Comment 14 for bug 1321354

This behaviour appeared for me first time after upgrade to Ubuntu 17.04. Several versions before (all from 14.04) there had no such problem. And now after some idle time I can see constant network load (down ~300 kB/s, up ~450 kB/s, see screenshot in attachemenet).

Unmounting helps (but sometimes umount hangs for several minutes before unmounting)