mm/vmstat.c: do not show lowmem reserve protection information of empty zone

Because the lowmem reserve protection of a zone can't tell anything if the
zone is empty, except of adding one more line in /proc/zoneinfo.

Let's remove it from that zone's showing.

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200402140113.3696-4-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5e24143..068706a 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1592,6 +1592,12 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
                   zone->present_pages,
                   zone_managed_pages(zone));
 
+       /* If unpopulated, no other information is useful */
+       if (!populated_zone(zone)) {
+               seq_putc(m, '\n');
+               return;
+       }
+
        seq_printf(m,
                   "\n        protection: (%ld",
                   zone->lowmem_reserve[0]);
@@ -1599,12 +1605,6 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
                seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
        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", zone_stat_name(i),
                           zone_page_state(zone, i));