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>
47 #include <asm/uaccess.h>
48 #include <asm/cacheflush.h>
50 #include <asm/mmu_context.h>
54 #ifndef arch_mmap_check
55 #define arch_mmap_check(addr, len, flags) (0)
58 #ifndef arch_rebalance_pgtables
59 #define arch_rebalance_pgtables(addr, len) (addr)
62 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
63 const int mmap_rnd_bits_min
= CONFIG_ARCH_MMAP_RND_BITS_MIN
;
64 const int mmap_rnd_bits_max
= CONFIG_ARCH_MMAP_RND_BITS_MAX
;
65 int mmap_rnd_bits __read_mostly
= CONFIG_ARCH_MMAP_RND_BITS
;
67 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
68 const int mmap_rnd_compat_bits_min
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN
;
69 const int mmap_rnd_compat_bits_max
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX
;
70 int mmap_rnd_compat_bits __read_mostly
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS
;
73 static bool ignore_rlimit_data
= true;
74 core_param(ignore_rlimit_data
, ignore_rlimit_data
, bool, 0644);
76 static void unmap_region(struct mm_struct
*mm
,
77 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
78 unsigned long start
, unsigned long end
);
80 /* description of effects of mapping type and prot in current implementation.
81 * this is due to the limited x86 page protection hardware. The expected
82 * behavior is in parens:
85 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
86 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
87 * w: (no) no w: (no) no w: (yes) yes w: (no) no
88 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
90 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
91 * w: (no) no w: (no) no w: (copy) copy w: (no) no
92 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
95 pgprot_t protection_map
[16] = {
96 __P000
, __P001
, __P010
, __P011
, __P100
, __P101
, __P110
, __P111
,
97 __S000
, __S001
, __S010
, __S011
, __S100
, __S101
, __S110
, __S111
100 pgprot_t
vm_get_page_prot(unsigned long vm_flags
)
102 return __pgprot(pgprot_val(protection_map
[vm_flags
&
103 (VM_READ
|VM_WRITE
|VM_EXEC
|VM_SHARED
)]) |
104 pgprot_val(arch_vm_get_page_prot(vm_flags
)));
106 EXPORT_SYMBOL(vm_get_page_prot
);
108 static pgprot_t
vm_pgprot_modify(pgprot_t oldprot
, unsigned long vm_flags
)
110 return pgprot_modify(oldprot
, vm_get_page_prot(vm_flags
));
113 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
114 void vma_set_page_prot(struct vm_area_struct
*vma
)
116 unsigned long vm_flags
= vma
->vm_flags
;
118 vma
->vm_page_prot
= vm_pgprot_modify(vma
->vm_page_prot
, vm_flags
);
119 if (vma_wants_writenotify(vma
)) {
120 vm_flags
&= ~VM_SHARED
;
121 vma
->vm_page_prot
= vm_pgprot_modify(vma
->vm_page_prot
,
127 int sysctl_overcommit_memory __read_mostly
= OVERCOMMIT_GUESS
; /* heuristic overcommit */
128 int sysctl_overcommit_ratio __read_mostly
= 50; /* default is 50% */
129 unsigned long sysctl_overcommit_kbytes __read_mostly
;
130 int sysctl_max_map_count __read_mostly
= DEFAULT_MAX_MAP_COUNT
;
131 unsigned long sysctl_user_reserve_kbytes __read_mostly
= 1UL << 17; /* 128MB */
132 unsigned long sysctl_admin_reserve_kbytes __read_mostly
= 1UL << 13; /* 8MB */
134 * Make sure vm_committed_as in one cacheline and not cacheline shared with
135 * other variables. It can be updated by several CPUs frequently.
137 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp
;
140 * The global memory commitment made in the system can be a metric
141 * that can be used to drive ballooning decisions when Linux is hosted
142 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
143 * balancing memory across competing virtual machines that are hosted.
144 * Several metrics drive this policy engine including the guest reported
147 unsigned long vm_memory_committed(void)
149 return percpu_counter_read_positive(&vm_committed_as
);
151 EXPORT_SYMBOL_GPL(vm_memory_committed
);
154 * Check that a process has enough memory to allocate a new virtual
155 * mapping. 0 means there is enough memory for the allocation to
156 * succeed and -ENOMEM implies there is not.
158 * We currently support three overcommit policies, which are set via the
159 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
161 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
162 * Additional code 2002 Jul 20 by Robert Love.
164 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
166 * Note this is a helper function intended to be used by LSMs which
167 * wish to use this logic.
169 int __vm_enough_memory(struct mm_struct
*mm
, long pages
, int cap_sys_admin
)
171 long free
, allowed
, reserve
;
173 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as
) <
174 -(s64
)vm_committed_as_batch
* num_online_cpus(),
175 "memory commitment underflow");
177 vm_acct_memory(pages
);
180 * Sometimes we want to use more memory than we have
182 if (sysctl_overcommit_memory
== OVERCOMMIT_ALWAYS
)
185 if (sysctl_overcommit_memory
== OVERCOMMIT_GUESS
) {
186 free
= global_page_state(NR_FREE_PAGES
);
187 free
+= global_page_state(NR_FILE_PAGES
);
190 * shmem pages shouldn't be counted as free in this
191 * case, they can't be purged, only swapped out, and
192 * that won't affect the overall amount of available
193 * memory in the system.
195 free
-= global_page_state(NR_SHMEM
);
197 free
+= get_nr_swap_pages();
200 * Any slabs which are created with the
201 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
202 * which are reclaimable, under pressure. The dentry
203 * cache and most inode caches should fall into this
205 free
+= global_page_state(NR_SLAB_RECLAIMABLE
);
208 * Leave reserved pages. The pages are not for anonymous pages.
210 if (free
<= totalreserve_pages
)
213 free
-= totalreserve_pages
;
216 * Reserve some for root
219 free
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
227 allowed
= vm_commit_limit();
229 * Reserve some for root
232 allowed
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
235 * Don't let a single process grow so big a user can't recover
238 reserve
= sysctl_user_reserve_kbytes
>> (PAGE_SHIFT
- 10);
239 allowed
-= min_t(long, mm
->total_vm
/ 32, reserve
);
242 if (percpu_counter_read_positive(&vm_committed_as
) < allowed
)
245 vm_unacct_memory(pages
);
251 * Requires inode->i_mapping->i_mmap_rwsem
253 static void __remove_shared_vm_struct(struct vm_area_struct
*vma
,
254 struct file
*file
, struct address_space
*mapping
)
256 if (vma
->vm_flags
& VM_DENYWRITE
)
257 atomic_inc(&file_inode(file
)->i_writecount
);
258 if (vma
->vm_flags
& VM_SHARED
)
259 mapping_unmap_writable(mapping
);
261 flush_dcache_mmap_lock(mapping
);
262 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
263 flush_dcache_mmap_unlock(mapping
);
267 * Unlink a file-based vm structure from its interval tree, to hide
268 * vma from rmap and vmtruncate before freeing its page tables.
270 void unlink_file_vma(struct vm_area_struct
*vma
)
272 struct file
*file
= vma
->vm_file
;
275 struct address_space
*mapping
= file
->f_mapping
;
276 i_mmap_lock_write(mapping
);
277 __remove_shared_vm_struct(vma
, file
, mapping
);
278 i_mmap_unlock_write(mapping
);
283 * Close a vm structure and free it, returning the next.
285 static struct vm_area_struct
*remove_vma(struct vm_area_struct
*vma
)
287 struct vm_area_struct
*next
= vma
->vm_next
;
290 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
291 vma
->vm_ops
->close(vma
);
294 mpol_put(vma_policy(vma
));
295 kmem_cache_free(vm_area_cachep
, vma
);
299 static unsigned long do_brk(unsigned long addr
, unsigned long len
);
301 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
303 unsigned long retval
;
304 unsigned long newbrk
, oldbrk
;
305 struct mm_struct
*mm
= current
->mm
;
306 unsigned long min_brk
;
309 down_write(&mm
->mmap_sem
);
311 #ifdef CONFIG_COMPAT_BRK
313 * CONFIG_COMPAT_BRK can still be overridden by setting
314 * randomize_va_space to 2, which will still cause mm->start_brk
315 * to be arbitrarily shifted
317 if (current
->brk_randomized
)
318 min_brk
= mm
->start_brk
;
320 min_brk
= mm
->end_data
;
322 min_brk
= mm
->start_brk
;
328 * Check against rlimit here. If this check is done later after the test
329 * of oldbrk with newbrk then it can escape the test and let the data
330 * segment grow beyond its set limit the in case where the limit is
331 * not page aligned -Ram Gupta
333 if (check_data_rlimit(rlimit(RLIMIT_DATA
), brk
, mm
->start_brk
,
334 mm
->end_data
, mm
->start_data
))
337 newbrk
= PAGE_ALIGN(brk
);
338 oldbrk
= PAGE_ALIGN(mm
->brk
);
339 if (oldbrk
== newbrk
)
342 /* Always allow shrinking brk. */
343 if (brk
<= mm
->brk
) {
344 if (!do_munmap(mm
, newbrk
, oldbrk
-newbrk
))
349 /* Check against existing mmap mappings. */
350 if (find_vma_intersection(mm
, oldbrk
, newbrk
+PAGE_SIZE
))
353 /* Ok, looks good - let it rip. */
354 if (do_brk(oldbrk
, newbrk
-oldbrk
) != oldbrk
)
359 populate
= newbrk
> oldbrk
&& (mm
->def_flags
& VM_LOCKED
) != 0;
360 up_write(&mm
->mmap_sem
);
362 mm_populate(oldbrk
, newbrk
- oldbrk
);
367 up_write(&mm
->mmap_sem
);
371 static long vma_compute_subtree_gap(struct vm_area_struct
*vma
)
373 unsigned long max
, subtree_gap
;
376 max
-= vma
->vm_prev
->vm_end
;
377 if (vma
->vm_rb
.rb_left
) {
378 subtree_gap
= rb_entry(vma
->vm_rb
.rb_left
,
379 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
380 if (subtree_gap
> max
)
383 if (vma
->vm_rb
.rb_right
) {
384 subtree_gap
= rb_entry(vma
->vm_rb
.rb_right
,
385 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
386 if (subtree_gap
> max
)
392 #ifdef CONFIG_DEBUG_VM_RB
393 static int browse_rb(struct rb_root
*root
)
395 int i
= 0, j
, bug
= 0;
396 struct rb_node
*nd
, *pn
= NULL
;
397 unsigned long prev
= 0, pend
= 0;
399 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
400 struct vm_area_struct
*vma
;
401 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
402 if (vma
->vm_start
< prev
) {
403 pr_emerg("vm_start %lx < prev %lx\n",
404 vma
->vm_start
, prev
);
407 if (vma
->vm_start
< pend
) {
408 pr_emerg("vm_start %lx < pend %lx\n",
409 vma
->vm_start
, pend
);
412 if (vma
->vm_start
> vma
->vm_end
) {
413 pr_emerg("vm_start %lx > vm_end %lx\n",
414 vma
->vm_start
, vma
->vm_end
);
417 if (vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
)) {
418 pr_emerg("free gap %lx, correct %lx\n",
420 vma_compute_subtree_gap(vma
));
425 prev
= vma
->vm_start
;
429 for (nd
= pn
; nd
; nd
= rb_prev(nd
))
432 pr_emerg("backwards %d, forwards %d\n", j
, i
);
438 static void validate_mm_rb(struct rb_root
*root
, struct vm_area_struct
*ignore
)
442 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
443 struct vm_area_struct
*vma
;
444 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
445 VM_BUG_ON_VMA(vma
!= ignore
&&
446 vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
),
451 static void validate_mm(struct mm_struct
*mm
)
455 unsigned long highest_address
= 0;
456 struct vm_area_struct
*vma
= mm
->mmap
;
459 struct anon_vma_chain
*avc
;
461 vma_lock_anon_vma(vma
);
462 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
463 anon_vma_interval_tree_verify(avc
);
464 vma_unlock_anon_vma(vma
);
465 highest_address
= vma
->vm_end
;
469 if (i
!= mm
->map_count
) {
470 pr_emerg("map_count %d vm_next %d\n", mm
->map_count
, i
);
473 if (highest_address
!= mm
->highest_vm_end
) {
474 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
475 mm
->highest_vm_end
, highest_address
);
478 i
= browse_rb(&mm
->mm_rb
);
479 if (i
!= mm
->map_count
) {
481 pr_emerg("map_count %d rb %d\n", mm
->map_count
, i
);
484 VM_BUG_ON_MM(bug
, mm
);
487 #define validate_mm_rb(root, ignore) do { } while (0)
488 #define validate_mm(mm) do { } while (0)
491 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks
, struct vm_area_struct
, vm_rb
,
492 unsigned long, rb_subtree_gap
, vma_compute_subtree_gap
)
495 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
496 * vma->vm_prev->vm_end values changed, without modifying the vma's position
499 static void vma_gap_update(struct vm_area_struct
*vma
)
502 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
503 * function that does exacltly what we want.
