From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk Date: Wed, 14 Aug 2019 09:38:54 +0200 Message-ID: <20190814073854.GA27249@lst.de> References: <20190806160554.14046-1-hch@lst.de> <20190806160554.14046-5-hch@lst.de> <20190807174548.GJ1571@mellanox.com> <20190808065933.GA29382@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Dan Williams Cc: Christoph Hellwig , Jason Gunthorpe , =?iso-8859-1?B?Suly9G1l?= Glisse , Ben Skeggs , Felix Kuehling , Ralph Campbell , "linux-mm@kvack.org" , "nouveau@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" , "amd-gfx@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" List-Id: dri-devel@lists.freedesktop.org On Tue, Aug 13, 2019 at 06:36:33PM -0700, Dan Williams wrote: > Section alignment constraints somewhat save us here. The only example > I can think of a PMD not containing a uniform pgmap association for > each pte is the case when the pgmap overlaps normal dram, i.e. shares > the same 'struct memory_section' for a given span. Otherwise, distinct > pgmaps arrange to manage their own exclusive sections (and now > subsections as of v5.3). Otherwise the implementation could not > guarantee different mapping lifetimes. > > That said, this seems to want a better mechanism to determine "pfn is > ZONE_DEVICE". So I guess this patch is fine for now, and once you provide a better mechanism we can switch over to it?