"Sierra Guiza, Alejandro (Alex)" <[email protected]> writes:

> @[email protected] Could you please check this patch? It's somehow related to
> migrate_device_page() for long term device coherent pages.

Sure thing. This whole series is in my queue of things to review once I make it 
home from LSF/MM.

- Alistair

> Regards,
> Alex Sierra
>> -----Original Message-----
>> From: amd-gfx <[email protected]> On Behalf Of Alex
>> Sierra
>> Sent: Thursday, May 5, 2022 4:34 PM
>> To: [email protected]
>> Cc: [email protected]; [email protected]; [email protected];
>> Kuehling, Felix <[email protected]>; [email protected]; amd-
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]; akpm@linux-
>> foundation.org; [email protected]; [email protected]
>> Subject: [PATCH v1 04/15] mm: add device coherent checker to remove
>> migration pte
>>
>> During remove_migration_pte(), entries for device coherent type pages that
>> were not created through special migration ptes, ignore _PAGE_RW flag. This
>> path can be found at migrate_device_page(), where valid vma is not
>> required. In this case, migrate_vma_collect_pmd() is not called and special
>> migration ptes are not set.
>>
>> Signed-off-by: Alex Sierra <[email protected]>
>> ---
>>  mm/migrate.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c index
>> 6c31ee1e1c9b..e18ddee56f37 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -206,7 +206,8 @@ static bool remove_migration_pte(struct folio *folio,
>>               * Recheck VMA as permissions can change since migration
>> started
>>               */
>>              entry = pte_to_swp_entry(*pvmw.pte);
>> -            if (is_writable_migration_entry(entry))
>> +            if (is_writable_migration_entry(entry) ||
>> +                is_device_coherent_page(pfn_to_page(pvmw.pfn)))
>>                      pte = maybe_mkwrite(pte, vma);
>>              else if (pte_swp_uffd_wp(*pvmw.pte))
>>                      pte = pte_mkuffd_wp(pte);
>> --
>> 2.32.0

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