blob: 506fa44403df5cc3215cb69ec2d1098a96bb7919 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
Alan Cox046c6882009-01-05 14:06:29 +00006 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
9
10#include <linux/mm.h>
11#include <linux/hugetlb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/shm.h>
Hugh Dickins1ff82992009-09-21 17:02:05 -070013#include <linux/ksm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#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>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070021#include <linux/mmu_notifier.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
23#include <asm/uaccess.h>
24#include <asm/cacheflush.h>
25#include <asm/tlbflush.h>
26
Rik van Rielba470de2008-10-18 20:26:50 -070027#include "internal.h"
28
Hugh Dickins7be7a542005-10-29 18:16:00 -070029static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030{
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);
Andrea Arcangelibae9c192011-01-13 15:46:46 -080044 split_huge_page_pmd(mm, pmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 if (pmd_none_or_clear_bad(pmd))
46 return NULL;
47
Hugh Dickins7be7a542005-10-29 18:16:00 -070048 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070049}
50
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080051static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
52 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070053{
54 pgd_t *pgd;
55 pud_t *pud;
Hugh Dickinsc74df322005-10-29 18:16:23 -070056 pmd_t *pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
58 pgd = pgd_offset(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 pud = pud_alloc(mm, pgd, addr);
60 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -070061 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070062
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 pmd = pmd_alloc(mm, pud, addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -070064 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -070065 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070066
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080067 VM_BUG_ON(pmd_trans_huge(*pmd));
68 if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
Hugh Dickinsc74df322005-10-29 18:16:23 -070069 return NULL;
70
Hugh Dickins7be7a542005-10-29 18:16:00 -070071 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070072}
73
Hugh Dickins7be7a542005-10-29 18:16:00 -070074static 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)
Linus Torvalds1da177e2005-04-16 15:20:36 -070078{
79 struct address_space *mapping = NULL;
80 struct mm_struct *mm = vma->vm_mm;
Hugh Dickins7be7a542005-10-29 18:16:00 -070081 pte_t *old_pte, *new_pte, pte;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070082 spinlock_t *old_ptl, *new_ptl;
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070083 unsigned long old_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070085 old_start = old_addr;
86 mmu_notifier_invalidate_range_start(vma->vm_mm,
87 old_start, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 if (vma->vm_file) {
89 /*
90 * Subtle point from Rajesh Venkatasubramanian: before
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100091 * moving file-based ptes, we must lock truncate_pagecache
92 * out, since it might clean the dst vma before the src vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 * and we propagate stale pages into the dst afterward.
94 */
95 mapping = vma->vm_file->f_mapping;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070096 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 }
Hugh Dickins7be7a542005-10-29 18:16:00 -070098
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070099 /*
100 * We don't have to worry about the ordering of src and dst
101 * pte locks because exclusive mmap_sem prevents deadlock.
