diff -u util-linux-2.17.2/debian/changelog util-linux-2.17.2/debian/changelog
--- util-linux-2.17.2/debian/changelog
+++ util-linux-2.17.2/debian/changelog
@@ -1,3 +1,13 @@
+util-linux (2.17.2-0ubuntu2) lucid; urgency=low
+
+  * Proposed bug fix for umount failing on autofs mounts as covered by
+    bug https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/579858
+    - Change fstab.c so it will not attempt to add an 'existing' mount that is
+      not found in /etc/mtab (by fstype being NULL) but issue a warning message
+      instead. 
+
+ -- Paul Crawford <psc@sat.dundee.ac.uk>  Mon, 11 Oct 2010 17:30:26 +0100
+
 util-linux (2.17.2-0ubuntu1) lucid; urgency=low
 
   * Merge from Debian experimental, remaining changes:
diff -u util-linux-2.17.2/mount/fstab.c util-linux-2.17.2/mount/fstab.c
--- util-linux-2.17.2/mount/fstab.c
+++ util-linux-2.17.2/mount/fstab.c
@@ -863,24 +863,32 @@
 			mc->m.mnt_dir = xstrdup(instead->mnt_dir);
 		}
 	} else if (instead) {
-		/* not found, add a new entry */
-		absent = xmalloc(sizeof(*absent));
-		absent->m.mnt_fsname = xstrdup(instead->mnt_fsname);
-		absent->m.mnt_dir = xstrdup(instead->mnt_dir);
-		absent->m.mnt_type = xstrdup(instead->mnt_type);
-		absent->m.mnt_opts = xstrdup(instead->mnt_opts);
-		absent->m.mnt_freq = instead->mnt_freq;
-		absent->m.mnt_passno = instead->mnt_passno;
-		absent->nxt = mc0;
-		if (mc0->prev != NULL) {
-			absent->prev = mc0->prev;
-			mc0->prev->nxt = absent;
+		if(instead->mnt_fsname != NULL) {	
+			/* not found, add a new entry */
+			absent = xmalloc(sizeof(*absent));
+			absent->m.mnt_fsname = xstrdup(instead->mnt_fsname);
+			absent->m.mnt_dir = xstrdup(instead->mnt_dir);
+			absent->m.mnt_type = xstrdup(instead->mnt_type);
+			absent->m.mnt_opts = xstrdup(instead->mnt_opts);
+			absent->m.mnt_freq = instead->mnt_freq;
+			absent->m.mnt_passno = instead->mnt_passno;
+			absent->nxt = mc0;
+			if (mc0->prev != NULL) {
+				absent->prev = mc0->prev;
+				mc0->prev->nxt = absent;
+			} else {
+				absent->prev = mc0;
+			}
+			mc0->prev = absent;
+			if (mc0->nxt == NULL)
+				mc0->nxt = absent;
 		} else {
-			absent->prev = mc0;
+			/* Trying to remount read-only an 'existing' system that is not in mtab? 
+			 * See line 258 of umount.c and https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/579858 
+			 */
+			error (_("%s has null fsname - mtab not updated"),
+					instead->mnt_dir);
 		}
-		mc0->prev = absent;
-		if (mc0->nxt == NULL)
-			mc0->nxt = absent;
 	}
 
 	/* write chain to mtemp */