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>
33 #include <linux/random.h>
35 #include <asm/uaccess.h>
36 #include <asm/cacheflush.h>
38 #include <asm/mmu_context.h>
42 #ifndef arch_mmap_check
43 #define arch_mmap_check(addr, len, flags) (0)
46 #ifndef arch_rebalance_pgtables
47 #define arch_rebalance_pgtables(addr, len) (addr)
50 /* No sane architecture will #define these to anything else */
51 #ifndef arch_add_exec_range
52 #define arch_add_exec_range(mm, limit) do { ; } while (0)
54 #ifndef arch_flush_exec_range
55 #define arch_flush_exec_range(mm) do { ; } while (0)
57 #ifndef arch_remove_exec_range
58 #define arch_remove_exec_range(mm, limit) do { ; } while (0)
62 static void unmap_region(struct mm_struct *mm,
63 struct vm_area_struct *vma, struct vm_area_struct *prev,
64 unsigned long start, unsigned long end);
67 * WARNING: the debugging will use recursive algorithms so never enable this
68 * unless you know what you are doing.
72 /* description of effects of mapping type and prot in current implementation.
73 * this is due to the limited x86 page protection hardware. The expected
74 * behavior is in parens:
77 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
78 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
79 * w: (no) no w: (no) no w: (yes) yes w: (no) no
80 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
82 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
83 * w: (no) no w: (no) no w: (copy) copy w: (no) no
84 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
87 pgprot_t protection_map[16] = {
88 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
89 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
92 pgprot_t vm_get_page_prot(unsigned long vm_flags)
94 return __pgprot(pgprot_val(protection_map[vm_flags &
95 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
96 pgprot_val(arch_vm_get_page_prot(vm_flags)));
98 EXPORT_SYMBOL(vm_get_page_prot);
100 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
101 int sysctl_overcommit_ratio = 50; /* default is 50% */
102 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
103 struct percpu_counter vm_committed_as;
106 * Check that a process has enough memory to allocate a new virtual
107 * mapping. 0 means there is enough memory for the allocation to
108 * succeed and -ENOMEM implies there is not.
110 * We currently support three overcommit policies, which are set via the
111 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
113 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
114 * Additional code 2002 Jul 20 by Robert Love.
116 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
118 * Note this is a helper function intended to be used by LSMs which
119 * wish to use this logic.
121 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
123 unsigned long free, allowed;
125 vm_acct_memory(pages);
128 * Sometimes we want to use more memory than we have
130 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
133 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
136 free = global_page_state(NR_FILE_PAGES);
137 free += nr_swap_pages;
140 * Any slabs which are created with the
141 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
142 * which are reclaimable, under pressure. The dentry
143 * cache and most inode caches should fall into this
145 free += global_page_state(NR_SLAB_RECLAIMABLE);
148 * Leave the last 3% for root
157 * nr_free_pages() is very expensive on large systems,
158 * only call if we're about to fail.
163 * Leave reserved pages. The pages are not for anonymous pages.
165 if (n <= totalreserve_pages)
168 n -= totalreserve_pages;
171 * Leave the last 3% for root
183 allowed = (totalram_pages - hugetlb_total_pages())
184 * sysctl_overcommit_ratio / 100;
186 * Leave the last 3% for root
189 allowed -= allowed / 32;
190 allowed += total_swap_pages;
192 /* Don't let a single process grow too big:
193 leave 3% of the size of this process for other processes */
195 allowed -= mm->total_vm / 32;
197 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
200 vm_unacct_memory(pages);
206 * Requires inode->i_mapping->i_mmap_lock
208 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
209 struct file *file, struct address_space *mapping)
211 if (vma->vm_flags & VM_DENYWRITE)
212 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
213 if (vma->vm_flags & VM_SHARED)
214 mapping->i_mmap_writable--;
216 flush_dcache_mmap_lock(mapping);
217 if (unlikely(vma->vm_flags & VM_NONLINEAR))
218 list_del_init(&vma->shared.vm_set.list);
220 vma_prio_tree_remove(vma, &mapping->i_mmap);
221 flush_dcache_mmap_unlock(mapping);
225 * Unlink a file-based vm structure from its prio_tree, to hide
226 * vma from rmap and vmtruncate before freeing its page tables.
228 void unlink_file_vma(struct vm_area_struct *vma)
230 struct file *file = vma->vm_file;
233 struct address_space *mapping = file->f_mapping;
234 spin_lock(&mapping->i_mmap_lock);
235 __remove_shared_vm_struct(vma, file, mapping);
236 spin_unlock(&mapping->i_mmap_lock);
241 * Close a vm structure and free it, returning the next.
243 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
245 struct vm_area_struct *next = vma->vm_next;
248 if (vma->vm_ops && vma->vm_ops->close)
249 vma->vm_ops->close(vma);
252 if (vma->vm_flags & VM_EXECUTABLE)
253 removed_exe_file_vma(vma->vm_mm);
255 mpol_put(vma_policy(vma));
256 kmem_cache_free(vm_area_cachep, vma);
260 SYSCALL_DEFINE1(brk, unsigned long, brk)
262 unsigned long rlim, retval;
263 unsigned long newbrk, oldbrk;
264 struct mm_struct *mm = current->mm;
265 unsigned long min_brk;
267 down_write(&mm->mmap_sem);
269 #ifdef CONFIG_COMPAT_BRK
271 * CONFIG_COMPAT_BRK can still be overridden by setting
272 * randomize_va_space to 2, which will still cause mm->start_brk
273 * to be arbitrarily shifted
275 if (current->brk_randomized)
276 min_brk = mm->start_brk;
278 min_brk = mm->end_data;
280 min_brk = mm->start_brk;
286 * Check against rlimit here. If this check is done later after the test
287 * of oldbrk with newbrk then it can escape the test and let the data
288 * segment grow beyond its set limit the in case where the limit is
289 * not page aligned -Ram Gupta
291 rlim = rlimit(RLIMIT_DATA);
292 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
293 (mm->end_data - mm->start_data) > rlim)
296 newbrk = PAGE_ALIGN(brk);
297 oldbrk = PAGE_ALIGN(mm->brk);
298 if (oldbrk == newbrk)
301 /* Always allow shrinking brk. */
302 if (brk <= mm->brk) {
303 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
308 /* Check against existing mmap mappings. */
309 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
312 /* Ok, looks good - let it rip. */
313 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
319 up_write(&mm->mmap_sem);
324 static int browse_rb(struct rb_root *root)
327 struct rb_node *nd, *pn = NULL;
328 unsigned long prev = 0, pend = 0;
330 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
331 struct vm_area_struct *vma;
332 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
333 if (vma->vm_start < prev)
334 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
335 if (vma->vm_start < pend)
336 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
337 if (vma->vm_start > vma->vm_end)
338 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
341 prev = vma->vm_start;
345 for (nd = pn; nd; nd = rb_prev(nd)) {
349 printk("backwards %d, forwards %d\n", j, i), i = 0;
353 void validate_mm(struct mm_struct *mm)
357 struct vm_area_struct *tmp = mm->mmap;
362 if (i != mm->map_count)
363 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
364 i = browse_rb(&mm->mm_rb);
365 if (i != mm->map_count)
366 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
370 #define validate_mm(mm) do { } while (0)
373 static struct vm_area_struct *
374 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
375 struct vm_area_struct **pprev, struct rb_node ***rb_link,
376 struct rb_node ** rb_parent)
378 struct vm_area_struct * vma;
379 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
381 __rb_link = &mm->mm_rb.rb_node;
382 rb_prev = __rb_parent = NULL;
386 struct vm_area_struct *vma_tmp;
388 __rb_parent = *__rb_link;
389 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
391 if (vma_tmp->vm_end > addr) {
393 if (vma_tmp->vm_start <= addr)
395 __rb_link = &__rb_parent->rb_left;
397 rb_prev = __rb_parent;
398 __rb_link = &__rb_parent->rb_right;
404 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
405 *rb_link = __rb_link;
406 *rb_parent = __rb_parent;
411 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
412 struct vm_area_struct *prev, struct rb_node *rb_parent)
414 struct vm_area_struct *next;
416 if (vma->vm_flags & VM_EXEC)
417 arch_add_exec_range(mm, vma->vm_end);
421 next = prev->vm_next;
426 next = rb_entry(rb_parent,
427 struct vm_area_struct, vm_rb);
436 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
437 struct rb_node **rb_link, struct rb_node *rb_parent)
439 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
440 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
443 static void __vma_link_file(struct vm_area_struct *vma)
449 struct address_space *mapping = file->f_mapping;
451 if (vma->vm_flags & VM_DENYWRITE)
452 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
453 if (vma->vm_flags & VM_SHARED)
454 mapping->i_mmap_writable++;
456 flush_dcache_mmap_lock(mapping);
457 if (unlikely(vma->vm_flags & VM_NONLINEAR))
458 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
460 vma_prio_tree_insert(vma, &mapping->i_mmap);
461 flush_dcache_mmap_unlock(mapping);
466 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
467 struct vm_area_struct *prev, struct rb_node **rb_link,
468 struct rb_node *rb_parent)
470 __vma_link_list(mm, vma, prev, rb_parent);
471 __vma_link_rb(mm, vma, rb_link, rb_parent);
474 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
475 struct vm_area_struct *prev, struct rb_node **rb_link,
476 struct rb_node *rb_parent)
478 struct address_space *mapping = NULL;
481 mapping = vma->vm_file->f_mapping;
484 spin_lock(&mapping->i_mmap_lock);
485 vma->vm_truncate_count = mapping->truncate_count;
488 __vma_link(mm, vma, prev, rb_link, rb_parent);
489 __vma_link_file(vma);
492 spin_unlock(&mapping->i_mmap_lock);
499 * Helper for vma_adjust in the split_vma insert case:
500 * insert vm structure into list and rbtree and anon_vma,
501 * but it has already been inserted into prio_tree earlier.
