6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/backing-dev.h>
15 #include <linux/vmacache.h>
16 #include <linux/shm.h>
17 #include <linux/mman.h>
18 #include <linux/pagemap.h>
19 #include <linux/swap.h>
20 #include <linux/syscalls.h>
21 #include <linux/capability.h>
22 #include <linux/init.h>
23 #include <linux/file.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/hugetlb.h>
28 #include <linux/shmem_fs.h>
29 #include <linux/profile.h>
30 #include <linux/export.h>
31 #include <linux/mount.h>
32 #include <linux/mempolicy.h>
33 #include <linux/rmap.h>
34 #include <linux/mmu_notifier.h>
35 #include <linux/mmdebug.h>
36 #include <linux/perf_event.h>
37 #include <linux/audit.h>
38 #include <linux/khugepaged.h>
39 #include <linux/uprobes.h>
40 #include <linux/rbtree_augmented.h>
41 #include <linux/notifier.h>
42 #include <linux/memory.h>
43 #include <linux/printk.h>
44 #include <linux/userfaultfd_k.h>
45 #include <linux/moduleparam.h>
46 #include <linux/pkeys.h>
48 #include <asm/uaccess.h>
49 #include <asm/cacheflush.h>
51 #include <asm/mmu_context.h>
55 #ifndef arch_mmap_check
56 #define arch_mmap_check(addr, len, flags) (0)
59 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
60 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
61 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
62 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
64 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
65 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
66 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
67 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
70 static bool ignore_rlimit_data;
71 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
73 static void unmap_region(struct mm_struct *mm,
74 struct vm_area_struct *vma, struct vm_area_struct *prev,
75 unsigned long start, unsigned long end);
77 /* description of effects of mapping type and prot in current implementation.
78 * this is due to the limited x86 page protection hardware. The expected
79 * behavior is in parens:
82 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
83 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
84 * w: (no) no w: (no) no w: (yes) yes w: (no) no
85 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
87 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
88 * w: (no) no w: (no) no w: (copy) copy w: (no) no
89 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
92 pgprot_t protection_map[16] = {
93 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
94 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
97 pgprot_t vm_get_page_prot(unsigned long vm_flags)
99 return __pgprot(pgprot_val(protection_map[vm_flags &
100 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
101 pgprot_val(arch_vm_get_page_prot(vm_flags)));
103 EXPORT_SYMBOL(vm_get_page_prot);
105 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
107 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
110 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
111 void vma_set_page_prot(struct vm_area_struct *vma)
113 unsigned long vm_flags = vma->vm_flags;
115 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
116 if (vma_wants_writenotify(vma)) {
117 vm_flags &= ~VM_SHARED;
118 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
124 * Requires inode->i_mapping->i_mmap_rwsem
126 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
127 struct file *file, struct address_space *mapping)
129 if (vma->vm_flags & VM_DENYWRITE)
130 atomic_inc(&file_inode(file)->i_writecount);
131 if (vma->vm_flags & VM_SHARED)
132 mapping_unmap_writable(mapping);
134 flush_dcache_mmap_lock(mapping);
135 vma_interval_tree_remove(vma, &mapping->i_mmap);
136 flush_dcache_mmap_unlock(mapping);
140 * Unlink a file-based vm structure from its interval tree, to hide
141 * vma from rmap and vmtruncate before freeing its page tables.
143 void unlink_file_vma(struct vm_area_struct *vma)
145 struct file *file = vma->vm_file;
148 struct address_space *mapping = file->f_mapping;
149 i_mmap_lock_write(mapping);
150 __remove_shared_vm_struct(vma, file, mapping);
151 i_mmap_unlock_write(mapping);
156 * Close a vm structure and free it, returning the next.
158 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
160 struct vm_area_struct *next = vma->vm_next;
163 if (vma->vm_ops && vma->vm_ops->close)
164 vma->vm_ops->close(vma);
167 mpol_put(vma_policy(vma));
168 kmem_cache_free(vm_area_cachep, vma);
172 static int do_brk(unsigned long addr, unsigned long len);
174 SYSCALL_DEFINE1(brk, unsigned long, brk)
176 unsigned long retval;
177 unsigned long newbrk, oldbrk;
178 struct mm_struct *mm = current->mm;
179 unsigned long min_brk;
182 if (down_write_killable(&mm->mmap_sem))
185 #ifdef CONFIG_COMPAT_BRK
187 * CONFIG_COMPAT_BRK can still be overridden by setting
188 * randomize_va_space to 2, which will still cause mm->start_brk
189 * to be arbitrarily shifted
191 if (current->brk_randomized)
192 min_brk = mm->start_brk;
194 min_brk = mm->end_data;
196 min_brk = mm->start_brk;
202 * Check against rlimit here. If this check is done later after the test
203 * of oldbrk with newbrk then it can escape the test and let the data
204 * segment grow beyond its set limit the in case where the limit is
205 * not page aligned -Ram Gupta
207 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
208 mm->end_data, mm->start_data))
211 newbrk = PAGE_ALIGN(brk);
212 oldbrk = PAGE_ALIGN(mm->brk);
213 if (oldbrk == newbrk)
216 /* Always allow shrinking brk. */
217 if (brk <= mm->brk) {
218 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
223 /* Check against existing mmap mappings. */
224 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
227 /* Ok, looks good - let it rip. */
228 if (do_brk(oldbrk, newbrk-oldbrk) < 0)
233 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
234 up_write(&mm->mmap_sem);
236 mm_populate(oldbrk, newbrk - oldbrk);
241 up_write(&mm->mmap_sem);
245 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
247 unsigned long max, subtree_gap;
250 max -= vma->vm_prev->vm_end;
251 if (vma->vm_rb.rb_left) {
252 subtree_gap = rb_entry(vma->vm_rb.rb_left,
253 struct vm_area_struct, vm_rb)->rb_subtree_gap;
254 if (subtree_gap > max)
257 if (vma->vm_rb.rb_right) {
258 subtree_gap = rb_entry(vma->vm_rb.rb_right,
259 struct vm_area_struct, vm_rb)->rb_subtree_gap;
260 if (subtree_gap > max)
266 #ifdef CONFIG_DEBUG_VM_RB
267 static int browse_rb(struct mm_struct *mm)
269 struct rb_root *root = &mm->mm_rb;
270 int i = 0, j, bug = 0;
271 struct rb_node *nd, *pn = NULL;
272 unsigned long prev = 0, pend = 0;
274 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
275 struct vm_area_struct *vma;
276 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
277 if (vma->vm_start < prev) {
278 pr_emerg("vm_start %lx < prev %lx\n",
279 vma->vm_start, prev);
282 if (vma->vm_start < pend) {
283 pr_emerg("vm_start %lx < pend %lx\n",
284 vma->vm_start, pend);
287 if (vma->vm_start > vma->vm_end) {
288 pr_emerg("vm_start %lx > vm_end %lx\n",
289 vma->vm_start, vma->vm_end);
292 spin_lock(&mm->page_table_lock);
293 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
294 pr_emerg("free gap %lx, correct %lx\n",
296 vma_compute_subtree_gap(vma));
299 spin_unlock(&mm->page_table_lock);
302 prev = vma->vm_start;
306 for (nd = pn; nd; nd = rb_prev(nd))
309 pr_emerg("backwards %d, forwards %d\n", j, i);
315 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
319 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
320 struct vm_area_struct *vma;
321 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
322 VM_BUG_ON_VMA(vma != ignore &&
323 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
328 static void validate_mm(struct mm_struct *mm)
332 unsigned long highest_address = 0;
333 struct vm_area_struct *vma = mm->mmap;
336 struct anon_vma *anon_vma = vma->anon_vma;
337 struct anon_vma_chain *avc;
340 anon_vma_lock_read(anon_vma);
341 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
342 anon_vma_interval_tree_verify(avc);
343 anon_vma_unlock_read(anon_vma);
346 highest_address = vma->vm_end;
350 if (i != mm->map_count) {
351 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
354 if (highest_address != mm->highest_vm_end) {
355 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
356 mm->highest_vm_end, highest_address);
360 if (i != mm->map_count) {
362 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
365 VM_BUG_ON_MM(bug, mm);
368 #define validate_mm_rb(root, ignore) do { } while (0)
369 #define validate_mm(mm) do { } while (0)
372 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
373 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
376 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
377 * vma->vm_prev->vm_end values changed, without modifying the vma's position
380 static void vma_gap_update(struct vm_area_struct *vma)
383 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
384 * function that does exacltly what we want.
386 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
389 static inline void vma_rb_insert(struct vm_area_struct *vma,
390 struct rb_root *root)
392 /* All rb_subtree_gap values must be consistent prior to insertion */
393 validate_mm_rb(root, NULL);
395 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
398 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
401 * All rb_subtree_gap values must be consistent prior to erase,
402 * with the possible exception of the vma being erased.
404 validate_mm_rb(root, vma);
407 * Note rb_erase_augmented is a fairly large inline function,
408 * so make sure we instantiate it only once with our desired
409 * augmented rbtree callbacks.
411 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
415 * vma has some anon_vma assigned, and is already inserted on that
416 * anon_vma's interval trees.
418 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
419 * vma must be removed from the anon_vma's interval trees using
420 * anon_vma_interval_tree_pre_update_vma().
422 * After the update, the vma will be reinserted using
423 * anon_vma_interval_tree_post_update_vma().
425 * The entire update must be protected by exclusive mmap_sem and by
426 * the root anon_vma's mutex.
