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/export.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>
33 #include <linux/uprobes.h>
35 #include <asm/uaccess.h>
36 #include <asm/cacheflush.h>
38 #include <asm/mmu_context.h>
42 #ifndef arch_mmap_check
43 #define arch_mmap_check(addr, len, flags) (0)
46 #ifndef arch_rebalance_pgtables
47 #define arch_rebalance_pgtables(addr, len) (addr)
50 static void unmap_region(struct mm_struct
*mm
,
51 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
52 unsigned long start
, unsigned long end
);
55 * WARNING: the debugging will use recursive algorithms so never enable this
56 * unless you know what you are doing.
60 /* description of effects of mapping type and prot in current implementation.
61 * this is due to the limited x86 page protection hardware. The expected
62 * behavior is in parens:
65 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
66 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
67 * w: (no) no w: (no) no w: (yes) yes w: (no) no
68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
70 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
71 * w: (no) no w: (no) no w: (copy) copy w: (no) no
72 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
75 pgprot_t protection_map
[16] = {
76 __P000
, __P001
, __P010
, __P011
, __P100
, __P101
, __P110
, __P111
,
77 __S000
, __S001
, __S010
, __S011
, __S100
, __S101
, __S110
, __S111
80 pgprot_t
vm_get_page_prot(unsigned long vm_flags
)
82 return __pgprot(pgprot_val(protection_map
[vm_flags
&
83 (VM_READ
|VM_WRITE
|VM_EXEC
|VM_SHARED
)]) |
84 pgprot_val(arch_vm_get_page_prot(vm_flags
)));
86 EXPORT_SYMBOL(vm_get_page_prot
);
88 int sysctl_overcommit_memory __read_mostly
= OVERCOMMIT_GUESS
; /* heuristic overcommit */
89 int sysctl_overcommit_ratio __read_mostly
= 50; /* default is 50% */
90 int sysctl_max_map_count __read_mostly
= DEFAULT_MAX_MAP_COUNT
;
92 * Make sure vm_committed_as in one cacheline and not cacheline shared with
93 * other variables. It can be updated by several CPUs frequently.
95 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp
;
98 * Check that a process has enough memory to allocate a new virtual
99 * mapping. 0 means there is enough memory for the allocation to
100 * succeed and -ENOMEM implies there is not.
102 * We currently support three overcommit policies, which are set via the
103 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
105 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
106 * Additional code 2002 Jul 20 by Robert Love.
108 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
110 * Note this is a helper function intended to be used by LSMs which
111 * wish to use this logic.
113 int __vm_enough_memory(struct mm_struct
*mm
, long pages
, int cap_sys_admin
)
115 unsigned long free
, allowed
;
117 vm_acct_memory(pages
);
120 * Sometimes we want to use more memory than we have
122 if (sysctl_overcommit_memory
== OVERCOMMIT_ALWAYS
)
125 if (sysctl_overcommit_memory
== OVERCOMMIT_GUESS
) {
126 free
= global_page_state(NR_FREE_PAGES
);
127 free
+= global_page_state(NR_FILE_PAGES
);
130 * shmem pages shouldn't be counted as free in this
131 * case, they can't be purged, only swapped out, and
132 * that won't affect the overall amount of available
133 * memory in the system.
135 free
-= global_page_state(NR_SHMEM
);
137 free
+= nr_swap_pages
;
140 * Any slabs which are created with the
141 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
142 * which are reclaimable, under pressure. The dentry
143 * cache and most inode caches should fall into this
145 free
+= global_page_state(NR_SLAB_RECLAIMABLE
);
148 * Leave reserved pages. The pages are not for anonymous pages.
150 if (free
<= totalreserve_pages
)
153 free
-= totalreserve_pages
;
156 * Leave the last 3% for root
167 allowed
= (totalram_pages
- hugetlb_total_pages())
168 * sysctl_overcommit_ratio
/ 100;
170 * Leave the last 3% for root
173 allowed
-= allowed
/ 32;
174 allowed
+= total_swap_pages
;
176 /* Don't let a single process grow too big:
177 leave 3% of the size of this process for other processes */
179 allowed
-= mm
->total_vm
/ 32;
181 if (percpu_counter_read_positive(&vm_committed_as
) < allowed
)
184 vm_unacct_memory(pages
);
190 * Requires inode->i_mapping->i_mmap_mutex
192 static void __remove_shared_vm_struct(struct vm_area_struct
*vma
,
193 struct file
*file
, struct address_space
*mapping
)
195 if (vma
->vm_flags
& VM_DENYWRITE
)
196 atomic_inc(&file
->f_path
.dentry
->d_inode
->i_writecount
);
197 if (vma
->vm_flags
& VM_SHARED
)
198 mapping
->i_mmap_writable
--;
200 flush_dcache_mmap_lock(mapping
);
201 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
202 list_del_init(&vma
->shared
.vm_set
.list
);
204 vma_prio_tree_remove(vma
, &mapping
->i_mmap
);
205 flush_dcache_mmap_unlock(mapping
);
209 * Unlink a file-based vm structure from its prio_tree, to hide
210 * vma from rmap and vmtruncate before freeing its page tables.
212 void unlink_file_vma(struct vm_area_struct
*vma
)
214 struct file
*file
= vma
->vm_file
;
217 struct address_space
*mapping
= file
->f_mapping
;
218 mutex_lock(&mapping
->i_mmap_mutex
);
219 __remove_shared_vm_struct(vma
, file
, mapping
);
220 mutex_unlock(&mapping
->i_mmap_mutex
);
226 * Close a vm structure and free it, returning the next.
228 static struct vm_area_struct
*remove_vma(struct vm_area_struct
*vma
)
230 struct vm_area_struct
*next
= vma
->vm_next
;
233 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
234 vma
->vm_ops
->close(vma
);
237 if (vma
->vm_flags
& VM_EXECUTABLE
)
238 removed_exe_file_vma(vma
->vm_mm
);
240 mpol_put(vma_policy(vma
));
241 kmem_cache_free(vm_area_cachep
, vma
);
245 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
247 unsigned long rlim
, retval
;
248 unsigned long newbrk
, oldbrk
;
249 struct mm_struct
*mm
= current
->mm
;
250 unsigned long min_brk
;
252 down_write(&mm
->mmap_sem
);
254 #ifdef CONFIG_COMPAT_BRK
256 * CONFIG_COMPAT_BRK can still be overridden by setting
257 * randomize_va_space to 2, which will still cause mm->start_brk
258 * to be arbitrarily shifted
260 if (current
->brk_randomized
)
261 min_brk
= mm
->start_brk
;
263 min_brk
= mm
->end_data
;
265 min_brk
= mm
->start_brk
;
271 * Check against rlimit here. If this check is done later after the test
272 * of oldbrk with newbrk then it can escape the test and let the data
273 * segment grow beyond its set limit the in case where the limit is
274 * not page aligned -Ram Gupta
276 rlim
= rlimit(RLIMIT_DATA
);
277 if (rlim
< RLIM_INFINITY
&& (brk
- mm
->start_brk
) +
278 (mm
->end_data
- mm
->start_data
) > rlim
)
281 newbrk
= PAGE_ALIGN(brk
);
282 oldbrk
= PAGE_ALIGN(mm
->brk
);
283 if (oldbrk
== newbrk
)
286 /* Always allow shrinking brk. */
287 if (brk
<= mm
->brk
) {
288 if (!do_munmap(mm
, newbrk
, oldbrk
-newbrk
))
293 /* Check against existing mmap mappings. */
294 if (find_vma_intersection(mm
, oldbrk
, newbrk
+PAGE_SIZE
))
297 /* Ok, looks good - let it rip. */
298 if (do_brk(oldbrk
, newbrk
-oldbrk
) != oldbrk
)
304 up_write(&mm
->mmap_sem
);
309 static int browse_rb(struct rb_root
*root
)
312 struct rb_node
*nd
, *pn
= NULL
;
313 unsigned long prev
= 0, pend
= 0;
315 for (nd
= rb_first(root
); nd
; nd
= rb_next(nd
)) {
316 struct vm_area_struct
*vma
;
317 vma
= rb_entry(nd
, struct vm_area_struct
, vm_rb
);
318 if (vma
->vm_start
< prev
)
319 printk("vm_start %lx prev %lx\n", vma
->vm_start
, prev
), i
= -1;
320 if (vma
->vm_start
< pend
)
321 printk("vm_start %lx pend %lx\n", vma
->vm_start
, pend
);
322 if (vma
->vm_start
> vma
->vm_end
)
323 printk("vm_end %lx < vm_start %lx\n", vma
->vm_end
, vma
->vm_start
);
326 prev
= vma
->vm_start
;
330 for (nd
= pn
; nd
; nd
= rb_prev(nd
)) {
334 printk("backwards %d, forwards %d\n", j
, i
), i
= 0;
338 void validate_mm(struct mm_struct
*mm
)
342 struct vm_area_struct
*tmp
= mm
->mmap
;
347 if (i
!= mm
->map_count
)
348 printk("map_count %d vm_next %d\n", mm
->map_count
, i
), bug
= 1;
349 i
= browse_rb(&mm
->mm_rb
);
350 if (i
!= mm
->map_count
)
351 printk("map_count %d rb %d\n", mm
->map_count
, i
), bug
= 1;
355 #define validate_mm(mm) do { } while (0)
358 static struct vm_area_struct
*
359 find_vma_prepare(struct mm_struct
*mm
, unsigned long addr
,
360 struct vm_area_struct
**pprev
, struct rb_node
***rb_link
,
361 struct rb_node
** rb_parent
)
363 struct vm_area_struct
* vma
;
364 struct rb_node
** __rb_link
, * __rb_parent
, * rb_prev
;
366 __rb_link
= &mm
->mm_rb
.rb_node
;
367 rb_prev
= __rb_parent
= NULL
;
371 struct vm_area_struct
*vma_tmp
;
373 __rb_parent
= *__rb_link
;
374 vma_tmp
= rb_entry(__rb_parent
, struct vm_area_struct
, vm_rb
);
376 if (vma_tmp
->vm_end
> addr
) {
378 if (vma_tmp
->vm_start
<= addr
)
380 __rb_link
= &__rb_parent
->rb_left
;
382 rb_prev
= __rb_parent
;
383 __rb_link
= &__rb_parent
->rb_right
;
389 *pprev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
390 *rb_link
= __rb_link
;
391 *rb_parent
= __rb_parent
;
395 void __vma_link_rb(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
396 struct rb_node
**rb_link
, struct rb_node
*rb_parent
)
398 rb_link_node(&vma
->vm_rb
, rb_parent
, rb_link
);
399 rb_insert_color(&vma
->vm_rb
, &mm
->mm_rb
);
402 static void __vma_link_file(struct vm_area_struct
*vma
)
408 struct address_space
*mapping
= file
->f_mapping
;
410 if (vma
->vm_flags
& VM_DENYWRITE
)
411 atomic_dec(&file
->f_path
.dentry
->d_inode
->i_writecount
);
412 if (vma
->vm_flags
& VM_SHARED
)
413 mapping
->i_mmap_writable
++;
415 flush_dcache_mmap_lock(mapping
);
416 if (unlikely(vma
->vm_flags
& VM_NONLINEAR
))
417 vma_nonlinear_insert(vma
, &mapping
->i_mmap_nonlinear
);
419 vma_prio_tree_insert(vma
, &mapping
->i_mmap
);
420 flush_dcache_mmap_unlock(mapping
);
425 __vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
426 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
427 struct rb_node
*rb_parent
)
429 __vma_link_list(mm
, vma
, prev
, rb_parent
);
430 __vma_link_rb(mm
, vma
, rb_link
, rb_parent
);
433 static void vma_link(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
434 struct vm_area_struct
*prev
, struct rb_node
**rb_link
,
435 struct rb_node
*rb_parent
)
437 struct address_space
*mapping
= NULL
;
440 mapping
= vma
->vm_file
->f_mapping
;
443 mutex_lock(&mapping
->i_mmap_mutex
);
445 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
446 __vma_link_file(vma
);
449 mutex_unlock(&mapping
->i_mmap_mutex
);
456 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
457 * mm's list and rbtree. It has already been inserted into the prio_tree.
