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/profile.h>
29 #include <linux/export.h>
30 #include <linux/mount.h>
31 #include <linux/mempolicy.h>
32 #include <linux/rmap.h>
33 #include <linux/mmu_notifier.h>
34 #include <linux/mmdebug.h>
35 #include <linux/perf_event.h>
36 #include <linux/audit.h>
37 #include <linux/khugepaged.h>
38 #include <linux/uprobes.h>
39 #include <linux/rbtree_augmented.h>
40 #include <linux/notifier.h>
41 #include <linux/memory.h>
42 #include <linux/printk.h>
43 #include <linux/userfaultfd_k.h>
44 #include <linux/moduleparam.h>
46 #include <asm/uaccess.h>
47 #include <asm/cacheflush.h>
49 #include <asm/mmu_context.h>
53 #ifndef arch_mmap_check
54 #define arch_mmap_check(addr, len, flags) (0)
57 #ifndef arch_rebalance_pgtables
58 #define arch_rebalance_pgtables(addr, len) (addr)
61 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
62 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
63 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
64 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
66 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
67 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
68 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
69 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
72 static bool ignore_rlimit_data = true;
73 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
75 static void unmap_region(struct mm_struct *mm,
76 struct vm_area_struct *vma, struct vm_area_struct *prev,
77 unsigned long start, unsigned long end);
79 /* description of effects of mapping type and prot in current implementation.
80 * this is due to the limited x86 page protection hardware. The expected
81 * behavior is in parens:
84 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
85 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
86 * w: (no) no w: (no) no w: (yes) yes w: (no) no
87 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
89 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
90 * w: (no) no w: (no) no w: (copy) copy w: (no) no
91 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
94 pgprot_t protection_map[16] = {
95 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
96 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
99 pgprot_t vm_get_page_prot(unsigned long vm_flags)
101 return __pgprot(pgprot_val(protection_map[vm_flags &
102 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
103 pgprot_val(arch_vm_get_page_prot(vm_flags)));
105 EXPORT_SYMBOL(vm_get_page_prot);
107 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
109 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
112 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
113 void vma_set_page_prot(struct vm_area_struct *vma)
115 unsigned long vm_flags = vma->vm_flags;
117 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
118 if (vma_wants_writenotify(vma)) {
119 vm_flags &= ~VM_SHARED;
120 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
126 * Requires inode->i_mapping->i_mmap_rwsem
128 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
129 struct file *file, struct address_space *mapping)
131 if (vma->vm_flags & VM_DENYWRITE)
132 atomic_inc(&file_inode(file)->i_writecount);
133 if (vma->vm_flags & VM_SHARED)
134 mapping_unmap_writable(mapping);
136 flush_dcache_mmap_lock(mapping);
137 vma_interval_tree_remove(vma, &mapping->i_mmap);
138 flush_dcache_mmap_unlock(mapping);
142 * Unlink a file-based vm structure from its interval tree, to hide
143 * vma from rmap and vmtruncate before freeing its page tables.
145 void unlink_file_vma(struct vm_area_struct *vma)
147 struct file *file = vma->vm_file;
150 struct address_space *mapping = file->f_mapping;
151 i_mmap_lock_write(mapping);
152 __remove_shared_vm_struct(vma, file, mapping);
153 i_mmap_unlock_write(mapping);
158 * Close a vm structure and free it, returning the next.
160 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
162 struct vm_area_struct *next = vma->vm_next;
165 if (vma->vm_ops && vma->vm_ops->close)
166 vma->vm_ops->close(vma);
169 mpol_put(vma_policy(vma));
170 kmem_cache_free(vm_area_cachep, vma);
174 static unsigned long do_brk(unsigned long addr, unsigned long len);
176 SYSCALL_DEFINE1(brk, unsigned long, brk)
178 unsigned long retval;
179 unsigned long newbrk, oldbrk;
180 struct mm_struct *mm = current->mm;
181 unsigned long min_brk;
184 down_write(&mm->mmap_sem);
186 #ifdef CONFIG_COMPAT_BRK
188 * CONFIG_COMPAT_BRK can still be overridden by setting
189 * randomize_va_space to 2, which will still cause mm->start_brk
190 * to be arbitrarily shifted
192 if (current->brk_randomized)
193 min_brk = mm->start_brk;
195 min_brk = mm->end_data;
197 min_brk = mm->start_brk;
203 * Check against rlimit here. If this check is done later after the test
204 * of oldbrk with newbrk then it can escape the test and let the data
205 * segment grow beyond its set limit the in case where the limit is
206 * not page aligned -Ram Gupta
208 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
209 mm->end_data, mm->start_data))
212 newbrk = PAGE_ALIGN(brk);
213 oldbrk = PAGE_ALIGN(mm->brk);
214 if (oldbrk == newbrk)
217 /* Always allow shrinking brk. */
218 if (brk <= mm->brk) {
219 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
224 /* Check against existing mmap mappings. */
225 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
228 /* Ok, looks good - let it rip. */
229 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
234 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
235 up_write(&mm->mmap_sem);
237 mm_populate(oldbrk, newbrk - oldbrk);
242 up_write(&mm->mmap_sem);
246 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
248 unsigned long max, subtree_gap;
251 max -= vma->vm_prev->vm_end;
252 if (vma->vm_rb.rb_left) {
253 subtree_gap = rb_entry(vma->vm_rb.rb_left,
254 struct vm_area_struct, vm_rb)->rb_subtree_gap;
255 if (subtree_gap > max)
258 if (vma->vm_rb.rb_right) {
259 subtree_gap = rb_entry(vma->vm_rb.rb_right,
260 struct vm_area_struct, vm_rb)->rb_subtree_gap;
261 if (subtree_gap > max)
267 #ifdef CONFIG_DEBUG_VM_RB
268 static int browse_rb(struct mm_struct *mm)
270 struct rb_root *root = &mm->mm_rb;
271 int i = 0, j, bug = 0;
272 struct rb_node *nd, *pn = NULL;
273 unsigned long prev = 0, pend = 0;
275 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
276 struct vm_area_struct *vma;
277 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
278 if (vma->vm_start < prev) {
279 pr_emerg("vm_start %lx < prev %lx\n",
280 vma->vm_start, prev);
283 if (vma->vm_start < pend) {
284 pr_emerg("vm_start %lx < pend %lx\n",
285 vma->vm_start, pend);
288 if (vma->vm_start > vma->vm_end) {
289 pr_emerg("vm_start %lx > vm_end %lx\n",
290 vma->vm_start, vma->vm_end);
293 spin_lock(&mm->page_table_lock);
294 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
295 pr_emerg("free gap %lx, correct %lx\n",
297 vma_compute_subtree_gap(vma));
300 spin_unlock(&mm->page_table_lock);
303 prev = vma->vm_start;
307 for (nd = pn; nd; nd = rb_prev(nd))
310 pr_emerg("backwards %d, forwards %d\n", j, i);
316 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
320 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
321 struct vm_area_struct *vma;
322 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
323 VM_BUG_ON_VMA(vma != ignore &&
324 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
329 static void validate_mm(struct mm_struct *mm)
333 unsigned long highest_address = 0;
334 struct vm_area_struct *vma = mm->mmap;
337 struct anon_vma *anon_vma = vma->anon_vma;
338 struct anon_vma_chain *avc;
341 anon_vma_lock_read(anon_vma);
342 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
343 anon_vma_interval_tree_verify(avc);
344 anon_vma_unlock_read(anon_vma);
347 highest_address = vma->vm_end;
351 if (i != mm->map_count) {
352 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
355 if (highest_address != mm->highest_vm_end) {
356 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
357 mm->highest_vm_end, highest_address);
361 if (i != mm->map_count) {
363 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
366 VM_BUG_ON_MM(bug, mm);
369 #define validate_mm_rb(root, ignore) do { } while (0)
370 #define validate_mm(mm) do { } while (0)
373 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
374 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
377 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
378 * vma->vm_prev->vm_end values changed, without modifying the vma's position
381 static void vma_gap_update(struct vm_area_struct *vma)
384 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
385 * function that does exacltly what we want.
387 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
390 static inline void vma_rb_insert(struct vm_area_struct *vma,
391 struct rb_root *root)
393 /* All rb_subtree_gap values must be consistent prior to insertion */
394 validate_mm_rb(root, NULL);
396 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
399 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
402 * All rb_subtree_gap values must be consistent prior to erase,
403 * with the possible exception of the vma being erased.
405 validate_mm_rb(root, vma);
408 * Note rb_erase_augmented is a fairly large inline function,
409 * so make sure we instantiate it only once with our desired
410 * augmented rbtree callbacks.
412 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
416 * vma has some anon_vma assigned, and is already inserted on that
417 * anon_vma's interval trees.
419 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
420 * vma must be removed from the anon_vma's interval trees using
421 * anon_vma_interval_tree_pre_update_vma().
423 * After the update, the vma will be reinserted using
424 * anon_vma_interval_tree_post_update_vma().
426 * The entire update must be protected by exclusive mmap_sem and by
427 * the root anon_vma's mutex.
