How to kill a <defunct> process with parent 1
The only way you could remove the zombie/defunct process, would be to kill the parent. Since the parent is init (pid 1), that would also take down your system.
This pretty much leaves you with two options.
- Manually modify the process table, eg. create a dummy process, link the defunct process as a child of the dummy, then kill them off. Quite dangerous, and you may have to manually clean up other process resources such as semaphores and file handles.
- Reboot the system.
I'd go with the second.
Check if there was a kernel panic,
# dmesg |tail
Check if the process is in "D" Unkillable sleep, where it's in kernel mode for some syscall which has not returned yet (either kernel oops, or some other reason) http://www.nabble.com/What-causes-an-unkillable-process--td20645581.html
You could try restarting init:
# telinit u
Otherwise, I wouldn't worry too much. It's not running and it's not taking any resources and it's just there so the kernel can remember it.
If a zombie has init as its parent, then init has stopped working properly. One of the roles of init is to clean up zombies. If it doesn't do it, noone else will. So the only solution is to reboot. If init is broken, then a reboot may fail, so I'd shut down important services, sync the filesystem then hit the power button instead.
Let's keep the panic down, shall we? A "defunct" or "zombie" process is not a process. It is simply an entry in the process table, with a saved exit code. Thus, a zombie holds no resources, takes no CPU cycles, and uses no memory, since it is not a process. Don't get all weird and itchy trying to "kill" zombie processes. Just like their namesakes, they can't be killed, since they're already dead. But unlike the brain-eating kind, they harm absolutely no-one, and won't bite other processes.
Don't let zombie processes eat your brain. Just ignore them.