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Message-ID: <48E3D03C.5010808@gmail.com>
Date: Wed, 01 Oct 2008 21:32:12 +0200
From: Jiri Slaby <jirislaby@gmail.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Vegard Nossum <vegard.nossum@gmail.com>,
       Vegard Nossum <vegardno@ifi.uio.no>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y
References: <20081001104717.GA7925@ben.ifi.uio.no> <48E359B4.7050708@gmail.com> <19f34abd0810010415s405dcd98j187e5c9c20fc2d16@mail.gmail.com> <48E35E83.9040101@gmail.com> <19f34abd0810010942ifef42efv6c45831789aa1293@mail.gmail.com> <20081001165246.GY25711@one.firstfloor.org>
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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()?