6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 #include <linux/slab.h>
10 #include <linux/backing-dev.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>
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>
31 #include <linux/audit.h>
32 #include <linux/khugepaged.h>
34 #include <asm/uaccess.h>
35 #include <asm/cacheflush.h>
37 #include <asm/mmu_context.h>
41 #ifndef arch_mmap_check
42 #define arch_mmap_check(addr, len, flags) (0)
45 #ifndef arch_rebalance_pgtables
46 #define arch_rebalance_pgtables(addr, len) (addr)
49 static void unmap_region(struct mm_struct *mm,
50 struct vm_area_struct *vma, struct vm_area_struct *prev,
51 unsigned long start, unsigned long end);
54 * WARNING: the debugging will use recursive algorithms so never enable this
55 * unless you know what you are doing.
59 /* description of effects of mapping type and prot in current implementation.
60 * this is due to the limited x86 page protection hardware. The expected
61 * behavior is in parens:
64 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
65 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
66 * w: (no) no w: (no) no w: (yes) yes w: (no) no
67 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
69 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
70 * w: (no) no w: (no) no w: (copy) copy w: (no) no
71 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
74 pgprot_t protection_map[16] = {
75 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
76 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
79 pgprot_t vm_get_page_prot(unsigned long vm_flags)
81 return __pgprot(pgprot_val(protection_map[vm_flags &
82 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
83 pgprot_val(arch_vm_get_page_prot(vm_flags)));
85 EXPORT_SYMBOL(vm_get_page_prot);
87 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
88 int sysctl_overcommit_ratio = 50; /* default is 50% */
89 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
90 struct percpu_counter vm_committed_as;
93 * Check that a process has enough memory to allocate a new virtual
94 * mapping. 0 means there is enough memory for the allocation to
95 * succeed and -ENOMEM implies there is not.
97 * We currently support three overcommit policies, which are set via the
98 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
100 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
101 * Additional code 2002 Jul 20 by Robert Love.
103 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
105 * Note this is a helper function intended to be used by LSMs which
106 * wish to use this logic.
108 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
110 unsigned long free, allowed;
112 vm_acct_memory(pages);
115 * Sometimes we want to use more memory than we have
117 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
120 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
123 free = global_page_state(NR_FILE_PAGES);
124 free += nr_swap_pages;
127 * Any slabs which are created with the
128 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
129 * which are reclaimable, under pressure. The dentry
130 * cache and most inode caches should fall into this
132 free += global_page_state(NR_SLAB_RECLAIMABLE);
135 * Leave the last 3% for root
144 * nr_free_pages() is very expensive on large systems,
145 * only call if we're about to fail.
150 * Leave reserved pages. The pages are not for anonymous pages.
152 if (n <= totalreserve_pages)
155 n -= totalreserve_pages;
158 * Leave the last 3% for root
170 allowed = (totalram_pages - hugetlb_total_pages())
171 * sysctl_overcommit_ratio / 100;
173 * Leave the last 3% for root
176 allowed -= allowed / 32;
177 allowed += total_swap_pages;
179 /* Don't let a single process grow too big:
180 leave 3% of the size of this process for other processes */
182 allowed -= mm->total_vm / 32;
184 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
187 vm_unacct_memory(pages);
193 * Requires inode->i_mapping->i_mmap_lock
195 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
196 struct file *file, struct address_space *mapping)
198 if (vma->vm_flags & VM_DENYWRITE)
199 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
200 if (vma->vm_flags & VM_SHARED)
201 mapping->i_mmap_writable--;
203 flush_dcache_mmap_lock(mapping);
204 if (unlikely(vma->vm_flags & VM_NONLINEAR))
205 list_del_init(&vma->shared.vm_set.list);
207 vma_prio_tree_remove(vma, &mapping->i_mmap);
208 flush_dcache_mmap_unlock(mapping);
212 * Unlink a file-based vm structure from its prio_tree, to hide
213 * vma from rmap and vmtruncate before freeing its page tables.
215 void unlink_file_vma(struct vm_area_struct *vma)
217 struct file *file = vma->vm_file;
220 struct address_space *mapping = file->f_mapping;
221 spin_lock(&mapping->i_mmap_lock);
222 __remove_shared_vm_struct(vma, file, mapping);
223 spin_unlock(&mapping->i_mmap_lock);
228 * Close a vm structure and free it, returning the next.
230 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
232 struct vm_area_struct *next = vma->vm_next;
235 if (vma->vm_ops && vma->vm_ops->close)
236 vma->vm_ops->close(vma);
239 if (vma->vm_flags & VM_EXECUTABLE)
240 removed_exe_file_vma(vma->vm_mm);
242 mpol_put(vma_policy(vma));
243 kmem_cache_free(vm_area_cachep, vma);
247 SYSCALL_DEFINE1(brk, unsigned long, brk)
249 unsigned long rlim, retval;
250 unsigned long newbrk, oldbrk;
251 struct mm_struct *mm = current->mm;
252 unsigned long min_brk;
254 down_write(&mm->mmap_sem);
256 #ifdef CONFIG_COMPAT_BRK
257 min_brk = mm->end_code;
259 min_brk = mm->start_brk;
265 * Check against rlimit here. If this check is done later after the test
266 * of oldbrk with newbrk then it can escape the test and let the data
267 * segment grow beyond its set limit the in case where the limit is
268 * not page aligned -Ram Gupta
270 rlim = rlimit(RLIMIT_DATA);
271 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
272 (mm->end_data - mm->start_data) > rlim)
275 newbrk = PAGE_ALIGN(brk);
276 oldbrk = PAGE_ALIGN(mm->brk);
277 if (oldbrk == newbrk)
280 /* Always allow shrinking brk. */
281 if (brk <= mm->brk) {
282 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
287 /* Check against existing mmap mappings. */
288 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
291 /* Ok, looks good - let it rip. */
292 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
298 up_write(&mm->mmap_sem);
303 static int browse_rb(struct rb_root *root)
306 struct rb_node *nd, *pn = NULL;
307 unsigned long prev = 0, pend = 0;
309 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
310 struct vm_area_struct *vma;
311 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
312 if (vma->vm_start < prev)
313 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
314 if (vma->vm_start < pend)
315 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
316 if (vma->vm_start > vma->vm_end)
317 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
320 prev = vma->vm_start;
324 for (nd = pn; nd; nd = rb_prev(nd)) {
328 printk("backwards %d, forwards %d\n", j, i), i = 0;
332 void validate_mm(struct mm_struct *mm)
336 struct vm_area_struct *tmp = mm->mmap;
341 if (i != mm->map_count)
342 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
343 i = browse_rb(&mm->mm_rb);
344 if (i != mm->map_count)
345 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
349 #define validate_mm(mm) do { } while (0)
352 static struct vm_area_struct *
353 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
354 struct vm_area_struct **pprev, struct rb_node ***rb_link,
355 struct rb_node ** rb_parent)
357 struct vm_area_struct * vma;
358 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
360 __rb_link = &mm->mm_rb.rb_node;
361 rb_prev = __rb_parent = NULL;
365 struct vm_area_struct *vma_tmp;
367 __rb_parent = *__rb_link;
368 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
370 if (vma_tmp->vm_end > addr) {
372 if (vma_tmp->vm_start <= addr)
374 __rb_link = &__rb_parent->rb_left;
376 rb_prev = __rb_parent;
377 __rb_link = &__rb_parent->rb_right;
383 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
384 *rb_link = __rb_link;
385 *rb_parent = __rb_parent;
390 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
391 struct vm_area_struct *prev, struct rb_node *rb_parent)
393 struct vm_area_struct *next;
397 next = prev->vm_next;
402 next = rb_entry(rb_parent,
403 struct vm_area_struct, vm_rb);
412 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
413 struct rb_node **rb_link, struct rb_node *rb_parent)
415 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
416 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
419 static void __vma_link_file(struct vm_area_struct *vma)
425 struct address_space *mapping = file->f_mapping;
427 if (vma->vm_flags & VM_DENYWRITE)
428 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
429 if (vma->vm_flags & VM_SHARED)
430 mapping->i_mmap_writable++;
432 flush_dcache_mmap_lock(mapping);
433 if (unlikely(vma->vm_flags & VM_NONLINEAR))
434 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
436 vma_prio_tree_insert(vma, &mapping->i_mmap);
437 flush_dcache_mmap_unlock(mapping);
442 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
443 struct vm_area_struct *prev, struct rb_node **rb_link,
444 struct rb_node *rb_parent)
446 __vma_link_list(mm, vma, prev, rb_parent);
447 __vma_link_rb(mm, vma, rb_link, rb_parent);
450 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
451 struct vm_area_struct *prev, struct rb_node **rb_link,
452 struct rb_node *rb_parent)
454 struct address_space *mapping = NULL;
457 mapping = vma->vm_file->f_mapping;
460 spin_lock(&mapping->i_mmap_lock);
461 vma->vm_truncate_count = mapping->truncate_count;
464 __vma_link(mm, vma, prev, rb_link, rb_parent);
465 __vma_link_file(vma);
468 spin_unlock(&mapping->i_mmap_lock);
475 * Helper for vma_adjust in the split_vma insert case:
476 * insert vm structure into list and rbtree and anon_vma,
477 * but it has already been inserted into prio_tree earlier.
