blob: 1903bdf65e428d88e5bf124243d99ee7ab7c51e3 [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>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080016#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/fs.h>
18#include <linux/highmem.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21
22#include <asm/uaccess.h>
23#include <asm/cacheflush.h>
24#include <asm/tlbflush.h>
25
Hugh Dickins7be7a542005-10-29 18:16:00 -070026static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070027{
28 pgd_t *pgd;
29 pud_t *pud;
30 pmd_t *pmd;
31
32 pgd = pgd_offset(mm, addr);
33 if (pgd_none_or_clear_bad(pgd))
34 return NULL;
35
36 pud = pud_offset(pgd, addr);
37 if (pud_none_or_clear_bad(pud))
38 return NULL;
39
40 pmd = pmd_offset(pud, addr);
41 if (pmd_none_or_clear_bad(pmd))
42 return NULL;
43
Hugh Dickins7be7a542005-10-29 18:16:00 -070044 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045}
46
Hugh Dickins7be7a542005-10-29 18:16:00 -070047static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070048{
49 pgd_t *pgd;
50 pud_t *pud;
Hugh Dickinsc74df322005-10-29 18:16:23 -070051 pmd_t *pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53 pgd = pgd_offset(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 pud = pud_alloc(mm, pgd, addr);
55 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -070056 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070057
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 pmd = pmd_alloc(mm, pud, addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -070059 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -070060 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070061
Hugh Dickins1bb36302005-10-29 18:16:22 -070062 if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
Hugh Dickinsc74df322005-10-29 18:16:23 -070063 return NULL;
64
Hugh Dickins7be7a542005-10-29 18:16:00 -070065 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070066}
67
Hugh Dickins7be7a542005-10-29 18:16:00 -070068static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
69 unsigned long old_addr, unsigned long old_end,
70 struct vm_area_struct *new_vma, pmd_t *new_pmd,
71 unsigned long new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070072{
73 struct address_space *mapping = NULL;
74 struct mm_struct *mm = vma->vm_mm;
Hugh Dickins7be7a542005-10-29 18:16:00 -070075 pte_t *old_pte, *new_pte, pte;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070076 spinlock_t *old_ptl, *new_ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
78 if (vma->vm_file) {
79 /*
80 * Subtle point from Rajesh Venkatasubramanian: before
81 * moving file-based ptes, we must lock vmtruncate out,
82 * since it might clean the dst vma before the src vma,
83 * and we propagate stale pages into the dst afterward.
84 */
85 mapping = vma->vm_file->f_mapping;
86 spin_lock(&mapping->i_mmap_lock);
87 if (new_vma->vm_truncate_count &&
88 new_vma->vm_truncate_count != vma->vm_truncate_count)
89 new_vma->vm_truncate_count = 0;
90 }
Hugh Dickins7be7a542005-10-29 18:16:00 -070091
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070092 /*
93 * We don't have to worry about the ordering of src and dst
94 * pte locks because exclusive mmap_sem prevents deadlock.
95 */
Hugh Dickinsc74df322005-10-29 18:16:23 -070096 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
97 new_pte = pte_offset_map_nested(new_pmd, new_addr);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070098 new_ptl = pte_lockptr(mm, new_pmd);
99 if (new_ptl != old_ptl)
100 spin_lock(new_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
Hugh Dickins7be7a542005-10-29 18:16:00 -0700102 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
103 new_pte++, new_addr += PAGE_SIZE) {
104 if (pte_none(*old_pte))
105 continue;
106 pte = ptep_clear_flush(vma, old_addr, old_pte);
107 /* ZERO_PAGE can be dependant on virtual addr */
108 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
109 set_pte_at(mm, new_addr, new_pte, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700111
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700112 if (new_ptl != old_ptl)
113 spin_unlock(new_ptl);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700114 pte_unmap_nested(new_pte - 1);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700115 pte_unmap_unlock(old_pte - 1, old_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 if (mapping)
117 spin_unlock(&mapping->i_mmap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118}
119
Hugh Dickins7be7a542005-10-29 18:16:00 -0700120#define LATENCY_LIMIT (64 * PAGE_SIZE)
121
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122static unsigned long move_page_tables(struct vm_area_struct *vma,
123 unsigned long old_addr, struct vm_area_struct *new_vma,
124 unsigned long new_addr, unsigned long len)
125{
Hugh Dickins7be7a542005-10-29 18:16:00 -0700126 unsigned long extent, next, old_end;
127 pmd_t *old_pmd, *new_pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Hugh Dickins7be7a542005-10-29 18:16:00 -0700129 old_end = old_addr + len;
130 flush_cache_range(vma, old_addr, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Hugh Dickins7be7a542005-10-29 18:16:00 -0700132 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 cond_resched();
Hugh Dickins7be7a542005-10-29 18:16:00 -0700134 next = (old_addr + PMD_SIZE) & PMD_MASK;
135 if (next - 1 > old_end)
136 next = old_end;
137 extent = next - old_addr;
138 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
139 if (!old_pmd)
140 continue;
141 new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
142 if (!new_pmd)
143 break;
144 next = (new_addr + PMD_SIZE) & PMD_MASK;
145 if (extent > next - new_addr)
146 extent = next - new_addr;
147 if (extent > LATENCY_LIMIT)
148 extent = LATENCY_LIMIT;
149 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
150 new_vma, new_pmd, new_addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700152
153 return len + old_addr - old_end; /* how much done */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154}
155
156static unsigned long move_vma(struct vm_area_struct *vma,
157 unsigned long old_addr, unsigned long old_len,
158 unsigned long new_len, unsigned long new_addr)
159{
160 struct mm_struct *mm = vma->vm_mm;
161 struct vm_area_struct *new_vma;
162 unsigned long vm_flags = vma->vm_flags;
163 unsigned long new_pgoff;
164 unsigned long moved_len;
165 unsigned long excess = 0;
Hugh Dickins365e9c872005-10-29 18:16:18 -0700166 unsigned long hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 int split = 0;
168
169 /*
170 * We'd prefer to avoid failure later on in do_munmap:
171 * which may split one vma into three before unmapping.
