linux-kernel - Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression

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Date:   Wed, 24 May 2023 16:10:23 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Mike Christie <michael.christie@...cle.com>, linux@...mhuis.info,
        nicolas.dichtel@...nd.com, axboe@...nel.dk,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, mst@...hat.com,
        sgarzare@...hat.com, jasowang@...hat.com, stefanha@...hat.com,
        brauner@...nel.org
Subject: Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps
 regression

On 05/23, Eric W. Biederman wrote:
>
> I want to point out that we need to consider not just SIGKILL, but
> SIGABRT that causes a coredump, as well as the process peforming
> an ordinary exit(2).  All of which will cause get_signal to return
> SIGKILL in this context.

Yes, but probably SIGABRT/exit doesn't really differ from SIGKILL wrt
vhost_worker().

> It is probably not the worst thing in the world, but what this means
> is now if you pass a copy of the vhost file descriptor to another
> process the vhost_worker will persist, and thus the process will persist
> until that copy of the file descriptor is closed.

Hadn't thought about it.

I am fighting with internal bugzillas today, will try to write another
email tomorrow.

But before that, I would like to have an answer to my "main" question in
my previois email. Otherwise I am still not sure I understand what exactly
we need to fix.

Oleg.