[PATCHSET] cgroup: reorganize cgroup source files

[PATCHSET] cgroup: reorganize cgroup source files

[Tejun Heo]

cgroup source files are getting a bit too unwieldy.  Let's reorganize
them.

* Move cgroup files in kernel to kernel/cgroup.

* Split cgroup.c into multiple files.

The only functional change this patchset causes is loss of a
WARN_ON(); otherwise, everything remains identical.

This patchset contains the following eight patches.

 0001-cgroup-reorder-css_set-fields.patch
 0002-cgroup-move-cgroup-files-under-kernel-cgroup.patch
 0003-cgroup-move-cgroup-v1-specific-code-to-kernel-cgroup.patch
 0004-cgroup-refactor-mount-path-and-clearly-distinguish-v.patch
 0005-cgroup-separate-out-cgroup1_kf_syscall_ops.patch
 0006-cgroup-move-v1-mount-functions-to-kernel-cgroup-cgro.patch
 0007-cgroup-rename-functions-for-consistency.patch
 0008-cgroup-move-namespace-code-to-kernel-cgroup-namespac.patch

The patchset is available in the following git branch

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup-reorg

and on top of the following git branch

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup2-procs

diffstat follows.  Thanks.

 include/linux/cgroup-defs.h     |   54 -
 kernel/Makefile                 |    5 
 kernel/cgroup/Makefile          |    5 
 kernel/cgroup/cgroup-internal.h |  155 +++
 kernel/cgroup/cgroup-v1.c       | 1395 ++++++++++++++++++++++++++++
 kernel/cgroup/cgroup.c          | 1940 +++-------------------------------------
 kernel/cgroup/namespace.c       |  155 +++
 7 files changed, 1907 insertions(+), 1802 deletions(-)

--
tejun

[PATCH 1/8] cgroup: reorder css_set fields

[Tejun Heo]

Reorder css_set fields so that they're roughly in the order of how hot
they are.  The rough order is

1. the actual csses
2. reference counter and the default cgroup pointer.
3. task lists and iterations
4. fields used during merge including css_set lookup
5. the rest

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 include/linux/cgroup-defs.h | 54 ++++++++++++++++++++++-----------------------
 kernel/cgroup.c             | 13 ++++++-----
 2 files changed, 35 insertions(+), 32 deletions(-)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 8a916dc..3c02404 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -148,14 +148,18 @@ struct cgroup_subsys_state {
  * set for a task.
  */
 struct css_set {
-	/* Reference count */
-	atomic_t refcount;
-
 	/*
-	 * List running through all cgroup groups in the same hash
-	 * slot. Protected by css_set_lock
+	 * Set of subsystem states, one for each subsystem. This array is
+	 * immutable after creation apart from the init_css_set during
+	 * subsystem registration (at boot time).
 	 */
-	struct hlist_node hlist;
+	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+	/* reference count */
+	atomic_t refcount;
+
+	/* the default cgroup associated with this css_set */
+	struct cgroup *dfl_cgrp;
 
 	/*
 	 * Lists running through all tasks using this cgroup group.
@@ -167,21 +171,29 @@ struct css_set {
 	struct list_head tasks;
 	struct list_head mg_tasks;
 
+	/* all css_task_iters currently walking this cset */
+	struct list_head task_iters;
+
 	/*
-	 * List of cgrp_cset_links pointing at cgroups referenced from this
-	 * css_set.  Protected by css_set_lock.
+	 * On the default hierarhcy, ->subsys[ssid] may point to a css
+	 * attached to an ancestor instead of the cgroup this css_set is
+	 * associated with.  The following node is anchored at
+	 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
+	 * iterate through all css's attached to a given cgroup.
 	 */
-	struct list_head cgrp_links;
+	struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
 
-	/* the default cgroup associated with this css_set */
-	struct cgroup *dfl_cgrp;
+	/*
+	 * List running through all cgroup groups in the same hash
+	 * slot. Protected by css_set_lock
+	 */
+	struct hlist_node hlist;
 
 	/*
-	 * Set of subsystem states, one for each subsystem. This array is
-	 * immutable after creation apart from the init_css_set during
-	 * subsystem registration (at boot time).
+	 * List of cgrp_cset_links pointing at cgroups referenced from this
+	 * css_set.  Protected by css_set_lock.
 	 */
-	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+	struct list_head cgrp_links;
 
 	/*
 	 * List of csets participating in the on-going migration either as
@@ -201,18 +213,6 @@ struct css_set {
 	struct cgroup *mg_dst_cgrp;
 	struct css_set *mg_dst_cset;
 
-	/*
-	 * On the default hierarhcy, ->subsys[ssid] may point to a css
-	 * attached to an ancestor instead of the cgroup this css_set is
-	 * associated with.  The following node is anchored at
-	 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
-	 * iterate through all css's attached to a given cgroup.
-	 */
-	struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
-
-	/* all css_task_iters currently walking this cset */
-	struct list_head task_iters;
-
 	/* dead and being drained, ignore for migration */
 	bool dead;
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b9e2d85..1a815f2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -647,12 +647,12 @@ struct cgrp_cset_link {
  */
 struct css_set init_css_set = {
 	.refcount		= ATOMIC_INIT(1),
-	.cgrp_links		= LIST_HEAD_INIT(init_css_set.cgrp_links),
 	.tasks			= LIST_HEAD_INIT(init_css_set.tasks),
 	.mg_tasks		= LIST_HEAD_INIT(init_css_set.mg_tasks),
+	.task_iters		= LIST_HEAD_INIT(init_css_set.task_iters),
+	.cgrp_links		= LIST_HEAD_INIT(init_css_set.cgrp_links),
 	.mg_preload_node	= LIST_HEAD_INIT(init_css_set.mg_preload_node),
 	.mg_node		= LIST_HEAD_INIT(init_css_set.mg_node),
-	.task_iters		= LIST_HEAD_INIT(init_css_set.task_iters),
 };
 
 static int css_set_count	= 1;	/* 1 for init_css_set */
@@ -1095,13 +1095,13 @@ static struct css_set *find_css_set(struct css_set *old_cset,
 	}
 
 	atomic_set(&cset->refcount, 1);
-	INIT_LIST_HEAD(&cset->cgrp_links);
 	INIT_LIST_HEAD(&cset->tasks);
 	INIT_LIST_HEAD(&cset->mg_tasks);
-	INIT_LIST_HEAD(&cset->mg_preload_node);
-	INIT_LIST_HEAD(&cset->mg_node);
 	INIT_LIST_HEAD(&cset->task_iters);
 	INIT_HLIST_NODE(&cset->hlist);
+	INIT_LIST_HEAD(&cset->cgrp_links);
+	INIT_LIST_HEAD(&cset->mg_preload_node);
+	INIT_LIST_HEAD(&cset->mg_node);
 
 	/* Copy the set of subsystem state objects generated in
 	 * find_existing_css_set() */
@@ -4384,6 +4384,9 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
 	struct task_struct *task;
 	int ret;
 
+	if (cgroup_on_dfl(to))
+		return -EINVAL;
+
 	if (!cgroup_may_migrate_to(to))
 		return -EBUSY;
 
-- 
2.9.3

[PATCH 2/8] cgroup: move cgroup files under kernel/cgroup/

[Tejun Heo]

They're growing to be too many and planned to get split further.  Move
them under their own directory.

 kernel/cgroup.c		-> kernel/cgroup/cgroup.c
 kernel/cgroup_freezer.c	-> kernel/cgroup/freezer.c
 kernel/cgroup_pids.c		-> kernel/cgroup/pids.c
 kernel/cpuset.c		-> kernel/cgroup/cpuset.c

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/Makefile                               | 5 +----
 kernel/cgroup/Makefile                        | 5 +++++
 kernel/{ => cgroup}/cgroup.c                  | 0
 kernel/{ => cgroup}/cpuset.c                  | 0
 kernel/{cgroup_freezer.c => cgroup/freezer.c} | 0
 kernel/{cgroup_pids.c => cgroup/pids.c}       | 0
 6 files changed, 6 insertions(+), 4 deletions(-)
 create mode 100644 kernel/cgroup/Makefile
 rename kernel/{ => cgroup}/cgroup.c (100%)
 rename kernel/{ => cgroup}/cpuset.c (100%)
 rename kernel/{cgroup_freezer.c => cgroup/freezer.c} (100%)
 rename kernel/{cgroup_pids.c => cgroup/pids.c} (100%)

diff --git a/kernel/Makefile b/kernel/Makefile
index 12c679f..b302b47 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -64,10 +64,7 @@ obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
-obj-$(CONFIG_CGROUPS) += cgroup.o
-obj-$(CONFIG_CGROUP_FREEZER) += cgroup_freezer.o
-obj-$(CONFIG_CGROUP_PIDS) += cgroup_pids.o
-obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CGROUPS) += cgroup/
 obj-$(CONFIG_UTS_NS) += utsname.o
 obj-$(CONFIG_USER_NS) += user_namespace.o
 obj-$(CONFIG_PID_NS) += pid_namespace.o
diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
new file mode 100644
index 0000000..4d561a5
--- /dev/null
+++ b/kernel/cgroup/Makefile
@@ -0,0 +1,5 @@
+obj-y := cgroup.o
+
+obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
+obj-$(CONFIG_CGROUP_PIDS) += pids.o
+obj-$(CONFIG_CPUSETS) += cpuset.o
diff --git a/kernel/cgroup.c b/kernel/cgroup/cgroup.c
similarity index 100%
rename from kernel/cgroup.c
rename to kernel/cgroup/cgroup.c
diff --git a/kernel/cpuset.c b/kernel/cgroup/cpuset.c
similarity index 100%
rename from kernel/cpuset.c
rename to kernel/cgroup/cpuset.c
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup/freezer.c
similarity index 100%
rename from kernel/cgroup_freezer.c
rename to kernel/cgroup/freezer.c
diff --git a/kernel/cgroup_pids.c b/kernel/cgroup/pids.c
similarity index 100%
rename from kernel/cgroup_pids.c
rename to kernel/cgroup/pids.c
-- 
2.9.3

[PATCH 6/8] cgroup: move v1 mount functions to kernel/cgroup/cgroup-v1.c

[Tejun Heo]

Now that the v1 mount code is split into separate functions, move them
to kernel/cgroup/cgroup-v1.c along with the mount option handling
code.  As this puts all v1-only kernfs_syscall_ops in cgroup-v1.c,
move cgroup1_kf_syscall_ops to cgroup-v1.c too.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/cgroup/cgroup-internal.h |  28 ++-
 kernel/cgroup/cgroup-v1.c       | 381 ++++++++++++++++++++++++++++++++++++-
 kernel/cgroup/cgroup.c          | 410 +---------------------------------------
 3 files changed, 413 insertions(+), 406 deletions(-)

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 7b8182e..3d431b6 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -26,6 +26,16 @@ struct cgrp_cset_link {
 	struct list_head	cgrp_link;
 };
 
+struct cgroup_sb_opts {
+	u16 subsys_mask;
+	unsigned int flags;
+	char *release_agent;
+	bool cpuset_clone_children;
+	char *name;
+	/* User explicitly requested empty subsystem */
+	bool none;
+};
+
 extern struct cgroup_subsys *cgroup_subsys[];
 extern struct list_head cgroup_roots;
 extern struct file_system_type cgroup_fs_type;
@@ -64,7 +74,13 @@ void cgroup_kn_unlock(struct kernfs_node *kn);
 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
 			  struct cgroup_namespace *ns);
 