459 static void __insert_vm_struct(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
461 struct vm_area_struct
*__vma
, *prev
;
462 struct rb_node
**rb_link
, *rb_parent
;
464 __vma
= find_vma_prepare(mm
, vma
->vm_start
,&prev
, &rb_link
, &rb_parent
);
465 BUG_ON(__vma
&& __vma
->vm_start
< vma
->vm_end
);
466 __vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
471 __vma_unlink(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
472 struct vm_area_struct
*prev
)
474 struct vm_area_struct
*next
= vma
->vm_next
;
476 prev
->vm_next
= next
;
478 next
->vm_prev
= prev
;
479 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
480 if (mm
->mmap_cache
== vma
)
481 mm
->mmap_cache
= prev
;
485 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
486 * is already present in an i_mmap tree without adjusting the tree.
487 * The following helper function should be used when such adjustments
488 * are necessary. The "insert" vma (if any) is to be inserted
489 * before we drop the necessary locks.
491 int vma_adjust(struct vm_area_struct
*vma
, unsigned long start
,
492 unsigned long end
, pgoff_t pgoff
, struct vm_area_struct
*insert
)
494 struct mm_struct
*mm
= vma
->vm_mm
;
495 struct vm_area_struct
*next
= vma
->vm_next
;
496 struct vm_area_struct
*importer
= NULL
;
497 struct address_space
*mapping
= NULL
;
498 struct prio_tree_root
*root
= NULL
;
499 struct anon_vma
*anon_vma
= NULL
;
500 struct file
*file
= vma
->vm_file
;
501 long adjust_next
= 0;
504 if (next
&& !insert
) {
505 struct vm_area_struct
*exporter
= NULL
;
507 if (end
>= next
->vm_end
) {
509 * vma expands, overlapping all the next, and
510 * perhaps the one after too (mprotect case 6).
512 again
: remove_next
= 1 + (end
> next
->vm_end
);
516 } else if (end
> next
->vm_start
) {
518 * vma expands, overlapping part of the next:
519 * mprotect case 5 shifting the boundary up.
521 adjust_next
= (end
- next
->vm_start
) >> PAGE_SHIFT
;
524 } else if (end
< vma
->vm_end
) {
526 * vma shrinks, and !insert tells it's not
527 * split_vma inserting another: so it must be
528 * mprotect case 4 shifting the boundary down.
530 adjust_next
= - ((vma
->vm_end
- end
) >> PAGE_SHIFT
);
536 * Easily overlooked: when mprotect shifts the boundary,
537 * make sure the expanding vma has anon_vma set if the
538 * shrinking vma had, to cover any anon pages imported.
540 if (exporter
&& exporter
->anon_vma
&& !importer
->anon_vma
) {
541 if (anon_vma_clone(importer
, exporter
))
543 importer
->anon_vma
= exporter
->anon_vma
;
548 mapping
= file
->f_mapping
;
549 if (!(vma
->vm_flags
& VM_NONLINEAR
)) {
550 root
= &mapping
->i_mmap
;
557 mutex_lock(&mapping
->i_mmap_mutex
);
560 * Put into prio_tree now, so instantiated pages
561 * are visible to arm/parisc __flush_dcache_page
562 * throughout; but we cannot insert into address
563 * space until vma start or end is updated.
565 __vma_link_file(insert
);
569 vma_adjust_trans_huge(vma
, start
, end
, adjust_next
);
572 * When changing only vma->vm_end, we don't really need anon_vma
573 * lock. This is a fairly rare case by itself, but the anon_vma
574 * lock may be shared between many sibling processes. Skipping
575 * the lock for brk adjustments makes a difference sometimes.
577 if (vma
->anon_vma
&& (importer
|| start
!= vma
->vm_start
)) {
578 anon_vma
= vma
->anon_vma
;
579 anon_vma_lock(anon_vma
);
583 flush_dcache_mmap_lock(mapping
);
584 vma_prio_tree_remove(vma
, root
);
586 vma_prio_tree_remove(next
, root
);
589 vma
->vm_start
= start
;
591 vma
->vm_pgoff
= pgoff
;
593 next
->vm_start
+= adjust_next
<< PAGE_SHIFT
;
594 next
->vm_pgoff
+= adjust_next
;
599 vma_prio_tree_insert(next
, root
);
600 vma_prio_tree_insert(vma
, root
);
601 flush_dcache_mmap_unlock(mapping
);
606 * vma_merge has merged next into vma, and needs
607 * us to remove next before dropping the locks.
609 __vma_unlink(mm
, next
, vma
);
611 __remove_shared_vm_struct(next
, file
, mapping
);
614 * split_vma has split insert from vma, and needs
615 * us to insert it before dropping the locks
616 * (it may either follow vma or precede it).
618 __insert_vm_struct(mm
, insert
);
622 anon_vma_unlock(anon_vma
);
624 mutex_unlock(&mapping
->i_mmap_mutex
);
637 if (next
->vm_flags
& VM_EXECUTABLE
)
638 removed_exe_file_vma(mm
);
641 anon_vma_merge(vma
, next
);
643 mpol_put(vma_policy(next
));
644 kmem_cache_free(vm_area_cachep
, next
);
646 * In mprotect's case 6 (see comments on vma_merge),
647 * we must remove another next too. It would clutter
648 * up the code too much to do both in one go.
650 if (remove_next
== 2) {
664 * If the vma has a ->close operation then the driver probably needs to release
665 * per-vma resources, so we don't attempt to merge those.
667 static inline int is_mergeable_vma(struct vm_area_struct
*vma
,
668 struct file
*file
, unsigned long vm_flags
)
670 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
671 if ((vma
->vm_flags
^ vm_flags
) & ~VM_CAN_NONLINEAR
)
673 if (vma
->vm_file
!= file
)
675 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
680 static inline int is_mergeable_anon_vma(struct anon_vma
*anon_vma1
,
681 struct anon_vma
*anon_vma2
,
682 struct vm_area_struct
*vma
)
685 * The list_is_singular() test is to avoid merging VMA cloned from
686 * parents. This can improve scalability caused by anon_vma lock.
688 if ((!anon_vma1
|| !anon_vma2
) && (!vma
||
689 list_is_singular(&vma
->anon_vma_chain
)))
691 return anon_vma1
== anon_vma2
;
695 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
696 * in front of (at a lower virtual address and file offset than) the vma.
698 * We cannot merge two vmas if they have differently assigned (non-NULL)
699 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
701 * We don't check here for the merged mmap wrapping around the end of pagecache
702 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
703 * wrap, nor mmaps which cover the final page at index -1UL.
706 can_vma_merge_before(struct vm_area_struct
*vma
, unsigned long vm_flags
,
707 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
709 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
710 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
711 if (vma
->vm_pgoff
== vm_pgoff
)
718 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
719 * beyond (at a higher virtual address and file offset than) the vma.
