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1/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
9
10#include <linux/mm.h>
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>
17#include <linux/fs.h>
18#include <linux/highmem.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21#include <linux/mmu_notifier.h>
22
23#include <asm/uaccess.h>
24#include <asm/cacheflush.h>
25#include <asm/tlbflush.h>
26
27#include "internal.h"
28
29static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
30{
31 pgd_t *pgd;
32 pud_t *pud;
33 pmd_t *pmd;
34
35 pgd = pgd_offset(mm, addr);
36 if (pgd_none_or_clear_bad(pgd))
37 return NULL;
38
39 pud = pud_offset(pgd, addr);
40 if (pud_none_or_clear_bad(pud))
41 return NULL;
42
43 pmd = pmd_offset(pud, addr);
44 split_huge_page_pmd(mm, pmd);
45 if (pmd_none_or_clear_bad(pmd))
46 return NULL;
47
48 return pmd;
49}
50
51static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
52 unsigned long addr)
53{
54 pgd_t *pgd;
55 pud_t *pud;
56 pmd_t *pmd;
57
58 pgd = pgd_offset(mm, addr);
59 pud = pud_alloc(mm, pgd, addr);
60 if (!pud)
61 return NULL;
62
63 pmd = pmd_alloc(mm, pud, addr);
64 if (!pmd)
65 return NULL;
66
67 VM_BUG_ON(pmd_trans_huge(*pmd));
68 if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
69 return NULL;
70
71 return pmd;
72}
73
74static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
75 unsigned long old_addr, unsigned long old_end,
76 struct vm_area_struct *new_vma, pmd_t *new_pmd,
77 unsigned long new_addr)
78{
79 struct address_space *mapping = NULL;
80 struct mm_struct *mm = vma->vm_mm;
81 pte_t *old_pte, *new_pte, pte;
82 spinlock_t *old_ptl, *new_ptl;
83 unsigned long old_start;
84
85 old_start = old_addr;
86 mmu_notifier_invalidate_range_start(vma->vm_mm,
87 old_start, old_end);
88 if (vma->vm_file) {
89 /*
90 * Subtle point from Rajesh Venkatasubramanian: before
91 * moving file-based ptes, we must lock truncate_pagecache
92 * out, since it might clean the dst vma before the src vma,
93 * and we propagate stale pages into the dst afterward.
94 */
95 mapping = vma->vm_file->f_mapping;
96 mutex_lock(&mapping->i_mmap_mutex);
97 }
98
99 /*
100 * We don't have to worry about the ordering of src and dst
101 * pte locks because exclusive mmap_sem prevents deadlock.
102 */
103 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
104 new_pte = pte_offset_map(new_pmd, new_addr);
105 new_ptl = pte_lockptr(mm, new_pmd);
106 if (new_ptl != old_ptl)
107 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
108 arch_enter_lazy_mmu_mode();
109
110 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
111 new_pte++, new_addr += PAGE_SIZE) {
112 if (pte_none(*old_pte))
113 continue;
114 pte = ptep_clear_flush(vma, old_addr, old_pte);
115 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
116 set_pte_at(mm, new_addr, new_pte, pte);
117 }
118
119 arch_leave_lazy_mmu_mode();
120 if (new_ptl != old_ptl)
121 spin_unlock(new_ptl);
122 pte_unmap(new_pte - 1);
123 pte_unmap_unlock(old_pte - 1, old_ptl);
124 if (mapping)
125 mutex_unlock(&mapping->i_mmap_mutex);
126 mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
127}
128
129#define LATENCY_LIMIT (64 * PAGE_SIZE)
130
131unsigned long move_page_tables(struct vm_area_struct *vma,
132 unsigned long old_addr, struct vm_area_struct *new_vma,