503 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
505 struct vm_area_struct *__vma, *prev;
506 struct rb_node **rb_link, *rb_parent;
508 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
509 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
510 __vma_link(mm, vma, prev, rb_link, rb_parent);
515 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
516 struct vm_area_struct *prev)
518 struct vm_area_struct *next = vma->vm_next;
520 prev->vm_next = next;
522 next->vm_prev = prev;
523 rb_erase(&vma->vm_rb, &mm->mm_rb);
524 if (mm->mmap_cache == vma)
525 mm->mmap_cache = prev;
526 if (vma->vm_flags & VM_EXEC)
527 arch_remove_exec_range(mm, vma->vm_end);
531 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
532 * is already present in an i_mmap tree without adjusting the tree.
533 * The following helper function should be used when such adjustments
534 * are necessary. The "insert" vma (if any) is to be inserted
535 * before we drop the necessary locks.
537 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
538 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
540 struct mm_struct *mm = vma->vm_mm;
541 struct vm_area_struct *next = vma->vm_next;
542 struct vm_area_struct *importer = NULL;
543 struct address_space *mapping = NULL;
544 struct prio_tree_root *root = NULL;
545 struct anon_vma *anon_vma = NULL;
546 struct file *file = vma->vm_file;
547 long adjust_next = 0;
550 if (next && !insert) {
551 struct vm_area_struct *exporter = NULL;
553 if (end >= next->vm_end) {
555 * vma expands, overlapping all the next, and
556 * perhaps the one after too (mprotect case 6).
558 again: remove_next = 1 + (end > next->vm_end);
562 } else if (end > next->vm_start) {
564 * vma expands, overlapping part of the next:
565 * mprotect case 5 shifting the boundary up.
567 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
570 } else if (end < vma->vm_end) {
572 * vma shrinks, and !insert tells it's not
573 * split_vma inserting another: so it must be
574 * mprotect case 4 shifting the boundary down.
576 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
582 * Easily overlooked: when mprotect shifts the boundary,
583 * make sure the expanding vma has anon_vma set if the
584 * shrinking vma had, to cover any anon pages imported.
586 if (exporter && exporter->anon_vma && !importer->anon_vma) {
587 if (anon_vma_clone(importer, exporter))
589 importer->anon_vma = exporter->anon_vma;
594 mapping = file->f_mapping;
595 if (!(vma->vm_flags & VM_NONLINEAR))
596 root = &mapping->i_mmap;
597 spin_lock(&mapping->i_mmap_lock);
599 vma->vm_truncate_count != next->vm_truncate_count) {
601 * unmap_mapping_range might be in progress:
602 * ensure that the expanding vma is rescanned.
604 importer->vm_truncate_count = 0;
607 insert->vm_truncate_count = vma->vm_truncate_count;
609 * Put into prio_tree now, so instantiated pages
610 * are visible to arm/parisc __flush_dcache_page
611 * throughout; but we cannot insert into address
612 * space until vma start or end is updated.
614 __vma_link_file(insert);
618 vma_adjust_trans_huge(vma, start, end, adjust_next);
621 * When changing only vma->vm_end, we don't really need anon_vma
622 * lock. This is a fairly rare case by itself, but the anon_vma
623 * lock may be shared between many sibling processes. Skipping
624 * the lock for brk adjustments makes a difference sometimes.
626 if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
627 anon_vma = vma->anon_vma;
628 anon_vma_lock(anon_vma);
632 flush_dcache_mmap_lock(mapping);
633 vma_prio_tree_remove(vma, root);
635 vma_prio_tree_remove(next, root);
638 vma->vm_start = start;
640 vma->vm_pgoff = pgoff;
642 next->vm_start += adjust_next << PAGE_SHIFT;
643 next->vm_pgoff += adjust_next;
648 vma_prio_tree_insert(next, root);
649 vma_prio_tree_insert(vma, root);
650 flush_dcache_mmap_unlock(mapping);
655 * vma_merge has merged next into vma, and needs
656 * us to remove next before dropping the locks.
658 __vma_unlink(mm, next, vma);
660 __remove_shared_vm_struct(next, file, mapping);
663 * split_vma has split insert from vma, and needs
664 * us to insert it before dropping the locks
665 * (it may either follow vma or precede it).
667 __insert_vm_struct(mm, insert);
671 anon_vma_unlock(anon_vma);
673 spin_unlock(&mapping->i_mmap_lock);
678 if (next->vm_flags & VM_EXECUTABLE)
679 removed_exe_file_vma(mm);
682 anon_vma_merge(vma, next);
684 mpol_put(vma_policy(next));
685 kmem_cache_free(vm_area_cachep, next);
687 * In mprotect's case 6 (see comments on vma_merge),
688 * we must remove another next too. It would clutter
689 * up the code too much to do both in one go.
691 if (remove_next == 2) {
703 * If the vma has a ->close operation then the driver probably needs to release
704 * per-vma resources, so we don't attempt to merge those.
706 static inline int is_mergeable_vma(struct vm_area_struct *vma,
707 struct file *file, unsigned long vm_flags)
709 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
710 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
712 if (vma->vm_file != file)
714 if (vma->vm_ops && vma->vm_ops->close)
719 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
720 struct anon_vma *anon_vma2)
722 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
726 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
727 * in front of (at a lower virtual address and file offset than) the vma.
729 * We cannot merge two vmas if they have differently assigned (non-NULL)
730 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
732 * We don't check here for the merged mmap wrapping around the end of pagecache
733 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
734 * wrap, nor mmaps which cover the final page at index -1UL.
737 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
738 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
740 if (is_mergeable_vma(vma, file, vm_flags) &&
741 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
742 if (vma->vm_pgoff == vm_pgoff)
749 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
750 * beyond (at a higher virtual address and file offset than) the vma.
752 * We cannot merge two vmas if they have differently assigned (non-NULL)
753 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
756 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
757 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
759 if (is_mergeable_vma(vma, file, vm_flags) &&
760 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
762 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
763 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
770 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
771 * whether that can be merged with its predecessor or its successor.
