[PATCH] VM: add page_state info to per-node meminfo

Add page_state info to the per-node meminfo file in sysfs.  This is mostly
just for informational purposes.

The lack of this information was brought up recently during a discussion
regarding pagecache clearing, and I put this patch together to test out one
of the suggestions.

It seems like interesting info to have, so I'm submitting the patch.

Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 904b27c..16c513a 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -39,13 +39,25 @@
 	int n;
 	int nid = dev->id;
 	struct sysinfo i;
+	struct page_state ps;
 	unsigned long inactive;
 	unsigned long active;
 	unsigned long free;
 
 	si_meminfo_node(&i, nid);
+	get_page_state_node(&ps, nid);
 	__get_zone_counts(&active, &inactive, &free, NODE_DATA(nid));
 
+	/* Check for negative values in these approximate counters */
+	if ((long)ps.nr_dirty < 0)
+		ps.nr_dirty = 0;
+	if ((long)ps.nr_writeback < 0)
+		ps.nr_writeback = 0;
+	if ((long)ps.nr_mapped < 0)
+		ps.nr_mapped = 0;
+	if ((long)ps.nr_slab < 0)
+		ps.nr_slab = 0;
+
 	n = sprintf(buf, "\n"
 		       "Node %d MemTotal:     %8lu kB\n"
 		       "Node %d MemFree:      %8lu kB\n"
@@ -55,7 +67,11 @@
 		       "Node %d HighTotal:    %8lu kB\n"
 		       "Node %d HighFree:     %8lu kB\n"
 		       "Node %d LowTotal:     %8lu kB\n"
-		       "Node %d LowFree:      %8lu kB\n",
+		       "Node %d LowFree:      %8lu kB\n"
+		       "Node %d Dirty:        %8lu kB\n"
+		       "Node %d Writeback:    %8lu kB\n"
+		       "Node %d Mapped:       %8lu kB\n"
+		       "Node %d Slab:         %8lu kB\n",
 		       nid, K(i.totalram),
 		       nid, K(i.freeram),
 		       nid, K(i.totalram - i.freeram),
@@ -64,7 +80,11 @@
 		       nid, K(i.totalhigh),
 		       nid, K(i.freehigh),
 		       nid, K(i.totalram - i.totalhigh),
-		       nid, K(i.freeram - i.freehigh));
+		       nid, K(i.freeram - i.freehigh),
+		       nid, K(ps.nr_dirty),
+		       nid, K(ps.nr_writeback),
+		       nid, K(ps.nr_mapped),
+		       nid, K(ps.nr_slab));
 	n += hugetlb_report_node_meminfo(nid, buf + n);
 	return n;
 }