blob: ddaeee9a0b69e5a5e5b232377ae97801fd6a438e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
6 * Address space accounting code <alan@redhat.com>
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/slab.h>
13#include <linux/shm.h>
14#include <linux/mman.h>
15#include <linux/swap.h>
16#include <linux/fs.h>
17#include <linux/highmem.h>
18#include <linux/security.h>
19#include <linux/syscalls.h>
20
21#include <asm/uaccess.h>
22#include <asm/cacheflush.h>
23#include <asm/tlbflush.h>
24
Hugh Dickins7be7a542005-10-29 18:16:00 -070025static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070026{
27 pgd_t *pgd;
28 pud_t *pud;
29 pmd_t *pmd;
30
31 pgd = pgd_offset(mm, addr);
32 if (pgd_none_or_clear_bad(pgd))
33 return NULL;
34
35 pud = pud_offset(pgd, addr);
36 if (pud_none_or_clear_bad(pud))
37 return NULL;
38
39 pmd = pmd_offset(pud, addr);
40 if (pmd_none_or_clear_bad(pmd))
41 return NULL;
42
Hugh Dickins7be7a542005-10-29 18:16:00 -070043 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044}
45
Hugh Dickins7be7a542005-10-29 18:16:00 -070046static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070047{
48 pgd_t *pgd;
49 pud_t *pud;
Hugh Dickinsc74df322005-10-29 18:16:23 -070050 pmd_t *pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52 pgd = pgd_offset(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 pud = pud_alloc(mm, pgd, addr);
54 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -070055 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 pmd = pmd_alloc(mm, pud, addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -070058 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -070059 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070060
Hugh Dickins1bb36302005-10-29 18:16:22 -070061 if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
Hugh Dickinsc74df322005-10-29 18:16:23 -070062 return NULL;
63
Hugh Dickins7be7a542005-10-29 18:16:00 -070064 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065}
66
Hugh Dickins7be7a542005-10-29 18:16:00 -070067static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
68 unsigned long old_addr, unsigned long old_end,
69 struct vm_area_struct *new_vma, pmd_t *new_pmd,
70 unsigned long new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071{
72 struct address_space *mapping = NULL;
73 struct mm_struct *mm = vma->vm_mm;
Hugh Dickins7be7a542005-10-29 18:16:00 -070074 pte_t *old_pte, *new_pte, pte;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070075 spinlock_t *old_ptl, *new_ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
77 if (vma->vm_file) {
78 /*
79 * Subtle point from Rajesh Venkatasubramanian: before
80 * moving file-based ptes, we must lock vmtruncate out,
81 * since it might clean the dst vma before the src vma,
82 * and we propagate stale pages into the dst afterward.
83 */
84 mapping = vma->vm_file->f_mapping;
85 spin_lock(&mapping->i_mmap_lock);
86 if (new_vma->vm_truncate_count &&
87 new_vma->vm_truncate_count != vma->vm_truncate_count)
88 new_vma->vm_truncate_count = 0;
89 }
Hugh Dickins7be7a542005-10-29 18:16:00 -070090
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070091 /*
92 * We don't have to worry about the ordering of src and dst
93 * pte locks because exclusive mmap_sem prevents deadlock.
94 */
Hugh Dickinsc74df322005-10-29 18:16:23 -070095 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
96 new_pte = pte_offset_map_nested(new_pmd, new_addr);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070097 new_ptl = pte_lockptr(mm, new_pmd);
98 if (new_ptl != old_ptl)
99 spin_lock(new_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
Hugh Dickins7be7a542005-10-29 18:16:00 -0700101 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
102 new_pte++, new_addr += PAGE_SIZE) {
103 if (pte_none(*old_pte))
104 continue;
105 pte = ptep_clear_flush(vma, old_addr, old_pte);
106 /* ZERO_PAGE can be dependant on virtual addr */
107 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
108 set_pte_at(mm, new_addr, new_pte, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700110
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700111 if (new_ptl != old_ptl)
112 spin_unlock(new_ptl);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700113 pte_unmap_nested(new_pte - 1);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700114 pte_unmap_unlock(old_pte - 1, old_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 if (mapping)
116 spin_unlock(&mapping->i_mmap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117}
118
Hugh Dickins7be7a542005-10-29 18:16:00 -0700119#define LATENCY_LIMIT (64 * PAGE_SIZE)
120
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121static unsigned long move_page_tables(struct vm_area_struct *vma,
122 unsigned long old_addr, struct vm_area_struct *new_vma,
123 unsigned long new_addr, unsigned long len)
124{
Hugh Dickins7be7a542005-10-29 18:16:00 -0700125 unsigned long extent, next, old_end;
126 pmd_t *old_pmd, *new_pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Hugh Dickins7be7a542005-10-29 18:16:00 -0700128 old_end = old_addr + len;