772 * Or both (it neatly fills a hole).
774 * In most cases - when called for mmap, brk or mremap - [addr,end) is
775 * certain not to be mapped by the time vma_merge is called; but when
776 * called for mprotect, it is certain to be already mapped (either at
777 * an offset within prev, or at the start of next), and the flags of
778 * this area are about to be changed to vm_flags - and the no-change
779 * case has already been eliminated.
781 * The following mprotect cases have to be considered, where AAAA is
782 * the area passed down from mprotect_fixup, never extending beyond one
783 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
785 * AAAA AAAA AAAA AAAA
786 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
787 * cannot merge might become might become might become
788 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
789 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
790 * mremap move: PPPPNNNNNNNN 8
792 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
793 * might become case 1 below case 2 below case 3 below
795 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
796 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
798 struct vm_area_struct *vma_merge(struct mm_struct *mm,
799 struct vm_area_struct *prev, unsigned long addr,
800 unsigned long end, unsigned long vm_flags,
801 struct anon_vma *anon_vma, struct file *file,
802 pgoff_t pgoff, struct mempolicy *policy)
804 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
805 struct vm_area_struct *area, *next;
809 * We later require that vma->vm_flags == vm_flags,
810 * so this tests vma->vm_flags & VM_SPECIAL, too.
812 if (vm_flags & VM_SPECIAL)
816 next = prev->vm_next;
820 if (next && next->vm_end == end) /* cases 6, 7, 8 */
821 next = next->vm_next;
824 * Can it merge with the predecessor?
826 if (prev && prev->vm_end == addr &&
827 mpol_equal(vma_policy(prev), policy) &&
828 can_vma_merge_after(prev, vm_flags,
829 anon_vma, file, pgoff)) {
831 * OK, it can. Can we now merge in the successor as well?
833 if (next && end == next->vm_start &&
834 mpol_equal(policy, vma_policy(next)) &&
835 can_vma_merge_before(next, vm_flags,
836 anon_vma, file, pgoff+pglen) &&
837 is_mergeable_anon_vma(prev->anon_vma,
840 err = vma_adjust(prev, prev->vm_start,
841 next->vm_end, prev->vm_pgoff, NULL);
842 } else /* cases 2, 5, 7 */
843 err = vma_adjust(prev, prev->vm_start,
844 end, prev->vm_pgoff, NULL);
845 if (prev->vm_flags & VM_EXEC)
846 arch_add_exec_range(mm, prev->vm_end);
849 khugepaged_enter_vma_merge(prev);
854 * Can this new request be merged in front of next?
856 if (next && end == next->vm_start &&
857 mpol_equal(policy, vma_policy(next)) &&
858 can_vma_merge_before(next, vm_flags,
859 anon_vma, file, pgoff+pglen)) {
860 if (prev && addr < prev->vm_end) /* case 4 */
861 err = vma_adjust(prev, prev->vm_start,
862 addr, prev->vm_pgoff, NULL);
863 else /* cases 3, 8 */
864 err = vma_adjust(area, addr, next->vm_end,
865 next->vm_pgoff - pglen, NULL);
868 khugepaged_enter_vma_merge(area);
876 * Rough compatbility check to quickly see if it's even worth looking
877 * at sharing an anon_vma.
879 * They need to have the same vm_file, and the flags can only differ
880 * in things that mprotect may change.
882 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
883 * we can merge the two vma's. For example, we refuse to merge a vma if
884 * there is a vm_ops->close() function, because that indicates that the
885 * driver is doing some kind of reference counting. But that doesn't
886 * really matter for the anon_vma sharing case.
888 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
890 return a->vm_end == b->vm_start &&
891 mpol_equal(vma_policy(a), vma_policy(b)) &&
892 a->vm_file == b->vm_file &&
893 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
894 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
898 * Do some basic sanity checking to see if we can re-use the anon_vma
899 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
900 * the same as 'old', the other will be the new one that is trying
901 * to share the anon_vma.
903 * NOTE! This runs with mm_sem held for reading, so it is possible that
904 * the anon_vma of 'old' is concurrently in the process of being set up
905 * by another page fault trying to merge _that_. But that's ok: if it
906 * is being set up, that automatically means that it will be a singleton
907 * acceptable for merging, so we can do all of this optimistically. But
908 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
910 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
911 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
912 * is to return an anon_vma that is "complex" due to having gone through
915 * We also make sure that the two vma's are compatible (adjacent,
916 * and with the same memory policies). That's all stable, even with just
917 * a read lock on the mm_sem.
919 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
921 if (anon_vma_compatible(a, b)) {
922 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
924 if (anon_vma && list_is_singular(&old->anon_vma_chain))
931 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
932 * neighbouring vmas for a suitable anon_vma, before it goes off
933 * to allocate a new anon_vma. It checks because a repetitive
934 * sequence of mprotects and faults may otherwise lead to distinct
935 * anon_vmas being allocated, preventing vma merge in subsequent
938 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
940 struct anon_vma *anon_vma;
941 struct vm_area_struct *near;
947 anon_vma = reusable_anon_vma(near, vma, near);
952 * It is potentially slow to have to call find_vma_prev here.
953 * But it's only on the first write fault on the vma, not
954 * every time, and we could devise a way to avoid it later
955 * (e.g. stash info in next's anon_vma_node when assigning
956 * an anon_vma, or when trying vma_merge). Another time.
958 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
962 anon_vma = reusable_anon_vma(near, near, vma);
967 * There's no absolute need to look only at touching neighbours:
968 * we could search further afield for "compatible" anon_vmas.
969 * But it would probably just be a waste of time searching,
970 * or lead to too many vmas hanging off the same anon_vma.
971 * We're trying to allow mprotect remerging later on,
972 * not trying to minimize memory used for anon_vmas.
977 #ifdef CONFIG_PROC_FS
978 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
979 struct file *file, long pages)
981 const unsigned long stack_flags
982 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
985 mm->shared_vm += pages;
986 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
987 mm->exec_vm += pages;
988 } else if (flags & stack_flags)
989 mm->stack_vm += pages;
990 if (flags & (VM_RESERVED|VM_IO))
991 mm->reserved_vm += pages;
993 #endif /* CONFIG_PROC_FS */
996 * The caller must hold down_write(¤t->mm->mmap_sem).
999 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1000 unsigned long len, unsigned long prot,
1001 unsigned long flags, unsigned long pgoff)
1003 struct mm_struct * mm = current->mm;
1004 struct inode *inode;
1005 unsigned int vm_flags;
1007 unsigned long reqprot = prot;
1010 * Does the application expect PROT_READ to imply PROT_EXEC?
1012 * (the exception is when the underlying filesystem is noexec
1013 * mounted, in which case we dont add PROT_EXEC.)
1015 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1016 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1022 if (!(flags & MAP_FIXED))
1023 addr = round_hint_to_min(addr);
1025 /* Careful about overflows.. */
1026 len = PAGE_ALIGN(len);
1030 /* offset overflow? */
1031 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1034 /* Too many mappings? */
1035 if (mm->map_count > sysctl_max_map_count)
1038 /* Obtain the address to map to. we verify (or select) it and ensure
1039 * that it represents a valid section of the address space.
1041 addr = get_unmapped_area_prot(file, addr, len, pgoff, flags,
1043 if (addr & ~PAGE_MASK)
1046 /* Do simple checking here so the lower-level routines won't have
1047 * to. we assume access permissions have been handled by the open
1048 * of the memory object, so we don't do any here.
1050 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1051 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1053 if (flags & MAP_LOCKED)
1054 if (!can_do_mlock())
1057 /* mlock MCL_FUTURE? */
1058 if (vm_flags & VM_LOCKED) {
1059 unsigned long locked, lock_limit;
1060 locked = len >> PAGE_SHIFT;
1061 locked += mm->locked_vm;
1062 lock_limit = rlimit(RLIMIT_MEMLOCK);
1063 lock_limit >>= PAGE_SHIFT;
1064 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1068 inode = file ? file->f_path.dentry->d_inode : NULL;
1071 switch (flags & MAP_TYPE) {
1073 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1077 * Make sure we don't allow writing to an append-only
1080 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1084 * Make sure there are no mandatory locks on the file.
