;
126
127                 if (free > pages)
128                         return 0;
129
130                 /*
131                  * nr_free_pages() is very expensive on large systems,
132                  * only call if we're about to fail.
133                  */
134                 n = nr_free_pages();
135
136                 /*
137                  * Leave reserved pages. The pages are not for anonymous pages.
138                  */
139                 if (n <= totalreserve_pages)
140                         goto error;
141                 else
142                         n -= totalreserve_pages;
143
144                 /*
145                  * Leave the last 3% for root
146                  */
147                 if (!cap_sys_admin)
148                         n -= n / 32;
149                 free += n;
150
151                 if (free > pages)
152                         return 0;
153
154                 goto error;
155         }
156
157         allowed = (totalram_pages - hugetlb_total_pages())
158                 * sysctl_overcommit_ratio / 100;
159         /*
160          * Leave the last 3% for root
161          */
162         if (!cap_sys_admin)
163                 allowed -= allowed / 32;
164         allowed += total_swap_pages;
165
166         /* Don't let a single process grow too big:
167            leave 3% of the size of this process for other processes */
168         allowed -= current->mm->total_vm / 32;
169
170         /*
171          * cast `allowed' as a signed long because vm_committed_space
172          * sometimes has a negative value
173          */
174         if (atomic_read(&vm_committed_space) < (long)allowed)
175                 return 0;
176 error:
177         vm_unacct_memory(pages);
178
179         return -ENOMEM;
180 }
181
182 EXPORT_SYMBOL(__vm_enough_memory);
183
184 /*
185  * Requires inode->i_mapping->i_mmap_lock
186  */
187 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
188                 struct file *file, struct address_space *mapping)
189 {
190         if (vma->vm_flags & VM_DENYWRITE)
191                 atomic_inc(&file->f_dentry->d_inode->i_writecount);
192         if (vma->vm_flags & VM_SHARED)
193                 mapping->i_mmap_writable--;
194
195         flush_dcache_mmap_lock(mapping);
196         if (unlikely(vma->vm_flags & VM_NONLINEAR))
197                 list_del_init(&vma->shared.vm_set.list);
198         else
199                 vma_prio_tree_remove(vma, &mapping->i_mmap);
200         flush_dcache_mmap_unlock(mapping);
201 }
202
203 /*
204  * Unlink a file-based vm structure from its prio_tree, to hide
205  * vma from rmap and vmtruncate before freeing its page tables.
206  */
207 void unlink_file_vma(struct vm_area_struct *vma)
208 {
209         struct file *file = vma->vm_file;
210
211         if (file) {
212                 struct address_space *mapping = file->f_mapping;
213                 spin_lock(&mapping->i_mmap_lock);
214                 __remove_shared_vm_struct(vma, file, mapping);
215                 spin_unlock(&mapping->i_mmap_lock);
216         }
217 }
218
219 /*
220  * Close a vm structure and free it, returning the next.
221  */
222 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
223 {
224         struct vm_area_struct *next = vma->vm_next;
225
226         might_sleep();
227         if (vma->vm_ops && vma->vm_ops->close)
228                 vma->vm_ops->close(vma);
229         if (vma->vm_file)
230                 fput(vma->vm_file);
231         mpol_free(vma_policy(vma));
232         kmem_cache_free(vm_area_cachep, vma);
233         return next;
234 }
235
236 asmlinkage unsigned long sys_brk(unsigned long brk)
237 {
238         unsigned long rlim, retval;
239         unsigned long newbrk, oldbrk;
240         struct mm_struct *mm = current->mm;
241
242         down_write(&mm->mmap_sem);
243
244         if (brk < mm->end_code)
245                 goto out;
246
247         /*
248          * Check against rlimit here. If this check is done later after the test
249          * of oldbrk with newbrk then it can escape the test and let the data
250          * segment grow beyond its set limit the in case where the limit is
251          * not page aligned -Ram Gupta
252          */
253         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
254         if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
255                 goto out;
256
257         newbrk = PAGE_ALIGN(brk);
258         oldbrk = PAGE_ALIGN(mm->brk);
259         if (oldbrk == newbrk)
260                 goto set_brk;
261
262         /* Always allow shrinking brk. */
263         if (brk <= mm->brk) {
264                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
265                         goto set_brk;
266                 goto out;
267         }
268
269         /* Check against existing mmap mappings. */
270         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
271                 goto out;
272
273         /* Ok, looks good - let it rip. */
274         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
275                 goto out;
276 set_brk:
277         mm->brk = brk;
278 out:
279         retval = mm->brk;
280         up_write(&mm->mmap_sem);
281         return retval;
282 }
283
284 #ifdef DEBUG_MM_RB
285 static int browse_rb(struct rb_root *root)
286 {
287         int i = 0, j;
288         struct rb_node *nd, *pn = NULL;
289         unsigned long prev = 0, pend = 0;
290
291         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
292                 struct vm_area_struct *vma;
293                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
294                 if (vma->vm_start < prev)
295                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
296                 if (vma->vm_start < pend)
297                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
298                 if (vma->vm_start > vma->vm_end)
299                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
300                 i++;
301                 pn = nd;
302         }
303         j = 0;
304         for (nd = pn; nd; nd = rb_prev(nd)) {
305                 j++;
306         }
307         if (i != j)
308                 printk("backwards %d, forwards %d\n", j, i), i = 0;
309         return i;
310 }
311
312 void validate_mm(struct mm_struct *mm)
313 {
314         int bug = 0;
315         int i = 0;
316         struct vm_area_struct *tmp = mm->mmap;
317         while (tmp) {
318                 tmp = tmp->vm_next;
319                 i++;
320         }
321         if (i != mm->map_count)
322                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
323         i = browse_rb(&mm->mm_rb);
324         if (i != mm->map_count)
325                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
326         BUG_ON(bug);
327 }
328 #else
329 #define validate_mm(mm) do { } while (0)
330 #endif
331
332 static struct vm_area_struct *
333 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
334                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
335                 struct rb_node ** rb_parent)
336 {
337         struct vm_area_struct * vma;
338         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
339
340         __rb_link = &mm->mm_rb.rb_node;
341         rb_prev = __rb_parent = NULL;
342         vma = NULL;
343
344         while (*__rb_link) {
345                 struct vm_area_struct *vma_tmp;
346
347                 __rb_parent = *__rb_link;
348                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
349
350                 if (vma_tmp->vm_end > addr) {
351                         vma = vma_tmp;
352                         if (vma_tmp->vm_start <= addr)
353                                 return vma;
354                         __rb_link = &__rb_parent->rb_left;
355                 } else {
356                         rb_prev = __rb_parent;
357                         __rb_link = &__rb_parent->rb_right;
358                 }
359         }
360
361         *pprev = NULL;
362         if (rb_prev)
363                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
364         *rb_link = __rb_link;
365         *rb_parent = __rb_parent;
366         return vma;
367 }
368
369 static inline void
370 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
371                 struct vm_area_struct *prev, struct rb_node *rb_parent)
372 {
373         if (prev) {
374                 vma->vm_next = prev->vm_next;
375                 prev->vm_next = vma;
376         } else {
377                 mm->mmap = vma;
378                 if (rb_parent)
379                         vma->vm_next = rb_entry(rb_parent,
380                                         struct vm_area_struct, vm_rb);
381                 else
382                         vma->vm_next = NULL;
383         }
384 }
385
386 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
387                 struct rb_node **rb_link, struct rb_node *rb_parent)
388 {
389         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
390         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
391 }
392
393 static inline void __vma_link_file(struct vm_area_struct *vma)
394 {
395         struct file * file;
396
397         file = vma->vm_file;
398         if (file) {
399                 struct address_space *mapping = file->f_mapping;
400
401                 if (vma->vm_flags & VM_DENYWRITE)
402                         atomic_dec(&file->f_dentry->d_inode->i_writecount);
403                 if (vma->vm_flags & VM_SHARED)
404                         mapping->i_mmap_writable++;
405
406                 flush_dcache_mmap_lock(mapping);
407                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
408                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
409                 else
410                         vma_prio_tree_insert(vma, &mapping->i_mmap);
411                 flush_dcache_mmap_unlock(mapping);
412         }
413 }
414
415 static void
416 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
417         struct vm_area_struct *prev, struct rb_node **rb_link,
418         struct rb_node *rb_parent)
419 {
420         __vma_link_list(mm, vma, prev, rb_parent);
421         __vma_link_rb(mm, vma, rb_link, rb_parent);
422         __anon_vma_link(vma);
423 }
424
425 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
426                         struct vm_area_struct *prev, struct rb_node **rb_link,
427                         struct rb_node *rb_parent)
428 {
429         struct address_space *mapping = NULL;
430
431         if (vma->vm_file)
432                 mapping = vma->vm_file->f_mapping;
433
434         if (mapping) {
435                 spin_lock(&mapping->i_mmap_lock);
436                 vma->vm_truncate_count = mapping->truncate_count;
437         }
438         anon_vma_lock(vma);
439
440         __vma_link(mm, vma, prev, rb_link, rb_parent);
441         __vma_link_file(vma);
442
443         anon_vma_unlock(vma);
444         if (mapping)
445                 spin_unlock(&mapping->i_mmap_lock);
446
447         mm->map_count++;
448         validate_mm(mm);
449 }
450
451 /*
452  * Helper for vma_adjust in the split_vma insert case:
453  * insert vm structure into list and rbtree and anon_vma,
454  * but it has already been inserted into prio_tree earlier.
