On Wed, Dec 22, 2021 at 8:08 AM Jan Kara <jack@xxxxxxx> wrote: > > Well, but O_DIRECT reads must use FOLL_PIN in any case because they modify > page data (and so we need to detect them both for COW and filesystem needs). Well, O_DIRECT reads do, but not necessarily writes. And hey, even reads have been dodgy in the past when we didn't really have the pinning logic - there's been a lot of users that just wanted it to work for their particular use-case rather than in general and in all situations.. Linus