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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>
Cyrill Gorcunov6dec97d2013-08-27 12:37:18 +040018#include <linux/swapops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/highmem.h>
20#include <linux/security.h>
21#include <linux/syscalls.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070022#include <linux/mmu_notifier.h>
Paul McQuade2581d202014-10-09 15:29:01 -070023#include <linux/uaccess.h>
Laurent Dufour4abad2c2015-06-24 16:56:19 -070024#include <linux/mm-arch-hooks.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <asm/cacheflush.h>
27#include <asm/tlbflush.h>
28
Rik van Rielba470de2008-10-18 20:26:50 -070029#include "internal.h"
30
Hugh Dickins7be7a542005-10-29 18:16:00 -070031static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070032{
33 pgd_t *pgd;
34 pud_t *pud;
35 pmd_t *pmd;
36
37 pgd = pgd_offset(mm, addr);
38 if (pgd_none_or_clear_bad(pgd))
39 return NULL;
40
41 pud = pud_offset(pgd, addr);
42 if (pud_none_or_clear_bad(pud))
43 return NULL;
44
45 pmd = pmd_offset(pud, addr);
Andrea Arcangeli37a1c492011-10-31 17:08:30 -070046 if (pmd_none(*pmd))
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 return NULL;
48
Hugh Dickins7be7a542005-10-29 18:16:00 -070049 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050}
51
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080052static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
53 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070054{
55 pgd_t *pgd;
56 pud_t *pud;
Hugh Dickinsc74df322005-10-29 18:16:23 -070057 pmd_t *pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59 pgd = pgd_offset(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 pud = pud_alloc(mm, pgd, addr);
61 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -070062 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 pmd = pmd_alloc(mm, pud, addr);
Hugh Dickins57a8f0c2013-10-16 13:47:09 -070065 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -070066 return NULL;
Hugh Dickins7be7a542005-10-29 18:16:00 -070067
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -080068 VM_BUG_ON(pmd_trans_huge(*pmd));
Hugh Dickinsc74df322005-10-29 18:16:23 -070069
Hugh Dickins7be7a542005-10-29 18:16:00 -070070 return pmd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071}
72
Hugh Dickins1d069b72016-05-19 17:12:57 -070073static void take_rmap_locks(struct vm_area_struct *vma)
74{
75 if (vma->vm_file)
76 i_mmap_lock_write(vma->vm_file->f_mapping);
77 if (vma->anon_vma)
78 anon_vma_lock_write(vma->anon_vma);
79}
80
81static void drop_rmap_locks(struct vm_area_struct *vma)
82{
83 if (vma->anon_vma)
84 anon_vma_unlock_write(vma->anon_vma);
85 if (vma->vm_file)
86 i_mmap_unlock_write(vma->vm_file->f_mapping);
87}
88
Cyrill Gorcunov6dec97d2013-08-27 12:37:18 +040089static pte_t move_soft_dirty_pte(pte_t pte)
90{
91 /*
92 * Set soft dirty bit so we can notice
93 * in userspace the ptes were moved.
94 */
95#ifdef CONFIG_MEM_SOFT_DIRTY
96 if (pte_present(pte))
97 pte = pte_mksoft_dirty(pte);
98 else if (is_swap_pte(pte))
99 pte = pte_swp_mksoft_dirty(pte);
Cyrill Gorcunov6dec97d2013-08-27 12:37:18 +0400100#endif
101 return pte;
102}
103
Hugh Dickins7be7a542005-10-29 18:16:00 -0700104static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
105 unsigned long old_addr, unsigned long old_end,
106 struct vm_area_struct *new_vma, pmd_t *new_pmd,
Michel Lespinasse38a76012012-10-08 16:31:50 -0700107 unsigned long new_addr, bool need_rmap_locks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 struct mm_struct *mm = vma->vm_mm;
Hugh Dickins7be7a542005-10-29 18:16:00 -0700110 pte_t *old_pte, *new_pte, pte;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700111 spinlock_t *old_ptl, *new_ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
Michel Lespinasse38a76012012-10-08 16:31:50 -0700113 /*
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -0800114 * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
Michel Lespinasse38a76012012-10-08 16:31:50 -0700115 * locks to ensure that rmap will always observe either the old or the
116 * new ptes. This is the easiest way to avoid races with
117 * truncate_pagecache(), page migration, etc...
