Disable cgroups memory controller, unless explicitly enabled

This should result in very low run-time overhead, though this is yet
to be measured.

svn path=/dists/trunk/linux-2.6/; revision=17394

debian/config/config

@@ -3404,6 +3404,7 @@ CONFIG_PROC_PID_CPUSET=y
 CONFIG_CGROUP_CPUACCT=y
 CONFIG_RESOURCE_COUNTERS=y
 CONFIG_CGROUP_MEM_RES_CTLR=y
+CONFIG_CGROUP_MEM_RES_CTLR_DISABLED=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_FAIR_GROUP_SCHED=y
 # CONFIG_RT_GROUP_SCHED is not set

debian/patches/debian/cgroups-Document-the-Debian-memory-resource-controll.patch

@@ -0,0 +1,28 @@
+From 969e4dd0b5c715b239c765b870f2abf81c57e878 Mon Sep 17 00:00:00 2001
+From: Ben Hutchings <ben@decadent.org.uk>
+Date: Sun, 30 May 2010 22:47:01 +0100
+Subject: [PATCH 2/2] cgroups: Document the Debian memory resource controller
+ config change
+
+---
+ Documentation/cgroups/memory.txt |    4 ++++
+ 1 files changed, 4 insertions(+), 0 deletions(-)
+
+diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
+index 7c16347..684f70d 100644
+--- a/Documentation/cgroups/memory.txt
++++ b/Documentation/cgroups/memory.txt
+@@ -47,6 +47,10 @@ Features:
+  Kernel memory and Hugepages are not under control yet. We just manage
+  pages on LRU. To add more controls, we have to take care of performance.
+ 
++NOTE: In Debian kernel packages, the memory resource controller is
++included but disabled by default.  Use the kernel parameter
++'cgroup_enable=memory' to enable it.
++
+ Brief summary of control files.
+ 
+  tasks				 # attach a task(thread) and show list of threads
+-- 
+1.7.4.4
+

debian/patches/features/all/cgroups-Allow-memory-cgroup-support-to-be-included-b.patch

@@ -0,0 +1,115 @@
+From: Ben Hutchings <ben@decadent.org.uk>
+Date: Sun, 30 May 2010 22:43:38 +0100
+Subject: [PATCH 1/2] cgroups: Allow memory cgroup support to be included but
+ disabled
+
+Memory cgroup support has some run-time overhead, so it's useful to
+include it in a distribution kernel without enabling it by default.
+Add a kernel config option to disable it by default and a kernel
+parameter 'cgroup_enable' as the opposite to 'cgroup_disable'.
+
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ Documentation/kernel-parameters.txt |    4 ++--
+ init/Kconfig                        |    8 ++++++++
+ kernel/cgroup.c                     |   20 ++++++++++++++++----
+ mm/memcontrol.c                     |    3 +++
+ 4 files changed, 29 insertions(+), 6 deletions(-)
+
+diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
+index cc85a92..38e0b44 100644
+--- a/Documentation/kernel-parameters.txt
++++ b/Documentation/kernel-parameters.txt
+@@ -425,8 +425,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
+ 	ccw_timeout_log [S390]
+ 			See Documentation/s390/CommonIO for details.
+ 
+-	cgroup_disable= [KNL] Disable a particular controller
+-			Format: {name of the controller(s) to disable}
++	cgroup_disable= [KNL] Disable/enable a particular controller
++	cgroup_enable=	Format: {name of the controller(s) to disable/enable}
+ 				{Currently supported controllers - "memory"}
+ 
+ 	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
+diff --git a/init/Kconfig b/init/Kconfig
+index d886b1e..3410369 100644
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -659,6 +659,14 @@ config CGROUP_MEM_RES_CTLR
+ 	  This config option also selects MM_OWNER config option, which
+ 	  could in turn add some fork/exit overhead.
+ 
++config CGROUP_MEM_RES_CTLR_DISABLED
++	bool "Memory Resource Controller disabled by default"
++	depends on CGROUP_MEM_RES_CTLR
++	default n
++	help
++	  Disable the memory group resource controller unless explicitly
++	  enabled using the kernel parameter "cgroup_enable=memory".
++
+ config CGROUP_MEM_RES_CTLR_SWAP
+ 	bool "Memory Resource Controller Swap Extension"
+ 	depends on CGROUP_MEM_RES_CTLR && SWAP
+diff --git a/kernel/cgroup.c b/kernel/cgroup.c
+index 25c7eb5..b3c5aa7 100644
+--- a/kernel/cgroup.c
++++ b/kernel/cgroup.c
+@@ -4526,7 +4526,7 @@ static void cgroup_release_agent(struct work_struct *work)
+ 	mutex_unlock(&cgroup_mutex);
+ }
+ 
+-static int __init cgroup_disable(char *str)
++static int __init cgroup_set_disabled(char *str, int value)
+ {
+ 	int i;
+ 	char *token;
+@@ -4542,17 +4542,29 @@ static int __init cgroup_disable(char *str)
+ 			struct cgroup_subsys *ss = subsys[i];
+ 
+ 			if (!strcmp(token, ss->name)) {
+-				ss->disabled = 1;
+-				printk(KERN_INFO "Disabling %s control group"
+-					" subsystem\n", ss->name);
++				ss->disabled = value;
++				printk(KERN_INFO
++				       "%sabling %s control group subsystem\n",
++				       value ? "Dis" : "En", ss->name);
+ 				break;
+ 			}
+ 		}
+ 	}
+ 	return 1;
+ }
++
++static int __init cgroup_disable(char *str)
++{
++	return cgroup_set_disabled(str, 1);
++}
+ __setup("cgroup_disable=", cgroup_disable);
+ 
++static int __init cgroup_enable(char *str)
++{
++	return cgroup_set_disabled(str, 0);
++}
++__setup("cgroup_enable=", cgroup_enable);
++
+ /*
+  * Functons for CSS ID.
+  */
+diff --git a/mm/memcontrol.c b/mm/memcontrol.c
+index 010f916..f660a07 100644
+--- a/mm/memcontrol.c
++++ b/mm/memcontrol.c
+@@ -5153,6 +5153,9 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
+ 
+ struct cgroup_subsys mem_cgroup_subsys = {
+ 	.name = "memory",
++#ifdef CONFIG_CGROUP_MEM_RES_CTLR_DISABLED
++	.disabled = 1,
++#endif
+ 	.subsys_id = mem_cgroup_subsys_id,
+ 	.create = mem_cgroup_create,
+ 	.pre_destroy = mem_cgroup_pre_destroy,
+-- 
+1.7.4.4
+

debian/patches/series/1~experimental.2

@@ -0,0 +1,2 @@
++ features/all/cgroups-Allow-memory-cgroup-support-to-be-included-b.patch
++ debian/cgroups-Document-the-Debian-memory-resource-controll.patch