721 * We cannot merge two vmas if they have differently assigned (non-NULL)
722 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
725 can_vma_merge_after(struct vm_area_struct
*vma
, unsigned long vm_flags
,
726 struct anon_vma
*anon_vma
, struct file
*file
, pgoff_t vm_pgoff
)
728 if (is_mergeable_vma(vma
, file
, vm_flags
) &&
729 is_mergeable_anon_vma(anon_vma
, vma
->anon_vma
, vma
)) {
731 vm_pglen
= (vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
;
732 if (vma
->vm_pgoff
+ vm_pglen
== vm_pgoff
)
739 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
740 * whether that can be merged with its predecessor or its successor.
741 * Or both (it neatly fills a hole).
743 * In most cases - when called for mmap, brk or mremap - [addr,end) is
744 * certain not to be mapped by the time vma_merge is called; but when
745 * called for mprotect, it is certain to be already mapped (either at
746 * an offset within prev, or at the start of next), and the flags of
747 * this area are about to be changed to vm_flags - and the no-change
748 * case has already been eliminated.
750 * The following mprotect cases have to be considered, where AAAA is
751 * the area passed down from mprotect_fixup, never extending beyond one
752 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
754 * AAAA AAAA AAAA AAAA
755 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
756 * cannot merge might become might become might become
757 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
758 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
759 * mremap move: PPPPNNNNNNNN 8
761 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
762 * might become case 1 below case 2 below case 3 below
764 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
765 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
767 struct vm_area_struct
*vma_merge(struct mm_struct
*mm
,
768 struct vm_area_struct
*prev
, unsigned long addr
,
769 unsigned long end
, unsigned long vm_flags
,
770 struct anon_vma
*anon_vma
, struct file
*file
,
771 pgoff_t pgoff
, struct mempolicy
*policy
)
773 pgoff_t pglen
= (end
- addr
) >> PAGE_SHIFT
;
774 struct vm_area_struct
*area
, *next
;
778 * We later require that vma->vm_flags == vm_flags,
779 * so this tests vma->vm_flags & VM_SPECIAL, too.
781 if (vm_flags
& VM_SPECIAL
)
785 next
= prev
->vm_next
;
789 if (next
&& next
->vm_end
== end
) /* cases 6, 7, 8 */
790 next
= next
->vm_next
;
793 * Can it merge with the predecessor?
795 if (prev
&& prev
->vm_end
== addr
&&
796 mpol_equal(vma_policy(prev
), policy
) &&
797 can_vma_merge_after(prev
, vm_flags
,
798 anon_vma
, file
, pgoff
)) {
800 * OK, it can. Can we now merge in the successor as well?
802 if (next
&& end
== next
->vm_start
&&
803 mpol_equal(policy
, vma_policy(next
)) &&
804 can_vma_merge_before(next
, vm_flags
,
805 anon_vma
, file
, pgoff
+pglen
) &&
806 is_mergeable_anon_vma(prev
->anon_vma
,
807 next
->anon_vma
, NULL
)) {
809 err
= vma_adjust(prev
, prev
->vm_start
,
810 next
->vm_end
, prev
->vm_pgoff
, NULL
);
811 } else /* cases 2, 5, 7 */
812 err
= vma_adjust(prev
, prev
->vm_start
,
813 end
, prev
->vm_pgoff
, NULL
);
816 khugepaged_enter_vma_merge(prev
);
821 * Can this new request be merged in front of next?
823 if (next
&& end
== next
->vm_start
&&
824 mpol_equal(policy
, vma_policy(next
)) &&
825 can_vma_merge_before(next
, vm_flags
,
826 anon_vma
, file
, pgoff
+pglen
)) {
827 if (prev
&& addr
< prev
->vm_end
) /* case 4 */
828 err
= vma_adjust(prev
, prev
->vm_start
,
829 addr
, prev
->vm_pgoff
, NULL
);
830 else /* cases 3, 8 */
831 err
= vma_adjust(area
, addr
, next
->vm_end
,
832 next
->vm_pgoff
- pglen
, NULL
);
835 khugepaged_enter_vma_merge(area
);
843 * Rough compatbility check to quickly see if it's even worth looking
844 * at sharing an anon_vma.
846 * They need to have the same vm_file, and the flags can only differ
847 * in things that mprotect may change.
849 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
850 * we can merge the two vma's. For example, we refuse to merge a vma if
851 * there is a vm_ops->close() function, because that indicates that the
852 * driver is doing some kind of reference counting. But that doesn't
853 * really matter for the anon_vma sharing case.
855 static int anon_vma_compatible(struct vm_area_struct
*a
, struct vm_area_struct
*b
)
857 return a
->vm_end
== b
->vm_start
&&
858 mpol_equal(vma_policy(a
), vma_policy(b
)) &&
859 a
->vm_file
== b
->vm_file
&&
860 !((a
->vm_flags
^ b
->vm_flags
) & ~(VM_READ
|VM_WRITE
|VM_EXEC
)) &&
861 b
->vm_pgoff
== a
->vm_pgoff
+ ((b
->vm_start
- a
->vm_start
) >> PAGE_SHIFT
);
865 * Do some basic sanity checking to see if we can re-use the anon_vma
866 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
867 * the same as 'old', the other will be the new one that is trying
868 * to share the anon_vma.
870 * NOTE! This runs with mm_sem held for reading, so it is possible that
871 * the anon_vma of 'old' is concurrently in the process of being set up
872 * by another page fault trying to merge _that_. But that's ok: if it
873 * is being set up, that automatically means that it will be a singleton
874 * acceptable for merging, so we can do all of this optimistically. But
875 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
877 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
878 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
879 * is to return an anon_vma that is "complex" due to having gone through
882 * We also make sure that the two vma's are compatible (adjacent,
883 * and with the same memory policies). That's all stable, even with just
884 * a read lock on the mm_sem.
886 static struct anon_vma
*reusable_anon_vma(struct vm_area_struct
*old
, struct vm_area_struct
*a
, struct vm_area_struct
*b
)
888 if (anon_vma_compatible(a
, b
)) {
889 struct anon_vma
*anon_vma
= ACCESS_ONCE(old
->anon_vma
);
891 if (anon_vma
&& list_is_singular(&old
->anon_vma_chain
))
898 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
899 * neighbouring vmas for a suitable anon_vma, before it goes off
900 * to allocate a new anon_vma. It checks because a repetitive
901 * sequence of mprotects and faults may otherwise lead to distinct
902 * anon_vmas being allocated, preventing vma merge in subsequent
905 struct anon_vma
*find_mergeable_anon_vma(struct vm_area_struct
*vma
)
907 struct anon_vma
*anon_vma
;
908 struct vm_area_struct
*near
;
914 anon_vma
= reusable_anon_vma(near
, vma
, near
);
922 anon_vma
= reusable_anon_vma(near
, near
, vma
);
927 * There's no absolute need to look only at touching neighbours:
928 * we could search further afield for "compatible" anon_vmas.
929 * But it would probably just be a waste of time searching,
930 * or lead to too many vmas hanging off the same anon_vma.
931 * We're trying to allow mprotect remerging later on,
932 * not trying to minimize memory used for anon_vmas.
937 #ifdef CONFIG_PROC_FS
938 void vm_stat_account(struct mm_struct
*mm
, unsigned long flags
,
939 struct file
*file
, long pages
)
941 const unsigned long stack_flags
942 = VM_STACK_FLAGS
& (VM_GROWSUP
|VM_GROWSDOWN
);
945 mm
->shared_vm
+= pages
;
946 if ((flags
& (VM_EXEC
|VM_WRITE
)) == VM_EXEC
)
947 mm
->exec_vm
+= pages
;
948 } else if (flags
& stack_flags
)
949 mm
->stack_vm
+= pages
;
950 if (flags
& (VM_RESERVED
|VM_IO
))
951 mm
->reserved_vm
+= pages
;
953 #endif /* CONFIG_PROC_FS */
956 * If a hint addr is less than mmap_min_addr change hint to be as
957 * low as possible but still greater than mmap_min_addr
959 static inline unsigned long round_hint_to_min(unsigned long hint
)
962 if (((void *)hint
!= NULL
) &&
963 (hint
< mmap_min_addr
))
964 return PAGE_ALIGN(mmap_min_addr
);
969 * The caller must hold down_write(¤t->mm->mmap_sem).
972 unsigned long do_mmap_pgoff(struct file
*file
, unsigned long addr
,
973 unsigned long len
, unsigned long prot
,
974 unsigned long flags
, unsigned long pgoff
)
976 struct mm_struct
* mm
= current
->mm
;
980 unsigned long reqprot
= prot
;
983 * Does the application expect PROT_READ to imply PROT_EXEC?
985 * (the exception is when the underlying filesystem is noexec
986 * mounted, in which case we dont add PROT_EXEC.)
988 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
989 if (!(file
&& (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
)))
995 if (!(flags
& MAP_FIXED
))
996 addr
= round_hint_to_min(addr
);
998 /* Careful about overflows.. */
999 len
= PAGE_ALIGN(len
);
1003 /* offset overflow? */
1004 if ((pgoff
+ (len
>> PAGE_SHIFT
)) < pgoff
)
1007 /* Too many mappings? */
1008 if (mm
->map_count
> sysctl_max_map_count
)
1011 /* Obtain the address to map to. we verify (or select) it and ensure
1012 * that it represents a valid section of the address space.
1014 addr
= get_unmapped_area(file
, addr
, len
, pgoff
, flags
);
1015 if (addr
& ~PAGE_MASK
)
1018 /* Do simple checking here so the lower-level routines won't have
1019 * to. we assume access permissions have been handled by the open
1020 * of the memory object, so we don't do any here.
