ASoC: Remove console DAPM debug code
[firewire-audio.git] / mm / mmap.c
blobd9c77b2dbe9d6489cdf5e40e5f5ae0dfc2be2a5a
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/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
29 #include <linux/mmu_notifier.h>
30 #include <linux/perf_event.h>
32 #include <asm/uaccess.h>
33 #include <asm/cacheflush.h>
34 #include <asm/tlb.h>
35 #include <asm/mmu_context.h>
37 #include "internal.h"
39 #ifndef arch_mmap_check
40 #define arch_mmap_check(addr, len, flags) (0)
41 #endif
43 #ifndef arch_rebalance_pgtables
44 #define arch_rebalance_pgtables(addr, len) (addr)
45 #endif
47 static void unmap_region(struct mm_struct *mm,
48 struct vm_area_struct *vma, struct vm_area_struct *prev,
49 unsigned long start, unsigned long end);
52 * WARNING: the debugging will use recursive algorithms so never enable this
53 * unless you know what you are doing.
55 #undef DEBUG_MM_RB
57 /* description of effects of mapping type and prot in current implementation.
58 * this is due to the limited x86 page protection hardware. The expected
59 * behavior is in parens:
61 * map_type prot
62 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
63 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
64 * w: (no) no w: (no) no w: (yes) yes w: (no) no
65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
67 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
68 * w: (no) no w: (no) no w: (copy) copy w: (no) no
69 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
72 pgprot_t protection_map[16] = {
73 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
74 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
77 pgprot_t vm_get_page_prot(unsigned long vm_flags)
79 return __pgprot(pgprot_val(protection_map[vm_flags &
80 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
81 pgprot_val(arch_vm_get_page_prot(vm_flags)));
83 EXPORT_SYMBOL(vm_get_page_prot);
85 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
86 int sysctl_overcommit_ratio = 50; /* default is 50% */
87 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
88 struct percpu_counter vm_committed_as;
91 * Check that a process has enough memory to allocate a new virtual
92 * mapping. 0 means there is enough memory for the allocation to
93 * succeed and -ENOMEM implies there is not.
95 * We currently support three overcommit policies, which are set via the
96 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
98 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
99 * Additional code 2002 Jul 20 by Robert Love.
101 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
103 * Note this is a helper function intended to be used by LSMs which
104 * wish to use this logic.
106 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
108 unsigned long free, allowed;
110 vm_acct_memory(pages);
113 * Sometimes we want to use more memory than we have
115 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
116 return 0;
118 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
119 unsigned long n;
121 free = global_page_state(NR_FILE_PAGES);
122 free += nr_swap_pages;
125 * Any slabs which are created with the
126 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
127 * which are reclaimable, under pressure. The dentry
128 * cache and most inode caches should fall into this
130 free += global_page_state(NR_SLAB_RECLAIMABLE);
133 * Leave the last 3% for root
135 if (!cap_sys_admin)
136 free -= free / 32;
138 if (free > pages)
139 return 0;
142 * nr_free_pages() is very expensive on large systems,
143 * only call if we're about to fail.
145 n = nr_free_pages();
148 * Leave reserved pages. The pages are not for anonymous pages.
150 if (n <= totalreserve_pages)
151 goto error;
152 else
153 n -= totalreserve_pages;
156 * Leave the last 3% for root
158 if (!cap_sys_admin)
159 n -= n / 32;
160 free += n;
162 if (free > pages)
163 return 0;
165 goto error;
168 allowed = (totalram_pages - hugetlb_total_pages())
169 * sysctl_overcommit_ratio / 100;
171 * Leave the last 3% for root
173 if (!cap_sys_admin)
174 allowed -= allowed / 32;
175 allowed += total_swap_pages;
177 /* Don't let a single process grow too big:
178 leave 3% of the size of this process for other processes */
179 if (mm)
180 allowed -= mm->total_vm / 32;
182 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
183 return 0;
184 error:
185 vm_unacct_memory(pages);
187 return -ENOMEM;
191 * Requires inode->i_mapping->i_mmap_lock
193 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
194 struct file *file, struct address_space *mapping)
196 if (vma->vm_flags & VM_DENYWRITE)
197 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
198 if (vma->vm_flags & VM_SHARED)
199 mapping->i_mmap_writable--;
201 flush_dcache_mmap_lock(mapping);
202 if (unlikely(vma->vm_flags & VM_NONLINEAR))
203 list_del_init(&vma->shared.vm_set.list);
204 else
205 vma_prio_tree_remove(vma, &mapping->i_mmap);
206 flush_dcache_mmap_unlock(mapping);
210 * Unlink a file-based vm structure from its prio_tree, to hide
211 * vma from rmap and vmtruncate before freeing its page tables.
213 void unlink_file_vma(struct vm_area_struct *vma)
215 struct file *file = vma->vm_file;
217 if (file) {
218 struct address_space *mapping = file->f_mapping;
219 spin_lock(&mapping->i_mmap_lock);
220 __remove_shared_vm_struct(vma, file, mapping);
221 spin_unlock(&mapping->i_mmap_lock);
226 * Close a vm structure and free it, returning the next.
228 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
230 struct vm_area_struct *next = vma->vm_next;
232 might_sleep();
233 if (vma->vm_ops && vma->vm_ops->close)
234 vma->vm_ops->close(vma);
235 if (vma->vm_file) {
236 fput(vma->vm_file);
237 if (vma->vm_flags & VM_EXECUTABLE)
238 removed_exe_file_vma(vma->vm_mm);
240 mpol_put(vma_policy(vma));
241 kmem_cache_free(vm_area_cachep, vma);
242 return next;
245 SYSCALL_DEFINE1(brk, unsigned long, brk)
247 unsigned long rlim, retval;
248 unsigned long newbrk, oldbrk;
249 struct mm_struct *mm = current->mm;
250 unsigned long min_brk;
252 down_write(&mm->mmap_sem);
254 #ifdef CONFIG_COMPAT_BRK
255 min_brk = mm->end_code;
256 #else
257 min_brk = mm->start_brk;
258 #endif
259 if (brk < min_brk)
260 goto out;
263 * Check against rlimit here. If this check is done later after the test
264 * of oldbrk with newbrk then it can escape the test and let the data
265 * segment grow beyond its set limit the in case where the limit is
266 * not page aligned -Ram Gupta
268 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
269 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
270 (mm->end_data - mm->start_data) > rlim)
271 goto out;
273 newbrk = PAGE_ALIGN(brk);
274 oldbrk = PAGE_ALIGN(mm->brk);
275 if (oldbrk == newbrk)
276 goto set_brk;
278 /* Always allow shrinking brk. */
279 if (brk <= mm->brk) {
280 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
281 goto set_brk;
282 goto out;
285 /* Check against existing mmap mappings. */
286 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
287 goto out;
289 /* Ok, looks good - let it rip. */
290 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
291 goto out;
292 set_brk:
293 mm->brk = brk;
294 out:
295 retval = mm->brk;
296 up_write(&mm->mmap_sem);
297 return retval;
300 #ifdef DEBUG_MM_RB
301 static int browse_rb(struct rb_root *root)
303 int i = 0, j;
304 struct rb_node *nd, *pn = NULL;
305 unsigned long prev = 0, pend = 0;
307 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
308 struct vm_area_struct *vma;
309 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
310 if (vma->vm_start < prev)
311 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
312 if (vma->vm_start < pend)
313 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
314 if (vma->vm_start > vma->vm_end)
315 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
316 i++;
317 pn = nd;
318 prev = vma->vm_start;
319 pend = vma->vm_end;
321 j = 0;
322 for (nd = pn; nd; nd = rb_prev(nd)) {
323 j++;
325 if (i != j)
326 printk("backwards %d, forwards %d\n", j, i), i = 0;
327 return i;
330 void validate_mm(struct mm_struct *mm)
332 int bug = 0;
333 int i = 0;
334 struct vm_area_struct *tmp = mm->mmap;
335 while (tmp) {
336 tmp = tmp->vm_next;
337 i++;
339 if (i != mm->map_count)
340 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
341 i = browse_rb(&mm->mm_rb);
342 if (i != mm->map_count)