455  */
456 static void
457 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
458 {
459         struct vm_area_struct * __vma, * prev;
460         struct rb_node ** rb_link, * rb_parent;
461
462         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
463         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
464         __vma_link(mm, vma, prev, rb_link, rb_parent);
465         mm->map_count++;
466 }
467
468 static inline void
469 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
470                 struct vm_area_struct *prev)
471 {
472         prev->vm_next = vma->vm_next;
473         rb_erase(&vma->vm_rb, &mm->mm_rb);
474         if (mm->mmap_cache == vma)
475                 mm->mmap_cache = prev;
476 }
477
478 /*
479  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
480  * is already present in an i_mmap tree without adjusting the tree.
481  * The following helper function should be used when such adjustments
482  * are necessary.  The "insert" vma (if any) is to be inserted
483  * before we drop the necessary locks.
484  */
485 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
486         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
487 {
488         struct mm_struct *mm = vma->vm_mm;
489         struct vm_area_struct *next = vma->vm_next;
490         struct vm_area_struct *importer = NULL;
491         struct address_space *mapping = NULL;
492         struct prio_tree_root *root = NULL;
493         struct file *file = vma->vm_file;
494         struct anon_vma *anon_vma = NULL;
495         long adjust_next = 0;
496         int remove_next = 0;
497
498         if (next && !insert) {
499                 if (end >= next->vm_end) {
500                         /*
501                          * vma expands, overlapping all the next, and
502                          * perhaps the one after too (mprotect case 6).
503                          */
504 again:                  remove_next = 1 + (end > next->vm_end);
505                         end = next->vm_end;
506                         anon_vma = next->anon_vma;
507                         importer = vma;
508                 } else if (end > next->vm_start) {
509                         /*
510                          * vma expands, overlapping part of the next:
511                          * mprotect case 5 shifting the boundary up.
512                          */
513                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
514                         anon_vma = next->anon_vma;
515                         importer = vma;
516                 } else if (end < vma->vm_end) {
517                         /*
518                          * vma shrinks, and !insert tells it's not
519                          * split_vma inserting another: so it must be
520                          * mprotect case 4 shifting the boundary down.
521                          */
522                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
523                         anon_vma = next->anon_vma;
524                         importer = next;
525                 }
526         }
527
528         if (file) {
529                 mapping = file->f_mapping;
530                 if (!(vma->vm_flags & VM_NONLINEAR))
531                         root = &mapping->i_mmap;
532                 spin_lock(&mapping->i_mmap_lock);
533                 if (importer &&
534                     vma->vm_truncate_count != next->vm_truncate_count) {
535                         /*
536                          * unmap_mapping_range might be in progress:
537                          * ensure that the expanding vma is rescanned.
538                          */
539                         importer->vm_truncate_count = 0;
540                 }
541                 if (insert) {
542                         insert->vm_truncate_count = vma->vm_truncate_count;
543                         /*
544                          * Put into prio_tree now, so instantiated pages
545                          * are visible to arm/parisc __flush_dcache_page
546                          * throughout; but we cannot insert into address
547                          * space until vma start or end is updated.
548                          */
549                         __vma_link_file(insert);
550                 }
551         }
552
553         /*
554          * When changing only vma->vm_end, we don't really need
555          * anon_vma lock: but is that case worth optimizing out?
556          */
557         if (vma->anon_vma)
558                 anon_vma = vma->anon_vma;
559         if (anon_vma) {
560                 spin_lock(&anon_vma->lock);
561                 /*
562                  * Easily overlooked: when mprotect shifts the boundary,
563                  * make sure the expanding vma has anon_vma set if the
564                  * shrinking vma had, to cover any anon pages imported.
565                  */
566                 if (importer && !importer->anon_vma) {
567                         importer->anon_vma = anon_vma;
568                         __anon_vma_link(importer);
569                 }
570         }
571
572         if (root) {
573                 flush_dcache_mmap_lock(mapping);
574                 vma_prio_tree_remove(vma, root);
575                 if (adjust_next)
576                         vma_prio_tree_remove(next, root);
577         }
578
579         vma->vm_start = start;
580         vma->vm_end = end;
581         vma->vm_pgoff = pgoff;
582         if (adjust_next) {
583                 next->vm_start += adjust_next << PAGE_SHIFT;
584                 next->vm_pgoff += adjust_next;
585         }
586
587         if (root) {
588                 if (adjust_next)
589                         vma_prio_tree_insert(next, root);
590                 vma_prio_tree_insert(vma, root);
591                 flush_dcache_mmap_unlock(mapping);
592         }
593
594         if (remove_next) {
595                 /*
596                  * vma_merge has merged next into vma, and needs
597                  * us to remove next before dropping the locks.
598                  */
599                 __vma_unlink(mm, next, vma);
600                 if (file)
601                         __remove_shared_vm_struct(next, file, mapping);
602                 if (next->anon_vma)
603                         __anon_vma_merge(vma, next);
604         } else if (insert) {
605                 /*
606                  * split_vma has split insert from vma, and needs
607                  * us to insert it before dropping the locks
608                  * (it may either follow vma or precede it).
609                  */
610                 __insert_vm_struct(mm, insert);
611         }
612
613         if (anon_vma)
614                 spin_unlock(&anon_vma->lock);
615         if (mapping)
616                 spin_unlock(&mapping->i_mmap_lock);
617
618         if (remove_next) {
619                 if (file)
620                         fput(file);
621                 mm->map_count--;
622                 mpol_free(vma_policy(next));
623                 kmem_cache_free(vm_area_cachep, next);
624                 /*
625                  * In mprotect's case 6 (see comments on vma_merge),
626                  * we must remove another next too. It would clutter
627                  * up the code too much to do both in one go.
628                  */
629                 if (remove_next == 2) {
630                         next = vma->vm_next;
631                         goto again;
632                 }
633         }
634
635         validate_mm(mm);
636 }
637
638 /*
639  * If the vma has a ->close operation then the driver probably needs to release
640  * per-vma resources, so we don't attempt to merge those.
