Re: [RFC PATCH v2 34/47] hugetlb: userfaultfd: add support for high-granularity UFFDIO_CONTINUE

[Peter Xu]

James,

On Fri, Oct 21, 2022 at 04:36:50PM +0000, James Houghton wrote:
> +	bool use_hgm = uffd_ctx_has_hgm(&dst_vma->vm_userfaultfd_ctx) &&
> +		mode == MCOPY_ATOMIC_CONTINUE;

Do you think in your new version use_hgm can work even for MISSING by
default?

I had a feeling that the major components are ready for that anyway.  Then
no matter how HGM is enabled (assuming it'll switch to MADV, or even one
can just register with MISSING+MINOR and enable the uffd HGM feature), an
existing MISSING only app can easily switch to HGM support if it's on huge
pages.

Thanks,

-- 
Peter Xu