6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/backing-dev.h>
15 #include <linux/vmacache.h>
16 #include <linux/shm.h>
17 #include <linux/mman.h>
18 #include <linux/pagemap.h>
19 #include <linux/swap.h>
20 #include <linux/syscalls.h>
21 #include <linux/capability.h>
22 #include <linux/init.h>
23 #include <linux/file.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/hugetlb.h>
28 #include <linux/shmem_fs.h>
29 #include <linux/profile.h>
30 #include <linux/export.h>
31 #include <linux/mount.h>
32 #include <linux/mempolicy.h>
33 #include <linux/rmap.h>
34 #include <linux/mmu_notifier.h>
35 #include <linux/mmdebug.h>
36 #include <linux/perf_event.h>
37 #include <linux/audit.h>
38 #include <linux/khugepaged.h>
39 #include <linux/uprobes.h>
40 #include <linux/rbtree_augmented.h>
41 #include <linux/notifier.h>
42 #include <linux/memory.h>
43 #include <linux/printk.h>
44 #include <linux/userfaultfd_k.h>
45 #include <linux/moduleparam.h>
46 #include <linux/pkeys.h>
47 #include <linux/oom.h>
49 #include <linux/uaccess.h>
50 #include <asm/cacheflush.h>
52 #include <asm/mmu_context.h>
56 #ifndef arch_mmap_check
57 #define arch_mmap_check(addr, len, flags) (0)
60 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
61 const int mmap_rnd_bits_min
= CONFIG_ARCH_MMAP_RND_BITS_MIN
;
62 const int mmap_rnd_bits_max
= CONFIG_ARCH_MMAP_RND_BITS_MAX
;
63 int mmap_rnd_bits __read_mostly
= CONFIG_ARCH_MMAP_RND_BITS
;
65 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
66 const int mmap_rnd_compat_bits_min
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN
;
67 const int mmap_rnd_compat_bits_max
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX
;
68 int mmap_rnd_compat_bits __read_mostly
= CONFIG_ARCH_MMAP_RND_COMPAT_BITS
;
71 static bool ignore_rlimit_data
;
72 core_param(ignore_rlimit_data
, ignore_rlimit_data
, bool, 0644);
74 static void unmap_region(struct mm_struct
*mm
,
75 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
76 unsigned long start
, unsigned long end
);
78 /* description of effects of mapping type and prot in current implementation.
79 * this is due to the limited x86 page protection hardware. The expected
80 * behavior is in parens:
83 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
84 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
85 * w: (no) no w: (no) no w: (yes) yes w: (no) no
86 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
88 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
89 * w: (no) no w: (no) no w: (copy) copy w: (no) no
90 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
92 * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
98 pgprot_t protection_map
[16] __ro_after_init
= {
99 __P000
, __P001
, __P010
, __P011
, __P100
, __P101
, __P110
, __P111
,
100 __S000
, __S001
, __S010
, __S011
, __S100
, __S101
, __S110
, __S111
103 pgprot_t
vm_get_page_prot(unsigned long vm_flags
)
105 return __pgprot(pgprot_val(protection_map
[vm_flags
&
106 (VM_READ
|VM_WRITE
|VM_EXEC
|VM_SHARED
)]) |
107 pgprot_val(arch_vm_get_page_prot(vm_flags
)));
109 EXPORT_SYMBOL(vm_get_page_prot
);
111 static pgprot_t
vm_pgprot_modify(pgprot_t oldprot
, unsigned long vm_flags
)
113 return pgprot_modify(oldprot
, vm_get_page_prot(vm_flags
));
116 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
117 void vma_set_page_prot(struct vm_area_struct
*vma
)
119 unsigned long vm_flags
= vma
->vm_flags
;
120 pgprot_t vm_page_prot
;
122 vm_page_prot
= vm_pgprot_modify(vma
->vm_page_prot
, vm_flags
);
123 if (vma_wants_writenotify(vma
, vm_page_prot
)) {
124 vm_flags
&= ~VM_SHARED
;
125 vm_page_prot
= vm_pgprot_modify(vm_page_prot
, vm_flags
);
127 /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
128 WRITE_ONCE(vma
->vm_page_prot
, vm_page_prot
);
132 * Requires inode->i_mapping->i_mmap_rwsem
134 static void __remove_shared_vm_struct(struct vm_area_struct
*vma
,
135 struct file
*file
, struct address_space
*mapping
)
137 if (vma
->vm_flags
& VM_DENYWRITE
)
138 atomic_inc(&file_inode(file
)->i_writecount
);
139 if (vma
->vm_flags
& VM_SHARED
)
140 mapping_unmap_writable(mapping
);
142 flush_dcache_mmap_lock(mapping
);
143 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
144 flush_dcache_mmap_unlock(mapping
);
148 * Unlink a file-based vm structure from its interval tree, to hide
149 * vma from rmap and vmtruncate before freeing its page tables.
151 void unlink_file_vma(struct vm_area_struct
*vma
)
153 struct file
*file
= vma
->vm_file
;
156 struct address_space
*mapping
= file
->f_mapping
;
157 i_mmap_lock_write(mapping
);
158 __remove_shared_vm_struct(vma
, file
, mapping
);
159 i_mmap_unlock_write(mapping
);
164 * Close a vm structure and free it, returning the next.
166 static struct vm_area_struct
*remove_vma(struct vm_area_struct
*vma
)
168 struct vm_area_struct
*next
= vma
->vm_next
;
171 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
172 vma
->vm_ops
->close(vma
);
175 mpol_put(vma_policy(vma
));
176 kmem_cache_free(vm_area_cachep
, vma
);
180 static int do_brk(unsigned long addr
, unsigned long len
, struct list_head
*uf
);
182 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
184 unsigned long retval
;
185 unsigned long newbrk
, oldbrk
;
186 struct mm_struct
*mm
= current
->mm
;
187 struct vm_area_struct
*next
;
188 unsigned long min_brk
;
192 if (down_write_killable(&mm
->mmap_sem
))
195 #ifdef CONFIG_COMPAT_BRK
197 * CONFIG_COMPAT_BRK can still be overridden by setting
198 * randomize_va_space to 2, which will still cause mm->start_brk
199 * to be arbitrarily shifted
201 if (current
->brk_randomized
)
202 min_brk
= mm
->start_brk
;
204 min_brk
= mm
->end_data
;
206 min_brk
= mm
->start_brk
;
212 * Check against rlimit here. If this check is done later after the test
213 * of oldbrk with newbrk then it can escape the test and let the data
214 * segment grow beyond its set limit the in case where the limit is
215 * not page aligned -Ram Gupta
217 if (check_data_rlimit(rlimit(RLIMIT_DATA
), brk
, mm
->start_brk
,
218 mm
->end_data
, mm
->start_data
))
221 newbrk
= PAGE_ALIGN(brk
);
222 oldbrk
= PAGE_ALIGN(mm
->brk
);
223 if (oldbrk
== newbrk
)
226 /* Always allow shrinking brk. */
227 if (brk
<= mm
->brk
) {
228 if (!do_munmap(mm
, newbrk
, oldbrk
-newbrk
, &uf
))
233 /* Check against existing mmap mappings. */
234 next
= find_vma(mm
, oldbrk
);
235 if (next
&& newbrk
+ PAGE_SIZE
> vm_start_gap(next
))
238 /* Ok, looks good - let it rip. */
239 if (do_brk(oldbrk
, newbrk
-oldbrk
, &uf
) < 0)
244 populate
= newbrk
> oldbrk
&& (mm
->def_flags
& VM_LOCKED
) != 0;
245 up_write(&mm
->mmap_sem
);
246 userfaultfd_unmap_complete(mm
, &uf
);
248 mm_populate(oldbrk
, newbrk
- oldbrk
);
253 up_write(&mm
->mmap_sem
);
257 static long vma_compute_subtree_gap(struct vm_area_struct
*vma
)
259 unsigned long max
, prev_end
, subtree_gap
;
262 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
263 * allow two stack_guard_gaps between them here, and when choosing
264 * an unmapped area; whereas when expanding we only require one.
265 * That's a little inconsistent, but keeps the code here simpler.
267 max
= vm_start_gap(vma
);
269 prev_end
= vm_end_gap(vma
->vm_prev
);
275 if (vma
->vm_rb
.rb_left
) {
276 subtree_gap
= rb_entry(vma
->vm_rb
.rb_left
,
277 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
278 if (subtree_gap
> max
)
281 if (vma
->vm_rb
.rb_right
) {
282 subtree_gap
= rb_entry(vma
->vm_rb
.rb_right
,
283 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
284 if (subtree_gap
> max
)
290 #ifdef CONFIG_DEBUG_VM_RB
291 static int browse_rb(struct mm_struct
*mm
)
293 struct rb_root
*root
= &mm
->mm_rb
;
294 int i
= 0, j
, bug
= 0;
295 struct rb_node
*nd
, *pn
= NULL
;
296 unsigned long prev
= 0, pend
= 0;
298 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
299 struct vm_area_struct
*vma
;
300 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
301 if (vma
->vm_start
< prev
) {
302 pr_emerg("vm_start %lx < prev %lx\n",
303 vma
->vm_start
, prev
);
306 if (vma
->vm_start
< pend
) {
307 pr_emerg("vm_start %lx < pend %lx\n",
308 vma
->vm_start
, pend
);
311 if (vma
->vm_start
> vma
->vm_end
) {
312 pr_emerg("vm_start %lx > vm_end %lx\n",
313 vma
->vm_start
, vma
->vm_end
);
316 spin_lock(&mm
->page_table_lock
);
317 if (vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
)) {
318 pr_emerg("free gap %lx, correct %lx\n",
320 vma_compute_subtree_gap(vma
));
323 spin_unlock(&mm
->page_table_lock
);
326 prev
= vma
->vm_start
;
330 for (nd
= pn
; nd
; nd
= rb_prev(nd
))
333 pr_emerg("backwards %d, forwards %d\n", j
, i
);
339 static void validate_mm_rb(struct rb_root
*root
, struct vm_area_struct
*ignore
)
343 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
344 struct vm_area_struct
*vma
;
345 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
346 VM_BUG_ON_VMA(vma
!= ignore
&&
347 vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
),
352 static void validate_mm(struct mm_struct
*mm
)
356 unsigned long highest_address
= 0;
357 struct vm_area_struct
*vma
= mm
->mmap
;
360 struct anon_vma
*anon_vma
= vma
->anon_vma
;
361 struct anon_vma_chain
*avc
;
364 anon_vma_lock_read(anon_vma
);
365 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
366 anon_vma_interval_tree_verify(avc
);
367 anon_vma_unlock_read(anon_vma
);
370 highest_address
= vm_end_gap(vma
);
374 if (i
!= mm
->map_count
) {
375 pr_emerg("map_count %d vm_next %d\n", mm
->map_count
, i
);
378 if (highest_address
!= mm
->highest_vm_end
) {
379 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
380 mm
->highest_vm_end
, highest_address
);
384 if (i
!= mm
->map_count
) {
386 pr_emerg("map_count %d rb %d\n", mm
->map_count
, i
);
389 VM_BUG_ON_MM(bug
, mm
);
392 #define validate_mm_rb(root, ignore) do { } while (0)
393 #define validate_mm(mm) do { } while (0)
396 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks
, struct vm_area_struct
, vm_rb
,
397 unsigned long, rb_subtree_gap
, vma_compute_subtree_gap
)
400 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
401 * vma->vm_prev->vm_end values changed, without modifying the vma's position
404 static void vma_gap_update(struct vm_area_struct
*vma
)
407 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
408 * function that does exacltly what we want.
410 vma_gap_callbacks_propagate(&vma
->vm_rb
, NULL
);
413 static inline void vma_rb_insert(struct vm_area_struct
*vma
,
414 struct rb_root
*root
)
416 /* All rb_subtree_gap values must be consistent prior to insertion */
417 validate_mm_rb(root
, NULL
);
419 rb_insert_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
422 static void __vma_rb_erase(struct vm_area_struct
*vma
, struct rb_root
*root
)
425 * Note rb_erase_augmented is a fairly large inline function,
426 * so make sure we instantiate it only once with our desired
427 * augmented rbtree callbacks.
429 rb_erase_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
432 static __always_inline
void vma_rb_erase_ignore(struct vm_area_struct
*vma
,
433 struct rb_root
*root
,
434 struct vm_area_struct
*ignore
)
437 * All rb_subtree_gap values must be consistent prior to erase,
438 * with the possible exception of the "next" vma being erased if
439 * next->vm_start was reduced.
441 validate_mm_rb(root
, ignore
);
443 __vma_rb_erase(vma
, root
);
446 static __always_inline
void vma_rb_erase(struct vm_area_struct
*vma
,
447 struct rb_root
*root
)
450 * All rb_subtree_gap values must be consistent prior to erase,
451 * with the possible exception of the vma being erased.
453 validate_mm_rb(root
, vma
);
455 __vma_rb_erase(vma
, root
);
459 * vma has some anon_vma assigned, and is already inserted on that
460 * anon_vma's interval trees.
462 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
463 * vma must be removed from the anon_vma's interval trees using
464 * anon_vma_interval_tree_pre_update_vma().
466 * After the update, the vma will be reinserted using
467 * anon_vma_interval_tree_post_update_vma().
