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