[PATCH 3/4] mm: workingset: add vmstat counter for shadow nodes

Johannes Weiner
2018-10-09T18:48:22Z

Make it easier to catch bugs in the shadow node shrinker by adding a
counter for the shadow nodes in circulation.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
include/linux/mmzone.h | 1 +
mm/vmstat.c | 1 +
mm/workingset.c | 12 ++++++++++--
3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4179e67add3d..d82e80d82aa6 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -161,6 +161,7 @@ enum node_stat_item {
NR_SLAB_UNRECLAIMABLE,
NR_ISOLATED_ANON, /* Temporary isolated pages from anon lru */
NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */
+ WORKINGSET_NODES,
WORKINGSET_REFAULT,
WORKINGSET_ACTIVATE,
WORKINGSET_RESTORE,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index d08ed044759d..6038ce593ce3 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1143,6 +1143,7 @@ const char * const vmstat_text[] = {
"nr_slab_unreclaimable",
"nr_isolated_anon",
"nr_isolated_file",
+ "workingset_nodes",
"workingset_refault",
"workingset_activate",
"workingset_restore",
diff --git a/mm/workingset.c b/mm/workingset.c
index f564aaa6b71d..cfdf6adf7e7c 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -378,11 +378,17 @@ void workingset_update_node(struct xa_node *node)
* as node->private_list is protected by the i_pages lock.
*/
if (node->count && node->count == node->nr_values) {
- if (list_empty(&node->private_list))
+ if (list_empty(&node->private_list)) {
list_lru_add(&shadow_nodes, &node->private_list);
+ __inc_lruvec_page_state(virt_to_page(node),
+ WORKINGSET_NODES);
+ }
} else {
- if (!list_empty(&node->private_list))
+ if (!list_empty(&node->private_list)) {
list_lru_del(&shadow_nodes, &node->private_list);
+ __dec_lruvec_page_state(virt_to_page(node),
+ WORKINGSET_NODES);
+ }
}
}

@@ -472,6 +478,8 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
}

list_lru_isolate(lru, item);
+ __dec_lruvec_page_state(virt_to_page(node), WORKINGSET_NODES);
+
spin_unlock(lru_lock);

/*
--
2.19.0