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 | 17 | #include <linux/fs.h> |
6dec97dc | 18 | #include <linux/swapops.h> |
1da177e4 LT |
19 | #include <linux/highmem.h> |
20 | #include <linux/security.h> | |
21 | #include <linux/syscalls.h> | |
cddb8a5c | 22 | #include <linux/mmu_notifier.h> |
cf4aebc2 | 23 | #include <linux/sched/sysctl.h> |
1da177e4 LT |
24 | |
25 | #include <asm/uaccess.h> | |
26 | #include <asm/cacheflush.h> | |
27 | #include <asm/tlbflush.h> | |
1ecfd533 | 28 | #include <asm/pgalloc.h> |
1da177e4 | 29 | |
ba470de4 RR |
30 | #include "internal.h" |
31 | ||
7be7a546 | 32 | static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
33 | { |
34 | pgd_t *pgd; | |
35 | pud_t *pud; | |
36 | pmd_t *pmd; | |
37 | ||
38 | pgd = pgd_offset(mm, addr); | |
39 | if (pgd_none_or_clear_bad(pgd)) | |
40 | return NULL; | |
41 | ||
42 | pud = pud_offset(pgd, addr); | |
43 | if (pud_none_or_clear_bad(pud)) | |
44 | return NULL; | |
45 | ||
46 | pmd = pmd_offset(pud, addr); | |
37a1c49a | 47 | if (pmd_none(*pmd)) |
1da177e4 LT |
48 | return NULL; |
49 | ||
7be7a546 | 50 | return pmd; |
1da177e4 LT |
51 | } |
52 | ||
8ac1f832 AA |
53 | static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma, |
54 | unsigned long addr) | |
1da177e4 LT |
55 | { |
56 | pgd_t *pgd; | |
57 | pud_t *pud; | |
c74df32c | 58 | pmd_t *pmd; |
1da177e4 LT |
59 | |
60 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
61 | pud = pud_alloc(mm, pgd, addr); |
62 | if (!pud) | |
c74df32c | 63 | return NULL; |
7be7a546 | 64 | |
1da177e4 | 65 | pmd = pmd_alloc(mm, pud, addr); |
1ecfd533 CG |
66 | if (!pmd) { |
67 | pud_free(mm, pud); | |
c74df32c | 68 | return NULL; |
1ecfd533 | 69 | } |
7be7a546 | 70 | |
8ac1f832 | 71 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
c74df32c | 72 | |
7be7a546 | 73 | return pmd; |
1da177e4 LT |
74 | } |
75 | ||
6dec97dc CG |
76 | static pte_t move_soft_dirty_pte(pte_t pte) |
77 | { | |
78 | /* | |
79 | * Set soft dirty bit so we can notice | |
80 | * in userspace the ptes were moved. | |
81 | */ | |
82 | #ifdef CONFIG_MEM_SOFT_DIRTY | |
83 | if (pte_present(pte)) | |
84 | pte = pte_mksoft_dirty(pte); | |
85 | else if (is_swap_pte(pte)) | |
86 | pte = pte_swp_mksoft_dirty(pte); | |
87 | else if (pte_file(pte)) | |
88 | pte = pte_file_mksoft_dirty(pte); | |
89 | #endif | |
90 | return pte; | |
91 | } | |
92 | ||
7be7a546 HD |
93 | static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, |
94 | unsigned long old_addr, unsigned long old_end, | |
95 | struct vm_area_struct *new_vma, pmd_t *new_pmd, | |
38a76013 | 96 | unsigned long new_addr, bool need_rmap_locks) |
1da177e4 LT |
97 | { |
98 | struct address_space *mapping = NULL; | |
38a76013 | 99 | struct anon_vma *anon_vma = NULL; |
1da177e4 | 100 | struct mm_struct *mm = vma->vm_mm; |
7be7a546 | 101 | pte_t *old_pte, *new_pte, pte; |
4c21e2f2 | 102 | spinlock_t *old_ptl, *new_ptl; |
1da177e4 | 103 | |
38a76013 ML |
104 | /* |
105 | * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma | |
106 | * locks to ensure that rmap will always observe either the old or the | |
107 | * new ptes. This is the easiest way to avoid races with | |
108 | * truncate_pagecache(), page migration, etc... | |
109 | * | |
110 | * When need_rmap_locks is false, we use other ways to avoid | |
111 | * such races: | |
112 | * | |
113 | * - During exec() shift_arg_pages(), we use a specially tagged vma | |
114 | * which rmap call sites look for using is_vma_temporary_stack(). | |
115 | * | |