343 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
344 BUG_ON(bug);
346 #else
347 #define validate_mm(mm) do { } while (0)
348 #endif
350 static struct vm_area_struct *
351 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
352 struct vm_area_struct **pprev, struct rb_node ***rb_link,
353 struct rb_node ** rb_parent)
355 struct vm_area_struct * vma;
356 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
358 __rb_link = &mm->mm_rb.rb_node;
359 rb_prev = __rb_parent = NULL;
360 vma = NULL;
362 while (*__rb_link) {
363 struct vm_area_struct *vma_tmp;
365 __rb_parent = *__rb_link;
366 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
368 if (vma_tmp->vm_end > addr) {
369 vma = vma_tmp;
370 if (vma_tmp->vm_start <= addr)
371 break;
372 __rb_link = &__rb_parent->rb_left;
373 } else {
374 rb_prev = __rb_parent;
375 __rb_link = &__rb_parent->rb_right;
379 *pprev = NULL;
380 if (rb_prev)
381 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
382 *rb_link = __rb_link;
383 *rb_parent = __rb_parent;
384 return vma;
387 static inline void
388 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
389 struct vm_area_struct *prev, struct rb_node *rb_parent)
391 if (prev) {
392 vma->vm_next = prev->vm_next;
393 prev->vm_next = vma;
394 } else {
395 mm->mmap = vma;
396 if (rb_parent)
397 vma->vm_next = rb_entry(rb_parent,
398 struct vm_area_struct, vm_rb);
399 else
400 vma->vm_next = NULL;
404 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
405 struct rb_node **rb_link, struct rb_node *rb_parent)
407 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
408 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
411 static void __vma_link_file(struct vm_area_struct *vma)
413 struct file *file;
415 file = vma->vm_file;
416 if (file) {
417 struct address_space *mapping = file->f_mapping;
419 if (vma->vm_flags & VM_DENYWRITE)
420 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
421 if (vma->vm_flags & VM_SHARED)
422 mapping->i_mmap_writable++;
424 flush_dcache_mmap_lock(mapping);
425 if (unlikely(vma->vm_flags & VM_NONLINEAR))
426 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
427 else
428 vma_prio_tree_insert(vma, &mapping->i_mmap);
429 flush_dcache_mmap_unlock(mapping);
433 static void
434 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
435 struct vm_area_struct *prev, struct rb_node **rb_link,
436 struct rb_node *rb_parent)
438 __vma_link_list(mm, vma, prev, rb_parent);
439 __vma_link_rb(mm, vma, rb_link, rb_parent);
440 __anon_vma_link(vma);
443 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
444 struct vm_area_struct *prev, struct rb_node **rb_link,
445 struct rb_node *rb_parent)
447 struct address_space *mapping = NULL;
449 if (vma->vm_file)
450 mapping = vma->vm_file->f_mapping;
452 if (mapping) {
453 spin_lock(&mapping->i_mmap_lock);
454 vma->vm_truncate_count = mapping->truncate_count;
456 anon_vma_lock(vma);
458 __vma_link(mm, vma, prev, rb_link, rb_parent);
459 __vma_link_file(vma);
461 anon_vma_unlock(vma);
462 if (mapping)
463 spin_unlock(&mapping->i_mmap_lock);
465 mm->map_count++;
466 validate_mm(mm);
470 * Helper for vma_adjust in the split_vma insert case:
471 * insert vm structure into list and rbtree and anon_vma,
472 * but it has already been inserted into prio_tree earlier.
474 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
476 struct vm_area_struct *__vma, *prev;
477 struct rb_node **rb_link, *rb_parent;
479 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
480 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
481 __vma_link(mm, vma, prev, rb_link, rb_parent);
482 mm->map_count++;
485 static inline void
486 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
487 struct vm_area_struct *prev)
489 prev->vm_next = vma->vm_next;
490 rb_erase(&vma->vm_rb, &mm->mm_rb);
491 if (mm->mmap_cache == vma)
492 mm->mmap_cache = prev;
496 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
497 * is already present in an i_mmap tree without adjusting the tree.
498 * The following helper function should be used when such adjustments
499 * are necessary. The "insert" vma (if any) is to be inserted
500 * before we drop the necessary locks.
502 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
503 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
505 struct mm_struct *mm = vma->vm_mm;
506 struct vm_area_struct *next = vma->vm_next;
507 struct vm_area_struct *importer = NULL;
508 struct address_space *mapping = NULL;
509 struct prio_tree_root *root = NULL;
510 struct file *file = vma->vm_file;
511 struct anon_vma *anon_vma = NULL;
512 long adjust_next = 0;
513 int remove_next = 0;
515 if (next && !insert) {
516 if (end >= next->vm_end) {
518 * vma expands, overlapping all the next, and
519 * perhaps the one after too (mprotect case 6).
521 again: remove_next = 1 + (end > next->vm_end);
522 end = next->vm_end;
523 anon_vma = next->anon_vma;
524 importer = vma;
525 } else if (end > next->vm_start) {
527 * vma expands, overlapping part of the next:
528 * mprotect case 5 shifting the boundary up.
530 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
531 anon_vma = next->anon_vma;
532 importer = vma;
533 } else if (end < vma->vm_end) {
535 * vma shrinks, and !insert tells it's not
536 * split_vma inserting another: so it must be
537 * mprotect case 4 shifting the boundary down.
539 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
540 anon_vma = next->anon_vma;
541 importer = next;
545 if (file) {
546 mapping = file->f_mapping;
547 if (!(vma->vm_flags & VM_NONLINEAR))
548 root = &mapping->i_mmap;
549 spin_lock(&mapping->i_mmap_lock);
550 if (importer &&
551 vma->vm_truncate_count != next->vm_truncate_count) {
553 * unmap_mapping_range might be in progress:
554 * ensure that the expanding vma is rescanned.
556 importer->vm_truncate_count = 0;
558 if (insert) {
559 insert->vm_truncate_count = vma->vm_truncate_count;
561 * Put into prio_tree now, so instantiated pages
562 * are visible to arm/parisc __flush_dcache_page
563 * throughout; but we cannot insert into address
564 * space until vma start or end is updated.
566 __vma_link_file(insert);
571 * When changing only vma->vm_end, we don't really need
572 * anon_vma lock.
574 if (vma->anon_vma && (insert || importer || start != vma->vm_start))
575 anon_vma = vma->anon_vma;
576 if (anon_vma) {
577 spin_lock(&anon_vma->lock);
579 * Easily overlooked: when mprotect shifts the boundary,
580 * make sure the expanding vma has anon_vma set if the
581 * shrinking vma had, to cover any anon pages imported.
583 if (importer && !importer->anon_vma) {
584 importer->anon_vma = anon_vma;
585 __anon_vma_link(importer);
589 if (root) {
590 flush_dcache_mmap_lock(mapping);
591 vma_prio_tree_remove(vma, root);
592 if (adjust_next)
593 vma_prio_tree_remove(next, root);
596 vma->vm_start = start;
597 vma->vm_end = end;
598 vma->vm_pgoff = pgoff;
599 if (adjust_next) {
600 next->vm_start += adjust_next << PAGE_SHIFT;
601 next->vm_pgoff += adjust_next;
604 if (root) {
605 if (adjust_next)
606 vma_prio_tree_insert(next, root);
607 vma_prio_tree_insert(vma, root);
608 flush_dcache_mmap_unlock(mapping);
611 if (remove_next) {
613 * vma_merge has merged next into vma, and needs
614 * us to remove next before dropping the locks.
616 __vma_unlink(mm, next, vma);
617 if (file)
618 __remove_shared_vm_struct(next, file, mapping);
619 if (next->anon_vma)
620 __anon_vma_merge(vma, next);
621 } else if (insert) {
623 * split_vma has split insert from vma, and needs
624 * us to insert it before dropping the locks
625 * (it may either follow vma or precede it).
627 __insert_vm_struct(mm, insert);
630 if (anon_vma)
631 spin_unlock(&anon_vma->lock);
632 if (mapping)
633 spin_unlock(&mapping->i_mmap_lock);
635 if (remove_next) {
636 if (file) {
637 fput(file);
638 if (next->vm_flags & VM_EXECUTABLE)
639 removed_exe_file_vma(mm);
641 mm->map_count--;
642 mpol_put(vma_policy(next));
643 kmem_cache_free(vm_area_cachep, next);
645 * In mprotect's case 6 (see comments on vma_merge),
646 * we must remove another next too. It would clutter
647 * up the code too much to do both in one go.
649 if (remove_next == 2) {
650 next = vma->vm_next;
651 goto again;
655 validate_mm(mm);
659 * If the vma has a ->close operation then the driver probably needs to release
660 * per-vma resources, so we don't attempt to merge those.