118 *
119 * When need_rmap_locks is false, we use other ways to avoid
120 * such races:
121 *
122 * - During exec() shift_arg_pages(), we use a specially tagged vma
123 * which rmap call sites look for using is_vma_temporary_stack().
124 *
125 * - During mremap(), new_vma is often known to be placed after vma
126 * in rmap traversal order. This ensures rmap will always observe
127 * either the old pte, or the new pte, or both (the page table locks
128 * serialize access to individual ptes, but only rmap traversal
129 * order guarantees that we won't miss both the old and new ptes).
130 */
Hugh Dickins1d069b72016-05-19 17:12:57 -0700131 if (need_rmap_locks)
132 take_rmap_locks(vma);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700133
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700134 /*
135 * We don't have to worry about the ordering of src and dst
136 * pte locks because exclusive mmap_sem prevents deadlock.
137 */
Hugh Dickinsc74df322005-10-29 18:16:23 -0700138 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700139 new_pte = pte_offset_map(new_pmd, new_addr);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700140 new_ptl = pte_lockptr(mm, new_pmd);
141 if (new_ptl != old_ptl)
Ingo Molnarf20dc5f2006-07-03 00:25:08 -0700142 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700143 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Hugh Dickins7be7a542005-10-29 18:16:00 -0700145 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
146 new_pte++, new_addr += PAGE_SIZE) {
147 if (pte_none(*old_pte))
148 continue;
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700149 pte = ptep_get_and_clear(mm, old_addr, old_pte);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700150 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
Cyrill Gorcunov6dec97d2013-08-27 12:37:18 +0400151 pte = move_soft_dirty_pte(pte);
152 set_pte_at(mm, new_addr, new_pte, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 }
Hugh Dickins7be7a542005-10-29 18:16:00 -0700154
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700155 arch_leave_lazy_mmu_mode();
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700156 if (new_ptl != old_ptl)
157 spin_unlock(new_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700158 pte_unmap(new_pte - 1);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700159 pte_unmap_unlock(old_pte - 1, old_ptl);
Hugh Dickins1d069b72016-05-19 17:12:57 -0700160 if (need_rmap_locks)
161 drop_rmap_locks(vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162}
163
Hugh Dickins7be7a542005-10-29 18:16:00 -0700164#define LATENCY_LIMIT (64 * PAGE_SIZE)
165
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700166unsigned long move_page_tables(struct vm_area_struct *vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 unsigned long old_addr, struct vm_area_struct *new_vma,
Michel Lespinasse38a76012012-10-08 16:31:50 -0700168 unsigned long new_addr, unsigned long len,
169 bool need_rmap_locks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170{
Hugh Dickins7be7a542005-10-29 18:16:00 -0700171 unsigned long extent, next, old_end;
172 pmd_t *old_pmd, *new_pmd;
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700173 bool need_flush = false;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700174 unsigned long mmun_start; /* For mmu_notifiers */
175 unsigned long mmun_end; /* For mmu_notifiers */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176
Hugh Dickins7be7a542005-10-29 18:16:00 -0700177 old_end = old_addr + len;
178 flush_cache_range(vma, old_addr, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700180 mmun_start = old_addr;
181 mmun_end = old_end;
182 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700183
Hugh Dickins7be7a542005-10-29 18:16:00 -0700184 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 cond_resched();
