6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
29 #include <linux/mmu_notifier.h>
30 #include <linux/perf_event.h>
31 #include <linux/audit.h>
32 #include <linux/khugepaged.h>
34 #include <asm/uaccess.h>
35 #include <asm/cacheflush.h>
37 #include <asm/mmu_context.h>
41 #ifndef arch_mmap_check
42 #define arch_mmap_check(addr, len, flags) (0)
45 #ifndef arch_rebalance_pgtables
46 #define arch_rebalance_pgtables(addr, len) (addr)
49 static void unmap_region(struct mm_struct
*mm
,
50 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
51 unsigned long start
, unsigned long end
);
54 * WARNING: the debugging will use recursive algorithms so never enable this
55 * unless you know what you are doing.
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
= OVERCOMMIT_GUESS
; /* heuristic overcommit */
88 int sysctl_overcommit_ratio
= 50; /* default is 50% */
89 int sysctl_max_map_count __read_mostly
= DEFAULT_MAX_MAP_COUNT
;
90 struct percpu_counter vm_committed_as
;
93 * Check that a process has enough memory to allocate a new virtual
94 * mapping. 0 means there is enough memory for the allocation to
95 * succeed and -ENOMEM implies there is not.
97 * We currently support three overcommit policies, which are set via the
98 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
100 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
101 * Additional code 2002 Jul 20 by Robert Love.
103 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
105 * Note this is a helper function intended to be used by LSMs which
106 * wish to use this logic.
108 int __vm_enough_memory(struct mm_struct
*mm
, long pages
, int cap_sys_admin
)
110 unsigned long free
, allowed
;
112 vm_acct_memory(pages
);
115 * Sometimes we want to use more memory than we have
117 if (sysctl_overcommit_memory
== OVERCOMMIT_ALWAYS
)
120 if (sysctl_overcommit_memory
== OVERCOMMIT_GUESS
) {
123 free
= global_page_state(NR_FILE_PAGES
);
124 free
+= nr_swap_pages
;
127 * Any slabs which are created with the
128 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
129 * which are reclaimable, under pressure. The dentry
130 * cache and most inode caches should fall into this
132 free
+= global_page_state(NR_SLAB_RECLAIMABLE
);
135 * Leave the last 3% for root
144 * nr_free_pages() is very expensive on large systems,
145 * only call if we're about to fail.
150 * Leave reserved pages. The pages are not for anonymous pages.
152 if (n
<= totalreserve_pages
)
155 n
-= totalreserve_pages
;
158 * Leave the last 3% for root
170 allowed
= (totalram_pages
- hugetlb_total_pages())
171 * sysctl_overcommit_ratio
/ 100;
173 * Leave the last 3% for root
176 allowed
-= allowed
/ 32;
177 allowed
+= total_swap_pages
;
179 /* Don't let a single process grow too big:
180 leave 3% of the size of this process for other processes */
182 allowed
-= mm
->total_vm
/ 32;
184 if (percpu_counter_read_positive(&vm_committed_as
) < allowed
)
187 vm_unacct_memory(pages
);
193 * Requires inode->i_mapping->i_mmap_lock
195 static void __remove_shared_vm_struct(struct vm_area_struct
*vma
,
196 struct file
*file
, struct address_space
*mapping
)
198 if (vma
->vm_flags
& VM_DENYWRITE
)
199 atomic_inc(&file
->f_path
.dentry
->d_inode
->i_writecount
);
200 if (vma
->vm_flags
& VM_SHARED
)
201 mapping
->i_mmap_writable
--;
203 flush_dcache_mmap_lock(mapping
);
204 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
205 list_del_init(&vma
->shared
.vm_set
.list
);
207 vma_prio_tree_remove(vma
, &mapping
->i_mmap
);
208 flush_dcache_mmap_unlock(mapping
);
212 * Unlink a file-based vm structure from its prio_tree, to hide
213 * vma from rmap and vmtruncate before freeing its page tables.
215 void unlink_file_vma(struct vm_area_struct
*vma
)
217 struct file
*file
= vma
->vm_file
;
220 struct address_space
*mapping
= file
->f_mapping
;
221 spin_lock(&mapping
->i_mmap_lock
);
222 __remove_shared_vm_struct(vma
, file
, mapping
);
223 spin_unlock(&mapping
->i_mmap_lock
);
228 * Close a vm structure and free it, returning the next.
230 static struct vm_area_struct
*remove_vma(struct vm_area_struct
*vma
)
232 struct vm_area_struct
*next
= vma
->vm_next
;
235 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
236 vma
->vm_ops
->close(vma
);
239 if (vma
->vm_flags
& VM_EXECUTABLE
)
240 removed_exe_file_vma(vma
->vm_mm
);
242 mpol_put(vma_policy(vma
));
243 kmem_cache_free(vm_area_cachep
, vma
);
247 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
249 unsigned long rlim
, retval
;
250 unsigned long newbrk
, oldbrk
;
251 struct mm_struct
*mm
= current
->mm
;
252 unsigned long min_brk
;
254 down_write(&mm
->mmap_sem
);
256 #ifdef CONFIG_COMPAT_BRK
257 min_brk
= mm
->end_code
;
259 min_brk
= mm
->start_brk
;
265 * Check against rlimit here. If this check is done later after the test
266 * of oldbrk with newbrk then it can escape the test and let the data
267 * segment grow beyond its set limit the in case where the limit is
268 * not page aligned -Ram Gupta
270 rlim
= rlimit(RLIMIT_DATA
);
271 if (rlim
< RLIM_INFINITY
&& (brk
- mm
->start_brk
) +
272 (mm
->end_data
- mm
->start_data
) > rlim
)
275 newbrk
= PAGE_ALIGN(brk
);
276 oldbrk
= PAGE_ALIGN(mm
->brk
);
277 if (oldbrk
== newbrk
)
280 /* Always allow shrinking brk. */
281 if (brk
<= mm
->brk
) {
282 if (!do_munmap(mm
, newbrk
, oldbrk
-newbrk
))
287 /* Check against existing mmap mappings. */
288 if (find_vma_intersection(mm
, oldbrk
, newbrk
+PAGE_SIZE
))
291 /* Ok, looks good - let it rip. */
292 if (do_brk(oldbrk
, newbrk
-oldbrk
) != oldbrk
)
298 up_write(&mm
->mmap_sem
);
303 static int browse_rb(struct rb_root
*root
)
306 struct rb_node
*nd
, *pn
= NULL
;
307 unsigned long prev
= 0, pend
= 0;
309 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
310 struct vm_area_struct
*vma
;
311 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
312 if (vma
->vm_start
< prev
)
313 printk("vm_start %lx prev %lx\n", vma
->vm_start
, prev
), i
= -1;
314 if (vma
->vm_start
< pend
)
315 printk("vm_start %lx pend %lx\n", vma
->vm_start
, pend
);
316 if (vma
->vm_start
> vma
->vm_end
)
317 printk("vm_end %lx < vm_start %lx\n", vma
->vm_end
, vma
->vm_start
);
320 prev
= vma
->vm_start
;
324 for (nd
= pn
; nd
; nd
= rb_prev(nd
)) {
328 printk("backwards %d, forwards %d\n", j
, i
), i
= 0;
332 void validate_mm(struct mm_struct
*mm
)
336 struct vm_area_struct
*tmp
= mm
->mmap
;
341 if (i
!= mm
->map_count
)
342 printk("map_count %d vm_next %d\n", mm
->map_count
, i
), bug
= 1;
343 i
= browse_rb(&mm
->mm_rb
);
344 if (i
!= mm
->map_count
)
345 printk("map_count %d rb %d\n", mm
->map_count
, i
), bug
= 1;
349 #define validate_mm(mm) do { } while (0)
352 static struct vm_area_struct
*
353 find_vma_prepare(struct mm_struct
*mm
, unsigned long addr
,
354 struct vm_area_struct
**pprev
, struct rb_node
***rb_link
,
355 struct rb_node
** rb_parent
)
357 struct vm_area_struct
* vma
;
358 struct rb_node
** __rb_link
, * __rb_parent
, * rb_prev
;
360 __rb_link
= &mm
->mm_rb
.rb_node
;
361 rb_prev
= __rb_parent
= NULL
;
365 struct vm_area_struct
*vma_tmp
;
367 __rb_parent
= *__rb_link
;
368 vma_tmp
= rb_entry(__rb_parent
, struct vm_area_struct
, vm_rb
);
370 if (vma_tmp
->vm_end
> addr
) {
372 if (vma_tmp
->vm_start
<= addr
)
374 __rb_link
= &__rb_parent
->rb_left
;
376 rb_prev
= __rb_parent
;
377 __rb_link
= &__rb_parent
->rb_right
;
383 *pprev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
384 *rb_link
= __rb_link
;
385 *rb_parent
= __rb_parent
;
390 __vma_link_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
391 struct vm_area_struct
*prev
, struct rb_node
*rb_parent
)
393 struct vm_area_struct
*next
;
397 next
= prev
->vm_next
;
402 next
= rb_entry(rb_parent
,
403 struct vm_area_struct
, vm_rb
);
412 void __vma_link_rb(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
413 struct rb_node
**rb_link
, struct rb_node
*rb_parent
)
415 rb_link_node(&vma
->vm_rb
, rb_parent
, rb_link
);
416 rb_insert_color(&vma
->vm_rb
, &mm
->mm_rb
);
419 static void __vma_link_file(struct vm_area_struct
*vma
)
425 struct address_space
*mapping
= file
->f_mapping
;
427 if (vma
->vm_flags
& VM_DENYWRITE
)
428 atomic_dec(&file
->f_path
.dentry
->d_inode
->i_writecount
);
429 if (vma
->vm_flags
& VM_SHARED
)
430 mapping
->i_mmap_writable
++;
432 flush_dcache_mmap_lock(mapping
);
433 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
434 vma_nonlinear_insert(vma
, &mapping
->i_mmap_nonlinear
);
436 vma_prio_tree_insert(vma
, &mapping
->i_mmap
);
437 flush_dcache_mmap_unlock(mapping
);
442 __vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
443 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
444 struct rb_node
*rb_parent
)
446 __vma_link_list(mm
, vma
, prev
, rb_parent
);
447 __vma_link_rb(mm
, vma
, rb_link
, rb_parent
);
450 static void vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
451 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
452 struct rb_node
*rb_parent
)
454 struct address_space
*mapping
= NULL
;
457 mapping
= vma
->vm_file
->f_mapping
;
460 spin_lock(&mapping
->i_mmap_lock
);
461 vma
->vm_truncate_count
= mapping
->truncate_count
;
464 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
465 __vma_link_file(vma
);
468 spin_unlock(&mapping
->i_mmap_lock
);
475 * Helper for vma_adjust in the split_vma insert case:
476 * insert vm structure into list and rbtree and anon_vma,
477 * but it has already been inserted into prio_tree earlier.
