On Tue, Dec 06, 2022 at 05:49:28PM +0100, Oleg Nesterov wrote: > 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. Given that this is not the first time that Tasks Trace RCU has been involved in a deadlock involving this exit path, I could certainly get behind this approach. ;-) Thanx, Paul