641  */
642 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
643
644 static inline int is_mergeable_vma(struct vm_area_struct *vma,
645                         struct file *file, unsigned long vm_flags)
646 {
647         if (vma->vm_flags != vm_flags)
648                 return 0;
649         if (vma->vm_file != file)
650                 return 0;
651         if (vma->vm_ops && vma->vm_ops->close)
652                 return 0;
653         return 1;
654 }
655
656 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
657                                         struct anon_vma *anon_vma2)
658 {
659         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
660 }
661
662 /*
663  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
664  * in front of (at a lower 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  * We don't check here for the merged mmap wrapping around the end of pagecache
670  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
671  * wrap, nor mmaps which cover the final page at index -1UL.
672  */
673 static int
674 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
675         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
676 {
677         if (is_mergeable_vma(vma, file, vm_flags) &&
678             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
679                 if (vma->vm_pgoff == vm_pgoff)
680                         return 1;
681         }
682         return 0;
683 }
684
685 /*
686  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
687  * beyond (at a higher virtual address and file offset than) the vma.
688  *
689  * We cannot merge two vmas if they have differently assigned (non-NULL)
690  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
691  */
692 static int
693 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
694         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
695 {
696         if (is_mergeable_vma(vma, file, vm_flags) &&
697             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
698                 pgoff_t vm_pglen;
699                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
700                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
701                         return 1;
702         }
703         return 0;
704 }
705
706 /*
707  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
708  * whether that can be merged with its predecessor or its successor.
709  * Or both (it neatly fills a hole).
710  *
711  * In most cases - when called for mmap, brk or mremap - [addr,end) is
712  * certain not to be mapped by the time vma_merge is called; but when
713  * called for mprotect, it is certain to be already mapped (either at
714  * an offset within prev, or at the start of next), and the flags of
715  * this area are about to be changed to vm_flags - and the no-change
716  * case has already been eliminated.
717  *
718  * The following mprotect cases have to be considered, where AAAA is
719  * the area passed down from mprotect_fixup, never extending beyond one
720  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
721  *
722  *     AAAA             AAAA                AAAA          AAAA
723  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
724  *    cannot merge    might become    might become    might become
725  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
726  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
727  *    mremap move:                                    PPPPNNNNNNNN 8
728  *        AAAA
729  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
730  *    might become    case 1 below    case 2 below    case 3 below
731  *
732  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
733  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
734  */
735 struct vm_area_struct *vma_merge(struct mm_struct *mm,
736                         struct vm_area_struct *prev, unsigned long addr,
737                         unsigned long end, unsigned long vm_flags,
738                         struct anon_vma *anon_vma, struct file *file,
739                         pgoff_t pgoff, struct mempolicy *policy)
740 {
741         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
742         struct vm_area_struct *area, *next;
743
744         /*
745          * We later require that vma->vm_flags == vm_flags,
746          * so this tests vma->vm_flags & VM_SPECIAL, too.
747          */
748         if (vm_flags & VM_SPECIAL)
749                 return NULL;
750
751         if (prev)
752                 next = prev->vm_next;
753         else
754                 next = mm->mmap;
755         area = next;
756         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
757                 next = next->vm_next;
758
759         /*
760          * Can it merge with the predecessor?
761          */
762         if (prev && prev->vm_end == addr &&
763                         mpol_equal(vma_policy(prev), policy) &&
764                         can_vma_merge_after(prev, vm_flags,
765                                                 anon_vma, file, pgoff)) {
766                 /*
767                  * OK, it can.  Can we now merge in the successor as well?
768                  */
769                 if (next && end == next->vm_start &&
770                                 mpol_equal(policy, vma_policy(next)) &&
771                                 can_vma_merge_before(next, vm_flags,
772                                         anon_vma, file, pgoff+pglen) &&
773                                 is_mergeable_anon_vma(prev->anon_vma,
774                                                       next->anon_vma)) {
775                                                         /* cases 1, 6 */
776                         vma_adjust(prev, prev->vm_start,
777                                 next->vm_end, prev->vm_pgoff, NULL);
778                 } else                                  /* cases 2, 5, 7 */
779                         vma_adjust(prev, prev->vm_start,
780                                 end, prev->vm_pgoff, NULL);
781                 return prev;
782         }
783
784         /*
785          * Can this new request be merged in front of next?
786          */
787         if (next && end == next->vm_start &&
788                         mpol_equal(policy, vma_policy(next)) &&
789                         can_vma_merge_before(next, vm_flags,
790                                         anon_vma, file, pgoff+pglen)) {
791                 if (prev && addr < prev->vm_end)        /* case 4 */
792                         vma_adjust(prev, prev->vm_start,
793                                 addr, prev->vm_pgoff, NULL);
794                 else                                    /* cases 3, 8 */
795                         vma_adjust(area, addr, next->vm_end,
796                                 next->vm_pgoff - pglen, NULL);
797                 return area;
798         }
799
800         return NULL;
801 }
802
803 /*
804  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
805  * neighbouring vmas for a suitable anon_vma, before it goes off
806  * to allocate a new anon_vma.  It checks because a repetitive
807  * sequence of mprotects and faults may otherwise lead to distinct
808  * anon_vmas being allocated, preventing vma merge in subsequent
809  * mprotect.
810  */
811 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
812 {
813         struct vm_area_struct *near;
814         unsigned long vm_flags;
815
816         near = vma->vm_next;
817         if (!near)
818                 goto try_prev;
819
820         /*
821          * Since only mprotect tries to remerge vmas, match flags
822          * which might be mprotected into each other later on.
823          * Neither mlock nor madvise tries to remerge at present,
824          * so leave their flags as obstructing a merge.
825          */
826         vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
827         vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
828
829         if (near->anon_vma && vma->vm_end == near->vm_start &&
830                         mpol_equal(vma_policy(vma), vma_policy(near)) &&
831                         can_vma_merge_before(near, vm_flags,
832                                 NULL, vma->vm_file, vma->vm_pgoff +
833                                 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
834                 return near->anon_vma;
835 try_prev:
836         /*
837          * It is potentially slow to have to call find_vma_prev here.
838          * But it's only on the first write fault on the vma, not
839          * every time, and we could devise a way to avoid it later
840          * (e.g. stash info in next's anon_vma_node when assigning
841          * an anon_vma, or when trying vma_merge).  Another time.
842          */
843         BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
844         if (!near)
845                 goto none;
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 && near->vm_end == vma->vm_start &&
851                         mpol_equal(vma_policy(near), vma_policy(vma)) &&
852                         can_vma_merge_after(near, vm_flags,
853                                 NULL, vma->vm_file, vma->vm_pgoff))
854                 return near->anon_vma;
855 none:
856         /*
857          * There's no absolute need to look only at touching neighbours:
858          * we could search further afield for "compatible" anon_vmas.
859          * But it would probably just be a waste of time searching,
860          * or lead to too many vmas hanging off the same anon_vma.
861          * We're trying to allow mprotect remerging later on,
862          * not trying to minimize memory used for anon_vmas.
863          */
864         return NULL;
865 }
866
867 #ifdef CONFIG_PROC_FS
868 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
869                                                 struct file *file, long pages)
870 {
871         const unsigned long stack_flags
872                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
873
874         if (file) {
875                 mm->shared_vm += pages;
876                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
877                         mm->exec_vm += pages;
878         } else if (flags & stack_flags)
879                 mm->stack_vm += pages;
880         if (flags & (VM_RESERVED|VM_IO))
881                 mm->reserved_vm += pages;
882 }
883 #endif /* CONFIG_PROC_FS */
884
885 /*
886  * The caller must hold down_write(current->mm->mmap_sem).
