From: "John B. Wyatt IV" <jwyatt@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>,
Petr Mladek <pmladek@suse.com>,
Clark Williams <williams@redhat.com>,
Juri Lelli <jlelli@redhat.com>,
Derek Barbosa <debarbos@redhat.com>,
Bruno Goncalves <bgoncalv@redhat.com>,
"John B. Wyatt IV" <sageofredondo@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>
Subject: Re: NMIs reported by console_blast.sh with 6.6.20-rt25
Date: Thu, 4 Apr 2024 20:10:47 -0400 [thread overview]
Message-ID: <Zg9BhxtWepFZyH8t@hatbackup> (raw)
In-Reply-To: <20240402103414.KkkX5RuV@linutronix.de>
On Tue, Apr 02, 2024 at 12:34:14PM +0200, Sebastian Andrzej Siewior wrote:
> > Just before the sysrq that crashes the system.
>
> so this is intentional.
Yes.
> >
> > This is part of the console_blast.sh script that John Ogness sent me.
> >
> > Please see below:
> …
>
> Okay. Then everything works as it should…
Correct.
>
> > > > NMI Backtrace for 6.6.20-rt25 no forced preemption with tuned throughput-performance profile
> > > > -----------------------------
> > >
> > > This and the following backtrace shows the same picture: The CPU is
> > > crashing due to proc/sysrq request and does CPU-backtraces via NMI and
> > > polls in early_printk, waiting for the UART to become idle (probably).
> > >
> > > I don't see an issue here so far.
> >
> > Luis Goncalves discussed it with me after reading your response. Thank
> > you for your help. The NMI was needed to flush the buffers upon the
> > system crashing itself. Does this part about NMI watchdog need to be
> > documented?
>
> Not sure about that one. There is an _a_ _lot_ to be printed from NMI
> and the NMI watchdog might trigger if nothing is triggering the
> NMI-watchdog during the print job. Also, the crash was requested.
I reran the 6.6 test and no NMI was reported with fully preemptive and
the realtime tuned profile. It was my error; my apologies for that.
I did include more of logs if you want to see here for my 6.8 testing.
https://lore.kernel.org/linux-rt-users/ZgWL2UyknaE2T70C@thinkpad2021/T/#u
Sincerely,
John Wyatt
Software Engineer, Core Kernel
Red Hat
next prev parent reply other threads:[~2024-04-05 0:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-15 19:21 NMIs reported by console_blast.sh with 6.6.20-rt25 John B. Wyatt IV
2024-03-22 12:29 ` Sebastian Andrzej Siewior
2024-03-27 23:44 ` John B. Wyatt IV
2024-04-02 10:34 ` Sebastian Andrzej Siewior
2024-04-05 0:10 ` John B. Wyatt IV [this message]
2024-04-05 6:52 ` Sebastian Andrzej Siewior
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