116 | * - During mremap(), new_vma is often known to be placed after vma | |
117 | * in rmap traversal order. This ensures rmap will always observe | |
118 | * either the old pte, or the new pte, or both (the page table locks | |
119 | * serialize access to individual ptes, but only rmap traversal | |
120 | * order guarantees that we won't miss both the old and new ptes). | |
121 | */ | |
122 | if (need_rmap_locks) { | |
123 | if (vma->vm_file) { | |
124 | mapping = vma->vm_file->f_mapping; | |
125 | mutex_lock(&mapping->i_mmap_mutex); | |
126 | } | |
127 | if (vma->anon_vma) { | |
128 | anon_vma = vma->anon_vma; | |
4fc3f1d6 | 129 | anon_vma_lock_write(anon_vma); |
38a76013 | 130 | } |
1da177e4 | 131 | } |
1da177e4 | 132 | |
4c21e2f2 HD |
133 | /* |
134 | * We don't have to worry about the ordering of src and dst | |
135 | * pte locks because exclusive mmap_sem prevents deadlock. | |
136 | */ | |
c74df32c | 137 | old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); |
ece0e2b6 | 138 | new_pte = pte_offset_map(new_pmd, new_addr); |
4c21e2f2 HD |
139 | new_ptl = pte_lockptr(mm, new_pmd); |
140 | if (new_ptl != old_ptl) | |
f20dc5f7 | 141 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); |
6606c3e0 | 142 | arch_enter_lazy_mmu_mode(); |
7be7a546 HD |
143 | |
144 | for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, | |
145 | new_pte++, new_addr += PAGE_SIZE) { | |
146 | if (pte_none(*old_pte)) | |
147 | continue; | |
7b6efc2b | 148 | pte = ptep_get_and_clear(mm, old_addr, old_pte); |
7be7a546 | 149 | pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); |
6dec97dc CG |
150 | pte = move_soft_dirty_pte(pte); |
151 | set_pte_at(mm, new_addr, new_pte, pte); | |
1da177e4 | 152 | } |
7be7a546 | 153 | |
6606c3e0 | 154 | arch_leave_lazy_mmu_mode(); |
4c21e2f2 HD |
155 | if (new_ptl != old_ptl) |
156 | spin_unlock(new_ptl); | |
ece0e2b6 | 157 | pte_unmap(new_pte - 1); |
c74df32c | 158 | pte_unmap_unlock(old_pte - 1, old_ptl); |
108d6642 | 159 | if (anon_vma) |
08b52706 | 160 | anon_vma_unlock_write(anon_vma); |
1da177e4 | 161 | if (mapping) |
3d48ae45 | 162 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
163 | } |
164 | ||
7be7a546 HD |
165 | #define LATENCY_LIMIT (64 * PAGE_SIZE) |
166 | ||
b6a2fea3 | 167 | unsigned long move_page_tables(struct vm_area_struct *vma, |
1da177e4 | 168 | unsigned long old_addr, struct vm_area_struct *new_vma, |
38a76013 ML |
169 | unsigned long new_addr, unsigned long len, |
170 | bool need_rmap_locks) | |
1da177e4 | 171 | { |
7be7a546 HD |
172 | unsigned long extent, next, old_end; |
173 | pmd_t *old_pmd, *new_pmd; | |
7b6efc2b | 174 | bool need_flush = false; |
2ec74c3e SG |
175 | unsigned long mmun_start; /* For mmu_notifiers */ |
176 | unsigned long mmun_end; /* For mmu_notifiers */ | |
1da177e4 | 177 | |
7be7a546 HD |
178 | old_end = old_addr + len; |
179 | flush_cache_range(vma, old_addr, old_end); | |
1da177e4 | 180 | |
2ec74c3e SG |
181 | mmun_start = old_addr; |
182 | mmun_end = old_end; | |
183 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); | |
7b6efc2b | 184 | |
7be7a546 | 185 | for (; old_addr < old_end; old_addr += extent, new_addr += extent) { |
1da177e4 | 186 | cond_resched(); |
7be7a546 | 187 | next = (old_addr + PMD_SIZE) & PMD_MASK; |
ebed4846 | 188 | /* even if next overflowed, extent below will be ok */ |
7be7a546 | 189 | extent = next - old_addr; |
ebed4846 AA |
190 | if (extent > old_end - old_addr) |
191 | extent = old_end - old_addr; | |
7be7a546 HD |
192 | old_pmd = get_old_pmd(vma->vm_mm, old_addr); |
193 | if (!old_pmd) | |
