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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 Arcangeli37a1c492011-10-31 17:08:30 -070044 if (pmd_none(*pmd))
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 return NULL;
46
Hugh Dickins7be7a542005-10-29 18:16:00 -070047 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048}
49
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080050static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
51 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070052{
53 pgd_t *pgd;
54 pud_t *pud;
Hugh Dickinsc74df322005-10-29 18:16:23 -070055 pmd_t *pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57 pgd = pgd_offset(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 pud = pud_alloc(mm, pgd, addr);
59 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -070060 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070061
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 pmd = pmd_alloc(mm, pud, addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -070063 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -070064 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070065
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080066 VM_BUG_ON(pmd_trans_huge(*pmd));
Hugh Dickinsc74df322005-10-29 18:16:23 -070067
Hugh Dickins7be7a542005-10-29 18:16:00 -070068 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070069}
70
Hugh Dickins7be7a542005-10-29 18:16:00 -070071static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
72 unsigned long old_addr, unsigned long old_end,
73 struct vm_area_struct *new_vma, pmd_t *new_pmd,
74 unsigned long new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075{
76 struct address_space *mapping = NULL;
77 struct mm_struct *mm = vma->vm_mm;
Hugh Dickins7be7a542005-10-29 18:16:00 -070078 pte_t *old_pte, *new_pte, pte;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070079 spinlock_t *old_ptl, *new_ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
81 if (vma->vm_file) {
82 /*
83 * Subtle point from Rajesh Venkatasubramanian: before
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100084 * moving file-based ptes, we must lock truncate_pagecache
85 * out, since it might clean the dst vma before the src vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 * and we propagate stale pages into the dst afterward.
87 */
88 mapping = vma->vm_file->f_mapping;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070089 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 }
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);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -070097 new_pte = pte_offset_map(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)
Ingo Molnarf20dc5f2006-07-03 00:25:08 -0700100 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700101 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
Hugh Dickins7be7a542005-10-29 18:16:00 -0700103 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
104 new_pte++, new_addr += PAGE_SIZE) {
105 if (pte_none(*old_pte))
106 continue;
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700107 pte = ptep_get_and_clear(mm, old_addr, old_pte);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700108 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
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700112 arch_leave_lazy_mmu_mode();
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700113 if (new_ptl != old_ptl)
114 spin_unlock(new_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700115 pte_unmap(new_pte - 1);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700116 pte_unmap_unlock(old_pte - 1, old_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 if (mapping)
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700118 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119}
120
Hugh Dickins7be7a542005-10-29 18:16:00 -0700121#define LATENCY_LIMIT (64 * PAGE_SIZE)
122
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700123unsigned long move_page_tables(struct vm_area_struct *vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 unsigned long old_addr, struct vm_area_struct *new_vma,
125 unsigned long new_addr, unsigned long len)
126{
Hugh Dickins7be7a542005-10-29 18:16:00 -0700127 unsigned long extent, next, old_end;
128 pmd_t *old_pmd, *new_pmd;
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700129 bool need_flush = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Hugh Dickins7be7a542005-10-29 18:16:00 -0700131 old_end = old_addr + len;