662 static inline int is_mergeable_vma(struct vm_area_struct *vma,
663 struct file *file, unsigned long vm_flags)
665 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
666 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
667 return 0;
668 if (vma->vm_file != file)
669 return 0;
670 if (vma->vm_ops && vma->vm_ops->close)
671 return 0;
672 return 1;
675 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
676 struct anon_vma *anon_vma2)
678 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
682 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
683 * in front of (at a lower virtual address and file offset than) the vma.
685 * We cannot merge two vmas if they have differently assigned (non-NULL)
686 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
688 * We don't check here for the merged mmap wrapping around the end of pagecache
689 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
690 * wrap, nor mmaps which cover the final page at index -1UL.
692 static int
693 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
694 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
696 if (is_mergeable_vma(vma, file, vm_flags) &&
697 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
698 if (vma->vm_pgoff == vm_pgoff)
699 return 1;
701 return 0;
705 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
706 * beyond (at a higher virtual address and file offset than) the vma.
708 * We cannot merge two vmas if they have differently assigned (non-NULL)
709 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
711 static int
712 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
713 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
715 if (is_mergeable_vma(vma, file, vm_flags) &&
716 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
717 pgoff_t vm_pglen;
718 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
719 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
720 return 1;
722 return 0;
726 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
727 * whether that can be merged with its predecessor or its successor.
728 * Or both (it neatly fills a hole).
730 * In most cases - when called for mmap, brk or mremap - [addr,end) is
731 * certain not to be mapped by the time vma_merge is called; but when
732 * called for mprotect, it is certain to be already mapped (either at
733 * an offset within prev, or at the start of next), and the flags of
734 * this area are about to be changed to vm_flags - and the no-change
735 * case has already been eliminated.
737 * The following mprotect cases have to be considered, where AAAA is
738 * the area passed down from mprotect_fixup, never extending beyond one
739 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
741 * AAAA AAAA AAAA AAAA
742 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
743 * cannot merge might become might become might become
744 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
745 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
746 * mremap move: PPPPNNNNNNNN 8
747 * AAAA
748 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
749 * might become case 1 below case 2 below case 3 below
751 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
752 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
754 struct vm_area_struct *vma_merge(struct mm_struct *mm,
755 struct vm_area_struct *prev, unsigned long addr,
756 unsigned long end, unsigned long vm_flags,
757 struct anon_vma *anon_vma, struct file *file,
758 pgoff_t pgoff, struct mempolicy *policy)
760 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
761 struct vm_area_struct *area, *next;
764 * We later require that vma->vm_flags == vm_flags,
765 * so this tests vma->vm_flags & VM_SPECIAL, too.
767 if (vm_flags & VM_SPECIAL)
768 return NULL;
770 if (prev)
771 next = prev->vm_next;
772 else
773 next = mm->mmap;
774 area = next;
775 if (next && next->vm_end == end) /* cases 6, 7, 8 */
776 next = next->vm_next;
779 * Can it merge with the predecessor?
781 if (prev && prev->vm_end == addr &&
782 mpol_equal(vma_policy(prev), policy) &&
783 can_vma_merge_after(prev, vm_flags,
784 anon_vma, file, pgoff)) {
786 * OK, it can. Can we now merge in the successor as well?
788 if (next && end == next->vm_start &&
789 mpol_equal(policy, vma_policy(next)) &&
790 can_vma_merge_before(next, vm_flags,
791 anon_vma, file, pgoff+pglen) &&
792 is_mergeable_anon_vma(prev->anon_vma,
793 next->anon_vma)) {
794 /* cases 1, 6 */
795 vma_adjust(prev, prev->vm_start,
796 next->vm_end, prev->vm_pgoff, NULL);
797 } else /* cases 2, 5, 7 */
798 vma_adjust(prev, prev->vm_start,
799 end, prev->vm_pgoff, NULL);
800 return prev;
804 * Can this new request be merged in front of next?
806 if (next && end == next->vm_start &&
807 mpol_equal(policy, vma_policy(next)) &&
808 can_vma_merge_before(next, vm_flags,
809 anon_vma, file, pgoff+pglen)) {
810 if (prev && addr < prev->vm_end) /* case 4 */
811 vma_adjust(prev, prev->vm_start,
812 addr, prev->vm_pgoff, NULL);
813 else /* cases 3, 8 */
814 vma_adjust(area, addr, next->vm_end,
815 next->vm_pgoff - pglen, NULL);
816 return area;
819 return NULL;
823 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
824 * neighbouring vmas for a suitable anon_vma, before it goes off
825 * to allocate a new anon_vma. It checks because a repetitive
826 * sequence of mprotects and faults may otherwise lead to distinct
827 * anon_vmas being allocated, preventing vma merge in subsequent
828 * mprotect.
830 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
832 struct vm_area_struct *near;
833 unsigned long vm_flags;
835 near = vma->vm_next;
836 if (!near)
837 goto try_prev;
840 * Since only mprotect tries to remerge vmas, match flags
841 * which might be mprotected into each other later on.
842 * Neither mlock nor madvise tries to remerge at present,
843 * so leave their flags as obstructing a merge.
845 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
846 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
848 if (near->anon_vma && vma->vm_end == near->vm_start &&
849 mpol_equal(vma_policy(vma), vma_policy(near)) &&
850 can_vma_merge_before(near, vm_flags,
851 NULL, vma->vm_file, vma->vm_pgoff +
852 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
853 return near->anon_vma;
854 try_prev:
856 * It is potentially slow to have to call find_vma_prev here.
857 * But it's only on the first write fault on the vma, not
858 * every time, and we could devise a way to avoid it later
859 * (e.g. stash info in next's anon_vma_node when assigning
860 * an anon_vma, or when trying vma_merge). Another time.
862 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
863 if (!near)
864 goto none;
866 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
867 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
869 if (near->anon_vma && near->vm_end == vma->vm_start &&
870 mpol_equal(vma_policy(near), vma_policy(vma)) &&
871 can_vma_merge_after(near, vm_flags,
872 NULL, vma->vm_file, vma->vm_pgoff))
873 return near->anon_vma;
874 none:
876 * There's no absolute need to look only at touching neighbours:
877 * we could search further afield for "compatible" anon_vmas.
878 * But it would probably just be a waste of time searching,
879 * or lead to too many vmas hanging off the same anon_vma.
880 * We're trying to allow mprotect remerging later on,
881 * not trying to minimize memory used for anon_vmas.
883 return NULL;
886 #ifdef CONFIG_PROC_FS
887 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
888 struct file *file, long pages)
890 const unsigned long stack_flags
891 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
893 if (file) {
894 mm->shared_vm += pages;
895 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
896 mm->exec_vm += pages;
897 } else if (flags & stack_flags)
898 mm->stack_vm += pages;
899 if (flags & (VM_RESERVED|VM_IO))
900 mm->reserved_vm += pages;
902 #endif /* CONFIG_PROC_FS */
905 * The caller must hold down_write(&current->mm->mmap_sem).
908 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
909 unsigned long len, unsigned long prot,
910 unsigned long flags, unsigned long pgoff)
912 struct mm_struct * mm = current->mm;
913 struct inode *inode;
914 unsigned int vm_flags;
915 int error;
916 unsigned long reqprot = prot;
919 * Does the application expect PROT_READ to imply PROT_EXEC?
921 * (the exception is when the underlying filesystem is noexec
922 * mounted, in which case we dont add PROT_EXEC.)
924 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
925 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
926 prot |= PROT_EXEC;
928 if (!len)
929 return -EINVAL;
931 if (!(flags & MAP_FIXED))
932 addr = round_hint_to_min(addr);
934 /* Careful about overflows.. */
935 len = PAGE_ALIGN(len);
936 if (!len)
937 return -ENOMEM;
939 /* offset overflow? */
940 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
941 return -EOVERFLOW;
943 /* Too many mappings? */
944 if (mm->map_count > sysctl_max_map_count)
945 return -ENOMEM;
947 /* Obtain the address to map to. we verify (or select) it and ensure
948 * that it represents a valid section of the address space.
950 addr = get_unmapped_area(file, addr, len, pgoff, flags);
951 if (addr & ~PAGE_MASK)
952 return addr;
954 /* Do simple checking here so the lower-level routines won't have
955 * to. we assume access permissions have been handled by the open
956 * of the memory object, so we don't do any here.