Hugh Dickins7be7a542005-10-29 18:16:00 -0700186 next = (old_addr + PMD_SIZE) & PMD_MASK;
Andrea Arcangeliebed4842011-10-31 17:08:22 -0700187 /* even if next overflowed, extent below will be ok */
Hugh Dickins7be7a542005-10-29 18:16:00 -0700188 extent = next - old_addr;
Andrea Arcangeliebed4842011-10-31 17:08:22 -0700189 if (extent > old_end - old_addr)
190 extent = old_end - old_addr;
Hugh Dickins7be7a542005-10-29 18:16:00 -0700191 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
192 if (!old_pmd)
193 continue;
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800194 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700195 if (!new_pmd)
196 break;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -0700197 if (pmd_trans_huge(*old_pmd)) {
Kirill A. Shutemovdd18dbc2014-05-09 15:37:00 -0700198 if (extent == HPAGE_PMD_SIZE) {
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -0800199 bool moved;
Kirill A. Shutemovdd18dbc2014-05-09 15:37:00 -0700200 /* See comment in move_ptes() */
201 if (need_rmap_locks)
Hugh Dickins1d069b72016-05-19 17:12:57 -0700202 take_rmap_locks(vma);
Hugh Dickinsbf8616d2016-05-19 17:12:54 -0700203 moved = move_huge_pmd(vma, old_addr, new_addr,
204 old_end, old_pmd, new_pmd);
Kirill A. Shutemovdd18dbc2014-05-09 15:37:00 -0700205 if (need_rmap_locks)
Hugh Dickins1d069b72016-05-19 17:12:57 -0700206 drop_rmap_locks(vma);
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -0800207 if (moved) {
208 need_flush = true;
209 continue;
210 }
Kirill A. Shutemovdd18dbc2014-05-09 15:37:00 -0700211 }
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -0800212 split_huge_pmd(vma, old_pmd, old_addr);
Kirill A. Shutemov6b9116a2016-02-11 16:13:03 -0800213 if (pmd_none(*old_pmd))
214 continue;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -0700215 VM_BUG_ON(pmd_trans_huge(*old_pmd));
216 }
Kirill A. Shutemov3ed3a4f2016-03-17 14:19:11 -0700217 if (pte_alloc(new_vma->vm_mm, new_pmd, new_addr))
Andrea Arcangeli37a1c492011-10-31 17:08:30 -0700218 break;
Hugh Dickins7be7a542005-10-29 18:16:00 -0700219 next = (new_addr + PMD_SIZE) & PMD_MASK;
220 if (extent > next - new_addr)
221 extent = next - new_addr;
222 if (extent > LATENCY_LIMIT)
223 extent = LATENCY_LIMIT;
224 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
Michel Lespinasse38a76012012-10-08 16:31:50 -0700225 new_vma, new_pmd, new_addr, need_rmap_locks);
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700226 need_flush = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 }
Andrea Arcangeli7b6efc22011-10-31 17:08:26 -0700228 if (likely(need_flush))
229 flush_tlb_range(vma, old_end-len, old_addr);
230
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700231 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
Hugh Dickins7be7a542005-10-29 18:16:00 -0700232
233 return len + old_addr - old_end; /* how much done */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234}
235
236static unsigned long move_vma(struct vm_area_struct *vma,
237 unsigned long old_addr, unsigned long old_len,
Michel Lespinasse81909b82013-02-22 16:32:41 -0800238 unsigned long new_len, unsigned long new_addr, bool *locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239{
240 struct mm_struct *mm = vma->vm_mm;
241 struct vm_area_struct *new_vma;
242 unsigned long vm_flags = vma->vm_flags;
243 unsigned long new_pgoff;
244 unsigned long moved_len;
245 unsigned long excess = 0;
Hugh Dickins365e9c872005-10-29 18:16:18 -0700246 unsigned long hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 int split = 0;
Hugh Dickins7103ad32009-09-21 17:02:28 -0700248 int err;
Michel Lespinasse38a76012012-10-08 16:31:50 -0700249 bool need_rmap_locks;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250
251 /*
252 * We'd prefer to avoid failure later on in do_munmap:
253 * which may split one vma into three before unmapping.
