fed up with those stupid warnings
[mmotm.git] / mm / mmap.c
blob2a81f9761cebb469ddb646a95591ef6dd7cf0587
1 /*
2 * mm/mmap.c
4 * Written by obz.
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 */
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
11 #include <linux/mm.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
20 #include <linux/fs.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/ima.h>
24 #include <linux/hugetlb.h>
25 #include <linux/profile.h>
26 #include <linux/module.h>
27 #include <linux/mount.h>
28 #include <linux/mempolicy.h>
29 #include <linux/rmap.h>
30 #include <linux/mmu_notifier.h>
31 #include <linux/perf_event.h>
33 #include <asm/uaccess.h>
34 #include <asm/cacheflush.h>
35 #include <asm/tlb.h>
36 #include <asm/mmu_context.h>
38 #include "internal.h"
40 #ifndef arch_mmap_check
41 #define arch_mmap_check(addr, len, flags) (0)
42 #endif
44 #ifndef arch_rebalance_pgtables
45 #define arch_rebalance_pgtables(addr, len) (addr)
46 #endif
48 static void unmap_region(struct mm_struct *mm,
49 struct vm_area_struct *vma, struct vm_area_struct *prev,
50 unsigned long start, unsigned long end);
53 * WARNING: the debugging will use recursive algorithms so never enable this
54 * unless you know what you are doing.
56 #undef DEBUG_MM_RB
58 /* description of effects of mapping type and prot in current implementation.
59 * this is due to the limited x86 page protection hardware. The expected
60 * behavior is in parens:
62 * map_type prot
63 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
64 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
65 * w: (no) no w: (no) no w: (yes) yes w: (no) no
66 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
68 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
69 * w: (no) no w: (no) no w: (copy) copy w: (no) no
70 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
73 pgprot_t protection_map[16] = {
74 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
75 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
78 pgprot_t vm_get_page_prot(unsigned long vm_flags)
80 return __pgprot(pgprot_val(protection_map[vm_flags &
81 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
82 pgprot_val(arch_vm_get_page_prot(vm_flags)));
84 EXPORT_SYMBOL(vm_get_page_prot);
86 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
87 int sysctl_overcommit_ratio = 50; /* default is 50% */
88 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
89 struct percpu_counter vm_committed_as;
92 * Check that a process has enough memory to allocate a new virtual
93 * mapping. 0 means there is enough memory for the allocation to
94 * succeed and -ENOMEM implies there is not.
96 * We currently support three overcommit policies, which are set via the
97 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
99 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
100 * Additional code 2002 Jul 20 by Robert Love.
102 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
104 * Note this is a helper function intended to be used by LSMs which
105 * wish to use this logic.
107 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
109 unsigned long free, allowed;
111 vm_acct_memory(pages);
114 * Sometimes we want to use more memory than we have
116 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
117 return 0;
119 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
120 unsigned long n;
122 free = global_page_state(NR_FILE_PAGES);
123 free += nr_swap_pages;
126 * Any slabs which are created with the
127 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
128 * which are reclaimable, under pressure. The dentry
129 * cache and most inode caches should fall into this
131 free += global_page_state(NR_SLAB_RECLAIMABLE);
134 * Leave the last 3% for root
136 if (!cap_sys_admin)
137 free -= free / 32;
139 if (free > pages)
140 return 0;
143 * nr_free_pages() is very expensive on large systems,
144 * only call if we're about to fail.
146 n = nr_free_pages();
149 * Leave reserved pages. The pages are not for anonymous pages.
151 if (n <= totalreserve_pages)
152 goto error;
153 else
154 n -= totalreserve_pages;
157 * Leave the last 3% for root
159 if (!cap_sys_admin)
160 n -= n / 32;
161 free += n;
163 if (free > pages)
164 return 0;
166 goto error;
169 allowed = (totalram_pages - hugetlb_total_pages())
170 * sysctl_overcommit_ratio / 100;
172 * Leave the last 3% for root
174 if (!cap_sys_admin)
175 allowed -= allowed / 32;
176 allowed += total_swap_pages;
178 /* Don't let a single process grow too big:
179 leave 3% of the size of this process for other processes */
180 if (mm)
181 allowed -= mm->total_vm / 32;
183 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
184 return 0;
185 error:
186 vm_unacct_memory(pages);
188 return -ENOMEM;
192 * Requires inode->i_mapping->i_mmap_lock
194 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
195 struct file *file, struct address_space *mapping)
197 if (vma->vm_flags & VM_DENYWRITE)
198 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
199 if (vma->vm_flags & VM_SHARED)
200 mapping->i_mmap_writable--;
202 flush_dcache_mmap_lock(mapping);
203 if (unlikely(vma->vm_flags & VM_NONLINEAR))
204 list_del_init(&vma->shared.vm_set.list);
205 else
206 vma_prio_tree_remove(vma, &mapping->i_mmap);
207 flush_dcache_mmap_unlock(mapping);
211 * Unlink a file-based vm structure from its prio_tree, to hide
212 * vma from rmap and vmtruncate before freeing its page tables.
214 void unlink_file_vma(struct vm_area_struct *vma)
216 struct file *file = vma->vm_file;
218 if (file) {
219 struct address_space *mapping = file->f_mapping;
220 spin_lock(&mapping->i_mmap_lock);
221 __remove_shared_vm_struct(vma, file, mapping);
222 spin_unlock(&mapping->i_mmap_lock);
227 * Close a vm structure and free it, returning the next.
229 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
231 struct vm_area_struct *next = vma->vm_next;
233 might_sleep();
234 if (vma->vm_ops && vma->vm_ops->close)
235 vma->vm_ops->close(vma);
236 if (vma->vm_file) {
237 fput(vma->vm_file);
238 if (vma->vm_flags & VM_EXECUTABLE)
239 removed_exe_file_vma(vma->vm_mm);
241 mpol_put(vma_policy(vma));
242 kmem_cache_free(vm_area_cachep, vma);
243 return next;
246 SYSCALL_DEFINE1(brk, unsigned long, brk)
248 unsigned long rlim, retval;
249 unsigned long newbrk, oldbrk;
250 struct mm_struct *mm = current->mm;
251 unsigned long min_brk;
253 down_write(&mm->mmap_sem);
255 #ifdef CONFIG_COMPAT_BRK
256 min_brk = mm->end_code;
257 #else
258 min_brk = mm->start_brk;
259 #endif
260 if (brk < min_brk)
261 goto out;
264 * Check against rlimit here. If this check is done later after the test
265 * of oldbrk with newbrk then it can escape the test and let the data
266 * segment grow beyond its set limit the in case where the limit is
267 * not page aligned -Ram Gupta
269 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
270 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
271 (mm->end_data - mm->start_data) > rlim)
272 goto out;
274 newbrk = PAGE_ALIGN(brk);
275 oldbrk = PAGE_ALIGN(mm->brk);
276 if (oldbrk == newbrk)
277 goto set_brk;
279 /* Always allow shrinking brk. */
280 if (brk <= mm->brk) {
281 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
282 goto set_brk;
283 goto out;
286 /* Check against existing mmap mappings. */
287 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
288 goto out;
290 /* Ok, looks good - let it rip. */
291 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
292 goto out;
293 set_brk:
294 mm->brk = brk;
295 out:
296 retval = mm->brk;
297 up_write(&mm->mmap_sem);
298 return retval;
301 #ifdef DEBUG_MM_RB
302 static int browse_rb(struct rb_root *root)
304 int i = 0, j;
305 struct rb_node *nd, *pn = NULL;
306 unsigned long prev = 0, pend = 0;
308 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
309 struct vm_area_struct *vma;
310 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
311 if (vma->vm_start < prev)
312 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
313 if (vma->vm_start < pend)
314 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
315 if (vma->vm_start > vma->vm_end)
316 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
317 i++;
318 pn = nd;
319 prev = vma->vm_start;
320 pend = vma->vm_end;
322 j = 0;
323 for (nd = pn; nd; nd = rb_prev(nd)) {
324 j++;
326 if (i != j)
327 printk("backwards %d, forwards %d\n", j, i), i = 0;
328 return i;