1086 if (locks_verify_locked(inode))
1089 vm_flags |= VM_SHARED | VM_MAYSHARE;
1090 if (!(file->f_mode & FMODE_WRITE))
1091 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1095 if (!(file->f_mode & FMODE_READ))
1097 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1098 if (vm_flags & VM_EXEC)
1100 vm_flags &= ~VM_MAYEXEC;
1103 if (!file->f_op || !file->f_op->mmap)
1111 switch (flags & MAP_TYPE) {
1117 vm_flags |= VM_SHARED | VM_MAYSHARE;
1121 * Set pgoff according to addr for anon_vma.
1123 pgoff = addr >> PAGE_SHIFT;
1130 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1134 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1136 EXPORT_SYMBOL(do_mmap_pgoff);
1138 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1139 unsigned long, prot, unsigned long, flags,
1140 unsigned long, fd, unsigned long, pgoff)
1142 struct file *file = NULL;
1143 unsigned long retval = -EBADF;
1145 if (!(flags & MAP_ANONYMOUS)) {
1146 audit_mmap_fd(fd, flags);
1147 if (unlikely(flags & MAP_HUGETLB))
1152 } else if (flags & MAP_HUGETLB) {
1153 struct user_struct *user = NULL;
1155 * VM_NORESERVE is used because the reservations will be
1156 * taken when vm_ops->mmap() is called
1157 * A dummy user value is used because we are not locking
1158 * memory so no accounting is necessary
1160 len = ALIGN(len, huge_page_size(&default_hstate));
1161 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1162 &user, HUGETLB_ANONHUGE_INODE);
1164 return PTR_ERR(file);
1167 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1169 down_write(¤t->mm->mmap_sem);
1170 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1171 up_write(¤t->mm->mmap_sem);
1179 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1180 struct mmap_arg_struct {
1184 unsigned long flags;
1186 unsigned long offset;
1189 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1191 struct mmap_arg_struct a;
1193 if (copy_from_user(&a, arg, sizeof(a)))
1195 if (a.offset & ~PAGE_MASK)
1198 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1199 a.offset >> PAGE_SHIFT);
1201 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1204 * Some shared mappigns will want the pages marked read-only
1205 * to track write events. If so, we'll downgrade vm_page_prot
1206 * to the private version (using protection_map[] without the
1209 int vma_wants_writenotify(struct vm_area_struct *vma)
1211 unsigned int vm_flags = vma->vm_flags;
1213 /* If it was private or non-writable, the write bit is already clear */
1214 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1217 /* The backer wishes to know when pages are first written to? */
1218 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1221 /* The open routine did something to the protections already? */
1222 if (pgprot_val(vma->vm_page_prot) !=
1223 pgprot_val(vm_get_page_prot(vm_flags)))
1226 /* Specialty mapping? */
1227 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1230 /* Can the mapping track the dirty pages? */
1231 return vma->vm_file && vma->vm_file->f_mapping &&
1232 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1236 * We account for memory if it's a private writeable mapping,
1237 * not hugepages and VM_NORESERVE wasn't set.
1239 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1242 * hugetlb has its own accounting separate from the core VM
1243 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1245 if (file && is_file_hugepages(file))
1248 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1251 unsigned long mmap_region(struct file *file, unsigned long addr,
1252 unsigned long len, unsigned long flags,
1253 unsigned int vm_flags, unsigned long pgoff)
1255 struct mm_struct *mm = current->mm;
1256 struct vm_area_struct *vma, *prev;
1257 int correct_wcount = 0;
1259 struct rb_node **rb_link, *rb_parent;
1260 unsigned long charged = 0;
1261 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1263 /* Clear old maps */
1266 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1267 if (vma && vma->vm_start < addr + len) {
1268 if (do_munmap(mm, addr, len))
1273 /* Check against address space limit. */
1274 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1278 * Set 'VM_NORESERVE' if we should not account for the
1279 * memory use of this mapping.
1281 if ((flags & MAP_NORESERVE)) {
1282 /* We honor MAP_NORESERVE if allowed to overcommit */
1283 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1284 vm_flags |= VM_NORESERVE;
1286 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1287 if (file && is_file_hugepages(file))
1288 vm_flags |= VM_NORESERVE;
1292 * Private writable mapping: check memory availability
1294 if (accountable_mapping(file, vm_flags)) {
1295 charged = len >> PAGE_SHIFT;
1296 if (security_vm_enough_memory(charged))
1298 vm_flags |= VM_ACCOUNT;
1302 * Can we just expand an old mapping?
1304 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1309 * Determine the object being mapped and call the appropriate
1310 * specific mapper. the address has already been validated, but
1311 * not unmapped, but the maps are removed from the list.
1313 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1320 vma->vm_start = addr;
1321 vma->vm_end = addr + len;
1322 vma->vm_flags = vm_flags;
1323 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1324 vma->vm_pgoff = pgoff;
1325 INIT_LIST_HEAD(&vma->anon_vma_chain);
1329 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1331 if (vm_flags & VM_DENYWRITE) {
1332 error = deny_write_access(file);
1337 vma->vm_file = file;
1339 error = file->f_op->mmap(file, vma);
1341 goto unmap_and_free_vma;
1342 if (vm_flags & VM_EXECUTABLE)
1343 added_exe_file_vma(mm);
1345 /* Can addr have changed??
1347 * Answer: Yes, several device drivers can do it in their
1348 * f_op->mmap method. -DaveM
1350 addr = vma->vm_start;
1351 pgoff = vma->vm_pgoff;
1352 vm_flags = vma->vm_flags;
1353 } else if (vm_flags & VM_SHARED) {
1354 error = shmem_zero_setup(vma);
1359 if (vma_wants_writenotify(vma)) {
1360 pgprot_t pprot = vma->vm_page_prot;
1362 /* Can vma->vm_page_prot have changed??
1364 * Answer: Yes, drivers may have changed it in their
1365 * f_op->mmap method.
1367 * Ensures that vmas marked as uncached stay that way.
1369 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1370 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1371 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1374 vma_link(mm, vma, prev, rb_link, rb_parent);
1375 file = vma->vm_file;
1377 /* Once vma denies write, undo our temporary denial count */
1379 atomic_inc(&inode->i_writecount);
1381 perf_event_mmap(vma);
1383 mm->total_vm += len >> PAGE_SHIFT;
1384 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1385 if (vm_flags & VM_LOCKED) {
1386 if (!mlock_vma_pages_range(vma, addr, addr + len))
1387 mm->locked_vm += (len >> PAGE_SHIFT);
1388 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1389 make_pages_present(addr, addr + len);
1394 atomic_inc(&inode->i_writecount);
1395 vma->vm_file = NULL;
1398 /* Undo any partial mapping done by a device driver. */
1399 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1402 kmem_cache_free(vm_area_cachep, vma);
1405 vm_unacct_memory(charged);
1409 /* Get an address range which is currently unmapped.
1410 * For shmat() with addr=0.
1412 * Ugly calling convention alert:
1413 * Return value with the low bits set means error value,
1415 * if (ret & ~PAGE_MASK)
1418 * This function "knows" that -ENOMEM has the bits set.
