diff --git a/include/linux/mm.h b/include/linux/mm.h
index ffee2f743418..2be8d9b5e46f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -145,6 +145,15 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_WRITE	0x01	/* Fault was a write access */
 #define FAULT_FLAG_NONLINEAR	0x02	/* Fault was via a nonlinear mapping */
 
+static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)
+{
+	return ((vma->vm_flags & VM_PFNMAP) && vma->vm_pgoff);
+}
+
+static inline int is_pfn_mapping(struct vm_area_struct *vma)
+{
+	return (vma->vm_flags & VM_PFNMAP);
+}
 
 /*
  * vm_fault is filled by the the pagefault handler and passed to the vma's
diff --git a/mm/memory.c b/mm/memory.c
index 164951c47305..cef95c8c77fa 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1575,11 +1575,10 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	 * behaviour that some programs depend on. We mark the "original"
 	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
 	 */
-	if (is_cow_mapping(vma->vm_flags)) {
-		if (addr != vma->vm_start || end != vma->vm_end)
-			return -EINVAL;
+	if (addr == vma->vm_start && end == vma->vm_end)
 		vma->vm_pgoff = pfn;
-	}
+	else if (is_cow_mapping(vma->vm_flags))
+		return -EINVAL;
 
 	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;