From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v3 3/6] mm: support THP migration to device private memory Date: Mon, 9 Nov 2020 10:14:15 +0100 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 Return-path: Content-Disposition: inline In-Reply-To: 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 List-Id: nouveau.vger.kernel.org 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?