[RFC][PATCH] Disable CLONE_PARENT for init

[Oleg Nesterov]

On 07/01, Sukadev Bhattiprolu wrote:
>
> --- linux-mmotm.orig/kernel/fork.c	2009-06-30 23:01:06.000000000 -0700
> +++ linux-mmotm/kernel/fork.c	2009-07-01 17:29:09.000000000 -0700
> @@ -974,6 +974,16 @@ static struct task_struct *copy_process(
>  	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
>  		return ERR_PTR(-EINVAL);
>
> +	/*
> +	 * Siblings of global init remain as zombies on exit since they are
> +	 * not reaped by their parent (swapper). To solve this and to avoid
> +	 * multi-rooted process trees, prevent global and container-inits
> +	 * from creating siblings.
> +	 */
> +	if ((clone_flags & CLONE_PARENT) &&
> +				current->signal->flags & SIGNAL_UNKILLABLE)
> +		return ERR_PTR(-EINVAL);

Acked-by: Oleg Nesterov <oleg at redhat.com>