On Mon, Nov 04, 2019 at 12:33:09PM -0800, David Rientjes wrote: > > > On Sun, 3 Nov 2019, John Hubbard wrote: > > > Introduce pin_user_pages*() variations of get_user_pages*() calls, > > and also pin_longterm_pages*() variations. > > > > These variants all set FOLL_PIN, which is also introduced, and > > thoroughly documented. > > > > The pin_longterm*() variants also set FOLL_LONGTERM, in addition > > to FOLL_PIN: > > > > pin_user_pages() > > pin_user_pages_remote() > > pin_user_pages_fast() > > > > pin_longterm_pages() > > pin_longterm_pages_remote() > > pin_longterm_pages_fast() > > > > All pages that are pinned via the above calls, must be unpinned via > > put_user_page(). > > > > Hi John, > > I'm curious what consideration is given to what pageblock migrate types > that FOLL_PIN and FOLL_LONGTERM pages originate from, assuming that > longterm would want to originate from MIGRATE_UNMOVABLE pageblocks for the > purposes of anti-fragmentation? We do not control page block, GUP can happens on _any_ page that is map inside a process (anonymous private vma or regular file back one). Cheers, Jérôme
