From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 18 Sep 2017 11:01:46 +0000 (+0100)
Subject: cgroup: Add kernel param to enable memory group
X-Git-Tag: archive/raspbian/4.9.51-1+rpi1~5^2~146
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=6ba190e3360655eccac9a28a947c6e6713485275;p=linux-4.9.git

cgroup: Add kernel param to enable memory group

cgroup support is useful, but enabling the "memory" cgroup has a 32-byte
overhead per page. Arrange that "memory" cgroup is disabled by default
unless the "cgroup_memory" parameter is set to a true value.

See: https://github.com/raspberrypi/issues/1950

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2c785f957024..c3f5abf0fd7a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5638,6 +5638,8 @@ int __init cgroup_init_early(void)
 }
 
 static u16 cgroup_disable_mask __initdata;
+static bool cgroup_enable_memory;
+static int __init cgroup_disable(char *str);
 
 /**
  * cgroup_init - cgroup initialization
@@ -5676,6 +5678,9 @@ int __init cgroup_init(void)
 
 	mutex_unlock(&cgroup_mutex);
 
+	if (!cgroup_enable_memory)
+		cgroup_disable("memory");
+
 	for_each_subsys(ss, ssid) {
 		if (ss->early_init) {
 			struct cgroup_subsys_state *css =
@@ -6151,6 +6156,13 @@ static int __init cgroup_disable(char *str)
 }
 __setup("cgroup_disable=", cgroup_disable);
 
+static int __init cgroup_memory(char *str)
+{
+	kstrtobool(str, &cgroup_enable_memory);
+	return 1;
+}
+__setup("cgroup_memory=", cgroup_memory);
+
 static int __init cgroup_no_v1(char *str)
 {
 	struct cgroup_subsys *ss;