Re: [PATCH v9 14/41] mm: swap: Introduce lru_add_drain_progressive()

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 04/08/2026 22:35, Sean Christopherson wrote:
> On Tue, Aug 04, 2026, Ackerley Tng wrote:
>> "David Hildenbrand (Arm)" <david@kernel.org> writes:
>>> Andrew wants to give it some more time in -next, so I'm expecting it to
>>> land for 7.3.
>>>
>>>> 7.2 or 7.3, then I would strongly prefer to base v10 on linux-next (where
>>>> the fix will presumably land soonish), and target 7.4 for in-place
>>>> conversion. Then v10 can be applied against an early 7.3-rcN and we don't
>>>> need to juggle branches (assuming Andrew is ok taking the proposed patch
>>>> through the KVM tree).
>>>
>>> Agreed. We'd also have to get the actual preparation patch into 7.3. I can
>>> send it out and coordinate with Andrew.
>>>
>>
>> Thank you!
>>
>> When we were discussing this earlier at guest_memfd biweekly, before
>> deciding to refactor out a function like lru_cache_drain_for_folio(), we
>> did say that the likelihood of actually draining in practice is low,
>> especially on a machine with heavy load making allocations all the time.
>>
>> I think the threads with Xiaoyao have resolved, I can put v10 out
>> tomorrow. Would it be okay to go with the following from v8, and then
>> clean up later when lru_cache_drain_for_folio() is available?
> 
> No.
> 
>> I'm hoping not to push this back by a full cycle to 7.4,
>   
> Sorry, but we've missed 7.3, irrespective of the lru_cache_drain_for_folio() fix.
> Even if v10 is perfect, applying tomorrow means it will get ~3 business days in
> linux-next before I send pull requests to Paolo.  That's just not enough soak
> time for land a 40+ patch series, even if half of those patches are selftests.
> 
>> and also hold back other series dependent on this one.
> 
> Eh, I don't think there will be meaningful impact in practice.  If v10 is good
> to go, I'll get it applied on 7.3-r1, and will also get an early pull request
> over to Paolo (probably around 7.3-rc4).  I.e. folks can start posting against
> the landed series shortly after rc1, and I'll have a set-in-stone base on which
> to apply more stuff around rc4/rc5.

For the record, Arm CCA KVM support depends on this series and that
being a big series (around 40+ patches), it is an inconvenience for the
Maintainers to make an effort to review the series.  That said,  we are
happy with the way this is progressing and next cycle merge for this
series would be perfect for us.


> 
> And if v10 has issues, then *not* rushing it into 7.3 will likely be the fastest
> path forward.

Absolutely !Like any work, if it is not ready to merge, it is not.

Cheers
Suzuki