479 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
481 struct vm_area_struct *__vma, *prev;
482 struct rb_node **rb_link, *rb_parent;
484 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
485 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
486 __vma_link(mm, vma, prev, rb_link, rb_parent);
491 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
492 struct vm_area_struct *prev)
494 struct vm_area_struct *next = vma->vm_next;
496 prev->vm_next = next;
498 next->vm_prev = prev;
499 rb_erase(&vma->vm_rb, &mm->mm_rb);
500 if (mm->mmap_cache == vma)
501 mm->mmap_cache = prev;
505 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
506 * is already present in an i_mmap tree without adjusting the tree.
507 * The following helper function should be used when such adjustments
508 * are necessary. The "insert" vma (if any) is to be inserted
509 * before we drop the necessary locks.
511 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
512 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
514 struct mm_struct *mm = vma->vm_mm;
515 struct vm_area_struct *next = vma->vm_next;
516 struct vm_area_struct *importer = NULL;
517 struct address_space *mapping = NULL;
518 struct prio_tree_root *root = NULL;
519 struct anon_vma *anon_vma = NULL;
520 struct file *file = vma->vm_file;
521 long adjust_next = 0;
524 if (next && !insert) {
525 struct vm_area_struct *exporter = NULL;
527 if (end >= next->vm_end) {
529 * vma expands, overlapping all the next, and
530 * perhaps the one after too (mprotect case 6).
532 again: remove_next = 1 + (end > next->vm_end);
536 } else if (end > next->vm_start) {
538 * vma expands, overlapping part of the next:
539 * mprotect case 5 shifting the boundary up.
541 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
544 } else if (end < vma->vm_end) {
546 * vma shrinks, and !insert tells it's not
547 * split_vma inserting another: so it must be
548 * mprotect case 4 shifting the boundary down.
550 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
556 * Easily overlooked: when mprotect shifts the boundary,
557 * make sure the expanding vma has anon_vma set if the
558 * shrinking vma had, to cover any anon pages imported.
560 if (exporter && exporter->anon_vma && !importer->anon_vma) {
561 if (anon_vma_clone(importer, exporter))
563 importer->anon_vma = exporter->anon_vma;
568 mapping = file->f_mapping;
569 if (!(vma->vm_flags & VM_NONLINEAR))
570 root = &mapping->i_mmap;
571 spin_lock(&mapping->i_mmap_lock);
573 vma->vm_truncate_count != next->vm_truncate_count) {
575 * unmap_mapping_range might be in progress:
576 * ensure that the expanding vma is rescanned.
578 importer->vm_truncate_count = 0;
581 insert->vm_truncate_count = vma->vm_truncate_count;
583 * Put into prio_tree now, so instantiated pages
584 * are visible to arm/parisc __flush_dcache_page
585 * throughout; but we cannot insert into address
586 * space until vma start or end is updated.
588 __vma_link_file(insert);
593 * When changing only vma->vm_end, we don't really need anon_vma
594 * lock. This is a fairly rare case by itself, but the anon_vma
595 * lock may be shared between many sibling processes. Skipping
596 * the lock for brk adjustments makes a difference sometimes.
598 if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
599 anon_vma = vma->anon_vma;
600 anon_vma_lock(anon_vma);
604 flush_dcache_mmap_lock(mapping);
605 vma_prio_tree_remove(vma, root);
607 vma_prio_tree_remove(next, root);
610 vma->vm_start = start;
612 vma->vm_pgoff = pgoff;
614 next->vm_start += adjust_next << PAGE_SHIFT;
615 next->vm_pgoff += adjust_next;
620 vma_prio_tree_insert(next, root);
621 vma_prio_tree_insert(vma, root);
622 flush_dcache_mmap_unlock(mapping);
627 * vma_merge has merged next into vma, and needs
628 * us to remove next before dropping the locks.
630 __vma_unlink(mm, next, vma);
632 __remove_shared_vm_struct(next, file, mapping);
635 * split_vma has split insert from vma, and needs
636 * us to insert it before dropping the locks
637 * (it may either follow vma or precede it).
639 __insert_vm_struct(mm, insert);
643 anon_vma_unlock(anon_vma);
645 spin_unlock(&mapping->i_mmap_lock);
650 if (next->vm_flags & VM_EXECUTABLE)
651 removed_exe_file_vma(mm);
654 anon_vma_merge(vma, next);
656 mpol_put(vma_policy(next));
657 kmem_cache_free(vm_area_cachep, next);
659 * In mprotect's case 6 (see comments on vma_merge),
660 * we must remove another next too. It would clutter
661 * up the code too much to do both in one go.
663 if (remove_next == 2) {
675 * If the vma has a ->close operation then the driver probably needs to release
676 * per-vma resources, so we don't attempt to merge those.
678 static inline int is_mergeable_vma(struct vm_area_struct *vma,
679 struct file *file, unsigned long vm_flags)
681 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
682 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
684 if (vma->vm_file != file)
686 if (vma->vm_ops && vma->vm_ops->close)
691 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
692 struct anon_vma *anon_vma2)
694 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
698 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
699 * in front of (at a lower virtual address and file offset than) the vma.
701 * We cannot merge two vmas if they have differently assigned (non-NULL)
702 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
704 * We don't check here for the merged mmap wrapping around the end of pagecache
705 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
706 * wrap, nor mmaps which cover the final page at index -1UL.
709 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
710 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
712 if (is_mergeable_vma(vma, file, vm_flags) &&
713 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
714 if (vma->vm_pgoff == vm_pgoff)
721 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
722 * beyond (at a higher virtual address and file offset than) the vma.
724 * We cannot merge two vmas if they have differently assigned (non-NULL)
725 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
728 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
729 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
731 if (is_mergeable_vma(vma, file, vm_flags) &&
732 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
734 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
735 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
742 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
743 * whether that can be merged with its predecessor or its successor.