331 void validate_mm(struct mm_struct *mm)
333 int bug = 0;
334 int i = 0;
335 struct vm_area_struct *tmp = mm->mmap;
336 while (tmp) {
337 tmp = tmp->vm_next;
338 i++;
340 if (i != mm->map_count)
341 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
342 i = browse_rb(&mm->mm_rb);
343 if (i != mm->map_count)
344 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
345 BUG_ON(bug);
347 #else
348 #define validate_mm(mm) do { } while (0)
349 #endif
351 static struct vm_area_struct *
352 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
353 struct vm_area_struct **pprev, struct rb_node ***rb_link,
354 struct rb_node ** rb_parent)
356 struct vm_area_struct * vma;
357 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
359 __rb_link = &mm->mm_rb.rb_node;
360 rb_prev = __rb_parent = NULL;
361 vma = NULL;
363 while (*__rb_link) {
364 struct vm_area_struct *vma_tmp;
366 __rb_parent = *__rb_link;
367 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
369 if (vma_tmp->vm_end > addr) {
370 vma = vma_tmp;
371 if (vma_tmp->vm_start <= addr)
372 break;
373 __rb_link = &__rb_parent->rb_left;
374 } else {
375 rb_prev = __rb_parent;
376 __rb_link = &__rb_parent->rb_right;
380 *pprev = NULL;
381 if (rb_prev)
382 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
383 *rb_link = __rb_link;
384 *rb_parent = __rb_parent;
385 return vma;
388 static inline void
389 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
390 struct vm_area_struct *prev, struct rb_node *rb_parent)
392 if (prev) {
393 vma->vm_next = prev->vm_next;
394 prev->vm_next = vma;
395 } else {
396 mm->mmap = vma;
397 if (rb_parent)
398 vma->vm_next = rb_entry(rb_parent,
399 struct vm_area_struct, vm_rb);
400 else
401 vma->vm_next = NULL;
405 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
406 struct rb_node **rb_link, struct rb_node *rb_parent)
408 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
409 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
412 static void __vma_link_file(struct vm_area_struct *vma)
414 struct file *file;
416 file = vma->vm_file;
417 if (file) {
418 struct address_space *mapping = file->f_mapping;
420 if (vma->vm_flags & VM_DENYWRITE)
421 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
422 if (vma->vm_flags & VM_SHARED)
423 mapping->i_mmap_writable++;
425 flush_dcache_mmap_lock(mapping);
426 if (unlikely(vma->vm_flags & VM_NONLINEAR))
427 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
428 else
429 vma_prio_tree_insert(vma, &mapping->i_mmap);
430 flush_dcache_mmap_unlock(mapping);
434 static void
435 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
436 struct vm_area_struct *prev, struct rb_node **rb_link,
437 struct rb_node *rb_parent)
439 __vma_link_list(mm, vma, prev, rb_parent);
440 __vma_link_rb(mm, vma, rb_link, rb_parent);
441 __anon_vma_link(vma);
444 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
445 struct vm_area_struct *prev, struct rb_node **rb_link,
446 struct rb_node *rb_parent)
448 struct address_space *mapping = NULL;
450 if (vma->vm_file)
451 mapping = vma->vm_file->f_mapping;
453 if (mapping) {
454 spin_lock(&mapping->i_mmap_lock);
455 vma->vm_truncate_count = mapping->truncate_count;
457 anon_vma_lock(vma);
459 __vma_link(mm, vma, prev, rb_link, rb_parent);
460 __vma_link_file(vma);
462 anon_vma_unlock(vma);
463 if (mapping)
464 spin_unlock(&mapping->i_mmap_lock);
466 mm->map_count++;
467 validate_mm(mm);
471 * Helper for vma_adjust in the split_vma insert case:
472 * insert vm structure into list and rbtree and anon_vma,
473 * but it has already been inserted into prio_tree earlier.
475 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
477 struct vm_area_struct *__vma, *prev;
478 struct rb_node **rb_link, *rb_parent;
480 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
481 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
482 __vma_link(mm, vma, prev, rb_link, rb_parent);
483 mm->map_count++;
486 static inline void
487 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
488 struct vm_area_struct *prev)
490 prev->vm_next = vma->vm_next;
491 rb_erase(&vma->vm_rb, &mm->mm_rb);
492 if (mm->mmap_cache == vma)
493 mm->mmap_cache = prev;
497 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
498 * is already present in an i_mmap tree without adjusting the tree.
499 * The following helper function should be used when such adjustments
500 * are necessary. The "insert" vma (if any) is to be inserted
501 * before we drop the necessary locks.
503 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
504 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
506 struct mm_struct *mm = vma->vm_mm;
507 struct vm_area_struct *next = vma->vm_next;
508 struct vm_area_struct *importer = NULL;
509 struct address_space *mapping = NULL;
510 struct prio_tree_root *root = NULL;
511 struct file *file = vma->vm_file;
512 struct anon_vma *anon_vma = NULL;
513 long adjust_next = 0;
514 int remove_next = 0;
516 if (next && !insert) {
517 if (end >= next->vm_end) {
519 * vma expands, overlapping all the next, and
520 * perhaps the one after too (mprotect case 6).
522 again: remove_next = 1 + (end > next->vm_end);
523 end = next->vm_end;
524 anon_vma = next->anon_vma;
525 importer = vma;
526 } else if (end > next->vm_start) {
528 * vma expands, overlapping part of the next:
529 * mprotect case 5 shifting the boundary up.
531 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
532 anon_vma = next->anon_vma;
533 importer = vma;
534 } else if (end < vma->vm_end) {
536 * vma shrinks, and !insert tells it's not
537 * split_vma inserting another: so it must be
538 * mprotect case 4 shifting the boundary down.
540 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
541 anon_vma = next->anon_vma;
542 importer = next;
546 if (file) {
547 mapping = file->f_mapping;
548 if (!(vma->vm_flags & VM_NONLINEAR))
549 root = &mapping->i_mmap;
550 spin_lock(&mapping->i_mmap_lock);
551 if (importer &&
552 vma->vm_truncate_count != next->vm_truncate_count) {
554 * unmap_mapping_range might be in progress:
555 * ensure that the expanding vma is rescanned.
557 importer->vm_truncate_count = 0;
559 if (insert) {
560 insert->vm_truncate_count = vma->vm_truncate_count;
562 * Put into prio_tree now, so instantiated pages
563 * are visible to arm/parisc __flush_dcache_page
564 * throughout; but we cannot insert into address
565 * space until vma start or end is updated.
567 __vma_link_file(insert);
572 * When changing only vma->vm_end, we don't really need
573 * anon_vma lock.
575 if (vma->anon_vma && (insert || importer || start != vma->vm_start))
576 anon_vma = vma->anon_vma;
577 if (anon_vma) {
578 spin_lock(&anon_vma->lock);
580 * Easily overlooked: when mprotect shifts the boundary,
581 * make sure the expanding vma has anon_vma set if the
582 * shrinking vma had, to cover any anon pages imported.
584 if (importer && !importer->anon_vma) {
585 importer->anon_vma = anon_vma;
586 __anon_vma_link(importer);
590 if (root) {
591 flush_dcache_mmap_lock(mapping);
592 vma_prio_tree_remove(vma, root);
593 if (adjust_next)
594 vma_prio_tree_remove(next, root);
597 vma->vm_start = start;
598 vma->vm_end = end;
599 vma->vm_pgoff = pgoff;
600 if (adjust_next) {
601 next->vm_start += adjust_next << PAGE_SHIFT;
602 next->vm_pgoff += adjust_next;
605 if (root) {
606 if (adjust_next)
607 vma_prio_tree_insert(next, root);
608 vma_prio_tree_insert(vma, root);
609 flush_dcache_mmap_unlock(mapping);
612 if (remove_next) {
614 * vma_merge has merged next into vma, and needs
615 * us to remove next before dropping the locks.
617 __vma_unlink(mm, next, vma);
618 if (file)
619 __remove_shared_vm_struct(next, file, mapping);
620 if (next->anon_vma)
621 __anon_vma_merge(vma, next);
622 } else if (insert) {
624 * split_vma has split insert from vma, and needs
625 * us to insert it before dropping the locks
626 * (it may either follow vma or precede it).
628 __insert_vm_struct(mm, insert);
631 if (anon_vma)
632 spin_unlock(&anon_vma->lock);
633 if (mapping)
634 spin_unlock(&mapping->i_mmap_lock);
636 if (remove_next) {
637 if (file) {
638 fput(file);
639 if (next->vm_flags & VM_EXECUTABLE)
640 removed_exe_file_vma(mm);
642 mm->map_count--;
643 mpol_put(vma_policy(next));
644 kmem_cache_free(vm_area_cachep, next);
646 * In mprotect's case 6 (see comments on vma_merge),
647 * we must remove another next too. It would clutter
648 * up the code too much to do both in one go.
