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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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WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@ucw.cz>
To: lkp@lists.01.org
Subject: Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage
Date: Thu, 06 Apr 2017 19:33:06 +0200	[thread overview]
Message-ID: <20170406173306.GD10363@amd> (raw)
In-Reply-To: <20170403093152.GB15168@quack2.suse.cz>

[-- Attachment #1: Type: text/plain, Size: 730 bytes --]

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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  parent reply	other threads:[~2017-04-06 17:33 UTC|newest]

Thread overview: 111+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-29  9:25 [RFC][PATCHv2 0/8] printk: introduce printing kernel thread Sergey Senozhatsky
2017-03-29  9:25 ` [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Sergey Senozhatsky
2017-03-31 13:09   ` Petr Mladek
2017-03-31 13:33     ` Peter Zijlstra
2017-04-03 11:23       ` Sergey Senozhatsky
2017-04-03 12:43         ` Petr Mladek
2017-03-29  9:25 ` [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky
2017-04-04  9:01   ` Petr Mladek
2017-04-04  9:36     ` Sergey Senozhatsky
2017-04-06 17:14   ` Pavel Machek
2017-04-07  5:12     ` Sergey Senozhatsky
2017-04-07  7:21       ` Pavel Machek
2017-04-07  8:15         ` Sergey Senozhatsky
2017-04-07 12:06           ` Pavel Machek
2017-03-29  9:25 ` [RFC][PATCHv2 3/8] printk: offload printing from wake_up_klogd_work_func() Sergey Senozhatsky
2017-03-31 14:56   ` Petr Mladek
2017-04-04 16:15     ` Sergey Senozhatsky
2017-03-29  9:25 ` [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Sergey Senozhatsky
2017-03-31 15:06   ` Petr Mladek
2017-04-06 17:20   ` Pavel Machek
2017-04-09 10:59     ` Andreas Mohr
2017-04-10 12:20       ` Petr Mladek
2017-04-10 14:38         ` Sergey Senozhatsky
2017-03-29  9:25 ` [RFC][PATCHv2 5/8] sysrq: " Sergey Senozhatsky
2017-03-31 15:37   ` Petr Mladek
2017-04-01  0:04     ` Sergey Senozhatsky
2017-03-29  9:25 ` [RFC][PATCHv2 6/8] kexec: " Sergey Senozhatsky
2017-03-31 15:39   ` Petr Mladek
2017-03-29  9:25 ` [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Sergey Senozhatsky
2017-04-03 15:29   ` Petr Mladek
2017-04-04  8:29     ` Sergey Senozhatsky
2017-03-29  9:25 ` [RFC][PATCHv2 8/8] printk: enable printk offloading Sergey Senozhatsky
2017-03-30 21:38   ` [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage kernel test robot
2017-03-30 21:38     ` kernel test robot
2017-03-31  2:35     ` Sergey Senozhatsky
2017-03-31  2:35       ` Sergey Senozhatsky
2017-03-31  4:04       ` Sergey Senozhatsky
2017-03-31  4:04         ` Sergey Senozhatsky
2017-03-31  6:39         ` Ye Xiaolong
2017-03-31  6:39           ` Ye Xiaolong
2017-03-31 14:47           ` Sergey Senozhatsky
2017-03-31 14:47             ` Sergey Senozhatsky
2017-03-31 15:28             ` Eric W. Biederman
2017-03-31 15:28               ` Eric W. Biederman
2017-04-03  9:31               ` Jan Kara
2017-04-03  9:31                 ` Jan Kara
2017-04-03 10:06                 ` Petr Mladek
2017-04-03 10:06                   ` Petr Mladek
2017-04-06 17:33                 ` Pavel Machek [this message]
2017-04-06 17:33                   ` Pavel Machek
2017-04-07  4:44                   ` Sergey Senozhatsky
2017-04-07  4:44                     ` Sergey Senozhatsky
2017-04-07  7:15                     ` Pavel Machek
2017-04-07  7:15                       ` Pavel Machek
2017-04-07  7:46                       ` Sergey Senozhatsky
2017-04-07  7:46                         ` Sergey Senozhatsky
2017-04-07  8:14                         ` Pavel Machek
2017-04-07  8:14                           ` Pavel Machek
2017-04-07 12:10                           ` Sergey Senozhatsky
2017-04-07 12:10                             ` Sergey Senozhatsky
2017-04-07 12:44                             ` Pavel Machek
2017-04-07 12:44                               ` Pavel Machek
2017-04-07 14:40                               ` Steven Rostedt
2017-04-07 14:40                                 ` Steven Rostedt
2017-05-08  6:37                                 ` Sergey Senozhatsky
2017-05-08  6:37                                   ` Sergey Senozhatsky
2017-05-17 13:13                                   ` Petr Mladek
2017-05-17 13:13                                     ` Petr Mladek
2017-04-07 15:13                               ` Sergey Senozhatsky
2017-04-07 15:13                                 ` Sergey Senozhatsky
2017-04-07 15:23                                 ` Peter Zijlstra
2017-04-07 15:23                                   ` Peter Zijlstra
2017-04-07 15:40                                   ` Sergey Senozhatsky
2017-04-07 15:40                                     ` Sergey Senozhatsky
2017-04-09 18:21                                     ` Eric W. Biederman
2017-04-09 18:21                                       ` Eric W. Biederman
2017-04-10  4:46                                       ` Sergey Senozhatsky
2017-04-10  4:46                                         ` Sergey Senozhatsky
2017-04-09 10:12                                 ` Pavel Machek
2017-04-09 10:12                                   ` Pavel Machek
2017-04-10  4:53                                   ` Sergey Senozhatsky
2017-04-10  4:53                                     ` Sergey Senozhatsky
2017-04-10 11:54                                     ` Petr Mladek
2017-04-10 11:54                                       ` Petr Mladek
2017-04-10 15:08                                       ` Sergey Senozhatsky
2017-04-10 15:08                                         ` Sergey Senozhatsky
2017-04-10 18:48                                     ` Pavel Machek
2017-04-10 18:48                                       ` Pavel Machek
2017-04-11  1:46                                       ` Sergey Senozhatsky
2017-04-11  1:46                                         ` Sergey Senozhatsky
2017-04-11 16:19                                         ` Sergey Senozhatsky
2017-04-12 18:43                                           ` Pavel Machek
2017-04-13  4:34                                             ` Sergey Senozhatsky
2017-04-13  5:50                                           ` Sergey Senozhatsky
2017-04-13  8:19                                             ` Sergey Senozhatsky
2017-04-13 14:03                                           ` Petr Mladek
2017-04-14  4:42                                             ` Sergey Senozhatsky
2017-04-07 14:29                           ` Steven Rostedt
2017-04-07 14:29                             ` Steven Rostedt
2017-04-09  9:57                             ` Pavel Machek
2017-04-09  9:57                               ` Pavel Machek
2017-04-03 10:51               ` Sergey Senozhatsky
2017-04-03 10:51                 ` Sergey Senozhatsky
2017-04-05  7:29           ` Ye Xiaolong
2017-04-05  7:29             ` Ye Xiaolong
2017-04-05  8:40             ` Sergey Senozhatsky
2017-04-05  8:40               ` Sergey Senozhatsky
2017-04-03 15:42   ` [RFC][PATCHv2 8/8] printk: enable printk offloading Petr Mladek
2017-04-04 13:20     ` Sergey Senozhatsky
2017-04-02  4:13 [printk] fbc14616f4 BUG: kernel reboot-without-warning in test stage Fengguang Wu
2017-04-03  2:14 ` Sergey Senozhatsky

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