Bug#762041: systemd: upgrading systemd results in /run/user/<uid> being emptied

[Ansgar Burchardt]

Michael Biebl <biebl at debian.org> writes:
> Am 18.09.2014 um 21:22 schrieb Sven Joachim:
>> This is exactly what I observe: before the upgrade /run/user was mounted
>> on a tmpfs, after the upgrade another tmpfs appeared mounted on
>> /run/user/1000, shadowing the files on /run/user.  Unmounting that new
>> tmpfs brought the old files back to light.
>
> I suspect what happened is, that you had a running (desktop) session,
> which was started while still using logind v208.
>
> You then logged in a second time after the upgrade to v215 (e.g. on the
> console), while not logging out of your first session.
>
> The start of the second (logind) session using v215 is causing the
> per-user tmpfs to be mounted interfering with the state of the first
> logind session.
>
> Is this observation correct?

For my memory, opening a second session was not required for this to
happen when I upgraded.

I suspect logind just mounts the tmpfs when it unserializes the session
state on restart. Probably the call to user_start in manager_startup
does so (which then calls user_mkdir_runtime_path).

Ansgar