Re: [PATCH v6 0/2] mm/vmscan: fix NR_ISOLATED accounting and throttle MGLRU eviction

[Barry Song]

On Thu, Oct 15, 2026 at 7:09 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, 14 Oct 2026 17:00:22 +0800 Hui Zhu <hui.zhu@xxxxxxxxx> wrote:
>
> > The legacy reclaim path has two mechanisms around isolated folios that
> > MGLRU lacks:
> >
> > 1. NR_ISOLATED_ANON/FILE counters are updated when folios are isolated
> >    from the inactive lists. Compaction's too_many_isolated() relies on
> >    them to decide when to back off. The MGLRU reclaim path never
> >    updates them, so compaction cannot see MGLRU's in-flight isolation.
> >
> > 2. shrink_inactive_list() throttles direct reclaim via
> >    too_many_isolated() when isolated folios pile up. MGLRU's
> >    evict_folios() isolates folios without any such check, so many
> >    concurrent reclaimers can over-isolate the same (oldest) generation,
> >    leading to unnecessary swapping, thrashing and premature memcg OOM.
> >
> > Patch 1 fixes the counter accounting in the MGLRU isolation path.
> > Patch 2 adds a per-lruvec throttle, mirroring the legacy behavior but
> > adapted to MGLRU's per-lruvec contention and its dynamic type
> > selection/fallback.
>
> Thanks.  Questions for yourself and maintainers:
>
> [1/2] is nice and simple and reviewed.  How about I queue this for
> second week of the upcoming merge window?
>

+1 for this.

> [2/2] is much more code, isn't reviewed and has a Sashiko whine[*].  So
> I'm thinking this is 7.4-rcX material.
>
>
> [*] https://sashiko.dev/#/patchset/cover.1791968227.git.zhuhui@xxxxxxxxxx

Best Regards
Barry