linux-kernel - Re: [PATCH] panic, kexec: Don't mutex_trylock() in __crash

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Date:   Fri, 17 Jun 2022 18:53:32 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Valentin Schneider <vschneid@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        linux-rt-users@...r.kernel.org,
        Eric Biederman <ebiederm@...ssion.com>,
        Arnd Bergmann <arnd@...db.de>, Petr Mladek <pmladek@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Juri Lelli <jlelli@...hat.com>,
        "Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Subject: Re: [PATCH] panic, kexec: Don't mutex_trylock() in __crash_kexec()

On 2022-06-17 17:09:24 [+0100], Valentin Schneider wrote:
> Those were pretty much my thoughts. I *think* panic() can be re-entrant on
> the same CPU if the first entry was from NMI, but that still requires being
> able to schedule a thread that panics which isn't a given after getting
> that panic NMI. So for now actually doing the kexec in NMI (or IRQ) context
> seems to be the less hazardous route. 

most likely. Just get rid of the mutex and we should be good to go ;)

Sebastian