linux-kernel - Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on memory pressure

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Message-Id: <200710151105.57442.borntraeger@de.ibm.com>
Date:	Mon, 15 Oct 2007 11:05:57 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	"Theodore Ts'o" <tytso@....edu>
Subject: Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on memory pressure

Am Montag, 15. Oktober 2007 schrieb Nick Piggin:
> On Monday 15 October 2007 18:28, Christian Borntraeger wrote:
> > Andrew, this is a resend of a bugfix patch. Ramdisk seems a bit
> > unmaintained, so decided to sent the patch to you :-).
> > I have CCed Ted, who did work on the code in the 90s. I found no current
> > email address of Chad Page.
> 
> This really needs to be fixed...

I obviously agree ;-)
We have seen this problem happen several times. 

> I can't make up my mind between the approaches to fixing it.
> 
> On one hand, I would actually prefer to really mark the buffers
> dirty (as in: Eric's fix for this problem[*]) than this patch,
> and this seems a bit like a bandaid...

I have never seen these patches, so I cannot comment on them.
> 
> On the other hand, the wound being covered by the bandaid is
> actually the code in the buffer layer that does this latent
> "cleaning" of the page because it sadly doesn't really keep
> track of the pagecache state. But it *still* feels like we
> should be marking the rd page's buffers dirty which should
> avoid this problem anyway.

Yes, that would solve the problem as well. As long as we fix
the problem, I am happy. On the other hand, do you see any
obvious problem with this "bandaid"?

Christian
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