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/sched/sysctl.h>
41 #include <linux/notifier.h>
42 #include <linux/memory.h>
43 #include <linux/printk.h>
45 #include <asm/uaccess.h>
46 #include <asm/cacheflush.h>
48 #include <asm/mmu_context.h>
52 #ifndef arch_mmap_check
53 #define arch_mmap_check(addr, len, flags) (0)
56 #ifndef arch_rebalance_pgtables
57 #define arch_rebalance_pgtables(addr, len) (addr)
60 static void unmap_region(struct mm_struct *mm,
61 struct vm_area_struct *vma, struct vm_area_struct *prev,
62 unsigned long start, unsigned long end);
64 /* description of effects of mapping type and prot in current implementation.
65 * this is due to the limited x86 page protection hardware. The expected
66 * behavior is in parens:
69 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
70 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
71 * w: (no) no w: (no) no w: (yes) yes w: (no) no
72 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
74 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
75 * w: (no) no w: (no) no w: (copy) copy w: (no) no
76 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
79 pgprot_t protection_map[16] = {
80 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
81 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
84 pgprot_t vm_get_page_prot(unsigned long vm_flags)
86 return __pgprot(pgprot_val(protection_map[vm_flags &
87 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
88 pgprot_val(arch_vm_get_page_prot(vm_flags)));
90 EXPORT_SYMBOL(vm_get_page_prot);
92 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
93 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
94 unsigned long sysctl_overcommit_kbytes __read_mostly;
95 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
96 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
97 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
99 * Make sure vm_committed_as in one cacheline and not cacheline shared with
100 * other variables. It can be updated by several CPUs frequently.
102 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
105 * The global memory commitment made in the system can be a metric
106 * that can be used to drive ballooning decisions when Linux is hosted
107 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
108 * balancing memory across competing virtual machines that are hosted.
109 * Several metrics drive this policy engine including the guest reported
112 unsigned long vm_memory_committed(void)
114 return percpu_counter_read_positive(&vm_committed_as);
116 EXPORT_SYMBOL_GPL(vm_memory_committed);
119 * Check that a process has enough memory to allocate a new virtual
120 * mapping. 0 means there is enough memory for the allocation to
121 * succeed and -ENOMEM implies there is not.
123 * We currently support three overcommit policies, which are set via the
124 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
126 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
127 * Additional code 2002 Jul 20 by Robert Love.
129 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
131 * Note this is a helper function intended to be used by LSMs which
132 * wish to use this logic.
134 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
136 unsigned long free, allowed, reserve;
138 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
139 -(s64)vm_committed_as_batch * num_online_cpus(),
140 "memory commitment underflow");
142 vm_acct_memory(pages);
145 * Sometimes we want to use more memory than we have
147 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
150 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
151 free = global_page_state(NR_FREE_PAGES);
152 free += global_page_state(NR_FILE_PAGES);
155 * shmem pages shouldn't be counted as free in this
156 * case, they can't be purged, only swapped out, and
157 * that won't affect the overall amount of available
158 * memory in the system.
160 free -= global_page_state(NR_SHMEM);
162 free += get_nr_swap_pages();
165 * Any slabs which are created with the
166 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
167 * which are reclaimable, under pressure. The dentry
168 * cache and most inode caches should fall into this
170 free += global_page_state(NR_SLAB_RECLAIMABLE);
173 * Leave reserved pages. The pages are not for anonymous pages.
175 if (free <= totalreserve_pages)
178 free -= totalreserve_pages;
181 * Reserve some for root
184 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
192 allowed = vm_commit_limit();
194 * Reserve some for root
197 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
200 * Don't let a single process grow so big a user can't recover
203 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
204 allowed -= min(mm->total_vm / 32, reserve);
207 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
210 vm_unacct_memory(pages);
216 * Requires inode->i_mapping->i_mmap_mutex
218 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
219 struct file *file, struct address_space *mapping)
221 if (vma->vm_flags & VM_DENYWRITE)
222 atomic_inc(&file_inode(file)->i_writecount);
223 if (vma->vm_flags & VM_SHARED)
224 mapping_unmap_writable(mapping);
226 flush_dcache_mmap_lock(mapping);
227 if (unlikely(vma->vm_flags & VM_NONLINEAR))
228 list_del_init(&vma->shared.nonlinear);
230 vma_interval_tree_remove(vma, &mapping->i_mmap);
231 flush_dcache_mmap_unlock(mapping);
235 * Unlink a file-based vm structure from its interval tree, to hide
236 * vma from rmap and vmtruncate before freeing its page tables.
238 void unlink_file_vma(struct vm_area_struct *vma)
240 struct file *file = vma->vm_file;
243 struct address_space *mapping = file->f_mapping;
244 mutex_lock(&mapping->i_mmap_mutex);
245 __remove_shared_vm_struct(vma, file, mapping);
246 mutex_unlock(&mapping->i_mmap_mutex);
251 * Close a vm structure and free it, returning the next.
253 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
255 struct vm_area_struct *next = vma->vm_next;
258 if (vma->vm_ops && vma->vm_ops->close)
259 vma->vm_ops->close(vma);
262 mpol_put(vma_policy(vma));
263 kmem_cache_free(vm_area_cachep, vma);
267 static unsigned long do_brk(unsigned long addr, unsigned long len);
269 SYSCALL_DEFINE1(brk, unsigned long, brk)
271 unsigned long retval;
272 unsigned long newbrk, oldbrk;
273 struct mm_struct *mm = current->mm;
274 unsigned long min_brk;
277 down_write(&mm->mmap_sem);
279 #ifdef CONFIG_COMPAT_BRK
281 * CONFIG_COMPAT_BRK can still be overridden by setting
282 * randomize_va_space to 2, which will still cause mm->start_brk
283 * to be arbitrarily shifted
285 if (current->brk_randomized)
286 min_brk = mm->start_brk;
288 min_brk = mm->end_data;
290 min_brk = mm->start_brk;
296 * Check against rlimit here. If this check is done later after the test
297 * of oldbrk with newbrk then it can escape the test and let the data
298 * segment grow beyond its set limit the in case where the limit is
299 * not page aligned -Ram Gupta
301 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
302 mm->end_data, mm->start_data))
305 newbrk = PAGE_ALIGN(brk);
306 oldbrk = PAGE_ALIGN(mm->brk);
307 if (oldbrk == newbrk)
310 /* Always allow shrinking brk. */
311 if (brk <= mm->brk) {
312 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
317 /* Check against existing mmap mappings. */
318 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
321 /* Ok, looks good - let it rip. */
322 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
327 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
328 up_write(&mm->mmap_sem);
330 mm_populate(oldbrk, newbrk - oldbrk);
335 up_write(&mm->mmap_sem);
339 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
341 unsigned long max, subtree_gap;
344 max -= vma->vm_prev->vm_end;
345 if (vma->vm_rb.rb_left) {
346 subtree_gap = rb_entry(vma->vm_rb.rb_left,
347 struct vm_area_struct, vm_rb)->rb_subtree_gap;
348 if (subtree_gap > max)
351 if (vma->vm_rb.rb_right) {
352 subtree_gap = rb_entry(vma->vm_rb.rb_right,
353 struct vm_area_struct, vm_rb)->rb_subtree_gap;
354 if (subtree_gap > max)
360 #ifdef CONFIG_DEBUG_VM_RB
361 static int browse_rb(struct rb_root *root)
363 int i = 0, j, bug = 0;
364 struct rb_node *nd, *pn = NULL;
365 unsigned long prev = 0, pend = 0;
367 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
368 struct vm_area_struct *vma;
369 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
370 if (vma->vm_start < prev) {
371 pr_emerg("vm_start %lx < prev %lx\n",
372 vma->vm_start, prev);
375 if (vma->vm_start < pend) {
376 pr_emerg("vm_start %lx < pend %lx\n",
377 vma->vm_start, pend);
380 if (vma->vm_start > vma->vm_end) {
381 pr_emerg("vm_start %lx > vm_end %lx\n",
382 vma->vm_start, vma->vm_end);
385 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
386 pr_emerg("free gap %lx, correct %lx\n",
388 vma_compute_subtree_gap(vma));
393 prev = vma->vm_start;
397 for (nd = pn; nd; nd = rb_prev(nd))
400 pr_emerg("backwards %d, forwards %d\n", j, i);
406 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
410 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
411 struct vm_area_struct *vma;
412 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
413 VM_BUG_ON_VMA(vma != ignore &&
414 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
419 static void validate_mm(struct mm_struct *mm)
423 unsigned long highest_address = 0;
424 struct vm_area_struct *vma = mm->mmap;
427 struct anon_vma_chain *avc;
429 vma_lock_anon_vma(vma);
430 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
431 anon_vma_interval_tree_verify(avc);
432 vma_unlock_anon_vma(vma);
433 highest_address = vma->vm_end;
437 if (i != mm->map_count) {
438 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
441 if (highest_address != mm->highest_vm_end) {
442 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
443 mm->highest_vm_end, highest_address);
446 i = browse_rb(&mm->mm_rb);
447 if (i != mm->map_count) {
449 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
452 VM_BUG_ON_MM(bug, mm);
455 #define validate_mm_rb(root, ignore) do { } while (0)
456 #define validate_mm(mm) do { } while (0)
459 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
460 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
463 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
464 * vma->vm_prev->vm_end values changed, without modifying the vma's position
467 static void vma_gap_update(struct vm_area_struct *vma)
470 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
471 * function that does exacltly what we want.