650 if (remove_next == 2) {
651 next = vma->vm_next;
652 goto again;
656 validate_mm(mm);
660 * If the vma has a ->close operation then the driver probably needs to release
661 * per-vma resources, so we don't attempt to merge those.
663 static inline int is_mergeable_vma(struct vm_area_struct *vma,
664 struct file *file, unsigned long vm_flags)
666 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
667 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
668 return 0;
669 if (vma->vm_file != file)
670 return 0;
671 if (vma->vm_ops && vma->vm_ops->close)
672 return 0;
673 return 1;
676 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
677 struct anon_vma *anon_vma2)
679 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
683 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
684 * in front of (at a lower virtual address and file offset than) the vma.
686 * We cannot merge two vmas if they have differently assigned (non-NULL)
687 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
689 * We don't check here for the merged mmap wrapping around the end of pagecache
690 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
691 * wrap, nor mmaps which cover the final page at index -1UL.
693 static int
694 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
695 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
697 if (is_mergeable_vma(vma, file, vm_flags) &&
698 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
699 if (vma->vm_pgoff == vm_pgoff)
700 return 1;
702 return 0;
706 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
707 * beyond (at a higher virtual address and file offset than) the vma.
709 * We cannot merge two vmas if they have differently assigned (non-NULL)
710 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
712 static int
713 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
714 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
716 if (is_mergeable_vma(vma, file, vm_flags) &&
717 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
718 pgoff_t vm_pglen;
719 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
720 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
721 return 1;
723 return 0;
727 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
728 * whether that can be merged with its predecessor or its successor.
729 * Or both (it neatly fills a hole).
731 * In most cases - when called for mmap, brk or mremap - [addr,end) is
732 * certain not to be mapped by the time vma_merge is called; but when
733 * called for mprotect, it is certain to be already mapped (either at
734 * an offset within prev, or at the start of next), and the flags of
735 * this area are about to be changed to vm_flags - and the no-change
736 * case has already been eliminated.
738 * The following mprotect cases have to be considered, where AAAA is
739 * the area passed down from mprotect_fixup, never extending beyond one
740 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
742 * AAAA AAAA AAAA AAAA
743 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
744 * cannot merge might become might become might become
745 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
746 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
747 * mremap move: PPPPNNNNNNNN 8
748 * AAAA
749 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
750 * might become case 1 below case 2 below case 3 below
752 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
753 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
755 struct vm_area_struct *vma_merge(struct mm_struct *mm,
756 struct vm_area_struct *prev, unsigned long addr,
757 unsigned long end, unsigned long vm_flags,
758 struct anon_vma *anon_vma, struct file *file,
759 pgoff_t pgoff, struct mempolicy *policy)
761 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
762 struct vm_area_struct *area, *next;
765 * We later require that vma->vm_flags == vm_flags,
766 * so this tests vma->vm_flags & VM_SPECIAL, too.
768 if (vm_flags & VM_SPECIAL)
769 return NULL;
771 if (prev)
772 next = prev->vm_next;
773 else
774 next = mm->mmap;
775 area = next;
776 if (next && next->vm_end == end) /* cases 6, 7, 8 */
777 next = next->vm_next;
780 * Can it merge with the predecessor?
782 if (prev && prev->vm_end == addr &&
783 mpol_equal(vma_policy(prev), policy) &&
784 can_vma_merge_after(prev, vm_flags,
785 anon_vma, file, pgoff)) {
787 * OK, it can. Can we now merge in the successor as well?
789 if (next && end == next->vm_start &&
790 mpol_equal(policy, vma_policy(next)) &&
791 can_vma_merge_before(next, vm_flags,
792 anon_vma, file, pgoff+pglen) &&
793 is_mergeable_anon_vma(prev->anon_vma,
794 next->anon_vma)) {
795 /* cases 1, 6 */
796 vma_adjust(prev, prev->vm_start,
797 next->vm_end, prev->vm_pgoff, NULL);
798 } else /* cases 2, 5, 7 */
799 vma_adjust(prev, prev->vm_start,
800 end, prev->vm_pgoff, NULL);
801 return prev;
805 * Can this new request be merged in front of next?
807 if (next && end == next->vm_start &&
808 mpol_equal(policy, vma_policy(next)) &&
809 can_vma_merge_before(next, vm_flags,
810 anon_vma, file, pgoff+pglen)) {
811 if (prev && addr < prev->vm_end) /* case 4 */
812 vma_adjust(prev, prev->vm_start,
813 addr, prev->vm_pgoff, NULL);
814 else /* cases 3, 8 */
815 vma_adjust(area, addr, next->vm_end,
816 next->vm_pgoff - pglen, NULL);
817 return area;
820 return NULL;
824 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
825 * neighbouring vmas for a suitable anon_vma, before it goes off
826 * to allocate a new anon_vma. It checks because a repetitive
827 * sequence of mprotects and faults may otherwise lead to distinct
828 * anon_vmas being allocated, preventing vma merge in subsequent
829 * mprotect.
831 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
833 struct vm_area_struct *near;
834 unsigned long vm_flags;
836 near = vma->vm_next;
837 if (!near)
838 goto try_prev;
841 * Since only mprotect tries to remerge vmas, match flags
842 * which might be mprotected into each other later on.
843 * Neither mlock nor madvise tries to remerge at present,
844 * so leave their flags as obstructing a merge.
846 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
847 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
849 if (near->anon_vma && vma->vm_end == near->vm_start &&
850 mpol_equal(vma_policy(vma), vma_policy(near)) &&
851 can_vma_merge_before(near, vm_flags,
852 NULL, vma->vm_file, vma->vm_pgoff +
853 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
854 return near->anon_vma;
855 try_prev:
857 * It is potentially slow to have to call find_vma_prev here.
858 * But it's only on the first write fault on the vma, not
859 * every time, and we could devise a way to avoid it later
860 * (e.g. stash info in next's anon_vma_node when assigning
861 * an anon_vma, or when trying vma_merge). Another time.
863 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
864 if (!near)
865 goto none;
867 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
868 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
870 if (near->anon_vma && near->vm_end == vma->vm_start &&
871 mpol_equal(vma_policy(near), vma_policy(vma)) &&
872 can_vma_merge_after(near, vm_flags,
873 NULL, vma->vm_file, vma->vm_pgoff))
874 return near->anon_vma;
875 none:
877 * There's no absolute need to look only at touching neighbours:
878 * we could search further afield for "compatible" anon_vmas.
879 * But it would probably just be a waste of time searching,
880 * or lead to too many vmas hanging off the same anon_vma.
881 * We're trying to allow mprotect remerging later on,
882 * not trying to minimize memory used for anon_vmas.
884 return NULL;
887 #ifdef CONFIG_PROC_FS
888 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
889 struct file *file, long pages)
891 const unsigned long stack_flags
892 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
894 if (file) {
895 mm->shared_vm += pages;
896 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
897 mm->exec_vm += pages;
898 } else if (flags & stack_flags)
899 mm->stack_vm += pages;
900 if (flags & (VM_RESERVED|VM_IO))
901 mm->reserved_vm += pages;
903 #endif /* CONFIG_PROC_FS */
906 * The caller must hold down_write(&current->mm->mmap_sem).
909 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
910 unsigned long len, unsigned long prot,
911 unsigned long flags, unsigned long pgoff)
913 struct mm_struct * mm = current->mm;
914 struct inode *inode;
915 unsigned int vm_flags;
916 int error;
917 unsigned long reqprot = prot;
920 * Does the application expect PROT_READ to imply PROT_EXEC?
922 * (the exception is when the underlying filesystem is noexec
923 * mounted, in which case we dont add PROT_EXEC.)
925 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
926 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
927 prot |= PROT_EXEC;
929 if (!len)
930 return -EINVAL;
932 if (!(flags & MAP_FIXED))
933 addr = round_hint_to_min(addr);
935 error = arch_mmap_check(addr, len, flags);
936 if (error)
937 return error;
939 /* Careful about overflows.. */
940 len = PAGE_ALIGN(len);
941 if (!len || len > TASK_SIZE)
942 return -ENOMEM;
944 /* offset overflow? */
945 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
946 return -EOVERFLOW;
948 /* Too many mappings? */
949 if (mm->map_count > sysctl_max_map_count)
950 return -ENOMEM;
952 if (flags & MAP_HUGETLB) {
953 struct user_struct *user = NULL;
954 if (file)
955 return -EINVAL;
958 * VM_NORESERVE is used because the reservations will be
959 * taken when vm_ops->mmap() is called
960 * A dummy user value is used because we are not locking
961 * memory so no accounting is necessary
963 len = ALIGN(len, huge_page_size(&default_hstate));
964 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
965 &user, HUGETLB_ANONHUGE_INODE);
966 if (IS_ERR(file))
967 return PTR_ERR(file);
970 /* Obtain the address to map to. we verify (or select) it and ensure
971 * that it represents a valid section of the address space.
