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[23.128.96.18]) by mx.google.com with ESMTP id r11si8006996edv.237.2020.11.09.13.35.40; Mon, 09 Nov 2020 13:36:03 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=Pl5Tvt71; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729454AbgKIVeY (ORCPT + 99 others); Mon, 9 Nov 2020 16:34:24 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:15356 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727311AbgKIVeX (ORCPT ); Mon, 9 Nov 2020 16:34:23 -0500 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Mon, 09 Nov 2020 13:34:29 -0800 Received: from rcampbell-dev.nvidia.com (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 9 Nov 2020 21:34:17 +0000 Subject: Re: [PATCH v3 3/6] mm: support THP migration to device private memory To: Christoph Hellwig CC: , , , , "Jerome Glisse" , John Hubbard , "Alistair Popple" , Jason Gunthorpe , Bharata B Rao , Zi Yan , "Kirill A . Shutemov" , Yang Shi , Ben Skeggs , Shuah Khan , "Andrew Morton" References: <20201106005147.20113-1-rcampbell@nvidia.com> <20201106005147.20113-4-rcampbell@nvidia.com> <20201106080322.GE31341@lst.de> <20201109091415.GC28918@lst.de> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: <0ed2fbec-e855-9be5-4897-523b00391a5a@nvidia.com> Date: Mon, 9 Nov 2020 13:34:17 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20201109091415.GC28918@lst.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1604957669; bh=mGWceFZcFVepIg70odr/PpzpGbOYemVQsgtUyEDQ5DY=; h=Subject:To:CC:References:X-Nvconfidentiality:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=Pl5Tvt71udJU3v/0WCu3Asq2HX/8GyNfgumDPJG9uNsgU+MIpHqO+wOIFuKESw2q/ T1IEais/hXVH0hE8rKE2lCAGdDwBRi9dVnYmfyzEMdvWiU8ljU/IIx8nJzLhJrm8Im Jv4q8vv55QxoNkYyA59hGqNL1W7lRcfc1Bdn9fqco9eBhY/ppa0CMphwINQ0UtvxhQ fInFfJZirRP0B/gQzxgf5Pduu2ywcaiKuHbCzULx8PA9audLlpSfNnuhRwqtZUBuTt lKiNnMmbqI4la7ABjlO2OTxf6CZlpSP2Ead9izuGJp43VzgyLtZxafBHsW/aJGGLqs sO14lMybUWHDw== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/9/20 1:14 AM, Christoph Hellwig wrote: > On Fri, Nov 06, 2020 at 01:26:50PM -0800, Ralph Campbell wrote: >> >> On 11/6/20 12:03 AM, Christoph Hellwig wrote: >>> I hate the extra pin count magic here. IMHO we really need to finish >>> off the series to get rid of the extra references on the ZONE_DEVICE >>> pages first. >> >> First, thanks for the review comments. >> >> I don't like the extra refcount either, that is why I tried to fix that up >> before resending this series. However, you didn't like me just fixing the >> refcount only for device private pages and I don't know the dax/pmem code >> and peer-to-peer PCIe uses of ZONE_DEVICE pages well enough to say how >> long it will take me to fix all the use cases. >> So I wanted to make progress on the THP migration code in the mean time. > > I think P2P is pretty trivial, given that ZONE_DEVICE pages are used like > a normal memory allocator. DAX is the interesting case, any specific > help that you need with that? Thanks for the offer. I'm putting a list together... :-)