958 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
959 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
961 if (flags & MAP_LOCKED)
962 if (!can_do_mlock())
963 return -EPERM;
965 /* mlock MCL_FUTURE? */
966 if (vm_flags & VM_LOCKED) {
967 unsigned long locked, lock_limit;
968 locked = len >> PAGE_SHIFT;
969 locked += mm->locked_vm;
970 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
971 lock_limit >>= PAGE_SHIFT;
972 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
973 return -EAGAIN;
976 inode = file ? file->f_path.dentry->d_inode : NULL;
978 if (file) {
979 switch (flags & MAP_TYPE) {
980 case MAP_SHARED:
981 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
982 return -EACCES;
985 * Make sure we don't allow writing to an append-only
986 * file..
988 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
989 return -EACCES;
992 * Make sure there are no mandatory locks on the file.
994 if (locks_verify_locked(inode))
995 return -EAGAIN;
997 vm_flags |= VM_SHARED | VM_MAYSHARE;
998 if (!(file->f_mode & FMODE_WRITE))
999 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1001 /* fall through */
1002 case MAP_PRIVATE:
1003 if (!(file->f_mode & FMODE_READ))
1004 return -EACCES;
1005 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1006 if (vm_flags & VM_EXEC)
1007 return -EPERM;
1008 vm_flags &= ~VM_MAYEXEC;
1011 if (!file->f_op || !file->f_op->mmap)
1012 return -ENODEV;
1013 break;
1015 default:
1016 return -EINVAL;
1018 } else {
1019 switch (flags & MAP_TYPE) {
1020 case MAP_SHARED:
1022 * Ignore pgoff.
1024 pgoff = 0;
1025 vm_flags |= VM_SHARED | VM_MAYSHARE;
1026 break;
1027 case MAP_PRIVATE:
1029 * Set pgoff according to addr for anon_vma.
1031 pgoff = addr >> PAGE_SHIFT;
1032 break;
1033 default:
1034 return -EINVAL;
1038 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1039 if (error)
1040 return error;
1042 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1044 EXPORT_SYMBOL(do_mmap_pgoff);
1047 * Some shared mappigns will want the pages marked read-only
1048 * to track write events. If so, we'll downgrade vm_page_prot
1049 * to the private version (using protection_map[] without the
1050 * VM_SHARED bit).
1052 int vma_wants_writenotify(struct vm_area_struct *vma)
1054 unsigned int vm_flags = vma->vm_flags;
1056 /* If it was private or non-writable, the write bit is already clear */
1057 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1058 return 0;
1060 /* The backer wishes to know when pages are first written to? */
1061 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1062 return 1;
1064 /* The open routine did something to the protections already? */
1065 if (pgprot_val(vma->vm_page_prot) !=
1066 pgprot_val(vm_get_page_prot(vm_flags)))
1067 return 0;
1069 /* Specialty mapping? */
1070 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1071 return 0;
1073 /* Can the mapping track the dirty pages? */
1074 return vma->vm_file && vma->vm_file->f_mapping &&
1075 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1079 * We account for memory if it's a private writeable mapping,
1080 * not hugepages and VM_NORESERVE wasn't set.
1082 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1085 * hugetlb has its own accounting separate from the core VM
1086 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1088 if (file && is_file_hugepages(file))
1089 return 0;
1091 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1094 unsigned long mmap_region(struct file *file, unsigned long addr,
1095 unsigned long len, unsigned long flags,
1096 unsigned int vm_flags, unsigned long pgoff)
1098 struct mm_struct *mm = current->mm;
1099 struct vm_area_struct *vma, *prev;
1100 int correct_wcount = 0;
1101 int error;
1102 struct rb_node **rb_link, *rb_parent;
1103 unsigned long charged = 0;
1104 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1106 /* Clear old maps */
1107 error = -ENOMEM;
1108 munmap_back:
1109 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1110 if (vma && vma->vm_start < addr + len) {
1111 if (do_munmap(mm, addr, len))
1112 return -ENOMEM;
1113 goto munmap_back;
1116 /* Check against address space limit. */
1117 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1118 return -ENOMEM;
1121 * Set 'VM_NORESERVE' if we should not account for the
1122 * memory use of this mapping.
1124 if ((flags & MAP_NORESERVE)) {
1125 /* We honor MAP_NORESERVE if allowed to overcommit */
1126 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1127 vm_flags |= VM_NORESERVE;
1129 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1130 if (file && is_file_hugepages(file))
1131 vm_flags |= VM_NORESERVE;
1135 * Private writable mapping: check memory availability
1137 if (accountable_mapping(file, vm_flags)) {
1138 charged = len >> PAGE_SHIFT;
1139 if (security_vm_enough_memory(charged))
1140 return -ENOMEM;
1141 vm_flags |= VM_ACCOUNT;
1145 * Can we just expand an old mapping?
1147 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1148 if (vma)
1149 goto out;
1152 * Determine the object being mapped and call the appropriate
1153 * specific mapper. the address has already been validated, but
1154 * not unmapped, but the maps are removed from the list.
1156 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1157 if (!vma) {
1158 error = -ENOMEM;
1159 goto unacct_error;
1162 vma->vm_mm = mm;
1163 vma->vm_start = addr;
1164 vma->vm_end = addr + len;
1165 vma->vm_flags = vm_flags;
1166 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1167 vma->vm_pgoff = pgoff;
1169 if (file) {
1170 error = -EINVAL;
1171 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1172 goto free_vma;
1173 if (vm_flags & VM_DENYWRITE) {
1174 error = deny_write_access(file);
1175 if (error)
1176 goto free_vma;
1177 correct_wcount = 1;
1179 vma->vm_file = file;
1180 get_file(file);
1181 error = file->f_op->mmap(file, vma);
1182 if (error)
1183 goto unmap_and_free_vma;
1184 if (vm_flags & VM_EXECUTABLE)
1185 added_exe_file_vma(mm);
1187 /* Can addr have changed??
1189 * Answer: Yes, several device drivers can do it in their
1190 * f_op->mmap method. -DaveM
1192 addr = vma->vm_start;
1193 pgoff = vma->vm_pgoff;
1194 vm_flags = vma->vm_flags;
1195 } else if (vm_flags & VM_SHARED) {
1196 error = shmem_zero_setup(vma);
1197 if (error)
1198 goto free_vma;
1201 if (vma_wants_writenotify(vma)) {
1202 pgprot_t pprot = vma->vm_page_prot;
1204 /* Can vma->vm_page_prot have changed??
1206 * Answer: Yes, drivers may have changed it in their
1207 * f_op->mmap method.
1209 * Ensures that vmas marked as uncached stay that way.
1211 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1212 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1213 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1216 vma_link(mm, vma, prev, rb_link, rb_parent);
1217 file = vma->vm_file;
1219 /* Once vma denies write, undo our temporary denial count */
1220 if (correct_wcount)
1221 atomic_inc(&inode->i_writecount);
1222 out:
1223 perf_event_mmap(vma);
1225 mm->total_vm += len >> PAGE_SHIFT;
1226 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1227 if (vm_flags & VM_LOCKED) {
1229 * makes pages present; downgrades, drops, reacquires mmap_sem
1231 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
1232 if (nr_pages < 0)
1233 return nr_pages; /* vma gone! */
1234 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
1235 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1236 make_pages_present(addr, addr + len);
1237 return addr;
1239 unmap_and_free_vma:
1240 if (correct_wcount)
1241 atomic_inc(&inode->i_writecount);
1242 vma->vm_file = NULL;
1243 fput(file);
1245 /* Undo any partial mapping done by a device driver. */
1246 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1247 charged = 0;
1248 free_vma:
1249 kmem_cache_free(vm_area_cachep, vma);
1250 unacct_error:
1251 if (charged)
1252 vm_unacct_memory(charged);
1253 return error;
1256 /* Get an address range which is currently unmapped.
1257 * For shmat() with addr=0.
1259 * Ugly calling convention alert:
1260 * Return value with the low bits set means error value,
1261 * ie
1262 * if (ret & ~PAGE_MASK)
1263 * error = ret;
1265 * This function "knows" that -ENOMEM has the bits set.