479 static void __insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
481 struct vm_area_struct
*__vma
, *prev
;
482 struct rb_node
**rb_link
, *rb_parent
;
484 __vma
= find_vma_prepare(mm
, vma
->vm_start
,&prev
, &rb_link
, &rb_parent
);
485 BUG_ON(__vma
&& __vma
->vm_start
< vma
->vm_end
);
486 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
491 __vma_unlink(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
492 struct vm_area_struct
*prev
)
494 struct vm_area_struct
*next
= vma
->vm_next
;
496 prev
->vm_next
= next
;
498 next
->vm_prev
= prev
;
499 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
500 if (mm
->mmap_cache
== vma
)
501 mm
->mmap_cache
= prev
;
505 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
506 * is already present in an i_mmap tree without adjusting the tree.
507 * The following helper function should be used when such adjustments
508 * are necessary. The "insert" vma (if any) is to be inserted
509 * before we drop the necessary locks.
511 int vma_adjust(struct vm_area_struct
*vma
, unsigned long start
,
512 unsigned long end
, pgoff_t pgoff
, struct vm_area_struct
*insert
)
514 struct mm_struct
*mm
= vma
->vm_mm
;
515 struct vm_area_struct
*next
= vma
->vm_next
;
516 struct vm_area_struct
*importer
= NULL
;
517 struct address_space
*mapping
= NULL
;
518 struct prio_tree_root
*root
= NULL
;
519 struct anon_vma
*anon_vma
= NULL
;
520 struct file
*file
= vma
->vm_file
;
521 long adjust_next
= 0;
524 if (next
&& !insert
) {
525 struct vm_area_struct
*exporter
= NULL
;
527 if (end
>= next
->vm_end
) {
529 * vma expands, overlapping all the next, and
530 * perhaps the one after too (mprotect case 6).
532 again
: remove_next
= 1 + (end
> next
->vm_end
);
536 } else if (end
> next
->vm_start
) {
538 * vma expands, overlapping part of the next:
539 * mprotect case 5 shifting the boundary up.
541 adjust_next
= (end
- next
->vm_start
) >> PAGE_SHIFT
;
544 } else if (end
< vma
->vm_end
) {
546 * vma shrinks, and !insert tells it's not
547 * split_vma inserting another: so it must be
548 * mprotect case 4 shifting the boundary down.
550 adjust_next
= - ((vma
->vm_end
- end
) >> PAGE_SHIFT
);
556 * Easily overlooked: when mprotect shifts the boundary,
557 * make sure the expanding vma has anon_vma set if the
558 * shrinking vma had, to cover any anon pages imported.
560 if (exporter
&& exporter
->anon_vma
&& !importer
->anon_vma
) {
561 if (anon_vma_clone(importer
, exporter
))
563 importer
->anon_vma
= exporter
->anon_vma
;
568 mapping
= file
->f_mapping
;
569 if (!(vma
->vm_flags
& VM_NONLINEAR
))
570 root
= &mapping
->i_mmap
;
571 spin_lock(&mapping
->i_mmap_lock
);
573 vma
->vm_truncate_count
!= next
->vm_truncate_count
) {
575 * unmap_mapping_range might be in progress:
576 * ensure that the expanding vma is rescanned.
578 importer
->vm_truncate_count
= 0;
581 insert
->vm_truncate_count
= vma
->vm_truncate_count
;
583 * Put into prio_tree now, so instantiated pages
584 * are visible to arm/parisc __flush_dcache_page
585 * throughout; but we cannot insert into address
586 * space until vma start or end is updated.
588 __vma_link_file(insert
);
592 vma_adjust_trans_huge(vma
, start
, end
, adjust_next
);
595 * When changing only vma->vm_end, we don't really need anon_vma
596 * lock. This is a fairly rare case by itself, but the anon_vma
597 * lock may be shared between many sibling processes. Skipping
598 * the lock for brk adjustments makes a difference sometimes.
600 if (vma
->anon_vma
&& (insert
|| importer
|| start
!= vma
->vm_start
)) {
601 anon_vma
= vma
->anon_vma
;
602 anon_vma_lock(anon_vma
);
606 flush_dcache_mmap_lock(mapping
);
607 vma_prio_tree_remove(vma
, root
);
609 vma_prio_tree_remove(next
, root
);
612 vma
->vm_start
= start
;
614 vma
->vm_pgoff
= pgoff
;
616 next
->vm_start
+= adjust_next
<< PAGE_SHIFT
;
617 next
->vm_pgoff
+= adjust_next
;
622 vma_prio_tree_insert(next
, root
);
623 vma_prio_tree_insert(vma
, root
);
624 flush_dcache_mmap_unlock(mapping
);
629 * vma_merge has merged next into vma, and needs
630 * us to remove next before dropping the locks.
632 __vma_unlink(mm
, next
, vma
);
634 __remove_shared_vm_struct(next
, file
, mapping
);
637 * split_vma has split insert from vma, and needs
638 * us to insert it before dropping the locks
639 * (it may either follow vma or precede it).
641 __insert_vm_struct(mm
, insert
);
645 anon_vma_unlock(anon_vma
);
647 spin_unlock(&mapping
->i_mmap_lock
);
652 if (next
->vm_flags
& VM_EXECUTABLE
)
653 removed_exe_file_vma(mm
);
656 anon_vma_merge(vma
, next
);
658 mpol_put(vma_policy(next
));
659 kmem_cache_free(vm_area_cachep
, next
);
661 * In mprotect's case 6 (see comments on vma_merge),
662 * we must remove another next too. It would clutter
663 * up the code too much to do both in one go.
665 if (remove_next
== 2) {
677 * If the vma has a ->close operation then the driver probably needs to release
678 * per-vma resources, so we don't attempt to merge those.
680 static inline int is_mergeable_vma(struct vm_area_struct
*vma
,
681 struct file
*file
, unsigned long vm_flags
)
683 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
684 if ((vma
->vm_flags
^ vm_flags
) & ~VM_CAN_NONLINEAR
)
686 if (vma
->vm_file
!= file
)
688 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
693 static inline int is_mergeable_anon_vma(struct anon_vma
*anon_vma1
,
694 struct anon_vma
*anon_vma2
)
696 return !anon_vma1
|| !anon_vma2
|| (anon_vma1
== anon_vma2
);
700 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
701 * in front of (at a lower virtual address and file offset than) the vma.
703 * We cannot merge two vmas if they have differently assigned (non-NULL)
704 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
706 * We don't check here for the merged mmap wrapping around the end of pagecache
707 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
708 * wrap, nor mmaps which cover the final page at index -1UL.
711 can_vma_merge_before(struct vm_area_struct
*vma
, unsigned long vm_flags
,
712 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
714 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
715 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
)) {
716 if (vma
->vm_pgoff
== vm_pgoff
)
723 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
724 * beyond (at a higher virtual address and file offset than) the vma.
726 * We cannot merge two vmas if they have differently assigned (non-NULL)
727 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
730 can_vma_merge_after(struct vm_area_struct
*vma
, unsigned long vm_flags
,
731 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
733 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
734 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
)) {
736 vm_pglen
= (vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
;
737 if (vma
->vm_pgoff
+ vm_pglen
== vm_pgoff
)
744 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
745 * whether that can be merged with its predecessor or its successor.
746 * Or both (it neatly fills a hole).
748 * In most cases - when called for mmap, brk or mremap - [addr,end) is
749 * certain not to be mapped by the time vma_merge is called; but when
750 * called for mprotect, it is certain to be already mapped (either at
751 * an offset within prev, or at the start of next), and the flags of
752 * this area are about to be changed to vm_flags - and the no-change
753 * case has already been eliminated.
