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>
44 #include <linux/userfaultfd_k.h>
45 #include <linux/moduleparam.h>
46 #include <linux/pkeys.h>
48 #include <asm/uaccess.h>
49 #include <asm/cacheflush.h>
51 #include <asm/mmu_context.h>
55 #ifndef arch_mmap_check
56 #define arch_mmap_check(addr, len, flags) (0)
59 #ifndef arch_rebalance_pgtables
60 #define arch_rebalance_pgtables(addr, len) (addr)
63 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
64 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
65 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
66 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
68 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
69 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
70 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
71 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
74 static bool ignore_rlimit_data = true;
75 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
77 static void unmap_region(struct mm_struct *mm,
78 struct vm_area_struct *vma, struct vm_area_struct *prev,
79 unsigned long start, unsigned long end);
81 /* description of effects of mapping type and prot in current implementation.
82 * this is due to the limited x86 page protection hardware. The expected
83 * behavior is in parens:
86 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
87 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
88 * w: (no) no w: (no) no w: (yes) yes w: (no) no
89 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
91 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
92 * w: (no) no w: (no) no w: (copy) copy w: (no) no
93 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
96 pgprot_t protection_map[16] = {
97 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
98 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
101 pgprot_t vm_get_page_prot(unsigned long vm_flags)
103 return __pgprot(pgprot_val(protection_map[vm_flags &
104 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
105 pgprot_val(arch_vm_get_page_prot(vm_flags)));
107 EXPORT_SYMBOL(vm_get_page_prot);
109 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
111 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
114 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
115 void vma_set_page_prot(struct vm_area_struct *vma)
117 unsigned long vm_flags = vma->vm_flags;
119 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
120 if (vma_wants_writenotify(vma)) {
121 vm_flags &= ~VM_SHARED;
122 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
128 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
129 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
130 unsigned long sysctl_overcommit_kbytes __read_mostly;
131 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
132 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
133 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
135 * Make sure vm_committed_as in one cacheline and not cacheline shared with
136 * other variables. It can be updated by several CPUs frequently.
138 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
141 * The global memory commitment made in the system can be a metric
142 * that can be used to drive ballooning decisions when Linux is hosted
143 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
144 * balancing memory across competing virtual machines that are hosted.
145 * Several metrics drive this policy engine including the guest reported
148 unsigned long vm_memory_committed(void)
150 return percpu_counter_read_positive(&vm_committed_as);
152 EXPORT_SYMBOL_GPL(vm_memory_committed);
155 * Check that a process has enough memory to allocate a new virtual
156 * mapping. 0 means there is enough memory for the allocation to
157 * succeed and -ENOMEM implies there is not.
159 * We currently support three overcommit policies, which are set via the
160 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
162 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
163 * Additional code 2002 Jul 20 by Robert Love.
165 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
167 * Note this is a helper function intended to be used by LSMs which
168 * wish to use this logic.
170 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
172 long free, allowed, reserve;
174 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
175 -(s64)vm_committed_as_batch * num_online_cpus(),
176 "memory commitment underflow");
178 vm_acct_memory(pages);
181 * Sometimes we want to use more memory than we have
183 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
186 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
187 free = global_page_state(NR_FREE_PAGES);
188 free += global_page_state(NR_FILE_PAGES);
191 * shmem pages shouldn't be counted as free in this
192 * case, they can't be purged, only swapped out, and
193 * that won't affect the overall amount of available
194 * memory in the system.
196 free -= global_page_state(NR_SHMEM);
198 free += get_nr_swap_pages();
201 * Any slabs which are created with the
202 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
203 * which are reclaimable, under pressure. The dentry
204 * cache and most inode caches should fall into this
206 free += global_page_state(NR_SLAB_RECLAIMABLE);
209 * Leave reserved pages. The pages are not for anonymous pages.
211 if (free <= totalreserve_pages)
214 free -= totalreserve_pages;
217 * Reserve some for root
220 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
228 allowed = vm_commit_limit();
230 * Reserve some for root
233 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
236 * Don't let a single process grow so big a user can't recover
239 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
240 allowed -= min_t(long, mm->total_vm / 32, reserve);
243 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
246 vm_unacct_memory(pages);
252 * Requires inode->i_mapping->i_mmap_rwsem
254 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
255 struct file *file, struct address_space *mapping)
257 if (vma->vm_flags & VM_DENYWRITE)
258 atomic_inc(&file_inode(file)->i_writecount);
259 if (vma->vm_flags & VM_SHARED)
260 mapping_unmap_writable(mapping);
262 flush_dcache_mmap_lock(mapping);
263 vma_interval_tree_remove(vma, &mapping->i_mmap);
264 flush_dcache_mmap_unlock(mapping);
268 * Unlink a file-based vm structure from its interval tree, to hide
269 * vma from rmap and vmtruncate before freeing its page tables.
271 void unlink_file_vma(struct vm_area_struct *vma)
273 struct file *file = vma->vm_file;
276 struct address_space *mapping = file->f_mapping;
277 i_mmap_lock_write(mapping);
278 __remove_shared_vm_struct(vma, file, mapping);
279 i_mmap_unlock_write(mapping);
284 * Close a vm structure and free it, returning the next.
286 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
288 struct vm_area_struct *next = vma->vm_next;
291 if (vma->vm_ops && vma->vm_ops->close)
292 vma->vm_ops->close(vma);
295 mpol_put(vma_policy(vma));
296 kmem_cache_free(vm_area_cachep, vma);
300 static unsigned long do_brk(unsigned long addr, unsigned long len);
302 SYSCALL_DEFINE1(brk, unsigned long, brk)
304 unsigned long retval;
305 unsigned long newbrk, oldbrk;
306 struct mm_struct *mm = current->mm;
307 unsigned long min_brk;
310 down_write(&mm->mmap_sem);
312 #ifdef CONFIG_COMPAT_BRK
314 * CONFIG_COMPAT_BRK can still be overridden by setting
315 * randomize_va_space to 2, which will still cause mm->start_brk
316 * to be arbitrarily shifted
318 if (current->brk_randomized)
319 min_brk = mm->start_brk;
321 min_brk = mm->end_data;
323 min_brk = mm->start_brk;
329 * Check against rlimit here. If this check is done later after the test
330 * of oldbrk with newbrk then it can escape the test and let the data
331 * segment grow beyond its set limit the in case where the limit is
332 * not page aligned -Ram Gupta
334 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
335 mm->end_data, mm->start_data))
338 newbrk = PAGE_ALIGN(brk);
339 oldbrk = PAGE_ALIGN(mm->brk);
340 if (oldbrk == newbrk)
343 /* Always allow shrinking brk. */
344 if (brk <= mm->brk) {
345 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
350 /* Check against existing mmap mappings. */
351 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
354 /* Ok, looks good - let it rip. */
355 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
360 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
361 up_write(&mm->mmap_sem);
363 mm_populate(oldbrk, newbrk - oldbrk);
368 up_write(&mm->mmap_sem);
372 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
374 unsigned long max, subtree_gap;
377 max -= vma->vm_prev->vm_end;
378 if (vma->vm_rb.rb_left) {
379 subtree_gap = rb_entry(vma->vm_rb.rb_left,
380 struct vm_area_struct, vm_rb)->rb_subtree_gap;
381 if (subtree_gap > max)
384 if (vma->vm_rb.rb_right) {
385 subtree_gap = rb_entry(vma->vm_rb.rb_right,
386 struct vm_area_struct, vm_rb)->rb_subtree_gap;
387 if (subtree_gap > max)
393 #ifdef CONFIG_DEBUG_VM_RB
394 static int browse_rb(struct mm_struct *mm)
396 struct rb_root *root = &mm->mm_rb;
397 int i = 0, j, bug = 0;
398 struct rb_node *nd, *pn = NULL;
399 unsigned long prev = 0, pend = 0;
401 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
402 struct vm_area_struct *vma;
403 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
404 if (vma->vm_start < prev) {
405 pr_emerg("vm_start %lx < prev %lx\n",
406 vma->vm_start, prev);
409 if (vma->vm_start < pend) {
410 pr_emerg("vm_start %lx < pend %lx\n",
411 vma->vm_start, pend);
414 if (vma->vm_start > vma->vm_end) {
415 pr_emerg("vm_start %lx > vm_end %lx\n",
416 vma->vm_start, vma->vm_end);
419 spin_lock(&mm->page_table_lock);
420 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
421 pr_emerg("free gap %lx, correct %lx\n",
423 vma_compute_subtree_gap(vma));
426 spin_unlock(&mm->page_table_lock);
429 prev = vma->vm_start;
433 for (nd = pn; nd; nd = rb_prev(nd))
436 pr_emerg("backwards %d, forwards %d\n", j, i);
442 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
446 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
447 struct vm_area_struct *vma;
448 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
449 VM_BUG_ON_VMA(vma != ignore &&
450 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
455 static void validate_mm(struct mm_struct *mm)
459 unsigned long highest_address = 0;
460 struct vm_area_struct *vma = mm->mmap;
463 struct anon_vma *anon_vma = vma->anon_vma;
464 struct anon_vma_chain *avc;
467 anon_vma_lock_read(anon_vma);
468 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
469 anon_vma_interval_tree_verify(avc);
470 anon_vma_unlock_read(anon_vma);
473 highest_address = vma->vm_end;
477 if (i != mm->map_count) {
478 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
481 if (highest_address != mm->highest_vm_end) {
482 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
483 mm->highest_vm_end, highest_address);
487 if (i != mm->map_count) {
489 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
492 VM_BUG_ON_MM(bug, mm);
495 #define validate_mm_rb(root, ignore) do { } while (0)
496 #define validate_mm(mm) do { } while (0)
499 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
500 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
503 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
504 * vma->vm_prev->vm_end values changed, without modifying the vma's position
507 static void vma_gap_update(struct vm_area_struct *vma)
510 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
511 * function that does exacltly what we want.
