Happens for some time already in latest mainline kernel.
I'll attach relevant dmesg and /etc/mtab parts.
Created attachment 32032 [details]
Warnings in dmesg after was up for about 3 hours
Created attachment 32042 [details]
/etc/mtab with some ntf mounts cut out
Created attachment 32072 [details]
Argh, I uploaded the wrong, the local mtab, this one is mtab of the affected system
*** This bug has been marked as a duplicate of bug 19062 ***