linux-kernel - Re: [PATCH] kexec: Fix reboot race during device

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Message-ID: <CAEXW_YQ3YZExYb6FLg3fvWr9K+FGgNQx7xk3p-PngLG6rt8Ntw@mail.gmail.com>
Date:   Sat, 7 Oct 2023 21:30:42 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Ricardo Ribalda <ribalda@...gle.com>,
        Ross Zwisler <zwisler@...gle.com>,
        Rob Clark <robdclark@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        kexec@...ts.infradead.org
Subject: Re: [PATCH] kexec: Fix reboot race during device_shutdown()

On Mon, Oct 2, 2023 at 2:18 PM Joel Fernandes <joel@...lfernandes.org> wrote:
[..]
> > > Such freezing is already being done if kernel supports KEXEC_JUMP and
> > > kexec_image->preserve_context is true. However, doing it if either of these are
> > > not true prevents crashes/races.
> >
> > The KEXEC_JUMP case is something else entirely.  It is supposed to work
> > like suspend to RAM.  Maybe reboot should as well, but I am
> > uncomfortable making a generic device fix kexec specific.
>
> I see your point of view. I think regular reboot should also be fixed
> to avoid similar crash possibilities. I am happy to make a change for
> that similar to this patch if we want to proceed that way.
>
> Thoughts?

Just checking how we want to proceed, is the consensus that we should
prevent kernel crashes without relying on userspace stopping all
processes? Should we fix regular reboot syscall as well and not just
kexec reboot?

thanks,

 - Joel