Errors using mbuff

[root <root@rtpendel.isr.uni-stuttgart.de>]

Hi!

I am using mbuff shared memory to share some data between userspace an 
realtime space.
My rt-module is allocating three different areas of memory with "mbuff_alloc".
After doing so, I always find the following message in my syslog:

May 22 17:54:34 pc1 kernel: mbuff: kernel shared memory driver v0.7.2 for 
Linux
May 22 17:54:34 pc1 kernel: mbuff: (C) Tomasz Motylewski et al., GPL
May 22 17:54:34 pc1 kernel: mbuff: registered as MISC device minor 254
May 22 17:54:37 pc1 kernel: closing unknown mbuff c98d95a0
May 22 17:54:37 pc1 kernel: closing unknown mbuff c98d9f60
May 22 17:54:37 pc1 kernel: closing unknown mbuff c98d9360
May 22 17:54:37 pc1 kernel: closing unknown mbuff c98d9d20
May 22 17:54:37 pc1 kernel: closing unknown mbuff c98d9520


What can cause this error message?

Thanks,
Christian