Re: [PATCH] mm: migrate: record the mlocked page status to remove unnecessary lru drain

[Yosry Ahmed]

On Thu, Oct 19, 2023 at 8:52 PM Yin, Fengwei <fengwei.yin@xxxxxxxxx> wrote:
>
>
>
> On 10/20/2023 11:45 AM, Yosry Ahmed wrote:
> >>>>
> >>>> IMHO, that seems too hacky to me. I still prefer to rely on the migration process of the mlcock pages.
> >>>
> >>> BTW, Yosry tried to address the overlap of field lru and mlock_count:
> >>> https://lore.kernel.org/lkml/20230618065719.1363271-1-yosryahmed@xxxxxxxxxx/
> >>> But the lore doesn't group all the patches.
> >>
> >> Thanks for the information. I'd like to review and test if this work can
> >> continue.
> >
> > The motivation for this work was reviving the unevictable LRU for the
> > memcg recharging RFC series [1]. However, that series was heavily
> > criticized. I was not intending on following up on it.
> >
> > If reworking the mlock_count is beneficial for other reasons, I am
> > happy to respin it if the work needed to make it mergeable is minimal.
> > Otherwise, I don't think I have the time to revisit (but feel free to
> > pick up the patches if you'd like).
> >
> > [1]https://lore.kernel.org/lkml/20230720070825.992023-1-yosryahmed@xxxxxxxxxx/
>
> I believe reworking the mlock_count is focus here. If there is no overlap
> between lru and mlock_count, the whole logic of lru_add_drain() can be
> removed here.

All patches except patch 4 are for reworking the mlock_count. Once the
mlock count is reworked, reviving the unevictable LRU is actually very
simple and removes more code than it adds (see patch 4 below).

>
> And I noticed the link:
> https://lore.kernel.org/lkml/20230618065719.1363271-1-yosryahmed@xxxxxxxxxx/
> only has cover letter and the patches didn't grouped.

That's weird, here are the patches (in order):
https://lore.kernel.org/lkml/20230618065744.1363948-1-yosryahmed@xxxxxxxxxx/
https://lore.kernel.org/lkml/20230618065756.1364399-1-yosryahmed@xxxxxxxxxx/
https://lore.kernel.org/lkml/20230618065809.1364900-1-yosryahmed@xxxxxxxxxx/
https://lore.kernel.org/lkml/20230618065816.1365301-1-yosryahmed@xxxxxxxxxx/
https://lore.kernel.org/lkml/20230618065824.1365750-1-yosryahmed@xxxxxxxxxx/

>
>
> Regards
> Yin, Fengwei
>