11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * mm/mremap.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * (C) Copyright 1996 Linus Torvalds 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Address space accounting code <alan@redhat.com> 71da177e4SLinus Torvalds * (C) Copyright 2002 Red Hat Inc, All Rights Reserved 81da177e4SLinus Torvalds */ 91da177e4SLinus Torvalds 101da177e4SLinus Torvalds #include <linux/mm.h> 111da177e4SLinus Torvalds #include <linux/hugetlb.h> 121da177e4SLinus Torvalds #include <linux/slab.h> 131da177e4SLinus Torvalds #include <linux/shm.h> 141da177e4SLinus Torvalds #include <linux/mman.h> 151da177e4SLinus Torvalds #include <linux/swap.h> 16c59ede7bSRandy.Dunlap #include <linux/capability.h> 171da177e4SLinus Torvalds #include <linux/fs.h> 181da177e4SLinus Torvalds #include <linux/highmem.h> 191da177e4SLinus Torvalds #include <linux/security.h> 201da177e4SLinus Torvalds #include <linux/syscalls.h> 21cddb8a5cSAndrea Arcangeli #include <linux/mmu_notifier.h> 221da177e4SLinus Torvalds 231da177e4SLinus Torvalds #include <asm/uaccess.h> 241da177e4SLinus Torvalds #include <asm/cacheflush.h> 251da177e4SLinus Torvalds #include <asm/tlbflush.h> 261da177e4SLinus Torvalds 27*ba470de4SRik van Riel #include "internal.h" 28*ba470de4SRik van Riel 297be7a546SHugh Dickins static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) 301da177e4SLinus Torvalds { 311da177e4SLinus Torvalds pgd_t *pgd; 321da177e4SLinus Torvalds pud_t *pud; 331da177e4SLinus Torvalds pmd_t *pmd; 341da177e4SLinus Torvalds 351da177e4SLinus Torvalds pgd = pgd_offset(mm, addr); 361da177e4SLinus Torvalds if (pgd_none_or_clear_bad(pgd)) 371da177e4SLinus Torvalds return NULL; 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds pud = pud_offset(pgd, addr); 401da177e4SLinus Torvalds if (pud_none_or_clear_bad(pud)) 411da177e4SLinus Torvalds return NULL; 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds pmd = pmd_offset(pud, addr); 441da177e4SLinus Torvalds if (pmd_none_or_clear_bad(pmd)) 451da177e4SLinus Torvalds return NULL; 461da177e4SLinus Torvalds 477be7a546SHugh Dickins return pmd; 481da177e4SLinus Torvalds } 491da177e4SLinus Torvalds 507be7a546SHugh Dickins static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr) 511da177e4SLinus Torvalds { 521da177e4SLinus Torvalds pgd_t *pgd; 531da177e4SLinus Torvalds pud_t *pud; 54c74df32cSHugh Dickins pmd_t *pmd; 551da177e4SLinus Torvalds 561da177e4SLinus Torvalds pgd = pgd_offset(mm, addr); 571da177e4SLinus Torvalds pud = pud_alloc(mm, pgd, addr); 581da177e4SLinus Torvalds if (!pud) 59c74df32cSHugh Dickins return NULL; 607be7a546SHugh Dickins 611da177e4SLinus Torvalds pmd = pmd_alloc(mm, pud, addr); 627be7a546SHugh Dickins if (!pmd) 63c74df32cSHugh Dickins return NULL; 647be7a546SHugh Dickins 651bb3630eSHugh Dickins if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr)) 66c74df32cSHugh Dickins return NULL; 67c74df32cSHugh Dickins 687be7a546SHugh Dickins return pmd; 691da177e4SLinus Torvalds } 701da177e4SLinus Torvalds 717be7a546SHugh Dickins static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, 727be7a546SHugh Dickins unsigned long old_addr, unsigned long old_end, 737be7a546SHugh Dickins struct vm_area_struct *new_vma, pmd_t *new_pmd, 747be7a546SHugh Dickins unsigned long new_addr) 751da177e4SLinus Torvalds { 761da177e4SLinus Torvalds struct address_space *mapping = NULL; 771da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 787be7a546SHugh Dickins pte_t *old_pte, *new_pte, pte; 794c21e2f2SHugh Dickins spinlock_t *old_ptl, *new_ptl; 80cddb8a5cSAndrea Arcangeli unsigned long old_start; 811da177e4SLinus Torvalds 82cddb8a5cSAndrea