Re: [Bug Report] Elevated PMD nr_anon after running selftests

[Nico Pache]

On Thu, Jun 11, 2026 at 10:24 AM David Hildenbrand (Arm)
<david@xxxxxxxxxx> wrote:
>
> On 6/11/26 18:09, David Hildenbrand (Arm) wrote:
> > On 6/11/26 17:58, Nico Pache wrote:
> >> Hi,
> >>
> >> While testing my mTHP code I noticed that mm selftests caused an accounting error in
> >> /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/stats/nr_anon
> >>
> >> At first I thought I might have caused a regression, but when retesting with 7.1-rc5 (without my code), the issue was still present.
> >>
> >> This issue occurs in two mm selftests:
> >> 1) hmm test
> >> 2) migration - private_anon_htlb test
> >>
> >> I spoke to David about this and he suggested the following diff which seems to have solved both issues.
> >>
> >> David would you like to send a formal patch or patches?
> >>
> >> Cheers,
> >> -- Nico
> >>
> >> Diff for (1)
> >>
> >> diff --git a/mm/memremap.c b/mm/memremap.c
> >> index 053842d45cb1..683a77dd679d 100644
> >> --- a/mm/memremap.c
> >> +++ b/mm/memremap.c
> >> @@ -425,6 +425,7 @@ void free_zone_device_folio(struct folio *folio)
> >>         mem_cgroup_uncharge(folio);
> >>
> >>         if (folio_test_anon(folio)) {
> >> +               mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, -1);
> >>                 for (i = 0; i < nr; i++)
> >>                         __ClearPageAnonExclusive(folio_page(folio, i));
> >>         }
> >
> > Wasn't there another issue with hugetlb?
>
> Just realized that you sent this, but somehow my mail client got confused and
> hid it.

Yeah, sorry. Thanks for the message about the email client setting I'm
probably missing. Thunderbird may actually work for me now :)

Cheers,
-- Nico

>
> --
> Cheers,
>
> David
>