513 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
516 static inline void vma_rb_insert(struct vm_area_struct *vma,
517 struct rb_root *root)
519 /* All rb_subtree_gap values must be consistent prior to insertion */
520 validate_mm_rb(root, NULL);
522 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
525 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
528 * All rb_subtree_gap values must be consistent prior to erase,
529 * with the possible exception of the vma being erased.
531 validate_mm_rb(root, vma);
534 * Note rb_erase_augmented is a fairly large inline function,
535 * so make sure we instantiate it only once with our desired
536 * augmented rbtree callbacks.
538 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
542 * vma has some anon_vma assigned, and is already inserted on that
543 * anon_vma's interval trees.
545 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
546 * vma must be removed from the anon_vma's interval trees using
547 * anon_vma_interval_tree_pre_update_vma().
549 * After the update, the vma will be reinserted using
550 * anon_vma_interval_tree_post_update_vma().
552 * The entire update must be protected by exclusive mmap_sem and by
553 * the root anon_vma's mutex.
556 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
558 struct anon_vma_chain *avc;
560 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
561 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
565 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
567 struct anon_vma_chain *avc;
569 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
570 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
573 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
574 unsigned long end, struct vm_area_struct **pprev,
575 struct rb_node ***rb_link, struct rb_node **rb_parent)
577 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
579 __rb_link = &mm->mm_rb.rb_node;
580 rb_prev = __rb_parent = NULL;
583 struct vm_area_struct *vma_tmp;
585 __rb_parent = *__rb_link;
586 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
588 if (vma_tmp->vm_end > addr) {
589 /* Fail if an existing vma overlaps the area */
590 if (vma_tmp->vm_start < end)
592 __rb_link = &__rb_parent->rb_left;
594 rb_prev = __rb_parent;
595 __rb_link = &__rb_parent->rb_right;
601 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
602 *rb_link = __rb_link;
603 *rb_parent = __rb_parent;
607 static unsigned long count_vma_pages_range(struct mm_struct *mm,
608 unsigned long addr, unsigned long end)
610 unsigned long nr_pages = 0;
611 struct vm_area_struct *vma;
613 /* Find first overlaping mapping */
614 vma = find_vma_intersection(mm, addr, end);
618 nr_pages = (min(end, vma->vm_end) -
619 max(addr, vma->vm_start)) >> PAGE_SHIFT;
621 /* Iterate over the rest of the overlaps */
622 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
623 unsigned long overlap_len;
625 if (vma->vm_start > end)
628 overlap_len = min(end, vma->vm_end) - vma->vm_start;
629 nr_pages += overlap_len >> PAGE_SHIFT;
635 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
636 struct rb_node **rb_link, struct rb_node *rb_parent)
638 /* Update tracking information for the gap following the new vma. */
640 vma_gap_update(vma->vm_next);
642 mm->highest_vm_end = vma->vm_end;
645 * vma->vm_prev wasn't known when we followed the rbtree to find the
646 * correct insertion point for that vma. As a result, we could not
647 * update the vma vm_rb parents rb_subtree_gap values on the way down.
648 * So, we first insert the vma with a zero rb_subtree_gap value
649 * (to be consistent with what we did on the way down), and then
650 * immediately update the gap to the correct value. Finally we
651 * rebalance the rbtree after all augmented values have been set.
653 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
654 vma->rb_subtree_gap = 0;
656 vma_rb_insert(vma, &mm->mm_rb);
659 static void __vma_link_file(struct vm_area_struct *vma)
665 struct address_space *mapping = file->f_mapping;
667 if (vma->vm_flags & VM_DENYWRITE)
668 atomic_dec(&file_inode(file)->i_writecount);
669 if (vma->vm_flags & VM_SHARED)
670 atomic_inc(&mapping->i_mmap_writable);
672 flush_dcache_mmap_lock(mapping);
673 vma_interval_tree_insert(vma, &mapping->i_mmap);
674 flush_dcache_mmap_unlock(mapping);
679 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
680 struct vm_area_struct *prev, struct rb_node **rb_link,
681 struct rb_node *rb_parent)
683 __vma_link_list(mm, vma, prev, rb_parent);
684 __vma_link_rb(mm, vma, rb_link, rb_parent);
687 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
688 struct vm_area_struct *prev, struct rb_node **rb_link,
689 struct rb_node *rb_parent)
691 struct address_space *mapping = NULL;
694 mapping = vma->vm_file->f_mapping;
695 i_mmap_lock_write(mapping);
698 __vma_link(mm, vma, prev, rb_link, rb_parent);
699 __vma_link_file(vma);
702 i_mmap_unlock_write(mapping);
709 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
710 * mm's list and rbtree. It has already been inserted into the interval tree.
712 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
714 struct vm_area_struct *prev;
715 struct rb_node **rb_link, *rb_parent;
717 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
718 &prev, &rb_link, &rb_parent))
720 __vma_link(mm, vma, prev, rb_link, rb_parent);
725 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
726 struct vm_area_struct *prev)
728 struct vm_area_struct *next;
730 vma_rb_erase(vma, &mm->mm_rb);
731 prev->vm_next = next = vma->vm_next;
733 next->vm_prev = prev;
736 vmacache_invalidate(mm);
740 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
741 * is already present in an i_mmap tree without adjusting the tree.
742 * The following helper function should be used when such adjustments
743 * are necessary. The "insert" vma (if any) is to be inserted
744 * before we drop the necessary locks.
746 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
747 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
749 struct mm_struct *mm = vma->vm_mm;
750 struct vm_area_struct *next = vma->vm_next;
751 struct vm_area_struct *importer = NULL;
752 struct address_space *mapping = NULL;
753 struct rb_root *root = NULL;
754 struct anon_vma *anon_vma = NULL;
755 struct file *file = vma->vm_file;
756 bool start_changed = false, end_changed = false;
757 long adjust_next = 0;
760 if (next && !insert) {
761 struct vm_area_struct *exporter = NULL;
763 if (end >= next->vm_end) {
765 * vma expands, overlapping all the next, and
766 * perhaps the one after too (mprotect case 6).
768 again: remove_next = 1 + (end > next->vm_end);
772 } else if (end > next->vm_start) {
774 * vma expands, overlapping part of the next:
775 * mprotect case 5 shifting the boundary up.
777 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
780 } else if (end < vma->vm_end) {
782 * vma shrinks, and !insert tells it's not
783 * split_vma inserting another: so it must be
784 * mprotect case 4 shifting the boundary down.
786 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
792 * Easily overlooked: when mprotect shifts the boundary,
793 * make sure the expanding vma has anon_vma set if the
794 * shrinking vma had, to cover any anon pages imported.
796 if (exporter && exporter->anon_vma && !importer->anon_vma) {
799 importer->anon_vma = exporter->anon_vma;
800 error = anon_vma_clone(importer, exporter);
807 mapping = file->f_mapping;
808 root = &mapping->i_mmap;
809 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
812 uprobe_munmap(next, next->vm_start, next->vm_end);
814 i_mmap_lock_write(mapping);
817 * Put into interval tree now, so instantiated pages
818 * are visible to arm/parisc __flush_dcache_page
819 * throughout; but we cannot insert into address
820 * space until vma start or end is updated.
822 __vma_link_file(insert);
826 vma_adjust_trans_huge(vma, start, end, adjust_next);
828 anon_vma = vma->anon_vma;
829 if (!anon_vma && adjust_next)
830 anon_vma = next->anon_vma;
832 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
833 anon_vma != next->anon_vma, next);
834 anon_vma_lock_write(anon_vma);
835 anon_vma_interval_tree_pre_update_vma(vma);
837 anon_vma_interval_tree_pre_update_vma(next);
841 flush_dcache_mmap_lock(mapping);
842 vma_interval_tree_remove(vma, root);
844 vma_interval_tree_remove(next, root);
847 if (start != vma->vm_start) {
848 vma->vm_start = start;
849 start_changed = true;
851 if (end != vma->vm_end) {
855 vma->vm_pgoff = pgoff;
857 next->vm_start += adjust_next << PAGE_SHIFT;
858 next->vm_pgoff += adjust_next;
863 vma_interval_tree_insert(next, root);
864 vma_interval_tree_insert(vma, root);
865 flush_dcache_mmap_unlock(mapping);
870 * vma_merge has merged next into vma, and needs
871 * us to remove next before dropping the locks.
873 __vma_unlink(mm, next, vma);
875 __remove_shared_vm_struct(next, file, mapping);
878 * split_vma has split insert from vma, and needs
879 * us to insert it before dropping the locks
880 * (it may either follow vma or precede it).
882 __insert_vm_struct(mm, insert);
888 mm->highest_vm_end = end;
889 else if (!adjust_next)
890 vma_gap_update(next);
895 anon_vma_interval_tree_post_update_vma(vma);
897 anon_vma_interval_tree_post_update_vma(next);
898 anon_vma_unlock_write(anon_vma);
901 i_mmap_unlock_write(mapping);
912 uprobe_munmap(next, next->vm_start, next->vm_end);
916 anon_vma_merge(vma, next);
918 mpol_put(vma_policy(next));
919 kmem_cache_free(vm_area_cachep, next);
921 * In mprotect's case 6 (see comments on vma_merge),
922 * we must remove another next too. It would clutter
923 * up the code too much to do both in one go.
926 if (remove_next == 2)
929 vma_gap_update(next);
931 mm->highest_vm_end = end;
942 * If the vma has a ->close operation then the driver probably needs to release
943 * per-vma resources, so we don't attempt to merge those.