429 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
431 struct anon_vma_chain *avc;
433 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
434 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
438 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
440 struct anon_vma_chain *avc;
442 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
443 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
446 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
447 unsigned long end, struct vm_area_struct **pprev,
448 struct rb_node ***rb_link, struct rb_node **rb_parent)
450 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
452 __rb_link = &mm->mm_rb.rb_node;
453 rb_prev = __rb_parent = NULL;
456 struct vm_area_struct *vma_tmp;
458 __rb_parent = *__rb_link;
459 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
461 if (vma_tmp->vm_end > addr) {
462 /* Fail if an existing vma overlaps the area */
463 if (vma_tmp->vm_start < end)
465 __rb_link = &__rb_parent->rb_left;
467 rb_prev = __rb_parent;
468 __rb_link = &__rb_parent->rb_right;
474 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
475 *rb_link = __rb_link;
476 *rb_parent = __rb_parent;
480 static unsigned long count_vma_pages_range(struct mm_struct *mm,
481 unsigned long addr, unsigned long end)
483 unsigned long nr_pages = 0;
484 struct vm_area_struct *vma;
486 /* Find first overlaping mapping */
487 vma = find_vma_intersection(mm, addr, end);
491 nr_pages = (min(end, vma->vm_end) -
492 max(addr, vma->vm_start)) >> PAGE_SHIFT;
494 /* Iterate over the rest of the overlaps */
495 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
496 unsigned long overlap_len;
498 if (vma->vm_start > end)
501 overlap_len = min(end, vma->vm_end) - vma->vm_start;
502 nr_pages += overlap_len >> PAGE_SHIFT;
508 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
509 struct rb_node **rb_link, struct rb_node *rb_parent)
511 /* Update tracking information for the gap following the new vma. */
513 vma_gap_update(vma->vm_next);
515 mm->highest_vm_end = vma->vm_end;
518 * vma->vm_prev wasn't known when we followed the rbtree to find the
519 * correct insertion point for that vma. As a result, we could not
520 * update the vma vm_rb parents rb_subtree_gap values on the way down.
521 * So, we first insert the vma with a zero rb_subtree_gap value
522 * (to be consistent with what we did on the way down), and then
523 * immediately update the gap to the correct value. Finally we
524 * rebalance the rbtree after all augmented values have been set.
526 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
527 vma->rb_subtree_gap = 0;
529 vma_rb_insert(vma, &mm->mm_rb);
532 static void __vma_link_file(struct vm_area_struct *vma)
538 struct address_space *mapping = file->f_mapping;
540 if (vma->vm_flags & VM_DENYWRITE)
541 atomic_dec(&file_inode(file)->i_writecount);
542 if (vma->vm_flags & VM_SHARED)
543 atomic_inc(&mapping->i_mmap_writable);
545 flush_dcache_mmap_lock(mapping);
546 vma_interval_tree_insert(vma, &mapping->i_mmap);
547 flush_dcache_mmap_unlock(mapping);
552 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
553 struct vm_area_struct *prev, struct rb_node **rb_link,
554 struct rb_node *rb_parent)
556 __vma_link_list(mm, vma, prev, rb_parent);
557 __vma_link_rb(mm, vma, rb_link, rb_parent);
560 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
561 struct vm_area_struct *prev, struct rb_node **rb_link,
562 struct rb_node *rb_parent)
564 struct address_space *mapping = NULL;
567 mapping = vma->vm_file->f_mapping;
568 i_mmap_lock_write(mapping);
571 __vma_link(mm, vma, prev, rb_link, rb_parent);
572 __vma_link_file(vma);
575 i_mmap_unlock_write(mapping);
582 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
583 * mm's list and rbtree. It has already been inserted into the interval tree.
585 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
587 struct vm_area_struct *prev;
588 struct rb_node **rb_link, *rb_parent;
590 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
591 &prev, &rb_link, &rb_parent))
593 __vma_link(mm, vma, prev, rb_link, rb_parent);
598 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
599 struct vm_area_struct *prev)
601 struct vm_area_struct *next;
603 vma_rb_erase(vma, &mm->mm_rb);
604 prev->vm_next = next = vma->vm_next;
606 next->vm_prev = prev;
609 vmacache_invalidate(mm);
613 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
614 * is already present in an i_mmap tree without adjusting the tree.
615 * The following helper function should be used when such adjustments
616 * are necessary. The "insert" vma (if any) is to be inserted
617 * before we drop the necessary locks.
619 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
620 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
622 struct mm_struct *mm = vma->vm_mm;
623 struct vm_area_struct *next = vma->vm_next;
624 struct vm_area_struct *importer = NULL;
625 struct address_space *mapping = NULL;
626 struct rb_root *root = NULL;
627 struct anon_vma *anon_vma = NULL;
628 struct file *file = vma->vm_file;
629 bool start_changed = false, end_changed = false;
630 long adjust_next = 0;
633 if (next && !insert) {
634 struct vm_area_struct *exporter = NULL;
636 if (end >= next->vm_end) {
638 * vma expands, overlapping all the next, and
639 * perhaps the one after too (mprotect case 6).
641 again: remove_next = 1 + (end > next->vm_end);
645 } else if (end > next->vm_start) {
647 * vma expands, overlapping part of the next:
648 * mprotect case 5 shifting the boundary up.
650 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
653 } else if (end < vma->vm_end) {
655 * vma shrinks, and !insert tells it's not
656 * split_vma inserting another: so it must be
657 * mprotect case 4 shifting the boundary down.
659 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
665 * Easily overlooked: when mprotect shifts the boundary,
666 * make sure the expanding vma has anon_vma set if the
667 * shrinking vma had, to cover any anon pages imported.
669 if (exporter && exporter->anon_vma && !importer->anon_vma) {
672 importer->anon_vma = exporter->anon_vma;
673 error = anon_vma_clone(importer, exporter);
679 vma_adjust_trans_huge(vma, start, end, adjust_next);
682 mapping = file->f_mapping;
683 root = &mapping->i_mmap;
684 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
687 uprobe_munmap(next, next->vm_start, next->vm_end);
689 i_mmap_lock_write(mapping);
692 * Put into interval tree now, so instantiated pages
693 * are visible to arm/parisc __flush_dcache_page
694 * throughout; but we cannot insert into address
695 * space until vma start or end is updated.
697 __vma_link_file(insert);
701 anon_vma = vma->anon_vma;
702 if (!anon_vma && adjust_next)
703 anon_vma = next->anon_vma;
705 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
706 anon_vma != next->anon_vma, next);
707 anon_vma_lock_write(anon_vma);
708 anon_vma_interval_tree_pre_update_vma(vma);
710 anon_vma_interval_tree_pre_update_vma(next);
714 flush_dcache_mmap_lock(mapping);
715 vma_interval_tree_remove(vma, root);
717 vma_interval_tree_remove(next, root);
720 if (start != vma->vm_start) {
721 vma->vm_start = start;
722 start_changed = true;
724 if (end != vma->vm_end) {
728 vma->vm_pgoff = pgoff;
730 next->vm_start += adjust_next << PAGE_SHIFT;
731 next->vm_pgoff += adjust_next;
736 vma_interval_tree_insert(next, root);
737 vma_interval_tree_insert(vma, root);
738 flush_dcache_mmap_unlock(mapping);
743 * vma_merge has merged next into vma, and needs
744 * us to remove next before dropping the locks.
746 __vma_unlink(mm, next, vma);
748 __remove_shared_vm_struct(next, file, mapping);
751 * split_vma has split insert from vma, and needs
752 * us to insert it before dropping the locks
753 * (it may either follow vma or precede it).
755 __insert_vm_struct(mm, insert);
761 mm->highest_vm_end = end;
762 else if (!adjust_next)
763 vma_gap_update(next);
768 anon_vma_interval_tree_post_update_vma(vma);
770 anon_vma_interval_tree_post_update_vma(next);
771 anon_vma_unlock_write(anon_vma);
774 i_mmap_unlock_write(mapping);
785 uprobe_munmap(next, next->vm_start, next->vm_end);
789 anon_vma_merge(vma, next);
791 mpol_put(vma_policy(next));
792 kmem_cache_free(vm_area_cachep, next);
794 * In mprotect's case 6 (see comments on vma_merge),
795 * we must remove another next too. It would clutter
796 * up the code too much to do both in one go.
799 if (remove_next == 2)
802 vma_gap_update(next);
804 mm->highest_vm_end = end;
815 * If the vma has a ->close operation then the driver probably needs to release
816 * per-vma resources, so we don't attempt to merge those.
818 static inline int is_mergeable_vma(struct vm_area_struct *vma,
819 struct file *file, unsigned long vm_flags,
820 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
823 * VM_SOFTDIRTY should not prevent from VMA merging, if we
824 * match the flags but dirty bit -- the caller should mark
825 * merged VMA as dirty. If dirty bit won't be excluded from
826 * comparison, we increase pressue on the memory system forcing
827 * the kernel to generate new VMAs when old one could be
830 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
832 if (vma->vm_file != file)
834 if (vma->vm_ops && vma->vm_ops->close)
836 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
841 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
842 struct anon_vma *anon_vma2,
843 struct vm_area_struct *vma)
846 * The list_is_singular() test is to avoid merging VMA cloned from
847 * parents. This can improve scalability caused by anon_vma lock.
849 if ((!anon_vma1 || !anon_vma2) && (!vma ||
850 list_is_singular(&vma->anon_vma_chain)))
852 return anon_vma1 == anon_vma2;
856 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
857 * in front of (at a lower virtual address and file offset than) the vma.
859 * We cannot merge two vmas if they have differently assigned (non-NULL)
860 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
862 * We don't check here for the merged mmap wrapping around the end of pagecache
863 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
864 * wrap, nor mmaps which cover the final page at index -1UL.
867 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
868 struct anon_vma *anon_vma, struct file *file,
870 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
872 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
873 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
874 if (vma->vm_pgoff == vm_pgoff)
881 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
882 * beyond (at a higher virtual address and file offset than) the vma.
884 * We cannot merge two vmas if they have differently assigned (non-NULL)
885 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
888 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
889 struct anon_vma *anon_vma, struct file *file,
891 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
893 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
894 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
896 vm_pglen = vma_pages(vma);
897 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
904 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
905 * whether that can be merged with its predecessor or its successor.