430 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
432 struct anon_vma_chain *avc;
434 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
435 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
439 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
441 struct anon_vma_chain *avc;
443 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
444 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
447 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
448 unsigned long end, struct vm_area_struct **pprev,
449 struct rb_node ***rb_link, struct rb_node **rb_parent)
451 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
453 __rb_link = &mm->mm_rb.rb_node;
454 rb_prev = __rb_parent = NULL;
457 struct vm_area_struct *vma_tmp;
459 __rb_parent = *__rb_link;
460 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
462 if (vma_tmp->vm_end > addr) {
463 /* Fail if an existing vma overlaps the area */
464 if (vma_tmp->vm_start < end)
466 __rb_link = &__rb_parent->rb_left;
468 rb_prev = __rb_parent;
469 __rb_link = &__rb_parent->rb_right;
475 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
476 *rb_link = __rb_link;
477 *rb_parent = __rb_parent;
481 static unsigned long count_vma_pages_range(struct mm_struct *mm,
482 unsigned long addr, unsigned long end)
484 unsigned long nr_pages = 0;
485 struct vm_area_struct *vma;
487 /* Find first overlaping mapping */
488 vma = find_vma_intersection(mm, addr, end);
492 nr_pages = (min(end, vma->vm_end) -
493 max(addr, vma->vm_start)) >> PAGE_SHIFT;
495 /* Iterate over the rest of the overlaps */
496 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
497 unsigned long overlap_len;
499 if (vma->vm_start > end)
502 overlap_len = min(end, vma->vm_end) - vma->vm_start;
503 nr_pages += overlap_len >> PAGE_SHIFT;
509 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
510 struct rb_node **rb_link, struct rb_node *rb_parent)
512 /* Update tracking information for the gap following the new vma. */
514 vma_gap_update(vma->vm_next);
516 mm->highest_vm_end = vma->vm_end;
519 * vma->vm_prev wasn't known when we followed the rbtree to find the
520 * correct insertion point for that vma. As a result, we could not
521 * update the vma vm_rb parents rb_subtree_gap values on the way down.
522 * So, we first insert the vma with a zero rb_subtree_gap value
523 * (to be consistent with what we did on the way down), and then
524 * immediately update the gap to the correct value. Finally we
525 * rebalance the rbtree after all augmented values have been set.
527 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
528 vma->rb_subtree_gap = 0;
530 vma_rb_insert(vma, &mm->mm_rb);
533 static void __vma_link_file(struct vm_area_struct *vma)
539 struct address_space *mapping = file->f_mapping;
541 if (vma->vm_flags & VM_DENYWRITE)
542 atomic_dec(&file_inode(file)->i_writecount);
543 if (vma->vm_flags & VM_SHARED)
544 atomic_inc(&mapping->i_mmap_writable);
546 flush_dcache_mmap_lock(mapping);
547 vma_interval_tree_insert(vma, &mapping->i_mmap);
548 flush_dcache_mmap_unlock(mapping);
553 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
554 struct vm_area_struct *prev, struct rb_node **rb_link,
555 struct rb_node *rb_parent)
557 __vma_link_list(mm, vma, prev, rb_parent);
558 __vma_link_rb(mm, vma, rb_link, rb_parent);
561 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
562 struct vm_area_struct *prev, struct rb_node **rb_link,
563 struct rb_node *rb_parent)
565 struct address_space *mapping = NULL;
568 mapping = vma->vm_file->f_mapping;
569 i_mmap_lock_write(mapping);
572 __vma_link(mm, vma, prev, rb_link, rb_parent);
573 __vma_link_file(vma);
576 i_mmap_unlock_write(mapping);
583 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
584 * mm's list and rbtree. It has already been inserted into the interval tree.
586 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
588 struct vm_area_struct *prev;
589 struct rb_node **rb_link, *rb_parent;
591 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
592 &prev, &rb_link, &rb_parent))
594 __vma_link(mm, vma, prev, rb_link, rb_parent);
599 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
600 struct vm_area_struct *prev)
602 struct vm_area_struct *next;
604 vma_rb_erase(vma, &mm->mm_rb);
605 prev->vm_next = next = vma->vm_next;
607 next->vm_prev = prev;
610 vmacache_invalidate(mm);
614 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
615 * is already present in an i_mmap tree without adjusting the tree.
616 * The following helper function should be used when such adjustments
617 * are necessary. The "insert" vma (if any) is to be inserted
618 * before we drop the necessary locks.
620 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
621 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
623 struct mm_struct *mm = vma->vm_mm;
624 struct vm_area_struct *next = vma->vm_next;
625 struct vm_area_struct *importer = NULL;
626 struct address_space *mapping = NULL;
627 struct rb_root *root = NULL;
628 struct anon_vma *anon_vma = NULL;
629 struct file *file = vma->vm_file;
630 bool start_changed = false, end_changed = false;
631 long adjust_next = 0;
634 if (next && !insert) {
635 struct vm_area_struct *exporter = NULL;
637 if (end >= next->vm_end) {
639 * vma expands, overlapping all the next, and
640 * perhaps the one after too (mprotect case 6).
642 again: remove_next = 1 + (end > next->vm_end);
646 } else if (end > next->vm_start) {
648 * vma expands, overlapping part of the next:
649 * mprotect case 5 shifting the boundary up.
651 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
654 } else if (end < vma->vm_end) {
656 * vma shrinks, and !insert tells it's not
657 * split_vma inserting another: so it must be
658 * mprotect case 4 shifting the boundary down.
660 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
666 * Easily overlooked: when mprotect shifts the boundary,
667 * make sure the expanding vma has anon_vma set if the
668 * shrinking vma had, to cover any anon pages imported.
670 if (exporter && exporter->anon_vma && !importer->anon_vma) {
673 importer->anon_vma = exporter->anon_vma;
674 error = anon_vma_clone(importer, exporter);
681 mapping = file->f_mapping;
682 root = &mapping->i_mmap;
683 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
686 uprobe_munmap(next, next->vm_start, next->vm_end);
688 i_mmap_lock_write(mapping);
691 * Put into interval tree now, so instantiated pages
692 * are visible to arm/parisc __flush_dcache_page
693 * throughout; but we cannot insert into address
694 * space until vma start or end is updated.
696 __vma_link_file(insert);
700 vma_adjust_trans_huge(vma, start, end, adjust_next);
702 anon_vma = vma->anon_vma;
703 if (!anon_vma && adjust_next)
704 anon_vma = next->anon_vma;
706 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
707 anon_vma != next->anon_vma, next);
708 anon_vma_lock_write(anon_vma);
709 anon_vma_interval_tree_pre_update_vma(vma);
711 anon_vma_interval_tree_pre_update_vma(next);
715 flush_dcache_mmap_lock(mapping);
716 vma_interval_tree_remove(vma, root);
718 vma_interval_tree_remove(next, root);
721 if (start != vma->vm_start) {
722 vma->vm_start = start;
723 start_changed = true;
725 if (end != vma->vm_end) {
729 vma->vm_pgoff = pgoff;
731 next->vm_start += adjust_next << PAGE_SHIFT;
732 next->vm_pgoff += adjust_next;
737 vma_interval_tree_insert(next, root);
738 vma_interval_tree_insert(vma, root);
739 flush_dcache_mmap_unlock(mapping);
744 * vma_merge has merged next into vma, and needs
745 * us to remove next before dropping the locks.
747 __vma_unlink(mm, next, vma);
749 __remove_shared_vm_struct(next, file, mapping);
752 * split_vma has split insert from vma, and needs
753 * us to insert it before dropping the locks
754 * (it may either follow vma or precede it).
756 __insert_vm_struct(mm, insert);
762 mm->highest_vm_end = end;
763 else if (!adjust_next)
764 vma_gap_update(next);
769 anon_vma_interval_tree_post_update_vma(vma);
771 anon_vma_interval_tree_post_update_vma(next);
772 anon_vma_unlock_write(anon_vma);
775 i_mmap_unlock_write(mapping);
786 uprobe_munmap(next, next->vm_start, next->vm_end);
790 anon_vma_merge(vma, next);
792 mpol_put(vma_policy(next));
793 kmem_cache_free(vm_area_cachep, next);
795 * In mprotect's case 6 (see comments on vma_merge),
796 * we must remove another next too. It would clutter
797 * up the code too much to do both in one go.
800 if (remove_next == 2)
803 vma_gap_update(next);
805 mm->highest_vm_end = end;
816 * If the vma has a ->close operation then the driver probably needs to release
817 * per-vma resources, so we don't attempt to merge those.
819 static inline int is_mergeable_vma(struct vm_area_struct *vma,
820 struct file *file, unsigned long vm_flags,
821 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
824 * VM_SOFTDIRTY should not prevent from VMA merging, if we
825 * match the flags but dirty bit -- the caller should mark
826 * merged VMA as dirty. If dirty bit won't be excluded from
827 * comparison, we increase pressue on the memory system forcing
828 * the kernel to generate new VMAs when old one could be
831 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
833 if (vma->vm_file != file)
835 if (vma->vm_ops && vma->vm_ops->close)
837 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
842 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
843 struct anon_vma *anon_vma2,
844 struct vm_area_struct *vma)
847 * The list_is_singular() test is to avoid merging VMA cloned from
848 * parents. This can improve scalability caused by anon_vma lock.
850 if ((!anon_vma1 || !anon_vma2) && (!vma ||
851 list_is_singular(&vma->anon_vma_chain)))
853 return anon_vma1 == anon_vma2;
857 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
858 * in front of (at a lower virtual address and file offset than) the vma.
860 * We cannot merge two vmas if they have differently assigned (non-NULL)
861 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
863 * We don't check here for the merged mmap wrapping around the end of pagecache
864 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
865 * wrap, nor mmaps which cover the final page at index -1UL.
868 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
869 struct anon_vma *anon_vma, struct file *file,
871 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
873 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
874 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
875 if (vma->vm_pgoff == vm_pgoff)
882 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
883 * beyond (at a higher virtual address and file offset than) the vma.