194 | continue; | |
8ac1f832 | 195 | new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr); |
7be7a546 HD |
196 | if (!new_pmd) |
197 | break; | |
37a1c49a AA |
198 | if (pmd_trans_huge(*old_pmd)) { |
199 | int err = 0; | |
200 | if (extent == HPAGE_PMD_SIZE) | |
201 | err = move_huge_pmd(vma, new_vma, old_addr, | |
202 | new_addr, old_end, | |
203 | old_pmd, new_pmd); | |
204 | if (err > 0) { | |
205 | need_flush = true; | |
206 | continue; | |
207 | } else if (!err) { | |
e180377f | 208 | split_huge_page_pmd(vma, old_addr, old_pmd); |
37a1c49a AA |
209 | } |
210 | VM_BUG_ON(pmd_trans_huge(*old_pmd)); | |
211 | } | |
212 | if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma, | |
213 | new_pmd, new_addr)) | |
214 | break; | |
7be7a546 HD |
215 | next = (new_addr + PMD_SIZE) & PMD_MASK; |
216 | if (extent > next - new_addr) | |
217 | extent = next - new_addr; | |
218 | if (extent > LATENCY_LIMIT) | |
219 | extent = LATENCY_LIMIT; | |
220 | move_ptes(vma, old_pmd, old_addr, old_addr + extent, | |
38a76013 | 221 | new_vma, new_pmd, new_addr, need_rmap_locks); |
7b6efc2b | 222 | need_flush = true; |
1da177e4 | 223 | } |
7b6efc2b AA |
224 | if (likely(need_flush)) |
225 | flush_tlb_range(vma, old_end-len, old_addr); | |
226 | ||
2ec74c3e | 227 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
7be7a546 HD |
228 | |
229 | return len + old_addr - old_end; /* how much done */ | |
1da177e4 LT |
230 | } |
231 | ||
232 | static unsigned long move_vma(struct vm_area_struct *vma, | |
233 | unsigned long old_addr, unsigned long old_len, | |
81909b84 | 234 | unsigned long new_len, unsigned long new_addr, bool *locked) |
1da177e4 LT |
235 | { |
236 | struct mm_struct *mm = vma->vm_mm; | |
237 | struct vm_area_struct *new_vma; | |
238 | unsigned long vm_flags = vma->vm_flags; | |
239 | unsigned long new_pgoff; | |
240 | unsigned long moved_len; | |
241 | unsigned long excess = 0; | |
365e9c87 | 242 | unsigned long hiwater_vm; |
1da177e4 | 243 | int split = 0; |
7103ad32 | 244 | int err; |
38a76013 | 245 | bool need_rmap_locks; |
1da177e4 LT |
246 | |
247 | /* | |
248 | * We'd prefer to avoid failure later on in do_munmap: | |
249 | * which may split one vma into three before unmapping. | |
250 | */ | |
251 | if (mm->map_count >= sysctl_max_map_count - 3) | |
252 | return -ENOMEM; | |
253 | ||
1ff82995 HD |
254 | /* |
255 | * Advise KSM to break any KSM pages in the area to be moved: | |
256 | * it would be confusing if they were to turn up at the new | |
257 | * location, where they happen to coincide with different KSM | |
258 | * pages recently unmapped. But leave vma->vm_flags as it was, | |
259 | * so KSM can come around to merge on vma and new_vma afterwards. | |
260 | */ | |
7103ad32 HD |
261 | err = ksm_madvise(vma, old_addr, old_addr + old_len, |
262 | MADV_UNMERGEABLE, &vm_flags); | |
263 | if (err) | |
264 | return err; | |
1ff82995 | 265 | |
1da177e4 | 266 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); |
38a76013 ML |
267 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff, |
268 | &need_rmap_locks); | |
1da177e4 LT |
269 | if (!new_vma) |
270 | return -ENOMEM; | |
271 | ||
38a76013 ML |
272 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len, |
273 | need_rmap_locks); | |
1da177e4 LT |
274 | if (moved_len < old_len) { |
275 | /* | |
276 | * On error, move entries back from new area to old, | |
277 | * which will succeed since page tables still there, | |
278 | * and then proceed to unmap new area instead of old. | |
279 | */ | |
38a76013 ML |