473 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
476 static inline void vma_rb_insert(struct vm_area_struct *vma,
477 struct rb_root *root)
479 /* All rb_subtree_gap values must be consistent prior to insertion */
480 validate_mm_rb(root, NULL);
482 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
485 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
488 * All rb_subtree_gap values must be consistent prior to erase,
489 * with the possible exception of the vma being erased.
491 validate_mm_rb(root, vma);
494 * Note rb_erase_augmented is a fairly large inline function,
495 * so make sure we instantiate it only once with our desired
496 * augmented rbtree callbacks.
498 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
502 * vma has some anon_vma assigned, and is already inserted on that
503 * anon_vma's interval trees.
505 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
506 * vma must be removed from the anon_vma's interval trees using
507 * anon_vma_interval_tree_pre_update_vma().
509 * After the update, the vma will be reinserted using
510 * anon_vma_interval_tree_post_update_vma().
512 * The entire update must be protected by exclusive mmap_sem and by
513 * the root anon_vma's mutex.
516 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
518 struct anon_vma_chain *avc;
520 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
521 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
525 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
527 struct anon_vma_chain *avc;
529 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
530 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
533 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
534 unsigned long end, struct vm_area_struct **pprev,
535 struct rb_node ***rb_link, struct rb_node **rb_parent)
537 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
539 __rb_link = &mm->mm_rb.rb_node;
540 rb_prev = __rb_parent = NULL;
543 struct vm_area_struct *vma_tmp;
545 __rb_parent = *__rb_link;
546 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
548 if (vma_tmp->vm_end > addr) {
549 /* Fail if an existing vma overlaps the area */
550 if (vma_tmp->vm_start < end)
552 __rb_link = &__rb_parent->rb_left;
554 rb_prev = __rb_parent;
555 __rb_link = &__rb_parent->rb_right;
561 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
562 *rb_link = __rb_link;
563 *rb_parent = __rb_parent;
567 static unsigned long count_vma_pages_range(struct mm_struct *mm,
568 unsigned long addr, unsigned long end)
570 unsigned long nr_pages = 0;
571 struct vm_area_struct *vma;
573 /* Find first overlaping mapping */
574 vma = find_vma_intersection(mm, addr, end);
578 nr_pages = (min(end, vma->vm_end) -
579 max(addr, vma->vm_start)) >> PAGE_SHIFT;
581 /* Iterate over the rest of the overlaps */
582 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
583 unsigned long overlap_len;
585 if (vma->vm_start > end)
588 overlap_len = min(end, vma->vm_end) - vma->vm_start;
589 nr_pages += overlap_len >> PAGE_SHIFT;
595 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
596 struct rb_node **rb_link, struct rb_node *rb_parent)
598 /* Update tracking information for the gap following the new vma. */
600 vma_gap_update(vma->vm_next);
602 mm->highest_vm_end = vma->vm_end;
605 * vma->vm_prev wasn't known when we followed the rbtree to find the
606 * correct insertion point for that vma. As a result, we could not
607 * update the vma vm_rb parents rb_subtree_gap values on the way down.
608 * So, we first insert the vma with a zero rb_subtree_gap value
609 * (to be consistent with what we did on the way down), and then
610 * immediately update the gap to the correct value. Finally we
611 * rebalance the rbtree after all augmented values have been set.
613 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
614 vma->rb_subtree_gap = 0;
616 vma_rb_insert(vma, &mm->mm_rb);
619 static void __vma_link_file(struct vm_area_struct *vma)
625 struct address_space *mapping = file->f_mapping;
627 if (vma->vm_flags & VM_DENYWRITE)
628 atomic_dec(&file_inode(file)->i_writecount);
629 if (vma->vm_flags & VM_SHARED)
630 atomic_inc(&mapping->i_mmap_writable);
632 flush_dcache_mmap_lock(mapping);
633 if (unlikely(vma->vm_flags & VM_NONLINEAR))
634 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
636 vma_interval_tree_insert(vma, &mapping->i_mmap);
637 flush_dcache_mmap_unlock(mapping);
642 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
643 struct vm_area_struct *prev, struct rb_node **rb_link,
644 struct rb_node *rb_parent)
646 __vma_link_list(mm, vma, prev, rb_parent);
647 __vma_link_rb(mm, vma, rb_link, rb_parent);
650 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
651 struct vm_area_struct *prev, struct rb_node **rb_link,
652 struct rb_node *rb_parent)
654 struct address_space *mapping = NULL;
657 mapping = vma->vm_file->f_mapping;
658 mutex_lock(&mapping->i_mmap_mutex);
661 __vma_link(mm, vma, prev, rb_link, rb_parent);
662 __vma_link_file(vma);
665 mutex_unlock(&mapping->i_mmap_mutex);
672 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
673 * mm's list and rbtree. It has already been inserted into the interval tree.
675 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
677 struct vm_area_struct *prev;
678 struct rb_node **rb_link, *rb_parent;
680 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
681 &prev, &rb_link, &rb_parent))
683 __vma_link(mm, vma, prev, rb_link, rb_parent);
688 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
689 struct vm_area_struct *prev)
691 struct vm_area_struct *next;
693 vma_rb_erase(vma, &mm->mm_rb);
694 prev->vm_next = next = vma->vm_next;
696 next->vm_prev = prev;
699 vmacache_invalidate(mm);
703 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
704 * is already present in an i_mmap tree without adjusting the tree.
705 * The following helper function should be used when such adjustments
706 * are necessary. The "insert" vma (if any) is to be inserted
707 * before we drop the necessary locks.
709 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
710 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
712 struct mm_struct *mm = vma->vm_mm;
713 struct vm_area_struct *next = vma->vm_next;
714 struct vm_area_struct *importer = NULL;
715 struct address_space *mapping = NULL;
716 struct rb_root *root = NULL;
717 struct anon_vma *anon_vma = NULL;
718 struct file *file = vma->vm_file;
719 bool start_changed = false, end_changed = false;
720 long adjust_next = 0;
723 if (next && !insert) {
724 struct vm_area_struct *exporter = NULL;
726 if (end >= next->vm_end) {
728 * vma expands, overlapping all the next, and
729 * perhaps the one after too (mprotect case 6).
731 again: remove_next = 1 + (end > next->vm_end);
735 } else if (end > next->vm_start) {
737 * vma expands, overlapping part of the next:
738 * mprotect case 5 shifting the boundary up.
740 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
743 } else if (end < vma->vm_end) {
745 * vma shrinks, and !insert tells it's not
746 * split_vma inserting another: so it must be
747 * mprotect case 4 shifting the boundary down.
749 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
755 * Easily overlooked: when mprotect shifts the boundary,
756 * make sure the expanding vma has anon_vma set if the
757 * shrinking vma had, to cover any anon pages imported.
759 if (exporter && exporter->anon_vma && !importer->anon_vma) {
760 if (anon_vma_clone(importer, exporter))
762 importer->anon_vma = exporter->anon_vma;
767 mapping = file->f_mapping;
768 if (!(vma->vm_flags & VM_NONLINEAR)) {
769 root = &mapping->i_mmap;
770 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
773 uprobe_munmap(next, next->vm_start,
777 mutex_lock(&mapping->i_mmap_mutex);
780 * Put into interval tree now, so instantiated pages
781 * are visible to arm/parisc __flush_dcache_page
782 * throughout; but we cannot insert into address
783 * space until vma start or end is updated.
785 __vma_link_file(insert);
789 vma_adjust_trans_huge(vma, start, end, adjust_next);
791 anon_vma = vma->anon_vma;
792 if (!anon_vma && adjust_next)
793 anon_vma = next->anon_vma;
795 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
796 anon_vma != next->anon_vma, next);
797 anon_vma_lock_write(anon_vma);
798 anon_vma_interval_tree_pre_update_vma(vma);
800 anon_vma_interval_tree_pre_update_vma(next);
804 flush_dcache_mmap_lock(mapping);
805 vma_interval_tree_remove(vma, root);
807 vma_interval_tree_remove(next, root);
810 if (start != vma->vm_start) {
811 vma->vm_start = start;
812 start_changed = true;
814 if (end != vma->vm_end) {
818 vma->vm_pgoff = pgoff;
820 next->vm_start += adjust_next << PAGE_SHIFT;
821 next->vm_pgoff += adjust_next;
826 vma_interval_tree_insert(next, root);
827 vma_interval_tree_insert(vma, root);
828 flush_dcache_mmap_unlock(mapping);
833 * vma_merge has merged next into vma, and needs
834 * us to remove next before dropping the locks.
836 __vma_unlink(mm, next, vma);
838 __remove_shared_vm_struct(next, file, mapping);
841 * split_vma has split insert from vma, and needs
842 * us to insert it before dropping the locks
843 * (it may either follow vma or precede it).
845 __insert_vm_struct(mm, insert);
851 mm->highest_vm_end = end;
852 else if (!adjust_next)
853 vma_gap_update(next);
858 anon_vma_interval_tree_post_update_vma(vma);
860 anon_vma_interval_tree_post_update_vma(next);
861 anon_vma_unlock_write(anon_vma);
864 mutex_unlock(&mapping->i_mmap_mutex);
875 uprobe_munmap(next, next->vm_start, next->vm_end);
879 anon_vma_merge(vma, next);
881 mpol_put(vma_policy(next));
882 kmem_cache_free(vm_area_cachep, next);
884 * In mprotect's case 6 (see comments on vma_merge),
885 * we must remove another next too. It would clutter
886 * up the code too much to do both in one go.
889 if (remove_next == 2)
892 vma_gap_update(next);
894 mm->highest_vm_end = end;
905 * If the vma has a ->close operation then the driver probably needs to release
906 * per-vma resources, so we don't attempt to merge those.
