1// SPDX-License-Identifier: GPL-2.0
2/*
3 * mm/mremap.c
4 *
5 * (C) Copyright 1996 Linus Torvalds
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
9 */
10
11#include <linux/mm.h>
12#include <linux/hugetlb.h>
13#include <linux/shm.h>
14#include <linux/ksm.h>
15#include <linux/mman.h>
16#include <linux/swap.h>
17#include <linux/capability.h>
18#include <linux/fs.h>
19#include <linux/swapops.h>
20#include <linux/highmem.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/mmu_notifier.h>
24#include <linux/uaccess.h>
25#include <linux/mm-arch-hooks.h>
26#include <linux/userfaultfd_k.h>
27
28#include <asm/cacheflush.h>
29#include <asm/tlbflush.h>
30
31#include "internal.h"
32
33static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
34{
35 pgd_t *pgd;
36 p4d_t *p4d;
37 pud_t *pud;
38 pmd_t *pmd;
39
40 pgd = pgd_offset(mm, addr);
41 if (pgd_none_or_clear_bad(pgd))
42 return NULL;
43
44 p4d = p4d_offset(pgd, addr);
45 if (p4d_none_or_clear_bad(p4d))
46 return NULL;
47
48 pud = pud_offset(p4d, addr);
49 if (pud_none_or_clear_bad(pud))
50 return NULL;
51
52 pmd = pmd_offset(pud, addr);
53 if (pmd_none(*pmd))
54 return NULL;
55
56 return pmd;
57}
58
59static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
60 unsigned long addr)
61{
62 pgd_t *pgd;
63 p4d_t *p4d;
64 pud_t *pud;
65 pmd_t *pmd;
66
67 pgd = pgd_offset(mm, addr);
68 p4d = p4d_alloc(mm, pgd, addr);
69 if (!p4d)
70 return NULL;
71 pud = pud_alloc(mm, p4d, addr);
72 if (!pud)
73 return NULL;
74
75 pmd = pmd_alloc(mm, pud, addr);
76 if (!pmd)
77 return NULL;
78
79 VM_BUG_ON(pmd_trans_huge(*pmd));
80
81 return pmd;
82}
83
84static void take_rmap_locks(struct vm_area_struct *vma)
85{
86 if (vma->vm_file)
87 i_mmap_lock_write(vma->vm_file->f_mapping);
88 if (vma->anon_vma)
89 anon_vma_lock_write(vma->anon_vma);
90}
91
92static void drop_rmap_locks(struct vm_area_struct *vma)
93{
94 if (vma->anon_vma)
95 anon_vma_unlock_write(vma->anon_vma);
96 if (vma->vm_file)
97 i_mmap_unlock_write(vma->vm_file->f_mapping);
98}
99
100static pte_t move_soft_dirty_pte(pte_t pte)
101{
102 /*
103 * Set soft dirty bit so we can notice
104 * in userspace the ptes were moved.
105 */
106#ifdef CONFIG_MEM_SOFT_DIRTY
107 if (pte_present(pte))
108 pte = pte_mksoft_dirty(pte);
109 else if (is_swap_pte(pte))
110 pte = pte_swp_mksoft_dirty(pte);
111#endif
112 return pte;
113}
114
115static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
116 unsigned long old_addr, unsigned long old_end,
117 struct vm_area_struct *new_vma, pmd_t *new_pmd,
118 unsigned long new_addr, bool need_rmap_locks)
119{
120 struct mm_struct *mm = vma->vm_mm;
121 pte_t *old_pte, *new_pte, pte;
122 spinlock_t *old_ptl, *new_ptl;
123 bool force_flush = false;
124 unsigned long len = old_end - old_addr;
125
126 /*
127 * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
128 * locks to ensure that rmap will always observe either the old or the
129 * new ptes. This is the easiest way to avoid races with
130 * truncate_pagecache(), page migration, etc...
