Comment # 2 on bug 973529 from Howard Guo

Here you are:
root@howie /h/howard# cat /etc/pam.d/common-session
#%PAM-1.0
#
# This file is autogenerated by pam-config. All changes
# will be overwritten.
#
# Session-related modules common to all services
#
# This file is included from other service-specific PAM config files,
# and should contain a list of modules that define tasks to be performed
# at the start and end of sessions of *any* kind (both interactive and
# non-interactive
#
session required        pam_limits.so
session required        pam_unix.so     try_first_pass 
session optional        pam_umask.so
session optional        pam_systemd.so
session optional        pam_gnome_keyring.so    auto_start
only_if=gdm,gdm-password,lxdm,lightdm 
session optional        pam_env.so
root@howie /h/howard# cat /etc/pam.d/gdm
#%PAM-1.0
# GDM PAM standard configuration (with passwords)
auth     requisite      pam_nologin.so
auth     include        common-auth
account  include        common-account
password include        common-password
session  required       pam_loginuid.so
session  include        common-session

I do not use autologin.