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Date: Thu, 20 Dec 2001 17:56:37 -0500 (EST)
From: Alexander Viro <viro@math.psu.edu>
To: Linus Torvalds <torvalds@transmeta.com>
cc: torrey.hoffman@myrio.com, linux-kernel@vger.kernel.org,
        Marcelo Tosatti <marcelo@conectiva.com.br>
Subject: Re: ramdisk corruption problems - was: RE: pivot_root and initrd 
 kern el panic woes
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On Thu, 20 Dec 2001, Linus Torvalds wrote:

> The problem is that having buffers doesn't necessarily always mean that
> they are valid, nor that _all_ of them are valid.
> 
> Also, if the ramdisk "readpage" code is wrong, then so is the
> "prepare_write" code.  They share the same logic, which basically says
> that "if the page isn't up-to-date, then it is zero".  Which is always
> true for normal read/write accesses, but as you found out it's not true
> when parts of the page have been accessed by filesystems through the
> buffers. 

AFAICS, it's nastier than that.  What's to stop buffer_heads to be
freed under memory pressure?

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