Re: [PATCH v3 2/2] mm/mglru: fix ineffective memory protection for non-kswapd reclaim

[Ridong Chen]

On 9/3/2026 2:30 PM, Barry Song wrote:
> On Thu, Sep 3, 2026 at 11:20 AM Ridong Chen <ridong.chen@xxxxxxxxx> wrote:
> > From: Ridong Chen <chenridong@xxxxxxxxxx>
> >
> > For MGLRU, memory.min/low is not honored during global proactive reclaim
> > (writing to the root memory.reclaim) and global direct reclaim, because
> > these paths shrink memcgs using stale or effective protection (emin/elow).
>
> Are you sure it should be “stale or effective”?
> My gut feeling is that we don't need the “or” here.

My bad. It was a typo. Will remove "or".

> [...]
> > Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Assisted-by: Claude:claude-opus-4-8
> > Signed-off-by: Ridong Chen <chenridong@xxxxxxxxxx>
> > ---
>
> With a few nits:
>
> Reviewed-by: Barry Song <baohua@xxxxxxxxxx>
>
> [...]
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index b4c9b8f3dfe9..500cc2051d13 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -5111,7 +5111,13 @@ static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)
> >          struct mem_cgroup *memcg = lruvec_memcg(lruvec);
> >          struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> >
> > -       /* lru_gen_age_node() called mem_cgroup_calculate_protection() */
> > +       /*
> > +        * For kswapd, lru_gen_age_node() has already called
> > +        * mem_cgroup_calculate_protection()
> > +        */
>
> Could be clearer:
>
> /*
>   * For kswapd, mem_cgroup_calculate_protection() has already
>   * been called during the top-down cgroup traversal.
>   */

Thank you, will update.

> > +       if (!current_is_kswapd())
> > +               mem_cgroup_calculate_protection_path(NULL, memcg);
>
> Best Regards
> Barry

--
Best regards
Ridong