+void cgroup_free_root(struct cgroup_root *root);
+void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
+			       struct cgroup_root *root, unsigned long magic,
+			       struct cgroup_namespace *ns);
 
 bool cgroup_may_migrate_to(struct cgroup *dst_cgrp);
 void cgroup_migrate_finish(struct list_head *preloaded_csets);
@@ -84,18 +100,24 @@ ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes
 
 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
+int cgroup_rmdir(struct kernfs_node *kn);
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+		     struct kernfs_root *kf_root);
+
 /*
  * cgroup-v1.c
  */
-extern spinlock_t release_agent_path_lock;
 extern struct cftype cgroup_legacy_base_files[];
 extern const struct file_operations proc_cgroupstats_operations;
+extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 
 bool cgroup_ssid_no_v1(int ssid);
 void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
-int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-		   const char *new_name_str);
 void cgroup_release_agent(struct work_struct *work);
 void check_for_release(struct cgroup *cgrp);
+struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
+			     void *data, unsigned long magic,
+			     struct cgroup_namespace *ns);
 
 #endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 0b2c24f..ae240c0 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -1,7 +1,9 @@
 #include "cgroup-internal.h"
 
+#include <linux/ctype.h>
 #include <linux/kmod.h>
 #include <linux/sort.h>
+#include <linux/delay.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
@@ -32,7 +34,7 @@ static struct workqueue_struct *cgroup_pidlist_destroy_wq;
  * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
  * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
  */
-DEFINE_SPINLOCK(release_agent_path_lock);
+static DEFINE_SPINLOCK(release_agent_path_lock);
 
 bool cgroup_ssid_no_v1(int ssid)
 {
@@ -800,8 +802,8 @@ void cgroup_release_agent(struct work_struct *work)
 /*
  * cgroup_rename - Only allow simple rename of directories in place.
  */
-int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-		   const char *new_name_str)
+static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+			  const char *new_name_str)
 {
 	struct cgroup *cgrp = kn->priv;
 	int ret;
@@ -832,6 +834,379 @@ int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
 	return ret;
 }
 
+static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+{
+	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+	struct cgroup_subsys *ss;
+	int ssid;
+
+	for_each_subsys(ss, ssid)
+		if (root->subsys_mask & (1 << ssid))
+			seq_show_option(seq, ss->legacy_name, NULL);
+	if (root->flags & CGRP_ROOT_NOPREFIX)
+		seq_puts(seq, ",noprefix");
+	if (root->flags & CGRP_ROOT_XATTR)
+		seq_puts(seq, ",xattr");
+
+	spin_lock(&release_agent_path_lock);
+	if (strlen(root->release_agent_path))
+		seq_show_option(seq, "release_agent",
+				root->release_agent_path);
+	spin_unlock(&release_agent_path_lock);
+
+	if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+		seq_puts(seq, ",clone_children");
+	if (strlen(root->name))
+		seq_show_option(seq, "name", root->name);
+	return 0;
+}
+
+static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
+{
+	char *token, *o = data;
+	bool all_ss = false, one_ss = false;
+	u16 mask = U16_MAX;
+	struct cgroup_subsys *ss;
+	int nr_opts = 0;
+	int i;
+
+#ifdef CONFIG_CPUSETS
+	mask = ~((u16)1 << cpuset_cgrp_id);
+#endif
+
+	memset(opts, 0, sizeof(*opts));
+
+	while ((token = strsep(&o, ",")) != NULL) {
+		nr_opts++;
+
+		if (!*token)
+			return -EINVAL;
+		if (!strcmp(token, "none")) {
+			/* Explicitly have no subsystems */
+			opts->none = true;
+			continue;
+		}
+		if (!strcmp(token, "all")) {
+			/* Mutually exclusive option 'all' + subsystem name */
+			if (one_ss)
+				return -EINVAL;
+			all_ss = true;
+			continue;
+		}
+		if (!strcmp(token, "noprefix")) {
+			opts->flags |= CGRP_ROOT_NOPREFIX;
+			continue;
+		}
+		if (!strcmp(token, "clone_children")) {
+			opts->cpuset_clone_children = true;
+			continue;
+		}
+		if (!strcmp(token, "xattr")) {
+			opts->flags |= CGRP_ROOT_XATTR;
+			continue;
+		}
+		if (!strncmp(token, "release_agent=", 14)) {
+			/* Specifying two release agents is forbidden */
+			if (opts->release_agent)
+				return -EINVAL;
+			opts->release_agent =
+				kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
+			if (!opts->release_agent)
+				return -ENOMEM;
+			continue;
+		}
+		if (!strncmp(token, "name=", 5)) {
+			const char *name = token + 5;
+			/* Can't specify an empty name */
+			if (!strlen(name))
+				return -EINVAL;
+			/* Must match [\w.-]+ */
+			for (i = 0; i < strlen(name); i++) {
+				char c = name[i];
+				if (isalnum(c))
+					continue;
+				if ((c == '.') || (c == '-') || (c == '_'))
+					continue;
+				return -EINVAL;
+			}
+			/* Specifying two names is forbidden */
+			if (opts->name)
+				return -EINVAL;
+			opts->name = kstrndup(name,
+					      MAX_CGROUP_ROOT_NAMELEN - 1,
+					      GFP_KERNEL);
+			if (!opts->name)
+				return -ENOMEM;
+
+			continue;
+		}
+
+		for_each_subsys(ss, i) {
+			if (strcmp(token, ss->legacy_name))
+				continue;
+			if (!cgroup_ssid_enabled(i))
+				continue;
+			if (cgroup_ssid_no_v1(i))
+				continue;
+
+			/* Mutually exclusive option 'all' + subsystem name */
+			if (all_ss)
+				return -EINVAL;
+			opts->subsys_mask |= (1 << i);
+			one_ss = true;
+
+			break;
+		}
+		if (i == CGROUP_SUBSYS_COUNT)
+			return -ENOENT;
+	}
+
+	/*
+	 * If the 'all' option was specified select all the subsystems,
+	 * otherwise if 'none', 'name=' and a subsystem name options were
+	 * not specified, let's default to 'all'
+	 */
+	if (all_ss || (!one_ss && !opts->none && !opts->name))
+		for_each_subsys(ss, i)
+			if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
+				opts->subsys_mask |= (1 << i);
+
+	/*
+	 * We either have to specify by name or by subsystems. (So all
+	 * empty hierarchies must have a name).
+	 */
+	if (!opts->subsys_mask && !opts->name)
+		return -EINVAL;
+
+	/*
+	 * Option noprefix was introduced just for backward compatibility
+	 * with the old cpuset, so we allow noprefix only if mounting just
+	 * the cpuset subsystem.
+	 */
+	if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
+		return -EINVAL;
+
+	/* Can't specify "none" and some subsystems */
+	if (opts->subsys_mask && opts->none)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+	int ret = 0;
+	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+	struct cgroup_sb_opts opts;
+	u16 added_mask, removed_mask;
+
+	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+	/* See what subsystems are wanted */
+	ret = parse_cgroupfs_options(data, &opts);
+	if (ret)
+		goto out_unlock;
+
+	if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
+		pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
+			task_tgid_nr(current), current->comm);
+
+	added_mask = opts.subsys_mask & ~root->subsys_mask;
+	removed_mask = root->subsys_mask & ~opts.subsys_mask;
+
+	/* Don't allow flags or name to change at remount */
+	if ((opts.flags ^ root->flags) ||
+	    (opts.name && strcmp(opts.name, root->name))) {
+		pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
+		       opts.flags, opts.name ?: "", root->flags, root->name);
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	/* remounting is not allowed for populated hierarchies */
+	if (!list_empty(&root->cgrp.self.children)) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	ret = rebind_subsystems(root, added_mask);
+	if (ret)
+		goto out_unlock;
+
+	WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
+
+	if (opts.release_agent) {
+		spin_lock(&release_agent_path_lock);
+		strcpy(root->release_agent_path, opts.release_agent);
+		spin_unlock(&release_agent_path_lock);
+	}
+
+	trace_cgroup_remount(root);
+
+ out_unlock:
+	kfree(opts.release_agent);
+	kfree(opts.name);
+	mutex_unlock(&cgroup_mutex);
+	return ret;
+}
+
+struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
+	.rename			= cgroup1_rename,
+	.show_options		= cgroup1_show_options,
+	.remount_fs		= cgroup1_remount,
+	.mkdir			= cgroup_mkdir,
+	.rmdir			= cgroup_rmdir,
+	.show_path		= cgroup_show_path,
+};
+
+struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
+			     void *data, unsigned long magic,
+			     struct cgroup_namespace *ns)
+{
+	struct super_block *pinned_sb = NULL;
+	struct cgroup_sb_opts opts;
+	struct cgroup_root *root;
+	struct cgroup_subsys *ss;
+	struct dentry *dentry;
+	int i, ret;
+
+	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+	/* First find the desired set of subsystems */
+	ret = parse_cgroupfs_options(data, &opts);
+	if (ret)
+		goto out_unlock;
+
+	/*
+	 * Destruction of cgroup root is asynchronous, so subsystems may
+	 * still be dying after the previous unmount.  Let's drain the
+	 * dying subsystems.  We just need to ensure that the ones
+	 * unmounted previously finish dying and don't care about new ones
+	 * starting.  Testing ref liveliness is good enough.
+	 */
+	for_each_subsys(ss, i) {
+		if (!(opts.subsys_mask & (1 << i)) ||
+		    ss->root == &cgrp_dfl_root)
+			continue;
+
+		if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
+			mutex_unlock(&cgroup_mutex);
+			msleep(10);
+			ret = restart_syscall();
+			goto out_free;
+		}
+		cgroup_put(&ss->root->cgrp);
+	}
+
+	for_each_root(root) {
+		bool name_match = false;
+
+		if (root == &cgrp_dfl_root)
+			continue;
+
+		/*
+		 * If we asked for a name then it must match.  Also, if
+		 * name matches but sybsys_mask doesn't, we should fail.
+		 * Remember whether name matched.
+		 */
+		if (opts.name) {
+			if (strcmp(opts.name, root->name))
+				continue;
+			name_match = true;
+		}
+
+		/*
+		 * If we asked for subsystems (or explicitly for no
+		 * subsystems) then they must match.
+		 */
+		if ((opts.subsys_mask || opts.none) &&
+		    (opts.subsys_mask != root->subsys_mask)) {
+			if (!name_match)
+				continue;
+			ret = -EBUSY;
+			goto out_unlock;
+		}
+
+		if (root->flags ^ opts.flags)
+			pr_warn("new mount options do not match the existing superblock, will be ignored\n");
+
+		/*
+		 * We want to reuse @root whose lifetime is governed by its
+		 * ->cgrp.  Let's check whether @root is alive and keep it
+		 * that way.  As cgroup_kill_sb() can happen anytime, we
+		 * want to block it by pinning the sb so that @root doesn't
+		 * get killed before mount is complete.
+		 *
+		 * With the sb pinned, tryget_live can reliably indicate
+		 * whether @root can be reused.  If it's being killed,
+		 * drain it.  We can use wait_queue for the wait but this
+		 * path is super cold.  Let's just sleep a bit and retry.
+		 */
+		pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
+		if (IS_ERR(pinned_sb) ||
+		    !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
+			mutex_unlock(&cgroup_mutex);
+			if (!IS_ERR_OR_NULL(pinned_sb))
+				deactivate_super(pinned_sb);
+			msleep(10);
+			ret = restart_syscall();
+			goto out_free;
+		}
+
+		ret = 0;
+		goto out_unlock;
+	}
+
+	/*
+	 * No such thing, create a new one.  name= matching without subsys
+	 * specification is allowed for already existing hierarchies but we
+	 * can't create new one without subsys specification.
+	 */
+	if (!opts.subsys_mask && !opts.none) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	/* Hierarchies may only be created in the initial cgroup namespace. */
+	if (ns != &init_cgroup_ns) {
+		ret = -EPERM;
+		goto out_unlock;
+	}
+
+	root = kzalloc(sizeof(*root), GFP_KERNEL);
+	if (!root) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	init_cgroup_root(root, &opts);
+
+	ret = cgroup_setup_root(root, opts.subsys_mask);
+	if (ret)
+		cgroup_free_root(root);
+
+out_unlock:
+	mutex_unlock(&cgroup_mutex);
+out_free:
+	kfree(opts.release_agent);
+	kfree(opts.name);
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
+				 CGROUP_SUPER_MAGIC, ns);
+
+	/*
+	 * If @pinned_sb, we're reusing an existing root and holding an
+	 * extra ref on its sb.  Mount is complete.  Put the extra ref.
+	 */
+	if (pinned_sb)
+		deactivate_super(pinned_sb);
+
+	return dentry;
+}
+
 static int __init cgroup1_wq_init(void)
 {
 	/*
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index f1b71fb..ae25f14 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -31,7 +31,6 @@
 #include "cgroup-internal.h"
 