1267 #ifndef HAVE_ARCH_UNMAPPED_AREA
1268 unsigned long
1269 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1270 unsigned long len, unsigned long pgoff, unsigned long flags)
1272 struct mm_struct *mm = current->mm;
1273 struct vm_area_struct *vma;
1274 unsigned long start_addr;
1276 if (len > TASK_SIZE)
1277 return -ENOMEM;
1279 if (flags & MAP_FIXED)
1280 return addr;
1282 if (addr) {
1283 addr = PAGE_ALIGN(addr);
1284 vma = find_vma(mm, addr);
1285 if (TASK_SIZE - len >= addr &&
1286 (!vma || addr + len <= vma->vm_start))
1287 return addr;
1289 if (len > mm->cached_hole_size) {
1290 start_addr = addr = mm->free_area_cache;
1291 } else {
1292 start_addr = addr = TASK_UNMAPPED_BASE;
1293 mm->cached_hole_size = 0;
1296 full_search:
1297 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1298 /* At this point: (!vma || addr < vma->vm_end). */
1299 if (TASK_SIZE - len < addr) {
1301 * Start a new search - just in case we missed
1302 * some holes.
1304 if (start_addr != TASK_UNMAPPED_BASE) {
1305 addr = TASK_UNMAPPED_BASE;
1306 start_addr = addr;
1307 mm->cached_hole_size = 0;
1308 goto full_search;
1310 return -ENOMEM;
1312 if (!vma || addr + len <= vma->vm_start) {
1314 * Remember the place where we stopped the search:
1316 mm->free_area_cache = addr + len;
1317 return addr;
1319 if (addr + mm->cached_hole_size < vma->vm_start)
1320 mm->cached_hole_size = vma->vm_start - addr;
1321 addr = vma->vm_end;
1324 #endif
1326 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1329 * Is this a new hole at the lowest possible address?
1331 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1332 mm->free_area_cache = addr;
1333 mm->cached_hole_size = ~0UL;
1338 * This mmap-allocator allocates new areas top-down from below the
1339 * stack's low limit (the base):
1341 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1342 unsigned long
1343 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1344 const unsigned long len, const unsigned long pgoff,
1345 const unsigned long flags)
1347 struct vm_area_struct *vma;
1348 struct mm_struct *mm = current->mm;
1349 unsigned long addr = addr0;
1351 /* requested length too big for entire address space */
1352 if (len > TASK_SIZE)
1353 return -ENOMEM;
1355 if (flags & MAP_FIXED)
1356 return addr;
1358 /* requesting a specific address */
1359 if (addr) {
1360 addr = PAGE_ALIGN(addr);
1361 vma = find_vma(mm, addr);
1362 if (TASK_SIZE - len >= addr &&
1363 (!vma || addr + len <= vma->vm_start))
1364 return addr;
1367 /* check if free_area_cache is useful for us */
1368 if (len <= mm->cached_hole_size) {
1369 mm->cached_hole_size = 0;
1370 mm->free_area_cache = mm->mmap_base;
1373 /* either no address requested or can't fit in requested address hole */
1374 addr = mm->free_area_cache;
1376 /* make sure it can fit in the remaining address space */
1377 if (addr > len) {
1378 vma = find_vma(mm, addr-len);
1379 if (!vma || addr <= vma->vm_start)
1380 /* remember the address as a hint for next time */
1381 return (mm->free_area_cache = addr-len);
1384 if (mm->mmap_base < len)
1385 goto bottomup;
1387 addr = mm->mmap_base-len;
1389 do {
1391 * Lookup failure means no vma is above this address,
1392 * else if new region fits below vma->vm_start,
1393 * return with success:
1395 vma = find_vma(mm, addr);
1396 if (!vma || addr+len <= vma->vm_start)
1397 /* remember the address as a hint for next time */
1398 return (mm->free_area_cache = addr);
1400 /* remember the largest hole we saw so far */
1401 if (addr + mm->cached_hole_size < vma->vm_start)
1402 mm->cached_hole_size = vma->vm_start - addr;
1404 /* try just below the current vma->vm_start */
1405 addr = vma->vm_start-len;
1406 } while (len < vma->vm_start);
1408 bottomup:
1410 * A failed mmap() very likely causes application failure,
1411 * so fall back to the bottom-up function here. This scenario
1412 * can happen with large stack limits and large mmap()
1413 * allocations.
1415 mm->cached_hole_size = ~0UL;
1416 mm->free_area_cache = TASK_UNMAPPED_BASE;
1417 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1419 * Restore the topdown base:
1421 mm->free_area_cache = mm->mmap_base;
1422 mm->cached_hole_size = ~0UL;
1424 return addr;
1426 #endif
1428 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1431 * Is this a new hole at the highest possible address?
1433 if (addr > mm->free_area_cache)
1434 mm->free_area_cache = addr;
1436 /* dont allow allocations above current base */
1437 if (mm->free_area_cache > mm->mmap_base)
1438 mm->free_area_cache = mm->mmap_base;
1441 unsigned long
1442 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1443 unsigned long pgoff, unsigned long flags)
1445 unsigned long (*get_area)(struct file *, unsigned long,
1446 unsigned long, unsigned long, unsigned long);
1448 unsigned long error = arch_mmap_check(addr, len, flags);
1449 if (error)
1450 return error;
1452 /* Careful about overflows.. */
1453 if (len > TASK_SIZE)
1454 return -ENOMEM;
1456 get_area = current->mm->get_unmapped_area;
1457 if (file && file->f_op && file->f_op->get_unmapped_area)
1458 get_area = file->f_op->get_unmapped_area;
1459 addr = get_area(file, addr, len, pgoff, flags);
1460 if (IS_ERR_VALUE(addr))
1461 return addr;
1463 if (addr > TASK_SIZE - len)
1464 return -ENOMEM;
1465 if (addr & ~PAGE_MASK)
1466 return -EINVAL;
1468 return arch_rebalance_pgtables(addr, len);
1471 EXPORT_SYMBOL(get_unmapped_area);
1473 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1474 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1476 struct vm_area_struct *vma = NULL;
1478 if (mm) {
1479 /* Check the cache first. */
1480 /* (Cache hit rate is typically around 35%.) */
1481 vma = mm->mmap_cache;
1482 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1483 struct rb_node * rb_node;
1485 rb_node = mm->mm_rb.rb_node;
1486 vma = NULL;
1488 while (rb_node) {
1489 struct vm_area_struct * vma_tmp;
1491 vma_tmp = rb_entry(rb_node,
1492 struct vm_area_struct, vm_rb);
1494 if (vma_tmp->vm_end > addr) {
1495 vma = vma_tmp;
1496 if (vma_tmp->vm_start <= addr)
1497 break;
1498 rb_node = rb_node->rb_left;
1499 } else
1500 rb_node = rb_node->rb_right;
1502 if (vma)
1503 mm->mmap_cache = vma;
1506 return vma;
1509 EXPORT_SYMBOL(find_vma);
1511 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1512 struct vm_area_struct *
1513 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1514 struct vm_area_struct **pprev)
1516 struct vm_area_struct *vma = NULL, *prev = NULL;
1517 struct rb_node *rb_node;
1518 if (!mm)
1519 goto out;
1521 /* Guard against addr being lower than the first VMA */
1522 vma = mm->mmap;
1524 /* Go through the RB tree quickly. */
1525 rb_node = mm->mm_rb.rb_node;
1527 while (rb_node) {
1528 struct vm_area_struct *vma_tmp;
1529 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1531 if (addr < vma_tmp->vm_end) {
1532 rb_node = rb_node->rb_left;
1533 } else {
1534 prev = vma_tmp;
1535 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1536 break;
1537 rb_node = rb_node->rb_right;
1541 out:
1542 *pprev = prev;
1543 return prev ? prev->vm_next : vma;
1547 * Verify that the stack growth is acceptable and
1548 * update accounting. This is shared with both the
1549 * grow-up and grow-down cases.
1551 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1553 struct mm_struct *mm = vma->vm_mm;
1554 struct rlimit *rlim = current->signal->rlim;
1555 unsigned long new_start;
1557 /* address space limit tests */
1558 if (!may_expand_vm(mm, grow))
1559 return -ENOMEM;
1561 /* Stack limit test */
1562 if (size > rlim[RLIMIT_STACK].rlim_cur)
1563 return -ENOMEM;
1565 /* mlock limit tests */
1566 if (vma->vm_flags & VM_LOCKED) {
1567 unsigned long locked;
1568 unsigned long limit;
1569 locked = mm->locked_vm + grow;
1570 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1571 if (locked > limit && !capable(CAP_IPC_LOCK))
1572 return -ENOMEM;
1575 /* Check to ensure the stack will not grow into a hugetlb-only region */
1576 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1577 vma->vm_end - size;
1578 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1579 return -EFAULT;
1582 * Overcommit.. This must be the final test, as it will
1583 * update security statistics.