505 vma_gap_callbacks_propagate(&vma
->vm_rb
, NULL
);
508 static inline void vma_rb_insert(struct vm_area_struct
*vma
,
509 struct rb_root
*root
)
511 /* All rb_subtree_gap values must be consistent prior to insertion */
512 validate_mm_rb(root
, NULL
);
514 rb_insert_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
517 static void vma_rb_erase(struct vm_area_struct
*vma
, struct rb_root
*root
)
520 * All rb_subtree_gap values must be consistent prior to erase,
521 * with the possible exception of the vma being erased.
523 validate_mm_rb(root
, vma
);
526 * Note rb_erase_augmented is a fairly large inline function,
527 * so make sure we instantiate it only once with our desired
528 * augmented rbtree callbacks.
530 rb_erase_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
534 * vma has some anon_vma assigned, and is already inserted on that
535 * anon_vma's interval trees.
537 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
538 * vma must be removed from the anon_vma's interval trees using
539 * anon_vma_interval_tree_pre_update_vma().
541 * After the update, the vma will be reinserted using
542 * anon_vma_interval_tree_post_update_vma().
544 * The entire update must be protected by exclusive mmap_sem and by
545 * the root anon_vma's mutex.
548 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct
*vma
)
550 struct anon_vma_chain
*avc
;
552 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
553 anon_vma_interval_tree_remove(avc
, &avc
->anon_vma
->rb_root
);
557 anon_vma_interval_tree_post_update_vma(struct vm_area_struct
*vma
)
559 struct anon_vma_chain
*avc
;
561 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
562 anon_vma_interval_tree_insert(avc
, &avc
->anon_vma
->rb_root
);
565 static int find_vma_links(struct mm_struct
*mm
, unsigned long addr
,
566 unsigned long end
, struct vm_area_struct
**pprev
,
567 struct rb_node
***rb_link
, struct rb_node
**rb_parent
)
569 struct rb_node
**__rb_link
, *__rb_parent
, *rb_prev
;
571 __rb_link
= &mm
->mm_rb
.rb_node
;
572 rb_prev
= __rb_parent
= NULL
;
575 struct vm_area_struct
*vma_tmp
;
577 __rb_parent
= *__rb_link
;
578 vma_tmp
= rb_entry(__rb_parent
, struct vm_area_struct
, vm_rb
);
580 if (vma_tmp
->vm_end
> addr
) {
581 /* Fail if an existing vma overlaps the area */
582 if (vma_tmp
->vm_start
< end
)
584 __rb_link
= &__rb_parent
->rb_left
;
586 rb_prev
= __rb_parent
;
587 __rb_link
= &__rb_parent
->rb_right
;
593 *pprev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
594 *rb_link
= __rb_link
;
595 *rb_parent
= __rb_parent
;
599 static unsigned long count_vma_pages_range(struct mm_struct
*mm
,
600 unsigned long addr
, unsigned long end
)
602 unsigned long nr_pages
= 0;
603 struct vm_area_struct
*vma
;
605 /* Find first overlaping mapping */
606 vma
= find_vma_intersection(mm
, addr
, end
);
610 nr_pages
= (min(end
, vma
->vm_end
) -
611 max(addr
, vma
->vm_start
)) >> PAGE_SHIFT
;
613 /* Iterate over the rest of the overlaps */
614 for (vma
= vma
->vm_next
; vma
; vma
= vma
->vm_next
) {
615 unsigned long overlap_len
;
617 if (vma
->vm_start
> end
)
620 overlap_len
= min(end
, vma
->vm_end
) - vma
->vm_start
;
621 nr_pages
+= overlap_len
>> PAGE_SHIFT
;
627 void __vma_link_rb(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
628 struct rb_node
**rb_link
, struct rb_node
*rb_parent
)
630 /* Update tracking information for the gap following the new vma. */
632 vma_gap_update(vma
->vm_next
);
634 mm
->highest_vm_end
= vma
->vm_end
;
637 * vma->vm_prev wasn't known when we followed the rbtree to find the
638 * correct insertion point for that vma. As a result, we could not
639 * update the vma vm_rb parents rb_subtree_gap values on the way down.
640 * So, we first insert the vma with a zero rb_subtree_gap value
641 * (to be consistent with what we did on the way down), and then
642 * immediately update the gap to the correct value. Finally we
643 * rebalance the rbtree after all augmented values have been set.
645 rb_link_node(&vma
->vm_rb
, rb_parent
, rb_link
);
646 vma
->rb_subtree_gap
= 0;
648 vma_rb_insert(vma
, &mm
->mm_rb
);
651 static void __vma_link_file(struct vm_area_struct
*vma
)
657 struct address_space
*mapping
= file
->f_mapping
;
659 if (vma
->vm_flags
& VM_DENYWRITE
)
660 atomic_dec(&file_inode(file
)->i_writecount
);
661 if (vma
->vm_flags
& VM_SHARED
)
662 atomic_inc(&mapping
->i_mmap_writable
);
664 flush_dcache_mmap_lock(mapping
);
665 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
666 flush_dcache_mmap_unlock(mapping
);
671 __vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
672 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
673 struct rb_node
*rb_parent
)
675 __vma_link_list(mm
, vma
, prev
, rb_parent
);
676 __vma_link_rb(mm
, vma
, rb_link
, rb_parent
);
679 static void 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 struct address_space
*mapping
= NULL
;
686 mapping
= vma
->vm_file
->f_mapping
;
687 i_mmap_lock_write(mapping
);
690 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
691 __vma_link_file(vma
);
694 i_mmap_unlock_write(mapping
);
701 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
702 * mm's list and rbtree. It has already been inserted into the interval tree.
704 static void __insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
706 struct vm_area_struct
*prev
;
707 struct rb_node
**rb_link
, *rb_parent
;
709 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
710 &prev
, &rb_link
, &rb_parent
))
712 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
717 __vma_unlink(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
718 struct vm_area_struct
*prev
)
720 struct vm_area_struct
*next
;
722 vma_rb_erase(vma
, &mm
->mm_rb
);
723 prev
->vm_next
= next
= vma
->vm_next
;
725 next
->vm_prev
= prev
;
728 vmacache_invalidate(mm
);
732 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
733 * is already present in an i_mmap tree without adjusting the tree.
734 * The following helper function should be used when such adjustments
735 * are necessary. The "insert" vma (if any) is to be inserted
736 * before we drop the necessary locks.
738 int vma_adjust(struct vm_area_struct
*vma
, unsigned long start
,
739 unsigned long end
, pgoff_t pgoff
, struct vm_area_struct
*insert
)
741 struct mm_struct
*mm
= vma
->vm_mm
;
742 struct vm_area_struct
*next
= vma
->vm_next
;
743 struct vm_area_struct
*importer
= NULL
;
744 struct address_space
*mapping
= NULL
;
745 struct rb_root
*root
= NULL
;
746 struct anon_vma
*anon_vma
= NULL
;
747 struct file
*file
= vma
->vm_file
;
748 bool start_changed
= false, end_changed
= false;
749 long adjust_next
= 0;
752 if (next
&& !insert
) {
753 struct vm_area_struct
*exporter
= NULL
;
755 if (end
>= next
->vm_end
) {
757 * vma expands, overlapping all the next, and
758 * perhaps the one after too (mprotect case 6).
760 again
: remove_next
= 1 + (end
> next
->vm_end
);
764 } else if (end
> next
->vm_start
) {
766 * vma expands, overlapping part of the next:
767 * mprotect case 5 shifting the boundary up.
769 adjust_next
= (end
- next
->vm_start
) >> PAGE_SHIFT
;
772 } else if (end
< vma
->vm_end
) {
774 * vma shrinks, and !insert tells it's not
775 * split_vma inserting another: so it must be
776 * mprotect case 4 shifting the boundary down.
778 adjust_next
= -((vma
->vm_end
- end
) >> PAGE_SHIFT
);
784 * Easily overlooked: when mprotect shifts the boundary,
785 * make sure the expanding vma has anon_vma set if the
786 * shrinking vma had, to cover any anon pages imported.
788 if (exporter
&& exporter
->anon_vma
&& !importer
->anon_vma
) {
791 importer
->anon_vma
= exporter
->anon_vma
;
792 error
= anon_vma_clone(importer
, exporter
);
799 mapping
= file
->f_mapping
;
800 root
= &mapping
->i_mmap
;
801 uprobe_munmap(vma
, vma
->vm_start
, vma
->vm_end
);
804 uprobe_munmap(next
, next
->vm_start
, next
->vm_end
);
806 i_mmap_lock_write(mapping
);
809 * Put into interval tree now, so instantiated pages
810 * are visible to arm/parisc __flush_dcache_page
811 * throughout; but we cannot insert into address
812 * space until vma start or end is updated.
814 __vma_link_file(insert
);
818 vma_adjust_trans_huge(vma
, start
, end
, adjust_next
);
820 anon_vma
= vma
->anon_vma
;
821 if (!anon_vma
&& adjust_next
)
822 anon_vma
= next
->anon_vma
;
824 VM_BUG_ON_VMA(adjust_next
&& next
->anon_vma
&&
825 anon_vma
!= next
->anon_vma
, next
);
826 anon_vma_lock_write(anon_vma
);
827 anon_vma_interval_tree_pre_update_vma(vma
);
829 anon_vma_interval_tree_pre_update_vma(next
);
833 flush_dcache_mmap_lock(mapping
);
834 vma_interval_tree_remove(vma
, root
);
836 vma_interval_tree_remove(next
, root
);
839 if (start
!= vma
->vm_start
) {
840 vma
->vm_start
= start
;
841 start_changed
= true;
843 if (end
!= vma
->vm_end
) {
847 vma
->vm_pgoff
= pgoff
;
849 next
->vm_start
+= adjust_next
<< PAGE_SHIFT
;
850 next
->vm_pgoff
+= adjust_next
;
855 vma_interval_tree_insert(next
, root
);
856 vma_interval_tree_insert(vma
, root
);
857 flush_dcache_mmap_unlock(mapping
);
862 * vma_merge has merged next into vma, and needs
863 * us to remove next before dropping the locks.
865 __vma_unlink(mm
, next
, vma
);
867 __remove_shared_vm_struct(next
, file
, mapping
);
870 * split_vma has split insert from vma, and needs
871 * us to insert it before dropping the locks
872 * (it may either follow vma or precede it).
874 __insert_vm_struct(mm
, insert
);
880 mm
->highest_vm_end
= end
;
881 else if (!adjust_next
)
882 vma_gap_update(next
);
887 anon_vma_interval_tree_post_update_vma(vma
);
889 anon_vma_interval_tree_post_update_vma(next
);
890 anon_vma_unlock_write(anon_vma
);
893 i_mmap_unlock_write(mapping
);
904 uprobe_munmap(next
, next
->vm_start
, next
->vm_end
);
908 anon_vma_merge(vma
, next
);
910 mpol_put(vma_policy(next
));
911 kmem_cache_free(vm_area_cachep
, next
);
913 * In mprotect's case 6 (see comments on vma_merge),
914 * we must remove another next too. It would clutter
915 * up the code too much to do both in one go.
918 if (remove_next
== 2)
921 vma_gap_update(next
);
923 mm
->highest_vm_end
= end
;
934 * If the vma has a ->close operation then the driver probably needs to release
935 * per-vma resources, so we don't attempt to merge those.