744 * Or both (it neatly fills a hole).
746 * In most cases - when called for mmap, brk or mremap - [addr,end) is
747 * certain not to be mapped by the time vma_merge is called; but when
748 * called for mprotect, it is certain to be already mapped (either at
749 * an offset within prev, or at the start of next), and the flags of
750 * this area are about to be changed to vm_flags - and the no-change
751 * case has already been eliminated.
753 * The following mprotect cases have to be considered, where AAAA is
754 * the area passed down from mprotect_fixup, never extending beyond one
755 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
757 * AAAA AAAA AAAA AAAA
758 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
759 * cannot merge might become might become might become
760 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
761 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
762 * mremap move: PPPPNNNNNNNN 8
764 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
765 * might become case 1 below case 2 below case 3 below
767 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
768 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
770 struct vm_area_struct *vma_merge(struct mm_struct *mm,
771 struct vm_area_struct *prev, unsigned long addr,
772 unsigned long end, unsigned long vm_flags,
773 struct anon_vma *anon_vma, struct file *file,
774 pgoff_t pgoff, struct mempolicy *policy)
776 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
777 struct vm_area_struct *area, *next;
781 * We later require that vma->vm_flags == vm_flags,
782 * so this tests vma->vm_flags & VM_SPECIAL, too.
784 if (vm_flags & VM_SPECIAL)
788 next = prev->vm_next;
792 if (next && next->vm_end == end) /* cases 6, 7, 8 */
793 next = next->vm_next;
796 * Can it merge with the predecessor?
798 if (prev && prev->vm_end == addr &&
799 mpol_equal(vma_policy(prev), policy) &&
800 can_vma_merge_after(prev, vm_flags,
801 anon_vma, file, pgoff)) {
803 * OK, it can. Can we now merge in the successor as well?
805 if (next && end == next->vm_start &&
806 mpol_equal(policy, vma_policy(next)) &&
807 can_vma_merge_before(next, vm_flags,
808 anon_vma, file, pgoff+pglen) &&
809 is_mergeable_anon_vma(prev->anon_vma,
812 err = vma_adjust(prev, prev->vm_start,
813 next->vm_end, prev->vm_pgoff, NULL);
814 } else /* cases 2, 5, 7 */
815 err = vma_adjust(prev, prev->vm_start,
816 end, prev->vm_pgoff, NULL);
819 khugepaged_enter_vma_merge(prev);
824 * Can this new request be merged in front of next?
826 if (next && end == next->vm_start &&
827 mpol_equal(policy, vma_policy(next)) &&
828 can_vma_merge_before(next, vm_flags,
829 anon_vma, file, pgoff+pglen)) {
830 if (prev && addr < prev->vm_end) /* case 4 */
831 err = vma_adjust(prev, prev->vm_start,
832 addr, prev->vm_pgoff, NULL);
833 else /* cases 3, 8 */
834 err = vma_adjust(area, addr, next->vm_end,
835 next->vm_pgoff - pglen, NULL);
838 khugepaged_enter_vma_merge(area);
846 * Rough compatbility check to quickly see if it's even worth looking
847 * at sharing an anon_vma.
849 * They need to have the same vm_file, and the flags can only differ
850 * in things that mprotect may change.
852 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
853 * we can merge the two vma's. For example, we refuse to merge a vma if
854 * there is a vm_ops->close() function, because that indicates that the
855 * driver is doing some kind of reference counting. But that doesn't
856 * really matter for the anon_vma sharing case.
858 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
860 return a->vm_end == b->vm_start &&
861 mpol_equal(vma_policy(a), vma_policy(b)) &&
862 a->vm_file == b->vm_file &&
863 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
864 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
868 * Do some basic sanity checking to see if we can re-use the anon_vma
869 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
870 * the same as 'old', the other will be the new one that is trying
871 * to share the anon_vma.
873 * NOTE! This runs with mm_sem held for reading, so it is possible that
874 * the anon_vma of 'old' is concurrently in the process of being set up
875 * by another page fault trying to merge _that_. But that's ok: if it
876 * is being set up, that automatically means that it will be a singleton
877 * acceptable for merging, so we can do all of this optimistically. But
878 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
880 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
881 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
882 * is to return an anon_vma that is "complex" due to having gone through
885 * We also make sure that the two vma's are compatible (adjacent,
886 * and with the same memory policies). That's all stable, even with just
887 * a read lock on the mm_sem.
889 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
891 if (anon_vma_compatible(a, b)) {
892 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
894 if (anon_vma && list_is_singular(&old->anon_vma_chain))
901 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
902 * neighbouring vmas for a suitable anon_vma, before it goes off
903 * to allocate a new anon_vma. It checks because a repetitive
904 * sequence of mprotects and faults may otherwise lead to distinct
905 * anon_vmas being allocated, preventing vma merge in subsequent
908 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
910 struct anon_vma *anon_vma;
911 struct vm_area_struct *near;
917 anon_vma = reusable_anon_vma(near, vma, near);
922 * It is potentially slow to have to call find_vma_prev here.
923 * But it's only on the first write fault on the vma, not
924 * every time, and we could devise a way to avoid it later
925 * (e.g. stash info in next's anon_vma_node when assigning
926 * an anon_vma, or when trying vma_merge). Another time.
928 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
932 anon_vma = reusable_anon_vma(near, near, vma);
937 * There's no absolute need to look only at touching neighbours:
938 * we could search further afield for "compatible" anon_vmas.
939 * But it would probably just be a waste of time searching,
940 * or lead to too many vmas hanging off the same anon_vma.
941 * We're trying to allow mprotect remerging later on,
942 * not trying to minimize memory used for anon_vmas.
947 #ifdef CONFIG_PROC_FS
948 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
949 struct file *file, long pages)
951 const unsigned long stack_flags
952 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
955 mm->shared_vm += pages;
956 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
957 mm->exec_vm += pages;
958 } else if (flags & stack_flags)
959 mm->stack_vm += pages;
960 if (flags & (VM_RESERVED|VM_IO))
961 mm->reserved_vm += pages;
963 #endif /* CONFIG_PROC_FS */
966 * The caller must hold down_write(¤t->mm->mmap_sem).
969 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
970 unsigned long len, unsigned long prot,
971 unsigned long flags, unsigned long pgoff)
973 struct mm_struct * mm = current->mm;
975 unsigned int vm_flags;
977 unsigned long reqprot = prot;
980 * Does the application expect PROT_READ to imply PROT_EXEC?
982 * (the exception is when the underlying filesystem is noexec
983 * mounted, in which case we dont add PROT_EXEC.)
985 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
986 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
992 if (!(flags & MAP_FIXED))
993 addr = round_hint_to_min(addr);
995 /* Careful about overflows.. */
996 len = PAGE_ALIGN(len);
1000 /* offset overflow? */
1001 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1004 /* Too many mappings? */
1005 if (mm->map_count > sysctl_max_map_count)
1008 /* Obtain the address to map to. we verify (or select) it and ensure
1009 * that it represents a valid section of the address space.
1011 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1012 if (addr & ~PAGE_MASK)
1015 /* Do simple checking here so the lower-level routines won't have
1016 * to. we assume access permissions have been handled by the open
1017 * of the memory object, so we don't do any here.