755 * The following mprotect cases have to be considered, where AAAA is
756 * the area passed down from mprotect_fixup, never extending beyond one
757 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
759 * AAAA AAAA AAAA AAAA
760 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
761 * cannot merge might become might become might become
762 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
763 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
764 * mremap move: PPPPNNNNNNNN 8
766 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
767 * might become case 1 below case 2 below case 3 below
769 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
770 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
772 struct vm_area_struct
*vma_merge(struct mm_struct
*mm
,
773 struct vm_area_struct
*prev
, unsigned long addr
,
774 unsigned long end
, unsigned long vm_flags
,
775 struct anon_vma
*anon_vma
, struct file
*file
,
776 pgoff_t pgoff
, struct mempolicy
*policy
)
778 pgoff_t pglen
= (end
- addr
) >> PAGE_SHIFT
;
779 struct vm_area_struct
*area
, *next
;
783 * We later require that vma->vm_flags == vm_flags,
784 * so this tests vma->vm_flags & VM_SPECIAL, too.
786 if (vm_flags
& VM_SPECIAL
)
790 next
= prev
->vm_next
;
794 if (next
&& next
->vm_end
== end
) /* cases 6, 7, 8 */
795 next
= next
->vm_next
;
798 * Can it merge with the predecessor?
800 if (prev
&& prev
->vm_end
== addr
&&
801 mpol_equal(vma_policy(prev
), policy
) &&
802 can_vma_merge_after(prev
, vm_flags
,
803 anon_vma
, file
, pgoff
)) {
805 * OK, it can. Can we now merge in the successor as well?
807 if (next
&& end
== next
->vm_start
&&
808 mpol_equal(policy
, vma_policy(next
)) &&
809 can_vma_merge_before(next
, vm_flags
,
810 anon_vma
, file
, pgoff
+pglen
) &&
811 is_mergeable_anon_vma(prev
->anon_vma
,
814 err
= vma_adjust(prev
, prev
->vm_start
,
815 next
->vm_end
, prev
->vm_pgoff
, NULL
);
816 } else /* cases 2, 5, 7 */
817 err
= vma_adjust(prev
, prev
->vm_start
,
818 end
, prev
->vm_pgoff
, NULL
);
821 khugepaged_enter_vma_merge(prev
);
826 * Can this new request be merged in front of next?
828 if (next
&& end
== next
->vm_start
&&
829 mpol_equal(policy
, vma_policy(next
)) &&
830 can_vma_merge_before(next
, vm_flags
,
831 anon_vma
, file
, pgoff
+pglen
)) {
832 if (prev
&& addr
< prev
->vm_end
) /* case 4 */
833 err
= vma_adjust(prev
, prev
->vm_start
,
834 addr
, prev
->vm_pgoff
, NULL
);
835 else /* cases 3, 8 */
836 err
= vma_adjust(area
, addr
, next
->vm_end
,
837 next
->vm_pgoff
- pglen
, NULL
);
840 khugepaged_enter_vma_merge(area
);
848 * Rough compatbility check to quickly see if it's even worth looking
849 * at sharing an anon_vma.
851 * They need to have the same vm_file, and the flags can only differ
852 * in things that mprotect may change.
854 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
855 * we can merge the two vma's. For example, we refuse to merge a vma if
856 * there is a vm_ops->close() function, because that indicates that the
857 * driver is doing some kind of reference counting. But that doesn't
858 * really matter for the anon_vma sharing case.
860 static int anon_vma_compatible(struct vm_area_struct
*a
, struct vm_area_struct
*b
)
862 return a
->vm_end
== b
->vm_start
&&
863 mpol_equal(vma_policy(a
), vma_policy(b
)) &&
864 a
->vm_file
== b
->vm_file
&&
865 !((a
->vm_flags
^ b
->vm_flags
) & ~(VM_READ
|VM_WRITE
|VM_EXEC
)) &&
866 b
->vm_pgoff
== a
->vm_pgoff
+ ((b
->vm_start
- a
->vm_start
) >> PAGE_SHIFT
);
870 * Do some basic sanity checking to see if we can re-use the anon_vma
871 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
872 * the same as 'old', the other will be the new one that is trying
873 * to share the anon_vma.
875 * NOTE! This runs with mm_sem held for reading, so it is possible that
876 * the anon_vma of 'old' is concurrently in the process of being set up
877 * by another page fault trying to merge _that_. But that's ok: if it
878 * is being set up, that automatically means that it will be a singleton
879 * acceptable for merging, so we can do all of this optimistically. But
880 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
882 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
883 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
884 * is to return an anon_vma that is "complex" due to having gone through
887 * We also make sure that the two vma's are compatible (adjacent,
888 * and with the same memory policies). That's all stable, even with just
889 * a read lock on the mm_sem.
891 static struct anon_vma
*reusable_anon_vma(struct vm_area_struct
*old
, struct vm_area_struct
*a
, struct vm_area_struct
*b
)
893 if (anon_vma_compatible(a
, b
)) {
894 struct anon_vma
*anon_vma
= ACCESS_ONCE(old
->anon_vma
);
896 if (anon_vma
&& list_is_singular(&old
->anon_vma_chain
))
903 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
904 * neighbouring vmas for a suitable anon_vma, before it goes off
905 * to allocate a new anon_vma. It checks because a repetitive
906 * sequence of mprotects and faults may otherwise lead to distinct
907 * anon_vmas being allocated, preventing vma merge in subsequent
910 struct anon_vma
*find_mergeable_anon_vma(struct vm_area_struct
*vma
)
912 struct anon_vma
*anon_vma
;
913 struct vm_area_struct
*near
;
919 anon_vma
= reusable_anon_vma(near
, vma
, near
);
924 * It is potentially slow to have to call find_vma_prev here.
925 * But it's only on the first write fault on the vma, not
926 * every time, and we could devise a way to avoid it later
927 * (e.g. stash info in next's anon_vma_node when assigning
928 * an anon_vma, or when trying vma_merge). Another time.
930 BUG_ON(find_vma_prev(vma
->vm_mm
, vma
->vm_start
, &near
) != vma
);
934 anon_vma
= reusable_anon_vma(near
, near
, vma
);
939 * There's no absolute need to look only at touching neighbours:
940 * we could search further afield for "compatible" anon_vmas.
941 * But it would probably just be a waste of time searching,
942 * or lead to too many vmas hanging off the same anon_vma.
943 * We're trying to allow mprotect remerging later on,
944 * not trying to minimize memory used for anon_vmas.
949 #ifdef CONFIG_PROC_FS
950 void vm_stat_account(struct mm_struct
*mm
, unsigned long flags
,
951 struct file
*file
, long pages
)
953 const unsigned long stack_flags
954 = VM_STACK_FLAGS
& (VM_GROWSUP
|VM_GROWSDOWN
);
957 mm
->shared_vm
+= pages
;
958 if ((flags
& (VM_EXEC
|VM_WRITE
)) == VM_EXEC
)
959 mm
->exec_vm
+= pages
;
960 } else if (flags
& stack_flags
)
961 mm
->stack_vm
+= pages
;
962 if (flags
& (VM_RESERVED
|VM_IO
))
963 mm
->reserved_vm
+= pages
;
965 #endif /* CONFIG_PROC_FS */
968 * The caller must hold down_write(¤t->mm->mmap_sem).
971 unsigned long do_mmap_pgoff(struct file
*file
, unsigned long addr
,
972 unsigned long len
, unsigned long prot
,
973 unsigned long flags
, unsigned long pgoff
)
975 struct mm_struct
* mm
= current
->mm
;
977 unsigned int vm_flags
;
979 unsigned long reqprot
= prot
;
982 * Does the application expect PROT_READ to imply PROT_EXEC?
984 * (the exception is when the underlying filesystem is noexec
985 * mounted, in which case we dont add PROT_EXEC.)
987 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
988 if (!(file
&& (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
)))
994 if (!(flags
& MAP_FIXED
))
995 addr
= round_hint_to_min(addr
);
997 /* Careful about overflows.. */
998 len
= PAGE_ALIGN(len
);
1002 /* offset overflow? */
1003 if ((pgoff
+ (len
>> PAGE_SHIFT
)) < pgoff
)
1006 /* Too many mappings? */
1007 if (mm
->map_count
> sysctl_max_map_count
)
1010 /* Obtain the address to map to. we verify (or select) it and ensure
1011 * that it represents a valid section of the address space.
1013 addr
= get_unmapped_area(file
, addr
, len
, pgoff
, flags
);
1014 if (addr
& ~PAGE_MASK
)
1017 /* Do simple checking here so the lower-level routines won't have
1018 * to. we assume access permissions have been handled by the open
1019 * of the memory object, so we don't do any here.