937 static inline int is_mergeable_vma(struct vm_area_struct
*vma
,
938 struct file
*file
, unsigned long vm_flags
,
939 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
942 * VM_SOFTDIRTY should not prevent from VMA merging, if we
943 * match the flags but dirty bit -- the caller should mark
944 * merged VMA as dirty. If dirty bit won't be excluded from
945 * comparison, we increase pressue on the memory system forcing
946 * the kernel to generate new VMAs when old one could be
949 if ((vma
->vm_flags
^ vm_flags
) & ~VM_SOFTDIRTY
)
951 if (vma
->vm_file
!= file
)
953 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
955 if (!is_mergeable_vm_userfaultfd_ctx(vma
, vm_userfaultfd_ctx
))
960 static inline int is_mergeable_anon_vma(struct anon_vma
*anon_vma1
,
961 struct anon_vma
*anon_vma2
,
962 struct vm_area_struct
*vma
)
965 * The list_is_singular() test is to avoid merging VMA cloned from
966 * parents. This can improve scalability caused by anon_vma lock.
968 if ((!anon_vma1
|| !anon_vma2
) && (!vma
||
969 list_is_singular(&vma
->anon_vma_chain
)))
971 return anon_vma1
== anon_vma2
;
975 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
976 * in front of (at a lower virtual address and file offset than) the vma.
978 * We cannot merge two vmas if they have differently assigned (non-NULL)
979 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
981 * We don't check here for the merged mmap wrapping around the end of pagecache
982 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
983 * wrap, nor mmaps which cover the final page at index -1UL.
986 can_vma_merge_before(struct vm_area_struct
*vma
, unsigned long vm_flags
,
987 struct anon_vma
*anon_vma
, struct file
*file
,
989 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
991 if (is_mergeable_vma(vma
, file
, vm_flags
, vm_userfaultfd_ctx
) &&
992 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
993 if (vma
->vm_pgoff
== vm_pgoff
)
1000 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1001 * beyond (at a higher virtual address and file offset than) the vma.
1003 * We cannot merge two vmas if they have differently assigned (non-NULL)
1004 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1007 can_vma_merge_after(struct vm_area_struct
*vma
, unsigned long vm_flags
,
1008 struct anon_vma
*anon_vma
, struct file
*file
,
1010 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
1012 if (is_mergeable_vma(vma
, file
, vm_flags
, vm_userfaultfd_ctx
) &&
1013 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
1015 vm_pglen
= vma_pages(vma
);
1016 if (vma
->vm_pgoff
+ vm_pglen
== vm_pgoff
)
1023 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1024 * whether that can be merged with its predecessor or its successor.
1025 * Or both (it neatly fills a hole).
1027 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1028 * certain not to be mapped by the time vma_merge is called; but when
1029 * called for mprotect, it is certain to be already mapped (either at
1030 * an offset within prev, or at the start of next), and the flags of
1031 * this area are about to be changed to vm_flags - and the no-change
1032 * case has already been eliminated.
1034 * The following mprotect cases have to be considered, where AAAA is
1035 * the area passed down from mprotect_fixup, never extending beyond one
1036 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1038 * AAAA AAAA AAAA AAAA
1039 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1040 * cannot merge might become might become might become
1041 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1042 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1043 * mremap move: PPPPNNNNNNNN 8
1045 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1046 * might become case 1 below case 2 below case 3 below
1048 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1049 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1051 struct vm_area_struct
*vma_merge(struct mm_struct
*mm
,
1052 struct vm_area_struct
*prev
, unsigned long addr
,
1053 unsigned long end
, unsigned long vm_flags
,
1054 struct anon_vma
*anon_vma
, struct file
*file
,
1055 pgoff_t pgoff
, struct mempolicy
*policy
,
1056 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
1058 pgoff_t pglen
= (end
- addr
) >> PAGE_SHIFT
;
1059 struct vm_area_struct
*area
, *next
;
1063 * We later require that vma->vm_flags == vm_flags,
1064 * so this tests vma->vm_flags & VM_SPECIAL, too.
1066 if (vm_flags
& VM_SPECIAL
)
1070 next
= prev
->vm_next
;
1074 if (next
&& next
->vm_end
== end
) /* cases 6, 7, 8 */
1075 next
= next
->vm_next
;
1078 * Can it merge with the predecessor?
1080 if (prev
&& prev
->vm_end
== addr
&&
1081 mpol_equal(vma_policy(prev
), policy
) &&
1082 can_vma_merge_after(prev
, vm_flags
,
1083 anon_vma
, file
, pgoff
,
1084 vm_userfaultfd_ctx
)) {
1086 * OK, it can. Can we now merge in the successor as well?
1088 if (next
&& end
== next
->vm_start
&&
1089 mpol_equal(policy
, vma_policy(next
)) &&
1090 can_vma_merge_before(next
, vm_flags
,
1093 vm_userfaultfd_ctx
) &&
1094 is_mergeable_anon_vma(prev
->anon_vma
,
1095 next
->anon_vma
, NULL
)) {
1097 err
= vma_adjust(prev
, prev
->vm_start
,
1098 next
->vm_end
, prev
->vm_pgoff
, NULL
);
1099 } else /* cases 2, 5, 7 */
1100 err
= vma_adjust(prev
, prev
->vm_start
,
1101 end
, prev
->vm_pgoff
, NULL
);
1104 khugepaged_enter_vma_merge(prev
, vm_flags
);
1109 * Can this new request be merged in front of next?
1111 if (next
&& end
== next
->vm_start
&&
1112 mpol_equal(policy
, vma_policy(next
)) &&
1113 can_vma_merge_before(next
, vm_flags
,
1114 anon_vma
, file
, pgoff
+pglen
,
1115 vm_userfaultfd_ctx
)) {
1116 if (prev
&& addr
< prev
->vm_end
) /* case 4 */
1117 err
= vma_adjust(prev
, prev
->vm_start
,
1118 addr
, prev
->vm_pgoff
, NULL
);
1119 else /* cases 3, 8 */
1120 err
= vma_adjust(area
, addr
, next
->vm_end
,
1121 next
->vm_pgoff
- pglen
, NULL
);
1124 khugepaged_enter_vma_merge(area
, vm_flags
);
1132 * Rough compatbility check to quickly see if it's even worth looking
1133 * at sharing an anon_vma.
1135 * They need to have the same vm_file, and the flags can only differ
1136 * in things that mprotect may change.
1138 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1139 * we can merge the two vma's. For example, we refuse to merge a vma if
1140 * there is a vm_ops->close() function, because that indicates that the
1141 * driver is doing some kind of reference counting. But that doesn't
1142 * really matter for the anon_vma sharing case.
1144 static int anon_vma_compatible(struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1146 return a
->vm_end
== b
->vm_start
&&
1147 mpol_equal(vma_policy(a
), vma_policy(b
)) &&
1148 a
->vm_file
== b
->vm_file
&&
1149 !((a
->vm_flags
^ b
->vm_flags
) & ~(VM_READ
|VM_WRITE
|VM_EXEC
|VM_SOFTDIRTY
)) &&
1150 b
->vm_pgoff
== a
->vm_pgoff
+ ((b
->vm_start
- a
->vm_start
) >> PAGE_SHIFT
);
1154 * Do some basic sanity checking to see if we can re-use the anon_vma
1155 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1156 * the same as 'old', the other will be the new one that is trying
1157 * to share the anon_vma.
1159 * NOTE! This runs with mm_sem held for reading, so it is possible that
1160 * the anon_vma of 'old' is concurrently in the process of being set up
1161 * by another page fault trying to merge _that_. But that's ok: if it
1162 * is being set up, that automatically means that it will be a singleton
1163 * acceptable for merging, so we can do all of this optimistically. But
1164 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1166 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1167 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1168 * is to return an anon_vma that is "complex" due to having gone through
1171 * We also make sure that the two vma's are compatible (adjacent,
1172 * and with the same memory policies). That's all stable, even with just
1173 * a read lock on the mm_sem.
1175 static struct anon_vma
*reusable_anon_vma(struct vm_area_struct
*old
, struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1177 if (anon_vma_compatible(a
, b
)) {
1178 struct anon_vma
*anon_vma
= READ_ONCE(old
->anon_vma
);
1180 if (anon_vma
&& list_is_singular(&old
->anon_vma_chain
))
1187 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1188 * neighbouring vmas for a suitable anon_vma, before it goes off
1189 * to allocate a new anon_vma. It checks because a repetitive
1190 * sequence of mprotects and faults may otherwise lead to distinct
1191 * anon_vmas being allocated, preventing vma merge in subsequent
1194 struct anon_vma
*find_mergeable_anon_vma(struct vm_area_struct
*vma
)
1196 struct anon_vma
*anon_vma
;
1197 struct vm_area_struct
*near
;
1199 near
= vma
->vm_next
;
1203 anon_vma
= reusable_anon_vma(near
, vma
, near
);
1207 near
= vma
->vm_prev
;
1211 anon_vma
= reusable_anon_vma(near
, near
, vma
);
1216 * There's no absolute need to look only at touching neighbours:
1217 * we could search further afield for "compatible" anon_vmas.
1218 * But it would probably just be a waste of time searching,
1219 * or lead to too many vmas hanging off the same anon_vma.
1220 * We're trying to allow mprotect remerging later on,
1221 * not trying to minimize memory used for anon_vmas.
1227 * If a hint addr is less than mmap_min_addr change hint to be as
1228 * low as possible but still greater than mmap_min_addr
1230 static inline unsigned long round_hint_to_min(unsigned long hint
)
1233 if (((void *)hint
!= NULL
) &&
1234 (hint
< mmap_min_addr
))
1235 return PAGE_ALIGN(mmap_min_addr
);
1239 static inline int mlock_future_check(struct mm_struct
*mm
,
1240 unsigned long flags
,
1243 unsigned long locked
, lock_limit
;
1245 /* mlock MCL_FUTURE? */
1246 if (flags
& VM_LOCKED
) {
1247 locked
= len
>> PAGE_SHIFT
;
1248 locked
+= mm
->locked_vm
;
1249 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
1250 lock_limit
>>= PAGE_SHIFT
;
1251 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
1258 * The caller must hold down_write(¤t->mm->mmap_sem).
1260 unsigned long do_mmap(struct file
*file
, unsigned long addr
,
1261 unsigned long len
, unsigned long prot
,
1262 unsigned long flags
, vm_flags_t vm_flags
,
1263 unsigned long pgoff
, unsigned long *populate
)
1265 struct mm_struct
*mm
= current
->mm
;
1273 * Does the application expect PROT_READ to imply PROT_EXEC?
1275 * (the exception is when the underlying filesystem is noexec
1276 * mounted, in which case we dont add PROT_EXEC.)
1278 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
1279 if (!(file
&& path_noexec(&file
->f_path
)))
1282 if (!(flags
& MAP_FIXED
))
1283 addr
= round_hint_to_min(addr
);
1285 /* Careful about overflows.. */
1286 len
= PAGE_ALIGN(len
);
1290 /* offset overflow? */
1291 if ((pgoff
+ (len
>> PAGE_SHIFT
)) < pgoff
)
1294 /* Too many mappings? */
1295 if (mm
->map_count
> sysctl_max_map_count
)
1298 /* Obtain the address to map to. we verify (or select) it and ensure
1299 * that it represents a valid section of the address space.
1301 addr
= get_unmapped_area(file
, addr
, len
, pgoff
, flags
);
1302 if (offset_in_page(addr
))
1305 /* Do simple checking here so the lower-level routines won't have
1306 * to. we assume access permissions have been handled by the open
1307 * of the memory object, so we don't do any here.
1309 vm_flags
|= calc_vm_prot_bits(prot
) | calc_vm_flag_bits(flags
) |
1310 mm
->def_flags
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1312 if (flags
& MAP_LOCKED
)
1313 if (!can_do_mlock())
1316 if (mlock_future_check(mm
, vm_flags
, len
))
1320 struct inode
*inode
= file_inode(file
);
1322 switch (flags
& MAP_TYPE
) {
1324 if ((prot
&PROT_WRITE
) && !(file
->f_mode
&FMODE_WRITE
))
1328 * Make sure we don't allow writing to an append-only
1331 if (IS_APPEND(inode
) && (file
->f_mode
& FMODE_WRITE
))
1335 * Make sure there are no mandatory locks on the file.
