This seems to be caused by a bug in the e1000 module. If I remove that module with rmmod, the machine crashes, and if I whitelist that module in /etc/default/acpi-support, the machine hibernates successfully.
-- Kernel panic during second suspend to RAM or disk https://launchpad.net/bugs/62238 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
