mm/mremap.c

   1 /*
   2  *      mm/mremap.c
   3  *
   4  *      (C) Copyright 1996 Linus Torvalds
   5  *
   6  *      Address space accounting code   <alan@lxorguk.ukuu.org.uk>
   7  *      (C) Copyright 2002 Red Hat Inc, All Rights Reserved
   8  */
   9
  10 #include <linux/mm.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/shm.h>
  13 #include <linux/ksm.h>
  14 #include <linux/mman.h>
  15 #include <linux/swap.h>
  16 #include <linux/capability.h>
  17 #include <linux/fs.h>
  18 #include <linux/swapops.h>
  19 #include <linux/highmem.h>
  20 #include <linux/security.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/mmu_notifier.h>
  23 #include <linux/sched/sysctl.h>
  24 #include <linux/uaccess.h>
  25
  26 #include <asm/cacheflush.h>
  27 #include <asm/tlbflush.h>
  28
  29 #include "internal.h"
  30
  31 static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
  32 {
  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);
  46         if (pmd_none(*pmd))
  47                 return NULL;
  48
  49         return pmd;
  50 }
  51
  52 static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
  53                             unsigned long addr)
  54 {
  55         pgd_t *pgd;
  56         pud_t *pud;
  57         pmd_t *pmd;
  58
  59         pgd = pgd_offset(mm, addr);
  60         pud = pud_alloc(mm, pgd, addr);
  61         if (!pud)
  62                 return NULL;
  63
  64         pmd = pmd_alloc(mm, pud, addr);
  65         if (!pmd)
  66                 return NULL;
  67
  68         VM_BUG_ON(pmd_trans_huge(*pmd));
  69
  70         return pmd;
  71 }
  72
  73 static pte_t move_soft_dirty_pte(pte_t pte)
  74 {
  75         /*
  76          * Set soft dirty bit so we can notice
  77          * in userspace the ptes were moved.
  78          */
  79 #ifdef CONFIG_MEM_SOFT_DIRTY
  80         if (pte_present(pte))
  81                 pte = pte_mksoft_dirty(pte);
  82         else if (is_swap_pte(pte))
  83                 pte = pte_swp_mksoft_dirty(pte);
  84         else if (pte_file(pte))
  85                 pte = pte_file_mksoft_dirty(pte);
  86 #endif
  87         return pte;
  88 }
  89
  90 static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
  91                 unsigned long old_addr, unsigned long old_end,
  92                 struct vm_area_struct *new_vma, pmd_t *new_pmd,
  93                 unsigned long new_addr, bool need_rmap_locks)
  94 {
  95         struct address_space *mapping = NULL;
  96         struct anon_vma *anon_vma = NULL;
  97         struct mm_struct *mm = vma->vm_mm;
  98         pte_t *old_pte, *new_pte, pte;
  99         spinlock_t *old_ptl, *new_ptl;
 100
 101         /*
 102          * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
 103          * locks to ensure that rmap will always observe either the old or the
 104          * new ptes. This is the easiest way to avoid races with
 105          * truncate_pagecache(), page migration, etc...
 106          *
 107          * When need_rmap_locks is false, we use other ways to avoid
 108          * such races:
 109          *
 110          * - During exec() shift_arg_pages(), we use a specially tagged vma
 111          *   which rmap call sites look for using is_vma_temporary_stack().
 112          *
 113          * - During mremap(), new_vma is often known to be placed after vma
 114          *   in rmap traversal order. This ensures rmap will always observe
 115          *   either the old pte, or the new pte, or both (the page table locks
 116          *   serialize access to individual ptes, but only rmap traversal
 117          *   order guarantees that we won't miss both the old and new ptes).
 118          */
 119         if (need_rmap_locks) {
 120                 if (vma->vm_file) {
 121                         mapping = vma->vm_file->f_mapping;
 122                         i_mmap_lock_write(mapping);
 123                 }
 124                 if (vma->anon_vma) {
 125                         anon_vma = vma->anon_vma;
 126                         anon_vma_lock_write(anon_vma);
 127                 }
 128         }
 129
 130         /*
 131          * We don't have to worry about the ordering of src and dst
 132          * pte locks because exclusive mmap_sem prevents deadlock.
