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/export.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/uprobes.h>
34 #include <linux/rbtree_augmented.h>
35 #include <linux/sched/sysctl.h>
37 #include <asm/uaccess.h>
38 #include <asm/cacheflush.h>
40 #include <asm/mmu_context.h>
44 #ifndef arch_mmap_check
45 #define arch_mmap_check(addr, len, flags) (0)
48 #ifndef arch_rebalance_pgtables
49 #define arch_rebalance_pgtables(addr, len) (addr)
52 static void unmap_region(struct mm_struct *mm,
53 struct vm_area_struct *vma, struct vm_area_struct *prev,
54 unsigned long start, unsigned long end);
56 /* description of effects of mapping type and prot in current implementation.
57 * this is due to the limited x86 page protection hardware. The expected
58 * behavior is in parens:
61 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
62 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
63 * w: (no) no w: (no) no w: (yes) yes w: (no) no
64 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
66 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
67 * w: (no) no w: (no) no w: (copy) copy w: (no) no
68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
71 pgprot_t protection_map[16] = {
72 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
73 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
76 pgprot_t vm_get_page_prot(unsigned long vm_flags)
78 return __pgprot(pgprot_val(protection_map[vm_flags &
79 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
80 pgprot_val(arch_vm_get_page_prot(vm_flags)));
82 EXPORT_SYMBOL(vm_get_page_prot);
84 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
85 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
86 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
88 * Make sure vm_committed_as in one cacheline and not cacheline shared with
89 * other variables. It can be updated by several CPUs frequently.
91 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
94 * The global memory commitment made in the system can be a metric
95 * that can be used to drive ballooning decisions when Linux is hosted
96 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
97 * balancing memory across competing virtual machines that are hosted.
98 * Several metrics drive this policy engine including the guest reported
101 unsigned long vm_memory_committed(void)
103 return percpu_counter_read_positive(&vm_committed_as);
105 EXPORT_SYMBOL_GPL(vm_memory_committed);
108 * Check that a process has enough memory to allocate a new virtual
109 * mapping. 0 means there is enough memory for the allocation to
110 * succeed and -ENOMEM implies there is not.
112 * We currently support three overcommit policies, which are set via the
113 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
115 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
116 * Additional code 2002 Jul 20 by Robert Love.
118 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
120 * Note this is a helper function intended to be used by LSMs which
121 * wish to use this logic.
123 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
125 unsigned long free, allowed;
127 vm_acct_memory(pages);
130 * Sometimes we want to use more memory than we have
132 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
135 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
136 free = global_page_state(NR_FREE_PAGES);
137 free += global_page_state(NR_FILE_PAGES);
140 * shmem pages shouldn't be counted as free in this
141 * case, they can't be purged, only swapped out, and
142 * that won't affect the overall amount of available
143 * memory in the system.
145 free -= global_page_state(NR_SHMEM);
147 free += get_nr_swap_pages();
150 * Any slabs which are created with the
151 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
152 * which are reclaimable, under pressure. The dentry
153 * cache and most inode caches should fall into this
155 free += global_page_state(NR_SLAB_RECLAIMABLE);
158 * Leave reserved pages. The pages are not for anonymous pages.
160 if (free <= totalreserve_pages)
163 free -= totalreserve_pages;
166 * Leave the last 3% for root
177 allowed = (totalram_pages - hugetlb_total_pages())
178 * sysctl_overcommit_ratio / 100;
180 * Leave the last 3% for root
183 allowed -= allowed / 32;
184 allowed += total_swap_pages;
186 /* Don't let a single process grow too big:
187 leave 3% of the size of this process for other processes */
189 allowed -= mm->total_vm / 32;
191 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
194 vm_unacct_memory(pages);
200 * Requires inode->i_mapping->i_mmap_mutex
202 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
203 struct file *file, struct address_space *mapping)
205 if (vma->vm_flags & VM_DENYWRITE)
206 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
207 if (vma->vm_flags & VM_SHARED)
208 mapping->i_mmap_writable--;
210 flush_dcache_mmap_lock(mapping);
211 if (unlikely(vma->vm_flags & VM_NONLINEAR))
212 list_del_init(&vma->shared.nonlinear);
214 vma_interval_tree_remove(vma, &mapping->i_mmap);
215 flush_dcache_mmap_unlock(mapping);
219 * Unlink a file-based vm structure from its interval tree, to hide
220 * vma from rmap and vmtruncate before freeing its page tables.
222 void unlink_file_vma(struct vm_area_struct *vma)
224 struct file *file = vma->vm_file;
227 struct address_space *mapping = file->f_mapping;
228 mutex_lock(&mapping->i_mmap_mutex);
229 __remove_shared_vm_struct(vma, file, mapping);
230 mutex_unlock(&mapping->i_mmap_mutex);
235 * Close a vm structure and free it, returning the next.
237 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
239 struct vm_area_struct *next = vma->vm_next;
242 if (vma->vm_ops && vma->vm_ops->close)
243 vma->vm_ops->close(vma);
246 mpol_put(vma_policy(vma));
247 kmem_cache_free(vm_area_cachep, vma);
251 static unsigned long do_brk(unsigned long addr, unsigned long len);
253 SYSCALL_DEFINE1(brk, unsigned long, brk)
255 unsigned long rlim, retval;
256 unsigned long newbrk, oldbrk;
257 struct mm_struct *mm = current->mm;
258 unsigned long min_brk;
261 down_write(&mm->mmap_sem);
263 #ifdef CONFIG_COMPAT_BRK
265 * CONFIG_COMPAT_BRK can still be overridden by setting
266 * randomize_va_space to 2, which will still cause mm->start_brk
267 * to be arbitrarily shifted
269 if (current->brk_randomized)
270 min_brk = mm->start_brk;
272 min_brk = mm->end_data;
274 min_brk = mm->start_brk;
280 * Check against rlimit here. If this check is done later after the test
281 * of oldbrk with newbrk then it can escape the test and let the data
282 * segment grow beyond its set limit the in case where the limit is
283 * not page aligned -Ram Gupta
285 rlim = rlimit(RLIMIT_DATA);
286 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
287 (mm->end_data - mm->start_data) > rlim)
290 newbrk = PAGE_ALIGN(brk);
291 oldbrk = PAGE_ALIGN(mm->brk);
292 if (oldbrk == newbrk)
295 /* Always allow shrinking brk. */
296 if (brk <= mm->brk) {
297 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
302 /* Check against existing mmap mappings. */
303 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
306 /* Ok, looks good - let it rip. */
307 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
312 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
313 up_write(&mm->mmap_sem);
315 mm_populate(oldbrk, newbrk - oldbrk);
320 up_write(&mm->mmap_sem);
324 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
326 unsigned long max, subtree_gap;
329 max -= vma->vm_prev->vm_end;
330 if (vma->vm_rb.rb_left) {
331 subtree_gap = rb_entry(vma->vm_rb.rb_left,
332 struct vm_area_struct, vm_rb)->rb_subtree_gap;
333 if (subtree_gap > max)
336 if (vma->vm_rb.rb_right) {
337 subtree_gap = rb_entry(vma->vm_rb.rb_right,
338 struct vm_area_struct, vm_rb)->rb_subtree_gap;
339 if (subtree_gap > max)
345 #ifdef CONFIG_DEBUG_VM_RB
346 static int browse_rb(struct rb_root *root)
348 int i = 0, j, bug = 0;
349 struct rb_node *nd, *pn = NULL;
350 unsigned long prev = 0, pend = 0;
352 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
353 struct vm_area_struct *vma;
354 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
355 if (vma->vm_start < prev) {
356 printk("vm_start %lx prev %lx\n", vma->vm_start, prev);
359 if (vma->vm_start < pend) {
360 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
363 if (vma->vm_start > vma->vm_end) {
364 printk("vm_end %lx < vm_start %lx\n",
365 vma->vm_end, vma->vm_start);
368 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
369 printk("free gap %lx, correct %lx\n",
371 vma_compute_subtree_gap(vma));
376 prev = vma->vm_start;
380 for (nd = pn; nd; nd = rb_prev(nd))
383 printk("backwards %d, forwards %d\n", j, i);
389 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
393 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
394 struct vm_area_struct *vma;
395 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
396 BUG_ON(vma != ignore &&
397 vma->rb_subtree_gap != vma_compute_subtree_gap(vma));
401 void validate_mm(struct mm_struct *mm)
405 unsigned long highest_address = 0;
406 struct vm_area_struct *vma = mm->mmap;
408 struct anon_vma_chain *avc;
409 vma_lock_anon_vma(vma);
410 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
411 anon_vma_interval_tree_verify(avc);
412 vma_unlock_anon_vma(vma);
413 highest_address = vma->vm_end;
417 if (i != mm->map_count) {
418 printk("map_count %d vm_next %d\n", mm->map_count, i);
421 if (highest_address != mm->highest_vm_end) {
422 printk("mm->highest_vm_end %lx, found %lx\n",
423 mm->highest_vm_end, highest_address);
426 i = browse_rb(&mm->mm_rb);
427 if (i != mm->map_count) {
428 printk("map_count %d rb %d\n", mm->map_count, i);
434 #define validate_mm_rb(root, ignore) do { } while (0)
435 #define validate_mm(mm) do { } while (0)
438 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
439 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
442 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
443 * vma->vm_prev->vm_end values changed, without modifying the vma's position
446 static void vma_gap_update(struct vm_area_struct *vma)
449 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
450 * function that does exacltly what we want.
