Basic kernel memory functionality for the Memory Controller

This patch lays down the foundation for the kernel memory component
of the Memory Controller.

As of today, I am only laying down the following files:

 * memory.independent_kmem_limit
 * memory.kmem.limit_in_bytes (currently ignored)
 * memory.kmem.usage_in_bytes (always zero)

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Kirill A. Shutemov <kirill@shutemov.name>
CC: Paul Menage <paul@paulmenage.org>
CC: Greg Thelen <gthelen@google.com>
CC: Johannes Weiner <jweiner@redhat.com>
CC: Michal Hocko <mhocko@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 100 insertions, 5 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6aff93c98ac..9fbcff71245 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -227,6 +227,10 @@ struct mem_cgroup {
 	 */
 	struct res_counter memsw;
 	/*
+	 * the counter to account for kmem usage.
+	 */
+	struct res_counter kmem;
+	/*
 	 * Per cgroup active and inactive list, similar to the
 	 * per zone LRU lists.
 	 */
@@ -277,6 +281,11 @@ struct mem_cgroup {
 	 */
 	unsigned long 	move_charge_at_immigrate;
 	/*
+	 * Should kernel memory limits be stabilished independently
+	 * from user memory ?
+	 */
+	int		kmem_independent_accounting;
+	/*
 	 * percpu counter.
 	 */
 	struct mem_cgroup_stat_cpu *stat;
@@ -344,9 +353,14 @@ enum charge_type {
 };
 
 /* for encoding cft->private value on file */
-#define _MEM			(0)
-#define _MEMSWAP		(1)
-#define _OOM_TYPE		(2)
+
+enum mem_type {
+	_MEM = 0,
+	_MEMSWAP,
+	_OOM_TYPE,
+	_KMEM,
+};
+
 #define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
 #define MEMFILE_TYPE(val)	(((val) >> 16) & 0xffff)
 #define MEMFILE_ATTR(val)	((val) & 0xffff)
@@ -3848,10 +3862,17 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
 	u64 val;
 
 	if (!mem_cgroup_is_root(memcg)) {
+		val = 0;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+		if (!memcg->kmem_independent_accounting)
+			val = res_counter_read_u64(&memcg->kmem, RES_USAGE);
+#endif
 		if (!swap)
-			return res_counter_read_u64(&memcg->res, RES_USAGE);
+			val += res_counter_read_u64(&memcg->res, RES_USAGE);
 		else
-			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
+			val += res_counter_read_u64(&memcg->memsw, RES_USAGE);
+
+		return val;
 	}
 
 	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
@@ -3884,6 +3905,11 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 		else
 			val = res_counter_read_u64(&memcg->memsw, name);
 		break;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	case _KMEM:
+		val = res_counter_read_u64(&memcg->kmem, name);
+		break;
+#endif
 	default:
 		BUG();
 		break;
@@ -4612,6 +4638,69 @@ static int mem_control_numa_stat_open(struct inode *unused, struct file *file)
 }
 #endif /* CONFIG_NUMA */
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+static u64 kmem_limit_independent_read(struct cgroup *cgroup, struct cftype *cft)
+{
+	return mem_cgroup_from_cont(cgroup)->kmem_independent_accounting;
+}
+
+static int kmem_limit_independent_write(struct cgroup *cgroup, struct cftype *cft,
+					u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
+	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
+
+	val = !!val;
+
+	/*
+	 * This follows the same hierarchy restrictions than
+	 * mem_cgroup_hierarchy_write()
+	 */
+	if (!parent || !parent->use_hierarchy) {
+		if (list_empty(&cgroup->children))
+			memcg->kmem_independent_accounting = val;
+		else
+			return -EBUSY;
+	}
+	else
+		return -EINVAL;
+
+	return 0;
+}
+static struct cftype kmem_cgroup_files[] = {
+	{
+		.name = "independent_kmem_limit",
+		.read_u64 = kmem_limit_independent_read,
+		.write_u64 = kmem_limit_independent_write,
+	},
+	{
+		.name = "kmem.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "kmem.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
+		.read_u64 = mem_cgroup_read,
+	},
+};
+
+static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	int ret = 0;
+
+	ret = cgroup_add_files(cont, ss, kmem_cgroup_files,
+			       ARRAY_SIZE(kmem_cgroup_files));
+	return ret;
+};
+
+#else
+static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	return 0;
+}
+#endif
+
 static struct cftype mem_cgroup_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -4925,6 +5014,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	if (parent && parent->use_hierarchy) {
 		res_counter_init(&memcg->res, &parent->res);
 		res_counter_init(&memcg->memsw, &parent->memsw);
+		res_counter_init(&memcg->kmem, &parent->kmem);
 		/*
 		 * We increment refcnt of the parent to ensure that we can
 		 * safely access it on res_counter_charge/uncharge.
@@ -4935,6 +5025,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	} else {
 		res_counter_init(&memcg->res, NULL);
 		res_counter_init(&memcg->memsw, NULL);
+		res_counter_init(&memcg->kmem, NULL);
 	}
 	memcg->last_scanned_child = 0;
 	memcg->last_scanned_node = MAX_NUMNODES;
@@ -4978,6 +5069,10 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
 
 	if (!ret)
 		ret = register_memsw_files(cont, ss);
+
+	if (!ret)
+		ret = register_kmem_files(cont, ss);
+
 	return ret;
 }