[RFC PATCH V3 04/17] mm/kscand: Add only hot pages to migration list

[Raghavendra K T <raghavendra.kt@amd.com>]

 Previously all pages, accessed once are added.
Improve it by adding those that are accessed second time.

This logic is closer to current NUMAB implementation
of spotting hot pages.

Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
---
 mm/kscand.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/kscand.c b/mm/kscand.c
index 1d883d411664..7552ce32beea 100644
--- a/mm/kscand.c
+++ b/mm/kscand.c
@@ -196,6 +196,7 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 	struct kscand_migrate_info *info;
 	struct kscand_scanctrl *scanctrl = walk->private;
 	int srcnid;
+	bool prev_idle;
 
 	scanctrl->address = addr;
 	pte_t pteval = ptep_get(pte);
@@ -219,6 +220,7 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 		folio_put(folio);
 		return 0;
 	}
+	prev_idle = folio_test_idle(folio);
 	folio_set_idle(folio);
 	page_idle_clear_pte_refs(page, pte, walk);
 	srcnid = folio_nid(folio);
@@ -233,7 +235,7 @@ static int hot_vma_idle_pte_entry(pte_t *pte,
 		folio_put(folio);
 		return 0;
 	}
-	if (!folio_test_idle(folio) &&
+	if (!folio_test_idle(folio) && !prev_idle &&
 		(folio_test_young(folio) || folio_test_referenced(folio))) {
 
 		/* XXX: Leaking memory. TBD: consume info */
-- 
2.34.1