452 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
455 static inline void vma_rb_insert(struct vm_area_struct *vma,
456 struct rb_root *root)
458 /* All rb_subtree_gap values must be consistent prior to insertion */
459 validate_mm_rb(root, NULL);
461 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
464 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
467 * All rb_subtree_gap values must be consistent prior to erase,
468 * with the possible exception of the vma being erased.
470 validate_mm_rb(root, vma);
473 * Note rb_erase_augmented is a fairly large inline function,
474 * so make sure we instantiate it only once with our desired
475 * augmented rbtree callbacks.
477 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
481 * vma has some anon_vma assigned, and is already inserted on that
482 * anon_vma's interval trees.
484 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
485 * vma must be removed from the anon_vma's interval trees using
486 * anon_vma_interval_tree_pre_update_vma().
488 * After the update, the vma will be reinserted using
489 * anon_vma_interval_tree_post_update_vma().
491 * The entire update must be protected by exclusive mmap_sem and by
492 * the root anon_vma's mutex.
495 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
497 struct anon_vma_chain *avc;
499 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
500 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
504 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
506 struct anon_vma_chain *avc;
508 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
509 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
512 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
513 unsigned long end, struct vm_area_struct **pprev,
514 struct rb_node ***rb_link, struct rb_node **rb_parent)
516 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
518 __rb_link = &mm->mm_rb.rb_node;
519 rb_prev = __rb_parent = NULL;
522 struct vm_area_struct *vma_tmp;
524 __rb_parent = *__rb_link;
525 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
527 if (vma_tmp->vm_end > addr) {
528 /* Fail if an existing vma overlaps the area */
529 if (vma_tmp->vm_start < end)
531 __rb_link = &__rb_parent->rb_left;
533 rb_prev = __rb_parent;
534 __rb_link = &__rb_parent->rb_right;
540 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
541 *rb_link = __rb_link;
542 *rb_parent = __rb_parent;
546 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
547 struct rb_node **rb_link, struct rb_node *rb_parent)
549 /* Update tracking information for the gap following the new vma. */
551 vma_gap_update(vma->vm_next);
553 mm->highest_vm_end = vma->vm_end;
556 * vma->vm_prev wasn't known when we followed the rbtree to find the
557 * correct insertion point for that vma. As a result, we could not
558 * update the vma vm_rb parents rb_subtree_gap values on the way down.
559 * So, we first insert the vma with a zero rb_subtree_gap value
560 * (to be consistent with what we did on the way down), and then
561 * immediately update the gap to the correct value. Finally we
562 * rebalance the rbtree after all augmented values have been set.
564 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
565 vma->rb_subtree_gap = 0;
567 vma_rb_insert(vma, &mm->mm_rb);
570 static void __vma_link_file(struct vm_area_struct *vma)
576 struct address_space *mapping = file->f_mapping;
578 if (vma->vm_flags & VM_DENYWRITE)
579 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
580 if (vma->vm_flags & VM_SHARED)
581 mapping->i_mmap_writable++;
583 flush_dcache_mmap_lock(mapping);
584 if (unlikely(vma->vm_flags & VM_NONLINEAR))
585 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
587 vma_interval_tree_insert(vma, &mapping->i_mmap);
588 flush_dcache_mmap_unlock(mapping);
593 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
594 struct vm_area_struct *prev, struct rb_node **rb_link,
595 struct rb_node *rb_parent)
597 __vma_link_list(mm, vma, prev, rb_parent);
598 __vma_link_rb(mm, vma, rb_link, rb_parent);
601 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
602 struct vm_area_struct *prev, struct rb_node **rb_link,
603 struct rb_node *rb_parent)
605 struct address_space *mapping = NULL;
608 mapping = vma->vm_file->f_mapping;
611 mutex_lock(&mapping->i_mmap_mutex);
613 __vma_link(mm, vma, prev, rb_link, rb_parent);
614 __vma_link_file(vma);
617 mutex_unlock(&mapping->i_mmap_mutex);
624 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
625 * mm's list and rbtree. It has already been inserted into the interval tree.
627 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
629 struct vm_area_struct *prev;
630 struct rb_node **rb_link, *rb_parent;
632 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
633 &prev, &rb_link, &rb_parent))
635 __vma_link(mm, vma, prev, rb_link, rb_parent);
640 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
641 struct vm_area_struct *prev)
643 struct vm_area_struct *next;
645 vma_rb_erase(vma, &mm->mm_rb);
646 prev->vm_next = next = vma->vm_next;
648 next->vm_prev = prev;
649 if (mm->mmap_cache == vma)
650 mm->mmap_cache = prev;
654 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
655 * is already present in an i_mmap tree without adjusting the tree.
656 * The following helper function should be used when such adjustments
657 * are necessary. The "insert" vma (if any) is to be inserted
658 * before we drop the necessary locks.
660 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
661 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
663 struct mm_struct *mm = vma->vm_mm;
664 struct vm_area_struct *next = vma->vm_next;
665 struct vm_area_struct *importer = NULL;
666 struct address_space *mapping = NULL;
667 struct rb_root *root = NULL;
668 struct anon_vma *anon_vma = NULL;
669 struct file *file = vma->vm_file;
670 bool start_changed = false, end_changed = false;
671 long adjust_next = 0;
674 if (next && !insert) {
675 struct vm_area_struct *exporter = NULL;
677 if (end >= next->vm_end) {
679 * vma expands, overlapping all the next, and
680 * perhaps the one after too (mprotect case 6).
682 again: remove_next = 1 + (end > next->vm_end);
686 } else if (end > next->vm_start) {
688 * vma expands, overlapping part of the next:
689 * mprotect case 5 shifting the boundary up.
691 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
694 } else if (end < vma->vm_end) {
696 * vma shrinks, and !insert tells it's not
697 * split_vma inserting another: so it must be
698 * mprotect case 4 shifting the boundary down.
700 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
706 * Easily overlooked: when mprotect shifts the boundary,
707 * make sure the expanding vma has anon_vma set if the
708 * shrinking vma had, to cover any anon pages imported.
710 if (exporter && exporter->anon_vma && !importer->anon_vma) {
711 if (anon_vma_clone(importer, exporter))
713 importer->anon_vma = exporter->anon_vma;
718 mapping = file->f_mapping;
719 if (!(vma->vm_flags & VM_NONLINEAR)) {
720 root = &mapping->i_mmap;
721 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
724 uprobe_munmap(next, next->vm_start,
728 mutex_lock(&mapping->i_mmap_mutex);
731 * Put into interval tree now, so instantiated pages
732 * are visible to arm/parisc __flush_dcache_page
733 * throughout; but we cannot insert into address
734 * space until vma start or end is updated.
736 __vma_link_file(insert);
740 vma_adjust_trans_huge(vma, start, end, adjust_next);
742 anon_vma = vma->anon_vma;
743 if (!anon_vma && adjust_next)
744 anon_vma = next->anon_vma;
746 VM_BUG_ON(adjust_next && next->anon_vma &&
747 anon_vma != next->anon_vma);
748 anon_vma_lock_write(anon_vma);
749 anon_vma_interval_tree_pre_update_vma(vma);
751 anon_vma_interval_tree_pre_update_vma(next);
755 flush_dcache_mmap_lock(mapping);
756 vma_interval_tree_remove(vma, root);
758 vma_interval_tree_remove(next, root);
761 if (start != vma->vm_start) {
762 vma->vm_start = start;
763 start_changed = true;
765 if (end != vma->vm_end) {
769 vma->vm_pgoff = pgoff;
771 next->vm_start += adjust_next << PAGE_SHIFT;
772 next->vm_pgoff += adjust_next;
777 vma_interval_tree_insert(next, root);
778 vma_interval_tree_insert(vma, root);
779 flush_dcache_mmap_unlock(mapping);
784 * vma_merge has merged next into vma, and needs
785 * us to remove next before dropping the locks.
787 __vma_unlink(mm, next, vma);
789 __remove_shared_vm_struct(next, file, mapping);
792 * split_vma has split insert from vma, and needs
793 * us to insert it before dropping the locks
794 * (it may either follow vma or precede it).