132 flush_cache_range(vma, old_addr, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700134 mmu_notifier_invalidate_range_start(vma->vm_mm, old_addr, old_end);
135
Hugh Dickins7be7a542005-10-29 18:16:00 -0700136 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 cond_resched();
Hugh Dickins7be7a542005-10-29 18:16:00 -0700138 next = (old_addr + PMD_SIZE) & PMD_MASK;
Andrea Arcangeliebed4842011-10-31 17:08:22 -0700139 /* even if next overflowed, extent below will be ok */
Hugh Dickins7be7a542005-10-29 18:16:00 -0700140 extent = next - old_addr;
Andrea Arcangeliebed4842011-10-31 17:08:22 -0700141 if (extent > old_end - old_addr)
142 extent = old_end - old_addr;
Hugh Dickins7be7a542005-10-29 18:16:00 -0700143 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
144 if (!old_pmd)
145 continue;
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800146 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700147 if (!new_pmd)
148 break;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -0700149 if (pmd_trans_huge(*old_pmd)) {
150 int err = 0;
151 if (extent == HPAGE_PMD_SIZE)
152 err = move_huge_pmd(vma, new_vma, old_addr,
153 new_addr, old_end,
154 old_pmd, new_pmd);
155 if (err > 0) {
156 need_flush = true;
157 continue;
158 } else if (!err) {
159 split_huge_page_pmd(vma->vm_mm, old_pmd);
160 }
161 VM_BUG_ON(pmd_trans_huge(*old_pmd));
162 }
163 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
164 new_pmd, new_addr))
165 break;
Hugh Dickins7be7a542005-10-29 18:16:00 -0700166 next = (new_addr + PMD_SIZE) & PMD_MASK;
167 if (extent > next - new_addr)
168 extent = next - new_addr;
169 if (extent > LATENCY_LIMIT)
170 extent = LATENCY_LIMIT;
171 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
172 new_vma, new_pmd, new_addr);
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700173 need_flush = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 }
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700175 if (likely(need_flush))
176 flush_tlb_range(vma, old_end-len, old_addr);
177
178 mmu_notifier_invalidate_range_end(vma->vm_mm, old_end-len, old_end);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700179
180 return len + old_addr - old_end; /* how much done */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181}
182
183static unsigned long move_vma(struct vm_area_struct *vma,
184 unsigned long old_addr, unsigned long old_len,
185 unsigned long new_len, unsigned long new_addr)
186{
187 struct mm_struct *mm = vma->vm_mm;
188 struct vm_area_struct *new_vma;
189 unsigned long vm_flags = vma->vm_flags;
190 unsigned long new_pgoff;
191 unsigned long moved_len;
192 unsigned long excess = 0;
Hugh Dickins365e9c872005-10-29 18:16:18 -0700193 unsigned long hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 int split = 0;
Hugh Dickins7103ad32009-09-21 17:02:28 -0700195 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
197 /*
198 * We'd prefer to avoid failure later on in do_munmap:
199 * which may split one vma into three before unmapping.
200 */
201 if (mm->map_count >= sysctl_max_map_count - 3)
202 return -ENOMEM;
203
Hugh Dickins1ff82992009-09-21 17:02:05 -0700204 /*
205 * Advise KSM to break any KSM pages in the area to be moved:
206 * it would be confusing if they were to turn up at the new
207 * location, where they happen to coincide with different KSM
208 * pages recently unmapped. But leave vma->vm_flags as it was,
209 * so KSM can come around to merge on vma and new_vma afterwards.
210 */
Hugh Dickins7103ad32009-09-21 17:02:28 -0700211 err = ksm_madvise(vma, old_addr, old_addr + old_len,
212 MADV_UNMERGEABLE, &vm_flags);
213 if (err)
214 return err;
Hugh Dickins1ff82992009-09-21 17:02:05 -0700215
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
217 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
218 if (!new_vma)
219 return -ENOMEM;
220
221 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
222 if (moved_len < old_len) {
223 /*
Andrea Arcangeli948f0172012-01-10 15:08:05 -0800224 * Before moving the page tables from the new vma to
225 * the old vma, we need to be sure the old vma is
226 * queued after new vma in the same_anon_vma list to
227 * prevent SMP races with rmap_walk (that could lead
228 * rmap_walk to miss some page table).
229 */
230 anon_vma_moveto_tail(vma);
231
232 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 * On error, move entries back from new area to old,
234 * which will succeed since page tables still there,
235 * and then proceed to unmap new area instead of old.
