mm: fix up the vmscan stat in vmstat

The "pgsteal" stat is confusing because it counts both direct reclaim as
well as background reclaim.  However, we have "kswapd_steal" which also
counts background reclaim value.

This patch fixes it and also makes it match the existng "pgscan_" stats.

Test:
pgsteal_kswapd_dma32 447623
pgsteal_kswapd_normal 42272677
pgsteal_kswapd_movable 0
pgsteal_direct_dma32 2801
pgsteal_direct_normal 44353270
pgsteal_direct_movable 0

Signed-off-by: Ying Han <yinghan@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 13 insertions, 7 deletions

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 03b90cdc192..06f8e385825 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -26,13 +26,14 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
                 PGFREE, PGACTIVATE, PGDEACTIVATE,
                 PGFAULT, PGMAJFAULT,
                 FOR_ALL_ZONES(PGREFILL),
-                FOR_ALL_ZONES(PGSTEAL),
+                FOR_ALL_ZONES(PGSTEAL_KSWAPD),
+                FOR_ALL_ZONES(PGSTEAL_DIRECT),
                 FOR_ALL_ZONES(PGSCAN_KSWAPD),
                 FOR_ALL_ZONES(PGSCAN_DIRECT),
 #ifdef CONFIG_NUMA
                 PGSCAN_ZONE_RECLAIM_FAILED,
 #endif
-                PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL,
+                PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
                 KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
                 KSWAPD_SKIP_CONGESTION_WAIT,
                 PAGEOUTRUN, ALLOCSTALL, PGROTATED,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1a518684a32..33dc256033b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1568,9 +1568,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
         reclaim_stat->recent_scanned[0] += nr_anon;
         reclaim_stat->recent_scanned[1] += nr_file;
 
-        if (current_is_kswapd())
-                __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
-        __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
+        if (global_reclaim(sc)) {
+                if (current_is_kswapd())
+                        __count_zone_vm_events(PGSTEAL_KSWAPD, zone,
+                                               nr_reclaimed);
+                else
+                        __count_zone_vm_events(PGSTEAL_DIRECT, zone,
+                                               nr_reclaimed);
+        }
 
         putback_inactive_pages(mz, &page_list);
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f600557a765..7db1b9bab49 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -738,7 +738,8 @@ const char * const vmstat_text[] = {
         "pgmajfault",
 
         TEXTS_FOR_ZONES("pgrefill")
-        TEXTS_FOR_ZONES("pgsteal")
+        TEXTS_FOR_ZONES("pgsteal_kswapd")
+        TEXTS_FOR_ZONES("pgsteal_direct")
         TEXTS_FOR_ZONES("pgscan_kswapd")
         TEXTS_FOR_ZONES("pgscan_direct")
 
@@ -747,7 +748,6 @@ const char * const vmstat_text[] = {
 #endif
         "pginodesteal",
         "slabs_scanned",
-        "kswapd_steal",
         "kswapd_inodesteal",
         "kswapd_low_wmark_hit_quickly",
         "kswapd_high_wmark_hit_quickly",