Re: [RFC 1/1] mm/pagewalk: don't split device-backed huge pfnmaps

[David Hildenbrand (Arm)]

> The -EINVAL originates from:
> 
> vfio_dma_do_map -> vfio_pin_map_dma -> vfio_pin_pages_remote
> -> vaddr_get_pfns -> pin_user_pages_remote (mm/gup.c)
> 
> Possibly that’s also the origin of the concurrent PUD modification that requires
> the retry in the walker in this patch.

We'd have to find out why we manage to trigger a -EINVAL here. I don't
see how anything that this patch does could trigger that. So maybe a
problem in user space? (calling it on unsupported VMAs?).

-- 
Cheers,

David