diff --git a/mm/memory.c b/mm/memory.c
index 6bef278..655e142 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1055,7 +1055,7 @@
 	if (is_vm_hugetlb_page(vma))
 		return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 
-	if (unlikely(is_pfn_mapping(vma))) {
+	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
 		/*
 		 * We do not free on error cases below as remove_vma
 		 * gets called on error from higher level routine
@@ -1327,7 +1327,7 @@
 	if (vma->vm_file)
 		uprobe_munmap(vma, start, end);
 
-	if (unlikely(is_pfn_mapping(vma)))
+	if (unlikely(vma->vm_flags & VM_PFNMAP))
 		untrack_pfn(vma, 0, 0);
 
 	if (start != end) {
@@ -2299,26 +2299,20 @@
 	 * There's a horrible special case to handle copy-on-write
 	 * behaviour that some programs depend on. We mark the "original"
 	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
+	 * See vm_normal_page() for details.
 	 */
-	if (addr == vma->vm_start && end == vma->vm_end) {
+	if (is_cow_mapping(vma->vm_flags)) {
+		if (addr != vma->vm_start || end != vma->vm_end)
+			return -EINVAL;
 		vma->vm_pgoff = pfn;
-		vma->vm_flags |= VM_PFN_AT_MMAP;
-	} else if (is_cow_mapping(vma->vm_flags))
+	}
+
+	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
+	if (err)
 		return -EINVAL;
 
 	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
 
-	err = track_pfn_remap(vma, &prot, pfn, PAGE_ALIGN(size));
-	if (err) {
-		/*
-		 * To indicate that track_pfn related cleanup is not
-		 * needed from higher level routine calling unmap_vmas
-		 */
-		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
-		vma->vm_flags &= ~VM_PFN_AT_MMAP;
-		return -EINVAL;
-	}
-
 	BUG_ON(addr >= end);
 	pfn -= addr >> PAGE_SHIFT;
 	pgd = pgd_offset(mm, addr);