1022 vm_flags
= calc_vm_prot_bits(prot
) | calc_vm_flag_bits(flags
) |
1023 mm
->def_flags
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1025 if (flags
& MAP_LOCKED
)
1026 if (!can_do_mlock())
1029 /* mlock MCL_FUTURE? */
1030 if (vm_flags
& VM_LOCKED
) {
1031 unsigned long locked
, lock_limit
;
1032 locked
= len
>> PAGE_SHIFT
;
1033 locked
+= mm
->locked_vm
;
1034 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
1035 lock_limit
>>= PAGE_SHIFT
;
1036 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
1040 inode
= file
? file
->f_path
.dentry
->d_inode
: NULL
;
1043 switch (flags
& MAP_TYPE
) {
1045 if ((prot
&PROT_WRITE
) && !(file
->f_mode
&FMODE_WRITE
))
1049 * Make sure we don't allow writing to an append-only
1052 if (IS_APPEND(inode
) && (file
->f_mode
& FMODE_WRITE
))
1056 * Make sure there are no mandatory locks on the file.
1058 if (locks_verify_locked(inode
))
1061 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1062 if (!(file
->f_mode
& FMODE_WRITE
))
1063 vm_flags
&= ~(VM_MAYWRITE
| VM_SHARED
);
1067 if (!(file
->f_mode
& FMODE_READ
))
1069 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
) {
1070 if (vm_flags
& VM_EXEC
)
1072 vm_flags
&= ~VM_MAYEXEC
;
1075 if (!file
->f_op
|| !file
->f_op
->mmap
)
1083 switch (flags
& MAP_TYPE
) {
1089 vm_flags
|= VM_SHARED
| VM_MAYSHARE
;
1093 * Set pgoff according to addr for anon_vma.
1095 pgoff
= addr
>> PAGE_SHIFT
;
1102 error
= security_file_mmap(file
, reqprot
, prot
, flags
, addr
, 0);
1106 return mmap_region(file
, addr
, len
, flags
, vm_flags
, pgoff
);
1108 EXPORT_SYMBOL(do_mmap_pgoff
);
1110 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1111 unsigned long, prot
, unsigned long, flags
,
1112 unsigned long, fd
, unsigned long, pgoff
)
1114 struct file
*file
= NULL
;
1115 unsigned long retval
= -EBADF
;
1117 if (!(flags
& MAP_ANONYMOUS
)) {
1118 audit_mmap_fd(fd
, flags
);
1119 if (unlikely(flags
& MAP_HUGETLB
))
1124 } else if (flags
& MAP_HUGETLB
) {
1125 struct user_struct
*user
= NULL
;
1127 * VM_NORESERVE is used because the reservations will be
1128 * taken when vm_ops->mmap() is called
1129 * A dummy user value is used because we are not locking
1130 * memory so no accounting is necessary
1132 file
= hugetlb_file_setup(HUGETLB_ANON_FILE
, addr
, len
,
1133 VM_NORESERVE
, &user
,
1134 HUGETLB_ANONHUGE_INODE
);
1136 return PTR_ERR(file
);
1139 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1141 down_write(¤t
->mm
->mmap_sem
);
1142 retval
= do_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1143 up_write(¤t
->mm
->mmap_sem
);
1151 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1152 struct mmap_arg_struct
{
1156 unsigned long flags
;
1158 unsigned long offset
;
1161 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1163 struct mmap_arg_struct a
;
1165 if (copy_from_user(&a
, arg
, sizeof(a
)))
1167 if (a
.offset
& ~PAGE_MASK
)
1170 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1171 a
.offset
>> PAGE_SHIFT
);
1173 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1176 * Some shared mappigns will want the pages marked read-only
1177 * to track write events. If so, we'll downgrade vm_page_prot
1178 * to the private version (using protection_map[] without the
1181 int vma_wants_writenotify(struct vm_area_struct
*vma
)
1183 vm_flags_t vm_flags
= vma
->vm_flags
;
1185 /* If it was private or non-writable, the write bit is already clear */
1186 if ((vm_flags
& (VM_WRITE
|VM_SHARED
)) != ((VM_WRITE
|VM_SHARED
)))
1189 /* The backer wishes to know when pages are first written to? */
1190 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
)
1193 /* The open routine did something to the protections already? */
1194 if (pgprot_val(vma
->vm_page_prot
) !=
1195 pgprot_val(vm_get_page_prot(vm_flags
)))
1198 /* Specialty mapping? */
1199 if (vm_flags
& (VM_PFNMAP
|VM_INSERTPAGE
))
1202 /* Can the mapping track the dirty pages? */
1203 return vma
->vm_file
&& vma
->vm_file
->f_mapping
&&
1204 mapping_cap_account_dirty(vma
->vm_file
->f_mapping
);
1208 * We account for memory if it's a private writeable mapping,
1209 * not hugepages and VM_NORESERVE wasn't set.
1211 static inline int accountable_mapping(struct file
*file
, vm_flags_t vm_flags
)
1214 * hugetlb has its own accounting separate from the core VM
1215 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1217 if (file
&& is_file_hugepages(file
))
1220 return (vm_flags
& (VM_NORESERVE
| VM_SHARED
| VM_WRITE
)) == VM_WRITE
;
1223 unsigned long mmap_region(struct file
*file
, unsigned long addr
,
1224 unsigned long len
, unsigned long flags
,
1225 vm_flags_t vm_flags
, unsigned long pgoff
)
1227 struct mm_struct
*mm
= current
->mm
;
1228 struct vm_area_struct
*vma
, *prev
;
1229 int correct_wcount
= 0;
1231 struct rb_node
**rb_link
, *rb_parent
;
1232 unsigned long charged
= 0;
1233 struct inode
*inode
= file
? file
->f_path
.dentry
->d_inode
: NULL
;
1235 /* Clear old maps */
1238 vma
= find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
1239 if (vma
&& vma
->vm_start
< addr
+ len
) {
1240 if (do_munmap(mm
, addr
, len
))
1245 /* Check against address space limit. */
1246 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
))
1250 * Set 'VM_NORESERVE' if we should not account for the
1251 * memory use of this mapping.
1253 if ((flags
& MAP_NORESERVE
)) {
1254 /* We honor MAP_NORESERVE if allowed to overcommit */
1255 if (sysctl_overcommit_memory
!= OVERCOMMIT_NEVER
)
1256 vm_flags
|= VM_NORESERVE
;
1258 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1259 if (file
&& is_file_hugepages(file
))
1260 vm_flags
|= VM_NORESERVE
;
1264 * Private writable mapping: check memory availability
1266 if (accountable_mapping(file
, vm_flags
)) {
1267 charged
= len
>> PAGE_SHIFT
;
1268 if (security_vm_enough_memory_mm(mm
, charged
))
1270 vm_flags
|= VM_ACCOUNT
;
1274 * Can we just expand an old mapping?
1276 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vm_flags
, NULL
, file
, pgoff
, NULL
);
1281 * Determine the object being mapped and call the appropriate
1282 * specific mapper. the address has already been validated, but
1283 * not unmapped, but the maps are removed from the list.
1285 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1292 vma
->vm_start
= addr
;
1293 vma
->vm_end
= addr
+ len
;
1294 vma
->vm_flags
= vm_flags
;
1295 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
);
1296 vma
->vm_pgoff
= pgoff
;
1297 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1299 error
= -EINVAL
; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */
1302 if (vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
))
1304 if (vm_flags
& VM_DENYWRITE
) {
1305 error
= deny_write_access(file
);
1310 vma
->vm_file
= file
;
1312 error
= file
->f_op
->mmap(file
, vma
);
1314 goto unmap_and_free_vma
;
1315 if (vm_flags
& VM_EXECUTABLE
)
1316 added_exe_file_vma(mm
);
1318 /* Can addr have changed??
1320 * Answer: Yes, several device drivers can do it in their
1321 * f_op->mmap method. -DaveM
1323 addr
= vma
->vm_start
;
1324 pgoff
= vma
->vm_pgoff
;
1325 vm_flags
= vma
->vm_flags
;
1326 } else if (vm_flags
& VM_SHARED
) {
1327 if (unlikely(vm_flags
& (VM_GROWSDOWN
|VM_GROWSUP
)))
1329 error
= shmem_zero_setup(vma
);
1334 if (vma_wants_writenotify(vma
)) {
1335 pgprot_t pprot
= vma
->vm_page_prot
;
1337 /* Can vma->vm_page_prot have changed??
1339 * Answer: Yes, drivers may have changed it in their
1340 * f_op->mmap method.
1342 * Ensures that vmas marked as uncached stay that way.
1344 vma
->vm_page_prot
= vm_get_page_prot(vm_flags
& ~VM_SHARED
);
1345 if (pgprot_val(pprot
) == pgprot_val(pgprot_noncached(pprot
)))
1346 vma
->vm_page_prot
= pgprot_noncached(vma
->vm_page_prot
);
1349 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
1350 file
= vma
->vm_file
;
1352 /* Once vma denies write, undo our temporary denial count */
1354 atomic_inc(&inode
->i_writecount
);
1356 perf_event_mmap(vma
);
1358 mm
->total_vm
+= len
>> PAGE_SHIFT
;
1359 vm_stat_account(mm
, vm_flags
, file
, len
>> PAGE_SHIFT
);
1360 if (vm_flags
& VM_LOCKED
) {
1361 if (!mlock_vma_pages_range(vma
, addr
, addr
+ len
))
1362 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
1363 } else if ((flags
& MAP_POPULATE
) && !(flags
& MAP_NONBLOCK
))
1364 make_pages_present(addr
, addr
+ len
);
1366 if (file
&& uprobe_mmap(vma
))
1367 /* matching probes but cannot insert */
1368 goto unmap_and_free_vma
;
1374 atomic_inc(&inode
->i_writecount
);
1375 vma
->vm_file
= NULL
;
1378 /* Undo any partial mapping done by a device driver. */
1379 unmap_region(mm
, vma
, prev
, vma
->vm_start
, vma
->vm_end
);
1382 kmem_cache_free(vm_area_cachep
, vma
);
1385 vm_unacct_memory(charged
);
1389 /* Get an address range which is currently unmapped.
