From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A567C55ABD for ; Mon, 9 Nov 2020 09:14:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 845F32083B for ; Mon, 9 Nov 2020 09:14:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 845F32083B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF8B06B0036; Mon, 9 Nov 2020 04:14:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EB2246B005D; Mon, 9 Nov 2020 04:14:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D6EE36B0068; Mon, 9 Nov 2020 04:14:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0079.hostedemail.com [216.40.44.79]) by kanga.kvack.org (Postfix) with ESMTP id A703B6B0036 for ; Mon, 9 Nov 2020 04:14:24 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 466C38249980 for ; Mon, 9 Nov 2020 09:14:24 +0000 (UTC) X-FDA: 77464318848.29.bike83_5a125e2272eb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id 2AC44180868C1 for ; Mon, 9 Nov 2020 09:14:24 +0000 (UTC) X-HE-Tag: bike83_5a125e2272eb X-Filterd-Recvd-Size: 2437 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Mon, 9 Nov 2020 09:14:23 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id BBE6E68B05; Mon, 9 Nov 2020 10:14:20 +0100 (CET) Date: Mon, 9 Nov 2020 10:14:15 +0100 From: Christoph Hellwig To: Ralph Campbell Cc: Christoph Hellwig , linux-mm@kvack.org, nouveau@lists.freedesktop.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Jerome Glisse , John Hubbard , Alistair Popple , Jason Gunthorpe , Bharata B Rao , Zi Yan , "Kirill A . Shutemov" , Yang Shi , Ben Skeggs , Shuah Khan , Andrew Morton Subject: Re: [PATCH v3 3/6] mm: support THP migration to device private memory Message-ID: <20201109091415.GC28918@lst.de> References: <20201106005147.20113-1-rcampbell@nvidia.com> <20201106005147.20113-4-rcampbell@nvidia.com> <20201106080322.GE31341@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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?