Re: [PATCH 3/6] mm/migrate: split remove_migration_pte_hugetlb() out of remove_migration_pte()

[Garg, Shivank]

On 7/14/2026 6:10 PM, David Hildenbrand (Arm) wrote:
> On 7/12/26 09:38, Shivank Garg wrote:
>> remove_migration_pte() interleaves the regular folio path with the
>> hugetlb path via folio_test_hugetlb() and CONFIG_HUGETLB_PAGE
>> special cases. Simplify this by seprating the hugetlb handling into
>> remove_migration_pte_hugetlb().
>>
>> Factor out working-PTE construction from migration entry into
>> migration_softleaf_entry_to_pte(), used by both paths.
>>
>> While here, convert the VM_BUG_ON_FOLIO() to VM_WARN_ON_ONCE_FOLIO().
>>
>> No functional change intended.
>>
>> Signed-off-by: Shivank Garg <shivankg@xxxxxxx>
>> ---
>>  mm/migrate.c | 153 ++++++++++++++++++++++++++++++++++++++---------------------
>>  1 file changed, 98 insertions(+), 55 deletions(-)
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 222c8c15f782..8a098402b8c9 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -345,6 +345,89 @@ struct rmap_walk_arg {
>>  	bool map_unused_to_zeropage;
>>  };
>>  
>> +static pte_t migration_softleaf_entry_to_pte(struct folio *folio, struct page *new,
> 
> "migration_entry" should be sufficient, right? It implies "softleaf".

sure

> 
>> +		softleaf_t entry, pte_t old_pte, struct vm_area_struct *vma,
>> +		rmap_t *rmap_flags)
>> +{
>> +	pte_t pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
>> +
>> +	if (!softleaf_is_migration_young(entry))
>> +		pte = pte_mkold(pte);
>> +	if (folio_test_dirty(folio) && softleaf_is_migration_dirty(entry))
>> +		pte = pte_mkdirty(pte);
>> +	if (pte_swp_soft_dirty(old_pte))
>> +		pte = pte_mksoft_dirty(pte);
>> +	else
>> +		pte = pte_clear_soft_dirty(pte);
>> +
>> +	if (softleaf_is_migration_write(entry))
>> +		pte = pte_mkwrite(pte, vma);
>> +	else if (pte_swp_uffd(old_pte))
>> +		pte = pte_mkuffd(pte);
>> +
>> +	/* See do_swap_page(): restore PAGE_NONE for RWP */
>> +	if (pte_swp_uffd(old_pte) && userfaultfd_rwp(vma))
>> +		pte = pte_modify(pte, PAGE_NONE);
>> +
>> +	if (folio_test_anon(folio) && !softleaf_is_migration_read(entry))
>> +		*rmap_flags |= RMAP_EXCLUSIVE;
>> +
>> +	return pte;
>> +}
> 
> Can you move splitting that out into a separate patch? IIUC you can do that even
> without messing with the hugetlb stuff.
> 

yes, will move migration_entry_to_pte() into separate patch.

Thanks,
Shivank