[RFC][PATCH 4/7] memcg : test a memcg is reclaimable

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

A function for checking that a memcg has reclaimable pages. This makes
use of mem->scan_nodes when CONFIG_NUMA=y.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 include/linux/memcontrol.h |    1 +
 mm/memcontrol.c            |   19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

Index: mmotm-May6/mm/memcontrol.c
===================================================================
--- mmotm-May6.orig/mm/memcontrol.c
+++ mmotm-May6/mm/memcontrol.c
@@ -1623,11 +1623,30 @@ int mem_cgroup_select_victim_node(struct
 	return node;
 }
 
+bool mem_cgroup_test_reclaimable(struct mem_cgroup *memcg)
+{
+	mem_cgroup_may_update_nodemask(memcg);
+	return !nodes_empty(memcg->scan_nodes);
+}
+
 #else
 int mem_cgroup_select_victim_node(struct mem_cgroup *mem)
 {
 	return 0;
 }
+
+bool mem_cgroup_test_reclaimable(struct mem_cgroup *memcg)
+{
+	unsigned long nr;
+	int zid;
+
+	for (zid = NODE_DATA(0)->nr_zones - 1; zid >= 0; zid--)
+		if (mem_cgroup_zone_reclaimable_pages(memcg, 0, zid))
+			break;
+	if (zid < 0)
+		return false;
+	return true;
+}
 #endif
 
 /*
Index: mmotm-May6/include/linux/memcontrol.h
===================================================================
--- mmotm-May6.orig/include/linux/memcontrol.h
+++ mmotm-May6/include/linux/memcontrol.h
@@ -110,6 +110,7 @@ int mem_cgroup_inactive_anon_is_low(stru
 int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg);
 unsigned long
 mem_cgroup_zone_reclaimable_pages(struct mem_cgroup *memcg, int nid, int zid);
+bool mem_cgroup_test_reclaimable(struct mem_cgroup *memcg);
 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
 unsigned int mem_cgroup_swappiness(struct mem_cgroup *memcg);
 unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,

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