Arcangeli old_start = old_addr; 83cddb8a5cSAndrea Arcangeli mmu_notifier_invalidate_range_start(vma->vm_mm, 84cddb8a5cSAndrea Arcangeli old_start, old_end); 851da177e4SLinus Torvalds if (vma->vm_file) { 861da177e4SLinus Torvalds /* 871da177e4SLinus Torvalds * Subtle point from Rajesh Venkatasubramanian: before 881da177e4SLinus Torvalds * moving file-based ptes, we must lock vmtruncate out, 891da177e4SLinus Torvalds * since it might clean the dst vma before the src vma, 901da177e4SLinus Torvalds * and we propagate stale pages into the dst afterward. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds mapping = vma->vm_file->f_mapping; 931da177e4SLinus Torvalds spin_lock(&mapping->i_mmap_lock); 941da177e4SLinus Torvalds if (new_vma->vm_truncate_count && 951da177e4SLinus Torvalds new_vma->vm_truncate_count != vma->vm_truncate_count) 961da177e4SLinus Torvalds new_vma->vm_truncate_count = 0; 971da177e4SLinus Torvalds } 981da177e4SLinus Torvalds 994c21e2f2SHugh Dickins /* 1004c21e2f2SHugh Dickins * We don't have to worry about the ordering of src and dst 1014c21e2f2SHugh Dickins * pte locks because exclusive mmap_sem prevents deadlock. 1024c21e2f2SHugh Dickins */ 103c74df32cSHugh Dickins old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); 1047be7a546SHugh Dickins new_pte = pte_offset_map_nested(new_pmd, new_addr); 1054c21e2f2SHugh Dickins new_ptl = pte_lockptr(mm, new_pmd); 1064c21e2f2SHugh Dickins if (new_ptl != old_ptl) 107f20dc5f7SIngo Molnar spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1086606c3e0SZachary Amsden arch_enter_lazy_mmu_mode(); 1098b1f3124SNick Piggin 1107be7a546SHugh Dickins for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, 1117be7a546SHugh Dickins new_pte++, new_addr += PAGE_SIZE) { 1127be7a546SHugh Dickins if (pte_none(*old_pte)) 1137be7a546SHugh Dickins continue; 1147be7a546SHugh Dickins pte = ptep_clear_flush(vma, old_addr, old_pte); 1157be7a546SHugh Dickins pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); 1167be7a546SHugh Dickins set_pte_at(mm, new_addr, new_pte, pte); 1171da177e4SLinus Torvalds } 1187be7a546SHugh Dickins 1196606c3e0SZachary Amsden arch_leave_lazy_mmu_mode(); 1204c21e2f2SHugh Dickins if (new_ptl != old_ptl) 1214c21e2f2SHugh Dickins spin_unlock(new_ptl); 1227be7a546SHugh Dickins pte_unmap_nested(new_pte - 1); 123c74df32cSHugh Dickins pte_unmap_unlock(old_pte - 1, old_ptl); 1241da177e4SLinus Torvalds if (mapping) 1251da177e4SLinus Torvalds spin_unlock(&mapping->i_mmap_lock); 126cddb8a5cSAndrea Arcangeli mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end); 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1297be7a546SHugh Dickins #define LATENCY_LIMIT (64 * PAGE_SIZE) 1307be7a546SHugh Dickins 131b6a2fea3SOllie Wild unsigned long move_page_tables(struct vm_area_struct *vma, 1321da177e4SLinus Torvalds unsigned long old_addr, struct vm_area_struct *new_vma, 1331da177e4SLinus Torvalds unsigned long new_addr, unsigned long len) 1341da177e4SLinus Torvalds { 1357be7a546SHugh Dickins unsigned long extent, next, old_end; 1367be7a546SHugh Dickins pmd_t *old_pmd, *new_pmd; 1371da177e4SLinus Torvalds 1387be7a546SHugh Dickins old_end = old_addr + len; 1397be7a546SHugh Dickins flush_cache_range(vma, old_addr, old_end); 1401da177e4SLinus Torvalds 1417be7a546SHugh Dickins for (; old_addr < old_end; old_addr += extent, new_addr += extent) { 1421da177e4SLinus Torvalds cond_resched(); 1437be7a546SHugh Dickins next = (old_addr + PMD_SIZE) & PMD_MASK; 1447be7a546SHugh Dickins if (next - 1 > old_end) 1457be7a546SHugh Dickins next = old_end; 1467be7a546SHugh Dickins extent = next - old_addr; 1477be7a546SHugh Dickins old_pmd = get_old_pmd(vma->vm_mm, old_addr); 1487be7a546SHugh Dickins if (!old_pmd) 1497be7a546SHugh Dickins continue; 1507be7a546SHugh Dickins new_pmd = alloc_new_pmd(vma->vm_mm, new_addr); 1517be7a546SHugh Dickins if (!new_pmd) 1527be7a546SHugh Dickins break; 1537be7a546SHugh Dickins next = (new_addr + PMD_SIZE) & PMD_MASK; 1547be7a546SHugh Dickins if (extent > next - new_addr) 1557be7a546SHugh Dickins extent = next - new_addr; 1567be7a546SHugh Dickins if (extent > LATENCY_LIMIT) 1577be7a546SHugh Dickins extent = LATENCY_LIMIT; 1587be7a546SHugh Dickins move_ptes(vma, old_pmd, old_addr, old_addr + extent, 1597be7a546SHugh Dickins new_vma, new_pmd, new_addr); 1601da177e4SLinus Torvalds } 1617be7a546SHugh Dickins 1627be7a546SHugh Dickins return len + old_addr - old_end; /* how much done */ 1631da177e4SLinus Torvalds } 1641da177e4SLinus Torvalds 1651da177e4SLinus Torvalds static unsigned long move_vma(struct vm_area_struct *vma, 1661da177e4SLinus Torvalds unsigned long old_addr, unsigned long old_len, 1671da177e4SLinus Torvalds unsigned long new_len, unsigned long new_addr) 1681da177e4SLinus Torvalds { 1691da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 1701da177e4SLinus Torvalds struct vm_area_struct *new_vma; 1711da177e4SLinus Torvalds unsigned long vm_flags = vma->vm_flags; 1721da177e4SLinus Torvalds unsigned long new_pgoff; 1731da177e4SLinus Torvalds unsigned long moved_len; 1741da177e4SLinus Torvalds unsigned long excess = 0; 175365e9c87SHugh Dickins unsigned long hiwater_vm; 1761da177e4SLinus Torvalds int split = 0; 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* 1791da177e4SLinus Torvalds * We'd prefer to avoid failure later on in do_munmap: 1801da177e4SLinus Torvalds * which may split one vma into three before unmapping. 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds if (mm->map_count >= sysctl_max_map_count - 3) 1831da177e4SLinus Torvalds return -ENOMEM; 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); 1861da177e4SLinus Torvalds new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); 1871da177e4SLinus Torvalds if (!new_vma) 1881da177e4SLinus Torvalds return -ENOMEM; 1891da177e4SLinus Torvalds 1901da177e4SLinus Torvalds moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); 1911da177e4SLinus Torvalds if (moved_len < old_len) { 1921da177e4SLinus Torvalds /* 1931da177e4SLinus Torvalds * On error, move entries back from new area to old, 1941da177e4SLinus Torvalds * which will succeed since page tables still there, 1951da177e4SLinus Torvalds * and then proceed to unmap new area instead of old. 1961da177e4SLinus Torvalds */ 1971da177e4SLinus Torvalds move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); 1981da177e4SLinus Torvalds vma = new_vma; 1991da177e4SLinus Torvalds old_len = new_len; 2001da177e4SLinus Torvalds old_addr = new_addr; 2011da177e4SLinus Torvalds new_addr = -ENOMEM; 2021da177e4SLinus Torvalds } 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /* Conceal VM_ACCOUNT so old reservation is not undone */ 2051da177e4SLinus Torvalds if (vm_flags & VM_ACCOUNT) { 2061da177e4SLinus Torvalds vma->vm_flags &= ~VM_ACCOUNT; 2071da177e4SLinus Torvalds excess = vma->vm_end - vma->vm_start - old_len; 2081da177e4SLinus Torvalds if (old_addr > vma->vm_start && 2091da177e4SLinus Torvalds old_addr + old_len < vma->vm_end) 2101da177e4SLinus Torvalds split = 1; 2111da177e4SLinus Torvalds } 2121da177e4SLinus Torvalds 21371799062SKirill Korotaev /* 214365e9c87SHugh Dickins * If we failed to move page tables we still do total_vm increment 215365e9c87SHugh Dickins * since do_munmap() will decrement it by old_len == new_len. 216365e9c87SHugh Dickins * 217365e9c87SHugh Dickins * Since total_vm is about to be raised artificially high for a 218365e9c87SHugh Dickins * moment, we need to restore high watermark afterwards: if stats 219365e9c87SHugh Dickins * are taken meanwhile, total_vm and hiwater_vm appear too high. 220365e9c87SHugh Dickins * If this were a serious issue, we'd add a flag to do_munmap(). 