469 * The entire update must be protected by exclusive mmap_sem and by
470 * the root anon_vma's mutex.
473 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct
*vma
)
475 struct anon_vma_chain
*avc
;
477 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
478 anon_vma_interval_tree_remove(avc
, &avc
->anon_vma
->rb_root
);
482 anon_vma_interval_tree_post_update_vma(struct vm_area_struct
*vma
)
484 struct anon_vma_chain
*avc
;
486 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
487 anon_vma_interval_tree_insert(avc
, &avc
->anon_vma
->rb_root
);
490 static int find_vma_links(struct mm_struct
*mm
, unsigned long addr
,
491 unsigned long end
, struct vm_area_struct
**pprev
,
492 struct rb_node
***rb_link
, struct rb_node
**rb_parent
)
494 struct rb_node
**__rb_link
, *__rb_parent
, *rb_prev
;
496 __rb_link
= &mm
->mm_rb
.rb_node
;
497 rb_prev
= __rb_parent
= NULL
;
500 struct vm_area_struct
*vma_tmp
;
502 __rb_parent
= *__rb_link
;
503 vma_tmp
= rb_entry(__rb_parent
, struct vm_area_struct
, vm_rb
);
505 if (vma_tmp
->vm_end
> addr
) {
506 /* Fail if an existing vma overlaps the area */
507 if (vma_tmp
->vm_start
< end
)
509 __rb_link
= &__rb_parent
->rb_left
;
511 rb_prev
= __rb_parent
;
512 __rb_link
= &__rb_parent
->rb_right
;
518 *pprev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
519 *rb_link
= __rb_link
;
520 *rb_parent
= __rb_parent
;
524 static unsigned long count_vma_pages_range(struct mm_struct
*mm
,
525 unsigned long addr
, unsigned long end
)
527 unsigned long nr_pages
= 0;
528 struct vm_area_struct
*vma
;
530 /* Find first overlaping mapping */
531 vma
= find_vma_intersection(mm
, addr
, end
);
535 nr_pages
= (min(end
, vma
->vm_end
) -
536 max(addr
, vma
->vm_start
)) >> PAGE_SHIFT
;
538 /* Iterate over the rest of the overlaps */
539 for (vma
= vma
->vm_next
; vma
; vma
= vma
->vm_next
) {
540 unsigned long overlap_len
;
542 if (vma
->vm_start
> end
)
545 overlap_len
= min(end
, vma
->vm_end
) - vma
->vm_start
;
546 nr_pages
+= overlap_len
>> PAGE_SHIFT
;
552 void __vma_link_rb(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
553 struct rb_node
**rb_link
, struct rb_node
*rb_parent
)
555 /* Update tracking information for the gap following the new vma. */
557 vma_gap_update(vma
->vm_next
);
559 mm
->highest_vm_end
= vm_end_gap(vma
);
562 * vma->vm_prev wasn't known when we followed the rbtree to find the
563 * correct insertion point for that vma. As a result, we could not
564 * update the vma vm_rb parents rb_subtree_gap values on the way down.
565 * So, we first insert the vma with a zero rb_subtree_gap value
566 * (to be consistent with what we did on the way down), and then
567 * immediately update the gap to the correct value. Finally we
568 * rebalance the rbtree after all augmented values have been set.
570 rb_link_node(&vma
->vm_rb
, rb_parent
, rb_link
);
571 vma
->rb_subtree_gap
= 0;
573 vma_rb_insert(vma
, &mm
->mm_rb
);
576 static void __vma_link_file(struct vm_area_struct
*vma
)
582 struct address_space
*mapping
= file
->f_mapping
;
584 if (vma
->vm_flags
& VM_DENYWRITE
)
585 atomic_dec(&file_inode(file
)->i_writecount
);
586 if (vma
->vm_flags
& VM_SHARED
)
587 atomic_inc(&mapping
->i_mmap_writable
);
589 flush_dcache_mmap_lock(mapping
);
590 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
591 flush_dcache_mmap_unlock(mapping
);
596 __vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
597 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
598 struct rb_node
*rb_parent
)
600 __vma_link_list(mm
, vma
, prev
, rb_parent
);
601 __vma_link_rb(mm
, vma
, rb_link
, rb_parent
);
604 static void vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
605 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
606 struct rb_node
*rb_parent
)
608 struct address_space
*mapping
= NULL
;
611 mapping
= vma
->vm_file
->f_mapping
;
612 i_mmap_lock_write(mapping
);
615 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
616 __vma_link_file(vma
);
619 i_mmap_unlock_write(mapping
);
626 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
627 * mm's list and rbtree. It has already been inserted into the interval tree.
629 static void __insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
631 struct vm_area_struct
*prev
;
632 struct rb_node
**rb_link
, *rb_parent
;
634 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
635 &prev
, &rb_link
, &rb_parent
))
637 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
641 static __always_inline
void __vma_unlink_common(struct mm_struct
*mm
,
642 struct vm_area_struct
*vma
,
643 struct vm_area_struct
*prev
,
645 struct vm_area_struct
*ignore
)
647 struct vm_area_struct
*next
;
649 vma_rb_erase_ignore(vma
, &mm
->mm_rb
, ignore
);
652 prev
->vm_next
= next
;
656 prev
->vm_next
= next
;
661 next
->vm_prev
= prev
;
664 vmacache_invalidate(mm
);
667 static inline void __vma_unlink_prev(struct mm_struct
*mm
,
668 struct vm_area_struct
*vma
,
669 struct vm_area_struct
*prev
)
671 __vma_unlink_common(mm
, vma
, prev
, true, vma
);
675 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
676 * is already present in an i_mmap tree without adjusting the tree.
677 * The following helper function should be used when such adjustments
678 * are necessary. The "insert" vma (if any) is to be inserted
679 * before we drop the necessary locks.
681 int __vma_adjust(struct vm_area_struct
*vma
, unsigned long start
,
682 unsigned long end
, pgoff_t pgoff
, struct vm_area_struct
*insert
,
683 struct vm_area_struct
*expand
)
685 struct mm_struct
*mm
= vma
->vm_mm
;
686 struct vm_area_struct
*next
= vma
->vm_next
, *orig_vma
= vma
;
687 struct address_space
*mapping
= NULL
;
688 struct rb_root_cached
*root
= NULL
;
689 struct anon_vma
*anon_vma
= NULL
;
690 struct file
*file
= vma
->vm_file
;
691 bool start_changed
= false, end_changed
= false;
692 long adjust_next
= 0;
695 if (next
&& !insert
) {
696 struct vm_area_struct
*exporter
= NULL
, *importer
= NULL
;
698 if (end
>= next
->vm_end
) {
700 * vma expands, overlapping all the next, and
701 * perhaps the one after too (mprotect case 6).
702 * The only other cases that gets here are
703 * case 1, case 7 and case 8.
705 if (next
== expand
) {
707 * The only case where we don't expand "vma"
708 * and we expand "next" instead is case 8.
710 VM_WARN_ON(end
!= next
->vm_end
);
712 * remove_next == 3 means we're
713 * removing "vma" and that to do so we
714 * swapped "vma" and "next".
717 VM_WARN_ON(file
!= next
->vm_file
);
720 VM_WARN_ON(expand
!= vma
);
722 * case 1, 6, 7, remove_next == 2 is case 6,
723 * remove_next == 1 is case 1 or 7.
725 remove_next
= 1 + (end
> next
->vm_end
);
726 VM_WARN_ON(remove_next
== 2 &&
727 end
!= next
->vm_next
->vm_end
);
728 VM_WARN_ON(remove_next
== 1 &&
729 end
!= next
->vm_end
);
730 /* trim end to next, for case 6 first pass */
738 * If next doesn't have anon_vma, import from vma after
739 * next, if the vma overlaps with it.
741 if (remove_next
== 2 && !next
->anon_vma
)
742 exporter
= next
->vm_next
;
744 } else if (end
> next
->vm_start
) {
746 * vma expands, overlapping part of the next:
747 * mprotect case 5 shifting the boundary up.
749 adjust_next
= (end
- next
->vm_start
) >> PAGE_SHIFT
;
752 VM_WARN_ON(expand
!= importer
);
753 } else if (end
< vma
->vm_end
) {
755 * vma shrinks, and !insert tells it's not
756 * split_vma inserting another: so it must be
757 * mprotect case 4 shifting the boundary down.
759 adjust_next
= -((vma
->vm_end
- end
) >> PAGE_SHIFT
);
762 VM_WARN_ON(expand
!= importer
);
766 * Easily overlooked: when mprotect shifts the boundary,
767 * make sure the expanding vma has anon_vma set if the
768 * shrinking vma had, to cover any anon pages imported.
770 if (exporter
&& exporter
->anon_vma
&& !importer
->anon_vma
) {
773 importer
->anon_vma
= exporter
->anon_vma
;
774 error
= anon_vma_clone(importer
, exporter
);
780 vma_adjust_trans_huge(orig_vma
, start
, end
, adjust_next
);
783 mapping
= file
->f_mapping
;
784 root
= &mapping
->i_mmap
;
785 uprobe_munmap(vma
, vma
->vm_start
, vma
->vm_end
);
788 uprobe_munmap(next
, next
->vm_start
, next
->vm_end
);
790 i_mmap_lock_write(mapping
);
793 * Put into interval tree now, so instantiated pages
794 * are visible to arm/parisc __flush_dcache_page
795 * throughout; but we cannot insert into address
796 * space until vma start or end is updated.
798 __vma_link_file(insert
);
802 anon_vma
= vma
->anon_vma
;
803 if (!anon_vma
&& adjust_next
)
804 anon_vma
= next
->anon_vma
;
806 VM_WARN_ON(adjust_next
&& next
->anon_vma
&&
807 anon_vma
!= next
->anon_vma
);
808 anon_vma_lock_write(anon_vma
);
809 anon_vma_interval_tree_pre_update_vma(vma
);
811 anon_vma_interval_tree_pre_update_vma(next
);
815 flush_dcache_mmap_lock(mapping
);
816 vma_interval_tree_remove(vma
, root
);
818 vma_interval_tree_remove(next
, root
);
821 if (start
!= vma
->vm_start
) {
822 vma
->vm_start
= start
;
823 start_changed
= true;
825 if (end
!= vma
->vm_end
) {
829 vma
->vm_pgoff
= pgoff
;
831 next
->vm_start
+= adjust_next
<< PAGE_SHIFT
;
832 next
->vm_pgoff
+= adjust_next
;
837 vma_interval_tree_insert(next
, root
);
838 vma_interval_tree_insert(vma
, root
);
839 flush_dcache_mmap_unlock(mapping
);
844 * vma_merge has merged next into vma, and needs
845 * us to remove next before dropping the locks.
847 if (remove_next
!= 3)
848 __vma_unlink_prev(mm
, next
, vma
);
851 * vma is not before next if they've been
854 * pre-swap() next->vm_start was reduced so
855 * tell validate_mm_rb to ignore pre-swap()
856 * "next" (which is stored in post-swap()
859 __vma_unlink_common(mm
, next
, NULL
, false, vma
);
861 __remove_shared_vm_struct(next
, file
, mapping
);
864 * split_vma has split insert from vma, and needs
865 * us to insert it before dropping the locks
866 * (it may either follow vma or precede it).
868 __insert_vm_struct(mm
, insert
);
874 mm
->highest_vm_end
= vm_end_gap(vma
);
875 else if (!adjust_next
)
876 vma_gap_update(next
);
881 anon_vma_interval_tree_post_update_vma(vma
);
883 anon_vma_interval_tree_post_update_vma(next
);
884 anon_vma_unlock_write(anon_vma
);
887 i_mmap_unlock_write(mapping
);
898 uprobe_munmap(next
, next
->vm_start
, next
->vm_end
);
902 anon_vma_merge(vma
, next
);
904 mpol_put(vma_policy(next
));
905 kmem_cache_free(vm_area_cachep
, next
);
907 * In mprotect's case 6 (see comments on vma_merge),
908 * we must remove another next too. It would clutter
909 * up the code too much to do both in one go.
911 if (remove_next
!= 3) {
913 * If "next" was removed and vma->vm_end was
914 * expanded (up) over it, in turn
915 * "next->vm_prev->vm_end" changed and the
916 * "vma->vm_next" gap must be updated.
921 * For the scope of the comment "next" and
922 * "vma" considered pre-swap(): if "vma" was
923 * removed, next->vm_start was expanded (down)
924 * over it and the "next" gap must be updated.
925 * Because of the swap() the post-swap() "vma"
926 * actually points to pre-swap() "next"
927 * (post-swap() "next" as opposed is now a
932 if (remove_next
== 2) {
938 vma_gap_update(next
);
941 * If remove_next == 2 we obviously can't
944 * If remove_next == 3 we can't reach this
945 * path because pre-swap() next is always not
946 * NULL. pre-swap() "next" is not being
947 * removed and its next->vm_end is not altered
948 * (and furthermore "end" already matches
949 * next->vm_end in remove_next == 3).
951 * We reach this only in the remove_next == 1
952 * case if the "next" vma that was removed was
953 * the highest vma of the mm. However in such
954 * case next->vm_end == "end" and the extended
955 * "vma" has vma->vm_end == next->vm_end so
956 * mm->highest_vm_end doesn't need any update
957 * in remove_next == 1 case.
