Re: [PATCH 08/16] mm: add remap_pfn_range_prepare(), remap_pfn_range_complete()

Lorenzo Stoakes
2025-09-08T16:08:12Z

On Mon, Sep 08, 2025 at 01:03:06PM -0300, Jason Gunthorpe wrote:
> On Mon, Sep 08, 2025 at 03:18:46PM +0100, Lorenzo Stoakes wrote:
> > On Mon, Sep 08, 2025 at 10:35:38AM -0300, Jason Gunthorpe wrote:
> > > On Mon, Sep 08, 2025 at 02:27:12PM +0100, Lorenzo Stoakes wrote:
> > >
> > > > It's not only remap that is a concern here, people do all kinds of weird
> > > > and wonderful things in .mmap(), sometimes in combination with remap.
> > >
> > > So it should really not be split this way, complete is a badly name
> >
> > I don't understand, you think we can avoid splitting this in two? If so, I
> > disagree.
>
> I'm saying to the greatest extent possible complete should only
> populate PTEs.
>
> We should refrain from trying to use it for other things, because it
> shouldn't need to be there.

OK that sounds sensible, I will refactor to try to do only this in the
mmap_complete hook as far as is possible and see if I can use a generic function
also.

>
> > > The only example in this series didn't actually need to hold the lock.
> >
> > There's ~250 more mmap callbacks to work through. Do you provide a guarantee
> > that:
>
> I'd be happy if only a small few need something weird and everything
> else was aligned.

Ack!

>
> Jason

Cheers, Lorenzo