Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage

From: Pavel Machek <pavel@ucw.cz>
To: Jan Kara <jack@suse.cz>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Ye Xiaolong <xiaolong.ye@intel.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Petr Mladek <pmladek@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>, Len Brown <len.brown@intel.com>,
	linux-kernel@vger.kernel.org, lkp@01.org
Subject: Re: [printk]  fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage
Date: Thu, 6 Apr 2017 19:33:06 +0200	[thread overview]
Message-ID: <20170406173306.GD10363@amd> (raw)
In-Reply-To: <20170403093152.GB15168@quack2.suse.cz>

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Hi!

> This patch set gives up part of the printk() reliability for bounded
> latency (at least unless we detect we are really in trouble) which is IMHO
> a good trade-off for lots of users (and others can just turn this feature
> off).

If they can ever realize they were bitten by this feature.

Can we go for different tradeoff?

In console_unlock(), if you detect too much work, print "Too many
messages to print, %d bytes delayed" and wake up kernel thread.

You still get the latency, and people bitten by this feature will at
least get fair warning.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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