linux-kernel - Re: [PATCH 02/10] exit: Add and use make_task

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Message-ID: <YdUmN7n4W5YETUhW@zeniv-ca.linux.org.uk>
Date:   Wed, 5 Jan 2022 05:01:43 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexey Gladkov <legion@...nel.org>,
        Kyle Huey <me@...ehuey.com>, Oleg Nesterov <oleg@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [PATCH 02/10] exit: Add and use make_task_dead.

On Wed, Dec 08, 2021 at 02:25:24PM -0600, Eric W. Biederman wrote:
> There are two big uses of do_exit.  The first is it's design use to be
> the guts of the exit(2) system call.  The second use is to terminate
> a task after something catastrophic has happened like a NULL pointer
> in kernel code.
> 
> Add a function make_task_dead that is initialy exactly the same as
> do_exit to cover the cases where do_exit is called to handle
> catastrophic failure.  In time this can probably be reduced to just a
> light wrapper around do_task_dead. For now keep it exactly the same so
> that there will be no behavioral differences introducing this new
> concept.
> 
> Replace all of the uses of do_exit that use it for catastraphic
> task cleanup with make_task_dead to make it clear what the code
> is doing.
> 
> As part of this rename rewind_stack_do_exit
> rewind_stack_and_make_dead.

Umm...   What about .Linvalid_mask: in arch/xtensa/kernel/entry.S?
That's an obvious case for your make_task_dead().