959 VM_WARN_ON(mm
->highest_vm_end
!= vm_end_gap(vma
));
971 * If the vma has a ->close operation then the driver probably needs to release
972 * per-vma resources, so we don't attempt to merge those.
974 static inline int is_mergeable_vma(struct vm_area_struct
*vma
,
975 struct file
*file
, unsigned long vm_flags
,
976 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
979 * VM_SOFTDIRTY should not prevent from VMA merging, if we
980 * match the flags but dirty bit -- the caller should mark
981 * merged VMA as dirty. If dirty bit won't be excluded from
982 * comparison, we increase pressue on the memory system forcing
983 * the kernel to generate new VMAs when old one could be
986 if ((vma
->vm_flags
^ vm_flags
) & ~VM_SOFTDIRTY
)
988 if (vma
->vm_file
!= file
)
990 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
992 if (!is_mergeable_vm_userfaultfd_ctx(vma
, vm_userfaultfd_ctx
))
997 static inline int is_mergeable_anon_vma(struct anon_vma
*anon_vma1
,
998 struct anon_vma
*anon_vma2
,
999 struct vm_area_struct
*vma
)
1002 * The list_is_singular() test is to avoid merging VMA cloned from
1003 * parents. This can improve scalability caused by anon_vma lock.
1005 if ((!anon_vma1
|| !anon_vma2
) && (!vma
||
1006 list_is_singular(&vma
->anon_vma_chain
)))
1008 return anon_vma1
== anon_vma2
;
1012 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1013 * in front of (at a lower virtual address and file offset than) the vma.
1015 * We cannot merge two vmas if they have differently assigned (non-NULL)
1016 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1018 * We don't check here for the merged mmap wrapping around the end of pagecache
1019 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
1020 * wrap, nor mmaps which cover the final page at index -1UL.
1023 can_vma_merge_before(struct vm_area_struct
*vma
, unsigned long vm_flags
,
1024 struct anon_vma
*anon_vma
, struct file
*file
,
1026 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
1028 if (is_mergeable_vma(vma
, file
, vm_flags
, vm_userfaultfd_ctx
) &&
1029 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
1030 if (vma
->vm_pgoff
== vm_pgoff
)
1037 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1038 * beyond (at a higher virtual address and file offset than) the vma.
1040 * We cannot merge two vmas if they have differently assigned (non-NULL)
1041 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1044 can_vma_merge_after(struct vm_area_struct
*vma
, unsigned long vm_flags
,
1045 struct anon_vma
*anon_vma
, struct file
*file
,
1047 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
1049 if (is_mergeable_vma(vma
, file
, vm_flags
, vm_userfaultfd_ctx
) &&
1050 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
1052 vm_pglen
= vma_pages(vma
);
1053 if (vma
->vm_pgoff
+ vm_pglen
== vm_pgoff
)
1060 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1061 * whether that can be merged with its predecessor or its successor.
1062 * Or both (it neatly fills a hole).
1064 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1065 * certain not to be mapped by the time vma_merge is called; but when
1066 * called for mprotect, it is certain to be already mapped (either at
1067 * an offset within prev, or at the start of next), and the flags of
1068 * this area are about to be changed to vm_flags - and the no-change
1069 * case has already been eliminated.
1071 * The following mprotect cases have to be considered, where AAAA is
1072 * the area passed down from mprotect_fixup, never extending beyond one
1073 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1075 * AAAA AAAA AAAA AAAA
1076 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1077 * cannot merge might become might become might become
1078 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1079 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1080 * mremap move: PPPPXXXXXXXX 8
1082 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1083 * might become case 1 below case 2 below case 3 below
1085 * It is important for case 8 that the the vma NNNN overlapping the
1086 * region AAAA is never going to extended over XXXX. Instead XXXX must
1087 * be extended in region AAAA and NNNN must be removed. This way in
1088 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1089 * rmap_locks, the properties of the merged vma will be already
1090 * correct for the whole merged range. Some of those properties like
1091 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1092 * be correct for the whole merged range immediately after the
1093 * rmap_locks are released. Otherwise if XXXX would be removed and
1094 * NNNN would be extended over the XXXX range, remove_migration_ptes
1095 * or other rmap walkers (if working on addresses beyond the "end"
1096 * parameter) may establish ptes with the wrong permissions of NNNN
1097 * instead of the right permissions of XXXX.
1099 struct vm_area_struct
*vma_merge(struct mm_struct
*mm
,
1100 struct vm_area_struct
*prev
, unsigned long addr
,
1101 unsigned long end
, unsigned long vm_flags
,
1102 struct anon_vma
*anon_vma
, struct file
*file
,
1103 pgoff_t pgoff
, struct mempolicy
*policy
,
1104 struct vm_userfaultfd_ctx vm_userfaultfd_ctx
)
1106 pgoff_t pglen
= (end
- addr
) >> PAGE_SHIFT
;
1107 struct vm_area_struct
*area
, *next
;
1111 * We later require that vma->vm_flags == vm_flags,
1112 * so this tests vma->vm_flags & VM_SPECIAL, too.
1114 if (vm_flags
& VM_SPECIAL
)
1118 next
= prev
->vm_next
;
1122 if (area
&& area
->vm_end
== end
) /* cases 6, 7, 8 */
1123 next
= next
->vm_next
;
1125 /* verify some invariant that must be enforced by the caller */
1126 VM_WARN_ON(prev
&& addr
<= prev
->vm_start
);
1127 VM_WARN_ON(area
&& end
> area
->vm_end
);
1128 VM_WARN_ON(addr
>= end
);
1131 * Can it merge with the predecessor?
1133 if (prev
&& prev
->vm_end
== addr
&&
1134 mpol_equal(vma_policy(prev
), policy
) &&
1135 can_vma_merge_after(prev
, vm_flags
,
1136 anon_vma
, file
, pgoff
,
1137 vm_userfaultfd_ctx
)) {
1139 * OK, it can. Can we now merge in the successor as well?
1141 if (next
&& end
== next
->vm_start
&&
1142 mpol_equal(policy
, vma_policy(next
)) &&
1143 can_vma_merge_before(next
, vm_flags
,
1146 vm_userfaultfd_ctx
) &&
1147 is_mergeable_anon_vma(prev
->anon_vma
,
1148 next
->anon_vma
, NULL
)) {
1150 err
= __vma_adjust(prev
, prev
->vm_start
,
1151 next
->vm_end
, prev
->vm_pgoff
, NULL
,
1153 } else /* cases 2, 5, 7 */
1154 err
= __vma_adjust(prev
, prev
->vm_start
,
1155 end
, prev
->vm_pgoff
, NULL
, prev
);
1158 khugepaged_enter_vma_merge(prev
, vm_flags
);
1163 * Can this new request be merged in front of next?
1165 if (next
&& end
== next
->vm_start
&&
1166 mpol_equal(policy
, vma_policy(next
)) &&
1167 can_vma_merge_before(next
, vm_flags
,
1168 anon_vma
, file
, pgoff
+pglen
,
1169 vm_userfaultfd_ctx
)) {
1170 if (prev
&& addr
< prev
->vm_end
) /* case 4 */
1171 err
= __vma_adjust(prev
, prev
->vm_start
,
1172 addr
, prev
->vm_pgoff
, NULL
, next
);
1173 else { /* cases 3, 8 */
1174 err
= __vma_adjust(area
, addr
, next
->vm_end
,
1175 next
->vm_pgoff
- pglen
, NULL
, next
);
1177 * In case 3 area is already equal to next and
1178 * this is a noop, but in case 8 "area" has
1179 * been removed and next was expanded over it.
1185 khugepaged_enter_vma_merge(area
, vm_flags
);
1193 * Rough compatbility check to quickly see if it's even worth looking
1194 * at sharing an anon_vma.
1196 * They need to have the same vm_file, and the flags can only differ
1197 * in things that mprotect may change.
1199 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1200 * we can merge the two vma's. For example, we refuse to merge a vma if
1201 * there is a vm_ops->close() function, because that indicates that the
1202 * driver is doing some kind of reference counting. But that doesn't
1203 * really matter for the anon_vma sharing case.
1205 static int anon_vma_compatible(struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1207 return a
->vm_end
== b
->vm_start
&&
1208 mpol_equal(vma_policy(a
), vma_policy(b
)) &&
1209 a
->vm_file
== b
->vm_file
&&
1210 !((a
->vm_flags
^ b
->vm_flags
) & ~(VM_READ
|VM_WRITE
|VM_EXEC
|VM_SOFTDIRTY
)) &&
1211 b
->vm_pgoff
== a
->vm_pgoff
+ ((b
->vm_start
- a
->vm_start
) >> PAGE_SHIFT
);
1215 * Do some basic sanity checking to see if we can re-use the anon_vma
1216 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1217 * the same as 'old', the other will be the new one that is trying
1218 * to share the anon_vma.
1220 * NOTE! This runs with mm_sem held for reading, so it is possible that
1221 * the anon_vma of 'old' is concurrently in the process of being set up
1222 * by another page fault trying to merge _that_. But that's ok: if it
1223 * is being set up, that automatically means that it will be a singleton
1224 * acceptable for merging, so we can do all of this optimistically. But
1225 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1227 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1228 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1229 * is to return an anon_vma that is "complex" due to having gone through
1232 * We also make sure that the two vma's are compatible (adjacent,
1233 * and with the same memory policies). That's all stable, even with just
1234 * a read lock on the mm_sem.
1236 static struct anon_vma
*reusable_anon_vma(struct vm_area_struct
*old
, struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1238 if (anon_vma_compatible(a
, b
)) {
1239 struct anon_vma
*anon_vma
= READ_ONCE(old
->anon_vma
);
1241 if (anon_vma
&& list_is_singular(&old
->anon_vma_chain
))
1248 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1249 * neighbouring vmas for a suitable anon_vma, before it goes off
1250 * to allocate a new anon_vma. It checks because a repetitive
1251 * sequence of mprotects and faults may otherwise lead to distinct
1252 * anon_vmas being allocated, preventing vma merge in subsequent
1255 struct anon_vma
*find_mergeable_anon_vma(struct vm_area_struct
*vma
)
1257 struct anon_vma
*anon_vma
;
1258 struct vm_area_struct
*near
;
1260 near
= vma
->vm_next
;
1264 anon_vma
= reusable_anon_vma(near
, vma
, near
);
1268 near
= vma
->vm_prev
;
1272 anon_vma
= reusable_anon_vma(near
, near
, vma
);
1277 * There's no absolute need to look only at touching neighbours:
1278 * we could search further afield for "compatible" anon_vmas.
1279 * But it would probably just be a waste of time searching,
1280 * or lead to too many vmas hanging off the same anon_vma.
1281 * We're trying to allow mprotect remerging later on,
1282 * not trying to minimize memory used for anon_vmas.
1288 * If a hint addr is less than mmap_min_addr change hint to be as
1289 * low as possible but still greater than mmap_min_addr
1291 static inline unsigned long round_hint_to_min(unsigned long hint
)
1294 if (((void *)hint
!= NULL
) &&
1295 (hint
< mmap_min_addr
))
1296 return PAGE_ALIGN(mmap_min_addr
);
1300 static inline int mlock_future_check(struct mm_struct
*mm
,
1301 unsigned long flags
,
1304 unsigned long locked
, lock_limit
;
1306 /* mlock MCL_FUTURE? */
1307 if (flags
& VM_LOCKED
) {
1308 locked
= len
>> PAGE_SHIFT
;
1309 locked
+= mm
->locked_vm
;
1310 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
1311 lock_limit
>>= PAGE_SHIFT
;
1312 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
1319 * The caller must hold down_write(¤t->mm->mmap_sem).
1321 unsigned long do_mmap(struct file
*file
, unsigned long addr
,
1322 unsigned long len
, unsigned long prot
,
1323 unsigned long flags
, vm_flags_t vm_flags
,
1324 unsigned long pgoff
, unsigned long *populate
,
1325 struct list_head
*uf
)
1327 struct mm_struct
*mm
= current
->mm
;
1336 * Does the application expect PROT_READ to imply PROT_EXEC?
1338 * (the exception is when the underlying filesystem is noexec
1339 * mounted, in which case we dont add PROT_EXEC.)
1341 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
1342 if (!(file
&& path_noexec(&file
->f_path
)))
1345 if (!(flags
& MAP_FIXED
))
1346 addr
= round_hint_to_min(addr
);
1348 /* Careful about overflows.. */
1349 len
= PAGE_ALIGN(len
);
1353 /* offset overflow? */
1354 if ((pgoff
+ (len
>> PAGE_SHIFT
)) < pgoff
)
1357 /* Too many mappings? */
1358 if (mm
->map_count
> sysctl_max_map_count
)
1361 /* Obtain the address to map to. we verify (or select) it and ensure
1362 * that it represents a valid section of the address space.
1364 addr
= get_unmapped_area(file
, addr
, len
, pgoff
, flags
);
1365 if (offset_in_page(addr
))
1368 if (prot
== PROT_EXEC
) {
1369 pkey
= execute_only_pkey(mm
);
1374 /* Do simple checking here so the lower-level routines won't have
1375 * to. we assume access permissions have been handled by the open
1376 * of the memory object, so we don't do any here.
