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Date: Tue, 17 Feb 2026 09:16:18 +0100
From: Christian Brauner <brauner@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>, 
	Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>, 
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC 0/2] pidfd: add CLONE_AUTOREAP
Message-ID: <20260217-ruder-mietvertrag-1f48c75ea965@brauner>
References: <20260216-work-pidfs-autoreap-v1-0-e63f663008f2@kernel.org>
 <CAHk-=wj8Jp-JZRQsLaOGCWYb_qjsnHZUsdSfRpkwJOsjJozfGQ@mail.gmail.com>
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On Mon, Feb 16, 2026 at 07:25:48AM -0800, Linus Torvalds wrote:
> On Mon, 16 Feb 2026 at 05:49, Christian Brauner <brauner@kernel.org> wrote:
> >
> > CLONE_AUTOREAP requires CLONE_PIDFD because the process will never be
> > visible to wait().
> 
> This seems an unnecessary and counter-productive limitation.
> 
> The very *traditional* unix way to do auto-reaping is to fork twice,
> and have the "middle" parent just exit.
> 
> That makes the final child be re-parented to init, and it is invisible
> to wait() - all very much on purpose.
> 
> This was (perhaps still is?) very commonly used for starting up
> background daemons (together with disassociating from the tty etc).
> 
> So I don't mind th enew flag, but I think the restriction is
> unnecessary and not logical. Sometimes you simply don't *want*
> processes visible to wait - or care about a pidfd.

I'm completely fine removing that restriction and supporting autoreap
without pidfd.