172 */
173 if (mm->map_count >= sysctl_max_map_count - 3)
174 return -ENOMEM;
175
176 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
177 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
178 if (!new_vma)
179 return -ENOMEM;
180
181 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
182 if (moved_len < old_len) {
183 /*
184 * On error, move entries back from new area to old,
185 * which will succeed since page tables still there,
186 * and then proceed to unmap new area instead of old.
187 */
188 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
189 vma = new_vma;
190 old_len = new_len;
191 old_addr = new_addr;
192 new_addr = -ENOMEM;
193 }
194
195 /* Conceal VM_ACCOUNT so old reservation is not undone */
196 if (vm_flags & VM_ACCOUNT) {
197 vma->vm_flags &= ~VM_ACCOUNT;
198 excess = vma->vm_end - vma->vm_start - old_len;
199 if (old_addr > vma->vm_start &&
200 old_addr + old_len < vma->vm_end)
201 split = 1;
202 }
203
Kirill Korotaev71799062005-05-16 21:53:18 -0700204 /*
Hugh Dickins365e9c872005-10-29 18:16:18 -0700205 * If we failed to move page tables we still do total_vm increment
206 * since do_munmap() will decrement it by old_len == new_len.
207 *
208 * Since total_vm is about to be raised artificially high for a
209 * moment, we need to restore high watermark afterwards: if stats
210 * are taken meanwhile, total_vm and hiwater_vm appear too high.
211 * If this were a serious issue, we'd add a flag to do_munmap().
Kirill Korotaev71799062005-05-16 21:53:18 -0700212 */
Hugh Dickins365e9c872005-10-29 18:16:18 -0700213 hiwater_vm = mm->hiwater_vm;
Kirill Korotaev71799062005-05-16 21:53:18 -0700214 mm->total_vm += new_len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700215 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
Kirill Korotaev71799062005-05-16 21:53:18 -0700216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 if (do_munmap(mm, old_addr, old_len) < 0) {
218 /* OOM: unable to split vma, just get accounts right */
219 vm_unacct_memory(excess >> PAGE_SHIFT);
220 excess = 0;
221 }
Hugh Dickins365e9c872005-10-29 18:16:18 -0700222 mm->hiwater_vm = hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223
224 /* Restore VM_ACCOUNT if one or two pieces of vma left */
225 if (excess) {
226 vma->vm_flags |= VM_ACCOUNT;
227 if (split)
228 vma->vm_next->vm_flags |= VM_ACCOUNT;
229 }
230
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 if (vm_flags & VM_LOCKED) {
232 mm->locked_vm += new_len >> PAGE_SHIFT;
233 if (new_len > old_len)
234 make_pages_present(new_addr + old_len,
235 new_addr + new_len);
236 }
237
238 return new_addr;
239}
240
241/*
242 * Expand (or shrink) an existing mapping, potentially moving it at the
243 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
244 *
245 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
246 * This option implies MREMAP_MAYMOVE.
247 */
248unsigned long do_mremap(unsigned long addr,
249 unsigned long old_len, unsigned long new_len,
250 unsigned long flags, unsigned long new_addr)
251{
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700252 struct mm_struct *mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 struct vm_area_struct *vma;
254 unsigned long ret = -EINVAL;
255 unsigned long charged = 0;
256
257 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
258 goto out;
259
260 if (addr & ~PAGE_MASK)
261 goto out;
262
263 old_len = PAGE_ALIGN(old_len);
264 new_len = PAGE_ALIGN(new_len);
265
266 /*
267 * We allow a zero old-len as a special case
268 * for DOS-emu "duplicate shm area" thing. But
269 * a zero new-len is nonsensical.
