linux-kernel - Re: NMI watchdog dump does not print on hard lockup

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Message-ID: <CA+55aFxCnmd8+9qYs1pBG+N3ULQjMOV5S6yZCjA-w_pwc6kXyA@mail.gmail.com>
Date:   Fri, 13 Oct 2017 12:12:29 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: NMI watchdog dump does not print on hard lockup

On Fri, Oct 13, 2017 at 6:18 AM, Steven Rostedt <rostedt@...dmis.org> wrote:
>
> Or add the following case: The watchdog triggers, does the print, then
> if it triggers again in a certain amount of time, and the print still
> hasn't been flushed, the flush happens then.

By the time 40 sec has passed, I suspect most people have just
rebooted the machine.

I think an NMI watchdog should just force the flush - the same way an
oops should. Deadlocks aren't really relevant if something doesn't get
printed out anyway.

               Linus