memcg: memory cgroup hierarchy feature selector

Don't enable multiple hierarchy support by default. This patch introduces a features element that can be set to enable the nested depth hierarchy feature. This feature can only be enabled when the cgroup for which the feature this is enabled, has no children. Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: memory cgroup hierarchy feature selector
Don't enable multiple hierarchy support by default. This patch introduces a features element that can be set to enable the nested depth hierarchy feature. This feature can only be enabled when the cgroup for which the feature this is enabled, has no children. Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Balbir Singh · Linus Torvalds
1 parent 6d61ef409d
Showing 1 changed file with 57 additions and 4 deletions Side-by-side Diff
mm/memcontrol.c
@@ -149,6 +149,10 @@
 	 * reclaimed from. Protected by cgroup_lock()
 	 */
 	struct mem_cgroup *last_scanned_child;
+	/*
+	 * Should the accounting and control be hierarchical, per subtree?
+	 */
+	bool use_hierarchy;
  
 	int		obsolete;
 	atomic_t	refcnt;
@@ -1543,6 +1547,44 @@
 }
  
  
+static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
+{
+	return mem_cgroup_from_cont(cont)->use_hierarchy;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
+					u64 val)
+{
+	int retval = 0;
+	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+	struct cgroup *parent = cont->parent;
+	struct mem_cgroup *parent_mem = NULL;
+
+	if (parent)
+		parent_mem = mem_cgroup_from_cont(parent);
+
+	cgroup_lock();
+	/*
+	 * If parent's use_hiearchy is set, we can't make any modifications
+	 * in the child subtrees. If it is unset, then the change can
+	 * occur, provided the current cgroup has no children.
+	 *
+	 * For the root cgroup, parent_mem is NULL, we allow value to be
+	 * set if there are no children.
+	 */
+	if ((!parent_mem || !parent_mem->use_hierarchy) &&
+				(val == 1 || val == 0)) {
+		if (list_empty(&cont->children))
+			mem->use_hierarchy = val;
+		else
+			retval = -EBUSY;
+	} else
+		retval = -EINVAL;
+	cgroup_unlock();
+
+	return retval;
+}
+
 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
 	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
@@ -1706,6 +1748,11 @@
 		.name = "force_empty",
 		.trigger = mem_cgroup_force_empty_write,
 	},
+	{
+		.name = "use_hierarchy",
+		.write_u64 = mem_cgroup_hierarchy_write,
+		.read_u64 = mem_cgroup_hierarchy_read,
+	},
 };
  
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
  
  
@@ -1881,12 +1928,18 @@
 	if (cont->parent == NULL) {
 		enable_swap_cgroup();
 		parent = NULL;
-	} else
+	} else {
 		parent = mem_cgroup_from_cont(cont->parent);
+		mem->use_hierarchy = parent->use_hierarchy;
+	}
  
-	res_counter_init(&mem->res, parent ? &parent->res : NULL);
-	res_counter_init(&mem->memsw, parent ? &parent->memsw : NULL);
-
+	if (parent && parent->use_hierarchy) {
+		res_counter_init(&mem->res, &parent->res);
+		res_counter_init(&mem->memsw, &parent->memsw);
+	} else {
+		res_counter_init(&mem->res, NULL);
+		res_counter_init(&mem->memsw, NULL);
+	}
  
 	mem->last_scanned_child = NULL;
...	...	@@ -149,6 +149,10 @@
149	149	* reclaimed from. Protected by cgroup_lock()
150	150	*/
151	151	struct mem_cgroup *last_scanned_child;
	152	+ /*
	153	+ * Should the accounting and control be hierarchical, per subtree?
	154	+ */
	155	+ bool use_hierarchy;
152	156
153	157	int obsolete;
154	158	atomic_t refcnt;
...	...	@@ -1543,6 +1547,44 @@
1543	1547	}
1544	1548
1545	1549
	1550	+static u64 mem_cgroup_hierarchy_read(struct cgroup cont, struct cftype cft)
	1551	+{
	1552	+ return mem_cgroup_from_cont(cont)->use_hierarchy;
	1553	+}
	1554	+
	1555	+static int mem_cgroup_hierarchy_write(struct cgroup cont, struct cftype cft,
	1556	+ u64 val)
	1557	+{
	1558	+ int retval = 0;
	1559	+ struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
	1560	+ struct cgroup *parent = cont->parent;
	1561	+ struct mem_cgroup *parent_mem = NULL;
	1562	+
	1563	+ if (parent)
	1564	+ parent_mem = mem_cgroup_from_cont(parent);
	1565	+
	1566	+ cgroup_lock();
	1567	+ /*
	1568	+ * If parent's use_hiearchy is set, we can't make any modifications
	1569	+ * in the child subtrees. If it is unset, then the change can
	1570	+ * occur, provided the current cgroup has no children.
	1571	+ *
	1572	+ * For the root cgroup, parent_mem is NULL, we allow value to be
	1573	+ * set if there are no children.
	1574	+ */
	1575	+ if ((!parent_mem \|\| !parent_mem->use_hierarchy) &&
	1576	+ (val == 1 \|\| val == 0)) {
	1577	+ if (list_empty(&cont->children))
	1578	+ mem->use_hierarchy = val;
	1579	+ else
	1580	+ retval = -EBUSY;
	1581	+ } else
	1582	+ retval = -EINVAL;
	1583	+ cgroup_unlock();
	1584	+
	1585	+ return retval;
	1586	+}
	1587	+
1546	1588	static u64 mem_cgroup_read(struct cgroup cont, struct cftype cft)
1547	1589	{
1548	1590	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
...	...	@@ -1706,6 +1748,11 @@
1706	1748	.name = "force_empty",
1707	1749	.trigger = mem_cgroup_force_empty_write,
1708	1750	},
	1751	+ {
	1752	+ .name = "use_hierarchy",
	1753	+ .write_u64 = mem_cgroup_hierarchy_write,
	1754	+ .read_u64 = mem_cgroup_hierarchy_read,
	1755	+ },
1709	1756	};
1710	1757
1711	1758	#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
1712	1759
1713	1760
...	...	@@ -1881,12 +1928,18 @@
1881	1928	if (cont->parent == NULL) {
1882	1929	enable_swap_cgroup();
1883	1930	parent = NULL;
1884		- } else
	1931	+ } else {
1885	1932	parent = mem_cgroup_from_cont(cont->parent);
	1933	+ mem->use_hierarchy = parent->use_hierarchy;
	1934	+ }
1886	1935
1887		- res_counter_init(&mem->res, parent ? &parent->res : NULL);
1888		- res_counter_init(&mem->memsw, parent ? &parent->memsw : NULL);
1889		-
	1936	+ if (parent && parent->use_hierarchy) {
	1937	+ res_counter_init(&mem->res, &parent->res);
	1938	+ res_counter_init(&mem->memsw, &parent->memsw);
	1939	+ } else {
	1940	+ res_counter_init(&mem->res, NULL);
	1941	+ res_counter_init(&mem->memsw, NULL);
	1942	+ }
1890	1943
1891	1944	mem->last_scanned_child = NULL;
1892	1945