131 *
132 * When need_rmap_locks is false, we use other ways to avoid
133 * such races:
134 *
135 * - During exec() shift_arg_pages(), we use a specially tagged vma
136 * which rmap call sites look for using is_vma_temporary_stack().
137 *
138 * - During mremap(), new_vma is often known to be placed after vma
139 * in rmap traversal order. This ensures rmap will always observe
140 * either the old pte, or the new pte, or both (the page table locks
141 * serialize access to individual ptes, but only rmap traversal
142 * order guarantees that we won't miss both the old and new ptes).
143 */
144 if (need_rmap_locks)
145 take_rmap_locks(vma);
146
147 /*
148 * We don't have to worry about the ordering of src and dst
149 * pte locks because exclusive mmap_sem prevents deadlock.
150 */
151 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
152 new_pte = pte_offset_map(new_pmd, new_addr);
153 new_ptl = pte_lockptr(mm, new_pmd);
154 if (new_ptl != old_ptl)
155 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
156 flush_tlb_batched_pending(vma->vm_mm);
157 arch_enter_lazy_mmu_mode();
158
159 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
160 new_pte++, new_addr += PAGE_SIZE) {
161 if (pte_none(*old_pte))
162 continue;
163
164 pte = ptep_get_and_clear(mm, old_addr, old_pte);
165 /*
166 * If we are remapping a valid PTE, make sure
167 * to flush TLB before we drop the PTL for the
168 * PTE.
169 *
170 * NOTE! Both old and new PTL matter: the old one
171 * for racing with page_mkclean(), the new one to
172 * make sure the physical page stays valid until
173 * the TLB entry for the old mapping has been
174 * flushed.
175 */
176 if (pte_present(pte))
177 force_flush = true;
178 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
179 pte = move_soft_dirty_pte(pte);
180 set_pte_at(mm, new_addr, new_pte, pte);
181 }
182
183 arch_leave_lazy_mmu_mode();
184 if (force_flush)
185 flush_tlb_range(vma, old_end - len, old_end);
186 if (new_ptl != old_ptl)
187 spin_unlock(new_ptl);
188 pte_unmap(new_pte - 1);
189 pte_unmap_unlock(old_pte - 1, old_ptl);
190 if (need_rmap_locks)
191 drop_rmap_locks(vma);
192}
193
194#ifdef CONFIG_HAVE_MOVE_PMD
195static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
196 unsigned long new_addr, unsigned long old_end,
197 pmd_t *old_pmd, pmd_t *new_pmd)
198{
199 spinlock_t *old_ptl, *new_ptl;
200 struct mm_struct *mm = vma->vm_mm;
201 pmd_t pmd;
202
203 if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK)
204 || old_end - old_addr < PMD_SIZE)
205 return false;
206
207 /*
208 * The destination pmd shouldn't be established, free_pgtables()
209 * should have release it.
210 */
211 if (WARN_ON(!pmd_none(*new_pmd)))
212 return false;
213
214 /*
215 * We don't have to worry about the ordering of src and dst
216 * ptlocks because exclusive mmap_sem prevents deadlock.