908 static inline int is_mergeable_vma(struct vm_area_struct *vma,
909 struct file *file, unsigned long vm_flags)
912 * VM_SOFTDIRTY should not prevent from VMA merging, if we
913 * match the flags but dirty bit -- the caller should mark
914 * merged VMA as dirty. If dirty bit won't be excluded from
915 * comparison, we increase pressue on the memory system forcing
916 * the kernel to generate new VMAs when old one could be
919 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
921 if (vma->vm_file != file)
923 if (vma->vm_ops && vma->vm_ops->close)
928 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
929 struct anon_vma *anon_vma2,
930 struct vm_area_struct *vma)
933 * The list_is_singular() test is to avoid merging VMA cloned from
934 * parents. This can improve scalability caused by anon_vma lock.
936 if ((!anon_vma1 || !anon_vma2) && (!vma ||
937 list_is_singular(&vma->anon_vma_chain)))
939 return anon_vma1 == anon_vma2;
943 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
944 * in front of (at a lower virtual address and file offset than) the vma.
946 * We cannot merge two vmas if they have differently assigned (non-NULL)
947 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
949 * We don't check here for the merged mmap wrapping around the end of pagecache
950 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
951 * wrap, nor mmaps which cover the final page at index -1UL.
954 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
955 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
957 if (is_mergeable_vma(vma, file, vm_flags) &&
958 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
959 if (vma->vm_pgoff == vm_pgoff)
966 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
967 * beyond (at a higher virtual address and file offset than) the vma.
969 * We cannot merge two vmas if they have differently assigned (non-NULL)
970 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
973 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
974 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
976 if (is_mergeable_vma(vma, file, vm_flags) &&
977 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
979 vm_pglen = vma_pages(vma);
980 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
987 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
988 * whether that can be merged with its predecessor or its successor.
989 * Or both (it neatly fills a hole).
991 * In most cases - when called for mmap, brk or mremap - [addr,end) is
992 * certain not to be mapped by the time vma_merge is called; but when
993 * called for mprotect, it is certain to be already mapped (either at
994 * an offset within prev, or at the start of next), and the flags of
995 * this area are about to be changed to vm_flags - and the no-change
996 * case has already been eliminated.
998 * The following mprotect cases have to be considered, where AAAA is
999 * the area passed down from mprotect_fixup, never extending beyond one
1000 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1002 * AAAA AAAA AAAA AAAA
1003 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1004 * cannot merge might become might become might become
1005 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1006 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1007 * mremap move: PPPPNNNNNNNN 8
1009 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1010 * might become case 1 below case 2 below case 3 below
1012 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1013 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1015 struct vm_area_struct *vma_merge(struct mm_struct *mm,
1016 struct vm_area_struct *prev, unsigned long addr,
1017 unsigned long end, unsigned long vm_flags,
1018 struct anon_vma *anon_vma, struct file *file,
1019 pgoff_t pgoff, struct mempolicy *policy)
1021 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1022 struct vm_area_struct *area, *next;
1026 * We later require that vma->vm_flags == vm_flags,
1027 * so this tests vma->vm_flags & VM_SPECIAL, too.
1029 if (vm_flags & VM_SPECIAL)
1033 next = prev->vm_next;
1037 if (next && next->vm_end == end) /* cases 6, 7, 8 */
1038 next = next->vm_next;
1041 * Can it merge with the predecessor?
1043 if (prev && prev->vm_end == addr &&
1044 mpol_equal(vma_policy(prev), policy) &&
1045 can_vma_merge_after(prev, vm_flags,
1046 anon_vma, file, pgoff)) {
1048 * OK, it can. Can we now merge in the successor as well?
1050 if (next && end == next->vm_start &&
1051 mpol_equal(policy, vma_policy(next)) &&
1052 can_vma_merge_before(next, vm_flags,
1053 anon_vma, file, pgoff+pglen) &&
1054 is_mergeable_anon_vma(prev->anon_vma,
1055 next->anon_vma, NULL)) {
1057 err = vma_adjust(prev, prev->vm_start,
1058 next->vm_end, prev->vm_pgoff, NULL);
1059 } else /* cases 2, 5, 7 */
1060 err = vma_adjust(prev, prev->vm_start,
1061 end, prev->vm_pgoff, NULL);
1064 khugepaged_enter_vma_merge(prev);
1069 * Can this new request be merged in front of next?
1071 if (next && end == next->vm_start &&
1072 mpol_equal(policy, vma_policy(next)) &&
1073 can_vma_merge_before(next, vm_flags,
1074 anon_vma, file, pgoff+pglen)) {
1075 if (prev && addr < prev->vm_end) /* case 4 */
1076 err = vma_adjust(prev, prev->vm_start,
1077 addr, prev->vm_pgoff, NULL);
1078 else /* cases 3, 8 */
1079 err = vma_adjust(area, addr, next->vm_end,
1080 next->vm_pgoff - pglen, NULL);
1083 khugepaged_enter_vma_merge(area);
1091 * Rough compatbility check to quickly see if it's even worth looking
1092 * at sharing an anon_vma.
1094 * They need to have the same vm_file, and the flags can only differ
1095 * in things that mprotect may change.
1097 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1098 * we can merge the two vma's. For example, we refuse to merge a vma if
1099 * there is a vm_ops->close() function, because that indicates that the
1100 * driver is doing some kind of reference counting. But that doesn't
1101 * really matter for the anon_vma sharing case.
1103 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1105 return a->vm_end == b->vm_start &&
1106 mpol_equal(vma_policy(a), vma_policy(b)) &&
1107 a->vm_file == b->vm_file &&
1108 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1109 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1113 * Do some basic sanity checking to see if we can re-use the anon_vma
1114 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1115 * the same as 'old', the other will be the new one that is trying
1116 * to share the anon_vma.
1118 * NOTE! This runs with mm_sem held for reading, so it is possible that
1119 * the anon_vma of 'old' is concurrently in the process of being set up
1120 * by another page fault trying to merge _that_. But that's ok: if it
1121 * is being set up, that automatically means that it will be a singleton
1122 * acceptable for merging, so we can do all of this optimistically. But
1123 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
1125 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1126 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1127 * is to return an anon_vma that is "complex" due to having gone through
1130 * We also make sure that the two vma's are compatible (adjacent,
1131 * and with the same memory policies). That's all stable, even with just
1132 * a read lock on the mm_sem.
1134 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1136 if (anon_vma_compatible(a, b)) {
1137 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
1139 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1146 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1147 * neighbouring vmas for a suitable anon_vma, before it goes off
1148 * to allocate a new anon_vma. It checks because a repetitive
1149 * sequence of mprotects and faults may otherwise lead to distinct
1150 * anon_vmas being allocated, preventing vma merge in subsequent
1153 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1155 struct anon_vma *anon_vma;
1156 struct vm_area_struct *near;
1158 near = vma->vm_next;
1162 anon_vma = reusable_anon_vma(near, vma, near);
1166 near = vma->vm_prev;
1170 anon_vma = reusable_anon_vma(near, near, vma);
1175 * There's no absolute need to look only at touching neighbours:
1176 * we could search further afield for "compatible" anon_vmas.
1177 * But it would probably just be a waste of time searching,
1178 * or lead to too many vmas hanging off the same anon_vma.
1179 * We're trying to allow mprotect remerging later on,
1180 * not trying to minimize memory used for anon_vmas.
1185 #ifdef CONFIG_PROC_FS
1186 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1187 struct file *file, long pages)
1189 const unsigned long stack_flags
1190 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1192 mm->total_vm += pages;
1195 mm->shared_vm += pages;
1196 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1197 mm->exec_vm += pages;
1198 } else if (flags & stack_flags)
1199 mm->stack_vm += pages;
1201 #endif /* CONFIG_PROC_FS */
1204 * If a hint addr is less than mmap_min_addr change hint to be as
1205 * low as possible but still greater than mmap_min_addr
1207 static inline unsigned long round_hint_to_min(unsigned long hint)
1210 if (((void *)hint != NULL) &&
1211 (hint < mmap_min_addr))
1212 return PAGE_ALIGN(mmap_min_addr);
1216 static inline int mlock_future_check(struct mm_struct *mm,
1217 unsigned long flags,
1220 unsigned long locked, lock_limit;
1222 /* mlock MCL_FUTURE? */
1223 if (flags & VM_LOCKED) {
1224 locked = len >> PAGE_SHIFT;
1225 locked += mm->locked_vm;
1226 lock_limit = rlimit(RLIMIT_MEMLOCK);
1227 lock_limit >>= PAGE_SHIFT;
1228 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1235 * The caller must hold down_write(¤t->mm->mmap_sem).
1238 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1239 unsigned long len, unsigned long prot,
1240 unsigned long flags, unsigned long pgoff,
1241 unsigned long *populate)
1243 struct mm_struct *mm = current->mm;
1244 vm_flags_t vm_flags;
1249 * Does the application expect PROT_READ to imply PROT_EXEC?
1251 * (the exception is when the underlying filesystem is noexec
1252 * mounted, in which case we dont add PROT_EXEC.)
1254 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1255 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1261 if (!(flags & MAP_FIXED))
1262 addr = round_hint_to_min(addr);
1264 /* Careful about overflows.. */
1265 len = PAGE_ALIGN(len);
1269 /* offset overflow? */
1270 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1273 /* Too many mappings? */
1274 if (mm->map_count > sysctl_max_map_count)
1277 /* Obtain the address to map to. we verify (or select) it and ensure
1278 * that it represents a valid section of the address space.
