[RFC PATCH v2 2/6] mm/damon/vaddr: use damos->last_applied for migrate action

[SJ Park <sj@kernel.org>]

To avoid applying the same DAMOS action multiple times to folios that
are located across adjacent regions, damos->last_applied was introduced.
DAMOS_MIGRATE_{HOT,COLD} action support in vaddr is not utilizing it.
Use it to avoid unnecessarily applying the same action to the same folio
multiple times.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/vaddr.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index c271b6d63c027..b1d7bcf7305bb 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -834,6 +834,12 @@ static void damos_va_migrate_dests_add(struct folio *folio,
 	list_add(&folio->lru, &migration_lists[i]);
 }
 
+static inline bool damos_va_invalid_folio(struct folio *folio,
+		struct damos *s)
+{
+	return !folio || folio == s->last_applied;
+}
+
 static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
 		unsigned long next, struct mm_walk *walk)
 {
@@ -854,10 +860,11 @@ static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
 		if (!pmd_present(pmde))
 			goto huge_out;
 		folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
-		if (!folio)
+		if (damos_va_invalid_folio(folio, s))
 			goto huge_out;
 		if (damos_va_filter_out(s, folio, walk->vma, addr, NULL, pmd))
 			goto huge_out;
+		s->last_applied = folio;
 		damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
 				migration_lists);
 huge_out:
@@ -879,12 +886,13 @@ static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
 		if (pte_none(ptent) || !pte_present(ptent))
 			continue;
 		folio = vm_normal_folio(walk->vma, addr, ptent);
-		if (!folio)
+		if (damos_va_invalid_folio(folio, s))
 			continue;
 		page_idx = folio_page_idx(folio, pte_page(ptent));
 		nr = folio_nr_pages(folio) - page_idx;
 		if (damos_va_filter_out(s, folio, walk->vma, addr, pte, NULL))
 			continue;
+		s->last_applied = folio;
 		damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
 				migration_lists);
 	}
@@ -991,12 +999,6 @@ struct damos_va_stat_private {
 	unsigned long *sz_filter_passed;
 };
 
-static inline bool damos_va_invalid_folio(struct folio *folio,
-		struct damos *s)
-{
-	return !folio || folio == s->last_applied;
-}
-
 static int damos_va_stat_pmd_entry(pmd_t *pmd, unsigned long addr,
 		unsigned long next, struct mm_walk *walk)
 {
-- 
2.47.3