945 static inline int is_mergeable_vma(struct vm_area_struct *vma,
946 struct file *file, unsigned long vm_flags,
947 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
950 * VM_SOFTDIRTY should not prevent from VMA merging, if we
951 * match the flags but dirty bit -- the caller should mark
952 * merged VMA as dirty. If dirty bit won't be excluded from
953 * comparison, we increase pressue on the memory system forcing
954 * the kernel to generate new VMAs when old one could be
957 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
959 if (vma->vm_file != file)
961 if (vma->vm_ops && vma->vm_ops->close)
963 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
968 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
969 struct anon_vma *anon_vma2,
970 struct vm_area_struct *vma)
973 * The list_is_singular() test is to avoid merging VMA cloned from
974 * parents. This can improve scalability caused by anon_vma lock.
976 if ((!anon_vma1 || !anon_vma2) && (!vma ||
977 list_is_singular(&vma->anon_vma_chain)))
979 return anon_vma1 == anon_vma2;
983 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
984 * in front of (at a lower virtual address and file offset than) the vma.
986 * We cannot merge two vmas if they have differently assigned (non-NULL)
987 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
989 * We don't check here for the merged mmap wrapping around the end of pagecache
990 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
991 * wrap, nor mmaps which cover the final page at index -1UL.
994 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
995 struct anon_vma *anon_vma, struct file *file,
997 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
999 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1000 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1001 if (vma->vm_pgoff == vm_pgoff)
1008 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1009 * beyond (at a higher virtual address and file offset than) the vma.
1011 * We cannot merge two vmas if they have differently assigned (non-NULL)
1012 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1015 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1016 struct anon_vma *anon_vma, struct file *file,
1018 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1020 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1021 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1023 vm_pglen = vma_pages(vma);
1024 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1031 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1032 * whether that can be merged with its predecessor or its successor.
1033 * Or both (it neatly fills a hole).
1035 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1036 * certain not to be mapped by the time vma_merge is called; but when
1037 * called for mprotect, it is certain to be already mapped (either at
1038 * an offset within prev, or at the start of next), and the flags of
1039 * this area are about to be changed to vm_flags - and the no-change
1040 * case has already been eliminated.
1042 * The following mprotect cases have to be considered, where AAAA is
1043 * the area passed down from mprotect_fixup, never extending beyond one
1044 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1046 * AAAA AAAA AAAA AAAA
1047 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1048 * cannot merge might become might become might become
1049 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1050 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1051 * mremap move: PPPPNNNNNNNN 8
1053 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1054 * might become case 1 below case 2 below case 3 below
1056 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1057 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1059 struct vm_area_struct *vma_merge(struct mm_struct *mm,
1060 struct vm_area_struct *prev, unsigned long addr,
1061 unsigned long end, unsigned long vm_flags,
1062 struct anon_vma *anon_vma, struct file *file,
1063 pgoff_t pgoff, struct mempolicy *policy,
1064 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1066 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1067 struct vm_area_struct *area, *next;
1071 * We later require that vma->vm_flags == vm_flags,
1072 * so this tests vma->vm_flags & VM_SPECIAL, too.
1074 if (vm_flags & VM_SPECIAL)
1078 next = prev->vm_next;
1082 if (next && next->vm_end == end) /* cases 6, 7, 8 */
1083 next = next->vm_next;
1086 * Can it merge with the predecessor?
1088 if (prev && prev->vm_end == addr &&
1089 mpol_equal(vma_policy(prev), policy) &&
1090 can_vma_merge_after(prev, vm_flags,
1091 anon_vma, file, pgoff,
1092 vm_userfaultfd_ctx)) {
1094 * OK, it can. Can we now merge in the successor as well?
1096 if (next && end == next->vm_start &&
1097 mpol_equal(policy, vma_policy(next)) &&
1098 can_vma_merge_before(next, vm_flags,
1101 vm_userfaultfd_ctx) &&
1102 is_mergeable_anon_vma(prev->anon_vma,
1103 next->anon_vma, NULL)) {
1105 err = vma_adjust(prev, prev->vm_start,
1106 next->vm_end, prev->vm_pgoff, NULL);
1107 } else /* cases 2, 5, 7 */
1108 err = vma_adjust(prev, prev->vm_start,
1109 end, prev->vm_pgoff, NULL);
1112 khugepaged_enter_vma_merge(prev, vm_flags);
1117 * Can this new request be merged in front of next?
1119 if (next && end == next->vm_start &&
1120 mpol_equal(policy, vma_policy(next)) &&
1121 can_vma_merge_before(next, vm_flags,
1122 anon_vma, file, pgoff+pglen,
1123 vm_userfaultfd_ctx)) {
1124 if (prev && addr < prev->vm_end) /* case 4 */
1125 err = vma_adjust(prev, prev->vm_start,
1126 addr, prev->vm_pgoff, NULL);
1127 else /* cases 3, 8 */
1128 err = vma_adjust(area, addr, next->vm_end,
1129 next->vm_pgoff - pglen, NULL);
1132 khugepaged_enter_vma_merge(area, vm_flags);
1140 * Rough compatbility check to quickly see if it's even worth looking
1141 * at sharing an anon_vma.
1143 * They need to have the same vm_file, and the flags can only differ
1144 * in things that mprotect may change.
1146 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1147 * we can merge the two vma's. For example, we refuse to merge a vma if
1148 * there is a vm_ops->close() function, because that indicates that the
1149 * driver is doing some kind of reference counting. But that doesn't
1150 * really matter for the anon_vma sharing case.
1152 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1154 return a->vm_end == b->vm_start &&
1155 mpol_equal(vma_policy(a), vma_policy(b)) &&
1156 a->vm_file == b->vm_file &&
1157 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1158 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1162 * Do some basic sanity checking to see if we can re-use the anon_vma
1163 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1164 * the same as 'old', the other will be the new one that is trying
1165 * to share the anon_vma.
1167 * NOTE! This runs with mm_sem held for reading, so it is possible that
1168 * the anon_vma of 'old' is concurrently in the process of being set up
1169 * by another page fault trying to merge _that_. But that's ok: if it
1170 * is being set up, that automatically means that it will be a singleton
1171 * acceptable for merging, so we can do all of this optimistically. But
1172 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1174 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1175 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1176 * is to return an anon_vma that is "complex" due to having gone through
1179 * We also make sure that the two vma's are compatible (adjacent,
1180 * and with the same memory policies). That's all stable, even with just
1181 * a read lock on the mm_sem.
1183 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1185 if (anon_vma_compatible(a, b)) {
1186 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1188 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1195 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1196 * neighbouring vmas for a suitable anon_vma, before it goes off
1197 * to allocate a new anon_vma. It checks because a repetitive
1198 * sequence of mprotects and faults may otherwise lead to distinct
1199 * anon_vmas being allocated, preventing vma merge in subsequent
1202 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1204 struct anon_vma *anon_vma;
1205 struct vm_area_struct *near;
1207 near = vma->vm_next;
1211 anon_vma = reusable_anon_vma(near, vma, near);
1215 near = vma->vm_prev;
1219 anon_vma = reusable_anon_vma(near, near, vma);
1224 * There's no absolute need to look only at touching neighbours:
1225 * we could search further afield for "compatible" anon_vmas.
1226 * But it would probably just be a waste of time searching,
1227 * or lead to too many vmas hanging off the same anon_vma.
1228 * We're trying to allow mprotect remerging later on,
1229 * not trying to minimize memory used for anon_vmas.
1235 * If a hint addr is less than mmap_min_addr change hint to be as
1236 * low as possible but still greater than mmap_min_addr
1238 static inline unsigned long round_hint_to_min(unsigned long hint)
1241 if (((void *)hint != NULL) &&
1242 (hint < mmap_min_addr))
1243 return PAGE_ALIGN(mmap_min_addr);
1247 static inline int mlock_future_check(struct mm_struct *mm,
1248 unsigned long flags,
1251 unsigned long locked, lock_limit;
1253 /* mlock MCL_FUTURE? */
1254 if (flags & VM_LOCKED) {
1255 locked = len >> PAGE_SHIFT;
1256 locked += mm->locked_vm;
1257 lock_limit = rlimit(RLIMIT_MEMLOCK);
1258 lock_limit >>= PAGE_SHIFT;
1259 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1266 * The caller must hold down_write(¤t->mm->mmap_sem).
1268 unsigned long do_mmap(struct file *file, unsigned long addr,
1269 unsigned long len, unsigned long prot,
1270 unsigned long flags, vm_flags_t vm_flags,
1271 unsigned long pgoff, unsigned long *populate)
1273 struct mm_struct *mm = current->mm;
1282 * Does the application expect PROT_READ to imply PROT_EXEC?
1284 * (the exception is when the underlying filesystem is noexec
1285 * mounted, in which case we dont add PROT_EXEC.)
1287 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1288 if (!(file && path_noexec(&file->f_path)))
1291 if (!(flags & MAP_FIXED))
1292 addr = round_hint_to_min(addr);
1294 /* Careful about overflows.. */
1295 len = PAGE_ALIGN(len);
1299 /* offset overflow? */
1300 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1303 /* Too many mappings? */
1304 if (mm->map_count > sysctl_max_map_count)
1307 /* Obtain the address to map to. we verify (or select) it and ensure
1308 * that it represents a valid section of the address space.
1310 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1311 if (offset_in_page(addr))
1314 if (prot == PROT_EXEC) {
1315 pkey = execute_only_pkey(mm);
1320 /* Do simple checking here so the lower-level routines won't have
1321 * to. we assume access permissions have been handled by the open
1322 * of the memory object, so we don't do any here.
1324 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1325 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1327 if (flags & MAP_LOCKED)
1328 if (!can_do_mlock())
1331 if (mlock_future_check(mm, vm_flags, len))
1335 struct inode *inode = file_inode(file);
1337 switch (flags & MAP_TYPE) {
1339 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1343 * Make sure we don't allow writing to an append-only
1346 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1350 * Make sure there are no mandatory locks on the file.
