[RFC PATCH v1 4/7] mm: multi-gen LRU: support different page aging mechanism

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

Some architectures can handle different methods for determining
page access count. We may want to do architecture-specific tasks
reclassifying generation temperature etc during aging for such
architecture. Add an arch hook to support that.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 include/linux/page_aging.h | 14 +++++++++++++-
 mm/vmscan.c                |  8 +++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/linux/page_aging.h b/include/linux/page_aging.h
index ab77f4578916..d7c63ce0d824 100644
--- a/include/linux/page_aging.h
+++ b/include/linux/page_aging.h
@@ -11,6 +11,10 @@ static inline bool arch_supports_page_access_count(void)
 #endif
 
 #ifdef CONFIG_LRU_GEN
+bool __try_to_inc_max_seq(struct lruvec *lruvec,
+			  unsigned long max_seq, int scan_priority,
+			  bool can_swap, bool force_scan);
+
 #ifndef arch_get_lru_gen_seq
 static inline unsigned long arch_get_lru_gen_seq(struct lruvec *lruvec, struct folio *folio)
 {
@@ -19,8 +23,16 @@ static inline unsigned long arch_get_lru_gen_seq(struct lruvec *lruvec, struct f
 	return lruvec->lrugen.min_seq[type];
 }
 #endif
-#endif /* CONFIG_LRU_GEN */
 
+#ifndef arch_try_to_inc_max_seq
+static inline bool arch_try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
+					   int scan_priority, bool can_swap, bool force_scan)
+{
+	return __try_to_inc_max_seq(lruvec, max_seq, scan_priority, can_swap, force_scan);
+}
+#endif
+
+#endif /* CONFIG_LRU_GEN */
 #endif
 
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 518d1482f6ab..c8b98201f0b0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4536,7 +4536,13 @@ bool __try_to_inc_max_seq(struct lruvec *lruvec,
 static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
 			       int scan_priority, bool can_swap, bool force_scan)
 {
-	return __try_to_inc_max_seq(lruvec, max_seq, scan_priority, can_swap, force_scan);
+	if (arch_supports_page_access_count())
+		return arch_try_to_inc_max_seq(lruvec, max_seq,
+					       scan_priority, can_swap,
+					       force_scan);
+	else
+		return __try_to_inc_max_seq(lruvec, max_seq,
+					    scan_priority, can_swap, force_scan);
 }
 #endif
 
-- 
2.39.2