217 */
218 old_ptl = pmd_lock(vma->vm_mm, old_pmd);
219 new_ptl = pmd_lockptr(mm, new_pmd);
220 if (new_ptl != old_ptl)
221 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
222
223 /* Clear the pmd */
224 pmd = *old_pmd;
225 pmd_clear(old_pmd);
226
227 VM_BUG_ON(!pmd_none(*new_pmd));
228
229 /* Set the new pmd */
230 set_pmd_at(mm, new_addr, new_pmd, pmd);
231 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
232 if (new_ptl != old_ptl)
233 spin_unlock(new_ptl);
234 spin_unlock(old_ptl);
235
236 return true;
237}
238#endif
239
240unsigned long move_page_tables(struct vm_area_struct *vma,
241 unsigned long old_addr, struct vm_area_struct *new_vma,
242 unsigned long new_addr, unsigned long len,
243 bool need_rmap_locks)
244{
245 unsigned long extent, next, old_end;
246 struct mmu_notifier_range range;
247 pmd_t *old_pmd, *new_pmd;
248
249 old_end = old_addr + len;
250 flush_cache_range(vma, old_addr, old_end);
251
252 mmu_notifier_range_init(&range, vma->vm_mm, old_addr, old_end);
253 mmu_notifier_invalidate_range_start(&range);
254
255 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
256 cond_resched();
257 next = (old_addr + PMD_SIZE) & PMD_MASK;
258 /* even if next overflowed, extent below will be ok */
259 extent = next - old_addr;
260 if (extent > old_end - old_addr)
261 extent = old_end - old_addr;
262 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
263 if (!old_pmd)
264 continue;
265 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
266 if (!new_pmd)
267 break;
268 if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
269 if (extent == HPAGE_PMD_SIZE) {
270 bool moved;
271 /* See comment in move_ptes() */
272 if (need_rmap_locks)
273 take_rmap_locks(vma);
274 moved = move_huge_pmd(vma, old_addr, new_addr,
275 old_end, old_pmd, new_pmd);
276 if (need_rmap_locks)
277 drop_rmap_locks(vma);
278 if (moved)
279 continue;
280 }
281 split_huge_pmd(vma, old_pmd, old_addr);
282 if (pmd_trans_unstable(old_pmd))
283 continue;
284 } else if (extent == PMD_SIZE) {
285#ifdef CONFIG_HAVE_MOVE_PMD
286 /*
287 * If the extent is PMD-sized, try to speed the move by
288 * moving at the PMD level if possible.
289 */
290 bool moved;
291
292 if (need_rmap_locks)
293 take_rmap_locks(vma);
294 moved = move_normal_pmd(vma, old_addr, new_addr,
295 old_end, old_pmd, new_pmd);
296 if (need_rmap_locks)
297 drop_rmap_locks(vma);
298 if (moved)
299 continue;
300#endif
301 }
302
303 if (pte_alloc(new_vma->vm_mm, new_pmd))
304 break;
305 next = (new_addr + PMD_SIZE) & PMD_MASK;
306 if (extent > next - new_addr)
307 extent = next - new_addr;
308 move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma,
309 new_pmd, new_addr, need_rmap_locks);
310 }
311
312 mmu_notifier_invalidate_range_end(&range);
313
314 return len + old_addr - old_end; /* how much done */
315}
316
317static unsigned long move_vma(struct vm_area_struct *vma,
318 unsigned long old_addr, unsigned long old_len,
319 unsigned long new_len, unsigned long new_addr,
320 bool *locked, struct vm_userfaultfd_ctx *uf,
321 struct list_head *uf_unmap)
322{
323 struct mm_struct *mm = vma->vm_mm;
324 struct vm_area_struct *new_vma;
325 unsigned long vm_flags = vma->vm_flags;
326 unsigned long new_pgoff;
327 unsigned long moved_len;
328 unsigned long excess = 0;
329 unsigned long hiwater_vm;
330 int split = 0;
331 int err;
332 bool need_rmap_locks;
333
334 /*
335 * We'd prefer to avoid failure later on in do_munmap:
336 * which may split one vma into three before unmapping.
337 */
338 if (mm->map_count >= sysctl_max_map_count - 3)
339 return -ENOMEM;
340
341 /*
342 * Advise KSM to break any KSM pages in the area to be moved:
343 * it would be confusing if they were to turn up at the new
344 * location, where they happen to coincide with different KSM
345 * pages recently unmapped. But leave vma->vm_flags as it was,
346 * so KSM can come around to merge on vma and new_vma afterwards.
347 */
348 err = ksm_madvise(vma, old_addr, old_addr + old_len,
349 MADV_UNMERGEABLE, &vm_flags);
350 if (err)
351 return err;
352
353 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
354 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
355 &need_rmap_locks);
356 if (!new_vma)
357 return -ENOMEM;
358
359 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
360 need_rmap_locks);
361 if (moved_len < old_len) {
362 err = -ENOMEM;
363 } else if (vma->vm_ops && vma->vm_ops->mremap) {
364 err = vma->vm_ops->mremap(new_vma);
365 }
366
367 if (unlikely(err)) {
368 /*
369 * On error, move entries back from new area to old,
370 * which will succeed since page tables still there,
371 * and then proceed to unmap new area instead of old.