1352 if (locks_verify_locked(file))
1355 vm_flags |= VM_SHARED | VM_MAYSHARE;
1356 if (!(file->f_mode & FMODE_WRITE))
1357 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1361 if (!(file->f_mode & FMODE_READ))
1363 if (path_noexec(&file->f_path)) {
1364 if (vm_flags & VM_EXEC)
1366 vm_flags &= ~VM_MAYEXEC;
1369 if (!file->f_op->mmap)
1371 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1379 switch (flags & MAP_TYPE) {
1381 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1387 vm_flags |= VM_SHARED | VM_MAYSHARE;
1391 * Set pgoff according to addr for anon_vma.
1393 pgoff = addr >> PAGE_SHIFT;
1401 * Set 'VM_NORESERVE' if we should not account for the
1402 * memory use of this mapping.
1404 if (flags & MAP_NORESERVE) {
1405 /* We honor MAP_NORESERVE if allowed to overcommit */
1406 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1407 vm_flags |= VM_NORESERVE;
1409 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1410 if (file && is_file_hugepages(file))
1411 vm_flags |= VM_NORESERVE;
1414 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1415 if (!IS_ERR_VALUE(addr) &&
1416 ((vm_flags & VM_LOCKED) ||
1417 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1422 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1423 unsigned long, prot, unsigned long, flags,
1424 unsigned long, fd, unsigned long, pgoff)
1426 struct file *file = NULL;
1427 unsigned long retval;
1429 if (!(flags & MAP_ANONYMOUS)) {
1430 audit_mmap_fd(fd, flags);
1434 if (is_file_hugepages(file))
1435 len = ALIGN(len, huge_page_size(hstate_file(file)));
1437 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1439 } else if (flags & MAP_HUGETLB) {
1440 struct user_struct *user = NULL;
1443 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1447 len = ALIGN(len, huge_page_size(hs));
1449 * VM_NORESERVE is used because the reservations will be
1450 * taken when vm_ops->mmap() is called
1451 * A dummy user value is used because we are not locking
1452 * memory so no accounting is necessary
1454 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1456 &user, HUGETLB_ANONHUGE_INODE,
1457 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1459 return PTR_ERR(file);
1462 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1464 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1471 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1472 struct mmap_arg_struct {
1476 unsigned long flags;
1478 unsigned long offset;
1481 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1483 struct mmap_arg_struct a;
1485 if (copy_from_user(&a, arg, sizeof(a)))
1487 if (offset_in_page(a.offset))
1490 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1491 a.offset >> PAGE_SHIFT);
1493 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1496 * Some shared mappigns will want the pages marked read-only
1497 * to track write events. If so, we'll downgrade vm_page_prot
1498 * to the private version (using protection_map[] without the
1501 int vma_wants_writenotify(struct vm_area_struct *vma)
1503 vm_flags_t vm_flags = vma->vm_flags;
1504 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1506 /* If it was private or non-writable, the write bit is already clear */
1507 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1510 /* The backer wishes to know when pages are first written to? */
1511 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1514 /* The open routine did something to the protections that pgprot_modify
1515 * won't preserve? */
1516 if (pgprot_val(vma->vm_page_prot) !=
1517 pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1520 /* Do we need to track softdirty? */
1521 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1524 /* Specialty mapping? */
1525 if (vm_flags & VM_PFNMAP)
1528 /* Can the mapping track the dirty pages? */
1529 return vma->vm_file && vma->vm_file->f_mapping &&
1530 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1534 * We account for memory if it's a private writeable mapping,
1535 * not hugepages and VM_NORESERVE wasn't set.
1537 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1540 * hugetlb has its own accounting separate from the core VM
1541 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1543 if (file && is_file_hugepages(file))
1546 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1549 unsigned long mmap_region(struct file *file, unsigned long addr,
1550 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1552 struct mm_struct *mm = current->mm;
1553 struct vm_area_struct *vma, *prev;
1555 struct rb_node **rb_link, *rb_parent;
1556 unsigned long charged = 0;
1558 /* Check against address space limit. */
1559 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1560 unsigned long nr_pages;
1563 * MAP_FIXED may remove pages of mappings that intersects with
1564 * requested mapping. Account for the pages it would unmap.
1566 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1568 if (!may_expand_vm(mm, vm_flags,
1569 (len >> PAGE_SHIFT) - nr_pages))
1573 /* Clear old maps */
1574 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1576 if (do_munmap(mm, addr, len))
1581 * Private writable mapping: check memory availability
1583 if (accountable_mapping(file, vm_flags)) {
1584 charged = len >> PAGE_SHIFT;
1585 if (security_vm_enough_memory_mm(mm, charged))
1587 vm_flags |= VM_ACCOUNT;
1591 * Can we just expand an old mapping?
1593 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1594 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1599 * Determine the object being mapped and call the appropriate
1600 * specific mapper. the address has already been validated, but
1601 * not unmapped, but the maps are removed from the list.
1603 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1610 vma->vm_start = addr;
1611 vma->vm_end = addr + len;
1612 vma->vm_flags = vm_flags;
1613 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1614 vma->vm_pgoff = pgoff;
1615 INIT_LIST_HEAD(&vma->anon_vma_chain);
1618 if (vm_flags & VM_DENYWRITE) {
1619 error = deny_write_access(file);
1623 if (vm_flags & VM_SHARED) {
1624 error = mapping_map_writable(file->f_mapping);
1626 goto allow_write_and_free_vma;
1629 /* ->mmap() can change vma->vm_file, but must guarantee that
1630 * vma_link() below can deny write-access if VM_DENYWRITE is set
1631 * and map writably if VM_SHARED is set. This usually means the
1632 * new file must not have been exposed to user-space, yet.
1634 vma->vm_file = get_file(file);
1635 error = file->f_op->mmap(file, vma);
1637 goto unmap_and_free_vma;
1639 /* Can addr have changed??
1641 * Answer: Yes, several device drivers can do it in their
1642 * f_op->mmap method. -DaveM
1643 * Bug: If addr is changed, prev, rb_link, rb_parent should
1644 * be updated for vma_link()
1646 WARN_ON_ONCE(addr != vma->vm_start);
1648 addr = vma->vm_start;
1649 vm_flags = vma->vm_flags;
1650 } else if (vm_flags & VM_SHARED) {
1651 error = shmem_zero_setup(vma);
1656 vma_link(mm, vma, prev, rb_link, rb_parent);
1657 /* Once vma denies write, undo our temporary denial count */
1659 if (vm_flags & VM_SHARED)
1660 mapping_unmap_writable(file->f_mapping);
1661 if (vm_flags & VM_DENYWRITE)
1662 allow_write_access(file);
1664 file = vma->vm_file;
1666 perf_event_mmap(vma);
1668 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1669 if (vm_flags & VM_LOCKED) {
1670 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1671 vma == get_gate_vma(current->mm)))
1672 mm->locked_vm += (len >> PAGE_SHIFT);
1674 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1681 * New (or expanded) vma always get soft dirty status.
1682 * Otherwise user-space soft-dirty page tracker won't
1683 * be able to distinguish situation when vma area unmapped,
1684 * then new mapped in-place (which must be aimed as
1685 * a completely new data area).
1687 vma->vm_flags |= VM_SOFTDIRTY;
1689 vma_set_page_prot(vma);
1694 vma->vm_file = NULL;
1697 /* Undo any partial mapping done by a device driver. */
1698 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1700 if (vm_flags & VM_SHARED)
1701 mapping_unmap_writable(file->f_mapping);
1702 allow_write_and_free_vma:
1703 if (vm_flags & VM_DENYWRITE)
1704 allow_write_access(file);
1706 kmem_cache_free(vm_area_cachep, vma);
1709 vm_unacct_memory(charged);
1713 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1716 * We implement the search by looking for an rbtree node that
1717 * immediately follows a suitable gap. That is,
1718 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1719 * - gap_end = vma->vm_start >= info->low_limit + length;
1720 * - gap_end - gap_start >= length
1723 struct mm_struct *mm = current->mm;
1724 struct vm_area_struct *vma;
1725 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1727 /* Adjust search length to account for worst case alignment overhead */
1728 length = info->length + info->align_mask;
1729 if (length < info->length)
1732 /* Adjust search limits by the desired length */
1733 if (info->high_limit < length)
1735 high_limit = info->high_limit - length;
1737 if (info->low_limit > high_limit)
1739 low_limit = info->low_limit + length;
1741 /* Check if rbtree root looks promising */
1742 if (RB_EMPTY_ROOT(&mm->mm_rb))
1744 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1745 if (vma->rb_subtree_gap < length)
1749 /* Visit left subtree if it looks promising */
1750 gap_end = vma->vm_start;
1751 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1752 struct vm_area_struct *left =
1753 rb_entry(vma->vm_rb.rb_left,
1754 struct vm_area_struct, vm_rb);
1755 if (left->rb_subtree_gap >= length) {
1761 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1763 /* Check if current node has a suitable gap */
1764 if (gap_start > high_limit)
1766 if (gap_end >= low_limit && gap_end - gap_start >= length)
1769 /* Visit right subtree if it looks promising */
1770 if (vma->vm_rb.rb_right) {
1771 struct vm_area_struct *right =
1772 rb_entry(vma->vm_rb.rb_right,
1773 struct vm_area_struct, vm_rb);
1774 if (right->rb_subtree_gap >= length) {
1780 /* Go back up the rbtree to find next candidate node */
1782 struct rb_node *prev = &vma->vm_rb;
1783 if (!rb_parent(prev))
1785 vma = rb_entry(rb_parent(prev),
1786 struct vm_area_struct, vm_rb);
1787 if (prev == vma->vm_rb.rb_left) {
1788 gap_start = vma->vm_prev->vm_end;
1789 gap_end = vma->vm_start;
1796 /* Check highest gap, which does not precede any rbtree node */
1797 gap_start = mm->highest_vm_end;
1798 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1799 if (gap_start > high_limit)
1803 /* We found a suitable gap. Clip it with the original low_limit. */
1804 if (gap_start < info->low_limit)
1805 gap_start = info->low_limit;
1807 /* Adjust gap address to the desired alignment */
1808 gap_start += (info->align_offset - gap_start) & info->align_mask;
1810 VM_BUG_ON(gap_start + info->length > info->high_limit);
1811 VM_BUG_ON(gap_start + info->length > gap_end);
1815 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1817 struct mm_struct *mm = current->mm;
1818 struct vm_area_struct *vma;
1819 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1821 /* Adjust search length to account for worst case alignment overhead */
1822 length = info->length + info->align_mask;
1823 if (length < info->length)
1827 * Adjust search limits by the desired length.