1390 * For shmat() with addr=0.
1392 * Ugly calling convention alert:
1393 * Return value with the low bits set means error value,
1395 * if (ret & ~PAGE_MASK)
1398 * This function "knows" that -ENOMEM has the bits set.
1400 #ifndef HAVE_ARCH_UNMAPPED_AREA
1402 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
1403 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1405 struct mm_struct
*mm
= current
->mm
;
1406 struct vm_area_struct
*vma
;
1407 unsigned long start_addr
;
1409 if (len
> TASK_SIZE
)
1412 if (flags
& MAP_FIXED
)
1416 addr
= PAGE_ALIGN(addr
);
1417 vma
= find_vma(mm
, addr
);
1418 if (TASK_SIZE
- len
>= addr
&&
1419 (!vma
|| addr
+ len
<= vma
->vm_start
))
1422 if (len
> mm
->cached_hole_size
) {
1423 start_addr
= addr
= mm
->free_area_cache
;
1425 start_addr
= addr
= TASK_UNMAPPED_BASE
;
1426 mm
->cached_hole_size
= 0;
1430 for (vma
= find_vma(mm
, addr
); ; vma
= vma
->vm_next
) {
1431 /* At this point: (!vma || addr < vma->vm_end). */
1432 if (TASK_SIZE
- len
< addr
) {
1434 * Start a new search - just in case we missed
1437 if (start_addr
!= TASK_UNMAPPED_BASE
) {
1438 addr
= TASK_UNMAPPED_BASE
;
1440 mm
->cached_hole_size
= 0;
1445 if (!vma
|| addr
+ len
<= vma
->vm_start
) {
1447 * Remember the place where we stopped the search:
1449 mm
->free_area_cache
= addr
+ len
;
1452 if (addr
+ mm
->cached_hole_size
< vma
->vm_start
)
1453 mm
->cached_hole_size
= vma
->vm_start
- addr
;
1459 void arch_unmap_area(struct mm_struct
*mm
, unsigned long addr
)
1462 * Is this a new hole at the lowest possible address?
1464 if (addr
>= TASK_UNMAPPED_BASE
&& addr
< mm
->free_area_cache
)
1465 mm
->free_area_cache
= addr
;
1469 * This mmap-allocator allocates new areas top-down from below the
1470 * stack's low limit (the base):
1472 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1474 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
1475 const unsigned long len
, const unsigned long pgoff
,
1476 const unsigned long flags
)
1478 struct vm_area_struct
*vma
;
1479 struct mm_struct
*mm
= current
->mm
;
1480 unsigned long addr
= addr0
, start_addr
;
1482 /* requested length too big for entire address space */
1483 if (len
> TASK_SIZE
)
1486 if (flags
& MAP_FIXED
)
1489 /* requesting a specific address */
1491 addr
= PAGE_ALIGN(addr
);
1492 vma
= find_vma(mm
, addr
);
1493 if (TASK_SIZE
- len
>= addr
&&
1494 (!vma
|| addr
+ len
<= vma
->vm_start
))
1498 /* check if free_area_cache is useful for us */
1499 if (len
<= mm
->cached_hole_size
) {
1500 mm
->cached_hole_size
= 0;
1501 mm
->free_area_cache
= mm
->mmap_base
;
1505 /* either no address requested or can't fit in requested address hole */
1506 start_addr
= addr
= mm
->free_area_cache
;
1514 * Lookup failure means no vma is above this address,
1515 * else if new region fits below vma->vm_start,
1516 * return with success:
1518 vma
= find_vma(mm
, addr
);
1519 if (!vma
|| addr
+len
<= vma
->vm_start
)
1520 /* remember the address as a hint for next time */
1521 return (mm
->free_area_cache
= addr
);
1523 /* remember the largest hole we saw so far */
1524 if (addr
+ mm
->cached_hole_size
< vma
->vm_start
)
1525 mm
->cached_hole_size
= vma
->vm_start
- addr
;
1527 /* try just below the current vma->vm_start */
1528 addr
= vma
->vm_start
-len
;
1529 } while (len
< vma
->vm_start
);
1533 * if hint left us with no space for the requested
1534 * mapping then try again:
1536 * Note: this is different with the case of bottomup
1537 * which does the fully line-search, but we use find_vma
1538 * here that causes some holes skipped.
1540 if (start_addr
!= mm
->mmap_base
) {
1541 mm
->free_area_cache
= mm
->mmap_base
;
1542 mm
->cached_hole_size
= 0;
1547 * A failed mmap() very likely causes application failure,
1548 * so fall back to the bottom-up function here. This scenario
1549 * can happen with large stack limits and large mmap()
1552 mm
->cached_hole_size
= ~0UL;
1553 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
1554 addr
= arch_get_unmapped_area(filp
, addr0
, len
, pgoff
, flags
);
1556 * Restore the topdown base:
1558 mm
->free_area_cache
= mm
->mmap_base
;
1559 mm
->cached_hole_size
= ~0UL;
1565 void arch_unmap_area_topdown(struct mm_struct
*mm
, unsigned long addr
)
1568 * Is this a new hole at the highest possible address?
1570 if (addr
> mm
->free_area_cache
)
1571 mm
->free_area_cache
= addr
;
1573 /* dont allow allocations above current base */
1574 if (mm
->free_area_cache
> mm
->mmap_base
)
1575 mm
->free_area_cache
= mm
->mmap_base
;
1579 get_unmapped_area(struct file
*file
, unsigned long addr
, unsigned long len
,
1580 unsigned long pgoff
, unsigned long flags
)
1582 unsigned long (*get_area
)(struct file
*, unsigned long,
1583 unsigned long, unsigned long, unsigned long);
1585 unsigned long error
= arch_mmap_check(addr
, len
, flags
);
1589 /* Careful about overflows.. */
1590 if (len
> TASK_SIZE
)
1593 get_area
= current
->mm
->get_unmapped_area
;
1594 if (file
&& file
->f_op
&& file
->f_op
->get_unmapped_area
)
1595 get_area
= file
->f_op
->get_unmapped_area
;
1596 addr
= get_area(file
, addr
, len
, pgoff
, flags
);
1597 if (IS_ERR_VALUE(addr
))
1600 if (addr
> TASK_SIZE
- len
)
1602 if (addr
& ~PAGE_MASK
)
1605 return arch_rebalance_pgtables(addr
, len
);
1608 EXPORT_SYMBOL(get_unmapped_area
);
1610 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1611 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
1613 struct vm_area_struct
*vma
= NULL
;
1616 /* Check the cache first. */
1617 /* (Cache hit rate is typically around 35%.) */
1618 vma
= mm
->mmap_cache
;
1619 if (!(vma
&& vma
->vm_end
> addr
&& vma
->vm_start
<= addr
)) {
1620 struct rb_node
* rb_node
;
1622 rb_node
= mm
->mm_rb
.rb_node
;
1626 struct vm_area_struct
* vma_tmp
;
1628 vma_tmp
= rb_entry(rb_node
,
1629 struct vm_area_struct
, vm_rb
);
1631 if (vma_tmp
->vm_end
> addr
) {
1633 if (vma_tmp
->vm_start
<= addr
)
1635 rb_node
= rb_node
->rb_left
;
1637 rb_node
= rb_node
->rb_right
;
1640 mm
->mmap_cache
= vma
;
1646 EXPORT_SYMBOL(find_vma
);
1649 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1651 struct vm_area_struct
*
1652 find_vma_prev(struct mm_struct
*mm
, unsigned long addr
,
1653 struct vm_area_struct
**pprev
)
1655 struct vm_area_struct
*vma
;
1657 vma
= find_vma(mm
, addr
);
1659 *pprev
= vma
->vm_prev
;
1661 struct rb_node
*rb_node
= mm
->mm_rb
.rb_node
;
1664 *pprev
= rb_entry(rb_node
, struct vm_area_struct
, vm_rb
);
1665 rb_node
= rb_node
->rb_right
;
1672 * Verify that the stack growth is acceptable and
1673 * update accounting. This is shared with both the
1674 * grow-up and grow-down cases.
1676 static int acct_stack_growth(struct vm_area_struct
*vma
, unsigned long size
, unsigned long grow
)
1678 struct mm_struct
*mm
= vma
->vm_mm
;
1679 struct rlimit
*rlim
= current
->signal
->rlim
;
1680 unsigned long new_start
;
1682 /* address space limit tests */
1683 if (!may_expand_vm(mm
, grow
))
1686 /* Stack limit test */
1687 if (size
> ACCESS_ONCE(rlim
[RLIMIT_STACK
].rlim_cur
))
1690 /* mlock limit tests */
1691 if (vma
->vm_flags
& VM_LOCKED
) {
1692 unsigned long locked
;
1693 unsigned long limit
;
1694 locked
= mm
->locked_vm
+ grow
;
1695 limit
= ACCESS_ONCE(rlim
[RLIMIT_MEMLOCK
].rlim_cur
);
1696 limit
>>= PAGE_SHIFT
;
1697 if (locked
> limit
&& !capable(CAP_IPC_LOCK
))
1701 /* Check to ensure the stack will not grow into a hugetlb-only region */
1702 new_start
= (vma
->vm_flags
& VM_GROWSUP
) ? vma
->vm_start
:
1704 if (is_hugepage_only_range(vma
->vm_mm
, new_start
, size
))
1708 * Overcommit.. This must be the final test, as it will
1709 * update security statistics.