 #include <linux/cred.h>
-#include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/init_task.h>
 #include <linux/kernel.h>
@@ -49,7 +48,6 @@
 #include <linux/hashtable.h>
 #include <linux/idr.h>
 #include <linux/kthread.h>
-#include <linux/delay.h>
 #include <linux/atomic.h>
 #include <linux/cpuset.h>
 #include <linux/proc_ns.h>
@@ -1080,7 +1078,7 @@ static void cgroup_exit_root_id(struct cgroup_root *root)
 	idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
 }
 
-static void cgroup_free_root(struct cgroup_root *root)
+void cgroup_free_root(struct cgroup_root *root)
 {
 	if (root) {
 		idr_destroy(&root->cgroup_idr);
@@ -1234,7 +1232,6 @@ struct cgroup *task_cgroup_from_root(struct task_struct *task,
  * update of a tasks cgroup pointer by cgroup_attach_task()
  */
 
-static struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
 
 static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
@@ -1542,8 +1539,8 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 	return 0;
 }
 
-static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
-			    struct kernfs_root *kf_root)
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+		     struct kernfs_root *kf_root)
 {
 	int len = 0;
 	char *buf = NULL;
@@ -1569,232 +1566,6 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 	return len;
 }
 
-static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
-{
-	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
-	struct cgroup_subsys *ss;
-	int ssid;
-
-	for_each_subsys(ss, ssid)
-		if (root->subsys_mask & (1 << ssid))
-			seq_show_option(seq, ss->legacy_name, NULL);
-	if (root->flags & CGRP_ROOT_NOPREFIX)
-		seq_puts(seq, ",noprefix");
-	if (root->flags & CGRP_ROOT_XATTR)
-		seq_puts(seq, ",xattr");
-
-	spin_lock(&release_agent_path_lock);
-	if (strlen(root->release_agent_path))
-		seq_show_option(seq, "release_agent",
-				root->release_agent_path);
-	spin_unlock(&release_agent_path_lock);
-
-	if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
-		seq_puts(seq, ",clone_children");
-	if (strlen(root->name))
-		seq_show_option(seq, "name", root->name);
-	return 0;
-}
-
-struct cgroup_sb_opts {
-	u16 subsys_mask;
-	unsigned int flags;
-	char *release_agent;
-	bool cpuset_clone_children;
-	char *name;
-	/* User explicitly requested empty subsystem */
-	bool none;
-};
-
-static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
-{
-	char *token, *o = data;
-	bool all_ss = false, one_ss = false;
-	u16 mask = U16_MAX;
-	struct cgroup_subsys *ss;
-	int nr_opts = 0;
-	int i;
-
-#ifdef CONFIG_CPUSETS
-	mask = ~((u16)1 << cpuset_cgrp_id);
-#endif
-
-	memset(opts, 0, sizeof(*opts));
-
-	while ((token = strsep(&o, ",")) != NULL) {
-		nr_opts++;
-
-		if (!*token)
-			return -EINVAL;
-		if (!strcmp(token, "none")) {
-			/* Explicitly have no subsystems */
-			opts->none = true;
-			continue;
-		}
-		if (!strcmp(token, "all")) {
-			/* Mutually exclusive option 'all' + subsystem name */
-			if (one_ss)
-				return -EINVAL;
-			all_ss = true;
-			continue;
-		}
-		if (!strcmp(token, "noprefix")) {
-			opts->flags |= CGRP_ROOT_NOPREFIX;
-			continue;
-		}
-		if (!strcmp(token, "clone_children")) {
-			opts->cpuset_clone_children = true;
-			continue;
-		}
-		if (!strcmp(token, "xattr")) {
-			opts->flags |= CGRP_ROOT_XATTR;
-			continue;
-		}
-		if (!strncmp(token, "release_agent=", 14)) {
-			/* Specifying two release agents is forbidden */
-			if (opts->release_agent)
-				return -EINVAL;
-			opts->release_agent =
-				kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
-			if (!opts->release_agent)
-				return -ENOMEM;
-			continue;
-		}
-		if (!strncmp(token, "name=", 5)) {
-			const char *name = token + 5;
-			/* Can't specify an empty name */
-			if (!strlen(name))
-				return -EINVAL;
-			/* Must match [\w.-]+ */
-			for (i = 0; i < strlen(name); i++) {
-				char c = name[i];
-				if (isalnum(c))
-					continue;
-				if ((c == '.') || (c == '-') || (c == '_'))
-					continue;
-				return -EINVAL;
-			}
-			/* Specifying two names is forbidden */
-			if (opts->name)
-				return -EINVAL;
-			opts->name = kstrndup(name,
-					      MAX_CGROUP_ROOT_NAMELEN - 1,
-					      GFP_KERNEL);
-			if (!opts->name)
-				return -ENOMEM;
-
-			continue;
-		}
-
-		for_each_subsys(ss, i) {
-			if (strcmp(token, ss->legacy_name))
-				continue;
-			if (!cgroup_ssid_enabled(i))
-				continue;
-			if (cgroup_ssid_no_v1(i))
-				continue;
-
-			/* Mutually exclusive option 'all' + subsystem name */
-			if (all_ss)
-				return -EINVAL;
-			opts->subsys_mask |= (1 << i);
-			one_ss = true;
-
-			break;
-		}
-		if (i == CGROUP_SUBSYS_COUNT)
-			return -ENOENT;
-	}
-
-	/*
-	 * If the 'all' option was specified select all the subsystems,
-	 * otherwise if 'none', 'name=' and a subsystem name options were
-	 * not specified, let's default to 'all'
-	 */
-	if (all_ss || (!one_ss && !opts->none && !opts->name))
-		for_each_subsys(ss, i)
-			if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
-				opts->subsys_mask |= (1 << i);
-
-	/*
-	 * We either have to specify by name or by subsystems. (So all
-	 * empty hierarchies must have a name).
-	 */
-	if (!opts->subsys_mask && !opts->name)
-		return -EINVAL;
-
-	/*
-	 * Option noprefix was introduced just for backward compatibility
-	 * with the old cpuset, so we allow noprefix only if mounting just
-	 * the cpuset subsystem.
-	 */
-	if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
-		return -EINVAL;
-
-	/* Can't specify "none" and some subsystems */
-	if (opts->subsys_mask && opts->none)
-		return -EINVAL;
-
-	return 0;
-}
-
-static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
-{
-	int ret = 0;
-	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
-	struct cgroup_sb_opts opts;
-	u16 added_mask, removed_mask;
-
-	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
-	/* See what subsystems are wanted */
-	ret = parse_cgroupfs_options(data, &opts);
-	if (ret)
-		goto out_unlock;
-
-	if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
-		pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
-			task_tgid_nr(current), current->comm);
-
-	added_mask = opts.subsys_mask & ~root->subsys_mask;
-	removed_mask = root->subsys_mask & ~opts.subsys_mask;
-
-	/* Don't allow flags or name to change at remount */
-	if ((opts.flags ^ root->flags) ||
-	    (opts.name && strcmp(opts.name, root->name))) {
-		pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
-		       opts.flags, opts.name ?: "", root->flags, root->name);
-		ret = -EINVAL;
-		goto out_unlock;
-	}
-
-	/* remounting is not allowed for populated hierarchies */
-	if (!list_empty(&root->cgrp.self.children)) {
-		ret = -EBUSY;
-		goto out_unlock;
-	}
-
-	ret = rebind_subsystems(root, added_mask);
-	if (ret)
-		goto out_unlock;
-
-	WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
-
-	if (opts.release_agent) {
-		spin_lock(&release_agent_path_lock);
-		strcpy(root->release_agent_path, opts.release_agent);
-		spin_unlock(&release_agent_path_lock);
-	}
-
-	trace_cgroup_remount(root);
-
- out_unlock:
-	kfree(opts.release_agent);
-	kfree(opts.name);
-	mutex_unlock(&cgroup_mutex);
-	return ret;
-}
-
 static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
 {
 	pr_err("remount is not allowed\n");
@@ -1879,8 +1650,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
 	INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
 }
 
-static void init_cgroup_root(struct cgroup_root *root,
-			     struct cgroup_sb_opts *opts)
+void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts)
 {
 	struct cgroup *cgrp = &root->cgrp;
 
@@ -1899,7 +1669,7 @@ static void init_cgroup_root(struct cgroup_root *root,
 		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
 }
 
-static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 {
 	LIST_HEAD(tmp_links);
 	struct cgroup *root_cgrp = &root->cgrp;
@@ -1996,10 +1766,9 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	return ret;
 }
 
-static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
-				      int flags, struct cgroup_root *root,
-				      unsigned long magic,
-				      struct cgroup_namespace *ns)
+struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
+			       struct cgroup_root *root, unsigned long magic,
+			       struct cgroup_namespace *ns)
 {
 	struct dentry *dentry;
 	bool new_sb;
@@ -2033,155 +1802,6 @@ static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
 	return dentry;
 }
 