129 flush_cache_range(vma, old_addr, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Hugh Dickins7be7a542005-10-29 18:16:00 -0700131 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 cond_resched();
Hugh Dickins7be7a542005-10-29 18:16:00 -0700133 next = (old_addr + PMD_SIZE) & PMD_MASK;
134 if (next - 1 > old_end)
135 next = old_end;
136 extent = next - old_addr;
137 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
138 if (!old_pmd)
139 continue;
140 new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
141 if (!new_pmd)
142 break;
143 next = (new_addr + PMD_SIZE) & PMD_MASK;
144 if (extent > next - new_addr)
145 extent = next - new_addr;
146 if (extent > LATENCY_LIMIT)
147 extent = LATENCY_LIMIT;
148 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
149 new_vma, new_pmd, new_addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700151
152 return len + old_addr - old_end; /* how much done */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153}
154
155static unsigned long move_vma(struct vm_area_struct *vma,
156 unsigned long old_addr, unsigned long old_len,
157 unsigned long new_len, unsigned long new_addr)
158{
159 struct mm_struct *mm = vma->vm_mm;
160 struct vm_area_struct *new_vma;
161 unsigned long vm_flags = vma->vm_flags;
162 unsigned long new_pgoff;
163 unsigned long moved_len;
164 unsigned long excess = 0;
Hugh Dickins365e9c872005-10-29 18:16:18 -0700165 unsigned long hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 int split = 0;
167
168 /*
169 * We'd prefer to avoid failure later on in do_munmap:
170 * which may split one vma into three before unmapping.
171 */
172 if (mm->map_count >= sysctl_max_map_count - 3)
173 return -ENOMEM;
174
175 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
176 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
177 if (!new_vma)
178 return -ENOMEM;
179
180 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
181 if (moved_len < old_len) {
182 /*
183 * On error, move entries back from new area to old,
184 * which will succeed since page tables still there,
185 * and then proceed to unmap new area instead of old.
186 */
187 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
188 vma = new_vma;
189 old_len = new_len;
190 old_addr = new_addr;
191 new_addr = -ENOMEM;
192 }
193
194 /* Conceal VM_ACCOUNT so old reservation is not undone */
195 if (vm_flags & VM_ACCOUNT) {
196 vma->vm_flags &= ~VM_ACCOUNT;
197 excess = vma->vm_end - vma->vm_start - old_len;
198 if (old_addr > vma->vm_start &&
199 old_addr + old_len < vma->vm_end)
200 split = 1;
201 }
202
Kirill Korotaev71799062005-05-16 21:53:18 -0700203 /*
Hugh Dickins365e9c872005-10-29 18:16:18 -0700204 * If we failed to move page tables we still do total_vm increment
205 * since do_munmap() will decrement it by old_len == new_len.
206 *
207 * Since total_vm is about to be raised artificially high for a
208 * moment, we need to restore high watermark afterwards: if stats
209 * are taken meanwhile, total_vm and hiwater_vm appear too high.
210 * If this were a serious issue, we'd add a flag to do_munmap().
Kirill Korotaev71799062005-05-16 21:53:18 -0700211 */
Hugh Dickins365e9c872005-10-29 18:16:18 -0700212 hiwater_vm = mm->hiwater_vm;
Kirill Korotaev71799062005-05-16 21:53:18 -0700213 mm->total_vm += new_len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700214 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
Kirill Korotaev71799062005-05-16 21:53:18 -0700215
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 if (do_munmap(mm, old_addr, old_len) < 0) {
217 /* OOM: unable to split vma, just get accounts right */
218 vm_unacct_memory(excess >> PAGE_SHIFT);
219 excess = 0;
220 }
Hugh Dickins365e9c872005-10-29 18:16:18 -0700221 mm->hiwater_vm = hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
223 /* Restore VM_ACCOUNT if one or two pieces of vma left */
224 if (excess) {
225 vma->vm_flags |= VM_ACCOUNT;
226 if (split)
227 vma->vm_next->vm_flags |= VM_ACCOUNT;
228 }
229
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 if (vm_flags & VM_LOCKED) {
231 mm->locked_vm += new_len >> PAGE_SHIFT;
232 if (new_len > old_len)
233 make_pages_present(new_addr + old_len,
234 new_addr + new_len);
235 }
236
237 return new_addr;
238}
239
240/*
241 * Expand (or shrink) an existing mapping, potentially moving it at the
242 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
243 *
244 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
245 * This option implies MREMAP_MAYMOVE.
246 */
247unsigned long do_mremap(unsigned long addr,
248 unsigned long old_len, unsigned long new_len,
249 unsigned long flags, unsigned long new_addr)
250{
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700251 struct mm_struct *mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 struct vm_area_struct *vma;
253 unsigned long ret = -EINVAL;
254 unsigned long charged = 0;
255
256 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
257 goto out;
258
259 if (addr & ~PAGE_MASK)
260 goto out;
261
262 old_len = PAGE_ALIGN(old_len);
263 new_len = PAGE_ALIGN(new_len);
264
265 /*
266 * We allow a zero old-len as a special case
267 * for DOS-emu "duplicate shm area" thing. But
268 * a zero new-len is nonsensical.