372 */
373 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
374 true);
375 vma = new_vma;
376 old_len = new_len;
377 old_addr = new_addr;
378 new_addr = err;
379 } else {
380 mremap_userfaultfd_prep(new_vma, uf);
381 arch_remap(mm, old_addr, old_addr + old_len,
382 new_addr, new_addr + new_len);
383 }
384
385 /* Conceal VM_ACCOUNT so old reservation is not undone */
386 if (vm_flags & VM_ACCOUNT) {
387 vma->vm_flags &= ~VM_ACCOUNT;
388 excess = vma->vm_end - vma->vm_start - old_len;
389 if (old_addr > vma->vm_start &&
390 old_addr + old_len < vma->vm_end)
391 split = 1;
392 }
393
394 /*
395 * If we failed to move page tables we still do total_vm increment
396 * since do_munmap() will decrement it by old_len == new_len.
397 *
398 * Since total_vm is about to be raised artificially high for a
399 * moment, we need to restore high watermark afterwards: if stats
400 * are taken meanwhile, total_vm and hiwater_vm appear too high.
401 * If this were a serious issue, we'd add a flag to do_munmap().
402 */
403 hiwater_vm = mm->hiwater_vm;
404 vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT);
405
406 /* Tell pfnmap has moved from this vma */
407 if (unlikely(vma->vm_flags & VM_PFNMAP))
408 untrack_pfn_moved(vma);
409
410 if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
411 /* OOM: unable to split vma, just get accounts right */
412 vm_unacct_memory(excess >> PAGE_SHIFT);
413 excess = 0;
414 }
415 mm->hiwater_vm = hiwater_vm;
416
417 /* Restore VM_ACCOUNT if one or two pieces of vma left */
418 if (excess) {
419 vma->vm_flags |= VM_ACCOUNT;
420 if (split)
421 vma->vm_next->vm_flags |= VM_ACCOUNT;
422 }
423
424 if (vm_flags & VM_LOCKED) {
425 mm->locked_vm += new_len >> PAGE_SHIFT;
426 *locked = true;
427 }
428
429 return new_addr;
430}
431
432static struct vm_area_struct *vma_to_resize(unsigned long addr,
433 unsigned long old_len, unsigned long new_len, unsigned long *p)
434{
435 struct mm_struct *mm = current->mm;
436 struct vm_area_struct *vma = find_vma(mm, addr);
437 unsigned long pgoff;
438
439 if (!vma || vma->vm_start > addr)
440 return ERR_PTR(-EFAULT);
441
442 /*
443 * !old_len is a special case where an attempt is made to 'duplicate'
444 * a mapping. This makes no sense for private mappings as it will
445 * instead create a fresh/new mapping unrelated to the original. This
446 * is contrary to the basic idea of mremap which creates new mappings
447 * based on the original. There are no known use cases for this
448 * behavior. As a result, fail such attempts.