973 addr = get_unmapped_area(file, addr, len, pgoff, flags);
974 if (addr & ~PAGE_MASK)
975 return addr;
977 /* Do simple checking here so the lower-level routines won't have
978 * to. we assume access permissions have been handled by the open
979 * of the memory object, so we don't do any here.
981 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
982 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
984 if (flags & MAP_LOCKED)
985 if (!can_do_mlock())
986 return -EPERM;
988 /* mlock MCL_FUTURE? */
989 if (vm_flags & VM_LOCKED) {
990 unsigned long locked, lock_limit;
991 locked = len >> PAGE_SHIFT;
992 locked += mm->locked_vm;
993 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
994 lock_limit >>= PAGE_SHIFT;
995 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
996 return -EAGAIN;
999 inode = file ? file->f_path.dentry->d_inode : NULL;
1001 if (file) {
1002 switch (flags & MAP_TYPE) {
1003 case MAP_SHARED:
1004 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1005 return -EACCES;
1008 * Make sure we don't allow writing to an append-only
1009 * file..
1011 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1012 return -EACCES;
1015 * Make sure there are no mandatory locks on the file.
1017 if (locks_verify_locked(inode))
1018 return -EAGAIN;
1020 vm_flags |= VM_SHARED | VM_MAYSHARE;
1021 if (!(file->f_mode & FMODE_WRITE))
1022 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1024 /* fall through */
1025 case MAP_PRIVATE:
1026 if (!(file->f_mode & FMODE_READ))
1027 return -EACCES;
1028 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1029 if (vm_flags & VM_EXEC)
1030 return -EPERM;
1031 vm_flags &= ~VM_MAYEXEC;
1034 if (!file->f_op || !file->f_op->mmap)
1035 return -ENODEV;
1036 break;
1038 default:
1039 return -EINVAL;
1041 } else {
1042 switch (flags & MAP_TYPE) {
1043 case MAP_SHARED:
1045 * Ignore pgoff.
1047 pgoff = 0;
1048 vm_flags |= VM_SHARED | VM_MAYSHARE;
1049 break;
1050 case MAP_PRIVATE:
1052 * Set pgoff according to addr for anon_vma.
1054 pgoff = addr >> PAGE_SHIFT;
1055 break;
1056 default:
1057 return -EINVAL;
1061 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1062 if (error)
1063 return error;
1064 error = ima_file_mmap(file, prot);
1065 if (error)
1066 return error;
1068 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1070 EXPORT_SYMBOL(do_mmap_pgoff);
1073 * Some shared mappigns will want the pages marked read-only
1074 * to track write events. If so, we'll downgrade vm_page_prot
1075 * to the private version (using protection_map[] without the
1076 * VM_SHARED bit).
1078 int vma_wants_writenotify(struct vm_area_struct *vma)
1080 unsigned int vm_flags = vma->vm_flags;
1082 /* If it was private or non-writable, the write bit is already clear */
1083 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1084 return 0;
1086 /* The backer wishes to know when pages are first written to? */
1087 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1088 return 1;
1090 /* The open routine did something to the protections already? */
1091 if (pgprot_val(vma->vm_page_prot) !=
1092 pgprot_val(vm_get_page_prot(vm_flags)))
1093 return 0;
1095 /* Specialty mapping? */
1096 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1097 return 0;
1099 /* Can the mapping track the dirty pages? */
1100 return vma->vm_file && vma->vm_file->f_mapping &&
1101 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1105 * We account for memory if it's a private writeable mapping,
1106 * not hugepages and VM_NORESERVE wasn't set.
1108 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1111 * hugetlb has its own accounting separate from the core VM
1112 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1114 if (file && is_file_hugepages(file))
1115 return 0;
1117 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1120 unsigned long mmap_region(struct file *file, unsigned long addr,
1121 unsigned long len, unsigned long flags,
1122 unsigned int vm_flags, unsigned long pgoff)
1124 struct mm_struct *mm = current->mm;
1125 struct vm_area_struct *vma, *prev;
1126 int correct_wcount = 0;
1127 int error;
1128 struct rb_node **rb_link, *rb_parent;
1129 unsigned long charged = 0;
1130 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1132 /* Clear old maps */
1133 error = -ENOMEM;
1134 munmap_back:
1135 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1136 if (vma && vma->vm_start < addr + len) {
1137 if (do_munmap(mm, addr, len))
1138 return -ENOMEM;
1139 goto munmap_back;
1142 /* Check against address space limit. */
1143 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1144 return -ENOMEM;
1147 * Set 'VM_NORESERVE' if we should not account for the
1148 * memory use of this mapping.
1150 if ((flags & MAP_NORESERVE)) {
1151 /* We honor MAP_NORESERVE if allowed to overcommit */
1152 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1153 vm_flags |= VM_NORESERVE;
1155 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1156 if (file && is_file_hugepages(file))
1157 vm_flags |= VM_NORESERVE;
1161 * Private writable mapping: check memory availability
1163 if (accountable_mapping(file, vm_flags)) {
1164 charged = len >> PAGE_SHIFT;
1165 if (security_vm_enough_memory(charged))
1166 return -ENOMEM;
1167 vm_flags |= VM_ACCOUNT;
1171 * Can we just expand an old mapping?
1173 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1174 if (vma)
1175 goto out;
1178 * Determine the object being mapped and call the appropriate
1179 * specific mapper. the address has already been validated, but
1180 * not unmapped, but the maps are removed from the list.
1182 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1183 if (!vma) {
1184 error = -ENOMEM;
1185 goto unacct_error;
1188 vma->vm_mm = mm;
1189 vma->vm_start = addr;
1190 vma->vm_end = addr + len;
1191 vma->vm_flags = vm_flags;
1192 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1193 vma->vm_pgoff = pgoff;
1195 if (file) {
1196 error = -EINVAL;
1197 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1198 goto free_vma;
1199 if (vm_flags & VM_DENYWRITE) {
1200 error = deny_write_access(file);
1201 if (error)
1202 goto free_vma;
1203 correct_wcount = 1;
1205 vma->vm_file = file;
1206 get_file(file);
1207 error = file->f_op->mmap(file, vma);
1208 if (error)
1209 goto unmap_and_free_vma;
1210 if (vm_flags & VM_EXECUTABLE)
1211 added_exe_file_vma(mm);
1213 /* Can addr have changed??
1215 * Answer: Yes, several device drivers can do it in their
1216 * f_op->mmap method. -DaveM
1218 addr = vma->vm_start;
1219 pgoff = vma->vm_pgoff;
1220 vm_flags = vma->vm_flags;
1221 } else if (vm_flags & VM_SHARED) {
1222 error = shmem_zero_setup(vma);
1223 if (error)
1224 goto free_vma;
1227 if (vma_wants_writenotify(vma))
1228 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1230 vma_link(mm, vma, prev, rb_link, rb_parent);
1231 file = vma->vm_file;
1233 /* Once vma denies write, undo our temporary denial count */
1234 if (correct_wcount)
1235 atomic_inc(&inode->i_writecount);
1236 out:
1237 perf_event_mmap(vma);
1239 mm->total_vm += len >> PAGE_SHIFT;
1240 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1241 if (vm_flags & VM_LOCKED) {
1243 * makes pages present; downgrades, drops, reacquires mmap_sem
1245 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
1246 if (nr_pages < 0)
1247 return nr_pages; /* vma gone! */
1248 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
1249 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1250 make_pages_present(addr, addr + len);
1251 return addr;
1253 unmap_and_free_vma:
1254 if (correct_wcount)
1255 atomic_inc(&inode->i_writecount);
1256 vma->vm_file = NULL;
1257 fput(file);
1259 /* Undo any partial mapping done by a device driver. */
1260 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1261 charged = 0;
1262 free_vma:
1263 kmem_cache_free(vm_area_cachep, vma);
1264 unacct_error:
1265 if (charged)
1266 vm_unacct_memory(charged);
1267 return error;
1270 /* Get an address range which is currently unmapped.
1271 * For shmat() with addr=0.
