linux-kernel - Re: [PATCH v4] panic: Avoid the extra noise dmesg

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Message-ID: <20181210131729.04b8e0d3@gandalf.local.home>
Date:   Mon, 10 Dec 2018 13:17:29 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Feng Tang <feng.tang@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Kees Cook <keescook@...omium.org>,
        Borislav Petkov <bp@...e.de>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Sasha Levin <sashal@...nel.org>, stable@...nel.org
Subject: Re: [PATCH v4] panic: Avoid the extra noise dmesg

On Fri,  7 Dec 2018 17:51:19 +0800
Feng Tang <feng.tang@...el.com> wrote:

> When kernel panic happens, it will first print the panic call stack,
> then the ending msg like:
> 
> [   35.743249] ---[ end Kernel panic - not syncing: Fatal exception
> [   35.749975] ------------[ cut here ]------------
> 
> The above message are very useful for debugging.
> 
> But if system is configured to not reboot on panic, say the "panic_timeout"
> parameter equals 0, it will likely print out many noisy message like
> WARN() call stack for each and every CPU except the panic one, messages
> like below:


> Keeping the interrupt disabled will avoid the noisy message.
> 
> When code runs to this point, it means user has chosed to not reboot, or
> do any special handling by using the panic notifier method, the only reason
> to enable the interrupt may be sysrq migic key and panic_blink function
> (though may not work even with irq enabled). 
> 
> So make the irq disabled by default and add a cmdline parameter
> "panic_keep_irq_on" to turn it on when needed.
> 
> Signed-off-by: Feng Tang <feng.tang@...el.com>
>

Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

-- Steve