1019 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1020 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1022 if (flags & MAP_LOCKED)
1023 if (!can_do_mlock())
1026 /* mlock MCL_FUTURE? */
1027 if (vm_flags & VM_LOCKED) {
1028 unsigned long locked, lock_limit;
1029 locked = len >> PAGE_SHIFT;
1030 locked += mm->locked_vm;
1031 lock_limit = rlimit(RLIMIT_MEMLOCK);
1032 lock_limit >>= PAGE_SHIFT;
1033 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1037 inode = file ? file->f_path.dentry->d_inode : NULL;
1040 switch (flags & MAP_TYPE) {
1042 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1046 * Make sure we don't allow writing to an append-only
1049 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1053 * Make sure there are no mandatory locks on the file.
1055 if (locks_verify_locked(inode))
1058 vm_flags |= VM_SHARED | VM_MAYSHARE;
1059 if (!(file->f_mode & FMODE_WRITE))
1060 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1064 if (!(file->f_mode & FMODE_READ))
1066 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1067 if (vm_flags & VM_EXEC)
1069 vm_flags &= ~VM_MAYEXEC;
1072 if (!file->f_op || !file->f_op->mmap)
1080 switch (flags & MAP_TYPE) {
1086 vm_flags |= VM_SHARED | VM_MAYSHARE;
1090 * Set pgoff according to addr for anon_vma.
1092 pgoff = addr >> PAGE_SHIFT;
1099 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1103 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1105 EXPORT_SYMBOL(do_mmap_pgoff);
1107 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1108 unsigned long, prot, unsigned long, flags,
1109 unsigned long, fd, unsigned long, pgoff)
1111 struct file *file = NULL;
1112 unsigned long retval = -EBADF;
1114 if (!(flags & MAP_ANONYMOUS)) {
1115 audit_mmap_fd(fd, flags);
1116 if (unlikely(flags & MAP_HUGETLB))
1121 } else if (flags & MAP_HUGETLB) {
1122 struct user_struct *user = NULL;
1124 * VM_NORESERVE is used because the reservations will be
1125 * taken when vm_ops->mmap() is called
1126 * A dummy user value is used because we are not locking
1127 * memory so no accounting is necessary
1129 len = ALIGN(len, huge_page_size(&default_hstate));
1130 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1131 &user, HUGETLB_ANONHUGE_INODE);
1133 return PTR_ERR(file);
1136 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1138 down_write(¤t->mm->mmap_sem);
1139 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1140 up_write(¤t->mm->mmap_sem);
1148 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1149 struct mmap_arg_struct {
1153 unsigned long flags;
1155 unsigned long offset;
1158 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1160 struct mmap_arg_struct a;
1162 if (copy_from_user(&a, arg, sizeof(a)))
1164 if (a.offset & ~PAGE_MASK)
1167 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1168 a.offset >> PAGE_SHIFT);
1170 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1173 * Some shared mappigns will want the pages marked read-only
1174 * to track write events. If so, we'll downgrade vm_page_prot
1175 * to the private version (using protection_map[] without the
1178 int vma_wants_writenotify(struct vm_area_struct *vma)
1180 unsigned int vm_flags = vma->vm_flags;
1182 /* If it was private or non-writable, the write bit is already clear */
1183 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1186 /* The backer wishes to know when pages are first written to? */
1187 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1190 /* The open routine did something to the protections already? */
1191 if (pgprot_val(vma->vm_page_prot) !=
1192 pgprot_val(vm_get_page_prot(vm_flags)))
1195 /* Specialty mapping? */
1196 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1199 /* Can the mapping track the dirty pages? */
1200 return vma->vm_file && vma->vm_file->f_mapping &&
1201 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1205 * We account for memory if it's a private writeable mapping,
1206 * not hugepages and VM_NORESERVE wasn't set.
1208 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1211 * hugetlb has its own accounting separate from the core VM
1212 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1214 if (file && is_file_hugepages(file))
1217 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1220 unsigned long mmap_region(struct file *file, unsigned long addr,
1221 unsigned long len, unsigned long flags,
1222 unsigned int vm_flags, unsigned long pgoff)
1224 struct mm_struct *mm = current->mm;
1225 struct vm_area_struct *vma, *prev;
1226 int correct_wcount = 0;
1228 struct rb_node **rb_link, *rb_parent;
1229 unsigned long charged = 0;
1230 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1232 /* Clear old maps */
1235 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1236 if (vma && vma->vm_start < addr + len) {
1237 if (do_munmap(mm, addr, len))
1242 /* Check against address space limit. */
1243 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1247 * Set 'VM_NORESERVE' if we should not account for the
1248 * memory use of this mapping.
1250 if ((flags & MAP_NORESERVE)) {
1251 /* We honor MAP_NORESERVE if allowed to overcommit */
1252 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1253 vm_flags |= VM_NORESERVE;
1255 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1256 if (file && is_file_hugepages(file))
1257 vm_flags |= VM_NORESERVE;
1261 * Private writable mapping: check memory availability
1263 if (accountable_mapping(file, vm_flags)) {
1264 charged = len >> PAGE_SHIFT;
1265 if (security_vm_enough_memory(charged))
1267 vm_flags |= VM_ACCOUNT;
1271 * Can we just expand an old mapping?
1273 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1278 * Determine the object being mapped and call the appropriate
1279 * specific mapper. the address has already been validated, but
1280 * not unmapped, but the maps are removed from the list.
1282 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1289 vma->vm_start = addr;
1290 vma->vm_end = addr + len;
1291 vma->vm_flags = vm_flags;
1292 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1293 vma->vm_pgoff = pgoff;
1294 INIT_LIST_HEAD(&vma->anon_vma_chain);
1298 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1300 if (vm_flags & VM_DENYWRITE) {
1301 error = deny_write_access(file);
1306 vma->vm_file = file;
1308 error = file->f_op->mmap(file, vma);
1310 goto unmap_and_free_vma;
1311 if (vm_flags & VM_EXECUTABLE)
1312 added_exe_file_vma(mm);
1314 /* Can addr have changed??
1316 * Answer: Yes, several device drivers can do it in their
1317 * f_op->mmap method. -DaveM
1319 addr = vma->vm_start;
1320 pgoff = vma->vm_pgoff;
1321 vm_flags = vma->vm_flags;
1322 } else if (vm_flags & VM_SHARED) {
1323 error = shmem_zero_setup(vma);
1328 if (vma_wants_writenotify(vma)) {
1329 pgprot_t pprot = vma->vm_page_prot;
1331 /* Can vma->vm_page_prot have changed??
1333 * Answer: Yes, drivers may have changed it in their
1334 * f_op->mmap method.
1336 * Ensures that vmas marked as uncached stay that way.
1338 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1339 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1340 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1343 vma_link(mm, vma, prev, rb_link, rb_parent);
1344 file = vma->vm_file;
1346 /* Once vma denies write, undo our temporary denial count */
1348 atomic_inc(&inode->i_writecount);
1350 perf_event_mmap(vma);
1352 mm->total_vm += len >> PAGE_SHIFT;
1353 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1354 if (vm_flags & VM_LOCKED) {
1355 if (!mlock_vma_pages_range(vma, addr, addr + len))
1356 mm->locked_vm += (len >> PAGE_SHIFT);
1357 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1358 make_pages_present(addr, addr + len);
1363 atomic_inc(&inode->i_writecount);
1364 vma->vm_file = NULL;
1367 /* Undo any partial mapping done by a device driver. */
1368 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1371 kmem_cache_free(vm_area_cachep, vma);
1374 vm_unacct_memory(charged);
1378 /* Get an address range which is currently unmapped.
1379 * For shmat() with addr=0.
