6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/backing-dev.h>
13 #include <linux/shm.h>
14 #include <linux/mman.h>
15 #include <linux/pagemap.h>
16 #include <linux/swap.h>
17 #include <linux/syscalls.h>
18 #include <linux/capability.h>
19 #include <linux/init.h>
20 #include <linux/file.h>
22 #include <linux/personality.h>
23 #include <linux/security.h>
24 #include <linux/hugetlb.h>
25 #include <linux/profile.h>
26 #include <linux/export.h>
27 #include <linux/mount.h>
28 #include <linux/mempolicy.h>
29 #include <linux/rmap.h>
30 #include <linux/mmu_notifier.h>
31 #include <linux/perf_event.h>
32 #include <linux/audit.h>
33 #include <linux/khugepaged.h>
34 #include <linux/uprobes.h>
35 #include <linux/rbtree_augmented.h>
36 #include <linux/sched/sysctl.h>
37 #include <linux/notifier.h>
38 #include <linux/memory.h>
40 #include <asm/uaccess.h>
41 #include <asm/cacheflush.h>
43 #include <asm/mmu_context.h>
47 #ifndef arch_mmap_check
48 #define arch_mmap_check(addr, len, flags) (0)
51 #ifndef arch_rebalance_pgtables
52 #define arch_rebalance_pgtables(addr, len) (addr)
55 static void unmap_region(struct mm_struct
*mm
,
56 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
57 unsigned long start
, unsigned long end
);
59 /* description of effects of mapping type and prot in current implementation.
60 * this is due to the limited x86 page protection hardware. The expected
61 * behavior is in parens:
64 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
65 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
66 * w: (no) no w: (no) no w: (yes) yes w: (no) no
67 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
69 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
70 * w: (no) no w: (no) no w: (copy) copy w: (no) no
71 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
74 pgprot_t protection_map
[16] = {
75 __P000
, __P001
, __P010
, __P011
, __P100
, __P101
, __P110
, __P111
,
76 __S000
, __S001
, __S010
, __S011
, __S100
, __S101
, __S110
, __S111
79 pgprot_t
vm_get_page_prot(unsigned long vm_flags
)
81 return __pgprot(pgprot_val(protection_map
[vm_flags
&
82 (VM_READ
|VM_WRITE
|VM_EXEC
|VM_SHARED
)]) |
83 pgprot_val(arch_vm_get_page_prot(vm_flags
)));
85 EXPORT_SYMBOL(vm_get_page_prot
);
87 int sysctl_overcommit_memory __read_mostly
= OVERCOMMIT_GUESS
; /* heuristic overcommit */
88 int sysctl_overcommit_ratio __read_mostly
= 50; /* default is 50% */
89 int sysctl_max_map_count __read_mostly
= DEFAULT_MAX_MAP_COUNT
;
90 unsigned long sysctl_user_reserve_kbytes __read_mostly
= 1UL << 17; /* 128MB */
91 unsigned long sysctl_admin_reserve_kbytes __read_mostly
= 1UL << 13; /* 8MB */
93 * Make sure vm_committed_as in one cacheline and not cacheline shared with
94 * other variables. It can be updated by several CPUs frequently.
96 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp
;
99 * The global memory commitment made in the system can be a metric
100 * that can be used to drive ballooning decisions when Linux is hosted
101 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
102 * balancing memory across competing virtual machines that are hosted.
103 * Several metrics drive this policy engine including the guest reported
106 unsigned long vm_memory_committed(void)
108 return percpu_counter_read_positive(&vm_committed_as
);
110 EXPORT_SYMBOL_GPL(vm_memory_committed
);
113 * Check that a process has enough memory to allocate a new virtual
114 * mapping. 0 means there is enough memory for the allocation to
115 * succeed and -ENOMEM implies there is not.
117 * We currently support three overcommit policies, which are set via the
118 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
120 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
121 * Additional code 2002 Jul 20 by Robert Love.
123 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
125 * Note this is a helper function intended to be used by LSMs which
126 * wish to use this logic.
128 int __vm_enough_memory(struct mm_struct
*mm
, long pages
, int cap_sys_admin
)
130 unsigned long free
, allowed
, reserve
;
132 vm_acct_memory(pages
);
135 * Sometimes we want to use more memory than we have
137 if (sysctl_overcommit_memory
== OVERCOMMIT_ALWAYS
)
140 if (sysctl_overcommit_memory
== OVERCOMMIT_GUESS
) {
141 free
= global_page_state(NR_FREE_PAGES
);
142 free
+= global_page_state(NR_FILE_PAGES
);
145 * shmem pages shouldn't be counted as free in this
146 * case, they can't be purged, only swapped out, and
147 * that won't affect the overall amount of available
148 * memory in the system.
150 free
-= global_page_state(NR_SHMEM
);
152 free
+= get_nr_swap_pages();
155 * Any slabs which are created with the
156 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
157 * which are reclaimable, under pressure. The dentry
158 * cache and most inode caches should fall into this
160 free
+= global_page_state(NR_SLAB_RECLAIMABLE
);
163 * Leave reserved pages. The pages are not for anonymous pages.
165 if (free
<= totalreserve_pages
)
168 free
-= totalreserve_pages
;
171 * Reserve some for root
174 free
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
182 allowed
= (totalram_pages
- hugetlb_total_pages())
183 * sysctl_overcommit_ratio
/ 100;
185 * Reserve some for root
188 allowed
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
189 allowed
+= total_swap_pages
;
192 * Don't let a single process grow so big a user can't recover
195 reserve
= sysctl_user_reserve_kbytes
>> (PAGE_SHIFT
- 10);
196 allowed
-= min(mm
->total_vm
/ 32, reserve
);
199 if (percpu_counter_read_positive(&vm_committed_as
) < allowed
)
202 vm_unacct_memory(pages
);
208 * Requires inode->i_mapping->i_mmap_mutex
210 static void __remove_shared_vm_struct(struct vm_area_struct
*vma
,
211 struct file
*file
, struct address_space
*mapping
)
213 if (vma
->vm_flags
& VM_DENYWRITE
)
214 atomic_inc(&file_inode(file
)->i_writecount
);
215 if (vma
->vm_flags
& VM_SHARED
)
216 mapping
->i_mmap_writable
--;
218 flush_dcache_mmap_lock(mapping
);
219 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
220 list_del_init(&vma
->shared
.nonlinear
);
222 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
223 flush_dcache_mmap_unlock(mapping
);
227 * Unlink a file-based vm structure from its interval tree, to hide
228 * vma from rmap and vmtruncate before freeing its page tables.
230 void unlink_file_vma(struct vm_area_struct
*vma
)
232 struct file
*file
= vma
->vm_file
;
235 struct address_space
*mapping
= file
->f_mapping
;
236 mutex_lock(&mapping
->i_mmap_mutex
);
237 __remove_shared_vm_struct(vma
, file
, mapping
);
238 mutex_unlock(&mapping
->i_mmap_mutex
);
243 * Close a vm structure and free it, returning the next.
245 static struct vm_area_struct
*remove_vma(struct vm_area_struct
*vma
)
247 struct vm_area_struct
*next
= vma
->vm_next
;
250 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
251 vma
->vm_ops
->close(vma
);
254 mpol_put(vma_policy(vma
));
255 kmem_cache_free(vm_area_cachep
, vma
);
259 static unsigned long do_brk(unsigned long addr
, unsigned long len
);
261 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
263 unsigned long rlim
, retval
;
264 unsigned long newbrk
, oldbrk
;
265 struct mm_struct
*mm
= current
->mm
;
266 unsigned long min_brk
;
269 down_write(&mm
->mmap_sem
);
271 #ifdef CONFIG_COMPAT_BRK
273 * CONFIG_COMPAT_BRK can still be overridden by setting
274 * randomize_va_space to 2, which will still cause mm->start_brk
275 * to be arbitrarily shifted
277 if (current
->brk_randomized
)
278 min_brk
= mm
->start_brk
;
280 min_brk
= mm
->end_data
;
282 min_brk
= mm
->start_brk
;
288 * Check against rlimit here. If this check is done later after the test
289 * of oldbrk with newbrk then it can escape the test and let the data
290 * segment grow beyond its set limit the in case where the limit is
291 * not page aligned -Ram Gupta
293 rlim
= rlimit(RLIMIT_DATA
);
294 if (rlim
< RLIM_INFINITY
&& (brk
- mm
->start_brk
) +
295 (mm
->end_data
- mm
->start_data
) > rlim
)
298 newbrk
= PAGE_ALIGN(brk
);
299 oldbrk
= PAGE_ALIGN(mm
->brk
);
300 if (oldbrk
== newbrk
)
303 /* Always allow shrinking brk. */
304 if (brk
<= mm
->brk
) {
305 if (!do_munmap(mm
, newbrk
, oldbrk
-newbrk
))
310 /* Check against existing mmap mappings. */
311 if (find_vma_intersection(mm
, oldbrk
, newbrk
+PAGE_SIZE
))
314 /* Ok, looks good - let it rip. */
315 if (do_brk(oldbrk
, newbrk
-oldbrk
) != oldbrk
)
320 populate
= newbrk
> oldbrk
&& (mm
->def_flags
& VM_LOCKED
) != 0;
321 up_write(&mm
->mmap_sem
);
323 mm_populate(oldbrk
, newbrk
- oldbrk
);
328 up_write(&mm
->mmap_sem
);
332 static long vma_compute_subtree_gap(struct vm_area_struct
*vma
)
334 unsigned long max
, subtree_gap
;
337 max
-= vma
->vm_prev
->vm_end
;
338 if (vma
->vm_rb
.rb_left
) {
339 subtree_gap
= rb_entry(vma
->vm_rb
.rb_left
,
340 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
341 if (subtree_gap
> max
)
344 if (vma
->vm_rb
.rb_right
) {
345 subtree_gap
= rb_entry(vma
->vm_rb
.rb_right
,
346 struct vm_area_struct
, vm_rb
)->rb_subtree_gap
;
347 if (subtree_gap
> max
)
353 #ifdef CONFIG_DEBUG_VM_RB
354 static int browse_rb(struct rb_root
*root
)
356 int i
= 0, j
, bug
= 0;
357 struct rb_node
*nd
, *pn
= NULL
;
358 unsigned long prev
= 0, pend
= 0;
360 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
361 struct vm_area_struct
*vma
;
362 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
363 if (vma
->vm_start
< prev
) {
364 printk("vm_start %lx prev %lx\n", vma
->vm_start
, prev
);
367 if (vma
->vm_start
< pend
) {
368 printk("vm_start %lx pend %lx\n", vma
->vm_start
, pend
);
371 if (vma
->vm_start
> vma
->vm_end
) {
372 printk("vm_end %lx < vm_start %lx\n",
373 vma
->vm_end
, vma
->vm_start
);
376 if (vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
)) {
377 printk("free gap %lx, correct %lx\n",
379 vma_compute_subtree_gap(vma
));
384 prev
= vma
->vm_start
;
388 for (nd
= pn
; nd
; nd
= rb_prev(nd
))
391 printk("backwards %d, forwards %d\n", j
, i
);
397 static void validate_mm_rb(struct rb_root
*root
, struct vm_area_struct
*ignore
)
401 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
402 struct vm_area_struct
*vma
;
403 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
404 BUG_ON(vma
!= ignore
&&
405 vma
->rb_subtree_gap
!= vma_compute_subtree_gap(vma
));
409 void validate_mm(struct mm_struct
*mm
)
413 unsigned long highest_address
= 0;
414 struct vm_area_struct
*vma
= mm
->mmap
;
416 struct anon_vma_chain
*avc
;
417 vma_lock_anon_vma(vma
);
418 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
419 anon_vma_interval_tree_verify(avc
);
420 vma_unlock_anon_vma(vma
);
421 highest_address
= vma
->vm_end
;
425 if (i
!= mm
->map_count
) {
426 printk("map_count %d vm_next %d\n", mm
->map_count
, i
);
429 if (highest_address
!= mm
->highest_vm_end
) {
430 printk("mm->highest_vm_end %lx, found %lx\n",
431 mm
->highest_vm_end
, highest_address
);
434 i
= browse_rb(&mm
->mm_rb
);
435 if (i
!= mm
->map_count
) {
436 printk("map_count %d rb %d\n", mm
->map_count
, i
);
442 #define validate_mm_rb(root, ignore) do { } while (0)
443 #define validate_mm(mm) do { } while (0)
446 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks
, struct vm_area_struct
, vm_rb
,
447 unsigned long, rb_subtree_gap
, vma_compute_subtree_gap
)
450 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
451 * vma->vm_prev->vm_end values changed, without modifying the vma's position
454 static void vma_gap_update(struct vm_area_struct
*vma
)
457 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
458 * function that does exacltly what we want.
