Re: [PATCH v4] mm/migrate_device: Clear stale mapping after freeing swapcache

["Yadav, Arvind" <arvind.yadav@intel.com>]

On 30-07-2026 18:17, David Hildenbrand (Arm) wrote:
>>> While this looks good, I do wonder why do we have to supply the mapping here
>>> at all?
>>>
>>> Is there a path where we call folio_migrate_mapping() and the old folio (folio)
>>> does no longer have the right mapping attached?
>>>
>>> It would be a lot less error prone if the function would just obtain the mapping
>>> from the old folio.
>>
>> Agreed. I will make folio_migrate_mapping() obtain the mapping from the source
>> folio and update its in-tree callers. Since this changes an exported helper, I
>> will send it as a separate patch in v5.
> I think it would be good to understand why we currently pass in the folio: was
> there ever a reason to do so? Or why do we pass in something that can just
> easily be had from the source folio?
>
> But note that that should be a follow-up cleanup to the fix.


Thanks for the suggestion. Once this is merged, I will review the 
history and callers to confirm whether any path intentionally uses a 
mapping other than folio_mapping(src) and follow up with a separate 
cleanup patch if needed.

Thanks,
Arvind