diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 4e167b5..20476d1 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -143,7 +143,7 @@
 #define _PAGE_ACCESSED	0x020
 #define _PAGE_DIRTY	0x040
 #define _PAGE_PSE	0x080	/* 2MB page */
-#define _PAGE_FILE	0x040	/* set:pagecache, unset:swap */
+#define _PAGE_FILE	0x040	/* nonlinear file mapping, saved PTE; unset:swap */
 #define _PAGE_GLOBAL	0x100	/* Global TLB entry */
 
 #define _PAGE_PROTNONE	0x080	/* If not present */