1828 * See implementation comment at top of unmapped_area().
1830 gap_end = info->high_limit;
1831 if (gap_end < length)
1833 high_limit = gap_end - length;
1835 if (info->low_limit > high_limit)
1837 low_limit = info->low_limit + length;
1839 /* Check highest gap, which does not precede any rbtree node */
1840 gap_start = mm->highest_vm_end;
1841 if (gap_start <= high_limit)
1844 /* Check if rbtree root looks promising */
1845 if (RB_EMPTY_ROOT(&mm->mm_rb))
1847 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1848 if (vma->rb_subtree_gap < length)
1852 /* Visit right subtree if it looks promising */
1853 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1854 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1855 struct vm_area_struct *right =
1856 rb_entry(vma->vm_rb.rb_right,
1857 struct vm_area_struct, vm_rb);
1858 if (right->rb_subtree_gap >= length) {
1865 /* Check if current node has a suitable gap */
1866 gap_end = vma->vm_start;
1867 if (gap_end < low_limit)
1869 if (gap_start <= high_limit && gap_end - gap_start >= length)
1872 /* Visit left subtree if it looks promising */
1873 if (vma->vm_rb.rb_left) {
1874 struct vm_area_struct *left =
1875 rb_entry(vma->vm_rb.rb_left,
1876 struct vm_area_struct, vm_rb);
1877 if (left->rb_subtree_gap >= length) {
1883 /* Go back up the rbtree to find next candidate node */
1885 struct rb_node *prev = &vma->vm_rb;
1886 if (!rb_parent(prev))
1888 vma = rb_entry(rb_parent(prev),
1889 struct vm_area_struct, vm_rb);
1890 if (prev == vma->vm_rb.rb_right) {
1891 gap_start = vma->vm_prev ?
1892 vma->vm_prev->vm_end : 0;
1899 /* We found a suitable gap. Clip it with the original high_limit. */
1900 if (gap_end > info->high_limit)
1901 gap_end = info->high_limit;
1904 /* Compute highest gap address at the desired alignment */
1905 gap_end -= info->length;
1906 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1908 VM_BUG_ON(gap_end < info->low_limit);
1909 VM_BUG_ON(gap_end < gap_start);
1913 /* Get an address range which is currently unmapped.
1914 * For shmat() with addr=0.
1916 * Ugly calling convention alert:
1917 * Return value with the low bits set means error value,
1919 * if (ret & ~PAGE_MASK)
1922 * This function "knows" that -ENOMEM has the bits set.
1924 #ifndef HAVE_ARCH_UNMAPPED_AREA
1926 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1927 unsigned long len, unsigned long pgoff, unsigned long flags)
1929 struct mm_struct *mm = current->mm;
1930 struct vm_area_struct *vma;
1931 struct vm_unmapped_area_info info;
1933 if (len > TASK_SIZE - mmap_min_addr)
1936 if (flags & MAP_FIXED)
1940 addr = PAGE_ALIGN(addr);
1941 vma = find_vma(mm, addr);
1942 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1943 (!vma || addr + len <= vma->vm_start))
1949 info.low_limit = mm->mmap_base;
1950 info.high_limit = TASK_SIZE;
1951 info.align_mask = 0;
1952 return vm_unmapped_area(&info);
1957 * This mmap-allocator allocates new areas top-down from below the
1958 * stack's low limit (the base):
1960 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1962 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1963 const unsigned long len, const unsigned long pgoff,
1964 const unsigned long flags)
1966 struct vm_area_struct *vma;
1967 struct mm_struct *mm = current->mm;
1968 unsigned long addr = addr0;
1969 struct vm_unmapped_area_info info;
1971 /* requested length too big for entire address space */
1972 if (len > TASK_SIZE - mmap_min_addr)
1975 if (flags & MAP_FIXED)
1978 /* requesting a specific address */
1980 addr = PAGE_ALIGN(addr);
1981 vma = find_vma(mm, addr);
1982 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1983 (!vma || addr + len <= vma->vm_start))
1987 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1989 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1990 info.high_limit = mm->mmap_base;
1991 info.align_mask = 0;
1992 addr = vm_unmapped_area(&info);
1995 * A failed mmap() very likely causes application failure,
1996 * so fall back to the bottom-up function here. This scenario
1997 * can happen with large stack limits and large mmap()
2000 if (offset_in_page(addr)) {
2001 VM_BUG_ON(addr != -ENOMEM);
2003 info.low_limit = TASK_UNMAPPED_BASE;
2004 info.high_limit = TASK_SIZE;
2005 addr = vm_unmapped_area(&info);
2013 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2014 unsigned long pgoff, unsigned long flags)
2016 unsigned long (*get_area)(struct file *, unsigned long,
2017 unsigned long, unsigned long, unsigned long);
2019 unsigned long error = arch_mmap_check(addr, len, flags);
2023 /* Careful about overflows.. */
2024 if (len > TASK_SIZE)
2027 get_area = current->mm->get_unmapped_area;
2028 if (file && file->f_op->get_unmapped_area)
2029 get_area = file->f_op->get_unmapped_area;
2030 addr = get_area(file, addr, len, pgoff, flags);
2031 if (IS_ERR_VALUE(addr))
2034 if (addr > TASK_SIZE - len)
2036 if (offset_in_page(addr))
2039 addr = arch_rebalance_pgtables(addr, len);
2040 error = security_mmap_addr(addr);
2041 return error ? error : addr;
2044 EXPORT_SYMBOL(get_unmapped_area);
2046 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2047 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2049 struct rb_node *rb_node;
2050 struct vm_area_struct *vma;
2052 /* Check the cache first. */
2053 vma = vmacache_find(mm, addr);
2057 rb_node = mm->mm_rb.rb_node;
2060 struct vm_area_struct *tmp;
2062 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2064 if (tmp->vm_end > addr) {
2066 if (tmp->vm_start <= addr)
2068 rb_node = rb_node->rb_left;
2070 rb_node = rb_node->rb_right;
2074 vmacache_update(addr, vma);
2078 EXPORT_SYMBOL(find_vma);
2081 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2083 struct vm_area_struct *
2084 find_vma_prev(struct mm_struct *mm, unsigned long addr,
2085 struct vm_area_struct **pprev)
2087 struct vm_area_struct *vma;
2089 vma = find_vma(mm, addr);
2091 *pprev = vma->vm_prev;
2093 struct rb_node *rb_node = mm->mm_rb.rb_node;
2096 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2097 rb_node = rb_node->rb_right;
2104 * Verify that the stack growth is acceptable and
2105 * update accounting. This is shared with both the
2106 * grow-up and grow-down cases.
2108 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2110 struct mm_struct *mm = vma->vm_mm;
2111 struct rlimit *rlim = current->signal->rlim;
2112 unsigned long new_start, actual_size;
2114 /* address space limit tests */
2115 if (!may_expand_vm(mm, vma->vm_flags, grow))
2118 /* Stack limit test */
2120 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2121 actual_size -= PAGE_SIZE;
2122 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2125 /* mlock limit tests */
2126 if (vma->vm_flags & VM_LOCKED) {
2127 unsigned long locked;
2128 unsigned long limit;
2129 locked = mm->locked_vm + grow;
2130 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2131 limit >>= PAGE_SHIFT;
2132 if (locked > limit && !capable(CAP_IPC_LOCK))
2136 /* Check to ensure the stack will not grow into a hugetlb-only region */
2137 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2139 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2143 * Overcommit.. This must be the final test, as it will
2144 * update security statistics.
2146 if (security_vm_enough_memory_mm(mm, grow))
2152 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2154 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2155 * vma is the last one with address > vma->vm_end. Have to extend vma.
2157 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2159 struct mm_struct *mm = vma->vm_mm;
2162 if (!(vma->vm_flags & VM_GROWSUP))
2165 /* Guard against wrapping around to address 0. */
2166 if (address < PAGE_ALIGN(address+4))
2167 address = PAGE_ALIGN(address+4);
2171 /* We must make sure the anon_vma is allocated. */
2172 if (unlikely(anon_vma_prepare(vma)))
2176 * vma->vm_start/vm_end cannot change under us because the caller
2177 * is required to hold the mmap_sem in read mode. We need the
2178 * anon_vma lock to serialize against concurrent expand_stacks.
2180 anon_vma_lock_write(vma->anon_vma);
2182 /* Somebody else might have raced and expanded it already */
2183 if (address > vma->vm_end) {
2184 unsigned long size, grow;
2186 size = address - vma->vm_start;
2187 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2190 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2191 error = acct_stack_growth(vma, size, grow);
2194 * vma_gap_update() doesn't support concurrent
2195 * updates, but we only hold a shared mmap_sem
2196 * lock here, so we need to protect against
2197 * concurrent vma expansions.
2198 * anon_vma_lock_write() doesn't help here, as
2199 * we don't guarantee that all growable vmas
2200 * in a mm share the same root anon vma.
2201 * So, we reuse mm->page_table_lock to guard
2202 * against concurrent vma expansions.
2204 spin_lock(&mm->page_table_lock);
2205 if (vma->vm_flags & VM_LOCKED)
2206 mm->locked_vm += grow;
2207 vm_stat_account(mm, vma->vm_flags, grow);
2208 anon_vma_interval_tree_pre_update_vma(vma);
2209 vma->vm_end = address;
2210 anon_vma_interval_tree_post_update_vma(vma);
2212 vma_gap_update(vma->vm_next);
2214 mm->highest_vm_end = address;
2215 spin_unlock(&mm->page_table_lock);
2217 perf_event_mmap(vma);
2221 anon_vma_unlock_write(vma->anon_vma);
2222 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2226 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2229 * vma is the first one with address < vma->vm_start. Have to extend vma.
