Re: Threads stuck in zap_pid_ns_processes()

From: Eric W. Biederman
Date: Thu Jun 01 2017 - 13:15:55 EST


Guenter Roeck <linux@xxxxxxxxxxxx> writes:
>
> I think you nailed it. If I drop CLONE_NEWPID from the reproducer I get
> a zombie process.
>
> I guess the only question left is if zap_pid_ns_processes() should (or could)
> somehow detect that situation and return instead of waiting forever.
> What do you think ?

Any chance you can point me at the chromium code that is performing the
ptrace?

I want to conduct a review of the kernel semantics to see if the current
semantics make it unnecessarily easy to get into hang situations. If
the semantics make it really easy to get into a hang situation I want
to see if there is anything we can do to delicately change the semantics
to avoid the hangs without breaking existing userspace.

We have a real problem in exec which has similar semantics and as long
as I am looking at one I figure I should look at the other.

Eric