1585 if (security_vm_enough_memory_mm(mm, grow))
1586 return -ENOMEM;
1588 /* Ok, everything looks good - let it rip */
1589 mm->total_vm += grow;
1590 if (vma->vm_flags & VM_LOCKED)
1591 mm->locked_vm += grow;
1592 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1593 return 0;
1596 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1598 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1599 * vma is the last one with address > vma->vm_end. Have to extend vma.
1601 #ifndef CONFIG_IA64
1602 static
1603 #endif
1604 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1606 int error;
1608 if (!(vma->vm_flags & VM_GROWSUP))
1609 return -EFAULT;
1612 * We must make sure the anon_vma is allocated
1613 * so that the anon_vma locking is not a noop.
1615 if (unlikely(anon_vma_prepare(vma)))
1616 return -ENOMEM;
1617 anon_vma_lock(vma);
1620 * vma->vm_start/vm_end cannot change under us because the caller
1621 * is required to hold the mmap_sem in read mode. We need the
1622 * anon_vma lock to serialize against concurrent expand_stacks.
1623 * Also guard against wrapping around to address 0.
1625 if (address < PAGE_ALIGN(address+4))
1626 address = PAGE_ALIGN(address+4);
1627 else {
1628 anon_vma_unlock(vma);
1629 return -ENOMEM;
1631 error = 0;
1633 /* Somebody else might have raced and expanded it already */
1634 if (address > vma->vm_end) {
1635 unsigned long size, grow;
1637 size = address - vma->vm_start;
1638 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1640 error = acct_stack_growth(vma, size, grow);
1641 if (!error)
1642 vma->vm_end = address;
1644 anon_vma_unlock(vma);
1645 return error;
1647 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1650 * vma is the first one with address < vma->vm_start. Have to extend vma.
1652 static int expand_downwards(struct vm_area_struct *vma,
1653 unsigned long address)
1655 int error;
1658 * We must make sure the anon_vma is allocated
1659 * so that the anon_vma locking is not a noop.
1661 if (unlikely(anon_vma_prepare(vma)))
1662 return -ENOMEM;
1664 address &= PAGE_MASK;
1665 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1666 if (error)
1667 return error;
1669 anon_vma_lock(vma);
1672 * vma->vm_start/vm_end cannot change under us because the caller
1673 * is required to hold the mmap_sem in read mode. We need the
1674 * anon_vma lock to serialize against concurrent expand_stacks.
1677 /* Somebody else might have raced and expanded it already */
1678 if (address < vma->vm_start) {
1679 unsigned long size, grow;
1681 size = vma->vm_end - address;
1682 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1684 error = acct_stack_growth(vma, size, grow);
1685 if (!error) {
1686 vma->vm_start = address;
1687 vma->vm_pgoff -= grow;
1690 anon_vma_unlock(vma);
1691 return error;
1694 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1696 return expand_downwards(vma, address);
1699 #ifdef CONFIG_STACK_GROWSUP
1700 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1702 return expand_upwards(vma, address);
1705 struct vm_area_struct *
1706 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1708 struct vm_area_struct *vma, *prev;
1710 addr &= PAGE_MASK;
1711 vma = find_vma_prev(mm, addr, &prev);
1712 if (vma && (vma->vm_start <= addr))
1713 return vma;
1714 if (!prev || expand_stack(prev, addr))
1715 return NULL;
1716 if (prev->vm_flags & VM_LOCKED) {
1717 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
1718 return NULL; /* vma gone! */
1720 return prev;
1722 #else
1723 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1725 return expand_downwards(vma, address);
1728 struct vm_area_struct *
1729 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1731 struct vm_area_struct * vma;
1732 unsigned long start;
1734 addr &= PAGE_MASK;
1735 vma = find_vma(mm,addr);
1736 if (!vma)
1737 return NULL;
1738 if (vma->vm_start <= addr)
1739 return vma;
1740 if (!(vma->vm_flags & VM_GROWSDOWN))
1741 return NULL;
1742 start = vma->vm_start;
1743 if (expand_stack(vma, addr))
1744 return NULL;
1745 if (vma->vm_flags & VM_LOCKED) {
1746 if (mlock_vma_pages_range(vma, addr, start) < 0)
1747 return NULL; /* vma gone! */
1749 return vma;
1751 #endif
1754 * Ok - we have the memory areas we should free on the vma list,
1755 * so release them, and do the vma updates.
1757 * Called with the mm semaphore held.
1759 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1761 /* Update high watermark before we lower total_vm */
1762 update_hiwater_vm(mm);
1763 do {
1764 long nrpages = vma_pages(vma);
1766 mm->total_vm -= nrpages;
1767 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1768 vma = remove_vma(vma);
1769 } while (vma);
1770 validate_mm(mm);
1774 * Get rid of page table information in the indicated region.
1776 * Called with the mm semaphore held.
1778 static void unmap_region(struct mm_struct *mm,
1779 struct vm_area_struct *vma, struct vm_area_struct *prev,
1780 unsigned long start, unsigned long end)
1782 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1783 struct mmu_gather *tlb;
1784 unsigned long nr_accounted = 0;
1786 lru_add_drain();
1787 tlb = tlb_gather_mmu(mm, 0);
1788 update_hiwater_rss(mm);
1789 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1790 vm_unacct_memory(nr_accounted);
1791 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1792 next? next->vm_start: 0);
1793 tlb_finish_mmu(tlb, start, end);
1797 * Create a list of vma's touched by the unmap, removing them from the mm's
1798 * vma list as we go..
1800 static void
1801 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1802 struct vm_area_struct *prev, unsigned long end)
1804 struct vm_area_struct **insertion_point;
1805 struct vm_area_struct *tail_vma = NULL;
1806 unsigned long addr;
1808 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1809 do {
1810 rb_erase(&vma->vm_rb, &mm->mm_rb);
1811 mm->map_count--;
1812 tail_vma = vma;
1813 vma = vma->vm_next;
1814 } while (vma && vma->vm_start < end);
1815 *insertion_point = vma;
1816 tail_vma->vm_next = NULL;
1817 if (mm->unmap_area == arch_unmap_area)
1818 addr = prev ? prev->vm_end : mm->mmap_base;
1819 else
1820 addr = vma ? vma->vm_start : mm->mmap_base;
1821 mm->unmap_area(mm, addr);
1822 mm->mmap_cache = NULL; /* Kill the cache. */
1826 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1827 * munmap path where it doesn't make sense to fail.
1829 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1830 unsigned long addr, int new_below)
1832 struct mempolicy *pol;
1833 struct vm_area_struct *new;
1835 if (is_vm_hugetlb_page(vma) && (addr &
1836 ~(huge_page_mask(hstate_vma(vma)))))
1837 return -EINVAL;
1839 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1840 if (!new)
1841 return -ENOMEM;
1843 /* most fields are the same, copy all, and then fixup */
1844 *new = *vma;
1846 if (new_below)
1847 new->vm_end = addr;
1848 else {
1849 new->vm_start = addr;
1850 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1853 pol = mpol_dup(vma_policy(vma));
1854 if (IS_ERR(pol)) {
1855 kmem_cache_free(vm_area_cachep, new);
1856 return PTR_ERR(pol);
1858 vma_set_policy(new, pol);
1860 if (new->vm_file) {
1861 get_file(new->vm_file);
1862 if (vma->vm_flags & VM_EXECUTABLE)
1863 added_exe_file_vma(mm);
1866 if (new->vm_ops && new->vm_ops->open)
1867 new->vm_ops->open(new);
1869 if (new_below)
1870 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1871 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1872 else
1873 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1875 return 0;
1879 * Split a vma into two pieces at address 'addr', a new vma is allocated
1880 * either for the first part or the tail.
1882 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1883 unsigned long addr, int new_below)
1885 if (mm->map_count >= sysctl_max_map_count)
1886 return -ENOMEM;
1888 return __split_vma(mm, vma, addr, new_below);
1891 /* Munmap is split into 2 main parts -- this part which finds
1892 * what needs doing, and the areas themselves, which do the
1893 * work. This now handles partial unmappings.