1711 if (security_vm_enough_memory_mm(mm
, grow
))
1714 /* Ok, everything looks good - let it rip */
1715 mm
->total_vm
+= grow
;
1716 if (vma
->vm_flags
& VM_LOCKED
)
1717 mm
->locked_vm
+= grow
;
1718 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, grow
);
1722 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1724 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1725 * vma is the last one with address > vma->vm_end. Have to extend vma.
1727 int expand_upwards(struct vm_area_struct
*vma
, unsigned long address
)
1731 if (!(vma
->vm_flags
& VM_GROWSUP
))
1735 * We must make sure the anon_vma is allocated
1736 * so that the anon_vma locking is not a noop.
1738 if (unlikely(anon_vma_prepare(vma
)))
1740 vma_lock_anon_vma(vma
);
1743 * vma->vm_start/vm_end cannot change under us because the caller
1744 * is required to hold the mmap_sem in read mode. We need the
1745 * anon_vma lock to serialize against concurrent expand_stacks.
1746 * Also guard against wrapping around to address 0.
1748 if (address
< PAGE_ALIGN(address
+4))
1749 address
= PAGE_ALIGN(address
+4);
1751 vma_unlock_anon_vma(vma
);
1756 /* Somebody else might have raced and expanded it already */
1757 if (address
> vma
->vm_end
) {
1758 unsigned long size
, grow
;
1760 size
= address
- vma
->vm_start
;
1761 grow
= (address
- vma
->vm_end
) >> PAGE_SHIFT
;
1764 if (vma
->vm_pgoff
+ (size
>> PAGE_SHIFT
) >= vma
->vm_pgoff
) {
1765 error
= acct_stack_growth(vma
, size
, grow
);
1767 vma
->vm_end
= address
;
1768 perf_event_mmap(vma
);
1772 vma_unlock_anon_vma(vma
);
1773 khugepaged_enter_vma_merge(vma
);
1776 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1779 * vma is the first one with address < vma->vm_start. Have to extend vma.
1781 int expand_downwards(struct vm_area_struct
*vma
,
1782 unsigned long address
)
1787 * We must make sure the anon_vma is allocated
1788 * so that the anon_vma locking is not a noop.
1790 if (unlikely(anon_vma_prepare(vma
)))
1793 address
&= PAGE_MASK
;
1794 error
= security_file_mmap(NULL
, 0, 0, 0, address
, 1);
1798 vma_lock_anon_vma(vma
);
1801 * vma->vm_start/vm_end cannot change under us because the caller
1802 * is required to hold the mmap_sem in read mode. We need the
1803 * anon_vma lock to serialize against concurrent expand_stacks.
1806 /* Somebody else might have raced and expanded it already */
1807 if (address
< vma
->vm_start
) {
1808 unsigned long size
, grow
;
1810 size
= vma
->vm_end
- address
;
1811 grow
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
1814 if (grow
<= vma
->vm_pgoff
) {
1815 error
= acct_stack_growth(vma
, size
, grow
);
1817 vma
->vm_start
= address
;
1818 vma
->vm_pgoff
-= grow
;
1819 perf_event_mmap(vma
);
1823 vma_unlock_anon_vma(vma
);
1824 khugepaged_enter_vma_merge(vma
);
1828 #ifdef CONFIG_STACK_GROWSUP
1829 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
1831 return expand_upwards(vma
, address
);
1834 struct vm_area_struct
*
1835 find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
1837 struct vm_area_struct
*vma
, *prev
;
1840 vma
= find_vma_prev(mm
, addr
, &prev
);
1841 if (vma
&& (vma
->vm_start
<= addr
))
1843 if (!prev
|| expand_stack(prev
, addr
))
1845 if (prev
->vm_flags
& VM_LOCKED
) {
1846 mlock_vma_pages_range(prev
, addr
, prev
->vm_end
);
1851 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
1853 return expand_downwards(vma
, address
);
1856 struct vm_area_struct
*
1857 find_extend_vma(struct mm_struct
* mm
, unsigned long addr
)
1859 struct vm_area_struct
* vma
;
1860 unsigned long start
;
1863 vma
= find_vma(mm
,addr
);
1866 if (vma
->vm_start
<= addr
)
1868 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
1870 start
= vma
->vm_start
;
1871 if (expand_stack(vma
, addr
))
1873 if (vma
->vm_flags
& VM_LOCKED
) {
1874 mlock_vma_pages_range(vma
, addr
, start
);
1881 * Ok - we have the memory areas we should free on the vma list,
1882 * so release them, and do the vma updates.
1884 * Called with the mm semaphore held.
1886 static void remove_vma_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
1888 /* Update high watermark before we lower total_vm */
1889 update_hiwater_vm(mm
);
1891 long nrpages
= vma_pages(vma
);
1893 mm
->total_vm
-= nrpages
;
1894 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, -nrpages
);
1895 vma
= remove_vma(vma
);
1901 * Get rid of page table information in the indicated region.
1903 * Called with the mm semaphore held.
1905 static void unmap_region(struct mm_struct
*mm
,
1906 struct vm_area_struct
*vma
, struct vm_area_struct
*prev
,
1907 unsigned long start
, unsigned long end
)
1909 struct vm_area_struct
*next
= prev
? prev
->vm_next
: mm
->mmap
;
1910 struct mmu_gather tlb
;
1911 unsigned long nr_accounted
= 0;
1914 tlb_gather_mmu(&tlb
, mm
, 0);
1915 update_hiwater_rss(mm
);
1916 unmap_vmas(&tlb
, vma
, start
, end
, &nr_accounted
, NULL
);
1917 vm_unacct_memory(nr_accounted
);
1918 free_pgtables(&tlb
, vma
, prev
? prev
->vm_end
: FIRST_USER_ADDRESS
,
1919 next
? next
->vm_start
: 0);
1920 tlb_finish_mmu(&tlb
, start
, end
);
1924 * Create a list of vma's touched by the unmap, removing them from the mm's
1925 * vma list as we go..
1928 detach_vmas_to_be_unmapped(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1929 struct vm_area_struct
*prev
, unsigned long end
)
1931 struct vm_area_struct
**insertion_point
;
1932 struct vm_area_struct
*tail_vma
= NULL
;
1935 insertion_point
= (prev
? &prev
->vm_next
: &mm
->mmap
);
1936 vma
->vm_prev
= NULL
;
1938 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
1942 } while (vma
&& vma
->vm_start
< end
);
1943 *insertion_point
= vma
;
1945 vma
->vm_prev
= prev
;
1946 tail_vma
->vm_next
= NULL
;
1947 if (mm
->unmap_area
== arch_unmap_area
)
1948 addr
= prev
? prev
->vm_end
: mm
->mmap_base
;
1950 addr
= vma
? vma
->vm_start
: mm
->mmap_base
;
1951 mm
->unmap_area(mm
, addr
);
1952 mm
->mmap_cache
= NULL
; /* Kill the cache. */
1956 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1957 * munmap path where it doesn't make sense to fail.
1959 static int __split_vma(struct mm_struct
* mm
, struct vm_area_struct
* vma
,
1960 unsigned long addr
, int new_below
)
1962 struct mempolicy
*pol
;
1963 struct vm_area_struct
*new;
1966 if (is_vm_hugetlb_page(vma
) && (addr
&
1967 ~(huge_page_mask(hstate_vma(vma
)))))
1970 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
1974 /* most fields are the same, copy all, and then fixup */
1977 INIT_LIST_HEAD(&new->anon_vma_chain
);
1982 new->vm_start
= addr
;
1983 new->vm_pgoff
+= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
);
1986 pol
= mpol_dup(vma_policy(vma
));
1991 vma_set_policy(new, pol
);
1993 if (anon_vma_clone(new, vma
))
1997 get_file(new->vm_file
);
1998 if (vma
->vm_flags
& VM_EXECUTABLE
)
1999 added_exe_file_vma(mm
);
2002 if (new->vm_ops
&& new->vm_ops
->open
)
2003 new->vm_ops
->open(new);
2006 err
= vma_adjust(vma
, addr
, vma
->vm_end
, vma
->vm_pgoff
+
2007 ((addr
- new->vm_start
) >> PAGE_SHIFT
), new);
2009 err
= vma_adjust(vma
, vma
->vm_start
, addr
, vma
->vm_pgoff
, new);
2015 /* Clean everything up if vma_adjust failed. */
2016 if (new->vm_ops
&& new->vm_ops
->close
)
2017 new->vm_ops
->close(new);
2019 if (vma
->vm_flags
& VM_EXECUTABLE
)
2020 removed_exe_file_vma(mm
);
2023 unlink_anon_vmas(new);
2027 kmem_cache_free(vm_area_cachep
, new);
2033 * Split a vma into two pieces at address 'addr', a new vma is allocated
2034 * either for the first part or the tail.
2036 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2037 unsigned long addr
, int new_below
)
2039 if (mm
->map_count
>= sysctl_max_map_count
)
2042 return __split_vma(mm
, vma
, addr
, new_below
);
2045 /* Munmap is split into 2 main parts -- this part which finds
2046 * what needs doing, and the areas themselves, which do the
2047 * work. This now handles partial unmappings.
2048 * Jeremy Fitzhardinge <jeremy@goop.org>
2050 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
)
2053 struct vm_area_struct
*vma
, *prev
, *last
;
2055 if ((start
& ~PAGE_MASK
) || start
> TASK_SIZE
|| len
> TASK_SIZE
-start
)
2058 if ((len
= PAGE_ALIGN(len
)) == 0)
2061 /* Find the first overlapping VMA */
2062 vma
= find_vma(mm
, start
);
2065 prev
= vma
->vm_prev
;
2066 /* we have start < vma->vm_end */
2068 /* if it doesn't overlap, we have nothing.. */
2070 if (vma
->vm_start
>= end
)
2074 * If we need to split any vma, do it now to save pain later.