906 * Or both (it neatly fills a hole).
908 * In most cases - when called for mmap, brk or mremap - [addr,end) is
909 * certain not to be mapped by the time vma_merge is called; but when
910 * called for mprotect, it is certain to be already mapped (either at
911 * an offset within prev, or at the start of next), and the flags of
912 * this area are about to be changed to vm_flags - and the no-change
913 * case has already been eliminated.
915 * The following mprotect cases have to be considered, where AAAA is
916 * the area passed down from mprotect_fixup, never extending beyond one
917 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
919 * AAAA AAAA AAAA AAAA
920 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
921 * cannot merge might become might become might become
922 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
923 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
924 * mremap move: PPPPNNNNNNNN 8
926 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
927 * might become case 1 below case 2 below case 3 below
929 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
930 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
932 struct vm_area_struct *vma_merge(struct mm_struct *mm,
933 struct vm_area_struct *prev, unsigned long addr,
934 unsigned long end, unsigned long vm_flags,
935 struct anon_vma *anon_vma, struct file *file,
936 pgoff_t pgoff, struct mempolicy *policy,
937 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
939 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
940 struct vm_area_struct *area, *next;
944 * We later require that vma->vm_flags == vm_flags,
945 * so this tests vma->vm_flags & VM_SPECIAL, too.
947 if (vm_flags & VM_SPECIAL)
951 next = prev->vm_next;
955 if (next && next->vm_end == end) /* cases 6, 7, 8 */
956 next = next->vm_next;
959 * Can it merge with the predecessor?
961 if (prev && prev->vm_end == addr &&
962 mpol_equal(vma_policy(prev), policy) &&
963 can_vma_merge_after(prev, vm_flags,
964 anon_vma, file, pgoff,
965 vm_userfaultfd_ctx)) {
967 * OK, it can. Can we now merge in the successor as well?
969 if (next && end == next->vm_start &&
970 mpol_equal(policy, vma_policy(next)) &&
971 can_vma_merge_before(next, vm_flags,
974 vm_userfaultfd_ctx) &&
975 is_mergeable_anon_vma(prev->anon_vma,
976 next->anon_vma, NULL)) {
978 err = vma_adjust(prev, prev->vm_start,
979 next->vm_end, prev->vm_pgoff, NULL);
980 } else /* cases 2, 5, 7 */
981 err = vma_adjust(prev, prev->vm_start,
982 end, prev->vm_pgoff, NULL);
985 khugepaged_enter_vma_merge(prev, vm_flags);
990 * Can this new request be merged in front of next?
992 if (next && end == next->vm_start &&
993 mpol_equal(policy, vma_policy(next)) &&
994 can_vma_merge_before(next, vm_flags,
995 anon_vma, file, pgoff+pglen,
996 vm_userfaultfd_ctx)) {
997 if (prev && addr < prev->vm_end) /* case 4 */
998 err = vma_adjust(prev, prev->vm_start,
999 addr, prev->vm_pgoff, NULL);
1000 else /* cases 3, 8 */
1001 err = vma_adjust(area, addr, next->vm_end,
1002 next->vm_pgoff - pglen, NULL);
1005 khugepaged_enter_vma_merge(area, vm_flags);
1013 * Rough compatbility check to quickly see if it's even worth looking
1014 * at sharing an anon_vma.
1016 * They need to have the same vm_file, and the flags can only differ
1017 * in things that mprotect may change.
1019 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1020 * we can merge the two vma's. For example, we refuse to merge a vma if
1021 * there is a vm_ops->close() function, because that indicates that the
1022 * driver is doing some kind of reference counting. But that doesn't
1023 * really matter for the anon_vma sharing case.
1025 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1027 return a->vm_end == b->vm_start &&
1028 mpol_equal(vma_policy(a), vma_policy(b)) &&
1029 a->vm_file == b->vm_file &&
1030 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1031 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1035 * Do some basic sanity checking to see if we can re-use the anon_vma
1036 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1037 * the same as 'old', the other will be the new one that is trying
1038 * to share the anon_vma.
1040 * NOTE! This runs with mm_sem held for reading, so it is possible that
1041 * the anon_vma of 'old' is concurrently in the process of being set up
1042 * by another page fault trying to merge _that_. But that's ok: if it
1043 * is being set up, that automatically means that it will be a singleton
1044 * acceptable for merging, so we can do all of this optimistically. But
1045 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1047 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1048 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1049 * is to return an anon_vma that is "complex" due to having gone through
1052 * We also make sure that the two vma's are compatible (adjacent,
1053 * and with the same memory policies). That's all stable, even with just
1054 * a read lock on the mm_sem.
1056 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1058 if (anon_vma_compatible(a, b)) {
1059 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1061 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1068 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1069 * neighbouring vmas for a suitable anon_vma, before it goes off
1070 * to allocate a new anon_vma. It checks because a repetitive
1071 * sequence of mprotects and faults may otherwise lead to distinct
1072 * anon_vmas being allocated, preventing vma merge in subsequent
1075 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1077 struct anon_vma *anon_vma;
1078 struct vm_area_struct *near;
1080 near = vma->vm_next;
1084 anon_vma = reusable_anon_vma(near, vma, near);
1088 near = vma->vm_prev;
1092 anon_vma = reusable_anon_vma(near, near, vma);
1097 * There's no absolute need to look only at touching neighbours:
1098 * we could search further afield for "compatible" anon_vmas.
1099 * But it would probably just be a waste of time searching,
1100 * or lead to too many vmas hanging off the same anon_vma.
1101 * We're trying to allow mprotect remerging later on,
1102 * not trying to minimize memory used for anon_vmas.
1108 * If a hint addr is less than mmap_min_addr change hint to be as
1109 * low as possible but still greater than mmap_min_addr
1111 static inline unsigned long round_hint_to_min(unsigned long hint)
1114 if (((void *)hint != NULL) &&
1115 (hint < mmap_min_addr))
1116 return PAGE_ALIGN(mmap_min_addr);
1120 static inline int mlock_future_check(struct mm_struct *mm,
1121 unsigned long flags,
1124 unsigned long locked, lock_limit;
1126 /* mlock MCL_FUTURE? */
1127 if (flags & VM_LOCKED) {
1128 locked = len >> PAGE_SHIFT;
1129 locked += mm->locked_vm;
1130 lock_limit = rlimit(RLIMIT_MEMLOCK);
1131 lock_limit >>= PAGE_SHIFT;
1132 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1139 * The caller must hold down_write(¤t->mm->mmap_sem).
1141 unsigned long do_mmap(struct file *file, unsigned long addr,
1142 unsigned long len, unsigned long prot,
1143 unsigned long flags, vm_flags_t vm_flags,
1144 unsigned long pgoff, unsigned long *populate)
1146 struct mm_struct *mm = current->mm;
1155 * Does the application expect PROT_READ to imply PROT_EXEC?
1157 * (the exception is when the underlying filesystem is noexec
1158 * mounted, in which case we dont add PROT_EXEC.)
1160 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1161 if (!(file && path_noexec(&file->f_path)))
1164 if (!(flags & MAP_FIXED))
1165 addr = round_hint_to_min(addr);
1167 /* Careful about overflows.. */
1168 len = PAGE_ALIGN(len);
1172 /* offset overflow? */
1173 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1176 /* Too many mappings? */
1177 if (mm->map_count > sysctl_max_map_count)
1180 /* Obtain the address to map to. we verify (or select) it and ensure
1181 * that it represents a valid section of the address space.
1183 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1184 if (offset_in_page(addr))
1187 if (prot == PROT_EXEC) {
1188 pkey = execute_only_pkey(mm);
1193 /* Do simple checking here so the lower-level routines won't have
1194 * to. we assume access permissions have been handled by the open
1195 * of the memory object, so we don't do any here.
1197 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1198 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1200 if (flags & MAP_LOCKED)
1201 if (!can_do_mlock())
1204 if (mlock_future_check(mm, vm_flags, len))
1208 struct inode *inode = file_inode(file);
1210 switch (flags & MAP_TYPE) {
1212 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1216 * Make sure we don't allow writing to an append-only
1219 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1223 * Make sure there are no mandatory locks on the file.
1225 if (locks_verify_locked(file))
1228 vm_flags |= VM_SHARED | VM_MAYSHARE;
1229 if (!(file->f_mode & FMODE_WRITE))
1230 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1234 if (!(file->f_mode & FMODE_READ))
1236 if (path_noexec(&file->f_path)) {
1237 if (vm_flags & VM_EXEC)
1239 vm_flags &= ~VM_MAYEXEC;
1242 if (!file->f_op->mmap)
1244 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1252 switch (flags & MAP_TYPE) {
1254 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1260 vm_flags |= VM_SHARED | VM_MAYSHARE;
1264 * Set pgoff according to addr for anon_vma.
1266 pgoff = addr >> PAGE_SHIFT;
1274 * Set 'VM_NORESERVE' if we should not account for the
1275 * memory use of this mapping.
