linux-ext4 - Re: Oops while going into hibernate

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Date:	Thu, 13 Jan 2011 12:48:40 +0100 (CET)
From:	Sebastian Ott <sebott@...ux.vnet.ibm.com>
To:	Theodore Tso <tytso@....edu>
cc:	"linux-ext4@...r.kernel.org development" <linux-ext4@...r.kernel.org>,
	LKML Kernel <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: Oops while going into hibernate


On Wed, 12 Jan 2011, Theodore Tso wrote:
> That looks really bogus.  /usr/bin/killall is a system binary, and there's
> no good reason that hibernation should be trying to write pages to that
> binary.
> 
> You said originally that the oops was happening "while going into
> hibernation right after resuming with...".   So that means you did a
> successful suspend/resume, and then the second suspend caused the oops?
Yes. I basically did a
echo reboot > /sys/power/disk
for i in {1..5} ;do echo disk > /sys/power/state ;done
and it crashed very early in the second suspend.

> It looks like somehow the pages were left marked as dirty, so the
> writeback daemons attempted writing back a page to an inode which was
> never opened read/write (and in fact as a text page for
> /usr/bin/killall, was mapped read/only).
> Given that ext4 initializes jinode only when the file is opened
> read/write, the fact that it is null, and the fact that it makes no
> sense that a program would be modifying /usr/bin/killall as part of a
> suspend/resume, it looks very much like we just unmasked a software
> suspend bug....
Ah, ok. Thanks for the explanation!

Regards,
Sebastian
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