460 vma_gap_callbacks_propagate(&vma
->vm_rb
, NULL
);
463 static inline void vma_rb_insert(struct vm_area_struct
*vma
,
464 struct rb_root
*root
)
466 /* All rb_subtree_gap values must be consistent prior to insertion */
467 validate_mm_rb(root
, NULL
);
469 rb_insert_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
472 static void vma_rb_erase(struct vm_area_struct
*vma
, struct rb_root
*root
)
475 * All rb_subtree_gap values must be consistent prior to erase,
476 * with the possible exception of the vma being erased.
478 validate_mm_rb(root
, vma
);
481 * Note rb_erase_augmented is a fairly large inline function,
482 * so make sure we instantiate it only once with our desired
483 * augmented rbtree callbacks.
485 rb_erase_augmented(&vma
->vm_rb
, root
, &vma_gap_callbacks
);
489 * vma has some anon_vma assigned, and is already inserted on that
490 * anon_vma's interval trees.
492 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
493 * vma must be removed from the anon_vma's interval trees using
494 * anon_vma_interval_tree_pre_update_vma().
496 * After the update, the vma will be reinserted using
497 * anon_vma_interval_tree_post_update_vma().
499 * The entire update must be protected by exclusive mmap_sem and by
500 * the root anon_vma's mutex.
503 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct
*vma
)
505 struct anon_vma_chain
*avc
;
507 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
508 anon_vma_interval_tree_remove(avc
, &avc
->anon_vma
->rb_root
);
512 anon_vma_interval_tree_post_update_vma(struct vm_area_struct
*vma
)
514 struct anon_vma_chain
*avc
;
516 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
517 anon_vma_interval_tree_insert(avc
, &avc
->anon_vma
->rb_root
);
520 static int find_vma_links(struct mm_struct
*mm
, unsigned long addr
,
521 unsigned long end
, struct vm_area_struct
**pprev
,
522 struct rb_node
***rb_link
, struct rb_node
**rb_parent
)
524 struct rb_node
**__rb_link
, *__rb_parent
, *rb_prev
;
526 __rb_link
= &mm
->mm_rb
.rb_node
;
527 rb_prev
= __rb_parent
= NULL
;
530 struct vm_area_struct
*vma_tmp
;
532 __rb_parent
= *__rb_link
;
533 vma_tmp
= rb_entry(__rb_parent
, struct vm_area_struct
, vm_rb
);
535 if (vma_tmp
->vm_end
> addr
) {
536 /* Fail if an existing vma overlaps the area */
537 if (vma_tmp
->vm_start
< end
)
539 __rb_link
= &__rb_parent
->rb_left
;
541 rb_prev
= __rb_parent
;
542 __rb_link
= &__rb_parent
->rb_right
;
548 *pprev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
549 *rb_link
= __rb_link
;
550 *rb_parent
= __rb_parent
;
554 static unsigned long count_vma_pages_range(struct mm_struct
*mm
,
555 unsigned long addr
, unsigned long end
)
557 unsigned long nr_pages
= 0;
558 struct vm_area_struct
*vma
;
560 /* Find first overlaping mapping */
561 vma
= find_vma_intersection(mm
, addr
, end
);
565 nr_pages
= (min(end
, vma
->vm_end
) -
566 max(addr
, vma
->vm_start
)) >> PAGE_SHIFT
;
568 /* Iterate over the rest of the overlaps */
569 for (vma
= vma
->vm_next
; vma
; vma
= vma
->vm_next
) {
570 unsigned long overlap_len
;
572 if (vma
->vm_start
> end
)
575 overlap_len
= min(end
, vma
->vm_end
) - vma
->vm_start
;
576 nr_pages
+= overlap_len
>> PAGE_SHIFT
;
582 void __vma_link_rb(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
583 struct rb_node
**rb_link
, struct rb_node
*rb_parent
)
585 /* Update tracking information for the gap following the new vma. */
587 vma_gap_update(vma
->vm_next
);
589 mm
->highest_vm_end
= vma
->vm_end
;
592 * vma->vm_prev wasn't known when we followed the rbtree to find the
593 * correct insertion point for that vma. As a result, we could not
594 * update the vma vm_rb parents rb_subtree_gap values on the way down.
595 * So, we first insert the vma with a zero rb_subtree_gap value
596 * (to be consistent with what we did on the way down), and then
597 * immediately update the gap to the correct value. Finally we
598 * rebalance the rbtree after all augmented values have been set.
600 rb_link_node(&vma
->vm_rb
, rb_parent
, rb_link
);
601 vma
->rb_subtree_gap
= 0;
603 vma_rb_insert(vma
, &mm
->mm_rb
);
606 static void __vma_link_file(struct vm_area_struct
*vma
)
612 struct address_space
*mapping
= file
->f_mapping
;
614 if (vma
->vm_flags
& VM_DENYWRITE
)
615 atomic_dec(&file_inode(file
)->i_writecount
);
616 if (vma
->vm_flags
& VM_SHARED
)
617 mapping
->i_mmap_writable
++;
619 flush_dcache_mmap_lock(mapping
);
620 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
621 vma_nonlinear_insert(vma
, &mapping
->i_mmap_nonlinear
);
623 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
624 flush_dcache_mmap_unlock(mapping
);
629 __vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
630 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
631 struct rb_node
*rb_parent
)
633 __vma_link_list(mm
, vma
, prev
, rb_parent
);
634 __vma_link_rb(mm
, vma
, rb_link
, rb_parent
);
637 static void vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
638 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
639 struct rb_node
*rb_parent
)
641 struct address_space
*mapping
= NULL
;
644 mapping
= vma
->vm_file
->f_mapping
;
647 mutex_lock(&mapping
->i_mmap_mutex
);
649 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
650 __vma_link_file(vma
);
653 mutex_unlock(&mapping
->i_mmap_mutex
);
660 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
661 * mm's list and rbtree. It has already been inserted into the interval tree.
663 static void __insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
665 struct vm_area_struct
*prev
;
666 struct rb_node
**rb_link
, *rb_parent
;
668 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
669 &prev
, &rb_link
, &rb_parent
))
671 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
676 __vma_unlink(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
677 struct vm_area_struct
*prev
)
679 struct vm_area_struct
*next
;
681 vma_rb_erase(vma
, &mm
->mm_rb
);
682 prev
->vm_next
= next
= vma
->vm_next
;
684 next
->vm_prev
= prev
;
685 if (mm
->mmap_cache
== vma
)
686 mm
->mmap_cache
= prev
;
690 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
691 * is already present in an i_mmap tree without adjusting the tree.
692 * The following helper function should be used when such adjustments
693 * are necessary. The "insert" vma (if any) is to be inserted
694 * before we drop the necessary locks.
696 int vma_adjust(struct vm_area_struct
*vma
, unsigned long start
,
697 unsigned long end
, pgoff_t pgoff
, struct vm_area_struct
*insert
)
699 struct mm_struct
*mm
= vma
->vm_mm
;
700 struct vm_area_struct
*next
= vma
->vm_next
;
701 struct vm_area_struct
*importer
= NULL
;
702 struct address_space
*mapping
= NULL
;
703 struct rb_root
*root
= NULL
;
704 struct anon_vma
*anon_vma
= NULL
;
705 struct file
*file
= vma
->vm_file
;
706 bool start_changed
= false, end_changed
= false;
707 long adjust_next
= 0;
710 if (next
&& !insert
) {
711 struct vm_area_struct
*exporter
= NULL
;
713 if (end
>= next
->vm_end
) {
715 * vma expands, overlapping all the next, and
716 * perhaps the one after too (mprotect case 6).
718 again
: remove_next
= 1 + (end
> next
->vm_end
);
722 } else if (end
> next
->vm_start
) {
724 * vma expands, overlapping part of the next:
725 * mprotect case 5 shifting the boundary up.
727 adjust_next
= (end
- next
->vm_start
) >> PAGE_SHIFT
;
730 } else if (end
< vma
->vm_end
) {
732 * vma shrinks, and !insert tells it's not
733 * split_vma inserting another: so it must be
734 * mprotect case 4 shifting the boundary down.
736 adjust_next
= - ((vma
->vm_end
- end
) >> PAGE_SHIFT
);
742 * Easily overlooked: when mprotect shifts the boundary,
743 * make sure the expanding vma has anon_vma set if the
744 * shrinking vma had, to cover any anon pages imported.
746 if (exporter
&& exporter
->anon_vma
&& !importer
->anon_vma
) {
747 if (anon_vma_clone(importer
, exporter
))
749 importer
->anon_vma
= exporter
->anon_vma
;
754 mapping
= file
->f_mapping
;
755 if (!(vma
->vm_flags
& VM_NONLINEAR
)) {
756 root
= &mapping
->i_mmap
;
757 uprobe_munmap(vma
, vma
->vm_start
, vma
->vm_end
);
760 uprobe_munmap(next
, next
->vm_start
,
764 mutex_lock(&mapping
->i_mmap_mutex
);
767 * Put into interval tree now, so instantiated pages
768 * are visible to arm/parisc __flush_dcache_page
769 * throughout; but we cannot insert into address
770 * space until vma start or end is updated.
772 __vma_link_file(insert
);
776 vma_adjust_trans_huge(vma
, start
, end
, adjust_next
);
778 anon_vma
= vma
->anon_vma
;
779 if (!anon_vma
&& adjust_next
)
780 anon_vma
= next
->anon_vma
;
782 VM_BUG_ON(adjust_next
&& next
->anon_vma
&&
783 anon_vma
!= next
->anon_vma
);
784 anon_vma_lock_write(anon_vma
);
785 anon_vma_interval_tree_pre_update_vma(vma
);
787 anon_vma_interval_tree_pre_update_vma(next
);
791 flush_dcache_mmap_lock(mapping
);
792 vma_interval_tree_remove(vma
, root
);
794 vma_interval_tree_remove(next
, root
);
797 if (start
!= vma
->vm_start
) {
798 vma
->vm_start
= start
;
799 start_changed
= true;
801 if (end
!= vma
->vm_end
) {
805 vma
->vm_pgoff
= pgoff
;
807 next
->vm_start
+= adjust_next
<< PAGE_SHIFT
;
808 next
->vm_pgoff
+= adjust_next
;
813 vma_interval_tree_insert(next
, root
);
814 vma_interval_tree_insert(vma
, root
);
815 flush_dcache_mmap_unlock(mapping
);
820 * vma_merge has merged next into vma, and needs
821 * us to remove next before dropping the locks.
