Re: [PATCH 0/2] mm: vmscan: fix scan overshoot and ineligible folio scanning

[Andrew Morton]

On Tue, 11 Aug 2026 15:08:47 +0800 Wupeng Ma <mawupeng1@xxxxxxxxxx> wrote:

> shrink_lruvec() drives reclaim in SWAP_CLUSTER_MAX (32) chunks, but
> isolate_lru_folios() may scan far more than that per call on a single
> LRU.  The excess is never charged back, so shrink_lruvec() keeps
> rescanning the same folios round after round.  When reclaim targets a
> lower zone, the same scanner also keeps walking zone-ineligible folios
> that can never satisfy the allocation, inflating nr_reclaimed into a
> false progress that delays the OOM.
> 
> This series fixes both:
> 
>   [1/2] Charge the isolate overshoot against the scan quota so the
>         next round skips already-scanned folios.
>   [2/2] Stop scanning once too many zone-ineligible folios have been
>         skipped, instead of force-isolating them.

This all sounds fairly bad.  Is there some report?  Real-world test
results?  Laboratory test results?  Something to help us understand the
impact of the issues and the situations in which they occur.

Thanks.