254 */
255 if (mm->map_count >= sysctl_max_map_count - 3)
256 return -ENOMEM;
257
Hugh Dickins1ff82992009-09-21 17:02:05 -0700258 /*
259 * Advise KSM to break any KSM pages in the area to be moved:
260 * it would be confusing if they were to turn up at the new
261 * location, where they happen to coincide with different KSM
262 * pages recently unmapped. But leave vma->vm_flags as it was,
263 * so KSM can come around to merge on vma and new_vma afterwards.
264 */
Hugh Dickins7103ad32009-09-21 17:02:28 -0700265 err = ksm_madvise(vma, old_addr, old_addr + old_len,
266 MADV_UNMERGEABLE, &vm_flags);
267 if (err)
268 return err;
Hugh Dickins1ff82992009-09-21 17:02:05 -0700269
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
Michel Lespinasse38a76012012-10-08 16:31:50 -0700271 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
272 &need_rmap_locks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 if (!new_vma)
274 return -ENOMEM;
275
Michel Lespinasse38a76012012-10-08 16:31:50 -0700276 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
277 need_rmap_locks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 if (moved_len < old_len) {
Oleg Nesterovdf1eab32015-09-04 15:48:01 -0700279 err = -ENOMEM;
Oleg Nesterov5477e702015-09-04 15:48:04 -0700280 } else if (vma->vm_ops && vma->vm_ops->mremap) {
281 err = vma->vm_ops->mremap(new_vma);
Oleg Nesterovdf1eab32015-09-04 15:48:01 -0700282 }
283
284 if (unlikely(err)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 /*
286 * On error, move entries back from new area to old,
287 * which will succeed since page tables still there,
288 * and then proceed to unmap new area instead of old.
289 */
Michel Lespinasse38a76012012-10-08 16:31:50 -0700290 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
291 true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 vma = new_vma;
293 old_len = new_len;
294 old_addr = new_addr;
Oleg Nesterovdf1eab32015-09-04 15:48:01 -0700295 new_addr = err;
Laurent Dufour4abad2c2015-06-24 16:56:19 -0700296 } else {
Laurent Dufour4abad2c2015-06-24 16:56:19 -0700297 arch_remap(mm, old_addr, old_addr + old_len,
298 new_addr, new_addr + new_len);
Al Virob2edffd2015-04-06 17:48:54 -0400299 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300
301 /* Conceal VM_ACCOUNT so old reservation is not undone */
302 if (vm_flags & VM_ACCOUNT) {
303 vma->vm_flags &= ~VM_ACCOUNT;
304 excess = vma->vm_end - vma->vm_start - old_len;
305 if (old_addr > vma->vm_start &&
306 old_addr + old_len < vma->vm_end)
307 split = 1;
308 }
309
Kirill Korotaev71799062005-05-16 21:53:18 -0700310 /*
Hugh Dickins365e9c872005-10-29 18:16:18 -0700311 * If we failed to move page tables we still do total_vm increment
312 * since do_munmap() will decrement it by old_len == new_len.
313 *
314 * Since total_vm is about to be raised artificially high for a
315 * moment, we need to restore high watermark afterwards: if stats
316 * are taken meanwhile, total_vm and hiwater_vm appear too high.
317 * If this were a serious issue, we'd add a flag to do_munmap().