22171799062SKirill Korotaev */ 222365e9c87SHugh Dickins hiwater_vm = mm->hiwater_vm; 22371799062SKirill Korotaev mm->total_vm += new_len >> PAGE_SHIFT; 224ab50b8edSHugh Dickins vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); 22571799062SKirill Korotaev 2261da177e4SLinus Torvalds if (do_munmap(mm, old_addr, old_len) < 0) { 2271da177e4SLinus Torvalds /* OOM: unable to split vma, just get accounts right */ 2281da177e4SLinus Torvalds vm_unacct_memory(excess >> PAGE_SHIFT); 2291da177e4SLinus Torvalds excess = 0; 2301da177e4SLinus Torvalds } 231365e9c87SHugh Dickins mm->hiwater_vm = hiwater_vm; 2321da177e4SLinus Torvalds 2331da177e4SLinus Torvalds /* Restore VM_ACCOUNT if one or two pieces of vma left */ 2341da177e4SLinus Torvalds if (excess) { 2351da177e4SLinus Torvalds vma->vm_flags |= VM_ACCOUNT; 2361da177e4SLinus Torvalds if (split) 2371da177e4SLinus Torvalds vma->vm_next->vm_flags |= VM_ACCOUNT; 2381da177e4SLinus Torvalds } 2391da177e4SLinus Torvalds 2401da177e4SLinus Torvalds if (vm_flags & VM_LOCKED) { 2411da177e4SLinus Torvalds mm->locked_vm += new_len >> PAGE_SHIFT; 2421da177e4SLinus Torvalds if (new_len > old_len) 243*ba470de4SRik van Riel mlock_vma_pages_range(new_vma, new_addr + old_len, 2441da177e4SLinus Torvalds new_addr + new_len); 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds return new_addr; 2481da177e4SLinus Torvalds } 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds /* 2511da177e4SLinus Torvalds * Expand (or shrink) an existing mapping, potentially moving it at the 2521da177e4SLinus Torvalds * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) 2531da177e4SLinus Torvalds * 2541da177e4SLinus Torvalds * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise 2551da177e4SLinus Torvalds * This option implies MREMAP_MAYMOVE. 2561da177e4SLinus Torvalds */ 2571da177e4SLinus Torvalds unsigned long do_mremap(unsigned long addr, 2581da177e4SLinus Torvalds unsigned long old_len, unsigned long new_len, 2591da177e4SLinus Torvalds unsigned long flags, unsigned long new_addr) 2601da177e4SLinus Torvalds { 261d0de32d9SHugh Dickins struct mm_struct *mm = current->mm; 2621da177e4SLinus Torvalds struct vm_area_struct *vma; 2631da177e4SLinus Torvalds unsigned long ret = -EINVAL; 2641da177e4SLinus Torvalds unsigned long charged = 0; 2651da177e4SLinus Torvalds 2661da177e4SLinus Torvalds if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) 2671da177e4SLinus Torvalds goto out; 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvalds if (addr & ~PAGE_MASK) 2701da177e4SLinus Torvalds goto out; 2711da177e4SLinus Torvalds 2721da177e4SLinus Torvalds old_len = PAGE_ALIGN(old_len); 2731da177e4SLinus Torvalds new_len = PAGE_ALIGN(new_len); 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* 2761da177e4SLinus Torvalds * We allow a zero old-len as a special case 2771da177e4SLinus Torvalds * for DOS-emu "duplicate shm area" thing. But 2781da177e4SLinus Torvalds * a zero new-len is nonsensical. 2791da177e4SLinus Torvalds */ 2801da177e4SLinus Torvalds if (!new_len) 2811da177e4SLinus Torvalds goto out; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds /* new_addr is only valid if MREMAP_FIXED is specified */ 2841da177e4SLinus Torvalds if (flags & MREMAP_FIXED) { 2851da177e4SLinus Torvalds if (new_addr & ~PAGE_MASK) 2861da177e4SLinus Torvalds goto out; 2871da177e4SLinus Torvalds if (!