280 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len, |
281 | true); | |
1da177e4 LT |
282 | vma = new_vma; |
283 | old_len = new_len; | |
284 | old_addr = new_addr; | |
285 | new_addr = -ENOMEM; | |
286 | } | |
287 | ||
288 | /* Conceal VM_ACCOUNT so old reservation is not undone */ | |
289 | if (vm_flags & VM_ACCOUNT) { | |
290 | vma->vm_flags &= ~VM_ACCOUNT; | |
291 | excess = vma->vm_end - vma->vm_start - old_len; | |
292 | if (old_addr > vma->vm_start && | |
293 | old_addr + old_len < vma->vm_end) | |
294 | split = 1; | |
295 | } | |
296 | ||
71799062 | 297 | /* |
365e9c87 HD |
298 | * If we failed to move page tables we still do total_vm increment |
299 | * since do_munmap() will decrement it by old_len == new_len. | |
300 | * | |
301 | * Since total_vm is about to be raised artificially high for a | |
302 | * moment, we need to restore high watermark afterwards: if stats | |
303 | * are taken meanwhile, total_vm and hiwater_vm appear too high. | |
304 | * If this were a serious issue, we'd add a flag to do_munmap(). | |
71799062 | 305 | */ |
365e9c87 | 306 | hiwater_vm = mm->hiwater_vm; |
ab50b8ed | 307 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
71799062 | 308 | |
1da177e4 LT |
309 | if (do_munmap(mm, old_addr, old_len) < 0) { |
310 | /* OOM: unable to split vma, just get accounts right */ | |
311 | vm_unacct_memory(excess >> PAGE_SHIFT); | |
312 | excess = 0; | |
313 | } | |
365e9c87 | 314 | mm->hiwater_vm = hiwater_vm; |
1da177e4 LT |
315 | |
316 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ | |
317 | if (excess) { | |
318 | vma->vm_flags |= VM_ACCOUNT; | |
319 | if (split) | |
320 | vma->vm_next->vm_flags |= VM_ACCOUNT; | |
321 | } | |
322 | ||
1da177e4 LT |
323 | if (vm_flags & VM_LOCKED) { |
324 | mm->locked_vm += new_len >> PAGE_SHIFT; | |
81909b84 | 325 | *locked = true; |
1da177e4 LT |
326 | } |
327 | ||
328 | return new_addr; | |
329 | } | |
330 | ||
54f5de70 AV |
331 | static struct vm_area_struct *vma_to_resize(unsigned long addr, |
332 | unsigned long old_len, unsigned long new_len, unsigned long *p) | |
333 | { | |
334 | struct mm_struct *mm = current->mm; | |
335 | struct vm_area_struct *vma = find_vma(mm, addr); | |
336 | ||
337 | if (!vma || vma->vm_start > addr) | |
338 | goto Efault; | |
339 | ||
340 | if (is_vm_hugetlb_page(vma)) | |
341 | goto Einval; | |
342 | ||
343 | /* We can't remap across vm area boundaries */ | |
344 | if (old_len > vma->vm_end - addr) | |
345 | goto Efault; | |
346 | ||
982134ba LT |
347 | /* Need to be careful about a growing mapping */ |
348 | if (new_len > old_len) { | |
349 | unsigned long pgoff; | |
350 | ||
351 | if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) | |
54f5de70 | 352 | goto Efault; |
982134ba LT |
353 | pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; |
354 | pgoff += vma->vm_pgoff; | |
355 | if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) | |
356 | goto Einval; | |
54f5de70 AV |
357 | } |
358 | ||
359 | if (vma->vm_flags & VM_LOCKED) { | |
360 | unsigned long locked, lock_limit; | |
361 | locked = mm->locked_vm << PAGE_SHIFT; | |
59e99e5b | 362 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
54f5de70 AV |
363 | locked += new_len - old_len; |
364 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
365 | goto Eagain; | |
366 | } | |
367 | ||
368 | if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) | |
369 | goto Enomem; | |
370 | ||
371 | if (vma->vm_flags & VM_ACCOUNT) { | |
372 | unsigned long charged = (new_len - old_len) >> PAGE_SHIFT; | |
