Re: [BUG] dma-mapping: remove CONFIG_DMA_REMAP

[Mark Hounschell]

On 6/21/22 10:19, Christoph Hellwig wrote:
> On Tue, Jun 21, 2022 at 10:06:59AM -0400, Mark Hounschell wrote:
> > On 6/21/22 09:48, Christoph Hellwig wrote:
> > > On Tue, Jun 21, 2022 at 09:43:18AM -0400, Mark Hounschell wrote:
> > > > Revert that commit and all works like normal. This commit breaks user land.
> > >
> > > No.  We had that discussion before.  It exposeѕ how broken your out of
> > > tree driver is, which you don't bother to fix despite Robin even taking
> > > the pains to explain you how.
> >
> > No, this is not the original issue and we never actually had a discussion.
> > That original issue was about using Set/ClearPageReserved. You nor Robin
> > even tried to explain why it was wrong to use it. It was never an issue in
> > previous kernels. Why now? In any case I have removed that code. This is
> > what happens now.
> >
> > What is it you think I am doing wrong. Except for using
> > Set/ClearPageReserved you have not explained anything to me.
>
> Which part of "you must not call virt_to_page on the result that is
> very clearly stated in the documentation and has been explained to
> you repeatly" is still not clear to you?

That has not been explained to me at all. I am NOT any longer using 
virt_to_page at all anywhere in the driver. I was told that 
Set/ClearPageReserve was what I was doing wrong. Not that I was using 
virt_to_page with it. I am not using either now. I am using only 
dma_alloc_coherent.

> Which part of "if your of tree modules stops working, this does not
> constitute userspace breakage" is not clear to you?
>
> I'm done with this, please stop bothering me.

I am not trying to bother you and there is no reason for you to be rude 
to me. I just think this is a bug and am trying to get to the bottom of it.

Regards
Mark