885 * We cannot merge two vmas if they have differently assigned (non-NULL)
886 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
889 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
890 struct anon_vma *anon_vma, struct file *file,
892 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
894 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
895 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
897 vm_pglen = vma_pages(vma);
898 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
905 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
906 * whether that can be merged with its predecessor or its successor.
907 * Or both (it neatly fills a hole).
909 * In most cases - when called for mmap, brk or mremap - [addr,end) is
910 * certain not to be mapped by the time vma_merge is called; but when
911 * called for mprotect, it is certain to be already mapped (either at
912 * an offset within prev, or at the start of next), and the flags of
913 * this area are about to be changed to vm_flags - and the no-change
914 * case has already been eliminated.
916 * The following mprotect cases have to be considered, where AAAA is
917 * the area passed down from mprotect_fixup, never extending beyond one
918 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
920 * AAAA AAAA AAAA AAAA
921 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
922 * cannot merge might become might become might become
923 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
924 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
925 * mremap move: PPPPNNNNNNNN 8
927 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
928 * might become case 1 below case 2 below case 3 below
930 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
931 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
933 struct vm_area_struct *vma_merge(struct mm_struct *mm,
934 struct vm_area_struct *prev, unsigned long addr,
935 unsigned long end, unsigned long vm_flags,
936 struct anon_vma *anon_vma, struct file *file,
937 pgoff_t pgoff, struct mempolicy *policy,
938 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
940 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
941 struct vm_area_struct *area, *next;
945 * We later require that vma->vm_flags == vm_flags,
946 * so this tests vma->vm_flags & VM_SPECIAL, too.
948 if (vm_flags & VM_SPECIAL)
952 next = prev->vm_next;
956 if (next && next->vm_end == end) /* cases 6, 7, 8 */
957 next = next->vm_next;
960 * Can it merge with the predecessor?
962 if (prev && prev->vm_end == addr &&
963 mpol_equal(vma_policy(prev), policy) &&
964 can_vma_merge_after(prev, vm_flags,
965 anon_vma, file, pgoff,
966 vm_userfaultfd_ctx)) {
968 * OK, it can. Can we now merge in the successor as well?
970 if (next && end == next->vm_start &&
971 mpol_equal(policy, vma_policy(next)) &&
972 can_vma_merge_before(next, vm_flags,
975 vm_userfaultfd_ctx) &&
976 is_mergeable_anon_vma(prev->anon_vma,
977 next->anon_vma, NULL)) {
979 err = vma_adjust(prev, prev->vm_start,
980 next->vm_end, prev->vm_pgoff, NULL);
981 } else /* cases 2, 5, 7 */
982 err = vma_adjust(prev, prev->vm_start,
983 end, prev->vm_pgoff, NULL);
986 khugepaged_enter_vma_merge(prev, vm_flags);
991 * Can this new request be merged in front of next?
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 vm_userfaultfd_ctx)) {
998 if (prev && addr < prev->vm_end) /* case 4 */
999 err = vma_adjust(prev, prev->vm_start,
1000 addr, prev->vm_pgoff, NULL);
1001 else /* cases 3, 8 */
1002 err = vma_adjust(area, addr, next->vm_end,
1003 next->vm_pgoff - pglen, NULL);
1006 khugepaged_enter_vma_merge(area, vm_flags);
1014 * Rough compatbility check to quickly see if it's even worth looking
1015 * at sharing an anon_vma.
1017 * They need to have the same vm_file, and the flags can only differ
1018 * in things that mprotect may change.
1020 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1021 * we can merge the two vma's. For example, we refuse to merge a vma if
1022 * there is a vm_ops->close() function, because that indicates that the
1023 * driver is doing some kind of reference counting. But that doesn't
1024 * really matter for the anon_vma sharing case.
1026 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1028 return a->vm_end == b->vm_start &&
1029 mpol_equal(vma_policy(a), vma_policy(b)) &&
1030 a->vm_file == b->vm_file &&
1031 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1032 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1036 * Do some basic sanity checking to see if we can re-use the anon_vma
1037 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1038 * the same as 'old', the other will be the new one that is trying
1039 * to share the anon_vma.
1041 * NOTE! This runs with mm_sem held for reading, so it is possible that
1042 * the anon_vma of 'old' is concurrently in the process of being set up
1043 * by another page fault trying to merge _that_. But that's ok: if it
1044 * is being set up, that automatically means that it will be a singleton
1045 * acceptable for merging, so we can do all of this optimistically. But
1046 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1048 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1049 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1050 * is to return an anon_vma that is "complex" due to having gone through
1053 * We also make sure that the two vma's are compatible (adjacent,
1054 * and with the same memory policies). That's all stable, even with just
1055 * a read lock on the mm_sem.
1057 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1059 if (anon_vma_compatible(a, b)) {
1060 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1062 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1069 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1070 * neighbouring vmas for a suitable anon_vma, before it goes off
1071 * to allocate a new anon_vma. It checks because a repetitive
1072 * sequence of mprotects and faults may otherwise lead to distinct
1073 * anon_vmas being allocated, preventing vma merge in subsequent
1076 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1078 struct anon_vma *anon_vma;
1079 struct vm_area_struct *near;
1081 near = vma->vm_next;
1085 anon_vma = reusable_anon_vma(near, vma, near);
1089 near = vma->vm_prev;
1093 anon_vma = reusable_anon_vma(near, near, vma);
1098 * There's no absolute need to look only at touching neighbours:
1099 * we could search further afield for "compatible" anon_vmas.
1100 * But it would probably just be a waste of time searching,
1101 * or lead to too many vmas hanging off the same anon_vma.
1102 * We're trying to allow mprotect remerging later on,
1103 * not trying to minimize memory used for anon_vmas.
1109 * If a hint addr is less than mmap_min_addr change hint to be as
1110 * low as possible but still greater than mmap_min_addr
1112 static inline unsigned long round_hint_to_min(unsigned long hint)
1115 if (((void *)hint != NULL) &&
1116 (hint < mmap_min_addr))
1117 return PAGE_ALIGN(mmap_min_addr);
1121 static inline int mlock_future_check(struct mm_struct *mm,
1122 unsigned long flags,
1125 unsigned long locked, lock_limit;
1127 /* mlock MCL_FUTURE? */
1128 if (flags & VM_LOCKED) {
1129 locked = len >> PAGE_SHIFT;
1130 locked += mm->locked_vm;
1131 lock_limit = rlimit(RLIMIT_MEMLOCK);
1132 lock_limit >>= PAGE_SHIFT;
1133 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1140 * The caller must hold down_write(¤t->mm->mmap_sem).
1142 unsigned long do_mmap(struct file *file, unsigned long addr,
1143 unsigned long len, unsigned long prot,
1144 unsigned long flags, vm_flags_t vm_flags,
1145 unsigned long pgoff, unsigned long *populate)
1147 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 /* Do simple checking here so the lower-level routines won't have
1188 * to. we assume access permissions have been handled by the open
1189 * of the memory object, so we don't do any here.
1191 vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1192 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1194 if (flags & MAP_LOCKED)
1195 if (!can_do_mlock())
1198 if (mlock_future_check(mm, vm_flags, len))
1202 struct inode *inode = file_inode(file);
1204 switch (flags & MAP_TYPE) {
1206 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1210 * Make sure we don't allow writing to an append-only
1213 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1217 * Make sure there are no mandatory locks on the file.
1219 if (locks_verify_locked(file))
1222 vm_flags |= VM_SHARED | VM_MAYSHARE;
1223 if (!(file->f_mode & FMODE_WRITE))
1224 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1228 if (!(file->f_mode & FMODE_READ))
1230 if (path_noexec(&file->f_path)) {
1231 if (vm_flags & VM_EXEC)
1233 vm_flags &= ~VM_MAYEXEC;
1236 if (!file->f_op->mmap)
1238 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1246 switch (flags & MAP_TYPE) {
1248 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1254 vm_flags |= VM_SHARED | VM_MAYSHARE;
1258 * Set pgoff according to addr for anon_vma.
1260 pgoff = addr >> PAGE_SHIFT;
1268 * Set 'VM_NORESERVE' if we should not account for the
1269 * memory use of this mapping.
1271 if (flags & MAP_NORESERVE) {
1272 /* We honor MAP_NORESERVE if allowed to overcommit */
1273 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1274 vm_flags |= VM_NORESERVE;
1276 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1277 if (file && is_file_hugepages(file))
1278 vm_flags |= VM_NORESERVE;
1281 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1282 if (!IS_ERR_VALUE(addr) &&
1283 ((vm_flags & VM_LOCKED) ||
1284 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1289 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1290 unsigned long, prot, unsigned long, flags,
1291 unsigned long, fd, unsigned long, pgoff)
1293 struct file *file = NULL;
1294 unsigned long retval;
1296 if (!(flags & MAP_ANONYMOUS)) {
1297 audit_mmap_fd(fd, flags);
1301 if (is_file_hugepages(file))
1302 len = ALIGN(len, huge_page_size(hstate_file(file)));
1304 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1306 } else if (flags & MAP_HUGETLB) {
1307 struct user_struct *user = NULL;
1310 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1314 len = ALIGN(len, huge_page_size(hs));
1316 * VM_NORESERVE is used because the reservations will be
1317 * taken when vm_ops->mmap() is called
1318 * A dummy user value is used because we are not locking
1319 * memory so no accounting is necessary
1321 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1323 &user, HUGETLB_ANONHUGE_INODE,
1324 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1326 return PTR_ERR(file);
1329 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1331 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1338 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1339 struct mmap_arg_struct {
1343 unsigned long flags;
1345 unsigned long offset;
1348 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1350 struct mmap_arg_struct a;
1352 if (copy_from_user(&a, arg, sizeof(a)))
1354 if (offset_in_page(a.offset))
1357 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1358 a.offset >> PAGE_SHIFT);
1360 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1363 * Some shared mappigns will want the pages marked read-only
1364 * to track write events. If so, we'll downgrade vm_page_prot
1365 * to the private version (using protection_map[] without the
1368 int vma_wants_writenotify(struct vm_area_struct *vma)
1370 vm_flags_t vm_flags = vma->vm_flags;
1371 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1373 /* If it was private or non-writable, the write bit is already clear */
1374 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1377 /* The backer wishes to know when pages are first written to? */
1378 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1381 /* The open routine did something to the protections that pgprot_modify
1382 * won't preserve? */
1383 if (pgprot_val(vma->vm_page_prot) !=
1384 pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1387 /* Do we need to track softdirty? */
1388 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1391 /* Specialty mapping? */
1392 if (vm_flags & VM_PFNMAP)
1395 /* Can the mapping track the dirty pages? */
1396 return vma->vm_file && vma->vm_file->f_mapping &&
1397 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1401 * We account for memory if it's a private writeable mapping,
1402 * not hugepages and VM_NORESERVE wasn't set.