1021 vm_flags
= calc_vm_prot_bits(prot
) | calc_vm_flag_bits(flags
) |
1022 mm
->def_flags
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1024 if (flags
& MAP_LOCKED
)
1025 if (!can_do_mlock())
1028 /* mlock MCL_FUTURE? */
1029 if (vm_flags
& VM_LOCKED
) {
1030 unsigned long locked
, lock_limit
;
1031 locked
= len
>> PAGE_SHIFT
;
1032 locked
+= mm
->locked_vm
;
1033 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
1034 lock_limit
>>= PAGE_SHIFT
;
1035 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
1039 inode
= file
? file
->f_path
.dentry
->d_inode
: NULL
;
1042 switch (flags
& MAP_TYPE
) {
1044 if ((prot
&PROT_WRITE
) && !(file
->f_mode
&FMODE_WRITE
))
1048 * Make sure we don't allow writing to an append-only
1051 if (IS_APPEND(inode
) && (file
->f_mode
& FMODE_WRITE
))
1055 * Make sure there are no mandatory locks on the file.
1057 if (locks_verify_locked(inode
))
1060 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1061 if (!(file
->f_mode
& FMODE_WRITE
))
1062 vm_flags
&= ~(VM_MAYWRITE
| VM_SHARED
);
1066 if (!(file
->f_mode
& FMODE_READ
))
1068 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
) {
1069 if (vm_flags
& VM_EXEC
)
1071 vm_flags
&= ~VM_MAYEXEC
;
1074 if (!file
->f_op
|| !file
->f_op
->mmap
)
1082 switch (flags
& MAP_TYPE
) {
1088 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1092 * Set pgoff according to addr for anon_vma.
1094 pgoff
= addr
>> PAGE_SHIFT
;
1101 error
= security_file_mmap(file
, reqprot
, prot
, flags
, addr
, 0);
1105 return mmap_region(file
, addr
, len
, flags
, vm_flags
, pgoff
);
1107 EXPORT_SYMBOL(do_mmap_pgoff
);
1109 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1110 unsigned long, prot
, unsigned long, flags
,
1111 unsigned long, fd
, unsigned long, pgoff
)
1113 struct file
*file
= NULL
;
1114 unsigned long retval
= -EBADF
;
1116 if (!(flags
& MAP_ANONYMOUS
)) {
1117 audit_mmap_fd(fd
, flags
);
1118 if (unlikely(flags
& MAP_HUGETLB
))
1123 } else if (flags
& MAP_HUGETLB
) {
1124 struct user_struct
*user
= NULL
;
1126 * VM_NORESERVE is used because the reservations will be
1127 * taken when vm_ops->mmap() is called
1128 * A dummy user value is used because we are not locking
1129 * memory so no accounting is necessary
1131 len
= ALIGN(len
, huge_page_size(&default_hstate
));
1132 file
= hugetlb_file_setup(HUGETLB_ANON_FILE
, len
, VM_NORESERVE
,
1133 &user
, HUGETLB_ANONHUGE_INODE
);
1135 return PTR_ERR(file
);
1138 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1140 down_write(¤t
->mm
->mmap_sem
);
1141 retval
= do_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1142 up_write(¤t
->mm
->mmap_sem
);
1150 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1151 struct mmap_arg_struct
{
1155 unsigned long flags
;
1157 unsigned long offset
;
1160 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1162 struct mmap_arg_struct a
;
1164 if (copy_from_user(&a
, arg
, sizeof(a
)))
1166 if (a
.offset
& ~PAGE_MASK
)
1169 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1170 a
.offset
>> PAGE_SHIFT
);
1172 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1175 * Some shared mappigns will want the pages marked read-only
1176 * to track write events. If so, we'll downgrade vm_page_prot
1177 * to the private version (using protection_map[] without the
1180 int vma_wants_writenotify(struct vm_area_struct
*vma
)
1182 unsigned int vm_flags
= vma
->vm_flags
;
1184 /* If it was private or non-writable, the write bit is already clear */
1185 if ((vm_flags
& (VM_WRITE
|VM_SHARED
)) != ((VM_WRITE
|VM_SHARED
)))
1188 /* The backer wishes to know when pages are first written to? */
1189 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
)
1192 /* The open routine did something to the protections already? */
1193 if (pgprot_val(vma
->vm_page_prot
) !=
1194 pgprot_val(vm_get_page_prot(vm_flags
)))
1197 /* Specialty mapping? */
1198 if (vm_flags
& (VM_PFNMAP
|VM_INSERTPAGE
))
1201 /* Can the mapping track the dirty pages? */
1202 return vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
1203 mapping_cap_account_dirty(vma
->vm_file
->f_mapping
);
1207 * We account for memory if it's a private writeable mapping,
1208 * not hugepages and VM_NORESERVE wasn't set.
1210 static inline int accountable_mapping(struct file
*file
, unsigned int vm_flags
)
1213 * hugetlb has its own accounting separate from the core VM
1214 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1216 if (file
&& is_file_hugepages(file
))
1219 return (vm_flags
& (VM_NORESERVE
| VM_SHARED
| VM_WRITE
)) == VM_WRITE
;
1222 unsigned long mmap_region(struct file
*file
, unsigned long addr
,
1223 unsigned long len
, unsigned long flags
,
1224 unsigned int vm_flags
, unsigned long pgoff
)
1226 struct mm_struct
*mm
= current
->mm
;
1227 struct vm_area_struct
*vma
, *prev
;
1228 int correct_wcount
= 0;
1230 struct rb_node
**rb_link
, *rb_parent
;
1231 unsigned long charged
= 0;
1232 struct inode
*inode
= file
? file
->f_path
.dentry
->d_inode
: NULL
;
1234 /* Clear old maps */
1237 vma
= find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
1238 if (vma
&& vma
->vm_start
< addr
+ len
) {
1239 if (do_munmap(mm
, addr
, len
))
1244 /* Check against address space limit. */
1245 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
))
1249 * Set 'VM_NORESERVE' if we should not account for the
1250 * memory use of this mapping.
1252 if ((flags
& MAP_NORESERVE
)) {
1253 /* We honor MAP_NORESERVE if allowed to overcommit */
1254 if (sysctl_overcommit_memory
!= OVERCOMMIT_NEVER
)
1255 vm_flags
|= VM_NORESERVE
;
1257 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1258 if (file
&& is_file_hugepages(file
))
1259 vm_flags
|= VM_NORESERVE
;
1263 * Private writable mapping: check memory availability
1265 if (accountable_mapping(file
, vm_flags
)) {
1266 charged
= len
>> PAGE_SHIFT
;
1267 if (security_vm_enough_memory(charged
))
1269 vm_flags
|= VM_ACCOUNT
;
1273 * Can we just expand an old mapping?
1275 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vm_flags
, NULL
, file
, pgoff
, NULL
);
1280 * Determine the object being mapped and call the appropriate
1281 * specific mapper. the address has already been validated, but
1282 * not unmapped, but the maps are removed from the list.
1284 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1291 vma
->vm_start
= addr
;
1292 vma
->vm_end
= addr
+ len
;
1293 vma
->vm_flags
= vm_flags
;
1294 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
);
1295 vma
->vm_pgoff
= pgoff
;
1296 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1300 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1302 if (vm_flags
& VM_DENYWRITE
) {
1303 error
= deny_write_access(file
);
1308 vma
->vm_file
= file
;
1310 error
= file
->f_op
->mmap(file
, vma
);
1312 goto unmap_and_free_vma
;
1313 if (vm_flags
& VM_EXECUTABLE
)
1314 added_exe_file_vma(mm
);
1316 /* Can addr have changed??
1318 * Answer: Yes, several device drivers can do it in their
1319 * f_op->mmap method. -DaveM
1321 addr
= vma
->vm_start
;
1322 pgoff
= vma
->vm_pgoff
;
1323 vm_flags
= vma
->vm_flags
;
1324 } else if (vm_flags
& VM_SHARED
) {
1325 error
= shmem_zero_setup(vma
);
1330 if (vma_wants_writenotify(vma
)) {
1331 pgprot_t pprot
= vma
->vm_page_prot
;
1333 /* Can vma->vm_page_prot have changed??
1335 * Answer: Yes, drivers may have changed it in their
1336 * f_op->mmap method.
1338 * Ensures that vmas marked as uncached stay that way.
1340 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
& ~VM_SHARED
);
1341 if (pgprot_val(pprot
) == pgprot_val(pgprot_noncached(pprot
)))
1342 vma
->vm_page_prot
= pgprot_noncached(vma
->vm_page_prot
);
1345 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
1346 file
= vma
->vm_file
;
1348 /* Once vma denies write, undo our temporary denial count */
1350 atomic_inc(&inode
->i_writecount
);
1352 perf_event_mmap(vma
);
1354 mm
->total_vm
+= len
>> PAGE_SHIFT
;
1355 vm_stat_account(mm
, vm_flags
, file
, len
>> PAGE_SHIFT
);
1356 if (vm_flags
& VM_LOCKED
) {
1357 if (!mlock_vma_pages_range(vma
, addr
, addr
+ len
))
1358 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
1359 } else if ((flags
& MAP_POPULATE
) && !(flags
& MAP_NONBLOCK
))
1360 make_pages_present(addr
, addr
+ len
);
1365 atomic_inc(&inode
->i_writecount
);
1366 vma
->vm_file
= NULL
;
1369 /* Undo any partial mapping done by a device driver. */
1370 unmap_region(mm
, vma
, prev
, vma
->vm_start
, vma
->vm_end
);
1373 kmem_cache_free(vm_area_cachep
, vma
);
1376 vm_unacct_memory(charged
);
1380 /* Get an address range which is currently unmapped.
