linux-kernel - Re: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG

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Message-ID: <20081001194655.GZ25711@one.firstfloor.org>
Date:	Wed, 1 Oct 2008 21:46:55 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	Vegard Nossum <vegardno@....uio.no>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y

> Yes, but __pa() used for converting to a physical address used as a parameter
> for __pfn_valid() will panic on invalid addresses passed to it when DEBUG_VIRTUAL=y.

Ok that's a bug indeed.

> Anyway virt_addr_valid() is IMHO wrong. E.g. first modules VM address
> 0xffffffffa0000000 is after __pa() 200M which is valid pfn after the shift even
> on the flatmem model with enough memory.
> 
> Am I missing something? What's the exact purpose of the virt_addr_valid()?

I think it's supposed to be only used on direct mapping anyways (judging
from a quick look a the users)

So not handling text mapping is ok, but don't panic on it.

-Andi

-- 
ak@...ux.intel.com
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