[PATCH 2/2] arm64/mm: Improve comment in contpte_ptep_get_lockless()

[David Hildenbrand]

On 04.03.24 19:40, Ryan Roberts wrote:
> On 04/03/2024 17:37, Catalin Marinas wrote:
>> On Mon, Mar 04, 2024 at 12:54:23PM +0000, Ryan Roberts wrote:
>>> On 01/03/2024 18:47, Catalin Marinas wrote:
>>>> On Mon, Feb 26, 2024 at 12:03:21PM +0000, Ryan Roberts wrote:
>>>>> Make clear the atmicity/consistency requirements of the API and how we
>>>>> achieve them.
>>>>>
>>>>> Link: https://lore.kernel.org/linux-mm/Zc-Tqqfksho3BHmU@arm.com/
>>>>> Signed-off-by: Ryan Roberts <ryan.roberts at arm.com>
>>>>> ---
>>>>>   arch/arm64/mm/contpte.c | 24 ++++++++++++++----------
>>>>>   1 file changed, 14 insertions(+), 10 deletions(-)
>> [...]
>>>> Throughout the callers of this function, I couldn't find one where it
>>>> matters. So I concluded that they don't need the dirty state. Normally
>>>> the dirty state is passed to the page flags, so not lost after the pte
>>>> has been cleaned.
>>>
>>> I agree we can simplify the semantics. But I think its better done in a separate
>>> series (which I previously linked).
>>>
>>> What's the bottom line here? Are you ok with this comment as a short term
>>> solution for now, or do you want something more radical (i.e. push to get the
>>> series that does these simplifications reviewed and in time for v6.9).
>>>
>>> I still believe the current ptep_get_lockless() implementation is correct. So
>>> given I have a plan to simplify in the long run, I hope we can still get this
>>> series into v6.9 as planned.
>>
>> Yes, I'm fine with this patch. Assuming Andrew picked them up:
>>
>> Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>
> 
> Thanks! Yes, he did - they are in mm-unstable.
> 
>>
>> I'd like to get the simplification in as well at some point as I think
>> our ptep_get_lockless() is unnecessarily complex for most use-cases.
> 
> Yes, I'll keep pushing it. I know DavidH is keen for it.

Maybe just sent a v1 (after the merge window?) if there is no further 
feedback. I still want to look into the details, but it's stuck deep in 
my inbox I'm afraid :)

-- 
Cheers,

David / dhildenb