Re: [PATCH 3/3] rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()
From: Oleg Nesterov
Date: Tue Dec 06 2022 - 11:50:57 EST
On 11/30, Eric W. Biederman wrote:
>
> 2) I keep thinking zap_pid_ns_processes() should be changed so that
> after it sends SIGKILL to all of the relevant processes to not wait,
At least I think it should not wait for the tasks injected into this ns.
Because this looks like a kernel bug even if we forget about this deadlock.
Say we create a task P using clone(CLONE_NEWPID), then inject a task T into
P's pid-namespace via setns/fork. This make the process P "unkillable", it
will hang in zap_pid_ns_processes() "forever" until T->parent reaps a zombie
task T killed by P.
Oleg.