4 * (C) Copyright 1996 Linus Torvalds
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
11 #include <linux/hugetlb.h>
12 #include <linux/shm.h>
13 #include <linux/ksm.h>
14 #include <linux/mman.h>
15 #include <linux/swap.h>
16 #include <linux/capability.h>
18 #include <linux/swapops.h>
19 #include <linux/highmem.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/mmu_notifier.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/uaccess.h>
25 #include <linux/mm-arch-hooks.h>
27 #include <asm/cacheflush.h>
28 #include <asm/tlbflush.h>
32 static pmd_t
*get_old_pmd(struct mm_struct
*mm
, unsigned long addr
)
38 pgd
= pgd_offset(mm
, addr
);
39 if (pgd_none_or_clear_bad(pgd
))
42 pud
= pud_offset(pgd
, addr
);
43 if (pud_none_or_clear_bad(pud
))
46 pmd
= pmd_offset(pud
, addr
);
53 static pmd_t
*alloc_new_pmd(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
60 pgd
= pgd_offset(mm
, addr
);
61 pud
= pud_alloc(mm
, pgd
, addr
);
65 pmd
= pmd_alloc(mm
, pud
, addr
);
69 VM_BUG_ON(pmd_trans_huge(*pmd
));
74 static pte_t
move_soft_dirty_pte(pte_t pte
)
77 * Set soft dirty bit so we can notice
78 * in userspace the ptes were moved.
80 #ifdef CONFIG_MEM_SOFT_DIRTY
82 pte
= pte_mksoft_dirty(pte
);
83 else if (is_swap_pte(pte
))
84 pte
= pte_swp_mksoft_dirty(pte
);
89 static void move_ptes(struct vm_area_struct
*vma
, pmd_t
*old_pmd
,
90 unsigned long old_addr
, unsigned long old_end
,
91 struct vm_area_struct
*new_vma
, pmd_t
*new_pmd
,
92 unsigned long new_addr
, bool need_rmap_locks
)
94 struct address_space
*mapping
= NULL
;
95 struct anon_vma
*anon_vma
= NULL
;
96 struct mm_struct
*mm
= vma
->vm_mm
;
97 pte_t
*old_pte
, *new_pte
, pte
;
98 spinlock_t
*old_ptl
, *new_ptl
;
101 * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
102 * locks to ensure that rmap will always observe either the old or the
103 * new ptes. This is the easiest way to avoid races with
104 * truncate_pagecache(), page migration, etc...
106 * When need_rmap_locks is false, we use other ways to avoid
109 * - During exec() shift_arg_pages(), we use a specially tagged vma
110 * which rmap call sites look for using is_vma_temporary_stack().
112 * - During mremap(), new_vma is often known to be placed after vma
113 * in rmap traversal order. This ensures rmap will always observe
114 * either the old pte, or the new pte, or both (the page table locks
115 * serialize access to individual ptes, but only rmap traversal
116 * order guarantees that we won't miss both the old and new ptes).
118 if (need_rmap_locks
) {
120 mapping
= vma
->vm_file
->f_mapping
;
121 i_mmap_lock_write(mapping
);
124 anon_vma
= vma
->anon_vma
;
125 anon_vma_lock_write(anon_vma
);
130 * We don't have to worry about the ordering of src and dst
131 * pte locks because exclusive mmap_sem prevents deadlock.
