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/highmem.h>
19 #include <linux/security.h>
20 #include <linux/syscalls.h>
21 #include <linux/mmu_notifier.h>
23 #include <asm/uaccess.h>
24 #include <asm/cacheflush.h>
25 #include <asm/tlbflush.h>
29 static pmd_t
*get_old_pmd(struct mm_struct
*mm
, unsigned long addr
)
35 pgd
= pgd_offset(mm
, addr
);
36 if (pgd_none_or_clear_bad(pgd
))
39 pud
= pud_offset(pgd
, addr
);
40 if (pud_none_or_clear_bad(pud
))
43 pmd
= pmd_offset(pud
, addr
);
50 static pmd_t
*alloc_new_pmd(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
57 pgd
= pgd_offset(mm
, addr
);
58 pud
= pud_alloc(mm
, pgd
, addr
);
62 pmd
= pmd_alloc(mm
, pud
, addr
);
66 VM_BUG_ON(pmd_trans_huge(*pmd
));
71 static void move_ptes(struct vm_area_struct
*vma
, pmd_t
*old_pmd
,
72 unsigned long old_addr
, unsigned long old_end
,
73 struct vm_area_struct
*new_vma
, pmd_t
*new_pmd
,
74 unsigned long new_addr
)
76 struct address_space
*mapping
= NULL
;
77 struct mm_struct
*mm
= vma
->vm_mm
;
78 pte_t
*old_pte
, *new_pte
, pte
;
79 spinlock_t
*old_ptl
, *new_ptl
;
83 * Subtle point from Rajesh Venkatasubramanian: before
84 * moving file-based ptes, we must lock truncate_pagecache
85 * out, since it might clean the dst vma before the src vma,
86 * and we propagate stale pages into the dst afterward.
88 mapping
= vma
->vm_file
->f_mapping
;
89 mutex_lock(&mapping
->i_mmap_mutex
);
93 * We don't have to worry about the ordering of src and dst
94 * pte locks because exclusive mmap_sem prevents deadlock.
96 old_pte
= pte_offset_map_lock(mm
, old_pmd
, old_addr
, &old_ptl
);
97 new_pte
= pte_offset_map(new_pmd
, new_addr
);
98 new_ptl
= pte_lockptr(mm
, new_pmd
);
99 if (new_ptl
!= old_ptl
)
100 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
101 arch_enter_lazy_mmu_mode();
103 for (; old_addr
< old_end
; old_pte
++, old_addr
+= PAGE_SIZE
,
104 new_pte
++, new_addr
+= PAGE_SIZE
) {
105 if (pte_none(*old_pte
))
107 pte
= ptep_get_and_clear(mm
, old_addr
, old_pte
);
108 pte
= move_pte(pte
, new_vma
->vm_page_prot
, old_addr
, new_addr
);
109 set_pte_at(mm
, new_addr
, new_pte
, pte
);
112 arch_leave_lazy_mmu_mode();
113 if (new_ptl
!= old_ptl
)
114 spin_unlock(new_ptl
);
115 pte_unmap(new_pte
- 1);
116 pte_unmap_unlock(old_pte
- 1, old_ptl
);
118 mutex_unlock(&mapping
->i_mmap_mutex
);
121 #define LATENCY_LIMIT (64 * PAGE_SIZE)
123 unsigned long move_page_tables(struct vm_area_struct
*vma
,
124 unsigned long old_addr
, struct vm_area_struct
*new_vma
,
125 unsigned long new_addr
, unsigned long len
)
127 unsigned long extent
, next
, old_end
;
128 pmd_t
*old_pmd
, *new_pmd
;
129 bool need_flush
= false;
131 old_end
= old_addr
+ len
;
132 flush_cache_range(vma
, old_addr
, old_end
);
134 mmu_notifier_invalidate_range_start(vma
->vm_mm
, old_addr
, old_end
);
136 for (; old_addr
< old_end
; old_addr
+= extent
, new_addr
+= extent
) {
138 next
= (old_addr
+ PMD_SIZE
) & PMD_MASK
;
139 /* even if next overflowed, extent below will be ok */
140 extent
= next
- old_addr
;
141 if (extent
> old_end
- old_addr
)
142 extent
= old_end
- old_addr
;
143 old_pmd
= get_old_pmd(vma
->vm_mm
, old_addr
);
146 new_pmd
= alloc_new_pmd(vma
->vm_mm
, vma
, new_addr
);
149 if (pmd_trans_huge(*old_pmd