1337 if (locks_verify_locked(file
))
1340 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1341 if (!(file
->f_mode
& FMODE_WRITE
))
1342 vm_flags
&= ~(VM_MAYWRITE
| VM_SHARED
);
1346 if (!(file
->f_mode
& FMODE_READ
))
1348 if (path_noexec(&file
->f_path
)) {
1349 if (vm_flags
& VM_EXEC
)
1351 vm_flags
&= ~VM_MAYEXEC
;
1354 if (!file
->f_op
->mmap
)
1356 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1364 switch (flags
& MAP_TYPE
) {
1366 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1372 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1376 * Set pgoff according to addr for anon_vma.
1378 pgoff
= addr
>> PAGE_SHIFT
;
1386 * Set 'VM_NORESERVE' if we should not account for the
1387 * memory use of this mapping.
1389 if (flags
& MAP_NORESERVE
) {
1390 /* We honor MAP_NORESERVE if allowed to overcommit */
1391 if (sysctl_overcommit_memory
!= OVERCOMMIT_NEVER
)
1392 vm_flags
|= VM_NORESERVE
;
1394 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1395 if (file
&& is_file_hugepages(file
))
1396 vm_flags
|= VM_NORESERVE
;
1399 addr
= mmap_region(file
, addr
, len
, vm_flags
, pgoff
);
1400 if (!IS_ERR_VALUE(addr
) &&
1401 ((vm_flags
& VM_LOCKED
) ||
1402 (flags
& (MAP_POPULATE
| MAP_NONBLOCK
)) == MAP_POPULATE
))
1407 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1408 unsigned long, prot
, unsigned long, flags
,
1409 unsigned long, fd
, unsigned long, pgoff
)
1411 struct file
*file
= NULL
;
1412 unsigned long retval
;
1414 if (!(flags
& MAP_ANONYMOUS
)) {
1415 audit_mmap_fd(fd
, flags
);
1419 if (is_file_hugepages(file
))
1420 len
= ALIGN(len
, huge_page_size(hstate_file(file
)));
1422 if (unlikely(flags
& MAP_HUGETLB
&& !is_file_hugepages(file
)))
1424 } else if (flags
& MAP_HUGETLB
) {
1425 struct user_struct
*user
= NULL
;
1428 hs
= hstate_sizelog((flags
>> MAP_HUGE_SHIFT
) & SHM_HUGE_MASK
);
1432 len
= ALIGN(len
, huge_page_size(hs
));
1434 * VM_NORESERVE is used because the reservations will be
1435 * taken when vm_ops->mmap() is called
1436 * A dummy user value is used because we are not locking
1437 * memory so no accounting is necessary
1439 file
= hugetlb_file_setup(HUGETLB_ANON_FILE
, len
,
1441 &user
, HUGETLB_ANONHUGE_INODE
,
1442 (flags
>> MAP_HUGE_SHIFT
) & MAP_HUGE_MASK
);
1444 return PTR_ERR(file
);
1447 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1449 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1456 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1457 struct mmap_arg_struct
{
1461 unsigned long flags
;
1463 unsigned long offset
;
1466 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1468 struct mmap_arg_struct a
;
1470 if (copy_from_user(&a
, arg
, sizeof(a
)))
1472 if (offset_in_page(a
.offset
))
1475 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1476 a
.offset
>> PAGE_SHIFT
);
1478 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1481 * Some shared mappigns will want the pages marked read-only
1482 * to track write events. If so, we'll downgrade vm_page_prot
1483 * to the private version (using protection_map[] without the
1486 int vma_wants_writenotify(struct vm_area_struct
*vma
)
1488 vm_flags_t vm_flags
= vma
->vm_flags
;
1489 const struct vm_operations_struct
*vm_ops
= vma
->vm_ops
;
1491 /* If it was private or non-writable, the write bit is already clear */
1492 if ((vm_flags
& (VM_WRITE
|VM_SHARED
)) != ((VM_WRITE
|VM_SHARED
)))
1495 /* The backer wishes to know when pages are first written to? */
1496 if (vm_ops
&& (vm_ops
->page_mkwrite
|| vm_ops
->pfn_mkwrite
))
1499 /* The open routine did something to the protections that pgprot_modify
1500 * won't preserve? */
1501 if (pgprot_val(vma
->vm_page_prot
) !=
1502 pgprot_val(vm_pgprot_modify(vma
->vm_page_prot
, vm_flags
)))
1505 /* Do we need to track softdirty? */
1506 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY
) && !(vm_flags
& VM_SOFTDIRTY
))
1509 /* Specialty mapping? */
1510 if (vm_flags
& VM_PFNMAP
)
1513 /* Can the mapping track the dirty pages? */
1514 return vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
1515 mapping_cap_account_dirty(vma
->vm_file
->f_mapping
);
1519 * We account for memory if it's a private writeable mapping,
1520 * not hugepages and VM_NORESERVE wasn't set.
1522 static inline int accountable_mapping(struct file
*file
, vm_flags_t vm_flags
)
1525 * hugetlb has its own accounting separate from the core VM
1526 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1528 if (file
&& is_file_hugepages(file
))
1531 return (vm_flags
& (VM_NORESERVE
| VM_SHARED
| VM_WRITE
)) == VM_WRITE
;
1534 unsigned long mmap_region(struct file
*file
, unsigned long addr
,
1535 unsigned long len
, vm_flags_t vm_flags
, unsigned long pgoff
)
1537 struct mm_struct
*mm
= current
->mm
;
1538 struct vm_area_struct
*vma
, *prev
;
1540 struct rb_node
**rb_link
, *rb_parent
;
1541 unsigned long charged
= 0;
1543 /* Check against address space limit. */
1544 if (!may_expand_vm(mm
, vm_flags
, len
>> PAGE_SHIFT
)) {
1545 unsigned long nr_pages
;
1548 * MAP_FIXED may remove pages of mappings that intersects with
1549 * requested mapping. Account for the pages it would unmap.
1551 nr_pages
= count_vma_pages_range(mm
, addr
, addr
+ len
);
1553 if (!may_expand_vm(mm
, vm_flags
,
1554 (len
>> PAGE_SHIFT
) - nr_pages
))
1558 /* Clear old maps */
1559 while (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
,
1561 if (do_munmap(mm
, addr
, len
))
1566 * Private writable mapping: check memory availability
1568 if (accountable_mapping(file
, vm_flags
)) {
1569 charged
= len
>> PAGE_SHIFT
;
1570 if (security_vm_enough_memory_mm(mm
, charged
))
1572 vm_flags
|= VM_ACCOUNT
;
1576 * Can we just expand an old mapping?
1578 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vm_flags
,
1579 NULL
, file
, pgoff
, NULL
, NULL_VM_UFFD_CTX
);
1584 * Determine the object being mapped and call the appropriate
1585 * specific mapper. the address has already been validated, but
1586 * not unmapped, but the maps are removed from the list.
1588 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1595 vma
->vm_start
= addr
;
1596 vma
->vm_end
= addr
+ len
;
1597 vma
->vm_flags
= vm_flags
;
1598 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
);
1599 vma
->vm_pgoff
= pgoff
;
1600 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1603 if (vm_flags
& VM_DENYWRITE
) {
1604 error
= deny_write_access(file
);
1608 if (vm_flags
& VM_SHARED
) {
1609 error
= mapping_map_writable(file
->f_mapping
);
1611 goto allow_write_and_free_vma
;
1614 /* ->mmap() can change vma->vm_file, but must guarantee that
1615 * vma_link() below can deny write-access if VM_DENYWRITE is set
1616 * and map writably if VM_SHARED is set. This usually means the
1617 * new file must not have been exposed to user-space, yet.
1619 vma
->vm_file
= get_file(file
);
1620 error
= file
->f_op
->mmap(file
, vma
);
1622 goto unmap_and_free_vma
;
1624 /* Can addr have changed??
1626 * Answer: Yes, several device drivers can do it in their
1627 * f_op->mmap method. -DaveM
1628 * Bug: If addr is changed, prev, rb_link, rb_parent should
1629 * be updated for vma_link()
1631 WARN_ON_ONCE(addr
!= vma
->vm_start
);
1633 addr
= vma
->vm_start
;
1634 vm_flags
= vma
->vm_flags
;
1635 } else if (vm_flags
& VM_SHARED
) {
1636 error
= shmem_zero_setup(vma
);
1641 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
1642 /* Once vma denies write, undo our temporary denial count */
1644 if (vm_flags
& VM_SHARED
)
1645 mapping_unmap_writable(file
->f_mapping
);
1646 if (vm_flags
& VM_DENYWRITE
)
1647 allow_write_access(file
);
1649 file
= vma
->vm_file
;
1651 perf_event_mmap(vma
);
1653 vm_stat_account(mm
, vm_flags
, len
>> PAGE_SHIFT
);
1654 if (vm_flags
& VM_LOCKED
) {
1655 if (!((vm_flags
& VM_SPECIAL
) || is_vm_hugetlb_page(vma
) ||
1656 vma
== get_gate_vma(current
->mm
)))
1657 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
1659 vma
->vm_flags
&= VM_LOCKED_CLEAR_MASK
;
1666 * New (or expanded) vma always get soft dirty status.
1667 * Otherwise user-space soft-dirty page tracker won't
1668 * be able to distinguish situation when vma area unmapped,
1669 * then new mapped in-place (which must be aimed as
1670 * a completely new data area).
1672 vma
->vm_flags
|= VM_SOFTDIRTY
;
1674 vma_set_page_prot(vma
);
1679 vma
->vm_file
= NULL
;
1682 /* Undo any partial mapping done by a device driver. */
1683 unmap_region(mm
, vma
, prev
, vma
->vm_start
, vma
->vm_end
);
1685 if (vm_flags
& VM_SHARED
)
1686 mapping_unmap_writable(file
->f_mapping
);
1687 allow_write_and_free_vma
:
1688 if (vm_flags
& VM_DENYWRITE
)
1689 allow_write_access(file
);
1691 kmem_cache_free(vm_area_cachep
, vma
);
1694 vm_unacct_memory(charged
);
1698 unsigned long unmapped_area(struct vm_unmapped_area_info
*info
)
1701 * We implement the search by looking for an rbtree node that
1702 * immediately follows a suitable gap. That is,
1703 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1704 * - gap_end = vma->vm_start >= info->low_limit + length;
1705 * - gap_end - gap_start >= length
1708 struct mm_struct
*mm
= current
->mm
;
1709 struct vm_area_struct
*vma
;
1710 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1712 /* Adjust search length to account for worst case alignment overhead */
1713 length
= info
->length
+ info
->align_mask
;
1714 if (length
< info
->length
)
1717 /* Adjust search limits by the desired length */
1718 if (info
->high_limit
< length
)
1720 high_limit
= info
->high_limit
- length
;
1722 if (info
->low_limit
> high_limit
)
1724 low_limit
= info
->low_limit
+ length
;
1726 /* Check if rbtree root looks promising */
1727 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1729 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1730 if (vma
->rb_subtree_gap
< length
)
1734 /* Visit left subtree if it looks promising */
1735 gap_end
= vma
->vm_start
;
1736 if (gap_end
>= low_limit
&& vma
->vm_rb
.rb_left
) {
1737 struct vm_area_struct
*left
=
1738 rb_entry(vma
->vm_rb
.rb_left
,
1739 struct vm_area_struct
, vm_rb
);
1740 if (left
->rb_subtree_gap
>= length
) {
1746 gap_start
= vma
->vm_prev
? vma
->vm_prev
->vm_end
: 0;
1748 /* Check if current node has a suitable gap */
1749 if (gap_start
> high_limit
)
1751 if (gap_end
>= low_limit
&& gap_end
- gap_start
>= length
)
1754 /* Visit right subtree if it looks promising */
1755 if (vma
->vm_rb
.rb_right
) {
1756 struct vm_area_struct
*right
=
1757 rb_entry(vma
->vm_rb
.rb_right
,
1758 struct vm_area_struct
, vm_rb
);
1759 if (right
->rb_subtree_gap
>= length
) {
1765 /* Go back up the rbtree to find next candidate node */
1767 struct rb_node
*prev
= &vma
->vm_rb
;
1768 if (!rb_parent(prev
))
1770 vma
= rb_entry(rb_parent(prev
),
1771 struct vm_area_struct
, vm_rb
);
1772 if (prev
== vma
->vm_rb
.rb_left
) {
1773 gap_start
= vma
->vm_prev
->vm_end
;
1774 gap_end
= vma
->vm_start
;
1781 /* Check highest gap, which does not precede any rbtree node */
1782 gap_start
= mm
->highest_vm_end
;
1783 gap_end
= ULONG_MAX
; /* Only for VM_BUG_ON below */
1784 if (gap_start
> high_limit
)
1788 /* We found a suitable gap. Clip it with the original low_limit. */
1789 if (gap_start
< info
->low_limit
)
1790 gap_start
= info
->low_limit
;
1792 /* Adjust gap address to the desired alignment */
1793 gap_start
+= (info
->align_offset
- gap_start
) & info
->align_mask
;
1795 VM_BUG_ON(gap_start
+ info
->length
> info
->high_limit
);
1796 VM_BUG_ON(gap_start
+ info
->length
> gap_end
);
1800 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info
*info
)
1802 struct mm_struct
*mm
= current
->mm
;
1803 struct vm_area_struct
*vma
;
1804 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1806 /* Adjust search length to account for worst case alignment overhead */
1807 length
= info
->length
+ info
->align_mask
;
1808 if (length
< info
->length
)
1812 * Adjust search limits by the desired length.
