[PATCH 2/5] mm: rmap: add a ZONE_DEVICE folio warning in folio_referenced()

[Baolin Wang]

On 2/24/26 10:38 AM, Rik van Riel wrote:
> On Tue, 2026-02-24 at 09:56 +0800, Baolin Wang wrote:
>>
>> diff --git a/mm/rmap.c b/mm/rmap.c
>> index bff8f222004e..be785dfc9336 100644
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -1065,6 +1065,7 @@ int folio_referenced(struct folio *folio, int
>> is_locked,
>>   		.invalid_vma = invalid_folio_referenced_vma,
>>   	};
>>   
>> +	VM_WARN_ON_FOLIO(folio_is_zone_device(folio), folio);
>>   	*vm_flags = 0;
>>   	if (!pra.mapcount)
>>   		return 0;
> 
> Should be a VM_WARN_ON_ONCE_FOLIO so we do not cause
> a softlockup if we try to print information about a
> million ZONE_DEVICE pages?

Yes, sounds reasonable. Will do in next version. Thanks for reviewing.