1381 * For shmat() with addr=0.
1383 * Ugly calling convention alert:
1384 * Return value with the low bits set means error value,
1386 * if (ret & ~PAGE_MASK)
1389 * This function "knows" that -ENOMEM has the bits set.
1391 #ifndef HAVE_ARCH_UNMAPPED_AREA
1393 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
1394 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1396 struct mm_struct
*mm
= current
->mm
;
1397 struct vm_area_struct
*vma
;
1398 unsigned long start_addr
;
1400 if (len
> TASK_SIZE
)
1403 if (flags
& MAP_FIXED
)
1407 addr
= PAGE_ALIGN(addr
);
1408 vma
= find_vma(mm
, addr
);
1409 if (TASK_SIZE
- len
>= addr
&&
1410 (!vma
|| addr
+ len
<= vma
->vm_start
))
1413 if (len
> mm
->cached_hole_size
) {
1414 start_addr
= addr
= mm
->free_area_cache
;
1416 start_addr
= addr
= TASK_UNMAPPED_BASE
;
1417 mm
->cached_hole_size
= 0;
1421 for (vma
= find_vma(mm
, addr
); ; vma
= vma
->vm_next
) {
1422 /* At this point: (!vma || addr < vma->vm_end). */
1423 if (TASK_SIZE
- len
< addr
) {
1425 * Start a new search - just in case we missed
1428 if (start_addr
!= TASK_UNMAPPED_BASE
) {
1429 addr
= TASK_UNMAPPED_BASE
;
1431 mm
->cached_hole_size
= 0;
1436 if (!vma
|| addr
+ len
<= vma
->vm_start
) {
1438 * Remember the place where we stopped the search:
1440 mm
->free_area_cache
= addr
+ len
;
1443 if (addr
+ mm
->cached_hole_size
< vma
->vm_start
)
1444 mm
->cached_hole_size
= vma
->vm_start
- addr
;
1450 void arch_unmap_area(struct mm_struct
*mm
, unsigned long addr
)
1453 * Is this a new hole at the lowest possible address?
1455 if (addr
>= TASK_UNMAPPED_BASE
&& addr
< mm
->free_area_cache
) {
1456 mm
->free_area_cache
= addr
;
1457 mm
->cached_hole_size
= ~0UL;
1462 * This mmap-allocator allocates new areas top-down from below the
1463 * stack's low limit (the base):
1465 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1467 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
1468 const unsigned long len
, const unsigned long pgoff
,
1469 const unsigned long flags
)
1471 struct vm_area_struct
*vma
;
1472 struct mm_struct
*mm
= current
->mm
;
1473 unsigned long addr
= addr0
;
1475 /* requested length too big for entire address space */
1476 if (len
> TASK_SIZE
)
1479 if (flags
& MAP_FIXED
)
1482 /* requesting a specific address */
1484 addr
= PAGE_ALIGN(addr
);
1485 vma
= find_vma(mm
, addr
);
1486 if (TASK_SIZE
- len
>= addr
&&
1487 (!vma
|| addr
+ len
<= vma
->vm_start
))
1491 /* check if free_area_cache is useful for us */
1492 if (len
<= mm
->cached_hole_size
) {
1493 mm
->cached_hole_size
= 0;
1494 mm
->free_area_cache
= mm
->mmap_base
;
1497 /* either no address requested or can't fit in requested address hole */
1498 addr
= mm
->free_area_cache
;
1500 /* make sure it can fit in the remaining address space */
1502 vma
= find_vma(mm
, addr
-len
);
1503 if (!vma
|| addr
<= vma
->vm_start
)
1504 /* remember the address as a hint for next time */
1505 return (mm
->free_area_cache
= addr
-len
);
1508 if (mm
->mmap_base
< len
)
1511 addr
= mm
->mmap_base
-len
;
1515 * Lookup failure means no vma is above this address,
1516 * else if new region fits below vma->vm_start,
1517 * return with success:
1519 vma
= find_vma(mm
, addr
);
1520 if (!vma
|| addr
+len
<= vma
->vm_start
)
1521 /* remember the address as a hint for next time */
1522 return (mm
->free_area_cache
= addr
);
1524 /* remember the largest hole we saw so far */
1525 if (addr
+ mm
->cached_hole_size
< vma
->vm_start
)
1526 mm
->cached_hole_size
= vma
->vm_start
- addr
;
1528 /* try just below the current vma->vm_start */
1529 addr
= vma
->vm_start
-len
;
1530 } while (len
< vma
->vm_start
);
1534 * A failed mmap() very likely causes application failure,
1535 * so fall back to the bottom-up function here. This scenario
1536 * can happen with large stack limits and large mmap()
1539 mm
->cached_hole_size
= ~0UL;
1540 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
1541 addr
= arch_get_unmapped_area(filp
, addr0
, len
, pgoff
, flags
);
1543 * Restore the topdown base:
1545 mm
->free_area_cache
= mm
->mmap_base
;
1546 mm
->cached_hole_size
= ~0UL;
1552 void arch_unmap_area_topdown(struct mm_struct
*mm
, unsigned long addr
)
1555 * Is this a new hole at the highest possible address?
1557 if (addr
> mm
->free_area_cache
)
1558 mm
->free_area_cache
= addr
;
1560 /* dont allow allocations above current base */
1561 if (mm
->free_area_cache
> mm
->mmap_base
)
1562 mm
->free_area_cache
= mm
->mmap_base
;
1566 get_unmapped_area(struct file
*file
, unsigned long addr
, unsigned long len
,
1567 unsigned long pgoff
, unsigned long flags
)
1569 unsigned long (*get_area
)(struct file
*, unsigned long,
1570 unsigned long, unsigned long, unsigned long);
1572 unsigned long error
= arch_mmap_check(addr
, len
, flags
);
1576 /* Careful about overflows.. */
1577 if (len
> TASK_SIZE
)
1580 get_area
= current
->mm
->get_unmapped_area
;
1581 if (file
&& file
->f_op
&& file
->f_op
->get_unmapped_area
)
1582 get_area
= file
->f_op
->get_unmapped_area
;
1583 addr
= get_area(file
, addr
, len
, pgoff
, flags
);
1584 if (IS_ERR_VALUE(addr
))
1587 if (addr
> TASK_SIZE
- len
)
1589 if (addr
& ~PAGE_MASK
)
1592 return arch_rebalance_pgtables(addr
, len
);
1595 EXPORT_SYMBOL(get_unmapped_area
);
1597 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1598 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
1600 struct vm_area_struct
*vma
= NULL
;
1603 /* Check the cache first. */
1604 /* (Cache hit rate is typically around 35%.) */
1605 vma
= mm
->mmap_cache
;
1606 if (!(vma
&& vma
->vm_end
> addr
&& vma
->vm_start
<= addr
)) {
1607 struct rb_node
* rb_node
;
1609 rb_node
= mm
->mm_rb
.rb_node
;
1613 struct vm_area_struct
* vma_tmp
;
1615 vma_tmp
= rb_entry(rb_node
,
1616 struct vm_area_struct
, vm_rb
);
1618 if (vma_tmp
->vm_end
> addr
) {
1620 if (vma_tmp
->vm_start
<= addr
)
1622 rb_node
= rb_node
->rb_left
;
1624 rb_node
= rb_node
->rb_right
;
1627 mm
->mmap_cache
= vma
;
1633 EXPORT_SYMBOL(find_vma
);
1635 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1636 struct vm_area_struct
*
1637 find_vma_prev(struct mm_struct
*mm
, unsigned long addr
,
1638 struct vm_area_struct
**pprev
)
1640 struct vm_area_struct
*vma
= NULL
, *prev
= NULL
;
1641 struct rb_node
*rb_node
;
1645 /* Guard against addr being lower than the first VMA */
1648 /* Go through the RB tree quickly. */
1649 rb_node
= mm
->mm_rb
.rb_node
;
1652 struct vm_area_struct
*vma_tmp
;
1653 vma_tmp
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
1655 if (addr
< vma_tmp
->vm_end
) {
1656 rb_node
= rb_node
->rb_left
;
1659 if (!prev
->vm_next
|| (addr
< prev
->vm_next
->vm_end
))
1661 rb_node
= rb_node
->rb_right
;
1667 return prev
? prev
->vm_next
: vma
;
1671 * Verify that the stack growth is acceptable and
1672 * update accounting. This is shared with both the
1673 * grow-up and grow-down cases.
1675 static int acct_stack_growth(struct vm_area_struct
*vma
, unsigned long size
, unsigned long grow
)
1677 struct mm_struct
*mm
= vma
->vm_mm
;
1678 struct rlimit
*rlim
= current
->signal
->rlim
;
1679 unsigned long new_start
;
1681 /* address space limit tests */
1682 if (!may_expand_vm(mm
, grow
))
1685 /* Stack limit test */
1686 if (size
> ACCESS_ONCE(rlim
[RLIMIT_STACK
].rlim_cur
))
1689 /* mlock limit tests */
1690 if (vma
->vm_flags
& VM_LOCKED
) {
1691 unsigned long locked
;
1692 unsigned long limit
;
1693 locked
= mm
->locked_vm
+ grow
;
1694 limit
= ACCESS_ONCE(rlim
[RLIMIT_MEMLOCK
].rlim_cur
);
1695 limit
>>= PAGE_SHIFT
;
1696 if (locked
> limit
&& !capable(CAP_IPC_LOCK
))
1700 /* Check to ensure the stack will not grow into a hugetlb-only region */
1701 new_start
= (vma
->vm_flags
& VM_GROWSUP
) ? vma
->vm_start
:
1703 if (is_hugepage_only_range(vma
->vm_mm
, new_start
, size
))
1707 * Overcommit.. This must be the final test, as it will
1708 * update security statistics.
