Hi, I've hit a bit of a problem with nsenter and systemd-nspawn. When nsenter is used to enter the PID namespace created with systemd-nspawn, and the container's init attempts a shutdown, it hangs because nsenter is suspended. The sequence of events leading to the hang is: 1. nsenter launches a shell inside the container with PPID=0 as seen inside the container, 2. systemd with PID=1 goes through the shutdown sequence, issuing the equivalent(*) of kill(-1, SIGSTOP) kill(-1, SIGTERM) kill(_1, SIGCONT) reboot(RB_HALT_SYSTEM) Now, nsenter has a stanza in continue_as_child where it stops itself when the child gets stopped. Unfortunately, this means that nsenter gets stopped in response to kill(-1, SIGSTOP) which hits the child. Then the child dies on kill(-1, SIGTERM), is resumed with kill(-1, SIGCONT) and exits (it prints "exit", so it's easy to see that it terminated properly. Then the shell becomes a zombie, since nsenter it it's parent and it's sleeping. Meanwhile, init executes reboot, and hangs in there, since the container waits for the PID namespace to become empty (I'm guessing here, but that seems logical). When then I type 'fg' to continue nsenter, the child gets collected and the container successfully exits. This is with kernel 3.9-rc6 from Fedora. Thanks, Zbyszek -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
