linux-kernel - Re: [PATCH printk v4 27/27] lockdep: Mark emergency sections in lockdep splats

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Message-ID: <20240416111749.GM40213@noisy.programming.kicks-ass.net>
Date: Tue, 16 Apr 2024 13:17:49 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: John Ogness <john.ogness@...utronix.de>
Cc: Petr Mladek <pmladek@...e.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>
Subject: Re: [PATCH printk v4 27/27] lockdep: Mark emergency sections in
 lockdep splats

On Wed, Apr 03, 2024 at 12:17:29AM +0206, John Ogness wrote:
> Mark emergency sections wherever multiple lines of
> lock debugging output are generated. In an emergency
> section the CPU will not perform console output for the
> printk() calls. Instead, a flushing of the console
> output is triggered when exiting the emergency section.
> This allows the full message block to be stored as
> quickly as possible in the ringbuffer.

I am confused, when in emergency I want the thing to dump everything to
the atomic thing asap.

Storing it all up runs the risk of never getting to the 'complete' point
because we're dead.