Re: [PATCH 1/4] mm/damon: defensively skip zone device folios in damon_get_folio()

[Gregory Price]

On Thu, Aug 06, 2026 at 05:09:37PM -0700, SJ Park wrote:
> On Thu, 6 Aug 2026 12:05:00 -0500 Gregory Price <gourry@xxxxxxxxxx> wrote:
> 
> > On Thu, Aug 06, 2026 at 02:37:59PM +0100, Lorenzo Stoakes (ARM) wrote:
> > > On Tue, Jul 28, 2026 at 03:47:11PM -0400, Gregory Price wrote:
> > > > All DAMON physical- and virtual-address operations obtain their folios
> > > > through damon_get_folio(). That helper already excludes ZONE_DEVICE
> > > > memory implicitly via pfn_to_online_page() and folio_test_lru(), but
> > > > this is inconsistent with other callers in mm/ which test explicitly.
> > > >
> > > > Add an explicit folio_is_zone_device() rejection in damon_get_folio()
> > > > so the guarantee lives in one place and covers every caller uniformly,
> > > > consistent with other mm walkers that reject zone device folios.
> > > >
> > > > Signed-off-by: Gregory Price (Meta) <gourry@xxxxxxxxxx>
> > > 
> > > Thanks, nice to make it explicit!
> > > 
> > > Acked-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> > >
> > 
> > SJ Asked me to drop it,
> 
> I didn't asked you to drop this.  I asked your thought about revisioning this
> for my concern.  And you replied [1] you can drop this.
>

Sorry I didn't mean to imply you pushed for one side or another, just
that the feedback you gave about not wanting dead code is reason enough
to drop it.

I will probably just go ahead and drop it unless Lorenzo thinks the
patch is worth keeping.  In my next private node iteration, it ends up
back in anyway - so we get a two for one without the intermediate patch.

~Gregory