From: Pavel Machek <pavel@ucw.cz>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Petr Mladek <pmladek@suse.com>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Eric Biederman <ebiederm@xmission.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>, Len Brown <len.brown@intel.com>,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places
Date: Thu, 6 Apr 2017 19:20:52 +0200 [thread overview]
Message-ID: <20170406172051.GC10363@amd> (raw)
In-Reply-To: <20170329092511.3958-5-sergey.senozhatsky@gmail.com>
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On Wed 2017-03-29 18:25:07, Sergey Senozhatsky wrote:
> It's not always possible/safe to wake_up() printk kernel
> thread. For example, late suspend/early resume may printk()
> while timekeeping is not initialized yet, so calling into the
> scheduler may result in recursive warnings.
>
> Another thing to notice is the fact PM at some point
> freezes user space and kernel threads: freeze_processes()
> and freeze_kernel_threads(), correspondingly. Thus we need
> printk() to operate in old mode there and attempt to
> immediately flush pending kernel message to the console.
>
> This patch adds printk_emergency_begin/on sections.
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
I don't like this. It is symptom of printk getting much more fragile
now.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2017-04-06 17:21 UTC|newest]
Thread overview: 109+ 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 [this message]
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
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
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