1378 vm_flags
|= calc_vm_prot_bits(prot
, pkey
) | calc_vm_flag_bits(flags
) |
1379 mm
->def_flags
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1381 if (flags
& MAP_LOCKED
)
1382 if (!can_do_mlock())
1385 if (mlock_future_check(mm
, vm_flags
, len
))
1389 struct inode
*inode
= file_inode(file
);
1391 switch (flags
& MAP_TYPE
) {
1393 if ((prot
&PROT_WRITE
) && !(file
->f_mode
&FMODE_WRITE
))
1397 * Make sure we don't allow writing to an append-only
1400 if (IS_APPEND(inode
) && (file
->f_mode
& FMODE_WRITE
))
1404 * Make sure there are no mandatory locks on the file.
1406 if (locks_verify_locked(file
))
1409 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1410 if (!(file
->f_mode
& FMODE_WRITE
))
1411 vm_flags
&= ~(VM_MAYWRITE
| VM_SHARED
);
1415 if (!(file
->f_mode
& FMODE_READ
))
1417 if (path_noexec(&file
->f_path
)) {
1418 if (vm_flags
& VM_EXEC
)
1420 vm_flags
&= ~VM_MAYEXEC
;
1423 if (!file
->f_op
->mmap
)
1425 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1433 switch (flags
& MAP_TYPE
) {
1435 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1441 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1445 * Set pgoff according to addr for anon_vma.
1447 pgoff
= addr
>> PAGE_SHIFT
;
1455 * Set 'VM_NORESERVE' if we should not account for the
1456 * memory use of this mapping.
1458 if (flags
& MAP_NORESERVE
) {
1459 /* We honor MAP_NORESERVE if allowed to overcommit */
1460 if (sysctl_overcommit_memory
!= OVERCOMMIT_NEVER
)
1461 vm_flags
|= VM_NORESERVE
;
1463 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1464 if (file
&& is_file_hugepages(file
))
1465 vm_flags
|= VM_NORESERVE
;
1468 addr
= mmap_region(file
, addr
, len
, vm_flags
, pgoff
, uf
);
1469 if (!IS_ERR_VALUE(addr
) &&
1470 ((vm_flags
& VM_LOCKED
) ||
1471 (flags
& (MAP_POPULATE
| MAP_NONBLOCK
)) == MAP_POPULATE
))
1476 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1477 unsigned long, prot
, unsigned long, flags
,
1478 unsigned long, fd
, unsigned long, pgoff
)
1480 struct file
*file
= NULL
;
1481 unsigned long retval
;
1483 if (!(flags
& MAP_ANONYMOUS
)) {
1484 audit_mmap_fd(fd
, flags
);
1488 if (is_file_hugepages(file
))
1489 len
= ALIGN(len
, huge_page_size(hstate_file(file
)));
1491 if (unlikely(flags
& MAP_HUGETLB
&& !is_file_hugepages(file
)))
1493 } else if (flags
& MAP_HUGETLB
) {
1494 struct user_struct
*user
= NULL
;
1497 hs
= hstate_sizelog((flags
>> MAP_HUGE_SHIFT
) & MAP_HUGE_MASK
);
1501 len
= ALIGN(len
, huge_page_size(hs
));
1503 * VM_NORESERVE is used because the reservations will be
1504 * taken when vm_ops->mmap() is called
1505 * A dummy user value is used because we are not locking
1506 * memory so no accounting is necessary
1508 file
= hugetlb_file_setup(HUGETLB_ANON_FILE
, len
,
1510 &user
, HUGETLB_ANONHUGE_INODE
,
1511 (flags
>> MAP_HUGE_SHIFT
) & MAP_HUGE_MASK
);
1513 return PTR_ERR(file
);
1516 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1518 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1525 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1526 struct mmap_arg_struct
{
1530 unsigned long flags
;
1532 unsigned long offset
;
1535 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1537 struct mmap_arg_struct a
;
1539 if (copy_from_user(&a
, arg
, sizeof(a
)))
1541 if (offset_in_page(a
.offset
))
1544 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1545 a
.offset
>> PAGE_SHIFT
);
1547 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1550 * Some shared mappigns will want the pages marked read-only
1551 * to track write events. If so, we'll downgrade vm_page_prot
1552 * to the private version (using protection_map[] without the
1555 int vma_wants_writenotify(struct vm_area_struct
*vma
, pgprot_t vm_page_prot
)
1557 vm_flags_t vm_flags
= vma
->vm_flags
;
1558 const struct vm_operations_struct
*vm_ops
= vma
->vm_ops
;
1560 /* If it was private or non-writable, the write bit is already clear */
1561 if ((vm_flags
& (VM_WRITE
|VM_SHARED
)) != ((VM_WRITE
|VM_SHARED
)))
1564 /* The backer wishes to know when pages are first written to? */
1565 if (vm_ops
&& (vm_ops
->page_mkwrite
|| vm_ops
->pfn_mkwrite
))
1568 /* The open routine did something to the protections that pgprot_modify
1569 * won't preserve? */
1570 if (pgprot_val(vm_page_prot
) !=
1571 pgprot_val(vm_pgprot_modify(vm_page_prot
, vm_flags
)))
1574 /* Do we need to track softdirty? */
1575 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY
) && !(vm_flags
& VM_SOFTDIRTY
))
1578 /* Specialty mapping? */
1579 if (vm_flags
& VM_PFNMAP
)
1582 /* Can the mapping track the dirty pages? */
1583 return vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
1584 mapping_cap_account_dirty(vma
->vm_file
->f_mapping
);
1588 * We account for memory if it's a private writeable mapping,
1589 * not hugepages and VM_NORESERVE wasn't set.
1591 static inline int accountable_mapping(struct file
*file
, vm_flags_t vm_flags
)
1594 * hugetlb has its own accounting separate from the core VM
1595 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1597 if (file
&& is_file_hugepages(file
))
1600 return (vm_flags
& (VM_NORESERVE
| VM_SHARED
| VM_WRITE
)) == VM_WRITE
;
1603 unsigned long mmap_region(struct file
*file
, unsigned long addr
,
1604 unsigned long len
, vm_flags_t vm_flags
, unsigned long pgoff
,
1605 struct list_head
*uf
)
1607 struct mm_struct
*mm
= current
->mm
;
1608 struct vm_area_struct
*vma
, *prev
;
1610 struct rb_node
**rb_link
, *rb_parent
;
1611 unsigned long charged
= 0;
1613 /* Check against address space limit. */
1614 if (!may_expand_vm(mm
, vm_flags
, len
>> PAGE_SHIFT
)) {
1615 unsigned long nr_pages
;
1618 * MAP_FIXED may remove pages of mappings that intersects with
1619 * requested mapping. Account for the pages it would unmap.
1621 nr_pages
= count_vma_pages_range(mm
, addr
, addr
+ len
);
1623 if (!may_expand_vm(mm
, vm_flags
,
1624 (len
>> PAGE_SHIFT
) - nr_pages
))
1628 /* Clear old maps */
1629 while (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
,
1631 if (do_munmap(mm
, addr
, len
, uf
))
1636 * Private writable mapping: check memory availability
1638 if (accountable_mapping(file
, vm_flags
)) {
1639 charged
= len
>> PAGE_SHIFT
;
1640 if (security_vm_enough_memory_mm(mm
, charged
))
1642 vm_flags
|= VM_ACCOUNT
;
1646 * Can we just expand an old mapping?
1648 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vm_flags
,
1649 NULL
, file
, pgoff
, NULL
, NULL_VM_UFFD_CTX
);
1654 * Determine the object being mapped and call the appropriate
1655 * specific mapper. the address has already been validated, but
1656 * not unmapped, but the maps are removed from the list.
1658 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1665 vma
->vm_start
= addr
;
1666 vma
->vm_end
= addr
+ len
;
1667 vma
->vm_flags
= vm_flags
;
1668 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
);
1669 vma
->vm_pgoff
= pgoff
;
1670 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1673 if (vm_flags
& VM_DENYWRITE
) {
1674 error
= deny_write_access(file
);
1678 if (vm_flags
& VM_SHARED
) {
1679 error
= mapping_map_writable(file
->f_mapping
);
1681 goto allow_write_and_free_vma
;
1684 /* ->mmap() can change vma->vm_file, but must guarantee that
1685 * vma_link() below can deny write-access if VM_DENYWRITE is set
1686 * and map writably if VM_SHARED is set. This usually means the
1687 * new file must not have been exposed to user-space, yet.
1689 vma
->vm_file
= get_file(file
);
1690 error
= call_mmap(file
, vma
);
1692 goto unmap_and_free_vma
;
1694 /* Can addr have changed??
1696 * Answer: Yes, several device drivers can do it in their
1697 * f_op->mmap method. -DaveM
1698 * Bug: If addr is changed, prev, rb_link, rb_parent should
1699 * be updated for vma_link()
1701 WARN_ON_ONCE(addr
!= vma
->vm_start
);
1703 addr
= vma
->vm_start
;
1704 vm_flags
= vma
->vm_flags
;
1705 } else if (vm_flags
& VM_SHARED
) {
1706 error
= shmem_zero_setup(vma
);
1711 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
1712 /* Once vma denies write, undo our temporary denial count */
1714 if (vm_flags
& VM_SHARED
)
1715 mapping_unmap_writable(file
->f_mapping
);
1716 if (vm_flags
& VM_DENYWRITE
)
1717 allow_write_access(file
);
1719 file
= vma
->vm_file
;
1721 perf_event_mmap(vma
);
1723 vm_stat_account(mm
, vm_flags
, len
>> PAGE_SHIFT
);
1724 if (vm_flags
& VM_LOCKED
) {
1725 if (!((vm_flags
& VM_SPECIAL
) || is_vm_hugetlb_page(vma
) ||
1726 vma
== get_gate_vma(current
->mm
)))
1727 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
1729 vma
->vm_flags
&= VM_LOCKED_CLEAR_MASK
;
1736 * New (or expanded) vma always get soft dirty status.
1737 * Otherwise user-space soft-dirty page tracker won't
1738 * be able to distinguish situation when vma area unmapped,
1739 * then new mapped in-place (which must be aimed as
1740 * a completely new data area).
1742 vma
->vm_flags
|= VM_SOFTDIRTY
;
1744 vma_set_page_prot(vma
);
1749 vma
->vm_file
= NULL
;
1752 /* Undo any partial mapping done by a device driver. */
1753 unmap_region(mm
, vma
, prev
, vma
->vm_start
, vma
->vm_end
);
1755 if (vm_flags
& VM_SHARED
)
1756 mapping_unmap_writable(file
->f_mapping
);
1757 allow_write_and_free_vma
:
1758 if (vm_flags
& VM_DENYWRITE
)
1759 allow_write_access(file
);
1761 kmem_cache_free(vm_area_cachep
, vma
);
1764 vm_unacct_memory(charged
);
1768 unsigned long unmapped_area(struct vm_unmapped_area_info
*info
)
1771 * We implement the search by looking for an rbtree node that
1772 * immediately follows a suitable gap. That is,
1773 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1774 * - gap_end = vma->vm_start >= info->low_limit + length;
1775 * - gap_end - gap_start >= length
1778 struct mm_struct
*mm
= current
->mm
;
1779 struct vm_area_struct
*vma
;
1780 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1782 /* Adjust search length to account for worst case alignment overhead */
1783 length
= info
->length
+ info
->align_mask
;
1784 if (length
< info
->length
)
1787 /* Adjust search limits by the desired length */
1788 if (info
->high_limit
< length
)
1790 high_limit
= info
->high_limit
- length
;
1792 if (info
->low_limit
> high_limit
)
1794 low_limit
= info
->low_limit
+ length
;
1796 /* Check if rbtree root looks promising */
1797 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1799 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1800 if (vma
->rb_subtree_gap
< length
)
1804 /* Visit left subtree if it looks promising */
1805 gap_end
= vm_start_gap(vma
);
1806 if (gap_end
>= low_limit
&& vma
->vm_rb
.rb_left
) {
1807 struct vm_area_struct
*left
=
1808 rb_entry(vma
->vm_rb
.rb_left
,
1809 struct vm_area_struct
, vm_rb
);
1810 if (left
->rb_subtree_gap
>= length
) {
1816 gap_start
= vma
->vm_prev
? vm_end_gap(vma
->vm_prev
) : 0;
1818 /* Check if current node has a suitable gap */
1819 if (gap_start
> high_limit
)
1821 if (gap_end
>= low_limit
&&
1822 gap_end
> gap_start
&& gap_end
- gap_start
>= length
)
1825 /* Visit right subtree if it looks promising */
1826 if (vma
->vm_rb
.rb_right
) {
1827 struct vm_area_struct
*right
=
1828 rb_entry(vma
->vm_rb
.rb_right
,
1829 struct vm_area_struct
, vm_rb
);
1830 if (right
->rb_subtree_gap
>= length
) {
1836 /* Go back up the rbtree to find next candidate node */
1838 struct rb_node
*prev
= &vma
->vm_rb
;
1839 if (!rb_parent(prev
))
1841 vma
= rb_entry(rb_parent(prev
),
1842 struct vm_area_struct
, vm_rb
);
1843 if (prev
== vma
->vm_rb
.rb_left
) {
1844 gap_start
= vm_end_gap(vma
->vm_prev
);
1845 gap_end
= vm_start_gap(vma
);
1852 /* Check highest gap, which does not precede any rbtree node */
1853 gap_start
= mm
->highest_vm_end
;
1854 gap_end
= ULONG_MAX
; /* Only for VM_BUG_ON below */
1855 if (gap_start
> high_limit
)
1859 /* We found a suitable gap. Clip it with the original low_limit. */
1860 if (gap_start
< info
->low_limit
)
1861 gap_start
= info
->low_limit
;
1863 /* Adjust gap address to the desired alignment */
1864 gap_start
+= (info
->align_offset
- gap_start
) & info
->align_mask
;
1866 VM_BUG_ON(gap_start
+ info
->length
> info
->high_limit
);
1867 VM_BUG_ON(gap_start
+ info
->length
> gap_end
);
1871 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info
*info
)
1873 struct mm_struct
*mm
= current
->mm
;
1874 struct vm_area_struct
*vma
;
1875 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1877 /* Adjust search length to account for worst case alignment overhead */
1878 length
= info
->length
+ info
->align_mask
;
1879 if (length
< info
->length
)
1883 * Adjust search limits by the desired length.
