Re: [RESEND v7 04/29] powerpc: mm: add PMD swap-exclusive helpers

[Usama Arif]

On 18/09/2026 22:22, David Hildenbrand (Arm) wrote:
> On 9/14/26 14:27, Usama Arif wrote:
>> A later patch keeps a PMD-mapped anonymous THP mapped by a PMD across the
>> swap round-trip, so PG_anon_exclusive now has to survive in a swap PMD and
>> not just in a swap PTE.
>>
>> book3s64 builds a swap PMD by running the PTE encoding over pmd_pte(), so
>> the PMD helpers use the same _PAGE_SWP_EXCLUSIVE bit. It is also the only
>> powerpc variant that selects ARCH_HAS_PMD_SOFTLEAVES, via PPC_THP.
>>
>> Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>
>> Signed-off-by: Usama Arif <usama.arif@xxxxxxxxx>
>> ---
>>  arch/powerpc/include/asm/book3s/64/pgtable.h | 17 +++++++++++++++++
>>  1 file changed, 17 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> index dff8790a047db..28943ef3c1c80 100644
>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> @@ -699,6 +699,23 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
>>  	return __pte_raw(pte_raw(pte) & cpu_to_be64(~_PAGE_SWP_EXCLUSIVE));
>>  }
>>  
>> +#ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES
>> +static inline pmd_t pmd_swp_mkexclusive(pmd_t pmd)
>> +{
>> +	return __pmd_raw(pmd_raw(pmd) | cpu_to_be64(_PAGE_SWP_EXCLUSIVE));
>> +}
>> +
>> +static inline bool pmd_swp_exclusive(pmd_t pmd)
>> +{
>> +	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_SWP_EXCLUSIVE));
>> +}
>> +
>> +static inline pmd_t pmd_swp_clear_exclusive(pmd_t pmd)
>> +{
>> +	return __pmd_raw(pmd_raw(pmd) & cpu_to_be64(~_PAGE_SWP_EXCLUSIVE));
>> +}
>> +#endif
> 
> This should likely go below the pmd_swp_mksoft_dirty() handling block?
> 
> For softdirty it's e.g.,
> 
> #define pmd_swp_mksoft_dirty(pmd)	pte_pmd(pte_swp_mksoft_dirty(pmd_pte(pmd)))
> 
> 
> Why can't we follow a similar model here?
> 

I had just copied from pte_swp_mkexclusive()/pte_swp_exclusive()/pte_swp_clear_exclusive().


I will do this in the following revision for this patch:


diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index dff8790a047db..458c85cebfa65 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1060,6 +1060,12 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
 #endif
 #endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */

+#ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES
+#define pmd_swp_mkexclusive(pmd)       pte_pmd(pte_swp_mkexclusive(pmd_pte(pmd)))
+#define pmd_swp_exclusive(pmd)         pte_swp_exclusive(pmd_pte(pmd))
+#define pmd_swp_clear_exclusive(pmd)   pte_pmd(pte_swp_clear_exclusive(pmd_pte(pmd)))
+#endif
+
 #ifdef CONFIG_ARCH_HAS_PTE_PROTNONE
 static inline int pmd_protnone(pmd_t pmd)
 {