[PATCH AUTOSEL for 4.9 144/190] mm, vmstat: suppress pcp stats for unpopulated zones in zoneinfo

[Sasha Levin]

From: David Rientjes <rientjes@xxxxxxxxxx>

[ Upstream commit 7dfb8bf3b9caef4049bee51d2c22e1c3a311d483 ]

After "mm, vmstat: print non-populated zones in zoneinfo",
/proc/zoneinfo will show unpopulated zones.

The per-cpu pageset statistics are not relevant for unpopulated zones
and can be potentially lengthy, so supress them when they are not
interesting.

Also moves lowmem reserve protection information above pcp stats since
it is relevant for all zones per vm.lowmem_reserve_ratio.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703061400500.46428@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 mm/vmstat.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 3863b5d6d598..68b3193e4493 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1387,18 +1387,24 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		   zone->present_pages,
 		   zone->managed_pages);
 
-	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
-		seq_printf(m, "\n      %-12s %lu", vmstat_text[i],
-				zone_page_state(zone, i));
-
 	seq_printf(m,
 		   "\n        protection: (%ld",
 		   zone->lowmem_reserve[0]);
 	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
 		seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
-	seq_printf(m,
-		   ")"
-		   "\n  pagesets");
+	seq_putc(m, ')');
+
+	/* If unpopulated, no other information is useful */
+	if (!populated_zone(zone)) {
+		seq_putc(m, '\n');
+		return;
+	}
+
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		seq_printf(m, "\n      %-12s %lu", vmstat_text[i],
+				zone_page_state(zone, i));
+
+	seq_printf(m, "\n  pagesets");
 	for_each_online_cpu(i) {
 		struct per_cpu_pageset *pageset;
 
-- 
2.14.1