confusa10 down, unresponsive to ipmi/console
confusa10 was hanging on an ansible task to restart dockerd; investigating, systemctl stop docker hung, as did start; no useful status from systemctl status docker.
looking at the rest of the machine, I saw several jenkins build jobs that had been started on April 12 (this was afternoon PDT on the 14th). Attempting to strace those jobs hung strace unkillably. Nothing useful in dmesg or tailing syslog, so I decided to reboot, and it didn't come back up. IPMI won't accept a connection.