)) {
151 if (extent
== HPAGE_PMD_SIZE
)
152 err
= move_huge_pmd(vma
, new_vma
, old_addr
,
159 split_huge_page_pmd(vma
->vm_mm
, old_pmd
);
161 VM_BUG_ON(pmd_trans_huge(*old_pmd
));
163 if (pmd_none(*new_pmd
) && __pte_alloc(new_vma
->vm_mm
, new_vma
,
166 next
= (new_addr
+ PMD_SIZE
) & PMD_MASK
;
167 if (extent
> next
- new_addr
)
168 extent
= next
- new_addr
;
169 if (extent
> LATENCY_LIMIT
)
170 extent
= LATENCY_LIMIT
;
171 move_ptes(vma
, old_pmd
, old_addr
, old_addr
+ extent
,
172 new_vma
, new_pmd
, new_addr
);
175 if (likely(need_flush
))
176 flush_tlb_range(vma
, old_end
-len
, old_addr
);
178 mmu_notifier_invalidate_range_end(vma
->vm_mm
, old_end
-len
, old_end
);
180 return len
+ old_addr
- old_end
; /* how much done */
183 static unsigned long move_vma(struct vm_area_struct
*vma
,
184 unsigned long old_addr
, unsigned long old_len
,
185 unsigned long new_len
, unsigned long new_addr
)
187 struct mm_struct
*mm
= vma
->vm_mm
;
188 struct vm_area_struct
*new_vma
;
189 unsigned long vm_flags
= vma
->vm_flags
;
190 unsigned long new_pgoff
;
191 unsigned long moved_len
;
192 unsigned long excess
= 0;
193 unsigned long hiwater_vm
;
198 * We'd prefer to avoid failure later on in do_munmap:
199 * which may split one vma into three before unmapping.
201 if (mm
->map_count
>= sysctl_max_map_count
- 3)
205 * Advise KSM to break any KSM pages in the area to be moved:
206 * it would be confusing if they were to turn up at the new
207 * location, where they happen to coincide with different KSM
208 * pages recently unmapped. But leave vma->vm_flags as it was,
209 * so KSM can come around to merge on vma and new_vma afterwards.
211 err
= ksm_madvise(vma
, old_addr
, old_addr
+ old_len
,
212 MADV_UNMERGEABLE
, &vm_flags
);
216 new_pgoff
= vma
->vm_pgoff
+ ((old_addr
- vma
->vm_start
) >> PAGE_SHIFT
);
217 new_vma
= copy_vma(&vma
, new_addr
, new_len
, new_pgoff
);
221 moved_len
= move_page_tables(vma
, old_addr
, new_vma
, new_addr
, old_len
);
222 if (moved_len
< old_len
) {
224 * Before moving the page tables from the new vma to
225 * the old vma, we need to be sure the old vma is
226 * queued after new vma in the same_anon_vma list to
227 * prevent SMP races with rmap_walk (that could lead
228 * rmap_walk to miss some page table).
230 anon_vma_moveto_tail(vma
);
233 * On error, move entries back from new area to old,
234 * which will succeed since page tables still there,
235 * and then proceed to unmap new area instead of old.
237 move_page_tables(new_vma
, new_addr
, vma
, old_addr
, moved_len
);
244 /* Conceal VM_ACCOUNT so old reservation is not undone */
245 if (vm_flags
& VM_ACCOUNT
) {
246 vma
->vm_flags
&= ~VM_ACCOUNT
;
247 excess
= vma
->vm_end
- vma
->vm_start
- old_len
;
248 if (old_addr
> vma
->vm_start
&&
249 old_addr
+ old_len
< vma
->vm_end
)
254 * If we failed to move page tables we still do total_vm increment
255 * since do_munmap() will decrement it by old_len == new_len.
257 * Since total_vm is about to be raised artificially high for a
258 * moment, we need to restore high watermark afterwards: if stats
259 * are taken meanwhile, total_vm and hiwater_vm appear too high.
260 * If this were a serious issue, we'd add a flag to do_munmap().
