diff -up man-pages-3.30/man2/open.2.pom man-pages-3.30/man2/open.2
--- man-pages-3.30/man2/open.2.pom	2010-11-01 15:55:38.000000000 +0100
+++ man-pages-3.30/man2/open.2	2010-11-11 12:26:16.000000000 +0100
@@ -319,11 +319,21 @@ and
 already exists, then
 .BR open ()
 will fail.
-The behavior of
+On Linux (on kernel 2.6 or later)
 .B O_EXCL
-is undefined if
+can be used in 
+.BR open ()
+without
 .B O_CREAT
-is not specified.
+if the
+.I pathname
+is a block device.
+If the block device is in use by the system (mounted etc)
+.BR open ()
+will fail with 
+.B EBUSY.
+Otherwise the behavior is undefined.
+
 
 When these two flags are specified, symbolic links are not followed:
 .\" POSIX.1-2001 explicitly requires this behavior.