1884 * See implementation comment at top of unmapped_area().
1886 gap_end
= info
->high_limit
;
1887 if (gap_end
< length
)
1889 high_limit
= gap_end
- length
;
1891 if (info
->low_limit
> high_limit
)
1893 low_limit
= info
->low_limit
+ length
;
1895 /* Check highest gap, which does not precede any rbtree node */
1896 gap_start
= mm
->highest_vm_end
;
1897 if (gap_start
<= high_limit
)
1900 /* Check if rbtree root looks promising */
1901 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1903 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1904 if (vma
->rb_subtree_gap
< length
)
1908 /* Visit right subtree if it looks promising */
1909 gap_start
= vma
->vm_prev
? vm_end_gap(vma
->vm_prev
) : 0;
1910 if (gap_start
<= high_limit
&& vma
->vm_rb
.rb_right
) {
1911 struct vm_area_struct
*right
=
1912 rb_entry(vma
->vm_rb
.rb_right
,
1913 struct vm_area_struct
, vm_rb
);
1914 if (right
->rb_subtree_gap
>= length
) {
1921 /* Check if current node has a suitable gap */
1922 gap_end
= vm_start_gap(vma
);
1923 if (gap_end
< low_limit
)
1925 if (gap_start
<= high_limit
&&
1926 gap_end
> gap_start
&& gap_end
- gap_start
>= length
)
1929 /* Visit left subtree if it looks promising */
1930 if (vma
->vm_rb
.rb_left
) {
1931 struct vm_area_struct
*left
=
1932 rb_entry(vma
->vm_rb
.rb_left
,
1933 struct vm_area_struct
, vm_rb
);
1934 if (left
->rb_subtree_gap
>= length
) {
1940 /* Go back up the rbtree to find next candidate node */
1942 struct rb_node
*prev
= &vma
->vm_rb
;
1943 if (!rb_parent(prev
))
1945 vma
= rb_entry(rb_parent(prev
),
1946 struct vm_area_struct
, vm_rb
);
1947 if (prev
== vma
->vm_rb
.rb_right
) {
1948 gap_start
= vma
->vm_prev
?
1949 vm_end_gap(vma
->vm_prev
) : 0;
1956 /* We found a suitable gap. Clip it with the original high_limit. */
1957 if (gap_end
> info
->high_limit
)
1958 gap_end
= info
->high_limit
;
1961 /* Compute highest gap address at the desired alignment */
1962 gap_end
-= info
->length
;
1963 gap_end
-= (gap_end
- info
->align_offset
) & info
->align_mask
;
1965 VM_BUG_ON(gap_end
< info
->low_limit
);
1966 VM_BUG_ON(gap_end
< gap_start
);
1970 /* Get an address range which is currently unmapped.
1971 * For shmat() with addr=0.
1973 * Ugly calling convention alert:
1974 * Return value with the low bits set means error value,
1976 * if (ret & ~PAGE_MASK)
1979 * This function "knows" that -ENOMEM has the bits set.
1981 #ifndef HAVE_ARCH_UNMAPPED_AREA
1983 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
1984 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1986 struct mm_struct
*mm
= current
->mm
;
1987 struct vm_area_struct
*vma
, *prev
;
1988 struct vm_unmapped_area_info info
;
1990 if (len
> TASK_SIZE
- mmap_min_addr
)
1993 if (flags
& MAP_FIXED
)
1997 addr
= PAGE_ALIGN(addr
);
1998 vma
= find_vma_prev(mm
, addr
, &prev
);
1999 if (TASK_SIZE
- len
>= addr
&& addr
>= mmap_min_addr
&&
2000 (!vma
|| addr
+ len
<= vm_start_gap(vma
)) &&
2001 (!prev
|| addr
>= vm_end_gap(prev
)))
2007 info
.low_limit
= mm
->mmap_base
;
2008 info
.high_limit
= TASK_SIZE
;
2009 info
.align_mask
= 0;
2010 return vm_unmapped_area(&info
);
2015 * This mmap-allocator allocates new areas top-down from below the
2016 * stack's low limit (the base):
2018 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2020 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
2021 const unsigned long len
, const unsigned long pgoff
,
2022 const unsigned long flags
)
2024 struct vm_area_struct
*vma
, *prev
;
2025 struct mm_struct
*mm
= current
->mm
;
2026 unsigned long addr
= addr0
;
2027 struct vm_unmapped_area_info info
;
2029 /* requested length too big for entire address space */
2030 if (len
> TASK_SIZE
- mmap_min_addr
)
2033 if (flags
& MAP_FIXED
)
2036 /* requesting a specific address */
2038 addr
= PAGE_ALIGN(addr
);
2039 vma
= find_vma_prev(mm
, addr
, &prev
);
2040 if (TASK_SIZE
- len
>= addr
&& addr
>= mmap_min_addr
&&
2041 (!vma
|| addr
+ len
<= vm_start_gap(vma
)) &&
2042 (!prev
|| addr
>= vm_end_gap(prev
)))
2046 info
.flags
= VM_UNMAPPED_AREA_TOPDOWN
;
2048 info
.low_limit
= max(PAGE_SIZE
, mmap_min_addr
);
2049 info
.high_limit
= mm
->mmap_base
;
2050 info
.align_mask
= 0;
2051 addr
= vm_unmapped_area(&info
);
2054 * A failed mmap() very likely causes application failure,
2055 * so fall back to the bottom-up function here. This scenario
2056 * can happen with large stack limits and large mmap()
2059 if (offset_in_page(addr
)) {
2060 VM_BUG_ON(addr
!= -ENOMEM
);
2062 info
.low_limit
= TASK_UNMAPPED_BASE
;
2063 info
.high_limit
= TASK_SIZE
;
2064 addr
= vm_unmapped_area(&info
);
2072 get_unmapped_area(struct file
*file
, unsigned long addr
, unsigned long len
,
2073 unsigned long pgoff
, unsigned long flags
)
2075 unsigned long (*get_area
)(struct file
*, unsigned long,
2076 unsigned long, unsigned long, unsigned long);
2078 unsigned long error
= arch_mmap_check(addr
, len
, flags
);
2082 /* Careful about overflows.. */
2083 if (len
> TASK_SIZE
)
2086 get_area
= current
->mm
->get_unmapped_area
;
2088 if (file
->f_op
->get_unmapped_area
)
2089 get_area
= file
->f_op
->get_unmapped_area
;
2090 } else if (flags
& MAP_SHARED
) {
2092 * mmap_region() will call shmem_zero_setup() to create a file,
2093 * so use shmem's get_unmapped_area in case it can be huge.
2094 * do_mmap_pgoff() will clear pgoff, so match alignment.
2097 get_area
= shmem_get_unmapped_area
;
2100 addr
= get_area(file
, addr
, len
, pgoff
, flags
);
2101 if (IS_ERR_VALUE(addr
))
2104 if (addr
> TASK_SIZE
- len
)
2106 if (offset_in_page(addr
))
2109 error
= security_mmap_addr(addr
);
2110 return error
? error
: addr
;
2113 EXPORT_SYMBOL(get_unmapped_area
);
2115 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2116 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
2118 struct rb_node
*rb_node
;
2119 struct vm_area_struct
*vma
;
2121 /* Check the cache first. */
2122 vma
= vmacache_find(mm
, addr
);
2126 rb_node
= mm
->mm_rb
.rb_node
;
2129 struct vm_area_struct
*tmp
;
2131 tmp
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
2133 if (tmp
->vm_end
> addr
) {
2135 if (tmp
->vm_start
<= addr
)
2137 rb_node
= rb_node
->rb_left
;
2139 rb_node
= rb_node
->rb_right
;
2143 vmacache_update(addr
, vma
);
2147 EXPORT_SYMBOL(find_vma
);
2150 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2152 struct vm_area_struct
*
2153 find_vma_prev(struct mm_struct
*mm
, unsigned long addr
,
2154 struct vm_area_struct
**pprev
)
2156 struct vm_area_struct
*vma
;
2158 vma
= find_vma(mm
, addr
);
2160 *pprev
= vma
->vm_prev
;
2162 struct rb_node
*rb_node
= mm
->mm_rb
.rb_node
;
2165 *pprev
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
2166 rb_node
= rb_node
->rb_right
;
2173 * Verify that the stack growth is acceptable and
2174 * update accounting. This is shared with both the
2175 * grow-up and grow-down cases.
2177 static int acct_stack_growth(struct vm_area_struct
*vma
,
2178 unsigned long size
, unsigned long grow
)
2180 struct mm_struct
*mm
= vma
->vm_mm
;
2181 unsigned long new_start
;
2183 /* address space limit tests */
2184 if (!may_expand_vm(mm
, vma
->vm_flags
, grow
))
2187 /* Stack limit test */
2188 if (size
> rlimit(RLIMIT_STACK
))
2191 /* mlock limit tests */
2192 if (vma
->vm_flags
& VM_LOCKED
) {
2193 unsigned long locked
;
2194 unsigned long limit
;
2195 locked
= mm
->locked_vm
+ grow
;
2196 limit
= rlimit(RLIMIT_MEMLOCK
);
2197 limit
>>= PAGE_SHIFT
;
2198 if (locked
> limit
&& !capable(CAP_IPC_LOCK
))
2202 /* Check to ensure the stack will not grow into a hugetlb-only region */
2203 new_start
= (vma
->vm_flags
& VM_GROWSUP
) ? vma
->vm_start
:
2205 if (is_hugepage_only_range(vma
->vm_mm
, new_start
, size
))
2209 * Overcommit.. This must be the final test, as it will
2210 * update security statistics.
2212 if (security_vm_enough_memory_mm(mm
, grow
))
2218 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2220 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2221 * vma is the last one with address > vma->vm_end. Have to extend vma.
2223 int expand_upwards(struct vm_area_struct
*vma
, unsigned long address
)
2225 struct mm_struct
*mm
= vma
->vm_mm
;
2226 struct vm_area_struct
*next
;
2227 unsigned long gap_addr
;
2230 if (!(vma
->vm_flags
& VM_GROWSUP
))
2233 /* Guard against exceeding limits of the address space. */
2234 address
&= PAGE_MASK
;
2235 if (address
>= (TASK_SIZE
& PAGE_MASK
))
2237 address
+= PAGE_SIZE
;
2239 /* Enforce stack_guard_gap */
2240 gap_addr
= address
+ stack_guard_gap
;
2242 /* Guard against overflow */
2243 if (gap_addr
< address
|| gap_addr
> TASK_SIZE
)
2244 gap_addr
= TASK_SIZE
;
2246 next
= vma
->vm_next
;
2247 if (next
&& next
->vm_start
< gap_addr
&&
2248 (next
->vm_flags
& (VM_WRITE
|VM_READ
|VM_EXEC
))) {
2249 if (!(next
->vm_flags
& VM_GROWSUP
))
2251 /* Check that both stack segments have the same anon_vma? */
2254 /* We must make sure the anon_vma is allocated. */
2255 if (unlikely(anon_vma_prepare(vma
)))
2259 * vma->vm_start/vm_end cannot change under us because the caller
2260 * is required to hold the mmap_sem in read mode. We need the
2261 * anon_vma lock to serialize against concurrent expand_stacks.
2263 anon_vma_lock_write(vma
->anon_vma
);
2265 /* Somebody else might have raced and expanded it already */
2266 if (address
> vma
->vm_end
) {
2267 unsigned long size
, grow
;
2269 size
= address
- vma
->vm_start
;
2270 grow
= (address
- vma
->vm_end
) >> PAGE_SHIFT
;
2273 if (vma
->vm_pgoff
+ (size
>> PAGE_SHIFT
) >= vma
->vm_pgoff
) {
2274 error
= acct_stack_growth(vma
, size
, grow
);
2277 * vma_gap_update() doesn't support concurrent
2278 * updates, but we only hold a shared mmap_sem
2279 * lock here, so we need to protect against
2280 * concurrent vma expansions.
2281 * anon_vma_lock_write() doesn't help here, as
2282 * we don't guarantee that all growable vmas
2283 * in a mm share the same root anon vma.
2284 * So, we reuse mm->page_table_lock to guard
2285 * against concurrent vma expansions.