269 */
270 if (!new_len)
271 goto out;
272
273 /* new_addr is only valid if MREMAP_FIXED is specified */
274 if (flags & MREMAP_FIXED) {
275 if (new_addr & ~PAGE_MASK)
276 goto out;
277 if (!(flags & MREMAP_MAYMOVE))
278 goto out;
279
280 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
281 goto out;
282
283 /* Check if the location we're moving into overlaps the
284 * old location at all, and fail if it does.
285 */
286 if ((new_addr <= addr) && (new_addr+new_len) > addr)
287 goto out;
288
289 if ((addr <= new_addr) && (addr+old_len) > new_addr)
290 goto out;
291
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700292 ret = do_munmap(mm, new_addr, new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 if (ret)
294 goto out;
295 }
296
297 /*
298 * Always allow a shrinking remap: that just unmaps
299 * the unnecessary pages..
300 * do_munmap does all the needed commit accounting
301 */
302 if (old_len >= new_len) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700303 ret = do_munmap(mm, addr+new_len, old_len - new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 if (ret && old_len != new_len)
305 goto out;
306 ret = addr;
307 if (!(flags & MREMAP_FIXED) || (new_addr == addr))
308 goto out;
309 old_len = new_len;
310 }
311
312 /*
313 * Ok, we need to grow.. or relocate.
314 */
315 ret = -EFAULT;
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700316 vma = find_vma(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 if (!vma || vma->vm_start > addr)
318 goto out;
319 if (is_vm_hugetlb_page(vma)) {
320 ret = -EINVAL;
321 goto out;
322 }
323 /* We can't remap across vm area boundaries */
324 if (old_len > vma->vm_end - addr)
325 goto out;
Linus Torvalds4d7672b2005-12-16 10:21:23 -0800326 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 if (new_len > old_len)
328 goto out;
329 }
330 if (vma->vm_flags & VM_LOCKED) {
331 unsigned long locked, lock_limit;
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700332 locked = mm->locked_vm << PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
334 locked += new_len - old_len;
335 ret = -EAGAIN;
336 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
337 goto out;
338 }
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700339 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
akpm@osdl.org119f6572005-05-01 08:58:35 -0700340 ret = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 goto out;
akpm@osdl.org119f6572005-05-01 08:58:35 -0700342 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343
344 if (vma->vm_flags & VM_ACCOUNT) {
345 charged = (new_len - old_len) >> PAGE_SHIFT;
346 if (security_vm_enough_memory(charged))
347 goto out_nc;
348 }
349
350 /* old_len exactly to the end of the area..
351 * And we're not relocating the area.
352 */
353 if (old_len == vma->vm_end - addr &&
354 !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
355 (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
356 unsigned long max_addr = TASK_SIZE;
357 if (vma->vm_next)
358 max_addr = vma->vm_next->vm_start;
359 /* can we just expand the current mapping? */
360 if (max_addr - addr >= new_len) {
361 int pages = (new_len - old_len) >> PAGE_SHIFT;
362
363 vma_adjust(vma, vma->vm_start,
364 addr + new_len, vma->vm_pgoff, NULL);
365
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700366 mm->total_vm += pages;
367 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 if (vma->vm_flags & VM_LOCKED) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700369 mm->locked_vm += pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 make_pages_present(addr + old_len,
371 addr + new_len);
372 }
373 ret = addr;
374 goto out;
375 }
376 }
377
378 /*
379 * We weren't able to just expand or shrink the area,
380 * we need to create a new one and move it..
381 */
382 ret = -ENOMEM;
383 if (flags & MREMAP_MAYMOVE) {
384 if (!(flags & MREMAP_FIXED)) {
385 unsigned long map_flags = 0;
386 if (vma->vm_flags & VM_MAYSHARE)
387 map_flags |= MAP_SHARED;
388
389 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
390 vma->vm_pgoff, map_flags);
391 ret = new_addr;
392 if (new_addr & ~PAGE_MASK)
393 goto out;
394 }
395 ret = move_vma(vma, addr, old_len, new_len, new_addr);
396 }
397out:
398 if (ret & ~PAGE_MASK)
399 vm_unacct_memory(charged);
400out_nc:
401 return ret;
402}
403
404asmlinkage unsigned long sys_mremap(unsigned long addr,
405 unsigned long old_len, unsigned long new_len,
406 unsigned long flags, unsigned long new_addr)
407{
408 unsigned long ret;
409
410 down_write(&current->mm->mmap_sem);
411 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
412 up_write(&current->mm->mmap_sem);
413 return ret;
414}