Re: [PATCH 2/7] xen/gntdev,x86: Remove apply_to_page_range() use from module

[Peter Zijlstra]

On Mon, Apr 12, 2021 at 10:26:40AM +0200, Christoph Hellwig wrote:
> On Mon, Apr 12, 2021 at 10:00:14AM +0200, Peter Zijlstra wrote:
> > Instead of relying on apply_to_page_range() being available to
> > modules, move its use into core kernel code and export it's
> > application.
> 
> This doesn't exactly look great, but at least it contains the damage..

That was just about as far as I got...

> > NOTE: ideally we do: use_ptemod = !auto_translate_physmap &&
> > gnttab_map_avail_bits and remove this hack.
> 
> Given how much pain the !auto_translate_physmap case causes all over
> the kernel I wonder what a realistic timeline might be for dropping
> support for this case might be..

I've no experience with any of that; it looks absolutely disguisting,
all of it. I figured that's part of the Xen 'charm' :-)