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From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Subject: Re: [PATCH v10 3/3] mm: add anonymous vma name refcounting
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Date:   Tue, 12 Oct 2021 09:43:56 +0200
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> I'm still evaluating the proposal to use memfds but I'm not sure if
> the issue that David Hildenbrand mentioned about additional memory
> consumed in pagecache (which has to be addressed) is the only one we
> will encounter with this approach. If anyone knows of any potential
> issues with using memfds as named anonymous memory, I would really
> appreciate your feedback before I go too far in that direction.

[MAP_PRIVATE memfd only behave that way with 4k, not with huge pages, so 
I think it just has to be fixed. It doesn't make any sense to allocate a 
page for the pagecache ("populate the file") when accessing via a 
private mapping that's supposed to leave the file untouched]

My gut feeling is if you really need a string as identifier, then try 
going with memfds. Yes, we might hit some road blocks to be sorted out, 
but it just logically makes sense to me: Files have names. These names 
exist before mapping and after mapping. They "name" the content.

Maybe it's just me, but the whole interface, setting the name via a 
prctl after the mapping was already instantiated doesn't really spark 
joy at my end. That's not a strong pushback, but if we can avoid it 
using something that's already there, that would be very much preferred.

-- 
Thanks,

David / dhildenb