191c5424 | 373 | if (security_vm_enough_memory_mm(mm, charged)) |
54f5de70 AV |
374 | goto Efault; |
375 | *p = charged; | |
376 | } | |
377 | ||
378 | return vma; | |
379 | ||
380 | Efault: /* very odd choice for most of the cases, but... */ | |
381 | return ERR_PTR(-EFAULT); | |
382 | Einval: | |
383 | return ERR_PTR(-EINVAL); | |
384 | Enomem: | |
385 | return ERR_PTR(-ENOMEM); | |
386 | Eagain: | |
387 | return ERR_PTR(-EAGAIN); | |
388 | } | |
389 | ||
81909b84 ML |
390 | static unsigned long mremap_to(unsigned long addr, unsigned long old_len, |
391 | unsigned long new_addr, unsigned long new_len, bool *locked) | |
ecc1a899 AV |
392 | { |
393 | struct mm_struct *mm = current->mm; | |
394 | struct vm_area_struct *vma; | |
395 | unsigned long ret = -EINVAL; | |
396 | unsigned long charged = 0; | |
097eed10 | 397 | unsigned long map_flags; |
ecc1a899 AV |
398 | |
399 | if (new_addr & ~PAGE_MASK) | |
400 | goto out; | |
401 | ||
402 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) | |
403 | goto out; | |
404 | ||
405 | /* Check if the location we're moving into overlaps the | |
406 | * old location at all, and fail if it does. | |
407 | */ | |
408 | if ((new_addr <= addr) && (new_addr+new_len) > addr) | |
409 | goto out; | |
410 | ||
411 | if ((addr <= new_addr) && (addr+old_len) > new_addr) | |
412 | goto out; | |
413 | ||
ecc1a899 AV |
414 | ret = do_munmap(mm, new_addr, new_len); |
415 | if (ret) | |
416 | goto out; | |
417 | ||
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) | |
421 | goto out; | |
422 | old_len = new_len; | |
423 | } | |
424 | ||
425 | vma = vma_to_resize(addr, old_len, new_len, &charged); | |
426 | if (IS_ERR(vma)) { | |
427 | ret = PTR_ERR(vma); | |
428 | goto out; | |
429 | } | |
430 | ||
097eed10 AV |
431 | map_flags = MAP_FIXED; |
432 | if (vma->vm_flags & VM_MAYSHARE) | |
433 | map_flags |= MAP_SHARED; | |
9206de95 | 434 | |
097eed10 AV |
435 | ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + |
436 | ((addr - vma->vm_start) >> PAGE_SHIFT), | |
437 | map_flags); | |
ecc1a899 | 438 | if (ret & ~PAGE_MASK) |
097eed10 AV |
439 | goto out1; |
440 | ||
81909b84 | 441 | ret = move_vma(vma, addr, old_len, new_len, new_addr, locked); |
097eed10 AV |
442 | if (!(ret & ~PAGE_MASK)) |
443 | goto out; | |
444 | out1: | |
445 | vm_unacct_memory(charged); | |
ecc1a899 AV |
446 | |
447 | out: | |
448 | return ret; | |
449 | } | |
450 | ||
1a0ef85f AV |
451 | static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) |
452 | { | |
f106af4e | 453 | unsigned long end = vma->vm_end + delta; |
9206de95 | 454 | if (end < vma->vm_end) /* overflow */ |
f106af4e | 455 | return 0; |
9206de95 | 456 | if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */ |
f106af4e AV |
457 | return 0; |
458 | if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start, | |
459 | 0, MAP_FIXED) & ~PAGE_MASK) | |
1a0ef85f | 460 | return 0; |
1a0ef85f AV |
461 | return 1; |
462 | } | |
463 | ||
1da177e4 LT |
464 | /* |
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) | |
467 | * | |
468 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise | |
469 | * This option implies MREMAP_MAYMOVE. | |
470 | */ | |
63a81db1 AV |
471 | SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
472 | unsigned long, new_len, unsigned long, flags, | |
473 | unsigned long, new_addr) | |
1da177e4 | 474 | { |
d0de32d9 | 475 | struct mm_struct *mm = current->mm; |
1da177e4 LT |
476 | struct vm_area_struct *vma; |
477 | unsigned long ret = -EINVAL; | |