1381 * Ugly calling convention alert:
1382 * Return value with the low bits set means error value,
1384 * if (ret & ~PAGE_MASK)
1387 * This function "knows" that -ENOMEM has the bits set.
1389 #ifndef HAVE_ARCH_UNMAPPED_AREA
1391 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1392 unsigned long len, unsigned long pgoff, unsigned long flags)
1394 struct mm_struct *mm = current->mm;
1395 struct vm_area_struct *vma;
1396 unsigned long start_addr;
1398 if (len > TASK_SIZE)
1401 if (flags & MAP_FIXED)
1405 addr = PAGE_ALIGN(addr);
1406 vma = find_vma(mm, addr);
1407 if (TASK_SIZE - len >= addr &&
1408 (!vma || addr + len <= vma->vm_start))
1411 if (len > mm->cached_hole_size) {
1412 start_addr = addr = mm->free_area_cache;
1414 start_addr = addr = TASK_UNMAPPED_BASE;
1415 mm->cached_hole_size = 0;
1419 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1420 /* At this point: (!vma || addr < vma->vm_end). */
1421 if (TASK_SIZE - len < addr) {
1423 * Start a new search - just in case we missed
1426 if (start_addr != TASK_UNMAPPED_BASE) {
1427 addr = TASK_UNMAPPED_BASE;
1429 mm->cached_hole_size = 0;
1434 if (!vma || addr + len <= vma->vm_start) {
1436 * Remember the place where we stopped the search:
1438 mm->free_area_cache = addr + len;
1441 if (addr + mm->cached_hole_size < vma->vm_start)
1442 mm->cached_hole_size = vma->vm_start - addr;
1448 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1451 * Is this a new hole at the lowest possible address?
1453 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1454 mm->free_area_cache = addr;
1455 mm->cached_hole_size = ~0UL;
1460 * This mmap-allocator allocates new areas top-down from below the
1461 * stack's low limit (the base):
1463 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1465 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1466 const unsigned long len, const unsigned long pgoff,
1467 const unsigned long flags)
1469 struct vm_area_struct *vma;
1470 struct mm_struct *mm = current->mm;
1471 unsigned long addr = addr0;
1473 /* requested length too big for entire address space */
1474 if (len > TASK_SIZE)
1477 if (flags & MAP_FIXED)
1480 /* requesting a specific address */
1482 addr = PAGE_ALIGN(addr);
1483 vma = find_vma(mm, addr);
1484 if (TASK_SIZE - len >= addr &&
1485 (!vma || addr + len <= vma->vm_start))
1489 /* check if free_area_cache is useful for us */
1490 if (len <= mm->cached_hole_size) {
1491 mm->cached_hole_size = 0;
1492 mm->free_area_cache = mm->mmap_base;
1495 /* either no address requested or can't fit in requested address hole */
1496 addr = mm->free_area_cache;
1498 /* make sure it can fit in the remaining address space */
1500 vma = find_vma(mm, addr-len);
1501 if (!vma || addr <= vma->vm_start)
1502 /* remember the address as a hint for next time */
1503 return (mm->free_area_cache = addr-len);
1506 if (mm->mmap_base < len)
1509 addr = mm->mmap_base-len;
1513 * Lookup failure means no vma is above this address,
1514 * else if new region fits below vma->vm_start,
1515 * return with success:
1517 vma = find_vma(mm, addr);
1518 if (!vma || addr+len <= vma->vm_start)
1519 /* remember the address as a hint for next time */
1520 return (mm->free_area_cache = addr);
1522 /* remember the largest hole we saw so far */
1523 if (addr + mm->cached_hole_size < vma->vm_start)
1524 mm->cached_hole_size = vma->vm_start - addr;
1526 /* try just below the current vma->vm_start */
1527 addr = vma->vm_start-len;
1528 } while (len < vma->vm_start);
1532 * A failed mmap() very likely causes application failure,
1533 * so fall back to the bottom-up function here. This scenario
1534 * can happen with large stack limits and large mmap()
1537 mm->cached_hole_size = ~0UL;
1538 mm->free_area_cache = TASK_UNMAPPED_BASE;
1539 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1541 * Restore the topdown base:
1543 mm->free_area_cache = mm->mmap_base;
1544 mm->cached_hole_size = ~0UL;
1550 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1553 * Is this a new hole at the highest possible address?
1555 if (addr > mm->free_area_cache)
1556 mm->free_area_cache = addr;
1558 /* dont allow allocations above current base */
1559 if (mm->free_area_cache > mm->mmap_base)
1560 mm->free_area_cache = mm->mmap_base;
1564 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1565 unsigned long pgoff, unsigned long flags)
1567 unsigned long (*get_area)(struct file *, unsigned long,
1568 unsigned long, unsigned long, unsigned long);
1570 unsigned long error = arch_mmap_check(addr, len, flags);
1574 /* Careful about overflows.. */
1575 if (len > TASK_SIZE)
1578 get_area = current->mm->get_unmapped_area;
1579 if (file && file->f_op && file->f_op->get_unmapped_area)
1580 get_area = file->f_op->get_unmapped_area;
1581 addr = get_area(file, addr, len, pgoff, flags);
1582 if (IS_ERR_VALUE(addr))
1585 if (addr > TASK_SIZE - len)
1587 if (addr & ~PAGE_MASK)
1590 return arch_rebalance_pgtables(addr, len);
1593 EXPORT_SYMBOL(get_unmapped_area);
1595 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1596 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1598 struct vm_area_struct *vma = NULL;
1601 /* Check the cache first. */
1602 /* (Cache hit rate is typically around 35%.) */
1603 vma = mm->mmap_cache;
1604 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1605 struct rb_node * rb_node;
1607 rb_node = mm->mm_rb.rb_node;
1611 struct vm_area_struct * vma_tmp;
1613 vma_tmp = rb_entry(rb_node,
1614 struct vm_area_struct, vm_rb);
1616 if (vma_tmp->vm_end > addr) {
1618 if (vma_tmp->vm_start <= addr)
1620 rb_node = rb_node->rb_left;
1622 rb_node = rb_node->rb_right;
1625 mm->mmap_cache = vma;
1631 EXPORT_SYMBOL(find_vma);
1633 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1634 struct vm_area_struct *
1635 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1636 struct vm_area_struct **pprev)
1638 struct vm_area_struct *vma = NULL, *prev = NULL;
1639 struct rb_node *rb_node;
1643 /* Guard against addr being lower than the first VMA */
1646 /* Go through the RB tree quickly. */
1647 rb_node = mm->mm_rb.rb_node;
1650 struct vm_area_struct *vma_tmp;
1651 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1653 if (addr < vma_tmp->vm_end) {
1654 rb_node = rb_node->rb_left;
1657 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1659 rb_node = rb_node->rb_right;
1665 return prev ? prev->vm_next : vma;
1669 * Verify that the stack growth is acceptable and
1670 * update accounting. This is shared with both the
1671 * grow-up and grow-down cases.
1673 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1675 struct mm_struct *mm = vma->vm_mm;
1676 struct rlimit *rlim = current->signal->rlim;
1677 unsigned long new_start;
1679 /* address space limit tests */
1680 if (!may_expand_vm(mm, grow))
1683 /* Stack limit test */
1684 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1687 /* mlock limit tests */
1688 if (vma->vm_flags & VM_LOCKED) {
1689 unsigned long locked;
1690 unsigned long limit;
1691 locked = mm->locked_vm + grow;
1692 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1693 limit >>= PAGE_SHIFT;
1694 if (locked > limit && !capable(CAP_IPC_LOCK))
1698 /* Check to ensure the stack will not grow into a hugetlb-only region */
1699 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1701 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1705 * Overcommit.. This must be the final test, as it will
1706 * update security statistics.
