Re: BUG: mmapfile/writev spurious zero bytes (x86_64/not i386, bisected,reproducable)

From: Andi Kleen
Date: Tue Jun 17 2008 - 17:35:30 EST


Linus Torvalds wrote:
>
> On Tue, 17 Jun 2008, Andi Kleen wrote:
>> Loads are not supposed to fault in copy_to_user(). Only stores are.
>
> Andi, just shut up already.
>
> It is "copy_user". Notice the lack of "from" or "to". That code handles
> *both* copy_to_user and copy_from_user.

Yes, but it assumes only one can fault at a time.

>
>> If your patch fixes something then the main wrong thing is the caller
>> who passes a faulting source address.
>
> Andi, SHUT THE F*CK UP. Read the code. Read the patch.

I did exactly the same patch first on your first email and then I realized
it was wrong before posting ;-)

> Sorry for ever
> involving you. I don't want to hear your idiotic whining.

The patch is wrong because it'll break the other case (in this case
copy_from_user)

-Andi

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