linux-kernel - Re: Memory corruption during hibernation since 2.6.31

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Message-ID: <20100809072646.GD1463@ucw.cz>
Date:	Mon, 9 Aug 2010 09:26:46 +0200
From:	Pavel Machek <pavel@....cz>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Hugh Dickins <hughd@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Ondrej Zary <linux@...nbow-software.org>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Balbir Singh <balbir@...ibm.com>
Subject: Re: Memory corruption during hibernation since 2.6.31

Hi!

> > I've CC'ed Andrea because we were having an offline conversation about
> > whether ksmd (and his khugepaged) need to set_freezable(); and I wonder
> > if this swap bug underlies his interest, though he was mainly worrying
> > about I/O in progress.
> 
> My opinion is that with current freezer model it is needed for suspend
> to disk. The kthread_should_stop seems useless for kswapd/ksmd, but
> I'm afraid it might get useful in the future so just to stay on the
> safe side I added it to khugepaged as well, but it's contributing to
> the pollution.
> 
> I've no idea why the freezing isn't preemptive (through the scheduler,
> all these kernel threads are obviously lowlatency beasts) by default

Hibernation woulld like all  tasks frozen with no locks held - so that
write to disk does not have to care about locking.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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