796 __insert_vm_struct(mm, insert);
802 mm->highest_vm_end = end;
803 else if (!adjust_next)
804 vma_gap_update(next);
809 anon_vma_interval_tree_post_update_vma(vma);
811 anon_vma_interval_tree_post_update_vma(next);
812 anon_vma_unlock_write(anon_vma);
815 mutex_unlock(&mapping->i_mmap_mutex);
826 uprobe_munmap(next, next->vm_start, next->vm_end);
830 anon_vma_merge(vma, next);
832 mpol_put(vma_policy(next));
833 kmem_cache_free(vm_area_cachep, next);
835 * In mprotect's case 6 (see comments on vma_merge),
836 * we must remove another next too. It would clutter
837 * up the code too much to do both in one go.
840 if (remove_next == 2)
843 vma_gap_update(next);
845 mm->highest_vm_end = end;
856 * If the vma has a ->close operation then the driver probably needs to release
857 * per-vma resources, so we don't attempt to merge those.
859 static inline int is_mergeable_vma(struct vm_area_struct *vma,
860 struct file *file, unsigned long vm_flags)
862 if (vma->vm_flags ^ vm_flags)
864 if (vma->vm_file != file)
866 if (vma->vm_ops && vma->vm_ops->close)
871 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
872 struct anon_vma *anon_vma2,
873 struct vm_area_struct *vma)
876 * The list_is_singular() test is to avoid merging VMA cloned from
877 * parents. This can improve scalability caused by anon_vma lock.
879 if ((!anon_vma1 || !anon_vma2) && (!vma ||
880 list_is_singular(&vma->anon_vma_chain)))
882 return anon_vma1 == anon_vma2;
886 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
887 * in front of (at a lower virtual address and file offset than) the vma.
889 * We cannot merge two vmas if they have differently assigned (non-NULL)
890 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
892 * We don't check here for the merged mmap wrapping around the end of pagecache
893 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
894 * wrap, nor mmaps which cover the final page at index -1UL.
897 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
898 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
900 if (is_mergeable_vma(vma, file, vm_flags) &&
901 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
902 if (vma->vm_pgoff == vm_pgoff)
909 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
910 * beyond (at a higher virtual address and file offset than) the vma.
912 * We cannot merge two vmas if they have differently assigned (non-NULL)
913 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
916 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
917 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
919 if (is_mergeable_vma(vma, file, vm_flags) &&
920 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
922 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
923 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
930 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
931 * whether that can be merged with its predecessor or its successor.
932 * Or both (it neatly fills a hole).
934 * In most cases - when called for mmap, brk or mremap - [addr,end) is
935 * certain not to be mapped by the time vma_merge is called; but when
936 * called for mprotect, it is certain to be already mapped (either at
937 * an offset within prev, or at the start of next), and the flags of
938 * this area are about to be changed to vm_flags - and the no-change
939 * case has already been eliminated.
941 * The following mprotect cases have to be considered, where AAAA is
942 * the area passed down from mprotect_fixup, never extending beyond one
943 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
945 * AAAA AAAA AAAA AAAA
946 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
947 * cannot merge might become might become might become
948 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
949 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
950 * mremap move: PPPPNNNNNNNN 8
952 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
953 * might become case 1 below case 2 below case 3 below
955 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
956 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
958 struct vm_area_struct *vma_merge(struct mm_struct *mm,
959 struct vm_area_struct *prev, unsigned long addr,
960 unsigned long end, unsigned long vm_flags,
961 struct anon_vma *anon_vma, struct file *file,
962 pgoff_t pgoff, struct mempolicy *policy)
964 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
965 struct vm_area_struct *area, *next;
969 * We later require that vma->vm_flags == vm_flags,
970 * so this tests vma->vm_flags & VM_SPECIAL, too.
972 if (vm_flags & VM_SPECIAL)
976 next = prev->vm_next;
980 if (next && next->vm_end == end) /* cases 6, 7, 8 */
981 next = next->vm_next;
984 * Can it merge with the predecessor?
986 if (prev && prev->vm_end == addr &&
987 mpol_equal(vma_policy(prev), policy) &&
988 can_vma_merge_after(prev, vm_flags,
989 anon_vma, file, pgoff)) {
991 * OK, it can. Can we now merge in the successor as well?
993 if (next && end == next->vm_start &&
994 mpol_equal(policy, vma_policy(next)) &&
995 can_vma_merge_before(next, vm_flags,
996 anon_vma, file, pgoff+pglen) &&
997 is_mergeable_anon_vma(prev->anon_vma,
998 next->anon_vma, NULL)) {
1000 err = vma_adjust(prev, prev->vm_start,
1001 next->vm_end, prev->vm_pgoff, NULL);
1002 } else /* cases 2, 5, 7 */
1003 err = vma_adjust(prev, prev->vm_start,
1004 end, prev->vm_pgoff, NULL);
1007 khugepaged_enter_vma_merge(prev);
1012 * Can this new request be merged in front of next?
1014 if (next && end == next->vm_start &&
1015 mpol_equal(policy, vma_policy(next)) &&
1016 can_vma_merge_before(next, vm_flags,
1017 anon_vma, file, pgoff+pglen)) {
1018 if (prev && addr < prev->vm_end) /* case 4 */
1019 err = vma_adjust(prev, prev->vm_start,
1020 addr, prev->vm_pgoff, NULL);
1021 else /* cases 3, 8 */
1022 err = vma_adjust(area, addr, next->vm_end,
1023 next->vm_pgoff - pglen, NULL);
1026 khugepaged_enter_vma_merge(area);
1034 * Rough compatbility check to quickly see if it's even worth looking
1035 * at sharing an anon_vma.
1037 * They need to have the same vm_file, and the flags can only differ
1038 * in things that mprotect may change.
1040 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1041 * we can merge the two vma's. For example, we refuse to merge a vma if
1042 * there is a vm_ops->close() function, because that indicates that the
1043 * driver is doing some kind of reference counting. But that doesn't
1044 * really matter for the anon_vma sharing case.
1046 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1048 return a->vm_end == b->vm_start &&
1049 mpol_equal(vma_policy(a), vma_policy(b)) &&
1050 a->vm_file == b->vm_file &&
1051 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
1052 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1056 * Do some basic sanity checking to see if we can re-use the anon_vma
1057 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1058 * the same as 'old', the other will be the new one that is trying
1059 * to share the anon_vma.
1061 * NOTE! This runs with mm_sem held for reading, so it is possible that
1062 * the anon_vma of 'old' is concurrently in the process of being set up
1063 * by another page fault trying to merge _that_. But that's ok: if it
1064 * is being set up, that automatically means that it will be a singleton
1065 * acceptable for merging, so we can do all of this optimistically. But
1066 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
1068 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1069 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1070 * is to return an anon_vma that is "complex" due to having gone through
1073 * We also make sure that the two vma's are compatible (adjacent,
1074 * and with the same memory policies). That's all stable, even with just
1075 * a read lock on the mm_sem.
1077 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1079 if (anon_vma_compatible(a, b)) {
1080 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
1082 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1089 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1090 * neighbouring vmas for a suitable anon_vma, before it goes off
1091 * to allocate a new anon_vma. It checks because a repetitive
1092 * sequence of mprotects and faults may otherwise lead to distinct
1093 * anon_vmas being allocated, preventing vma merge in subsequent
1096 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1098 struct anon_vma *anon_vma;
1099 struct vm_area_struct *near;
1101 near = vma->vm_next;
1105 anon_vma = reusable_anon_vma(near, vma, near);
1109 near = vma->vm_prev;
1113 anon_vma = reusable_anon_vma(near, near, vma);
1118 * There's no absolute need to look only at touching neighbours:
1119 * we could search further afield for "compatible" anon_vmas.
1120 * But it would probably just be a waste of time searching,
1121 * or lead to too many vmas hanging off the same anon_vma.
1122 * We're trying to allow mprotect remerging later on,
1123 * not trying to minimize memory used for anon_vmas.
1128 #ifdef CONFIG_PROC_FS
1129 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1130 struct file *file, long pages)
1132 const unsigned long stack_flags
1133 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1135 mm->total_vm += pages;
1138 mm->shared_vm += pages;
1139 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1140 mm->exec_vm += pages;
1141 } else if (flags & stack_flags)
1142 mm->stack_vm += pages;
1144 #endif /* CONFIG_PROC_FS */
1147 * If a hint addr is less than mmap_min_addr change hint to be as
1148 * low as possible but still greater than mmap_min_addr
1150 static inline unsigned long round_hint_to_min(unsigned long hint)
1153 if (((void *)hint != NULL) &&
1154 (hint < mmap_min_addr))
1155 return PAGE_ALIGN(mmap_min_addr);
1160 * The caller must hold down_write(¤t->mm->mmap_sem).
1163 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1164 unsigned long len, unsigned long prot,
1165 unsigned long flags, unsigned long pgoff,
1166 unsigned long *populate)
1168 struct mm_struct * mm = current->mm;
1169 struct inode *inode;
1170 vm_flags_t vm_flags;
1175 * Does the application expect PROT_READ to imply PROT_EXEC?
