Re: [PATCH] mm/rmap: remove stale hugetlb check in try_to_unmap_one

[Kunwu Chan]

On Mon, 31 Aug 2026 17:00:56 +0100 "Lorenzo Stoakes (ARM)" <ljs@xxxxxxxxxx> wrote:

> On Mon, Aug 31, 2026 at 11:59:12PM +0800, Kunwu Chan wrote:
> > On Mon, 31 Aug 2026 08:28:47 +0000 Dev Jain <dev.jain@xxxxxxx> wrote:
> >
> > > Post commit d4ec5572825a ("mm/rmap: add try_to_unmap_poisoned_hugetlb_one")
> > > try_to_unmap_one() cannot be called with a hugetlb folio. Therefore remove
> > > the folio_test_hugetlb() check.
> >
> > Yes, the d4ec5572825 change shows that try_to_unmap() dispatches
> > hugetlb folios to try_to_unmap_poisoned_hugetlb_one(),
> > so try_to_unmap_one() cannot be called with a hugetlb folio.
> >
> >
> > It would be better to add:
> > Fixes: d4ec5572825 ("mm/rmap: add try_to_unmap_poisoned_hugetlb_one")
> 
> Nope, let's not thanks.
> 
> This isn't a bug.
> 

Got it, thanks for pointing that out. 
I mistakenly treated the stale code as a bug.

Thanks,
KunWu

> >
> > Reviewed-by: Kunwu Chan <kunwu.chan@xxxxxxxxx>
> >
> > Thanks,
> > KunWu
> >
> > >
> > > Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
> > > ---
> > > Rebase soup - my huge_ptep_get() fixes landed after the refactoring.
> > >
> > > This patch applies on Linux 7.3-rc1.
> > >
> > >  mm/rmap.c | 7 ++-----
> > >  1 file changed, 2 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/mm/rmap.c b/mm/rmap.c
> > > index d1819fd699380..606c8ecf31302 100644
> > > --- a/mm/rmap.c
> > > +++ b/mm/rmap.c
> > > @@ -2299,11 +2299,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> > >  		VM_BUG_ON_FOLIO(!pvmw.pte, folio);
> > >
> > >  		address = pvmw.address;
> > > -		if (folio_test_hugetlb(folio)) {
> > > -			pteval = huge_ptep_get(mm, address, pvmw.pte);
> > > -		} else {
> > > -			pteval = ptep_get(pvmw.pte);
> > > -		}
> > > +		pteval = ptep_get(pvmw.pte);
> > > +
> > >  		if (likely(pte_present(pteval))) {
> > >  			pfn = pte_pfn(pteval);
> > >  		} else {
> > > --
> > > 2.43.0
> > >
> > >
> >
> 
> --
> Cheers, Lorenzo
>