Subject: Re: [PATCH v6 3/3] mm/gup: disallow FOLL_LONGTERM GUP-fast writing to file-backed mappings

From: Jason Gunthorpe <[email-masked]>
Date: Tue, 2 May 2023 10:10:51 -0300

On Tue, May 02, 2023 at 03:04:27PM +0200, Christian Borntraeger wrote:
\> > We can reintroduce a flag to permit exceptions if this is really broken, are you
> > able to test? I don't have an s390 sat around :)
> 
> Matt (Rosato on cc) probably can. In the end, it would mean having
>   <memoryBacking>
>     <source type="file"/>
>   </memoryBacking>

This s390 code is the least of the problems, after this series VFIO
won't startup at all with this configuration.

Jason