823 __vma_unlink(mm
, next
, vma
);
825 __remove_shared_vm_struct(next
, file
, mapping
);
828 * split_vma has split insert from vma, and needs
829 * us to insert it before dropping the locks
830 * (it may either follow vma or precede it).
832 __insert_vm_struct(mm
, insert
);
838 mm
->highest_vm_end
= end
;
839 else if (!adjust_next
)
840 vma_gap_update(next
);
845 anon_vma_interval_tree_post_update_vma(vma
);
847 anon_vma_interval_tree_post_update_vma(next
);
848 anon_vma_unlock_write(anon_vma
);
851 mutex_unlock(&mapping
->i_mmap_mutex
);
862 uprobe_munmap(next
, next
->vm_start
, next
->vm_end
);
866 anon_vma_merge(vma
, next
);
868 vma_set_policy(vma
, vma_policy(next
));
869 kmem_cache_free(vm_area_cachep
, next
);
871 * In mprotect's case 6 (see comments on vma_merge),
872 * we must remove another next too. It would clutter
873 * up the code too much to do both in one go.
876 if (remove_next
== 2)
879 vma_gap_update(next
);
881 mm
->highest_vm_end
= end
;
892 * If the vma has a ->close operation then the driver probably needs to release
893 * per-vma resources, so we don't attempt to merge those.
895 static inline int is_mergeable_vma(struct vm_area_struct
*vma
,
896 struct file
*file
, unsigned long vm_flags
)
898 if (vma
->vm_flags
^ vm_flags
)
900 if (vma
->vm_file
!= file
)
902 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
907 static inline int is_mergeable_anon_vma(struct anon_vma
*anon_vma1
,
908 struct anon_vma
*anon_vma2
,
909 struct vm_area_struct
*vma
)
912 * The list_is_singular() test is to avoid merging VMA cloned from
913 * parents. This can improve scalability caused by anon_vma lock.
915 if ((!anon_vma1
|| !anon_vma2
) && (!vma
||
916 list_is_singular(&vma
->anon_vma_chain
)))
918 return anon_vma1
== anon_vma2
;
922 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
923 * in front of (at a lower virtual address and file offset than) the vma.
925 * We cannot merge two vmas if they have differently assigned (non-NULL)
926 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
928 * We don't check here for the merged mmap wrapping around the end of pagecache
929 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
930 * wrap, nor mmaps which cover the final page at index -1UL.
933 can_vma_merge_before(struct vm_area_struct
*vma
, unsigned long vm_flags
,
934 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
936 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
937 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
938 if (vma
->vm_pgoff
== vm_pgoff
)
945 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
946 * beyond (at a higher virtual address and file offset than) the vma.
948 * We cannot merge two vmas if they have differently assigned (non-NULL)
949 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
952 can_vma_merge_after(struct vm_area_struct
*vma
, unsigned long vm_flags
,
953 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
955 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
956 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
958 vm_pglen
= (vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
;
959 if (vma
->vm_pgoff
+ vm_pglen
== vm_pgoff
)
966 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
967 * whether that can be merged with its predecessor or its successor.
968 * Or both (it neatly fills a hole).
970 * In most cases - when called for mmap, brk or mremap - [addr,end) is
971 * certain not to be mapped by the time vma_merge is called; but when
972 * called for mprotect, it is certain to be already mapped (either at
973 * an offset within prev, or at the start of next), and the flags of
974 * this area are about to be changed to vm_flags - and the no-change
975 * case has already been eliminated.
977 * The following mprotect cases have to be considered, where AAAA is
978 * the area passed down from mprotect_fixup, never extending beyond one
979 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
981 * AAAA AAAA AAAA AAAA
982 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
983 * cannot merge might become might become might become
984 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
985 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
986 * mremap move: PPPPNNNNNNNN 8
988 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
989 * might become case 1 below case 2 below case 3 below
991 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
992 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
994 struct vm_area_struct
*vma_merge(struct mm_struct
*mm
,
995 struct vm_area_struct
*prev
, unsigned long addr
,
996 unsigned long end
, unsigned long vm_flags
,
997 struct anon_vma
*anon_vma
, struct file
*file
,
998 pgoff_t pgoff
, struct mempolicy
*policy
)
1000 pgoff_t pglen
= (end
- addr
) >> PAGE_SHIFT
;
1001 struct vm_area_struct
*area
, *next
;
1005 * We later require that vma->vm_flags == vm_flags,
1006 * so this tests vma->vm_flags & VM_SPECIAL, too.
1008 if (vm_flags
& VM_SPECIAL
)
1012 next
= prev
->vm_next
;
1016 if (next
&& next
->vm_end
== end
) /* cases 6, 7, 8 */
1017 next
= next
->vm_next
;
1020 * Can it merge with the predecessor?
1022 if (prev
&& prev
->vm_end
== addr
&&
1023 mpol_equal(vma_policy(prev
), policy
) &&
1024 can_vma_merge_after(prev
, vm_flags
,
1025 anon_vma
, file
, pgoff
)) {
1027 * OK, it can. Can we now merge in the successor as well?
1029 if (next
&& end
== next
->vm_start
&&
1030 mpol_equal(policy
, vma_policy(next
)) &&
1031 can_vma_merge_before(next
, vm_flags
,
1032 anon_vma
, file
, pgoff
+pglen
) &&
1033 is_mergeable_anon_vma(prev
->anon_vma
,
1034 next
->anon_vma
, NULL
)) {
1036 err
= vma_adjust(prev
, prev
->vm_start
,
1037 next
->vm_end
, prev
->vm_pgoff
, NULL
);
1038 } else /* cases 2, 5, 7 */
1039 err
= vma_adjust(prev
, prev
->vm_start
,
1040 end
, prev
->vm_pgoff
, NULL
);
1043 khugepaged_enter_vma_merge(prev
);
1048 * Can this new request be merged in front of next?
1050 if (next
&& end
== next
->vm_start
&&
1051 mpol_equal(policy
, vma_policy(next
)) &&
1052 can_vma_merge_before(next
, vm_flags
,
1053 anon_vma
, file
, pgoff
+pglen
)) {
1054 if (prev
&& addr
< prev
->vm_end
) /* case 4 */
1055 err
= vma_adjust(prev
, prev
->vm_start
,
1056 addr
, prev
->vm_pgoff
, NULL
);
1057 else /* cases 3, 8 */
1058 err
= vma_adjust(area
, addr
, next
->vm_end
,
1059 next
->vm_pgoff
- pglen
, NULL
);
1062 khugepaged_enter_vma_merge(area
);
1070 * Rough compatbility check to quickly see if it's even worth looking
1071 * at sharing an anon_vma.
1073 * They need to have the same vm_file, and the flags can only differ
1074 * in things that mprotect may change.
1076 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1077 * we can merge the two vma's. For example, we refuse to merge a vma if
1078 * there is a vm_ops->close() function, because that indicates that the
1079 * driver is doing some kind of reference counting. But that doesn't
1080 * really matter for the anon_vma sharing case.
1082 static int anon_vma_compatible(struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1084 return a
->vm_end
== b
->vm_start
&&
1085 mpol_equal(vma_policy(a
), vma_policy(b
)) &&
1086 a
->vm_file
== b
->vm_file
&&
1087 !((a
->vm_flags
^ b
->vm_flags
) & ~(VM_READ
|VM_WRITE
|VM_EXEC
)) &&
1088 b
->vm_pgoff
== a
->vm_pgoff
+ ((b
->vm_start
- a
->vm_start
) >> PAGE_SHIFT
);
1092 * Do some basic sanity checking to see if we can re-use the anon_vma
1093 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1094 * the same as 'old', the other will be the new one that is trying
1095 * to share the anon_vma.
1097 * NOTE! This runs with mm_sem held for reading, so it is possible that
1098 * the anon_vma of 'old' is concurrently in the process of being set up
1099 * by another page fault trying to merge _that_. But that's ok: if it
1100 * is being set up, that automatically means that it will be a singleton
1101 * acceptable for merging, so we can do all of this optimistically. But
1102 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
1104 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1105 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1106 * is to return an anon_vma that is "complex" due to having gone through
1109 * We also make sure that the two vma's are compatible (adjacent,
1110 * and with the same memory policies). That's all stable, even with just
1111 * a read lock on the mm_sem.
1113 static struct anon_vma
*reusable_anon_vma(struct vm_area_struct
*old
, struct vm_area_struct
*a
, struct vm_area_struct
*b
)
1115 if (anon_vma_compatible(a
, b
)) {
1116 struct anon_vma
*anon_vma
= ACCESS_ONCE(old
->anon_vma
);
1118 if (anon_vma
&& list_is_singular(&old
->anon_vma_chain
))
1125 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1126 * neighbouring vmas for a suitable anon_vma, before it goes off
1127 * to allocate a new anon_vma. It checks because a repetitive
1128 * sequence of mprotects and faults may otherwise lead to distinct
1129 * anon_vmas being allocated, preventing vma merge in subsequent
1132 struct anon_vma
*find_mergeable_anon_vma(struct vm_area_struct
*vma
)
1134 struct anon_vma
*anon_vma
;
1135 struct vm_area_struct
*near
;
1137 near
= vma
->vm_next
;
1141 anon_vma
= reusable_anon_vma(near
, vma
, near
);
1145 near
= vma
->vm_prev
;
1149 anon_vma
= reusable_anon_vma(near
, near
, vma
);
1154 * There's no absolute need to look only at touching neighbours:
1155 * we could search further afield for "compatible" anon_vmas.
1156 * But it would probably just be a waste of time searching,
1157 * or lead to too many vmas hanging off the same anon_vma.
1158 * We're trying to allow mprotect remerging later on,
1159 * not trying to minimize memory used for anon_vmas.
1164 #ifdef CONFIG_PROC_FS
1165 void vm_stat_account(struct mm_struct
*mm
, unsigned long flags
,
1166 struct file
*file
, long pages
)
1168 const unsigned long stack_flags
1169 = VM_STACK_FLAGS
& (VM_GROWSUP
|VM_GROWSDOWN
);
1171 mm
->total_vm
+= pages
;
1174 mm
->shared_vm
+= pages
;
1175 if ((flags
& (VM_EXEC
|VM_WRITE
)) == VM_EXEC
)
1176 mm
->exec_vm
+= pages
;
1177 } else if (flags
& stack_flags
)
1178 mm
->stack_vm
+= pages
;
1180 #endif /* CONFIG_PROC_FS */
1183 * If a hint addr is less than mmap_min_addr change hint to be as
1184 * low as possible but still greater than mmap_min_addr
1186 static inline unsigned long round_hint_to_min(unsigned long hint
)
1189 if (((void *)hint
!= NULL
) &&
1190 (hint
< mmap_min_addr
))
1191 return PAGE_ALIGN(mmap_min_addr
);
1196 * The caller must hold down_write(¤t->mm->mmap_sem).
1199 unsigned long do_mmap_pgoff(struct file
*file
, unsigned long addr
,
1200 unsigned long len
, unsigned long prot
,
1201 unsigned long flags
, unsigned long pgoff
,
1202 unsigned long *populate
)
1204 struct mm_struct
* mm
= current
->mm
;
1205 struct inode
*inode
;
1206 vm_flags_t vm_flags
;
1211 * Does the application expect PROT_READ to imply PROT_EXEC?
1213 * (the exception is when the underlying filesystem is noexec
1214 * mounted, in which case we dont add PROT_EXEC.)
