From 1b089def0fb8833ec4b331b61908f29d6b491ccb Mon Sep 17 00:00:00 2001 From: Usama Arif Date: Mon, 27 Jul 2026 09:23:24 -0700 Subject: [PATCH] mm/vmscan: add pgrotate_anon and pgrotate_file vmstat counters Reclaim can spend substantial work on an LRU type without immediately reclaiming or demoting a corresponding amount of memory. Record this work in PGROTATE_ANON and PGROTATE_FILE. For classic LRU reclaim: - Inactive-list reclaim adds nr_scanned - nr_reclaimed to the corresponding anon/file counter when isolation succeeds. - Active-list reclaim adds referenced executable file folios that are retained on the active list to PGROTATE_FILE. Active anon reclaim does not contribute this component. For MGLRU, add the number of initially isolated pages that remain unreclaimed after both the initial and retry passes to the counter for the selected anon/file type. These counters are distinct from the existing pgrotated vm event. pgrotated records an actual move to the inactive-list tail, primarily after reclaim-marked writeback completes or failed invalidation leaves a folio for accelerated reclaim. PGROTATE_ANON and PGROTATE_FILE measure reclaim cost and do not imply that a folio moved to an LRU tail. A subsequent patch will consume these counters for anon/file scan balancing. Link: https://lore.kernel.org/20260727162550.2032-3-usama.arif@linux.dev Signed-off-by: Usama Arif Acked-by: Shakeel Butt Acked-by: Johannes Weiner Reviewed-by: Vlastimil Babka (SUSE) Cc: Axel Rasmussen Cc: Baoquan He Cc: Chris Li Cc: David Hildenbrand Cc: David Rientjes Cc: Kairui Song Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Nhat Pham Cc: Roman Gushchin Cc: Suren Baghdasaryan Cc: Wei Xu Cc: Yuanchu Xie Signed-off-by: Andrew Morton --- include/linux/mmzone.h | 2 ++ mm/memcontrol.c | 2 ++ mm/vmscan.c | 14 +++++++++++++- mm/vmstat.c | 2 ++ 4 files changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 0507193b3ae3..1cc5ea506b7c 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -323,6 +323,8 @@ enum node_stat_item { PGSCAN_PROACTIVE, PGSCAN_ANON, PGSCAN_FILE, + PGROTATE_ANON, + PGROTATE_FILE, PGREFILL, #ifdef CONFIG_HUGETLB_PAGE NR_HUGETLB, diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d804f8d07581..011bb3b0346b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -425,6 +425,8 @@ static const unsigned int memcg_node_stat_items[] = { PGSCAN_PROACTIVE, PGSCAN_ANON, PGSCAN_FILE, + PGROTATE_ANON, + PGROTATE_FILE, PGREFILL, #ifdef CONFIG_HUGETLB_PAGE NR_HUGETLB, diff --git a/mm/vmscan.c b/mm/vmscan.c index 5bad065a38f1..fa2c5cf577af 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2038,6 +2038,9 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan, item = PGSTEAL_KSWAPD + reclaimer_offset(sc); mod_lruvec_state(lruvec, item, nr_reclaimed); mod_lruvec_state(lruvec, PGSTEAL_ANON + file, nr_reclaimed); + if (nr_scanned > nr_reclaimed) + mod_lruvec_state(lruvec, PGROTATE_ANON + file, + nr_scanned - nr_reclaimed); lruvec_lock_irq(lruvec); lru_note_cost_unlock_irq(lruvec, file, stat.nr_pageout, @@ -2147,6 +2150,8 @@ static void shrink_active_list(unsigned long nr_to_scan, count_vm_events(PGDEACTIVATE, nr_deactivate); count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate); mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); + if (nr_rotated) + mod_lruvec_state(lruvec, PGROTATE_ANON + file, nr_rotated); lruvec_lock_irq(lruvec); lru_note_cost_unlock_irq(lruvec, file, 0, nr_rotated); @@ -4828,7 +4833,8 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec, struct reclaim_stat stat; struct lru_gen_mm_walk *walk; int scanned, reclaimed; - int isolated = 0, type, type_scanned; + int isolated = 0, nr_isolated = 0, type, type_scanned; + unsigned long total_reclaimed = 0; bool skip_retry = false; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct pglist_data *pgdat = lruvec_pgdat(lruvec); @@ -4840,6 +4846,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec, scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness, &list, &isolated, &type, &type_scanned); + nr_isolated = isolated; /* Scanning may have emptied the oldest gen, flush it */ if (scanned) @@ -4852,6 +4859,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec, retry: reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false, memcg); sc->nr_reclaimed += reclaimed; + total_reclaimed += reclaimed; /* Retry pass is only meant for clean folios without new isolation */ if (isolated) handle_reclaim_writeback(isolated, pgdat, sc, &stat); @@ -4903,6 +4911,10 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec, goto retry; } + if (nr_isolated > total_reclaimed) + mod_lruvec_state(lruvec, PGROTATE_ANON + type, + nr_isolated - total_reclaimed); + return scanned; } diff --git a/mm/vmstat.c b/mm/vmstat.c index 507118474c03..7d6e61a01f51 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1301,6 +1301,8 @@ const char * const vmstat_text[] = { [I(PGSCAN_PROACTIVE)] = "pgscan_proactive", [I(PGSCAN_ANON)] = "pgscan_anon", [I(PGSCAN_FILE)] = "pgscan_file", + [I(PGROTATE_ANON)] = "pgrotate_anon", + [I(PGROTATE_FILE)] = "pgrotate_file", [I(PGREFILL)] = "pgrefill", #ifdef CONFIG_HUGETLB_PAGE [I(NR_HUGETLB)] = "nr_hugetlb",