Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * mm/mremap.c | |
3 | * | |
4 | * (C) Copyright 1996 Linus Torvalds | |
5 | * | |
046c6884 | 6 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
1da177e4 LT |
7 | * (C) Copyright 2002 Red Hat Inc, All Rights Reserved |
8 | */ | |
9 | ||
10 | #include <linux/mm.h> | |
11 | #include <linux/hugetlb.h> | |
1da177e4 | 12 | #include <linux/shm.h> |
1ff82995 | 13 | #include <linux/ksm.h> |
1da177e4 LT |
14 | #include <linux/mman.h> |
15 | #include <linux/swap.h> | |
c59ede7b | 16 | #include <linux/capability.h> |
1da177e4 LT |
17 | #include <linux/fs.h> |
18 | #include <linux/highmem.h> | |
19 | #include <linux/security.h> | |
20 | #include <linux/syscalls.h> | |
cddb8a5c | 21 | #include <linux/mmu_notifier.h> |
cf4aebc2 | 22 | #include <linux/sched/sysctl.h> |
1da177e4 LT |
23 | |
24 | #include <asm/uaccess.h> | |
25 | #include <asm/cacheflush.h> | |
26 | #include <asm/tlbflush.h> | |
27 | ||
ba470de4 RR |
28 | #include "internal.h" |
29 | ||
7be7a546 | 30 | static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
31 | { |
32 | pgd_t *pgd; | |
33 | pud_t *pud; | |
34 | pmd_t *pmd; | |
35 | ||
36 | pgd = pgd_offset(mm, addr); | |
37 | if (pgd_none_or_clear_bad(pgd)) | |
38 | return NULL; | |
39 | ||
40 | pud = pud_offset(pgd, addr); | |
41 | if (pud_none_or_clear_bad(pud)) | |
42 | return NULL; | |
43 | ||
44 | pmd = pmd_offset(pud, addr); | |
37a1c49a | 45 | if (pmd_none(*pmd)) |
1da177e4 LT |
46 | return NULL; |
47 | ||
7be7a546 | 48 | return pmd; |
1da177e4 LT |
49 | } |
50 | ||
8ac1f832 AA |
51 | static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma, |
52 | unsigned long addr) | |
1da177e4 LT |
53 | { |
54 | pgd_t *pgd; | |
55 | pud_t *pud; | |
c74df32c | 56 | pmd_t *pmd; |
1da177e4 LT |
57 | |
58 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
59 | pud = pud_alloc(mm, pgd, addr); |
60 | if (!pud) | |
c74df32c | 61 | return NULL; |
7be7a546 | 62 | |
1da177e4 | 63 | pmd = pmd_alloc(mm, pud, addr); |
7be7a546 | 64 | if (!pmd) |
c74df32c | 65 | return NULL; |
7be7a546 | 66 | |
8ac1f832 | 67 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
c74df32c | 68 | |
7be7a546 | 69 | return pmd; |
1da177e4 LT |
70 | } |
71 | ||
7be7a546 HD |
72 | static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, |
73 | unsigned long old_addr, unsigned long old_end, | |
74 | struct vm_area_struct *new_vma, pmd_t *new_pmd, | |
38a76013 | 75 | unsigned long new_addr, bool need_rmap_locks) |
1da177e4 LT |
76 | { |
77 | struct address_space *mapping = NULL; | |
38a76013 | 78 | struct anon_vma *anon_vma = NULL; |
1da177e4 | 79 | struct mm_struct *mm = vma->vm_mm; |
7be7a546 | 80 | pte_t *old_pte, *new_pte, pte; |
4c21e2f2 | 81 | spinlock_t *old_ptl, *new_ptl; |
1da177e4 | 82 | |
38a76013 ML |
83 | /* |
84 | * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma | |
85 | * locks to ensure that rmap will always observe either the old or the | |
86 | * new ptes. This is the easiest way to avoid races with | |
87 | * truncate_pagecache(), page migration, etc... | |
88 | * | |
89 | * When need_rmap_locks is false, we use other ways to avoid | |
90 | * such races: | |
91 | * | |
92 | * - During exec() shift_arg_pages(), we use a specially tagged vma | |
93 | * which rmap call sites look for using is_vma_temporary_stack(). | |
94 | * | |
95 | * - During mremap(), new_vma is often known to be placed after vma | |
96 | * in rmap traversal order. This ensures rmap will always observe | |
97 | * either the old pte, or the new pte, or both (the page table locks | |