133 unsigned long new_addr, unsigned long len)
134{
135 unsigned long extent, next, old_end;
136 pmd_t *old_pmd, *new_pmd;
137
138 old_end = old_addr + len;
139 flush_cache_range(vma, old_addr, old_end);
140
141 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
142 cond_resched();
143 next = (old_addr + PMD_SIZE) & PMD_MASK;
144 if (next - 1 > old_end)
145 next = old_end;
146 extent = next - old_addr;
147 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
148 if (!old_pmd)
149 continue;
150 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
151 if (!new_pmd)
152 break;
153 next = (new_addr + PMD_SIZE) & PMD_MASK;
154 if (extent > next - new_addr)
155 extent = next - new_addr;
156 if (extent > LATENCY_LIMIT)
157 extent = LATENCY_LIMIT;
158 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
159 new_vma, new_pmd, new_addr);
160 }
161
162 return len + old_addr - old_end; /* how much done */
163}
164
165static unsigned long move_vma(struct vm_area_struct *vma,
166 unsigned long old_addr, unsigned long old_len,
167 unsigned long new_len, unsigned long new_addr)
168{
169 struct mm_struct *mm = vma->vm_mm;
170 struct vm_area_struct *new_vma;
171 unsigned long vm_flags = vma->vm_flags;
172 unsigned long new_pgoff;
173 unsigned long moved_len;
174 unsigned long excess = 0;
175 unsigned long hiwater_vm;
176 int split = 0;
177 int err;
178
179 /*
180 * We'd prefer to avoid failure later on in do_munmap:
181 * which may split one vma into three before unmapping.
182 */
183 if (mm->map_count >= sysctl_max_map_count - 3)
184 return -ENOMEM;
185
186 /*
187 * Advise KSM to break any KSM pages in the area to be moved:
188 * it would be confusing if they were to turn up at the new
189 * location, where they happen to coincide with different KSM
190 * pages recently unmapped. But leave vma->vm_flags as it was,
191 * so KSM can come around to merge on vma and new_vma afterwards.
192 */
193 err = ksm_madvise(vma, old_addr, old_addr + old_len,
194 MADV_UNMERGEABLE, &vm_flags);
195 if (err)
196 return err;
197
198 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
199 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
200 if (!new_vma)
201 return -ENOMEM;
202
203 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
204 if (moved_len < old_len) {
205 /*
206 * On error, move entries back from new area to old,
207 * which will succeed since page tables still there,
208 * and then proceed to unmap new area instead of old.
209 */
210 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
211 vma = new_vma;
212 old_len = new_len;
213 old_addr = new_addr;
214 new_addr = -ENOMEM;
215 }
216
217 /* Conceal VM_ACCOUNT so old reservation is not undone */
218 if (vm_flags & VM_ACCOUNT) {
219 vma->vm_flags &= ~VM_ACCOUNT;
220 excess = vma->vm_end - vma->vm_start - old_len;
221 if (old_addr > vma->vm_start &&
222 old_addr + old_len < vma->vm_end)
223 split = 1;
224 }
225
226 /*
227 * If we failed to move page tables we still do total_vm increment
228 * since do_munmap() will decrement it by old_len == new_len.
229 *
230 * Since total_vm is about to be raised artificially high for a
231 * moment, we need to restore high watermark afterwards: if stats
232 * are taken meanwhile, total_vm and hiwater_vm appear too high.
233 * If this were a serious issue, we'd add a flag to do_munmap().
