Commit 1d391686 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds

mremap: don't do uneccesary checks if new_len == old_len

The "new_len > old_len" branch in vma_to_resize() looks very confusing.
It only covers the VM_DONTEXPAND/pgoff checks but everything below is
equally unneeded if new_len == old_len.

Change this code to return if "new_len == old_len", new_len < old_len is
not possible, otherwise the code below is wrong anyway.
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d456fb9e
...@@ -346,6 +346,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, ...@@ -346,6 +346,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
{ {
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;
struct vm_area_struct *vma = find_vma(mm, addr); struct vm_area_struct *vma = find_vma(mm, addr);
unsigned long pgoff;
if (!vma || vma->vm_start > addr) if (!vma || vma->vm_start > addr)
return ERR_PTR(-EFAULT); return ERR_PTR(-EFAULT);
...@@ -357,17 +358,17 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, ...@@ -357,17 +358,17 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
if (old_len > vma->vm_end - addr) if (old_len > vma->vm_end - addr)
return ERR_PTR(-EFAULT); return ERR_PTR(-EFAULT);
if (new_len == old_len)
return vma;
/* Need to be careful about a growing mapping */ /* Need to be careful about a growing mapping */
if (new_len > old_len) { pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
unsigned long pgoff; pgoff += vma->vm_pgoff;
if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) return ERR_PTR(-EINVAL);
return ERR_PTR(-EFAULT);
pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
pgoff += vma->vm_pgoff; return ERR_PTR(-EFAULT);
if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
return ERR_PTR(-EINVAL);
}
if (vma->vm_flags & VM_LOCKED) { if (vma->vm_flags & VM_LOCKED) {
unsigned long locked, lock_limit; unsigned long locked, lock_limit;
......
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