[PATCH v5 07/10] Display current tcp memory allocation in kmem cgroup

[Glauber Costa <glommer@parallels.com>]

This patch introduces kmem.tcp.usage_in_bytes file, living in the
kmem_cgroup filesystem. It is a simple read-only file that displays the
amount of kernel memory currently consumed by the cgroup.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: David S. Miller <davem@davemloft.net>
CC: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
---
 Documentation/cgroups/memory.txt |    1 +
 mm/memcontrol.c                  |   14 +++++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index c1db134..00f1a88 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -79,6 +79,7 @@ Brief summary of control files.
  memory.independent_kmem_limit	 # select whether or not kernel memory limits are
 				   independent of user limits
  memory.kmem.tcp.limit_in_bytes  # set/show hard limit for tcp buf memory
+ memory.kmem.tcp.usage_in_bytes  # show current tcp buf memory allocation
 
 1. History
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ee122a6..51b5a55 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -528,6 +528,11 @@ static struct cftype tcp_files[] = {
 		.read_u64 = mem_cgroup_read,
 		.private = MEMFILE_PRIVATE(_KMEM_TCP, RES_LIMIT),
 	},
+	{
+		.name = "kmem.tcp.usage_in_bytes",
+		.read_u64 = mem_cgroup_read,
+		.private = MEMFILE_PRIVATE(_KMEM_TCP, RES_USAGE),
+	},
 };
 
 static void tcp_create_cgroup(struct mem_cgroup *cg, struct cgroup_subsys *ss)
@@ -4126,9 +4131,12 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 #if defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM) && defined(CONFIG_INET)
 	case _KMEM_TCP:
 		/* Be explicit: tcp root does not have a res_counter */
-		if (mem_cgroup_is_root(mem))
-			val = RESOURCE_MAX;
-		else
+		if (mem_cgroup_is_root(mem)) {
+			if (name == RES_USAGE)
+				val = atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT;
+			else
+				val = RESOURCE_MAX;
+		} else
 			val = res_counter_read_u64(&mem->tcp.tcp_memory_allocated, name);
 		break;
 #endif
-- 
1.7.6.4

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