mount.cifs i.c.w. autofs can stop working

Binary package hint: samba

I have encountered this problem on at least Kubuntu 8.04 and Ubuntu 9.04.

How to reproduce:

# install autofs and tools to mount cifs shares

$ sudo apt-get install autofs smbfs

$ cat /etc/auto.master
/smb /etc/auto.smb

$ /etc/init.d/autofs restart

# 'server' has a publicly accessible shares: share1, share2, share3

$ ls /smb/server
share1 share2 share3

$ ls /smb/server/share1
# contents of share1

# Switch to another terminal
$ cd /smb/server/share1

$ ls
# contents of share1

# Switch back to original terminal

# Here the trouble starts:

# Wait 5 minutes for autofs to start umounting the shares or force the issue with
$ for s in $(mount | grep cifs | awk '{print $1}'); do sudo umount $s; done

$ ls /smb/server
share1 share2 share3

# Here trouble is actually visible:

$ ls /smb/server/share1
ls: cannot access /smb/server/share1/share1: No such file or directory
ls: cannot access /smb/server/share1/share2: No such file or directory
ls: cannot access /smb/server/share1/share3: No such file or directory
share1 share2 share3

$ mount
[...]
automount(pid4875) on /smb type autofs (rw,fd=4,pgrp=4875,minproto=2,maxproto=4)
//server/share1 on /smb/server/share1 type cifs (rw,mand)
//server/share1/share1 on /smb/server/share1/share1 type cifs (rw,mand)
//server/share1/share2 on /smb/server/share1/share2 type cifs (rw,mand)
//server/share1/share3 on /smb/server/share1/share3 type cifs (rw,mand)

None of the actual map contents is accessible after this. In the other terminal, the map will still be accessible, but only for as long as the cwd is on that map.

The output to dmesg shows the following output

$ dmesg
[...]
[ 3335.652854] CIFS VFS: cifs_mount failed w/return code = -6

$ apt-cache policy smbfs
smbfs:
  Installed: 2:3.3.2-1ubuntu3
  Candidate: 2:3.3.2-1ubuntu3
  Version table:
 *** 2:3.3.2-1ubuntu3 0
        500 http://nl.archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status

$ apt-cache policy autofs
autofs:
  Installed: 4.1.4+debian-2.1ubuntu2
  Candidate: 4.1.4+debian-2.1ubuntu2
  Version table:
 *** 4.1.4+debian-2.1ubuntu2 0
        500 http://nl.archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status