1710 if (security_vm_enough_memory_mm(mm
, grow
))
1713 /* Ok, everything looks good - let it rip */
1714 mm
->total_vm
+= grow
;
1715 if (vma
->vm_flags
& VM_LOCKED
)
1716 mm
->locked_vm
+= grow
;
1717 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, grow
);
1721 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1723 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1724 * vma is the last one with address > vma->vm_end. Have to extend vma.
1726 int expand_upwards(struct vm_area_struct
*vma
, unsigned long address
)
1730 if (!(vma
->vm_flags
& VM_GROWSUP
))
1734 * We must make sure the anon_vma is allocated
1735 * so that the anon_vma locking is not a noop.
1737 if (unlikely(anon_vma_prepare(vma
)))
1739 vma_lock_anon_vma(vma
);
1742 * vma->vm_start/vm_end cannot change under us because the caller
1743 * is required to hold the mmap_sem in read mode. We need the
1744 * anon_vma lock to serialize against concurrent expand_stacks.
1745 * Also guard against wrapping around to address 0.
1747 if (address
< PAGE_ALIGN(address
+4))
1748 address
= PAGE_ALIGN(address
+4);
1750 vma_unlock_anon_vma(vma
);
1755 /* Somebody else might have raced and expanded it already */
1756 if (address
> vma
->vm_end
) {
1757 unsigned long size
, grow
;
1759 size
= address
- vma
->vm_start
;
1760 grow
= (address
- vma
->vm_end
) >> PAGE_SHIFT
;
1762 error
= acct_stack_growth(vma
, size
, grow
);
1764 vma
->vm_end
= address
;
1765 perf_event_mmap(vma
);
1768 vma_unlock_anon_vma(vma
);
1769 khugepaged_enter_vma_merge(vma
);
1772 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1775 * vma is the first one with address < vma->vm_start. Have to extend vma.
1777 static int expand_downwards(struct vm_area_struct
*vma
,
1778 unsigned long address
)
1783 * We must make sure the anon_vma is allocated
1784 * so that the anon_vma locking is not a noop.
1786 if (unlikely(anon_vma_prepare(vma
)))
1789 address
&= PAGE_MASK
;
1790 error
= security_file_mmap(NULL
, 0, 0, 0, address
, 1);
1794 vma_lock_anon_vma(vma
);
1797 * vma->vm_start/vm_end cannot change under us because the caller
1798 * is required to hold the mmap_sem in read mode. We need the
1799 * anon_vma lock to serialize against concurrent expand_stacks.
1802 /* Somebody else might have raced and expanded it already */
1803 if (address
< vma
->vm_start
) {
1804 unsigned long size
, grow
;
1806 size
= vma
->vm_end
- address
;
1807 grow
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
1809 error
= acct_stack_growth(vma
, size
, grow
);
1811 vma
->vm_start
= address
;
1812 vma
->vm_pgoff
-= grow
;
1813 perf_event_mmap(vma
);
1816 vma_unlock_anon_vma(vma
);
1817 khugepaged_enter_vma_merge(vma
);
1821 int expand_stack_downwards(struct vm_area_struct
*vma
, unsigned long address
)
1823 return expand_downwards(vma
, address
);
1826 #ifdef CONFIG_STACK_GROWSUP
1827 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
1829 return expand_upwards(vma
, address
);
1832 struct vm_area_struct
*
1833 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
1835 struct vm_area_struct
*vma
, *prev
;
1838 vma
= find_vma_prev(mm
, addr
, &prev
);
1839 if (vma
&& (vma
->vm_start
<= addr
))
1841 if (!prev
|| expand_stack(prev
, addr
))
1843 if (prev
->vm_flags
& VM_LOCKED
) {
1844 mlock_vma_pages_range(prev
, addr
, prev
->vm_end
);
1849 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
1851 return expand_downwards(vma
, address
);
1854 struct vm_area_struct
*
1855 find_extend_vma(struct mm_struct
* mm
, unsigned long addr
)
1857 struct vm_area_struct
* vma
;
1858 unsigned long start
;
1861 vma
= find_vma(mm
,addr
);
1864 if (vma
->vm_start
<= addr
)
1866 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
1868 start
= vma
->vm_start
;
1869 if (expand_stack(vma
, addr
))
1871 if (vma
->vm_flags
& VM_LOCKED
) {
1872 mlock_vma_pages_range(vma
, addr
, start
);
1879 * Ok - we have the memory areas we should free on the vma list,
1880 * so release them, and do the vma updates.
1882 * Called with the mm semaphore held.
1884 static void remove_vma_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
1886 /* Update high watermark before we lower total_vm */
1887 update_hiwater_vm(mm
);
1889 long nrpages
= vma_pages(vma
);
1891 mm
->total_vm
-= nrpages
;
1892 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, -nrpages
);
1893 vma
= remove_vma(vma
);
1899 * Get rid of page table information in the indicated region.
1901 * Called with the mm semaphore held.
1903 static void unmap_region(struct mm_struct
*mm
,
1904 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
1905 unsigned long start
, unsigned long end
)
1907 struct vm_area_struct
*next
= prev
? prev
->vm_next
: mm
->mmap
;
1908 struct mmu_gather
*tlb
;
1909 unsigned long nr_accounted
= 0;
1912 tlb
= tlb_gather_mmu(mm
, 0);
1913 update_hiwater_rss(mm
);
1914 unmap_vmas(&tlb
, vma
, start
, end
, &nr_accounted
, NULL
);
1915 vm_unacct_memory(nr_accounted
);
1916 free_pgtables(tlb
, vma
, prev
? prev
->vm_end
: FIRST_USER_ADDRESS
,
1917 next
? next
->vm_start
: 0);
1918 tlb_finish_mmu(tlb
, start
, end
);
1922 * Create a list of vma's touched by the unmap, removing them from the mm's
1923 * vma list as we go..
1926 detach_vmas_to_be_unmapped(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1927 struct vm_area_struct
*prev
, unsigned long end
)
1929 struct vm_area_struct
**insertion_point
;
1930 struct vm_area_struct
*tail_vma
= NULL
;
1933 insertion_point
= (prev
? &prev
->vm_next
: &mm
->mmap
);
1934 vma
->vm_prev
= NULL
;
1936 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
1940 } while (vma
&& vma
->vm_start
< end
);
1941 *insertion_point
= vma
;
1943 vma
->vm_prev
= prev
;
1944 tail_vma
->vm_next
= NULL
;
1945 if (mm
->unmap_area
== arch_unmap_area
)
1946 addr
= prev
? prev
->vm_end
: mm
->mmap_base
;
1948 addr
= vma
? vma
->vm_start
: mm
->mmap_base
;
1949 mm
->unmap_area(mm
, addr
);
1950 mm
->mmap_cache
= NULL
; /* Kill the cache. */
1954 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1955 * munmap path where it doesn't make sense to fail.
1957 static int __split_vma(struct mm_struct
* mm
, struct vm_area_struct
* vma
,
1958 unsigned long addr
, int new_below
)
1960 struct mempolicy
*pol
;
1961 struct vm_area_struct
*new;
1964 if (is_vm_hugetlb_page(vma
) && (addr
&
1965 ~(huge_page_mask(hstate_vma(vma
)))))
1968 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
1972 /* most fields are the same, copy all, and then fixup */
1975 INIT_LIST_HEAD(&new->anon_vma_chain
);
1980 new->vm_start
= addr
;
1981 new->vm_pgoff
+= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
);
1984 pol
= mpol_dup(vma_policy(vma
));
1989 vma_set_policy(new, pol
);
1991 if (anon_vma_clone(new, vma
))
1995 get_file(new->vm_file
);
1996 if (vma
->vm_flags
& VM_EXECUTABLE
)
1997 added_exe_file_vma(mm
);
2000 if (new->vm_ops
&& new->vm_ops
->open
)
2001 new->vm_ops
->open(new);
2004 err
= vma_adjust(vma
, addr
, vma
->vm_end
, vma
->vm_pgoff
+
2005 ((addr
- new->vm_start
) >> PAGE_SHIFT
), new);
2007 err
= vma_adjust(vma
, vma
->vm_start
, addr
, vma
->vm_pgoff
, new);
2013 /* Clean everything up if vma_adjust failed. */
2014 if (new->vm_ops
&& new->vm_ops
->close
)
2015 new->vm_ops
->close(new);
2017 if (vma
->vm_flags
& VM_EXECUTABLE
)
2018 removed_exe_file_vma(mm
);
2021 unlink_anon_vmas(new);
2025 kmem_cache_free(vm_area_cachep
, new);
2031 * Split a vma into two pieces at address 'addr', a new vma is allocated
2032 * either for the first part or the tail.