887  */
888
889 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
890                         unsigned long len, unsigned long prot,
891                         unsigned long flags, unsigned long pgoff)
892 {
893         struct mm_struct * mm = current->mm;
894         struct vm_area_struct * vma, * prev;
895         struct inode *inode;
896         unsigned int vm_flags;
897         int correct_wcount = 0;
898         int error;
899         struct rb_node ** rb_link, * rb_parent;
900         int accountable = 1;
901         unsigned long charged = 0, reqprot = prot;
902
903         if (file) {
904                 if (is_file_hugepages(file))
905                         accountable = 0;
906
907                 if (!file->f_op || !file->f_op->mmap)
908                         return -ENODEV;
909
910                 if ((prot & PROT_EXEC) &&
911                     (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
912                         return -EPERM;
913         }
914         /*
915          * Does the application expect PROT_READ to imply PROT_EXEC?
916          *
917          * (the exception is when the underlying filesystem is noexec
918          *  mounted, in which case we dont add PROT_EXEC.)
919          */
920         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
921                 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
922                         prot |= PROT_EXEC;
923
924         if (!len)
925                 return -EINVAL;
926
927         error = arch_mmap_check(addr, len, flags);
928         if (error)
929                 return error;
930
931         /* Careful about overflows.. */
932         len = PAGE_ALIGN(len);
933         if (!len || len > TASK_SIZE)
934                 return -ENOMEM;
935
936         /* offset overflow? */
937         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
938                return -EOVERFLOW;
939
940         /* Too many mappings? */
941         if (mm->map_count > sysctl_max_map_count)
942                 return -ENOMEM;
943
944         /* Obtain the address to map to. we verify (or select) it and ensure
945          * that it represents a valid section of the address space.
946          */
947         addr = get_unmapped_area(file, addr, len, pgoff, flags);
948         if (addr & ~PAGE_MASK)
949                 return addr;
950
951         /* Do simple checking here so the lower-level routines won't have
952          * to. we assume access permissions have been handled by the open
953          * of the memory object, so we don't do any here.
954          */
955         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
956                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
957
958         if (flags & MAP_LOCKED) {
959                 if (!can_do_mlock())
960                         return -EPERM;
961                 vm_flags |= VM_LOCKED;
962         }
963         /* mlock MCL_FUTURE? */
964         if (vm_flags & VM_LOCKED) {
965                 unsigned long locked, lock_limit;
966                 locked = len >> PAGE_SHIFT;
967                 locked += mm->locked_vm;
968                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
969                 lock_limit >>= PAGE_SHIFT;
970                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
971                         return -EAGAIN;
972         }
973
974         inode = file ? file->f_dentry->d_inode : NULL;
975
976         if (file) {
977                 switch (flags & MAP_TYPE) {
978                 case MAP_SHARED:
979                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
980                                 return -EACCES;
981
982                         /*
983                          * Make sure we don't allow writing to an append-only
984                          * file..
985                          */
986                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
987                                 return -EACCES;
988
989                         /*
990                          * Make sure there are no mandatory locks on the file.
991                          */
992                         if (locks_verify_locked(inode))
993                                 return -EAGAIN;
994
995                         vm_flags |= VM_SHARED | VM_MAYSHARE;
996                         if (!(file->f_mode & FMODE_WRITE))
997                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
998
999                         /* fall through */
1000                 case MAP_PRIVATE:
1001                         if (!(file->f_mode & FMODE_READ))
1002                                 return -EACCES;
1003                         break;
1004
1005                 default:
1006                         return -EINVAL;
1007                 }
1008         } else {
1009                 switch (flags & MAP_TYPE) {
1010                 case MAP_SHARED:
1011                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1012                         break;
1013                 case MAP_PRIVATE:
1014                         /*
1015                          * Set pgoff according to addr for anon_vma.
1016                          */
1017                         pgoff = addr >> PAGE_SHIFT;
1018                         break;
1019                 default:
1020                         return -EINVAL;
1021                 }
1022         }
1023
1024         error = security_file_mmap(file, reqprot, prot, flags);
1025         if (error)
1026                 return error;
1027                 
1028         /* Clear old maps */
1029         error = -ENOMEM;
1030 munmap_back:
1031         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1032         if (vma && vma->vm_start < addr + len) {
1033                 if (do_munmap(mm, addr, len))
1034                         return -ENOMEM;
1035                 goto munmap_back;
1036         }
1037
1038         /* Check against address space limit. */
1039         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1040                 return -ENOMEM;
1041
1042         if (accountable && (!(flags & MAP_NORESERVE) ||
1043                             sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1044                 if (vm_flags & VM_SHARED) {
1045                         /* Check memory availability in shmem_file_setup? */
1046                         vm_flags |= VM_ACCOUNT;
1047                 } else if (vm_flags & VM_WRITE) {
1048                         /*
1049                          * Private writable mapping: check memory availability
1050                          */
1051                         charged = len >> PAGE_SHIFT;
1052                         if (security_vm_enough_memory(charged))
1053                                 return -ENOMEM;
1054                         vm_flags |= VM_ACCOUNT;
1055                 }
1056         }
1057
1058         /*
1059          * Can we just expand an old private anonymous mapping?
1060          * The VM_SHARED test is necessary because shmem_zero_setup
1061          * will create the file object for a shared anonymous map below.
1062          */
1063         if (!file && !(vm_flags & VM_SHARED) &&
1064             vma_merge(mm, prev, addr, addr + len, vm_flags,
1065                                         NULL, NULL, pgoff, NULL))
1066                 goto out;
1067
1068         /*
1069          * Determine the object being mapped and call the appropriate
1070          * specific mapper. the address has already been validated, but
1071          * not unmapped, but the maps are removed from the list.
1072          */
1073         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1074         if (!vma) {
1075                 error = -ENOMEM;
1076                 goto unacct_error;
1077         }
1078
1079         vma->vm_mm = mm;
1080         vma->vm_start = addr;
1081         vma->vm_end = addr + len;
1082         vma->vm_flags = vm_flags;
1083         vma->vm_page_prot = protection_map[vm_flags &
1084                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
1085         vma->vm_pgoff = pgoff;
1086
1087         if (file) {
1088                 error = -EINVAL;
1089                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1090                         goto free_vma;
1091                 if (vm_flags & VM_DENYWRITE) {
1092                         error = deny_write_access(file);
1093                         if (error)
1094                                 goto free_vma;
1095                         correct_wcount = 1;
1096                 }
1097                 vma->vm_file = file;
1098                 get_file(file);
1099                 error = file->f_op->mmap(file, vma);
1100                 if (error)
1101                         goto unmap_and_free_vma;
1102         } else if (vm_flags & VM_SHARED) {
1103                 error = shmem_zero_setup(vma);
1104                 if (error)
1105                         goto free_vma;
1106         }
1107
1108         /* Don't make the VMA automatically writable if it's shared, but the
1109          * backer wishes to know when pages are first written to */
1110         if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1111                 vma->vm_page_prot =
1112                         protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)];
1113
1114         /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1115          * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1116          * that memory reservation must be checked; but that reservation
1117          * belongs to shared memory object, not to vma: so now clear it.
1118          */
1119         if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1120                 vma->vm_flags &= ~VM_ACCOUNT;
1121
1122         /* Can addr have changed??
