[PATCH 4/9] pid: Generalize task_active_pid_ns

[Oleg Nesterov]

Sorry for the delay, and sorry, can't read this series carefully now.
A couple of question though.

On 12/12, Eric W. Biederman wrote:
>
> Currently task_active_pid_ns is not safe to call after a
> task becomes a zombie and exit_task_namespaces is called,
> as nsproxy becomes NULL.  By reading the pid namespace from
> the pid of the task we can trivially solve this problem

Confused. If the task becomes a zombie, we can't assume it has a valid
->pids[].pid. The parent can release us as soon as exit_notify() drops
tasklist.

?

Oleg.