linux-kernel - Re: [PATCH] printk/console: Enable console kthreads only when there is no boot console left

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Message-ID: <YrCPUTah+Tu9P2V7@alley>
Date:   Mon, 20 Jun 2022 17:16:33 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Marek Behún <kabel@...nel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        John Ogness <john.ogness@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Jan Kara <jack@...e.cz>, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] printk/console: Enable console kthreads only when there
 is no boot console left

On Mon 2022-06-20 17:14:30, Petr Mladek wrote:
> The console kthreads uncovered several races in console drivers.
> All problems were in situation when a console was being properly
> initialized and registered while an early console, using the same
> port, was being used.
> 
> These problems are pretty hard to debug because they often result
> into silent boot crashes. It would be nice to fix them but it
> looks like a can of worms.
> 
> Prevent these problems by delaying the use of console kthreads
> after all early consoles are gone. It might later be optimized.
> But let's close this can of worms with a big hammer for now
> so that they do not break first impression on the kthreads
> that solve other real problems.

Marek, could you please try if this patch solves the problem
for you?

Best Regards,
Petr