1420 #ifndef HAVE_ARCH_UNMAPPED_AREA
1422 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1423 unsigned long len, unsigned long pgoff, unsigned long flags)
1425 struct mm_struct *mm = current->mm;
1426 struct vm_area_struct *vma;
1427 unsigned long start_addr;
1429 if (len > TASK_SIZE)
1432 if (flags & MAP_FIXED)
1436 addr = PAGE_ALIGN(addr);
1437 vma = find_vma(mm, addr);
1438 if (TASK_SIZE - len >= addr &&
1439 (!vma || addr + len <= vma->vm_start))
1442 if (len > mm->cached_hole_size) {
1443 start_addr = addr = mm->free_area_cache;
1445 start_addr = addr = TASK_UNMAPPED_BASE;
1446 mm->cached_hole_size = 0;
1450 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1451 /* At this point: (!vma || addr < vma->vm_end). */
1452 if (TASK_SIZE - len < addr) {
1454 * Start a new search - just in case we missed
1457 if (start_addr != TASK_UNMAPPED_BASE) {
1458 addr = TASK_UNMAPPED_BASE;
1460 mm->cached_hole_size = 0;
1465 if (!vma || addr + len <= vma->vm_start) {
1467 * Remember the place where we stopped the search:
1469 mm->free_area_cache = addr + len;
1472 if (addr + mm->cached_hole_size < vma->vm_start)
1473 mm->cached_hole_size = vma->vm_start - addr;
1479 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1482 * Is this a new hole at the lowest possible address?
1484 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1485 mm->free_area_cache = addr;
1486 mm->cached_hole_size = ~0UL;
1491 * This mmap-allocator allocates new areas top-down from below the
1492 * stack's low limit (the base):
1494 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1496 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1497 const unsigned long len, const unsigned long pgoff,
1498 const unsigned long flags)
1500 struct vm_area_struct *vma;
1501 struct mm_struct *mm = current->mm;
1502 unsigned long addr = addr0;
1504 /* requested length too big for entire address space */
1505 if (len > TASK_SIZE)
1508 if (flags & MAP_FIXED)
1511 /* requesting a specific address */
1513 addr = PAGE_ALIGN(addr);
1514 vma = find_vma(mm, addr);
1515 if (TASK_SIZE - len >= addr &&
1516 (!vma || addr + len <= vma->vm_start))
1520 /* check if free_area_cache is useful for us */
1521 if (len <= mm->cached_hole_size) {
1522 mm->cached_hole_size = 0;
1523 mm->free_area_cache = mm->mmap_base;
1526 /* either no address requested or can't fit in requested address hole */
1527 addr = mm->free_area_cache;
1529 /* make sure it can fit in the remaining address space */
1531 vma = find_vma(mm, addr-len);
1532 if (!vma || addr <= vma->vm_start)
1533 /* remember the address as a hint for next time */
1534 return (mm->free_area_cache = addr-len);
1537 if (mm->mmap_base < len)
1540 addr = mm->mmap_base-len;
1544 * Lookup failure means no vma is above this address,
1545 * else if new region fits below vma->vm_start,
1546 * return with success:
1548 vma = find_vma(mm, addr);
1549 if (!vma || addr+len <= vma->vm_start)
1550 /* remember the address as a hint for next time */
1551 return (mm->free_area_cache = addr);
1553 /* remember the largest hole we saw so far */
1554 if (addr + mm->cached_hole_size < vma->vm_start)
1555 mm->cached_hole_size = vma->vm_start - addr;
1557 /* try just below the current vma->vm_start */
1558 addr = vma->vm_start-len;
1559 } while (len < vma->vm_start);
1563 * A failed mmap() very likely causes application failure,
1564 * so fall back to the bottom-up function here. This scenario
1565 * can happen with large stack limits and large mmap()
1568 mm->cached_hole_size = ~0UL;
1569 mm->free_area_cache = TASK_UNMAPPED_BASE;
1570 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1572 * Restore the topdown base:
1574 mm->free_area_cache = mm->mmap_base;
1575 mm->cached_hole_size = ~0UL;
1581 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1584 * Is this a new hole at the highest possible address?
1586 if (addr > mm->free_area_cache)
1587 mm->free_area_cache = addr;
1589 /* dont allow allocations above current base */
1590 if (mm->free_area_cache > mm->mmap_base)
1591 mm->free_area_cache = mm->mmap_base;
1595 get_unmapped_area_prot(struct file *file, unsigned long addr, unsigned long len,
1596 unsigned long pgoff, unsigned long flags, int exec)
1598 unsigned long (*get_area)(struct file *, unsigned long,
1599 unsigned long, unsigned long, unsigned long);
1601 unsigned long error = arch_mmap_check(addr, len, flags);
1605 /* Careful about overflows.. */
1606 if (len > TASK_SIZE)
1609 if (exec && current->mm->get_unmapped_exec_area)
1610 get_area = current->mm->get_unmapped_exec_area;
1612 get_area = current->mm->get_unmapped_area;
1614 if (file && file->f_op && file->f_op->get_unmapped_area)
1615 get_area = file->f_op->get_unmapped_area;
1616 addr = get_area(file, addr, len, pgoff, flags);
1617 if (IS_ERR_VALUE(addr))
1620 if (addr > TASK_SIZE - len)
1622 if (addr & ~PAGE_MASK)
1625 return arch_rebalance_pgtables(addr, len);
1627 EXPORT_SYMBOL(get_unmapped_area_prot);
1629 static bool should_randomize(void)
1631 return (current->flags & PF_RANDOMIZE) &&
1632 !(current->personality & ADDR_NO_RANDOMIZE);
1635 #define SHLIB_BASE 0x00110000
1638 arch_get_unmapped_exec_area(struct file *filp, unsigned long addr0,
1639 unsigned long len0, unsigned long pgoff, unsigned long flags)
1641 unsigned long addr = addr0, len = len0;
1642 struct mm_struct *mm = current->mm;
1643 struct vm_area_struct *vma;
1646 if (len > TASK_SIZE)
1649 if (flags & MAP_FIXED)
1653 addr = !should_randomize() ? SHLIB_BASE :
1654 randomize_range(SHLIB_BASE, 0x01000000, len);
1657 addr = PAGE_ALIGN(addr);
1658 vma = find_vma(mm, addr);
1659 if (TASK_SIZE - len >= addr &&
1660 (!vma || addr + len <= vma->vm_start))
1665 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1666 /* At this point: (!vma || addr < vma->vm_end). */
1667 if (TASK_SIZE - len < addr)
1670 if (!vma || addr + len <= vma->vm_start) {
1672 * Must not let a PROT_EXEC mapping get into the
1675 if (addr + len > mm->brk)
1679 * Up until the brk area we randomize addresses
1680 * as much as possible:
1682 if (addr >= 0x01000000 && should_randomize()) {
1683 tmp = randomize_range(0x01000000,
1684 PAGE_ALIGN(max(mm->start_brk,
1685 (unsigned long)0x08000000)), len);
1686 vma = find_vma(mm, tmp);
1687 if (TASK_SIZE - len >= tmp &&
1688 (!vma || tmp + len <= vma->vm_start))
1692 * Ok, randomization didnt work out - return
1693 * the result of the linear search:
1701 return current->mm->get_unmapped_area(filp, addr0, len0, pgoff, flags);
1705 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1706 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1708 struct vm_area_struct *vma = NULL;
1711 /* Check the cache first. */
1712 /* (Cache hit rate is typically around 35%.) */
1713 vma = mm->mmap_cache;
1714 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1715 struct rb_node * rb_node;
1717 rb_node = mm->mm_rb.rb_node;
1721 struct vm_area_struct * vma_tmp;
1723 vma_tmp = rb_entry(rb_node,
1724 struct vm_area_struct, vm_rb);
1726 if (vma_tmp->vm_end > addr) {
1728 if (vma_tmp->vm_start <= addr)
1730 rb_node = rb_node->rb_left;
1732 rb_node = rb_node->rb_right;
1735 mm->mmap_cache = vma;
1741 EXPORT_SYMBOL(find_vma);
1743 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1744 struct vm_area_struct *
1745 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1746 struct vm_area_struct **pprev)
1748 struct vm_area_struct *vma = NULL, *prev = NULL;
1749 struct rb_node *rb_node;
1753 /* Guard against addr being lower than the first VMA */
1756 /* Go through the RB tree quickly. */
1757 rb_node = mm->mm_rb.rb_node;
1760 struct vm_area_struct *vma_tmp;
1761 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1763 if (addr < vma_tmp->vm_end) {
1764 rb_node = rb_node->rb_left;
1767 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1769 rb_node = rb_node->rb_right;
1775 return prev ? prev->vm_next : vma;
1779 * Verify that the stack growth is acceptable and
1780 * update accounting. This is shared with both the
1781 * grow-up and grow-down cases.