234 */
235 hiwater_vm = mm->hiwater_vm;
236 mm->total_vm += new_len >> PAGE_SHIFT;
237 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
238
239 if (do_munmap(mm, old_addr, old_len) < 0) {
240 /* OOM: unable to split vma, just get accounts right */
241 vm_unacct_memory(excess >> PAGE_SHIFT);
242 excess = 0;
243 }
244 mm->hiwater_vm = hiwater_vm;
245
246 /* Restore VM_ACCOUNT if one or two pieces of vma left */
247 if (excess) {
248 vma->vm_flags |= VM_ACCOUNT;
249 if (split)
250 vma->vm_next->vm_flags |= VM_ACCOUNT;
251 }
252
253 if (vm_flags & VM_LOCKED) {
254 mm->locked_vm += new_len >> PAGE_SHIFT;
255 if (new_len > old_len)
256 mlock_vma_pages_range(new_vma, new_addr + old_len,
257 new_addr + new_len);
258 }
259
260 return new_addr;
261}
262
263static struct vm_area_struct *vma_to_resize(unsigned long addr,
264 unsigned long old_len, unsigned long new_len, unsigned long *p)
265{
266 struct mm_struct *mm = current->mm;
267 struct vm_area_struct *vma = find_vma(mm, addr);
268
269 if (!vma || vma->vm_start > addr)
270 goto Efault;
271
272 if (is_vm_hugetlb_page(vma))
273 goto Einval;
274
275 /* We can't remap across vm area boundaries */
276 if (old_len > vma->vm_end - addr)
277 goto Efault;
278
279 /* Need to be careful about a growing mapping */
280 if (new_len > old_len) {
281 unsigned long pgoff;
282
283 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
284 goto Efault;
285 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
286 pgoff += vma->vm_pgoff;
287 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
288 goto Einval;
289 }
290
291 if (vma->vm_flags & VM_LOCKED) {
292 unsigned long locked, lock_limit;
293 locked = mm->locked_vm << PAGE_SHIFT;
294 lock_limit = rlimit(RLIMIT_MEMLOCK);
295 locked += new_len - old_len;
296 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
297 goto Eagain;
298 }
299
300 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
301 goto Enomem;
302
303 if (vma->vm_flags & VM_ACCOUNT) {
304 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
305 if (security_vm_enough_memory(charged))
306 goto Efault;
307 *p = charged;
308 }
309
310 return vma;
311
312Efault: /* very odd choice for most of the cases, but... */
313 return ERR_PTR(-EFAULT);
314Einval:
315 return ERR_PTR(-EINVAL);
316Enomem:
317 return ERR_PTR(-ENOMEM);
318Eagain:
319 return ERR_PTR(-EAGAIN);
320}
321
322static unsigned long mremap_to(unsigned long addr,
323 unsigned long old_len, unsigned long new_addr,
324 unsigned long new_len)
325{
326 struct mm_struct *mm = current->mm;
327 struct vm_area_struct *vma;
328 unsigned long ret = -EINVAL;
329 unsigned long charged = 0;
330 unsigned long map_flags;
331
332 if (new_addr & ~PAGE_MASK)
333 goto out;
334
335 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
336 goto out;
337
338 /* Check if the location we're moving into overlaps the
339 * old location at all, and fail if it does.
340 */
341 if ((new_addr <= addr) && (new_addr+new_len) > addr)
342 goto out;
343
344 if ((addr <= new_addr) && (addr+old_len) > new_addr)
345 goto out;
346
347 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
348 if (ret)
349 goto out;
350
351 ret = do_munmap(mm, new_addr, new_len);
352 if (ret)
353 goto out;
354
355 if (old_len >= new_len) {
356 ret = do_munmap(mm, addr+new_len, old_len - new_len);
357 if (ret && old_len != new_len)
358 goto out;
359 old_len = new_len;
360 }
361
362 vma = vma_to_resize(addr, old_len, new_len, &charged);
363 if (IS_ERR(vma)) {
364 ret = PTR_ERR(vma);
365 goto out;
366 }
367
368 map_flags = MAP_FIXED;
369 if (vma->vm_flags & VM_MAYSHARE)
370 map_flags |= MAP_SHARED;
371
372 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
373 ((addr - vma->vm_start) >> PAGE_SHIFT),
374 map_flags);
375 if (ret & ~PAGE_MASK)
376 goto out1;
377
378 ret = move_vma(vma, addr, old_len, new_len, new_addr);
379 if (!(ret & ~PAGE_MASK))
380 goto out;
381out1:
382 vm_unacct_memory(charged);
383
384out:
385 return ret;
386}
387
388static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
389{
390 unsigned long end = vma->vm_end + delta;
391 if (end < vma->vm_end) /* overflow */
392 return 0;
393 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
394 return 0;
395 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
396 0, MAP_FIXED) & ~PAGE_MASK)
397 return 0;
398 return 1;
399}
400
401/*
402 * Expand (or shrink) an existing mapping, potentially moving it at the
403 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
404 *
405 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
406 * This option implies MREMAP_MAYMOVE.
