---

yaml
---
r: 198247
b: refs/heads/master
c: 76ab0f5
h: refs/heads/master
i:
  198245: e6cc5d7
  198243: 222b03c
  198239: d83e277
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 748446bb6b5a9390b546af38ec899c868a9dbcf0
+refs/heads/master: 76ab0f530e4a01d4dc20cdc1d5e87753c579dc18

trunk/Documentation/sysctl/vm.txt

@@ -19,6 +19,7 @@ files can be found in mm/swap.c.
 Currently, these files are in /proc/sys/vm:
 
 - block_dump
+- compact_memory
 - dirty_background_bytes
 - dirty_background_ratio
 - dirty_bytes
@@ -64,6 +65,15 @@ information on block I/O debugging is in Documentation/laptops/laptop-mode.txt.
 
 ==============================================================
 
+compact_memory
+
+Available only when CONFIG_COMPACTION is set. When 1 is written to the file,
+all zones are compacted such that free memory is available in contiguous
+blocks where possible. This can be important for example in the allocation of
+huge pages although processes will also directly compact memory as required.
+
+==============================================================
+
 dirty_background_bytes
 
 Contains the amount of dirty memory at which the pdflush background writeback

trunk/include/linux/compaction.h

@@ -6,4 +6,10 @@
 #define COMPACT_PARTIAL		1
 #define COMPACT_COMPLETE	2
 
+#ifdef CONFIG_COMPACTION
+extern int sysctl_compact_memory;
+extern int sysctl_compaction_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos);
+#endif /* CONFIG_COMPACTION */
+
 #endif /* _LINUX_COMPACTION_H */

trunk/kernel/sysctl.c

@@ -37,6 +37,7 @@
 #include <linux/highuid.h>
 #include <linux/writeback.h>
 #include <linux/ratelimit.h>
+#include <linux/compaction.h>
 #include <linux/hugetlb.h>
 #include <linux/initrd.h>
 #include <linux/key.h>
@@ -1121,6 +1122,15 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= drop_caches_sysctl_handler,
 	},
+#ifdef CONFIG_COMPACTION
+	{
+		.procname	= "compact_memory",
+		.data		= &sysctl_compact_memory,
+		.maxlen		= sizeof(int),
+		.mode		= 0200,
+		.proc_handler	= sysctl_compaction_handler,
+	},
+#endif /* CONFIG_COMPACTION */
 	{
 		.procname	= "min_free_kbytes",
 		.data		= &min_free_kbytes,

trunk/mm/compaction.c

@@ -12,6 +12,7 @@
 #include <linux/compaction.h>
 #include <linux/mm_inline.h>
 #include <linux/backing-dev.h>
+#include <linux/sysctl.h>
 #include "internal.h"
 
 /*
@@ -391,3 +392,64 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 
 	return ret;
 }
+
+/* Compact all zones within a node */
+static int compact_node(int nid)
+{
+	int zoneid;
+	pg_data_t *pgdat;
+	struct zone *zone;
+
+	if (nid < 0 || nid >= nr_node_ids || !node_online(nid))
+		return -EINVAL;
+	pgdat = NODE_DATA(nid);
+
+	/* Flush pending updates to the LRU lists */
+	lru_add_drain_all();
+
+	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+		struct compact_control cc = {
+			.nr_freepages = 0,
+			.nr_migratepages = 0,
+		};
+
+		zone = &pgdat->node_zones[zoneid];
+		if (!populated_zone(zone))
+			continue;
+
+		cc.zone = zone;
+		INIT_LIST_HEAD(&cc.freepages);
+		INIT_LIST_HEAD(&cc.migratepages);
+
+		compact_zone(zone, &cc);
+
+		VM_BUG_ON(!list_empty(&cc.freepages));
+		VM_BUG_ON(!list_empty(&cc.migratepages));
+	}
+
+	return 0;
+}
+
+/* Compact all nodes in the system */
+static int compact_nodes(void)
+{
+	int nid;
+
+	for_each_online_node(nid)
+		compact_node(nid);
+
+	return COMPACT_COMPLETE;
+}
+
+/* The written value is actually unused, all memory is compacted */
+int sysctl_compact_memory;
+
+/* This is the entry point for compacting all nodes via /proc/sys/vm */
+int sysctl_compaction_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	if (write)
+		return compact_nodes();
+
+	return 0;
+}