2231 int expand_downwards(struct vm_area_struct *vma,
2232 unsigned long address)
2234 struct mm_struct *mm = vma->vm_mm;
2237 address &= PAGE_MASK;
2238 error = security_mmap_addr(address);
2242 /* We must make sure the anon_vma is allocated. */
2243 if (unlikely(anon_vma_prepare(vma)))
2247 * vma->vm_start/vm_end cannot change under us because the caller
2248 * is required to hold the mmap_sem in read mode. We need the
2249 * anon_vma lock to serialize against concurrent expand_stacks.
2251 anon_vma_lock_write(vma->anon_vma);
2253 /* Somebody else might have raced and expanded it already */
2254 if (address < vma->vm_start) {
2255 unsigned long size, grow;
2257 size = vma->vm_end - address;
2258 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2261 if (grow <= vma->vm_pgoff) {
2262 error = acct_stack_growth(vma, size, grow);
2265 * vma_gap_update() doesn't support concurrent
2266 * updates, but we only hold a shared mmap_sem
2267 * lock here, so we need to protect against
2268 * concurrent vma expansions.
2269 * anon_vma_lock_write() doesn't help here, as
2270 * we don't guarantee that all growable vmas
2271 * in a mm share the same root anon vma.
2272 * So, we reuse mm->page_table_lock to guard
2273 * against concurrent vma expansions.
2275 spin_lock(&mm->page_table_lock);
2276 if (vma->vm_flags & VM_LOCKED)
2277 mm->locked_vm += grow;
2278 vm_stat_account(mm, vma->vm_flags, grow);
2279 anon_vma_interval_tree_pre_update_vma(vma);
2280 vma->vm_start = address;
2281 vma->vm_pgoff -= grow;
2282 anon_vma_interval_tree_post_update_vma(vma);
2283 vma_gap_update(vma);
2284 spin_unlock(&mm->page_table_lock);
2286 perf_event_mmap(vma);
2290 anon_vma_unlock_write(vma->anon_vma);
2291 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2297 * Note how expand_stack() refuses to expand the stack all the way to
2298 * abut the next virtual mapping, *unless* that mapping itself is also
2299 * a stack mapping. We want to leave room for a guard page, after all
2300 * (the guard page itself is not added here, that is done by the
2301 * actual page faulting logic)
2303 * This matches the behavior of the guard page logic (see mm/memory.c:
2304 * check_stack_guard_page()), which only allows the guard page to be
2305 * removed under these circumstances.
2307 #ifdef CONFIG_STACK_GROWSUP
2308 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2310 struct vm_area_struct *next;
2312 address &= PAGE_MASK;
2313 next = vma->vm_next;
2314 if (next && next->vm_start == address + PAGE_SIZE) {
2315 if (!(next->vm_flags & VM_GROWSUP))
2318 return expand_upwards(vma, address);
2321 struct vm_area_struct *
2322 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2324 struct vm_area_struct *vma, *prev;
2327 vma = find_vma_prev(mm, addr, &prev);
2328 if (vma && (vma->vm_start <= addr))
2330 if (!prev || expand_stack(prev, addr))
2332 if (prev->vm_flags & VM_LOCKED)
2333 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2337 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2339 struct vm_area_struct *prev;
2341 address &= PAGE_MASK;
2342 prev = vma->vm_prev;
2343 if (prev && prev->vm_end == address) {
2344 if (!(prev->vm_flags & VM_GROWSDOWN))
2347 return expand_downwards(vma, address);
2350 struct vm_area_struct *
2351 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2353 struct vm_area_struct *vma;
2354 unsigned long start;
2357 vma = find_vma(mm, addr);
2360 if (vma->vm_start <= addr)
2362 if (!(vma->vm_flags & VM_GROWSDOWN))
2364 start = vma->vm_start;
2365 if (expand_stack(vma, addr))
2367 if (vma->vm_flags & VM_LOCKED)
2368 populate_vma_page_range(vma, addr, start, NULL);
2373 EXPORT_SYMBOL_GPL(find_extend_vma);
2376 * Ok - we have the memory areas we should free on the vma list,
2377 * so release them, and do the vma updates.
2379 * Called with the mm semaphore held.
2381 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2383 unsigned long nr_accounted = 0;
2385 /* Update high watermark before we lower total_vm */
2386 update_hiwater_vm(mm);
2388 long nrpages = vma_pages(vma);
2390 if (vma->vm_flags & VM_ACCOUNT)
2391 nr_accounted += nrpages;
2392 vm_stat_account(mm, vma->vm_flags, -nrpages);
2393 vma = remove_vma(vma);
2395 vm_unacct_memory(nr_accounted);
2400 * Get rid of page table information in the indicated region.
2402 * Called with the mm semaphore held.
2404 static void unmap_region(struct mm_struct *mm,
2405 struct vm_area_struct *vma, struct vm_area_struct *prev,
2406 unsigned long start, unsigned long end)
2408 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2409 struct mmu_gather tlb;
2412 tlb_gather_mmu(&tlb, mm, start, end);
2413 update_hiwater_rss(mm);
2414 unmap_vmas(&tlb, vma, start, end);
2415 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2416 next ? next->vm_start : USER_PGTABLES_CEILING);
2417 tlb_finish_mmu(&tlb, start, end);
2421 * Create a list of vma's touched by the unmap, removing them from the mm's
2422 * vma list as we go..
2425 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2426 struct vm_area_struct *prev, unsigned long end)
2428 struct vm_area_struct **insertion_point;
2429 struct vm_area_struct *tail_vma = NULL;
2431 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2432 vma->vm_prev = NULL;
2434 vma_rb_erase(vma, &mm->mm_rb);
2438 } while (vma && vma->vm_start < end);
2439 *insertion_point = vma;
2441 vma->vm_prev = prev;
2442 vma_gap_update(vma);
2444 mm->highest_vm_end = prev ? prev->vm_end : 0;
2445 tail_vma->vm_next = NULL;
2447 /* Kill the cache */
2448 vmacache_invalidate(mm);
2452 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2453 * munmap path where it doesn't make sense to fail.
2455 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2456 unsigned long addr, int new_below)
2458 struct vm_area_struct *new;
2461 if (is_vm_hugetlb_page(vma) && (addr &
2462 ~(huge_page_mask(hstate_vma(vma)))))
2465 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2469 /* most fields are the same, copy all, and then fixup */
2472 INIT_LIST_HEAD(&new->anon_vma_chain);
2477 new->vm_start = addr;
2478 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2481 err = vma_dup_policy(vma, new);
2485 err = anon_vma_clone(new, vma);
2490 get_file(new->vm_file);
2492 if (new->vm_ops && new->vm_ops->open)
2493 new->vm_ops->open(new);
2496 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2497 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2499 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2505 /* Clean everything up if vma_adjust failed. */
2506 if (new->vm_ops && new->vm_ops->close)
2507 new->vm_ops->close(new);
2510 unlink_anon_vmas(new);
2512 mpol_put(vma_policy(new));
2514 kmem_cache_free(vm_area_cachep, new);
2519 * Split a vma into two pieces at address 'addr', a new vma is allocated
2520 * either for the first part or the tail.
2522 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2523 unsigned long addr, int new_below)
2525 if (mm->map_count >= sysctl_max_map_count)
2528 return __split_vma(mm, vma, addr, new_below);
2531 /* Munmap is split into 2 main parts -- this part which finds
2532 * what needs doing, and the areas themselves, which do the
2533 * work. This now handles partial unmappings.
2534 * Jeremy Fitzhardinge <jeremy@goop.org>
2536 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2539 struct vm_area_struct *vma, *prev, *last;
2541 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2544 len = PAGE_ALIGN(len);
2548 /* Find the first overlapping VMA */
2549 vma = find_vma(mm, start);
2552 prev = vma->vm_prev;
2553 /* we have start < vma->vm_end */
2555 /* if it doesn't overlap, we have nothing.. */
2557 if (vma->vm_start >= end)
2561 * If we need to split any vma, do it now to save pain later.
2563 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2564 * unmapped vm_area_struct will remain in use: so lower split_vma
2565 * places tmp vma above, and higher split_vma places tmp vma below.
2567 if (start > vma->vm_start) {
2571 * Make sure that map_count on return from munmap() will
2572 * not exceed its limit; but let map_count go just above
2573 * its limit temporarily, to help free resources as expected.
2575 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2578 error = __split_vma(mm, vma, start, 0);
2584 /* Does it split the last one? */
2585 last = find_vma(mm, end);
2586 if (last && end > last->vm_start) {
2587 int error = __split_vma(mm, last, end, 1);
2591 vma = prev ? prev->vm_next : mm->mmap;
2594 * unlock any mlock()ed ranges before detaching vmas
2596 if (mm->locked_vm) {
2597 struct vm_area_struct *tmp = vma;
2598 while (tmp && tmp->vm_start < end) {
2599 if (tmp->vm_flags & VM_LOCKED) {
2600 mm->locked_vm -= vma_pages(tmp);
2601 munlock_vma_pages_all(tmp);
2608 * Remove the vma's, and unmap the actual pages
2610 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2611 unmap_region(mm, vma, prev, start, end);
2613 arch_unmap(mm, vma, start, end);
2615 /* Fix up all other VM information */
2616 remove_vma_list(mm, vma);
2621 int vm_munmap(unsigned long start, size_t len)
2624 struct mm_struct *mm = current->mm;
2626 down_write(&mm->mmap_sem);
2627 ret = do_munmap(mm, start, len);
2628 up_write(&mm->mmap_sem);
2631 EXPORT_SYMBOL(vm_munmap);
2633 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2635 profile_munmap(addr);
2636 return vm_munmap(addr, len);
2641 * Emulation of deprecated remap_file_pages() syscall.
