Re: [RFC PATCH 0/6] Add support for shared PTEs across processes

[David Hildenbrand]

On 26.01.22 14:38, Matthew Wilcox wrote:
> On Wed, Jan 26, 2022 at 11:16:42AM +0100, David Hildenbrand wrote:
>> A while ago I talked with Peter about an extended uffd (here: WP)
>> mechanism that would work on fds instead of the process address space.
> 
> As far as I can tell, uffd is a grotesque hack that exists to work around
> the poor choice to use anonymous memory instead of file-backed memory
> in kvm.  Every time I see somebody mention it, I feel pain.
> 

I might be missing something important, because KVM can deal with
file-back memory just fine and uffd is used heavily outside of hypervisors.

I'd love to learn how to handle what ordinary uffd (handle
missing/unpopulated pages) and uffd-wp (handle write access to pages)
can do with files instead. Because if something like that already
exists, it would be precisely what I am talking about.

Maybe mentioning uffd was a bad choice ;)

-- 
Thanks,

David / dhildenb