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

["David Hildenbrand (Arm)" <david@kernel.org>]

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.

-- 
Cheers,

David