diff --git a/mm/memory.c b/mm/memory.c
index 67f0ab9..6793b9c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -994,6 +994,29 @@
 	return end;
 }
 
+/**
+ * zap_vma_ptes - remove ptes mapping the vma
+ * @vma: vm_area_struct holding ptes to be zapped
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ *
+ * This function only unmaps ptes assigned to VM_PFNMAP vmas.
+ *
+ * The entire address range must be fully contained within the vma.
+ *
+ * Returns 0 if successful.
+ */
+int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
+		unsigned long size)
+{
+	if (address < vma->vm_start || address + size > vma->vm_end ||
+	    		!(vma->vm_flags & VM_PFNMAP))
+		return -1;
+	zap_page_range(vma, address, size, NULL);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(zap_vma_ptes);
+
 /*
  * Do a quick page-table lookup for a single page.
  */