-static struct dentry *cgroup1_mount(struct file_system_type *fs_type,
-				    int flags, void *data,
-				    unsigned long magic,
-				    struct cgroup_namespace *ns)
-{
-	struct super_block *pinned_sb = NULL;
-	struct cgroup_sb_opts opts;
-	struct cgroup_root *root;
-	struct cgroup_subsys *ss;
-	struct dentry *dentry;
-	int i, ret;
-
-	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
-	/* First find the desired set of subsystems */
-	ret = parse_cgroupfs_options(data, &opts);
-	if (ret)
-		goto out_unlock;
-
-	/*
-	 * Destruction of cgroup root is asynchronous, so subsystems may
-	 * still be dying after the previous unmount.  Let's drain the
-	 * dying subsystems.  We just need to ensure that the ones
-	 * unmounted previously finish dying and don't care about new ones
-	 * starting.  Testing ref liveliness is good enough.
-	 */
-	for_each_subsys(ss, i) {
-		if (!(opts.subsys_mask & (1 << i)) ||
-		    ss->root == &cgrp_dfl_root)
-			continue;
-
-		if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
-			mutex_unlock(&cgroup_mutex);
-			msleep(10);
-			ret = restart_syscall();
-			goto out_free;
-		}
-		cgroup_put(&ss->root->cgrp);
-	}
-
-	for_each_root(root) {
-		bool name_match = false;
-
-		if (root == &cgrp_dfl_root)
-			continue;
-
-		/*
-		 * If we asked for a name then it must match.  Also, if
-		 * name matches but sybsys_mask doesn't, we should fail.
-		 * Remember whether name matched.
-		 */
-		if (opts.name) {
-			if (strcmp(opts.name, root->name))
-				continue;
-			name_match = true;
-		}
-
-		/*
-		 * If we asked for subsystems (or explicitly for no
-		 * subsystems) then they must match.
-		 */
-		if ((opts.subsys_mask || opts.none) &&
-		    (opts.subsys_mask != root->subsys_mask)) {
-			if (!name_match)
-				continue;
-			ret = -EBUSY;
-			goto out_unlock;
-		}
-
-		if (root->flags ^ opts.flags)
-			pr_warn("new mount options do not match the existing superblock, will be ignored\n");
-
-		/*
-		 * We want to reuse @root whose lifetime is governed by its
-		 * ->cgrp.  Let's check whether @root is alive and keep it
-		 * that way.  As cgroup_kill_sb() can happen anytime, we
-		 * want to block it by pinning the sb so that @root doesn't
-		 * get killed before mount is complete.
-		 *
-		 * With the sb pinned, tryget_live can reliably indicate
-		 * whether @root can be reused.  If it's being killed,
-		 * drain it.  We can use wait_queue for the wait but this
-		 * path is super cold.  Let's just sleep a bit and retry.
-		 */
-		pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
-		if (IS_ERR(pinned_sb) ||
-		    !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
-			mutex_unlock(&cgroup_mutex);
-			if (!IS_ERR_OR_NULL(pinned_sb))
-				deactivate_super(pinned_sb);
-			msleep(10);
-			ret = restart_syscall();
-			goto out_free;
-		}
-
-		ret = 0;
-		goto out_unlock;
-	}
-
-	/*
-	 * No such thing, create a new one.  name= matching without subsys
-	 * specification is allowed for already existing hierarchies but we
-	 * can't create new one without subsys specification.
-	 */
-	if (!opts.subsys_mask && !opts.none) {
-		ret = -EINVAL;
-		goto out_unlock;
-	}
-
-	/* Hierarchies may only be created in the initial cgroup namespace. */
-	if (ns != &init_cgroup_ns) {
-		ret = -EPERM;
-		goto out_unlock;
-	}
-
-	root = kzalloc(sizeof(*root), GFP_KERNEL);
-	if (!root) {
-		ret = -ENOMEM;
-		goto out_unlock;
-	}
-
-	init_cgroup_root(root, &opts);
-
-	ret = cgroup_setup_root(root, opts.subsys_mask);
-	if (ret)
-		cgroup_free_root(root);
-
-out_unlock:
-	mutex_unlock(&cgroup_mutex);
-out_free:
-	kfree(opts.release_agent);
-	kfree(opts.name);
-
-	if (ret)
-		return ERR_PTR(ret);
-
-	dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
-				 CGROUP_SUPER_MAGIC, ns);
-
-	/*
-	 * If @pinned_sb, we're reusing an existing root and holding an
-	 * extra ref on its sb.  Mount is complete.  Put the extra ref.
-	 */
-	if (pinned_sb)
-		deactivate_super(pinned_sb);
-
-	return dentry;
-}
-
 static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 			 int flags, const char *unused_dev_name,
 			 void *data)
@@ -4589,8 +4209,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 	return ERR_PTR(ret);
 }
 
-static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
-			umode_t mode)
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
 {
 	struct cgroup *parent, *cgrp;
 	struct kernfs_node *kn;
@@ -4802,7 +4421,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	return 0;
 };
 
-static int cgroup_rmdir(struct kernfs_node *kn)
+int cgroup_rmdir(struct kernfs_node *kn)
 {
 	struct cgroup *cgrp;
 	int ret = 0;
@@ -4820,15 +4439,6 @@ static int cgroup_rmdir(struct kernfs_node *kn)
 	return ret;
 }
 
-static struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
-	.remount_fs		= cgroup1_remount,
-	.show_options		= cgroup1_show_options,
-	.rename			= cgroup1_rename,
-	.mkdir			= cgroup_mkdir,
-	.rmdir			= cgroup_rmdir,
-	.show_path		= cgroup_show_path,
-};
-
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
 	.remount_fs		= cgroup_remount,
 	.mkdir			= cgroup_mkdir,
-- 
2.9.3

[PATCH 8/8] cgroup: move namespace code to kernel/cgroup/namespace.c

[Tejun Heo]

get/put_css_set() get exposed in cgroup-internal.h in the process.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/cgroup/Makefile          |   2 +-
 kernel/cgroup/cgroup-internal.h |  32 ++++++++
 kernel/cgroup/cgroup.c          | 175 +---------------------------------------
 kernel/cgroup/namespace.c       | 155 +++++++++++++++++++++++++++++++++++
 4 files changed, 189 insertions(+), 175 deletions(-)
 create mode 100644 kernel/cgroup/namespace.c

diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
index 719588c..6d42a32 100644
--- a/kernel/cgroup/Makefile
+++ b/kernel/cgroup/Makefile
@@ -1,4 +1,4 @@
-obj-y := cgroup.o cgroup-v1.o
+obj-y := cgroup.o namespace.o cgroup-v1.o
 
 obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
 obj-$(CONFIG_CGROUP_PIDS) += pids.o
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 2020d8d..690fa5d 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -63,6 +63,33 @@ static inline bool notify_on_release(const struct cgroup *cgrp)
 	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 }
 
+void put_css_set_locked(struct css_set *cset);
+
+static inline void put_css_set(struct css_set *cset)
+{
+	unsigned long flags;
+
+	/*
+	 * Ensure that the refcount doesn't hit zero while any readers
+	 * can see it. Similar to atomic_dec_and_lock(), but for an
+	 * rwlock
+	 */
+	if (atomic_add_unless(&cset->refcount, -1, 1))
+		return;
+
+	spin_lock_irqsave(&css_set_lock, flags);
+	put_css_set_locked(cset);
+	spin_unlock_irqrestore(&css_set_lock, flags);
+}
+
+/*
+ * refcounted get/put for css_set objects
+ */
+static inline void get_css_set(struct css_set *cset)
+{
+	atomic_inc(&cset->refcount);
+}
+
 bool cgroup_ssid_enabled(int ssid);
 bool cgroup_on_dfl(const struct cgroup *cgrp);
 
@@ -106,6 +133,11 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 		     struct kernfs_root *kf_root);
 
 /*
+ * namespace.c
+ */
+extern const struct proc_ns_operations cgroupns_operations;
+
+/*
  * cgroup-v1.c
  */
 extern struct cftype cgroup1_base_files[];
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index dcfbeb6..792f151 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -720,7 +720,7 @@ static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
 	return key;
 }
 
-static void put_css_set_locked(struct css_set *cset)
+void put_css_set_locked(struct css_set *cset)
 {
 	struct cgrp_cset_link *link, *tmp_link;
 	struct cgroup_subsys *ss;
@@ -750,31 +750,6 @@ static void put_css_set_locked(struct css_set *cset)
 	kfree_rcu(cset, rcu_head);
 }
 
-static void put_css_set(struct css_set *cset)
-{
-	unsigned long flags;
-
-	/*
-	 * Ensure that the refcount doesn't hit zero while any readers
-	 * can see it. Similar to atomic_dec_and_lock(), but for an
-	 * rwlock
-	 */
-	if (atomic_add_unless(&cset->refcount, -1, 1))
-		return;
-
-	spin_lock_irqsave(&css_set_lock, flags);
-	put_css_set_locked(cset);
-	spin_unlock_irqrestore(&css_set_lock, flags);
-}
-
-/*
- * refcounted get/put for css_set objects
- */
-static inline void get_css_set(struct css_set *cset)
-{
-	atomic_inc(&cset->refcount);
-}
-
 /**
  * compare_css_sets - helper function for find_existing_css_set().
  * @cset: candidate css_set being tested
@@ -5111,154 +5086,6 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd)
 
