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Date:   Wed, 2 Feb 2022 15:57:50 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Alex Sierra <alex.sierra@amd.com>, Felix.Kuehling@amd.com,
        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, jgg@nvidia.com, jglisse@redhat.com, apopple@nvidia.com,
        willy@infradead.org
Subject: Re: [PATCH v4 00/10] Add MEMORY_DEVICE_COHERENT for coherent
 device memory mapping
Message-ID: <20220202145750.GA25170@lst.de>
References: <20220127030949.19396-1-alex.sierra@amd.com> <20220127143258.8da663659948ad1e6f0c0ea8@linux-foundation.org>
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On Thu, Jan 27, 2022 at 02:32:58PM -0800, Andrew Morton wrote:
> On Wed, 26 Jan 2022 21:09:39 -0600 Alex Sierra <alex.sierra@amd.com> wrote:
> 
> > This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory
> > owned by a device that can be mapped into CPU page tables like
> > MEMORY_DEVICE_GENERIC and can also be migrated like
> > MEMORY_DEVICE_PRIVATE.
> 
> Some more reviewer input appears to be desirable here.
> 
> I was going to tentatively add it to -mm and -next, but problems. 
> 5.17-rc1's mm/migrate.c:migrate_vma_check_page() is rather different
> from the tree you patched.  Please redo, refresh and resend?

I really hate adding more types with the weird one off page refcount.
We need to clean that mess up first.