1277 if (flags & MAP_NORESERVE) {
1278 /* We honor MAP_NORESERVE if allowed to overcommit */
1279 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1280 vm_flags |= VM_NORESERVE;
1282 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1283 if (file && is_file_hugepages(file))
1284 vm_flags |= VM_NORESERVE;
1287 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1288 if (!IS_ERR_VALUE(addr) &&
1289 ((vm_flags & VM_LOCKED) ||
1290 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1295 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1296 unsigned long, prot, unsigned long, flags,
1297 unsigned long, fd, unsigned long, pgoff)
1299 struct file *file = NULL;
1300 unsigned long retval;
1302 if (!(flags & MAP_ANONYMOUS)) {
1303 audit_mmap_fd(fd, flags);
1307 if (is_file_hugepages(file))
1308 len = ALIGN(len, huge_page_size(hstate_file(file)));
1310 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1312 } else if (flags & MAP_HUGETLB) {
1313 struct user_struct *user = NULL;
1316 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1320 len = ALIGN(len, huge_page_size(hs));
1322 * VM_NORESERVE is used because the reservations will be
1323 * taken when vm_ops->mmap() is called
1324 * A dummy user value is used because we are not locking
1325 * memory so no accounting is necessary
1327 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1329 &user, HUGETLB_ANONHUGE_INODE,
1330 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1332 return PTR_ERR(file);
1335 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1337 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1344 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1345 struct mmap_arg_struct {
1349 unsigned long flags;
1351 unsigned long offset;
1354 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1356 struct mmap_arg_struct a;
1358 if (copy_from_user(&a, arg, sizeof(a)))
1360 if (offset_in_page(a.offset))
1363 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1364 a.offset >> PAGE_SHIFT);
1366 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1369 * Some shared mappigns will want the pages marked read-only
1370 * to track write events. If so, we'll downgrade vm_page_prot
1371 * to the private version (using protection_map[] without the
1374 int vma_wants_writenotify(struct vm_area_struct *vma)
1376 vm_flags_t vm_flags = vma->vm_flags;
1377 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1379 /* If it was private or non-writable, the write bit is already clear */
1380 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1383 /* The backer wishes to know when pages are first written to? */
1384 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1387 /* The open routine did something to the protections that pgprot_modify
1388 * won't preserve? */
1389 if (pgprot_val(vma->vm_page_prot) !=
1390 pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1393 /* Do we need to track softdirty? */
1394 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1397 /* Specialty mapping? */
1398 if (vm_flags & VM_PFNMAP)
1401 /* Can the mapping track the dirty pages? */
1402 return vma->vm_file && vma->vm_file->f_mapping &&
1403 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1407 * We account for memory if it's a private writeable mapping,
1408 * not hugepages and VM_NORESERVE wasn't set.
1410 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1413 * hugetlb has its own accounting separate from the core VM
1414 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1416 if (file && is_file_hugepages(file))
1419 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1422 unsigned long mmap_region(struct file *file, unsigned long addr,
1423 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1425 struct mm_struct *mm = current->mm;
1426 struct vm_area_struct *vma, *prev;
1428 struct rb_node **rb_link, *rb_parent;
1429 unsigned long charged = 0;
1431 /* Check against address space limit. */
1432 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1433 unsigned long nr_pages;
1436 * MAP_FIXED may remove pages of mappings that intersects with
1437 * requested mapping. Account for the pages it would unmap.
1439 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1441 if (!may_expand_vm(mm, vm_flags,
1442 (len >> PAGE_SHIFT) - nr_pages))
1446 /* Clear old maps */
1447 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1449 if (do_munmap(mm, addr, len))
1454 * Private writable mapping: check memory availability
1456 if (accountable_mapping(file, vm_flags)) {
1457 charged = len >> PAGE_SHIFT;
1458 if (security_vm_enough_memory_mm(mm, charged))
1460 vm_flags |= VM_ACCOUNT;
1464 * Can we just expand an old mapping?
1466 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1467 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1472 * Determine the object being mapped and call the appropriate
1473 * specific mapper. the address has already been validated, but
1474 * not unmapped, but the maps are removed from the list.
1476 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1483 vma->vm_start = addr;
1484 vma->vm_end = addr + len;
1485 vma->vm_flags = vm_flags;
1486 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1487 vma->vm_pgoff = pgoff;
1488 INIT_LIST_HEAD(&vma->anon_vma_chain);
1491 if (vm_flags & VM_DENYWRITE) {
1492 error = deny_write_access(file);
1496 if (vm_flags & VM_SHARED) {
1497 error = mapping_map_writable(file->f_mapping);
1499 goto allow_write_and_free_vma;
1502 /* ->mmap() can change vma->vm_file, but must guarantee that
1503 * vma_link() below can deny write-access if VM_DENYWRITE is set
1504 * and map writably if VM_SHARED is set. This usually means the
1505 * new file must not have been exposed to user-space, yet.
1507 vma->vm_file = get_file(file);
1508 error = file->f_op->mmap(file, vma);
1510 goto unmap_and_free_vma;
1512 /* Can addr have changed??
1514 * Answer: Yes, several device drivers can do it in their
1515 * f_op->mmap method. -DaveM
1516 * Bug: If addr is changed, prev, rb_link, rb_parent should
1517 * be updated for vma_link()
1519 WARN_ON_ONCE(addr != vma->vm_start);
1521 addr = vma->vm_start;
1522 vm_flags = vma->vm_flags;
1523 } else if (vm_flags & VM_SHARED) {
1524 error = shmem_zero_setup(vma);
1529 vma_link(mm, vma, prev, rb_link, rb_parent);
1530 /* Once vma denies write, undo our temporary denial count */
1532 if (vm_flags & VM_SHARED)
1533 mapping_unmap_writable(file->f_mapping);
1534 if (vm_flags & VM_DENYWRITE)
1535 allow_write_access(file);
1537 file = vma->vm_file;
1539 perf_event_mmap(vma);
1541 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1542 if (vm_flags & VM_LOCKED) {
1543 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1544 vma == get_gate_vma(current->mm)))
1545 mm->locked_vm += (len >> PAGE_SHIFT);
1547 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1554 * New (or expanded) vma always get soft dirty status.
1555 * Otherwise user-space soft-dirty page tracker won't
1556 * be able to distinguish situation when vma area unmapped,
1557 * then new mapped in-place (which must be aimed as
1558 * a completely new data area).
1560 vma->vm_flags |= VM_SOFTDIRTY;
1562 vma_set_page_prot(vma);
1567 vma->vm_file = NULL;
1570 /* Undo any partial mapping done by a device driver. */
1571 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1573 if (vm_flags & VM_SHARED)
1574 mapping_unmap_writable(file->f_mapping);
1575 allow_write_and_free_vma:
1576 if (vm_flags & VM_DENYWRITE)
1577 allow_write_access(file);
1579 kmem_cache_free(vm_area_cachep, vma);
1582 vm_unacct_memory(charged);
1586 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1589 * We implement the search by looking for an rbtree node that
1590 * immediately follows a suitable gap. That is,
1591 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1592 * - gap_end = vma->vm_start >= info->low_limit + length;
1593 * - gap_end - gap_start >= length
1596 struct mm_struct *mm = current->mm;
1597 struct vm_area_struct *vma;
1598 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1600 /* Adjust search length to account for worst case alignment overhead */
1601 length = info->length + info->align_mask;
1602 if (length < info->length)
1605 /* Adjust search limits by the desired length */
1606 if (info->high_limit < length)
1608 high_limit = info->high_limit - length;
1610 if (info->low_limit > high_limit)
1612 low_limit = info->low_limit + length;
1614 /* Check if rbtree root looks promising */
1615 if (RB_EMPTY_ROOT(&mm->mm_rb))
1617 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1618 if (vma->rb_subtree_gap < length)
1622 /* Visit left subtree if it looks promising */
1623 gap_end = vma->vm_start;
1624 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1625 struct vm_area_struct *left =
1626 rb_entry(vma->vm_rb.rb_left,
1627 struct vm_area_struct, vm_rb);
1628 if (left->rb_subtree_gap >= length) {
1634 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1636 /* Check if current node has a suitable gap */
1637 if (gap_start > high_limit)
1639 if (gap_end >= low_limit && gap_end - gap_start >= length)
1642 /* Visit right subtree if it looks promising */
1643 if (vma->vm_rb.rb_right) {
1644 struct vm_area_struct *right =
1645 rb_entry(vma->vm_rb.rb_right,
1646 struct vm_area_struct, vm_rb);
1647 if (right->rb_subtree_gap >= length) {
1653 /* Go back up the rbtree to find next candidate node */
1655 struct rb_node *prev = &vma->vm_rb;
1656 if (!rb_parent(prev))
1658 vma = rb_entry(rb_parent(prev),
1659 struct vm_area_struct, vm_rb);
1660 if (prev == vma->vm_rb.rb_left) {
1661 gap_start = vma->vm_prev->vm_end;
1662 gap_end = vma->vm_start;
1669 /* Check highest gap, which does not precede any rbtree node */
1670 gap_start = mm->highest_vm_end;
1671 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1672 if (gap_start > high_limit)
1676 /* We found a suitable gap. Clip it with the original low_limit. */
1677 if (gap_start < info->low_limit)
1678 gap_start = info->low_limit;
1680 /* Adjust gap address to the desired alignment */
1681 gap_start += (info->align_offset - gap_start) & info->align_mask;
1683 VM_BUG_ON(gap_start + info->length > info->high_limit);
1684 VM_BUG_ON(gap_start + info->length > gap_end);
1688 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1690 struct mm_struct *mm = current->mm;
1691 struct vm_area_struct *vma;
1692 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1694 /* Adjust search length to account for worst case alignment overhead */
1695 length = info->length + info->align_mask;
1696 if (length < info->length)
1700 * Adjust search limits by the desired length.
1701 * See implementation comment at top of unmapped_area().
1703 gap_end = info->high_limit;
1704 if (gap_end < length)
1706 high_limit = gap_end - length;
1708 if (info->low_limit > high_limit)
1710 low_limit = info->low_limit + length;
1712 /* Check highest gap, which does not precede any rbtree node */
1713 gap_start = mm->highest_vm_end;
1714 if (gap_start <= high_limit)
1717 /* Check if rbtree root looks promising */
1718 if (RB_EMPTY_ROOT(&mm->mm_rb))
1720 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1721 if (vma->rb_subtree_gap < length)
1725 /* Visit right subtree if it looks promising */
1726 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1727 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1728 struct vm_area_struct *right =
1729 rb_entry(vma->vm_rb.rb_right,
1730 struct vm_area_struct, vm_rb);
1731 if (right->rb_subtree_gap >= length) {
1738 /* Check if current node has a suitable gap */
1739 gap_end = vma->vm_start;
1740 if (gap_end < low_limit)
1742 if (gap_start <= high_limit && gap_end - gap_start >= length)
1745 /* Visit left subtree if it looks promising */
1746 if (vma->vm_rb.rb_left) {
1747 struct vm_area_struct *left =
1748 rb_entry(vma->vm_rb.rb_left,
1749 struct vm_area_struct, vm_rb);
1750 if (left->rb_subtree_gap >= length) {
1756 /* Go back up the rbtree to find next candidate node */
1758 struct rb_node *prev = &vma->vm_rb;
1759 if (!rb_parent(prev))
1761 vma = rb_entry(rb_parent(prev),
1762 struct vm_area_struct, vm_rb);
1763 if (prev == vma->vm_rb.rb_right) {
1764 gap_start = vma->vm_prev ?