1273 * Ugly calling convention alert:
1274 * Return value with the low bits set means error value,
1275 * ie
1276 * if (ret & ~PAGE_MASK)
1277 * error = ret;
1279 * This function "knows" that -ENOMEM has the bits set.
1281 #ifndef HAVE_ARCH_UNMAPPED_AREA
1282 unsigned long
1283 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1284 unsigned long len, unsigned long pgoff, unsigned long flags)
1286 struct mm_struct *mm = current->mm;
1287 struct vm_area_struct *vma;
1288 unsigned long start_addr;
1290 if (len > TASK_SIZE)
1291 return -ENOMEM;
1293 if (flags & MAP_FIXED)
1294 return addr;
1296 if (addr) {
1297 addr = PAGE_ALIGN(addr);
1298 vma = find_vma(mm, addr);
1299 if (TASK_SIZE - len >= addr &&
1300 (!vma || addr + len <= vma->vm_start))
1301 return addr;
1303 if (len > mm->cached_hole_size) {
1304 start_addr = addr = mm->free_area_cache;
1305 } else {
1306 start_addr = addr = TASK_UNMAPPED_BASE;
1307 mm->cached_hole_size = 0;
1310 full_search:
1311 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1312 /* At this point: (!vma || addr < vma->vm_end). */
1313 if (TASK_SIZE - len < addr) {
1315 * Start a new search - just in case we missed
1316 * some holes.
1318 if (start_addr != TASK_UNMAPPED_BASE) {
1319 addr = TASK_UNMAPPED_BASE;
1320 start_addr = addr;
1321 mm->cached_hole_size = 0;
1322 goto full_search;
1324 return -ENOMEM;
1326 if (!vma || addr + len <= vma->vm_start) {
1328 * Remember the place where we stopped the search:
1330 mm->free_area_cache = addr + len;
1331 return addr;
1333 if (addr + mm->cached_hole_size < vma->vm_start)
1334 mm->cached_hole_size = vma->vm_start - addr;
1335 addr = vma->vm_end;
1338 #endif
1340 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1343 * Is this a new hole at the lowest possible address?
1345 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1346 mm->free_area_cache = addr;
1347 mm->cached_hole_size = ~0UL;
1352 * This mmap-allocator allocates new areas top-down from below the
1353 * stack's low limit (the base):
1355 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1356 unsigned long
1357 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1358 const unsigned long len, const unsigned long pgoff,
1359 const unsigned long flags)
1361 struct vm_area_struct *vma;
1362 struct mm_struct *mm = current->mm;
1363 unsigned long addr = addr0;
1365 /* requested length too big for entire address space */
1366 if (len > TASK_SIZE)
1367 return -ENOMEM;
1369 if (flags & MAP_FIXED)
1370 return addr;
1372 /* requesting a specific address */
1373 if (addr) {
1374 addr = PAGE_ALIGN(addr);
1375 vma = find_vma(mm, addr);
1376 if (TASK_SIZE - len >= addr &&
1377 (!vma || addr + len <= vma->vm_start))
1378 return addr;
1381 /* check if free_area_cache is useful for us */
1382 if (len <= mm->cached_hole_size) {
1383 mm->cached_hole_size = 0;
1384 mm->free_area_cache = mm->mmap_base;
1387 /* either no address requested or can't fit in requested address hole */
1388 addr = mm->free_area_cache;
1390 /* make sure it can fit in the remaining address space */
1391 if (addr > len) {
1392 vma = find_vma(mm, addr-len);
1393 if (!vma || addr <= vma->vm_start)
1394 /* remember the address as a hint for next time */
1395 return (mm->free_area_cache = addr-len);
1398 if (mm->mmap_base < len)
1399 goto bottomup;
1401 addr = mm->mmap_base-len;
1403 do {
1405 * Lookup failure means no vma is above this address,
1406 * else if new region fits below vma->vm_start,
1407 * return with success:
1409 vma = find_vma(mm, addr);
1410 if (!vma || addr+len <= vma->vm_start)
1411 /* remember the address as a hint for next time */
1412 return (mm->free_area_cache = addr);
1414 /* remember the largest hole we saw so far */
1415 if (addr + mm->cached_hole_size < vma->vm_start)
1416 mm->cached_hole_size = vma->vm_start - addr;
1418 /* try just below the current vma->vm_start */
1419 addr = vma->vm_start-len;
1420 } while (len < vma->vm_start);
1422 bottomup:
1424 * A failed mmap() very likely causes application failure,
1425 * so fall back to the bottom-up function here. This scenario
1426 * can happen with large stack limits and large mmap()
1427 * allocations.
1429 mm->cached_hole_size = ~0UL;
1430 mm->free_area_cache = TASK_UNMAPPED_BASE;
1431 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1433 * Restore the topdown base:
1435 mm->free_area_cache = mm->mmap_base;
1436 mm->cached_hole_size = ~0UL;
1438 return addr;
1440 #endif
1442 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1445 * Is this a new hole at the highest possible address?
1447 if (addr > mm->free_area_cache)
1448 mm->free_area_cache = addr;
1450 /* dont allow allocations above current base */
1451 if (mm->free_area_cache > mm->mmap_base)
1452 mm->free_area_cache = mm->mmap_base;
1455 unsigned long
1456 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1457 unsigned long pgoff, unsigned long flags)
1459 unsigned long (*get_area)(struct file *, unsigned long,
1460 unsigned long, unsigned long, unsigned long);
1462 get_area = current->mm->get_unmapped_area;
1463 if (file && file->f_op && file->f_op->get_unmapped_area)
1464 get_area = file->f_op->get_unmapped_area;
1465 addr = get_area(file, addr, len, pgoff, flags);
1466 if (IS_ERR_VALUE(addr))
1467 return addr;
1469 if (addr > TASK_SIZE - len)
1470 return -ENOMEM;
1471 if (addr & ~PAGE_MASK)
1472 return -EINVAL;
1474 return arch_rebalance_pgtables(addr, len);
1477 EXPORT_SYMBOL(get_unmapped_area);
1479 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1480 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1482 struct vm_area_struct *vma = NULL;
1484 if (mm) {
1485 /* Check the cache first. */
1486 /* (Cache hit rate is typically around 35%.) */
1487 vma = mm->mmap_cache;
1488 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1489 struct rb_node * rb_node;
1491 rb_node = mm->mm_rb.rb_node;
1492 vma = NULL;
1494 while (rb_node) {
1495 struct vm_area_struct * vma_tmp;
1497 vma_tmp = rb_entry(rb_node,
1498 struct vm_area_struct, vm_rb);
1500 if (vma_tmp->vm_end > addr) {
1501 vma = vma_tmp;
1502 if (vma_tmp->vm_start <= addr)
1503 break;
1504 rb_node = rb_node->rb_left;
1505 } else
1506 rb_node = rb_node->rb_right;
1508 if (vma)
1509 mm->mmap_cache = vma;
1512 return vma;
1515 EXPORT_SYMBOL(find_vma);
1517 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1518 struct vm_area_struct *
1519 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1520 struct vm_area_struct **pprev)
1522 struct vm_area_struct *vma = NULL, *prev = NULL;
1523 struct rb_node *rb_node;
1524 if (!mm)
1525 goto out;
1527 /* Guard against addr being lower than the first VMA */
1528 vma = mm->mmap;
1530 /* Go through the RB tree quickly. */
1531 rb_node = mm->mm_rb.rb_node;
1533 while (rb_node) {
1534 struct vm_area_struct *vma_tmp;
1535 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1537 if (addr < vma_tmp->vm_end) {
1538 rb_node = rb_node->rb_left;
1539 } else {
1540 prev = vma_tmp;
1541 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1542 break;
1543 rb_node = rb_node->rb_right;
1547 out:
1548 *pprev = prev;
1549 return prev ? prev->vm_next : vma;
1553 * Verify that the stack growth is acceptable and
1554 * update accounting. This is shared with both the
1555 * grow-up and grow-down cases.
1557 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1559 struct mm_struct *mm = vma->vm_mm;
1560 struct rlimit *rlim = current->signal->rlim;
1561 unsigned long new_start;
1563 /* address space limit tests */
1564 if (!may_expand_vm(mm, grow))
1565 return -ENOMEM;
1567 /* Stack limit test */
1568 if (size > rlim[RLIMIT_STACK].rlim_cur)
1569 return -ENOMEM;
1571 /* mlock limit tests */
1572 if (vma->vm_flags & VM_LOCKED) {
1573 unsigned long locked;
1574 unsigned long limit;
1575 locked = mm->locked_vm + grow;
1576 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1577 if (locked > limit && !capable(CAP_IPC_LOCK))
1578 return -ENOMEM;
1581 /* Check to ensure the stack will not grow into a hugetlb-only region */
1582 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1583 vma->vm_end - size;
1584 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1585 return -EFAULT;
1588 * Overcommit.. This must be the final test, as it will
1589 * update security statistics.