1216 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
1217 if (!(file
&& (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
)))
1223 if (!(flags
& MAP_FIXED
))
1224 addr
= round_hint_to_min(addr
);
1226 /* Careful about overflows.. */
1227 len
= PAGE_ALIGN(len
);
1231 /* offset overflow? */
1232 if ((pgoff
+ (len
>> PAGE_SHIFT
)) < pgoff
)
1235 /* Too many mappings? */
1236 if (mm
->map_count
> sysctl_max_map_count
)
1239 /* Obtain the address to map to. we verify (or select) it and ensure
1240 * that it represents a valid section of the address space.
1242 addr
= get_unmapped_area(file
, addr
, len
, pgoff
, flags
);
1243 if (addr
& ~PAGE_MASK
)
1246 /* Do simple checking here so the lower-level routines won't have
1247 * to. we assume access permissions have been handled by the open
1248 * of the memory object, so we don't do any here.
1250 vm_flags
= calc_vm_prot_bits(prot
) | calc_vm_flag_bits(flags
) |
1251 mm
->def_flags
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1253 if (flags
& MAP_LOCKED
)
1254 if (!can_do_mlock())
1257 /* mlock MCL_FUTURE? */
1258 if (vm_flags
& VM_LOCKED
) {
1259 unsigned long locked
, lock_limit
;
1260 locked
= len
>> PAGE_SHIFT
;
1261 locked
+= mm
->locked_vm
;
1262 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
1263 lock_limit
>>= PAGE_SHIFT
;
1264 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
1268 inode
= file
? file_inode(file
) : NULL
;
1271 switch (flags
& MAP_TYPE
) {
1273 if ((prot
&PROT_WRITE
) && !(file
->f_mode
&FMODE_WRITE
))
1277 * Make sure we don't allow writing to an append-only
1280 if (IS_APPEND(inode
) && (file
->f_mode
& FMODE_WRITE
))
1284 * Make sure there are no mandatory locks on the file.
1286 if (locks_verify_locked(inode
))
1289 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1290 if (!(file
->f_mode
& FMODE_WRITE
))
1291 vm_flags
&= ~(VM_MAYWRITE
| VM_SHARED
);
1295 if (!(file
->f_mode
& FMODE_READ
))
1297 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
) {
1298 if (vm_flags
& VM_EXEC
)
1300 vm_flags
&= ~VM_MAYEXEC
;
1303 if (!file
->f_op
|| !file
->f_op
->mmap
)
1311 switch (flags
& MAP_TYPE
) {
1317 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1321 * Set pgoff according to addr for anon_vma.
1323 pgoff
= addr
>> PAGE_SHIFT
;
1331 * Set 'VM_NORESERVE' if we should not account for the
1332 * memory use of this mapping.
1334 if (flags
& MAP_NORESERVE
) {
1335 /* We honor MAP_NORESERVE if allowed to overcommit */
1336 if (sysctl_overcommit_memory
!= OVERCOMMIT_NEVER
)
1337 vm_flags
|= VM_NORESERVE
;
1339 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1340 if (file
&& is_file_hugepages(file
))
1341 vm_flags
|= VM_NORESERVE
;
1344 addr
= mmap_region(file
, addr
, len
, vm_flags
, pgoff
);
1345 if (!IS_ERR_VALUE(addr
) &&
1346 ((vm_flags
& VM_LOCKED
) ||
1347 (flags
& (MAP_POPULATE
| MAP_NONBLOCK
)) == MAP_POPULATE
))
1352 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1353 unsigned long, prot
, unsigned long, flags
,
1354 unsigned long, fd
, unsigned long, pgoff
)
1356 struct file
*file
= NULL
;
1357 unsigned long retval
= -EBADF
;
1359 if (!(flags
& MAP_ANONYMOUS
)) {
1360 audit_mmap_fd(fd
, flags
);
1361 if (unlikely(flags
& MAP_HUGETLB
))
1366 } else if (flags
& MAP_HUGETLB
) {
1367 struct user_struct
*user
= NULL
;
1369 * VM_NORESERVE is used because the reservations will be
1370 * taken when vm_ops->mmap() is called
1371 * A dummy user value is used because we are not locking
1372 * memory so no accounting is necessary
1374 file
= hugetlb_file_setup(HUGETLB_ANON_FILE
, addr
, len
,
1376 &user
, HUGETLB_ANONHUGE_INODE
,
1377 (flags
>> MAP_HUGE_SHIFT
) & MAP_HUGE_MASK
);
1379 return PTR_ERR(file
);
1382 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1384 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1391 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1392 struct mmap_arg_struct
{
1396 unsigned long flags
;
1398 unsigned long offset
;
1401 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1403 struct mmap_arg_struct a
;
1405 if (copy_from_user(&a
, arg
, sizeof(a
)))
1407 if (a
.offset
& ~PAGE_MASK
)
1410 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1411 a
.offset
>> PAGE_SHIFT
);
1413 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1416 * Some shared mappigns will want the pages marked read-only
1417 * to track write events. If so, we'll downgrade vm_page_prot
1418 * to the private version (using protection_map[] without the
1421 int vma_wants_writenotify(struct vm_area_struct
*vma
)
1423 vm_flags_t vm_flags
= vma
->vm_flags
;
1425 /* If it was private or non-writable, the write bit is already clear */
1426 if ((vm_flags
& (VM_WRITE
|VM_SHARED
)) != ((VM_WRITE
|VM_SHARED
)))
1429 /* The backer wishes to know when pages are first written to? */
1430 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
)
1433 /* The open routine did something to the protections already? */
1434 if (pgprot_val(vma
->vm_page_prot
) !=
1435 pgprot_val(vm_get_page_prot(vm_flags
)))
1438 /* Specialty mapping? */
1439 if (vm_flags
& VM_PFNMAP
)
1442 /* Can the mapping track the dirty pages? */
1443 return vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
1444 mapping_cap_account_dirty(vma
->vm_file
->f_mapping
);
1448 * We account for memory if it's a private writeable mapping,
1449 * not hugepages and VM_NORESERVE wasn't set.
1451 static inline int accountable_mapping(struct file
*file
, vm_flags_t vm_flags
)
1454 * hugetlb has its own accounting separate from the core VM
1455 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1457 if (file
&& is_file_hugepages(file
))
1460 return (vm_flags
& (VM_NORESERVE
| VM_SHARED
| VM_WRITE
)) == VM_WRITE
;
1463 unsigned long mmap_region(struct file
*file
, unsigned long addr
,
1464 unsigned long len
, vm_flags_t vm_flags
, unsigned long pgoff
)
1466 struct mm_struct
*mm
= current
->mm
;
1467 struct vm_area_struct
*vma
, *prev
;
1468 int correct_wcount
= 0;
1470 struct rb_node
**rb_link
, *rb_parent
;
1471 unsigned long charged
= 0;
1472 struct inode
*inode
= file
? file_inode(file
) : NULL
;
1474 /* Check against address space limit. */
1475 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
)) {
1476 unsigned long nr_pages
;
1479 * MAP_FIXED may remove pages of mappings that intersects with
1480 * requested mapping. Account for the pages it would unmap.
1482 if (!(vm_flags
& MAP_FIXED
))
1485 nr_pages
= count_vma_pages_range(mm
, addr
, addr
+ len
);
1487 if (!may_expand_vm(mm
, (len
>> PAGE_SHIFT
) - nr_pages
))
1491 /* Clear old maps */
1494 if (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
, &rb_parent
)) {
1495 if (do_munmap(mm
, addr
, len
))
1501 * Private writable mapping: check memory availability
1503 if (accountable_mapping(file
, vm_flags
)) {
1504 charged
= len
>> PAGE_SHIFT
;
1505 if (security_vm_enough_memory_mm(mm
, charged
))
1507 vm_flags
|= VM_ACCOUNT
;
1511 * Can we just expand an old mapping?
1513 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vm_flags
, NULL
, file
, pgoff
, NULL
);
1518 * Determine the object being mapped and call the appropriate
1519 * specific mapper. the address has already been validated, but
1520 * not unmapped, but the maps are removed from the list.
1522 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1529 vma
->vm_start
= addr
;
1530 vma
->vm_end
= addr
+ len
;
1531 vma
->vm_flags
= vm_flags
;
1532 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
);
1533 vma
->vm_pgoff
= pgoff
;
1534 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1536 error
= -EINVAL
; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */
1539 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1541 if (vm_flags
& VM_DENYWRITE
) {
1542 error
= deny_write_access(file
);
1547 vma
->vm_file
= get_file(file
);
1548 error
= file
->f_op
->mmap(file
, vma
);
1550 goto unmap_and_free_vma
;
1552 /* Can addr have changed??
1554 * Answer: Yes, several device drivers can do it in their
1555 * f_op->mmap method. -DaveM
1556 * Bug: If addr is changed, prev, rb_link, rb_parent should
1557 * be updated for vma_link()
1559 WARN_ON_ONCE(addr
!= vma
->vm_start
);
1561 addr
= vma
->vm_start
;
1562 pgoff
= vma
->vm_pgoff
;
1563 vm_flags
= vma
->vm_flags
;
1564 } else if (vm_flags
& VM_SHARED
) {
1565 if (unlikely(vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
)))
1567 error
= shmem_zero_setup(vma
);
1572 if (vma_wants_writenotify(vma
)) {
1573 pgprot_t pprot
= vma
->vm_page_prot
;
1575 /* Can vma->vm_page_prot have changed??
1577 * Answer: Yes, drivers may have changed it in their
1578 * f_op->mmap method.
1580 * Ensures that vmas marked as uncached stay that way.
