Re: [PATCH v2] mm/ksm: keep soft-dirty and uffd-wp when merging a page

[Lance Yang]

Hi Samarth,

Could you send a v3 with just the soft-dirty fix, as David
suggested? Leave the uffd-wp/RWP bits to me (I'll take
a closer look).

On 2026/10/21 17:49, Lance Yang wrote:
> On 2026/10/21 16:55, Kiryl Shutsemau wrote:
> > On Wed, Oct 21, 2026 at 10:21:53AM +0200, David Hildenbrand (Arm) wrote:
> > > > +1. Did it ever actually work there :) Why not just skip them and
> > > > call it a day :D
> > >
> > > I think QEMU just always sets MADV_MERGABLE and later activates uffd. 
> > > So that
> > > needs some care to not disable them. So let's rather try to get it 
> > > fixed properly.
> > >
> > > Can you send out proper patches? Thanks!
>
> Thanks David! Will take it over next week and get proper patches out :)
>
> > +1.
> >
> > Lance's direction is right. Unsharing is not an access: do_wp_page()
> > already skips the uffd-wp fault on FAULT_FLAG_UNSHARE, and RWP should do
> > the same.
>
> Thanks Kiryl! Will take a close look at that :)
>
> Cheers, Lance