1813 * See implementation comment at top of unmapped_area().
1815 gap_end
= info
->high_limit
;
1816 if (gap_end
< length
)
1818 high_limit
= gap_end
- length
;
1820 if (info
->low_limit
> high_limit
)
1822 low_limit
= info
->low_limit
+ length
;
1824 /* Check highest gap, which does not precede any rbtree node */
1825 gap_start
= mm
->highest_vm_end
;
1826 if (gap_start
<= high_limit
)
1829 /* Check if rbtree root looks promising */
1830 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1832 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1833 if (vma
->rb_subtree_gap
< length
)
1837 /* Visit right subtree if it looks promising */
1838 gap_start
= vma
->vm_prev
? vma
->vm_prev
->vm_end
: 0;
1839 if (gap_start
<= high_limit
&& vma
->vm_rb
.rb_right
) {
1840 struct vm_area_struct
*right
=
1841 rb_entry(vma
->vm_rb
.rb_right
,
1842 struct vm_area_struct
, vm_rb
);
1843 if (right
->rb_subtree_gap
>= length
) {
1850 /* Check if current node has a suitable gap */
1851 gap_end
= vma
->vm_start
;
1852 if (gap_end
< low_limit
)
1854 if (gap_start
<= high_limit
&& gap_end
- gap_start
>= length
)
1857 /* Visit left subtree if it looks promising */
1858 if (vma
->vm_rb
.rb_left
) {
1859 struct vm_area_struct
*left
=
1860 rb_entry(vma
->vm_rb
.rb_left
,
1861 struct vm_area_struct
, vm_rb
);
1862 if (left
->rb_subtree_gap
>= length
) {
1868 /* Go back up the rbtree to find next candidate node */
1870 struct rb_node
*prev
= &vma
->vm_rb
;
1871 if (!rb_parent(prev
))
1873 vma
= rb_entry(rb_parent(prev
),
1874 struct vm_area_struct
, vm_rb
);
1875 if (prev
== vma
->vm_rb
.rb_right
) {
1876 gap_start
= vma
->vm_prev
?
1877 vma
->vm_prev
->vm_end
: 0;
1884 /* We found a suitable gap. Clip it with the original high_limit. */
1885 if (gap_end
> info
->high_limit
)
1886 gap_end
= info
->high_limit
;
1889 /* Compute highest gap address at the desired alignment */
1890 gap_end
-= info
->length
;
1891 gap_end
-= (gap_end
- info
->align_offset
) & info
->align_mask
;
1893 VM_BUG_ON(gap_end
< info
->low_limit
);
1894 VM_BUG_ON(gap_end
< gap_start
);
1898 /* Get an address range which is currently unmapped.
1899 * For shmat() with addr=0.
1901 * Ugly calling convention alert:
1902 * Return value with the low bits set means error value,
1904 * if (ret & ~PAGE_MASK)
1907 * This function "knows" that -ENOMEM has the bits set.
1909 #ifndef HAVE_ARCH_UNMAPPED_AREA
1911 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
1912 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1914 struct mm_struct
*mm
= current
->mm
;
1915 struct vm_area_struct
*vma
;
1916 struct vm_unmapped_area_info info
;
1918 if (len
> TASK_SIZE
- mmap_min_addr
)
1921 if (flags
& MAP_FIXED
)
1925 addr
= PAGE_ALIGN(addr
);
1926 vma
= find_vma(mm
, addr
);
1927 if (TASK_SIZE
- len
>= addr
&& addr
>= mmap_min_addr
&&
1928 (!vma
|| addr
+ len
<= vma
->vm_start
))
1934 info
.low_limit
= mm
->mmap_base
;
1935 info
.high_limit
= TASK_SIZE
;
1936 info
.align_mask
= 0;
1937 return vm_unmapped_area(&info
);
1942 * This mmap-allocator allocates new areas top-down from below the
1943 * stack's low limit (the base):
1945 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1947 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
1948 const unsigned long len
, const unsigned long pgoff
,
1949 const unsigned long flags
)
1951 struct vm_area_struct
*vma
;
1952 struct mm_struct
*mm
= current
->mm
;
1953 unsigned long addr
= addr0
;
1954 struct vm_unmapped_area_info info
;
1956 /* requested length too big for entire address space */
1957 if (len
> TASK_SIZE
- mmap_min_addr
)
1960 if (flags
& MAP_FIXED
)
1963 /* requesting a specific address */
1965 addr
= PAGE_ALIGN(addr
);
1966 vma
= find_vma(mm
, addr
);
1967 if (TASK_SIZE
- len
>= addr
&& addr
>= mmap_min_addr
&&
1968 (!vma
|| addr
+ len
<= vma
->vm_start
))
1972 info
.flags
= VM_UNMAPPED_AREA_TOPDOWN
;
1974 info
.low_limit
= max(PAGE_SIZE
, mmap_min_addr
);
1975 info
.high_limit
= mm
->mmap_base
;
1976 info
.align_mask
= 0;
1977 addr
= vm_unmapped_area(&info
);
1980 * A failed mmap() very likely causes application failure,
1981 * so fall back to the bottom-up function here. This scenario
1982 * can happen with large stack limits and large mmap()
1985 if (offset_in_page(addr
)) {
1986 VM_BUG_ON(addr
!= -ENOMEM
);
1988 info
.low_limit
= TASK_UNMAPPED_BASE
;
1989 info
.high_limit
= TASK_SIZE
;
1990 addr
= vm_unmapped_area(&info
);
1998 get_unmapped_area(struct file
*file
, unsigned long addr
, unsigned long len
,
1999 unsigned long pgoff
, unsigned long flags
)
2001 unsigned long (*get_area
)(struct file
*, unsigned long,
2002 unsigned long, unsigned long, unsigned long);
2004 unsigned long error
= arch_mmap_check(addr
, len
, flags
);
2008 /* Careful about overflows.. */
2009 if (len
> TASK_SIZE
)
2012 get_area
= current
->mm
->get_unmapped_area
;
2013 if (file
&& file
->f_op
->get_unmapped_area
)
2014 get_area
= file
->f_op
->get_unmapped_area
;
2015 addr
= get_area(file
, addr
, len
, pgoff
, flags
);
2016 if (IS_ERR_VALUE(addr
))
2019 if (addr
> TASK_SIZE
- len
)
2021 if (offset_in_page(addr
))
2024 addr
= arch_rebalance_pgtables(addr
, len
);
2025 error
= security_mmap_addr(addr
);
2026 return error
? error
: addr
;
2029 EXPORT_SYMBOL(get_unmapped_area
);
2031 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2032 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
2034 struct rb_node
*rb_node
;
2035 struct vm_area_struct
*vma
;
2037 /* Check the cache first. */
2038 vma
= vmacache_find(mm
, addr
);
2042 rb_node
= mm
->mm_rb
.rb_node
;
2045 struct vm_area_struct
*tmp
;
2047 tmp
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
2049 if (tmp
->vm_end
> addr
) {
2051 if (tmp
->vm_start
<= addr
)
2053 rb_node
= rb_node
->rb_left
;
2055 rb_node
= rb_node
->rb_right
;
2059 vmacache_update(addr
, vma
);
2063 EXPORT_SYMBOL(find_vma
);
2066 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2068 struct vm_area_struct
*
2069 find_vma_prev(struct mm_struct
*mm
, unsigned long addr
,
2070 struct vm_area_struct
**pprev
)
2072 struct vm_area_struct
*vma
;
2074 vma
= find_vma(mm
, addr
);
2076 *pprev
= vma
->vm_prev
;
2078 struct rb_node
*rb_node
= mm
->mm_rb
.rb_node
;
2081 *pprev
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
2082 rb_node
= rb_node
->rb_right
;
2089 * Verify that the stack growth is acceptable and
2090 * update accounting. This is shared with both the
2091 * grow-up and grow-down cases.
2093 static int acct_stack_growth(struct vm_area_struct
*vma
, unsigned long size
, unsigned long grow
)
2095 struct mm_struct
*mm
= vma
->vm_mm
;
2096 struct rlimit
*rlim
= current
->signal
->rlim
;
2097 unsigned long new_start
, actual_size
;
2099 /* address space limit tests */
2100 if (!may_expand_vm(mm
, vma
->vm_flags
, grow
))
2103 /* Stack limit test */
2105 if (size
&& (vma
->vm_flags
& (VM_GROWSUP
| VM_GROWSDOWN
)))
2106 actual_size
-= PAGE_SIZE
;
2107 if (actual_size
> READ_ONCE(rlim
[RLIMIT_STACK
].rlim_cur
))
2110 /* mlock limit tests */
2111 if (vma
->vm_flags
& VM_LOCKED
) {
2112 unsigned long locked
;
2113 unsigned long limit
;
2114 locked
= mm
->locked_vm
+ grow
;
2115 limit
= READ_ONCE(rlim
[RLIMIT_MEMLOCK
].rlim_cur
);
2116 limit
>>= PAGE_SHIFT
;
2117 if (locked
> limit
&& !capable(CAP_IPC_LOCK
))
2121 /* Check to ensure the stack will not grow into a hugetlb-only region */
2122 new_start
= (vma
->vm_flags
& VM_GROWSUP
) ? vma
->vm_start
:
2124 if (is_hugepage_only_range(vma
->vm_mm
, new_start
, size
))
2128 * Overcommit.. This must be the final test, as it will
2129 * update security statistics.
2131 if (security_vm_enough_memory_mm(mm
, grow
))
2137 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2139 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2140 * vma is the last one with address > vma->vm_end. Have to extend vma.
2142 int expand_upwards(struct vm_area_struct
*vma
, unsigned long address
)
2144 struct mm_struct
*mm
= vma
->vm_mm
;
2147 if (!(vma
->vm_flags
& VM_GROWSUP
))
2151 * We must make sure the anon_vma is allocated
2152 * so that the anon_vma locking is not a noop.
2154 if (unlikely(anon_vma_prepare(vma
)))
2156 vma_lock_anon_vma(vma
);
2159 * vma->vm_start/vm_end cannot change under us because the caller
2160 * is required to hold the mmap_sem in read mode. We need the
2161 * anon_vma lock to serialize against concurrent expand_stacks.
2162 * Also guard against wrapping around to address 0.
2164 if (address
< PAGE_ALIGN(address
+4))
2165 address
= PAGE_ALIGN(address
+4);
2167 vma_unlock_anon_vma(vma
);
2172 /* Somebody else might have raced and expanded it already */
2173 if (address
> vma
->vm_end
) {
2174 unsigned long size
, grow
;
2176 size
= address
- vma
->vm_start
;
2177 grow
= (address
- vma
->vm_end
) >> PAGE_SHIFT
;
2180 if (vma
->vm_pgoff
+ (size
>> PAGE_SHIFT
) >= vma
->vm_pgoff
) {
2181 error
= acct_stack_growth(vma
, size
, grow
);
2184 * vma_gap_update() doesn't support concurrent
2185 * updates, but we only hold a shared mmap_sem
2186 * lock here, so we need to protect against
2187 * concurrent vma expansions.