1582 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
& ~VM_SHARED
);
1583 if (pgprot_val(pprot
) == pgprot_val(pgprot_noncached(pprot
)))
1584 vma
->vm_page_prot
= pgprot_noncached(vma
->vm_page_prot
);
1587 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
1588 file
= vma
->vm_file
;
1590 /* Once vma denies write, undo our temporary denial count */
1592 atomic_inc(&inode
->i_writecount
);
1594 perf_event_mmap(vma
);
1596 vm_stat_account(mm
, vm_flags
, file
, len
>> PAGE_SHIFT
);
1597 if (vm_flags
& VM_LOCKED
) {
1598 if (!((vm_flags
& VM_SPECIAL
) || is_vm_hugetlb_page(vma
) ||
1599 vma
== get_gate_vma(current
->mm
)))
1600 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
1602 vma
->vm_flags
&= ~VM_LOCKED
;
1612 atomic_inc(&inode
->i_writecount
);
1613 vma
->vm_file
= NULL
;
1616 /* Undo any partial mapping done by a device driver. */
1617 unmap_region(mm
, vma
, prev
, vma
->vm_start
, vma
->vm_end
);
1620 kmem_cache_free(vm_area_cachep
, vma
);
1623 vm_unacct_memory(charged
);
1627 unsigned long unmapped_area(struct vm_unmapped_area_info
*info
)
1630 * We implement the search by looking for an rbtree node that
1631 * immediately follows a suitable gap. That is,
1632 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1633 * - gap_end = vma->vm_start >= info->low_limit + length;
1634 * - gap_end - gap_start >= length
1637 struct mm_struct
*mm
= current
->mm
;
1638 struct vm_area_struct
*vma
;
1639 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1641 /* Adjust search length to account for worst case alignment overhead */
1642 length
= info
->length
+ info
->align_mask
;
1643 if (length
< info
->length
)
1646 /* Adjust search limits by the desired length */
1647 if (info
->high_limit
< length
)
1649 high_limit
= info
->high_limit
- length
;
1651 if (info
->low_limit
> high_limit
)
1653 low_limit
= info
->low_limit
+ length
;
1655 /* Check if rbtree root looks promising */
1656 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1658 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1659 if (vma
->rb_subtree_gap
< length
)
1663 /* Visit left subtree if it looks promising */
1664 gap_end
= vma
->vm_start
;
1665 if (gap_end
>= low_limit
&& vma
->vm_rb
.rb_left
) {
1666 struct vm_area_struct
*left
=
1667 rb_entry(vma
->vm_rb
.rb_left
,
1668 struct vm_area_struct
, vm_rb
);
1669 if (left
->rb_subtree_gap
>= length
) {
1675 gap_start
= vma
->vm_prev
? vma
->vm_prev
->vm_end
: 0;
1677 /* Check if current node has a suitable gap */
1678 if (gap_start
> high_limit
)
1680 if (gap_end
>= low_limit
&& gap_end
- gap_start
>= length
)
1683 /* Visit right subtree if it looks promising */
1684 if (vma
->vm_rb
.rb_right
) {
1685 struct vm_area_struct
*right
=
1686 rb_entry(vma
->vm_rb
.rb_right
,
1687 struct vm_area_struct
, vm_rb
);
1688 if (right
->rb_subtree_gap
>= length
) {
1694 /* Go back up the rbtree to find next candidate node */
1696 struct rb_node
*prev
= &vma
->vm_rb
;
1697 if (!rb_parent(prev
))
1699 vma
= rb_entry(rb_parent(prev
),
1700 struct vm_area_struct
, vm_rb
);
1701 if (prev
== vma
->vm_rb
.rb_left
) {
1702 gap_start
= vma
->vm_prev
->vm_end
;
1703 gap_end
= vma
->vm_start
;
1710 /* Check highest gap, which does not precede any rbtree node */
1711 gap_start
= mm
->highest_vm_end
;
1712 gap_end
= ULONG_MAX
; /* Only for VM_BUG_ON below */
1713 if (gap_start
> high_limit
)
1717 /* We found a suitable gap. Clip it with the original low_limit. */
1718 if (gap_start
< info
->low_limit
)
1719 gap_start
= info
->low_limit
;
1721 /* Adjust gap address to the desired alignment */
1722 gap_start
+= (info
->align_offset
- gap_start
) & info
->align_mask
;
1724 VM_BUG_ON(gap_start
+ info
->length
> info
->high_limit
);
1725 VM_BUG_ON(gap_start
+ info
->length
> gap_end
);
1729 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info
*info
)
1731 struct mm_struct
*mm
= current
->mm
;
1732 struct vm_area_struct
*vma
;
1733 unsigned long length
, low_limit
, high_limit
, gap_start
, gap_end
;
1735 /* Adjust search length to account for worst case alignment overhead */
1736 length
= info
->length
+ info
->align_mask
;
1737 if (length
< info
->length
)
1741 * Adjust search limits by the desired length.
1742 * See implementation comment at top of unmapped_area().
1744 gap_end
= info
->high_limit
;
1745 if (gap_end
< length
)
1747 high_limit
= gap_end
- length
;
1749 if (info
->low_limit
> high_limit
)
1751 low_limit
= info
->low_limit
+ length
;
1753 /* Check highest gap, which does not precede any rbtree node */
1754 gap_start
= mm
->highest_vm_end
;
1755 if (gap_start
<= high_limit
)
1758 /* Check if rbtree root looks promising */
1759 if (RB_EMPTY_ROOT(&mm
->mm_rb
))
1761 vma
= rb_entry(mm
->mm_rb
.rb_node
, struct vm_area_struct
, vm_rb
);
1762 if (vma
->rb_subtree_gap
< length
)
1766 /* Visit right subtree if it looks promising */
1767 gap_start
= vma
->vm_prev
? vma
->vm_prev
->vm_end
: 0;
1768 if (gap_start
<= high_limit
&& vma
->vm_rb
.rb_right
) {
1769 struct vm_area_struct
*right
=
1770 rb_entry(vma
->vm_rb
.rb_right
,
1771 struct vm_area_struct
, vm_rb
);
1772 if (right
->rb_subtree_gap
>= length
) {
1779 /* Check if current node has a suitable gap */
1780 gap_end
= vma
->vm_start
;
1781 if (gap_end
< low_limit
)
1783 if (gap_start
<= high_limit
&& gap_end
- gap_start
>= length
)
1786 /* Visit left subtree if it looks promising */
1787 if (vma
->vm_rb
.rb_left
) {
1788 struct vm_area_struct
*left
=
1789 rb_entry(vma
->vm_rb
.rb_left
,
1790 struct vm_area_struct
, vm_rb
);
1791 if (left
->rb_subtree_gap
>= length
) {
1797 /* Go back up the rbtree to find next candidate node */
1799 struct rb_node
*prev
= &vma
->vm_rb
;
1800 if (!rb_parent(prev
))
1802 vma
= rb_entry(rb_parent(prev
),
1803 struct vm_area_struct
, vm_rb
);
1804 if (prev
== vma
->vm_rb
.rb_right
) {
1805 gap_start
= vma
->vm_prev
?
1806 vma
->vm_prev
->vm_end
: 0;
1813 /* We found a suitable gap. Clip it with the original high_limit. */
1814 if (gap_end
> info
->high_limit
)
1815 gap_end
= info
->high_limit
;
1818 /* Compute highest gap address at the desired alignment */
1819 gap_end
-= info
->length
;
1820 gap_end
-= (gap_end
- info
->align_offset
) & info
->align_mask
;
1822 VM_BUG_ON(gap_end
< info
->low_limit
);
1823 VM_BUG_ON(gap_end
< gap_start
);
1827 /* Get an address range which is currently unmapped.
1828 * For shmat() with addr=0.
1830 * Ugly calling convention alert:
1831 * Return value with the low bits set means error value,
1833 * if (ret & ~PAGE_MASK)
1836 * This function "knows" that -ENOMEM has the bits set.
1838 #ifndef HAVE_ARCH_UNMAPPED_AREA
1840 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
1841 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1843 struct mm_struct
*mm
= current
->mm
;
1844 struct vm_area_struct
*vma
;
1845 struct vm_unmapped_area_info info
;
1847 if (len
> TASK_SIZE
)
1850 if (flags
& MAP_FIXED
)
1854 addr
= PAGE_ALIGN(addr
);
1855 vma
= find_vma(mm
, addr
);
1856 if (TASK_SIZE
- len
>= addr
&&
1857 (!vma
|| addr
+ len
<= vma
->vm_start
))
1863 info
.low_limit
= TASK_UNMAPPED_BASE
;
1864 info
.high_limit
= TASK_SIZE
;
1865 info
.align_mask
= 0;
1866 return vm_unmapped_area(&info
);
1870 void arch_unmap_area(struct mm_struct
*mm
, unsigned long addr
)
1873 * Is this a new hole at the lowest possible address?
1875 if (addr
>= TASK_UNMAPPED_BASE
&& addr
< mm
->free_area_cache
)
1876 mm
->free_area_cache
= addr
;
1880 * This mmap-allocator allocates new areas top-down from below the
1881 * stack's low limit (the base):
1883 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1885 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
1886 const unsigned long len
, const unsigned long pgoff
,
1887 const unsigned long flags
)
1889 struct vm_area_struct
*vma
;
1890 struct mm_struct
*mm
= current
->mm
;
1891 unsigned long addr
= addr0
;
1892 struct vm_unmapped_area_info info
;
1894 /* requested length too big for entire address space */
1895 if (len
> TASK_SIZE
)
1898 if (flags
& MAP_FIXED
)
1901 /* requesting a specific address */
1903 addr
= PAGE_ALIGN(addr
);
1904 vma
= find_vma(mm
, addr
);
1905 if (TASK_SIZE
- len
>= addr
&&
1906 (!vma
|| addr
+ len
<= vma
->vm_start
))
1910 info
.flags
= VM_UNMAPPED_AREA_TOPDOWN
;
1912 info
.low_limit
= PAGE_SIZE
;
1913 info
.high_limit
= mm
->mmap_base
;
1914 info
.align_mask
= 0;
1915 addr
= vm_unmapped_area(&info
);
1918 * A failed mmap() very likely causes application failure,
1919 * so fall back to the bottom-up function here. This scenario
1920 * can happen with large stack limits and large mmap()
1923 if (addr
& ~PAGE_MASK
) {
1924 VM_BUG_ON(addr
!= -ENOMEM
);
1926 info
.low_limit
= TASK_UNMAPPED_BASE
;
1927 info
.high_limit
= TASK_SIZE
;
1928 addr
= vm_unmapped_area(&info
);
1935 void arch_unmap_area_topdown(struct mm_struct
*mm
, unsigned long addr
)
1938 * Is this a new hole at the highest possible address?
1940 if (addr
> mm
->free_area_cache
)
1941 mm
->free_area_cache
= addr
;
1943 /* dont allow allocations above current base */
1944 if (mm
->free_area_cache
> mm
->mmap_base
)
1945 mm
->free_area_cache
= mm
->mmap_base
;
1949 get_unmapped_area(struct file
*file
, unsigned long addr
, unsigned long len
,
1950 unsigned long pgoff
, unsigned long flags
)
1952 unsigned long (*get_area
)(struct file
*, unsigned long,
1953 unsigned long, unsigned long, unsigned long);
1955 unsigned long error
= arch_mmap_check(addr
, len
, flags
);
1959 /* Careful about overflows.. */
1960 if (len
> TASK_SIZE
)
1963 get_area
= current
->mm
->get_unmapped_area
;
1964 if (file
&& file
->f_op
&& file
->f_op
->get_unmapped_area
)
1965 get_area
= file
->f_op
->get_unmapped_area
;
1966 addr
= get_area(file
, addr
, len
, pgoff
, flags
);
1967 if (IS_ERR_VALUE(addr
))
1970 if (addr
> TASK_SIZE
- len
)
1972 if (addr
& ~PAGE_MASK
)
1975 addr
= arch_rebalance_pgtables(addr
, len
);
1976 error
= security_mmap_addr(addr
);
1977 return error
? error
: addr
;
1980 EXPORT_SYMBOL(get_unmapped_area
);
1982 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1983 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
1985 struct vm_area_struct
*vma
= NULL
;
1987 /* Check the cache first. */
1988 /* (Cache hit rate is typically around 35%.) */
1989 vma
= ACCESS_ONCE(mm
->mmap_cache
);
1990 if (!(vma
&& vma
->vm_end
> addr
&& vma
->vm_start
<= addr
)) {
1991 struct rb_node
*rb_node
;
1993 rb_node
= mm
->mm_rb
.rb_node
;
1997 struct vm_area_struct
*vma_tmp
;
1999 vma_tmp
= rb_entry(rb_node
,
2000 struct vm_area_struct
, vm_rb
);
2002 if (vma_tmp
->vm_end
> addr
) {
2004 if (vma_tmp
->vm_start
<= addr
)
2006 rb_node
= rb_node
->rb_left
;
2008 rb_node
= rb_node
->rb_right
;
2011 mm
->mmap_cache
= vma
;
2016 EXPORT_SYMBOL(find_vma
);
2019 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2021 struct vm_area_struct
*
2022 find_vma_prev(struct mm_struct
*mm
, unsigned long addr
,
2023 struct vm_area_struct
**pprev
)
2025 struct vm_area_struct
*vma
;
2027 vma
= find_vma(mm
, addr
);
2029 *pprev
= vma
->vm_prev
;
2031 struct rb_node
*rb_node
= mm
->mm_rb
.rb_node
;
2034 *pprev
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
2035 rb_node
= rb_node
->rb_right
;
2042 * Verify that the stack growth is acceptable and
2043 * update accounting. This is shared with both the
2044 * grow-up and grow-down cases.
