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Date: Fri, 31 Mar 2017 17:06:18 +0200
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>,
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        "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
Message-ID: <20170331150618.GC3452@pathway.suse.cz>
References: <20170329092511.3958-1-sergey.senozhatsky@gmail.com>
 <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>

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