On Tue, Mar 23, 2021 at 12:47:24PM +0100, Daniel Vetter wrote: > > +static inline bool is_cow_mapping(vm_flags_t flags) > > Bit a bikeshed, but I wonder whether the public interface shouldn't be > vma_is_cow_mapping. Or whether this shouldn't be rejected somewhere else, > since at least in drivers/gpu we have tons of cases that don't check for > this and get it all kinds of wrong I think. > > remap_pfn_range handles this for many cases, but by far not for all. > > Anyway patch itself lgtm: > > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> I would like it if io_remap_pfn_range() did not allow shared mappings at all. IIRC it doesn't work anyway, the kernel can't reliably copy from IO pages eg the "_copy_from_user_inatomic()" under cow_user_page() will not work on s390 that requires all IO memory be accessed with special instructions. Unfortunately I have no idea what the long ago special case of allowing COW'd IO mappings is. :\ Jason _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
