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From: Petr Mladek <pmladek@suse.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, 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>, Pavel Machek <pavel@ucw.cz>,
	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: Fri, 31 Mar 2017 17:06:18 +0200	[thread overview]
Message-ID: <20170331150618.GC3452@pathway.suse.cz> (raw)
In-Reply-To: <20170329092511.3958-5-sergey.senozhatsky@gmail.com>

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>

It looks reasonable to me. Feel free to use:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Well, it still would be great if people more familiar
with this code look at it.

Best Regards,
Petr

  reply	other threads:[~2017-03-31 15:06 UTC|newest]

Thread overview: 75+ 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 [this message]
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
2017-03-31  2:35     ` Sergey Senozhatsky
2017-03-31  4:04       ` Sergey Senozhatsky
2017-03-31  6:39         ` Ye Xiaolong
2017-03-31 14:47           ` Sergey Senozhatsky
2017-03-31 15:28             ` Eric W. Biederman
2017-04-03  9:31               ` Jan Kara
2017-04-03 10:06                 ` Petr Mladek
2017-04-06 17:33                 ` Pavel Machek
2017-04-07  4:44                   ` Sergey Senozhatsky
2017-04-07  7:15                     ` Pavel Machek
2017-04-07  7:46                       ` Sergey Senozhatsky
2017-04-07  8:14                         ` Pavel Machek
2017-04-07 12:10                           ` Sergey Senozhatsky
2017-04-07 12:44                             ` Pavel Machek
2017-04-07 14:40                               ` Steven Rostedt
2017-05-08  6:37                                 ` Sergey Senozhatsky
2017-05-17 13:13                                   ` Petr Mladek
2017-04-07 15:13                               ` Sergey Senozhatsky
2017-04-07 15:23                                 ` Peter Zijlstra
2017-04-07 15:40                                   ` Sergey Senozhatsky
2017-04-09 18:21                                     ` Eric W. Biederman
2017-04-10  4:46                                       ` Sergey Senozhatsky
2017-04-09 10:12                                 ` Pavel Machek
2017-04-10  4:53                                   ` Sergey Senozhatsky
2017-04-10 11:54                                     ` Petr Mladek
2017-04-10 15:08                                       ` Sergey Senozhatsky
2017-04-10 18:48                                     ` Pavel Machek
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
2017-04-09  9:57                             ` Pavel Machek
2017-04-03 10:51               ` Sergey Senozhatsky
2017-04-05  7:29           ` Ye Xiaolong
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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