1177 * (the exception is when the underlying filesystem is noexec
1178 * mounted, in which case we dont add PROT_EXEC.)
1180 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1181 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1187 if (!(flags & MAP_FIXED))
1188 addr = round_hint_to_min(addr);
1190 /* Careful about overflows.. */
1191 len = PAGE_ALIGN(len);
1195 /* offset overflow? */
1196 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1199 /* Too many mappings? */
1200 if (mm->map_count > sysctl_max_map_count)
1203 /* Obtain the address to map to. we verify (or select) it and ensure
1204 * that it represents a valid section of the address space.
1206 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1207 if (addr & ~PAGE_MASK)
1210 /* Do simple checking here so the lower-level routines won't have
1211 * to. we assume access permissions have been handled by the open
1212 * of the memory object, so we don't do any here.
1214 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1215 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1217 if (flags & MAP_LOCKED)
1218 if (!can_do_mlock())
1221 /* mlock MCL_FUTURE? */
1222 if (vm_flags & VM_LOCKED) {
1223 unsigned long locked, lock_limit;
1224 locked = len >> PAGE_SHIFT;
1225 locked += mm->locked_vm;
1226 lock_limit = rlimit(RLIMIT_MEMLOCK);
1227 lock_limit >>= PAGE_SHIFT;
1228 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1232 inode = file ? file->f_path.dentry->d_inode : NULL;
1235 switch (flags & MAP_TYPE) {
1237 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1241 * Make sure we don't allow writing to an append-only
1244 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1248 * Make sure there are no mandatory locks on the file.
1250 if (locks_verify_locked(inode))
1253 vm_flags |= VM_SHARED | VM_MAYSHARE;
1254 if (!(file->f_mode & FMODE_WRITE))
1255 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1259 if (!(file->f_mode & FMODE_READ))
1261 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1262 if (vm_flags & VM_EXEC)
1264 vm_flags &= ~VM_MAYEXEC;
1267 if (!file->f_op || !file->f_op->mmap)
1275 switch (flags & MAP_TYPE) {
1281 vm_flags |= VM_SHARED | VM_MAYSHARE;
1285 * Set pgoff according to addr for anon_vma.
1287 pgoff = addr >> PAGE_SHIFT;
1295 * Set 'VM_NORESERVE' if we should not account for the
1296 * memory use of this mapping.
1298 if (flags & MAP_NORESERVE) {
1299 /* We honor MAP_NORESERVE if allowed to overcommit */
1300 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1301 vm_flags |= VM_NORESERVE;
1303 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1304 if (file && is_file_hugepages(file))
1305 vm_flags |= VM_NORESERVE;
1308 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1309 if (!IS_ERR_VALUE(addr) && (vm_flags & VM_POPULATE))
1314 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1315 unsigned long, prot, unsigned long, flags,
1316 unsigned long, fd, unsigned long, pgoff)
1318 struct file *file = NULL;
1319 unsigned long retval = -EBADF;
1321 if (!(flags & MAP_ANONYMOUS)) {
1322 audit_mmap_fd(fd, flags);
1323 if (unlikely(flags & MAP_HUGETLB))
1328 } else if (flags & MAP_HUGETLB) {
1329 struct user_struct *user = NULL;
1331 * VM_NORESERVE is used because the reservations will be
1332 * taken when vm_ops->mmap() is called
1333 * A dummy user value is used because we are not locking
1334 * memory so no accounting is necessary
1336 file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
1338 &user, HUGETLB_ANONHUGE_INODE,
1339 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1341 return PTR_ERR(file);
1344 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1346 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1353 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1354 struct mmap_arg_struct {
1358 unsigned long flags;
1360 unsigned long offset;
1363 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1365 struct mmap_arg_struct a;
1367 if (copy_from_user(&a, arg, sizeof(a)))
1369 if (a.offset & ~PAGE_MASK)
1372 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1373 a.offset >> PAGE_SHIFT);
1375 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1378 * Some shared mappigns will want the pages marked read-only
1379 * to track write events. If so, we'll downgrade vm_page_prot
1380 * to the private version (using protection_map[] without the
1383 int vma_wants_writenotify(struct vm_area_struct *vma)
1385 vm_flags_t vm_flags = vma->vm_flags;
1387 /* If it was private or non-writable, the write bit is already clear */
1388 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1391 /* The backer wishes to know when pages are first written to? */
1392 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1395 /* The open routine did something to the protections already? */
1396 if (pgprot_val(vma->vm_page_prot) !=
1397 pgprot_val(vm_get_page_prot(vm_flags)))
1400 /* Specialty mapping? */
1401 if (vm_flags & VM_PFNMAP)
1404 /* Can the mapping track the dirty pages? */
1405 return vma->vm_file && vma->vm_file->f_mapping &&
1406 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1410 * We account for memory if it's a private writeable mapping,
1411 * not hugepages and VM_NORESERVE wasn't set.
1413 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1416 * hugetlb has its own accounting separate from the core VM
1417 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1419 if (file && is_file_hugepages(file))
1422 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1425 unsigned long mmap_region(struct file *file, unsigned long addr,
1426 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1428 struct mm_struct *mm = current->mm;
1429 struct vm_area_struct *vma, *prev;
1430 int correct_wcount = 0;
1432 struct rb_node **rb_link, *rb_parent;
1433 unsigned long charged = 0;
1434 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1436 /* Clear old maps */
1439 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
1440 if (do_munmap(mm, addr, len))
1445 /* Check against address space limit. */
1446 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1450 * Private writable mapping: check memory availability
1452 if (accountable_mapping(file, vm_flags)) {
1453 charged = len >> PAGE_SHIFT;
1454 if (security_vm_enough_memory_mm(mm, charged))
1456 vm_flags |= VM_ACCOUNT;
1460 * Can we just expand an old mapping?
1462 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1467 * Determine the object being mapped and call the appropriate
1468 * specific mapper. the address has already been validated, but
1469 * not unmapped, but the maps are removed from the list.
1471 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1478 vma->vm_start = addr;
1479 vma->vm_end = addr + len;
1480 vma->vm_flags = vm_flags;
1481 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1482 vma->vm_pgoff = pgoff;
1483 INIT_LIST_HEAD(&vma->anon_vma_chain);
1485 error = -EINVAL; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */
1488 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1490 if (vm_flags & VM_DENYWRITE) {
1491 error = deny_write_access(file);
1496 vma->vm_file = get_file(file);
1497 error = file->f_op->mmap(file, vma);
1499 goto unmap_and_free_vma;
1501 /* Can addr have changed??
1503 * Answer: Yes, several device drivers can do it in their
1504 * f_op->mmap method. -DaveM
1505 * Bug: If addr is changed, prev, rb_link, rb_parent should
1506 * be updated for vma_link()
1508 WARN_ON_ONCE(addr != vma->vm_start);
1510 addr = vma->vm_start;
1511 pgoff = vma->vm_pgoff;
1512 vm_flags = vma->vm_flags;
1513 } else if (vm_flags & VM_SHARED) {
1514 if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP)))
1516 error = shmem_zero_setup(vma);
1521 if (vma_wants_writenotify(vma)) {
1522 pgprot_t pprot = vma->vm_page_prot;
1524 /* Can vma->vm_page_prot have changed??
1526 * Answer: Yes, drivers may have changed it in their
1527 * f_op->mmap method.
1529 * Ensures that vmas marked as uncached stay that way.
