mm: avoid taking zone lock in pagetypeinfo_showmixed()

pagetypeinfo_showmixedcount_print is found to take a lot of time to
complete and it does this holding the zone lock and disabling interrupts.
In some cases it is found to take more than a second (On a 2.4GHz,8Gb
RAM,arm64 cpu).  Avoid taking the zone lock similar to what is done by
read_page_owner, which means possibility of inaccurate results.

Change-Id: I11ec4a3a445d602e47fcc18a3e40480b74ad98af
Link: http://lkml.kernel.org/r/1498045643-12257-1-git-send-email-vinmenon@codeaurora.org
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: zhongjiang <zhongjiang@huawei.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Git-commit: a94b5fd913ac55a32fe05dfba21eb6af0e539781
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
[vinmenon@codeaurora.org: fix trivial merge conflicts]
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>

1 files changed, 17 insertions, 10 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index b8f2eda3381d..d6b4817c4416 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -906,6 +906,7 @@ static void frag_stop(struct seq_file *m, void *arg)
 
 /* Walk all the zones in a node and print using a callback */
 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
+		bool nolock,
 		void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 {
 	struct zone *zone;
@@ -916,9 +917,11 @@ static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 		if (!populated_zone(zone))
 			continue;
 
-		spin_lock_irqsave(&zone->lock, flags);
+		if (!nolock)
+			spin_lock_irqsave(&zone->lock, flags);
 		print(m, pgdat, zone);
-		spin_unlock_irqrestore(&zone->lock, flags);
+		if (!nolock)
+			spin_unlock_irqrestore(&zone->lock, flags);
 	}
 }
 #endif
@@ -954,7 +957,7 @@ static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 static int frag_show(struct seq_file *m, void *arg)
 {
 	pg_data_t *pgdat = (pg_data_t *)arg;
-	walk_zones_in_node(m, pgdat, frag_show_print);
+	walk_zones_in_node(m, pgdat, false, frag_show_print);
 	return 0;
 }
 
@@ -995,7 +998,7 @@ static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 		seq_printf(m, "%6d ", order);
 	seq_putc(m, '\n');
 
-	walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
+	walk_zones_in_node(m, pgdat, false, pagetypeinfo_showfree_print);
 
 	return 0;
 }
@@ -1044,7 +1047,7 @@ static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 		seq_printf(m, "%12s ", migratetype_names[mtype]);
 	seq_putc(m, '\n');
-	walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
+	walk_zones_in_node(m, pgdat, false, pagetypeinfo_showblockcount_print);
 
 	return 0;
 }
@@ -1088,7 +1091,11 @@ static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
 
 			page = pfn_to_page(pfn);
 			if (PageBuddy(page)) {
-				pfn += (1UL << page_order(page)) - 1;
+				unsigned long freepage_order;
+
+				freepage_order = page_order_unsafe(page);
+				if (freepage_order < MAX_ORDER)
+					pfn += (1UL << freepage_order) - 1;
 				continue;
 			}
 
@@ -1143,7 +1150,7 @@ static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
 		seq_printf(m, "%12s ", migratetype_names[mtype]);
 	seq_putc(m, '\n');
 
-	walk_zones_in_node(m, pgdat, pagetypeinfo_showmixedcount_print);
+	walk_zones_in_node(m, pgdat, true, pagetypeinfo_showmixedcount_print);
 #endif /* CONFIG_PAGE_OWNER */
 }
 
@@ -1276,7 +1283,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 static int zoneinfo_show(struct seq_file *m, void *arg)
 {
 	pg_data_t *pgdat = (pg_data_t *)arg;
-	walk_zones_in_node(m, pgdat, zoneinfo_show_print);
+	walk_zones_in_node(m, pgdat, false, zoneinfo_show_print);
 	return 0;
 }
 
@@ -1635,7 +1642,7 @@ static int unusable_show(struct seq_file *m, void *arg)
 	if (!node_state(pgdat->node_id, N_MEMORY))
 		return 0;
 
-	walk_zones_in_node(m, pgdat, unusable_show_print);
+	walk_zones_in_node(m, pgdat, false, unusable_show_print);
 
 	return 0;
 }
@@ -1687,7 +1694,7 @@ static int extfrag_show(struct seq_file *m, void *arg)
 {
 	pg_data_t *pgdat = (pg_data_t *)arg;
 
-	walk_zones_in_node(m, pgdat, extfrag_show_print);
+	walk_zones_in_node(m, pgdat, false, extfrag_show_print);
 
 	return 0;
 }