 133          */
 134         old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
 135         new_pte = pte_offset_map(new_pmd, new_addr);
 136         new_ptl = pte_lockptr(mm, new_pmd);
 137         if (new_ptl != old_ptl)
 138                 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
 139         arch_enter_lazy_mmu_mode();
 140
 141         for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
 142                                    new_pte++, new_addr += PAGE_SIZE) {
 143                 if (pte_none(*old_pte))
 144                         continue;
 145                 pte = ptep_get_and_clear(mm, old_addr, old_pte);
 146                 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
 147
 148 #ifdef CONFIG_ARCH_TRACK_EXEC_LIMIT
 149                 if (!(__supported_pte_mask & _PAGE_NX) && pte_present(pte) && (new_vma->vm_flags & (VM_PAGEEXEC | VM_EXEC)) == VM_PAGEEXEC)
 150                         pte = pte_exprotect(pte);
 151 #endif
 152
 153                 pte = move_soft_dirty_pte(pte);
 154                 set_pte_at(mm, new_addr, new_pte, pte);
 155         }
 156
 157         arch_leave_lazy_mmu_mode();
 158         if (new_ptl != old_ptl)
 159                 spin_unlock(new_ptl);
 160         pte_unmap(new_pte - 1);
 161         pte_unmap_unlock(old_pte - 1, old_ptl);
 162         if (anon_vma)
 163                 anon_vma_unlock_write(anon_vma);
 164         if (mapping)
 165                 i_mmap_unlock_write(mapping);
 166 }
 167
 168 #define LATENCY_LIMIT   (64 * PAGE_SIZE)
 169
 170 unsigned long move_page_tables(struct vm_area_struct *vma,
 171                 unsigned long old_addr, struct vm_area_struct *new_vma,
 172                 unsigned long new_addr, unsigned long len,
 173                 bool need_rmap_locks)
 174 {
 175         unsigned long extent, next, old_end;
 176         pmd_t *old_pmd, *new_pmd;
 177         bool need_flush = false;
 178         unsigned long mmun_start;       /* For mmu_notifiers */
 179         unsigned long mmun_end;         /* For mmu_notifiers */
 180
 181         old_end = old_addr + len;
 182         flush_cache_range(vma, old_addr, old_end);
 183
 184         mmun_start = old_addr;
 185         mmun_end   = old_end;
 186         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
 187
 188         for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
 189                 cond_resched();
 190                 next = (old_addr + PMD_SIZE) & PMD_MASK;
 191                 /* even if next overflowed, extent below will be ok */
 192                 extent = next - old_addr;
 193                 if (extent > old_end - old_addr)
 194                         extent = old_end - old_addr;
 195                 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
 196                 if (!old_pmd)
 197                         continue;
 198                 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
 199                 if (!new_pmd)
 200                         break;
 201                 if (pmd_trans_huge(*old_pmd)) {
 202                         int err = 0;
 203                         if (extent == HPAGE_PMD_SIZE) {
 204                                 VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
 205                                               vma);
 206                                 /* See comment in move_ptes() */
 207                                 if (need_rmap_locks)
 208                                         anon_vma_lock_write(vma->anon_vma);
 209                                 err = move_huge_pmd(vma, new_vma, old_addr,
 210                                                     new_addr, old_end,
 211                                                     old_pmd, new_pmd);
 212                                 if (need_rmap_locks)
 213                                         anon_vma_unlock_write(vma->anon_vma);
 214                         }
 215                         if (err > 0) {
 216                                 need_flush = true;
 217                                 continue;
 218                         } else if (!err) {
 219                                 split_huge_page_pmd(vma, old_addr, old_pmd);
 220                         }
 221                         VM_BUG_ON(pmd_trans_huge(*old_pmd));
 222                 }
 223                 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
 224                                                       new_pmd, new_addr))
 225                         break;
 226                 next = (new_addr + PMD_SIZE) & PMD_MASK;
 227                 if (extent > next - new_addr)
 228                         extent = next - new_addr;
 229                 if (extent > LATENCY_LIMIT)
 230                         extent = LATENCY_LIMIT;
 231                 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
 232                           new_vma, new_pmd, new_addr, need_rmap_locks);
 233                 need_flush = true;
 234         }
 235         if (likely(need_flush))
 236                 flush_tlb_range(vma, old_end-len, old_addr);
 237
 238         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
 239
 240         return len + old_addr - old_end;        /* how much done */
 241 }
 242
 243 static unsigned long move_vma(struct vm_area_struct *vma,
 244                 unsigned long old_addr, unsigned long old_len,
 245                 unsigned long new_len, unsigned long new_addr, bool *locked)
 246 {
 247         struct mm_struct *mm = vma->vm_mm;
 248         struct vm_area_struct *new_vma;
 249         unsigned long vm_flags = vma->vm_flags;
 250         unsigned long new_pgoff;
 251         unsigned long moved_len;
 252         unsigned long excess = 0;
 253         unsigned long hiwater_vm;
 254         int split = 0;
 255         int err;
 256         bool need_rmap_locks;
 257
 258         /*
 259          * We'd prefer to avoid failure later on in do_munmap:
 260          * which may split one vma into three before unmapping.