1531 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1532 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1533 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1536 vma_link(mm, vma, prev, rb_link, rb_parent);
1537 file = vma->vm_file;
1539 /* Once vma denies write, undo our temporary denial count */
1541 atomic_inc(&inode->i_writecount);
1543 perf_event_mmap(vma);
1545 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1546 if (vm_flags & VM_LOCKED) {
1547 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1548 vma == get_gate_vma(current->mm)))
1549 mm->locked_vm += (len >> PAGE_SHIFT);
1551 vma->vm_flags &= ~VM_LOCKED;
1561 atomic_inc(&inode->i_writecount);
1562 vma->vm_file = NULL;
1565 /* Undo any partial mapping done by a device driver. */
1566 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1569 kmem_cache_free(vm_area_cachep, vma);
1572 vm_unacct_memory(charged);
1576 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1579 * We implement the search by looking for an rbtree node that
1580 * immediately follows a suitable gap. That is,
1581 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1582 * - gap_end = vma->vm_start >= info->low_limit + length;
1583 * - gap_end - gap_start >= length
1586 struct mm_struct *mm = current->mm;
1587 struct vm_area_struct *vma;
1588 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1590 /* Adjust search length to account for worst case alignment overhead */
1591 length = info->length + info->align_mask;
1592 if (length < info->length)
1595 /* Adjust search limits by the desired length */
1596 if (info->high_limit < length)
1598 high_limit = info->high_limit - length;
1600 if (info->low_limit > high_limit)
1602 low_limit = info->low_limit + length;
1604 /* Check if rbtree root looks promising */
1605 if (RB_EMPTY_ROOT(&mm->mm_rb))
1607 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1608 if (vma->rb_subtree_gap < length)
1612 /* Visit left subtree if it looks promising */
1613 gap_end = vma->vm_start;
1614 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1615 struct vm_area_struct *left =
1616 rb_entry(vma->vm_rb.rb_left,
1617 struct vm_area_struct, vm_rb);
1618 if (left->rb_subtree_gap >= length) {
1624 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1626 /* Check if current node has a suitable gap */
1627 if (gap_start > high_limit)
1629 if (gap_end >= low_limit && gap_end - gap_start >= length)
1632 /* Visit right subtree if it looks promising */
1633 if (vma->vm_rb.rb_right) {
1634 struct vm_area_struct *right =
1635 rb_entry(vma->vm_rb.rb_right,
1636 struct vm_area_struct, vm_rb);
1637 if (right->rb_subtree_gap >= length) {
1643 /* Go back up the rbtree to find next candidate node */
1645 struct rb_node *prev = &vma->vm_rb;
1646 if (!rb_parent(prev))
1648 vma = rb_entry(rb_parent(prev),
1649 struct vm_area_struct, vm_rb);
1650 if (prev == vma->vm_rb.rb_left) {
1651 gap_start = vma->vm_prev->vm_end;
1652 gap_end = vma->vm_start;
1659 /* Check highest gap, which does not precede any rbtree node */
1660 gap_start = mm->highest_vm_end;
1661 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1662 if (gap_start > high_limit)
1666 /* We found a suitable gap. Clip it with the original low_limit. */
1667 if (gap_start < info->low_limit)
1668 gap_start = info->low_limit;
1670 /* Adjust gap address to the desired alignment */
1671 gap_start += (info->align_offset - gap_start) & info->align_mask;
1673 VM_BUG_ON(gap_start + info->length > info->high_limit);
1674 VM_BUG_ON(gap_start + info->length > gap_end);
1678 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1680 struct mm_struct *mm = current->mm;
1681 struct vm_area_struct *vma;
1682 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1684 /* Adjust search length to account for worst case alignment overhead */
1685 length = info->length + info->align_mask;
1686 if (length < info->length)
1690 * Adjust search limits by the desired length.
1691 * See implementation comment at top of unmapped_area().
1693 gap_end = info->high_limit;
1694 if (gap_end < length)
1696 high_limit = gap_end - length;
1698 if (info->low_limit > high_limit)
1700 low_limit = info->low_limit + length;
1702 /* Check highest gap, which does not precede any rbtree node */
1703 gap_start = mm->highest_vm_end;
1704 if (gap_start <= high_limit)
1707 /* Check if rbtree root looks promising */
1708 if (RB_EMPTY_ROOT(&mm->mm_rb))
1710 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1711 if (vma->rb_subtree_gap < length)
1715 /* Visit right subtree if it looks promising */
1716 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1717 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1718 struct vm_area_struct *right =
1719 rb_entry(vma->vm_rb.rb_right,
1720 struct vm_area_struct, vm_rb);
1721 if (right->rb_subtree_gap >= length) {
1728 /* Check if current node has a suitable gap */
1729 gap_end = vma->vm_start;
1730 if (gap_end < low_limit)
1732 if (gap_start <= high_limit && gap_end - gap_start >= length)
1735 /* Visit left subtree if it looks promising */
1736 if (vma->vm_rb.rb_left) {
1737 struct vm_area_struct *left =
1738 rb_entry(vma->vm_rb.rb_left,
1739 struct vm_area_struct, vm_rb);
1740 if (left->rb_subtree_gap >= length) {
1746 /* Go back up the rbtree to find next candidate node */
1748 struct rb_node *prev = &vma->vm_rb;
1749 if (!rb_parent(prev))
1751 vma = rb_entry(rb_parent(prev),
1752 struct vm_area_struct, vm_rb);
1753 if (prev == vma->vm_rb.rb_right) {
1754 gap_start = vma->vm_prev ?
1755 vma->vm_prev->vm_end : 0;
1762 /* We found a suitable gap. Clip it with the original high_limit. */
1763 if (gap_end > info->high_limit)
1764 gap_end = info->high_limit;
1767 /* Compute highest gap address at the desired alignment */
1768 gap_end -= info->length;
1769 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1771 VM_BUG_ON(gap_end < info->low_limit);
1772 VM_BUG_ON(gap_end < gap_start);
1776 /* Get an address range which is currently unmapped.
1777 * For shmat() with addr=0.
1779 * Ugly calling convention alert:
1780 * Return value with the low bits set means error value,
1782 * if (ret & ~PAGE_MASK)
1785 * This function "knows" that -ENOMEM has the bits set.
1787 #ifndef HAVE_ARCH_UNMAPPED_AREA
1789 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1790 unsigned long len, unsigned long pgoff, unsigned long flags)
1792 struct mm_struct *mm = current->mm;
1793 struct vm_area_struct *vma;
1794 struct vm_unmapped_area_info info;
1796 if (len > TASK_SIZE)
1799 if (flags & MAP_FIXED)
1803 addr = PAGE_ALIGN(addr);
1804 vma = find_vma(mm, addr);
1805 if (TASK_SIZE - len >= addr &&
1806 (!vma || addr + len <= vma->vm_start))
1812 info.low_limit = TASK_UNMAPPED_BASE;
1813 info.high_limit = TASK_SIZE;
1814 info.align_mask = 0;
1815 return vm_unmapped_area(&info);
1819 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1822 * Is this a new hole at the lowest possible address?
1824 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache)
1825 mm->free_area_cache = addr;
1829 * This mmap-allocator allocates new areas top-down from below the
1830 * stack's low limit (the base):
1832 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1834 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1835 const unsigned long len, const unsigned long pgoff,
1836 const unsigned long flags)
1838 struct vm_area_struct *vma;
1839 struct mm_struct *mm = current->mm;
1840 unsigned long addr = addr0;
1841 struct vm_unmapped_area_info info;
1843 /* requested length too big for entire address space */
1844 if (len > TASK_SIZE)
1847 if (flags & MAP_FIXED)
1850 /* requesting a specific address */
1852 addr = PAGE_ALIGN(addr);
1853 vma = find_vma(mm, addr);
1854 if (TASK_SIZE - len >= addr &&
1855 (!vma || addr + len <= vma->vm_start))
1859 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1861 info.low_limit = PAGE_SIZE;
1862 info.high_limit = mm->mmap_base;
1863 info.align_mask = 0;
1864 addr = vm_unmapped_area(&info);
1867 * A failed mmap() very likely causes application failure,
1868 * so fall back to the bottom-up function here. This scenario
1869 * can happen with large stack limits and large mmap()
1872 if (addr & ~PAGE_MASK) {
1873 VM_BUG_ON(addr != -ENOMEM);
1875 info.low_limit = TASK_UNMAPPED_BASE;
1876 info.high_limit = TASK_SIZE;
1877 addr = vm_unmapped_area(&info);
1884 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1887 * Is this a new hole at the highest possible address?
1889 if (addr > mm->free_area_cache)
1890 mm->free_area_cache = addr;
1892 /* dont allow allocations above current base */
1893 if (mm->free_area_cache > mm->mmap_base)
1894 mm->free_area_cache = mm->mmap_base;
1898 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1899 unsigned long pgoff, unsigned long flags)
1901 unsigned long (*get_area)(struct file *, unsigned long,
1902 unsigned long, unsigned long, unsigned long);
1904 unsigned long error = arch_mmap_check(addr, len, flags);
1908 /* Careful about overflows.. */
1909 if (len > TASK_SIZE)
1912 get_area = current->mm->get_unmapped_area;
1913 if (file && file->f_op && file->f_op->get_unmapped_area)
1914 get_area = file->f_op->get_unmapped_area;
1915 addr = get_area(file, addr, len, pgoff, flags);
1916 if (IS_ERR_VALUE(addr))
1919 if (addr > TASK_SIZE - len)
1921 if (addr & ~PAGE_MASK)
1924 addr = arch_rebalance_pgtables(addr, len);
1925 error = security_mmap_addr(addr);
1926 return error ? error : addr;
1929 EXPORT_SYMBOL(get_unmapped_area);
1931 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1932 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1934 struct vm_area_struct *vma = NULL;
1936 if (WARN_ON_ONCE(!mm)) /* Remove this in linux-3.6 */
1939 /* Check the cache first. */
1940 /* (Cache hit rate is typically around 35%.) */
1941 vma = mm->mmap_cache;
1942 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1943 struct rb_node *rb_node;
1945 rb_node = mm->mm_rb.rb_node;
1949 struct vm_area_struct *vma_tmp;
1951 vma_tmp = rb_entry(rb_node,
1952 struct vm_area_struct, vm_rb);
1954 if (vma_tmp->vm_end > addr) {
1956 if (vma_tmp->vm_start <= addr)
1958 rb_node = rb_node->rb_left;
1960 rb_node = rb_node->rb_right;
1963 mm->mmap_cache = vma;
1968 EXPORT_SYMBOL(find_vma);
1971 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1973 struct vm_area_struct *
1974 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1975 struct vm_area_struct **pprev)
1977 struct vm_area_struct *vma;
1979 vma = find_vma(mm, addr);
1981 *pprev = vma->vm_prev;
1983 struct rb_node *rb_node = mm->mm_rb.rb_node;
1986 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1987 rb_node = rb_node->rb_right;
1994 * Verify that the stack growth is acceptable and
1995 * update accounting. This is shared with both the
1996 * grow-up and grow-down cases.
