On Mon, Sep 18, 2017 at 2:31 AM, Jan Kara <jack@xxxxxxx> wrote: > On Sun 17-09-17 19:39:45, Christoph Hellwig wrote: >> On Sat, Sep 16, 2017 at 08:44:14PM -0700, Dan Williams wrote: >> > So it wasn't all that easy, and Linus declined to take it. I think we >> > should add a new ->mmap_validate() file operation and save the >> > tree-wide cleanup until later. >> >> Note that we already have a mmap_capabilities callout for nommu, >> I wonder if we could generalize that. > > So if I understood Dan right, Linus refused to merge the patch which adds > 'flags' argument to ->mmap callback. That is actually logically independent > change from validating flags passed to mmap(2) syscall. Dan did it just to > save himself from adding a VMA flag for MAP_DIRECT. > > For validating flags passed to mmap(2), I agree we could use > ->mmap_capabilities() instead of mmap_supported_mask Dan has added. But I > don't have a strong opinion there. The drawback I see with mmap_capabilities is that it requires all mmap flags to have a corresponding vm_flag. After the cold reaction the VM_DAX flag received I'd want to be sure they were on board with this direction.