Kirill Korotaev71799062005-05-16 21:53:18 -0700318 */
Hugh Dickins365e9c872005-10-29 18:16:18 -0700319 hiwater_vm = mm->hiwater_vm;
Konstantin Khlebnikov84638332016-01-14 15:22:07 -0800320 vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT);
Kirill Korotaev71799062005-05-16 21:53:18 -0700321
Toshi Kanid9fe4fa2015-12-22 17:54:23 -0700322 /* Tell pfnmap has moved from this vma */
323 if (unlikely(vma->vm_flags & VM_PFNMAP))
324 untrack_pfn_moved(vma);
325
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 if (do_munmap(mm, old_addr, old_len) < 0) {
327 /* OOM: unable to split vma, just get accounts right */
328 vm_unacct_memory(excess >> PAGE_SHIFT);
329 excess = 0;
330 }
Hugh Dickins365e9c872005-10-29 18:16:18 -0700331 mm->hiwater_vm = hiwater_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332
333 /* Restore VM_ACCOUNT if one or two pieces of vma left */
334 if (excess) {
335 vma->vm_flags |= VM_ACCOUNT;
336 if (split)
337 vma->vm_next->vm_flags |= VM_ACCOUNT;
338 }
339
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 if (vm_flags & VM_LOCKED) {
341 mm->locked_vm += new_len >> PAGE_SHIFT;
Michel Lespinasse81909b82013-02-22 16:32:41 -0800342 *locked = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
344
345 return new_addr;
346}
347
Al Viro54f5de72009-11-24 07:17:46 -0500348static struct vm_area_struct *vma_to_resize(unsigned long addr,
349 unsigned long old_len, unsigned long new_len, unsigned long *p)
350{
351 struct mm_struct *mm = current->mm;
352 struct vm_area_struct *vma = find_vma(mm, addr);
Oleg Nesterov1d391682015-09-04 15:48:10 -0700353 unsigned long pgoff;
Al Viro54f5de72009-11-24 07:17:46 -0500354
355 if (!vma || vma->vm_start > addr)
Derek6cd576132015-04-15 16:14:02 -0700356 return ERR_PTR(-EFAULT);
Al Viro54f5de72009-11-24 07:17:46 -0500357
358 if (is_vm_hugetlb_page(vma))
Derek6cd576132015-04-15 16:14:02 -0700359 return ERR_PTR(-EINVAL);
Al Viro54f5de72009-11-24 07:17:46 -0500360
361 /* We can't remap across vm area boundaries */
362 if (old_len > vma->vm_end - addr)
Derek6cd576132015-04-15 16:14:02 -0700363 return ERR_PTR(-EFAULT);
Al Viro54f5de72009-11-24 07:17:46 -0500364
Oleg Nesterov1d391682015-09-04 15:48:10 -0700365 if (new_len == old_len)
366 return vma;
Linus Torvalds982134b2011-04-07 07:35:50 -0700367
Oleg Nesterov1d391682015-09-04 15:48:10 -0700368 /* Need to be careful about a growing mapping */
369 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
370 pgoff += vma->vm_pgoff;
371 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
372 return ERR_PTR(-EINVAL);
373
374 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
375 return ERR_PTR(-EFAULT);
Al Viro54f5de72009-11-24 07:17:46 -0500376
377 if (vma->vm_flags & VM_LOCKED) {
378 unsigned long locked, lock_limit;
379 locked = mm->locked_vm << PAGE_SHIFT;
Jiri Slaby59e99e52010-03-05 13:41:44 -0800380 lock_limit = rlimit(RLIMIT_MEMLOCK);
Al Viro54f5de72009-11-24 07:17:46 -0500381 locked += new_len - old_len;
382 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
Derek6cd576132015-04-15 16:14:02 -0700383 return ERR_PTR(-EAGAIN);
Al Viro54f5de72009-11-24 07:17:46 -0500384 }
385
Konstantin Khlebnikov84638332016-01-14 15:22:07 -0800386 if (!may_expand_vm(mm, vma->vm_flags,
387 (new_len - old_len) >> PAGE_SHIFT))
Derek6cd576132015-04-15 16:14:02 -0700388 return ERR_PTR(-ENOMEM);
Al Viro54f5de72009-11-24 07:17:46 -0500389
390 if (vma->vm_flags & VM_ACCOUNT) {
391 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
Al Viro191c5422012-02-13 03:58:52 +0000392 if (security_vm_enough_memory_mm(mm, charged))
Derek6cd576132015-04-15 16:14:02 -0700393 return ERR_PTR(-ENOMEM);
Al Viro54f5de72009-11-24 07:17:46 -0500394 *p = charged;
395 }
396
397 return vma;
Al Viro54f5de72009-11-24 07:17:46 -0500398}
399
Michel Lespinasse81909b82013-02-22 16:32:41 -0800400static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
401 unsigned long new_addr, unsigned long new_len, bool *locked)
Al Viroecc1a892009-11-24 07:28:07 -0500402{
