linux-kernel - Re: [PATCH v3 29/30] luo: allow preserving memfd

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Message-ID: <aLiXNLiWNFuvh4_G@kernel.org>
Date: Wed, 3 Sep 2025 22:29:56 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: Jason Gunthorpe <jgg@...dia.com>, Pratyush Yadav <pratyush@...nel.org>,
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Subject: Re: [PATCH v3 29/30] luo: allow preserving memfd

On Wed, Sep 03, 2025 at 03:59:40PM +0000, Pasha Tatashin wrote:
> > 
> > And again in real systems we expect memfd to be fully populated too.
> 
> I thought so too, but we already have a use case for slightly sparse
> memfd, unfortunately, that becomes *very* inefficient when fully
> populated.

Wait, regardless of how sparse memfd is, once you memfd_pin_folios() the
number of folios to preserve is known and the metadata to preserve is a
fully populated array.

-- 
Sincerely yours,
Mike.