1123          *
1124          * Answer: Yes, several device drivers can do it in their
1125          *         f_op->mmap method. -DaveM
1126          */
1127         addr = vma->vm_start;
1128         pgoff = vma->vm_pgoff;
1129         vm_flags = vma->vm_flags;
1130
1131         if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1132                         vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1133                 file = vma->vm_file;
1134                 vma_link(mm, vma, prev, rb_link, rb_parent);
1135                 if (correct_wcount)
1136                         atomic_inc(&inode->i_writecount);
1137         } else {
1138                 if (file) {
1139                         if (correct_wcount)
1140                                 atomic_inc(&inode->i_writecount);
1141                         fput(file);
1142                 }
1143                 mpol_free(vma_policy(vma));
1144                 kmem_cache_free(vm_area_cachep, vma);
1145         }
1146 out:    
1147         mm->total_vm += len >> PAGE_SHIFT;
1148         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1149         if (vm_flags & VM_LOCKED) {
1150                 mm->locked_vm += len >> PAGE_SHIFT;
1151                 make_pages_present(addr, addr + len);
1152         }
1153         if (flags & MAP_POPULATE) {
1154                 up_write(&mm->mmap_sem);
1155                 sys_remap_file_pages(addr, len, 0,
1156                                         pgoff, flags & MAP_NONBLOCK);
1157                 down_write(&mm->mmap_sem);
1158         }
1159         return addr;
1160
1161 unmap_and_free_vma:
1162         if (correct_wcount)
1163                 atomic_inc(&inode->i_writecount);
1164         vma->vm_file = NULL;
1165         fput(file);
1166
1167         /* Undo any partial mapping done by a device driver. */
1168         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1169         charged = 0;
1170 free_vma:
1171         kmem_cache_free(vm_area_cachep, vma);
1172 unacct_error:
1173         if (charged)
1174                 vm_unacct_memory(charged);
1175         return error;
1176 }
1177
1178 EXPORT_SYMBOL(do_mmap_pgoff);
1179
1180 /* Get an address range which is currently unmapped.
1181  * For shmat() with addr=0.
1182  *
1183  * Ugly calling convention alert:
1184  * Return value with the low bits set means error value,
1185  * ie
1186  *      if (ret & ~PAGE_MASK)
1187  *              error = ret;
1188  *
1189  * This function "knows" that -ENOMEM has the bits set.
1190  */
1191 #ifndef HAVE_ARCH_UNMAPPED_AREA
1192 unsigned long
1193 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1194                 unsigned long len, unsigned long pgoff, unsigned long flags)
1195 {
1196         struct mm_struct *mm = current->mm;
1197         struct vm_area_struct *vma;
1198         unsigned long start_addr;
1199
1200         if (len > TASK_SIZE)
1201                 return -ENOMEM;
1202
1203         if (addr) {
1204                 addr = PAGE_ALIGN(addr);
1205                 vma = find_vma(mm, addr);
1206                 if (TASK_SIZE - len >= addr &&
1207                     (!vma || addr + len <= vma->vm_start))
1208                         return addr;
1209         }
1210         if (len > mm->cached_hole_size) {
1211                 start_addr = addr = mm->free_area_cache;
1212         } else {
1213                 start_addr = addr = TASK_UNMAPPED_BASE;
1214                 mm->cached_hole_size = 0;
1215         }
1216
1217 full_search:
1218         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1219                 /* At this point:  (!vma || addr < vma->vm_end). */
1220                 if (TASK_SIZE - len < addr) {
1221                         /*
1222                          * Start a new search - just in case we missed
1223                          * some holes.
1224                          */
1225                         if (start_addr != TASK_UNMAPPED_BASE) {
1226                                 addr = TASK_UNMAPPED_BASE;
1227                                 start_addr = addr;
1228                                 mm->cached_hole_size = 0;
1229                                 goto full_search;
1230                         }
1231                         return -ENOMEM;
1232                 }
1233                 if (!vma || addr + len <= vma->vm_start) {
1234                         /*
1235                          * Remember the place where we stopped the search:
1236                          */
1237                         mm->free_area_cache = addr + len;
1238                         return addr;
1239                 }
1240                 if (addr + mm->cached_hole_size < vma->vm_start)
1241                         mm->cached_hole_size = vma->vm_start - addr;
1242                 addr = vma->vm_end;
1243         }
1244 }
1245 #endif  
1246
1247 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1248 {
1249         /*
1250          * Is this a new hole at the lowest possible address?
1251          */
1252         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1253                 mm->free_area_cache = addr;
1254                 mm->cached_hole_size = ~0UL;
1255         }
1256 }
1257
1258 /*
1259  * This mmap-allocator allocates new areas top-down from below the
1260  * stack's low limit (the base):
1261  */
1262 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1263 unsigned long
1264 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1265                           const unsigned long len, const unsigned long pgoff,
1266                           const unsigned long flags)
1267 {
1268         struct vm_area_struct *vma;
1269         struct mm_struct *mm = current->mm;
1270         unsigned long addr = addr0;
1271
1272         /* requested length too big for entire address space */
1273         if (len > TASK_SIZE)
1274                 return -ENOMEM;
1275
1276         /* requesting a specific address */
1277         if (addr) {
1278                 addr = PAGE_ALIGN(addr);
1279                 vma = find_vma(mm, addr);
1280                 if (TASK_SIZE - len >= addr &&
1281                                 (!vma || addr + len <= vma->vm_start))
1282                         return addr;
1283         }
1284
1285         /* check if free_area_cache is useful for us */
1286         if (len <= mm->cached_hole_size) {
1287                 mm->cached_hole_size = 0;
1288                 mm->free_area_cache = mm->mmap_base;
1289         }
1290
1291         /* either no address requested or can't fit in requested address hole */
1292         addr = mm->free_area_cache;
1293
1294         /* make sure it can fit in the remaining address space */
1295         if (addr > len) {
1296                 vma = find_vma(mm, addr-len);
1297                 if (!vma || addr <= vma->vm_start)
1298                         /* remember the address as a hint for next time */
1299                         return (mm->free_area_cache = addr-len);
1300         }
1301
1302         if (mm->mmap_base < len)
1303                 goto bottomup;
1304
1305         addr = mm->mmap_base-len;
1306
1307         do {
1308                 /*
1309                  * Lookup failure means no vma is above this address,
1310                  * else if new region fits below vma->vm_start,
1311                  * return with success:
1312                  */
1313                 vma = find_vma(mm, addr);
1314                 if (!vma || addr+len <= vma->vm_start)
1315                         /* remember the address as a hint for next time */
1316                         return (mm->free_area_cache = addr);
1317
1318                 /* remember the largest hole we saw so far */
1319                 if (addr + mm->cached_hole_size < vma->vm_start)
1320                         mm->cached_hole_size = vma->vm_start - addr;
1321
1322                 /* try just below the current vma->vm_start */
1323                 addr = vma->vm_start-len;
1324         } while (len < vma->vm_start);
1325
1326 bottomup:
1327         /*
1328          * A failed mmap() very likely causes application failure,
1329          * so fall back to the bottom-up function here. This scenario
1330          * can happen with large stack limits and large mmap()
1331          * allocations.
1332          */
1333         mm->cached_hole_size = ~0UL;
1334         mm->free_area_cache = TASK_UNMAPPED_BASE;
1335         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1336         /*
1337          * Restore the topdown base:
1338          */
1339         mm->free_area_cache = mm->mmap_base;
1340         mm->cached_hole_size = ~0UL;
1341
1342         return addr;
1343 }
1344 #endif
1345
1346 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1347 {
1348         /*
1349          * Is this a new hole at the highest possible address?