1894 * Jeremy Fitzhardinge <jeremy@goop.org>
1896 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1898 unsigned long end;
1899 struct vm_area_struct *vma, *prev, *last;
1901 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1902 return -EINVAL;
1904 if ((len = PAGE_ALIGN(len)) == 0)
1905 return -EINVAL;
1907 /* Find the first overlapping VMA */
1908 vma = find_vma_prev(mm, start, &prev);
1909 if (!vma)
1910 return 0;
1911 /* we have start < vma->vm_end */
1913 /* if it doesn't overlap, we have nothing.. */
1914 end = start + len;
1915 if (vma->vm_start >= end)
1916 return 0;
1919 * If we need to split any vma, do it now to save pain later.
1921 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1922 * unmapped vm_area_struct will remain in use: so lower split_vma
1923 * places tmp vma above, and higher split_vma places tmp vma below.
1925 if (start > vma->vm_start) {
1926 int error;
1929 * Make sure that map_count on return from munmap() will
1930 * not exceed its limit; but let map_count go just above
1931 * its limit temporarily, to help free resources as expected.
1933 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
1934 return -ENOMEM;
1936 error = __split_vma(mm, vma, start, 0);
1937 if (error)
1938 return error;
1939 prev = vma;
1942 /* Does it split the last one? */
1943 last = find_vma(mm, end);
1944 if (last && end > last->vm_start) {
1945 int error = __split_vma(mm, last, end, 1);
1946 if (error)
1947 return error;
1949 vma = prev? prev->vm_next: mm->mmap;
1952 * unlock any mlock()ed ranges before detaching vmas
1954 if (mm->locked_vm) {
1955 struct vm_area_struct *tmp = vma;
1956 while (tmp && tmp->vm_start < end) {
1957 if (tmp->vm_flags & VM_LOCKED) {
1958 mm->locked_vm -= vma_pages(tmp);
1959 munlock_vma_pages_all(tmp);
1961 tmp = tmp->vm_next;
1966 * Remove the vma's, and unmap the actual pages
1968 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1969 unmap_region(mm, vma, prev, start, end);
1971 /* Fix up all other VM information */
1972 remove_vma_list(mm, vma);
1974 return 0;
1977 EXPORT_SYMBOL(do_munmap);
1979 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1981 int ret;
1982 struct mm_struct *mm = current->mm;
1984 profile_munmap(addr);
1986 down_write(&mm->mmap_sem);
1987 ret = do_munmap(mm, addr, len);
1988 up_write(&mm->mmap_sem);
1989 return ret;
1992 static inline void verify_mm_writelocked(struct mm_struct *mm)
1994 #ifdef CONFIG_DEBUG_VM
1995 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1996 WARN_ON(1);
1997 up_read(&mm->mmap_sem);
1999 #endif
2003 * this is really a simplified "do_mmap". it only handles
2004 * anonymous maps. eventually we may be able to do some
2005 * brk-specific accounting here.
2007 unsigned long do_brk(unsigned long addr, unsigned long len)
2009 struct mm_struct * mm = current->mm;
2010 struct vm_area_struct * vma, * prev;
2011 unsigned long flags;
2012 struct rb_node ** rb_link, * rb_parent;
2013 pgoff_t pgoff = addr >> PAGE_SHIFT;
2014 int error;
2016 len = PAGE_ALIGN(len);
2017 if (!len)
2018 return addr;
2020 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2021 if (error)
2022 return error;
2024 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2026 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2027 if (error & ~PAGE_MASK)
2028 return error;
2031 * mlock MCL_FUTURE?
2033 if (mm->def_flags & VM_LOCKED) {
2034 unsigned long locked, lock_limit;
2035 locked = len >> PAGE_SHIFT;
2036 locked += mm->locked_vm;
2037 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2038 lock_limit >>= PAGE_SHIFT;
2039 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2040 return -EAGAIN;
2044 * mm->mmap_sem is required to protect against another thread
2045 * changing the mappings in case we sleep.
2047 verify_mm_writelocked(mm);
2050 * Clear old maps. this also does some error checking for us
2052 munmap_back:
2053 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2054 if (vma && vma->vm_start < addr + len) {
2055 if (do_munmap(mm, addr, len))
2056 return -ENOMEM;
2057 goto munmap_back;
2060 /* Check against address space limits *after* clearing old maps... */
2061 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2062 return -ENOMEM;
2064 if (mm->map_count > sysctl_max_map_count)
2065 return -ENOMEM;
2067 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2068 return -ENOMEM;
2070 /* Can we just expand an old private anonymous mapping? */
2071 vma = vma_merge(mm, prev, addr, addr + len, flags,
2072 NULL, NULL, pgoff, NULL);
2073 if (vma)
2074 goto out;
2077 * create a vma struct for an anonymous mapping
2079 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2080 if (!vma) {
2081 vm_unacct_memory(len >> PAGE_SHIFT);
2082 return -ENOMEM;
2085 vma->vm_mm = mm;
2086 vma->vm_start = addr;
2087 vma->vm_end = addr + len;
2088 vma->vm_pgoff = pgoff;
2089 vma->vm_flags = flags;
2090 vma->vm_page_prot = vm_get_page_prot(flags);
2091 vma_link(mm, vma, prev, rb_link, rb_parent);
2092 out:
2093 mm->total_vm += len >> PAGE_SHIFT;
2094 if (flags & VM_LOCKED) {
2095 if (!mlock_vma_pages_range(vma, addr, addr + len))
2096 mm->locked_vm += (len >> PAGE_SHIFT);
2098 return addr;
2101 EXPORT_SYMBOL(do_brk);
2103 /* Release all mmaps. */
2104 void exit_mmap(struct mm_struct *mm)
2106 struct mmu_gather *tlb;
2107 struct vm_area_struct *vma;
2108 unsigned long nr_accounted = 0;
2109 unsigned long end;
2111 /* mm's last user has gone, and its about to be pulled down */
2112 mmu_notifier_release(mm);
2114 if (mm->locked_vm) {
2115 vma = mm->mmap;
2116 while (vma) {
2117 if (vma->vm_flags & VM_LOCKED)
2118 munlock_vma_pages_all(vma);
2119 vma = vma->vm_next;
2123 arch_exit_mmap(mm);
2125 vma = mm->mmap;
2126 if (!vma) /* Can happen if dup_mmap() received an OOM */
2127 return;
2129 lru_add_drain();
2130 flush_cache_mm(mm);
2131 tlb = tlb_gather_mmu(mm, 1);
2132 /* update_hiwater_rss(mm) here? but nobody should be looking */
2133 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2134 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2135 vm_unacct_memory(nr_accounted);
2137 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2138 tlb_finish_mmu(tlb, 0, end);
2141 * Walk the list again, actually closing and freeing it,
2142 * with preemption enabled, without holding any MM locks.
2144 while (vma)
2145 vma = remove_vma(vma);
2147 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2150 /* Insert vm structure into process list sorted by address
2151 * and into the inode's i_mmap tree. If vm_file is non-NULL
2152 * then i_mmap_lock is taken here.
2154 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2156 struct vm_area_struct * __vma, * prev;
2157 struct rb_node ** rb_link, * rb_parent;
2160 * The vm_pgoff of a purely anonymous vma should be irrelevant
2161 * until its first write fault, when page's anon_vma and index
2162 * are set. But now set the vm_pgoff it will almost certainly
2163 * end up with (unless mremap moves it elsewhere before that
2164 * first wfault), so /proc/pid/maps tells a consistent story.
2166 * By setting it to reflect the virtual start address of the
2167 * vma, merges and splits can happen in a seamless way, just
2168 * using the existing file pgoff checks and manipulations.
2169 * Similarly in do_mmap_pgoff and in do_brk.
2171 if (!vma->vm_file) {
2172 BUG_ON(vma->anon_vma);
2173 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2175 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2176 if (__vma && __vma->vm_start < vma->vm_end)
2177 return -ENOMEM;
2178 if ((vma->vm_flags & VM_ACCOUNT) &&
2179 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2180 return -ENOMEM;
2181 vma_link(mm, vma, prev, rb_link, rb_parent);
2182 return 0;
2186 * Copy the vma structure to a new location in the same mm,
2187 * prior to moving page table entries, to effect an mremap move.
2189 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2190 unsigned long addr, unsigned long len, pgoff_t pgoff)
2192 struct vm_area_struct *vma = *vmap;
2193 unsigned long vma_start = vma->vm_start;
2194 struct mm_struct *mm = vma->vm_mm;
2195 struct vm_area_struct *new_vma, *prev;
2196 struct rb_node **rb_link, *rb_parent;
2197 struct mempolicy *pol;
2200 * If anonymous vma has not yet been faulted, update new pgoff
2201 * to match new location, to increase its chance of merging.