1765 vma->vm_prev->vm_end : 0;
1772 /* We found a suitable gap. Clip it with the original high_limit. */
1773 if (gap_end > info->high_limit)
1774 gap_end = info->high_limit;
1777 /* Compute highest gap address at the desired alignment */
1778 gap_end -= info->length;
1779 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1781 VM_BUG_ON(gap_end < info->low_limit);
1782 VM_BUG_ON(gap_end < gap_start);
1786 /* Get an address range which is currently unmapped.
1787 * For shmat() with addr=0.
1789 * Ugly calling convention alert:
1790 * Return value with the low bits set means error value,
1792 * if (ret & ~PAGE_MASK)
1795 * This function "knows" that -ENOMEM has the bits set.
1797 #ifndef HAVE_ARCH_UNMAPPED_AREA
1799 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1800 unsigned long len, unsigned long pgoff, unsigned long flags)
1802 struct mm_struct *mm = current->mm;
1803 struct vm_area_struct *vma;
1804 struct vm_unmapped_area_info info;
1806 if (len > TASK_SIZE - mmap_min_addr)
1809 if (flags & MAP_FIXED)
1813 addr = PAGE_ALIGN(addr);
1814 vma = find_vma(mm, addr);
1815 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1816 (!vma || addr + len <= vma->vm_start))
1822 info.low_limit = mm->mmap_base;
1823 info.high_limit = TASK_SIZE;
1824 info.align_mask = 0;
1825 return vm_unmapped_area(&info);
1830 * This mmap-allocator allocates new areas top-down from below the
1831 * stack's low limit (the base):
1833 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1835 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1836 const unsigned long len, const unsigned long pgoff,
1837 const unsigned long flags)
1839 struct vm_area_struct *vma;
1840 struct mm_struct *mm = current->mm;
1841 unsigned long addr = addr0;
1842 struct vm_unmapped_area_info info;
1844 /* requested length too big for entire address space */
1845 if (len > TASK_SIZE - mmap_min_addr)
1848 if (flags & MAP_FIXED)
1851 /* requesting a specific address */
1853 addr = PAGE_ALIGN(addr);
1854 vma = find_vma(mm, addr);
1855 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1856 (!vma || addr + len <= vma->vm_start))
1860 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1862 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1863 info.high_limit = mm->mmap_base;
1864 info.align_mask = 0;
1865 addr = vm_unmapped_area(&info);
1868 * A failed mmap() very likely causes application failure,
1869 * so fall back to the bottom-up function here. This scenario
1870 * can happen with large stack limits and large mmap()
1873 if (offset_in_page(addr)) {
1874 VM_BUG_ON(addr != -ENOMEM);
1876 info.low_limit = TASK_UNMAPPED_BASE;
1877 info.high_limit = TASK_SIZE;
1878 addr = vm_unmapped_area(&info);
1886 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1887 unsigned long pgoff, unsigned long flags)
1889 unsigned long (*get_area)(struct file *, unsigned long,
1890 unsigned long, unsigned long, unsigned long);
1892 unsigned long error = arch_mmap_check(addr, len, flags);
1896 /* Careful about overflows.. */
1897 if (len > TASK_SIZE)
1900 get_area = current->mm->get_unmapped_area;
1902 if (file->f_op->get_unmapped_area)
1903 get_area = file->f_op->get_unmapped_area;
1904 } else if (flags & MAP_SHARED) {
1906 * mmap_region() will call shmem_zero_setup() to create a file,
1907 * so use shmem's get_unmapped_area in case it can be huge.
1908 * do_mmap_pgoff() will clear pgoff, so match alignment.
1911 get_area = shmem_get_unmapped_area;
1914 addr = get_area(file, addr, len, pgoff, flags);
1915 if (IS_ERR_VALUE(addr))
1918 if (addr > TASK_SIZE - len)
1920 if (offset_in_page(addr))
1923 error = security_mmap_addr(addr);
1924 return error ? error : addr;
1927 EXPORT_SYMBOL(get_unmapped_area);
1929 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1930 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1932 struct rb_node *rb_node;
1933 struct vm_area_struct *vma;
1935 /* Check the cache first. */
1936 vma = vmacache_find(mm, addr);
1940 rb_node = mm->mm_rb.rb_node;
1943 struct vm_area_struct *tmp;
1945 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1947 if (tmp->vm_end > addr) {
1949 if (tmp->vm_start <= addr)
1951 rb_node = rb_node->rb_left;
1953 rb_node = rb_node->rb_right;
1957 vmacache_update(addr, vma);
1961 EXPORT_SYMBOL(find_vma);
1964 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1966 struct vm_area_struct *
1967 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1968 struct vm_area_struct **pprev)
1970 struct vm_area_struct *vma;
1972 vma = find_vma(mm, addr);
1974 *pprev = vma->vm_prev;
1976 struct rb_node *rb_node = mm->mm_rb.rb_node;
1979 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1980 rb_node = rb_node->rb_right;
1987 * Verify that the stack growth is acceptable and
1988 * update accounting. This is shared with both the
1989 * grow-up and grow-down cases.
1991 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1993 struct mm_struct *mm = vma->vm_mm;
1994 struct rlimit *rlim = current->signal->rlim;
1995 unsigned long new_start, actual_size;
1997 /* address space limit tests */
1998 if (!may_expand_vm(mm, vma->vm_flags, grow))
2001 /* Stack limit test */
2003 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2004 actual_size -= PAGE_SIZE;
2005 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2008 /* mlock limit tests */
2009 if (vma->vm_flags & VM_LOCKED) {
2010 unsigned long locked;
2011 unsigned long limit;
2012 locked = mm->locked_vm + grow;
2013 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2014 limit >>= PAGE_SHIFT;
2015 if (locked > limit && !capable(CAP_IPC_LOCK))
2019 /* Check to ensure the stack will not grow into a hugetlb-only region */
2020 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2022 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2026 * Overcommit.. This must be the final test, as it will
2027 * update security statistics.
2029 if (security_vm_enough_memory_mm(mm, grow))
2035 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2037 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2038 * vma is the last one with address > vma->vm_end. Have to extend vma.
2040 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2042 struct mm_struct *mm = vma->vm_mm;
2045 if (!(vma->vm_flags & VM_GROWSUP))
2048 /* Guard against wrapping around to address 0. */
2049 if (address < PAGE_ALIGN(address+4))
2050 address = PAGE_ALIGN(address+4);
2054 /* We must make sure the anon_vma is allocated. */
2055 if (unlikely(anon_vma_prepare(vma)))
2059 * vma->vm_start/vm_end cannot change under us because the caller
2060 * is required to hold the mmap_sem in read mode. We need the
2061 * anon_vma lock to serialize against concurrent expand_stacks.
2063 anon_vma_lock_write(vma->anon_vma);
2065 /* Somebody else might have raced and expanded it already */
2066 if (address > vma->vm_end) {
2067 unsigned long size, grow;
2069 size = address - vma->vm_start;
2070 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2073 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2074 error = acct_stack_growth(vma, size, grow);
2077 * vma_gap_update() doesn't support concurrent
2078 * updates, but we only hold a shared mmap_sem
2079 * lock here, so we need to protect against
2080 * concurrent vma expansions.
2081 * anon_vma_lock_write() doesn't help here, as
2082 * we don't guarantee that all growable vmas
2083 * in a mm share the same root anon vma.
2084 * So, we reuse mm->page_table_lock to guard
2085 * against concurrent vma expansions.
2087 spin_lock(&mm->page_table_lock);
2088 if (vma->vm_flags & VM_LOCKED)
2089 mm->locked_vm += grow;
2090 vm_stat_account(mm, vma->vm_flags, grow);
2091 anon_vma_interval_tree_pre_update_vma(vma);
2092 vma->vm_end = address;
2093 anon_vma_interval_tree_post_update_vma(vma);
2095 vma_gap_update(vma->vm_next);
2097 mm->highest_vm_end = address;
2098 spin_unlock(&mm->page_table_lock);
2100 perf_event_mmap(vma);
2104 anon_vma_unlock_write(vma->anon_vma);
2105 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2109 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2112 * vma is the first one with address < vma->vm_start. Have to extend vma.
2114 int expand_downwards(struct vm_area_struct *vma,
2115 unsigned long address)
2117 struct mm_struct *mm = vma->vm_mm;
2120 address &= PAGE_MASK;
2121 error = security_mmap_addr(address);
2125 /* We must make sure the anon_vma is allocated. */
2126 if (unlikely(anon_vma_prepare(vma)))
2130 * vma->vm_start/vm_end cannot change under us because the caller
2131 * is required to hold the mmap_sem in read mode. We need the
2132 * anon_vma lock to serialize against concurrent expand_stacks.
2134 anon_vma_lock_write(vma->anon_vma);
2136 /* Somebody else might have raced and expanded it already */
2137 if (address < vma->vm_start) {
2138 unsigned long size, grow;
2140 size = vma->vm_end - address;
2141 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2144 if (grow <= vma->vm_pgoff) {
2145 error = acct_stack_growth(vma, size, grow);
2148 * vma_gap_update() doesn't support concurrent
2149 * updates, but we only hold a shared mmap_sem
2150 * lock here, so we need to protect against
2151 * concurrent vma expansions.
