Re: [RFC] Null Namespaces

[Li Chen]

Hi John,

Sorry for the silence. I got pulled into some work stuff recently and
only caught up with these threads now. I still have not studied every
patch line by line, but I wanted to say that I really appreciate you
pushing on this.

The embryonic-process framing lines up well with the direction I have
been trying to move toward after the earlier feedback: make the
not-yet-runnable state explicit, and keep task creation separate from the
state installed into the new task.

For my next process-builder RFC, I plan to keep the first step small: a
pidfd-based builder for posix_spawn-style semantics, with limited action
support; it will not yet have the pristine/no-source backend. 
So cwd/root, non-CLOEXEC fds, and
other selected source state can still be inherited unless actions or
attributes say otherwise.

I think the lower-authority/null-namespace side should be an explicit
mode, not the default for the posix_spawn-compatible path. Otherwise it
would change existing expectations around cwd/root, inherited fds, and
other source state.

Longer term, I would like to add that lower-authority side as follow-up
work: pristine/no-source process creation, where resources are installed
deliberately instead of starting from the parent's fs/fd/mm state. I had
an earlier experimental local branch that tried to separate pristine task
allocation from source-state installation, but that is not the RFC I plan
to send first.

For that later mode, Christian's nullfs/failfs direction also looks like
the more practical way to express the low-authority fs state.

Thanks again for pushing this forward.

Regards,
Li​