133 old_pte
= pte_offset_map_lock(mm
, old_pmd
, old_addr
, &old_ptl
);
134 new_pte
= pte_offset_map(new_pmd
, new_addr
);
135 new_ptl
= pte_lockptr(mm
, new_pmd
);
136 if (new_ptl
!= old_ptl
)
137 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
138 arch_enter_lazy_mmu_mode();
140 for (; old_addr
< old_end
; old_pte
++, old_addr
+= PAGE_SIZE
,
141 new_pte
++, new_addr
+= PAGE_SIZE
) {
142 if (pte_none(*old_pte
))
144 pte
= ptep_get_and_clear(mm
, old_addr
, old_pte
);
145 pte
= move_pte(pte
, new_vma
->vm_page_prot
, old_addr
, new_addr
);
146 pte
= move_soft_dirty_pte(pte
);
147 set_pte_at(mm
, new_addr
, new_pte
, pte
);
150 arch_leave_lazy_mmu_mode();
151 if (new_ptl
!= old_ptl
)
152 spin_unlock(new_ptl
);
153 pte_unmap(new_pte
- 1);
154 pte_unmap_unlock(old_pte
- 1, old_ptl
);
156 anon_vma_unlock_write(anon_vma
);
158 i_mmap_unlock_write(mapping
);
161 #define LATENCY_LIMIT (64 * PAGE_SIZE)
163 unsigned long move_page_tables(struct vm_area_struct
*vma
,
164 unsigned long old_addr
, struct vm_area_struct
*new_vma
,
165 unsigned long new_addr
, unsigned long len
,
166 bool need_rmap_locks
)
168 unsigned long extent
, next
, old_end
;
169 pmd_t
*old_pmd
, *new_pmd
;
170 bool need_flush
= false;
171 unsigned long mmun_start
; /* For mmu_notifiers */
172 unsigned long mmun_end
; /* For mmu_notifiers */
174 old_end
= old_addr
+ len
;
175 flush_cache_range(vma
, old_addr
, old_end
);
177 mmun_start
= old_addr
;
179 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
181 for (; old_addr
< old_end
; old_addr
+= extent
, new_addr
+= extent
) {
183 next
= (old_addr
+ PMD_SIZE
) & PMD_MASK
;
184 /* even if next overflowed, extent below will be ok */
185 extent
= next
- old_addr
;
186 if (extent
> old_end
- old_addr
)
187 extent
= old_end
- old_addr
;
188 old_pmd
= get_old_pmd(vma
->vm_mm
, old_addr
);
191 new_pmd
= alloc_new_pmd(vma
->vm_mm
, vma
, new_addr
);
194 if (pmd_trans_huge(*old_pmd
)) {
196 if (extent
== HPAGE_PMD_SIZE
) {
197 VM_BUG_ON_VMA(vma
->vm_file
|| !vma
->anon_vma
,
199 /* See comment in move_ptes() */
201 anon_vma_lock_write(vma
->anon_vma
);
202 err
= move_huge_pmd(vma
, new_vma
, old_addr
,
206 anon_vma_unlock_write(vma
->anon_vma
);
212 split_huge_page_pmd(vma
, old_addr
, old_pmd
);
214 VM_BUG_ON(pmd_trans_huge(*old_pmd
));
216 if (pmd_none(*new_pmd
) && __pte_alloc(new_vma
->vm_mm
, new_vma
,
219 next
= (new_addr
+ PMD_SIZE
) & PMD_MASK
;
220 if (extent
> next
- new_addr
)
221 extent
= next
- new_addr
;
222 if (extent
> LATENCY_LIMIT
)
223 extent
= LATENCY_LIMIT
;
224 move_ptes(vma
, old_pmd
, old_addr
, old_addr
+ extent
,
225 new_vma
, new_pmd
, new_addr
, need_rmap_locks
);
228 if (likely(need_flush
))
229 flush_tlb_range(vma
, old_end
-len
, old_addr
);
231 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
233 return len
+ old_addr
- old_end
; /* how much done */
236 static unsigned long move_vma(struct vm_area_struct
*vma
,
237 unsigned long old_addr
, unsigned long old_len
,
238 unsigned long new_len
, unsigned long new_addr
, bool *locked
)
240 struct mm_struct
*mm
= vma
->vm_mm
;
241 struct vm_area_struct
*new_vma
;
242 unsigned long vm_flags
= vma
->vm_flags
;
243 unsigned long new_pgoff
;
244 unsigned long moved_len
;
245 unsigned long excess
= 0;
246 unsigned long hiwater_vm
;
249 bool need_rmap_locks
;
252 * We'd prefer to avoid failure later on in do_munmap:
253 * which may split one vma into three before unmapping.
255 if (mm
->map_count
>= sysctl_max_map_count
- 3)
259 * Advise KSM to break any KSM pages in the area to be moved:
260 * it would be confusing if they were to turn up at the new
261 * location, where they happen to coincide with different KSM
262 * pages recently unmapped. But leave vma->vm_flags as it was,
263 * so KSM can come around to merge on vma and new_vma afterwards.
265 err
= ksm_madvise(vma
, old_addr
, old_addr
+ old_len
,
266 MADV_UNMERGEABLE
, &vm_flags
);
270 new_pgoff
= vma
->vm_pgoff
+ ((old_addr
- vma
->vm_start
) >> PAGE_SHIFT
);
271 new_vma
= copy_vma(&vma
, new_addr
, new_len
, new_pgoff
,
276 moved_len
= move_page_tables(vma
, old_addr
, new_vma
, new_addr
, old_len
,
278 if (moved_len
< old_len
) {
280 } else if (vma
->vm_ops
&& vma
->vm_ops
->mremap
) {
281 err
= vma
->vm_ops
->mremap(new_vma
);
286 * On error, move entries back from new area to old,
287 * which will succeed since page tables still there,
288 * and then proceed to unmap new area instead of old.