403 struct mm_struct *mm = current->mm;
404 struct vm_area_struct *vma;
405 unsigned long ret = -EINVAL;
406 unsigned long charged = 0;
Al Viro097eed12009-11-24 08:43:52 -0500407 unsigned long map_flags;
Al Viroecc1a892009-11-24 07:28:07 -0500408
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800409 if (offset_in_page(new_addr))
Al Viroecc1a892009-11-24 07:28:07 -0500410 goto out;
411
412 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
413 goto out;
414
Oleg Nesterov99432422015-09-04 15:48:13 -0700415 /* Ensure the old/new locations do not overlap */
416 if (addr + old_len > new_addr && new_addr + new_len > addr)
Al Viroecc1a892009-11-24 07:28:07 -0500417 goto out;
418
Al Viroecc1a892009-11-24 07:28:07 -0500419 ret = do_munmap(mm, new_addr, new_len);
420 if (ret)
421 goto out;
422
423 if (old_len >= new_len) {
424 ret = do_munmap(mm, addr+new_len, old_len - new_len);
425 if (ret && old_len != new_len)
426 goto out;
427 old_len = new_len;
428 }
429
430 vma = vma_to_resize(addr, old_len, new_len, &charged);
431 if (IS_ERR(vma)) {
432 ret = PTR_ERR(vma);
433 goto out;
434 }
435
Al Viro097eed12009-11-24 08:43:52 -0500436 map_flags = MAP_FIXED;
437 if (vma->vm_flags & VM_MAYSHARE)
438 map_flags |= MAP_SHARED;
Al Viro9206de92009-12-03 15:23:11 -0500439
Al Viro097eed12009-11-24 08:43:52 -0500440 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
441 ((addr - vma->vm_start) >> PAGE_SHIFT),
442 map_flags);
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800443 if (offset_in_page(ret))
Al Viro097eed12009-11-24 08:43:52 -0500444 goto out1;
445
Michel Lespinasse81909b82013-02-22 16:32:41 -0800446 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800447 if (!(offset_in_page(ret)))
Al Viro097eed12009-11-24 08:43:52 -0500448 goto out;
449out1:
450 vm_unacct_memory(charged);
Al Viroecc1a892009-11-24 07:28:07 -0500451
452out:
453 return ret;
454}
455
Al Viro1a0ef852009-11-24 07:43:18 -0500456static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
457{
Al Virof106af42009-11-24 08:25:18 -0500458 unsigned long end = vma->vm_end + delta;
Al Viro9206de92009-12-03 15:23:11 -0500459 if (end < vma->vm_end) /* overflow */
Al Viro1a0ef852009-11-24 07:43:18 -0500460 return 0;
Al Viro9206de92009-12-03 15:23:11 -0500461 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
Al Virof106af42009-11-24 08:25:18 -0500462 return 0;
463 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
464 0, MAP_FIXED) & ~PAGE_MASK)
465 return 0;
Al Viro1a0ef852009-11-24 07:43:18 -0500466 return 1;
467}
468
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469/*
470 * Expand (or shrink) an existing mapping, potentially moving it at the
471 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
472 *
473 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
474 * This option implies MREMAP_MAYMOVE.
475 */
Al Viro63a81db2012-05-30 11:32:04 -0400476SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
477 unsigned long, new_len, unsigned long, flags,
478 unsigned long, new_addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479{
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700480 struct mm_struct *mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 struct vm_area_struct *vma;
482 unsigned long ret = -EINVAL;
483 unsigned long charged = 0;
Michel Lespinasse81909b82013-02-22 16:32:41 -0800484 bool locked = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485
486 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
Rasmus Villemoes9a2458a2013-07-08 15:59:48 -0700487 return ret;
488
489 if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
490 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800492 if (offset_in_page(addr))
Rasmus Villemoes9a2458a2013-07-08 15:59:48 -0700493 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494
495 old_len = PAGE_ALIGN(old_len);
496 new_len = PAGE_ALIGN(new_len);
497
498 /*
499 * We allow a zero old-len as a special case
500 * for DOS-emu "duplicate shm area" thing. But
501 * a zero new-len is nonsensical.