 #endif	/* CONFIG_SOCK_CGROUP_DATA */
 
-/* cgroup namespaces */
-
-static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
-{
-	return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
-}
-
-static void dec_cgroup_namespaces(struct ucounts *ucounts)
-{
-	dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
-}
-
-static struct cgroup_namespace *alloc_cgroup_ns(void)
-{
-	struct cgroup_namespace *new_ns;
-	int ret;
-
-	new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
-	if (!new_ns)
-		return ERR_PTR(-ENOMEM);
-	ret = ns_alloc_inum(&new_ns->ns);
-	if (ret) {
-		kfree(new_ns);
-		return ERR_PTR(ret);
-	}
-	atomic_set(&new_ns->count, 1);
-	new_ns->ns.ops = &cgroupns_operations;
-	return new_ns;
-}
-
-void free_cgroup_ns(struct cgroup_namespace *ns)
-{
-	put_css_set(ns->root_cset);
-	dec_cgroup_namespaces(ns->ucounts);
-	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
-	kfree(ns);
-}
-EXPORT_SYMBOL(free_cgroup_ns);
-
-struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
-					struct user_namespace *user_ns,
-					struct cgroup_namespace *old_ns)
-{
-	struct cgroup_namespace *new_ns;
-	struct ucounts *ucounts;
-	struct css_set *cset;
-
-	BUG_ON(!old_ns);
-
-	if (!(flags & CLONE_NEWCGROUP)) {
-		get_cgroup_ns(old_ns);
-		return old_ns;
-	}
-
-	/* Allow only sysadmin to create cgroup namespace. */
-	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
-		return ERR_PTR(-EPERM);
-
-	ucounts = inc_cgroup_namespaces(user_ns);
-	if (!ucounts)
-		return ERR_PTR(-ENOSPC);
-
-	/* It is not safe to take cgroup_mutex here */
-	spin_lock_irq(&css_set_lock);
-	cset = task_css_set(current);
-	get_css_set(cset);
-	spin_unlock_irq(&css_set_lock);
-
-	new_ns = alloc_cgroup_ns();
-	if (IS_ERR(new_ns)) {
-		put_css_set(cset);
-		dec_cgroup_namespaces(ucounts);
-		return new_ns;
-	}
-
-	new_ns->user_ns = get_user_ns(user_ns);
-	new_ns->ucounts = ucounts;
-	new_ns->root_cset = cset;
-
-	return new_ns;
-}
-
-static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct cgroup_namespace, ns);
-}
-
-static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
-{
-	struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
-
-	if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
-	    !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
-		return -EPERM;
-
-	/* Don't need to do anything if we are attaching to our own cgroupns. */
-	if (cgroup_ns == nsproxy->cgroup_ns)
-		return 0;
-
-	get_cgroup_ns(cgroup_ns);
-	put_cgroup_ns(nsproxy->cgroup_ns);
-	nsproxy->cgroup_ns = cgroup_ns;
-
-	return 0;
-}
-
-static struct ns_common *cgroupns_get(struct task_struct *task)
-{
-	struct cgroup_namespace *ns = NULL;
-	struct nsproxy *nsproxy;
-
-	task_lock(task);
-	nsproxy = task->nsproxy;
-	if (nsproxy) {
-		ns = nsproxy->cgroup_ns;
-		get_cgroup_ns(ns);
-	}
-	task_unlock(task);
-
-	return ns ? &ns->ns : NULL;
-}
-
-static void cgroupns_put(struct ns_common *ns)
-{
-	put_cgroup_ns(to_cg_ns(ns));
-}
-
-static struct user_namespace *cgroupns_owner(struct ns_common *ns)
-{
-	return to_cg_ns(ns)->user_ns;
-}
-
-const struct proc_ns_operations cgroupns_operations = {
-	.name		= "cgroup",
-	.type		= CLONE_NEWCGROUP,
-	.get		= cgroupns_get,
-	.put		= cgroupns_put,
-	.install	= cgroupns_install,
-	.owner		= cgroupns_owner,
-};
-
-static __init int cgroup_namespaces_init(void)
-{
-	return 0;
-}
-subsys_initcall(cgroup_namespaces_init);
-
 #ifdef CONFIG_CGROUP_BPF
 void cgroup_bpf_update(struct cgroup *cgrp,
 		       struct bpf_prog *prog,
diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
new file mode 100644
index 0000000..cff7ea6
--- /dev/null
+++ b/kernel/cgroup/namespace.c
@@ -0,0 +1,155 @@
+#include "cgroup-internal.h"
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/nsproxy.h>
+#include <linux/proc_ns.h>
+
+
+/* cgroup namespaces */
+
+static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
+{
+	return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
+}
+
+static void dec_cgroup_namespaces(struct ucounts *ucounts)
+{
+	dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
+}
+
+static struct cgroup_namespace *alloc_cgroup_ns(void)
+{
+	struct cgroup_namespace *new_ns;
+	int ret;
+
+	new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
+	if (!new_ns)
+		return ERR_PTR(-ENOMEM);
+	ret = ns_alloc_inum(&new_ns->ns);
+	if (ret) {
+		kfree(new_ns);
+		return ERR_PTR(ret);
+	}
+	atomic_set(&new_ns->count, 1);
+	new_ns->ns.ops = &cgroupns_operations;
+	return new_ns;
+}
+
+void free_cgroup_ns(struct cgroup_namespace *ns)
+{
+	put_css_set(ns->root_cset);
+	dec_cgroup_namespaces(ns->ucounts);
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+EXPORT_SYMBOL(free_cgroup_ns);
+
+struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
+					struct user_namespace *user_ns,
+					struct cgroup_namespace *old_ns)
+{
+	struct cgroup_namespace *new_ns;
+	struct ucounts *ucounts;
+	struct css_set *cset;
+
+	BUG_ON(!old_ns);
+
+	if (!(flags & CLONE_NEWCGROUP)) {
+		get_cgroup_ns(old_ns);
+		return old_ns;
+	}
+
+	/* Allow only sysadmin to create cgroup namespace. */
+	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+		return ERR_PTR(-EPERM);
+
+	ucounts = inc_cgroup_namespaces(user_ns);
+	if (!ucounts)
+		return ERR_PTR(-ENOSPC);
+
+	/* It is not safe to take cgroup_mutex here */
+	spin_lock_irq(&css_set_lock);
+	cset = task_css_set(current);
+	get_css_set(cset);
+	spin_unlock_irq(&css_set_lock);
+
+	new_ns = alloc_cgroup_ns();
+	if (IS_ERR(new_ns)) {
+		put_css_set(cset);
+		dec_cgroup_namespaces(ucounts);
+		return new_ns;
+	}
+
+	new_ns->user_ns = get_user_ns(user_ns);
+	new_ns->ucounts = ucounts;
+	new_ns->root_cset = cset;
+
+	return new_ns;
+}
+
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct cgroup_namespace, ns);
+}
+
+static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
+{
+	struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
+
+	if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
+	    !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
+		return -EPERM;
+
+	/* Don't need to do anything if we are attaching to our own cgroupns. */
+	if (cgroup_ns == nsproxy->cgroup_ns)
+		return 0;
+
+	get_cgroup_ns(cgroup_ns);
+	put_cgroup_ns(nsproxy->cgroup_ns);
+	nsproxy->cgroup_ns = cgroup_ns;
+
+	return 0;
+}
+
+static struct ns_common *cgroupns_get(struct task_struct *task)
+{
+	struct cgroup_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->cgroup_ns;
+		get_cgroup_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void cgroupns_put(struct ns_common *ns)
+{
+	put_cgroup_ns(to_cg_ns(ns));
+}
+
+static struct user_namespace *cgroupns_owner(struct ns_common *ns)
+{
+	return to_cg_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations cgroupns_operations = {
+	.name		= "cgroup",
+	.type		= CLONE_NEWCGROUP,
+	.get		= cgroupns_get,
+	.put		= cgroupns_put,
+	.install	= cgroupns_install,
+	.owner		= cgroupns_owner,
+};
+
+static __init int cgroup_namespaces_init(void)
+{
+	return 0;
+}
+subsys_initcall(cgroup_namespaces_init);
-- 
2.9.3

[PATCH 9/8] cgroup: fix RCU related sparse warnings

[Tejun Heo]

From 9ca76e7e3cb885bc5701e9b1fe90c44f4aef123a Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Date: Thu, 22 Dec 2016 12:28:01 -0500

kn->priv which is a void * is used as a RCU pointer by cgroup.  When
dereferencing it, it was passing kn->priv to rcu_derefreence() without
casting it into a RCU pointer triggering address space mismatch
warning from sparse.  Fix them.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Reported-by: Fengguang Wu <fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 kernel/cgroup/cgroup-v1.c | 2 +-
 kernel/cgroup/cgroup.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 37be09e..465b101 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -694,7 +694,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
 	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
 	 */
 	rcu_read_lock();
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (!cgrp || cgroup_is_dead(cgrp)) {
 		rcu_read_unlock();
 		mutex_unlock(&cgroup_mutex);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index b6b9068..d9d82e9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4932,7 +4932,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
 	 * have been or be removed at any point.  @kn->priv is RCU
 	 * protected for this access.  See css_release_work_fn() for details.
 	 */
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (cgrp)
 		css = cgroup_css(cgrp, ss);
 
-- 
2.9.3

Re: [PATCHSET] cgroup: reorganize cgroup source files

[Zefan Li]

On 2016/12/21 5:08, Tejun Heo wrote:
> cgroup source files are getting a bit too unwieldy.  Let's reorganize
> them.
> 
> * Move cgroup files in kernel to kernel/cgroup.
> 
> * Split cgroup.c into multiple files.
> 
> The only functional change this patchset causes is loss of a
> WARN_ON(); otherwise, everything remains identical.
> 
> This patchset contains the following eight patches.
> 
>  0001-cgroup-reorder-css_set-fields.patch
>  0002-cgroup-move-cgroup-files-under-kernel-cgroup.patch
>  0003-cgroup-move-cgroup-v1-specific-code-to-kernel-cgroup.patch
>  0004-cgroup-refactor-mount-path-and-clearly-distinguish-v.patch
>  0005-cgroup-separate-out-cgroup1_kf_syscall_ops.patch
>  0006-cgroup-move-v1-mount-functions-to-kernel-cgroup-cgro.patch
>  0007-cgroup-rename-functions-for-consistency.patch
>  0008-cgroup-move-namespace-code-to-kernel-cgroup-namespac.patch
> 
> The patchset is available in the following git branch
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup-reorg
> 
> and on top of the following git branch
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup2-procs
> 
> diffstat follows.  Thanks.
> 
>  include/linux/cgroup-defs.h     |   54 -
>  kernel/Makefile                 |    5 
>  kernel/cgroup/Makefile          |    5 
>  kernel/cgroup/cgroup-internal.h |  155 +++
>  kernel/cgroup/cgroup-v1.c       | 1395 ++++++++++++++++++++++++++++
>  kernel/cgroup/cgroup.c          | 1940 +++-------------------------------------
>  kernel/cgroup/namespace.c       |  155 +++
>  7 files changed, 1907 insertions(+), 1802 deletions(-)
> 

Acked-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

Re: [PATCHSET] cgroup: reorganize cgroup source files

[Tejun Heo]

On Tue, Dec 20, 2016 at 04:08:19PM -0500, Tejun Heo wrote:
> cgroup source files are getting a bit too unwieldy.  Let's reorganize
> them.
> 
> * Move cgroup files in kernel to kernel/cgroup.
> 
> * Split cgroup.c into multiple files.
> 
> The only functional change this patchset causes is loss of a
> WARN_ON(); otherwise, everything remains identical.

Applied to cgroup/for-4.11.

-- 
tejun

[PATCH 3/8] cgroup: move cgroup v1 specific code to kernel/cgroup/cgroup-v1.c

[Tejun Heo]

cgroup.c is getting too unwieldy.  Let's move out cgroup v1 specific
code along with the debug controller into kernel/cgroup/cgroup-v1.c.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/cgroup/Makefile          |    2 +-
 kernel/cgroup/cgroup-internal.h |  101 ++++
 kernel/cgroup/cgroup-v1.c       | 1027 +++++++++++++++++++++++++++++++++++
 kernel/cgroup/cgroup.c          | 1134 ++-------------------------------------
 4 files changed, 1160 insertions(+), 1104 deletions(-)
 create mode 100644 kernel/cgroup/cgroup-internal.h
 create mode 100644 kernel/cgroup/cgroup-v1.c

diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
index 4d561a5..719588c 100644
--- a/kernel/cgroup/Makefile
+++ b/kernel/cgroup/Makefile
@@ -1,4 +1,4 @@
-obj-y := cgroup.o
+obj-y := cgroup.o cgroup-v1.o
 
 obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
 obj-$(CONFIG_CGROUP_PIDS) += pids.o
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
new file mode 100644
index 0000000..d86fbbc
--- /dev/null
+++ b/kernel/cgroup/cgroup-internal.h
@@ -0,0 +1,101 @@
+#ifndef __CGROUP_INTERNAL_H
+#define __CGROUP_INTERNAL_H
+
+#include <linux/cgroup.h>
+#include <linux/kernfs.h>
+#include <linux/workqueue.h>
+#include <linux/list.h>
+
+/*
+ * A cgroup can be associated with multiple css_sets as different tasks may
+ * belong to different cgroups on different hierarchies.  In the other
+ * direction, a css_set is naturally associated with multiple cgroups.
+ * This M:N relationship is represented by the following link structure
+ * which exists for each association and allows traversing the associations
+ * from both sides.
+ */
+struct cgrp_cset_link {
+	/* the cgroup and css_set this link associates */
+	struct cgroup		*cgrp;
+	struct css_set		*cset;
+
+	/* list of cgrp_cset_links anchored at cgrp->cset_links */
+	struct list_head	cset_link;
+
+	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
+	struct list_head	cgrp_link;
+};
+
+extern struct cgroup_subsys *cgroup_subsys[];
+extern struct list_head cgroup_roots;
+extern struct file_system_type cgroup_fs_type;
+
+/* iterate across the hierarchies */
+#define for_each_root(root)						\
+	list_for_each_entry((root), &cgroup_roots, root_list)
+
+/**
+ * for_each_subsys - iterate all enabled cgroup subsystems
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ */
+#define for_each_subsys(ss, ssid)					\
+	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
+	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
+
+static inline bool cgroup_is_dead(const struct cgroup *cgrp)
+{
+	return !(cgrp->self.flags & CSS_ONLINE);
+}
+
+static inline bool notify_on_release(const struct cgroup *cgrp)
+{
+	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+}
+
+bool cgroup_ssid_enabled(int ssid);
+bool cgroup_on_dfl(const struct cgroup *cgrp);
+
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+				     struct cgroup_root *root);
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
+void cgroup_kn_unlock(struct kernfs_node *kn);
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+			  struct cgroup_namespace *ns);
+
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+
+bool cgroup_may_migrate_to(struct cgroup *dst_cgrp);
+void cgroup_migrate_finish(struct list_head *preloaded_csets);
+void cgroup_migrate_add_src(struct css_set *src_cset,
+			    struct cgroup *dst_cgrp,
+			    struct list_head *preloaded_csets);
+int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets);
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+		   struct cgroup_root *root);
+
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+		       bool threadgroup);
+ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+			     size_t nbytes, loff_t off, bool threadgroup);
+ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			   loff_t off);
+
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
+
+/*
+ * cgroup-v1.c
+ */
+extern spinlock_t release_agent_path_lock;
+extern struct cftype cgroup_legacy_base_files[];
+extern const struct file_operations proc_cgroupstats_operations;
+
+bool cgroup_ssid_no_v1(int ssid);
+void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
+int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		  const char *new_name_str);
+void cgroup_release_agent(struct work_struct *work);
+void check_for_release(struct cgroup *cgrp);
+
+#endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
new file mode 100644
index 0000000..7af745a
--- /dev/null
+++ b/kernel/cgroup/cgroup-v1.c
@@ -0,0 +1,1027 @@
+#include "cgroup-internal.h"
+
+#include <linux/kmod.h>
+#include <linux/sort.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delayacct.h>
+#include <linux/pid_namespace.h>
+#include <linux/cgroupstats.h>
+
+#include <trace/events/cgroup.h>
+
+/*
+ * pidlists linger the following amount before being destroyed.  The goal
+ * is avoiding frequent destruction in the middle of consecutive read calls
+ * Expiring in the middle is a performance problem not a correctness one.
+ * 1 sec should be enough.
+ */
+#define CGROUP_PIDLIST_DESTROY_DELAY	HZ
+
+/* Controllers blocked by the commandline in v1 */
+static u16 cgroup_no_v1_mask;
+
+/*
+ * pidlist destructions need to be flushed on cgroup destruction.  Use a
+ * separate workqueue as flush domain.
+ */
+static struct workqueue_struct *cgroup_pidlist_destroy_wq;
+
+/*
+ * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
+ * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
+ */
+DEFINE_SPINLOCK(release_agent_path_lock);
+
+bool cgroup_ssid_no_v1(int ssid)
+{
+	return cgroup_no_v1_mask & (1 << ssid);
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+	struct cgroup_root *root;
+	int retval = 0;
+
+	mutex_lock(&cgroup_mutex);
+	percpu_down_write(&cgroup_threadgroup_rwsem);
+	for_each_root(root) {
+		struct cgroup *from_cgrp;
+
+		if (root == &cgrp_dfl_root)
+			continue;
+
+		spin_lock_irq(&css_set_lock);
+		from_cgrp = task_cgroup_from_root(from, root);
+		spin_unlock_irq(&css_set_lock);
+
+		retval = cgroup_attach_task(from_cgrp, tsk, false);
+		if (retval)
+			break;
+	}
+	percpu_up_write(&cgroup_threadgroup_rwsem);
+	mutex_unlock(&cgroup_mutex);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
+
+/**
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ *
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup.  No task
+ * can slip out of migration through forking.
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+	LIST_HEAD(preloaded_csets);
+	struct cgrp_cset_link *link;
+	struct css_task_iter it;
+	struct task_struct *task;
+	int ret;
+
+	if (cgroup_on_dfl(to))
+		return -EINVAL;
+
+	if (!cgroup_may_migrate_to(to))
+		return -EBUSY;
+
+	mutex_lock(&cgroup_mutex);
+
+	percpu_down_write(&cgroup_threadgroup_rwsem);
+
+	/* all tasks in @from are being moved, all csets are source */
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &from->cset_links, cset_link)
+		cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
+	spin_unlock_irq(&css_set_lock);
+
+	ret = cgroup_migrate_prepare_dst(&preloaded_csets);
+	if (ret)
+		goto out_err;
+
+	/*
+	 * Migrate tasks one-by-one until @from is empty.  This fails iff
+	 * ->can_attach() fails.
+	 */
+	do {
+		css_task_iter_start(&from->self, &it);
+		task = css_task_iter_next(&it);
+		if (task)
+			get_task_struct(task);
+		css_task_iter_end(&it);
+
+		if (task) {
+			ret = cgroup_migrate(task, false, to->root);
+			if (!ret)
+				trace_cgroup_transfer_tasks(to, task, false);
+			put_task_struct(task);
+		}
+	} while (task && !ret);
+out_err:
+	cgroup_migrate_finish(&preloaded_csets);
+	percpu_up_write(&cgroup_threadgroup_rwsem);
+	mutex_unlock(&cgroup_mutex);
+	return ret;
+}
+
+/*
+ * Stuff for reading the 'tasks'/'procs' files.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ */
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+	CGROUP_FILE_PROCS,
+	CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+	/*
+	 * used to find which pidlist is wanted. doesn't change as long as
+	 * this particular list stays in the list.
+	*/
+	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+	/* array of xids */
+	pid_t *list;
+	/* how many elements the above list has */
+	int length;
+	/* each of these stored in a list by its cgroup */
+	struct list_head links;
+	/* pointer to the cgroup we belong to, for list removal purposes */
+	struct cgroup *owner;
+	/* for delayed destruction */
+	struct delayed_work destroy_dwork;
+};
+
+/*
+ * The following two functions "fix" the issue where there are more pids
+ * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
+ * TODO: replace with a kernel-wide solution to this problem
+ */
+#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
+static void *pidlist_allocate(int count)
+{
+	if (PIDLIST_TOO_LARGE(count))
+		return vmalloc(count * sizeof(pid_t));
+	else
+		return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
+}
+
+static void pidlist_free(void *p)
+{
+	kvfree(p);
+}
+
+/*
+ * Used to destroy all pidlists lingering waiting for destroy timer.  None
+ * should be left afterwards.
+ */
+void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
+{
+	struct cgroup_pidlist *l, *tmp_l;
+
+	mutex_lock(&cgrp->pidlist_mutex);
+	list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
+		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
+	mutex_unlock(&cgrp->pidlist_mutex);
+
+	flush_workqueue(cgroup_pidlist_destroy_wq);
+	BUG_ON(!list_empty(&cgrp->pidlists));
+}
+
+static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
+						destroy_dwork);
+	struct cgroup_pidlist *tofree = NULL;
+
+	mutex_lock(&l->owner->pidlist_mutex);
+
+	/*
+	 * Destroy iff we didn't get queued again.  The state won't change
+	 * as destroy_dwork can only be queued while locked.
+	 */
+	if (!delayed_work_pending(dwork)) {
+		list_del(&l->links);
+		pidlist_free(l->list);
+		put_pid_ns(l->key.ns);
+		tofree = l;
+	}
+
+	mutex_unlock(&l->owner->pidlist_mutex);
+	kfree(tofree);
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * Returns the number of unique elements.
+ */
+static int pidlist_uniq(pid_t *list, int length)
+{
+	int src, dest = 1;
+
+	/*
+	 * we presume the 0th element is unique, so i starts at 1. trivial
+	 * edge cases first; no work needs to be done for either
+	 */
+	if (length == 0 || length == 1)
+		return length;
+	/* src and dest walk down the list; dest counts unique elements */
+	for (src = 1; src < length; src++) {
+		/* find next unique element */
+		while (list[src] == list[src-1]) {
+			src++;
+			if (src == length)
+				goto after;
+		}
+		/* dest always points to where the next unique element goes */
+		list[dest] = list[src];
+		dest++;
+	}
+after:
+	return dest;
+}
+
+/*
+ * The two pid files - task and cgroup.procs - guaranteed that the result
+ * is sorted, which forced this whole pidlist fiasco.  As pid order is
+ * different per namespace, each namespace needs differently sorted list,
+ * making it impossible to use, for example, single rbtree of member tasks
+ * sorted by task pointer.  As pidlists can be fairly large, allocating one
+ * per open file is dangerous, so cgroup had to implement shared pool of
+ * pidlists keyed by cgroup and namespace.
+ */
+static int cmppid(const void *a, const void *b)
+{
+	return *(pid_t *)a - *(pid_t *)b;
+}
+
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+						  enum cgroup_filetype type)
+{
+	struct cgroup_pidlist *l;
+	/* don't need task_nsproxy() if we're looking at ourself */
+	struct pid_namespace *ns = task_active_pid_ns(current);
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	list_for_each_entry(l, &cgrp->pidlists, links)
+		if (l->key.type == type && l->key.ns == ns)
+			return l;
+	return NULL;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
+						enum cgroup_filetype type)
+{
+	struct cgroup_pidlist *l;
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	l = cgroup_pidlist_find(cgrp, type);
+	if (l)
+		return l;
+
+	/* entry not found; create a new one */
+	l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+	if (!l)
+		return l;
+
+	INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
+	l->key.type = type;
+	/* don't need task_nsproxy() if we're looking at ourself */
+	l->key.ns = get_pid_ns(task_active_pid_ns(current));
+	l->owner = cgrp;
+	list_add(&l->links, &cgrp->pidlists);
+	return l;
+}
+
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ *
+ * Return the number of tasks in the cgroup.  The returned number can be
+ * higher than the actual number of tasks due to css_set references from
+ * namespace roots and temporary usages.
+ */
+static int cgroup_task_count(const struct cgroup *cgrp)
+{
+	int count = 0;
+	struct cgrp_cset_link *link;
+
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &cgrp->cset_links, cset_link)
+		count += atomic_read(&link->cset->refcount);
+	spin_unlock_irq(&css_set_lock);
+	return count;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
+ */
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+			      struct cgroup_pidlist **lp)
+{
+	pid_t *array;
+	int length;
+	int pid, n = 0; /* used for populating the array */
+	struct css_task_iter it;
+	struct task_struct *tsk;
+	struct cgroup_pidlist *l;
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	/*
+	 * If cgroup gets more users after we read count, we won't have
+	 * enough space - tough.  This race is indistinguishable to the
+	 * caller from the case that the additional cgroup users didn't
+	 * show up until sometime later on.
+	 */
+	length = cgroup_task_count(cgrp);
+	array = pidlist_allocate(length);
+	if (!array)
+		return -ENOMEM;
+	/* now, populate the array */
+	css_task_iter_start(&cgrp->self, &it);
+	while ((tsk = css_task_iter_next(&it))) {
+		if (unlikely(n == length))
+			break;
+		/* get tgid or pid for procs or tasks file respectively */
+		if (type == CGROUP_FILE_PROCS)
+			pid = task_tgid_vnr(tsk);
+		else
+			pid = task_pid_vnr(tsk);
+		if (pid > 0) /* make sure to only use valid results */
+			array[n++] = pid;
+	}
+	css_task_iter_end(&it);
+	length = n;
+	/* now sort & (if procs) strip out duplicates */
+	sort(array, length, sizeof(pid_t), cmppid, NULL);
+	if (type == CGROUP_FILE_PROCS)
+		length = pidlist_uniq(array, length);
+
+	l = cgroup_pidlist_find_create(cgrp, type);
+	if (!l) {
+		pidlist_free(array);
+		return -ENOMEM;
+	}
+
+	/* store array, freeing old if necessary */
+	pidlist_free(l->list);
+	l->list = array;
+	l->length = length;
+	*lp = l;
+	return 0;
+}
+
+/*
+ * seq_file methods for the tasks/procs files. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->l->list array.
+ */
+
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
+{
+	/*
+	 * Initially we receive a position value that corresponds to
+	 * one more than the last pid shown (or 0 on the first call or
+	 * after a seek to the start). Use a binary-search to find the
+	 * next pid to display, if any
+	 */
+	struct kernfs_open_file *of = s->private;
+	struct cgroup *cgrp = seq_css(s)->cgroup;
+	struct cgroup_pidlist *l;
+	enum cgroup_filetype type = seq_cft(s)->private;
+	int index = 0, pid = *pos;
+	int *iter, ret;
+
+	mutex_lock(&cgrp->pidlist_mutex);
+
+	/*