407 */
408unsigned long do_mremap(unsigned long addr,
409 unsigned long old_len, unsigned long new_len,
410 unsigned long flags, unsigned long new_addr)
411{
412 struct mm_struct *mm = current->mm;
413 struct vm_area_struct *vma;
414 unsigned long ret = -EINVAL;
415 unsigned long charged = 0;
416
417 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
418 goto out;
419
420 if (addr & ~PAGE_MASK)
421 goto out;
422
423 old_len = PAGE_ALIGN(old_len);
424 new_len = PAGE_ALIGN(new_len);
425
426 /*
427 * We allow a zero old-len as a special case
428 * for DOS-emu "duplicate shm area" thing. But
429 * a zero new-len is nonsensical.
430 */
431 if (!new_len)
432 goto out;
433
434 if (flags & MREMAP_FIXED) {
435 if (flags & MREMAP_MAYMOVE)
436 ret = mremap_to(addr, old_len, new_addr, new_len);
437 goto out;
438 }
439
440 /*
441 * Always allow a shrinking remap: that just unmaps
442 * the unnecessary pages..
443 * do_munmap does all the needed commit accounting
444 */
445 if (old_len >= new_len) {
446 ret = do_munmap(mm, addr+new_len, old_len - new_len);
447 if (ret && old_len != new_len)
448 goto out;
449 ret = addr;
450 goto out;
451 }
452
453 /*
454 * Ok, we need to grow..
455 */
456 vma = vma_to_resize(addr, old_len, new_len, &charged);
457 if (IS_ERR(vma)) {
458 ret = PTR_ERR(vma);
459 goto out;
460 }
461
462 /* old_len exactly to the end of the area..
463 */
464 if (old_len == vma->vm_end - addr) {
465 /* can we just expand the current mapping? */
466 if (vma_expandable(vma, new_len - old_len)) {
467 int pages = (new_len - old_len) >> PAGE_SHIFT;
468
469 if (vma_adjust(vma, vma->vm_start, addr + new_len,
470 vma->vm_pgoff, NULL)) {
471 ret = -ENOMEM;
472 goto out;
473 }
474
475 mm->total_vm += pages;
476 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
477 if (vma->vm_flags & VM_LOCKED) {
478 mm->locked_vm += pages;
479 mlock_vma_pages_range(vma, addr + old_len,
480 addr + new_len);
481 }
482 ret = addr;
483 goto out;
484 }
485 }
486
487 /*
488 * We weren't able to just expand or shrink the area,
489 * we need to create a new one and move it..