1708 if (security_vm_enough_memory_mm(mm, grow))
1711 /* Ok, everything looks good - let it rip */
1712 mm->total_vm += grow;
1713 if (vma->vm_flags & VM_LOCKED)
1714 mm->locked_vm += grow;
1715 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1719 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1721 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1722 * vma is the last one with address > vma->vm_end. Have to extend vma.
1724 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1728 if (!(vma->vm_flags & VM_GROWSUP))
1732 * We must make sure the anon_vma is allocated
1733 * so that the anon_vma locking is not a noop.
1735 if (unlikely(anon_vma_prepare(vma)))
1737 vma_lock_anon_vma(vma);
1740 * vma->vm_start/vm_end cannot change under us because the caller
1741 * is required to hold the mmap_sem in read mode. We need the
1742 * anon_vma lock to serialize against concurrent expand_stacks.
1743 * Also guard against wrapping around to address 0.
1745 if (address < PAGE_ALIGN(address+4))
1746 address = PAGE_ALIGN(address+4);
1748 vma_unlock_anon_vma(vma);
1753 /* Somebody else might have raced and expanded it already */
1754 if (address > vma->vm_end) {
1755 unsigned long size, grow;
1757 size = address - vma->vm_start;
1758 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1760 error = acct_stack_growth(vma, size, grow);
1762 vma->vm_end = address;
1763 perf_event_mmap(vma);
1766 vma_unlock_anon_vma(vma);
1767 khugepaged_enter_vma_merge(vma);
1770 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1773 * vma is the first one with address < vma->vm_start. Have to extend vma.
1775 static int expand_downwards(struct vm_area_struct *vma,
1776 unsigned long address)
1781 * We must make sure the anon_vma is allocated
1782 * so that the anon_vma locking is not a noop.
1784 if (unlikely(anon_vma_prepare(vma)))
1787 address &= PAGE_MASK;
1788 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1792 vma_lock_anon_vma(vma);
1795 * vma->vm_start/vm_end cannot change under us because the caller
1796 * is required to hold the mmap_sem in read mode. We need the
1797 * anon_vma lock to serialize against concurrent expand_stacks.
1800 /* Somebody else might have raced and expanded it already */
1801 if (address < vma->vm_start) {
1802 unsigned long size, grow;
1804 size = vma->vm_end - address;
1805 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1807 error = acct_stack_growth(vma, size, grow);
1809 vma->vm_start = address;
1810 vma->vm_pgoff -= grow;
1811 perf_event_mmap(vma);
1814 vma_unlock_anon_vma(vma);
1815 khugepaged_enter_vma_merge(vma);
1819 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1821 return expand_downwards(vma, address);
1824 #ifdef CONFIG_STACK_GROWSUP
1825 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1827 return expand_upwards(vma, address);
1830 struct vm_area_struct *
1831 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1833 struct vm_area_struct *vma, *prev;
1836 vma = find_vma_prev(mm, addr, &prev);
1837 if (vma && (vma->vm_start <= addr))
1839 if (!prev || expand_stack(prev, addr))
1841 if (prev->vm_flags & VM_LOCKED) {
1842 mlock_vma_pages_range(prev, addr, prev->vm_end);
1847 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1849 return expand_downwards(vma, address);
1852 struct vm_area_struct *
1853 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1855 struct vm_area_struct * vma;
1856 unsigned long start;
1859 vma = find_vma(mm,addr);
1862 if (vma->vm_start <= addr)
1864 if (!(vma->vm_flags & VM_GROWSDOWN))
1866 start = vma->vm_start;
1867 if (expand_stack(vma, addr))
1869 if (vma->vm_flags & VM_LOCKED) {
1870 mlock_vma_pages_range(vma, addr, start);
1877 * Ok - we have the memory areas we should free on the vma list,
1878 * so release them, and do the vma updates.
1880 * Called with the mm semaphore held.
1882 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1884 /* Update high watermark before we lower total_vm */
1885 update_hiwater_vm(mm);
1887 long nrpages = vma_pages(vma);
1889 mm->total_vm -= nrpages;
1890 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1891 vma = remove_vma(vma);
1897 * Get rid of page table information in the indicated region.
1899 * Called with the mm semaphore held.
1901 static void unmap_region(struct mm_struct *mm,
1902 struct vm_area_struct *vma, struct vm_area_struct *prev,
1903 unsigned long start, unsigned long end)
1905 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1906 struct mmu_gather *tlb;
1907 unsigned long nr_accounted = 0;
1910 tlb = tlb_gather_mmu(mm, 0);
1911 update_hiwater_rss(mm);
1912 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1913 vm_unacct_memory(nr_accounted);
1914 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1915 next? next->vm_start: 0);
1916 tlb_finish_mmu(tlb, start, end);
1920 * Create a list of vma's touched by the unmap, removing them from the mm's
1921 * vma list as we go..
1924 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1925 struct vm_area_struct *prev, unsigned long end)
1927 struct vm_area_struct **insertion_point;
1928 struct vm_area_struct *tail_vma = NULL;
1931 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1932 vma->vm_prev = NULL;
1934 rb_erase(&vma->vm_rb, &mm->mm_rb);
1938 } while (vma && vma->vm_start < end);
1939 *insertion_point = vma;
1941 vma->vm_prev = prev;
1942 tail_vma->vm_next = NULL;
1943 if (mm->unmap_area == arch_unmap_area)
1944 addr = prev ? prev->vm_end : mm->mmap_base;
1946 addr = vma ? vma->vm_start : mm->mmap_base;
1947 mm->unmap_area(mm, addr);
1948 mm->mmap_cache = NULL; /* Kill the cache. */
1952 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1953 * munmap path where it doesn't make sense to fail.
1955 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1956 unsigned long addr, int new_below)
1958 struct mempolicy *pol;
1959 struct vm_area_struct *new;
1962 if (is_vm_hugetlb_page(vma) && (addr &
1963 ~(huge_page_mask(hstate_vma(vma)))))
1966 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1970 /* most fields are the same, copy all, and then fixup */
1973 INIT_LIST_HEAD(&new->anon_vma_chain);
1978 new->vm_start = addr;
1979 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1982 pol = mpol_dup(vma_policy(vma));
1987 vma_set_policy(new, pol);
1989 if (anon_vma_clone(new, vma))
1993 get_file(new->vm_file);
1994 if (vma->vm_flags & VM_EXECUTABLE)
1995 added_exe_file_vma(mm);
1998 if (new->vm_ops && new->vm_ops->open)
1999 new->vm_ops->open(new);
2002 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2003 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2005 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2011 /* Clean everything up if vma_adjust failed. */
2012 if (new->vm_ops && new->vm_ops->close)
2013 new->vm_ops->close(new);
2015 if (vma->vm_flags & VM_EXECUTABLE)
2016 removed_exe_file_vma(mm);
2019 unlink_anon_vmas(new);
2023 kmem_cache_free(vm_area_cachep, new);
2029 * Split a vma into two pieces at address 'addr', a new vma is allocated
2030 * either for the first part or the tail.
2032 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2033 unsigned long addr, int new_below)
2035 if (mm->map_count >= sysctl_max_map_count)
2038 return __split_vma(mm, vma, addr, new_below);
2041 /* Munmap is split into 2 main parts -- this part which finds
2042 * what needs doing, and the areas themselves, which do the
2043 * work. This now handles partial unmappings.