2046 static int acct_stack_growth(struct vm_area_struct
*vma
, unsigned long size
, unsigned long grow
)
2048 struct mm_struct
*mm
= vma
->vm_mm
;
2049 struct rlimit
*rlim
= current
->signal
->rlim
;
2050 unsigned long new_start
;
2052 /* address space limit tests */
2053 if (!may_expand_vm(mm
, grow
))
2056 /* Stack limit test */
2057 if (size
> ACCESS_ONCE(rlim
[RLIMIT_STACK
].rlim_cur
))
2060 /* mlock limit tests */
2061 if (vma
->vm_flags
& VM_LOCKED
) {
2062 unsigned long locked
;
2063 unsigned long limit
;
2064 locked
= mm
->locked_vm
+ grow
;
2065 limit
= ACCESS_ONCE(rlim
[RLIMIT_MEMLOCK
].rlim_cur
);
2066 limit
>>= PAGE_SHIFT
;
2067 if (locked
> limit
&& !capable(CAP_IPC_LOCK
))
2071 /* Check to ensure the stack will not grow into a hugetlb-only region */
2072 new_start
= (vma
->vm_flags
& VM_GROWSUP
) ? vma
->vm_start
:
2074 if (is_hugepage_only_range(vma
->vm_mm
, new_start
, size
))
2078 * Overcommit.. This must be the final test, as it will
2079 * update security statistics.
2081 if (security_vm_enough_memory_mm(mm
, grow
))
2084 /* Ok, everything looks good - let it rip */
2085 if (vma
->vm_flags
& VM_LOCKED
)
2086 mm
->locked_vm
+= grow
;
2087 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, grow
);
2091 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2093 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2094 * vma is the last one with address > vma->vm_end. Have to extend vma.
2096 int expand_upwards(struct vm_area_struct
*vma
, unsigned long address
)
2100 if (!(vma
->vm_flags
& VM_GROWSUP
))
2104 * We must make sure the anon_vma is allocated
2105 * so that the anon_vma locking is not a noop.
2107 if (unlikely(anon_vma_prepare(vma
)))
2109 vma_lock_anon_vma(vma
);
2112 * vma->vm_start/vm_end cannot change under us because the caller
2113 * is required to hold the mmap_sem in read mode. We need the
2114 * anon_vma lock to serialize against concurrent expand_stacks.
2115 * Also guard against wrapping around to address 0.
2117 if (address
< PAGE_ALIGN(address
+4))
2118 address
= PAGE_ALIGN(address
+4);
2120 vma_unlock_anon_vma(vma
);
2125 /* Somebody else might have raced and expanded it already */
2126 if (address
> vma
->vm_end
) {
2127 unsigned long size
, grow
;
2129 size
= address
- vma
->vm_start
;
2130 grow
= (address
- vma
->vm_end
) >> PAGE_SHIFT
;
2133 if (vma
->vm_pgoff
+ (size
>> PAGE_SHIFT
) >= vma
->vm_pgoff
) {
2134 error
= acct_stack_growth(vma
, size
, grow
);
2137 * vma_gap_update() doesn't support concurrent
2138 * updates, but we only hold a shared mmap_sem
2139 * lock here, so we need to protect against
2140 * concurrent vma expansions.
2141 * vma_lock_anon_vma() doesn't help here, as
2142 * we don't guarantee that all growable vmas
2143 * in a mm share the same root anon vma.
2144 * So, we reuse mm->page_table_lock to guard
2145 * against concurrent vma expansions.
2147 spin_lock(&vma
->vm_mm
->page_table_lock
);
2148 anon_vma_interval_tree_pre_update_vma(vma
);
2149 vma
->vm_end
= address
;
2150 anon_vma_interval_tree_post_update_vma(vma
);
2152 vma_gap_update(vma
->vm_next
);
2154 vma
->vm_mm
->highest_vm_end
= address
;
2155 spin_unlock(&vma
->vm_mm
->page_table_lock
);
2157 perf_event_mmap(vma
);
2161 vma_unlock_anon_vma(vma
);
2162 khugepaged_enter_vma_merge(vma
);
2163 validate_mm(vma
->vm_mm
);
2166 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2169 * vma is the first one with address < vma->vm_start. Have to extend vma.
2171 int expand_downwards(struct vm_area_struct
*vma
,
2172 unsigned long address
)
2177 * We must make sure the anon_vma is allocated
2178 * so that the anon_vma locking is not a noop.
2180 if (unlikely(anon_vma_prepare(vma
)))
2183 address
&= PAGE_MASK
;
2184 error
= security_mmap_addr(address
);
2188 vma_lock_anon_vma(vma
);
2191 * vma->vm_start/vm_end cannot change under us because the caller
2192 * is required to hold the mmap_sem in read mode. We need the
2193 * anon_vma lock to serialize against concurrent expand_stacks.
2196 /* Somebody else might have raced and expanded it already */
2197 if (address
< vma
->vm_start
) {
2198 unsigned long size
, grow
;
2200 size
= vma
->vm_end
- address
;
2201 grow
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
2204 if (grow
<= vma
->vm_pgoff
) {
2205 error
= acct_stack_growth(vma
, size
, grow
);
2208 * vma_gap_update() doesn't support concurrent
2209 * updates, but we only hold a shared mmap_sem
2210 * lock here, so we need to protect against
2211 * concurrent vma expansions.
2212 * vma_lock_anon_vma() doesn't help here, as
2213 * we don't guarantee that all growable vmas
2214 * in a mm share the same root anon vma.
2215 * So, we reuse mm->page_table_lock to guard
2216 * against concurrent vma expansions.
2218 spin_lock(&vma
->vm_mm
->page_table_lock
);
2219 anon_vma_interval_tree_pre_update_vma(vma
);
2220 vma
->vm_start
= address
;
2221 vma
->vm_pgoff
-= grow
;
2222 anon_vma_interval_tree_post_update_vma(vma
);
2223 vma_gap_update(vma
);
2224 spin_unlock(&vma
->vm_mm
->page_table_lock
);
2226 perf_event_mmap(vma
);
2230 vma_unlock_anon_vma(vma
);
2231 khugepaged_enter_vma_merge(vma
);
2232 validate_mm(vma
->vm_mm
);
2237 * Note how expand_stack() refuses to expand the stack all the way to
2238 * abut the next virtual mapping, *unless* that mapping itself is also
2239 * a stack mapping. We want to leave room for a guard page, after all
2240 * (the guard page itself is not added here, that is done by the
2241 * actual page faulting logic)
2243 * This matches the behavior of the guard page logic (see mm/memory.c:
2244 * check_stack_guard_page()), which only allows the guard page to be
2245 * removed under these circumstances.
2247 #ifdef CONFIG_STACK_GROWSUP
2248 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2250 struct vm_area_struct
*next
;
2252 address
&= PAGE_MASK
;
2253 next
= vma
->vm_next
;
2254 if (next
&& next
->vm_start
== address
+ PAGE_SIZE
) {
2255 if (!(next
->vm_flags
& VM_GROWSUP
))
2258 return expand_upwards(vma
, address
);
2261 struct vm_area_struct
*
2262 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
2264 struct vm_area_struct
*vma
, *prev
;
2267 vma
= find_vma_prev(mm
, addr
, &prev
);
2268 if (vma
&& (vma
->vm_start
<= addr
))
2270 if (!prev
|| expand_stack(prev
, addr
))
2272 if (prev
->vm_flags
& VM_LOCKED
)
2273 __mlock_vma_pages_range(prev
, addr
, prev
->vm_end
, NULL
);
2277 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
2279 struct vm_area_struct
*prev
;
2281 address
&= PAGE_MASK
;
2282 prev
= vma
->vm_prev
;
2283 if (prev
&& prev
->vm_end
== address
) {
2284 if (!(prev
->vm_flags
& VM_GROWSDOWN
))
2287 return expand_downwards(vma
, address
);
2290 struct vm_area_struct
*
2291 find_extend_vma(struct mm_struct
* mm
, unsigned long addr
)
2293 struct vm_area_struct
* vma
;
2294 unsigned long start
;
2297 vma
= find_vma(mm
,addr
);
2300 if (vma
->vm_start
<= addr
)
2302 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
2304 start
= vma
->vm_start
;
2305 if (expand_stack(vma
, addr
))
2307 if (vma
->vm_flags
& VM_LOCKED
)
2308 __mlock_vma_pages_range(vma
, addr
, start
, NULL
);
2314 * Ok - we have the memory areas we should free on the vma list,
2315 * so release them, and do the vma updates.
2317 * Called with the mm semaphore held.
2319 static void remove_vma_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
2321 unsigned long nr_accounted
= 0;
2323 /* Update high watermark before we lower total_vm */
2324 update_hiwater_vm(mm
);
2326 long nrpages
= vma_pages(vma
);
2328 if (vma
->vm_flags
& VM_ACCOUNT
)
2329 nr_accounted
+= nrpages
;
2330 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, -nrpages
);
2331 vma
= remove_vma(vma
);
2333 vm_unacct_memory(nr_accounted
);
2338 * Get rid of page table information in the indicated region.
2340 * Called with the mm semaphore held.
2342 static void unmap_region(struct mm_struct
*mm
,
2343 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
2344 unsigned long start
, unsigned long end
)
2346 struct vm_area_struct
*next
= prev
? prev
->vm_next
: mm
->mmap
;
2347 struct mmu_gather tlb
;
2350 tlb_gather_mmu(&tlb
, mm
, 0);
2351 update_hiwater_rss(mm
);
2352 unmap_vmas(&tlb
, vma
, start
, end
);
2353 free_pgtables(&tlb
, vma
, prev
? prev
->vm_end
: FIRST_USER_ADDRESS
,
2354 next
? next
->vm_start
: USER_PGTABLES_CEILING
);
2355 tlb_finish_mmu(&tlb
, start
, end
);
2359 * Create a list of vma's touched by the unmap, removing them from the mm's
2360 * vma list as we go..
2363 detach_vmas_to_be_unmapped(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2364 struct vm_area_struct
*prev
, unsigned long end
)
2366 struct vm_area_struct
**insertion_point
;
2367 struct vm_area_struct
*tail_vma
= NULL
;
2370 insertion_point
= (prev
? &prev
->vm_next
: &mm
->mmap
);
2371 vma
->vm_prev
= NULL
;
2373 vma_rb_erase(vma
, &mm
->mm_rb
);
2377 } while (vma
&& vma
->vm_start
< end
);
2378 *insertion_point
= vma
;
2380 vma
->vm_prev
= prev
;
2381 vma_gap_update(vma
);
2383 mm
->highest_vm_end
= prev
? prev
->vm_end
: 0;
2384 tail_vma
->vm_next
= NULL
;
2385 if (mm
->unmap_area
== arch_unmap_area
)
2386 addr
= prev
? prev
->vm_end
: mm
->mmap_base
;
2388 addr
= vma
? vma
->vm_start
: mm
->mmap_base
;
2389 mm
->unmap_area(mm
, addr
);
2390 mm
->mmap_cache
= NULL
; /* Kill the cache. */
2394 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2395 * munmap path where it doesn't make sense to fail.
