Re: [PATCH v2 2/2] mm: multi-gen LRU: remove get_lruvec()

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

On Mon, 2 Nov 2026 at 14:56, Barry Song <baohua@kernel.org> wrote:
>
> On Tue, Oct 27, 2026 at 4:23 AM Siddharth Chintamaneni
> <sidchintamaneni@gmail.com> wrote:
> >
> > get_lruvec() was originally introduced in commit ec1c86b25f4b ("mm:
> > multi-gen LRU: groundwork") to guard against NULL NODE_DATA(nid) on
> > uninitialized NUMA nodes (`return pgdat ? &pgdat->__lruvec : NULL;`).
> > After commit 09f49dca570a ("mm: handle uninitialized numa nodes
> > gracefully") and commit 931b6a8b36a2 ("mm: multi-gen LRU: remove NULL
> > checks on NODE_DATA()"), that NULL check was removed, leaving
> > get_lruvec() as a thin wrapper around mem_cgroup_lruvec().
> >
> > Remove get_lruvec() and call mem_cgroup_lruvec() directly at all call
> > sites.
> >
> > Suggested-by: Barry Song <baohua@kernel.org>
> > Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> > Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
> > Signed-off-by: Hardik Garg <hargar@linux.microsoft.com>
> > ---
>
> It's great to see the MGLRU-specific get_lruvec() gone. Thanks!
> Hopefully, we can get rid of more MGLRU-specific code,
> such as get_swappiness().
>

I just looked into removing get_swappiness() in favor of its LRU variant
(sc_swappiness()). Do you mean moving the additional conditionals
directly into the callsites?

something like this -
<AI Suggested>

diff --git a/mm/vmscan.c b/mm/vmscan.c
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2761,25 +2761,6 @@ static struct lruvec *get_lruvec(struct
mem_cgroup *memcg, int nid)
  return &pgdat->__lruvec;
 }

-static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc)
-{
- struct mem_cgroup *memcg = lruvec_memcg(lruvec);
- struct pglist_data *pgdat = lruvec_pgdat(lruvec);
- int swappiness = sc_swappiness(sc, memcg);
-
- if (swappiness == SWAPPINESS_ANON_ONLY)
- return swappiness;
-
- if (!sc->may_swap)
- return 0;
-
- if (!can_demote(pgdat->node_id, sc, memcg) &&
-    mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH)
- return 0;
-
- return swappiness;
-}
-
 static int get_nr_gens(struct lruvec *lruvec, int type)
 {
  return lruvec->lrugen.max_seq - lruvec->lrugen.min_seq[type] + 1;
@@ -4173,8 +4154,13 @@ static unsigned long
lruvec_evictable_size(struct lruvec *lruvec, int swappiness
 static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
 {
  unsigned long total;
- int swappiness = get_swappiness(lruvec, sc);
  struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+ struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+ int swappiness = sc_swappiness(sc, memcg);
+
+ if (swappiness != SWAPPINESS_ANON_ONLY &&
+    (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)))
+ swappiness = 0;


> Reviewed-by: Barry Song <baohua@kernel.org>