[PATCH 2/2] mm/cgroup: delay soft limit data allocation
From: Laurent Dufour
Date: Wed Feb 22 2017 - 10:59:34 EST
Until a soft limit is set to a cgroup, the soft limit data are useless
so delay this allocation when a limit is set.
Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 52 +++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 39 insertions(+), 13 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 228ac44f77e1..bc2e6ab69c0c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -142,6 +142,8 @@ struct mem_cgroup_tree {
struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
};
+static DEFINE_MUTEX(soft_limit_mutex);
+static bool soft_limit_initialized;
static struct mem_cgroup_tree soft_limit_tree __read_mostly;
/* for OOM */
@@ -381,6 +383,36 @@ mem_cgroup_page_nodeinfo(struct mem_cgroup *memcg, struct page *page)
return memcg->nodeinfo[nid];
}
+static void soft_limit_initialize(void)
+{
+ int node;
+
+ mutex_lock(&soft_limit_mutex);
+ if (soft_limit_initialized)
+ goto bail;
+
+ for_each_node(node) {
+ struct mem_cgroup_tree_per_node *rtpn;
+
+ rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
+ node_online(node) ? node : NUMA_NO_NODE);
+ /* Best effort, but should we warn if allocation failed */
+ if (rtpn) {
+ rtpn->rb_root = RB_ROOT;
+ spin_lock_init(&rtpn->lock);
+ /*
+ * We don't want the compiler to set rb_tree_per_node
+ * before rb_root and lock are initialized.
+ */
+ WRITE_ONCE(soft_limit_tree.rb_tree_per_node[node],
+ rtpn);
+ }
+ }
+ soft_limit_initialized = true;
+bail:
+ mutex_unlock(&soft_limit_mutex);
+}
+
static struct mem_cgroup_tree_per_node *
soft_limit_tree_node(int nid)
{
@@ -465,6 +497,8 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
struct mem_cgroup_tree_per_node *mctz;
mctz = soft_limit_tree_from_page(page);
+ if (!mctz)
+ return;
/*
* Necessary to update all ancestors when hierarchy is used.
* because their event counter is not touched.
@@ -502,7 +536,8 @@ static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
for_each_node(nid) {
mz = mem_cgroup_nodeinfo(memcg, nid);
mctz = soft_limit_tree_node(nid);
- mem_cgroup_remove_exceeded(mz, mctz);
+ if (mctz)
+ mem_cgroup_remove_exceeded(mz, mctz);
}
}
@@ -3000,6 +3035,8 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
}
break;
case RES_SOFT_LIMIT:
+ if (!soft_limit_initialized)
+ soft_limit_initialize();
memcg->soft_limit = nr_pages;
ret = 0;
break;
@@ -5774,7 +5811,7 @@ __setup("cgroup.memory=", cgroup_memory);
*/
static int __init mem_cgroup_init(void)
{
- int cpu, node;
+ int cpu;
#ifndef CONFIG_SLOB
/*
@@ -5794,17 +5831,6 @@ static int __init mem_cgroup_init(void)
INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
drain_local_stock);
- for_each_node(node) {
- struct mem_cgroup_tree_per_node *rtpn;
-
- rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
- node_online(node) ? node : NUMA_NO_NODE);
-
- rtpn->rb_root = RB_ROOT;
- spin_lock_init(&rtpn->lock);
- soft_limit_tree.rb_tree_per_node[node] = rtpn;
- }
-
return 0;
}
subsys_initcall(mem_cgroup_init);
--
2.7.4