2076 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2077 * unmapped vm_area_struct will remain in use: so lower split_vma
2078 * places tmp vma above, and higher split_vma places tmp vma below.
2080 if (start
> vma
->vm_start
) {
2084 * Make sure that map_count on return from munmap() will
2085 * not exceed its limit; but let map_count go just above
2086 * its limit temporarily, to help free resources as expected.
2088 if (end
< vma
->vm_end
&& mm
->map_count
>= sysctl_max_map_count
)
2091 error
= __split_vma(mm
, vma
, start
, 0);
2097 /* Does it split the last one? */
2098 last
= find_vma(mm
, end
);
2099 if (last
&& end
> last
->vm_start
) {
2100 int error
= __split_vma(mm
, last
, end
, 1);
2104 vma
= prev
? prev
->vm_next
: mm
->mmap
;
2107 * unlock any mlock()ed ranges before detaching vmas
2109 if (mm
->locked_vm
) {
2110 struct vm_area_struct
*tmp
= vma
;
2111 while (tmp
&& tmp
->vm_start
< end
) {
2112 if (tmp
->vm_flags
& VM_LOCKED
) {
2113 mm
->locked_vm
-= vma_pages(tmp
);
2114 munlock_vma_pages_all(tmp
);
2121 * Remove the vma's, and unmap the actual pages
2123 detach_vmas_to_be_unmapped(mm
, vma
, prev
, end
);
2124 unmap_region(mm
, vma
, prev
, start
, end
);
2126 /* Fix up all other VM information */
2127 remove_vma_list(mm
, vma
);
2132 EXPORT_SYMBOL(do_munmap
);
2134 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
2137 struct mm_struct
*mm
= current
->mm
;
2139 profile_munmap(addr
);
2141 down_write(&mm
->mmap_sem
);
2142 ret
= do_munmap(mm
, addr
, len
);
2143 up_write(&mm
->mmap_sem
);
2147 static inline void verify_mm_writelocked(struct mm_struct
*mm
)
2149 #ifdef CONFIG_DEBUG_VM
2150 if (unlikely(down_read_trylock(&mm
->mmap_sem
))) {
2152 up_read(&mm
->mmap_sem
);
2158 * this is really a simplified "do_mmap". it only handles
2159 * anonymous maps. eventually we may be able to do some
2160 * brk-specific accounting here.
2162 unsigned long do_brk(unsigned long addr
, unsigned long len
)
2164 struct mm_struct
* mm
= current
->mm
;
2165 struct vm_area_struct
* vma
, * prev
;
2166 unsigned long flags
;
2167 struct rb_node
** rb_link
, * rb_parent
;
2168 pgoff_t pgoff
= addr
>> PAGE_SHIFT
;
2171 len
= PAGE_ALIGN(len
);
2175 error
= security_file_mmap(NULL
, 0, 0, 0, addr
, 1);
2179 flags
= VM_DATA_DEFAULT_FLAGS
| VM_ACCOUNT
| mm
->def_flags
;
2181 error
= get_unmapped_area(NULL
, addr
, len
, 0, MAP_FIXED
);
2182 if (error
& ~PAGE_MASK
)
2188 if (mm
->def_flags
& VM_LOCKED
) {
2189 unsigned long locked
, lock_limit
;
2190 locked
= len
>> PAGE_SHIFT
;
2191 locked
+= mm
->locked_vm
;
2192 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
2193 lock_limit
>>= PAGE_SHIFT
;
2194 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
2199 * mm->mmap_sem is required to protect against another thread
2200 * changing the mappings in case we sleep.
2202 verify_mm_writelocked(mm
);
2205 * Clear old maps. this also does some error checking for us
2208 vma
= find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
2209 if (vma
&& vma
->vm_start
< addr
+ len
) {
2210 if (do_munmap(mm
, addr
, len
))
2215 /* Check against address space limits *after* clearing old maps... */
2216 if (!may_expand_vm(mm
, len
>> PAGE_SHIFT
))
2219 if (mm
->map_count
> sysctl_max_map_count
)
2222 if (security_vm_enough_memory_mm(mm
, len
>> PAGE_SHIFT
))
2225 /* Can we just expand an old private anonymous mapping? */
2226 vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, flags
,
2227 NULL
, NULL
, pgoff
, NULL
);
2232 * create a vma struct for an anonymous mapping
2234 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2236 vm_unacct_memory(len
>> PAGE_SHIFT
);
2240 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2242 vma
->vm_start
= addr
;
2243 vma
->vm_end
= addr
+ len
;
2244 vma
->vm_pgoff
= pgoff
;
2245 vma
->vm_flags
= flags
;
2246 vma
->vm_page_prot
= vm_get_page_prot(flags
);
2247 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2249 perf_event_mmap(vma
);
2250 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2251 if (flags
& VM_LOCKED
) {
2252 if (!mlock_vma_pages_range(vma
, addr
, addr
+ len
))
2253 mm
->locked_vm
+= (len
>> PAGE_SHIFT
);
2258 EXPORT_SYMBOL(do_brk
);
2260 /* Release all mmaps. */
2261 void exit_mmap(struct mm_struct
*mm
)
2263 struct mmu_gather tlb
;
2264 struct vm_area_struct
*vma
;
2265 unsigned long nr_accounted
= 0;
2267 /* mm's last user has gone, and its about to be pulled down */
2268 mmu_notifier_release(mm
);
2270 if (mm
->locked_vm
) {
2273 if (vma
->vm_flags
& VM_LOCKED
)
2274 munlock_vma_pages_all(vma
);
2282 if (!vma
) /* Can happen if dup_mmap() received an OOM */
2287 tlb_gather_mmu(&tlb
, mm
, 1);
2288 /* update_hiwater_rss(mm) here? but nobody should be looking */
2289 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2290 unmap_vmas(&tlb
, vma
, 0, -1, &nr_accounted
, NULL
);
2291 vm_unacct_memory(nr_accounted
);
2293 free_pgtables(&tlb
, vma
, FIRST_USER_ADDRESS
, 0);
2294 tlb_finish_mmu(&tlb
, 0, -1);
2297 * Walk the list again, actually closing and freeing it,
2298 * with preemption enabled, without holding any MM locks.
2301 vma
= remove_vma(vma
);
2303 BUG_ON(mm
->nr_ptes
> (FIRST_USER_ADDRESS
+PMD_SIZE
-1)>>PMD_SHIFT
);
2306 /* Insert vm structure into process list sorted by address
2307 * and into the inode's i_mmap tree. If vm_file is non-NULL
2308 * then i_mmap_mutex is taken here.
2310 int insert_vm_struct(struct mm_struct
* mm
, struct vm_area_struct
* vma
)
2312 struct vm_area_struct
* __vma
, * prev
;
2313 struct rb_node
** rb_link
, * rb_parent
;
2316 * The vm_pgoff of a purely anonymous vma should be irrelevant
2317 * until its first write fault, when page's anon_vma and index
2318 * are set. But now set the vm_pgoff it will almost certainly
2319 * end up with (unless mremap moves it elsewhere before that
2320 * first wfault), so /proc/pid/maps tells a consistent story.
2322 * By setting it to reflect the virtual start address of the
2323 * vma, merges and splits can happen in a seamless way, just
2324 * using the existing file pgoff checks and manipulations.
2325 * Similarly in do_mmap_pgoff and in do_brk.
2327 if (!vma
->vm_file
) {
2328 BUG_ON(vma
->anon_vma
);
2329 vma
->vm_pgoff
= vma
->vm_start
>> PAGE_SHIFT
;
2331 __vma
= find_vma_prepare(mm
,vma
->vm_start
,&prev
,&rb_link
,&rb_parent
);
2332 if (__vma
&& __vma
->vm_start
< vma
->vm_end
)
2334 if ((vma
->vm_flags
& VM_ACCOUNT
) &&
2335 security_vm_enough_memory_mm(mm
, vma_pages(vma
)))
2338 if (vma
->vm_file
&& uprobe_mmap(vma
))
2341 vma_link(mm
, vma
, prev
, rb_link
, rb_parent
);
2346 * Copy the vma structure to a new location in the same mm,
2347 * prior to moving page table entries, to effect an mremap move.
2349 struct vm_area_struct
*copy_vma(struct vm_area_struct
**vmap
,
2350 unsigned long addr
, unsigned long len
, pgoff_t pgoff
)
2352 struct vm_area_struct
*vma
= *vmap
;
2353 unsigned long vma_start
= vma
->vm_start
;
2354 struct mm_struct
*mm
= vma
->vm_mm
;
2355 struct vm_area_struct
*new_vma
, *prev
;
2356 struct rb_node
**rb_link
, *rb_parent
;
2357 struct mempolicy
*pol
;
2358 bool faulted_in_anon_vma
= true;
2361 * If anonymous vma has not yet been faulted, update new pgoff
2362 * to match new location, to increase its chance of merging.
2364 if (unlikely(!vma
->vm_file
&& !vma
->anon_vma
)) {
2365 pgoff
= addr
>> PAGE_SHIFT
;
2366 faulted_in_anon_vma
= false;
2369 find_vma_prepare(mm
, addr
, &prev
, &rb_link
, &rb_parent
);
2370 new_vma
= vma_merge(mm
, prev
, addr
, addr
+ len
, vma
->vm_flags
,
2371 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
2374 * Source vma may have been merged into new_vma
2376 if (unlikely(vma_start
>= new_vma
->vm_start
&&
2377 vma_start
< new_vma
->vm_end
)) {
2379 * The only way we can get a vma_merge with
2380 * self during an mremap is if the vma hasn't
2381 * been faulted in yet and we were allowed to
2382 * reset the dst vma->vm_pgoff to the
2383 * destination address of the mremap to allow
2384 * the merge to happen. mremap must change the
2385 * vm_pgoff linearity between src and dst vmas
2386 * (in turn preventing a vma_merge) to be
2387 * safe. It is only safe to keep the vm_pgoff
2388 * linear if there are no pages mapped yet.