2152 * anon_vma_lock_write() doesn't help here, as
2153 * we don't guarantee that all growable vmas
2154 * in a mm share the same root anon vma.
2155 * So, we reuse mm->page_table_lock to guard
2156 * against concurrent vma expansions.
2158 spin_lock(&mm->page_table_lock);
2159 if (vma->vm_flags & VM_LOCKED)
2160 mm->locked_vm += grow;
2161 vm_stat_account(mm, vma->vm_flags, grow);
2162 anon_vma_interval_tree_pre_update_vma(vma);
2163 vma->vm_start = address;
2164 vma->vm_pgoff -= grow;
2165 anon_vma_interval_tree_post_update_vma(vma);
2166 vma_gap_update(vma);
2167 spin_unlock(&mm->page_table_lock);
2169 perf_event_mmap(vma);
2173 anon_vma_unlock_write(vma->anon_vma);
2174 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2180 * Note how expand_stack() refuses to expand the stack all the way to
2181 * abut the next virtual mapping, *unless* that mapping itself is also
2182 * a stack mapping. We want to leave room for a guard page, after all
2183 * (the guard page itself is not added here, that is done by the
2184 * actual page faulting logic)
2186 * This matches the behavior of the guard page logic (see mm/memory.c:
2187 * check_stack_guard_page()), which only allows the guard page to be
2188 * removed under these circumstances.
2190 #ifdef CONFIG_STACK_GROWSUP
2191 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2193 struct vm_area_struct *next;
2195 address &= PAGE_MASK;
2196 next = vma->vm_next;
2197 if (next && next->vm_start == address + PAGE_SIZE) {
2198 if (!(next->vm_flags & VM_GROWSUP))
2201 return expand_upwards(vma, address);
2204 struct vm_area_struct *
2205 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2207 struct vm_area_struct *vma, *prev;
2210 vma = find_vma_prev(mm, addr, &prev);
2211 if (vma && (vma->vm_start <= addr))
2213 if (!prev || expand_stack(prev, addr))
2215 if (prev->vm_flags & VM_LOCKED)
2216 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2220 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2222 struct vm_area_struct *prev;
2224 address &= PAGE_MASK;
2225 prev = vma->vm_prev;
2226 if (prev && prev->vm_end == address) {
2227 if (!(prev->vm_flags & VM_GROWSDOWN))
2230 return expand_downwards(vma, address);
2233 struct vm_area_struct *
2234 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2236 struct vm_area_struct *vma;
2237 unsigned long start;
2240 vma = find_vma(mm, addr);
2243 if (vma->vm_start <= addr)
2245 if (!(vma->vm_flags & VM_GROWSDOWN))
2247 start = vma->vm_start;
2248 if (expand_stack(vma, addr))
2250 if (vma->vm_flags & VM_LOCKED)
2251 populate_vma_page_range(vma, addr, start, NULL);
2256 EXPORT_SYMBOL_GPL(find_extend_vma);
2259 * Ok - we have the memory areas we should free on the vma list,
2260 * so release them, and do the vma updates.
2262 * Called with the mm semaphore held.
2264 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2266 unsigned long nr_accounted = 0;
2268 /* Update high watermark before we lower total_vm */
2269 update_hiwater_vm(mm);
2271 long nrpages = vma_pages(vma);
2273 if (vma->vm_flags & VM_ACCOUNT)
2274 nr_accounted += nrpages;
2275 vm_stat_account(mm, vma->vm_flags, -nrpages);
2276 vma = remove_vma(vma);
2278 vm_unacct_memory(nr_accounted);
2283 * Get rid of page table information in the indicated region.
2285 * Called with the mm semaphore held.
2287 static void unmap_region(struct mm_struct *mm,
2288 struct vm_area_struct *vma, struct vm_area_struct *prev,
2289 unsigned long start, unsigned long end)
2291 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2292 struct mmu_gather tlb;
2295 tlb_gather_mmu(&tlb, mm, start, end);
2296 update_hiwater_rss(mm);
2297 unmap_vmas(&tlb, vma, start, end);
2298 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2299 next ? next->vm_start : USER_PGTABLES_CEILING);
2300 tlb_finish_mmu(&tlb, start, end);
2304 * Create a list of vma's touched by the unmap, removing them from the mm's
2305 * vma list as we go..
2308 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2309 struct vm_area_struct *prev, unsigned long end)
2311 struct vm_area_struct **insertion_point;
2312 struct vm_area_struct *tail_vma = NULL;
2314 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2315 vma->vm_prev = NULL;
2317 vma_rb_erase(vma, &mm->mm_rb);
2321 } while (vma && vma->vm_start < end);
2322 *insertion_point = vma;
2324 vma->vm_prev = prev;
2325 vma_gap_update(vma);
2327 mm->highest_vm_end = prev ? prev->vm_end : 0;
2328 tail_vma->vm_next = NULL;
2330 /* Kill the cache */
2331 vmacache_invalidate(mm);
2335 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2336 * munmap path where it doesn't make sense to fail.
2338 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2339 unsigned long addr, int new_below)
2341 struct vm_area_struct *new;
2344 if (is_vm_hugetlb_page(vma) && (addr &
2345 ~(huge_page_mask(hstate_vma(vma)))))
2348 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2352 /* most fields are the same, copy all, and then fixup */
2355 INIT_LIST_HEAD(&new->anon_vma_chain);
2360 new->vm_start = addr;
2361 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2364 err = vma_dup_policy(vma, new);
2368 err = anon_vma_clone(new, vma);
2373 get_file(new->vm_file);
2375 if (new->vm_ops && new->vm_ops->open)
2376 new->vm_ops->open(new);
2379 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2380 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2382 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2388 /* Clean everything up if vma_adjust failed. */
2389 if (new->vm_ops && new->vm_ops->close)
2390 new->vm_ops->close(new);
2393 unlink_anon_vmas(new);
2395 mpol_put(vma_policy(new));
2397 kmem_cache_free(vm_area_cachep, new);
2402 * Split a vma into two pieces at address 'addr', a new vma is allocated
2403 * either for the first part or the tail.
2405 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2406 unsigned long addr, int new_below)
2408 if (mm->map_count >= sysctl_max_map_count)
2411 return __split_vma(mm, vma, addr, new_below);
2414 /* Munmap is split into 2 main parts -- this part which finds
2415 * what needs doing, and the areas themselves, which do the
2416 * work. This now handles partial unmappings.
2417 * Jeremy Fitzhardinge <jeremy@goop.org>
2419 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2422 struct vm_area_struct *vma, *prev, *last;
2424 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2427 len = PAGE_ALIGN(len);
2431 /* Find the first overlapping VMA */
2432 vma = find_vma(mm, start);
2435 prev = vma->vm_prev;
2436 /* we have start < vma->vm_end */
2438 /* if it doesn't overlap, we have nothing.. */
2440 if (vma->vm_start >= end)
2444 * If we need to split any vma, do it now to save pain later.
2446 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2447 * unmapped vm_area_struct will remain in use: so lower split_vma
2448 * places tmp vma above, and higher split_vma places tmp vma below.
2450 if (start > vma->vm_start) {
2454 * Make sure that map_count on return from munmap() will
2455 * not exceed its limit; but let map_count go just above
2456 * its limit temporarily, to help free resources as expected.
2458 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2461 error = __split_vma(mm, vma, start, 0);
2467 /* Does it split the last one? */
2468 last = find_vma(mm, end);
2469 if (last && end > last->vm_start) {
2470 int error = __split_vma(mm, last, end, 1);
2474 vma = prev ? prev->vm_next : mm->mmap;
2477 * unlock any mlock()ed ranges before detaching vmas
2479 if (mm->locked_vm) {
2480 struct vm_area_struct *tmp = vma;
2481 while (tmp && tmp->vm_start < end) {
2482 if (tmp->vm_flags & VM_LOCKED) {
2483 mm->locked_vm -= vma_pages(tmp);
2484 munlock_vma_pages_all(tmp);
2491 * Remove the vma's, and unmap the actual pages
2493 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2494 unmap_region(mm, vma, prev, start, end);
2496 arch_unmap(mm, vma, start, end);
2498 /* Fix up all other VM information */
2499 remove_vma_list(mm, vma);
2504 int vm_munmap(unsigned long start, size_t len)
2507 struct mm_struct *mm = current->mm;
2509 if (down_write_killable(&mm->mmap_sem))
2512 ret = do_munmap(mm, start, len);
2513 up_write(&mm->mmap_sem);
2516 EXPORT_SYMBOL(vm_munmap);
2518 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2521 struct mm_struct *mm = current->mm;
2523 profile_munmap(addr);
2524 if (down_write_killable(&mm->mmap_sem))
2526 ret = do_munmap(mm, addr, len);
2527 up_write(&mm->mmap_sem);
2533 * Emulation of deprecated remap_file_pages() syscall.