1280 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1281 if (addr & ~PAGE_MASK)
1284 /* Do simple checking here so the lower-level routines won't have
1285 * to. we assume access permissions have been handled by the open
1286 * of the memory object, so we don't do any here.
1288 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1289 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1291 if (flags & MAP_LOCKED)
1292 if (!can_do_mlock())
1295 if (mlock_future_check(mm, vm_flags, len))
1299 struct inode *inode = file_inode(file);
1301 switch (flags & MAP_TYPE) {
1303 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1307 * Make sure we don't allow writing to an append-only
1310 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1314 * Make sure there are no mandatory locks on the file.
1316 if (locks_verify_locked(file))
1319 vm_flags |= VM_SHARED | VM_MAYSHARE;
1320 if (!(file->f_mode & FMODE_WRITE))
1321 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1325 if (!(file->f_mode & FMODE_READ))
1327 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1328 if (vm_flags & VM_EXEC)
1330 vm_flags &= ~VM_MAYEXEC;
1333 if (!file->f_op->mmap)
1335 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1343 switch (flags & MAP_TYPE) {
1345 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1351 vm_flags |= VM_SHARED | VM_MAYSHARE;
1355 * Set pgoff according to addr for anon_vma.
1357 pgoff = addr >> PAGE_SHIFT;
1365 * Set 'VM_NORESERVE' if we should not account for the
1366 * memory use of this mapping.
1368 if (flags & MAP_NORESERVE) {
1369 /* We honor MAP_NORESERVE if allowed to overcommit */
1370 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1371 vm_flags |= VM_NORESERVE;
1373 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1374 if (file && is_file_hugepages(file))
1375 vm_flags |= VM_NORESERVE;
1378 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1379 if (!IS_ERR_VALUE(addr) &&
1380 ((vm_flags & VM_LOCKED) ||
1381 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1386 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1387 unsigned long, prot, unsigned long, flags,
1388 unsigned long, fd, unsigned long, pgoff)
1390 struct file *file = NULL;
1391 unsigned long retval = -EBADF;
1393 if (!(flags & MAP_ANONYMOUS)) {
1394 audit_mmap_fd(fd, flags);
1398 if (is_file_hugepages(file))
1399 len = ALIGN(len, huge_page_size(hstate_file(file)));
1401 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1403 } else if (flags & MAP_HUGETLB) {
1404 struct user_struct *user = NULL;
1407 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1411 len = ALIGN(len, huge_page_size(hs));
1413 * VM_NORESERVE is used because the reservations will be
1414 * taken when vm_ops->mmap() is called
1415 * A dummy user value is used because we are not locking
1416 * memory so no accounting is necessary
1418 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1420 &user, HUGETLB_ANONHUGE_INODE,
1421 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1423 return PTR_ERR(file);
1426 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1428 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1436 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1437 struct mmap_arg_struct {
1441 unsigned long flags;
1443 unsigned long offset;
1446 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1448 struct mmap_arg_struct a;
1450 if (copy_from_user(&a, arg, sizeof(a)))
1452 if (a.offset & ~PAGE_MASK)
1455 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1456 a.offset >> PAGE_SHIFT);
1458 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1461 * Some shared mappigns will want the pages marked read-only
1462 * to track write events. If so, we'll downgrade vm_page_prot
1463 * to the private version (using protection_map[] without the
1466 int vma_wants_writenotify(struct vm_area_struct *vma)
1468 vm_flags_t vm_flags = vma->vm_flags;
1470 /* If it was private or non-writable, the write bit is already clear */
1471 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1474 /* The backer wishes to know when pages are first written to? */
1475 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1478 /* The open routine did something to the protections already? */
1479 if (pgprot_val(vma->vm_page_prot) !=
1480 pgprot_val(vm_get_page_prot(vm_flags)))
1483 /* Specialty mapping? */
1484 if (vm_flags & VM_PFNMAP)
1487 /* Can the mapping track the dirty pages? */
1488 return vma->vm_file && vma->vm_file->f_mapping &&
1489 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1493 * We account for memory if it's a private writeable mapping,
1494 * not hugepages and VM_NORESERVE wasn't set.
1496 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1499 * hugetlb has its own accounting separate from the core VM
1500 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1502 if (file && is_file_hugepages(file))
1505 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1508 unsigned long mmap_region(struct file *file, unsigned long addr,
1509 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1511 struct mm_struct *mm = current->mm;
1512 struct vm_area_struct *vma, *prev;
1514 struct rb_node **rb_link, *rb_parent;
1515 unsigned long charged = 0;
1517 /* Check against address space limit. */
1518 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
1519 unsigned long nr_pages;
1522 * MAP_FIXED may remove pages of mappings that intersects with
1523 * requested mapping. Account for the pages it would unmap.
1525 if (!(vm_flags & MAP_FIXED))
1528 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1530 if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
1534 /* Clear old maps */
1537 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
1538 if (do_munmap(mm, addr, len))
1544 * Private writable mapping: check memory availability
1546 if (accountable_mapping(file, vm_flags)) {
1547 charged = len >> PAGE_SHIFT;
1548 if (security_vm_enough_memory_mm(mm, charged))
1550 vm_flags |= VM_ACCOUNT;
1554 * Can we just expand an old mapping?
1556 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1561 * Determine the object being mapped and call the appropriate
1562 * specific mapper. the address has already been validated, but
1563 * not unmapped, but the maps are removed from the list.
1565 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1572 vma->vm_start = addr;
1573 vma->vm_end = addr + len;
1574 vma->vm_flags = vm_flags;
1575 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1576 vma->vm_pgoff = pgoff;
1577 INIT_LIST_HEAD(&vma->anon_vma_chain);
1580 if (vm_flags & VM_DENYWRITE) {
1581 error = deny_write_access(file);
1585 if (vm_flags & VM_SHARED) {
1586 error = mapping_map_writable(file->f_mapping);
1588 goto allow_write_and_free_vma;
1591 /* ->mmap() can change vma->vm_file, but must guarantee that
1592 * vma_link() below can deny write-access if VM_DENYWRITE is set
1593 * and map writably if VM_SHARED is set. This usually means the
1594 * new file must not have been exposed to user-space, yet.
1596 vma->vm_file = get_file(file);
1597 error = file->f_op->mmap(file, vma);
1599 goto unmap_and_free_vma;
1601 /* Can addr have changed??
1603 * Answer: Yes, several device drivers can do it in their
1604 * f_op->mmap method. -DaveM
1605 * Bug: If addr is changed, prev, rb_link, rb_parent should
1606 * be updated for vma_link()
1608 WARN_ON_ONCE(addr != vma->vm_start);
1610 addr = vma->vm_start;
1611 vm_flags = vma->vm_flags;
1612 } else if (vm_flags & VM_SHARED) {
1613 error = shmem_zero_setup(vma);
1618 if (vma_wants_writenotify(vma)) {
1619 pgprot_t pprot = vma->vm_page_prot;
1621 /* Can vma->vm_page_prot have changed??
1623 * Answer: Yes, drivers may have changed it in their
1624 * f_op->mmap method.
1626 * Ensures that vmas marked as uncached stay that way.
1628 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1629 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1630 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1633 vma_link(mm, vma, prev, rb_link, rb_parent);
1634 /* Once vma denies write, undo our temporary denial count */
1636 if (vm_flags & VM_SHARED)
1637 mapping_unmap_writable(file->f_mapping);
1638 if (vm_flags & VM_DENYWRITE)
1639 allow_write_access(file);
1641 file = vma->vm_file;
1643 perf_event_mmap(vma);
1645 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1646 if (vm_flags & VM_LOCKED) {
1647 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1648 vma == get_gate_vma(current->mm)))
1649 mm->locked_vm += (len >> PAGE_SHIFT);
1651 vma->vm_flags &= ~VM_LOCKED;
1658 * New (or expanded) vma always get soft dirty status.
1659 * Otherwise user-space soft-dirty page tracker won't
1660 * be able to distinguish situation when vma area unmapped,
1661 * then new mapped in-place (which must be aimed as
1662 * a completely new data area).
