[systemd-devel] systemd v4[01] and graphical login managers

Lennart Poettering lennart at poettering.net
Thu Feb 9 10:38:39 PST 2012

On Thu, 09.02.12 18:50, Christian Hesse (list at eworm.de) wrote:

> Hello everybody,
> starting with systemd v40 I have problems with graphical login managers
> (tested with lightdm and slim on Arch).
> After successful user authentication the login manager is killed by
> systemd-logind with SIGTERM. I think this is because of the changes in commit
> "logind: if we have to stop a session, kill at least its leader" - not sure
> though. Anybody else with this problem?

Yes, there have been similar reports. I am not entirely sure what's
going on here, but it's most likely by code that closes all open fds
after the PAM session start hook finished in the parent process of login
processes. It's OK to close all open fds in the child, but it's not OK
to do so in the parent.

systemd-logind tracks open sessions by keeping open a FIFO fd to the PAM
session client. When the session client dies then systemd will see that
as EOF. Now, if the PAM client side eagerly closes all fds it finds this
will trigger an immediate end of session.


Lennart Poettering - Red Hat, Inc.

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