1998 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2000 struct mm_struct *mm = vma->vm_mm;
2001 struct rlimit *rlim = current->signal->rlim;
2002 unsigned long new_start;
2004 /* address space limit tests */
2005 if (!may_expand_vm(mm, grow))
2008 /* Stack limit test */
2009 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2012 /* mlock limit tests */
2013 if (vma->vm_flags & VM_LOCKED) {
2014 unsigned long locked;
2015 unsigned long limit;
2016 locked = mm->locked_vm + grow;
2017 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2018 limit >>= PAGE_SHIFT;
2019 if (locked > limit && !capable(CAP_IPC_LOCK))
2023 /* Check to ensure the stack will not grow into a hugetlb-only region */
2024 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2026 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2030 * Overcommit.. This must be the final test, as it will
2031 * update security statistics.
2033 if (security_vm_enough_memory_mm(mm, grow))
2036 /* Ok, everything looks good - let it rip */
2037 if (vma->vm_flags & VM_LOCKED)
2038 mm->locked_vm += grow;
2039 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2043 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2045 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2046 * vma is the last one with address > vma->vm_end. Have to extend vma.
2048 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2052 if (!(vma->vm_flags & VM_GROWSUP))
2056 * We must make sure the anon_vma is allocated
2057 * so that the anon_vma locking is not a noop.
2059 if (unlikely(anon_vma_prepare(vma)))
2061 vma_lock_anon_vma(vma);
2064 * vma->vm_start/vm_end cannot change under us because the caller
2065 * is required to hold the mmap_sem in read mode. We need the
2066 * anon_vma lock to serialize against concurrent expand_stacks.
2067 * Also guard against wrapping around to address 0.
2069 if (address < PAGE_ALIGN(address+4))
2070 address = PAGE_ALIGN(address+4);
2072 vma_unlock_anon_vma(vma);
2077 /* Somebody else might have raced and expanded it already */
2078 if (address > vma->vm_end) {
2079 unsigned long size, grow;
2081 size = address - vma->vm_start;
2082 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2085 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2086 error = acct_stack_growth(vma, size, grow);
2089 * vma_gap_update() doesn't support concurrent
2090 * updates, but we only hold a shared mmap_sem
2091 * lock here, so we need to protect against
2092 * concurrent vma expansions.
2093 * vma_lock_anon_vma() doesn't help here, as
2094 * we don't guarantee that all growable vmas
2095 * in a mm share the same root anon vma.
2096 * So, we reuse mm->page_table_lock to guard
2097 * against concurrent vma expansions.
2099 spin_lock(&vma->vm_mm->page_table_lock);
2100 anon_vma_interval_tree_pre_update_vma(vma);
2101 vma->vm_end = address;
2102 anon_vma_interval_tree_post_update_vma(vma);
2104 vma_gap_update(vma->vm_next);
2106 vma->vm_mm->highest_vm_end = address;
2107 spin_unlock(&vma->vm_mm->page_table_lock);
2109 perf_event_mmap(vma);
2113 vma_unlock_anon_vma(vma);
2114 khugepaged_enter_vma_merge(vma);
2115 validate_mm(vma->vm_mm);
2118 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2121 * vma is the first one with address < vma->vm_start. Have to extend vma.
2123 int expand_downwards(struct vm_area_struct *vma,
2124 unsigned long address)
2129 * We must make sure the anon_vma is allocated
2130 * so that the anon_vma locking is not a noop.
2132 if (unlikely(anon_vma_prepare(vma)))
2135 address &= PAGE_MASK;
2136 error = security_mmap_addr(address);
2140 vma_lock_anon_vma(vma);
2143 * vma->vm_start/vm_end cannot change under us because the caller
2144 * is required to hold the mmap_sem in read mode. We need the
2145 * anon_vma lock to serialize against concurrent expand_stacks.
2148 /* Somebody else might have raced and expanded it already */
2149 if (address < vma->vm_start) {
2150 unsigned long size, grow;
2152 size = vma->vm_end - address;
2153 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2156 if (grow <= vma->vm_pgoff) {
2157 error = acct_stack_growth(vma, size, grow);
2160 * vma_gap_update() doesn't support concurrent
2161 * updates, but we only hold a shared mmap_sem
2162 * lock here, so we need to protect against
2163 * concurrent vma expansions.
2164 * vma_lock_anon_vma() doesn't help here, as
2165 * we don't guarantee that all growable vmas
2166 * in a mm share the same root anon vma.
2167 * So, we reuse mm->page_table_lock to guard
2168 * against concurrent vma expansions.
2170 spin_lock(&vma->vm_mm->page_table_lock);
2171 anon_vma_interval_tree_pre_update_vma(vma);
2172 vma->vm_start = address;
2173 vma->vm_pgoff -= grow;
2174 anon_vma_interval_tree_post_update_vma(vma);
2175 vma_gap_update(vma);
2176 spin_unlock(&vma->vm_mm->page_table_lock);
2178 perf_event_mmap(vma);
2182 vma_unlock_anon_vma(vma);
2183 khugepaged_enter_vma_merge(vma);
2184 validate_mm(vma->vm_mm);
2188 #ifdef CONFIG_STACK_GROWSUP
2189 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2191 return expand_upwards(vma, address);
2194 struct vm_area_struct *
2195 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2197 struct vm_area_struct *vma, *prev;
2200 vma = find_vma_prev(mm, addr, &prev);
2201 if (vma && (vma->vm_start <= addr))
2203 if (!prev || expand_stack(prev, addr))
2205 if (prev->vm_flags & VM_LOCKED)
2206 __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2210 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2212 return expand_downwards(vma, address);
2215 struct vm_area_struct *
2216 find_extend_vma(struct mm_struct * mm, unsigned long addr)
2218 struct vm_area_struct * vma;
2219 unsigned long start;
2222 vma = find_vma(mm,addr);
2225 if (vma->vm_start <= addr)
2227 if (!(vma->vm_flags & VM_GROWSDOWN))
2229 start = vma->vm_start;
2230 if (expand_stack(vma, addr))
2232 if (vma->vm_flags & VM_LOCKED)
2233 __mlock_vma_pages_range(vma, addr, start, NULL);
2239 * Ok - we have the memory areas we should free on the vma list,
2240 * so release them, and do the vma updates.
2242 * Called with the mm semaphore held.
2244 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2246 unsigned long nr_accounted = 0;
2248 /* Update high watermark before we lower total_vm */
2249 update_hiwater_vm(mm);
2251 long nrpages = vma_pages(vma);
2253 if (vma->vm_flags & VM_ACCOUNT)
2254 nr_accounted += nrpages;
2255 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2256 vma = remove_vma(vma);
2258 vm_unacct_memory(nr_accounted);
2263 * Get rid of page table information in the indicated region.
2265 * Called with the mm semaphore held.
2267 static void unmap_region(struct mm_struct *mm,
2268 struct vm_area_struct *vma, struct vm_area_struct *prev,
2269 unsigned long start, unsigned long end)
2271 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
2272 struct mmu_gather tlb;
2275 tlb_gather_mmu(&tlb, mm, 0);
2276 update_hiwater_rss(mm);
2277 unmap_vmas(&tlb, vma, start, end);
2278 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2279 next ? next->vm_start : 0);
2280 tlb_finish_mmu(&tlb, start, end);
2284 * Create a list of vma's touched by the unmap, removing them from the mm's
2285 * vma list as we go..
2288 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2289 struct vm_area_struct *prev, unsigned long end)
2291 struct vm_area_struct **insertion_point;
2292 struct vm_area_struct *tail_vma = NULL;
2295 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2296 vma->vm_prev = NULL;
2298 vma_rb_erase(vma, &mm->mm_rb);
2302 } while (vma && vma->vm_start < end);
2303 *insertion_point = vma;
2305 vma->vm_prev = prev;
2306 vma_gap_update(vma);
2308 mm->highest_vm_end = prev ? prev->vm_end : 0;
2309 tail_vma->vm_next = NULL;
2310 if (mm->unmap_area == arch_unmap_area)
2311 addr = prev ? prev->vm_end : mm->mmap_base;
2313 addr = vma ? vma->vm_start : mm->mmap_base;
2314 mm->unmap_area(mm, addr);
2315 mm->mmap_cache = NULL; /* Kill the cache. */
2319 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2320 * munmap path where it doesn't make sense to fail.