2044 * Jeremy Fitzhardinge <jeremy@goop.org>
2046 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2049 struct vm_area_struct *vma, *prev, *last;
2051 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2054 if ((len = PAGE_ALIGN(len)) == 0)
2057 /* Find the first overlapping VMA */
2058 vma = find_vma_prev(mm, start, &prev);
2061 /* we have start < vma->vm_end */
2063 /* if it doesn't overlap, we have nothing.. */
2065 if (vma->vm_start >= end)
2069 * If we need to split any vma, do it now to save pain later.
2071 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2072 * unmapped vm_area_struct will remain in use: so lower split_vma
2073 * places tmp vma above, and higher split_vma places tmp vma below.
2075 if (start > vma->vm_start) {
2079 * Make sure that map_count on return from munmap() will
2080 * not exceed its limit; but let map_count go just above
2081 * its limit temporarily, to help free resources as expected.
2083 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2086 error = __split_vma(mm, vma, start, 0);
2092 /* Does it split the last one? */
2093 last = find_vma(mm, end);
2094 if (last && end > last->vm_start) {
2095 int error = __split_vma(mm, last, end, 1);
2099 vma = prev? prev->vm_next: mm->mmap;
2102 * unlock any mlock()ed ranges before detaching vmas
2104 if (mm->locked_vm) {
2105 struct vm_area_struct *tmp = vma;
2106 while (tmp && tmp->vm_start < end) {
2107 if (tmp->vm_flags & VM_LOCKED) {
2108 mm->locked_vm -= vma_pages(tmp);
2109 munlock_vma_pages_all(tmp);
2116 * Remove the vma's, and unmap the actual pages
2118 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2119 unmap_region(mm, vma, prev, start, end);
2121 /* Fix up all other VM information */
2122 remove_vma_list(mm, vma);
2127 EXPORT_SYMBOL(do_munmap);
2129 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2132 struct mm_struct *mm = current->mm;
2134 profile_munmap(addr);
2136 down_write(&mm->mmap_sem);
2137 ret = do_munmap(mm, addr, len);
2138 up_write(&mm->mmap_sem);
2142 static inline void verify_mm_writelocked(struct mm_struct *mm)
2144 #ifdef CONFIG_DEBUG_VM
2145 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2147 up_read(&mm->mmap_sem);
2153 * this is really a simplified "do_mmap". it only handles
2154 * anonymous maps. eventually we may be able to do some
2155 * brk-specific accounting here.
2157 unsigned long do_brk(unsigned long addr, unsigned long len)
2159 struct mm_struct * mm = current->mm;
2160 struct vm_area_struct * vma, * prev;
2161 unsigned long flags;
2162 struct rb_node ** rb_link, * rb_parent;
2163 pgoff_t pgoff = addr >> PAGE_SHIFT;
2166 len = PAGE_ALIGN(len);
2170 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2174 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2176 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2177 if (error & ~PAGE_MASK)
2183 if (mm->def_flags & VM_LOCKED) {
2184 unsigned long locked, lock_limit;
2185 locked = len >> PAGE_SHIFT;
2186 locked += mm->locked_vm;
2187 lock_limit = rlimit(RLIMIT_MEMLOCK);
2188 lock_limit >>= PAGE_SHIFT;
2189 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2194 * mm->mmap_sem is required to protect against another thread
2195 * changing the mappings in case we sleep.
2197 verify_mm_writelocked(mm);
2200 * Clear old maps. this also does some error checking for us
2203 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2204 if (vma && vma->vm_start < addr + len) {
2205 if (do_munmap(mm, addr, len))
2210 /* Check against address space limits *after* clearing old maps... */
2211 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2214 if (mm->map_count > sysctl_max_map_count)
2217 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2220 /* Can we just expand an old private anonymous mapping? */
2221 vma = vma_merge(mm, prev, addr, addr + len, flags,
2222 NULL, NULL, pgoff, NULL);
2227 * create a vma struct for an anonymous mapping
2229 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2231 vm_unacct_memory(len >> PAGE_SHIFT);
2235 INIT_LIST_HEAD(&vma->anon_vma_chain);
2237 vma->vm_start = addr;
2238 vma->vm_end = addr + len;
2239 vma->vm_pgoff = pgoff;
2240 vma->vm_flags = flags;
2241 vma->vm_page_prot = vm_get_page_prot(flags);
2242 vma_link(mm, vma, prev, rb_link, rb_parent);
2244 perf_event_mmap(vma);
2245 mm->total_vm += len >> PAGE_SHIFT;
2246 if (flags & VM_LOCKED) {
2247 if (!mlock_vma_pages_range(vma, addr, addr + len))
2248 mm->locked_vm += (len >> PAGE_SHIFT);
2253 EXPORT_SYMBOL(do_brk);
2255 /* Release all mmaps. */
2256 void exit_mmap(struct mm_struct *mm)
2258 struct mmu_gather *tlb;
2259 struct vm_area_struct *vma;
2260 unsigned long nr_accounted = 0;
2263 /* mm's last user has gone, and its about to be pulled down */
2264 mmu_notifier_release(mm);
2266 if (mm->locked_vm) {
2269 if (vma->vm_flags & VM_LOCKED)
2270 munlock_vma_pages_all(vma);
2278 if (!vma) /* Can happen if dup_mmap() received an OOM */
2283 tlb = tlb_gather_mmu(mm, 1);
2284 /* update_hiwater_rss(mm) here? but nobody should be looking */
2285 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2286 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2287 vm_unacct_memory(nr_accounted);
2289 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2290 tlb_finish_mmu(tlb, 0, end);
2293 * Walk the list again, actually closing and freeing it,
2294 * with preemption enabled, without holding any MM locks.
2297 vma = remove_vma(vma);
2299 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2302 /* Insert vm structure into process list sorted by address
2303 * and into the inode's i_mmap tree. If vm_file is non-NULL
2304 * then i_mmap_lock is taken here.
2306 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2308 struct vm_area_struct * __vma, * prev;
2309 struct rb_node ** rb_link, * rb_parent;
2312 * The vm_pgoff of a purely anonymous vma should be irrelevant
2313 * until its first write fault, when page's anon_vma and index
2314 * are set. But now set the vm_pgoff it will almost certainly
2315 * end up with (unless mremap moves it elsewhere before that
2316 * first wfault), so /proc/pid/maps tells a consistent story.
2318 * By setting it to reflect the virtual start address of the
2319 * vma, merges and splits can happen in a seamless way, just
2320 * using the existing file pgoff checks and manipulations.
2321 * Similarly in do_mmap_pgoff and in do_brk.
2323 if (!vma->vm_file) {
2324 BUG_ON(vma->anon_vma);
2325 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2327 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2328 if (__vma && __vma->vm_start < vma->vm_end)
2330 if ((vma->vm_flags & VM_ACCOUNT) &&
2331 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2333 vma_link(mm, vma, prev, rb_link, rb_parent);
2338 * Copy the vma structure to a new location in the same mm,
2339 * prior to moving page table entries, to effect an mremap move.
2341 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2342 unsigned long addr, unsigned long len, pgoff_t pgoff)
2344 struct vm_area_struct *vma = *vmap;
2345 unsigned long vma_start = vma->vm_start;
2346 struct mm_struct *mm = vma->vm_mm;
2347 struct vm_area_struct *new_vma, *prev;
2348 struct rb_node **rb_link, *rb_parent;
2349 struct mempolicy *pol;
2352 * If anonymous vma has not yet been faulted, update new pgoff
2353 * to match new location, to increase its chance of merging.
