From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Date: Wed, 31 Mar 2021 13:18:54 +0000 Subject: Re: [PATCH v7 5/8] mm: Device exclusive memory access Message-Id: <20210331131854.GI1463678@nvidia.com> List-Id: References: <20210326000805.2518-1-apopple@nvidia.com> <20210326000805.2518-6-apopple@nvidia.com> <20210330193234.GA2356281@nvidia.com> <2521635.masqiumSp9@nvdebian> In-Reply-To: <2521635.masqiumSp9@nvdebian> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alistair Popple Cc: linux-mm@kvack.org, nouveau@lists.freedesktop.org, bskeggs@redhat.com, akpm@linux-foundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, dri-devel@lists.freedesktop.org, jhubbard@nvidia.com, rcampbell@nvidia.com, jglisse@redhat.com, hch@infradead.org, daniel@ffwll.ch, willy@infradead.org, Christoph Hellwig On Wed, Mar 31, 2021 at 11:59:28PM +1100, Alistair Popple wrote: > I guess that makes sense as the split could go either way at the > moment but I should add a check to make sure this isn't used with > pinned pages anyway. Is it possible to have a pinned page under one of these things? If I pin it before you migrate it then it remains pinned but hidden under the swap entry? So the special logic is needed and the pinned page has to be copied and written as a normal pte, not dropped as a migration entry Jason