2322 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
2323 unsigned long addr, int new_below)
2325 struct mempolicy *pol;
2326 struct vm_area_struct *new;
2329 if (is_vm_hugetlb_page(vma) && (addr &
2330 ~(huge_page_mask(hstate_vma(vma)))))
2333 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2337 /* most fields are the same, copy all, and then fixup */
2340 INIT_LIST_HEAD(&new->anon_vma_chain);
2345 new->vm_start = addr;
2346 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2349 pol = mpol_dup(vma_policy(vma));
2354 vma_set_policy(new, pol);
2356 if (anon_vma_clone(new, vma))
2360 get_file(new->vm_file);
2362 if (new->vm_ops && new->vm_ops->open)
2363 new->vm_ops->open(new);
2366 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2367 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2369 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2375 /* Clean everything up if vma_adjust failed. */
2376 if (new->vm_ops && new->vm_ops->close)
2377 new->vm_ops->close(new);
2380 unlink_anon_vmas(new);
2384 kmem_cache_free(vm_area_cachep, new);
2390 * Split a vma into two pieces at address 'addr', a new vma is allocated
2391 * either for the first part or the tail.
2393 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2394 unsigned long addr, int new_below)
2396 if (mm->map_count >= sysctl_max_map_count)
2399 return __split_vma(mm, vma, addr, new_below);
2402 /* Munmap is split into 2 main parts -- this part which finds
2403 * what needs doing, and the areas themselves, which do the
2404 * work. This now handles partial unmappings.
2405 * Jeremy Fitzhardinge <jeremy@goop.org>
2407 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2410 struct vm_area_struct *vma, *prev, *last;
2412 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2415 if ((len = PAGE_ALIGN(len)) == 0)
2418 /* Find the first overlapping VMA */
2419 vma = find_vma(mm, start);
2422 prev = vma->vm_prev;
2423 /* we have start < vma->vm_end */
2425 /* if it doesn't overlap, we have nothing.. */
2427 if (vma->vm_start >= end)
2431 * If we need to split any vma, do it now to save pain later.
2433 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2434 * unmapped vm_area_struct will remain in use: so lower split_vma
2435 * places tmp vma above, and higher split_vma places tmp vma below.
2437 if (start > vma->vm_start) {
2441 * Make sure that map_count on return from munmap() will
2442 * not exceed its limit; but let map_count go just above
2443 * its limit temporarily, to help free resources as expected.
2445 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2448 error = __split_vma(mm, vma, start, 0);
2454 /* Does it split the last one? */
2455 last = find_vma(mm, end);
2456 if (last && end > last->vm_start) {
2457 int error = __split_vma(mm, last, end, 1);
2461 vma = prev? prev->vm_next: mm->mmap;
2464 * unlock any mlock()ed ranges before detaching vmas
2466 if (mm->locked_vm) {
2467 struct vm_area_struct *tmp = vma;
2468 while (tmp && tmp->vm_start < end) {
2469 if (tmp->vm_flags & VM_LOCKED) {
2470 mm->locked_vm -= vma_pages(tmp);
2471 munlock_vma_pages_all(tmp);
2478 * Remove the vma's, and unmap the actual pages
2480 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2481 unmap_region(mm, vma, prev, start, end);
2483 /* Fix up all other VM information */
2484 remove_vma_list(mm, vma);
2489 int vm_munmap(unsigned long start, size_t len)
2492 struct mm_struct *mm = current->mm;
2494 down_write(&mm->mmap_sem);
2495 ret = do_munmap(mm, start, len);
2496 up_write(&mm->mmap_sem);
2499 EXPORT_SYMBOL(vm_munmap);
2501 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2503 profile_munmap(addr);
2504 return vm_munmap(addr, len);
2507 static inline void verify_mm_writelocked(struct mm_struct *mm)
2509 #ifdef CONFIG_DEBUG_VM
2510 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2512 up_read(&mm->mmap_sem);
2518 * this is really a simplified "do_mmap". it only handles
2519 * anonymous maps. eventually we may be able to do some
2520 * brk-specific accounting here.
2522 static unsigned long do_brk(unsigned long addr, unsigned long len)
2524 struct mm_struct * mm = current->mm;
2525 struct vm_area_struct * vma, * prev;
2526 unsigned long flags;
2527 struct rb_node ** rb_link, * rb_parent;
2528 pgoff_t pgoff = addr >> PAGE_SHIFT;
2531 len = PAGE_ALIGN(len);
2535 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2537 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2538 if (error & ~PAGE_MASK)
2544 if (mm->def_flags & VM_LOCKED) {
2545 unsigned long locked, lock_limit;
2546 locked = len >> PAGE_SHIFT;
2547 locked += mm->locked_vm;
2548 lock_limit = rlimit(RLIMIT_MEMLOCK);
2549 lock_limit >>= PAGE_SHIFT;
2550 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2555 * mm->mmap_sem is required to protect against another thread
2556 * changing the mappings in case we sleep.
2558 verify_mm_writelocked(mm);
2561 * Clear old maps. this also does some error checking for us
2564 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
2565 if (do_munmap(mm, addr, len))
2570 /* Check against address space limits *after* clearing old maps... */
2571 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2574 if (mm->map_count > sysctl_max_map_count)
2577 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2580 /* Can we just expand an old private anonymous mapping? */
2581 vma = vma_merge(mm, prev, addr, addr + len, flags,
2582 NULL, NULL, pgoff, NULL);
2587 * create a vma struct for an anonymous mapping
2589 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2591 vm_unacct_memory(len >> PAGE_SHIFT);
2595 INIT_LIST_HEAD(&vma->anon_vma_chain);
2597 vma->vm_start = addr;
2598 vma->vm_end = addr + len;
2599 vma->vm_pgoff = pgoff;
2600 vma->vm_flags = flags;
2601 vma->vm_page_prot = vm_get_page_prot(flags);
2602 vma_link(mm, vma, prev, rb_link, rb_parent);
2604 perf_event_mmap(vma);
2605 mm->total_vm += len >> PAGE_SHIFT;
2606 if (flags & VM_LOCKED)
2607 mm->locked_vm += (len >> PAGE_SHIFT);
2611 unsigned long vm_brk(unsigned long addr, unsigned long len)
2613 struct mm_struct *mm = current->mm;
2617 down_write(&mm->mmap_sem);
2618 ret = do_brk(addr, len);
2619 populate = ((mm->def_flags & VM_LOCKED) != 0);
2620 up_write(&mm->mmap_sem);
2622 mm_populate(addr, len);
2625 EXPORT_SYMBOL(vm_brk);
2627 /* Release all mmaps. */
2628 void exit_mmap(struct mm_struct *mm)
2630 struct mmu_gather tlb;
2631 struct vm_area_struct *vma;
2632 unsigned long nr_accounted = 0;
2634 /* mm's last user has gone, and its about to be pulled down */
2635 mmu_notifier_release(mm);
2637 if (mm->locked_vm) {
2640 if (vma->vm_flags & VM_LOCKED)
2641 munlock_vma_pages_all(vma);
2649 if (!vma) /* Can happen if dup_mmap() received an OOM */
2654 tlb_gather_mmu(&tlb, mm, 1);
2655 /* update_hiwater_rss(mm) here? but nobody should be looking */
2656 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2657 unmap_vmas(&tlb, vma, 0, -1);
2659 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2660 tlb_finish_mmu(&tlb, 0, -1);
2663 * Walk the list again, actually closing and freeing it,
2664 * with preemption enabled, without holding any MM locks.
2667 if (vma->vm_flags & VM_ACCOUNT)
2668 nr_accounted += vma_pages(vma);
2669 vma = remove_vma(vma);
2671 vm_unacct_memory(nr_accounted);
2673 WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2676 /* Insert vm structure into process list sorted by address
2677 * and into the inode's i_mmap tree. If vm_file is non-NULL
2678 * then i_mmap_mutex is taken here.
2680 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2682 struct vm_area_struct *prev;
2683 struct rb_node **rb_link, *rb_parent;
2686 * The vm_pgoff of a purely anonymous vma should be irrelevant
2687 * until its first write fault, when page's anon_vma and index
2688 * are set. But now set the vm_pgoff it will almost certainly
2689 * end up with (unless mremap moves it elsewhere before that
2690 * first wfault), so /proc/pid/maps tells a consistent story.
2692 * By setting it to reflect the virtual start address of the
2693 * vma, merges and splits can happen in a seamless way, just
2694 * using the existing file pgoff checks and manipulations.
2695 * Similarly in do_mmap_pgoff and in do_brk.
2697 if (!vma->vm_file) {
2698 BUG_ON(vma->anon_vma);
2699 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2701 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2702 &prev, &rb_link, &rb_parent))
2704 if ((vma->vm_flags & VM_ACCOUNT) &&
2705 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2708 vma_link(mm, vma, prev, rb_link, rb_parent);
2713 * Copy the vma structure to a new location in the same mm,
2714 * prior to moving page table entries, to effect an mremap move.