1404 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1407 * hugetlb has its own accounting separate from the core VM
1408 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1410 if (file && is_file_hugepages(file))
1413 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1416 unsigned long mmap_region(struct file *file, unsigned long addr,
1417 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1419 struct mm_struct *mm = current->mm;
1420 struct vm_area_struct *vma, *prev;
1422 struct rb_node **rb_link, *rb_parent;
1423 unsigned long charged = 0;
1425 /* Check against address space limit. */
1426 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1427 unsigned long nr_pages;
1430 * MAP_FIXED may remove pages of mappings that intersects with
1431 * requested mapping. Account for the pages it would unmap.
1433 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1435 if (!may_expand_vm(mm, vm_flags,
1436 (len >> PAGE_SHIFT) - nr_pages))
1440 /* Clear old maps */
1441 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1443 if (do_munmap(mm, addr, len))
1448 * Private writable mapping: check memory availability
1450 if (accountable_mapping(file, vm_flags)) {
1451 charged = len >> PAGE_SHIFT;
1452 if (security_vm_enough_memory_mm(mm, charged))
1454 vm_flags |= VM_ACCOUNT;
1458 * Can we just expand an old mapping?
1460 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1461 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1466 * Determine the object being mapped and call the appropriate
1467 * specific mapper. the address has already been validated, but
1468 * not unmapped, but the maps are removed from the list.
1470 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1477 vma->vm_start = addr;
1478 vma->vm_end = addr + len;
1479 vma->vm_flags = vm_flags;
1480 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1481 vma->vm_pgoff = pgoff;
1482 INIT_LIST_HEAD(&vma->anon_vma_chain);
1485 if (vm_flags & VM_DENYWRITE) {
1486 error = deny_write_access(file);
1490 if (vm_flags & VM_SHARED) {
1491 error = mapping_map_writable(file->f_mapping);
1493 goto allow_write_and_free_vma;
1496 /* ->mmap() can change vma->vm_file, but must guarantee that
1497 * vma_link() below can deny write-access if VM_DENYWRITE is set
1498 * and map writably if VM_SHARED is set. This usually means the
1499 * new file must not have been exposed to user-space, yet.
1501 vma->vm_file = get_file(file);
1502 error = file->f_op->mmap(file, vma);
1504 goto unmap_and_free_vma;
1506 /* Can addr have changed??
1508 * Answer: Yes, several device drivers can do it in their
1509 * f_op->mmap method. -DaveM
1510 * Bug: If addr is changed, prev, rb_link, rb_parent should
1511 * be updated for vma_link()
1513 WARN_ON_ONCE(addr != vma->vm_start);
1515 addr = vma->vm_start;
1516 vm_flags = vma->vm_flags;
1517 } else if (vm_flags & VM_SHARED) {
1518 error = shmem_zero_setup(vma);
1523 vma_link(mm, vma, prev, rb_link, rb_parent);
1524 /* Once vma denies write, undo our temporary denial count */
1526 if (vm_flags & VM_SHARED)
1527 mapping_unmap_writable(file->f_mapping);
1528 if (vm_flags & VM_DENYWRITE)
1529 allow_write_access(file);
1531 file = vma->vm_file;
1533 perf_event_mmap(vma);
1535 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1536 if (vm_flags & VM_LOCKED) {
1537 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1538 vma == get_gate_vma(current->mm)))
1539 mm->locked_vm += (len >> PAGE_SHIFT);
1541 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1548 * New (or expanded) vma always get soft dirty status.
1549 * Otherwise user-space soft-dirty page tracker won't
1550 * be able to distinguish situation when vma area unmapped,
1551 * then new mapped in-place (which must be aimed as
1552 * a completely new data area).
1554 vma->vm_flags |= VM_SOFTDIRTY;
1556 vma_set_page_prot(vma);
1561 vma->vm_file = NULL;
1564 /* Undo any partial mapping done by a device driver. */
1565 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1567 if (vm_flags & VM_SHARED)
1568 mapping_unmap_writable(file->f_mapping);
1569 allow_write_and_free_vma:
1570 if (vm_flags & VM_DENYWRITE)
1571 allow_write_access(file);
1573 kmem_cache_free(vm_area_cachep, vma);
1576 vm_unacct_memory(charged);
1580 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1583 * We implement the search by looking for an rbtree node that
1584 * immediately follows a suitable gap. That is,
1585 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1586 * - gap_end = vma->vm_start >= info->low_limit + length;
1587 * - gap_end - gap_start >= length
1590 struct mm_struct *mm = current->mm;
1591 struct vm_area_struct *vma;
1592 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1594 /* Adjust search length to account for worst case alignment overhead */
1595 length = info->length + info->align_mask;
1596 if (length < info->length)
1599 /* Adjust search limits by the desired length */
1600 if (info->high_limit < length)
1602 high_limit = info->high_limit - length;
1604 if (info->low_limit > high_limit)
1606 low_limit = info->low_limit + length;
1608 /* Check if rbtree root looks promising */
1609 if (RB_EMPTY_ROOT(&mm->mm_rb))
1611 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1612 if (vma->rb_subtree_gap < length)
1616 /* Visit left subtree if it looks promising */
1617 gap_end = vma->vm_start;
1618 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1619 struct vm_area_struct *left =
1620 rb_entry(vma->vm_rb.rb_left,
1621 struct vm_area_struct, vm_rb);
1622 if (left->rb_subtree_gap >= length) {
1628 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1630 /* Check if current node has a suitable gap */
1631 if (gap_start > high_limit)
1633 if (gap_end >= low_limit && gap_end - gap_start >= length)
1636 /* Visit right subtree if it looks promising */
1637 if (vma->vm_rb.rb_right) {
1638 struct vm_area_struct *right =
1639 rb_entry(vma->vm_rb.rb_right,
1640 struct vm_area_struct, vm_rb);
1641 if (right->rb_subtree_gap >= length) {
1647 /* Go back up the rbtree to find next candidate node */
1649 struct rb_node *prev = &vma->vm_rb;
1650 if (!rb_parent(prev))
1652 vma = rb_entry(rb_parent(prev),
1653 struct vm_area_struct, vm_rb);
1654 if (prev == vma->vm_rb.rb_left) {
1655 gap_start = vma->vm_prev->vm_end;
1656 gap_end = vma->vm_start;
1663 /* Check highest gap, which does not precede any rbtree node */
1664 gap_start = mm->highest_vm_end;
1665 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1666 if (gap_start > high_limit)
1670 /* We found a suitable gap. Clip it with the original low_limit. */
1671 if (gap_start < info->low_limit)
1672 gap_start = info->low_limit;
1674 /* Adjust gap address to the desired alignment */
1675 gap_start += (info->align_offset - gap_start) & info->align_mask;
1677 VM_BUG_ON(gap_start + info->length > info->high_limit);
1678 VM_BUG_ON(gap_start + info->length > gap_end);
1682 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1684 struct mm_struct *mm = current->mm;
1685 struct vm_area_struct *vma;
1686 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1688 /* Adjust search length to account for worst case alignment overhead */
1689 length = info->length + info->align_mask;
1690 if (length < info->length)
1694 * Adjust search limits by the desired length.
1695 * See implementation comment at top of unmapped_area().
1697 gap_end = info->high_limit;
1698 if (gap_end < length)
1700 high_limit = gap_end - length;
1702 if (info->low_limit > high_limit)
1704 low_limit = info->low_limit + length;
1706 /* Check highest gap, which does not precede any rbtree node */
1707 gap_start = mm->highest_vm_end;
1708 if (gap_start <= high_limit)
1711 /* Check if rbtree root looks promising */
1712 if (RB_EMPTY_ROOT(&mm->mm_rb))
1714 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1715 if (vma->rb_subtree_gap < length)
1719 /* Visit right subtree if it looks promising */
1720 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1721 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1722 struct vm_area_struct *right =
1723 rb_entry(vma->vm_rb.rb_right,
1724 struct vm_area_struct, vm_rb);
1725 if (right->rb_subtree_gap >= length) {
1732 /* Check if current node has a suitable gap */
1733 gap_end = vma->vm_start;
1734 if (gap_end < low_limit)
1736 if (gap_start <= high_limit && gap_end - gap_start >= length)
1739 /* Visit left subtree if it looks promising */
1740 if (vma->vm_rb.rb_left) {
1741 struct vm_area_struct *left =
1742 rb_entry(vma->vm_rb.rb_left,
1743 struct vm_area_struct, vm_rb);
1744 if (left->rb_subtree_gap >= length) {
1750 /* Go back up the rbtree to find next candidate node */
1752 struct rb_node *prev = &vma->vm_rb;
1753 if (!rb_parent(prev))
1755 vma = rb_entry(rb_parent(prev),
1756 struct vm_area_struct, vm_rb);
1757 if (prev == vma->vm_rb.rb_right) {
1758 gap_start = vma->vm_prev ?