490 */
491 ret = -ENOMEM;
492 if (flags & MREMAP_MAYMOVE) {
493 unsigned long map_flags = 0;
494 if (vma->vm_flags & VM_MAYSHARE)
495 map_flags |= MAP_SHARED;
496
497 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
498 vma->vm_pgoff +
499 ((addr - vma->vm_start) >> PAGE_SHIFT),
500 map_flags);
501 if (new_addr & ~PAGE_MASK) {
502 ret = new_addr;
503 goto out;
504 }
505
506 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
507 if (ret)
508 goto out;
509 ret = move_vma(vma, addr, old_len, new_len, new_addr);
510 }
511out:
512 if (ret & ~PAGE_MASK)
513 vm_unacct_memory(charged);
514 return ret;
515}
516
517SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
518 unsigned long, new_len, unsigned long, flags,
519 unsigned long, new_addr)
520{
521 unsigned long ret;
522
523 down_write(¤t->mm->mmap_sem);
524 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
525 up_write(¤t->mm->mmap_sem);
526 return ret;
527}
1/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
9
10#include <linux/mm.h>
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>
17#include <linux/fs.h>
18#include <linux/highmem.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21#include <linux/mmu_notifier.h>
22
23#include <asm/uaccess.h>
24#include <asm/cacheflush.h>
25#include <asm/tlbflush.h>
26
27#include "internal.h"
28
29static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
30{
31 pgd_t *pgd;
32 pud_t *pud;
33 pmd_t *pmd;
34
35 pgd = pgd_offset(mm, addr);
36 if (pgd_none_or_clear_bad(pgd))
37 return NULL;
38
39 pud = pud_offset(pgd, addr);
40 if (pud_none_or_clear_bad(pud))
41 return NULL;
42
43 pmd = pmd_offset(pud, addr);
44 if (pmd_none(*pmd))
45 return NULL;
46
47 return pmd;
48}
49
50static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
51 unsigned long addr)
52{
53 pgd_t *pgd;
54 pud_t *pud;
55 pmd_t *pmd;
56
57 pgd = pgd_offset(mm, addr);
58 pud = pud_alloc(mm, pgd, addr);
59 if (!pud)
60 return NULL;
61
62 pmd = pmd_alloc(mm, pud, addr);
63 if (!pmd)
64 return NULL;
65
66 VM_BUG_ON(pmd_trans_huge(*pmd));
67
68 return pmd;
69}
70
71static 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)
75{
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;
80
81 if (vma->vm_file) {
82 /*
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.
87 */
88 mapping = vma->vm_file->f_mapping;
89 mutex_lock(&mapping->i_mmap_mutex);
90 }
91
92 /*
93 * We don't have to worry about the ordering of src and dst
94 * pte locks because exclusive mmap_sem prevents deadlock.
95 */
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();
102
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))
106 continue;
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);
110 }
111
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);
117 if (mapping)
118 mutex_unlock(&mapping->i_mmap_mutex);
119}
120
121#define LATENCY_LIMIT (64 * PAGE_SIZE)
122
123unsigned 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)
126{
127 unsigned long extent, next, old_end;
128 pmd_t *old_pmd, *new_pmd;
129 bool need_flush = false;
130
131 old_end = old_addr + len;
132 flush_cache_range(vma, old_addr, old_end);
133
134 mmu_notifier_invalidate_range_start(vma->vm_mm, old_addr, old_end);
135
136 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
137 cond_resched();
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);
144 if (!old_pmd)
145 continue;
146 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
147 if (!new_pmd)
148 break;
149 if (pmd_trans_huge(*old_pmd)) {
150 int err = 0;
151 if (extent == HPAGE_PMD_SIZE)
152 err = move_huge_pmd(vma, new_vma, old_addr,
153 new_addr, old_end,
154 old_pmd, new_pmd);
155 if (err > 0) {
156 need_flush = true;
157 continue;
158 } else if (!err) {
159 split_huge_page_pmd(vma->vm_mm, old_pmd);
160 }
161 VM_BUG_ON(pmd_trans_huge(*old_pmd));
162 }
163 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
164 new_pmd, new_addr))
165 break;
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);
173 need_flush = true;
174 }
175 if (likely(need_flush))
176 flush_tlb_range(vma, old_end-len, old_addr);
177
178 mmu_notifier_invalidate_range_end(vma->vm_mm, old_end-len, old_end);
179
180 return len + old_addr - old_end; /* how much done */
181}
182
183static 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)
186{
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;
194 int split = 0;
195 int err;
196
197 /*
198 * We'd prefer to avoid failure later on in do_munmap:
199 * which may split one vma into three before unmapping.
200 */
201 if (mm->map_count >= sysctl_max_map_count - 3)
202 return -ENOMEM;
203
204 /*
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.
