[SOLVED]vlock endless loop hangs shutdown

Question

Recently my i86_64 system has been hanging on shutdown, the boot partition needing checking on restart (no errors reported).  After waiting over ten minutes for shutdown to complete, it's still hung.  CTL·ALT·DEL has no effect.
Running a debug shell (F9) also hangs when console (F1) freezes during shutdown.
"sync && poweroff -f " avoids the hang but the boot partitions still requires checking.
If I run "sudo umount /dev/sdf1 " (/boot) then "sudo sync && sudo reboot -f " the system shuts down and reboots without requiring file-system check.
"lsof " shows no open files on /boot/…
No serial console available.
What could be causing this..? & are they separate issues..?
This system boots with grub, has been around a long time, survived the switch to systemd and survived a major hardware upgrade.
Ref: freedesktop.org/systemd/debugging
Ref: Full System Spec
Edit: corrected the Sysinfo link.
Edit:
After upgrading to systemd-208, the debug console(F9) now works.  Shutdown hangs running vclock.  The error message from journalctl -f is
vlock[528]: pam_unix(vclock:auth): auth could not identify password for [..user..]
which continues until system is killed by hardware reboot.
I have compared /etc/pam.d/ to one from a properly behaving i686 laptop, and could see no differences, but my knowledge of PAM in very limited.
I'm running XFCE4 and run Xfce automatically using the xorg-xinit method at Start X at Login combining with  Automatic login to virtual console
Last edited by keepitsimpleengineer (2013-10-07 21:05:01)

Answer 1

cfr wrote:
I was thinking of e.g. https://bbs.archlinux.org/viewtopic.php?id=170756
What is vclock for? Seems to be connected with vdso? Is that right? Which is some sort of virtualised something? (That is, I didn't understand the explanation I found.)
vlock (recently moved into kbd) locks virtual consoles.  I presume opening XFCE at boot without password uses it.
keepitsimpleengineer wrote:I'm running XFCE4 and run Xfce automatically using the xorg-xinit method at Start X at Login combining with  Automatic login to virtual console
I believe this locks virtual console/terminal #1 (Alt-F1) in which to run X.
I presume systemd tries to unlock this locked virtual console as a part of shutdown, and stumbles in authorization, then continues  ad infinitum.  If so, two failures indicated; authorization (PAM), and systemd allowing the unlimited loop with failure.
keepitsimpleengineer wrote:
After upgrading to systemd-208, the debug console(Alt-F9) now works.  Shutdown hangs running vclock.  The error message from journalctl -f is
vclock[528]: pam_unix(vclock:auth): auth could not identify password for [..user..]
which continues until system is killed by hardware reboot.
In any case, I'm working struggling with that theory.  Curious as to why systemd-204-3-x86_64 had no problem with this while systemd-207-3-x86_64, systemd-207-5-x86_64, and systemd-208-1-x86_64 do.