1759 vma->vm_prev->vm_end : 0;
1766 /* We found a suitable gap. Clip it with the original high_limit. */
1767 if (gap_end > info->high_limit)
1768 gap_end = info->high_limit;
1771 /* Compute highest gap address at the desired alignment */
1772 gap_end -= info->length;
1773 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1775 VM_BUG_ON(gap_end < info->low_limit);
1776 VM_BUG_ON(gap_end < gap_start);
1780 /* Get an address range which is currently unmapped.
1781 * For shmat() with addr=0.
1783 * Ugly calling convention alert:
1784 * Return value with the low bits set means error value,
1786 * if (ret & ~PAGE_MASK)
1789 * This function "knows" that -ENOMEM has the bits set.
1791 #ifndef HAVE_ARCH_UNMAPPED_AREA
1793 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1794 unsigned long len, unsigned long pgoff, unsigned long flags)
1796 struct mm_struct *mm = current->mm;
1797 struct vm_area_struct *vma;
1798 struct vm_unmapped_area_info info;
1800 if (len > TASK_SIZE - mmap_min_addr)
1803 if (flags & MAP_FIXED)
1807 addr = PAGE_ALIGN(addr);
1808 vma = find_vma(mm, addr);
1809 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1810 (!vma || addr + len <= vma->vm_start))
1816 info.low_limit = mm->mmap_base;
1817 info.high_limit = TASK_SIZE;
1818 info.align_mask = 0;
1819 return vm_unmapped_area(&info);
1824 * This mmap-allocator allocates new areas top-down from below the
1825 * stack's low limit (the base):
1827 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1829 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1830 const unsigned long len, const unsigned long pgoff,
1831 const unsigned long flags)
1833 struct vm_area_struct *vma;
1834 struct mm_struct *mm = current->mm;
1835 unsigned long addr = addr0;
1836 struct vm_unmapped_area_info info;
1838 /* requested length too big for entire address space */
1839 if (len > TASK_SIZE - mmap_min_addr)
1842 if (flags & MAP_FIXED)
1845 /* requesting a specific address */
1847 addr = PAGE_ALIGN(addr);
1848 vma = find_vma(mm, addr);
1849 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1850 (!vma || addr + len <= vma->vm_start))
1854 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1856 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1857 info.high_limit = mm->mmap_base;
1858 info.align_mask = 0;
1859 addr = vm_unmapped_area(&info);
1862 * A failed mmap() very likely causes application failure,
1863 * so fall back to the bottom-up function here. This scenario
1864 * can happen with large stack limits and large mmap()
1867 if (offset_in_page(addr)) {
1868 VM_BUG_ON(addr != -ENOMEM);
1870 info.low_limit = TASK_UNMAPPED_BASE;
1871 info.high_limit = TASK_SIZE;
1872 addr = vm_unmapped_area(&info);
1880 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1881 unsigned long pgoff, unsigned long flags)
1883 unsigned long (*get_area)(struct file *, unsigned long,
1884 unsigned long, unsigned long, unsigned long);
1886 unsigned long error = arch_mmap_check(addr, len, flags);
1890 /* Careful about overflows.. */
1891 if (len > TASK_SIZE)
1894 get_area = current->mm->get_unmapped_area;
1895 if (file && file->f_op->get_unmapped_area)
1896 get_area = file->f_op->get_unmapped_area;
1897 addr = get_area(file, addr, len, pgoff, flags);
1898 if (IS_ERR_VALUE(addr))
1901 if (addr > TASK_SIZE - len)
1903 if (offset_in_page(addr))
1906 addr = arch_rebalance_pgtables(addr, len);
1907 error = security_mmap_addr(addr);
1908 return error ? error : addr;
1911 EXPORT_SYMBOL(get_unmapped_area);
1913 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1914 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1916 struct rb_node *rb_node;
1917 struct vm_area_struct *vma;
1919 /* Check the cache first. */
1920 vma = vmacache_find(mm, addr);
1924 rb_node = mm->mm_rb.rb_node;
1927 struct vm_area_struct *tmp;
1929 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1931 if (tmp->vm_end > addr) {
1933 if (tmp->vm_start <= addr)
1935 rb_node = rb_node->rb_left;
1937 rb_node = rb_node->rb_right;
1941 vmacache_update(addr, vma);
1945 EXPORT_SYMBOL(find_vma);
1948 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1950 struct vm_area_struct *
1951 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1952 struct vm_area_struct **pprev)
1954 struct vm_area_struct *vma;
1956 vma = find_vma(mm, addr);
1958 *pprev = vma->vm_prev;
1960 struct rb_node *rb_node = mm->mm_rb.rb_node;
1963 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1964 rb_node = rb_node->rb_right;
1971 * Verify that the stack growth is acceptable and
1972 * update accounting. This is shared with both the
1973 * grow-up and grow-down cases.
1975 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1977 struct mm_struct *mm = vma->vm_mm;
1978 struct rlimit *rlim = current->signal->rlim;
1979 unsigned long new_start, actual_size;
1981 /* address space limit tests */
1982 if (!may_expand_vm(mm, vma->vm_flags, grow))
1985 /* Stack limit test */
1987 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
1988 actual_size -= PAGE_SIZE;
1989 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1992 /* mlock limit tests */
1993 if (vma->vm_flags & VM_LOCKED) {
1994 unsigned long locked;
1995 unsigned long limit;
1996 locked = mm->locked_vm + grow;
1997 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1998 limit >>= PAGE_SHIFT;
1999 if (locked > limit && !capable(CAP_IPC_LOCK))
2003 /* Check to ensure the stack will not grow into a hugetlb-only region */
2004 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2006 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2010 * Overcommit.. This must be the final test, as it will
2011 * update security statistics.
2013 if (security_vm_enough_memory_mm(mm, grow))
2019 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2021 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2022 * vma is the last one with address > vma->vm_end. Have to extend vma.
2024 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2026 struct mm_struct *mm = vma->vm_mm;
2029 if (!(vma->vm_flags & VM_GROWSUP))
2032 /* Guard against wrapping around to address 0. */
2033 if (address < PAGE_ALIGN(address+4))
2034 address = PAGE_ALIGN(address+4);
2038 /* We must make sure the anon_vma is allocated. */
2039 if (unlikely(anon_vma_prepare(vma)))
2043 * vma->vm_start/vm_end cannot change under us because the caller
2044 * is required to hold the mmap_sem in read mode. We need the
2045 * anon_vma lock to serialize against concurrent expand_stacks.
2047 anon_vma_lock_write(vma->anon_vma);
2049 /* Somebody else might have raced and expanded it already */
2050 if (address > vma->vm_end) {
2051 unsigned long size, grow;
2053 size = address - vma->vm_start;
2054 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2057 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2058 error = acct_stack_growth(vma, size, grow);
2061 * vma_gap_update() doesn't support concurrent
2062 * updates, but we only hold a shared mmap_sem
2063 * lock here, so we need to protect against
2064 * concurrent vma expansions.
2065 * anon_vma_lock_write() doesn't help here, as
2066 * we don't guarantee that all growable vmas
2067 * in a mm share the same root anon vma.
2068 * So, we reuse mm->page_table_lock to guard
2069 * against concurrent vma expansions.
2071 spin_lock(&mm->page_table_lock);
2072 if (vma->vm_flags & VM_LOCKED)
2073 mm->locked_vm += grow;
2074 vm_stat_account(mm, vma->vm_flags, grow);
2075 anon_vma_interval_tree_pre_update_vma(vma);
2076 vma->vm_end = address;
2077 anon_vma_interval_tree_post_update_vma(vma);
2079 vma_gap_update(vma->vm_next);
2081 mm->highest_vm_end = address;
2082 spin_unlock(&mm->page_table_lock);
2084 perf_event_mmap(vma);
2088 anon_vma_unlock_write(vma->anon_vma);
2089 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2093 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2096 * vma is the first one with address < vma->vm_start. Have to extend vma.
2098 int expand_downwards(struct vm_area_struct *vma,
2099 unsigned long address)
2101 struct mm_struct *mm = vma->vm_mm;
2104 address &= PAGE_MASK;
2105 error = security_mmap_addr(address);
2109 /* We must make sure the anon_vma is allocated. */
2110 if (unlikely(anon_vma_prepare(vma)))
2114 * vma->vm_start/vm_end cannot change under us because the caller
2115 * is required to hold the mmap_sem in read mode. We need the
2116 * anon_vma lock to serialize against concurrent expand_stacks.
2118 anon_vma_lock_write(vma->anon_vma);
2120 /* Somebody else might have raced and expanded it already */
2121 if (address < vma->vm_start) {
2122 unsigned long size, grow;
2124 size = vma->vm_end - address;
2125 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2128 if (grow <= vma->vm_pgoff) {
2129 error = acct_stack_growth(vma, size, grow);
2132 * vma_gap_update() doesn't support concurrent
2133 * updates, but we only hold a shared mmap_sem
2134 * lock here, so we need to protect against
2135 * concurrent vma expansions.