290 move_page_tables(new_vma
, new_addr
, vma
, old_addr
, moved_len
,
297 arch_remap(mm
, old_addr
, old_addr
+ old_len
,
298 new_addr
, new_addr
+ new_len
);
301 /* Conceal VM_ACCOUNT so old reservation is not undone */
302 if (vm_flags
& VM_ACCOUNT
) {
303 vma
->vm_flags
&= ~VM_ACCOUNT
;
304 excess
= vma
->vm_end
- vma
->vm_start
- old_len
;
305 if (old_addr
> vma
->vm_start
&&
306 old_addr
+ old_len
< vma
->vm_end
)
311 * If we failed to move page tables we still do total_vm increment
312 * since do_munmap() will decrement it by old_len == new_len.
314 * Since total_vm is about to be raised artificially high for a
315 * moment, we need to restore high watermark afterwards: if stats
316 * are taken meanwhile, total_vm and hiwater_vm appear too high.
317 * If this were a serious issue, we'd add a flag to do_munmap().
319 hiwater_vm
= mm
->hiwater_vm
;
320 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, new_len
>>PAGE_SHIFT
);
322 if (do_munmap(mm
, old_addr
, old_len
) < 0) {
323 /* OOM: unable to split vma, just get accounts right */
324 vm_unacct_memory(excess
>> PAGE_SHIFT
);
327 mm
->hiwater_vm
= hiwater_vm
;
329 /* Restore VM_ACCOUNT if one or two pieces of vma left */
331 vma
->vm_flags
|= VM_ACCOUNT
;
333 vma
->vm_next
->vm_flags
|= VM_ACCOUNT
;
336 if (vm_flags
& VM_LOCKED
) {
337 mm
->locked_vm
+= new_len
>> PAGE_SHIFT
;
344 static struct vm_area_struct
*vma_to_resize(unsigned long addr
,
345 unsigned long old_len
, unsigned long new_len
, unsigned long *p
)
347 struct mm_struct
*mm
= current
->mm
;
348 struct vm_area_struct
*vma
= find_vma(mm
, addr
);
351 if (!vma
|| vma
->vm_start
> addr
)
352 return ERR_PTR(-EFAULT
);
354 if (is_vm_hugetlb_page(vma
))
355 return ERR_PTR(-EINVAL
);
357 /* We can't remap across vm area boundaries */
358 if (old_len
> vma
->vm_end
- addr
)
359 return ERR_PTR(-EFAULT
);
361 if (new_len
== old_len
)
364 /* Need to be careful about a growing mapping */
365 pgoff
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
366 pgoff
+= vma
->vm_pgoff
;
367 if (pgoff
+ (new_len
>> PAGE_SHIFT
) < pgoff
)
368 return ERR_PTR(-EINVAL
);
370 if (vma
->vm_flags
& (VM_DONTEXPAND
| VM_PFNMAP
))
371 return ERR_PTR(-EFAULT
);
373 if (vma
->vm_flags
& VM_LOCKED
) {
374 unsigned long locked
, lock_limit
;
375 locked
= mm
->locked_vm
<< PAGE_SHIFT
;
376 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
377 locked
+= new_len
- old_len
;
378 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
379 return ERR_PTR(-EAGAIN
);
382 if (!may_expand_vm(mm
, (new_len
- old_len
) >> PAGE_SHIFT
))
383 return ERR_PTR(-ENOMEM
);
385 if (vma
->vm_flags
& VM_ACCOUNT
) {
386 unsigned long charged
= (new_len
- old_len
) >> PAGE_SHIFT
;
387 if (security_vm_enough_memory_mm(mm
, charged
))
388 return ERR_PTR(-ENOMEM
);
395 static unsigned long mremap_to(unsigned long addr
, unsigned long old_len
,
396 unsigned long new_addr
, unsigned long new_len
, bool *locked
)
398 struct mm_struct
*mm
= current
->mm
;
399 struct vm_area_struct
*vma
;
400 unsigned long ret
= -EINVAL
;
401 unsigned long charged
= 0;
402 unsigned long map_flags
;
404 if (new_addr
& ~PAGE_MASK
)
407 if (new_len
> TASK_SIZE
|| new_addr
> TASK_SIZE
- new_len
)
410 /* Ensure the old/new locations do not overlap */
411 if (addr
+ old_len
> new_addr
&& new_addr
+ new_len
> addr
)
414 ret
= do_munmap(mm
, new_addr
, new_len
);
418 if (old_len
>= new_len
) {
419 ret
= do_munmap(mm