210 */
211 err = ksm_madvise(vma, old_addr, old_addr + old_len,
212 MADV_UNMERGEABLE, &vm_flags);
213 if (err)
214 return err;
215
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);
218 if (!new_vma)
219 return -ENOMEM;
220
221 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
222 if (moved_len < old_len) {
223 /*
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).
229 */
230 anon_vma_moveto_tail(vma);
231
232 /*
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.
236 */
237 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
238 vma = new_vma;
239 old_len = new_len;
240 old_addr = new_addr;
241 new_addr = -ENOMEM;
242 }
243
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)
250 split = 1;
251 }
252
253 /*
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.
256 *
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().
261 */
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);
265
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);
269 excess = 0;
270 }
271 mm->hiwater_vm = hiwater_vm;
272
273 /* Restore VM_ACCOUNT if one or two pieces of vma left */
274 if (excess) {
275 vma->vm_flags |= VM_ACCOUNT;
276 if (split)
277 vma->vm_next->vm_flags |= VM_ACCOUNT;
278 }
279
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,
284 new_addr + new_len);
285 }
286
287 return new_addr;
288}
289
290static struct vm_area_struct *vma_to_resize(unsigned long addr,
291 unsigned long old_len, unsigned long new_len, unsigned long *p)
292{
293 struct mm_struct *mm = current->mm;
294 struct vm_area_struct *vma = find_vma(mm, addr);
295
296 if (!vma || vma->vm_start > addr)
297 goto Efault;
298
299 if (is_vm_hugetlb_page(vma))
300 goto Einval;
301
302 /* We can't remap across vm area boundaries */
303 if (old_len > vma->vm_end - addr)
304 goto Efault;
305
306 /* Need to be careful about a growing mapping */
307 if (new_len > old_len) {
308 unsigned long pgoff;
309
310 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
311 goto Efault;
312 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
313 pgoff += vma->vm_pgoff;
314 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
315 goto Einval;
316 }
317
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))
324 goto Eagain;
325 }
326
327 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
328 goto Enomem;
329
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))
333 goto Efault;
334 *p = charged;
335 }
336
337 return vma;
338
339Efault: /* very odd choice for most of the cases, but... */
340 return ERR_PTR(-EFAULT);
341Einval:
342 return ERR_PTR(-EINVAL);
343Enomem:
344 return ERR_PTR(-ENOMEM);
345Eagain:
346 return ERR_PTR(-EAGAIN);
347}
348
349static unsigned long mremap_to(unsigned long addr,
350 unsigned long old_len, unsigned long new_addr,
351 unsigned long new_len)
352{
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;
358
359 if (new_addr & ~PAGE_MASK)
360 goto out;
361
362 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
363 goto out;
364
365 /* Check if the location we're moving into overlaps the
366 * old location at all, and fail if it does.
367 */
368 if ((new_addr <= addr) && (new_addr+new_len) > addr)
369 goto out;
370
371 if ((addr <= new_addr) && (addr+old_len) > new_addr)
372 goto out;
373
374 ret = do_munmap(mm, new_addr, new_len);
375 if (ret)
376 goto out;
377
378 if (old_len >= new_len) {
379 ret = do_munmap(mm, addr+new_len, old_len - new_len);
380 if (ret && old_len != new_len)
381 goto out;
382 old_len = new_len;
383 }
384
385 vma = vma_to_resize(addr, old_len, new_len, &charged);
386 if (IS_ERR(vma)) {
387 ret = PTR_ERR(vma);
388 goto out;
389 }
390
391 map_flags = MAP_FIXED;
392 if (vma->vm_flags & VM_MAYSHARE)
393 map_flags |= MAP_SHARED;
394
395 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
396 ((addr - vma->vm_start) >> PAGE_SHIFT),
397 map_flags);
398 if (ret & ~PAGE_MASK)
399 goto out1;
400
401 ret = move_vma(vma, addr, old_len, new_len, new_addr);
402 if (!(ret & ~PAGE_MASK))
403 goto out;
404out1:
405 vm_unacct_memory(charged);
406
407out:
408 return ret;
409}
410
411static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
412{
413 unsigned long end = vma->vm_end + delta;
414 if (end < vma->vm_end) /* overflow */
415 return 0;
416 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
417 return 0;
418 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
419 0, MAP_FIXED) & ~PAGE_MASK)
420 return 0;
421 return 1;
422}
423
424/*
425 * Expand (or shrink) an existing mapping, potentially moving it at the
426 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
427 *
428 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
429 * This option implies MREMAP_MAYMOVE.