2397 static int __split_vma(struct mm_struct
* mm
, struct vm_area_struct
* vma
,
2398 unsigned long addr
, int new_below
)
2400 struct mempolicy
*pol
;
2401 struct vm_area_struct
*new;
2404 if (is_vm_hugetlb_page(vma
) && (addr
&
2405 ~(huge_page_mask(hstate_vma(vma
)))))
2408 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2412 /* most fields are the same, copy all, and then fixup */
2415 INIT_LIST_HEAD(&new->anon_vma_chain
);
2420 new->vm_start
= addr
;
2421 new->vm_pgoff
+= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
);
2424 pol
= mpol_dup(vma_policy(vma
));
2429 vma_set_policy(new, pol
);
2431 if (anon_vma_clone(new, vma
))
2435 get_file(new->vm_file
);
2437 if (new->vm_ops
&& new->vm_ops
->open
)
2438 new->vm_ops
->open(new);
2441 err
= vma_adjust(vma
, addr
, vma
->vm_end
, vma
->vm_pgoff
+
2442 ((addr
- new->vm_start
) >> PAGE_SHIFT
), new);
2444 err
= vma_adjust(vma
, vma
->vm_start
, addr
, vma
->vm_pgoff
, new);
2450 /* Clean everything up if vma_adjust failed. */
2451 if (new->vm_ops
&& new->vm_ops
->close
)
2452 new->vm_ops
->close(new);
2455 unlink_anon_vmas(new);
2459 kmem_cache_free(vm_area_cachep
, new);
2465 * Split a vma into two pieces at address 'addr', a new vma is allocated
2466 * either for the first part or the tail.
2468 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2469 unsigned long addr
, int new_below
)
2471 if (mm
->map_count
>= sysctl_max_map_count
)
2474 return __split_vma(mm
, vma
, addr
, new_below
);
2477 /* Munmap is split into 2 main parts -- this part which finds
2478 * what needs doing, and the areas themselves, which do the
2479 * work. This now handles partial unmappings.
2480 * Jeremy Fitzhardinge <jeremy@goop.org>
2482 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
)
2485 struct vm_area_struct
*vma
, *prev
, *last
;
2487 if ((start
& ~PAGE_MASK
) || start
> TASK_SIZE
|| len
> TASK_SIZE
-start
)
2490 if ((len
= PAGE_ALIGN(len
)) == 0)
2493 /* Find the first overlapping VMA */
2494 vma
= find_vma(mm
, start
);
2497 prev
= vma
->vm_prev
;
2498 /* we have start < vma->vm_end */
2500 /* if it doesn't overlap, we have nothing.. */
2502 if (vma
->vm_start
>= end
)
2506 * If we need to split any vma, do it now to save pain later.
2508 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2509 * unmapped vm_area_struct will remain in use: so lower split_vma
2510 * places tmp vma above, and higher split_vma places tmp vma below.
2512 if (start
> vma
->vm_start
) {
2516 * Make sure that map_count on return from munmap() will
2517 * not exceed its limit; but let map_count go just above
2518 * its limit temporarily, to help free resources as expected.
2520 if (end
< vma
->vm_end
&& mm
->map_count
>= sysctl_max_map_count
)
2523 error
= __split_vma(mm
, vma
, start
, 0);
2529 /* Does it split the last one? */
2530 last
= find_vma(mm
, end
);
2531 if (last
&& end
> last
->vm_start
) {
2532 int error
= __split_vma(mm
, last
, end
, 1);
2536 vma
= prev
? prev
->vm_next
: mm
->mmap
;
2539 * unlock any mlock()ed ranges before detaching vmas
2541 if (mm
->locked_vm
) {
2542 struct vm_area_struct
*tmp
= vma
;
2543 while (tmp
&& tmp
->vm_start
< end
) {
2544 if (tmp
->vm_flags
& VM_LOCKED
) {
2545 mm
->locked_vm
-= vma_pages(tmp
);
2546 munlock_vma_pages_all(tmp
);
2553 * Remove the vma's, and unmap the actual pages
2555 detach_vmas_to_be_unmapped(mm
, vma
, prev
, end
);
2556 unmap_region(mm
, vma
, prev
, start
, end
);
2558 /* Fix up all other VM information */
2559 remove_vma_list(mm
, vma
);
2564 int vm_munmap(unsigned long start
, size_t len
)
2567 struct mm_struct
*mm
= current
->mm
;
2569 down_write(&mm
->mmap_sem
);
2570 ret
= do_munmap(mm
, start
, len
);
2571 up_write(&mm
->mmap_sem
);
2574 EXPORT_SYMBOL(vm_munmap
);
2576 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
2578 profile_munmap(addr
);
2579 return vm_munmap(addr
, len
);
2582 static inline void verify_mm_writelocked(struct mm_struct
*mm
)
2584 #ifdef CONFIG_DEBUG_VM
2585 if (unlikely(down_read_trylock(&mm
->mmap_sem
))) {
2587 up_read(&mm
->mmap_sem
);
2593 * this is really a simplified "do_mmap". it only handles
2594 * anonymous maps. eventually we may be able to do some
2595 * brk-specific accounting here.
2597 static unsigned long do_brk(unsigned long addr
, unsigned long len
)
2599 struct mm_struct
* mm
= current
->mm
;
2600 struct vm_area_struct
* vma
, * prev
;
2601 unsigned long flags
;
2602 struct rb_node
** rb_link
, * rb_parent
;
2603 pgoff_t pgoff
= addr
>> PAGE_SHIFT
;
2606 len
= PAGE_ALIGN(len
);
2610 flags
= VM_DATA_DEFAULT_FLAGS
| VM_ACCOUNT
| mm
->def_flags
;
2612 error
= get_unmapped_area(NULL
, addr
, len
, 0, MAP_FIXED
);
2613 if (error
& ~PAGE_MASK
)
2619 if (mm
->def_flags
& VM_LOCKED
) {
2620 unsigned long locked
, lock_limit
;
2621 locked
= len
>> PAGE_SHIFT
;
2622 locked
+= mm
->locked_vm
;
2623 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
2624 lock_limit
>>= PAGE_SHIFT
;
2625 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
2630 * mm->mmap_sem is required to protect against another thread
2631 * changing the mappings in case we sleep.
2633 verify_mm_writelocked(mm
);
2636 * Clear old maps. this also does some error checking for us
2639 if (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
, &rb_parent
)) {
2640 if (do_munmap(mm
, addr
, len
))
2645 /* Check against address space limits *after* clearing old maps... */
2646 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
))
2649 if (mm
->map_count
> sysctl_max_map_count
)
2652 if (security_vm_enough_memory_mm(mm
, len
>> PAGE_SHIFT
))
2655 /* Can we just expand an old private anonymous mapping? */
2656 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, flags
,
2657 NULL
, NULL
, pgoff
, NULL
);
2662 * create a vma struct for an anonymous mapping
2664 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2666 vm_unacct_memory(len
>> PAGE_SHIFT
);
2670 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2672 vma
->vm_start
= addr
;
2673 vma
->vm_end
= addr
+ len
;
2674 vma
->vm_pgoff
= pgoff
;
2675 vma
->vm_flags
= flags
;
2676 vma
->vm_page_prot
= vm_get_page_prot(flags
);
2677 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2679 perf_event_mmap(vma
);
2680 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2681 if (flags
& VM_LOCKED
)
2682 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
2686 unsigned long vm_brk(unsigned long addr
, unsigned long len
)
2688 struct mm_struct
*mm
= current
->mm
;
2692 down_write(&mm
->mmap_sem
);
2693 ret
= do_brk(addr
, len
);
2694 populate
= ((mm
->def_flags
& VM_LOCKED
) != 0);
2695 up_write(&mm
->mmap_sem
);
2697 mm_populate(addr
, len
);
2700 EXPORT_SYMBOL(vm_brk
);
2702 /* Release all mmaps. */
2703 void exit_mmap(struct mm_struct
*mm
)
2705 struct mmu_gather tlb
;
2706 struct vm_area_struct
*vma
;
2707 unsigned long nr_accounted
= 0;
2709 /* mm's last user has gone, and its about to be pulled down */
2710 mmu_notifier_release(mm
);
2712 if (mm
->locked_vm
) {
2715 if (vma
->vm_flags
& VM_LOCKED
)
2716 munlock_vma_pages_all(vma
);
2724 if (!vma
) /* Can happen if dup_mmap() received an OOM */
2729 tlb_gather_mmu(&tlb
, mm
, 1);
2730 /* update_hiwater_rss(mm) here? but nobody should be looking */
2731 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2732 unmap_vmas(&tlb
, vma
, 0, -1);
2734 free_pgtables(&tlb
, vma
, FIRST_USER_ADDRESS
, USER_PGTABLES_CEILING
);
2735 tlb_finish_mmu(&tlb
, 0, -1);
2738 * Walk the list again, actually closing and freeing it,
2739 * with preemption enabled, without holding any MM locks.
2742 if (vma
->vm_flags
& VM_ACCOUNT
)
2743 nr_accounted
+= vma_pages(vma
);
2744 vma
= remove_vma(vma
);
2746 vm_unacct_memory(nr_accounted
);
2748 WARN_ON(mm
->nr_ptes
> (FIRST_USER_ADDRESS
+PMD_SIZE
-1)>>PMD_SHIFT
);
2751 /* Insert vm structure into process list sorted by address
2752 * and into the inode's i_mmap tree. If vm_file is non-NULL
2753 * then i_mmap_mutex is taken here.
2755 int insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
2757 struct vm_area_struct
*prev
;
2758 struct rb_node
**rb_link
, *rb_parent
;
2761 * The vm_pgoff of a purely anonymous vma should be irrelevant
2762 * until its first write fault, when page's anon_vma and index
2763 * are set. But now set the vm_pgoff it will almost certainly
2764 * end up with (unless mremap moves it elsewhere before that
2765 * first wfault), so /proc/pid/maps tells a consistent story.
2767 * By setting it to reflect the virtual start address of the
2768 * vma, merges and splits can happen in a seamless way, just
2769 * using the existing file pgoff checks and manipulations.
2770 * Similarly in do_mmap_pgoff and in do_brk.
2772 if (!vma
->vm_file
) {
2773 BUG_ON(vma
->anon_vma
);
2774 vma
->vm_pgoff
= vma
->vm_start
>> PAGE_SHIFT
;
2776 if (find_vma_links(mm
, vma
->vm_start
, vma
->vm_end
,
2777 &prev
, &rb_link
, &rb_parent
))
2779 if ((vma
->vm_flags
& VM_ACCOUNT
) &&
2780 security_vm_enough_memory_mm(mm
, vma_pages(vma
)))
2783 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2788 * Copy the vma structure to a new location in the same mm,
2789 * prior to moving page table entries, to effect an mremap move.
2791 struct vm_area_struct
*copy_vma(struct vm_area_struct
**vmap
,
2792 unsigned long addr
, unsigned long len
, pgoff_t pgoff
,
2793 bool *need_rmap_locks
)
2795 struct vm_area_struct
*vma
= *vmap
;
2796 unsigned long vma_start
= vma
->vm_start
;
2797 struct mm_struct
*mm
= vma
->vm_mm
;
2798 struct vm_area_struct
*new_vma
, *prev
;
2799 struct rb_node
**rb_link
, *rb_parent
;
2800 struct mempolicy
*pol
;
2801 bool faulted_in_anon_vma
= true;
2804 * If anonymous vma has not yet been faulted, update new pgoff
2805 * to match new location, to increase its chance of merging.
2807 if (unlikely(!vma
->vm_file
&& !vma
->anon_vma
)) {
2808 pgoff
= addr
>> PAGE_SHIFT
;
2809 faulted_in_anon_vma
= false;
2812 if (find_vma_links(mm
, addr
, addr
+ len
, &prev
, &rb_link
, &rb_parent
))
2813 return NULL
; /* should never get here */
2814 new_vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vma
->vm_flags
,
2815 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
2818 * Source vma may have been merged into new_vma
2820 if (unlikely(vma_start
>= new_vma
->vm_start
&&
2821 vma_start
< new_vma
->vm_end
)) {
2823 * The only way we can get a vma_merge with
2824 * self during an mremap is if the vma hasn't
2825 * been faulted in yet and we were allowed to
2826 * reset the dst vma->vm_pgoff to the
2827 * destination address of the mremap to allow
2828 * the merge to happen. mremap must change the
2829 * vm_pgoff linearity between src and dst vmas
2830 * (in turn preventing a vma_merge) to be
2831 * safe. It is only safe to keep the vm_pgoff
2832 * linear if there are no pages mapped yet.
