Re: [PATCH RFC 05/11] mm: convert PTE table entries in ptep_get()

[Muhammad Usama Anjum <usama.anjum@xxxxxxx>]

On 30/07/2026 11:24 am, Alexander Gordeev wrote:
> On Thu, Jul 30, 2026 at 11:11:35AM +0100, Muhammad Usama Anjum wrote:
>> On 30/07/2026 11:08 am, Alexander Gordeev wrote:
>>> On Mon, Jul 27, 2026 at 05:46:56PM +0100, Muhammad Usama Anjum wrote:
>>>> ptep_get() now accepts a pointer to hw_pte_t storage but must continue to
>>>> return a logical pte_t value. Add __pte_from_hw() as the conversion hook
>>>> and apply it in the generic ptep_get() implementation.
>>>>
>>>> Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxx>
>>>> ---
>>>>  include/linux/pgtable.h       | 2 +-
>>>>  include/linux/pgtable_types.h | 1 +
>>>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
>>>> index dad80d264aac2..3003ac9cd81fe 100644
>>>> --- a/include/linux/pgtable.h
>>>> +++ b/include/linux/pgtable.h
>>>> @@ -493,7 +493,7 @@ static inline int pudp_set_access_flags(struct 
>>>> vm_area_struct *vma,
>>>>  #ifndef ptep_get
>>>>  static inline pte_t ptep_get(hw_pte_t *ptep)
>>>>  {
>>>> -  return READ_ONCE(*ptep);
>>>> +  return READ_ONCE(__pte_from_hw(*ptep));
>>>
>>> Should it be something like?
>>>
>>>     return __pte_from_hw(READ_ONCE(*ptep));
>> I'd thought about it. My thinking is that we should get the pte_t first 
>> before
>> before calling READ_ONCE(). Please correct me what makes more sense?
> 
> I have a problem with "get the pte_t first" part ;) I think what we want
> is atomically read the hw_pte_t from the HW table and then convert the
> result to pte_t.
Got it. I'll fix it in the next version.

> 
>>>
>>>>  }
>>>>  #endif
>>>>  
>>>> diff --git a/include/linux/pgtable_types.h b/include/linux/pgtable_types.h
>>>> index ed5dba42a4f8c..61afe27307ec2 100644
>>>> --- a/include/linux/pgtable_types.h
>>>> +++ b/include/linux/pgtable_types.h
>>>> @@ -6,6 +6,7 @@
>>>>  
>>>>  #ifndef __HAVE_ARCH_HW_PTE_T
>>>>  #define hw_pte_t pte_t
>>>> +#define __pte_from_hw(pte)        (pte)
>>>>  #endif
>>>>  
>>>>  #endif /* _LINUX_PGTABLE_TYPES_H */
>>>> -- 
>>>> 2.47.3
>>>>
>>
>> -- 
>> Thanks,
>> Usama
>>

-- 
Thanks,
Usama