1664 vma->vm_flags |= VM_SOFTDIRTY;
1669 vma->vm_file = NULL;
1672 /* Undo any partial mapping done by a device driver. */
1673 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1675 if (vm_flags & VM_SHARED)
1676 mapping_unmap_writable(file->f_mapping);
1677 allow_write_and_free_vma:
1678 if (vm_flags & VM_DENYWRITE)
1679 allow_write_access(file);
1681 kmem_cache_free(vm_area_cachep, vma);
1684 vm_unacct_memory(charged);
1688 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1691 * We implement the search by looking for an rbtree node that
1692 * immediately follows a suitable gap. That is,
1693 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1694 * - gap_end = vma->vm_start >= info->low_limit + length;
1695 * - gap_end - gap_start >= length
1698 struct mm_struct *mm = current->mm;
1699 struct vm_area_struct *vma;
1700 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1702 /* Adjust search length to account for worst case alignment overhead */
1703 length = info->length + info->align_mask;
1704 if (length < info->length)
1707 /* Adjust search limits by the desired length */
1708 if (info->high_limit < length)
1710 high_limit = info->high_limit - length;
1712 if (info->low_limit > high_limit)
1714 low_limit = info->low_limit + length;
1716 /* Check if rbtree root looks promising */
1717 if (RB_EMPTY_ROOT(&mm->mm_rb))
1719 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1720 if (vma->rb_subtree_gap < length)
1724 /* Visit left subtree if it looks promising */
1725 gap_end = vma->vm_start;
1726 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1727 struct vm_area_struct *left =
1728 rb_entry(vma->vm_rb.rb_left,
1729 struct vm_area_struct, vm_rb);
1730 if (left->rb_subtree_gap >= length) {
1736 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1738 /* Check if current node has a suitable gap */
1739 if (gap_start > high_limit)
1741 if (gap_end >= low_limit && gap_end - gap_start >= length)
1744 /* Visit right subtree if it looks promising */
1745 if (vma->vm_rb.rb_right) {
1746 struct vm_area_struct *right =
1747 rb_entry(vma->vm_rb.rb_right,
1748 struct vm_area_struct, vm_rb);
1749 if (right->rb_subtree_gap >= length) {
1755 /* Go back up the rbtree to find next candidate node */
1757 struct rb_node *prev = &vma->vm_rb;
1758 if (!rb_parent(prev))
1760 vma = rb_entry(rb_parent(prev),
1761 struct vm_area_struct, vm_rb);
1762 if (prev == vma->vm_rb.rb_left) {
1763 gap_start = vma->vm_prev->vm_end;
1764 gap_end = vma->vm_start;
1771 /* Check highest gap, which does not precede any rbtree node */
1772 gap_start = mm->highest_vm_end;
1773 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1774 if (gap_start > high_limit)
1778 /* We found a suitable gap. Clip it with the original low_limit. */
1779 if (gap_start < info->low_limit)
1780 gap_start = info->low_limit;
1782 /* Adjust gap address to the desired alignment */
1783 gap_start += (info->align_offset - gap_start) & info->align_mask;
1785 VM_BUG_ON(gap_start + info->length > info->high_limit);
1786 VM_BUG_ON(gap_start + info->length > gap_end);
1790 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1792 struct mm_struct *mm = current->mm;
1793 struct vm_area_struct *vma;
1794 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1796 /* Adjust search length to account for worst case alignment overhead */
1797 length = info->length + info->align_mask;
1798 if (length < info->length)
1802 * Adjust search limits by the desired length.
1803 * See implementation comment at top of unmapped_area().
1805 gap_end = info->high_limit;
1806 if (gap_end < length)
1808 high_limit = gap_end - length;
1810 if (info->low_limit > high_limit)
1812 low_limit = info->low_limit + length;
1814 /* Check highest gap, which does not precede any rbtree node */
1815 gap_start = mm->highest_vm_end;
1816 if (gap_start <= high_limit)
1819 /* Check if rbtree root looks promising */
1820 if (RB_EMPTY_ROOT(&mm->mm_rb))
1822 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1823 if (vma->rb_subtree_gap < length)
1827 /* Visit right subtree if it looks promising */
1828 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1829 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1830 struct vm_area_struct *right =
1831 rb_entry(vma->vm_rb.rb_right,
1832 struct vm_area_struct, vm_rb);
1833 if (right->rb_subtree_gap >= length) {
1840 /* Check if current node has a suitable gap */
1841 gap_end = vma->vm_start;
1842 if (gap_end < low_limit)
1844 if (gap_start <= high_limit && gap_end - gap_start >= length)
1847 /* Visit left subtree if it looks promising */
1848 if (vma->vm_rb.rb_left) {
1849 struct vm_area_struct *left =
1850 rb_entry(vma->vm_rb.rb_left,
1851 struct vm_area_struct, vm_rb);
1852 if (left->rb_subtree_gap >= length) {
1858 /* Go back up the rbtree to find next candidate node */
1860 struct rb_node *prev = &vma->vm_rb;
1861 if (!rb_parent(prev))
1863 vma = rb_entry(rb_parent(prev),
1864 struct vm_area_struct, vm_rb);
1865 if (prev == vma->vm_rb.rb_right) {
1866 gap_start = vma->vm_prev ?
1867 vma->vm_prev->vm_end : 0;
1874 /* We found a suitable gap. Clip it with the original high_limit. */
1875 if (gap_end > info->high_limit)
1876 gap_end = info->high_limit;
1879 /* Compute highest gap address at the desired alignment */
1880 gap_end -= info->length;
1881 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1883 VM_BUG_ON(gap_end < info->low_limit);
1884 VM_BUG_ON(gap_end < gap_start);
1888 /* Get an address range which is currently unmapped.
1889 * For shmat() with addr=0.
1891 * Ugly calling convention alert:
1892 * Return value with the low bits set means error value,
1894 * if (ret & ~PAGE_MASK)
1897 * This function "knows" that -ENOMEM has the bits set.
1899 #ifndef HAVE_ARCH_UNMAPPED_AREA
1901 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1902 unsigned long len, unsigned long pgoff, unsigned long flags)
1904 struct mm_struct *mm = current->mm;
1905 struct vm_area_struct *vma;
1906 struct vm_unmapped_area_info info;
1908 if (len > TASK_SIZE - mmap_min_addr)
1911 if (flags & MAP_FIXED)
1915 addr = PAGE_ALIGN(addr);
1916 vma = find_vma(mm, addr);
1917 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1918 (!vma || addr + len <= vma->vm_start))
1924 info.low_limit = mm->mmap_base;
1925 info.high_limit = TASK_SIZE;
1926 info.align_mask = 0;
1927 return vm_unmapped_area(&info);
1932 * This mmap-allocator allocates new areas top-down from below the
1933 * stack's low limit (the base):
1935 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1937 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1938 const unsigned long len, const unsigned long pgoff,
1939 const unsigned long flags)
1941 struct vm_area_struct *vma;
1942 struct mm_struct *mm = current->mm;
1943 unsigned long addr = addr0;
1944 struct vm_unmapped_area_info info;
1946 /* requested length too big for entire address space */
1947 if (len > TASK_SIZE - mmap_min_addr)
1950 if (flags & MAP_FIXED)
1953 /* requesting a specific address */
1955 addr = PAGE_ALIGN(addr);
1956 vma = find_vma(mm, addr);
1957 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1958 (!vma || addr + len <= vma->vm_start))
1962 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1964 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1965 info.high_limit = mm->mmap_base;
1966 info.align_mask = 0;
1967 addr = vm_unmapped_area(&info);
1970 * A failed mmap() very likely causes application failure,
1971 * so fall back to the bottom-up function here. This scenario
1972 * can happen with large stack limits and large mmap()
1975 if (addr & ~PAGE_MASK) {
1976 VM_BUG_ON(addr != -ENOMEM);
1978 info.low_limit = TASK_UNMAPPED_BASE;
1979 info.high_limit = TASK_SIZE;
1980 addr = vm_unmapped_area(&info);
1988 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1989 unsigned long pgoff, unsigned long flags)
1991 unsigned long (*get_area)(struct file *, unsigned long,
1992 unsigned long, unsigned long, unsigned long);
1994 unsigned long error = arch_mmap_check(addr, len, flags);
1998 /* Careful about overflows.. */
1999 if (len > TASK_SIZE)
2002 get_area = current->mm->get_unmapped_area;
2003 if (file && file->f_op->get_unmapped_area)
2004 get_area = file->f_op->get_unmapped_area;
2005 addr = get_area(file, addr, len, pgoff, flags);
2006 if (IS_ERR_VALUE(addr))
2009 if (addr > TASK_SIZE - len)
2011 if (addr & ~PAGE_MASK)
2014 addr = arch_rebalance_pgtables(addr, len);
2015 error = security_mmap_addr(addr);
2016 return error ? error : addr;
2019 EXPORT_SYMBOL(get_unmapped_area);
2021 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2022 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2024 struct rb_node *rb_node;
2025 struct vm_area_struct *vma;
2027 /* Check the cache first. */
2028 vma = vmacache_find(mm, addr);
2032 rb_node = mm->mm_rb.rb_node;
2036 struct vm_area_struct *tmp;
2038 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2040 if (tmp->vm_end > addr) {
2042 if (tmp->vm_start <= addr)
2044 rb_node = rb_node->rb_left;
2046 rb_node = rb_node->rb_right;
2050 vmacache_update(addr, vma);
2054 EXPORT_SYMBOL(find_vma);
2057 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2059 struct vm_area_struct *
2060 find_vma_prev(struct mm_struct *mm, unsigned long addr,
2061 struct vm_area_struct **pprev)
2063 struct vm_area_struct *vma;
2065 vma = find_vma(mm, addr);
2067 *pprev = vma->vm_prev;
2069 struct rb_node *rb_node = mm->mm_rb.rb_node;
2072 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2073 rb_node = rb_node->rb_right;
2080 * Verify that the stack growth is acceptable and
2081 * update accounting. This is shared with both the
2082 * grow-up and grow-down cases.
2084 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2086 struct mm_struct *mm = vma->vm_mm;
2087 struct rlimit *rlim = current->signal->rlim;
2088 unsigned long new_start;
2090 /* address space limit tests */
2091 if (!may_expand_vm(mm, grow))
2094 /* Stack limit test */
2095 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2098 /* mlock limit tests */
2099 if (vma->vm_flags & VM_LOCKED) {
2100 unsigned long locked;
2101 unsigned long limit;
2102 locked = mm->locked_vm + grow;
2103 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2104 limit >>= PAGE_SHIFT;
2105 if (locked > limit && !capable(CAP_IPC_LOCK))
2109 /* Check to ensure the stack will not grow into a hugetlb-only region */
2110 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2112 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2116 * Overcommit.. This must be the final test, as it will
2117 * update security statistics.
2119 if (security_vm_enough_memory_mm(mm, grow))
2122 /* Ok, everything looks good - let it rip */
2123 if (vma->vm_flags & VM_LOCKED)
2124 mm->locked_vm += grow;
2125 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2129 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2131 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2132 * vma is the last one with address > vma->vm_end. Have to extend vma.