2136 * anon_vma_lock_write() doesn't help here, as
2137 * we don't guarantee that all growable vmas
2138 * in a mm share the same root anon vma.
2139 * So, we reuse mm->page_table_lock to guard
2140 * against concurrent vma expansions.
2142 spin_lock(&mm->page_table_lock);
2143 if (vma->vm_flags & VM_LOCKED)
2144 mm->locked_vm += grow;
2145 vm_stat_account(mm, vma->vm_flags, grow);
2146 anon_vma_interval_tree_pre_update_vma(vma);
2147 vma->vm_start = address;
2148 vma->vm_pgoff -= grow;
2149 anon_vma_interval_tree_post_update_vma(vma);
2150 vma_gap_update(vma);
2151 spin_unlock(&mm->page_table_lock);
2153 perf_event_mmap(vma);
2157 anon_vma_unlock_write(vma->anon_vma);
2158 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2164 * Note how expand_stack() refuses to expand the stack all the way to
2165 * abut the next virtual mapping, *unless* that mapping itself is also
2166 * a stack mapping. We want to leave room for a guard page, after all
2167 * (the guard page itself is not added here, that is done by the
2168 * actual page faulting logic)
2170 * This matches the behavior of the guard page logic (see mm/memory.c:
2171 * check_stack_guard_page()), which only allows the guard page to be
2172 * removed under these circumstances.
2174 #ifdef CONFIG_STACK_GROWSUP
2175 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2177 struct vm_area_struct *next;
2179 address &= PAGE_MASK;
2180 next = vma->vm_next;
2181 if (next && next->vm_start == address + PAGE_SIZE) {
2182 if (!(next->vm_flags & VM_GROWSUP))
2185 return expand_upwards(vma, address);
2188 struct vm_area_struct *
2189 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2191 struct vm_area_struct *vma, *prev;
2194 vma = find_vma_prev(mm, addr, &prev);
2195 if (vma && (vma->vm_start <= addr))
2197 if (!prev || expand_stack(prev, addr))
2199 if (prev->vm_flags & VM_LOCKED)
2200 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2204 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2206 struct vm_area_struct *prev;
2208 address &= PAGE_MASK;
2209 prev = vma->vm_prev;
2210 if (prev && prev->vm_end == address) {
2211 if (!(prev->vm_flags & VM_GROWSDOWN))
2214 return expand_downwards(vma, address);
2217 struct vm_area_struct *
2218 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2220 struct vm_area_struct *vma;
2221 unsigned long start;
2224 vma = find_vma(mm, addr);
2227 if (vma->vm_start <= addr)
2229 if (!(vma->vm_flags & VM_GROWSDOWN))
2231 start = vma->vm_start;
2232 if (expand_stack(vma, addr))
2234 if (vma->vm_flags & VM_LOCKED)
2235 populate_vma_page_range(vma, addr, start, NULL);
2240 EXPORT_SYMBOL_GPL(find_extend_vma);
2243 * Ok - we have the memory areas we should free on the vma list,
2244 * so release them, and do the vma updates.
2246 * Called with the mm semaphore held.
2248 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2250 unsigned long nr_accounted = 0;
2252 /* Update high watermark before we lower total_vm */
2253 update_hiwater_vm(mm);
2255 long nrpages = vma_pages(vma);
2257 if (vma->vm_flags & VM_ACCOUNT)
2258 nr_accounted += nrpages;
2259 vm_stat_account(mm, vma->vm_flags, -nrpages);
2260 vma = remove_vma(vma);
2262 vm_unacct_memory(nr_accounted);
2267 * Get rid of page table information in the indicated region.
2269 * Called with the mm semaphore held.
2271 static void unmap_region(struct mm_struct *mm,
2272 struct vm_area_struct *vma, struct vm_area_struct *prev,
2273 unsigned long start, unsigned long end)
2275 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2276 struct mmu_gather tlb;
2279 tlb_gather_mmu(&tlb, mm, start, end);
2280 update_hiwater_rss(mm);
2281 unmap_vmas(&tlb, vma, start, end);
2282 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2283 next ? next->vm_start : USER_PGTABLES_CEILING);
2284 tlb_finish_mmu(&tlb, start, end);
2288 * Create a list of vma's touched by the unmap, removing them from the mm's
2289 * vma list as we go..
2292 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2293 struct vm_area_struct *prev, unsigned long end)
2295 struct vm_area_struct **insertion_point;
2296 struct vm_area_struct *tail_vma = NULL;
2298 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2299 vma->vm_prev = NULL;
2301 vma_rb_erase(vma, &mm->mm_rb);
2305 } while (vma && vma->vm_start < end);
2306 *insertion_point = vma;
2308 vma->vm_prev = prev;
2309 vma_gap_update(vma);
2311 mm->highest_vm_end = prev ? prev->vm_end : 0;
2312 tail_vma->vm_next = NULL;
2314 /* Kill the cache */
2315 vmacache_invalidate(mm);
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 vm_area_struct *new;
2328 if (is_vm_hugetlb_page(vma) && (addr &
2329 ~(huge_page_mask(hstate_vma(vma)))))
2332 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2336 /* most fields are the same, copy all, and then fixup */
2339 INIT_LIST_HEAD(&new->anon_vma_chain);
2344 new->vm_start = addr;
2345 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2348 err = vma_dup_policy(vma, new);
2352 err = anon_vma_clone(new, vma);
2357 get_file(new->vm_file);
2359 if (new->vm_ops && new->vm_ops->open)
2360 new->vm_ops->open(new);
2363 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2364 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2366 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2372 /* Clean everything up if vma_adjust failed. */
2373 if (new->vm_ops && new->vm_ops->close)
2374 new->vm_ops->close(new);
2377 unlink_anon_vmas(new);
2379 mpol_put(vma_policy(new));
2381 kmem_cache_free(vm_area_cachep, new);
2386 * Split a vma into two pieces at address 'addr', a new vma is allocated
2387 * either for the first part or the tail.
2389 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2390 unsigned long addr, int new_below)
2392 if (mm->map_count >= sysctl_max_map_count)
2395 return __split_vma(mm, vma, addr, new_below);
2398 /* Munmap is split into 2 main parts -- this part which finds
2399 * what needs doing, and the areas themselves, which do the
2400 * work. This now handles partial unmappings.
2401 * Jeremy Fitzhardinge <jeremy@goop.org>
2403 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2406 struct vm_area_struct *vma, *prev, *last;
2408 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2411 len = PAGE_ALIGN(len);
2415 /* Find the first overlapping VMA */
2416 vma = find_vma(mm, start);
2419 prev = vma->vm_prev;
2420 /* we have start < vma->vm_end */
2422 /* if it doesn't overlap, we have nothing.. */
2424 if (vma->vm_start >= end)
2428 * If we need to split any vma, do it now to save pain later.
2430 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2431 * unmapped vm_area_struct will remain in use: so lower split_vma
2432 * places tmp vma above, and higher split_vma places tmp vma below.
2434 if (start > vma->vm_start) {
2438 * Make sure that map_count on return from munmap() will
2439 * not exceed its limit; but let map_count go just above
2440 * its limit temporarily, to help free resources as expected.
2442 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2445 error = __split_vma(mm, vma, start, 0);
2451 /* Does it split the last one? */
2452 last = find_vma(mm, end);
2453 if (last && end > last->vm_start) {
2454 int error = __split_vma(mm, last, end, 1);
2458 vma = prev ? prev->vm_next : mm->mmap;
2461 * unlock any mlock()ed ranges before detaching vmas
2463 if (mm->locked_vm) {
2464 struct vm_area_struct *tmp = vma;
2465 while (tmp && tmp->vm_start < end) {
2466 if (tmp->vm_flags & VM_LOCKED) {
2467 mm->locked_vm -= vma_pages(tmp);
2468 munlock_vma_pages_all(tmp);
2475 * Remove the vma's, and unmap the actual pages
2477 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2478 unmap_region(mm, vma, prev, start, end);
2480 arch_unmap(mm, vma, start, end);
2482 /* Fix up all other VM information */
2483 remove_vma_list(mm, vma);
2488 int vm_munmap(unsigned long start, size_t len)
2491 struct mm_struct *mm = current->mm;
2493 down_write(&mm->mmap_sem);
2494 ret = do_munmap(mm, start, len);
2495 up_write(&mm->mmap_sem);
2498 EXPORT_SYMBOL(vm_munmap);
2500 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2502 profile_munmap(addr);
2503 return vm_munmap(addr, len);
2508 * Emulation of deprecated remap_file_pages() syscall.
