Subject: Re: [RFC 0/8] Define coherent device memory node
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
References: <1477283517-2504-1-git-send-email-khandual@linux.vnet.ibm.com>
Cc: mhocko@suse.com, js1304@gmail.com, vbabka@suse.cz, mgorman@suse.de,
        minchan@kernel.org, akpm@linux-foundation.org,
        aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <580E4D2D.2070408@intel.com>
Date: Mon, 24 Oct 2016 11:04:29 -0700
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On 10/23/2016 09:31 PM, Anshuman Khandual wrote:
> 	To achieve seamless integration  between system RAM and coherent
> device memory it must be able to utilize core memory kernel features like
> anon mapping, file mapping, page cache, driver managed pages, HW poisoning,
> migrations, reclaim, compaction, etc.

So, you need to support all these things, but not autonuma or hugetlbfs?
 What's the reasoning behind that?

If you *really* don't want a "cdm" page to be migrated, then why isn't
that policy set on the VMA in the first place?  That would keep "cdm"
pages from being made non-cdm.  And, why would autonuma ever make a
non-cdm page and migrate it in to cdm?  There will be no NUMA access
faults caused by the devices that are fed to autonuma.

I'm confused.