236 */
237 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
238 vma = new_vma;
239 old_len = new_len;
240 old_addr = new_addr;
241 new_addr = -ENOMEM;
242 }
243
244 /* Conceal VM_ACCOUNT so old reservation is not undone */
245 if (vm_flags & VM_ACCOUNT) {
246 vma->vm_flags &= ~VM_ACCOUNT;
247 excess = vma->vm_end - vma->vm_start - old_len;
248 if (old_addr > vma->vm_start &&
249 old_addr + old_len < vma->vm_end)
250 split = 1;
251 }
252
Kirill Korotaev71799062005-05-16 21:53:18 -0700253 /*
Hugh Dickins365e9c872005-10-29 18:16:18 -0700254 * If we failed to move page tables we still do total_vm increment
255 * since do_munmap() will decrement it by old_len == new_len.
256 *
257 * Since total_vm is about to be raised artificially high for a
258 * moment, we need to restore high watermark afterwards: if stats
259 * are taken meanwhile, total_vm and hiwater_vm appear too high.
260 * If this were a serious issue, we'd add a flag to do_munmap().
Kirill Korotaev71799062005-05-16 21:53:18 -0700261 */
Hugh Dickins365e9c872005-10-29 18:16:18 -0700262 hiwater_vm = mm->hiwater_vm;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700263 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
Kirill Korotaev71799062005-05-16 21:53:18 -0700264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 if (do_munmap(mm, old_addr, old_len) < 0) {
266 /* OOM: unable to split vma, just get accounts right */
267 vm_unacct_memory(excess >> PAGE_SHIFT);
268 excess = 0;
269 }
Hugh Dickins365e9c872005-10-29 18:16:18 -0700270 mm->hiwater_vm = hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
272 /* Restore VM_ACCOUNT if one or two pieces of vma left */
273 if (excess) {
274 vma->vm_flags |= VM_ACCOUNT;
275 if (split)
276 vma->vm_next->vm_flags |= VM_ACCOUNT;
277 }
278
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 if (vm_flags & VM_LOCKED) {
280 mm->locked_vm += new_len >> PAGE_SHIFT;
281 if (new_len > old_len)
Rik van Rielba470de2008-10-18 20:26:50 -0700282 mlock_vma_pages_range(new_vma, new_addr + old_len,
283 new_addr + new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 }
285
286 return new_addr;
287}
288
Al Viro54f5de72009-11-24 07:17:46 -0500289static struct vm_area_struct *vma_to_resize(unsigned long addr,
290 unsigned long old_len, unsigned long new_len, unsigned long *p)
291{
292 struct mm_struct *mm = current->mm;
293 struct vm_area_struct *vma = find_vma(mm, addr);
294
295 if (!vma || vma->vm_start > addr)
296 goto Efault;
297
298 if (is_vm_hugetlb_page(vma))
299 goto Einval;
300
301 /* We can't remap across vm area boundaries */
302 if (old_len > vma->vm_end - addr)
303 goto Efault;
304
Linus Torvalds982134b2011-04-07 07:35:50 -0700305 /* Need to be careful about a growing mapping */
306 if (new_len > old_len) {
307 unsigned long pgoff;
308
309 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
Al Viro54f5de72009-11-24 07:17:46 -0500310 goto Efault;
Linus Torvalds982134b2011-04-07 07:35:50 -0700311 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
312 pgoff += vma->vm_pgoff;
313 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
314 goto Einval;
Al Viro54f5de72009-11-24 07:17:46 -0500315 }
316
317 if (vma->vm_flags & VM_LOCKED) {
318 unsigned long locked, lock_limit;
319 locked = mm->locked_vm << PAGE_SHIFT;
Jiri Slaby59e99e52010-03-05 13:41:44 -0800320 lock_limit = rlimit(RLIMIT_MEMLOCK);
Al Viro54f5de72009-11-24 07:17:46 -0500321 locked += new_len - old_len;
322 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
