linux-kernel - Re: [PATCH 01/17] signal: Make SIGKILL during coredumps an explicit special case

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Date: Wed, 19 Jun 2024 21:11:06 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/17] signal: Make SIGKILL during coredumps an explicit
 special case

On 06/19, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@...hat.com> writes:
>
> > Hi Eric,
> >
> > I'll _try_ to read this (nontrivial) changes this week. To be honest,
> > right now I don't really understand your goals after the quick glance...
> >
> > So far I have only looked at this simple 1/17 and it doesn't look right
> > to me.
>
> It might be worth applying them all on a branch and just looking at the
> end result.

Perhaps. Say, the next 2/17 patch. I'd say it is very difficult to understand
the purpose unless you read the next patches. OK, at least the change log
mentions "in preparation".

> > 	- complete_signal() won't be called, so signal->group_exit_code
> > 	  won't be updated.
> >
> > 	  coredump_finish() won't change it too so the process will exit
> > 	  with group_exit_code == signr /* coredumping signal */.
> >
> > 	  Yes, the fix is obvious and trivial...
>
> The signal handling from the coredump is arguably correct.  The process
> has already exited, and gotten an exit code.

And zap_process() sets roup_exit_code = signr. But,

> But I really don't care about the exit_code either way.  I just want to
> make ``killing'' a dead process while it core dumps independent of
> complete_signal.
>
> That ``killing'' of a dead process is a completely special case.

Sorry I fail to understand...

If the coredumping process is killed by SIGKILL, it should exit with
group_exit_code = SIGKILL, right? At least this is what we have now.

Oleg.