1591 if (security_vm_enough_memory_mm(mm, grow))
1592 return -ENOMEM;
1594 /* Ok, everything looks good - let it rip */
1595 mm->total_vm += grow;
1596 if (vma->vm_flags & VM_LOCKED)
1597 mm->locked_vm += grow;
1598 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1599 return 0;
1602 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1604 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1605 * vma is the last one with address > vma->vm_end. Have to extend vma.
1607 #ifndef CONFIG_IA64
1608 static
1609 #endif
1610 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1612 int error;
1614 if (!(vma->vm_flags & VM_GROWSUP))
1615 return -EFAULT;
1618 * We must make sure the anon_vma is allocated
1619 * so that the anon_vma locking is not a noop.
1621 if (unlikely(anon_vma_prepare(vma)))
1622 return -ENOMEM;
1623 anon_vma_lock(vma);
1626 * vma->vm_start/vm_end cannot change under us because the caller
1627 * is required to hold the mmap_sem in read mode. We need the
1628 * anon_vma lock to serialize against concurrent expand_stacks.
1629 * Also guard against wrapping around to address 0.
1631 if (address < PAGE_ALIGN(address+4))
1632 address = PAGE_ALIGN(address+4);
1633 else {
1634 anon_vma_unlock(vma);
1635 return -ENOMEM;
1637 error = 0;
1639 /* Somebody else might have raced and expanded it already */
1640 if (address > vma->vm_end) {
1641 unsigned long size, grow;
1643 size = address - vma->vm_start;
1644 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1646 error = acct_stack_growth(vma, size, grow);
1647 if (!error)
1648 vma->vm_end = address;
1650 anon_vma_unlock(vma);
1651 return error;
1653 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1656 * vma is the first one with address < vma->vm_start. Have to extend vma.
1658 static int expand_downwards(struct vm_area_struct *vma,
1659 unsigned long address)
1661 int error;
1664 * We must make sure the anon_vma is allocated
1665 * so that the anon_vma locking is not a noop.
1667 if (unlikely(anon_vma_prepare(vma)))
1668 return -ENOMEM;
1670 address &= PAGE_MASK;
1671 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1672 if (error)
1673 return error;
1675 anon_vma_lock(vma);
1678 * vma->vm_start/vm_end cannot change under us because the caller
1679 * is required to hold the mmap_sem in read mode. We need the
1680 * anon_vma lock to serialize against concurrent expand_stacks.
1683 /* Somebody else might have raced and expanded it already */
1684 if (address < vma->vm_start) {
1685 unsigned long size, grow;
1687 size = vma->vm_end - address;
1688 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1690 error = acct_stack_growth(vma, size, grow);
1691 if (!error) {
1692 vma->vm_start = address;
1693 vma->vm_pgoff -= grow;
1696 anon_vma_unlock(vma);
1697 return error;
1700 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1702 return expand_downwards(vma, address);
1705 #ifdef CONFIG_STACK_GROWSUP
1706 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1708 return expand_upwards(vma, address);
1711 struct vm_area_struct *
1712 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1714 struct vm_area_struct *vma, *prev;
1716 addr &= PAGE_MASK;
1717 vma = find_vma_prev(mm, addr, &prev);
1718 if (vma && (vma->vm_start <= addr))
1719 return vma;
1720 if (!prev || expand_stack(prev, addr))
1721 return NULL;
1722 if (prev->vm_flags & VM_LOCKED) {
1723 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
1724 return NULL; /* vma gone! */
1726 return prev;
1728 #else
1729 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1731 return expand_downwards(vma, address);
1734 struct vm_area_struct *
1735 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1737 struct vm_area_struct * vma;
1738 unsigned long start;
1740 addr &= PAGE_MASK;
1741 vma = find_vma(mm,addr);
1742 if (!vma)
1743 return NULL;
1744 if (vma->vm_start <= addr)
1745 return vma;
1746 if (!(vma->vm_flags & VM_GROWSDOWN))
1747 return NULL;
1748 start = vma->vm_start;
1749 if (expand_stack(vma, addr))
1750 return NULL;
1751 if (vma->vm_flags & VM_LOCKED) {
1752 if (mlock_vma_pages_range(vma, addr, start) < 0)
1753 return NULL; /* vma gone! */
1755 return vma;
1757 #endif
1760 * Ok - we have the memory areas we should free on the vma list,
1761 * so release them, and do the vma updates.
1763 * Called with the mm semaphore held.
1765 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1767 /* Update high watermark before we lower total_vm */
1768 update_hiwater_vm(mm);
1769 do {
1770 long nrpages = vma_pages(vma);
1772 mm->total_vm -= nrpages;
1773 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1774 vma = remove_vma(vma);
1775 } while (vma);
1776 validate_mm(mm);
1780 * Get rid of page table information in the indicated region.
1782 * Called with the mm semaphore held.
1784 static void unmap_region(struct mm_struct *mm,
1785 struct vm_area_struct *vma, struct vm_area_struct *prev,
1786 unsigned long start, unsigned long end)
1788 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1789 struct mmu_gather *tlb;
1790 unsigned long nr_accounted = 0;
1792 lru_add_drain();
1793 tlb = tlb_gather_mmu(mm, 0);
1794 update_hiwater_rss(mm);
1795 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1796 vm_unacct_memory(nr_accounted);
1797 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1798 next? next->vm_start: 0);
1799 tlb_finish_mmu(tlb, start, end);
1803 * Create a list of vma's touched by the unmap, removing them from the mm's
1804 * vma list as we go..
1806 static void
1807 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1808 struct vm_area_struct *prev, unsigned long end)
1810 struct vm_area_struct **insertion_point;
1811 struct vm_area_struct *tail_vma = NULL;
1812 unsigned long addr;
1814 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1815 do {
1816 rb_erase(&vma->vm_rb, &mm->mm_rb);
1817 mm->map_count--;
1818 tail_vma = vma;
1819 vma = vma->vm_next;
1820 } while (vma && vma->vm_start < end);
1821 *insertion_point = vma;
1822 tail_vma->vm_next = NULL;
1823 if (mm->unmap_area == arch_unmap_area)
1824 addr = prev ? prev->vm_end : mm->mmap_base;
1825 else
1826 addr = vma ? vma->vm_start : mm->mmap_base;
1827 mm->unmap_area(mm, addr);
1828 mm->mmap_cache = NULL; /* Kill the cache. */
1832 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1833 * munmap path where it doesn't make sense to fail.
1835 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1836 unsigned long addr, int new_below)
1838 struct mempolicy *pol;
1839 struct vm_area_struct *new;
1841 if (is_vm_hugetlb_page(vma) && (addr &
1842 ~(huge_page_mask(hstate_vma(vma)))))
1843 return -EINVAL;
1845 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1846 if (!new)
1847 return -ENOMEM;
1849 /* most fields are the same, copy all, and then fixup */
1850 *new = *vma;
1852 if (new_below)
1853 new->vm_end = addr;
1854 else {
1855 new->vm_start = addr;
1856 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1859 pol = mpol_dup(vma_policy(vma));
1860 if (IS_ERR(pol)) {
1861 kmem_cache_free(vm_area_cachep, new);
1862 return PTR_ERR(pol);
1864 vma_set_policy(new, pol);
1866 if (new->vm_file) {
1867 get_file(new->vm_file);
1868 if (vma->vm_flags & VM_EXECUTABLE)
1869 added_exe_file_vma(mm);
1872 if (new->vm_ops && new->vm_ops->open)
1873 new->vm_ops->open(new);
1875 if (new_below)
1876 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1877 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1878 else
1879 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1881 return 0;
1885 * Split a vma into two pieces at address 'addr', a new vma is allocated
1886 * either for the first part or the tail.
1888 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1889 unsigned long addr, int new_below)
1891 if (mm->map_count >= sysctl_max_map_count)
1892 return -ENOMEM;
1894 return __split_vma(mm, vma, addr, new_below);
1897 /* Munmap is split into 2 main parts -- this part which finds
1898 * what needs doing, and the areas themselves, which do the
1899 * work. This now handles partial unmappings.
