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

On 02.05.23 15:10, Jason Gunthorpe wrote:

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

quoted

quoted

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.

Good question if the domain would fail to start. I recall that IOMMUs 
for zPCI are special on s390x. [1]

Well, zPCI is special. I cannot immediately tell when we would trigger 
long-term pinning.

[1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg875728.html

-- 
Thanks,

David / dhildenb