mm, vmstat: suppress pcp stats for unpopulated zones in zoneinfo

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@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmstat.c b/mm/vmstat.c
index a828b17ced1a9d19d4074e5862ef5a10c2f760db..f5fa1bd1eb1656cb4e608bd301c83e92f66ac3b2 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1393,18 +1393,24 @@ 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;