98 | * serialize access to individual ptes, but only rmap traversal | |
99 | * order guarantees that we won't miss both the old and new ptes). | |
100 | */ | |
101 | if (need_rmap_locks) { | |
102 | if (vma->vm_file) { | |
103 | mapping = vma->vm_file->f_mapping; | |
104 | mutex_lock(&mapping->i_mmap_mutex); | |
105 | } | |
106 | if (vma->anon_vma) { | |
107 | anon_vma = vma->anon_vma; | |
4fc3f1d6 | 108 | anon_vma_lock_write(anon_vma); |
38a76013 | 109 | } |
1da177e4 | 110 | } |
1da177e4 | 111 | |
4c21e2f2 HD |
112 | /* |
113 | * We don't have to worry about the ordering of src and dst | |
114 | * pte locks because exclusive mmap_sem prevents deadlock. | |
115 | */ | |
c74df32c | 116 | old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); |
ece0e2b6 | 117 | new_pte = pte_offset_map(new_pmd, new_addr); |
4c21e2f2 HD |
118 | new_ptl = pte_lockptr(mm, new_pmd); |
119 | if (new_ptl != old_ptl) | |
f20dc5f7 | 120 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); |
6606c3e0 | 121 | arch_enter_lazy_mmu_mode(); |
7be7a546 HD |
122 | |
123 | for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, | |
124 | new_pte++, new_addr += PAGE_SIZE) { | |
125 | if (pte_none(*old_pte)) | |
126 | continue; | |
7b6efc2b | 127 | pte = ptep_get_and_clear(mm, old_addr, old_pte); |
7be7a546 HD |
128 | pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); |
129 | set_pte_at(mm, new_addr, new_pte, pte); | |
1da177e4 | 130 | } |
7be7a546 | 131 | |
6606c3e0 | 132 | arch_leave_lazy_mmu_mode(); |
4c21e2f2 HD |
133 | if (new_ptl != old_ptl) |
134 | spin_unlock(new_ptl); | |
ece0e2b6 | 135 | pte_unmap(new_pte - 1); |
c74df32c | 136 | pte_unmap_unlock(old_pte - 1, old_ptl); |
108d6642 | 137 | if (anon_vma) |
08b52706 | 138 | anon_vma_unlock_write(anon_vma); |
1da177e4 | 139 | if (mapping) |
3d48ae45 | 140 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
141 | } |
142 | ||
7be7a546 HD |
143 | #define LATENCY_LIMIT (64 * PAGE_SIZE) |
144 | ||
b6a2fea3 | 145 | unsigned long move_page_tables(struct vm_area_struct *vma, |
1da177e4 | 146 | unsigned long old_addr, struct vm_area_struct *new_vma, |
38a76013 ML |
147 | unsigned long new_addr, unsigned long len, |
148 | bool need_rmap_locks) | |
1da177e4 | 149 | { |
7be7a546 HD |
150 | unsigned long extent, next, old_end; |
151 | pmd_t *old_pmd, *new_pmd; | |
7b6efc2b | 152 | bool need_flush = false; |
2ec74c3e SG |
153 | unsigned long mmun_start; /* For mmu_notifiers */ |
154 | unsigned long mmun_end; /* For mmu_notifiers */ | |
1da177e4 | 155 | |
7be7a546 HD |
156 | old_end = old_addr + len; |
157 | flush_cache_range(vma, old_addr, old_end); | |
1da177e4 | 158 | |
2ec74c3e SG |
159 | mmun_start = old_addr; |
160 | mmun_end = old_end; | |
161 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); | |
7b6efc2b | 162 | |
7be7a546 | 163 | for (; old_addr < old_end; old_addr += extent, new_addr += extent) { |
1da177e4 | 164 | cond_resched(); |
7be7a546 | 165 | next = (old_addr + PMD_SIZE) & PMD_MASK; |
ebed4846 | 166 | /* even if next overflowed, extent below will be ok */ |
7be7a546 | 167 | extent = next - old_addr; |
ebed4846 AA |
168 | if (extent > old_end - old_addr) |
169 | extent = old_end - old_addr; | |
7be7a546 HD |
170 | old_pmd = get_old_pmd(vma->vm_mm, old_addr); |
171 | if (!old_pmd) | |
172 | continue; | |
8ac1f832 | 173 | new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr); |
7be7a546 HD |
174 | if (!new_pmd) |
175 | break; | |
37a1c49a AA |
176 | if (pmd_trans_huge(*old_pmd)) { |
177 | int err = 0; | |
61913112 KS |
178 | if (extent == HPAGE_PMD_SIZE) { |
