From: Jiri Slaby <jirislaby@gmail.com>
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
Date: Wed, 01 Oct 2008 22:01:00 +0200 [thread overview]
Message-ID: <48E3D6FC.7070709@gmail.com> (raw)
In-Reply-To: <20081001194655.GZ25711@one.firstfloor.org>
On 10/01/2008 09:46 PM, Andi Kleen wrote:
>> 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)
Then kmemcheck assumes something else. Citing:
* We need to be extremely careful not to follow any invalid pointers,
* because this function can be called for *any* possible address.
and the very first check is !virt_addr_valid(address).
> So not handling text mapping is ok, but don't panic on it.
It doesn't handle properly anything but text and direct mapping. Now it
oopses/causes BUG on that wrong cases.
I think we should set it down there that it was intended to be used only on
text/direct mapping and only for checking if there is a physical memory page
behind this kind of virtual address.
next prev parent reply other threads:[~2008-10-01 20:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-01 10:47 [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y Vegard Nossum
2008-10-01 11:06 ` Jiri Slaby
2008-10-01 11:07 ` Jiri Slaby
2008-10-01 11:15 ` Vegard Nossum
2008-10-01 11:26 ` Jiri Slaby
2008-10-01 16:42 ` Vegard Nossum
2008-10-01 16:52 ` Andi Kleen
2008-10-01 19:32 ` Jiri Slaby
2008-10-01 19:46 ` Andi Kleen
2008-10-01 20:01 ` Jiri Slaby [this message]
2008-10-02 6:18 ` Vegard Nossum
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