On Thu, Oct 22, 2020 at 09:00:44AM +0200, Daniel Vetter wrote: > On Thu, Oct 22, 2020 at 1:20 AM Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > > > On Wed, Oct 21, 2020 at 09:24:08PM +0200, Daniel Vetter wrote: > > > On Wed, Oct 21, 2020 at 6:37 PM Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > > > > > > > On Wed, Oct 21, 2020 at 05:54:54PM +0200, Daniel Vetter wrote: > > > > > > > > > The trouble is that io_remap_pfn adjust vma->pgoff, so we'd need to > > > > > split that. So ideally ->mmap would never set up any ptes. > > > > > > > > /dev/mem makes pgoff == pfn so it doesn't get changed by remap. > > > > > > > > pgoff doesn't get touched for MAP_SHARED either, so there are other > > > > users that could work like this - eg anyone mmaping IO memory is > > > > probably OK. > > > > > > I was more generally thinking for io_remap_pfn_users because of the > > > mkwrite use-case we might have in fbdev emulation in drm. > > > > You have a use case for MAP_PRIVATE and io_remap_pfn_range()?? > > Uh no :-) So it is fine, the pgoff mangling only happens for MAP_PRIVATE Jason
