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Date:   Tue, 11 Jul 2023 06:27:08 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Jason Gunthorpe <jgg@ziepe.ca>
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Subject: Re: Memory providers multiplexing (Was: [PATCH net-next v4 4/5]
 page_pool: remove PP_FLAG_PAGE_FRAG flag)
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References: <eadebd58-d79a-30b6-87aa-1c77acb2ec17@redhat.com> <20230619110705.106ec599@kernel.org> <CAHS8izOySGEcXmMg3Gbb5DS-D9-B165gNpwf5a+ObJ7WigLmHg@mail.gmail.com> <5e0ac5bb-2cfa-3b58-9503-1e161f3c9bd5@kernel.org> <CAHS8izP2fPS56uXKMCnbKnPNn=xhTd0SZ1NRUgnAvyuSeSSjGA@mail.gmail.com> <ZKNA9Pkg2vMJjHds@ziepe.ca> <CAHS8izNB0qNaU8OTcwDYmeVPtCrEjTTOhwCHtVsLiyhXmPLsXQ@mail.gmail.com> <ZKxDZfVAbVHgNgIM@ziepe.ca> <CAHS8izO3h3yh=CLJgzhLwCVM4SLgf64nnmBtGrXs=vxuJQHnMQ@mail.gmail.com> <ZKyZBbKEpmkFkpWV@ziepe.ca>
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On Mon, Jul 10, 2023 at 08:49:25PM -0300, Jason Gunthorpe wrote:
> The entire point of DEVICE_PRIVATE is that the page content, and
> access to the page's physical location, is *explicitly* unavailable to
> anyone but the pgmap owner.

DEVICE_PRIVATE is in fact availably to no one at all.  It is a place
holder for memory not addressable at all.

Not going to comment on the rest of this as it seems bat shit crazy
hacks for out of tree junk.  Why is anyone even wasting time on this?