179 | VM_BUG_ON(vma->vm_file || !vma->anon_vma); | |
180 | /* See comment in move_ptes() */ | |
181 | if (need_rmap_locks) | |
182 | anon_vma_lock_write(vma->anon_vma); | |
37a1c49a AA |
183 | err = move_huge_pmd(vma, new_vma, old_addr, |
184 | new_addr, old_end, | |
185 | old_pmd, new_pmd); | |
61913112 KS |
186 | if (need_rmap_locks) |
187 | anon_vma_unlock_write(vma->anon_vma); | |
188 | } | |
37a1c49a AA |
189 | if (err > 0) { |
190 | need_flush = true; | |
191 | continue; | |
192 | } else if (!err) { | |
e180377f | 193 | split_huge_page_pmd(vma, old_addr, old_pmd); |
37a1c49a AA |
194 | } |
195 | VM_BUG_ON(pmd_trans_huge(*old_pmd)); | |
196 | } | |
197 | if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma, | |
198 | new_pmd, new_addr)) | |
199 | break; | |
7be7a546 HD |
200 | next = (new_addr + PMD_SIZE) & PMD_MASK; |
201 | if (extent > next - new_addr) | |
202 | extent = next - new_addr; | |
203 | if (extent > LATENCY_LIMIT) | |
204 | extent = LATENCY_LIMIT; | |
205 | move_ptes(vma, old_pmd, old_addr, old_addr + extent, | |
38a76013 | 206 | new_vma, new_pmd, new_addr, need_rmap_locks); |
7b6efc2b | 207 | need_flush = true; |
1da177e4 | 208 | } |
7b6efc2b AA |
209 | if (likely(need_flush)) |
210 | flush_tlb_range(vma, old_end-len, old_addr); | |
211 | ||
2ec74c3e | 212 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
7be7a546 HD |
213 | |
214 | return len + old_addr - old_end; /* how much done */ | |
1da177e4 LT |
215 | } |
216 | ||
217 | static unsigned long move_vma(struct vm_area_struct *vma, | |
218 | unsigned long old_addr, unsigned long old_len, | |
81909b84 | 219 | unsigned long new_len, unsigned long new_addr, bool *locked) |
1da177e4 LT |
220 | { |
221 | struct mm_struct *mm = vma->vm_mm; | |
222 | struct vm_area_struct *new_vma; | |
223 | unsigned long vm_flags = vma->vm_flags; | |
224 | unsigned long new_pgoff; | |
225 | unsigned long moved_len; | |
226 | unsigned long excess = 0; | |
365e9c87 | 227 | unsigned long hiwater_vm; |
1da177e4 | 228 | int split = 0; |
7103ad32 | 229 | int err; |
38a76013 | 230 | bool need_rmap_locks; |
1da177e4 LT |
231 | |
232 | /* | |
233 | * We'd prefer to avoid failure later on in do_munmap: | |
234 | * which may split one vma into three before unmapping. | |
235 | */ | |
236 | if (mm->map_count >= sysctl_max_map_count - 3) | |
237 | return -ENOMEM; | |
238 | ||
1ff82995 HD |
239 | /* |
240 | * Advise KSM to break any KSM pages in the area to be moved: | |
241 | * it would be confusing if they were to turn up at the new | |
242 | * location, where they happen to coincide with different KSM | |
243 | * pages recently unmapped. But leave vma->vm_flags as it was, | |
244 | * so KSM can come around to merge on vma and new_vma afterwards. | |
245 | */ | |
7103ad32 HD |
246 | err = ksm_madvise(vma, old_addr, old_addr + old_len, |
247 | MADV_UNMERGEABLE, &vm_flags); | |
248 | if (err) | |
249 | return err; | |
1ff82995 | 250 | |
1da177e4 | 251 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); |
38a76013 ML |
252 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff, |
253 | &need_rmap_locks); | |
1da177e4 LT |
254 | if (!new_vma) |
255 | return -ENOMEM; | |
256 | ||
38a76013 ML |
257 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len, |
258 | need_rmap_locks); | |
1da177e4 LT |
259 | if (moved_len < old_len) { |
260 | /* | |
261 | * On error, move entries back from new area to old, | |
262 | * which will succeed since page tables still there, | |
263 | * and then proceed to unmap new area instead of old. | |
264 | */ | |
38a76013 ML |