323 goto Eagain;
324 }
325
326 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
327 goto Enomem;
328
329 if (vma->vm_flags & VM_ACCOUNT) {
330 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
Al Viro191c5422012-02-13 03:58:52 +0000331 if (security_vm_enough_memory_mm(mm, charged))
Al Viro54f5de72009-11-24 07:17:46 -0500332 goto Efault;
333 *p = charged;
334 }
335
336 return vma;
337
338Efault: /* very odd choice for most of the cases, but... */
339 return ERR_PTR(-EFAULT);
340Einval:
341 return ERR_PTR(-EINVAL);
342Enomem:
343 return ERR_PTR(-ENOMEM);
344Eagain:
345 return ERR_PTR(-EAGAIN);
346}
347
Al Viroecc1a892009-11-24 07:28:07 -0500348static unsigned long mremap_to(unsigned long addr,
349 unsigned long old_len, unsigned long new_addr,
350 unsigned long new_len)
351{
352 struct mm_struct *mm = current->mm;
353 struct vm_area_struct *vma;
354 unsigned long ret = -EINVAL;
355 unsigned long charged = 0;
Al Viro097eed12009-11-24 08:43:52 -0500356 unsigned long map_flags;
Al Viroecc1a892009-11-24 07:28:07 -0500357
358 if (new_addr & ~PAGE_MASK)
359 goto out;
360
361 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
362 goto out;
363
364 /* Check if the location we're moving into overlaps the
365 * old location at all, and fail if it does.
366 */
367 if ((new_addr <= addr) && (new_addr+new_len) > addr)
368 goto out;
369
370 if ((addr <= new_addr) && (addr+old_len) > new_addr)
371 goto out;
372
Al Viroecc1a892009-11-24 07:28:07 -0500373 ret = do_munmap(mm, new_addr, new_len);
374 if (ret)
375 goto out;
376
377 if (old_len >= new_len) {
378 ret = do_munmap(mm, addr+new_len, old_len - new_len);
379 if (ret && old_len != new_len)
380 goto out;
381 old_len = new_len;
382 }
383
384 vma = vma_to_resize(addr, old_len, new_len, &charged);
385 if (IS_ERR(vma)) {
386 ret = PTR_ERR(vma);
387 goto out;
388 }
389
Al Viro097eed12009-11-24 08:43:52 -0500390 map_flags = MAP_FIXED;
391 if (vma->vm_flags & VM_MAYSHARE)
392 map_flags |= MAP_SHARED;
Al Viro9206de92009-12-03 15:23:11 -0500393
Al Viro097eed12009-11-24 08:43:52 -0500394 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
395 ((addr - vma->vm_start) >> PAGE_SHIFT),
396 map_flags);
Al Viroecc1a892009-11-24 07:28:07 -0500397 if (ret & ~PAGE_MASK)
Al Viro097eed12009-11-24 08:43:52 -0500398 goto out1;
399
400 ret = move_vma(vma, addr, old_len, new_len, new_addr);
401 if (!(ret & ~PAGE_MASK))
402 goto out;
403out1:
404 vm_unacct_memory(charged);
Al Viroecc1a892009-11-24 07:28:07 -0500405
406out:
407 return ret;
408}
409
Al Viro1a0ef852009-11-24 07:43:18 -0500410static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
411{
Al Virof106af42009-11-24 08:25:18 -0500412 unsigned long end = vma->vm_end + delta;
Al Viro9206de92009-12-03 15:23:11 -0500413 if (end < vma->vm_end) /* overflow */
Al Viro1a0ef852009-11-24 07:43:18 -0500414 return 0;
Al Viro9206de92009-12-03 15:23:11 -0500415 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
Al Virof106af42009-11-24 08:25:18 -0500416 return 0;
417 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
418 0, MAP_FIXED) & ~PAGE_MASK)
419 return 0;
Al Viro1a0ef852009-11-24 07:43:18 -0500420 return 1;
421}
422
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423/*
424 * Expand (or shrink) an existing mapping, potentially moving it at the
425 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
426 *
427 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
428 * This option implies MREMAP_MAYMOVE.