2390 VM_BUG_ON(faulted_in_anon_vma
);
2393 anon_vma_moveto_tail(new_vma
);
2395 new_vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
2398 pol
= mpol_dup(vma_policy(vma
));
2401 INIT_LIST_HEAD(&new_vma
->anon_vma_chain
);
2402 if (anon_vma_clone(new_vma
, vma
))
2403 goto out_free_mempol
;
2404 vma_set_policy(new_vma
, pol
);
2405 new_vma
->vm_start
= addr
;
2406 new_vma
->vm_end
= addr
+ len
;
2407 new_vma
->vm_pgoff
= pgoff
;
2408 if (new_vma
->vm_file
) {
2409 get_file(new_vma
->vm_file
);
2411 if (uprobe_mmap(new_vma
))
2412 goto out_free_mempol
;
2414 if (vma
->vm_flags
& VM_EXECUTABLE
)
2415 added_exe_file_vma(mm
);
2417 if (new_vma
->vm_ops
&& new_vma
->vm_ops
->open
)
2418 new_vma
->vm_ops
->open(new_vma
);
2419 vma_link(mm
, new_vma
, prev
, rb_link
, rb_parent
);
2427 kmem_cache_free(vm_area_cachep
, new_vma
);
2432 * Return true if the calling process may expand its vm space by the passed
2435 int may_expand_vm(struct mm_struct
*mm
, unsigned long npages
)
2437 unsigned long cur
= mm
->total_vm
; /* pages */
2440 lim
= rlimit(RLIMIT_AS
) >> PAGE_SHIFT
;
2442 if (cur
+ npages
> lim
)
2448 static int special_mapping_fault(struct vm_area_struct
*vma
,
2449 struct vm_fault
*vmf
)
2452 struct page
**pages
;
2455 * special mappings have no vm_file, and in that case, the mm
2456 * uses vm_pgoff internally. So we have to subtract it from here.
2457 * We are allowed to do this because we are the mm; do not copy
2458 * this code into drivers!
2460 pgoff
= vmf
->pgoff
- vma
->vm_pgoff
;
2462 for (pages
= vma
->vm_private_data
; pgoff
&& *pages
; ++pages
)
2466 struct page
*page
= *pages
;
2472 return VM_FAULT_SIGBUS
;
2476 * Having a close hook prevents vma merging regardless of flags.
2478 static void special_mapping_close(struct vm_area_struct
*vma
)
2482 static const struct vm_operations_struct special_mapping_vmops
= {
2483 .close
= special_mapping_close
,
2484 .fault
= special_mapping_fault
,
2488 * Called with mm->mmap_sem held for writing.
2489 * Insert a new vma covering the given region, with the given flags.
2490 * Its pages are supplied by the given array of struct page *.
2491 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2492 * The region past the last page supplied will always produce SIGBUS.
2493 * The array pointer and the pages it points to are assumed to stay alive
2494 * for as long as this mapping might exist.
2496 int install_special_mapping(struct mm_struct
*mm
,
2497 unsigned long addr
, unsigned long len
,
2498 unsigned long vm_flags
, struct page
**pages
)
2501 struct vm_area_struct
*vma
;
2503 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
2504 if (unlikely(vma
== NULL
))
2507 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
2509 vma
->vm_start
= addr
;
2510 vma
->vm_end
= addr
+ len
;
2512 vma
->vm_flags
= vm_flags
| mm
->def_flags
| VM_DONTEXPAND
;
2513 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
2515 vma
->vm_ops
= &special_mapping_vmops
;
2516 vma
->vm_private_data
= pages
;
2518 ret
= security_file_mmap(NULL
, 0, 0, 0, vma
->vm_start
, 1);
2522 ret
= insert_vm_struct(mm
, vma
);
2526 mm
->total_vm
+= len
>> PAGE_SHIFT
;
2528 perf_event_mmap(vma
);
2533 kmem_cache_free(vm_area_cachep
, vma
);
2537 static DEFINE_MUTEX(mm_all_locks_mutex
);
2539 static void vm_lock_anon_vma(struct mm_struct
*mm
, struct anon_vma
*anon_vma
)
2541 if (!test_bit(0, (unsigned long *) &anon_vma
->root
->head
.next
)) {
2543 * The LSB of head.next can't change from under us
2544 * because we hold the mm_all_locks_mutex.
2546 mutex_lock_nest_lock(&anon_vma
->root
->mutex
, &mm
->mmap_sem
);
2548 * We can safely modify head.next after taking the
2549 * anon_vma->root->mutex. If some other vma in this mm shares
2550 * the same anon_vma we won't take it again.
2552 * No need of atomic instructions here, head.next
2553 * can't change from under us thanks to the
2554 * anon_vma->root->mutex.
2556 if (__test_and_set_bit(0, (unsigned long *)
2557 &anon_vma
->root
->head
.next
))
2562 static void vm_lock_mapping(struct mm_struct
*mm
, struct address_space
*mapping
)
2564 if (!test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
2566 * AS_MM_ALL_LOCKS can't change from under us because
2567 * we hold the mm_all_locks_mutex.
2569 * Operations on ->flags have to be atomic because
2570 * even if AS_MM_ALL_LOCKS is stable thanks to the
2571 * mm_all_locks_mutex, there may be other cpus
2572 * changing other bitflags in parallel to us.
2574 if (test_and_set_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
))
2576 mutex_lock_nest_lock(&mapping
->i_mmap_mutex
, &mm
->mmap_sem
);
2581 * This operation locks against the VM for all pte/vma/mm related
2582 * operations that could ever happen on a certain mm. This includes
2583 * vmtruncate, try_to_unmap, and all page faults.
2585 * The caller must take the mmap_sem in write mode before calling
2586 * mm_take_all_locks(). The caller isn't allowed to release the
2587 * mmap_sem until mm_drop_all_locks() returns.
2589 * mmap_sem in write mode is required in order to block all operations
2590 * that could modify pagetables and free pages without need of
2591 * altering the vma layout (for example populate_range() with
2592 * nonlinear vmas). It's also needed in write mode to avoid new
2593 * anon_vmas to be associated with existing vmas.
2595 * A single task can't take more than one mm_take_all_locks() in a row
2596 * or it would deadlock.
2598 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2599 * mapping->flags avoid to take the same lock twice, if more than one
2600 * vma in this mm is backed by the same anon_vma or address_space.
2602 * We can take all the locks in random order because the VM code
2603 * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
2604 * takes more than one of them in a row. Secondly we're protected
2605 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2607 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2608 * that may have to take thousand of locks.
2610 * mm_take_all_locks() can fail if it's interrupted by signals.
2612 int mm_take_all_locks(struct mm_struct
*mm
)
2614 struct vm_area_struct
*vma
;
2615 struct anon_vma_chain
*avc
;
2617 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
2619 mutex_lock(&mm_all_locks_mutex
);
2621 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2622 if (signal_pending(current
))
2624 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
2625 vm_lock_mapping(mm
, vma
->vm_file
->f_mapping
);
2628 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2629 if (signal_pending(current
))
2632 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
2633 vm_lock_anon_vma(mm
, avc
->anon_vma
);
2639 mm_drop_all_locks(mm
);
2643 static void vm_unlock_anon_vma(struct anon_vma
*anon_vma
)
2645 if (test_bit(0, (unsigned long *) &anon_vma
->root
->head
.next
)) {
2647 * The LSB of head.next can't change to 0 from under
2648 * us because we hold the mm_all_locks_mutex.
2650 * We must however clear the bitflag before unlocking
2651 * the vma so the users using the anon_vma->head will
2652 * never see our bitflag.
2654 * No need of atomic instructions here, head.next
2655 * can't change from under us until we release the
2656 * anon_vma->root->mutex.
2658 if (!__test_and_clear_bit(0, (unsigned long *)
2659 &anon_vma
->root
->head
.next
))
2661 anon_vma_unlock(anon_vma
);
2665 static void vm_unlock_mapping(struct address_space
*mapping
)
2667 if (test_bit(AS_MM_ALL_LOCKS
, &mapping
->flags
)) {
2669 * AS_MM_ALL_LOCKS can't change to 0 from under us
2670 * because we hold the mm_all_locks_mutex.
2672 mutex_unlock(&mapping
->i_mmap_mutex
);
2673 if (!test_and_clear_bit(AS_MM_ALL_LOCKS
,
2680 * The mmap_sem cannot be released by the caller until
2681 * mm_drop_all_locks() returns.
2683 void mm_drop_all_locks(struct mm_struct
*mm
)
2685 struct vm_area_struct
*vma
;
2686 struct anon_vma_chain
*avc
;
2688 BUG_ON(down_read_trylock(&mm
->mmap_sem
));
2689 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex
));
2691 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2693 list_for_each_entry(avc
, &vma
->anon_vma_chain
, same_vma
)
2694 vm_unlock_anon_vma(avc
->anon_vma
);
2695 if (vma
->vm_file
&& vma
->vm_file
->f_mapping
)
2696 vm_unlock_mapping(vma
->vm_file
->f_mapping
);
2699 mutex_unlock(&mm_all_locks_mutex
);
2703 * initialise the VMA slab
2705 void __init
mmap_init(void)
2709 ret
= percpu_counter_init(&vm_committed_as
, 0);