1783 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1785 struct mm_struct *mm = vma->vm_mm;
1786 struct rlimit *rlim = current->signal->rlim;
1787 unsigned long new_start;
1789 /* address space limit tests */
1790 if (!may_expand_vm(mm, grow))
1793 /* Stack limit test */
1794 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1797 /* mlock limit tests */
1798 if (vma->vm_flags & VM_LOCKED) {
1799 unsigned long locked;
1800 unsigned long limit;
1801 locked = mm->locked_vm + grow;
1802 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1803 limit >>= PAGE_SHIFT;
1804 if (locked > limit && !capable(CAP_IPC_LOCK))
1808 /* Check to ensure the stack will not grow into a hugetlb-only region */
1809 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1811 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1815 * Overcommit.. This must be the final test, as it will
1816 * update security statistics.
1818 if (security_vm_enough_memory_mm(mm, grow))
1821 /* Ok, everything looks good - let it rip */
1822 mm->total_vm += grow;
1823 if (vma->vm_flags & VM_LOCKED)
1824 mm->locked_vm += grow;
1825 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1829 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1831 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1832 * vma is the last one with address > vma->vm_end. Have to extend vma.
1834 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1838 if (!(vma->vm_flags & VM_GROWSUP))
1842 * We must make sure the anon_vma is allocated
1843 * so that the anon_vma locking is not a noop.
1845 if (unlikely(anon_vma_prepare(vma)))
1847 vma_lock_anon_vma(vma);
1850 * vma->vm_start/vm_end cannot change under us because the caller
1851 * is required to hold the mmap_sem in read mode. We need the
1852 * anon_vma lock to serialize against concurrent expand_stacks.
1853 * Also guard against wrapping around to address 0.
1855 if (address < PAGE_ALIGN(address+4))
1856 address = PAGE_ALIGN(address+4);
1858 vma_unlock_anon_vma(vma);
1863 /* Somebody else might have raced and expanded it already */
1864 if (address > vma->vm_end) {
1865 unsigned long size, grow;
1867 size = address - vma->vm_start;
1868 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1870 error = acct_stack_growth(vma, size, grow);
1872 vma->vm_end = address;
1873 perf_event_mmap(vma);
1876 vma_unlock_anon_vma(vma);
1877 khugepaged_enter_vma_merge(vma);
1880 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1883 * vma is the first one with address < vma->vm_start. Have to extend vma.
1885 static int expand_downwards(struct vm_area_struct *vma,
1886 unsigned long address)
1891 * We must make sure the anon_vma is allocated
1892 * so that the anon_vma locking is not a noop.
1894 if (unlikely(anon_vma_prepare(vma)))
1897 address &= PAGE_MASK;
1898 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1902 vma_lock_anon_vma(vma);
1905 * vma->vm_start/vm_end cannot change under us because the caller
1906 * is required to hold the mmap_sem in read mode. We need the
1907 * anon_vma lock to serialize against concurrent expand_stacks.
1910 /* Somebody else might have raced and expanded it already */
1911 if (address < vma->vm_start) {
1912 unsigned long size, grow;
1914 size = vma->vm_end - address;
1915 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1918 if (grow <= vma->vm_pgoff) {
1919 error = acct_stack_growth(vma, size, grow);
1921 vma->vm_start = address;
1922 vma->vm_pgoff -= grow;
1923 perf_event_mmap(vma);
1927 vma_unlock_anon_vma(vma);
1928 khugepaged_enter_vma_merge(vma);
1932 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1934 return expand_downwards(vma, address);
1937 #ifdef CONFIG_STACK_GROWSUP
1938 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1940 return expand_upwards(vma, address);
1943 struct vm_area_struct *
1944 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1946 struct vm_area_struct *vma, *prev;
1949 vma = find_vma_prev(mm, addr, &prev);
1950 if (vma && (vma->vm_start <= addr))
1952 if (!prev || expand_stack(prev, addr))
1954 if (prev->vm_flags & VM_LOCKED) {
1955 mlock_vma_pages_range(prev, addr, prev->vm_end);
1960 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1962 return expand_downwards(vma, address);
1965 struct vm_area_struct *
1966 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1968 struct vm_area_struct * vma;
1969 unsigned long start;
1972 vma = find_vma(mm,addr);
1975 if (vma->vm_start <= addr)
1977 if (!(vma->vm_flags & VM_GROWSDOWN))
1979 start = vma->vm_start;
1980 if (expand_stack(vma, addr))
1982 if (vma->vm_flags & VM_LOCKED) {
1983 mlock_vma_pages_range(vma, addr, start);
1990 * Ok - we have the memory areas we should free on the vma list,
1991 * so release them, and do the vma updates.
1993 * Called with the mm semaphore held.
1995 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1997 /* Update high watermark before we lower total_vm */
1998 update_hiwater_vm(mm);
2000 long nrpages = vma_pages(vma);
2002 mm->total_vm -= nrpages;
2003 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2004 vma = remove_vma(vma);
2010 * Get rid of page table information in the indicated region.
2012 * Called with the mm semaphore held.
2014 static void unmap_region(struct mm_struct *mm,
2015 struct vm_area_struct *vma, struct vm_area_struct *prev,
2016 unsigned long start, unsigned long end)
2018 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
2019 struct mmu_gather *tlb;
2020 unsigned long nr_accounted = 0;
2023 tlb = tlb_gather_mmu(mm, 0);
2024 update_hiwater_rss(mm);
2025 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
2026 vm_unacct_memory(nr_accounted);
2027 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
2028 next? next->vm_start: 0);
2029 tlb_finish_mmu(tlb, start, end);
2033 * Create a list of vma's touched by the unmap, removing them from the mm's
2034 * vma list as we go..
2037 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2038 struct vm_area_struct *prev, unsigned long end)
2040 struct vm_area_struct **insertion_point;
2041 struct vm_area_struct *tail_vma = NULL;
2044 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2045 vma->vm_prev = NULL;
2047 rb_erase(&vma->vm_rb, &mm->mm_rb);
2051 } while (vma && vma->vm_start < end);
2052 *insertion_point = vma;
2054 vma->vm_prev = prev;
2055 tail_vma->vm_next = NULL;
2056 if (mm->unmap_area == arch_unmap_area)
2057 addr = prev ? prev->vm_end : mm->mmap_base;
2059 addr = vma ? vma->vm_start : mm->mmap_base;
2060 mm->unmap_area(mm, addr);
2061 mm->mmap_cache = NULL; /* Kill the cache. */
2065 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2066 * munmap path where it doesn't make sense to fail.
2068 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
2069 unsigned long addr, int new_below)
2071 struct mempolicy *pol;
2072 struct vm_area_struct *new;
2075 if (is_vm_hugetlb_page(vma) && (addr &
2076 ~(huge_page_mask(hstate_vma(vma)))))
2079 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2083 /* most fields are the same, copy all, and then fixup */
2086 INIT_LIST_HEAD(&new->anon_vma_chain);
2091 new->vm_start = addr;
2092 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2095 pol = mpol_dup(vma_policy(vma));
2100 vma_set_policy(new, pol);
2102 if (anon_vma_clone(new, vma))
2106 get_file(new->vm_file);
2107 if (vma->vm_flags & VM_EXECUTABLE)
2108 added_exe_file_vma(mm);
2111 if (new->vm_ops && new->vm_ops->open)
2112 new->vm_ops->open(new);
2115 unsigned long old_end = vma->vm_end;
2117 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2118 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2119 if (vma->vm_flags & VM_EXEC)
2120 arch_remove_exec_range(mm, old_end);
2122 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2128 /* Clean everything up if vma_adjust failed. */
2129 if (new->vm_ops && new->vm_ops->close)
2130 new->vm_ops->close(new);
2132 if (vma->vm_flags & VM_EXECUTABLE)
2133 removed_exe_file_vma(mm);
2136 unlink_anon_vmas(new);
2140 kmem_cache_free(vm_area_cachep, new);
2146 * Split a vma into two pieces at address 'addr', a new vma is allocated
2147 * either for the first part or the tail.
