mm: print the promo watermark in zoneinfo

Print the promo watermark in zoneinfo just like other watermarks.  This
helps users check and verify all the watermarks are appropriate.

Link: https://lkml.kernel.org/r/20240801232548.36604-3-kaiyang2@cs.cmu.eduSigned-off-by: Kaiyang Zhao <kaiyang2@cs.cmu.edu>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmstat.c

@@ -1743,6 +1743,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		   "\n        min      %lu"
 		   "\n        low      %lu"
 		   "\n        high     %lu"
+		   "\n        promo    %lu"
 		   "\n        spanned  %lu"
 		   "\n        present  %lu"
 		   "\n        managed  %lu"
@@ -1752,6 +1753,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		   min_wmark_pages(zone),
 		   low_wmark_pages(zone),
 		   high_wmark_pages(zone),
+		   promo_wmark_pages(zone),
 		   zone->spanned_pages,
 		   zone->present_pages,
 		   zone_managed_pages(zone),