Re: [PATCH RFC 01/11] mm: introduce hw_pte_t for PTE table storage

[Muhammad Usama Anjum <usama.anjum@arm.com>]

On 31/07/2026 6:49 am, Anshuman Khandual wrote:
> On Mon, Jul 27, 2026 at 05:46:52PM +0100, Muhammad Usama Anjum wrote:
>> pte_t is used both for logical PTE values and for entries stored in a PTE
>> table, so pte_t * does not distinguish a pointer to a copied value from a
>> pointer to table storage.
> 
> Should we rather call them as "Linux PTE" and "HW PTE" instead ?
> 
> Some like "Logical PTE" does not really sound very clear on what it represents.
Yeah, I should make distinction more visible in the cover letter.

> 
>>
>> Introduce hw_pte_t as the generic name for a PTE table element. Define it
>> as an alias of pte_t by default so architectures retain their existing
>> representation and behavior until they opt in to a distinct storage type.
> 
> Makes sense.
> 
>>
>> Include asm/page.h so pte_t is defined before the generic alias.
>>
>> Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
>> ---
>>  MAINTAINERS                   |  1 +
>>  include/linux/pgtable_types.h | 11 +++++++++++
>>  2 files changed, 12 insertions(+)
>>  create mode 100644 include/linux/pgtable_types.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 15dd00c7ffec5..78aac05949829 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -16981,6 +16981,7 @@ F:	include/linux/mmu_notifier.h
>>  F:	include/linux/pagewalk.h
>>  F:	include/linux/pgalloc.h
>>  F:	include/linux/pgtable.h
>> +F:	include/linux/pgtable_types.h
> 
> s/pgtable_types.h/pgtable_hw_types.h ?
I prefer shorter file names.

> 
>>  F:	include/linux/ptdump.h
>>  F:	include/linux/vmpressure.h
>>  F:	include/linux/vmstat.h
>> diff --git a/include/linux/pgtable_types.h b/include/linux/pgtable_types.h
>> new file mode 100644
>> index 0000000000000..ed5dba42a4f8c
>> --- /dev/null
>> +++ b/include/linux/pgtable_types.h
>> @@ -0,0 +1,11 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#ifndef _LINUX_PGTABLE_TYPES_H
>> +#define _LINUX_PGTABLE_TYPES_H
>> +
>> +#include <asm/page.h>
>> +
>> +#ifndef __HAVE_ARCH_HW_PTE_T
> 
> __HAVE_ARCH_HW_PTE_T macro is a better approach here or a config ARCH_HAS_HW_PTE_T
> based selective platform subscription should be introduced instead ?
Moving to CONFIG_ARCH_HAS_PTE_T from the next version as suggested here [1].

[1] https://lore.kernel.org/all/78a0402d-5436-4aab-a704-90fab56eec50@kernel.org 

-- 
Thanks,
Usama