449 */
450 if (!old_len && !(vma->vm_flags & (VM_SHARED | VM_MAYSHARE))) {
451 pr_warn_once("%s (%d): attempted to duplicate a private mapping with mremap. This is not supported.\n", current->comm, current->pid);
452 return ERR_PTR(-EINVAL);
453 }
454
455 if (is_vm_hugetlb_page(vma))
456 return ERR_PTR(-EINVAL);
457
458 /* We can't remap across vm area boundaries */
459 if (old_len > vma->vm_end - addr)
460 return ERR_PTR(-EFAULT);
461
462 if (new_len == old_len)
463 return vma;
464
465 /* Need to be careful about a growing mapping */
466 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
467 pgoff += vma->vm_pgoff;
468 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
469 return ERR_PTR(-EINVAL);
470
471 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
472 return ERR_PTR(-EFAULT);
473
474 if (vma->vm_flags & VM_LOCKED) {
475 unsigned long locked, lock_limit;
476 locked = mm->locked_vm << PAGE_SHIFT;
477 lock_limit = rlimit(RLIMIT_MEMLOCK);
478 locked += new_len - old_len;
479 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
480 return ERR_PTR(-EAGAIN);
481 }
482
483 if (!may_expand_vm(mm, vma->vm_flags,
484 (new_len - old_len) >> PAGE_SHIFT))
485 return ERR_PTR(-ENOMEM);
486
487 if (vma->vm_flags & VM_ACCOUNT) {
488 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
489 if (security_vm_enough_memory_mm(mm, charged))
490 return ERR_PTR(-ENOMEM);
491 *p = charged;
492 }
493
494 return vma;
495}
496
497static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
498 unsigned long new_addr, unsigned long new_len, bool *locked,
499 struct vm_userfaultfd_ctx *uf,
500 struct list_head *uf_unmap_early,
501 struct list_head *uf_unmap)
502{
503 struct mm_struct *mm = current->mm;
504 struct vm_area_struct *vma;
505 unsigned long ret = -EINVAL;
506 unsigned long charged = 0;
507 unsigned long map_flags;
508
509 if (offset_in_page(new_addr))
510 goto out;
511
512 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
513 goto out;
514
515 /* Ensure the old/new locations do not overlap */
516 if (addr + old_len > new_addr && new_addr + new_len > addr)
517 goto out;
518
519 /*
520 * move_vma() need us to stay 4 maps below the threshold, otherwise
521 * it will bail out at the very beginning.
522 * That is a problem if we have already unmaped the regions here
523 * (new_addr, and old_addr), because userspace will not know the
524 * state of the vma's after it gets -ENOMEM.
525 * So, to avoid such scenario we can pre-compute if the whole
526 * operation has high chances to success map-wise.
527 * Worst-scenario case is when both vma's (new_addr and old_addr) get
528 * split in 3 before unmaping it.
529 * That means 2 more maps (1 for each) to the ones we already hold.
530 * Check whether current map count plus 2 still leads us to 4 maps below
531 * the threshold, otherwise return -ENOMEM here to be more safe.
532 */
533 if ((mm->map_count + 2) >= sysctl_max_map_count - 3)
534 return -ENOMEM;
535
536 ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);
537 if (ret)
538 goto out;
539
540 if (old_len >= new_len) {
541 ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
542 if (ret && old_len != new_len)
543 goto out;
544 old_len = new_len;
545 }
546
547 vma = vma_to_resize(addr, old_len, new_len, &charged);
548 if (IS_ERR(vma)) {
549 ret = PTR_ERR(vma);
550 goto out;
551 }
552
553 map_flags = MAP_FIXED;
554 if (vma->vm_flags & VM_MAYSHARE)
555 map_flags |= MAP_SHARED;
556
557 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
558 ((addr - vma->vm_start) >> PAGE_SHIFT),
559 map_flags);
560 if (offset_in_page(ret))
561 goto out1;
562
563 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf,
564 uf_unmap);
565 if (!(offset_in_page(ret)))
566 goto out;
567out1:
568 vm_unacct_memory(charged);
569
570out:
571 return ret;
572}
573
574static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
575{
576 unsigned long end = vma->vm_end + delta;
577 if (end < vma->vm_end) /* overflow */
578 return 0;
579 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
580 return 0;
581 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
582 0, MAP_FIXED) & ~PAGE_MASK)
583 return 0;
584 return 1;
585}
586
587/*
588 * Expand (or shrink) an existing mapping, potentially moving it at the
589 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
590 *
591 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
592 * This option implies MREMAP_MAYMOVE.