2188 * vma_lock_anon_vma() doesn't help here, as
2189 * we don't guarantee that all growable vmas
2190 * in a mm share the same root anon vma.
2191 * So, we reuse mm->page_table_lock to guard
2192 * against concurrent vma expansions.
2194 spin_lock(&mm
->page_table_lock
);
2195 if (vma
->vm_flags
& VM_LOCKED
)
2196 mm
->locked_vm
+= grow
;
2197 vm_stat_account(mm
, vma
->vm_flags
, grow
);
2198 anon_vma_interval_tree_pre_update_vma(vma
);
2199 vma
->vm_end
= address
;
2200 anon_vma_interval_tree_post_update_vma(vma
);
2202 vma_gap_update(vma
->vm_next
);
2204 mm
->highest_vm_end
= address
;
2205 spin_unlock(&mm
->page_table_lock
);
2207 perf_event_mmap(vma
);
2211 vma_unlock_anon_vma(vma
);
2212 khugepaged_enter_vma_merge(vma
, vma
->vm_flags
);
2216 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2219 * vma is the first one with address < vma->vm_start. Have to extend vma.
2221 int expand_downwards(struct vm_area_struct
*vma
,
2222 unsigned long address
)
2224 struct mm_struct
*mm
= vma
->vm_mm
;
2228 * We must make sure the anon_vma is allocated
2229 * so that the anon_vma locking is not a noop.
2231 if (unlikely(anon_vma_prepare(vma
)))
2234 address
&= PAGE_MASK
;
2235 error
= security_mmap_addr(address
);
2239 vma_lock_anon_vma(vma
);
2242 * vma->vm_start/vm_end cannot change under us because the caller
2243 * is required to hold the mmap_sem in read mode. We need the
2244 * anon_vma lock to serialize against concurrent expand_stacks.
2247 /* Somebody else might have raced and expanded it already */
2248 if (address
< vma
->vm_start
) {
2249 unsigned long size
, grow
;
2251 size
= vma
->vm_end
- address
;
2252 grow
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
2255 if (grow
<= vma
->vm_pgoff
) {
2256 error
= acct_stack_growth(vma
, size
, grow
);
2259 * vma_gap_update() doesn't support concurrent
2260 * updates, but we only hold a shared mmap_sem
2261 * lock here, so we need to protect against
2262 * concurrent vma expansions.
2263 * vma_lock_anon_vma() doesn't help here, as
2264 * we don't guarantee that all growable vmas
2265 * in a mm share the same root anon vma.
2266 * So, we reuse mm->page_table_lock to guard
2267 * against concurrent vma expansions.
2269 spin_lock(&mm
->page_table_lock
);
2270 if (vma
->vm_flags
& VM_LOCKED
)
2271 mm
->locked_vm
+= grow
;
2272 vm_stat_account(mm
, vma
->vm_flags
, grow
);
2273 anon_vma_interval_tree_pre_update_vma(vma
);
2274 vma
->vm_start
= address
;
2275 vma
->vm_pgoff
-= grow
;
2276 anon_vma_interval_tree_post_update_vma(vma
);
2277 vma_gap_update(vma
);
2278 spin_unlock(&mm
->page_table_lock
);
2280 perf_event_mmap(vma
);
2284 vma_unlock_anon_vma(vma
);
2285 khugepaged_enter_vma_merge(vma
, vma
->vm_flags
);
2291 * Note how expand_stack() refuses to expand the stack all the way to
2292 * abut the next virtual mapping, *unless* that mapping itself is also
2293 * a stack mapping. We want to leave room for a guard page, after all
2294 * (the guard page itself is not added here, that is done by the
2295 * actual page faulting logic)
2297 * This matches the behavior of the guard page logic (see mm/memory.c:
2298 * check_stack_guard_page()), which only allows the guard page to be
2299 * removed under these circumstances.
2301 #ifdef CONFIG_STACK_GROWSUP
2302 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2304 struct vm_area_struct
*next
;
2306 address
&= PAGE_MASK
;
2307 next
= vma
->vm_next
;
2308 if (next
&& next
->vm_start
== address
+ PAGE_SIZE
) {
2309 if (!(next
->vm_flags
& VM_GROWSUP
))
2312 return expand_upwards(vma
, address
);
2315 struct vm_area_struct
*
2316 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
2318 struct vm_area_struct
*vma
, *prev
;
2321 vma
= find_vma_prev(mm
, addr
, &prev
);
2322 if (vma
&& (vma
->vm_start
<= addr
))
2324 if (!prev
|| expand_stack(prev
, addr
))
2326 if (prev
->vm_flags
& VM_LOCKED
)
2327 populate_vma_page_range(prev
, addr
, prev
->vm_end
, NULL
);
2331 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2333 struct vm_area_struct
*prev
;
2335 address
&= PAGE_MASK
;
2336 prev
= vma
->vm_prev
;
2337 if (prev
&& prev
->vm_end
== address
) {
2338 if (!(prev
->vm_flags
& VM_GROWSDOWN
))
2341 return expand_downwards(vma
, address
);
2344 struct vm_area_struct
*
2345 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
2347 struct vm_area_struct
*vma
;
2348 unsigned long start
;
2351 vma
= find_vma(mm
, addr
);
2354 if (vma
->vm_start
<= addr
)
2356 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
2358 start
= vma
->vm_start
;
2359 if (expand_stack(vma
, addr
))
2361 if (vma
->vm_flags
& VM_LOCKED
)
2362 populate_vma_page_range(vma
, addr
, start
, NULL
);
2367 EXPORT_SYMBOL_GPL(find_extend_vma
);
2370 * Ok - we have the memory areas we should free on the vma list,
2371 * so release them, and do the vma updates.
2373 * Called with the mm semaphore held.
2375 static void remove_vma_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
2377 unsigned long nr_accounted
= 0;
2379 /* Update high watermark before we lower total_vm */
2380 update_hiwater_vm(mm
);
2382 long nrpages
= vma_pages(vma
);
2384 if (vma
->vm_flags
& VM_ACCOUNT
)
2385 nr_accounted
+= nrpages
;
2386 vm_stat_account(mm
, vma
->vm_flags
, -nrpages
);
2387 vma
= remove_vma(vma
);
2389 vm_unacct_memory(nr_accounted
);
2394 * Get rid of page table information in the indicated region.
2396 * Called with the mm semaphore held.
2398 static void unmap_region(struct mm_struct
*mm
,
2399 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
2400 unsigned long start
, unsigned long end
)
2402 struct vm_area_struct
*next
= prev
? prev
->vm_next
: mm
->mmap
;
2403 struct mmu_gather tlb
;
2406 tlb_gather_mmu(&tlb
, mm
, start
, end
);
2407 update_hiwater_rss(mm
);
2408 unmap_vmas(&tlb
, vma
, start
, end
);
2409 free_pgtables(&tlb
, vma
, prev
? prev
->vm_end
: FIRST_USER_ADDRESS
,
2410 next
? next
->vm_start
: USER_PGTABLES_CEILING
);
2411 tlb_finish_mmu(&tlb
, start
, end
);
2415 * Create a list of vma's touched by the unmap, removing them from the mm's
2416 * vma list as we go..
2419 detach_vmas_to_be_unmapped(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2420 struct vm_area_struct
*prev
, unsigned long end
)
2422 struct vm_area_struct
**insertion_point
;
2423 struct vm_area_struct
*tail_vma
= NULL
;
2425 insertion_point
= (prev
? &prev
->vm_next
: &mm
->mmap
);
2426 vma
->vm_prev
= NULL
;
2428 vma_rb_erase(vma
, &mm
->mm_rb
);
2432 } while (vma
&& vma
->vm_start
< end
);
2433 *insertion_point
= vma
;
2435 vma
->vm_prev
= prev
;
2436 vma_gap_update(vma
);
2438 mm
->highest_vm_end
= prev
? prev
->vm_end
: 0;
2439 tail_vma
->vm_next
= NULL
;
2441 /* Kill the cache */
2442 vmacache_invalidate(mm
);
2446 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2447 * munmap path where it doesn't make sense to fail.
2449 static int __split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2450 unsigned long addr
, int new_below
)
2452 struct vm_area_struct
*new;
2455 if (is_vm_hugetlb_page(vma
) && (addr
&
2456 ~(huge_page_mask(hstate_vma(vma
)))))
2459 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2463 /* most fields are the same, copy all, and then fixup */
2466 INIT_LIST_HEAD(&new->anon_vma_chain
);
2471 new->vm_start
= addr
;
2472 new->vm_pgoff
+= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
);
2475 err
= vma_dup_policy(vma
, new);
2479 err
= anon_vma_clone(new, vma
);
2484 get_file(new->vm_file
);
2486 if (new->vm_ops
&& new->vm_ops
->open
)
2487 new->vm_ops
->open(new);
2490 err
= vma_adjust(vma
, addr
, vma
->vm_end
, vma
->vm_pgoff
+
2491 ((addr
- new->vm_start
) >> PAGE_SHIFT
), new);
2493 err
= vma_adjust(vma
, vma
->vm_start
, addr
, vma
->vm_pgoff
, new);
2499 /* Clean everything up if vma_adjust failed. */
2500 if (new->vm_ops
&& new->vm_ops
->close
)
2501 new->vm_ops
->close(new);
2504 unlink_anon_vmas(new);
2506 mpol_put(vma_policy(new));
2508 kmem_cache_free(vm_area_cachep
, new);
2513 * Split a vma into two pieces at address 'addr', a new vma is allocated
2514 * either for the first part or the tail.
2516 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2517 unsigned long addr
, int new_below
)
2519 if (mm
->map_count
>= sysctl_max_map_count
)
2522 return __split_vma(mm
, vma
, addr
, new_below
);
2525 /* Munmap is split into 2 main parts -- this part which finds
2526 * what needs doing, and the areas themselves, which do the
2527 * work. This now handles partial unmappings.
2528 * Jeremy Fitzhardinge <jeremy@goop.org>
2530 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
)
2533 struct vm_area_struct
*vma
, *prev
, *last
;
2535 if ((offset_in_page(start
)) || start
> TASK_SIZE
|| len
> TASK_SIZE
-start
)
2538 len
= PAGE_ALIGN(len
);
2542 /* Find the first overlapping VMA */
2543 vma
= find_vma(mm
, start
);
2546 prev
= vma
->vm_prev
;
2547 /* we have start < vma->vm_end */
2549 /* if it doesn't overlap, we have nothing.. */
2551 if (vma
->vm_start
>= end
)
2555 * If we need to split any vma, do it now to save pain later.
2557 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2558 * unmapped vm_area_struct will remain in use: so lower split_vma
2559 * places tmp vma above, and higher split_vma places tmp vma below.
2561 if (start
> vma
->vm_start
) {
2565 * Make sure that map_count on return from munmap() will
2566 * not exceed its limit; but let map_count go just above
2567 * its limit temporarily, to help free resources as expected.
2569 if (end
< vma
->vm_end
&& mm
->map_count
>= sysctl_max_map_count
)
2572 error
= __split_vma(mm
, vma
, start
, 0);
2578 /* Does it split the last one? */
2579 last
= find_vma(mm
, end
);
2580 if (last
&& end
> last
->vm_start
) {
2581 int error
= __split_vma(mm
, last
, end
, 1);
2585 vma
= prev
? prev
->vm_next
: mm
->mmap
;
2588 * unlock any mlock()ed ranges before detaching vmas
2590 if (mm
->locked_vm
) {
2591 struct vm_area_struct
*tmp
= vma
;
2592 while (tmp
&& tmp
->vm_start
< end
) {
2593 if (tmp
->vm_flags
& VM_LOCKED
) {
2594 mm
->locked_vm
-= vma_pages(tmp
);
2595 munlock_vma_pages_all(tmp
);
2602 * Remove the vma's, and unmap the actual pages
2604 detach_vmas_to_be_unmapped(mm
, vma
, prev
, end
);
2605 unmap_region(mm
, vma
, prev
, start
, end
);
2607 arch_unmap(mm
, vma
, start
, end
);
2609 /* Fix up all other VM information */
2610 remove_vma_list(mm
, vma
);
2615 int vm_munmap(unsigned long start
, size_t len
)
2618 struct mm_struct
*mm
= current
->mm
;
2620 down_write(&mm
->mmap_sem
);
2621 ret
= do_munmap(mm
, start
, len
);
2622 up_write(&mm
->mmap_sem
);
2625 EXPORT_SYMBOL(vm_munmap
);
2627 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
2629 profile_munmap(addr
);
2630 return vm_munmap(addr
, len
);
2635 * Emulation of deprecated remap_file_pages() syscall.