2287 spin_lock(&mm
->page_table_lock
);
2288 if (vma
->vm_flags
& VM_LOCKED
)
2289 mm
->locked_vm
+= grow
;
2290 vm_stat_account(mm
, vma
->vm_flags
, grow
);
2291 anon_vma_interval_tree_pre_update_vma(vma
);
2292 vma
->vm_end
= address
;
2293 anon_vma_interval_tree_post_update_vma(vma
);
2295 vma_gap_update(vma
->vm_next
);
2297 mm
->highest_vm_end
= vm_end_gap(vma
);
2298 spin_unlock(&mm
->page_table_lock
);
2300 perf_event_mmap(vma
);
2304 anon_vma_unlock_write(vma
->anon_vma
);
2305 khugepaged_enter_vma_merge(vma
, vma
->vm_flags
);
2309 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2312 * vma is the first one with address < vma->vm_start. Have to extend vma.
2314 int expand_downwards(struct vm_area_struct
*vma
,
2315 unsigned long address
)
2317 struct mm_struct
*mm
= vma
->vm_mm
;
2318 struct vm_area_struct
*prev
;
2321 address
&= PAGE_MASK
;
2322 error
= security_mmap_addr(address
);
2326 /* Enforce stack_guard_gap */
2327 prev
= vma
->vm_prev
;
2328 /* Check that both stack segments have the same anon_vma? */
2329 if (prev
&& !(prev
->vm_flags
& VM_GROWSDOWN
) &&
2330 (prev
->vm_flags
& (VM_WRITE
|VM_READ
|VM_EXEC
))) {
2331 if (address
- prev
->vm_end
< stack_guard_gap
)
2335 /* We must make sure the anon_vma is allocated. */
2336 if (unlikely(anon_vma_prepare(vma
)))
2340 * vma->vm_start/vm_end cannot change under us because the caller
2341 * is required to hold the mmap_sem in read mode. We need the
2342 * anon_vma lock to serialize against concurrent expand_stacks.
2344 anon_vma_lock_write(vma
->anon_vma
);
2346 /* Somebody else might have raced and expanded it already */
2347 if (address
< vma
->vm_start
) {
2348 unsigned long size
, grow
;
2350 size
= vma
->vm_end
- address
;
2351 grow
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
2354 if (grow
<= vma
->vm_pgoff
) {
2355 error
= acct_stack_growth(vma
, size
, grow
);
2358 * vma_gap_update() doesn't support concurrent
2359 * updates, but we only hold a shared mmap_sem
2360 * lock here, so we need to protect against
2361 * concurrent vma expansions.
2362 * anon_vma_lock_write() doesn't help here, as
2363 * we don't guarantee that all growable vmas
2364 * in a mm share the same root anon vma.
2365 * So, we reuse mm->page_table_lock to guard
2366 * against concurrent vma expansions.
2368 spin_lock(&mm
->page_table_lock
);
2369 if (vma
->vm_flags
& VM_LOCKED
)
2370 mm
->locked_vm
+= grow
;
2371 vm_stat_account(mm
, vma
->vm_flags
, grow
);
2372 anon_vma_interval_tree_pre_update_vma(vma
);
2373 vma
->vm_start
= address
;
2374 vma
->vm_pgoff
-= grow
;
2375 anon_vma_interval_tree_post_update_vma(vma
);
2376 vma_gap_update(vma
);
2377 spin_unlock(&mm
->page_table_lock
);
2379 perf_event_mmap(vma
);
2383 anon_vma_unlock_write(vma
->anon_vma
);
2384 khugepaged_enter_vma_merge(vma
, vma
->vm_flags
);
2389 /* enforced gap between the expanding stack and other mappings. */
2390 unsigned long stack_guard_gap
= 256UL<<PAGE_SHIFT
;
2392 static int __init
cmdline_parse_stack_guard_gap(char *p
)
2397 val
= simple_strtoul(p
, &endptr
, 10);
2399 stack_guard_gap
= val
<< PAGE_SHIFT
;
2403 __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap
);
2405 #ifdef CONFIG_STACK_GROWSUP
2406 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2408 return expand_upwards(vma
, address
);
2411 struct vm_area_struct
*
2412 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
2414 struct vm_area_struct
*vma
, *prev
;
2417 vma
= find_vma_prev(mm
, addr
, &prev
);
2418 if (vma
&& (vma
->vm_start
<= addr
))
2420 if (!prev
|| expand_stack(prev
, addr
))
2422 if (prev
->vm_flags
& VM_LOCKED
)
2423 populate_vma_page_range(prev
, addr
, prev
->vm_end
, NULL
);
2427 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2429 return expand_downwards(vma
, address
);
2432 struct vm_area_struct
*
2433 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
2435 struct vm_area_struct
*vma
;
2436 unsigned long start
;
2439 vma
= find_vma(mm
, addr
);
2442 if (vma
->vm_start
<= addr
)
2444 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
2446 start
= vma
->vm_start
;
2447 if (expand_stack(vma
, addr
))
2449 if (vma
->vm_flags
& VM_LOCKED
)
2450 populate_vma_page_range(vma
, addr
, start
, NULL
);
2455 EXPORT_SYMBOL_GPL(find_extend_vma
);
2458 * Ok - we have the memory areas we should free on the vma list,
2459 * so release them, and do the vma updates.
2461 * Called with the mm semaphore held.
2463 static void remove_vma_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
2465 unsigned long nr_accounted
= 0;
2467 /* Update high watermark before we lower total_vm */
2468 update_hiwater_vm(mm
);
2470 long nrpages
= vma_pages(vma
);
2472 if (vma
->vm_flags
& VM_ACCOUNT
)
2473 nr_accounted
+= nrpages
;
2474 vm_stat_account(mm
, vma
->vm_flags
, -nrpages
);
2475 vma
= remove_vma(vma
);
2477 vm_unacct_memory(nr_accounted
);
2482 * Get rid of page table information in the indicated region.
2484 * Called with the mm semaphore held.
2486 static void unmap_region(struct mm_struct
*mm
,
2487 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
2488 unsigned long start
, unsigned long end
)
2490 struct vm_area_struct
*next
= prev
? prev
->vm_next
: mm
->mmap
;
2491 struct mmu_gather tlb
;
2494 tlb_gather_mmu(&tlb
, mm
, start
, end
);
2495 update_hiwater_rss(mm
);
2496 unmap_vmas(&tlb
, vma
, start
, end
);
2497 free_pgtables(&tlb
, vma
, prev
? prev
->vm_end
: FIRST_USER_ADDRESS
,
2498 next
? next
->vm_start
: USER_PGTABLES_CEILING
);
2499 tlb_finish_mmu(&tlb
, start
, end
);
2503 * Create a list of vma's touched by the unmap, removing them from the mm's
2504 * vma list as we go..
2507 detach_vmas_to_be_unmapped(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2508 struct vm_area_struct
*prev
, unsigned long end
)
2510 struct vm_area_struct
**insertion_point
;
2511 struct vm_area_struct
*tail_vma
= NULL
;
2513 insertion_point
= (prev
? &prev
->vm_next
: &mm
->mmap
);
2514 vma
->vm_prev
= NULL
;
2516 vma_rb_erase(vma
, &mm
->mm_rb
);
2520 } while (vma
&& vma
->vm_start
< end
);
2521 *insertion_point
= vma
;
2523 vma
->vm_prev
= prev
;
2524 vma_gap_update(vma
);
2526 mm
->highest_vm_end
= prev
? vm_end_gap(prev
) : 0;
2527 tail_vma
->vm_next
= NULL
;
2529 /* Kill the cache */
2530 vmacache_invalidate(mm
);
2534 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2535 * has already been checked or doesn't make sense to fail.
2537 int __split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2538 unsigned long addr
, int new_below
)
2540 struct vm_area_struct
*new;
2543 if (is_vm_hugetlb_page(vma
) && (addr
&
2544 ~(huge_page_mask(hstate_vma(vma
)))))
2547 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2551 /* most fields are the same, copy all, and then fixup */
2554 INIT_LIST_HEAD(&new->anon_vma_chain
);
2559 new->vm_start
= addr
;
2560 new->vm_pgoff
+= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
);
2563 err
= vma_dup_policy(vma
, new);
2567 err
= anon_vma_clone(new, vma
);
2572 get_file(new->vm_file
);
2574 if (new->vm_ops
&& new->vm_ops
->open
)
2575 new->vm_ops
->open(new);
2578 err
= vma_adjust(vma
, addr
, vma
->vm_end
, vma
->vm_pgoff
+
2579 ((addr
- new->vm_start
) >> PAGE_SHIFT
), new);
2581 err
= vma_adjust(vma
, vma
->vm_start
, addr
, vma
->vm_pgoff
, new);
2587 /* Clean everything up if vma_adjust failed. */
2588 if (new->vm_ops
&& new->vm_ops
->close
)
2589 new->vm_ops
->close(new);
2592 unlink_anon_vmas(new);
2594 mpol_put(vma_policy(new));
2596 kmem_cache_free(vm_area_cachep
, new);
2601 * Split a vma into two pieces at address 'addr', a new vma is allocated
2602 * either for the first part or the tail.
2604 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2605 unsigned long addr
, int new_below
)
2607 if (mm
->map_count
>= sysctl_max_map_count
)
2610 return __split_vma(mm
, vma
, addr
, new_below
);
2613 /* Munmap is split into 2 main parts -- this part which finds
2614 * what needs doing, and the areas themselves, which do the
2615 * work. This now handles partial unmappings.
2616 * Jeremy Fitzhardinge <jeremy@goop.org>
2618 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
,
2619 struct list_head
*uf
)
2622 struct vm_area_struct
*vma
, *prev
, *last
;
2624 if ((offset_in_page(start
)) || start
> TASK_SIZE
|| len
> TASK_SIZE
-start
)
2627 len
= PAGE_ALIGN(len
);
2631 /* Find the first overlapping VMA */
2632 vma
= find_vma(mm
, start
);
2635 prev
= vma
->vm_prev
;
2636 /* we have start < vma->vm_end */
2638 /* if it doesn't overlap, we have nothing.. */
2640 if (vma
->vm_start
>= end
)
2644 * If we need to split any vma, do it now to save pain later.
2646 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2647 * unmapped vm_area_struct will remain in use: so lower split_vma
2648 * places tmp vma above, and higher split_vma places tmp vma below.
2650 if (start
> vma
->vm_start
) {
2654 * Make sure that map_count on return from munmap() will
2655 * not exceed its limit; but let map_count go just above
2656 * its limit temporarily, to help free resources as expected.
2658 if (end
< vma
->vm_end
&& mm
->map_count
>= sysctl_max_map_count
)
2661 error
= __split_vma(mm
, vma
, start
, 0);
2667 /* Does it split the last one? */
2668 last
= find_vma(mm
, end
);
2669 if (last
&& end
> last
->vm_start
) {
2670 int error
= __split_vma(mm
, last
, end
, 1);
2674 vma
= prev
? prev
->vm_next
: mm
->mmap
;
2678 * If userfaultfd_unmap_prep returns an error the vmas
2679 * will remain splitted, but userland will get a
2680 * highly unexpected error anyway. This is no
2681 * different than the case where the first of the two
2682 * __split_vma fails, but we don't undo the first
2683 * split, despite we could. This is unlikely enough
2684 * failure that it's not worth optimizing it for.
2686 int error
= userfaultfd_unmap_prep(vma
, start
, end
, uf
);
2692 * unlock any mlock()ed ranges before detaching vmas
2694 if (mm
->locked_vm
) {
2695 struct vm_area_struct
*tmp
= vma
;
2696 while (tmp
&& tmp
->vm_start
< end
) {
2697 if (tmp
->vm_flags
& VM_LOCKED
) {
2698 mm
->locked_vm
-= vma_pages(tmp
);
2699 munlock_vma_pages_all(tmp
);
2706 * Remove the vma's, and unmap the actual pages
2708 detach_vmas_to_be_unmapped(mm
, vma
, prev
, end
);
2709 unmap_region(mm
, vma
, prev
, start
, end
);
2711 arch_unmap(mm
, vma
, start
, end
);
2713 /* Fix up all other VM information */
2714 remove_vma_list(mm
, vma
);
2719 int vm_munmap(unsigned long start
, size_t len
)
2722 struct mm_struct
*mm
= current
->mm
;
2725 if (down_write_killable(&mm
->mmap_sem
))
2728 ret
= do_munmap(mm
, start
, len
, &uf
);
2729 up_write(&mm
->mmap_sem
);
2730 userfaultfd_unmap_complete(mm
, &uf
);
2733 EXPORT_SYMBOL(vm_munmap
);
2735 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
2737 profile_munmap(addr
);
2738 return vm_munmap(addr
, len
);
2743 * Emulation of deprecated remap_file_pages() syscall.