2134 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2138 if (!(vma->vm_flags & VM_GROWSUP))
2142 * We must make sure the anon_vma is allocated
2143 * so that the anon_vma locking is not a noop.
2145 if (unlikely(anon_vma_prepare(vma)))
2147 vma_lock_anon_vma(vma);
2150 * vma->vm_start/vm_end cannot change under us because the caller
2151 * is required to hold the mmap_sem in read mode. We need the
2152 * anon_vma lock to serialize against concurrent expand_stacks.
2153 * Also guard against wrapping around to address 0.
2155 if (address < PAGE_ALIGN(address+4))
2156 address = PAGE_ALIGN(address+4);
2158 vma_unlock_anon_vma(vma);
2163 /* Somebody else might have raced and expanded it already */
2164 if (address > vma->vm_end) {
2165 unsigned long size, grow;
2167 size = address - vma->vm_start;
2168 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2171 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2172 error = acct_stack_growth(vma, size, grow);
2175 * vma_gap_update() doesn't support concurrent
2176 * updates, but we only hold a shared mmap_sem
2177 * lock here, so we need to protect against
2178 * concurrent vma expansions.
2179 * vma_lock_anon_vma() doesn't help here, as
2180 * we don't guarantee that all growable vmas
2181 * in a mm share the same root anon vma.
2182 * So, we reuse mm->page_table_lock to guard
2183 * against concurrent vma expansions.
2185 spin_lock(&vma->vm_mm->page_table_lock);
2186 anon_vma_interval_tree_pre_update_vma(vma);
2187 vma->vm_end = address;
2188 anon_vma_interval_tree_post_update_vma(vma);
2190 vma_gap_update(vma->vm_next);
2192 vma->vm_mm->highest_vm_end = address;
2193 spin_unlock(&vma->vm_mm->page_table_lock);
2195 perf_event_mmap(vma);
2199 vma_unlock_anon_vma(vma);
2200 khugepaged_enter_vma_merge(vma);
2201 validate_mm(vma->vm_mm);
2204 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2207 * vma is the first one with address < vma->vm_start. Have to extend vma.
2209 int expand_downwards(struct vm_area_struct *vma,
2210 unsigned long address)
2215 * We must make sure the anon_vma is allocated
2216 * so that the anon_vma locking is not a noop.
2218 if (unlikely(anon_vma_prepare(vma)))
2221 address &= PAGE_MASK;
2222 error = security_mmap_addr(address);
2226 vma_lock_anon_vma(vma);
2229 * vma->vm_start/vm_end cannot change under us because the caller
2230 * is required to hold the mmap_sem in read mode. We need the
2231 * anon_vma lock to serialize against concurrent expand_stacks.
2234 /* Somebody else might have raced and expanded it already */
2235 if (address < vma->vm_start) {
2236 unsigned long size, grow;
2238 size = vma->vm_end - address;
2239 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2242 if (grow <= vma->vm_pgoff) {
2243 error = acct_stack_growth(vma, size, grow);
2246 * vma_gap_update() doesn't support concurrent
2247 * updates, but we only hold a shared mmap_sem
2248 * lock here, so we need to protect against
2249 * concurrent vma expansions.
2250 * vma_lock_anon_vma() doesn't help here, as
2251 * we don't guarantee that all growable vmas
2252 * in a mm share the same root anon vma.
2253 * So, we reuse mm->page_table_lock to guard
2254 * against concurrent vma expansions.
2256 spin_lock(&vma->vm_mm->page_table_lock);
2257 anon_vma_interval_tree_pre_update_vma(vma);
2258 vma->vm_start = address;
2259 vma->vm_pgoff -= grow;
2260 anon_vma_interval_tree_post_update_vma(vma);
2261 vma_gap_update(vma);
2262 spin_unlock(&vma->vm_mm->page_table_lock);
2264 perf_event_mmap(vma);
2268 vma_unlock_anon_vma(vma);
2269 khugepaged_enter_vma_merge(vma);
2270 validate_mm(vma->vm_mm);
2275 * Note how expand_stack() refuses to expand the stack all the way to
2276 * abut the next virtual mapping, *unless* that mapping itself is also
2277 * a stack mapping. We want to leave room for a guard page, after all
2278 * (the guard page itself is not added here, that is done by the
2279 * actual page faulting logic)
2281 * This matches the behavior of the guard page logic (see mm/memory.c:
2282 * check_stack_guard_page()), which only allows the guard page to be
2283 * removed under these circumstances.
2285 #ifdef CONFIG_STACK_GROWSUP
2286 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2288 struct vm_area_struct *next;
2290 address &= PAGE_MASK;
2291 next = vma->vm_next;
2292 if (next && next->vm_start == address + PAGE_SIZE) {
2293 if (!(next->vm_flags & VM_GROWSUP))
2296 return expand_upwards(vma, address);
2299 struct vm_area_struct *
2300 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2302 struct vm_area_struct *vma, *prev;
2305 vma = find_vma_prev(mm, addr, &prev);
2306 if (vma && (vma->vm_start <= addr))
2308 if (!prev || expand_stack(prev, addr))
2310 if (prev->vm_flags & VM_LOCKED)
2311 __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2315 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2317 struct vm_area_struct *prev;
2319 address &= PAGE_MASK;
2320 prev = vma->vm_prev;
2321 if (prev && prev->vm_end == address) {
2322 if (!(prev->vm_flags & VM_GROWSDOWN))
2325 return expand_downwards(vma, address);
2328 struct vm_area_struct *
2329 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2331 struct vm_area_struct *vma;
2332 unsigned long start;
2335 vma = find_vma(mm, addr);
2338 if (vma->vm_start <= addr)
2340 if (!(vma->vm_flags & VM_GROWSDOWN))
2342 start = vma->vm_start;
2343 if (expand_stack(vma, addr))
2345 if (vma->vm_flags & VM_LOCKED)
2346 __mlock_vma_pages_range(vma, addr, start, NULL);
2352 * Ok - we have the memory areas we should free on the vma list,
2353 * so release them, and do the vma updates.
2355 * Called with the mm semaphore held.
2357 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2359 unsigned long nr_accounted = 0;
2361 /* Update high watermark before we lower total_vm */
2362 update_hiwater_vm(mm);
2364 long nrpages = vma_pages(vma);
2366 if (vma->vm_flags & VM_ACCOUNT)
2367 nr_accounted += nrpages;
2368 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2369 vma = remove_vma(vma);
2371 vm_unacct_memory(nr_accounted);
2376 * Get rid of page table information in the indicated region.
2378 * Called with the mm semaphore held.
2380 static void unmap_region(struct mm_struct *mm,
2381 struct vm_area_struct *vma, struct vm_area_struct *prev,
2382 unsigned long start, unsigned long end)
2384 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2385 struct mmu_gather tlb;
2388 tlb_gather_mmu(&tlb, mm, start, end);
2389 update_hiwater_rss(mm);
2390 unmap_vmas(&tlb, vma, start, end);
2391 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2392 next ? next->vm_start : USER_PGTABLES_CEILING);
2393 tlb_finish_mmu(&tlb, start, end);
2397 * Create a list of vma's touched by the unmap, removing them from the mm's
2398 * vma list as we go..
2401 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2402 struct vm_area_struct *prev, unsigned long end)
2404 struct vm_area_struct **insertion_point;
2405 struct vm_area_struct *tail_vma = NULL;
2407 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2408 vma->vm_prev = NULL;
2410 vma_rb_erase(vma, &mm->mm_rb);
2414 } while (vma && vma->vm_start < end);
2415 *insertion_point = vma;
2417 vma->vm_prev = prev;
2418 vma_gap_update(vma);
2420 mm->highest_vm_end = prev ? prev->vm_end : 0;
2421 tail_vma->vm_next = NULL;
2423 /* Kill the cache */
2424 vmacache_invalidate(mm);
2428 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2429 * munmap path where it doesn't make sense to fail.
2431 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2432 unsigned long addr, int new_below)
2434 struct vm_area_struct *new;
2437 if (is_vm_hugetlb_page(vma) && (addr &
2438 ~(huge_page_mask(hstate_vma(vma)))))
2441 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2445 /* most fields are the same, copy all, and then fixup */
2448 INIT_LIST_HEAD(&new->anon_vma_chain);
2453 new->vm_start = addr;
2454 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2457 err = vma_dup_policy(vma, new);
2461 if (anon_vma_clone(new, vma))
2465 get_file(new->vm_file);
2467 if (new->vm_ops && new->vm_ops->open)
2468 new->vm_ops->open(new);
2471 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2472 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2474 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2480 /* Clean everything up if vma_adjust failed. */
2481 if (new->vm_ops && new->vm_ops->close)
2482 new->vm_ops->close(new);
2485 unlink_anon_vmas(new);
2487 mpol_put(vma_policy(new));
2489 kmem_cache_free(vm_area_cachep, new);
2495 * Split a vma into two pieces at address 'addr', a new vma is allocated
2496 * either for the first part or the tail.
2498 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2499 unsigned long addr, int new_below)
2501 if (mm->map_count >= sysctl_max_map_count)
2504 return __split_vma(mm, vma, addr, new_below);
2507 /* Munmap is split into 2 main parts -- this part which finds
2508 * what needs doing, and the areas themselves, which do the
2509 * work. This now handles partial unmappings.
2510 * Jeremy Fitzhardinge <jeremy@goop.org>
2512 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2515 struct vm_area_struct *vma, *prev, *last;
2517 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2520 len = PAGE_ALIGN(len);
2524 /* Find the first overlapping VMA */
2525 vma = find_vma(mm, start);
2528 prev = vma->vm_prev;
2529 /* we have start < vma->vm_end */
2531 /* if it doesn't overlap, we have nothing.. */
2533 if (vma->vm_start >= end)
2537 * If we need to split any vma, do it now to save pain later.
