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Date: Tue, 09 Aug 2005 20:27:32 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Hugh Dickins <hugh@veritas.com>
CC: Russell King <rmk+lkml@arm.linux.org.uk>, ncunningham@cyclades.com,
       Daniel Phillips <phillips@arcor.de>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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       Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
       Andrea Arcangeli <andrea@suse.de>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [RFC][patch 0/2] mm: remove PageReserved
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Hugh Dickins wrote:

> 
> You're right (though I imagine might sometimes be holes rather than RAM).
> 

Yep. These holes are what I have in mind, and random other things
like the !(bad_ppro && page_kills_ppro(pfn)) check.

[...]

> I think Nick is treating the "use" of PageReserved in ioremap much too
> reverentially.  Fine to leave its removal from there to a later stage,
> but why shouldn't that also be removed?
> 

Well, as far as I had been able to gather, ioremap is trying to
ensure it does indeed only hit one of these holes, and not valid
RAM. I thought the fact that it *won't* bail out when encountering
kernel text or remap_pfn_range'ed pages was only due to PG_reserved
being the proverbial jack of all trades, master of none.

I could be wrong here though.

But in either case: I agree that it is probably not a great loss
to remove the check, although considering it will be needed for
swsusp anyway...

-- 
SUSE Labs, Novell Inc.

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