2355 if (!vma->vm_file && !vma->anon_vma)
2356 pgoff = addr >> PAGE_SHIFT;
2358 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2359 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2360 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2363 * Source vma may have been merged into new_vma
2365 if (vma_start >= new_vma->vm_start &&
2366 vma_start < new_vma->vm_end)
2369 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2372 pol = mpol_dup(vma_policy(vma));
2375 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2376 if (anon_vma_clone(new_vma, vma))
2377 goto out_free_mempol;
2378 vma_set_policy(new_vma, pol);
2379 new_vma->vm_start = addr;
2380 new_vma->vm_end = addr + len;
2381 new_vma->vm_pgoff = pgoff;
2382 if (new_vma->vm_file) {
2383 get_file(new_vma->vm_file);
2384 if (vma->vm_flags & VM_EXECUTABLE)
2385 added_exe_file_vma(mm);
2387 if (new_vma->vm_ops && new_vma->vm_ops->open)
2388 new_vma->vm_ops->open(new_vma);
2389 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2397 kmem_cache_free(vm_area_cachep, new_vma);
2402 * Return true if the calling process may expand its vm space by the passed
2405 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2407 unsigned long cur = mm->total_vm; /* pages */
2410 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2412 if (cur + npages > lim)
2418 static int special_mapping_fault(struct vm_area_struct *vma,
2419 struct vm_fault *vmf)
2422 struct page **pages;
2425 * special mappings have no vm_file, and in that case, the mm
2426 * uses vm_pgoff internally. So we have to subtract it from here.
2427 * We are allowed to do this because we are the mm; do not copy
2428 * this code into drivers!
2430 pgoff = vmf->pgoff - vma->vm_pgoff;
2432 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2436 struct page *page = *pages;
2442 return VM_FAULT_SIGBUS;
2446 * Having a close hook prevents vma merging regardless of flags.
2448 static void special_mapping_close(struct vm_area_struct *vma)
2452 static const struct vm_operations_struct special_mapping_vmops = {
2453 .close = special_mapping_close,
2454 .fault = special_mapping_fault,
2458 * Called with mm->mmap_sem held for writing.
2459 * Insert a new vma covering the given region, with the given flags.
2460 * Its pages are supplied by the given array of struct page *.
2461 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2462 * The region past the last page supplied will always produce SIGBUS.
2463 * The array pointer and the pages it points to are assumed to stay alive
2464 * for as long as this mapping might exist.
2466 int install_special_mapping(struct mm_struct *mm,
2467 unsigned long addr, unsigned long len,
2468 unsigned long vm_flags, struct page **pages)
2471 struct vm_area_struct *vma;
2473 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2474 if (unlikely(vma == NULL))
2477 INIT_LIST_HEAD(&vma->anon_vma_chain);
2479 vma->vm_start = addr;
2480 vma->vm_end = addr + len;
2482 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2483 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2485 vma->vm_ops = &special_mapping_vmops;
2486 vma->vm_private_data = pages;
2488 ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2492 ret = insert_vm_struct(mm, vma);
2496 mm->total_vm += len >> PAGE_SHIFT;
2498 perf_event_mmap(vma);
2503 kmem_cache_free(vm_area_cachep, vma);
2507 static DEFINE_MUTEX(mm_all_locks_mutex);
2509 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2511 if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2513 * The LSB of head.next can't change from under us
2514 * because we hold the mm_all_locks_mutex.
2516 spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
2518 * We can safely modify head.next after taking the
2519 * anon_vma->root->lock. If some other vma in this mm shares
2520 * the same anon_vma we won't take it again.
2522 * No need of atomic instructions here, head.next
2523 * can't change from under us thanks to the
2524 * anon_vma->root->lock.
2526 if (__test_and_set_bit(0, (unsigned long *)
2527 &anon_vma->root->head.next))
2532 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2534 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2536 * AS_MM_ALL_LOCKS can't change from under us because
2537 * we hold the mm_all_locks_mutex.
2539 * Operations on ->flags have to be atomic because
2540 * even if AS_MM_ALL_LOCKS is stable thanks to the
2541 * mm_all_locks_mutex, there may be other cpus
2542 * changing other bitflags in parallel to us.
2544 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2546 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2551 * This operation locks against the VM for all pte/vma/mm related
2552 * operations that could ever happen on a certain mm. This includes
2553 * vmtruncate, try_to_unmap, and all page faults.
2555 * The caller must take the mmap_sem in write mode before calling
2556 * mm_take_all_locks(). The caller isn't allowed to release the
2557 * mmap_sem until mm_drop_all_locks() returns.
2559 * mmap_sem in write mode is required in order to block all operations
2560 * that could modify pagetables and free pages without need of
2561 * altering the vma layout (for example populate_range() with
2562 * nonlinear vmas). It's also needed in write mode to avoid new
2563 * anon_vmas to be associated with existing vmas.
2565 * A single task can't take more than one mm_take_all_locks() in a row
2566 * or it would deadlock.
2568 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2569 * mapping->flags avoid to take the same lock twice, if more than one
2570 * vma in this mm is backed by the same anon_vma or address_space.
2572 * We can take all the locks in random order because the VM code
2573 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2574 * takes more than one of them in a row. Secondly we're protected
2575 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2577 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2578 * that may have to take thousand of locks.
2580 * mm_take_all_locks() can fail if it's interrupted by signals.
2582 int mm_take_all_locks(struct mm_struct *mm)
2584 struct vm_area_struct *vma;
2585 struct anon_vma_chain *avc;
2588 BUG_ON(down_read_trylock(&mm->mmap_sem));
2590 mutex_lock(&mm_all_locks_mutex);
2592 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2593 if (signal_pending(current))
2595 if (vma->vm_file && vma->vm_file->f_mapping)
2596 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2599 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2600 if (signal_pending(current))
2603 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2604 vm_lock_anon_vma(mm, avc->anon_vma);
2611 mm_drop_all_locks(mm);
2616 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2618 if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2620 * The LSB of head.next can't change to 0 from under
2621 * us because we hold the mm_all_locks_mutex.
2623 * We must however clear the bitflag before unlocking
2624 * the vma so the users using the anon_vma->head will
2625 * never see our bitflag.
2627 * No need of atomic instructions here, head.next
2628 * can't change from under us until we release the
2629 * anon_vma->root->lock.
2631 if (!__test_and_clear_bit(0, (unsigned long *)
2632 &anon_vma->root->head.next))
2634 anon_vma_unlock(anon_vma);
2638 static void vm_unlock_mapping(struct address_space *mapping)
2640 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2642 * AS_MM_ALL_LOCKS can't change to 0 from under us
2643 * because we hold the mm_all_locks_mutex.
2645 spin_unlock(&mapping->i_mmap_lock);
2646 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2653 * The mmap_sem cannot be released by the caller until
2654 * mm_drop_all_locks() returns.
2656 void mm_drop_all_locks(struct mm_struct *mm)
2658 struct vm_area_struct *vma;
2659 struct anon_vma_chain *avc;
2661 BUG_ON(down_read_trylock(&mm->mmap_sem));
2662 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2664 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2666 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2667 vm_unlock_anon_vma(avc->anon_vma);
2668 if (vma->vm_file && vma->vm_file->f_mapping)
2669 vm_unlock_mapping(vma->vm_file->f_mapping);
2672 mutex_unlock(&mm_all_locks_mutex);
2676 * initialise the VMA slab
2678 void __init mmap_init(void)
2682 ret = percpu_counter_init(&vm_committed_as, 0);