linux-kernel - Re: [PATCH 1/2] Allow a kthread to declare that it calls task_work

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Message-ID: <20231204161245.GA31326@redhat.com>
Date:   Mon, 4 Dec 2023 17:12:45 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     NeilBrown <neilb@...e.de>, Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Chuck Lever <chuck.lever@...cle.com>,
        Jeff Layton <jlayton@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nfs@...r.kernel.org
Subject: Re: [PATCH 1/2] Allow a kthread to declare that it calls
 task_work_run()

I am sick and can't read emails, just one note

On 12/04, Al Viro wrote:
>
> Just have the kernel threads born with ->task_works set to &work_exited

Then irq_thread()->task_work_add() will silently fail,

> and provide a primitive that would flip it from that to NULL.

OK, so this change should update irq_thread(). But what else can fail?

And what if another kthread uses task_work_add(current) to add the
desctructor and does fput() without task_work_run() ?

Oleg.