593 */
594SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
595 unsigned long, new_len, unsigned long, flags,
596 unsigned long, new_addr)
597{
598 struct mm_struct *mm = current->mm;
599 struct vm_area_struct *vma;
600 unsigned long ret = -EINVAL;
601 unsigned long charged = 0;
602 bool locked = false;
603 bool downgraded = false;
604 struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX;
605 LIST_HEAD(uf_unmap_early);
606 LIST_HEAD(uf_unmap);
607
608 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
609 return ret;
610
611 if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
612 return ret;
613
614 if (offset_in_page(addr))
615 return ret;
616
617 old_len = PAGE_ALIGN(old_len);
618 new_len = PAGE_ALIGN(new_len);
619
620 /*
621 * We allow a zero old-len as a special case
622 * for DOS-emu "duplicate shm area" thing. But
623 * a zero new-len is nonsensical.
624 */
625 if (!new_len)
626 return ret;
627
628 if (down_write_killable(&current->mm->mmap_sem))
629 return -EINTR;
630
631 if (flags & MREMAP_FIXED) {
632 ret = mremap_to(addr, old_len, new_addr, new_len,
633 &locked, &uf, &uf_unmap_early, &uf_unmap);
634 goto out;
635 }
636
637 /*
638 * Always allow a shrinking remap: that just unmaps
639 * the unnecessary pages..
640 * __do_munmap does all the needed commit accounting, and
641 * downgrades mmap_sem to read if so directed.
642 */
643 if (old_len >= new_len) {
644 int retval;
645
646 retval = __do_munmap(mm, addr+new_len, old_len - new_len,
647 &uf_unmap, true);
648 if (retval < 0 && old_len != new_len) {
649 ret = retval;
650 goto out;
651 /* Returning 1 indicates mmap_sem is downgraded to read. */
652 } else if (retval == 1)
653 downgraded = true;
654 ret = addr;
655 goto out;
656 }
657
658 /*
659 * Ok, we need to grow..
660 */
661 vma = vma_to_resize(addr, old_len, new_len, &charged);
662 if (IS_ERR(vma)) {
663 ret = PTR_ERR(vma);
664 goto out;
665 }
666
667 /* old_len exactly to the end of the area..
668 */
669 if (old_len == vma->vm_end - addr) {
670 /* can we just expand the current mapping? */
671 if (vma_expandable(vma, new_len - old_len)) {
672 int pages = (new_len - old_len) >> PAGE_SHIFT;
673
674 if (vma_adjust(vma, vma->vm_start, addr + new_len,
675 vma->vm_pgoff, NULL)) {
676 ret = -ENOMEM;
677 goto out;
678 }
679
680 vm_stat_account(mm, vma->vm_flags, pages);
681 if (vma->vm_flags & VM_LOCKED) {
682 mm->locked_vm += pages;
683 locked = true;
684 new_addr = addr;
685 }
686 ret = addr;
687 goto out;
688 }
689 }
690
691 /*
692 * We weren't able to just expand or shrink the area,
693 * we need to create a new one and move it..
694 */
695 ret = -ENOMEM;
696 if (flags & MREMAP_MAYMOVE) {
697 unsigned long map_flags = 0;
698 if (vma->vm_flags & VM_MAYSHARE)
699 map_flags |= MAP_SHARED;
700
701 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
702 vma->vm_pgoff +
703 ((addr - vma->vm_start) >> PAGE_SHIFT),
704 map_flags);
705 if (offset_in_page(new_addr)) {
706 ret = new_addr;
707 goto out;
708 }
709
710 ret = move_vma(vma, addr, old_len, new_len, new_addr,
711 &locked, &uf, &uf_unmap);
712 }
713out:
714 if (offset_in_page(ret)) {
715 vm_unacct_memory(charged);
716 locked = 0;
717 }
718 if (downgraded)
719 up_read(&current->mm->mmap_sem);
720 else
721 up_write(&current->mm->mmap_sem);
722 if (locked && new_len > old_len)
723 mm_populate(new_addr + old_len, new_len - old_len);
724 userfaultfd_unmap_complete(mm, &uf_unmap_early);
725 mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
726 userfaultfd_unmap_complete(mm, &uf_unmap);
727 return ret;
728}
729