mm/nommu: use offset_in_page macro

linux/mm.h provides offset_in_page() macro.  Let's use already predefined
macro instead of (addr & ~PAGE_MASK).
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/nommu.c

@@ -1497,7 +1497,7 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
 
 	if (copy_from_user(&a, arg, sizeof(a)))
 		return -EFAULT;
-	if (a.offset & ~PAGE_MASK)
+	if (offset_in_page(a.offset))
 		return -EINVAL;
 
 	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
@@ -1653,9 +1653,9 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
 			goto erase_whole_vma;
 		if (start < vma->vm_start || end > vma->vm_end)
 			return -EINVAL;
-		if (start & ~PAGE_MASK)
+		if (offset_in_page(start))
 			return -EINVAL;
-		if (end != vma->vm_end && end & ~PAGE_MASK)
+		if (end != vma->vm_end && offset_in_page(end))
 			return -EINVAL;
 		if (start != vma->vm_start && end != vma->vm_end) {
 			ret = split_vma(mm, vma, start, 1);
@@ -1736,7 +1736,7 @@ static unsigned long do_mremap(unsigned long addr,
 	if (old_len == 0 || new_len == 0)
 		return (unsigned long) -EINVAL;
 
-	if (addr & ~PAGE_MASK)
+	if (offset_in_page(addr))
 		return -EINVAL;
 
 	if (flags & MREMAP_FIXED && new_addr != addr)