vmstat: mlocked pages statistics

Add NR_MLOCK zone page state, which provides a (conservative) count of
mlocked pages (actually, the number of mlocked pages moved off the LRU).

Reworked by lts to fit in with the modified mlock page support in the
Reclaim Scalability series.

[kosaki.motohiro@jp.fujitsu.com: fix incorrect Mlocked field of /proc/meminfo]
[lee.schermerhorn@hp.com: mlocked-pages: add event counting with statistics]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d1f60d5fe2ea..da2d053a95f1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -88,8 +88,10 @@ enum zone_stat_item {
         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
 #ifdef CONFIG_UNEVICTABLE_LRU
         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
+        NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
 #else
         NR_UNEVICTABLE = NR_ACTIVE_FILE, /* avoid compiler errors in dead code */
+        NR_MLOCK = NR_ACTIVE_FILE,
 #endif
         NR_ANON_PAGES,  /* Mapped anonymous pages */
         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.