102 */
Hugh Dickinsc74df322005-10-29 18:16:23 -0700103 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700104 new_pte = pte_offset_map(new_pmd, new_addr);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700105 new_ptl = pte_lockptr(mm, new_pmd);
106 if (new_ptl != old_ptl)
Ingo Molnarf20dc5f2006-07-03 00:25:08 -0700107 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700108 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109
Hugh Dickins7be7a542005-10-29 18:16:00 -0700110 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);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700115 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
116 set_pte_at(mm, new_addr, new_pte, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700118
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700119 arch_leave_lazy_mmu_mode();
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700120 if (new_ptl != old_ptl)
121 spin_unlock(new_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700122 pte_unmap(new_pte - 1);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700123 pte_unmap_unlock(old_pte - 1, old_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 if (mapping)
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700125 mutex_unlock(&mapping->i_mmap_mutex);
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700126 mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
128
Hugh Dickins7be7a542005-10-29 18:16:00 -0700129#define LATENCY_LIMIT (64 * PAGE_SIZE)
130
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700131unsigned long move_page_tables(struct vm_area_struct *vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 unsigned long old_addr, struct vm_area_struct *new_vma,
133 unsigned long new_addr, unsigned long len)
134{
Hugh Dickins7be7a542005-10-29 18:16:00 -0700135 unsigned long extent, next, old_end;
136 pmd_t *old_pmd, *new_pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
Hugh Dickins7be7a542005-10-29 18:16:00 -0700138 old_end = old_addr + len;
139 flush_cache_range(vma, old_addr, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
Hugh Dickins7be7a542005-10-29 18:16:00 -0700141 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 cond_resched();
Hugh Dickins7be7a542005-10-29 18:16:00 -0700143 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;
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800150 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700151 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700161
162 return len + old_addr - old_end; /* how much done */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163}
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;
Hugh Dickins365e9c872005-10-29 18:16:18 -0700175 unsigned long hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 int split = 0;
Hugh Dickins7103ad32009-09-21 17:02:28 -0700177 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
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
Hugh Dickins1ff82992009-09-21 17:02:05 -0700186 /*
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 */
Hugh Dickins7103ad32009-09-21 17:02:28 -0700193 err = ksm_madvise(vma, old_addr, old_addr + old_len,
194 MADV_UNMERGEABLE, &vm_flags);
195 if (err)
196 return err;
Hugh Dickins1ff82992009-09-21 17:02:05 -0700197
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 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
Kirill Korotaev71799062005-05-16 21:53:18 -0700226 /*
Hugh Dickins365e9c872005-10-29 18:16:18 -0700227 * 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().
Kirill Korotaev71799062005-05-16 21:53:18 -0700234 */
Hugh Dickins365e9c872005-10-29 18:16:18 -0700235 hiwater_vm = mm->hiwater_vm;
Kirill Korotaev71799062005-05-16 21:53:18 -0700236 mm->total_vm += new_len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700237 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
Kirill Korotaev71799062005-05-16 21:53:18 -0700238
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 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 }
Hugh Dickins365e9c872005-10-29 18:16:18 -0700244 mm->hiwater_vm = hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 if (vm_flags & VM_LOCKED) {
254 mm->locked_vm += new_len >> PAGE_SHIFT;
255 if (new_len > old_len)
Rik van Rielba470de2008-10-18 20:26:50 -0700256 mlock_vma_pages_range(new_vma, new_addr + old_len,
257 new_addr + new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 }
259
260 return new_addr;
261}
262
Al Viro54f5de72009-11-24 07:17:46 -0500263static 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
Linus Torvalds982134b2011-04-07 07:35:50 -0700279 /* 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))
Al Viro54f5de72009-11-24 07:17:46 -0500284 goto Efault;
Linus Torvalds982134b2011-04-07 07:35:50 -0700285 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
286 pgoff += vma->vm_pgoff;
287 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
288 goto Einval;
Al Viro54f5de72009-11-24 07:17:46 -0500289 }
290
291 if (vma->vm_flags & VM_LOCKED) {
292 unsigned long locked, lock_limit;
293 locked = mm->locked_vm << PAGE_SHIFT;
Jiri Slaby59e99e52010-03-05 13:41:44 -0800294 lock_limit = rlimit(RLIMIT_MEMLOCK);
