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

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Message-Id: <200710160006.19735.nickpiggin@yahoo.com.au>
Date:	Tue, 16 Oct 2007 00:06:19 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Christian Borntraeger <borntraeger@...ibm.com>
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

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 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...

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.

[*] However, hmm, with Eric's patch I guess we'd still have a hole
where filesystems that write their buffers by hand think they are
"cleaning" these things and we're back to square one. That could
be fixed by marking the buffers dirty again?

Why were Eric's patches dropped, BTW? I don't remember.

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