2149 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2150 unsigned long addr, int new_below)
2152 if (mm->map_count >= sysctl_max_map_count)
2155 return __split_vma(mm, vma, addr, new_below);
2158 /* Munmap is split into 2 main parts -- this part which finds
2159 * what needs doing, and the areas themselves, which do the
2160 * work. This now handles partial unmappings.
2161 * Jeremy Fitzhardinge <jeremy@goop.org>
2163 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2166 struct vm_area_struct *vma, *prev, *last;
2168 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2171 if ((len = PAGE_ALIGN(len)) == 0)
2174 /* Find the first overlapping VMA */
2175 vma = find_vma_prev(mm, start, &prev);
2178 /* we have start < vma->vm_end */
2180 /* if it doesn't overlap, we have nothing.. */
2182 if (vma->vm_start >= end)
2186 * If we need to split any vma, do it now to save pain later.
2188 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2189 * unmapped vm_area_struct will remain in use: so lower split_vma
2190 * places tmp vma above, and higher split_vma places tmp vma below.
2192 if (start > vma->vm_start) {
2196 * Make sure that map_count on return from munmap() will
2197 * not exceed its limit; but let map_count go just above
2198 * its limit temporarily, to help free resources as expected.
2200 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2203 error = __split_vma(mm, vma, start, 0);
2209 /* Does it split the last one? */
2210 last = find_vma(mm, end);
2211 if (last && end > last->vm_start) {
2212 int error = __split_vma(mm, last, end, 1);
2216 vma = prev? prev->vm_next: mm->mmap;
2219 * unlock any mlock()ed ranges before detaching vmas
2221 if (mm->locked_vm) {
2222 struct vm_area_struct *tmp = vma;
2223 while (tmp && tmp->vm_start < end) {
2224 if (tmp->vm_flags & VM_LOCKED) {
2225 mm->locked_vm -= vma_pages(tmp);
2226 munlock_vma_pages_all(tmp);
2233 * Remove the vma's, and unmap the actual pages
2235 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2236 unmap_region(mm, vma, prev, start, end);
2238 /* Fix up all other VM information */
2239 remove_vma_list(mm, vma);
2244 EXPORT_SYMBOL(do_munmap);
2246 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2249 struct mm_struct *mm = current->mm;
2251 profile_munmap(addr);
2253 down_write(&mm->mmap_sem);
2254 ret = do_munmap(mm, addr, len);
2255 up_write(&mm->mmap_sem);
2259 static inline void verify_mm_writelocked(struct mm_struct *mm)
2261 #ifdef CONFIG_DEBUG_VM
2262 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2264 up_read(&mm->mmap_sem);
2270 * this is really a simplified "do_mmap". it only handles
2271 * anonymous maps. eventually we may be able to do some
2272 * brk-specific accounting here.
2274 unsigned long do_brk(unsigned long addr, unsigned long len)
2276 struct mm_struct * mm = current->mm;
2277 struct vm_area_struct * vma, * prev;
2278 unsigned long flags;
2279 struct rb_node ** rb_link, * rb_parent;
2280 pgoff_t pgoff = addr >> PAGE_SHIFT;
2283 len = PAGE_ALIGN(len);
2287 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2291 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2293 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2294 if (error & ~PAGE_MASK)
2300 if (mm->def_flags & VM_LOCKED) {
2301 unsigned long locked, lock_limit;
2302 locked = len >> PAGE_SHIFT;
2303 locked += mm->locked_vm;
2304 lock_limit = rlimit(RLIMIT_MEMLOCK);
2305 lock_limit >>= PAGE_SHIFT;
2306 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2311 * mm->mmap_sem is required to protect against another thread
2312 * changing the mappings in case we sleep.
2314 verify_mm_writelocked(mm);
2317 * Clear old maps. this also does some error checking for us
2320 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2321 if (vma && vma->vm_start < addr + len) {
2322 if (do_munmap(mm, addr, len))
2327 /* Check against address space limits *after* clearing old maps... */
2328 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2331 if (mm->map_count > sysctl_max_map_count)
2334 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2337 /* Can we just expand an old private anonymous mapping? */
2338 vma = vma_merge(mm, prev, addr, addr + len, flags,
2339 NULL, NULL, pgoff, NULL);
2344 * create a vma struct for an anonymous mapping
2346 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2348 vm_unacct_memory(len >> PAGE_SHIFT);
2352 INIT_LIST_HEAD(&vma->anon_vma_chain);
2354 vma->vm_start = addr;
2355 vma->vm_end = addr + len;
2356 vma->vm_pgoff = pgoff;
2357 vma->vm_flags = flags;
2358 vma->vm_page_prot = vm_get_page_prot(flags);
2359 vma_link(mm, vma, prev, rb_link, rb_parent);
2361 perf_event_mmap(vma);
2362 mm->total_vm += len >> PAGE_SHIFT;
2363 if (flags & VM_LOCKED) {
2364 if (!mlock_vma_pages_range(vma, addr, addr + len))
2365 mm->locked_vm += (len >> PAGE_SHIFT);
2370 EXPORT_SYMBOL(do_brk);
2372 /* Release all mmaps. */
2373 void exit_mmap(struct mm_struct *mm)
2375 struct mmu_gather *tlb;
2376 struct vm_area_struct *vma;
2377 unsigned long nr_accounted = 0;
2380 /* mm's last user has gone, and its about to be pulled down */
2381 mmu_notifier_release(mm);
2383 if (mm->locked_vm) {
2386 if (vma->vm_flags & VM_LOCKED)
2387 munlock_vma_pages_all(vma);
2395 if (!vma) /* Can happen if dup_mmap() received an OOM */
2400 tlb = tlb_gather_mmu(mm, 1);
2401 /* update_hiwater_rss(mm) here? but nobody should be looking */
2402 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2403 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2404 vm_unacct_memory(nr_accounted);
2406 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2407 tlb_finish_mmu(tlb, 0, end);
2408 arch_flush_exec_range(mm);
2411 * Walk the list again, actually closing and freeing it,
2412 * with preemption enabled, without holding any MM locks.
2415 vma = remove_vma(vma);
2417 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2420 /* Insert vm structure into process list sorted by address
2421 * and into the inode's i_mmap tree. If vm_file is non-NULL
2422 * then i_mmap_lock is taken here.
2424 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2426 struct vm_area_struct * __vma, * prev;
2427 struct rb_node ** rb_link, * rb_parent;
2430 * The vm_pgoff of a purely anonymous vma should be irrelevant
2431 * until its first write fault, when page's anon_vma and index
2432 * are set. But now set the vm_pgoff it will almost certainly
2433 * end up with (unless mremap moves it elsewhere before that
2434 * first wfault), so /proc/pid/maps tells a consistent story.
2436 * By setting it to reflect the virtual start address of the
2437 * vma, merges and splits can happen in a seamless way, just
2438 * using the existing file pgoff checks and manipulations.
2439 * Similarly in do_mmap_pgoff and in do_brk.
2441 if (!vma->vm_file) {
2442 BUG_ON(vma->anon_vma);
2443 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2445 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2446 if (__vma && __vma->vm_start < vma->vm_end)
2448 if ((vma->vm_flags & VM_ACCOUNT) &&
2449 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2451 vma_link(mm, vma, prev, rb_link, rb_parent);
2456 * Copy the vma structure to a new location in the same mm,
2457 * prior to moving page table entries, to effect an mremap move.