2539 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2540 * unmapped vm_area_struct will remain in use: so lower split_vma
2541 * places tmp vma above, and higher split_vma places tmp vma below.
2543 if (start > vma->vm_start) {
2547 * Make sure that map_count on return from munmap() will
2548 * not exceed its limit; but let map_count go just above
2549 * its limit temporarily, to help free resources as expected.
2551 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2554 error = __split_vma(mm, vma, start, 0);
2560 /* Does it split the last one? */
2561 last = find_vma(mm, end);
2562 if (last && end > last->vm_start) {
2563 int error = __split_vma(mm, last, end, 1);
2567 vma = prev ? prev->vm_next : mm->mmap;
2570 * unlock any mlock()ed ranges before detaching vmas
2572 if (mm->locked_vm) {
2573 struct vm_area_struct *tmp = vma;
2574 while (tmp && tmp->vm_start < end) {
2575 if (tmp->vm_flags & VM_LOCKED) {
2576 mm->locked_vm -= vma_pages(tmp);
2577 munlock_vma_pages_all(tmp);
2584 * Remove the vma's, and unmap the actual pages
2586 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2587 unmap_region(mm, vma, prev, start, end);
2589 /* Fix up all other VM information */
2590 remove_vma_list(mm, vma);
2595 int vm_munmap(unsigned long start, size_t len)
2598 struct mm_struct *mm = current->mm;
2600 down_write(&mm->mmap_sem);
2601 ret = do_munmap(mm, start, len);
2602 up_write(&mm->mmap_sem);
2605 EXPORT_SYMBOL(vm_munmap);
2607 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2609 profile_munmap(addr);
2610 return vm_munmap(addr, len);
2613 static inline void verify_mm_writelocked(struct mm_struct *mm)
2615 #ifdef CONFIG_DEBUG_VM
2616 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2618 up_read(&mm->mmap_sem);
2624 * this is really a simplified "do_mmap". it only handles
2625 * anonymous maps. eventually we may be able to do some
2626 * brk-specific accounting here.
2628 static unsigned long do_brk(unsigned long addr, unsigned long len)
2630 struct mm_struct *mm = current->mm;
2631 struct vm_area_struct *vma, *prev;
2632 unsigned long flags;
2633 struct rb_node **rb_link, *rb_parent;
2634 pgoff_t pgoff = addr >> PAGE_SHIFT;
2637 len = PAGE_ALIGN(len);
2641 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2643 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2644 if (error & ~PAGE_MASK)
2647 error = mlock_future_check(mm, mm->def_flags, len);
2652 * mm->mmap_sem is required to protect against another thread
2653 * changing the mappings in case we sleep.
2655 verify_mm_writelocked(mm);
2658 * Clear old maps. this also does some error checking for us
2661 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
2662 if (do_munmap(mm, addr, len))
2667 /* Check against address space limits *after* clearing old maps... */
2668 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2671 if (mm->map_count > sysctl_max_map_count)
2674 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2677 /* Can we just expand an old private anonymous mapping? */
2678 vma = vma_merge(mm, prev, addr, addr + len, flags,
2679 NULL, NULL, pgoff, NULL);
2684 * create a vma struct for an anonymous mapping
2686 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2688 vm_unacct_memory(len >> PAGE_SHIFT);
2692 INIT_LIST_HEAD(&vma->anon_vma_chain);
2694 vma->vm_start = addr;
2695 vma->vm_end = addr + len;
2696 vma->vm_pgoff = pgoff;
2697 vma->vm_flags = flags;
2698 vma->vm_page_prot = vm_get_page_prot(flags);
2699 vma_link(mm, vma, prev, rb_link, rb_parent);
2701 perf_event_mmap(vma);
2702 mm->total_vm += len >> PAGE_SHIFT;
2703 if (flags & VM_LOCKED)
2704 mm->locked_vm += (len >> PAGE_SHIFT);
2705 vma->vm_flags |= VM_SOFTDIRTY;
2709 unsigned long vm_brk(unsigned long addr, unsigned long len)
2711 struct mm_struct *mm = current->mm;
2715 down_write(&mm->mmap_sem);
2716 ret = do_brk(addr, len);
2717 populate = ((mm->def_flags & VM_LOCKED) != 0);
2718 up_write(&mm->mmap_sem);
2720 mm_populate(addr, len);
2723 EXPORT_SYMBOL(vm_brk);
2725 /* Release all mmaps. */
2726 void exit_mmap(struct mm_struct *mm)
2728 struct mmu_gather tlb;
2729 struct vm_area_struct *vma;
2730 unsigned long nr_accounted = 0;
2732 /* mm's last user has gone, and its about to be pulled down */
2733 mmu_notifier_release(mm);
2735 if (mm->locked_vm) {
2738 if (vma->vm_flags & VM_LOCKED)
2739 munlock_vma_pages_all(vma);
2747 if (!vma) /* Can happen if dup_mmap() received an OOM */
2752 tlb_gather_mmu(&tlb, mm, 0, -1);
2753 /* update_hiwater_rss(mm) here? but nobody should be looking */
2754 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2755 unmap_vmas(&tlb, vma, 0, -1);
2757 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2758 tlb_finish_mmu(&tlb, 0, -1);
2761 * Walk the list again, actually closing and freeing it,
2762 * with preemption enabled, without holding any MM locks.
2765 if (vma->vm_flags & VM_ACCOUNT)
2766 nr_accounted += vma_pages(vma);
2767 vma = remove_vma(vma);
2769 vm_unacct_memory(nr_accounted);
2771 WARN_ON(atomic_long_read(&mm->nr_ptes) >
2772 (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2775 /* Insert vm structure into process list sorted by address
2776 * and into the inode's i_mmap tree. If vm_file is non-NULL
2777 * then i_mmap_mutex is taken here.
2779 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2781 struct vm_area_struct *prev;
2782 struct rb_node **rb_link, *rb_parent;
2785 * The vm_pgoff of a purely anonymous vma should be irrelevant
2786 * until its first write fault, when page's anon_vma and index
2787 * are set. But now set the vm_pgoff it will almost certainly
2788 * end up with (unless mremap moves it elsewhere before that
2789 * first wfault), so /proc/pid/maps tells a consistent story.
2791 * By setting it to reflect the virtual start address of the
2792 * vma, merges and splits can happen in a seamless way, just
2793 * using the existing file pgoff checks and manipulations.
2794 * Similarly in do_mmap_pgoff and in do_brk.
2796 if (!vma->vm_file) {
2797 BUG_ON(vma->anon_vma);
2798 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2800 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2801 &prev, &rb_link, &rb_parent))
2803 if ((vma->vm_flags & VM_ACCOUNT) &&
2804 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2807 vma_link(mm, vma, prev, rb_link, rb_parent);
2812 * Copy the vma structure to a new location in the same mm,
2813 * prior to moving page table entries, to effect an mremap move.
2815 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2816 unsigned long addr, unsigned long len, pgoff_t pgoff,
2817 bool *need_rmap_locks)
2819 struct vm_area_struct *vma = *vmap;
2820 unsigned long vma_start = vma->vm_start;
2821 struct mm_struct *mm = vma->vm_mm;
2822 struct vm_area_struct *new_vma, *prev;
2823 struct rb_node **rb_link, *rb_parent;
2824 bool faulted_in_anon_vma = true;
2827 * If anonymous vma has not yet been faulted, update new pgoff
2828 * to match new location, to increase its chance of merging.
2830 if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2831 pgoff = addr >> PAGE_SHIFT;
2832 faulted_in_anon_vma = false;
2835 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2836 return NULL; /* should never get here */
2837 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2838 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2841 * Source vma may have been merged into new_vma
2843 if (unlikely(vma_start >= new_vma->vm_start &&
2844 vma_start < new_vma->vm_end)) {
2846 * The only way we can get a vma_merge with
2847 * self during an mremap is if the vma hasn't
2848 * been faulted in yet and we were allowed to
2849 * reset the dst vma->vm_pgoff to the
2850 * destination address of the mremap to allow
2851 * the merge to happen. mremap must change the
2852 * vm_pgoff linearity between src and dst vmas
2853 * (in turn preventing a vma_merge) to be
2854 * safe. It is only safe to keep the vm_pgoff
2855 * linear if there are no pages mapped yet.
2857 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2858 *vmap = vma = new_vma;
2860 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2862 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2865 new_vma->vm_start = addr;
2866 new_vma->vm_end = addr + len;
2867 new_vma->vm_pgoff = pgoff;
2868 if (vma_dup_policy(vma, new_vma))
2870 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2871 if (anon_vma_clone(new_vma, vma))
2872 goto out_free_mempol;
2873 if (new_vma->vm_file)
2874 get_file(new_vma->vm_file);
2875 if (new_vma->vm_ops && new_vma->vm_ops->open)
2876 new_vma->vm_ops->open(new_vma);
2877 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2878 *need_rmap_locks = false;
2884 mpol_put(vma_policy(new_vma));
2886 kmem_cache_free(vm_area_cachep, new_vma);
2891 * Return true if the calling process may expand its vm space by the passed
2894 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2896 unsigned long cur = mm->total_vm; /* pages */
2899 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2901 if (cur + npages > lim)
2906 static int special_mapping_fault(struct vm_area_struct *vma,
2907 struct vm_fault *vmf);
2910 * Having a close hook prevents vma merging regardless of flags.