(flags & MREMAP_MAYMOVE)) 2881da177e4SLinus Torvalds goto out; 2891da177e4SLinus Torvalds 2901da177e4SLinus Torvalds if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) 2911da177e4SLinus Torvalds goto out; 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds /* Check if the location we're moving into overlaps the 2941da177e4SLinus Torvalds * old location at all, and fail if it does. 2951da177e4SLinus Torvalds */ 2961da177e4SLinus Torvalds if ((new_addr <= addr) && (new_addr+new_len) > addr) 2971da177e4SLinus Torvalds goto out; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds if ((addr <= new_addr) && (addr+old_len) > new_addr) 3001da177e4SLinus Torvalds goto out; 3011da177e4SLinus Torvalds 302c80544dcSStephen Hemminger ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); 303ed032189SEric Paris if (ret) 304ed032189SEric Paris goto out; 305ed032189SEric Paris 306d0de32d9SHugh Dickins ret = do_munmap(mm, new_addr, new_len); 3071da177e4SLinus Torvalds if (ret) 3081da177e4SLinus Torvalds goto out; 3091da177e4SLinus Torvalds } 3101da177e4SLinus Torvalds 3111da177e4SLinus Torvalds /* 3121da177e4SLinus Torvalds * Always allow a shrinking remap: that just unmaps 3131da177e4SLinus Torvalds * the unnecessary pages.. 3141da177e4SLinus Torvalds * do_munmap does all the needed commit accounting 3151da177e4SLinus Torvalds */ 3161da177e4SLinus Torvalds if (old_len >= new_len) { 317d0de32d9SHugh Dickins ret = do_munmap(mm, addr+new_len, old_len - new_len); 3181da177e4SLinus Torvalds if (ret && old_len != new_len) 3191da177e4SLinus Torvalds goto out; 3201da177e4SLinus Torvalds ret = addr; 3211da177e4SLinus Torvalds if (!(flags & MREMAP_FIXED) || (new_addr == addr)) 3221da177e4SLinus Torvalds goto out; 3231da177e4SLinus Torvalds old_len = new_len; 3241da177e4SLinus Torvalds } 3251da177e4SLinus Torvalds 3261da177e4SLinus Torvalds /* 3271da177e4SLinus Torvalds * Ok, we need to grow.. or relocate. 3281da177e4SLinus Torvalds */ 3291da177e4SLinus Torvalds ret = -EFAULT; 330d0de32d9SHugh Dickins vma = find_vma(mm, addr); 3311da177e4SLinus Torvalds if (!vma || vma->vm_start > addr) 3321da177e4SLinus Torvalds goto out; 3331da177e4SLinus Torvalds if (is_vm_hugetlb_page(vma)) { 3341da177e4SLinus Torvalds ret = -EINVAL; 3351da177e4SLinus Torvalds goto out; 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds /* We can't remap across vm area boundaries */ 3381da177e4SLinus Torvalds if (old_len > vma->vm_end - addr) 3391da177e4SLinus Torvalds goto out; 3404d7672b4SLinus Torvalds if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { 3411da177e4SLinus Torvalds if (new_len > old_len) 3421da177e4SLinus Torvalds goto out; 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds if (vma->vm_flags & VM_LOCKED) { 3451da177e4SLinus Torvalds unsigned long locked, lock_limit; 346d0de32d9SHugh Dickins locked = mm->locked_vm << PAGE_SHIFT; 3471da177e4SLinus Torvalds lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 3481da177e4SLinus Torvalds locked += new_len - old_len; 3491da177e4SLinus Torvalds ret = -EAGAIN; 3501da177e4SLinus Torvalds if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 3511da177e4SLinus Torvalds goto out; 3521da177e4SLinus Torvalds } 353d0de32d9SHugh Dickins if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) { 3541da177e4SLinus Torvalds ret = -ENOMEM; 3551da177e4SLinus Torvalds goto out; 356119f657cSakpm@osdl.org } 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds if (vma->vm_flags & VM_ACCOUNT) { 3591da177e4SLinus Torvalds charged = (new_len - old_len) >> PAGE_SHIFT; 3601da177e4SLinus Torvalds if (security_vm_enough_memory(charged)) 3611da177e4SLinus Torvalds goto out_nc; 3621da177e4SLinus Torvalds } 3631da177e4SLinus Torvalds 3641da177e4SLinus Torvalds /* old_len exactly to the end of the area.. 3651da177e4SLinus Torvalds * And we're not relocating the area. 3661da177e4SLinus Torvalds */ 3671da177e4SLinus Torvalds if (old_len == vma->vm_end - addr && 3681da177e4SLinus Torvalds !