502 */
503 if (!new_len)
Rasmus Villemoes9a2458a2013-07-08 15:59:48 -0700504 return ret;
505
506 down_write(&current->mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 if (flags & MREMAP_FIXED) {
Rasmus Villemoes9a2458a2013-07-08 15:59:48 -0700509 ret = mremap_to(addr, old_len, new_addr, new_len,
510 &locked);
Al Viroecc1a892009-11-24 07:28:07 -0500511 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 }
513
514 /*
515 * Always allow a shrinking remap: that just unmaps
516 * the unnecessary pages..
517 * do_munmap does all the needed commit accounting
518 */
519 if (old_len >= new_len) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700520 ret = do_munmap(mm, addr+new_len, old_len - new_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 if (ret && old_len != new_len)
522 goto out;
523 ret = addr;
Al Viroecc1a892009-11-24 07:28:07 -0500524 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 }
526
527 /*
Al Viroecc1a892009-11-24 07:28:07 -0500528 * Ok, we need to grow..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 */
Al Viro54f5de72009-11-24 07:17:46 -0500530 vma = vma_to_resize(addr, old_len, new_len, &charged);
531 if (IS_ERR(vma)) {
532 ret = PTR_ERR(vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 }
535
536 /* old_len exactly to the end of the area..
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 */
Al Viroecc1a892009-11-24 07:28:07 -0500538 if (old_len == vma->vm_end - addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 /* can we just expand the current mapping? */
Al Viro1a0ef852009-11-24 07:43:18 -0500540 if (vma_expandable(vma, new_len - old_len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 int pages = (new_len - old_len) >> PAGE_SHIFT;
542
Rik van Riel5beb4932010-03-05 13:42:07 -0800543 if (vma_adjust(vma, vma->vm_start, addr + new_len,
544 vma->vm_pgoff, NULL)) {
545 ret = -ENOMEM;
546 goto out;
547 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
Konstantin Khlebnikov84638332016-01-14 15:22:07 -0800549 vm_stat_account(mm, vma->vm_flags, pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 if (vma->vm_flags & VM_LOCKED) {
Hugh Dickinsd0de32d2005-10-29 18:16:16 -0700551 mm->locked_vm += pages;
Michel Lespinasse81909b82013-02-22 16:32:41 -0800552 locked = true;
553 new_addr = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 }
555 ret = addr;
556 goto out;
557 }
558 }
559
560 /*
561 * We weren't able to just expand or shrink the area,
562 * we need to create a new one and move it..
563 */
564 ret = -ENOMEM;
565 if (flags & MREMAP_MAYMOVE) {
Al Viroecc1a892009-11-24 07:28:07 -0500566 unsigned long map_flags = 0;
567 if (vma->vm_flags & VM_MAYSHARE)
568 map_flags |= MAP_SHARED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569
Al Viroecc1a892009-11-24 07:28:07 -0500570 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
Al Viro93587412009-11-24 08:45:24 -0500571 vma->vm_pgoff +
572 ((addr - vma->vm_start) >> PAGE_SHIFT),
573 map_flags);
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800574 if (offset_in_page(new_addr)) {
Al Viroecc1a892009-11-24 07:28:07 -0500575 ret = new_addr;
576 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 }
Al Viroecc1a892009-11-24 07:28:07 -0500578
Michel Lespinasse81909b82013-02-22 16:32:41 -0800579 ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 }
581out:
Alexander Kuleshovf19cb112015-11-05 18:46:57 -0800582 if (offset_in_page(ret)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 vm_unacct_memory(charged);
Oleg Nesterovd456fb92015-09-04 15:48:07 -0700584 locked = 0;
585 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 up_write(&current->mm->mmap_sem);
Michel Lespinasse81909b82013-02-22 16:32:41 -0800587 if (locked && new_len > old_len)
588 mm_populate(new_addr + old_len, new_len - old_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 return ret;
590}