429 */
Al Viro63a81db2012-05-30 11:32:04 -0400430SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
431 unsigned long, new_len, unsigned long, flags,
432 unsigned long, new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433{
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700434 struct mm_struct *mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 struct vm_area_struct *vma;
436 unsigned long ret = -EINVAL;
437 unsigned long charged = 0;
438
Al Viro63a81db2012-05-30 11:32:04 -0400439 down_write(&current->mm->mmap_sem);
440
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
442 goto out;
443
444 if (addr & ~PAGE_MASK)
445 goto out;
446
447 old_len = PAGE_ALIGN(old_len);
448 new_len = PAGE_ALIGN(new_len);
449
450 /*
451 * We allow a zero old-len as a special case
452 * for DOS-emu "duplicate shm area" thing. But
453 * a zero new-len is nonsensical.
454 */
455 if (!new_len)
456 goto out;
457
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 if (flags & MREMAP_FIXED) {
Al Viroecc1a892009-11-24 07:28:07 -0500459 if (flags & MREMAP_MAYMOVE)
460 ret = mremap_to(addr, old_len, new_addr, new_len);
461 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 }
463
464 /*
465 * Always allow a shrinking remap: that just unmaps
466 * the unnecessary pages..
467 * do_munmap does all the needed commit accounting
468 */
469 if (old_len >= new_len) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700470 ret = do_munmap(mm, addr+new_len, old_len - new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 if (ret && old_len != new_len)
472 goto out;
473 ret = addr;
Al Viroecc1a892009-11-24 07:28:07 -0500474 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 }
476
477 /*
Al Viroecc1a892009-11-24 07:28:07 -0500478 * Ok, we need to grow..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 */
Al Viro54f5de72009-11-24 07:17:46 -0500480 vma = vma_to_resize(addr, old_len, new_len, &charged);
481 if (IS_ERR(vma)) {
482 ret = PTR_ERR(vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 }
485
486 /* old_len exactly to the end of the area..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 */
Al Viroecc1a892009-11-24 07:28:07 -0500488 if (old_len == vma->vm_end - addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 /* can we just expand the current mapping? */
Al Viro1a0ef852009-11-24 07:43:18 -0500490 if (vma_expandable(vma, new_len - old_len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 int pages = (new_len - old_len) >> PAGE_SHIFT;
492
Rik van Riel5beb4932010-03-05 13:42:07 -0800493 if (vma_adjust(vma, vma->vm_start, addr + new_len,
494 vma->vm_pgoff, NULL)) {
495 ret = -ENOMEM;
496 goto out;
497 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700499 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 if (vma->vm_flags & VM_LOCKED) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700501 mm->locked_vm += pages;
Rik van Rielba470de2008-10-18 20:26:50 -0700502 mlock_vma_pages_range(vma, addr + old_len,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 addr + new_len);
504 }
505 ret = addr;
506 goto out;
507 }
508 }
509
510 /*
511 * We weren't able to just expand or shrink the area,
512 * we need to create a new one and move it..
513 */
514 ret = -ENOMEM;
515 if (flags & MREMAP_MAYMOVE) {
Al Viroecc1a892009-11-24 07:28:07 -0500516 unsigned long map_flags = 0;
517 if (vma->vm_flags & VM_MAYSHARE)
518 map_flags |= MAP_SHARED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
Al Viroecc1a892009-11-24 07:28:07 -0500520 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
Al Viro93587412009-11-24 08:45:24 -0500521 vma->vm_pgoff +
522 ((addr - vma->vm_start) >> PAGE_SHIFT),
523 map_flags);
Al Viroecc1a892009-11-24 07:28:07 -0500524 if (new_addr & ~PAGE_MASK) {
525 ret = new_addr;
526 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 }
Al Viroecc1a892009-11-24 07:28:07 -0500528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 ret = move_vma(vma, addr, old_len, new_len, new_addr);
530 }
531out:
532 if (ret & ~PAGE_MASK)
533 vm_unacct_memory(charged);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 up_write(&current->mm->mmap_sem);
535 return ret;
536}