From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: Serial console is causing system lock-up
Date: Thu, 7 Mar 2019 10:56:52 +0900
Message-ID: <20190307015652.GA4893@jagdpanzerIV>
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To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Petr Mladek <pmladek@suse.com>, Nigel Croxon <ncroxon@redhat.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Steven Rostedt <rostedt@goodmis.org>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, dm-devel@redhat.com, linux-serial@vger.kernel.org
List-Id: linux-serial@vger.kernel.org

On (03/06/19 11:07), Mikulas Patocka wrote:
> This bug only happens if we select large logbuffer (millions of 
> characters). With smaller log buffer, there are messages "** X printk 
> messages dropped", but there's no lockup.
> 
> The kernel apparently puts 2 million characters into a console log buffer, 
> then takes some lock and than tries to write all of them to a slow serial 
> line.

Do you run a preemtible kernel?

	-ss