2535 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2536 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2539 struct mm_struct *mm = current->mm;
2540 struct vm_area_struct *vma;
2541 unsigned long populate = 0;
2542 unsigned long ret = -EINVAL;
2545 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2546 current->comm, current->pid);
2550 start = start & PAGE_MASK;
2551 size = size & PAGE_MASK;
2553 if (start + size <= start)
2556 /* Does pgoff wrap? */
2557 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2560 if (down_write_killable(&mm->mmap_sem))
2563 vma = find_vma(mm, start);
2565 if (!vma || !(vma->vm_flags & VM_SHARED))
2568 if (start < vma->vm_start)
2571 if (start + size > vma->vm_end) {
2572 struct vm_area_struct *next;
2574 for (next = vma->vm_next; next; next = next->vm_next) {
2575 /* hole between vmas ? */
2576 if (next->vm_start != next->vm_prev->vm_end)
2579 if (next->vm_file != vma->vm_file)
2582 if (next->vm_flags != vma->vm_flags)
2585 if (start + size <= next->vm_end)
2593 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2594 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2595 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2597 flags &= MAP_NONBLOCK;
2598 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2599 if (vma->vm_flags & VM_LOCKED) {
2600 struct vm_area_struct *tmp;
2601 flags |= MAP_LOCKED;
2603 /* drop PG_Mlocked flag for over-mapped range */
2604 for (tmp = vma; tmp->vm_start >= start + size;
2605 tmp = tmp->vm_next) {
2607 * Split pmd and munlock page on the border
2610 vma_adjust_trans_huge(tmp, start, start + size, 0);
2612 munlock_vma_pages_range(tmp,
2613 max(tmp->vm_start, start),
2614 min(tmp->vm_end, start + size));
2618 file = get_file(vma->vm_file);
2619 ret = do_mmap_pgoff(vma->vm_file, start, size,
2620 prot, flags, pgoff, &populate);
2623 up_write(&mm->mmap_sem);
2625 mm_populate(ret, populate);
2626 if (!IS_ERR_VALUE(ret))
2631 static inline void verify_mm_writelocked(struct mm_struct *mm)
2633 #ifdef CONFIG_DEBUG_VM
2634 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2636 up_read(&mm->mmap_sem);
2642 * this is really a simplified "do_mmap". it only handles
2643 * anonymous maps. eventually we may be able to do some
2644 * brk-specific accounting here.
2646 static int do_brk(unsigned long addr, unsigned long len)
2648 struct mm_struct *mm = current->mm;
2649 struct vm_area_struct *vma, *prev;
2650 unsigned long flags;
2651 struct rb_node **rb_link, *rb_parent;
2652 pgoff_t pgoff = addr >> PAGE_SHIFT;
2655 len = PAGE_ALIGN(len);
2659 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2661 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2662 if (offset_in_page(error))
2665 error = mlock_future_check(mm, mm->def_flags, len);
2670 * mm->mmap_sem is required to protect against another thread
2671 * changing the mappings in case we sleep.
2673 verify_mm_writelocked(mm);
2676 * Clear old maps. this also does some error checking for us
2678 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2680 if (do_munmap(mm, addr, len))
2684 /* Check against address space limits *after* clearing old maps... */
2685 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2688 if (mm->map_count > sysctl_max_map_count)
2691 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2694 /* Can we just expand an old private anonymous mapping? */
2695 vma = vma_merge(mm, prev, addr, addr + len, flags,
2696 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2701 * create a vma struct for an anonymous mapping
2703 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2705 vm_unacct_memory(len >> PAGE_SHIFT);
2709 INIT_LIST_HEAD(&vma->anon_vma_chain);
2711 vma->vm_start = addr;
2712 vma->vm_end = addr + len;
2713 vma->vm_pgoff = pgoff;
2714 vma->vm_flags = flags;
2715 vma->vm_page_prot = vm_get_page_prot(flags);
2716 vma_link(mm, vma, prev, rb_link, rb_parent);
2718 perf_event_mmap(vma);
2719 mm->total_vm += len >> PAGE_SHIFT;
2720 mm->data_vm += len >> PAGE_SHIFT;
2721 if (flags & VM_LOCKED)
2722 mm->locked_vm += (len >> PAGE_SHIFT);
2723 vma->vm_flags |= VM_SOFTDIRTY;
2727 int vm_brk(unsigned long addr, unsigned long len)
2729 struct mm_struct *mm = current->mm;
2733 if (down_write_killable(&mm->mmap_sem))
2736 ret = do_brk(addr, len);
2737 populate = ((mm->def_flags & VM_LOCKED) != 0);
2738 up_write(&mm->mmap_sem);
2739 if (populate && !ret)
2740 mm_populate(addr, len);
2743 EXPORT_SYMBOL(vm_brk);
2745 /* Release all mmaps. */
2746 void exit_mmap(struct mm_struct *mm)
2748 struct mmu_gather tlb;
2749 struct vm_area_struct *vma;
2750 unsigned long nr_accounted = 0;
2752 /* mm's last user has gone, and its about to be pulled down */
2753 mmu_notifier_release(mm);
2755 if (mm->locked_vm) {
2758 if (vma->vm_flags & VM_LOCKED)
2759 munlock_vma_pages_all(vma);
2767 if (!vma) /* Can happen if dup_mmap() received an OOM */
2772 tlb_gather_mmu(&tlb, mm, 0, -1);
2773 /* update_hiwater_rss(mm) here? but nobody should be looking */
2774 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2775 unmap_vmas(&tlb, vma, 0, -1);
2777 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2778 tlb_finish_mmu(&tlb, 0, -1);
2781 * Walk the list again, actually closing and freeing it,
2782 * with preemption enabled, without holding any MM locks.
2785 if (vma->vm_flags & VM_ACCOUNT)
2786 nr_accounted += vma_pages(vma);
2787 vma = remove_vma(vma);
2789 vm_unacct_memory(nr_accounted);
2792 /* Insert vm structure into process list sorted by address
2793 * and into the inode's i_mmap tree. If vm_file is non-NULL
2794 * then i_mmap_rwsem is taken here.
2796 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2798 struct vm_area_struct *prev;
2799 struct rb_node **rb_link, *rb_parent;
2801 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2802 &prev, &rb_link, &rb_parent))
2804 if ((vma->vm_flags & VM_ACCOUNT) &&
2805 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2809 * The vm_pgoff of a purely anonymous vma should be irrelevant
2810 * until its first write fault, when page's anon_vma and index
2811 * are set. But now set the vm_pgoff it will almost certainly
2812 * end up with (unless mremap moves it elsewhere before that
2813 * first wfault), so /proc/pid/maps tells a consistent story.
2815 * By setting it to reflect the virtual start address of the
2816 * vma, merges and splits can happen in a seamless way, just
2817 * using the existing file pgoff checks and manipulations.
2818 * Similarly in do_mmap_pgoff and in do_brk.
2820 if (vma_is_anonymous(vma)) {
2821 BUG_ON(vma->anon_vma);
2822 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2825 vma_link(mm, vma, prev, rb_link, rb_parent);
2830 * Copy the vma structure to a new location in the same mm,
2831 * prior to moving page table entries, to effect an mremap move.
2833 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2834 unsigned long addr, unsigned long len, pgoff_t pgoff,
2835 bool *need_rmap_locks)
2837 struct vm_area_struct *vma = *vmap;
2838 unsigned long vma_start = vma->vm_start;
2839 struct mm_struct *mm = vma->vm_mm;
2840 struct vm_area_struct *new_vma, *prev;
2841 struct rb_node **rb_link, *rb_parent;
2842 bool faulted_in_anon_vma = true;
2845 * If anonymous vma has not yet been faulted, update new pgoff
2846 * to match new location, to increase its chance of merging.
2848 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
2849 pgoff = addr >> PAGE_SHIFT;
2850 faulted_in_anon_vma = false;
2853 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2854 return NULL; /* should never get here */
2855 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2856 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
2857 vma->vm_userfaultfd_ctx);
2860 * Source vma may have been merged into new_vma
2862 if (unlikely(vma_start >= new_vma->vm_start &&
2863 vma_start < new_vma->vm_end)) {
2865 * The only way we can get a vma_merge with
2866 * self during an mremap is if the vma hasn't
2867 * been faulted in yet and we were allowed to
2868 * reset the dst vma->vm_pgoff to the
2869 * destination address of the mremap to allow
2870 * the merge to happen. mremap must change the
2871 * vm_pgoff linearity between src and dst vmas
2872 * (in turn preventing a vma_merge) to be
2873 * safe. It is only safe to keep the vm_pgoff
2874 * linear if there are no pages mapped yet.
2876 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2877 *vmap = vma = new_vma;
2879 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2881 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2885 new_vma->vm_start = addr;
2886 new_vma->vm_end = addr + len;
2887 new_vma->vm_pgoff = pgoff;
2888 if (vma_dup_policy(vma, new_vma))
2890 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2891 if (anon_vma_clone(new_vma, vma))
2892 goto out_free_mempol;
2893 if (new_vma->vm_file)
2894 get_file(new_vma->vm_file);
2895 if (new_vma->vm_ops && new_vma->vm_ops->open)
2896 new_vma->vm_ops->open(new_vma);
2897 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2898 *need_rmap_locks = false;
2903 mpol_put(vma_policy(new_vma));
2905 kmem_cache_free(vm_area_cachep, new_vma);
2911 * Return true if the calling process may expand its vm space by the passed
2914 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
2916 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
2919 if (is_data_mapping(flags) &&
2920 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
2921 /* Workaround for Valgrind */
2922 if (rlimit(RLIMIT_DATA) == 0 &&
2923 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
2925 if (!ignore_rlimit_data) {
2926 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
2927 current->comm, current->pid,
2928 (mm->data_vm + npages) << PAGE_SHIFT,
2929 rlimit(RLIMIT_DATA));
2937 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
2939 mm->total_vm += npages;
2941 if (is_exec_mapping(flags))
2942 mm->exec_vm += npages;
2943 else if (is_stack_mapping(flags))
2944 mm->stack_vm += npages;
2945 else if (is_data_mapping(flags))
2946 mm->data_vm += npages;
2949 static int special_mapping_fault(struct vm_area_struct *vma,
2950 struct vm_fault *vmf);
2953 * Having a close hook prevents vma merging regardless of flags.
