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Date:   Tue, 15 Feb 2022 19:32:09 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     David Hildenbrand <david@redhat.com>,
        Felix Kuehling <felix.kuehling@amd.com>,
        Alex Sierra <alex.sierra@amd.com>, akpm@linux-foundation.org,
        linux-mm@kvack.org, rcampbell@nvidia.com,
        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        hch@lst.de, jglisse@redhat.com, apopple@nvidia.com,
        willy@infradead.org
Subject: Re: [PATCH v6 01/10] mm: add zone device coherent type memory
 support
Message-ID: <20220215183209.GA24409@lst.de>
References: <20220201154901.7921-1-alex.sierra@amd.com> <20220201154901.7921-2-alex.sierra@amd.com> <beb38138-2266-1ff8-cc82-8fe914bed862@redhat.com> <f2af73c1-396b-168f-7f86-eb10b3b68a26@redhat.com> <a24d82d9-daf9-fa1a-8b9d-5db7fe10655e@amd.com> <078dd84e-ebbc-5c89-0407-f5ecc2ca3ebf@redhat.com> <20220215144524.GR4160@nvidia.com>
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On Tue, Feb 15, 2022 at 10:45:24AM -0400, Jason Gunthorpe wrote:
> > Do you know if DEVICE_GENERIC pages would end up as PageAnon()? My
> > assumption was that they would be part of a special mapping.
> 
> We need to stop using the special PTEs and VMAs for things that have a
> struct page. This is a mistake DAX created that must be undone.

Yes, we'll get to it.  Maybe we can do it for the non-DAX devmap
ptes first given that DAX is more complicated.