Al Viro54f5de72009-11-24 07:17:46 -0500295 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
Al Viroecc1a892009-11-24 07:28:07 -0500322static 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;
Al Viro097eed12009-11-24 08:43:52 -0500330 unsigned long map_flags;
Al Viroecc1a892009-11-24 07:28:07 -0500331
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
Al Viro097eed12009-11-24 08:43:52 -0500368 map_flags = MAP_FIXED;
369 if (vma->vm_flags & VM_MAYSHARE)
370 map_flags |= MAP_SHARED;
Al Viro9206de92009-12-03 15:23:11 -0500371
Al Viro097eed12009-11-24 08:43:52 -0500372 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
373 ((addr - vma->vm_start) >> PAGE_SHIFT),
374 map_flags);
Al Viroecc1a892009-11-24 07:28:07 -0500375 if (ret & ~PAGE_MASK)
Al Viro097eed12009-11-24 08:43:52 -0500376 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);
Al Viroecc1a892009-11-24 07:28:07 -0500383
384out:
385 return ret;
386}
387
Al Viro1a0ef852009-11-24 07:43:18 -0500388static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
389{
Al Virof106af42009-11-24 08:25:18 -0500390 unsigned long end = vma->vm_end + delta;
Al Viro9206de92009-12-03 15:23:11 -0500391 if (end < vma->vm_end) /* overflow */
Al Viro1a0ef852009-11-24 07:43:18 -0500392 return 0;
Al Viro9206de92009-12-03 15:23:11 -0500393 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
Al Virof106af42009-11-24 08:25:18 -0500394 return 0;
395 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
396 0, MAP_FIXED) & ~PAGE_MASK)
397 return 0;
Al Viro1a0ef852009-11-24 07:43:18 -0500398 return 1;
399}
400
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401/*
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{
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700412 struct mm_struct *mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 if (flags & MREMAP_FIXED) {
Al Viroecc1a892009-11-24 07:28:07 -0500435 if (flags & MREMAP_MAYMOVE)
436 ret = mremap_to(addr, old_len, new_addr, new_len);
437 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 }
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) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700446 ret = do_munmap(mm, addr+new_len, old_len - new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 if (ret && old_len != new_len)
448 goto out;
449 ret = addr;
Al Viroecc1a892009-11-24 07:28:07 -0500450 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 }
452
453 /*
Al Viroecc1a892009-11-24 07:28:07 -0500454 * Ok, we need to grow..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 */
Al Viro54f5de72009-11-24 07:17:46 -0500456 vma = vma_to_resize(addr, old_len, new_len, &charged);
457 if (IS_ERR(vma)) {
458 ret = PTR_ERR(vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 }
461
462 /* old_len exactly to the end of the area..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 */
Al Viroecc1a892009-11-24 07:28:07 -0500464 if (old_len == vma->vm_end - addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 /* can we just expand the current mapping? */
Al Viro1a0ef852009-11-24 07:43:18 -0500466 if (vma_expandable(vma, new_len - old_len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 int pages = (new_len - old_len) >> PAGE_SHIFT;
468
Rik van Riel5beb4932010-03-05 13:42:07 -0800469 if (vma_adjust(vma, vma->vm_start, addr + new_len,
470 vma->vm_pgoff, NULL)) {
471 ret = -ENOMEM;
472 goto out;
473 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700475 mm->total_vm += pages;
476 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 if (vma->vm_flags & VM_LOCKED) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700478 mm->locked_vm += pages;
Rik van Rielba470de2008-10-18 20:26:50 -0700479 mlock_vma_pages_range(vma, addr + old_len,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 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) {
Al Viroecc1a892009-11-24 07:28:07 -0500493 unsigned long map_flags = 0;
494 if (vma->vm_flags & VM_MAYSHARE)
495 map_flags |= MAP_SHARED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496
Al Viroecc1a892009-11-24 07:28:07 -0500497 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
Al Viro93587412009-11-24 08:45:24 -0500498 vma->vm_pgoff +
499 ((addr - vma->vm_start) >> PAGE_SHIFT),
500 map_flags);
Al Viroecc1a892009-11-24 07:28:07 -0500501 if (new_addr & ~PAGE_MASK) {
502 ret = new_addr;
503 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 }
Al Viroecc1a892009-11-24 07:28:07 -0500505
506 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
507 if (ret)
508 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 ret = move_vma(vma, addr, old_len, new_len, new_addr);
510 }
511out:
512 if (ret & ~PAGE_MASK)
513 vm_unacct_memory(charged);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 return ret;
515}
516
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100517SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
518 unsigned long, new_len, unsigned long, flags,
519 unsigned long, new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520{
521 unsigned long ret;
522
523 down_write(&current->mm->mmap_sem);
524 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
525 up_write(&current->mm->mmap_sem);
526 return ret;
527}