270 */
271 if (!new_len)
272 goto out;
273
274 /* new_addr is only valid if MREMAP_FIXED is specified */
275 if (flags & MREMAP_FIXED) {
276 if (new_addr & ~PAGE_MASK)
277 goto out;
278 if (!(flags & MREMAP_MAYMOVE))
279 goto out;
280
281 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
282 goto out;
283
284 /* Check if the location we're moving into overlaps the
285 * old location at all, and fail if it does.
286 */
287 if ((new_addr <= addr) && (new_addr+new_len) > addr)
288 goto out;
289
290 if ((addr <= new_addr) && (addr+old_len) > new_addr)
291 goto out;
292
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700293 ret = do_munmap(mm, new_addr, new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 if (ret)
295 goto out;
296 }
297
298 /*
299 * Always allow a shrinking remap: that just unmaps
300 * the unnecessary pages..
301 * do_munmap does all the needed commit accounting
302 */
303 if (old_len >= new_len) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700304 ret = do_munmap(mm, addr+new_len, old_len - new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 if (ret && old_len != new_len)
306 goto out;
307 ret = addr;
308 if (!(flags & MREMAP_FIXED) || (new_addr == addr))
309 goto out;
310 old_len = new_len;
311 }
312
313 /*
314 * Ok, we need to grow.. or relocate.
315 */
316 ret = -EFAULT;
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700317 vma = find_vma(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 if (!vma || vma->vm_start > addr)
319 goto out;
320 if (is_vm_hugetlb_page(vma)) {
321 ret = -EINVAL;
322 goto out;
323 }
324 /* We can't remap across vm area boundaries */
325 if (old_len > vma->vm_end - addr)
326 goto out;
Linus Torvalds4d7672b2005-12-16 10:21:23 -0800327 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 if (new_len > old_len)
329 goto out;
330 }
331 if (vma->vm_flags & VM_LOCKED) {
332 unsigned long locked, lock_limit;
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700333 locked = mm->locked_vm << PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
335 locked += new_len - old_len;
336 ret = -EAGAIN;
337 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
338 goto out;
339 }
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700340 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
akpm@osdl.org119f6572005-05-01 08:58:35 -0700341 ret = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 goto out;
akpm@osdl.org119f6572005-05-01 08:58:35 -0700343 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345 if (vma->vm_flags & VM_ACCOUNT) {
346 charged = (new_len - old_len) >> PAGE_SHIFT;
347 if (security_vm_enough_memory(charged))
348 goto out_nc;
349 }
350
351 /* old_len exactly to the end of the area..
352 * And we're not relocating the area.
353 */
354 if (old_len == vma->vm_end - addr &&
355 !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
356 (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
357 unsigned long max_addr = TASK_SIZE;
358 if (vma->vm_next)
359 max_addr = vma->vm_next->vm_start;
360 /* can we just expand the current mapping? */
361 if (max_addr - addr >= new_len) {
362 int pages = (new_len - old_len) >> PAGE_SHIFT;
363
364 vma_adjust(vma, vma->vm_start,
365 addr + new_len, vma->vm_pgoff, NULL);
366
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700367 mm->total_vm += pages;
368 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 if (vma->vm_flags & VM_LOCKED) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700370 mm->locked_vm += pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 make_pages_present(addr + old_len,
372 addr + new_len);
373 }
374 ret = addr;
375 goto out;
376 }
377 }
378
379 /*
380 * We weren't able to just expand or shrink the area,
381 * we need to create a new one and move it..
382 */
383 ret = -ENOMEM;
384 if (flags & MREMAP_MAYMOVE) {
385 if (!(flags & MREMAP_FIXED)) {
386 unsigned long map_flags = 0;
387 if (vma->vm_flags & VM_MAYSHARE)
388 map_flags |= MAP_SHARED;
389
390 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
391 vma->vm_pgoff, map_flags);
392 ret = new_addr;
393 if (new_addr & ~PAGE_MASK)
394 goto out;
395 }
396 ret = move_vma(vma, addr, old_len, new_len, new_addr);
397 }
398out:
399 if (ret & ~PAGE_MASK)
400 vm_unacct_memory(charged);
401out_nc:
402 return ret;
403}
404
405asmlinkage unsigned long sys_mremap(unsigned long addr,
406 unsigned long old_len, unsigned long new_len,
407 unsigned long flags, unsigned long new_addr)
408{
409 unsigned long ret;
410
411 down_write(&current->mm->mmap_sem);
412 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
413 up_write(&current->mm->mmap_sem);
414 return ret;
415}