2637 SYSCALL_DEFINE5(remap_file_pages
, unsigned long, start
, unsigned long, size
,
2638 unsigned long, prot
, unsigned long, pgoff
, unsigned long, flags
)
2641 struct mm_struct
*mm
= current
->mm
;
2642 struct vm_area_struct
*vma
;
2643 unsigned long populate
= 0;
2644 unsigned long ret
= -EINVAL
;
2647 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
2648 "See Documentation/vm/remap_file_pages.txt.\n",
2649 current
->comm
, current
->pid
);
2653 start
= start
& PAGE_MASK
;
2654 size
= size
& PAGE_MASK
;
2656 if (start
+ size
<= start
)
2659 /* Does pgoff wrap? */
2660 if (pgoff
+ (size
>> PAGE_SHIFT
) < pgoff
)
2663 down_write(&mm
->mmap_sem
);
2664 vma
= find_vma(mm
, start
);
2666 if (!vma
|| !(vma
->vm_flags
& VM_SHARED
))
2669 if (start
< vma
->vm_start
|| start
+ size
> vma
->vm_end
)
2672 if (pgoff
== linear_page_index(vma
, start
)) {
2677 prot
|= vma
->vm_flags
& VM_READ
? PROT_READ
: 0;
2678 prot
|= vma
->vm_flags
& VM_WRITE
? PROT_WRITE
: 0;
2679 prot
|= vma
->vm_flags
& VM_EXEC
? PROT_EXEC
: 0;
2681 flags
&= MAP_NONBLOCK
;
2682 flags
|= MAP_SHARED
| MAP_FIXED
| MAP_POPULATE
;
2683 if (vma
->vm_flags
& VM_LOCKED
) {
2684 flags
|= MAP_LOCKED
;
2685 /* drop PG_Mlocked flag for over-mapped range */
2686 munlock_vma_pages_range(vma
, start
, start
+ size
);
2689 file
= get_file(vma
->vm_file
);
2690 ret
= do_mmap_pgoff(vma
->vm_file
, start
, size
,
2691 prot
, flags
, pgoff
, &populate
);
2694 up_write(&mm
->mmap_sem
);
2696 mm_populate(ret
, populate
);
2697 if (!IS_ERR_VALUE(ret
))
2702 static inline void verify_mm_writelocked(struct mm_struct
*mm
)
2704 #ifdef CONFIG_DEBUG_VM
2705 if (unlikely(down_read_trylock(&mm
->mmap_sem
))) {
2707 up_read(&mm
->mmap_sem
);
2713 * this is really a simplified "do_mmap". it only handles
2714 * anonymous maps. eventually we may be able to do some
2715 * brk-specific accounting here.
2717 static unsigned long do_brk(unsigned long addr
, unsigned long len
)
2719 struct mm_struct
*mm
= current
->mm
;
2720 struct vm_area_struct
*vma
, *prev
;
2721 unsigned long flags
;
2722 struct rb_node
**rb_link
, *rb_parent
;
2723 pgoff_t pgoff
= addr
>> PAGE_SHIFT
;
2726 len
= PAGE_ALIGN(len
);
2730 flags
= VM_DATA_DEFAULT_FLAGS
| VM_ACCOUNT
| mm
->def_flags
;
2732 error
= get_unmapped_area(NULL
, addr
, len
, 0, MAP_FIXED
);
2733 if (offset_in_page(error
))
2736 error
= mlock_future_check(mm
, mm
->def_flags
, len
);
2741 * mm->mmap_sem is required to protect against another thread
2742 * changing the mappings in case we sleep.
2744 verify_mm_writelocked(mm
);
2747 * Clear old maps. this also does some error checking for us
2749 while (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
,
2751 if (do_munmap(mm
, addr
, len
))
2755 /* Check against address space limits *after* clearing old maps... */
2756 if (!may_expand_vm(mm
, flags
, len
>> PAGE_SHIFT
))
2759 if (mm
->map_count
> sysctl_max_map_count
)
2762 if (security_vm_enough_memory_mm(mm
, len
>> PAGE_SHIFT
))
2765 /* Can we just expand an old private anonymous mapping? */
2766 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, flags
,
2767 NULL
, NULL
, pgoff
, NULL
, NULL_VM_UFFD_CTX
);
2772 * create a vma struct for an anonymous mapping
2774 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2776 vm_unacct_memory(len
>> PAGE_SHIFT
);
2780 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2782 vma
->vm_start
= addr
;
2783 vma
->vm_end
= addr
+ len
;
2784 vma
->vm_pgoff
= pgoff
;
2785 vma
->vm_flags
= flags
;
2786 vma
->vm_page_prot
= vm_get_page_prot(flags
);
2787 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2789 perf_event_mmap(vma
);
2790 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2791 mm
->data_vm
+= len
>> PAGE_SHIFT
;
2792 if (flags
& VM_LOCKED
)
2793 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
2794 vma
->vm_flags
|= VM_SOFTDIRTY
;
2798 unsigned long vm_brk(unsigned long addr
, unsigned long len
)
2800 struct mm_struct
*mm
= current
->mm
;
2804 down_write(&mm
->mmap_sem
);
2805 ret
= do_brk(addr
, len
);
2806 populate
= ((mm
->def_flags
& VM_LOCKED
) != 0);
2807 up_write(&mm
->mmap_sem
);
2809 mm_populate(addr
, len
);
2812 EXPORT_SYMBOL(vm_brk
);
2814 /* Release all mmaps. */
2815 void exit_mmap(struct mm_struct
*mm
)
2817 struct mmu_gather tlb
;
2818 struct vm_area_struct
*vma
;
2819 unsigned long nr_accounted
= 0;
2821 /* mm's last user has gone, and its about to be pulled down */
2822 mmu_notifier_release(mm
);
2824 if (mm
->locked_vm
) {
2827 if (vma
->vm_flags
& VM_LOCKED
)
2828 munlock_vma_pages_all(vma
);
2836 if (!vma
) /* Can happen if dup_mmap() received an OOM */
2841 tlb_gather_mmu(&tlb
, mm
, 0, -1);
2842 /* update_hiwater_rss(mm) here? but nobody should be looking */
2843 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2844 unmap_vmas(&tlb
, vma
, 0, -1);
2846 free_pgtables(&tlb
, vma
, FIRST_USER_ADDRESS
, USER_PGTABLES_CEILING
);
2847 tlb_finish_mmu(&tlb
, 0, -1);
2850 * Walk the list again, actually closing and freeing it,
2851 * with preemption enabled, without holding any MM locks.
2854 if (vma
->vm_flags
& VM_ACCOUNT
)
2855 nr_accounted
+= vma_pages(vma
);
2856 vma
= remove_vma(vma
);
2858 vm_unacct_memory(nr_accounted
);
2861 /* Insert vm structure into process list sorted by address
2862 * and into the inode's i_mmap tree. If vm_file is non-NULL
2863 * then i_mmap_rwsem is taken here.
2865 int insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
2867 struct vm_area_struct
*prev
;
2868 struct rb_node
**rb_link
, *rb_parent
;
2870 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
2871 &prev
, &rb_link
, &rb_parent
))
2873 if ((vma
->vm_flags
& VM_ACCOUNT
) &&
2874 security_vm_enough_memory_mm(mm
, vma_pages(vma
)))
2878 * The vm_pgoff of a purely anonymous vma should be irrelevant
2879 * until its first write fault, when page's anon_vma and index
2880 * are set. But now set the vm_pgoff it will almost certainly
2881 * end up with (unless mremap moves it elsewhere before that
2882 * first wfault), so /proc/pid/maps tells a consistent story.
2884 * By setting it to reflect the virtual start address of the
2885 * vma, merges and splits can happen in a seamless way, just
2886 * using the existing file pgoff checks and manipulations.
2887 * Similarly in do_mmap_pgoff and in do_brk.
2889 if (vma_is_anonymous(vma
)) {
2890 BUG_ON(vma
->anon_vma
);
2891 vma
->vm_pgoff
= vma
->vm_start
>> PAGE_SHIFT
;
2894 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2899 * Copy the vma structure to a new location in the same mm,
2900 * prior to moving page table entries, to effect an mremap move.
2902 struct vm_area_struct
*copy_vma(struct vm_area_struct
**vmap
,
2903 unsigned long addr
, unsigned long len
, pgoff_t pgoff
,
2904 bool *need_rmap_locks
)
2906 struct vm_area_struct
*vma
= *vmap
;
2907 unsigned long vma_start
= vma
->vm_start
;
2908 struct mm_struct
*mm
= vma
->vm_mm
;
2909 struct vm_area_struct
*new_vma
, *prev
;
2910 struct rb_node
**rb_link
, *rb_parent
;
2911 bool faulted_in_anon_vma
= true;
2914 * If anonymous vma has not yet been faulted, update new pgoff
2915 * to match new location, to increase its chance of merging.
2917 if (unlikely(vma_is_anonymous(vma
) && !vma
->anon_vma
)) {
2918 pgoff
= addr
>> PAGE_SHIFT
;
2919 faulted_in_anon_vma
= false;
2922 if (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
, &rb_parent
))
2923 return NULL
; /* should never get here */
2924 new_vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vma
->vm_flags
,
2925 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
),
2926 vma
->vm_userfaultfd_ctx
);
2929 * Source vma may have been merged into new_vma
2931 if (unlikely(vma_start
>= new_vma
->vm_start
&&
2932 vma_start
< new_vma
->vm_end
)) {
2934 * The only way we can get a vma_merge with
2935 * self during an mremap is if the vma hasn't
2936 * been faulted in yet and we were allowed to
2937 * reset the dst vma->vm_pgoff to the
2938 * destination address of the mremap to allow
2939 * the merge to happen. mremap must change the
2940 * vm_pgoff linearity between src and dst vmas
2941 * (in turn preventing a vma_merge) to be
2942 * safe. It is only safe to keep the vm_pgoff
2943 * linear if there are no pages mapped yet.
2945 VM_BUG_ON_VMA(faulted_in_anon_vma
, new_vma
);
2946 *vmap
= vma
= new_vma
;
2948 *need_rmap_locks
= (new_vma
->vm_pgoff
<= vma
->vm_pgoff
);
2950 new_vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2954 new_vma
->vm_start
= addr
;
2955 new_vma
->vm_end
= addr
+ len
;
2956 new_vma
->vm_pgoff
= pgoff
;
2957 if (vma_dup_policy(vma
, new_vma
))
2959 INIT_LIST_HEAD(&new_vma
->anon_vma_chain
);
2960 if (anon_vma_clone(new_vma
, vma
))
2961 goto out_free_mempol
;
2962 if (new_vma
->vm_file
)
2963 get_file(new_vma
->vm_file
);
2964 if (new_vma
->vm_ops
&& new_vma
->vm_ops
->open
)
2965 new_vma
->vm_ops
->open(new_vma
);
2966 vma_link(mm
, new_vma
, prev
, rb_link
, rb_parent
);
2967 *need_rmap_locks
= false;
2972 mpol_put(vma_policy(new_vma
));
2974 kmem_cache_free(vm_area_cachep
, new_vma
);
2980 * Return true if the calling process may expand its vm space by the passed
2983 bool may_expand_vm(struct mm_struct
*mm
, vm_flags_t flags
, unsigned long npages
)
2985 if (mm
->total_vm
+ npages
> rlimit(RLIMIT_AS
) >> PAGE_SHIFT
)
2988 if (is_data_mapping(flags
) &&
2989 mm
->data_vm
+ npages
> rlimit(RLIMIT_DATA
) >> PAGE_SHIFT
) {
2990 if (ignore_rlimit_data
)
2991 pr_warn_once("%s (%d): VmData %lu exceed data ulimit "
2992 "%lu. Will be forbidden soon.\n",
2993 current
->comm
, current
->pid
,
2994 (mm
->data_vm
+ npages
) << PAGE_SHIFT
,
2995 rlimit(RLIMIT_DATA
));
3003 void vm_stat_account(struct mm_struct
*mm
, vm_flags_t flags
, long npages
)
3005 mm
->total_vm
+= npages
;
3007 if (is_exec_mapping(flags
))
3008 mm
->exec_vm
+= npages
;
3009 else if (is_stack_mapping(flags
))
3010 mm
->stack_vm
+= npages
;
3011 else if (is_data_mapping(flags
))
3012 mm
->data_vm
+= npages
;
3015 static int special_mapping_fault(struct vm_area_struct
*vma
,
3016 struct vm_fault
*vmf
);
3019 * Having a close hook prevents vma merging regardless of flags.