 261          */
 262         if (mm->map_count >= sysctl_max_map_count - 3)
 263                 return -ENOMEM;
 264
 265         /*
 266          * Advise KSM to break any KSM pages in the area to be moved:
 267          * it would be confusing if they were to turn up at the new
 268          * location, where they happen to coincide with different KSM
 269          * pages recently unmapped.  But leave vma->vm_flags as it was,
 270          * so KSM can come around to merge on vma and new_vma afterwards.
 271          */
 272         err = ksm_madvise(vma, old_addr, old_addr + old_len,
 273                                                 MADV_UNMERGEABLE, &vm_flags);
 274         if (err)
 275                 return err;
 276
 277         new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
 278         new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
 279                            &need_rmap_locks);
 280         if (!new_vma)
 281                 return -ENOMEM;
 282
 283         moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
 284                                      need_rmap_locks);
 285         if (moved_len < old_len) {
 286                 /*
 287                  * On error, move entries back from new area to old,
 288                  * which will succeed since page tables still there,
 289                  * and then proceed to unmap new area instead of old.
 290                  */
 291                 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
 292                                  true);
 293                 vma = new_vma;
 294                 old_len = new_len;
 295                 old_addr = new_addr;
 296                 new_addr = -ENOMEM;
 297         } else if (vma->vm_file && vma->vm_file->f_op->mremap)
 298                 vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
 299
 300         /* Conceal VM_ACCOUNT so old reservation is not undone */
 301         if (vm_flags & VM_ACCOUNT) {
 302                 vma->vm_flags &= ~VM_ACCOUNT;
 303                 excess = vma->vm_end - vma->vm_start - old_len;
 304                 if (old_addr > vma->vm_start &&
 305                     old_addr + old_len < vma->vm_end)
 306                         split = 1;
 307         }
 308
 309         /*
 310          * If we failed to move page tables we still do total_vm increment
 311          * since do_munmap() will decrement it by old_len == new_len.
 312          *
 313          * Since total_vm is about to be raised artificially high for a
 314          * moment, we need to restore high watermark afterwards: if stats
 315          * are taken meanwhile, total_vm and hiwater_vm appear too high.
 316          * If this were a serious issue, we'd add a flag to do_munmap().
 317          */
 318         hiwater_vm = mm->hiwater_vm;
 319         vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
 320
 321         if (do_munmap(mm, old_addr, old_len) < 0) {
 322                 /* OOM: unable to split vma, just get accounts right */
 323                 vm_unacct_memory(excess >> PAGE_SHIFT);
 324                 excess = 0;
 325         }
 326         mm->hiwater_vm = hiwater_vm;
 327
 328         /* Restore VM_ACCOUNT if one or two pieces of vma left */
 329         if (excess) {
 330                 vma->vm_flags |= VM_ACCOUNT;
 331                 if (split)
 332                         vma->vm_next->vm_flags |= VM_ACCOUNT;
 333         }
 334
 335         if (vm_flags & VM_LOCKED) {
 336                 mm->locked_vm += new_len >> PAGE_SHIFT;
 337                 *locked = true;
 338         }
 339
 340         return new_addr;
 341 }
 342
 343 static struct vm_area_struct *vma_to_resize(unsigned long addr,
 344         unsigned long old_len, unsigned long new_len, unsigned long *p)
 345 {
 346         struct mm_struct *mm = current->mm;
 347         struct vm_area_struct *vma = find_vma(mm, addr);
 348
 349         if (!vma || vma->vm_start > addr)
 350                 goto Efault;
 351
 352         if (is_vm_hugetlb_page(vma))
 353                 goto Einval;
 354
 355 #ifdef CONFIG_PAX_SEGMEXEC
 356         if (pax_find_mirror_vma(vma))
 357                 goto Einval;
 358 #endif
 359
 360         /* We can't remap across vm area boundaries */
 361         if (old_len > vma->vm_end - addr)
 362                 goto Efault;
 363
 364         /* Need to be careful about a growing mapping */
 365         if (new_len > old_len) {
 366                 unsigned long pgoff;