2643 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2644 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2647 struct mm_struct *mm = current->mm;
2648 struct vm_area_struct *vma;
2649 unsigned long populate = 0;
2650 unsigned long ret = -EINVAL;
2653 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
2654 "See Documentation/vm/remap_file_pages.txt.\n",
2655 current->comm, current->pid);
2659 start = start & PAGE_MASK;
2660 size = size & PAGE_MASK;
2662 if (start + size <= start)
2665 /* Does pgoff wrap? */
2666 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2669 down_write(&mm->mmap_sem);
2670 vma = find_vma(mm, start);
2672 if (!vma || !(vma->vm_flags & VM_SHARED))
2675 if (start < vma->vm_start || start + size > vma->vm_end)
2678 if (pgoff == linear_page_index(vma, start)) {
2683 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2684 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2685 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2687 flags &= MAP_NONBLOCK;
2688 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2689 if (vma->vm_flags & VM_LOCKED) {
2690 flags |= MAP_LOCKED;
2691 /* drop PG_Mlocked flag for over-mapped range */
2692 munlock_vma_pages_range(vma, start, start + size);
2695 file = get_file(vma->vm_file);
2696 ret = do_mmap_pgoff(vma->vm_file, start, size,
2697 prot, flags, pgoff, &populate);
2700 up_write(&mm->mmap_sem);
2702 mm_populate(ret, populate);
2703 if (!IS_ERR_VALUE(ret))
2708 static inline void verify_mm_writelocked(struct mm_struct *mm)
2710 #ifdef CONFIG_DEBUG_VM
2711 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2713 up_read(&mm->mmap_sem);
2719 * this is really a simplified "do_mmap". it only handles
2720 * anonymous maps. eventually we may be able to do some
2721 * brk-specific accounting here.
2723 static unsigned long do_brk(unsigned long addr, unsigned long len)
2725 struct mm_struct *mm = current->mm;
2726 struct vm_area_struct *vma, *prev;
2727 unsigned long flags;
2728 struct rb_node **rb_link, *rb_parent;
2729 pgoff_t pgoff = addr >> PAGE_SHIFT;
2732 len = PAGE_ALIGN(len);
2736 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2738 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2739 if (offset_in_page(error))
2742 error = mlock_future_check(mm, mm->def_flags, len);
2747 * mm->mmap_sem is required to protect against another thread
2748 * changing the mappings in case we sleep.
2750 verify_mm_writelocked(mm);
2753 * Clear old maps. this also does some error checking for us
2755 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2757 if (do_munmap(mm, addr, len))
2761 /* Check against address space limits *after* clearing old maps... */
2762 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2765 if (mm->map_count > sysctl_max_map_count)
2768 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2771 /* Can we just expand an old private anonymous mapping? */
2772 vma = vma_merge(mm, prev, addr, addr + len, flags,
2773 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2778 * create a vma struct for an anonymous mapping
2780 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2782 vm_unacct_memory(len >> PAGE_SHIFT);
2786 INIT_LIST_HEAD(&vma->anon_vma_chain);
2788 vma->vm_start = addr;
2789 vma->vm_end = addr + len;
2790 vma->vm_pgoff = pgoff;
2791 vma->vm_flags = flags;
2792 vma->vm_page_prot = vm_get_page_prot(flags);
2793 vma_link(mm, vma, prev, rb_link, rb_parent);
2795 perf_event_mmap(vma);
2796 mm->total_vm += len >> PAGE_SHIFT;
2797 mm->data_vm += len >> PAGE_SHIFT;
2798 if (flags & VM_LOCKED)
2799 mm->locked_vm += (len >> PAGE_SHIFT);
2800 vma->vm_flags |= VM_SOFTDIRTY;
2804 unsigned long vm_brk(unsigned long addr, unsigned long len)
2806 struct mm_struct *mm = current->mm;
2810 down_write(&mm->mmap_sem);
2811 ret = do_brk(addr, len);
2812 populate = ((mm->def_flags & VM_LOCKED) != 0);
2813 up_write(&mm->mmap_sem);
2815 mm_populate(addr, len);
2818 EXPORT_SYMBOL(vm_brk);
2820 /* Release all mmaps. */
2821 void exit_mmap(struct mm_struct *mm)
2823 struct mmu_gather tlb;
2824 struct vm_area_struct *vma;
2825 unsigned long nr_accounted = 0;
2827 /* mm's last user has gone, and its about to be pulled down */
2828 mmu_notifier_release(mm);
2830 if (mm->locked_vm) {
2833 if (vma->vm_flags & VM_LOCKED)
2834 munlock_vma_pages_all(vma);
2842 if (!vma) /* Can happen if dup_mmap() received an OOM */
2847 tlb_gather_mmu(&tlb, mm, 0, -1);
2848 /* update_hiwater_rss(mm) here? but nobody should be looking */
2849 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2850 unmap_vmas(&tlb, vma, 0, -1);
2852 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2853 tlb_finish_mmu(&tlb, 0, -1);
2856 * Walk the list again, actually closing and freeing it,
2857 * with preemption enabled, without holding any MM locks.
2860 if (vma->vm_flags & VM_ACCOUNT)
2861 nr_accounted += vma_pages(vma);
2862 vma = remove_vma(vma);
2864 vm_unacct_memory(nr_accounted);
2867 /* Insert vm structure into process list sorted by address
2868 * and into the inode's i_mmap tree. If vm_file is non-NULL
2869 * then i_mmap_rwsem is taken here.
2871 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2873 struct vm_area_struct *prev;
2874 struct rb_node **rb_link, *rb_parent;
2876 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2877 &prev, &rb_link, &rb_parent))
2879 if ((vma->vm_flags & VM_ACCOUNT) &&
2880 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2884 * The vm_pgoff of a purely anonymous vma should be irrelevant
2885 * until its first write fault, when page's anon_vma and index
2886 * are set. But now set the vm_pgoff it will almost certainly
2887 * end up with (unless mremap moves it elsewhere before that
2888 * first wfault), so /proc/pid/maps tells a consistent story.
2890 * By setting it to reflect the virtual start address of the
2891 * vma, merges and splits can happen in a seamless way, just
2892 * using the existing file pgoff checks and manipulations.
2893 * Similarly in do_mmap_pgoff and in do_brk.
2895 if (vma_is_anonymous(vma)) {
2896 BUG_ON(vma->anon_vma);
2897 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2900 vma_link(mm, vma, prev, rb_link, rb_parent);
2905 * Copy the vma structure to a new location in the same mm,
2906 * prior to moving page table entries, to effect an mremap move.
2908 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2909 unsigned long addr, unsigned long len, pgoff_t pgoff,
2910 bool *need_rmap_locks)
2912 struct vm_area_struct *vma = *vmap;
2913 unsigned long vma_start = vma->vm_start;
2914 struct mm_struct *mm = vma->vm_mm;
2915 struct vm_area_struct *new_vma, *prev;
2916 struct rb_node **rb_link, *rb_parent;
2917 bool faulted_in_anon_vma = true;
2920 * If anonymous vma has not yet been faulted, update new pgoff
2921 * to match new location, to increase its chance of merging.
2923 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
2924 pgoff = addr >> PAGE_SHIFT;
2925 faulted_in_anon_vma = false;
2928 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2929 return NULL; /* should never get here */
2930 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2931 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
2932 vma->vm_userfaultfd_ctx);
2935 * Source vma may have been merged into new_vma
2937 if (unlikely(vma_start >= new_vma->vm_start &&
2938 vma_start < new_vma->vm_end)) {
2940 * The only way we can get a vma_merge with
2941 * self during an mremap is if the vma hasn't
2942 * been faulted in yet and we were allowed to
2943 * reset the dst vma->vm_pgoff to the
2944 * destination address of the mremap to allow
2945 * the merge to happen. mremap must change the
2946 * vm_pgoff linearity between src and dst vmas
2947 * (in turn preventing a vma_merge) to be
2948 * safe. It is only safe to keep the vm_pgoff
2949 * linear if there are no pages mapped yet.
2951 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2952 *vmap = vma = new_vma;
2954 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2956 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2960 new_vma->vm_start = addr;
2961 new_vma->vm_end = addr + len;
2962 new_vma->vm_pgoff = pgoff;
2963 if (vma_dup_policy(vma, new_vma))
2965 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2966 if (anon_vma_clone(new_vma, vma))
2967 goto out_free_mempol;
2968 if (new_vma->vm_file)
2969 get_file(new_vma->vm_file);
2970 if (new_vma->vm_ops && new_vma->vm_ops->open)
2971 new_vma->vm_ops->open(new_vma);
2972 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2973 *need_rmap_locks = false;
2978 mpol_put(vma_policy(new_vma));
2980 kmem_cache_free(vm_area_cachep, new_vma);
2986 * Return true if the calling process may expand its vm space by the passed
2989 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
2991 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
2994 if (is_data_mapping(flags) &&
2995 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
2996 if (ignore_rlimit_data)
2997 pr_warn_once("%s (%d): VmData %lu exceed data ulimit "
2998 "%lu. Will be forbidden soon.\n",
2999 current->comm, current->pid,
3000 (mm->data_vm + npages) << PAGE_SHIFT,
3001 rlimit(RLIMIT_DATA));
3009 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3011 mm->total_vm += npages;
3013 if (is_exec_mapping(flags))
3014 mm->exec_vm += npages;
3015 else if (is_stack_mapping(flags))
3016 mm->stack_vm += npages;
3017 else if (is_data_mapping(flags))
3018 mm->data_vm += npages;
3021 static int special_mapping_fault(struct vm_area_struct *vma,
3022 struct vm_fault *vmf);
3025 * Having a close hook prevents vma merging regardless of flags.