1900 * Jeremy Fitzhardinge <jeremy@goop.org>
1902 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1904 unsigned long end;
1905 struct vm_area_struct *vma, *prev, *last;
1907 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1908 return -EINVAL;
1910 if ((len = PAGE_ALIGN(len)) == 0)
1911 return -EINVAL;
1913 /* Find the first overlapping VMA */
1914 vma = find_vma_prev(mm, start, &prev);
1915 if (!vma)
1916 return 0;
1917 /* we have start < vma->vm_end */
1919 /* if it doesn't overlap, we have nothing.. */
1920 end = start + len;
1921 if (vma->vm_start >= end)
1922 return 0;
1925 * If we need to split any vma, do it now to save pain later.
1927 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1928 * unmapped vm_area_struct will remain in use: so lower split_vma
1929 * places tmp vma above, and higher split_vma places tmp vma below.
1931 if (start > vma->vm_start) {
1932 int error;
1935 * Make sure that map_count on return from munmap() will
1936 * not exceed its limit; but let map_count go just above
1937 * its limit temporarily, to help free resources as expected.
1939 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
1940 return -ENOMEM;
1942 error = __split_vma(mm, vma, start, 0);
1943 if (error)
1944 return error;
1945 prev = vma;
1948 /* Does it split the last one? */
1949 last = find_vma(mm, end);
1950 if (last && end > last->vm_start) {
1951 int error = __split_vma(mm, last, end, 1);
1952 if (error)
1953 return error;
1955 vma = prev? prev->vm_next: mm->mmap;
1958 * unlock any mlock()ed ranges before detaching vmas
1960 if (mm->locked_vm) {
1961 struct vm_area_struct *tmp = vma;
1962 while (tmp && tmp->vm_start < end) {
1963 if (tmp->vm_flags & VM_LOCKED) {
1964 mm->locked_vm -= vma_pages(tmp);
1965 munlock_vma_pages_all(tmp);
1967 tmp = tmp->vm_next;
1972 * Remove the vma's, and unmap the actual pages
1974 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1975 unmap_region(mm, vma, prev, start, end);
1977 /* Fix up all other VM information */
1978 remove_vma_list(mm, vma);
1980 return 0;
1983 EXPORT_SYMBOL(do_munmap);
1985 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1987 int ret;
1988 struct mm_struct *mm = current->mm;
1990 profile_munmap(addr);
1992 down_write(&mm->mmap_sem);
1993 ret = do_munmap(mm, addr, len);
1994 up_write(&mm->mmap_sem);
1995 return ret;
1998 static inline void verify_mm_writelocked(struct mm_struct *mm)
2000 #ifdef CONFIG_DEBUG_VM
2001 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2002 WARN_ON(1);
2003 up_read(&mm->mmap_sem);
2005 #endif
2009 * this is really a simplified "do_mmap". it only handles
2010 * anonymous maps. eventually we may be able to do some
2011 * brk-specific accounting here.
2013 unsigned long do_brk(unsigned long addr, unsigned long len)
2015 struct mm_struct * mm = current->mm;
2016 struct vm_area_struct * vma, * prev;
2017 unsigned long flags;
2018 struct rb_node ** rb_link, * rb_parent;
2019 pgoff_t pgoff = addr >> PAGE_SHIFT;
2020 int error;
2022 len = PAGE_ALIGN(len);
2023 if (!len)
2024 return addr;
2026 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
2027 return -EINVAL;
2029 if (is_hugepage_only_range(mm, addr, len))
2030 return -EINVAL;
2032 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2033 if (error)
2034 return error;
2036 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2038 error = arch_mmap_check(addr, len, flags);
2039 if (error)
2040 return error;
2043 * mlock MCL_FUTURE?
2045 if (mm->def_flags & VM_LOCKED) {
2046 unsigned long locked, lock_limit;
2047 locked = len >> PAGE_SHIFT;
2048 locked += mm->locked_vm;
2049 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2050 lock_limit >>= PAGE_SHIFT;
2051 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2052 return -EAGAIN;
2056 * mm->mmap_sem is required to protect against another thread
2057 * changing the mappings in case we sleep.
2059 verify_mm_writelocked(mm);
2062 * Clear old maps. this also does some error checking for us
2064 munmap_back:
2065 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2066 if (vma && vma->vm_start < addr + len) {
2067 if (do_munmap(mm, addr, len))
2068 return -ENOMEM;
2069 goto munmap_back;
2072 /* Check against address space limits *after* clearing old maps... */
2073 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2074 return -ENOMEM;
2076 if (mm->map_count > sysctl_max_map_count)
2077 return -ENOMEM;
2079 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2080 return -ENOMEM;
2082 /* Can we just expand an old private anonymous mapping? */
2083 vma = vma_merge(mm, prev, addr, addr + len, flags,
2084 NULL, NULL, pgoff, NULL);
2085 if (vma)
2086 goto out;
2089 * create a vma struct for an anonymous mapping
2091 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2092 if (!vma) {
2093 vm_unacct_memory(len >> PAGE_SHIFT);
2094 return -ENOMEM;
2097 vma->vm_mm = mm;
2098 vma->vm_start = addr;
2099 vma->vm_end = addr + len;
2100 vma->vm_pgoff = pgoff;
2101 vma->vm_flags = flags;
2102 vma->vm_page_prot = vm_get_page_prot(flags);
2103 vma_link(mm, vma, prev, rb_link, rb_parent);
2104 out:
2105 mm->total_vm += len >> PAGE_SHIFT;
2106 if (flags & VM_LOCKED) {
2107 if (!mlock_vma_pages_range(vma, addr, addr + len))
2108 mm->locked_vm += (len >> PAGE_SHIFT);
2110 return addr;
2113 EXPORT_SYMBOL(do_brk);
2115 /* Release all mmaps. */
2116 void exit_mmap(struct mm_struct *mm)
2118 struct mmu_gather *tlb;
2119 struct vm_area_struct *vma;
2120 unsigned long nr_accounted = 0;
2121 unsigned long end;
2123 /* mm's last user has gone, and its about to be pulled down */
2124 mmu_notifier_release(mm);
2126 if (mm->locked_vm) {
2127 vma = mm->mmap;
2128 while (vma) {
2129 if (vma->vm_flags & VM_LOCKED)
2130 munlock_vma_pages_all(vma);
2131 vma = vma->vm_next;
2135 arch_exit_mmap(mm);
2137 vma = mm->mmap;
2138 if (!vma) /* Can happen if dup_mmap() received an OOM */
2139 return;
2141 lru_add_drain();
2142 flush_cache_mm(mm);
2143 tlb = tlb_gather_mmu(mm, 1);
2144 /* update_hiwater_rss(mm) here? but nobody should be looking */
2145 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2146 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2147 vm_unacct_memory(nr_accounted);
2149 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2150 tlb_finish_mmu(tlb, 0, end);
2153 * Walk the list again, actually closing and freeing it,
2154 * with preemption enabled, without holding any MM locks.
2156 while (vma)
2157 vma = remove_vma(vma);
2159 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2162 /* Insert vm structure into process list sorted by address
2163 * and into the inode's i_mmap tree. If vm_file is non-NULL
2164 * then i_mmap_lock is taken here.
2166 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2168 struct vm_area_struct * __vma, * prev;
2169 struct rb_node ** rb_link, * rb_parent;
2172 * The vm_pgoff of a purely anonymous vma should be irrelevant
2173 * until its first write fault, when page's anon_vma and index
2174 * are set. But now set the vm_pgoff it will almost certainly
2175 * end up with (unless mremap moves it elsewhere before that
2176 * first wfault), so /proc/pid/maps tells a consistent story.
2178 * By setting it to reflect the virtual start address of the
2179 * vma, merges and splits can happen in a seamless way, just
2180 * using the existing file pgoff checks and manipulations.
2181 * Similarly in do_mmap_pgoff and in do_brk.
2183 if (!vma->vm_file) {
2184 BUG_ON(vma->anon_vma);
2185 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2187 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2188 if (__vma && __vma->vm_start < vma->vm_end)
2189 return -ENOMEM;
2190 if ((vma->vm_flags & VM_ACCOUNT) &&
2191 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2192 return -ENOMEM;
2193 vma_link(mm, vma, prev, rb_link, rb_parent);
2194 return 0;
2198 * Copy the vma structure to a new location in the same mm,
2199 * prior to moving page table entries, to effect an mremap move.