2203 if (!vma->vm_file && !vma->anon_vma)
2204 pgoff = addr >> PAGE_SHIFT;
2206 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2207 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2208 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2209 if (new_vma) {
2211 * Source vma may have been merged into new_vma
2213 if (vma_start >= new_vma->vm_start &&
2214 vma_start < new_vma->vm_end)
2215 *vmap = new_vma;
2216 } else {
2217 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2218 if (new_vma) {
2219 *new_vma = *vma;
2220 pol = mpol_dup(vma_policy(vma));
2221 if (IS_ERR(pol)) {
2222 kmem_cache_free(vm_area_cachep, new_vma);
2223 return NULL;
2225 vma_set_policy(new_vma, pol);
2226 new_vma->vm_start = addr;
2227 new_vma->vm_end = addr + len;
2228 new_vma->vm_pgoff = pgoff;
2229 if (new_vma->vm_file) {
2230 get_file(new_vma->vm_file);
2231 if (vma->vm_flags & VM_EXECUTABLE)
2232 added_exe_file_vma(mm);
2234 if (new_vma->vm_ops && new_vma->vm_ops->open)
2235 new_vma->vm_ops->open(new_vma);
2236 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2239 return new_vma;
2243 * Return true if the calling process may expand its vm space by the passed
2244 * number of pages
2246 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2248 unsigned long cur = mm->total_vm; /* pages */
2249 unsigned long lim;
2251 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2253 if (cur + npages > lim)
2254 return 0;
2255 return 1;
2259 static int special_mapping_fault(struct vm_area_struct *vma,
2260 struct vm_fault *vmf)
2262 pgoff_t pgoff;
2263 struct page **pages;
2266 * special mappings have no vm_file, and in that case, the mm
2267 * uses vm_pgoff internally. So we have to subtract it from here.
2268 * We are allowed to do this because we are the mm; do not copy
2269 * this code into drivers!
2271 pgoff = vmf->pgoff - vma->vm_pgoff;
2273 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2274 pgoff--;
2276 if (*pages) {
2277 struct page *page = *pages;
2278 get_page(page);
2279 vmf->page = page;
2280 return 0;
2283 return VM_FAULT_SIGBUS;
2287 * Having a close hook prevents vma merging regardless of flags.
2289 static void special_mapping_close(struct vm_area_struct *vma)
2293 static const struct vm_operations_struct special_mapping_vmops = {
2294 .close = special_mapping_close,
2295 .fault = special_mapping_fault,
2299 * Called with mm->mmap_sem held for writing.
2300 * Insert a new vma covering the given region, with the given flags.
2301 * Its pages are supplied by the given array of struct page *.
2302 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2303 * The region past the last page supplied will always produce SIGBUS.
2304 * The array pointer and the pages it points to are assumed to stay alive
2305 * for as long as this mapping might exist.
2307 int install_special_mapping(struct mm_struct *mm,
2308 unsigned long addr, unsigned long len,
2309 unsigned long vm_flags, struct page **pages)
2311 struct vm_area_struct *vma;
2313 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2314 if (unlikely(vma == NULL))
2315 return -ENOMEM;
2317 vma->vm_mm = mm;
2318 vma->vm_start = addr;
2319 vma->vm_end = addr + len;
2321 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2322 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2324 vma->vm_ops = &special_mapping_vmops;
2325 vma->vm_private_data = pages;
2327 if (unlikely(insert_vm_struct(mm, vma))) {
2328 kmem_cache_free(vm_area_cachep, vma);
2329 return -ENOMEM;
2332 mm->total_vm += len >> PAGE_SHIFT;
2334 perf_event_mmap(vma);
2336 return 0;
2339 static DEFINE_MUTEX(mm_all_locks_mutex);
2341 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2343 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2345 * The LSB of head.next can't change from under us
2346 * because we hold the mm_all_locks_mutex.
2348 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2350 * We can safely modify head.next after taking the
2351 * anon_vma->lock. If some other vma in this mm shares
2352 * the same anon_vma we won't take it again.
2354 * No need of atomic instructions here, head.next
2355 * can't change from under us thanks to the
2356 * anon_vma->lock.
2358 if (__test_and_set_bit(0, (unsigned long *)
2359 &anon_vma->head.next))
2360 BUG();
2364 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2366 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2368 * AS_MM_ALL_LOCKS can't change from under us because
2369 * we hold the mm_all_locks_mutex.
2371 * Operations on ->flags have to be atomic because
2372 * even if AS_MM_ALL_LOCKS is stable thanks to the
2373 * mm_all_locks_mutex, there may be other cpus
2374 * changing other bitflags in parallel to us.
2376 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2377 BUG();
2378 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2383 * This operation locks against the VM for all pte/vma/mm related
2384 * operations that could ever happen on a certain mm. This includes
2385 * vmtruncate, try_to_unmap, and all page faults.
2387 * The caller must take the mmap_sem in write mode before calling
2388 * mm_take_all_locks(). The caller isn't allowed to release the
2389 * mmap_sem until mm_drop_all_locks() returns.
2391 * mmap_sem in write mode is required in order to block all operations
2392 * that could modify pagetables and free pages without need of
2393 * altering the vma layout (for example populate_range() with
2394 * nonlinear vmas). It's also needed in write mode to avoid new
2395 * anon_vmas to be associated with existing vmas.
2397 * A single task can't take more than one mm_take_all_locks() in a row
2398 * or it would deadlock.
2400 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2401 * mapping->flags avoid to take the same lock twice, if more than one
2402 * vma in this mm is backed by the same anon_vma or address_space.
2404 * We can take all the locks in random order because the VM code
2405 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2406 * takes more than one of them in a row. Secondly we're protected
2407 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2409 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2410 * that may have to take thousand of locks.
2412 * mm_take_all_locks() can fail if it's interrupted by signals.
2414 int mm_take_all_locks(struct mm_struct *mm)
2416 struct vm_area_struct *vma;
2417 int ret = -EINTR;
2419 BUG_ON(down_read_trylock(&mm->mmap_sem));
2421 mutex_lock(&mm_all_locks_mutex);
2423 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2424 if (signal_pending(current))
2425 goto out_unlock;
2426 if (vma->vm_file && vma->vm_file->f_mapping)
2427 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2430 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2431 if (signal_pending(current))
2432 goto out_unlock;
2433 if (vma->anon_vma)
2434 vm_lock_anon_vma(mm, vma->anon_vma);
2437 ret = 0;
2439 out_unlock:
2440 if (ret)
2441 mm_drop_all_locks(mm);
2443 return ret;
2446 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2448 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2450 * The LSB of head.next can't change to 0 from under
2451 * us because we hold the mm_all_locks_mutex.
2453 * We must however clear the bitflag before unlocking
2454 * the vma so the users using the anon_vma->head will
2455 * never see our bitflag.
2457 * No need of atomic instructions here, head.next
2458 * can't change from under us until we release the
2459 * anon_vma->lock.
2461 if (!__test_and_clear_bit(0, (unsigned long *)
2462 &anon_vma->head.next))
2463 BUG();
2464 spin_unlock(&anon_vma->lock);
2468 static void vm_unlock_mapping(struct address_space *mapping)
2470 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2472 * AS_MM_ALL_LOCKS can't change to 0 from under us
2473 * because we hold the mm_all_locks_mutex.
2475 spin_unlock(&mapping->i_mmap_lock);
2476 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2477 &mapping->flags))
2478 BUG();
2483 * The mmap_sem cannot be released by the caller until
2484 * mm_drop_all_locks() returns.
2486 void mm_drop_all_locks(struct mm_struct *mm)
2488 struct vm_area_struct *vma;
2490 BUG_ON(down_read_trylock(&mm->mmap_sem));
2491 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2493 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2494 if (vma->anon_vma)
2495 vm_unlock_anon_vma(vma->anon_vma);
2496 if (vma->vm_file && vma->vm_file->f_mapping)
2497 vm_unlock_mapping(vma->vm_file->f_mapping);
2500 mutex_unlock(&mm_all_locks_mutex);
2504 * initialise the VMA slab
2506 void __init mmap_init(void)
2508 int ret;
2510 ret = percpu_counter_init(&vm_committed_as, 0);
2511 VM_BUG_ON(ret);