2834 VM_BUG_ON(faulted_in_anon_vma
);
2835 *vmap
= vma
= new_vma
;
2837 *need_rmap_locks
= (new_vma
->vm_pgoff
<= vma
->vm_pgoff
);
2839 new_vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2842 new_vma
->vm_start
= addr
;
2843 new_vma
->vm_end
= addr
+ len
;
2844 new_vma
->vm_pgoff
= pgoff
;
2845 pol
= mpol_dup(vma_policy(vma
));
2848 vma_set_policy(new_vma
, pol
);
2849 INIT_LIST_HEAD(&new_vma
->anon_vma_chain
);
2850 if (anon_vma_clone(new_vma
, vma
))
2851 goto out_free_mempol
;
2852 if (new_vma
->vm_file
)
2853 get_file(new_vma
->vm_file
);
2854 if (new_vma
->vm_ops
&& new_vma
->vm_ops
->open
)
2855 new_vma
->vm_ops
->open(new_vma
);
2856 vma_link(mm
, new_vma
, prev
, rb_link
, rb_parent
);
2857 *need_rmap_locks
= false;
2865 kmem_cache_free(vm_area_cachep
, new_vma
);
2870 * Return true if the calling process may expand its vm space by the passed
2873 int may_expand_vm(struct mm_struct
*mm
, unsigned long npages
)
2875 unsigned long cur
= mm
->total_vm
; /* pages */
2878 lim
= rlimit(RLIMIT_AS
) >> PAGE_SHIFT
;
2880 if (cur
+ npages
> lim
)
2886 static int special_mapping_fault(struct vm_area_struct
*vma
,
2887 struct vm_fault
*vmf
)
2890 struct page
**pages
;
2893 * special mappings have no vm_file, and in that case, the mm
2894 * uses vm_pgoff internally. So we have to subtract it from here.
2895 * We are allowed to do this because we are the mm; do not copy
2896 * this code into drivers!
2898 pgoff
= vmf
->pgoff
- vma
->vm_pgoff
;
2900 for (pages
= vma
->vm_private_data
; pgoff
&& *pages
; ++pages
)
2904 struct page
*page
= *pages
;
2910 return VM_FAULT_SIGBUS
;
2914 * Having a close hook prevents vma merging regardless of flags.
2916 static void special_mapping_close(struct vm_area_struct
*vma
)
2920 static const struct vm_operations_struct special_mapping_vmops
= {
2921 .close
= special_mapping_close
,
2922 .fault
= special_mapping_fault
,
2926 * Called with mm->mmap_sem held for writing.
2927 * Insert a new vma covering the given region, with the given flags.
2928 * Its pages are supplied by the given array of struct page *.
2929 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2930 * The region past the last page supplied will always produce SIGBUS.
2931 * The array pointer and the pages it points to are assumed to stay alive
2932 * for as long as this mapping might exist.
2934 int install_special_mapping(struct mm_struct
*mm
,
2935 unsigned long addr
, unsigned long len
,
2936 unsigned long vm_flags
, struct page
**pages
)
2939 struct vm_area_struct
*vma
;
2941 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2942 if (unlikely(vma
== NULL
))
2945 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2947 vma
->vm_start
= addr
;
2948 vma
->vm_end
= addr
+ len
;
2950 vma
->vm_flags
= vm_flags
| mm
->def_flags
| VM_DONTEXPAND
;
2951 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
2953 vma
->vm_ops
= &special_mapping_vmops
;
2954 vma
->vm_private_data
= pages
;
2956 ret
= insert_vm_struct(mm
, vma
);
2960 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2962 perf_event_mmap(vma
);
2967 kmem_cache_free(vm_area_cachep
, vma
);
2971 static DEFINE_MUTEX(mm_all_locks_mutex
);
2973 static void vm_lock_anon_vma(struct mm_struct
*mm
, struct anon_vma
*anon_vma
)
2975 if (!test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_node
)) {
2977 * The LSB of head.next can't change from under us
2978 * because we hold the mm_all_locks_mutex.
2980 down_write_nest_lock(&anon_vma
->root
->rwsem
, &mm
->mmap_sem
);
2982 * We can safely modify head.next after taking the
2983 * anon_vma->root->rwsem. If some other vma in this mm shares
2984 * the same anon_vma we won't take it again.
2986 * No need of atomic instructions here, head.next
2987 * can't change from under us thanks to the
2988 * anon_vma->root->rwsem.
2990 if (__test_and_set_bit(0, (unsigned long *)
2991 &anon_vma
->root
->rb_root
.rb_node
))
2996 static void vm_lock_mapping(struct mm_struct
*mm
, struct address_space
*mapping
)
2998 if (!test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3000 * AS_MM_ALL_LOCKS can't change from under us because
3001 * we hold the mm_all_locks_mutex.
3003 * Operations on ->flags have to be atomic because
3004 * even if AS_MM_ALL_LOCKS is stable thanks to the
3005 * mm_all_locks_mutex, there may be other cpus
3006 * changing other bitflags in parallel to us.
3008 if (test_and_set_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
))
3010 mutex_lock_nest_lock(&mapping
->i_mmap_mutex
, &mm
->mmap_sem
);
3015 * This operation locks against the VM for all pte/vma/mm related
3016 * operations that could ever happen on a certain mm. This includes
3017 * vmtruncate, try_to_unmap, and all page faults.
3019 * The caller must take the mmap_sem in write mode before calling
3020 * mm_take_all_locks(). The caller isn't allowed to release the
3021 * mmap_sem until mm_drop_all_locks() returns.
3023 * mmap_sem in write mode is required in order to block all operations
3024 * that could modify pagetables and free pages without need of
3025 * altering the vma layout (for example populate_range() with
3026 * nonlinear vmas). It's also needed in write mode to avoid new
3027 * anon_vmas to be associated with existing vmas.
3029 * A single task can't take more than one mm_take_all_locks() in a row
3030 * or it would deadlock.
3032 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3033 * mapping->flags avoid to take the same lock twice, if more than one
3034 * vma in this mm is backed by the same anon_vma or address_space.
3036 * We can take all the locks in random order because the VM code
3037 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3038 * takes more than one of them in a row. Secondly we're protected
3039 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
3041 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3042 * that may have to take thousand of locks.
3044 * mm_take_all_locks() can fail if it's interrupted by signals.
3046 int mm_take_all_locks(struct mm_struct
*mm
)
3048 struct vm_area_struct
*vma
;
3049 struct anon_vma_chain
*avc
;
3051 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3053 mutex_lock(&mm_all_locks_mutex
);
3055 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3056 if (signal_pending(current
))
3058 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
3059 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
3062 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3063 if (signal_pending(current
))
3066 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3067 vm_lock_anon_vma(mm
, avc
->anon_vma
);
3073 mm_drop_all_locks(mm
);
3077 static void vm_unlock_anon_vma(struct anon_vma
*anon_vma
)
3079 if (test_bit(0, (unsigned long *) &anon_vma
->root
->rb_root
.rb_node
)) {
3081 * The LSB of head.next can't change to 0 from under
3082 * us because we hold the mm_all_locks_mutex.
3084 * We must however clear the bitflag before unlocking
3085 * the vma so the users using the anon_vma->rb_root will
3086 * never see our bitflag.
3088 * No need of atomic instructions here, head.next
3089 * can't change from under us until we release the
3090 * anon_vma->root->rwsem.
3092 if (!__test_and_clear_bit(0, (unsigned long *)
3093 &anon_vma
->root
->rb_root
.rb_node
))
3095 anon_vma_unlock_write(anon_vma
);
3099 static void vm_unlock_mapping(struct address_space
*mapping
)
3101 if (test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
3103 * AS_MM_ALL_LOCKS can't change to 0 from under us
3104 * because we hold the mm_all_locks_mutex.
3106 mutex_unlock(&mapping
->i_mmap_mutex
);
3107 if (!test_and_clear_bit(AS_MM_ALL_LOCKS
,
3114 * The mmap_sem cannot be released by the caller until
3115 * mm_drop_all_locks() returns.
3117 void mm_drop_all_locks(struct mm_struct
*mm
)
3119 struct vm_area_struct
*vma
;
3120 struct anon_vma_chain
*avc
;
3122 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
3123 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex
));
3125 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
3127 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
3128 vm_unlock_anon_vma(avc
->anon_vma
);
3129 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
3130 vm_unlock_mapping(vma
->vm_file
->f_mapping
);
3133 mutex_unlock(&mm_all_locks_mutex
);
3137 * initialise the VMA slab
3139 void __init
mmap_init(void)
3143 ret
= percpu_counter_init(&vm_committed_as
, 0);
3148 * Initialise sysctl_user_reserve_kbytes.
3150 * This is intended to prevent a user from starting a single memory hogging
3151 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3154 * The default value is min(3% of free memory, 128MB)
3155 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3157 static int init_user_reserve(void)
3159 unsigned long free_kbytes
;
3161 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3163 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
3166 module_init(init_user_reserve
)
3169 * Initialise sysctl_admin_reserve_kbytes.
3171 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3172 * to log in and kill a memory hogging process.
3174 * Systems with more than 256MB will reserve 8MB, enough to recover
3175 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3176 * only reserve 3% of free pages by default.
3178 static int init_admin_reserve(void)
3180 unsigned long free_kbytes
;
3182 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3184 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
3187 module_init(init_admin_reserve
)
3190 * Reinititalise user and admin reserves if memory is added or removed.
3192 * The default user reserve max is 128MB, and the default max for the
3193 * admin reserve is 8MB. These are usually, but not always, enough to
3194 * enable recovery from a memory hogging process using login/sshd, a shell,
3195 * and tools like top. It may make sense to increase or even disable the
3196 * reserve depending on the existence of swap or variations in the recovery
3197 * tools. So, the admin may have changed them.
3199 * If memory is added and the reserves have been eliminated or increased above
3200 * the default max, then we'll trust the admin.
3202 * If memory is removed and there isn't enough free memory, then we
3203 * need to reset the reserves.
3205 * Otherwise keep the reserve set by the admin.
3207 static int reserve_mem_notifier(struct notifier_block
*nb
,
3208 unsigned long action
, void *data
)
3210 unsigned long tmp
, free_kbytes
;
3214 /* Default max is 128MB. Leave alone if modified by operator. */
3215 tmp
= sysctl_user_reserve_kbytes
;
3216 if (0 < tmp
&& tmp
< (1UL << 17))
3217 init_user_reserve();
3219 /* Default max is 8MB. Leave alone if modified by operator. */
3220 tmp
= sysctl_admin_reserve_kbytes
;
3221 if (0 < tmp
&& tmp
< (1UL << 13))
3222 init_admin_reserve();
3226 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
3228 if (sysctl_user_reserve_kbytes
> free_kbytes
) {
3229 init_user_reserve();
3230 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3231 sysctl_user_reserve_kbytes
);
3234 if (sysctl_admin_reserve_kbytes
> free_kbytes
) {
3235 init_admin_reserve();
3236 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3237 sysctl_admin_reserve_kbytes
);
3246 static struct notifier_block reserve_mem_nb
= {
3247 .notifier_call
= reserve_mem_notifier
,
3250 static int __meminit
init_reserve_notifier(void)
3252 if (register_hotmemory_notifier(&reserve_mem_nb
))
3253 printk("Failed registering memory add/remove notifier for admin reserve");
3257 module_init(init_reserve_notifier
)