2034 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2035 unsigned long addr
, int new_below
)
2037 if (mm
->map_count
>= sysctl_max_map_count
)
2040 return __split_vma(mm
, vma
, addr
, new_below
);
2043 /* Munmap is split into 2 main parts -- this part which finds
2044 * what needs doing, and the areas themselves, which do the
2045 * work. This now handles partial unmappings.
2046 * Jeremy Fitzhardinge <jeremy@goop.org>
2048 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
)
2051 struct vm_area_struct
*vma
, *prev
, *last
;
2053 if ((start
& ~PAGE_MASK
) || start
> TASK_SIZE
|| len
> TASK_SIZE
-start
)
2056 if ((len
= PAGE_ALIGN(len
)) == 0)
2059 /* Find the first overlapping VMA */
2060 vma
= find_vma_prev(mm
, start
, &prev
);
2063 /* we have start < vma->vm_end */
2065 /* if it doesn't overlap, we have nothing.. */
2067 if (vma
->vm_start
>= end
)
2071 * If we need to split any vma, do it now to save pain later.
2073 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2074 * unmapped vm_area_struct will remain in use: so lower split_vma
2075 * places tmp vma above, and higher split_vma places tmp vma below.
2077 if (start
> vma
->vm_start
) {
2081 * Make sure that map_count on return from munmap() will
2082 * not exceed its limit; but let map_count go just above
2083 * its limit temporarily, to help free resources as expected.
2085 if (end
< vma
->vm_end
&& mm
->map_count
>= sysctl_max_map_count
)
2088 error
= __split_vma(mm
, vma
, start
, 0);
2094 /* Does it split the last one? */
2095 last
= find_vma(mm
, end
);
2096 if (last
&& end
> last
->vm_start
) {
2097 int error
= __split_vma(mm
, last
, end
, 1);
2101 vma
= prev
? prev
->vm_next
: mm
->mmap
;
2104 * unlock any mlock()ed ranges before detaching vmas
2106 if (mm
->locked_vm
) {
2107 struct vm_area_struct
*tmp
= vma
;
2108 while (tmp
&& tmp
->vm_start
< end
) {
2109 if (tmp
->vm_flags
& VM_LOCKED
) {
2110 mm
->locked_vm
-= vma_pages(tmp
);
2111 munlock_vma_pages_all(tmp
);
2118 * Remove the vma's, and unmap the actual pages
2120 detach_vmas_to_be_unmapped(mm
, vma
, prev
, end
);
2121 unmap_region(mm
, vma
, prev
, start
, end
);
2123 /* Fix up all other VM information */
2124 remove_vma_list(mm
, vma
);
2129 EXPORT_SYMBOL(do_munmap
);
2131 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
2134 struct mm_struct
*mm
= current
->mm
;
2136 profile_munmap(addr
);
2138 down_write(&mm
->mmap_sem
);
2139 ret
= do_munmap(mm
, addr
, len
);
2140 up_write(&mm
->mmap_sem
);
2144 static inline void verify_mm_writelocked(struct mm_struct
*mm
)
2146 #ifdef CONFIG_DEBUG_VM
2147 if (unlikely(down_read_trylock(&mm
->mmap_sem
))) {
2149 up_read(&mm
->mmap_sem
);
2155 * this is really a simplified "do_mmap". it only handles
2156 * anonymous maps. eventually we may be able to do some
2157 * brk-specific accounting here.
2159 unsigned long do_brk(unsigned long addr
, unsigned long len
)
2161 struct mm_struct
* mm
= current
->mm
;
2162 struct vm_area_struct
* vma
, * prev
;
2163 unsigned long flags
;
2164 struct rb_node
** rb_link
, * rb_parent
;
2165 pgoff_t pgoff
= addr
>> PAGE_SHIFT
;
2168 len
= PAGE_ALIGN(len
);
2172 error
= security_file_mmap(NULL
, 0, 0, 0, addr
, 1);
2176 flags
= VM_DATA_DEFAULT_FLAGS
| VM_ACCOUNT
| mm
->def_flags
;
2178 error
= get_unmapped_area(NULL
, addr
, len
, 0, MAP_FIXED
);
2179 if (error
& ~PAGE_MASK
)
2185 if (mm
->def_flags
& VM_LOCKED
) {
2186 unsigned long locked
, lock_limit
;
2187 locked
= len
>> PAGE_SHIFT
;
2188 locked
+= mm
->locked_vm
;
2189 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
2190 lock_limit
>>= PAGE_SHIFT
;
2191 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
2196 * mm->mmap_sem is required to protect against another thread
2197 * changing the mappings in case we sleep.
2199 verify_mm_writelocked(mm
);
2202 * Clear old maps. this also does some error checking for us
2205 vma
= find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
2206 if (vma
&& vma
->vm_start
< addr
+ len
) {
2207 if (do_munmap(mm
, addr
, len
))
2212 /* Check against address space limits *after* clearing old maps... */
2213 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
))
2216 if (mm
->map_count
> sysctl_max_map_count
)
2219 if (security_vm_enough_memory(len
>> PAGE_SHIFT
))
2222 /* Can we just expand an old private anonymous mapping? */
2223 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, flags
,
2224 NULL
, NULL
, pgoff
, NULL
);
2229 * create a vma struct for an anonymous mapping
2231 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2233 vm_unacct_memory(len
>> PAGE_SHIFT
);
2237 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2239 vma
->vm_start
= addr
;
2240 vma
->vm_end
= addr
+ len
;
2241 vma
->vm_pgoff
= pgoff
;
2242 vma
->vm_flags
= flags
;
2243 vma
->vm_page_prot
= vm_get_page_prot(flags
);
2244 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2246 perf_event_mmap(vma
);
2247 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2248 if (flags
& VM_LOCKED
) {
2249 if (!mlock_vma_pages_range(vma
, addr
, addr
+ len
))
2250 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
2255 EXPORT_SYMBOL(do_brk
);
2257 /* Release all mmaps. */
2258 void exit_mmap(struct mm_struct
*mm
)
2260 struct mmu_gather
*tlb
;
2261 struct vm_area_struct
*vma
;
2262 unsigned long nr_accounted
= 0;
2265 /* mm's last user has gone, and its about to be pulled down */
2266 mmu_notifier_release(mm
);
2268 if (mm
->locked_vm
) {
2271 if (vma
->vm_flags
& VM_LOCKED
)
2272 munlock_vma_pages_all(vma
);
2280 if (!vma
) /* Can happen if dup_mmap() received an OOM */
2285 tlb
= tlb_gather_mmu(mm
, 1);
2286 /* update_hiwater_rss(mm) here? but nobody should be looking */
2287 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2288 end
= unmap_vmas(&tlb
, vma
, 0, -1, &nr_accounted
, NULL
);
2289 vm_unacct_memory(nr_accounted
);
2291 free_pgtables(tlb
, vma
, FIRST_USER_ADDRESS
, 0);
2292 tlb_finish_mmu(tlb
, 0, end
);
2295 * Walk the list again, actually closing and freeing it,
2296 * with preemption enabled, without holding any MM locks.
2299 vma
= remove_vma(vma
);
2301 BUG_ON(mm
->nr_ptes
> (FIRST_USER_ADDRESS
+PMD_SIZE
-1)>>PMD_SHIFT
);
2304 /* Insert vm structure into process list sorted by address
2305 * and into the inode's i_mmap tree. If vm_file is non-NULL
2306 * then i_mmap_lock is taken here.
2308 int insert_vm_struct(struct mm_struct
* mm
, struct vm_area_struct
* vma
)
2310 struct vm_area_struct
* __vma
, * prev
;
2311 struct rb_node
** rb_link
, * rb_parent
;
2314 * The vm_pgoff of a purely anonymous vma should be irrelevant
2315 * until its first write fault, when page's anon_vma and index
2316 * are set. But now set the vm_pgoff it will almost certainly
2317 * end up with (unless mremap moves it elsewhere before that
2318 * first wfault), so /proc/pid/maps tells a consistent story.
2320 * By setting it to reflect the virtual start address of the
2321 * vma, merges and splits can happen in a seamless way, just
2322 * using the existing file pgoff checks and manipulations.
2323 * Similarly in do_mmap_pgoff and in do_brk.
2325 if (!vma
->vm_file
) {
2326 BUG_ON(vma
->anon_vma
);
2327 vma
->vm_pgoff
= vma
->vm_start
>> PAGE_SHIFT
;
2329 __vma
= find_vma_prepare(mm
,vma
->vm_start
,&prev
,&rb_link
,&rb_parent
);
2330 if (__vma
&& __vma
->vm_start
< vma
->vm_end
)
2332 if ((vma
->vm_flags
& VM_ACCOUNT
) &&
2333 security_vm_enough_memory_mm(mm
, vma_pages(vma
)))
2335 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2340 * Copy the vma structure to a new location in the same mm,
2341 * prior to moving page table entries, to effect an mremap move.
2343 struct vm_area_struct
*copy_vma(struct vm_area_struct
**vmap
,
2344 unsigned long addr
, unsigned long len
, pgoff_t pgoff
)
2346 struct vm_area_struct
*vma
= *vmap
;
2347 unsigned long vma_start
= vma
->vm_start
;
2348 struct mm_struct
*mm
= vma
->vm_mm
;
2349 struct vm_area_struct
*new_vma
, *prev
;
2350 struct rb_node
**rb_link
, *rb_parent
;
2351 struct mempolicy
*pol
;
2354 * If anonymous vma has not yet been faulted, update new pgoff
2355 * to match new location, to increase its chance of merging.