2745 SYSCALL_DEFINE5(remap_file_pages
, unsigned long, start
, unsigned long, size
,
2746 unsigned long, prot
, unsigned long, pgoff
, unsigned long, flags
)
2749 struct mm_struct
*mm
= current
->mm
;
2750 struct vm_area_struct
*vma
;
2751 unsigned long populate
= 0;
2752 unsigned long ret
= -EINVAL
;
2755 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2756 current
->comm
, current
->pid
);
2760 start
= start
& PAGE_MASK
;
2761 size
= size
& PAGE_MASK
;
2763 if (start
+ size
<= start
)
2766 /* Does pgoff wrap? */
2767 if (pgoff
+ (size
>> PAGE_SHIFT
) < pgoff
)
2770 if (down_write_killable(&mm
->mmap_sem
))
2773 vma
= find_vma(mm
, start
);
2775 if (!vma
|| !(vma
->vm_flags
& VM_SHARED
))
2778 if (start
< vma
->vm_start
)
2781 if (start
+ size
> vma
->vm_end
) {
2782 struct vm_area_struct
*next
;
2784 for (next
= vma
->vm_next
; next
; next
= next
->vm_next
) {
2785 /* hole between vmas ? */
2786 if (next
->vm_start
!= next
->vm_prev
->vm_end
)
2789 if (next
->vm_file
!= vma
->vm_file
)
2792 if (next
->vm_flags
!= vma
->vm_flags
)
2795 if (start
+ size
<= next
->vm_end
)
2803 prot
|= vma
->vm_flags
& VM_READ
? PROT_READ
: 0;
2804 prot
|= vma
->vm_flags
& VM_WRITE
? PROT_WRITE
: 0;
2805 prot
|= vma
->vm_flags
& VM_EXEC
? PROT_EXEC
: 0;
2807 flags
&= MAP_NONBLOCK
;
2808 flags
|= MAP_SHARED
| MAP_FIXED
| MAP_POPULATE
;
2809 if (vma
->vm_flags
& VM_LOCKED
) {
2810 struct vm_area_struct
*tmp
;
2811 flags
|= MAP_LOCKED
;
2813 /* drop PG_Mlocked flag for over-mapped range */
2814 for (tmp
= vma
; tmp
->vm_start
>= start
+ size
;
2815 tmp
= tmp
->vm_next
) {
2817 * Split pmd and munlock page on the border
2820 vma_adjust_trans_huge(tmp
, start
, start
+ size
, 0);
2822 munlock_vma_pages_range(tmp
,
2823 max(tmp
->vm_start
, start
),
2824 min(tmp
->vm_end
, start
+ size
));
2828 file
= get_file(vma
->vm_file
);
2829 ret
= do_mmap_pgoff(vma
->vm_file
, start
, size
,
2830 prot
, flags
, pgoff
, &populate
, NULL
);
2833 up_write(&mm
->mmap_sem
);
2835 mm_populate(ret
, populate
);
2836 if (!IS_ERR_VALUE(ret
))
2841 static inline void verify_mm_writelocked(struct mm_struct
*mm
)
2843 #ifdef CONFIG_DEBUG_VM
2844 if (unlikely(down_read_trylock(&mm
->mmap_sem
))) {
2846 up_read(&mm
->mmap_sem
);
2852 * this is really a simplified "do_mmap". it only handles
2853 * anonymous maps. eventually we may be able to do some
2854 * brk-specific accounting here.
2856 static int do_brk_flags(unsigned long addr
, unsigned long request
, unsigned long flags
, struct list_head
*uf
)
2858 struct mm_struct
*mm
= current
->mm
;
2859 struct vm_area_struct
*vma
, *prev
;
2861 struct rb_node
**rb_link
, *rb_parent
;
2862 pgoff_t pgoff
= addr
>> PAGE_SHIFT
;
2865 len
= PAGE_ALIGN(request
);
2871 /* Until we need other flags, refuse anything except VM_EXEC. */
2872 if ((flags
& (~VM_EXEC
)) != 0)
2874 flags
|= VM_DATA_DEFAULT_FLAGS
| VM_ACCOUNT
| mm
->def_flags
;
2876 error
= get_unmapped_area(NULL
, addr
, len
, 0, MAP_FIXED
);
2877 if (offset_in_page(error
))
2880 error
= mlock_future_check(mm
, mm
->def_flags
, len
);
2885 * mm->mmap_sem is required to protect against another thread
2886 * changing the mappings in case we sleep.
2888 verify_mm_writelocked(mm
);
2891 * Clear old maps. this also does some error checking for us
2893 while (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
,
2895 if (do_munmap(mm
, addr
, len
, uf
))
2899 /* Check against address space limits *after* clearing old maps... */
2900 if (!may_expand_vm(mm
, flags
, len
>> PAGE_SHIFT
))
2903 if (mm
->map_count
> sysctl_max_map_count
)
2906 if (security_vm_enough_memory_mm(mm
, len
>> PAGE_SHIFT
))
2909 /* Can we just expand an old private anonymous mapping? */
2910 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, flags
,
2911 NULL
, NULL
, pgoff
, NULL
, NULL_VM_UFFD_CTX
);
2916 * create a vma struct for an anonymous mapping
2918 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2920 vm_unacct_memory(len
>> PAGE_SHIFT
);
2924 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2926 vma
->vm_start
= addr
;
2927 vma
->vm_end
= addr
+ len
;
2928 vma
->vm_pgoff
= pgoff
;
2929 vma
->vm_flags
= flags
;
2930 vma
->vm_page_prot
= vm_get_page_prot(flags
);
2931 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2933 perf_event_mmap(vma
);
2934 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2935 mm
->data_vm
+= len
>> PAGE_SHIFT
;
2936 if (flags
& VM_LOCKED
)
2937 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
2938 vma
->vm_flags
|= VM_SOFTDIRTY
;
2942 static int do_brk(unsigned long addr
, unsigned long len
, struct list_head
*uf
)
2944 return do_brk_flags(addr
, len
, 0, uf
);
2947 int vm_brk_flags(unsigned long addr
, unsigned long len
, unsigned long flags
)
2949 struct mm_struct
*mm
= current
->mm
;
2954 if (down_write_killable(&mm
->mmap_sem
))
2957 ret
= do_brk_flags(addr
, len
, flags
, &uf
);
2958 populate
= ((mm
->def_flags
& VM_LOCKED
) != 0);
2959 up_write(&mm
->mmap_sem
);
2960 userfaultfd_unmap_complete(mm
, &uf
);
2961 if (populate
&& !ret
)
2962 mm_populate(addr
, len
);
2965 EXPORT_SYMBOL(vm_brk_flags
);
2967 int vm_brk(unsigned long addr
, unsigned long len
)
2969 return vm_brk_flags(addr
, len
, 0);
2971 EXPORT_SYMBOL(vm_brk
);
2973 /* Release all mmaps. */
2974 void exit_mmap(struct mm_struct
*mm
)
2976 struct mmu_gather tlb
;
2977 struct vm_area_struct
*vma
;
2978 unsigned long nr_accounted
= 0;
2980 /* mm's last user has gone, and its about to be pulled down */
2981 mmu_notifier_release(mm
);
2983 if (mm
->locked_vm
) {
2986 if (vma
->vm_flags
& VM_LOCKED
)
2987 munlock_vma_pages_all(vma
);
2995 if (!vma
) /* Can happen if dup_mmap() received an OOM */
3000 tlb_gather_mmu(&tlb
, mm
, 0, -1);
3001 /* update_hiwater_rss(mm) here? but nobody should be looking */
3002 /* Use -1 here to ensure all VMAs in the mm are unmapped */
3003 unmap_vmas(&tlb
, vma
, 0, -1);
3005 set_bit(MMF_OOM_SKIP
, &mm
->flags
);
3006 if (unlikely(tsk_is_oom_victim(current
))) {
3008 * Wait for oom_reap_task() to stop working on this
3009 * mm. Because MMF_OOM_SKIP is already set before
3010 * calling down_read(), oom_reap_task() will not run
3011 * on this "mm" post up_write().
3013 * tsk_is_oom_victim() cannot be set from under us
3014 * either because current->mm is already set to NULL
3015 * under task_lock before calling mmput and oom_mm is
3016 * set not NULL by the OOM killer only if current->mm
3017 * is found not NULL while holding the task_lock.
3019 down_write(&mm
->mmap_sem
);
3020 up_write(&mm
->mmap_sem
);
3022 free_pgtables(&tlb
, vma
, FIRST_USER_ADDRESS
, USER_PGTABLES_CEILING
);
3023 tlb_finish_mmu(&tlb
, 0, -1);
3026 * Walk the list again, actually closing and freeing it,
3027 * with preemption enabled, without holding any MM locks.
3030 if (vma
->vm_flags
& VM_ACCOUNT
)
3031 nr_accounted
+= vma_pages(vma
);
3032 vma
= remove_vma(vma
);
3034 vm_unacct_memory(nr_accounted
);
3037 /* Insert vm structure into process list sorted by address
3038 * and into the inode's i_mmap tree. If vm_file is non-NULL
3039 * then i_mmap_rwsem is taken here.
3041 int insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
3043 struct vm_area_struct
*prev
;
3044 struct rb_node
**rb_link
, *rb_parent
;
3046 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
3047 &prev
, &rb_link
, &rb_parent
))
3049 if ((vma
->vm_flags
& VM_ACCOUNT
) &&
3050 security_vm_enough_memory_mm(mm
, vma_pages(vma
)))
3054 * The vm_pgoff of a purely anonymous vma should be irrelevant
3055 * until its first write fault, when page's anon_vma and index
3056 * are set. But now set the vm_pgoff it will almost certainly
3057 * end up with (unless mremap moves it elsewhere before that
3058 * first wfault), so /proc/pid/maps tells a consistent story.
3060 * By setting it to reflect the virtual start address of the
3061 * vma, merges and splits can happen in a seamless way, just
3062 * using the existing file pgoff checks and manipulations.
3063 * Similarly in do_mmap_pgoff and in do_brk.
3065 if (vma_is_anonymous(vma
)) {
3066 BUG_ON(vma
->anon_vma
);
3067 vma
->vm_pgoff
= vma
->vm_start
>> PAGE_SHIFT
;
3070 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
3075 * Copy the vma structure to a new location in the same mm,
3076 * prior to moving page table entries, to effect an mremap move.
3078 struct vm_area_struct
*copy_vma(struct vm_area_struct
**vmap
,
3079 unsigned long addr
, unsigned long len
, pgoff_t pgoff
,
3080 bool *need_rmap_locks
)
3082 struct vm_area_struct
*vma
= *vmap
;
3083 unsigned long vma_start
= vma
->vm_start
;
3084 struct mm_struct
*mm
= vma
->vm_mm
;
3085 struct vm_area_struct
*new_vma
, *prev
;
3086 struct rb_node
**rb_link
, *rb_parent
;
3087 bool faulted_in_anon_vma
= true;
3090 * If anonymous vma has not yet been faulted, update new pgoff
3091 * to match new location, to increase its chance of merging.
3093 if (unlikely(vma_is_anonymous(vma
) && !vma
->anon_vma
)) {
3094 pgoff
= addr
>> PAGE_SHIFT
;
3095 faulted_in_anon_vma
= false;
3098 if (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
, &rb_parent
))
3099 return NULL
; /* should never get here */
3100 new_vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vma
->vm_flags
,
3101 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
),
3102 vma
->vm_userfaultfd_ctx
);
3105 * Source vma may have been merged into new_vma
3107 if (unlikely(vma_start
>= new_vma
->vm_start
&&
3108 vma_start
< new_vma
->vm_end
)) {
3110 * The only way we can get a vma_merge with
3111 * self during an mremap is if the vma hasn't
3112 * been faulted in yet and we were allowed to
3113 * reset the dst vma->vm_pgoff to the
3114 * destination address of the mremap to allow
3115 * the merge to happen. mremap must change the
3116 * vm_pgoff linearity between src and dst vmas
3117 * (in turn preventing a vma_merge) to be
3118 * safe. It is only safe to keep the vm_pgoff
3119 * linear if there are no pages mapped yet.
3121 VM_BUG_ON_VMA(faulted_in_anon_vma
, new_vma
);
3122 *vmap
= vma
= new_vma
;
3124 *need_rmap_locks
= (new_vma
->vm_pgoff
<= vma
->vm_pgoff
);
3126 new_vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
3130 new_vma
->vm_start
= addr
;
3131 new_vma
->vm_end
= addr
+ len
;
3132 new_vma
->vm_pgoff
= pgoff
;
3133 if (vma_dup_policy(vma
, new_vma
))
3135 INIT_LIST_HEAD(&new_vma
->anon_vma_chain
);
3136 if (anon_vma_clone(new_vma
, vma
))
3137 goto out_free_mempol
;
3138 if (new_vma
->vm_file
)
3139 get_file(new_vma
->vm_file
);
3140 if (new_vma
->vm_ops
&& new_vma
->vm_ops
->open
)
3141 new_vma
->vm_ops
->open(new_vma
);
3142 vma_link(mm
, new_vma
, prev
, rb_link
, rb_parent
);
3143 *need_rmap_locks
= false;
3148 mpol_put(vma_policy(new_vma
));
3150 kmem_cache_free(vm_area_cachep
, new_vma
);
3156 * Return true if the calling process may expand its vm space by the passed
3159 bool may_expand_vm(struct mm_struct
*mm
, vm_flags_t flags
, unsigned long npages
)
3161 if (mm
->total_vm
+ npages
> rlimit(RLIMIT_AS
) >> PAGE_SHIFT
)
3164 if (is_data_mapping(flags
) &&
3165 mm
->data_vm
+ npages
> rlimit(RLIMIT_DATA
) >> PAGE_SHIFT
) {
3166 /* Workaround for Valgrind */
3167 if (rlimit(RLIMIT_DATA
) == 0 &&
3168 mm
->data_vm
+ npages
<= rlimit_max(RLIMIT_DATA
) >> PAGE_SHIFT
)
3170 if (!ignore_rlimit_data
) {
3171 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
3172 current
->comm
, current
->pid
,
3173 (mm
->data_vm
+ npages
) << PAGE_SHIFT
,
3174 rlimit(RLIMIT_DATA
));
3182 void vm_stat_account(struct mm_struct
*mm
, vm_flags_t flags
, long npages
)
3184 mm
->total_vm
+= npages
;
3186 if (is_exec_mapping(flags
))
3187 mm
->exec_vm
+= npages
;
3188 else if (is_stack_mapping(flags
))
3189 mm
->stack_vm
+= npages
;
3190 else if (is_data_mapping(flags
))
3191 mm
->data_vm
+= npages
;
3194 static int special_mapping_fault(struct vm_fault
*vmf
);
3197 * Having a close hook prevents vma merging regardless of flags.
