Re: [PATCH RFC 07/17] userfaultfd: introduce vm_uffd_ops

[Mike Rapoport <rppt@kernel.org>]

On Wed, Feb 11, 2026 at 02:35:23PM -0500, Peter Xu wrote:
> On Sun, Feb 08, 2026 at 12:13:45PM +0200, Mike Rapoport wrote:
> > > 
> > > I understand you wanted to also make anon to be a driver, so this line
> > > won't apply to anon.  However IMHO anon is special enough so we can still
> > > make this in the generic path.
> > 
> > Well, the idea is to drop all vma_is*() in can_userfault(). And maybe
> > eventually in entire mm/userfaultfd.c
> > 
> > If all page cache filesystems need this, something like this should work,
> > right?
> > 
> > 	if (!uffd_supports_wp_marker() && (vma->vm_flags & VM_SHARED) &&
> > 	    (vm_flags & VM_UFFD_WP))
> > 		return false;
> 
> Sorry for a late response.
> 
> IMHO using vma_is_anonymous() for one more time should be better than
> leaking pte marker whole concept to modules. So the driver should only
> report if the driver supports UFFD_WP in general.  It shouldn't care about
> anything the core mm would already do otherwise, including this one on
> "whether system config / arch has globally enabled pte markers" and the
> relation between that config and the WP feature impl details.

I agree. Will move the check for the markers back into userfaultfd.c
 
> Thanks,
> 
> -- 
> Peter Xu
> 

-- 
Sincerely yours,
Mike.