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

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Date:	Wed, 01 Oct 2008 21:32:12 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	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

On 10/01/2008 06:52 PM, Andi Kleen wrote:
>> But it seems that the current virt_addr_valid() doesn't take this into
>> account. Should virt_addr_valid() be modified (on both x86_32 and
>> x86_64) to take into account the same checks as __phys_addr() does
>> when DEBUG_VIRTUAL=y? Or is it enough to use pfn_valid()?
> 
> At least in Linus' tree virt_addr_valid() is just a wrapper
> around pfn_valid()

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.

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()?
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