2955 static void special_mapping_close(struct vm_area_struct *vma)
2959 static const char *special_mapping_name(struct vm_area_struct *vma)
2961 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
2964 static int special_mapping_mremap(struct vm_area_struct *new_vma)
2966 struct vm_special_mapping *sm = new_vma->vm_private_data;
2969 return sm->mremap(sm, new_vma);
2973 static const struct vm_operations_struct special_mapping_vmops = {
2974 .close = special_mapping_close,
2975 .fault = special_mapping_fault,
2976 .mremap = special_mapping_mremap,
2977 .name = special_mapping_name,
2980 static const struct vm_operations_struct legacy_special_mapping_vmops = {
2981 .close = special_mapping_close,
2982 .fault = special_mapping_fault,
2985 static int special_mapping_fault(struct vm_area_struct *vma,
2986 struct vm_fault *vmf)
2989 struct page **pages;
2991 if (vma->vm_ops == &legacy_special_mapping_vmops) {
2992 pages = vma->vm_private_data;
2994 struct vm_special_mapping *sm = vma->vm_private_data;
2997 return sm->fault(sm, vma, vmf);
3002 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3006 struct page *page = *pages;
3012 return VM_FAULT_SIGBUS;
3015 static struct vm_area_struct *__install_special_mapping(
3016 struct mm_struct *mm,
3017 unsigned long addr, unsigned long len,
3018 unsigned long vm_flags, void *priv,
3019 const struct vm_operations_struct *ops)
3022 struct vm_area_struct *vma;
3024 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3025 if (unlikely(vma == NULL))
3026 return ERR_PTR(-ENOMEM);
3028 INIT_LIST_HEAD(&vma->anon_vma_chain);
3030 vma->vm_start = addr;
3031 vma->vm_end = addr + len;
3033 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3034 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3037 vma->vm_private_data = priv;
3039 ret = insert_vm_struct(mm, vma);
3043 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3045 perf_event_mmap(vma);
3050 kmem_cache_free(vm_area_cachep, vma);
3051 return ERR_PTR(ret);
3055 * Called with mm->mmap_sem held for writing.
3056 * Insert a new vma covering the given region, with the given flags.
3057 * Its pages are supplied by the given array of struct page *.
3058 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3059 * The region past the last page supplied will always produce SIGBUS.
3060 * The array pointer and the pages it points to are assumed to stay alive
3061 * for as long as this mapping might exist.
3063 struct vm_area_struct *_install_special_mapping(
3064 struct mm_struct *mm,
3065 unsigned long addr, unsigned long len,
3066 unsigned long vm_flags, const struct vm_special_mapping *spec)
3068 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3069 &special_mapping_vmops);
3072 int install_special_mapping(struct mm_struct *mm,
3073 unsigned long addr, unsigned long len,
3074 unsigned long vm_flags, struct page **pages)
3076 struct vm_area_struct *vma = __install_special_mapping(
3077 mm, addr, len, vm_flags, (void *)pages,
3078 &legacy_special_mapping_vmops);
3080 return PTR_ERR_OR_ZERO(vma);
3083 static DEFINE_MUTEX(mm_all_locks_mutex);
3085 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3087 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3089 * The LSB of head.next can't change from under us
3090 * because we hold the mm_all_locks_mutex.
3092 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3094 * We can safely modify head.next after taking the
3095 * anon_vma->root->rwsem. If some other vma in this mm shares
3096 * the same anon_vma we won't take it again.
3098 * No need of atomic instructions here, head.next
3099 * can't change from under us thanks to the
3100 * anon_vma->root->rwsem.
3102 if (__test_and_set_bit(0, (unsigned long *)
3103 &anon_vma->root->rb_root.rb_node))
3108 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3110 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3112 * AS_MM_ALL_LOCKS can't change from under us because
3113 * we hold the mm_all_locks_mutex.
3115 * Operations on ->flags have to be atomic because
3116 * even if AS_MM_ALL_LOCKS is stable thanks to the
3117 * mm_all_locks_mutex, there may be other cpus
3118 * changing other bitflags in parallel to us.
3120 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3122 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3127 * This operation locks against the VM for all pte/vma/mm related
3128 * operations that could ever happen on a certain mm. This includes
3129 * vmtruncate, try_to_unmap, and all page faults.
3131 * The caller must take the mmap_sem in write mode before calling
3132 * mm_take_all_locks(). The caller isn't allowed to release the
3133 * mmap_sem until mm_drop_all_locks() returns.
3135 * mmap_sem in write mode is required in order to block all operations
3136 * that could modify pagetables and free pages without need of
3137 * altering the vma layout. It's also needed in write mode to avoid new
3138 * anon_vmas to be associated with existing vmas.
3140 * A single task can't take more than one mm_take_all_locks() in a row
3141 * or it would deadlock.
3143 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3144 * mapping->flags avoid to take the same lock twice, if more than one
3145 * vma in this mm is backed by the same anon_vma or address_space.
3147 * We take locks in following order, accordingly to comment at beginning
3149 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3151 * - all i_mmap_rwsem locks;
3152 * - all anon_vma->rwseml
3154 * We can take all locks within these types randomly because the VM code
3155 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3156 * mm_all_locks_mutex.
3158 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3159 * that may have to take thousand of locks.
3161 * mm_take_all_locks() can fail if it's interrupted by signals.
3163 int mm_take_all_locks(struct mm_struct *mm)
3165 struct vm_area_struct *vma;
3166 struct anon_vma_chain *avc;
3168 BUG_ON(down_read_trylock(&mm->mmap_sem));
3170 mutex_lock(&mm_all_locks_mutex);
3172 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3173 if (signal_pending(current))
3175 if (vma->vm_file && vma->vm_file->f_mapping &&
3176 is_vm_hugetlb_page(vma))
3177 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3180 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3181 if (signal_pending(current))
3183 if (vma->vm_file && vma->vm_file->f_mapping &&
3184 !is_vm_hugetlb_page(vma))
3185 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3188 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3189 if (signal_pending(current))
3192 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3193 vm_lock_anon_vma(mm, avc->anon_vma);
3199 mm_drop_all_locks(mm);
3203 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3205 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3207 * The LSB of head.next can't change to 0 from under
3208 * us because we hold the mm_all_locks_mutex.
3210 * We must however clear the bitflag before unlocking
3211 * the vma so the users using the anon_vma->rb_root will
3212 * never see our bitflag.
3214 * No need of atomic instructions here, head.next
3215 * can't change from under us until we release the
3216 * anon_vma->root->rwsem.
3218 if (!__test_and_clear_bit(0, (unsigned long *)
3219 &anon_vma->root->rb_root.rb_node))
3221 anon_vma_unlock_write(anon_vma);
3225 static void vm_unlock_mapping(struct address_space *mapping)
3227 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3229 * AS_MM_ALL_LOCKS can't change to 0 from under us
3230 * because we hold the mm_all_locks_mutex.
3232 i_mmap_unlock_write(mapping);
3233 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3240 * The mmap_sem cannot be released by the caller until
3241 * mm_drop_all_locks() returns.
3243 void mm_drop_all_locks(struct mm_struct *mm)
3245 struct vm_area_struct *vma;
3246 struct anon_vma_chain *avc;
3248 BUG_ON(down_read_trylock(&mm->mmap_sem));
3249 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3251 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3253 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3254 vm_unlock_anon_vma(avc->anon_vma);
3255 if (vma->vm_file && vma->vm_file->f_mapping)
3256 vm_unlock_mapping(vma->vm_file->f_mapping);
3259 mutex_unlock(&mm_all_locks_mutex);
3263 * initialise the VMA slab
3265 void __init mmap_init(void)
3269 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3274 * Initialise sysctl_user_reserve_kbytes.
3276 * This is intended to prevent a user from starting a single memory hogging
3277 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3280 * The default value is min(3% of free memory, 128MB)
3281 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3283 static int init_user_reserve(void)
3285 unsigned long free_kbytes;
3287 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3289 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3292 subsys_initcall(init_user_reserve);
3295 * Initialise sysctl_admin_reserve_kbytes.
3297 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3298 * to log in and kill a memory hogging process.
3300 * Systems with more than 256MB will reserve 8MB, enough to recover
3301 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3302 * only reserve 3% of free pages by default.
3304 static int init_admin_reserve(void)
3306 unsigned long free_kbytes;
3308 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3310 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3313 subsys_initcall(init_admin_reserve);
3316 * Reinititalise user and admin reserves if memory is added or removed.
3318 * The default user reserve max is 128MB, and the default max for the
3319 * admin reserve is 8MB. These are usually, but not always, enough to
3320 * enable recovery from a memory hogging process using login/sshd, a shell,
3321 * and tools like top. It may make sense to increase or even disable the
3322 * reserve depending on the existence of swap or variations in the recovery
3323 * tools. So, the admin may have changed them.
3325 * If memory is added and the reserves have been eliminated or increased above
3326 * the default max, then we'll trust the admin.
3328 * If memory is removed and there isn't enough free memory, then we
3329 * need to reset the reserves.
3331 * Otherwise keep the reserve set by the admin.
3333 static int reserve_mem_notifier(struct notifier_block *nb,
3334 unsigned long action, void *data)
3336 unsigned long tmp, free_kbytes;
3340 /* Default max is 128MB. Leave alone if modified by operator. */
3341 tmp = sysctl_user_reserve_kbytes;
3342 if (0 < tmp && tmp < (1UL << 17))
3343 init_user_reserve();
3345 /* Default max is 8MB. Leave alone if modified by operator. */
3346 tmp = sysctl_admin_reserve_kbytes;
3347 if (0 < tmp && tmp < (1UL << 13))
3348 init_admin_reserve();
3352 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3354 if (sysctl_user_reserve_kbytes > free_kbytes) {
3355 init_user_reserve();
3356 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3357 sysctl_user_reserve_kbytes);
3360 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3361 init_admin_reserve();
3362 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3363 sysctl_admin_reserve_kbytes);
3372 static struct notifier_block reserve_mem_nb = {
3373 .notifier_call = reserve_mem_notifier,
3376 static int __meminit init_reserve_notifier(void)
3378 if (register_hotmemory_notifier(&reserve_mem_nb))
3379 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3383 subsys_initcall(init_reserve_notifier);