2912 static void special_mapping_close(struct vm_area_struct *vma)
2916 static const char *special_mapping_name(struct vm_area_struct *vma)
2918 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
2921 static const struct vm_operations_struct special_mapping_vmops = {
2922 .close = special_mapping_close,
2923 .fault = special_mapping_fault,
2924 .name = special_mapping_name,
2927 static const struct vm_operations_struct legacy_special_mapping_vmops = {
2928 .close = special_mapping_close,
2929 .fault = special_mapping_fault,
2932 static int special_mapping_fault(struct vm_area_struct *vma,
2933 struct vm_fault *vmf)
2936 struct page **pages;
2939 * special mappings have no vm_file, and in that case, the mm
2940 * uses vm_pgoff internally. So we have to subtract it from here.
2941 * We are allowed to do this because we are the mm; do not copy
2942 * this code into drivers!
2944 pgoff = vmf->pgoff - vma->vm_pgoff;
2946 if (vma->vm_ops == &legacy_special_mapping_vmops)
2947 pages = vma->vm_private_data;
2949 pages = ((struct vm_special_mapping *)vma->vm_private_data)->
2952 for (; pgoff && *pages; ++pages)
2956 struct page *page = *pages;
2962 return VM_FAULT_SIGBUS;
2965 static struct vm_area_struct *__install_special_mapping(
2966 struct mm_struct *mm,
2967 unsigned long addr, unsigned long len,
2968 unsigned long vm_flags, const struct vm_operations_struct *ops,
2972 struct vm_area_struct *vma;
2974 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2975 if (unlikely(vma == NULL))
2976 return ERR_PTR(-ENOMEM);
2978 INIT_LIST_HEAD(&vma->anon_vma_chain);
2980 vma->vm_start = addr;
2981 vma->vm_end = addr + len;
2983 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
2984 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2987 vma->vm_private_data = priv;
2989 ret = insert_vm_struct(mm, vma);
2993 mm->total_vm += len >> PAGE_SHIFT;
2995 perf_event_mmap(vma);
3000 kmem_cache_free(vm_area_cachep, vma);
3001 return ERR_PTR(ret);
3005 * Called with mm->mmap_sem held for writing.
3006 * Insert a new vma covering the given region, with the given flags.
3007 * Its pages are supplied by the given array of struct page *.
3008 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3009 * The region past the last page supplied will always produce SIGBUS.
3010 * The array pointer and the pages it points to are assumed to stay alive
3011 * for as long as this mapping might exist.
3013 struct vm_area_struct *_install_special_mapping(
3014 struct mm_struct *mm,
3015 unsigned long addr, unsigned long len,
3016 unsigned long vm_flags, const struct vm_special_mapping *spec)
3018 return __install_special_mapping(mm, addr, len, vm_flags,
3019 &special_mapping_vmops, (void *)spec);
3022 int install_special_mapping(struct mm_struct *mm,
3023 unsigned long addr, unsigned long len,
3024 unsigned long vm_flags, struct page **pages)
3026 struct vm_area_struct *vma = __install_special_mapping(
3027 mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
3030 return PTR_ERR_OR_ZERO(vma);
3033 static DEFINE_MUTEX(mm_all_locks_mutex);
3035 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3037 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3039 * The LSB of head.next can't change from under us
3040 * because we hold the mm_all_locks_mutex.
3042 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3044 * We can safely modify head.next after taking the
3045 * anon_vma->root->rwsem. If some other vma in this mm shares
3046 * the same anon_vma we won't take it again.
3048 * No need of atomic instructions here, head.next
3049 * can't change from under us thanks to the
3050 * anon_vma->root->rwsem.
3052 if (__test_and_set_bit(0, (unsigned long *)
3053 &anon_vma->root->rb_root.rb_node))
3058 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3060 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3062 * AS_MM_ALL_LOCKS can't change from under us because
3063 * we hold the mm_all_locks_mutex.
3065 * Operations on ->flags have to be atomic because
3066 * even if AS_MM_ALL_LOCKS is stable thanks to the
3067 * mm_all_locks_mutex, there may be other cpus
3068 * changing other bitflags in parallel to us.
3070 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3072 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
3077 * This operation locks against the VM for all pte/vma/mm related
3078 * operations that could ever happen on a certain mm. This includes
3079 * vmtruncate, try_to_unmap, and all page faults.
3081 * The caller must take the mmap_sem in write mode before calling
3082 * mm_take_all_locks(). The caller isn't allowed to release the
3083 * mmap_sem until mm_drop_all_locks() returns.
3085 * mmap_sem in write mode is required in order to block all operations
3086 * that could modify pagetables and free pages without need of
3087 * altering the vma layout (for example populate_range() with
3088 * nonlinear vmas). 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 can take all the locks in random order because the VM code
3099 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3100 * takes more than one of them in a row. Secondly we're protected
3101 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
3103 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3104 * that may have to take thousand of locks.
3106 * mm_take_all_locks() can fail if it's interrupted by signals.
3108 int mm_take_all_locks(struct mm_struct *mm)
3110 struct vm_area_struct *vma;
3111 struct anon_vma_chain *avc;
3113 BUG_ON(down_read_trylock(&mm->mmap_sem));
3115 mutex_lock(&mm_all_locks_mutex);
3117 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3118 if (signal_pending(current))
3120 if (vma->vm_file && vma->vm_file->f_mapping)
3121 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3124 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3125 if (signal_pending(current))
3128 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3129 vm_lock_anon_vma(mm, avc->anon_vma);
3135 mm_drop_all_locks(mm);
3139 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3141 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3143 * The LSB of head.next can't change to 0 from under
3144 * us because we hold the mm_all_locks_mutex.
3146 * We must however clear the bitflag before unlocking
3147 * the vma so the users using the anon_vma->rb_root will
3148 * never see our bitflag.
3150 * No need of atomic instructions here, head.next
3151 * can't change from under us until we release the
3152 * anon_vma->root->rwsem.
3154 if (!__test_and_clear_bit(0, (unsigned long *)
3155 &anon_vma->root->rb_root.rb_node))
3157 anon_vma_unlock_write(anon_vma);
3161 static void vm_unlock_mapping(struct address_space *mapping)
3163 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3165 * AS_MM_ALL_LOCKS can't change to 0 from under us
3166 * because we hold the mm_all_locks_mutex.
3168 mutex_unlock(&mapping->i_mmap_mutex);
3169 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3176 * The mmap_sem cannot be released by the caller until
3177 * mm_drop_all_locks() returns.
3179 void mm_drop_all_locks(struct mm_struct *mm)
3181 struct vm_area_struct *vma;
3182 struct anon_vma_chain *avc;
3184 BUG_ON(down_read_trylock(&mm->mmap_sem));
3185 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3187 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3189 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3190 vm_unlock_anon_vma(avc->anon_vma);
3191 if (vma->vm_file && vma->vm_file->f_mapping)
3192 vm_unlock_mapping(vma->vm_file->f_mapping);
3195 mutex_unlock(&mm_all_locks_mutex);
3199 * initialise the VMA slab
3201 void __init mmap_init(void)
3205 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3210 * Initialise sysctl_user_reserve_kbytes.
3212 * This is intended to prevent a user from starting a single memory hogging
3213 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3216 * The default value is min(3% of free memory, 128MB)
3217 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3219 static int init_user_reserve(void)
3221 unsigned long free_kbytes;
3223 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3225 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3228 subsys_initcall(init_user_reserve);
3231 * Initialise sysctl_admin_reserve_kbytes.
3233 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3234 * to log in and kill a memory hogging process.
3236 * Systems with more than 256MB will reserve 8MB, enough to recover
3237 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3238 * only reserve 3% of free pages by default.
3240 static int init_admin_reserve(void)
3242 unsigned long free_kbytes;
3244 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3246 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3249 subsys_initcall(init_admin_reserve);
3252 * Reinititalise user and admin reserves if memory is added or removed.
3254 * The default user reserve max is 128MB, and the default max for the
3255 * admin reserve is 8MB. These are usually, but not always, enough to
3256 * enable recovery from a memory hogging process using login/sshd, a shell,
3257 * and tools like top. It may make sense to increase or even disable the
3258 * reserve depending on the existence of swap or variations in the recovery
3259 * tools. So, the admin may have changed them.
3261 * If memory is added and the reserves have been eliminated or increased above
3262 * the default max, then we'll trust the admin.
3264 * If memory is removed and there isn't enough free memory, then we
3265 * need to reset the reserves.
3267 * Otherwise keep the reserve set by the admin.
3269 static int reserve_mem_notifier(struct notifier_block *nb,
3270 unsigned long action, void *data)
3272 unsigned long tmp, free_kbytes;
3276 /* Default max is 128MB. Leave alone if modified by operator. */
3277 tmp = sysctl_user_reserve_kbytes;
3278 if (0 < tmp && tmp < (1UL << 17))
3279 init_user_reserve();
3281 /* Default max is 8MB. Leave alone if modified by operator. */
3282 tmp = sysctl_admin_reserve_kbytes;
3283 if (0 < tmp && tmp < (1UL << 13))
3284 init_admin_reserve();
3288 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3290 if (sysctl_user_reserve_kbytes > free_kbytes) {
3291 init_user_reserve();
3292 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3293 sysctl_user_reserve_kbytes);
3296 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3297 init_admin_reserve();
3298 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3299 sysctl_admin_reserve_kbytes);
3308 static struct notifier_block reserve_mem_nb = {
3309 .notifier_call = reserve_mem_notifier,
3312 static int __meminit init_reserve_notifier(void)
3314 if (register_hotmemory_notifier(&reserve_mem_nb))
3315 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3319 subsys_initcall(init_reserve_notifier);