2510 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2511 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2514 struct mm_struct *mm = current->mm;
2515 struct vm_area_struct *vma;
2516 unsigned long populate = 0;
2517 unsigned long ret = -EINVAL;
2520 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2521 current->comm, current->pid);
2525 start = start & PAGE_MASK;
2526 size = size & PAGE_MASK;
2528 if (start + size <= start)
2531 /* Does pgoff wrap? */
2532 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2535 down_write(&mm->mmap_sem);
2536 vma = find_vma(mm, start);
2538 if (!vma || !(vma->vm_flags & VM_SHARED))
2541 if (start < vma->vm_start)
2544 if (start + size > vma->vm_end) {
2545 struct vm_area_struct *next;
2547 for (next = vma->vm_next; next; next = next->vm_next) {
2548 /* hole between vmas ? */
2549 if (next->vm_start != next->vm_prev->vm_end)
2552 if (next->vm_file != vma->vm_file)
2555 if (next->vm_flags != vma->vm_flags)
2558 if (start + size <= next->vm_end)
2566 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2567 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2568 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2570 flags &= MAP_NONBLOCK;
2571 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2572 if (vma->vm_flags & VM_LOCKED) {
2573 struct vm_area_struct *tmp;
2574 flags |= MAP_LOCKED;
2576 /* drop PG_Mlocked flag for over-mapped range */
2577 for (tmp = vma; tmp->vm_start >= start + size;
2578 tmp = tmp->vm_next) {
2579 munlock_vma_pages_range(tmp,
2580 max(tmp->vm_start, start),
2581 min(tmp->vm_end, start + size));
2585 file = get_file(vma->vm_file);
2586 ret = do_mmap_pgoff(vma->vm_file, start, size,
2587 prot, flags, pgoff, &populate);
2590 up_write(&mm->mmap_sem);
2592 mm_populate(ret, populate);
2593 if (!IS_ERR_VALUE(ret))
2598 static inline void verify_mm_writelocked(struct mm_struct *mm)
2600 #ifdef CONFIG_DEBUG_VM
2601 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2603 up_read(&mm->mmap_sem);
2609 * this is really a simplified "do_mmap". it only handles
2610 * anonymous maps. eventually we may be able to do some
2611 * brk-specific accounting here.
2613 static unsigned long do_brk(unsigned long addr, unsigned long len)
2615 struct mm_struct *mm = current->mm;
2616 struct vm_area_struct *vma, *prev;
2617 unsigned long flags;
2618 struct rb_node **rb_link, *rb_parent;
2619 pgoff_t pgoff = addr >> PAGE_SHIFT;
2622 len = PAGE_ALIGN(len);
2626 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2628 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2629 if (offset_in_page(error))
2632 error = mlock_future_check(mm, mm->def_flags, len);
2637 * mm->mmap_sem is required to protect against another thread
2638 * changing the mappings in case we sleep.
2640 verify_mm_writelocked(mm);
2643 * Clear old maps. this also does some error checking for us
2645 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2647 if (do_munmap(mm, addr, len))
2651 /* Check against address space limits *after* clearing old maps... */
2652 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2655 if (mm->map_count > sysctl_max_map_count)
2658 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2661 /* Can we just expand an old private anonymous mapping? */
2662 vma = vma_merge(mm, prev, addr, addr + len, flags,
2663 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2668 * create a vma struct for an anonymous mapping
2670 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2672 vm_unacct_memory(len >> PAGE_SHIFT);
2676 INIT_LIST_HEAD(&vma->anon_vma_chain);
2678 vma->vm_start = addr;
2679 vma->vm_end = addr + len;
2680 vma->vm_pgoff = pgoff;
2681 vma->vm_flags = flags;
2682 vma->vm_page_prot = vm_get_page_prot(flags);
2683 vma_link(mm, vma, prev, rb_link, rb_parent);
2685 perf_event_mmap(vma);
2686 mm->total_vm += len >> PAGE_SHIFT;
2687 mm->data_vm += len >> PAGE_SHIFT;
2688 if (flags & VM_LOCKED)
2689 mm->locked_vm += (len >> PAGE_SHIFT);
2690 vma->vm_flags |= VM_SOFTDIRTY;
2694 unsigned long vm_brk(unsigned long addr, unsigned long len)
2696 struct mm_struct *mm = current->mm;
2700 down_write(&mm->mmap_sem);
2701 ret = do_brk(addr, len);
2702 populate = ((mm->def_flags & VM_LOCKED) != 0);
2703 up_write(&mm->mmap_sem);
2705 mm_populate(addr, len);
2708 EXPORT_SYMBOL(vm_brk);
2710 /* Release all mmaps. */
2711 void exit_mmap(struct mm_struct *mm)
2713 struct mmu_gather tlb;
2714 struct vm_area_struct *vma;
2715 unsigned long nr_accounted = 0;
2717 /* mm's last user has gone, and its about to be pulled down */
2718 mmu_notifier_release(mm);
2720 if (mm->locked_vm) {
2723 if (vma->vm_flags & VM_LOCKED)
2724 munlock_vma_pages_all(vma);
2732 if (!vma) /* Can happen if dup_mmap() received an OOM */
2737 tlb_gather_mmu(&tlb, mm, 0, -1);
2738 /* update_hiwater_rss(mm) here? but nobody should be looking */
2739 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2740 unmap_vmas(&tlb, vma, 0, -1);
2742 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2743 tlb_finish_mmu(&tlb, 0, -1);
2746 * Walk the list again, actually closing and freeing it,
2747 * with preemption enabled, without holding any MM locks.
2750 if (vma->vm_flags & VM_ACCOUNT)
2751 nr_accounted += vma_pages(vma);
2752 vma = remove_vma(vma);
2754 vm_unacct_memory(nr_accounted);
2757 /* Insert vm structure into process list sorted by address
2758 * and into the inode's i_mmap tree. If vm_file is non-NULL
2759 * then i_mmap_rwsem is taken here.
2761 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2763 struct vm_area_struct *prev;
2764 struct rb_node **rb_link, *rb_parent;
2766 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2767 &prev, &rb_link, &rb_parent))
2769 if ((vma->vm_flags & VM_ACCOUNT) &&
2770 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2774 * The vm_pgoff of a purely anonymous vma should be irrelevant
2775 * until its first write fault, when page's anon_vma and index
2776 * are set. But now set the vm_pgoff it will almost certainly
2777 * end up with (unless mremap moves it elsewhere before that
2778 * first wfault), so /proc/pid/maps tells a consistent story.
2780 * By setting it to reflect the virtual start address of the
2781 * vma, merges and splits can happen in a seamless way, just
2782 * using the existing file pgoff checks and manipulations.
2783 * Similarly in do_mmap_pgoff and in do_brk.
2785 if (vma_is_anonymous(vma)) {
2786 BUG_ON(vma->anon_vma);
2787 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2790 vma_link(mm, vma, prev, rb_link, rb_parent);
2795 * Copy the vma structure to a new location in the same mm,
2796 * prior to moving page table entries, to effect an mremap move.
2798 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2799 unsigned long addr, unsigned long len, pgoff_t pgoff,
2800 bool *need_rmap_locks)
2802 struct vm_area_struct *vma = *vmap;
2803 unsigned long vma_start = vma->vm_start;
2804 struct mm_struct *mm = vma->vm_mm;
2805 struct vm_area_struct *new_vma, *prev;
2806 struct rb_node **rb_link, *rb_parent;
2807 bool faulted_in_anon_vma = true;
2810 * If anonymous vma has not yet been faulted, update new pgoff
2811 * to match new location, to increase its chance of merging.
2813 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
2814 pgoff = addr >> PAGE_SHIFT;
2815 faulted_in_anon_vma = false;
2818 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2819 return NULL; /* should never get here */
2820 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2821 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
2822 vma->vm_userfaultfd_ctx);
2825 * Source vma may have been merged into new_vma
2827 if (unlikely(vma_start >= new_vma->vm_start &&
2828 vma_start < new_vma->vm_end)) {
2830 * The only way we can get a vma_merge with
2831 * self during an mremap is if the vma hasn't
2832 * been faulted in yet and we were allowed to
2833 * reset the dst vma->vm_pgoff to the
2834 * destination address of the mremap to allow
2835 * the merge to happen. mremap must change the
2836 * vm_pgoff linearity between src and dst vmas
2837 * (in turn preventing a vma_merge) to be
2838 * safe. It is only safe to keep the vm_pgoff
2839 * linear if there are no pages mapped yet.
2841 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2842 *vmap = vma = new_vma;
2844 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2846 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2850 new_vma->vm_start = addr;
2851 new_vma->vm_end = addr + len;
2852 new_vma->vm_pgoff = pgoff;
2853 if (vma_dup_policy(vma, new_vma))
2855 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2856 if (anon_vma_clone(new_vma, vma))
2857 goto out_free_mempol;
2858 if (new_vma->vm_file)
2859 get_file(new_vma->vm_file);
2860 if (new_vma->vm_ops && new_vma->vm_ops->open)
2861 new_vma->vm_ops->open(new_vma);
2862 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2863 *need_rmap_locks = false;
2868 mpol_put(vma_policy(new_vma));
2870 kmem_cache_free(vm_area_cachep, new_vma);
2876 * Return true if the calling process may expand its vm space by the passed
2879 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
2881 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
2884 if (is_data_mapping(flags) &&
2885 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
2886 if (ignore_rlimit_data)
2887 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Will be forbidden soon.\n",
2888 current->comm, current->pid,
2889 (mm->data_vm + npages) << PAGE_SHIFT,
2890 rlimit(RLIMIT_DATA));
2898 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
2900 mm->total_vm += npages;
2902 if (is_exec_mapping(flags))
2903 mm->exec_vm += npages;
2904 else if (is_stack_mapping(flags))
2905 mm->stack_vm += npages;
2906 else if (is_data_mapping(flags))
2907 mm->data_vm += npages;
2910 static int special_mapping_fault(struct vm_area_struct *vma,
2911 struct vm_fault *vmf);
2914 * Having a close hook prevents vma merging regardless of flags.