, addr
+new_len
, old_len
- new_len
);
420 if (ret
&& old_len
!= new_len
)
425 vma
= vma_to_resize(addr
, old_len
, new_len
, &charged
);
431 map_flags
= MAP_FIXED
;
432 if (vma
->vm_flags
& VM_MAYSHARE
)
433 map_flags
|= MAP_SHARED
;
435 ret
= get_unmapped_area(vma
->vm_file
, new_addr
, new_len
, vma
->vm_pgoff
+
436 ((addr
- vma
->vm_start
) >> PAGE_SHIFT
),
438 if (ret
& ~PAGE_MASK
)
441 ret
= move_vma(vma
, addr
, old_len
, new_len
, new_addr
, locked
);
442 if (!(ret
& ~PAGE_MASK
))
445 vm_unacct_memory(charged
);
451 static int vma_expandable(struct vm_area_struct
*vma
, unsigned long delta
)
453 unsigned long end
= vma
->vm_end
+ delta
;
454 if (end
< vma
->vm_end
) /* overflow */
456 if (vma
->vm_next
&& vma
->vm_next
->vm_start
< end
) /* intersection */
458 if (get_unmapped_area(NULL
, vma
->vm_start
, end
- vma
->vm_start
,
459 0, MAP_FIXED
) & ~PAGE_MASK
)
465 * Expand (or shrink) an existing mapping, potentially moving it at the
466 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
468 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
469 * This option implies MREMAP_MAYMOVE.
471 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
472 unsigned long, new_len
, unsigned long, flags
,
473 unsigned long, new_addr
)
475 struct mm_struct
*mm
= current
->mm
;
476 struct vm_area_struct
*vma
;
477 unsigned long ret
= -EINVAL
;
478 unsigned long charged
= 0;
481 if (flags
& ~(MREMAP_FIXED
| MREMAP_MAYMOVE
))
484 if (flags
& MREMAP_FIXED
&& !(flags
& MREMAP_MAYMOVE
))
487 if (addr
& ~PAGE_MASK
)
490 old_len
= PAGE_ALIGN(old_len
);
491 new_len
= PAGE_ALIGN(new_len
);
494 * We allow a zero old-len as a special case
495 * for DOS-emu "duplicate shm area" thing. But
496 * a zero new-len is nonsensical.
501 down_write(¤t
->mm
->mmap_sem
);
503 if (flags
& MREMAP_FIXED
) {
504 ret
= mremap_to(addr
, old_len
, new_addr
, new_len
,
510 * Always allow a shrinking remap: that just unmaps
511 * the unnecessary pages..
512 * do_munmap does all the needed commit accounting
514 if (old_len
>= new_len
) {
515 ret
= do_munmap(mm
, addr
+new_len
, old_len
- new_len
);
516 if (ret
&& old_len
!= new_len
)
523 * Ok, we need to grow..
525 vma
= vma_to_resize(addr
, old_len
, new_len
, &charged
);
531 /* old_len exactly to the end of the area..
533 if (old_len
== vma
->vm_end
- addr
) {
534 /* can we just expand the current mapping? */
535 if (vma_expandable(vma
, new_len
- old_len
)) {
536 int pages
= (new_len
- old_len
) >> PAGE_SHIFT
;
538 if (vma_adjust(vma
, vma
->vm_start
, addr
+ new_len
,
539 vma
->vm_pgoff
, NULL
)) {
544 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, pages
);
545 if (vma
->vm_flags
& VM_LOCKED
) {
546 mm
->locked_vm
+= pages
;
556 * We weren't able to just expand or shrink the area,
557 * we need to create a new one and move it..
560 if (flags
& MREMAP_MAYMOVE
) {
561 unsigned long map_flags
= 0;
562 if (vma
->vm_flags
& VM_MAYSHARE
)
563 map_flags
|= MAP_SHARED
;
565 new_addr
= get_unmapped_area(vma
->vm_file
, 0, new_len
,
567 ((addr
- vma
->vm_start
) >> PAGE_SHIFT
),
569 if (new_addr
& ~PAGE_MASK
) {
574 ret
= move_vma(vma
, addr
, old_len
, new_len
, new_addr
, &locked
);
577 if (ret
& ~PAGE_MASK
) {
578 vm_unacct_memory(charged
);
581 up_write(¤t
->mm
->mmap_sem
);
582 if (locked
&& new_len
> old_len
)
583 mm_populate(new_addr
+ old_len
, new_len
- old_len
);
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