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Message-ID: <19f34abd0808211241l54863821n8e978682c9d43dc7@mail.gmail.com>
Date: Thu, 21 Aug 2008 21:41:05 +0200
From: "Vegard Nossum" <vegard.nossum@gmail.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: latest -git: hibernate: possible circular locking dependency detected
Cc: "Dmitry Adamushko" <dmitry.adamushko@gmail.com>,
       "Max Krasnyanskiy" <maxk@qualcomm.com>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       "Pavel Machek" <pavel@ucw.cz>
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On Thu, Aug 21, 2008 at 9:31 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> Now, what is the source of the "SysRq : Power Off" in the dmesg you posted?

The only suggestion I can make is that SysRq can be triggered remotely
with serial console (COM1/ttyS0), because I know that the serial line
is producing junk in the other direction (i.e. reading from /dev/ttyS0
on the kernel which has been booted with console=ttyS0 reads junk,
sometimes things that look like pieces of dmesg). Other than that, I
have no idea. The SysRq thing seems to only happen after I've entered
"echo disk > /sys/power/state" too.

(Also see my email at http://lkml.org/lkml/2008/8/21/409)

>
> Also, have you tried to hibernate with the "platform" setting selected in
> "cat /sys/power/disk" and if you have, does the lockdep warning appear in this
> case?

Yes, I have tried it. In fact, I believe the lockdep warning in the
boot-log comes with such a setting (ACPI was enabled; isn't platform
the default in that case?). At least it looked to be selected when
acpi is enabled:

> # cat /sys/power/disk
> [platform] test testproc shutdown reboot


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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