2357 if (!vma
->vm_file
&& !vma
->anon_vma
)
2358 pgoff
= addr
>> PAGE_SHIFT
;
2360 find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
2361 new_vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vma
->vm_flags
,
2362 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
2365 * Source vma may have been merged into new_vma
2367 if (vma_start
>= new_vma
->vm_start
&&
2368 vma_start
< new_vma
->vm_end
)
2371 new_vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2374 pol
= mpol_dup(vma_policy(vma
));
2377 INIT_LIST_HEAD(&new_vma
->anon_vma_chain
);
2378 if (anon_vma_clone(new_vma
, vma
))
2379 goto out_free_mempol
;
2380 vma_set_policy(new_vma
, pol
);
2381 new_vma
->vm_start
= addr
;
2382 new_vma
->vm_end
= addr
+ len
;
2383 new_vma
->vm_pgoff
= pgoff
;
2384 if (new_vma
->vm_file
) {
2385 get_file(new_vma
->vm_file
);
2386 if (vma
->vm_flags
& VM_EXECUTABLE
)
2387 added_exe_file_vma(mm
);
2389 if (new_vma
->vm_ops
&& new_vma
->vm_ops
->open
)
2390 new_vma
->vm_ops
->open(new_vma
);
2391 vma_link(mm
, new_vma
, prev
, rb_link
, rb_parent
);
2399 kmem_cache_free(vm_area_cachep
, new_vma
);
2404 * Return true if the calling process may expand its vm space by the passed
2407 int may_expand_vm(struct mm_struct
*mm
, unsigned long npages
)
2409 unsigned long cur
= mm
->total_vm
; /* pages */
2412 lim
= rlimit(RLIMIT_AS
) >> PAGE_SHIFT
;
2414 if (cur
+ npages
> lim
)
2420 static int special_mapping_fault(struct vm_area_struct
*vma
,
2421 struct vm_fault
*vmf
)
2424 struct page
**pages
;
2427 * special mappings have no vm_file, and in that case, the mm
2428 * uses vm_pgoff internally. So we have to subtract it from here.
2429 * We are allowed to do this because we are the mm; do not copy
2430 * this code into drivers!
2432 pgoff
= vmf
->pgoff
- vma
->vm_pgoff
;
2434 for (pages
= vma
->vm_private_data
; pgoff
&& *pages
; ++pages
)
2438 struct page
*page
= *pages
;
2444 return VM_FAULT_SIGBUS
;
2448 * Having a close hook prevents vma merging regardless of flags.
2450 static void special_mapping_close(struct vm_area_struct
*vma
)
2454 static const struct vm_operations_struct special_mapping_vmops
= {
2455 .close
= special_mapping_close
,
2456 .fault
= special_mapping_fault
,
2460 * Called with mm->mmap_sem held for writing.
2461 * Insert a new vma covering the given region, with the given flags.
2462 * Its pages are supplied by the given array of struct page *.
2463 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2464 * The region past the last page supplied will always produce SIGBUS.
2465 * The array pointer and the pages it points to are assumed to stay alive
2466 * for as long as this mapping might exist.
2468 int install_special_mapping(struct mm_struct
*mm
,
2469 unsigned long addr
, unsigned long len
,
2470 unsigned long vm_flags
, struct page
**pages
)
2473 struct vm_area_struct
*vma
;
2475 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2476 if (unlikely(vma
== NULL
))
2479 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2481 vma
->vm_start
= addr
;
2482 vma
->vm_end
= addr
+ len
;
2484 vma
->vm_flags
= vm_flags
| mm
->def_flags
| VM_DONTEXPAND
;
2485 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
2487 vma
->vm_ops
= &special_mapping_vmops
;
2488 vma
->vm_private_data
= pages
;
2490 ret
= security_file_mmap(NULL
, 0, 0, 0, vma
->vm_start
, 1);
2494 ret
= insert_vm_struct(mm
, vma
);
2498 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2500 perf_event_mmap(vma
);
2505 kmem_cache_free(vm_area_cachep
, vma
);
2509 static DEFINE_MUTEX(mm_all_locks_mutex
);
2511 static void vm_lock_anon_vma(struct mm_struct
*mm
, struct anon_vma
*anon_vma
)
2513 if (!test_bit(0, (unsigned long *) &anon_vma
->root
->head
.next
)) {
2515 * The LSB of head.next can't change from under us
2516 * because we hold the mm_all_locks_mutex.
2518 spin_lock_nest_lock(&anon_vma
->root
->lock
, &mm
->mmap_sem
);
2520 * We can safely modify head.next after taking the
2521 * anon_vma->root->lock. If some other vma in this mm shares
2522 * the same anon_vma we won't take it again.
2524 * No need of atomic instructions here, head.next
2525 * can't change from under us thanks to the
2526 * anon_vma->root->lock.
2528 if (__test_and_set_bit(0, (unsigned long *)
2529 &anon_vma
->root
->head
.next
))
2534 static void vm_lock_mapping(struct mm_struct
*mm
, struct address_space
*mapping
)
2536 if (!test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
2538 * AS_MM_ALL_LOCKS can't change from under us because
2539 * we hold the mm_all_locks_mutex.
2541 * Operations on ->flags have to be atomic because
2542 * even if AS_MM_ALL_LOCKS is stable thanks to the
2543 * mm_all_locks_mutex, there may be other cpus
2544 * changing other bitflags in parallel to us.
2546 if (test_and_set_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
))
2548 spin_lock_nest_lock(&mapping
->i_mmap_lock
, &mm
->mmap_sem
);
2553 * This operation locks against the VM for all pte/vma/mm related
2554 * operations that could ever happen on a certain mm. This includes
2555 * vmtruncate, try_to_unmap, and all page faults.
2557 * The caller must take the mmap_sem in write mode before calling
2558 * mm_take_all_locks(). The caller isn't allowed to release the
2559 * mmap_sem until mm_drop_all_locks() returns.
2561 * mmap_sem in write mode is required in order to block all operations
2562 * that could modify pagetables and free pages without need of
2563 * altering the vma layout (for example populate_range() with
2564 * nonlinear vmas). It's also needed in write mode to avoid new
2565 * anon_vmas to be associated with existing vmas.
2567 * A single task can't take more than one mm_take_all_locks() in a row
2568 * or it would deadlock.
2570 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2571 * mapping->flags avoid to take the same lock twice, if more than one
2572 * vma in this mm is backed by the same anon_vma or address_space.
2574 * We can take all the locks in random order because the VM code
2575 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2576 * takes more than one of them in a row. Secondly we're protected
2577 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2579 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2580 * that may have to take thousand of locks.
2582 * mm_take_all_locks() can fail if it's interrupted by signals.
2584 int mm_take_all_locks(struct mm_struct
*mm
)
2586 struct vm_area_struct
*vma
;
2587 struct anon_vma_chain
*avc
;
2590 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
2592 mutex_lock(&mm_all_locks_mutex
);
2594 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2595 if (signal_pending(current
))
2597 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
2598 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
2601 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2602 if (signal_pending(current
))
2605 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
2606 vm_lock_anon_vma(mm
, avc
->anon_vma
);
2613 mm_drop_all_locks(mm
);
2618 static void vm_unlock_anon_vma(struct anon_vma
*anon_vma
)
2620 if (test_bit(0, (unsigned long *) &anon_vma
->root
->head
.next
)) {
2622 * The LSB of head.next can't change to 0 from under
2623 * us because we hold the mm_all_locks_mutex.
2625 * We must however clear the bitflag before unlocking
2626 * the vma so the users using the anon_vma->head will
2627 * never see our bitflag.
2629 * No need of atomic instructions here, head.next
2630 * can't change from under us until we release the
2631 * anon_vma->root->lock.
2633 if (!__test_and_clear_bit(0, (unsigned long *)
2634 &anon_vma
->root
->head
.next
))
2636 anon_vma_unlock(anon_vma
);
2640 static void vm_unlock_mapping(struct address_space
*mapping
)
2642 if (test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
2644 * AS_MM_ALL_LOCKS can't change to 0 from under us
2645 * because we hold the mm_all_locks_mutex.
2647 spin_unlock(&mapping
->i_mmap_lock
);
2648 if (!test_and_clear_bit(AS_MM_ALL_LOCKS
,
2655 * The mmap_sem cannot be released by the caller until
2656 * mm_drop_all_locks() returns.
2658 void mm_drop_all_locks(struct mm_struct
*mm
)
2660 struct vm_area_struct
*vma
;
2661 struct anon_vma_chain
*avc
;
2663 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
2664 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex
));
2666 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2668 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
2669 vm_unlock_anon_vma(avc
->anon_vma
);
2670 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
2671 vm_unlock_mapping(vma
->vm_file
->f_mapping
);
2674 mutex_unlock(&mm_all_locks_mutex
);
2678 * initialise the VMA slab
2680 void __init
mmap_init(void)
2684 ret
= percpu_counter_init(&vm_committed_as
, 0);