On Thursday, 1 April 2021 12:18:54 AM AEDT Jason Gunthorpe wrote: > 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? At the moment yes. But I had planned (and this reminded me) to add a check to prevent marking pinned pages for exclusive access. This check was in the original migration based implementation as I don't think it makes much sense to allow exclusive access to pinned pages given it indicates another device is possibly using it. > 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 Yep, if we end up allowing pinned pages to exist under these then that makes sense. Thanks for the clarification. - Alistair > Jason >