Bug#870126: ecryptfs-mount-private: mount: No such file or directory

[Vladimir K]

So linkage of user and session keyrings is apparently done by pam_keyinit 
module.

There is a line:

    session    optional   pam_keyinit.so force revoke

in /etc/pam.d/login, but not in /etc/pam.d/lightdm.