+	 * !NULL @of->priv indicates that this isn't the first start()
+	 * after open.  If the matching pidlist is around, we can use that.
+	 * Look for it.  Note that @of->priv can't be used directly.  It
+	 * could already have been destroyed.
+	 */
+	if (of->priv)
+		of->priv = cgroup_pidlist_find(cgrp, type);
+
+	/*
+	 * Either this is the first start() after open or the matching
+	 * pidlist has been destroyed inbetween.  Create a new one.
+	 */
+	if (!of->priv) {
+		ret = pidlist_array_load(cgrp, type,
+					 (struct cgroup_pidlist **)&of->priv);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+	l = of->priv;
+
+	if (pid) {
+		int end = l->length;
+
+		while (index < end) {
+			int mid = (index + end) / 2;
+			if (l->list[mid] == pid) {
+				index = mid;
+				break;
+			} else if (l->list[mid] <= pid)
+				index = mid + 1;
+			else
+				end = mid;
+		}
+	}
+	/* If we're off the end of the array, we're done */
+	if (index >= l->length)
+		return NULL;
+	/* Update the abstract position to be the actual pid that we found */
+	iter = l->list + index;
+	*pos = *iter;
+	return iter;
+}
+
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
+{
+	struct kernfs_open_file *of = s->private;
+	struct cgroup_pidlist *l = of->priv;
+
+	if (l)
+		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
+				 CGROUP_PIDLIST_DESTROY_DELAY);
+	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+}
+
+static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct kernfs_open_file *of = s->private;
+	struct cgroup_pidlist *l = of->priv;
+	pid_t *p = v;
+	pid_t *end = l->list + l->length;
+	/*
+	 * Advance to the next pid in the array. If this goes off the
+	 * end, we're done
+	 */
+	p++;
+	if (p >= end) {
+		return NULL;
+	} else {
+		*pos = *p;
+		return p;
+	}
+}
+
+static int cgroup_pidlist_show(struct seq_file *s, void *v)
+{
+	seq_printf(s, "%d\n", *(int *)v);
+
+	return 0;
+}
+
+static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
+				  char *buf, size_t nbytes, loff_t off)
+{
+	return __cgroup_procs_write(of, buf, nbytes, off, false);
+}
+
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+					  char *buf, size_t nbytes, loff_t off)
+{
+	struct cgroup *cgrp;
+
+	BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+
+	cgrp = cgroup_kn_lock_live(of->kn, false);
+	if (!cgrp)
+		return -ENODEV;
+	spin_lock(&release_agent_path_lock);
+	strlcpy(cgrp->root->release_agent_path, strstrip(buf),
+		sizeof(cgrp->root->release_agent_path));
+	spin_unlock(&release_agent_path_lock);
+	cgroup_kn_unlock(of->kn);
+	return nbytes;
+}
+
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
+{
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+	spin_lock(&release_agent_path_lock);
+	seq_puts(seq, cgrp->root->release_agent_path);
+	spin_unlock(&release_agent_path_lock);
+	seq_putc(seq, '\n');
+	return 0;
+}
+
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
+{
+	seq_puts(seq, "0\n");
+	return 0;
+}
+
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+					 struct cftype *cft)
+{
+	return notify_on_release(css->cgroup);
+}
+
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+					  struct cftype *cft, u64 val)
+{
+	if (val)
+		set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+	else
+		clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+	return 0;
+}
+
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+				      struct cftype *cft)
+{
+	return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+}
+
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+				       struct cftype *cft, u64 val)
+{
+	if (val)
+		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+	else
+		clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+	return 0;
+}
+
+/* cgroup core interface files for the legacy hierarchies */
+struct cftype cgroup_legacy_base_files[] = {
+	{
+		.name = "cgroup.procs",
+		.seq_start = cgroup_pidlist_start,
+		.seq_next = cgroup_pidlist_next,
+		.seq_stop = cgroup_pidlist_stop,
+		.seq_show = cgroup_pidlist_show,
+		.private = CGROUP_FILE_PROCS,
+		.write = cgroup_procs_write,
+	},
+	{
+		.name = "cgroup.clone_children",
+		.read_u64 = cgroup_clone_children_read,
+		.write_u64 = cgroup_clone_children_write,
+	},
+	{
+		.name = "cgroup.sane_behavior",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = cgroup_sane_behavior_show,
+	},
+	{
+		.name = "tasks",
+		.seq_start = cgroup_pidlist_start,
+		.seq_next = cgroup_pidlist_next,
+		.seq_stop = cgroup_pidlist_stop,
+		.seq_show = cgroup_pidlist_show,
+		.private = CGROUP_FILE_TASKS,
+		.write = cgroup_tasks_write,
+	},
+	{
+		.name = "notify_on_release",
+		.read_u64 = cgroup_read_notify_on_release,
+		.write_u64 = cgroup_write_notify_on_release,
+	},
+	{
+		.name = "release_agent",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = cgroup_release_agent_show,
+		.write = cgroup_release_agent_write,
+		.max_write_len = PATH_MAX - 1,
+	},
+	{ }	/* terminate */
+};
+
+/* Display information about each subsystem and each hierarchy */
+static int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+	struct cgroup_subsys *ss;
+	int i;
+
+	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+	/*
+	 * ideally we don't want subsystems moving around while we do this.
+	 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
+	 * subsys/hierarchy state.
+	 */
+	mutex_lock(&cgroup_mutex);
+
+	for_each_subsys(ss, i)
+		seq_printf(m, "%s\t%d\t%d\t%d\n",
+			   ss->legacy_name, ss->root->hierarchy_id,
+			   atomic_read(&ss->root->nr_cgrps),
+			   cgroup_ssid_enabled(i));
+
+	mutex_unlock(&cgroup_mutex);
+	return 0;
+}
+
+static int cgroupstats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_cgroupstats_show, NULL);
+}
+
+const struct file_operations proc_cgroupstats_operations = {
+	.open = cgroupstats_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+	struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+	struct cgroup *cgrp;
+	struct css_task_iter it;
+	struct task_struct *tsk;
+
+	/* it should be kernfs_node belonging to cgroupfs and is a directory */
+	if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+	    kernfs_type(kn) != KERNFS_DIR)
+		return -EINVAL;
+
+	mutex_lock(&cgroup_mutex);
+
+	/*
+	 * We aren't being called from kernfs and there's no guarantee on
+	 * @kn->priv's validity.  For this and css_tryget_online_from_dir(),
+	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
+	 */
+	rcu_read_lock();
+	cgrp = rcu_dereference(kn->priv);
+	if (!cgrp || cgroup_is_dead(cgrp)) {
+		rcu_read_unlock();
+		mutex_unlock(&cgroup_mutex);
+		return -ENOENT;
+	}
+	rcu_read_unlock();
+
+	css_task_iter_start(&cgrp->self, &it);
+	while ((tsk = css_task_iter_next(&it))) {
+		switch (tsk->state) {
+		case TASK_RUNNING:
+			stats->nr_running++;
+			break;
+		case TASK_INTERRUPTIBLE:
+			stats->nr_sleeping++;
+			break;
+		case TASK_UNINTERRUPTIBLE:
+			stats->nr_uninterruptible++;
+			break;
+		case TASK_STOPPED:
+			stats->nr_stopped++;
+			break;
+		default:
+			if (delayacct_is_task_waiting_on_io(tsk))
+				stats->nr_io_wait++;
+			break;
+		}
+	}
+	css_task_iter_end(&it);
+
+	mutex_unlock(&cgroup_mutex);
+	return 0;
+}
+
+void check_for_release(struct cgroup *cgrp)
+{
+	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
+	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
+		schedule_work(&cgrp->release_agent_work);
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup.  That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence.  Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d.  The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task.  We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+void cgroup_release_agent(struct work_struct *work)
+{
+	struct cgroup *cgrp =
+		container_of(work, struct cgroup, release_agent_work);
+	char *pathbuf = NULL, *agentbuf = NULL;
+	char *argv[3], *envp[3];
+	int ret;
+
+	mutex_lock(&cgroup_mutex);
+
+	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+	agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
+	if (!pathbuf || !agentbuf)
+		goto out;
+
+	spin_lock_irq(&css_set_lock);
+	ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+	spin_unlock_irq(&css_set_lock);
+	if (ret < 0 || ret >= PATH_MAX)
+		goto out;
+
+	argv[0] = agentbuf;
+	argv[1] = pathbuf;
+	argv[2] = NULL;
+
+	/* minimal command environment */
+	envp[0] = "HOME=/";
+	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+	envp[2] = NULL;
+
+	mutex_unlock(&cgroup_mutex);
+	call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+	goto out_free;
+out:
+	mutex_unlock(&cgroup_mutex);
+out_free:
+	kfree(agentbuf);
+	kfree(pathbuf);
+}
+
+/*
+ * cgroup_rename - Only allow simple rename of directories in place.
+ */
+int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		  const char *new_name_str)
+{
+	struct cgroup *cgrp = kn->priv;
+	int ret;
+
+	if (kernfs_type(kn) != KERNFS_DIR)
+		return -ENOTDIR;
+	if (kn->parent != new_parent)
+		return -EIO;
+
+	/*
+	 * This isn't a proper migration and its usefulness is very
+	 * limited.  Disallow on the default hierarchy.
+	 */
+	if (cgroup_on_dfl(cgrp))
+		return -EPERM;
+
+	/*
+	 * We're gonna grab cgroup_mutex which nests outside kernfs
+	 * active_ref.  kernfs_rename() doesn't require active_ref
+	 * protection.  Break them before grabbing cgroup_mutex.
+	 */
+	kernfs_break_active_protection(new_parent);
+	kernfs_break_active_protection(kn);
+
+	mutex_lock(&cgroup_mutex);
+
+	ret = kernfs_rename(kn, new_parent, new_name_str);
+	if (!ret)
+		trace_cgroup_rename(cgrp);
+
+	mutex_unlock(&cgroup_mutex);
+
+	kernfs_unbreak_active_protection(kn);
+	kernfs_unbreak_active_protection(new_parent);
+	return ret;
+}
+
+static int __init cgroup1_wq_init(void)
+{
+	/*
+	 * Used to destroy pidlists and separate to serve as flush domain.
+	 * Cap @max_active to 1 too.
+	 */
+	cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
+						    0, 1);
+	BUG_ON(!cgroup_pidlist_destroy_wq);
+	return 0;
+}
+core_initcall(cgroup1_wq_init);
+
+static int __init cgroup_no_v1(char *str)
+{
+	struct cgroup_subsys *ss;
+	char *token;
+	int i;
+
+	while ((token = strsep(&str, ",")) != NULL) {
+		if (!*token)
+			continue;
+
+		if (!strcmp(token, "all")) {
+			cgroup_no_v1_mask = U16_MAX;
+			break;
+		}
+
+		for_each_subsys(ss, i) {
+			if (strcmp(token, ss->name) &&
+			    strcmp(token, ss->legacy_name))
+				continue;
+
+			cgroup_no_v1_mask |= 1 << i;
+		}
+	}
+	return 1;
+}
+__setup("cgroup_no_v1=", cgroup_no_v1);
+
+
+#ifdef CONFIG_CGROUP_DEBUG
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+	if (!css)
+		return ERR_PTR(-ENOMEM);
+
+	return css;
+}
+
+static void debug_css_free(struct cgroup_subsys_state *css)
+{
+	kfree(css);
+}
+
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+				struct cftype *cft)
+{
+	return cgroup_task_count(css->cgroup);
+}
+
+static u64 current_css_set_read(struct cgroup_subsys_state *css,
+				struct cftype *cft)
+{
+	return (u64)(unsigned long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
+					 struct cftype *cft)
+{
+	u64 count;
+
+	rcu_read_lock();
+	count = atomic_read(&task_css_set(current)->refcount);
+	rcu_read_unlock();
+	return count;
+}
+
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
+{
+	struct cgrp_cset_link *link;
+	struct css_set *cset;
+	char *name_buf;
+
+	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+	if (!name_buf)
+		return -ENOMEM;
+
+	spin_lock_irq(&css_set_lock);
+	rcu_read_lock();
+	cset = rcu_dereference(current->cgroups);
+	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+		struct cgroup *c = link->cgrp;
+
+		cgroup_name(c, name_buf, NAME_MAX + 1);
+		seq_printf(seq, "Root %d group %s\n",
+			   c->root->hierarchy_id, name_buf);
+	}
+	rcu_read_unlock();
+	spin_unlock_irq(&css_set_lock);
+	kfree(name_buf);
+	return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
+{
+	struct cgroup_subsys_state *css = seq_css(seq);
+	struct cgrp_cset_link *link;
+
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
+		struct css_set *cset = link->cset;
+		struct task_struct *task;
+		int count = 0;
+
+		seq_printf(seq, "css_set %p\n", cset);
+
+		list_for_each_entry(task, &cset->tasks, cg_list) {
+			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+				goto overflow;
+			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
+		}
+
+		list_for_each_entry(task, &cset->mg_tasks, cg_list) {
+			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+				goto overflow;
+			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
+		}
+		continue;
+	overflow:
+		seq_puts(seq, "  ...\n");
+	}
+	spin_unlock_irq(&css_set_lock);
+	return 0;
+}
+
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+	return (!cgroup_is_populated(css->cgroup) &&
+		!css_has_online_children(&css->cgroup->self));
+}
+
+static struct cftype debug_files[] =  {
+	{
+		.name = "taskcount",
+		.read_u64 = debug_taskcount_read,
+	},
+
+	{
+		.name = "current_css_set",
+		.read_u64 = current_css_set_read,
+	},
+
+	{
+		.name = "current_css_set_refcount",
+		.read_u64 = current_css_set_refcount_read,
+	},
+
+	{
+		.name = "current_css_set_cg_links",
+		.seq_show = current_css_set_cg_links_read,
+	},
+
+	{
+		.name = "cgroup_css_links",
+		.seq_show = cgroup_css_links_read,
+	},
+
+	{
+		.name = "releasable",
+		.read_u64 = releasable_read,
+	},
+
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys debug_cgrp_subsys = {
+	.css_alloc = debug_css_alloc,
+	.css_free = debug_css_free,
+	.legacy_cftypes = debug_files,
+};
+#endif /* CONFIG_CGROUP_DEBUG */
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 1a815f2..cb0d29e 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -28,15 +28,14 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/cgroup.h>
+#include "cgroup-internal.h"
+
 #include <linux/cred.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/init_task.h>
 #include <linux/kernel.h>
-#include <linux/list.h>
 #include <linux/magic.h>
-#include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>
@@ -47,14 +46,8 @@
 #include <linux/spinlock.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/string.h>
-#include <linux/sort.h>
-#include <linux/kmod.h>
-#include <linux/delayacct.h>
-#include <linux/cgroupstats.h>
 #include <linux/hashtable.h>
-#include <linux/pid_namespace.h>
 #include <linux/idr.h>
-#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
@@ -67,14 +60,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/cgroup.h>
 