3027 static void special_mapping_close(struct vm_area_struct *vma)
3031 static const char *special_mapping_name(struct vm_area_struct *vma)
3033 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3036 static const struct vm_operations_struct special_mapping_vmops = {
3037 .close = special_mapping_close,
3038 .fault = special_mapping_fault,
3039 .name = special_mapping_name,
3042 static const struct vm_operations_struct legacy_special_mapping_vmops = {
3043 .close = special_mapping_close,
3044 .fault = special_mapping_fault,
3047 static int special_mapping_fault(struct vm_area_struct *vma,
3048 struct vm_fault *vmf)
3051 struct page **pages;
3053 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3054 pages = vma->vm_private_data;
3056 struct vm_special_mapping *sm = vma->vm_private_data;
3059 return sm->fault(sm, vma, vmf);
3064 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3068 struct page *page = *pages;
3074 return VM_FAULT_SIGBUS;
3077 static struct vm_area_struct *__install_special_mapping(
3078 struct mm_struct *mm,
3079 unsigned long addr, unsigned long len,
3080 unsigned long vm_flags, void *priv,
3081 const struct vm_operations_struct *ops)
3084 struct vm_area_struct *vma;
3086 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3087 if (unlikely(vma == NULL))
3088 return ERR_PTR(-ENOMEM);
3090 INIT_LIST_HEAD(&vma->anon_vma_chain);
3092 vma->vm_start = addr;
3093 vma->vm_end = addr + len;
3095 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3096 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3099 vma->vm_private_data = priv;
3101 ret = insert_vm_struct(mm, vma);
3105 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3107 perf_event_mmap(vma);
3112 kmem_cache_free(vm_area_cachep, vma);
3113 return ERR_PTR(ret);
3117 * Called with mm->mmap_sem held for writing.
3118 * Insert a new vma covering the given region, with the given flags.
3119 * Its pages are supplied by the given array of struct page *.
3120 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3121 * The region past the last page supplied will always produce SIGBUS.
3122 * The array pointer and the pages it points to are assumed to stay alive
3123 * for as long as this mapping might exist.
3125 struct vm_area_struct *_install_special_mapping(
3126 struct mm_struct *mm,
3127 unsigned long addr, unsigned long len,
3128 unsigned long vm_flags, const struct vm_special_mapping *spec)
3130 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3131 &special_mapping_vmops);
3134 int install_special_mapping(struct mm_struct *mm,
3135 unsigned long addr, unsigned long len,
3136 unsigned long vm_flags, struct page **pages)
3138 struct vm_area_struct *vma = __install_special_mapping(
3139 mm, addr, len, vm_flags, (void *)pages,
3140 &legacy_special_mapping_vmops);
3142 return PTR_ERR_OR_ZERO(vma);
3145 static DEFINE_MUTEX(mm_all_locks_mutex);
3147 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3149 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3151 * The LSB of head.next can't change from under us
3152 * because we hold the mm_all_locks_mutex.
3154 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3156 * We can safely modify head.next after taking the
3157 * anon_vma->root->rwsem. If some other vma in this mm shares
3158 * the same anon_vma we won't take it again.
3160 * No need of atomic instructions here, head.next
3161 * can't change from under us thanks to the
3162 * anon_vma->root->rwsem.
3164 if (__test_and_set_bit(0, (unsigned long *)
3165 &anon_vma->root->rb_root.rb_node))
3170 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3172 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3174 * AS_MM_ALL_LOCKS can't change from under us because
3175 * we hold the mm_all_locks_mutex.
3177 * Operations on ->flags have to be atomic because
3178 * even if AS_MM_ALL_LOCKS is stable thanks to the
3179 * mm_all_locks_mutex, there may be other cpus
3180 * changing other bitflags in parallel to us.
3182 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3184 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3189 * This operation locks against the VM for all pte/vma/mm related
3190 * operations that could ever happen on a certain mm. This includes
3191 * vmtruncate, try_to_unmap, and all page faults.
3193 * The caller must take the mmap_sem in write mode before calling
3194 * mm_take_all_locks(). The caller isn't allowed to release the
3195 * mmap_sem until mm_drop_all_locks() returns.
3197 * mmap_sem in write mode is required in order to block all operations
3198 * that could modify pagetables and free pages without need of
3199 * altering the vma layout. It's also needed in write mode to avoid new
3200 * anon_vmas to be associated with existing vmas.
3202 * A single task can't take more than one mm_take_all_locks() in a row
3203 * or it would deadlock.
3205 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3206 * mapping->flags avoid to take the same lock twice, if more than one
3207 * vma in this mm is backed by the same anon_vma or address_space.
3209 * We take locks in following order, accordingly to comment at beginning
3211 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3213 * - all i_mmap_rwsem locks;
3214 * - all anon_vma->rwseml
3216 * We can take all locks within these types randomly because the VM code
3217 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3218 * mm_all_locks_mutex.
3220 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3221 * that may have to take thousand of locks.
3223 * mm_take_all_locks() can fail if it's interrupted by signals.
3225 int mm_take_all_locks(struct mm_struct *mm)
3227 struct vm_area_struct *vma;
3228 struct anon_vma_chain *avc;
3230 BUG_ON(down_read_trylock(&mm->mmap_sem));
3232 mutex_lock(&mm_all_locks_mutex);
3234 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3235 if (signal_pending(current))
3237 if (vma->vm_file && vma->vm_file->f_mapping &&
3238 is_vm_hugetlb_page(vma))
3239 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3242 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3243 if (signal_pending(current))
3245 if (vma->vm_file && vma->vm_file->f_mapping &&
3246 !is_vm_hugetlb_page(vma))
3247 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3250 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3251 if (signal_pending(current))
3254 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3255 vm_lock_anon_vma(mm, avc->anon_vma);
3261 mm_drop_all_locks(mm);
3265 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3267 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3269 * The LSB of head.next can't change to 0 from under
3270 * us because we hold the mm_all_locks_mutex.
3272 * We must however clear the bitflag before unlocking
3273 * the vma so the users using the anon_vma->rb_root will
3274 * never see our bitflag.
3276 * No need of atomic instructions here, head.next
3277 * can't change from under us until we release the
3278 * anon_vma->root->rwsem.
3280 if (!__test_and_clear_bit(0, (unsigned long *)
3281 &anon_vma->root->rb_root.rb_node))
3283 anon_vma_unlock_write(anon_vma);
3287 static void vm_unlock_mapping(struct address_space *mapping)
3289 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3291 * AS_MM_ALL_LOCKS can't change to 0 from under us
3292 * because we hold the mm_all_locks_mutex.
3294 i_mmap_unlock_write(mapping);
3295 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3302 * The mmap_sem cannot be released by the caller until
3303 * mm_drop_all_locks() returns.
3305 void mm_drop_all_locks(struct mm_struct *mm)
3307 struct vm_area_struct *vma;
3308 struct anon_vma_chain *avc;
3310 BUG_ON(down_read_trylock(&mm->mmap_sem));
3311 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3313 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3315 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3316 vm_unlock_anon_vma(avc->anon_vma);
3317 if (vma->vm_file && vma->vm_file->f_mapping)
3318 vm_unlock_mapping(vma->vm_file->f_mapping);
3321 mutex_unlock(&mm_all_locks_mutex);
3325 * initialise the VMA slab
3327 void __init mmap_init(void)
3331 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3336 * Initialise sysctl_user_reserve_kbytes.
3338 * This is intended to prevent a user from starting a single memory hogging
3339 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3342 * The default value is min(3% of free memory, 128MB)
3343 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3345 static int init_user_reserve(void)
3347 unsigned long free_kbytes;
3349 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3351 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3354 subsys_initcall(init_user_reserve);
3357 * Initialise sysctl_admin_reserve_kbytes.
3359 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3360 * to log in and kill a memory hogging process.
3362 * Systems with more than 256MB will reserve 8MB, enough to recover
3363 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3364 * only reserve 3% of free pages by default.
3366 static int init_admin_reserve(void)
3368 unsigned long free_kbytes;
3370 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3372 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3375 subsys_initcall(init_admin_reserve);
3378 * Reinititalise user and admin reserves if memory is added or removed.
3380 * The default user reserve max is 128MB, and the default max for the
3381 * admin reserve is 8MB. These are usually, but not always, enough to
3382 * enable recovery from a memory hogging process using login/sshd, a shell,
3383 * and tools like top. It may make sense to increase or even disable the
3384 * reserve depending on the existence of swap or variations in the recovery
3385 * tools. So, the admin may have changed them.
3387 * If memory is added and the reserves have been eliminated or increased above
3388 * the default max, then we'll trust the admin.
3390 * If memory is removed and there isn't enough free memory, then we
3391 * need to reset the reserves.
3393 * Otherwise keep the reserve set by the admin.
3395 static int reserve_mem_notifier(struct notifier_block *nb,
3396 unsigned long action, void *data)
3398 unsigned long tmp, free_kbytes;
3402 /* Default max is 128MB. Leave alone if modified by operator. */
3403 tmp = sysctl_user_reserve_kbytes;
3404 if (0 < tmp && tmp < (1UL << 17))
3405 init_user_reserve();
3407 /* Default max is 8MB. Leave alone if modified by operator. */
3408 tmp = sysctl_admin_reserve_kbytes;
3409 if (0 < tmp && tmp < (1UL << 13))
3410 init_admin_reserve();
3414 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3416 if (sysctl_user_reserve_kbytes > free_kbytes) {
3417 init_user_reserve();
3418 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3419 sysctl_user_reserve_kbytes);
3422 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3423 init_admin_reserve();
3424 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3425 sysctl_admin_reserve_kbytes);
3434 static struct notifier_block reserve_mem_nb = {
3435 .notifier_call = reserve_mem_notifier,
3438 static int __meminit init_reserve_notifier(void)
3440 if (register_hotmemory_notifier(&reserve_mem_nb))
3441 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3445 subsys_initcall(init_reserve_notifier);