3021 static void special_mapping_close(struct vm_area_struct
*vma
)
3025 static const char *special_mapping_name(struct vm_area_struct
*vma
)
3027 return ((struct vm_special_mapping
*)vma
->vm_private_data
)->name
;
3030 static const struct vm_operations_struct special_mapping_vmops
= {
3031 .close
= special_mapping_close
,
3032 .fault
= special_mapping_fault
,
3033 .name
= special_mapping_name
,
3036 static const struct vm_operations_struct legacy_special_mapping_vmops
= {
3037 .close
= special_mapping_close
,
3038 .fault
= special_mapping_fault
,
3041 static int special_mapping_fault(struct vm_area_struct
*vma
,
3042 struct vm_fault
*vmf
)
3045 struct page
**pages
;
3047 if (vma
->vm_ops
== &legacy_special_mapping_vmops
)
3048 pages
= vma
->vm_private_data
;
3050 pages
= ((struct vm_special_mapping
*)vma
->vm_private_data
)->
3053 for (pgoff
= vmf
->pgoff
; pgoff
&& *pages
; ++pages
)
3057 struct page
*page
= *pages
;
3063 return VM_FAULT_SIGBUS
;
3066 static struct vm_area_struct
*__install_special_mapping(
3067 struct mm_struct
*mm
,
3068 unsigned long addr
, unsigned long len
,
3069 unsigned long vm_flags
, void *priv
,
3070 const struct vm_operations_struct
*ops
)
3073 struct vm_area_struct
*vma
;
3075 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
3076 if (unlikely(vma
== NULL
))
3077 return ERR_PTR(-ENOMEM
);
3079 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
3081 vma
->vm_start
= addr
;
3082 vma
->vm_end
= addr
+ len
;
3084 vma
->vm_flags
= vm_flags
| mm
->def_flags
| VM_DONTEXPAND
| VM_SOFTDIRTY
;
3085 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
3088 vma
->vm_private_data
= priv
;
3090 ret
= insert_vm_struct(mm
, vma
);
3094 vm_stat_account(mm
, vma
->vm_flags
, len
>> PAGE_SHIFT
);
3096 perf_event_mmap(vma
);
3101 kmem_cache_free(vm_area_cachep
, vma
);
3102 return ERR_PTR(ret
);
3106 * Called with mm->mmap_sem held for writing.
3107 * Insert a new vma covering the given region, with the given flags.
3108 * Its pages are supplied by the given array of struct page *.
3109 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3110 * The region past the last page supplied will always produce SIGBUS.
3111 * The array pointer and the pages it points to are assumed to stay alive
3112 * for as long as this mapping might exist.
3114 struct vm_area_struct
*_install_special_mapping(
3115 struct mm_struct
*mm
,
3116 unsigned long addr
, unsigned long len
,
3117 unsigned long vm_flags
, const struct vm_special_mapping
*spec
)
3119 return __install_special_mapping(mm
, addr
, len
, vm_flags
, (void *)spec
,
3120 &special_mapping_vmops
);
3123 int install_special_mapping(struct mm_struct
*mm
,
3124 unsigned long addr
, unsigned long len
,
3125 unsigned long vm_flags
, struct page
**pages
)
3127 struct vm_area_struct
*vma
= __install_special_mapping(
3128 mm
, addr
, len
, vm_flags
, (void *)pages
,
3129 &legacy_special_mapping_vmops
);
3131 return PTR_ERR_OR_ZERO(vma
);
3134 static DEFINE_MUTEX(mm_all_locks_mutex
);
3136 static void vm_lock_anon_vma(struct mm_struct
*mm
, struct anon_vma
*anon_vma
)
3138 if (!test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_node
)) {
3140 * The LSB of head.next can't change from under us
3141 * because we hold the mm_all_locks_mutex.
3143 down_write_nest_lock(&anon_vma
->root
->rwsem
, &mm
->mmap_sem
);
3145 * We can safely modify head.next after taking the
3146 * anon_vma->root->rwsem. If some other vma in this mm shares
3147 * the same anon_vma we won't take it again.
3149 * No need of atomic instructions here, head.next
3150 * can't change from under us thanks to the
3151 * anon_vma->root->rwsem.
3153 if (__test_and_set_bit(0, (unsigned long *)
3154 &anon_vma
->root
->rb_root
.rb_node
))
3159 static void vm_lock_mapping(struct mm_struct
*mm
, struct address_space
*mapping
)
3161 if (!test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3163 * AS_MM_ALL_LOCKS can't change from under us because
3164 * we hold the mm_all_locks_mutex.
3166 * Operations on ->flags have to be atomic because
3167 * even if AS_MM_ALL_LOCKS is stable thanks to the
3168 * mm_all_locks_mutex, there may be other cpus
3169 * changing other bitflags in parallel to us.
3171 if (test_and_set_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
))
3173 down_write_nest_lock(&mapping
->i_mmap_rwsem
, &mm
->mmap_sem
);
3178 * This operation locks against the VM for all pte/vma/mm related
3179 * operations that could ever happen on a certain mm. This includes
3180 * vmtruncate, try_to_unmap, and all page faults.
3182 * The caller must take the mmap_sem in write mode before calling
3183 * mm_take_all_locks(). The caller isn't allowed to release the
3184 * mmap_sem until mm_drop_all_locks() returns.
3186 * mmap_sem in write mode is required in order to block all operations
3187 * that could modify pagetables and free pages without need of
3188 * altering the vma layout. It's also needed in write mode to avoid new
3189 * anon_vmas to be associated with existing vmas.
3191 * A single task can't take more than one mm_take_all_locks() in a row
3192 * or it would deadlock.
3194 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3195 * mapping->flags avoid to take the same lock twice, if more than one
3196 * vma in this mm is backed by the same anon_vma or address_space.
3198 * We take locks in following order, accordingly to comment at beginning
3200 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3202 * - all i_mmap_rwsem locks;
3203 * - all anon_vma->rwseml
3205 * We can take all locks within these types randomly because the VM code
3206 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3207 * mm_all_locks_mutex.
3209 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3210 * that may have to take thousand of locks.
3212 * mm_take_all_locks() can fail if it's interrupted by signals.
3214 int mm_take_all_locks(struct mm_struct
*mm
)
3216 struct vm_area_struct
*vma
;
3217 struct anon_vma_chain
*avc
;
3219 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3221 mutex_lock(&mm_all_locks_mutex
);
3223 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3224 if (signal_pending(current
))
3226 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
3227 is_vm_hugetlb_page(vma
))
3228 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
3231 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3232 if (signal_pending(current
))
3234 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
3235 !is_vm_hugetlb_page(vma
))
3236 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
3239 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3240 if (signal_pending(current
))
3243 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3244 vm_lock_anon_vma(mm
, avc
->anon_vma
);
3250 mm_drop_all_locks(mm
);
3254 static void vm_unlock_anon_vma(struct anon_vma
*anon_vma
)
3256 if (test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_node
)) {
3258 * The LSB of head.next can't change to 0 from under
3259 * us because we hold the mm_all_locks_mutex.
3261 * We must however clear the bitflag before unlocking
3262 * the vma so the users using the anon_vma->rb_root will
3263 * never see our bitflag.
3265 * No need of atomic instructions here, head.next
3266 * can't change from under us until we release the
3267 * anon_vma->root->rwsem.
3269 if (!__test_and_clear_bit(0, (unsigned long *)
3270 &anon_vma
->root
->rb_root
.rb_node
))
3272 anon_vma_unlock_write(anon_vma
);
3276 static void vm_unlock_mapping(struct address_space
*mapping
)
3278 if (test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3280 * AS_MM_ALL_LOCKS can't change to 0 from under us
3281 * because we hold the mm_all_locks_mutex.
3283 i_mmap_unlock_write(mapping
);
3284 if (!test_and_clear_bit(AS_MM_ALL_LOCKS
,
3291 * The mmap_sem cannot be released by the caller until
3292 * mm_drop_all_locks() returns.
3294 void mm_drop_all_locks(struct mm_struct
*mm
)
3296 struct vm_area_struct
*vma
;
3297 struct anon_vma_chain
*avc
;
3299 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3300 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex
));
3302 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3304 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3305 vm_unlock_anon_vma(avc
->anon_vma
);
3306 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
3307 vm_unlock_mapping(vma
->vm_file
->f_mapping
);
3310 mutex_unlock(&mm_all_locks_mutex
);
3314 * initialise the VMA slab
3316 void __init
mmap_init(void)
3320 ret
= percpu_counter_init(&vm_committed_as
, 0, GFP_KERNEL
);
3325 * Initialise sysctl_user_reserve_kbytes.
3327 * This is intended to prevent a user from starting a single memory hogging
3328 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3331 * The default value is min(3% of free memory, 128MB)
3332 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3334 static int init_user_reserve(void)
3336 unsigned long free_kbytes
;
3338 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3340 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
3343 subsys_initcall(init_user_reserve
);
3346 * Initialise sysctl_admin_reserve_kbytes.
3348 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3349 * to log in and kill a memory hogging process.
3351 * Systems with more than 256MB will reserve 8MB, enough to recover
3352 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3353 * only reserve 3% of free pages by default.
3355 static int init_admin_reserve(void)
3357 unsigned long free_kbytes
;
3359 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3361 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
3364 subsys_initcall(init_admin_reserve
);
3367 * Reinititalise user and admin reserves if memory is added or removed.
3369 * The default user reserve max is 128MB, and the default max for the
3370 * admin reserve is 8MB. These are usually, but not always, enough to
3371 * enable recovery from a memory hogging process using login/sshd, a shell,
3372 * and tools like top. It may make sense to increase or even disable the
3373 * reserve depending on the existence of swap or variations in the recovery
3374 * tools. So, the admin may have changed them.
3376 * If memory is added and the reserves have been eliminated or increased above
3377 * the default max, then we'll trust the admin.
3379 * If memory is removed and there isn't enough free memory, then we
3380 * need to reset the reserves.
3382 * Otherwise keep the reserve set by the admin.
3384 static int reserve_mem_notifier(struct notifier_block
*nb
,
3385 unsigned long action
, void *data
)
3387 unsigned long tmp
, free_kbytes
;
3391 /* Default max is 128MB. Leave alone if modified by operator. */
3392 tmp
= sysctl_user_reserve_kbytes
;
3393 if (0 < tmp
&& tmp
< (1UL << 17))
3394 init_user_reserve();
3396 /* Default max is 8MB. Leave alone if modified by operator. */
3397 tmp
= sysctl_admin_reserve_kbytes
;
3398 if (0 < tmp
&& tmp
< (1UL << 13))
3399 init_admin_reserve();
3403 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3405 if (sysctl_user_reserve_kbytes
> free_kbytes
) {
3406 init_user_reserve();
3407 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3408 sysctl_user_reserve_kbytes
);
3411 if (sysctl_admin_reserve_kbytes
> free_kbytes
) {
3412 init_admin_reserve();
3413 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3414 sysctl_admin_reserve_kbytes
);
3423 static struct notifier_block reserve_mem_nb
= {
3424 .notifier_call
= reserve_mem_notifier
,
3427 static int __meminit
init_reserve_notifier(void)
3429 if (register_hotmemory_notifier(&reserve_mem_nb
))
3430 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3434 subsys_initcall(init_reserve_notifier
);