478 | unsigned long charged = 0; | |
81909b84 | 479 | bool locked = false; |
1da177e4 LT |
480 | |
481 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) | |
9a2458a6 RV |
482 | return ret; |
483 | ||
484 | if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE)) | |
485 | return ret; | |
1da177e4 LT |
486 | |
487 | if (addr & ~PAGE_MASK) | |
9a2458a6 | 488 | return ret; |
1da177e4 LT |
489 | |
490 | old_len = PAGE_ALIGN(old_len); | |
491 | new_len = PAGE_ALIGN(new_len); | |
492 | ||
493 | /* | |
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. | |
497 | */ | |
498 | if (!new_len) | |
9a2458a6 RV |
499 | return ret; |
500 | ||
501 | down_write(¤t->mm->mmap_sem); | |
1da177e4 | 502 | |
1da177e4 | 503 | if (flags & MREMAP_FIXED) { |
9a2458a6 RV |
504 | ret = mremap_to(addr, old_len, new_addr, new_len, |
505 | &locked); | |
ecc1a899 | 506 | goto out; |
1da177e4 LT |
507 | } |
508 | ||
509 | /* | |
510 | * Always allow a shrinking remap: that just unmaps | |
511 | * the unnecessary pages.. | |
512 | * do_munmap does all the needed commit accounting | |
513 | */ | |
514 | if (old_len >= new_len) { | |
d0de32d9 | 515 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
1da177e4 LT |
516 | if (ret && old_len != new_len) |
517 | goto out; | |
518 | ret = addr; | |
ecc1a899 | 519 | goto out; |
1da177e4 LT |
520 | } |
521 | ||
522 | /* | |
ecc1a899 | 523 | * Ok, we need to grow.. |
1da177e4 | 524 | */ |
54f5de70 AV |
525 | vma = vma_to_resize(addr, old_len, new_len, &charged); |
526 | if (IS_ERR(vma)) { | |
527 | ret = PTR_ERR(vma); | |
1da177e4 | 528 | goto out; |
119f657c | 529 | } |
1da177e4 | 530 | |
1da177e4 | 531 | /* old_len exactly to the end of the area.. |
1da177e4 | 532 | */ |
ecc1a899 | 533 | if (old_len == vma->vm_end - addr) { |
1da177e4 | 534 | /* can we just expand the current mapping? */ |
1a0ef85f | 535 | if (vma_expandable(vma, new_len - old_len)) { |
1da177e4 LT |
536 | int pages = (new_len - old_len) >> PAGE_SHIFT; |
537 | ||
5beb4930 RR |
538 | if (vma_adjust(vma, vma->vm_start, addr + new_len, |
539 | vma->vm_pgoff, NULL)) { | |
540 | ret = -ENOMEM; | |
541 | goto out; | |
542 | } | |
1da177e4 | 543 | |
d0de32d9 | 544 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); |
1da177e4 | 545 | if (vma->vm_flags & VM_LOCKED) { |
d0de32d9 | 546 | mm->locked_vm += pages; |
81909b84 ML |
547 | locked = true; |
548 | new_addr = addr; | |
1da177e4 LT |
549 | } |
550 | ret = addr; | |
551 | goto out; | |
552 | } | |
553 | } | |
554 | ||
555 | /* | |
556 | * We weren't able to just expand or shrink the area, | |
557 | * we need to create a new one and move it.. | |
558 | */ | |
559 | ret = -ENOMEM; | |
560 | if (flags & MREMAP_MAYMOVE) { | |
ecc1a899 AV |
561 | unsigned long map_flags = 0; |
562 | if (vma->vm_flags & VM_MAYSHARE) | |
563 | map_flags |= MAP_SHARED; | |
564 | ||
565 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, | |
93587414 AV |
566 | vma->vm_pgoff + |
567 | ((addr - vma->vm_start) >> PAGE_SHIFT), | |
568 | map_flags); | |
ecc1a899 AV |
569 | if (new_addr & ~PAGE_MASK) { |
570 | ret = new_addr; | |
571 | goto out; | |
1da177e4 | 572 | } |
ecc1a899 | 573 | |
81909b84 | 574 | ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked); |
1da177e4 LT |
575 | } |
576 | out: | |
577 | if (ret & ~PAGE_MASK) | |
578 | vm_unacct_memory(charged); | |
1da177e4 | 579 | up_write(¤t->mm->mmap_sem); |
81909b84 ML |
580 | if (locked && new_len > old_len) |
581 | mm_populate(new_addr + old_len, new_len - old_len); | |
1da177e4 LT |
582 | return ret; |
583 | } |