2916 static void special_mapping_close(struct vm_area_struct *vma)
2920 static const char *special_mapping_name(struct vm_area_struct *vma)
2922 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
2925 static const struct vm_operations_struct special_mapping_vmops = {
2926 .close = special_mapping_close,
2927 .fault = special_mapping_fault,
2928 .name = special_mapping_name,
2931 static const struct vm_operations_struct legacy_special_mapping_vmops = {
2932 .close = special_mapping_close,
2933 .fault = special_mapping_fault,
2936 static int special_mapping_fault(struct vm_area_struct *vma,
2937 struct vm_fault *vmf)
2940 struct page **pages;
2942 if (vma->vm_ops == &legacy_special_mapping_vmops) {
2943 pages = vma->vm_private_data;
2945 struct vm_special_mapping *sm = vma->vm_private_data;
2948 return sm->fault(sm, vma, vmf);
2953 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
2957 struct page *page = *pages;
2963 return VM_FAULT_SIGBUS;
2966 static struct vm_area_struct *__install_special_mapping(
2967 struct mm_struct *mm,
2968 unsigned long addr, unsigned long len,
2969 unsigned long vm_flags, void *priv,
2970 const struct vm_operations_struct *ops)
2973 struct vm_area_struct *vma;
2975 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2976 if (unlikely(vma == NULL))
2977 return ERR_PTR(-ENOMEM);
2979 INIT_LIST_HEAD(&vma->anon_vma_chain);
2981 vma->vm_start = addr;
2982 vma->vm_end = addr + len;
2984 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
2985 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2988 vma->vm_private_data = priv;
2990 ret = insert_vm_struct(mm, vma);
2994 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
2996 perf_event_mmap(vma);
3001 kmem_cache_free(vm_area_cachep, vma);
3002 return ERR_PTR(ret);
3006 * Called with mm->mmap_sem held for writing.
3007 * Insert a new vma covering the given region, with the given flags.
3008 * Its pages are supplied by the given array of struct page *.
3009 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3010 * The region past the last page supplied will always produce SIGBUS.
3011 * The array pointer and the pages it points to are assumed to stay alive
3012 * for as long as this mapping might exist.
3014 struct vm_area_struct *_install_special_mapping(
3015 struct mm_struct *mm,
3016 unsigned long addr, unsigned long len,
3017 unsigned long vm_flags, const struct vm_special_mapping *spec)
3019 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3020 &special_mapping_vmops);
3023 int install_special_mapping(struct mm_struct *mm,
3024 unsigned long addr, unsigned long len,
3025 unsigned long vm_flags, struct page **pages)
3027 struct vm_area_struct *vma = __install_special_mapping(
3028 mm, addr, len, vm_flags, (void *)pages,
3029 &legacy_special_mapping_vmops);
3031 return PTR_ERR_OR_ZERO(vma);
3034 static DEFINE_MUTEX(mm_all_locks_mutex);
3036 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3038 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3040 * The LSB of head.next can't change from under us
3041 * because we hold the mm_all_locks_mutex.
3043 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3045 * We can safely modify head.next after taking the
3046 * anon_vma->root->rwsem. If some other vma in this mm shares
3047 * the same anon_vma we won't take it again.
3049 * No need of atomic instructions here, head.next
3050 * can't change from under us thanks to the
3051 * anon_vma->root->rwsem.
3053 if (__test_and_set_bit(0, (unsigned long *)
3054 &anon_vma->root->rb_root.rb_node))
3059 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3061 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3063 * AS_MM_ALL_LOCKS can't change from under us because
3064 * we hold the mm_all_locks_mutex.
3066 * Operations on ->flags have to be atomic because
3067 * even if AS_MM_ALL_LOCKS is stable thanks to the
3068 * mm_all_locks_mutex, there may be other cpus
3069 * changing other bitflags in parallel to us.
3071 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3073 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3078 * This operation locks against the VM for all pte/vma/mm related
3079 * operations that could ever happen on a certain mm. This includes
3080 * vmtruncate, try_to_unmap, and all page faults.
3082 * The caller must take the mmap_sem in write mode before calling
3083 * mm_take_all_locks(). The caller isn't allowed to release the
3084 * mmap_sem until mm_drop_all_locks() returns.
3086 * mmap_sem in write mode is required in order to block all operations
3087 * that could modify pagetables and free pages without need of
3088 * altering the vma layout. It's also needed in write mode to avoid new
3089 * anon_vmas to be associated with existing vmas.
3091 * A single task can't take more than one mm_take_all_locks() in a row
3092 * or it would deadlock.
3094 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3095 * mapping->flags avoid to take the same lock twice, if more than one
3096 * vma in this mm is backed by the same anon_vma or address_space.
3098 * We take locks in following order, accordingly to comment at beginning
3100 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3102 * - all i_mmap_rwsem locks;
3103 * - all anon_vma->rwseml
3105 * We can take all locks within these types randomly because the VM code
3106 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3107 * mm_all_locks_mutex.
3109 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3110 * that may have to take thousand of locks.
3112 * mm_take_all_locks() can fail if it's interrupted by signals.
3114 int mm_take_all_locks(struct mm_struct *mm)
3116 struct vm_area_struct *vma;
3117 struct anon_vma_chain *avc;
3119 BUG_ON(down_read_trylock(&mm->mmap_sem));
3121 mutex_lock(&mm_all_locks_mutex);
3123 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3124 if (signal_pending(current))
3126 if (vma->vm_file && vma->vm_file->f_mapping &&
3127 is_vm_hugetlb_page(vma))
3128 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3131 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3132 if (signal_pending(current))
3134 if (vma->vm_file && vma->vm_file->f_mapping &&
3135 !is_vm_hugetlb_page(vma))
3136 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3139 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3140 if (signal_pending(current))
3143 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3144 vm_lock_anon_vma(mm, avc->anon_vma);
3150 mm_drop_all_locks(mm);
3154 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3156 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3158 * The LSB of head.next can't change to 0 from under
3159 * us because we hold the mm_all_locks_mutex.
3161 * We must however clear the bitflag before unlocking
3162 * the vma so the users using the anon_vma->rb_root will
3163 * never see our bitflag.
3165 * No need of atomic instructions here, head.next
3166 * can't change from under us until we release the
3167 * anon_vma->root->rwsem.
3169 if (!__test_and_clear_bit(0, (unsigned long *)
3170 &anon_vma->root->rb_root.rb_node))
3172 anon_vma_unlock_write(anon_vma);
3176 static void vm_unlock_mapping(struct address_space *mapping)
3178 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3180 * AS_MM_ALL_LOCKS can't change to 0 from under us
3181 * because we hold the mm_all_locks_mutex.
3183 i_mmap_unlock_write(mapping);
3184 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3191 * The mmap_sem cannot be released by the caller until
3192 * mm_drop_all_locks() returns.
3194 void mm_drop_all_locks(struct mm_struct *mm)
3196 struct vm_area_struct *vma;
3197 struct anon_vma_chain *avc;
3199 BUG_ON(down_read_trylock(&mm->mmap_sem));
3200 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3202 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3204 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3205 vm_unlock_anon_vma(avc->anon_vma);
3206 if (vma->vm_file && vma->vm_file->f_mapping)
3207 vm_unlock_mapping(vma->vm_file->f_mapping);
3210 mutex_unlock(&mm_all_locks_mutex);
3214 * initialise the VMA slab
3216 void __init mmap_init(void)
3220 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3225 * Initialise sysctl_user_reserve_kbytes.
3227 * This is intended to prevent a user from starting a single memory hogging
3228 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3231 * The default value is min(3% of free memory, 128MB)
3232 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3234 static int init_user_reserve(void)
3236 unsigned long free_kbytes;
3238 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3240 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3243 subsys_initcall(init_user_reserve);
3246 * Initialise sysctl_admin_reserve_kbytes.
3248 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3249 * to log in and kill a memory hogging process.
3251 * Systems with more than 256MB will reserve 8MB, enough to recover
3252 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3253 * only reserve 3% of free pages by default.
3255 static int init_admin_reserve(void)
3257 unsigned long free_kbytes;
3259 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3261 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3264 subsys_initcall(init_admin_reserve);
3267 * Reinititalise user and admin reserves if memory is added or removed.
3269 * The default user reserve max is 128MB, and the default max for the
3270 * admin reserve is 8MB. These are usually, but not always, enough to
3271 * enable recovery from a memory hogging process using login/sshd, a shell,
3272 * and tools like top. It may make sense to increase or even disable the
3273 * reserve depending on the existence of swap or variations in the recovery
3274 * tools. So, the admin may have changed them.
3276 * If memory is added and the reserves have been eliminated or increased above
3277 * the default max, then we'll trust the admin.
3279 * If memory is removed and there isn't enough free memory, then we
3280 * need to reset the reserves.
3282 * Otherwise keep the reserve set by the admin.
3284 static int reserve_mem_notifier(struct notifier_block *nb,
3285 unsigned long action, void *data)
3287 unsigned long tmp, free_kbytes;
3291 /* Default max is 128MB. Leave alone if modified by operator. */
3292 tmp = sysctl_user_reserve_kbytes;
3293 if (0 < tmp && tmp < (1UL << 17))
3294 init_user_reserve();
3296 /* Default max is 8MB. Leave alone if modified by operator. */
3297 tmp = sysctl_admin_reserve_kbytes;
3298 if (0 < tmp && tmp < (1UL << 13))
3299 init_admin_reserve();
3303 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3305 if (sysctl_user_reserve_kbytes > free_kbytes) {
3306 init_user_reserve();
3307 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3308 sysctl_user_reserve_kbytes);
3311 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3312 init_admin_reserve();
3313 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3314 sysctl_admin_reserve_kbytes);
3323 static struct notifier_block reserve_mem_nb = {
3324 .notifier_call = reserve_mem_notifier,
3327 static int __meminit init_reserve_notifier(void)
3329 if (register_hotmemory_notifier(&reserve_mem_nb))
3330 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3334 subsys_initcall(init_reserve_notifier);