265 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len, |
266 | true); | |
1da177e4 LT |
267 | vma = new_vma; |
268 | old_len = new_len; | |
269 | old_addr = new_addr; | |
270 | new_addr = -ENOMEM; | |
271 | } | |
272 | ||
273 | /* Conceal VM_ACCOUNT so old reservation is not undone */ | |
274 | if (vm_flags & VM_ACCOUNT) { | |
275 | vma->vm_flags &= ~VM_ACCOUNT; | |
276 | excess = vma->vm_end - vma->vm_start - old_len; | |
277 | if (old_addr > vma->vm_start && | |
278 | old_addr + old_len < vma->vm_end) | |
279 | split = 1; | |
280 | } | |
281 | ||
71799062 | 282 | /* |
365e9c87 HD |
283 | * If we failed to move page tables we still do total_vm increment |
284 | * since do_munmap() will decrement it by old_len == new_len. | |
285 | * | |
286 | * Since total_vm is about to be raised artificially high for a | |
287 | * moment, we need to restore high watermark afterwards: if stats | |
288 | * are taken meanwhile, total_vm and hiwater_vm appear too high. | |
289 | * If this were a serious issue, we'd add a flag to do_munmap(). | |
71799062 | 290 | */ |
365e9c87 | 291 | hiwater_vm = mm->hiwater_vm; |
ab50b8ed | 292 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
71799062 | 293 | |
1da177e4 LT |
294 | if (do_munmap(mm, old_addr, old_len) < 0) { |
295 | /* OOM: unable to split vma, just get accounts right */ | |
296 | vm_unacct_memory(excess >> PAGE_SHIFT); | |
297 | excess = 0; | |
298 | } | |
365e9c87 | 299 | mm->hiwater_vm = hiwater_vm; |
1da177e4 LT |
300 | |
301 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ | |
302 | if (excess) { | |
303 | vma->vm_flags |= VM_ACCOUNT; | |
304 | if (split) | |
305 | vma->vm_next->vm_flags |= VM_ACCOUNT; | |
306 | } | |
307 | ||
1da177e4 LT |
308 | if (vm_flags & VM_LOCKED) { |
309 | mm->locked_vm += new_len >> PAGE_SHIFT; | |
81909b84 | 310 | *locked = true; |
1da177e4 LT |
311 | } |
312 | ||
313 | return new_addr; | |
314 | } | |
315 | ||
54f5de70 AV |
316 | static struct vm_area_struct *vma_to_resize(unsigned long addr, |
317 | unsigned long old_len, unsigned long new_len, unsigned long *p) | |
318 | { | |
319 | struct mm_struct *mm = current->mm; | |
320 | struct vm_area_struct *vma = find_vma(mm, addr); | |
321 | ||
322 | if (!vma || vma->vm_start > addr) | |
323 | goto Efault; | |
324 | ||
325 | if (is_vm_hugetlb_page(vma)) | |
326 | goto Einval; | |
327 | ||
328 | /* We can't remap across vm area boundaries */ | |
329 | if (old_len > vma->vm_end - addr) | |
330 | goto Efault; | |
331 | ||
982134ba LT |
332 | /* Need to be careful about a growing mapping */ |
333 | if (new_len > old_len) { | |
334 | unsigned long pgoff; | |
335 | ||
336 | if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) | |
54f5de70 | 337 | goto Efault; |
982134ba LT |
338 | pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; |
339 | pgoff += vma->vm_pgoff; | |
340 | if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) | |
341 | goto Einval; | |
54f5de70 AV |
342 | } |
343 | ||
344 | if (vma->vm_flags & VM_LOCKED) { | |
345 | unsigned long locked, lock_limit; | |
346 | locked = mm->locked_vm << PAGE_SHIFT; | |
59e99e5b | 347 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
54f5de70 AV |
348 | locked += new_len - old_len; |
349 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
350 | goto Eagain; | |
351 | } | |
352 | ||
353 | if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) | |
354 | goto Enomem; | |
355 | ||
356 | if (vma->vm_flags & VM_ACCOUNT) { | |
357 | unsigned long charged = (new_len - old_len) >> PAGE_SHIFT; | |
191c5424 | 358 | if (security_vm_enough_memory_mm(mm, charged)) |