262 hiwater_vm
= mm
->hiwater_vm
;
263 mm
->total_vm
+= new_len
>> PAGE_SHIFT
;
264 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, new_len
>>PAGE_SHIFT
);
266 if (do_munmap(mm
, old_addr
, old_len
) < 0) {
267 /* OOM: unable to split vma, just get accounts right */
268 vm_unacct_memory(excess
>> PAGE_SHIFT
);
271 mm
->hiwater_vm
= hiwater_vm
;
273 /* Restore VM_ACCOUNT if one or two pieces of vma left */
275 vma
->vm_flags
|= VM_ACCOUNT
;
277 vma
->vm_next
->vm_flags
|= VM_ACCOUNT
;
280 if (vm_flags
& VM_LOCKED
) {
281 mm
->locked_vm
+= new_len
>> PAGE_SHIFT
;
282 if (new_len
> old_len
)
283 mlock_vma_pages_range(new_vma
, new_addr
+ old_len
,
290 static struct vm_area_struct
*vma_to_resize(unsigned long addr
,
291 unsigned long old_len
, unsigned long new_len
, unsigned long *p
)
293 struct mm_struct
*mm
= current
->mm
;
294 struct vm_area_struct
*vma
= find_vma(mm
, addr
);
296 if (!vma
|| vma
->vm_start
> addr
)
299 if (is_vm_hugetlb_page(vma
))
302 /* We can't remap across vm area boundaries */
303 if (old_len
> vma
->vm_end
- addr
)
306 /* Need to be careful about a growing mapping */
307 if (new_len
> old_len
) {
310 if (vma
->vm_flags
& (VM_DONTEXPAND
| VM_PFNMAP
))
312 pgoff
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
313 pgoff
+= vma
->vm_pgoff
;
314 if (pgoff
+ (new_len
>> PAGE_SHIFT
) < pgoff
)
318 if (vma
->vm_flags
& VM_LOCKED
) {
319 unsigned long locked
, lock_limit
;
320 locked
= mm
->locked_vm
<< PAGE_SHIFT
;
321 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
322 locked
+= new_len
- old_len
;
323 if (locked
> lock_limit
&& !capable(CAP_IPC_LOCK
))
327 if (!may_expand_vm(mm
, (new_len
- old_len
) >> PAGE_SHIFT
))
330 if (vma
->vm_flags
& VM_ACCOUNT
) {
331 unsigned long charged
= (new_len
- old_len
) >> PAGE_SHIFT
;
332 if (security_vm_enough_memory_mm(mm
, charged
))
339 Efault
: /* very odd choice for most of the cases, but... */
340 return ERR_PTR(-EFAULT
);
342 return ERR_PTR(-EINVAL
);
344 return ERR_PTR(-ENOMEM
);
346 return ERR_PTR(-EAGAIN
);
349 static unsigned long mremap_to(unsigned long addr
,
350 unsigned long old_len
, unsigned long new_addr
,
351 unsigned long new_len
)
353 struct mm_struct
*mm
= current
->mm
;
354 struct vm_area_struct
*vma
;
355 unsigned long ret
= -EINVAL
;
356 unsigned long charged
= 0;
357 unsigned long map_flags
;
359 if (new_addr
& ~PAGE_MASK
)
362 if (new_len
> TASK_SIZE
|| new_addr
> TASK_SIZE
- new_len
)
365 /* Check if the location we're moving into overlaps the
366 * old location at all, and fail if it does.
368 if ((new_addr
<= addr
) && (new_addr
+new_len
) > addr
)
371 if ((addr
<= new_addr
) && (addr
+old_len
) > new_addr
)
374 ret
= security_file_mmap(NULL
, 0, 0, 0, new_addr
, 1);
378 ret
= do_munmap(mm
, new_addr
, new_len
);
382 if (old_len
>= new_len
) {
383 ret
= do_munmap(mm
, addr
+new_len
, old_len
- new_len
);
384 if (ret
&& old_len
!= new_len
)
389 vma
= vma_to_resize(addr
, old_len
, new_len
, &charged
);
395 map_flags
= MAP_FIXED
;
396 if (vma
->vm_flags
& VM_MAYSHARE
)
397 map_flags
|= MAP_SHARED
;
399 ret
= get_unmapped_area(vma
->vm_file
, new_addr
, new_len
, vma
->vm_pgoff
+
400 ((addr
- vma
->vm_start
) >> PAGE_SHIFT
),
402 if (ret
& ~PAGE_MASK
)
405 ret
= move_vma(vma
, addr
, old_len
, new_len
, new_addr
);
406 if (!(ret
& ~PAGE_MASK
))
409 vm_unacct_memory(charged
);
415 static int vma_expandable(struct vm_area_struct
*vma
, unsigned long delta
)
417 unsigned long end
= vma
->vm_end
+ delta
;
418 if (end
< vma
->vm_end
) /* overflow */
420 if (vma
->vm_next
&& vma
->vm_next
->vm_start
< end
) /* intersection */
422 if (get_unmapped_area(NULL
, vma
->vm_start
, end
- vma
->vm_start
,
423 0, MAP_FIXED
) & ~PAGE_MASK
)
429 * Expand (or shrink) an existing mapping, potentially moving it at the
430 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
432 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
433 * This option implies MREMAP_MAYMOVE.
