linux-kernel - Re: [PATCH 11/30] um: Improve panic notifiers consistency and ordering

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Date:   Tue, 10 May 2022 16:28:21 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
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        Richard Weinberger <richard@....at>
Subject: Re: [PATCH 11/30] um: Improve panic notifiers consistency and
 ordering

On Wed 2022-04-27 19:49:05, Guilherme G. Piccoli wrote:
> Currently the panic notifiers from user mode linux don't follow
> the convention for most of the other notifiers present in the
> kernel (indentation, priority setting, numeric return).
> More important, the priorities could be improved, since it's a
> special case (userspace), hence we could run the notifiers earlier;
> user mode linux shouldn't care much with other panic notifiers but
> the ordering among the mconsole and arch notifier is important,
> given that the arch one effectively triggers a core dump.

It is not clear to me why user mode linux should not care about
the other notifiers. It might be because I do not know much
about the user mode linux.

Is the because they always create core dump or are never running
in a hypervisor or ...?

AFAIK, the notifiers do many different things. For example, there
is a notifier that disables RCU watchdog, print some extra
information. Why none of them make sense here?

> This patch fixes that by running the mconsole notifier as the first
> panic notifier, followed by the architecture one (that coredumps).
> Also, we remove a useless header inclusion.


Best Regards,
Petr