2459 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2460 unsigned long addr, unsigned long len, pgoff_t pgoff)
2462 struct vm_area_struct *vma = *vmap;
2463 unsigned long vma_start = vma->vm_start;
2464 struct mm_struct *mm = vma->vm_mm;
2465 struct vm_area_struct *new_vma, *prev;
2466 struct rb_node **rb_link, *rb_parent;
2467 struct mempolicy *pol;
2470 * If anonymous vma has not yet been faulted, update new pgoff
2471 * to match new location, to increase its chance of merging.
2473 if (!vma->vm_file && !vma->anon_vma)
2474 pgoff = addr >> PAGE_SHIFT;
2476 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2477 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2478 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2481 * Source vma may have been merged into new_vma
2483 if (vma_start >= new_vma->vm_start &&
2484 vma_start < new_vma->vm_end)
2487 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2490 pol = mpol_dup(vma_policy(vma));
2493 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2494 if (anon_vma_clone(new_vma, vma))
2495 goto out_free_mempol;
2496 vma_set_policy(new_vma, pol);
2497 new_vma->vm_start = addr;
2498 new_vma->vm_end = addr + len;
2499 new_vma->vm_pgoff = pgoff;
2500 if (new_vma->vm_file) {
2501 get_file(new_vma->vm_file);
2502 if (vma->vm_flags & VM_EXECUTABLE)
2503 added_exe_file_vma(mm);
2505 if (new_vma->vm_ops && new_vma->vm_ops->open)
2506 new_vma->vm_ops->open(new_vma);
2507 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2515 kmem_cache_free(vm_area_cachep, new_vma);
2520 * Return true if the calling process may expand its vm space by the passed
2523 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2525 unsigned long cur = mm->total_vm; /* pages */
2528 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2530 if (cur + npages > lim)
2536 static int special_mapping_fault(struct vm_area_struct *vma,
2537 struct vm_fault *vmf)
2540 struct page **pages;
2543 * special mappings have no vm_file, and in that case, the mm
2544 * uses vm_pgoff internally. So we have to subtract it from here.
2545 * We are allowed to do this because we are the mm; do not copy
2546 * this code into drivers!
2548 pgoff = vmf->pgoff - vma->vm_pgoff;
2550 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2554 struct page *page = *pages;
2560 return VM_FAULT_SIGBUS;
2564 * Having a close hook prevents vma merging regardless of flags.
2566 static void special_mapping_close(struct vm_area_struct *vma)
2570 static const struct vm_operations_struct special_mapping_vmops = {
2571 .close = special_mapping_close,
2572 .fault = special_mapping_fault,
2576 * Called with mm->mmap_sem held for writing.
2577 * Insert a new vma covering the given region, with the given flags.
2578 * Its pages are supplied by the given array of struct page *.
2579 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2580 * The region past the last page supplied will always produce SIGBUS.
2581 * The array pointer and the pages it points to are assumed to stay alive
2582 * for as long as this mapping might exist.
2584 int install_special_mapping(struct mm_struct *mm,
2585 unsigned long addr, unsigned long len,
2586 unsigned long vm_flags, struct page **pages)
2589 struct vm_area_struct *vma;
2591 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2592 if (unlikely(vma == NULL))
2595 INIT_LIST_HEAD(&vma->anon_vma_chain);
2597 vma->vm_start = addr;
2598 vma->vm_end = addr + len;
2600 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2601 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2603 vma->vm_ops = &special_mapping_vmops;
2604 vma->vm_private_data = pages;
2606 ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2610 ret = insert_vm_struct(mm, vma);
2614 mm->total_vm += len >> PAGE_SHIFT;
2616 perf_event_mmap(vma);
2621 kmem_cache_free(vm_area_cachep, vma);
2625 static DEFINE_MUTEX(mm_all_locks_mutex);
2627 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2629 if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2631 * The LSB of head.next can't change from under us
2632 * because we hold the mm_all_locks_mutex.
2634 spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
2636 * We can safely modify head.next after taking the
2637 * anon_vma->root->lock. If some other vma in this mm shares
2638 * the same anon_vma we won't take it again.
2640 * No need of atomic instructions here, head.next
2641 * can't change from under us thanks to the
2642 * anon_vma->root->lock.
2644 if (__test_and_set_bit(0, (unsigned long *)
2645 &anon_vma->root->head.next))
2650 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2652 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2654 * AS_MM_ALL_LOCKS can't change from under us because
2655 * we hold the mm_all_locks_mutex.
2657 * Operations on ->flags have to be atomic because
2658 * even if AS_MM_ALL_LOCKS is stable thanks to the
2659 * mm_all_locks_mutex, there may be other cpus
2660 * changing other bitflags in parallel to us.
2662 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2664 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2669 * This operation locks against the VM for all pte/vma/mm related
2670 * operations that could ever happen on a certain mm. This includes
2671 * vmtruncate, try_to_unmap, and all page faults.
2673 * The caller must take the mmap_sem in write mode before calling
2674 * mm_take_all_locks(). The caller isn't allowed to release the
2675 * mmap_sem until mm_drop_all_locks() returns.
2677 * mmap_sem in write mode is required in order to block all operations
2678 * that could modify pagetables and free pages without need of
2679 * altering the vma layout (for example populate_range() with
2680 * nonlinear vmas). It's also needed in write mode to avoid new
2681 * anon_vmas to be associated with existing vmas.
2683 * A single task can't take more than one mm_take_all_locks() in a row
2684 * or it would deadlock.
2686 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2687 * mapping->flags avoid to take the same lock twice, if more than one
2688 * vma in this mm is backed by the same anon_vma or address_space.
2690 * We can take all the locks in random order because the VM code
2691 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2692 * takes more than one of them in a row. Secondly we're protected
2693 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2695 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2696 * that may have to take thousand of locks.
2698 * mm_take_all_locks() can fail if it's interrupted by signals.
2700 int mm_take_all_locks(struct mm_struct *mm)
2702 struct vm_area_struct *vma;
2703 struct anon_vma_chain *avc;
2706 BUG_ON(down_read_trylock(&mm->mmap_sem));
2708 mutex_lock(&mm_all_locks_mutex);
2710 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2711 if (signal_pending(current))
2713 if (vma->vm_file && vma->vm_file->f_mapping)
2714 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2717 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2718 if (signal_pending(current))
2721 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2722 vm_lock_anon_vma(mm, avc->anon_vma);
2729 mm_drop_all_locks(mm);
2734 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2736 if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2738 * The LSB of head.next can't change to 0 from under
2739 * us because we hold the mm_all_locks_mutex.
2741 * We must however clear the bitflag before unlocking
2742 * the vma so the users using the anon_vma->head will
2743 * never see our bitflag.
2745 * No need of atomic instructions here, head.next
2746 * can't change from under us until we release the
2747 * anon_vma->root->lock.
2749 if (!__test_and_clear_bit(0, (unsigned long *)
2750 &anon_vma->root->head.next))
2752 anon_vma_unlock(anon_vma);
2756 static void vm_unlock_mapping(struct address_space *mapping)
2758 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2760 * AS_MM_ALL_LOCKS can't change to 0 from under us
2761 * because we hold the mm_all_locks_mutex.
2763 spin_unlock(&mapping->i_mmap_lock);
2764 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2771 * The mmap_sem cannot be released by the caller until
2772 * mm_drop_all_locks() returns.
2774 void mm_drop_all_locks(struct mm_struct *mm)
2776 struct vm_area_struct *vma;
2777 struct anon_vma_chain *avc;
2779 BUG_ON(down_read_trylock(&mm->mmap_sem));
2780 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2782 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2784 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2785 vm_unlock_anon_vma(avc->anon_vma);
2786 if (vma->vm_file && vma->vm_file->f_mapping)
2787 vm_unlock_mapping(vma->vm_file->f_mapping);
2790 mutex_unlock(&mm_all_locks_mutex);
2794 * initialise the VMA slab
2796 void __init mmap_init(void)
2800 ret = percpu_counter_init(&vm_committed_as, 0);