1350          */
1351         if (addr > mm->free_area_cache)
1352                 mm->free_area_cache = addr;
1353
1354         /* dont allow allocations above current base */
1355         if (mm->free_area_cache > mm->mmap_base)
1356                 mm->free_area_cache = mm->mmap_base;
1357 }
1358
1359 unsigned long
1360 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1361                 unsigned long pgoff, unsigned long flags)
1362 {
1363         unsigned long ret;
1364
1365         if (!(flags & MAP_FIXED)) {
1366                 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1367
1368                 get_area = current->mm->get_unmapped_area;
1369                 if (file && file->f_op && file->f_op->get_unmapped_area)
1370                         get_area = file->f_op->get_unmapped_area;
1371                 addr = get_area(file, addr, len, pgoff, flags);
1372                 if (IS_ERR_VALUE(addr))
1373                         return addr;
1374         }
1375
1376         if (addr > TASK_SIZE - len)
1377                 return -ENOMEM;
1378         if (addr & ~PAGE_MASK)
1379                 return -EINVAL;
1380         if (file && is_file_hugepages(file))  {
1381                 /*
1382                  * Check if the given range is hugepage aligned, and
1383                  * can be made suitable for hugepages.
1384                  */
1385                 ret = prepare_hugepage_range(addr, len);
1386         } else {
1387                 /*
1388                  * Ensure that a normal request is not falling in a
1389                  * reserved hugepage range.  For some archs like IA-64,
1390                  * there is a separate region for hugepages.
1391                  */
1392                 ret = is_hugepage_only_range(current->mm, addr, len);
1393         }
1394         if (ret)
1395                 return -EINVAL;
1396         return addr;
1397 }
1398
1399 EXPORT_SYMBOL(get_unmapped_area);
1400
1401 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1402 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1403 {
1404         struct vm_area_struct *vma = NULL;
1405
1406         if (mm) {
1407                 /* Check the cache first. */
1408                 /* (Cache hit rate is typically around 35%.) */
1409                 vma = mm->mmap_cache;
1410                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1411                         struct rb_node * rb_node;
1412
1413                         rb_node = mm->mm_rb.rb_node;
1414                         vma = NULL;
1415
1416                         while (rb_node) {
1417                                 struct vm_area_struct * vma_tmp;
1418
1419                                 vma_tmp = rb_entry(rb_node,
1420                                                 struct vm_area_struct, vm_rb);
1421
1422                                 if (vma_tmp->vm_end > addr) {
1423                                         vma = vma_tmp;
1424                                         if (vma_tmp->vm_start <= addr)
1425                                                 break;
1426                                         rb_node = rb_node->rb_left;
1427                                 } else
1428                                         rb_node = rb_node->rb_right;
1429                         }
1430                         if (vma)
1431                                 mm->mmap_cache = vma;
1432                 }
1433         }
1434         return vma;
1435 }
1436
1437 EXPORT_SYMBOL(find_vma);
1438
1439 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1440 struct vm_area_struct *
1441 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1442                         struct vm_area_struct **pprev)
1443 {
1444         struct vm_area_struct *vma = NULL, *prev = NULL;
1445         struct rb_node * rb_node;
1446         if (!mm)
1447                 goto out;
1448
1449         /* Guard against addr being lower than the first VMA */
1450         vma = mm->mmap;
1451
1452         /* Go through the RB tree quickly. */
1453         rb_node = mm->mm_rb.rb_node;
1454
1455         while (rb_node) {
1456                 struct vm_area_struct *vma_tmp;
1457                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1458
1459                 if (addr < vma_tmp->vm_end) {
1460                         rb_node = rb_node->rb_left;
1461                 } else {
1462                         prev = vma_tmp;
1463                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1464                                 break;
1465                         rb_node = rb_node->rb_right;
1466                 }
1467         }
1468
1469 out:
1470         *pprev = prev;
1471         return prev ? prev->vm_next : vma;
1472 }
1473
1474 /*
1475  * Verify that the stack growth is acceptable and
1476  * update accounting. This is shared with both the
1477  * grow-up and grow-down cases.
1478  */
1479 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1480 {
1481         struct mm_struct *mm = vma->vm_mm;
1482         struct rlimit *rlim = current->signal->rlim;
1483
1484         /* address space limit tests */
1485         if (!may_expand_vm(mm, grow))
1486                 return -ENOMEM;
1487
1488         /* Stack limit test */
1489         if (size > rlim[RLIMIT_STACK].rlim_cur)
1490                 return -ENOMEM;
1491
1492         /* mlock limit tests */
1493         if (vma->vm_flags & VM_LOCKED) {
1494                 unsigned long locked;
1495                 unsigned long limit;
1496                 locked = mm->locked_vm + grow;
1497                 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1498                 if (locked > limit && !capable(CAP_IPC_LOCK))
1499                         return -ENOMEM;
1500         }
1501
1502         /*
1503          * Overcommit..  This must be the final test, as it will
1504          * update security statistics.
1505          */
1506         if (security_vm_enough_memory(grow))
1507                 return -ENOMEM;
1508
1509         /* Ok, everything looks good - let it rip */
1510         mm->total_vm += grow;
1511         if (vma->vm_flags & VM_LOCKED)
1512                 mm->locked_vm += grow;
1513         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1514         return 0;
1515 }
1516
1517 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1518 /*
1519  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1520  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1521  */
1522 #ifndef CONFIG_IA64
1523 static inline
1524 #endif
1525 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1526 {
1527         int error;
1528
1529         if (!(vma->vm_flags & VM_GROWSUP))
1530                 return -EFAULT;
1531
1532         /*
1533          * We must make sure the anon_vma is allocated
1534          * so that the anon_vma locking is not a noop.
1535          */
1536         if (unlikely(anon_vma_prepare(vma)))
1537                 return -ENOMEM;
1538         anon_vma_lock(vma);
1539
1540         /*
1541          * vma->vm_start/vm_end cannot change under us because the caller
1542          * is required to hold the mmap_sem in read mode.  We need the
1543          * anon_vma lock to serialize against concurrent expand_stacks.
1544          */
1545         address += 4 + PAGE_SIZE - 1;
1546         address &= PAGE_MASK;
1547         error = 0;
1548
1549         /* Somebody else might have raced and expanded it already */
1550         if (address > vma->vm_end) {
1551                 unsigned long size, grow;
1552
1553                 size = address - vma->vm_start;
1554                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1555
1556                 error = acct_stack_growth(vma, size, grow);
1557                 if (!error)
1558                         vma->vm_end = address;
1559         }
1560         anon_vma_unlock(vma);
1561         return error;
1562 }
1563 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1564
1565 #ifdef CONFIG_STACK_GROWSUP
1566 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1567 {
1568         return expand_upwards(vma, address);
1569 }
1570
1571 struct vm_area_struct *
1572 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1573 {
1574         struct vm_area_struct *vma, *prev;
1575
1576         addr &= PAGE_MASK;
1577         vma = find_vma_prev(mm, addr, &prev);
1578         if (vma && (vma->vm_start <= addr))
1579                 return vma;
1580         if (!prev || expand_stack(prev, addr))
1581                 return NULL;
1582         if (prev->vm_flags & VM_LOCKED) {
1583                 make_pages_present(addr, prev->vm_end);
1584         }
1585         return prev;
1586 }
1587 #else
1588 /*
1589  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1590  */
1591 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1592 {
1593         int error;
1594
1595         /*
1596          * We must make sure the anon_vma is allocated
1597          * so that the anon_vma locking is not a noop.
1598          */
1599         if (unlikely(anon_vma_prepare(vma)))
1600                 return -ENOMEM;
1601         anon_vma_lock(vma);
1602
1603         /*
1604          * vma->vm_start/vm_end cannot change under us because the caller
1605          * is required to hold the mmap_sem in read mode.  We need the
1606          * anon_vma lock to serialize against concurrent expand_stacks.