3199 static void special_mapping_close(struct vm_area_struct
*vma
)
3203 static const char *special_mapping_name(struct vm_area_struct
*vma
)
3205 return ((struct vm_special_mapping
*)vma
->vm_private_data
)->name
;
3208 static int special_mapping_mremap(struct vm_area_struct
*new_vma
)
3210 struct vm_special_mapping
*sm
= new_vma
->vm_private_data
;
3212 if (WARN_ON_ONCE(current
->mm
!= new_vma
->vm_mm
))
3216 return sm
->mremap(sm
, new_vma
);
3221 static const struct vm_operations_struct special_mapping_vmops
= {
3222 .close
= special_mapping_close
,
3223 .fault
= special_mapping_fault
,
3224 .mremap
= special_mapping_mremap
,
3225 .name
= special_mapping_name
,
3228 static const struct vm_operations_struct legacy_special_mapping_vmops
= {
3229 .close
= special_mapping_close
,
3230 .fault
= special_mapping_fault
,
3233 static int special_mapping_fault(struct vm_fault
*vmf
)
3235 struct vm_area_struct
*vma
= vmf
->vma
;
3237 struct page
**pages
;
3239 if (vma
->vm_ops
== &legacy_special_mapping_vmops
) {
3240 pages
= vma
->vm_private_data
;
3242 struct vm_special_mapping
*sm
= vma
->vm_private_data
;
3245 return sm
->fault(sm
, vmf
->vma
, vmf
);
3250 for (pgoff
= vmf
->pgoff
; pgoff
&& *pages
; ++pages
)
3254 struct page
*page
= *pages
;
3260 return VM_FAULT_SIGBUS
;
3263 static struct vm_area_struct
*__install_special_mapping(
3264 struct mm_struct
*mm
,
3265 unsigned long addr
, unsigned long len
,
3266 unsigned long vm_flags
, void *priv
,
3267 const struct vm_operations_struct
*ops
)
3270 struct vm_area_struct
*vma
;
3272 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
3273 if (unlikely(vma
== NULL
))
3274 return ERR_PTR(-ENOMEM
);
3276 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
3278 vma
->vm_start
= addr
;
3279 vma
->vm_end
= addr
+ len
;
3281 vma
->vm_flags
= vm_flags
| mm
->def_flags
| VM_DONTEXPAND
| VM_SOFTDIRTY
;
3282 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
3285 vma
->vm_private_data
= priv
;
3287 ret
= insert_vm_struct(mm
, vma
);
3291 vm_stat_account(mm
, vma
->vm_flags
, len
>> PAGE_SHIFT
);
3293 perf_event_mmap(vma
);
3298 kmem_cache_free(vm_area_cachep
, vma
);
3299 return ERR_PTR(ret
);
3302 bool vma_is_special_mapping(const struct vm_area_struct
*vma
,
3303 const struct vm_special_mapping
*sm
)
3305 return vma
->vm_private_data
== sm
&&
3306 (vma
->vm_ops
== &special_mapping_vmops
||
3307 vma
->vm_ops
== &legacy_special_mapping_vmops
);
3311 * Called with mm->mmap_sem held for writing.
3312 * Insert a new vma covering the given region, with the given flags.
3313 * Its pages are supplied by the given array of struct page *.
3314 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3315 * The region past the last page supplied will always produce SIGBUS.
3316 * The array pointer and the pages it points to are assumed to stay alive
3317 * for as long as this mapping might exist.
3319 struct vm_area_struct
*_install_special_mapping(
3320 struct mm_struct
*mm
,
3321 unsigned long addr
, unsigned long len
,
3322 unsigned long vm_flags
, const struct vm_special_mapping
*spec
)
3324 return __install_special_mapping(mm
, addr
, len
, vm_flags
, (void *)spec
,
3325 &special_mapping_vmops
);
3328 int install_special_mapping(struct mm_struct
*mm
,
3329 unsigned long addr
, unsigned long len
,
3330 unsigned long vm_flags
, struct page
**pages
)
3332 struct vm_area_struct
*vma
= __install_special_mapping(
3333 mm
, addr
, len
, vm_flags
, (void *)pages
,
3334 &legacy_special_mapping_vmops
);
3336 return PTR_ERR_OR_ZERO(vma
);
3339 static DEFINE_MUTEX(mm_all_locks_mutex
);
3341 static void vm_lock_anon_vma(struct mm_struct
*mm
, struct anon_vma
*anon_vma
)
3343 if (!test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_root
.rb_node
)) {
3345 * The LSB of head.next can't change from under us
3346 * because we hold the mm_all_locks_mutex.
3348 down_write_nest_lock(&anon_vma
->root
->rwsem
, &mm
->mmap_sem
);
3350 * We can safely modify head.next after taking the
3351 * anon_vma->root->rwsem. If some other vma in this mm shares
3352 * the same anon_vma we won't take it again.
3354 * No need of atomic instructions here, head.next
3355 * can't change from under us thanks to the
3356 * anon_vma->root->rwsem.
3358 if (__test_and_set_bit(0, (unsigned long *)
3359 &anon_vma
->root
->rb_root
.rb_root
.rb_node
))
3364 static void vm_lock_mapping(struct mm_struct
*mm
, struct address_space
*mapping
)
3366 if (!test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3368 * AS_MM_ALL_LOCKS can't change from under us because
3369 * we hold the mm_all_locks_mutex.
3371 * Operations on ->flags have to be atomic because
3372 * even if AS_MM_ALL_LOCKS is stable thanks to the
3373 * mm_all_locks_mutex, there may be other cpus
3374 * changing other bitflags in parallel to us.
3376 if (test_and_set_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
))
3378 down_write_nest_lock(&mapping
->i_mmap_rwsem
, &mm
->mmap_sem
);
3383 * This operation locks against the VM for all pte/vma/mm related
3384 * operations that could ever happen on a certain mm. This includes
3385 * vmtruncate, try_to_unmap, and all page faults.
3387 * The caller must take the mmap_sem in write mode before calling
3388 * mm_take_all_locks(). The caller isn't allowed to release the
3389 * mmap_sem until mm_drop_all_locks() returns.
3391 * mmap_sem in write mode is required in order to block all operations
3392 * that could modify pagetables and free pages without need of
3393 * altering the vma layout. It's also needed in write mode to avoid new
3394 * anon_vmas to be associated with existing vmas.
3396 * A single task can't take more than one mm_take_all_locks() in a row
3397 * or it would deadlock.
3399 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3400 * mapping->flags avoid to take the same lock twice, if more than one
3401 * vma in this mm is backed by the same anon_vma or address_space.
3403 * We take locks in following order, accordingly to comment at beginning
3405 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3407 * - all i_mmap_rwsem locks;
3408 * - all anon_vma->rwseml
3410 * We can take all locks within these types randomly because the VM code
3411 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3412 * mm_all_locks_mutex.
3414 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3415 * that may have to take thousand of locks.
3417 * mm_take_all_locks() can fail if it's interrupted by signals.
3419 int mm_take_all_locks(struct mm_struct
*mm
)
3421 struct vm_area_struct
*vma
;
3422 struct anon_vma_chain
*avc
;
3424 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3426 mutex_lock(&mm_all_locks_mutex
);
3428 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3429 if (signal_pending(current
))
3431 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
3432 is_vm_hugetlb_page(vma
))
3433 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
3436 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3437 if (signal_pending(current
))
3439 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
3440 !is_vm_hugetlb_page(vma
))
3441 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
3444 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3445 if (signal_pending(current
))
3448 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3449 vm_lock_anon_vma(mm
, avc
->anon_vma
);
3455 mm_drop_all_locks(mm
);
3459 static void vm_unlock_anon_vma(struct anon_vma
*anon_vma
)
3461 if (test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_root
.rb_node
)) {
3463 * The LSB of head.next can't change to 0 from under
3464 * us because we hold the mm_all_locks_mutex.
3466 * We must however clear the bitflag before unlocking
3467 * the vma so the users using the anon_vma->rb_root will
3468 * never see our bitflag.
3470 * No need of atomic instructions here, head.next
3471 * can't change from under us until we release the
3472 * anon_vma->root->rwsem.
3474 if (!__test_and_clear_bit(0, (unsigned long *)
3475 &anon_vma
->root
->rb_root
.rb_root
.rb_node
))
3477 anon_vma_unlock_write(anon_vma
);
3481 static void vm_unlock_mapping(struct address_space
*mapping
)
3483 if (test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3485 * AS_MM_ALL_LOCKS can't change to 0 from under us
3486 * because we hold the mm_all_locks_mutex.
3488 i_mmap_unlock_write(mapping
);
3489 if (!test_and_clear_bit(AS_MM_ALL_LOCKS
,
3496 * The mmap_sem cannot be released by the caller until
3497 * mm_drop_all_locks() returns.
3499 void mm_drop_all_locks(struct mm_struct
*mm
)
3501 struct vm_area_struct
*vma
;
3502 struct anon_vma_chain
*avc
;
3504 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3505 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex
));
3507 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3509 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3510 vm_unlock_anon_vma(avc
->anon_vma
);
3511 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
3512 vm_unlock_mapping(vma
->vm_file
->f_mapping
);
3515 mutex_unlock(&mm_all_locks_mutex
);
3519 * initialise the percpu counter for VM
3521 void __init
mmap_init(void)
3525 ret
= percpu_counter_init(&vm_committed_as
, 0, GFP_KERNEL
);
3530 * Initialise sysctl_user_reserve_kbytes.
3532 * This is intended to prevent a user from starting a single memory hogging
3533 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3536 * The default value is min(3% of free memory, 128MB)
3537 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3539 static int init_user_reserve(void)
3541 unsigned long free_kbytes
;
3543 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3545 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
3548 subsys_initcall(init_user_reserve
);
3551 * Initialise sysctl_admin_reserve_kbytes.
3553 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3554 * to log in and kill a memory hogging process.
3556 * Systems with more than 256MB will reserve 8MB, enough to recover
3557 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3558 * only reserve 3% of free pages by default.
3560 static int init_admin_reserve(void)
3562 unsigned long free_kbytes
;
3564 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3566 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
3569 subsys_initcall(init_admin_reserve
);
3572 * Reinititalise user and admin reserves if memory is added or removed.
3574 * The default user reserve max is 128MB, and the default max for the
3575 * admin reserve is 8MB. These are usually, but not always, enough to
3576 * enable recovery from a memory hogging process using login/sshd, a shell,
3577 * and tools like top. It may make sense to increase or even disable the
3578 * reserve depending on the existence of swap or variations in the recovery
3579 * tools. So, the admin may have changed them.
3581 * If memory is added and the reserves have been eliminated or increased above
3582 * the default max, then we'll trust the admin.
3584 * If memory is removed and there isn't enough free memory, then we
3585 * need to reset the reserves.
3587 * Otherwise keep the reserve set by the admin.
3589 static int reserve_mem_notifier(struct notifier_block
*nb
,
3590 unsigned long action
, void *data
)
3592 unsigned long tmp
, free_kbytes
;
3596 /* Default max is 128MB. Leave alone if modified by operator. */
3597 tmp
= sysctl_user_reserve_kbytes
;
3598 if (0 < tmp
&& tmp
< (1UL << 17))
3599 init_user_reserve();
3601 /* Default max is 8MB. Leave alone if modified by operator. */
3602 tmp
= sysctl_admin_reserve_kbytes
;
3603 if (0 < tmp
&& tmp
< (1UL << 13))
3604 init_admin_reserve();
3608 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3610 if (sysctl_user_reserve_kbytes
> free_kbytes
) {
3611 init_user_reserve();
3612 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3613 sysctl_user_reserve_kbytes
);
3616 if (sysctl_admin_reserve_kbytes
> free_kbytes
) {
3617 init_admin_reserve();
3618 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3619 sysctl_admin_reserve_kbytes
);
3628 static struct notifier_block reserve_mem_nb
= {
3629 .notifier_call
= reserve_mem_notifier
,
3632 static int __meminit
init_reserve_notifier(void)
3634 if (register_hotmemory_notifier(&reserve_mem_nb
))
3635 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3639 subsys_initcall(init_reserve_notifier
);