linux-kernel - [PATCH 3/3] mm-unstable: Multi-gen LRU: Fix can_swap in lru_gen_look

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Message-ID: <20230802001938.3913174-3-kaleshsingh@google.com>
Date:   Tue,  1 Aug 2023 17:19:37 -0700
From:   Kalesh Singh <kaleshsingh@...gle.com>
To:     yuzhao@...gle.com, akpm@...ux-foundation.org
Cc:     surenb@...gle.com, android-mm@...gle.com, kernel-team@...roid.com,
        Kalesh Singh <kaleshsingh@...gle.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH 3/3] mm-unstable: Multi-gen LRU: Fix can_swap in lru_gen_look_around()

walk->can_swap might be invalid since it's not guaranteed to be
initialized for the particular lruvec. Instead deduce it from the folio
type (anon/file).

Cc: Yu Zhao <yuzhao@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---
 mm/vmscan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6eecd291756c..b4329f93a682 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4656,6 +4656,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
 	pte_t *pte = pvmw->pte;
 	unsigned long addr = pvmw->address;
 	struct folio *folio = pfn_folio(pvmw->pfn);
+	bool can_swap = !folio_is_file_lru(folio);
 	struct mem_cgroup *memcg = folio_memcg(folio);
 	struct pglist_data *pgdat = folio_pgdat(folio);
 	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
@@ -4704,7 +4705,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
 		if (!pte_young(ptent))
 			continue;
 
-		folio = get_pfn_folio(pfn, memcg, pgdat, !walk || walk->can_swap);
+		folio = get_pfn_folio(pfn, memcg, pgdat, can_swap);
 		if (!folio)
 			continue;
 
-- 
2.41.0.255.g8b1d071c50-goog