1607          */
1608         address &= PAGE_MASK;
1609         error = 0;
1610
1611         /* Somebody else might have raced and expanded it already */
1612         if (address < vma->vm_start) {
1613                 unsigned long size, grow;
1614
1615                 size = vma->vm_end - address;
1616                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1617
1618                 error = acct_stack_growth(vma, size, grow);
1619                 if (!error) {
1620                         vma->vm_start = address;
1621                         vma->vm_pgoff -= grow;
1622                 }
1623         }
1624         anon_vma_unlock(vma);
1625         return error;
1626 }
1627
1628 struct vm_area_struct *
1629 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1630 {
1631         struct vm_area_struct * vma;
1632         unsigned long start;
1633
1634         addr &= PAGE_MASK;
1635         vma = find_vma(mm,addr);
1636         if (!vma)
1637                 return NULL;
1638         if (vma->vm_start <= addr)
1639                 return vma;
1640         if (!(vma->vm_flags & VM_GROWSDOWN))
1641                 return NULL;
1642         start = vma->vm_start;
1643         if (expand_stack(vma, addr))
1644                 return NULL;
1645         if (vma->vm_flags & VM_LOCKED) {
1646                 make_pages_present(addr, start);
1647         }
1648         return vma;
1649 }
1650 #endif
1651
1652 /*
1653  * Ok - we have the memory areas we should free on the vma list,
1654  * so release them, and do the vma updates.
1655  *
1656  * Called with the mm semaphore held.
1657  */
1658 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1659 {
1660         /* Update high watermark before we lower total_vm */
1661         update_hiwater_vm(mm);
1662         do {
1663                 long nrpages = vma_pages(vma);
1664
1665                 mm->total_vm -= nrpages;
1666                 if (vma->vm_flags & VM_LOCKED)
1667                         mm->locked_vm -= nrpages;
1668                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1669                 vma = remove_vma(vma);
1670         } while (vma);
1671         validate_mm(mm);
1672 }
1673
1674 /*
1675  * Get rid of page table information in the indicated region.
1676  *
1677  * Called with the mm semaphore held.
1678  */
1679 static void unmap_region(struct mm_struct *mm,
1680                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1681                 unsigned long start, unsigned long end)
1682 {
1683         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1684         struct mmu_gather *tlb;
1685         unsigned long nr_accounted = 0;
1686
1687         lru_add_drain();
1688         tlb = tlb_gather_mmu(mm, 0);
1689         update_hiwater_rss(mm);
1690         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1691         vm_unacct_memory(nr_accounted);
1692         free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1693                                  next? next->vm_start: 0);
1694         tlb_finish_mmu(tlb, start, end);
1695 }
1696
1697 /*
1698  * Create a list of vma's touched by the unmap, removing them from the mm's
1699  * vma list as we go..
1700  */
1701 static void
1702 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1703         struct vm_area_struct *prev, unsigned long end)
1704 {
1705         struct vm_area_struct **insertion_point;
1706         struct vm_area_struct *tail_vma = NULL;
1707         unsigned long addr;
1708
1709         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1710         do {
1711                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1712                 mm->map_count--;
1713                 tail_vma = vma;
1714                 vma = vma->vm_next;
1715         } while (vma && vma->vm_start < end);
1716         *insertion_point = vma;
1717         tail_vma->vm_next = NULL;
1718         if (mm->unmap_area == arch_unmap_area)
1719                 addr = prev ? prev->vm_end : mm->mmap_base;
1720         else
1721                 addr = vma ?  vma->vm_start : mm->mmap_base;
1722         mm->unmap_area(mm, addr);
1723         mm->mmap_cache = NULL;          /* Kill the cache. */
1724 }
1725
1726 /*
1727  * Split a vma into two pieces at address 'addr', a new vma is allocated
1728  * either for the first part or the the tail.
1729  */
1730 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1731               unsigned long addr, int new_below)
1732 {
1733         struct mempolicy *pol;
1734         struct vm_area_struct *new;
1735
1736         if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1737                 return -EINVAL;
1738
1739         if (mm->map_count >= sysctl_max_map_count)
1740                 return -ENOMEM;
1741
1742         new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1743         if (!new)
1744                 return -ENOMEM;
1745
1746         /* most fields are the same, copy all, and then fixup */
1747         *new = *vma;
1748
1749         if (new_below)
1750                 new->vm_end = addr;
1751         else {
1752                 new->vm_start = addr;
1753                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1754         }
1755
1756         pol = mpol_copy(vma_policy(vma));
1757         if (IS_ERR(pol)) {
1758                 kmem_cache_free(vm_area_cachep, new);
1759                 return PTR_ERR(pol);
1760         }
1761         vma_set_policy(new, pol);
1762
1763         if (new->vm_file)
1764                 get_file(new->vm_file);
1765
1766         if (new->vm_ops && new->vm_ops->open)
1767                 new->vm_ops->open(new);
1768
1769         if (new_below)
1770                 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1771                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
1772         else
1773                 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1774
1775         return 0;
1776 }
1777
1778 /* Munmap is split into 2 main parts -- this part which finds
1779  * what needs doing, and the areas themselves, which do the
1780  * work.  This now handles partial unmappings.
1781  * Jeremy Fitzhardinge <jeremy@goop.org>
1782  */
1783 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1784 {
1785         unsigned long end;
1786         struct vm_area_struct *vma, *prev, *last;
1787
1788         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1789                 return -EINVAL;
1790
1791         if ((len = PAGE_ALIGN(len)) == 0)
1792                 return -EINVAL;
1793
1794         /* Find the first overlapping VMA */
1795         vma = find_vma_prev(mm, start, &prev);
1796         if (!vma)
1797                 return 0;
1798         /* we have  start < vma->vm_end  */
1799
1800         /* if it doesn't overlap, we have nothing.. */
1801         end = start + len;
1802         if (vma->vm_start >= end)
1803                 return 0;
1804
1805         /*
1806          * If we need to split any vma, do it now to save pain later.
1807          *
1808          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1809          * unmapped vm_area_struct will remain in use: so lower split_vma
1810          * places tmp vma above, and higher split_vma places tmp vma below.
1811          */
1812         if (start > vma->vm_start) {
1813                 int error = split_vma(mm, vma, start, 0);
1814                 if (error)
1815                         return error;
1816                 prev = vma;
1817         }
1818
1819         /* Does it split the last one? */
1820         last = find_vma(mm, end);
1821         if (last && end > last->vm_start) {
1822                 int error = split_vma(mm, last, end, 1);
1823                 if (error)
1824                         return error;
1825         }
1826         vma = prev? prev->vm_next: mm->mmap;
1827
1828         /*
1829          * Remove the vma's, and unmap the actual pages
1830          */
1831         detach_vmas_to_be_unmapped(mm, vma, prev, end);
1832         unmap_region(mm, vma, prev, start, end);
1833
1834         /* Fix up all other VM information */
1835         remove_vma_list(mm, vma);
1836
1837         return 0;
1838 }
1839
1840 EXPORT_SYMBOL(do_munmap);
1841
1842 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1843 {
1844         int ret;
1845         struct mm_struct *mm = current->mm;
1846
1847         profile_munmap(addr);
1848
1849         down_write(&mm->mmap_sem);
1850         ret = do_munmap(mm, addr, len);
1851         up_write(&mm->mmap_sem);
1852         return ret;
1853 }
1854
1855 static inline void verify_mm_writelocked(struct mm_struct *mm)
1856 {
1857 #ifdef CONFIG_DEBUG_VM
1858         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1859                 WARN_ON(1);
1860                 up_read(&mm->mmap_sem);
1861         }
1862 #endif
1863 }
1864
1865 /*
1866  *  this is really a simplified "do_mmap".  it only handles
1867  *  anonymous maps.  eventually we may be able to do some
1868  *  brk-specific accounting here.