2716 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2717 unsigned long addr, unsigned long len, pgoff_t pgoff,
2718 bool *need_rmap_locks)
2720 struct vm_area_struct *vma = *vmap;
2721 unsigned long vma_start = vma->vm_start;
2722 struct mm_struct *mm = vma->vm_mm;
2723 struct vm_area_struct *new_vma, *prev;
2724 struct rb_node **rb_link, *rb_parent;
2725 struct mempolicy *pol;
2726 bool faulted_in_anon_vma = true;
2729 * If anonymous vma has not yet been faulted, update new pgoff
2730 * to match new location, to increase its chance of merging.
2732 if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2733 pgoff = addr >> PAGE_SHIFT;
2734 faulted_in_anon_vma = false;
2737 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2738 return NULL; /* should never get here */
2739 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2740 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2743 * Source vma may have been merged into new_vma
2745 if (unlikely(vma_start >= new_vma->vm_start &&
2746 vma_start < new_vma->vm_end)) {
2748 * The only way we can get a vma_merge with
2749 * self during an mremap is if the vma hasn't
2750 * been faulted in yet and we were allowed to
2751 * reset the dst vma->vm_pgoff to the
2752 * destination address of the mremap to allow
2753 * the merge to happen. mremap must change the
2754 * vm_pgoff linearity between src and dst vmas
2755 * (in turn preventing a vma_merge) to be
2756 * safe. It is only safe to keep the vm_pgoff
2757 * linear if there are no pages mapped yet.
2759 VM_BUG_ON(faulted_in_anon_vma);
2760 *vmap = vma = new_vma;
2762 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2764 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2767 new_vma->vm_start = addr;
2768 new_vma->vm_end = addr + len;
2769 new_vma->vm_pgoff = pgoff;
2770 pol = mpol_dup(vma_policy(vma));
2773 vma_set_policy(new_vma, pol);
2774 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2775 if (anon_vma_clone(new_vma, vma))
2776 goto out_free_mempol;
2777 if (new_vma->vm_file)
2778 get_file(new_vma->vm_file);
2779 if (new_vma->vm_ops && new_vma->vm_ops->open)
2780 new_vma->vm_ops->open(new_vma);
2781 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2782 *need_rmap_locks = false;
2790 kmem_cache_free(vm_area_cachep, new_vma);
2795 * Return true if the calling process may expand its vm space by the passed
2798 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2800 unsigned long cur = mm->total_vm; /* pages */
2803 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2805 if (cur + npages > lim)
2811 static int special_mapping_fault(struct vm_area_struct *vma,
2812 struct vm_fault *vmf)
2815 struct page **pages;
2818 * special mappings have no vm_file, and in that case, the mm
2819 * uses vm_pgoff internally. So we have to subtract it from here.
2820 * We are allowed to do this because we are the mm; do not copy
2821 * this code into drivers!
2823 pgoff = vmf->pgoff - vma->vm_pgoff;
2825 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2829 struct page *page = *pages;
2835 return VM_FAULT_SIGBUS;
2839 * Having a close hook prevents vma merging regardless of flags.
2841 static void special_mapping_close(struct vm_area_struct *vma)
2845 static const struct vm_operations_struct special_mapping_vmops = {
2846 .close = special_mapping_close,
2847 .fault = special_mapping_fault,
2851 * Called with mm->mmap_sem held for writing.
2852 * Insert a new vma covering the given region, with the given flags.
2853 * Its pages are supplied by the given array of struct page *.
2854 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2855 * The region past the last page supplied will always produce SIGBUS.
2856 * The array pointer and the pages it points to are assumed to stay alive
2857 * for as long as this mapping might exist.
2859 int install_special_mapping(struct mm_struct *mm,
2860 unsigned long addr, unsigned long len,
2861 unsigned long vm_flags, struct page **pages)
2864 struct vm_area_struct *vma;
2866 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2867 if (unlikely(vma == NULL))
2870 INIT_LIST_HEAD(&vma->anon_vma_chain);
2872 vma->vm_start = addr;
2873 vma->vm_end = addr + len;
2875 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2876 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2878 vma->vm_ops = &special_mapping_vmops;
2879 vma->vm_private_data = pages;
2881 ret = insert_vm_struct(mm, vma);
2885 mm->total_vm += len >> PAGE_SHIFT;
2887 perf_event_mmap(vma);
2892 kmem_cache_free(vm_area_cachep, vma);
2896 static DEFINE_MUTEX(mm_all_locks_mutex);
2898 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2900 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
2902 * The LSB of head.next can't change from under us
2903 * because we hold the mm_all_locks_mutex.
2905 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
2907 * We can safely modify head.next after taking the
2908 * anon_vma->root->rwsem. If some other vma in this mm shares
2909 * the same anon_vma we won't take it again.
2911 * No need of atomic instructions here, head.next
2912 * can't change from under us thanks to the
2913 * anon_vma->root->rwsem.
2915 if (__test_and_set_bit(0, (unsigned long *)
2916 &anon_vma->root->rb_root.rb_node))
2921 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2923 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2925 * AS_MM_ALL_LOCKS can't change from under us because
2926 * we hold the mm_all_locks_mutex.
2928 * Operations on ->flags have to be atomic because
2929 * even if AS_MM_ALL_LOCKS is stable thanks to the
2930 * mm_all_locks_mutex, there may be other cpus
2931 * changing other bitflags in parallel to us.
2933 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2935 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2940 * This operation locks against the VM for all pte/vma/mm related
2941 * operations that could ever happen on a certain mm. This includes
2942 * vmtruncate, try_to_unmap, and all page faults.
2944 * The caller must take the mmap_sem in write mode before calling
2945 * mm_take_all_locks(). The caller isn't allowed to release the
2946 * mmap_sem until mm_drop_all_locks() returns.
2948 * mmap_sem in write mode is required in order to block all operations
2949 * that could modify pagetables and free pages without need of
2950 * altering the vma layout (for example populate_range() with
2951 * nonlinear vmas). It's also needed in write mode to avoid new
2952 * anon_vmas to be associated with existing vmas.
2954 * A single task can't take more than one mm_take_all_locks() in a row
2955 * or it would deadlock.
2957 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
2958 * mapping->flags avoid to take the same lock twice, if more than one
2959 * vma in this mm is backed by the same anon_vma or address_space.
2961 * We can take all the locks in random order because the VM code
2962 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
2963 * takes more than one of them in a row. Secondly we're protected
2964 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2966 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2967 * that may have to take thousand of locks.
2969 * mm_take_all_locks() can fail if it's interrupted by signals.
2971 int mm_take_all_locks(struct mm_struct *mm)
2973 struct vm_area_struct *vma;
2974 struct anon_vma_chain *avc;
2976 BUG_ON(down_read_trylock(&mm->mmap_sem));
2978 mutex_lock(&mm_all_locks_mutex);
2980 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2981 if (signal_pending(current))
2983 if (vma->vm_file && vma->vm_file->f_mapping)
2984 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2987 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2988 if (signal_pending(current))
2991 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2992 vm_lock_anon_vma(mm, avc->anon_vma);
2998 mm_drop_all_locks(mm);
3002 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3004 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3006 * The LSB of head.next can't change to 0 from under
3007 * us because we hold the mm_all_locks_mutex.
3009 * We must however clear the bitflag before unlocking
3010 * the vma so the users using the anon_vma->rb_root will
3011 * never see our bitflag.
3013 * No need of atomic instructions here, head.next
3014 * can't change from under us until we release the
3015 * anon_vma->root->rwsem.
3017 if (!__test_and_clear_bit(0, (unsigned long *)
3018 &anon_vma->root->rb_root.rb_node))
3020 anon_vma_unlock_write(anon_vma);
3024 static void vm_unlock_mapping(struct address_space *mapping)
3026 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3028 * AS_MM_ALL_LOCKS can't change to 0 from under us
3029 * because we hold the mm_all_locks_mutex.
3031 mutex_unlock(&mapping->i_mmap_mutex);
3032 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3039 * The mmap_sem cannot be released by the caller until
3040 * mm_drop_all_locks() returns.
3042 void mm_drop_all_locks(struct mm_struct *mm)
3044 struct vm_area_struct *vma;
3045 struct anon_vma_chain *avc;
3047 BUG_ON(down_read_trylock(&mm->mmap_sem));
3048 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3050 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3052 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3053 vm_unlock_anon_vma(avc->anon_vma);
3054 if (vma->vm_file && vma->vm_file->f_mapping)
3055 vm_unlock_mapping(vma->vm_file->f_mapping);
3058 mutex_unlock(&mm_all_locks_mutex);
3062 * initialise the VMA slab
3064 void __init mmap_init(void)
3068 ret = percpu_counter_init(&vm_committed_as, 0);