430 */
431SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
432 unsigned long, new_len, unsigned long, flags,
433 unsigned long, new_addr)
434{
435 struct mm_struct *mm = current->mm;
436 struct vm_area_struct *vma;
437 unsigned long ret = -EINVAL;
438 unsigned long charged = 0;
439
440 down_write(¤t->mm->mmap_sem);
441
442 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
443 goto out;
444
445 if (addr & ~PAGE_MASK)
446 goto out;
447
448 old_len = PAGE_ALIGN(old_len);
449 new_len = PAGE_ALIGN(new_len);
450
451 /*
452 * We allow a zero old-len as a special case
453 * for DOS-emu "duplicate shm area" thing. But
454 * a zero new-len is nonsensical.
455 */
456 if (!new_len)
457 goto out;
458
459 if (flags & MREMAP_FIXED) {
460 if (flags & MREMAP_MAYMOVE)
461 ret = mremap_to(addr, old_len, new_addr, new_len);
462 goto out;
463 }
464
465 /*
466 * Always allow a shrinking remap: that just unmaps
467 * the unnecessary pages..
468 * do_munmap does all the needed commit accounting
469 */
470 if (old_len >= new_len) {
471 ret = do_munmap(mm, addr+new_len, old_len - new_len);
472 if (ret && old_len != new_len)
473 goto out;
474 ret = addr;
475 goto out;
476 }
477
478 /*
479 * Ok, we need to grow..
480 */
481 vma = vma_to_resize(addr, old_len, new_len, &charged);
482 if (IS_ERR(vma)) {
483 ret = PTR_ERR(vma);
484 goto out;
485 }
486
487 /* old_len exactly to the end of the area..
488 */
489 if (old_len == vma->vm_end - addr) {
490 /* can we just expand the current mapping? */
491 if (vma_expandable(vma, new_len - old_len)) {
492 int pages = (new_len - old_len) >> PAGE_SHIFT;
493
494 if (vma_adjust(vma, vma->vm_start, addr + new_len,
495 vma->vm_pgoff, NULL)) {
496 ret = -ENOMEM;
497 goto out;
498 }
499
500 mm->total_vm += pages;
501 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
502 if (vma->vm_flags & VM_LOCKED) {
503 mm->locked_vm += pages;
504 mlock_vma_pages_range(vma, addr + old_len,
505 addr + new_len);
506 }
507 ret = addr;
508 goto out;
509 }
510 }
511
512 /*
513 * We weren't able to just expand or shrink the area,
514 * we need to create a new one and move it..
515 */
516 ret = -ENOMEM;
517 if (flags & MREMAP_MAYMOVE) {
518 unsigned long map_flags = 0;
519 if (vma->vm_flags & VM_MAYSHARE)
520 map_flags |= MAP_SHARED;
521
522 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
523 vma->vm_pgoff +
524 ((addr - vma->vm_start) >> PAGE_SHIFT),
525 map_flags);
526 if (new_addr & ~PAGE_MASK) {
527 ret = new_addr;
528 goto out;
529 }
530
531 ret = move_vma(vma, addr, old_len, new_len, new_addr);
532 }
533out:
534 if (ret & ~PAGE_MASK)
535 vm_unacct_memory(charged);
536 up_write(¤t->mm->mmap_sem);
537 return ret;
538}