1869  */
1870 unsigned long do_brk(unsigned long addr, unsigned long len)
1871 {
1872         struct mm_struct * mm = current->mm;
1873         struct vm_area_struct * vma, * prev;
1874         unsigned long flags;
1875         struct rb_node ** rb_link, * rb_parent;
1876         pgoff_t pgoff = addr >> PAGE_SHIFT;
1877         int error;
1878
1879         len = PAGE_ALIGN(len);
1880         if (!len)
1881                 return addr;
1882
1883         if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1884                 return -EINVAL;
1885
1886         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1887
1888         error = arch_mmap_check(addr, len, flags);
1889         if (error)
1890                 return error;
1891
1892         /*
1893          * mlock MCL_FUTURE?
1894          */
1895         if (mm->def_flags & VM_LOCKED) {
1896                 unsigned long locked, lock_limit;
1897                 locked = len >> PAGE_SHIFT;
1898                 locked += mm->locked_vm;
1899                 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1900                 lock_limit >>= PAGE_SHIFT;
1901                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1902                         return -EAGAIN;
1903         }
1904
1905         /*
1906          * mm->mmap_sem is required to protect against another thread
1907          * changing the mappings in case we sleep.
1908          */
1909         verify_mm_writelocked(mm);
1910
1911         /*
1912          * Clear old maps.  this also does some error checking for us
1913          */
1914  munmap_back:
1915         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1916         if (vma && vma->vm_start < addr + len) {
1917                 if (do_munmap(mm, addr, len))
1918                         return -ENOMEM;
1919                 goto munmap_back;
1920         }
1921
1922         /* Check against address space limits *after* clearing old maps... */
1923         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1924                 return -ENOMEM;
1925
1926         if (mm->map_count > sysctl_max_map_count)
1927                 return -ENOMEM;
1928
1929         if (security_vm_enough_memory(len >> PAGE_SHIFT))
1930                 return -ENOMEM;
1931
1932         /* Can we just expand an old private anonymous mapping? */
1933         if (vma_merge(mm, prev, addr, addr + len, flags,
1934                                         NULL, NULL, pgoff, NULL))
1935                 goto out;
1936
1937         /*
1938          * create a vma struct for an anonymous mapping
1939          */
1940         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1941         if (!vma) {
1942                 vm_unacct_memory(len >> PAGE_SHIFT);
1943                 return -ENOMEM;
1944         }
1945
1946         vma->vm_mm = mm;
1947         vma->vm_start = addr;
1948         vma->vm_end = addr + len;
1949         vma->vm_pgoff = pgoff;
1950         vma->vm_flags = flags;
1951         vma->vm_page_prot = protection_map[flags &
1952                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
1953         vma_link(mm, vma, prev, rb_link, rb_parent);
1954 out:
1955         mm->total_vm += len >> PAGE_SHIFT;
1956         if (flags & VM_LOCKED) {
1957                 mm->locked_vm += len >> PAGE_SHIFT;
1958                 make_pages_present(addr, addr + len);
1959         }
1960         return addr;
1961 }
1962
1963 EXPORT_SYMBOL(do_brk);
1964
1965 /* Release all mmaps. */
1966 void exit_mmap(struct mm_struct *mm)
1967 {
1968         struct mmu_gather *tlb;
1969         struct vm_area_struct *vma = mm->mmap;
1970         unsigned long nr_accounted = 0;
1971         unsigned long end;
1972
1973         lru_add_drain();
1974         flush_cache_mm(mm);
1975         tlb = tlb_gather_mmu(mm, 1);
1976         /* Don't update_hiwater_rss(mm) here, do_exit already did */
1977         /* Use -1 here to ensure all VMAs in the mm are unmapped */
1978         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
1979         vm_unacct_memory(nr_accounted);
1980         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
1981         tlb_finish_mmu(tlb, 0, end);
1982
1983         /*
1984          * Walk the list again, actually closing and freeing it,
1985          * with preemption enabled, without holding any MM locks.
1986          */
1987         while (vma)
1988                 vma = remove_vma(vma);
1989
1990         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
1991 }
1992
1993 /* Insert vm structure into process list sorted by address
1994  * and into the inode's i_mmap tree.  If vm_file is non-NULL
1995  * then i_mmap_lock is taken here.
1996  */
1997 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
1998 {
1999         struct vm_area_struct * __vma, * prev;
2000         struct rb_node ** rb_link, * rb_parent;
2001
2002         /*
2003          * The vm_pgoff of a purely anonymous vma should be irrelevant
2004          * until its first write fault, when page's anon_vma and index
2005          * are set.  But now set the vm_pgoff it will almost certainly
2006          * end up with (unless mremap moves it elsewhere before that
2007          * first wfault), so /proc/pid/maps tells a consistent story.
2008          *
2009          * By setting it to reflect the virtual start address of the
2010          * vma, merges and splits can happen in a seamless way, just
2011          * using the existing file pgoff checks and manipulations.
2012          * Similarly in do_mmap_pgoff and in do_brk.
2013          */
2014         if (!vma->vm_file) {
2015                 BUG_ON(vma->anon_vma);
2016                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2017         }
2018         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2019         if (__vma && __vma->vm_start < vma->vm_end)
2020                 return -ENOMEM;
2021         if ((vma->vm_flags & VM_ACCOUNT) &&
2022              security_vm_enough_memory(vma_pages(vma)))
2023                 return -ENOMEM;
2024         vma_link(mm, vma, prev, rb_link, rb_parent);
2025         return 0;
2026 }
2027
2028 /*
2029  * Copy the vma structure to a new location in the same mm,
2030  * prior to moving page table entries, to effect an mremap move.
2031  */
2032 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2033         unsigned long addr, unsigned long len, pgoff_t pgoff)
2034 {
2035         struct vm_area_struct *vma = *vmap;
2036         unsigned long vma_start = vma->vm_start;
2037         struct mm_struct *mm = vma->vm_mm;
2038         struct vm_area_struct *new_vma, *prev;
2039         struct rb_node **rb_link, *rb_parent;
2040         struct mempolicy *pol;
2041
2042         /*
2043          * If anonymous vma has not yet been faulted, update new pgoff
2044          * to match new location, to increase its chance of merging.
2045          */
2046         if (!vma->vm_file && !vma->anon_vma)
2047                 pgoff = addr >> PAGE_SHIFT;
2048
2049         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2050         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2051                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2052         if (new_vma) {
2053                 /*
2054                  * Source vma may have been merged into new_vma
2055                  */
2056                 if (vma_start >= new_vma->vm_start &&
2057                     vma_start < new_vma->vm_end)
2058                         *vmap = new_vma;
2059         } else {
2060                 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
2061                 if (new_vma) {
2062                         *new_vma = *vma;
2063                         pol = mpol_copy(vma_policy(vma));
2064                         if (IS_ERR(pol)) {
2065                                 kmem_cache_free(vm_area_cachep, new_vma);
2066                                 return NULL;
2067                         }
2068                         vma_set_policy(new_vma, pol);
2069                         new_vma->vm_start = addr;
2070                         new_vma->vm_end = addr + len;
2071                         new_vma->vm_pgoff = pgoff;
2072                         if (new_vma->vm_file)
2073                                 get_file(new_vma->vm_file);
2074                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2075                                 new_vma->vm_ops->open(new_vma);
2076                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2077                 }
2078         }
2079         return new_vma;
2080 }
2081
2082 /*
2083  * Return true if the calling process may expand its vm space by the passed
2084  * number of pages
2085  */
2086 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2087 {
2088         unsigned long cur = mm->total_vm;       /* pages */
2089         unsigned long lim;
2090
2091         lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2092
2093         if (cur + npages > lim)
2094                 return 0;
2095         return 1;
2096 }