Re: [PATCH v5] mm: memory: fix truncation removing mapped folios

[Baolin Wang]

On 10/27/26 8:53 PM, David Hildenbrand (Arm) wrote:
> On 10/27/26 13:50, Baolin Wang wrote:
> > On 10/27/26 6:55 PM, David Hildenbrand (Arm) wrote:
> > > On 10/27/26 11:35, Baolin Wang wrote:
> > > > Sure.
> > > >
> > > >
> > > > IMHO, I'm not a big fan of adding two pmd_none() checks just to avoid an
> > > > uncommon concurrent sync.
> > >
> > > It's what we already had. We had to: one for handling pmd_none() directly and
> > > one for handling zapping while splitting (file THPs).
> > >
> > > We just managed to let the second also handle the final piece of the former.
> > >
> > > Anyhow, let's get this fixed.
> > >
> > > If you think the code is clearer your way (where I disagree)
> >
> > Fair enough. Though I have a different taste, I'd still like to make the
> > maintainer happy.
>
> Don't worry, it's hard to make me unhappy :)
>
> (just a bit overloaded right now)
>
> > I'll send out v6 tomorrow following your suggestion.
>
> That looks good. 

Thanks.

> Are you planning on following up with the memory barrier
> optimization for smaller folios?

If I can find some time, though I have quite a few pending TODOs now :). 
I don't think this is urgent, so if no one else picks it up, I'll add it 
to my TODO list.

> I hope below doesn't end up in some performance degradation.

This is not a common case, so I think it's fine.