((flags & MREMAP_FIXED) && (addr != new_addr)) && 3691da177e4SLinus Torvalds (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { 3701da177e4SLinus Torvalds unsigned long max_addr = TASK_SIZE; 3711da177e4SLinus Torvalds if (vma->vm_next) 3721da177e4SLinus Torvalds max_addr = vma->vm_next->vm_start; 3731da177e4SLinus Torvalds /* can we just expand the current mapping? */ 3741da177e4SLinus Torvalds if (max_addr - addr >= new_len) { 3751da177e4SLinus Torvalds int pages = (new_len - old_len) >> PAGE_SHIFT; 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds vma_adjust(vma, vma->vm_start, 3781da177e4SLinus Torvalds addr + new_len, vma->vm_pgoff, NULL); 3791da177e4SLinus Torvalds 380d0de32d9SHugh Dickins mm->total_vm += pages; 381d0de32d9SHugh Dickins vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); 3821da177e4SLinus Torvalds if (vma->vm_flags & VM_LOCKED) { 383d0de32d9SHugh Dickins mm->locked_vm += pages; 384*ba470de4SRik van Riel mlock_vma_pages_range(vma, addr + old_len, 3851da177e4SLinus Torvalds addr + new_len); 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds ret = addr; 3881da177e4SLinus Torvalds goto out; 3891da177e4SLinus Torvalds } 3901da177e4SLinus Torvalds } 3911da177e4SLinus Torvalds 3921da177e4SLinus Torvalds /* 3931da177e4SLinus Torvalds * We weren't able to just expand or shrink the area, 3941da177e4SLinus Torvalds * we need to create a new one and move it.. 3951da177e4SLinus Torvalds */ 3961da177e4SLinus Torvalds ret = -ENOMEM; 3971da177e4SLinus Torvalds if (flags & MREMAP_MAYMOVE) { 3981da177e4SLinus Torvalds if (!(flags & MREMAP_FIXED)) { 3991da177e4SLinus Torvalds unsigned long map_flags = 0; 4001da177e4SLinus Torvalds if (vma->vm_flags & VM_MAYSHARE) 4011da177e4SLinus Torvalds map_flags |= MAP_SHARED; 4021da177e4SLinus Torvalds 4031da177e4SLinus Torvalds new_addr = get_unmapped_area(vma->vm_file, 0, new_len, 4041da177e4SLinus Torvalds vma->vm_pgoff, map_flags); 405ed032189SEric Paris if (new_addr & ~PAGE_MASK) { 4061da177e4SLinus Torvalds ret = new_addr; 407ed032189SEric Paris goto out; 408ed032189SEric Paris } 409ed032189SEric Paris 410c80544dcSStephen Hemminger ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); 411ed032189SEric Paris if (ret) 4121da177e4SLinus Torvalds goto out; 4131da177e4SLinus Torvalds } 4141da177e4SLinus Torvalds ret = move_vma(vma, addr, old_len, new_len, new_addr); 4151da177e4SLinus Torvalds } 4161da177e4SLinus Torvalds out: 4171da177e4SLinus Torvalds if (ret & ~PAGE_MASK) 4181da177e4SLinus Torvalds vm_unacct_memory(charged); 4191da177e4SLinus Torvalds out_nc: 4201da177e4SLinus Torvalds return ret; 4211da177e4SLinus Torvalds } 4221da177e4SLinus Torvalds 4231da177e4SLinus Torvalds asmlinkage unsigned long sys_mremap(unsigned long addr, 4241da177e4SLinus Torvalds unsigned long old_len, unsigned long new_len, 4251da177e4SLinus Torvalds unsigned long flags, unsigned long new_addr) 4261da177e4SLinus Torvalds { 4271da177e4SLinus Torvalds unsigned long ret; 4281da177e4SLinus Torvalds 4291da177e4SLinus Torvalds down_write(¤t->mm->mmap_sem); 4301da177e4SLinus Torvalds ret = do_mremap(addr, old_len, new_len, flags, new_addr); 4311da177e4SLinus Torvalds up_write(¤t->mm->mmap_sem); 4321da177e4SLinus Torvalds return ret; 4331da177e4SLinus Torvalds } 434