435 unsigned long do_mremap(unsigned long addr
,
436 unsigned long old_len
, unsigned long new_len
,
437 unsigned long flags
, unsigned long new_addr
)
439 struct mm_struct
*mm
= current
->mm
;
440 struct vm_area_struct
*vma
;
441 unsigned long ret
= -EINVAL
;
442 unsigned long charged
= 0;
444 if (flags
& ~(MREMAP_FIXED
| MREMAP_MAYMOVE
))
447 if (addr
& ~PAGE_MASK
)
450 old_len
= PAGE_ALIGN(old_len
);
451 new_len
= PAGE_ALIGN(new_len
);
454 * We allow a zero old-len as a special case
455 * for DOS-emu "duplicate shm area" thing. But
456 * a zero new-len is nonsensical.
461 if (flags
& MREMAP_FIXED
) {
462 if (flags
& MREMAP_MAYMOVE
)
463 ret
= mremap_to(addr
, old_len
, new_addr
, new_len
);
468 * Always allow a shrinking remap: that just unmaps
469 * the unnecessary pages..
470 * do_munmap does all the needed commit accounting
472 if (old_len
>= new_len
) {
473 ret
= do_munmap(mm
, addr
+new_len
, old_len
- new_len
);
474 if (ret
&& old_len
!= new_len
)
481 * Ok, we need to grow..
483 vma
= vma_to_resize(addr
, old_len
, new_len
, &charged
);
489 /* old_len exactly to the end of the area..
491 if (old_len
== vma
->vm_end
- addr
) {
492 /* can we just expand the current mapping? */
493 if (vma_expandable(vma
, new_len
- old_len
)) {
494 int pages
= (new_len
- old_len
) >> PAGE_SHIFT
;
496 if (vma_adjust(vma
, vma
->vm_start
, addr
+ new_len
,
497 vma
->vm_pgoff
, NULL
)) {
502 mm
->total_vm
+= pages
;
503 vm_stat_account(mm
, vma
->vm_flags
, vma
->vm_file
, pages
);
504 if (vma
->vm_flags
& VM_LOCKED
) {
505 mm
->locked_vm
+= pages
;
506 mlock_vma_pages_range(vma
, addr
+ old_len
,
515 * We weren't able to just expand or shrink the area,
516 * we need to create a new one and move it..
519 if (flags
& MREMAP_MAYMOVE
) {
520 unsigned long map_flags
= 0;
521 if (vma
->vm_flags
& VM_MAYSHARE
)
522 map_flags
|= MAP_SHARED
;
524 new_addr
= get_unmapped_area(vma
->vm_file
, 0, new_len
,
526 ((addr
- vma
->vm_start
) >> PAGE_SHIFT
),
528 if (new_addr
& ~PAGE_MASK
) {
533 ret
= security_file_mmap(NULL
, 0, 0, 0, new_addr
, 1);
536 ret
= move_vma(vma
, addr
, old_len
, new_len
, new_addr
);
539 if (ret
& ~PAGE_MASK
)
540 vm_unacct_memory(charged
);
544 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
545 unsigned long, new_len
, unsigned long, flags
,
546 unsigned long, new_addr
)
550 down_write(¤t
->mm
->mmap_sem
);
551 ret
= do_mremap(addr
, old_len
, new_len
, flags
, new_addr
);
552 up_write(¤t
->mm
->mmap_sem
);
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