2201 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2202 unsigned long addr, unsigned long len, pgoff_t pgoff)
2204 struct vm_area_struct *vma = *vmap;
2205 unsigned long vma_start = vma->vm_start;
2206 struct mm_struct *mm = vma->vm_mm;
2207 struct vm_area_struct *new_vma, *prev;
2208 struct rb_node **rb_link, *rb_parent;
2209 struct mempolicy *pol;
2212 * If anonymous vma has not yet been faulted, update new pgoff
2213 * to match new location, to increase its chance of merging.
2215 if (!vma->vm_file && !vma->anon_vma)
2216 pgoff = addr >> PAGE_SHIFT;
2218 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2219 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2220 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2221 if (new_vma) {
2223 * Source vma may have been merged into new_vma
2225 if (vma_start >= new_vma->vm_start &&
2226 vma_start < new_vma->vm_end)
2227 *vmap = new_vma;
2228 } else {
2229 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2230 if (new_vma) {
2231 *new_vma = *vma;
2232 pol = mpol_dup(vma_policy(vma));
2233 if (IS_ERR(pol)) {
2234 kmem_cache_free(vm_area_cachep, new_vma);
2235 return NULL;
2237 vma_set_policy(new_vma, pol);
2238 new_vma->vm_start = addr;
2239 new_vma->vm_end = addr + len;
2240 new_vma->vm_pgoff = pgoff;
2241 if (new_vma->vm_file) {
2242 get_file(new_vma->vm_file);
2243 if (vma->vm_flags & VM_EXECUTABLE)
2244 added_exe_file_vma(mm);
2246 if (new_vma->vm_ops && new_vma->vm_ops->open)
2247 new_vma->vm_ops->open(new_vma);
2248 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2251 return new_vma;
2255 * Return true if the calling process may expand its vm space by the passed
2256 * number of pages
2258 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2260 unsigned long cur = mm->total_vm; /* pages */
2261 unsigned long lim;
2263 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2265 if (cur + npages > lim)
2266 return 0;
2267 return 1;
2271 static int special_mapping_fault(struct vm_area_struct *vma,
2272 struct vm_fault *vmf)
2274 pgoff_t pgoff;
2275 struct page **pages;
2278 * special mappings have no vm_file, and in that case, the mm
2279 * uses vm_pgoff internally. So we have to subtract it from here.
2280 * We are allowed to do this because we are the mm; do not copy
2281 * this code into drivers!
2283 pgoff = vmf->pgoff - vma->vm_pgoff;
2285 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2286 pgoff--;
2288 if (*pages) {
2289 struct page *page = *pages;
2290 get_page(page);
2291 vmf->page = page;
2292 return 0;
2295 return VM_FAULT_SIGBUS;
2299 * Having a close hook prevents vma merging regardless of flags.
2301 static void special_mapping_close(struct vm_area_struct *vma)
2305 static const struct vm_operations_struct special_mapping_vmops = {
2306 .close = special_mapping_close,
2307 .fault = special_mapping_fault,
2311 * Called with mm->mmap_sem held for writing.
2312 * Insert a new vma covering the given region, with the given flags.
2313 * Its pages are supplied by the given array of struct page *.
2314 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2315 * The region past the last page supplied will always produce SIGBUS.
2316 * The array pointer and the pages it points to are assumed to stay alive
2317 * for as long as this mapping might exist.
2319 int install_special_mapping(struct mm_struct *mm,
2320 unsigned long addr, unsigned long len,
2321 unsigned long vm_flags, struct page **pages)
2323 struct vm_area_struct *vma;
2325 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2326 if (unlikely(vma == NULL))
2327 return -ENOMEM;
2329 vma->vm_mm = mm;
2330 vma->vm_start = addr;
2331 vma->vm_end = addr + len;
2333 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2334 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2336 vma->vm_ops = &special_mapping_vmops;
2337 vma->vm_private_data = pages;
2339 if (unlikely(insert_vm_struct(mm, vma))) {
2340 kmem_cache_free(vm_area_cachep, vma);
2341 return -ENOMEM;
2344 mm->total_vm += len >> PAGE_SHIFT;
2346 perf_event_mmap(vma);
2348 return 0;
2351 static DEFINE_MUTEX(mm_all_locks_mutex);
2353 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2355 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2357 * The LSB of head.next can't change from under us
2358 * because we hold the mm_all_locks_mutex.
2360 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2362 * We can safely modify head.next after taking the
2363 * anon_vma->lock. If some other vma in this mm shares
2364 * the same anon_vma we won't take it again.
2366 * No need of atomic instructions here, head.next
2367 * can't change from under us thanks to the
2368 * anon_vma->lock.
2370 if (__test_and_set_bit(0, (unsigned long *)
2371 &anon_vma->head.next))
2372 BUG();
2376 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2378 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2380 * AS_MM_ALL_LOCKS can't change from under us because
2381 * we hold the mm_all_locks_mutex.
2383 * Operations on ->flags have to be atomic because
2384 * even if AS_MM_ALL_LOCKS is stable thanks to the
2385 * mm_all_locks_mutex, there may be other cpus
2386 * changing other bitflags in parallel to us.
2388 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2389 BUG();
2390 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2395 * This operation locks against the VM for all pte/vma/mm related
2396 * operations that could ever happen on a certain mm. This includes
2397 * vmtruncate, try_to_unmap, and all page faults.
2399 * The caller must take the mmap_sem in write mode before calling
2400 * mm_take_all_locks(). The caller isn't allowed to release the
2401 * mmap_sem until mm_drop_all_locks() returns.
2403 * mmap_sem in write mode is required in order to block all operations
2404 * that could modify pagetables and free pages without need of
2405 * altering the vma layout (for example populate_range() with
2406 * nonlinear vmas). It's also needed in write mode to avoid new
2407 * anon_vmas to be associated with existing vmas.
2409 * A single task can't take more than one mm_take_all_locks() in a row
2410 * or it would deadlock.
2412 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2413 * mapping->flags avoid to take the same lock twice, if more than one
2414 * vma in this mm is backed by the same anon_vma or address_space.
2416 * We can take all the locks in random order because the VM code
2417 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2418 * takes more than one of them in a row. Secondly we're protected
2419 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2421 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2422 * that may have to take thousand of locks.
2424 * mm_take_all_locks() can fail if it's interrupted by signals.
2426 int mm_take_all_locks(struct mm_struct *mm)
2428 struct vm_area_struct *vma;
2429 int ret = -EINTR;
2431 BUG_ON(down_read_trylock(&mm->mmap_sem));
2433 mutex_lock(&mm_all_locks_mutex);
2435 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2436 if (signal_pending(current))
2437 goto out_unlock;
2438 if (vma->vm_file && vma->vm_file->f_mapping)
2439 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2442 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2443 if (signal_pending(current))
2444 goto out_unlock;
2445 if (vma->anon_vma)
2446 vm_lock_anon_vma(mm, vma->anon_vma);
2449 ret = 0;
2451 out_unlock:
2452 if (ret)
2453 mm_drop_all_locks(mm);
2455 return ret;
2458 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2460 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2462 * The LSB of head.next can't change to 0 from under
2463 * us because we hold the mm_all_locks_mutex.
2465 * We must however clear the bitflag before unlocking
2466 * the vma so the users using the anon_vma->head will
2467 * never see our bitflag.
2469 * No need of atomic instructions here, head.next
2470 * can't change from under us until we release the
2471 * anon_vma->lock.
2473 if (!__test_and_clear_bit(0, (unsigned long *)
2474 &anon_vma->head.next))
2475 BUG();
2476 spin_unlock(&anon_vma->lock);
2480 static void vm_unlock_mapping(struct address_space *mapping)
2482 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2484 * AS_MM_ALL_LOCKS can't change to 0 from under us
2485 * because we hold the mm_all_locks_mutex.
2487 spin_unlock(&mapping->i_mmap_lock);
2488 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2489 &mapping->flags))
2490 BUG();
2495 * The mmap_sem cannot be released by the caller until
2496 * mm_drop_all_locks() returns.
2498 void mm_drop_all_locks(struct mm_struct *mm)
2500 struct vm_area_struct *vma;
2502 BUG_ON(down_read_trylock(&mm->mmap_sem));
2503 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2505 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2506 if (vma->anon_vma)
2507 vm_unlock_anon_vma(vma->anon_vma);
2508 if (vma->vm_file && vma->vm_file->f_mapping)
2509 vm_unlock_mapping(vma->vm_file->f_mapping);
2512 mutex_unlock(&mm_all_locks_mutex);
2516 * initialise the VMA slab
2518 void __init mmap_init(void)
2520 int ret;
2522 ret = percpu_counter_init(&vm_committed_as, 0);
2523 VM_BUG_ON(ret);