54f5de70 AV |
359 | goto Efault; |
360 | *p = charged; | |
361 | } | |
362 | ||
363 | return vma; | |
364 | ||
365 | Efault: /* very odd choice for most of the cases, but... */ | |
366 | return ERR_PTR(-EFAULT); | |
367 | Einval: | |
368 | return ERR_PTR(-EINVAL); | |
369 | Enomem: | |
370 | return ERR_PTR(-ENOMEM); | |
371 | Eagain: | |
372 | return ERR_PTR(-EAGAIN); | |
373 | } | |
374 | ||
81909b84 ML |
375 | static unsigned long mremap_to(unsigned long addr, unsigned long old_len, |
376 | unsigned long new_addr, unsigned long new_len, bool *locked) | |
ecc1a899 AV |
377 | { |
378 | struct mm_struct *mm = current->mm; | |
379 | struct vm_area_struct *vma; | |
380 | unsigned long ret = -EINVAL; | |
381 | unsigned long charged = 0; | |
097eed10 | 382 | unsigned long map_flags; |
ecc1a899 AV |
383 | |
384 | if (new_addr & ~PAGE_MASK) | |
385 | goto out; | |
386 | ||
387 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) | |
388 | goto out; | |
389 | ||
390 | /* Check if the location we're moving into overlaps the | |
391 | * old location at all, and fail if it does. | |
392 | */ | |
393 | if ((new_addr <= addr) && (new_addr+new_len) > addr) | |
394 | goto out; | |
395 | ||
396 | if ((addr <= new_addr) && (addr+old_len) > new_addr) | |
397 | goto out; | |
398 | ||
ecc1a899 AV |
399 | ret = do_munmap(mm, new_addr, new_len); |
400 | if (ret) | |
401 | goto out; | |
402 | ||
403 | if (old_len >= new_len) { | |
404 | ret = do_munmap(mm, addr+new_len, old_len - new_len); | |
405 | if (ret && old_len != new_len) | |
406 | goto out; | |
407 | old_len = new_len; | |
408 | } | |
409 | ||
410 | vma = vma_to_resize(addr, old_len, new_len, &charged); | |
411 | if (IS_ERR(vma)) { | |
412 | ret = PTR_ERR(vma); | |
413 | goto out; | |
414 | } | |
415 | ||
097eed10 AV |
416 | map_flags = MAP_FIXED; |
417 | if (vma->vm_flags & VM_MAYSHARE) | |
418 | map_flags |= MAP_SHARED; | |
9206de95 | 419 | |
097eed10 AV |
420 | ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + |
421 | ((addr - vma->vm_start) >> PAGE_SHIFT), | |
422 | map_flags); | |
ecc1a899 | 423 | if (ret & ~PAGE_MASK) |
097eed10 AV |
424 | goto out1; |
425 | ||
81909b84 | 426 | ret = move_vma(vma, addr, old_len, new_len, new_addr, locked); |
097eed10 AV |
427 | if (!(ret & ~PAGE_MASK)) |
428 | goto out; | |
429 | out1: | |
430 | vm_unacct_memory(charged); | |
ecc1a899 AV |
431 | |
432 | out: | |
433 | return ret; | |
434 | } | |
435 | ||
1a0ef85f AV |
436 | static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) |
437 | { | |
f106af4e | 438 | unsigned long end = vma->vm_end + delta; |
9206de95 | 439 | if (end < vma->vm_end) /* overflow */ |
f106af4e | 440 | return 0; |
9206de95 | 441 | if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */ |
f106af4e AV |
442 | return 0; |
443 | if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start, | |
444 | 0, MAP_FIXED) & ~PAGE_MASK) | |
1a0ef85f | 445 | return 0; |
1a0ef85f AV |
446 | return 1; |
447 | } | |
448 | ||
1da177e4 LT |
449 | /* |
450 | * Expand (or shrink) an existing mapping, potentially moving it at the | |
451 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) | |
452 | * | |
453 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise | |
454 | * This option implies MREMAP_MAYMOVE. | |
455 | */ | |
63a81db1 AV |
456 | SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
457 | unsigned long, new_len, unsigned long, flags, | |
458 | unsigned long, new_addr) | |
1da177e4 | 459 | { |
d0de32d9 | 460 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
461 | struct vm_area_struct *vma; |
