[patch 1/2] mm: vmstat: introduce node_page_state_pages_snapshot

[Marcelo Tosatti]

Introduce a _snapshot variant of node_page_state_snapshot,
similar to zone_page_state_snapshot.

To be used by next patch.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

---
 include/linux/vmstat.h |    4 ++++
 mm/vmstat.c            |   28 ++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

Index: linux/mm/vmstat.c
===================================================================
--- linux.orig/mm/vmstat.c
+++ linux/mm/vmstat.c
@@ -1031,6 +1031,34 @@ unsigned long node_page_state(struct pgl
 
 	return node_page_state_pages(pgdat, item);
 }
+
+/*
+ * Determine the per node value of a stat item, snapshot version
+ * (see comment on top zone_page_state_snapshot).
+ */
+unsigned long node_page_state_pages_snapshot(struct pglist_data *pgdat,
+					     enum node_stat_item item)
+{
+	long x = atomic_long_read(&pgdat->vm_stat[item]);
+#ifdef CONFIG_SMP
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		x += per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->vm_node_stat_diff[item];
+
+	if (x < 0)
+		x = 0;
+#endif
+	return x;
+}
+
+unsigned long node_page_state_snapshot(struct pglist_data *pgdat,
+				       enum node_stat_item item)
+{
+	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
+
+	return node_page_state_pages(pgdat, item);
+}
 #endif
 
 #ifdef CONFIG_COMPACTION
Index: linux/include/linux/vmstat.h
===================================================================
--- linux.orig/include/linux/vmstat.h
+++ linux/include/linux/vmstat.h
@@ -262,6 +262,10 @@ extern unsigned long node_page_state(str
 						enum node_stat_item item);
 extern unsigned long node_page_state_pages(struct pglist_data *pgdat,
 					   enum node_stat_item item);
+extern unsigned long node_page_state_snapshot(struct pglist_data *pgdat,
+						enum node_stat_item item);
+extern unsigned long node_page_state_pages_snapshot(struct pglist_data *pgdat,
+						    enum node_stat_item item);
 extern void fold_vm_numa_events(void);
 #else
 #define sum_zone_node_page_state(node, item) global_zone_page_state(item)