 367
 368                 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
 369                         goto Efault;
 370                 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
 371                 pgoff += vma->vm_pgoff;
 372                 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
 373                         goto Einval;
 374         }
 375
 376         if (vma->vm_flags & VM_LOCKED) {
 377                 unsigned long locked, lock_limit;
 378                 locked = mm->locked_vm << PAGE_SHIFT;
 379                 lock_limit = rlimit(RLIMIT_MEMLOCK);
 380                 locked += new_len - old_len;
 381                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
 382                         goto Eagain;
 383         }
 384
 385         if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
 386                 goto Enomem;
 387
 388         if (vma->vm_flags & VM_ACCOUNT) {
 389                 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
 390                 if (security_vm_enough_memory_mm(mm, charged))
 391                         goto Efault;
 392                 *p = charged;
 393         }
 394
 395         return vma;
 396
 397 Efault: /* very odd choice for most of the cases, but... */
 398         return ERR_PTR(-EFAULT);
 399 Einval:
 400         return ERR_PTR(-EINVAL);
 401 Enomem:
 402         return ERR_PTR(-ENOMEM);
 403 Eagain:
 404         return ERR_PTR(-EAGAIN);
 405 }
 406
 407 static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
 408                 unsigned long new_addr, unsigned long new_len, bool *locked)
 409 {
 410         struct mm_struct *mm = current->mm;
 411         struct vm_area_struct *vma;
 412         unsigned long ret = -EINVAL;
 413         unsigned long charged = 0;
 414         unsigned long map_flags;
 415         unsigned long pax_task_size = TASK_SIZE;
 416
 417         if (new_addr & ~PAGE_MASK)
 418                 goto out;
 419
 420 #ifdef CONFIG_PAX_SEGMEXEC
 421         if (mm->pax_flags & MF_PAX_SEGMEXEC)
 422                 pax_task_size = SEGMEXEC_TASK_SIZE;
 423 #endif
 424
 425         pax_task_size -= PAGE_SIZE;
 426
 427         if (new_len > TASK_SIZE || new_addr > pax_task_size - new_len)
 428                 goto out;
 429
 430         /* Check if the location we're moving into overlaps the
 431          * old location at all, and fail if it does.
 432          */
 433         if (addr + old_len > new_addr && new_addr + new_len > addr)
 434                 goto out;
 435
 436         ret = do_munmap(mm, new_addr, new_len);
 437         if (ret)
 438                 goto out;
 439
 440         if (old_len >= new_len) {
 441                 ret = do_munmap(mm, addr+new_len, old_len - new_len);
 442                 if (ret && old_len != new_len)
 443                         goto out;
 444                 old_len = new_len;
 445         }
 446
 447         vma = vma_to_resize(addr, old_len, new_len, &charged);
 448         if (IS_ERR(vma)) {
 449                 ret = PTR_ERR(vma);
 450                 goto out;
 451         }
 452
 453         map_flags = MAP_FIXED;
 454         if (vma->vm_flags & VM_MAYSHARE)
 455                 map_flags |= MAP_SHARED;
 456
 457         ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
 458                                 ((addr - vma->vm_start) >> PAGE_SHIFT),
 459                                 map_flags);
 460         if (ret & ~PAGE_MASK)
 461                 goto out1;
 462
 463         ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
 464         if (!(ret & ~PAGE_MASK))
 465                 goto out;
 466 out1:
 467         vm_unacct_memory(charged);
 468
 469 out:
 470         return ret;
 471 }
 472
 473 static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 474 {
 475         unsigned long end = vma->vm_end + delta;
 476         if (end < vma->vm_end) /* overflow */
 477                 return 0;
 478         if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
 479                 return 0;
 480         if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
 481                               0, MAP_FIXED) & ~PAGE_MASK)
 482                 return 0;
 483         return 1;
 484 }
 485
 486 /*
 487  * Expand (or shrink) an existing mapping, potentially moving it at the
 488  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
 489  *
 490  * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
 491  * This option implies MREMAP_MAYMOVE.