462 | unsigned long ret = -EINVAL; | |
463 | unsigned long charged = 0; | |
81909b84 | 464 | bool locked = false; |
1da177e4 | 465 | |
63a81db1 AV |
466 | down_write(¤t->mm->mmap_sem); |
467 | ||
1da177e4 LT |
468 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) |
469 | goto out; | |
470 | ||
471 | if (addr & ~PAGE_MASK) | |
472 | goto out; | |
473 | ||
474 | old_len = PAGE_ALIGN(old_len); | |
475 | new_len = PAGE_ALIGN(new_len); | |
476 | ||
477 | /* | |
478 | * We allow a zero old-len as a special case | |
479 | * for DOS-emu "duplicate shm area" thing. But | |
480 | * a zero new-len is nonsensical. | |
481 | */ | |
482 | if (!new_len) | |
483 | goto out; | |
484 | ||
1da177e4 | 485 | if (flags & MREMAP_FIXED) { |
ecc1a899 | 486 | if (flags & MREMAP_MAYMOVE) |
81909b84 ML |
487 | ret = mremap_to(addr, old_len, new_addr, new_len, |
488 | &locked); | |
ecc1a899 | 489 | goto out; |
1da177e4 LT |
490 | } |
491 | ||
492 | /* | |
493 | * Always allow a shrinking remap: that just unmaps | |
494 | * the unnecessary pages.. | |
495 | * do_munmap does all the needed commit accounting | |
496 | */ | |
497 | if (old_len >= new_len) { | |
d0de32d9 | 498 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
1da177e4 LT |
499 | if (ret && old_len != new_len) |
500 | goto out; | |
501 | ret = addr; | |
ecc1a899 | 502 | goto out; |
1da177e4 LT |
503 | } |
504 | ||
505 | /* | |
ecc1a899 | 506 | * Ok, we need to grow.. |
1da177e4 | 507 | */ |
54f5de70 AV |
508 | vma = vma_to_resize(addr, old_len, new_len, &charged); |
509 | if (IS_ERR(vma)) { | |
510 | ret = PTR_ERR(vma); | |
1da177e4 | 511 | goto out; |
119f657c | 512 | } |
1da177e4 | 513 | |
1da177e4 | 514 | /* old_len exactly to the end of the area.. |
1da177e4 | 515 | */ |
ecc1a899 | 516 | if (old_len == vma->vm_end - addr) { |
1da177e4 | 517 | /* can we just expand the current mapping? */ |
1a0ef85f | 518 | if (vma_expandable(vma, new_len - old_len)) { |
1da177e4 LT |
519 | int pages = (new_len - old_len) >> PAGE_SHIFT; |
520 | ||
5beb4930 RR |
521 | if (vma_adjust(vma, vma->vm_start, addr + new_len, |
522 | vma->vm_pgoff, NULL)) { | |
523 | ret = -ENOMEM; | |
524 | goto out; | |
525 | } | |
1da177e4 | 526 | |
d0de32d9 | 527 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); |
1da177e4 | 528 | if (vma->vm_flags & VM_LOCKED) { |
d0de32d9 | 529 | mm->locked_vm += pages; |
81909b84 ML |
530 | locked = true; |
531 | new_addr = addr; | |
1da177e4 LT |
532 | } |
533 | ret = addr; | |
534 | goto out; | |
535 | } | |
536 | } | |
537 | ||
538 | /* | |
539 | * We weren't able to just expand or shrink the area, | |
540 | * we need to create a new one and move it.. | |
541 | */ | |
542 | ret = -ENOMEM; | |
543 | if (flags & MREMAP_MAYMOVE) { | |
ecc1a899 AV |
544 | unsigned long map_flags = 0; |
545 | if (vma->vm_flags & VM_MAYSHARE) | |
546 | map_flags |= MAP_SHARED; | |
547 | ||
548 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, | |
93587414 AV |
549 | vma->vm_pgoff + |
550 | ((addr - vma->vm_start) >> PAGE_SHIFT), | |
551 | map_flags); | |
ecc1a899 AV |
552 | if (new_addr & ~PAGE_MASK) { |
553 | ret = new_addr; | |
554 | goto out; | |
1da177e4 | 555 | } |
ecc1a899 | 556 | |
81909b84 | 557 | ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked); |
1da177e4 LT |
558 | } |
559 | out: | |
560 | if (ret & ~PAGE_MASK) | |
561 | vm_unacct_memory(charged); | |
1da177e4 | 562 | up_write(¤t->mm->mmap_sem); |
81909b84 ML |
563 | if (locked && new_len > old_len) |
564 | mm_populate(new_addr + old_len, new_len - old_len); | |
1da177e4 LT |
565 | return ret; |
566 | } |