memcgroup: use vmalloc for mem_cgroup allocation

On ia64, this kmalloc() requires order-4 pages.  But this is not necessary to
be physically contiguous.  For big mem_cgroup, vmalloc is better.  For small
ones, kmalloc is used.

[akpm@linux-foundation.org: simplification]
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -31,6 +31,7 @@
 #include <linux/spinlock.h>
 #include <linux/fs.h>
 #include <linux/seq_file.h>
+#include <linux/vmalloc.h>
 
 #include <asm/uaccess.h>
 
@@ -983,6 +984,29 @@ static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
 	kfree(mem->info.nodeinfo[node]);
 }
 
+static struct mem_cgroup *mem_cgroup_alloc(void)
+{
+	struct mem_cgroup *mem;
+
+	if (sizeof(*mem) < PAGE_SIZE)
+		mem = kmalloc(sizeof(*mem), GFP_KERNEL);
+	else
+		mem = vmalloc(sizeof(*mem));
+
+	if (mem)
+		memset(mem, 0, sizeof(*mem));
+	return mem;
+}
+
+static void mem_cgroup_free(struct mem_cgroup *mem)
+{
+	if (sizeof(*mem) < PAGE_SIZE)
+		kfree(mem);
+	else
+		vfree(mem);
+}
+
+
 static struct cgroup_subsys_state *
 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 {
@@ -993,12 +1017,11 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 		mem = &init_mem_cgroup;
 		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
 	} else {
-		mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
+		mem = mem_cgroup_alloc();
+		if (!mem)
+			return ERR_PTR(-ENOMEM);
 	}
 
-	if (mem == NULL)
-		return ERR_PTR(-ENOMEM);
-
 	res_counter_init(&mem->res);
 
 	memset(&mem->info, 0, sizeof(mem->info));
@@ -1012,7 +1035,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	for_each_node_state(node, N_POSSIBLE)
 		free_mem_cgroup_per_zone_info(mem, node);
 	if (cont->parent != NULL)
-		kfree(mem);
+		mem_cgroup_free(mem);
 	return ERR_PTR(-ENOMEM);
 }
 
@@ -1032,7 +1055,7 @@ static void mem_cgroup_destroy(struct cgroup_subsys *ss,
 	for_each_node_state(node, N_POSSIBLE)
 		free_mem_cgroup_per_zone_info(mem, node);
 
-	kfree(mem_cgroup_from_cont(cont));
+	mem_cgroup_free(mem_cgroup_from_cont(cont));
 }
 
 static int mem_cgroup_populate(struct cgroup_subsys *ss,