 492  */
 493 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 494                 unsigned long, new_len, unsigned long, flags,
 495                 unsigned long, new_addr)
 496 {
 497         struct mm_struct *mm = current->mm;
 498         struct vm_area_struct *vma;
 499         unsigned long ret = -EINVAL;
 500         unsigned long charged = 0;
 501         bool locked = false;
 502         unsigned long pax_task_size = TASK_SIZE;
 503
 504         if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
 505                 return ret;
 506
 507         if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
 508                 return ret;
 509
 510         if (addr & ~PAGE_MASK)
 511                 return ret;
 512
 513         old_len = PAGE_ALIGN(old_len);
 514         new_len = PAGE_ALIGN(new_len);
 515
 516         /*
 517          * We allow a zero old-len as a special case
 518          * for DOS-emu "duplicate shm area" thing. But
 519          * a zero new-len is nonsensical.
 520          */
 521         if (!new_len)
 522                 return ret;
 523
 524 #ifdef CONFIG_PAX_SEGMEXEC
 525         if (mm->pax_flags & MF_PAX_SEGMEXEC)
 526                 pax_task_size = SEGMEXEC_TASK_SIZE;
 527 #endif
 528
 529         pax_task_size -= PAGE_SIZE;
 530
 531         if (new_len > pax_task_size || addr > pax_task_size-new_len ||
 532             old_len > pax_task_size || addr > pax_task_size-old_len)
 533                 return ret;
 534
 535         down_write(&current->mm->mmap_sem);
 536
 537         if (flags & MREMAP_FIXED) {
 538                 ret = mremap_to(addr, old_len, new_addr, new_len,
 539                                 &locked);
 540                 goto out;
 541         }
 542
 543         /*
 544          * Always allow a shrinking remap: that just unmaps
 545          * the unnecessary pages..
 546          * do_munmap does all the needed commit accounting
 547          */
 548         if (old_len >= new_len) {
 549                 ret = do_munmap(mm, addr+new_len, old_len - new_len);
 550                 if (ret && old_len != new_len)
 551                         goto out;
 552                 ret = addr;
 553                 goto out;
 554         }
 555
 556         /*
 557          * Ok, we need to grow..
 558          */
 559         vma = vma_to_resize(addr, old_len, new_len, &charged);
 560         if (IS_ERR(vma)) {
 561                 ret = PTR_ERR(vma);
 562                 goto out;
 563         }
 564
 565         /* old_len exactly to the end of the area..
 566          */
 567         if (old_len == vma->vm_end - addr) {
 568                 /* can we just expand the current mapping? */
 569                 if (vma_expandable(vma, new_len - old_len)) {
 570                         int pages = (new_len - old_len) >> PAGE_SHIFT;
 571
 572                         if (vma_adjust(vma, vma->vm_start, addr + new_len,
 573                                        vma->vm_pgoff, NULL)) {
 574                                 ret = -ENOMEM;
 575                                 goto out;
 576                         }
 577
 578                         vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
 579                         if (vma->vm_flags & VM_LOCKED) {
 580                                 mm->locked_vm += pages;
 581                                 locked = true;
 582                                 new_addr = addr;
 583                         }
 584                         ret = addr;
 585                         track_exec_limit(vma->vm_mm, vma->vm_start, addr + new_len, vma->vm_flags);
 586                         goto out;
 587                 }
 588         }
 589
 590         /*
 591          * We weren't able to just expand or shrink the area,
 592          * we need to create a new one and move it..
 593          */
 594         ret = -ENOMEM;
 595         if (flags & MREMAP_MAYMOVE) {
 596                 unsigned long map_flags = 0;
 597                 if (vma->vm_flags & VM_MAYSHARE)
 598                         map_flags |= MAP_SHARED;
 599
 600                 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
 601                                         vma->vm_pgoff +
 602                                         ((addr - vma->vm_start) >> PAGE_SHIFT),
 603                                         map_flags);
 604                 if (new_addr & ~PAGE_MASK) {
 605                         ret = new_addr;
 606                         goto out;
 607                 }
 608
 609                 map_flags = vma->vm_flags;
 610                 ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
 611                 if (!(ret & ~PAGE_MASK)) {
 612                         track_exec_limit(current->mm, addr, addr + old_len, 0UL);
 613                         track_exec_limit(current->mm, new_addr, new_addr + new_len, map_flags);
 614                 }
 615         }
 616 out:
 617         if (ret & ~PAGE_MASK)
 618                 vm_unacct_memory(charged);
 619         up_write(&current->mm->mmap_sem);
 620         if (locked && new_len > old_len)
 621                 mm_populate(new_addr + old_len, new_len - old_len);
 622         return ret;
 623 }