Description of problem: After issuing 'shutdown -h now' the following was printed on a screen: [ 1636.645050] systemd[1]: segfault at d0 ip 00007f7201e4aa13 sp 00007ffffe753eb0 error 4 in systemd[7f7201de7000+105000] and after that a machine went into a fully catatonic state with a power switch as the only way out. After a reboot a check what journald recorded revealed not much more: systemd[1]: Unmounted Temporary Directory. systemd[1]: Caught <SEGV>, dumped core as pid 1002. systemd[1]: Freezing execution. kernel: systemd[1]: segfault at d0 ip 00007f7201e4aa13 sp 00007ffffe753eb0 error 4 in systemd[7f7201de7000+105000] Unfortunately a promissed core is nowhere to be found. The incident happened when file systems were apparently already unmounted so this is not exactly a surprise. I only found a few subsequent Failed to get D-Bus connection: Failed to connect to socket /run/systemd/private: Connection refused and that was it until "Reboot". Version-Release number of selected component (if applicable): systemd-206-2.fc20.x86_64 How reproducible: The next few tries to shutdown and power off the whole system worked as they should. OTOH a number of times I observed a random incidents of a rawhide dying while attempting to shutdown/reboot; only on those occasions this was completely silent. No information of any sort on a screen or otherwise. Just a dead machine.
Hmm, can you reproduce this? If so, please do "systemctl enable debug-shell". This will give you a debug shell on Alt-F9 on next reboot. Then try to reproduce the issue. Then, please run "gdb /usr/lib/systemd/systemd 1" and do "bt full", and provide the backtrace here (if needed as photo...)
(In reply to Lennart Poettering from comment #1) > Hmm, can you reproduce this? No, not really I am afraid. Fairly recently I had one of those mysterious lockups on an attempt to power off, without any traces anywhere (a black screen and nothing to be found in logs), but "normally" this works as expected. No other incident where at least something was recorded. I hoped that "error 4 in systemd[7f7201de7000+105000]" may at least give you some ideas.
Nope, not really I fear. Closing for now. If you manage to reproduce this, please reopen!