-/*
- * pidlists linger the following amount before being destroyed.  The goal
- * is avoiding frequent destruction in the middle of consecutive read calls
- * Expiring in the middle is a performance problem not a correctness one.
- * 1 sec should be enough.
- */
-#define CGROUP_PIDLIST_DESTROY_DELAY	HZ
-
 #define CGROUP_FILE_NAME_MAX		(MAX_CGROUP_TYPE_NAMELEN +	\
 					 MAX_CFTYPE_NAME + 2)
 
@@ -110,12 +95,6 @@ static DEFINE_SPINLOCK(cgroup_idr_lock);
  */
 static DEFINE_SPINLOCK(cgroup_file_kn_lock);
 
-/*
- * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
- * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
- */
-static DEFINE_SPINLOCK(release_agent_path_lock);
-
 struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
 
 #define cgroup_assert_mutex_or_rcu_locked()				\
@@ -131,15 +110,9 @@ struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
  */
 static struct workqueue_struct *cgroup_destroy_wq;
 
-/*
- * pidlist destructions need to be flushed on cgroup destruction.  Use a
- * separate workqueue as flush domain.
- */
-static struct workqueue_struct *cgroup_pidlist_destroy_wq;
-
 /* generate an array of cgroup subsystem pointers */
 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
-static struct cgroup_subsys *cgroup_subsys[] = {
+struct cgroup_subsys *cgroup_subsys[] = {
 #include <linux/cgroup_subsys.h>
 };
 #undef SUBSYS
@@ -186,9 +159,6 @@ EXPORT_SYMBOL_GPL(cgrp_dfl_root);
  */
 static bool cgrp_dfl_visible;
 
-/* Controllers blocked by the commandline in v1 */
-static u16 cgroup_no_v1_mask;
-
 /* some controllers are not supported in the default hierarchy */
 static u16 cgrp_dfl_inhibit_ss_mask;
 
@@ -196,8 +166,7 @@ static u16 cgrp_dfl_inhibit_ss_mask;
 static unsigned long cgrp_dfl_implicit_ss_mask;
 
 /* The list of hierarchy roots */
-
-static LIST_HEAD(cgroup_roots);
+LIST_HEAD(cgroup_roots);
 static int cgroup_root_count;
 
 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
@@ -235,10 +204,7 @@ static u16 have_canfork_callback __read_mostly;
 
 static struct file_system_type cgroup2_fs_type;
 static struct cftype cgroup_dfl_base_files[];
-static struct cftype cgroup_legacy_base_files[];
 
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 static int cgroup_apply_control(struct cgroup *cgrp);
 static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
 static void css_task_iter_advance(struct css_task_iter *it);
@@ -259,7 +225,7 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
  * is fine for individual subsystems but unsuitable for cgroup core.  This
  * is slower static_key_enabled() based test indexed by @ssid.
  */
-static bool cgroup_ssid_enabled(int ssid)
+bool cgroup_ssid_enabled(int ssid)
 {
 	if (CGROUP_SUBSYS_COUNT == 0)
 		return false;
@@ -267,11 +233,6 @@ static bool cgroup_ssid_enabled(int ssid)
 	return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
 }
 
-static bool cgroup_ssid_no_v1(int ssid)
-{
-	return cgroup_no_v1_mask & (1 << ssid);
-}
-
 /**
  * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
  * @cgrp: the cgroup of interest
@@ -325,7 +286,7 @@ static bool cgroup_ssid_no_v1(int ssid)
  *
  * - debug: disallowed on the default hierarchy.
  */
-static bool cgroup_on_dfl(const struct cgroup *cgrp)
+bool cgroup_on_dfl(const struct cgroup *cgrp)
 {
 	return cgrp->root == &cgrp_dfl_root;
 }
@@ -481,12 +442,6 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
 	return css;
 }
 
-/* convenient tests for these bits */
-static inline bool cgroup_is_dead(const struct cgroup *cgrp)
-{
-	return !(cgrp->self.flags & CSS_ONLINE);
-}
-
 static void cgroup_get(struct cgroup *cgrp)
 {
 	WARN_ON_ONCE(cgroup_is_dead(cgrp));
@@ -518,11 +473,6 @@ struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
 }
 EXPORT_SYMBOL_GPL(of_css);
 
-static int notify_on_release(const struct cgroup *cgrp)
-{
-	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
-}
-
 /**
  * for_each_css - iterate all css's of a cgroup
  * @css: the iteration cursor
@@ -553,15 +503,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 		else
 
 /**
- * for_each_subsys - iterate all enabled cgroup subsystems
- * @ss: the iteration cursor
- * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- */
-#define for_each_subsys(ss, ssid)					\
-	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
-	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
-
-/**
  * do_each_subsys_mask - filter for_each_subsys with a bitmask
  * @ss: the iteration cursor
  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
@@ -585,10 +526,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 	}								\
 } while (false)
 
-/* iterate across the hierarchies */
-#define for_each_root(root)						\
-	list_for_each_entry((root), &cgroup_roots, root_list)
-
 /* iterate over child cgrps, lock should be held throughout iteration */
 #define cgroup_for_each_live_child(child, cgrp)				\
 	list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
@@ -615,29 +552,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 			;						\
 		else
 
-static void cgroup_release_agent(struct work_struct *work);
-static void check_for_release(struct cgroup *cgrp);
-
-/*
- * A cgroup can be associated with multiple css_sets as different tasks may
- * belong to different cgroups on different hierarchies.  In the other
- * direction, a css_set is naturally associated with multiple cgroups.
- * This M:N relationship is represented by the following link structure
- * which exists for each association and allows traversing the associations
- * from both sides.
- */
-struct cgrp_cset_link {
-	/* the cgroup and css_set this link associates */
-	struct cgroup		*cgrp;
-	struct css_set		*cset;
-
-	/* list of cgrp_cset_links anchored at cgrp->cset_links */
-	struct list_head	cset_link;
-
-	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
-	struct list_head	cgrp_link;
-};
-
 /*
  * The default css_set - used by init and its children prior to any
  * hierarchies being mounted. It contains a pointer to the root state
@@ -1138,7 +1052,7 @@ static struct css_set *find_css_set(struct css_set *old_cset,
 	return cset;
 }
 
-static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
 {
 	struct cgroup *root_cgrp = kf_root->kn->priv;
 
@@ -1283,8 +1197,8 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
  * Return the cgroup for "task" from the given hierarchy. Must be
  * called with cgroup_mutex and css_set_lock held.
  */
-static struct cgroup *task_cgroup_from_root(struct task_struct *task,
-					    struct cgroup_root *root)
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+				     struct cgroup_root *root)
 {
 	/*
 	 * No need to lock the task - since we hold cgroup_mutex the
@@ -1321,7 +1235,6 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task,
  */
 
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
-static const struct file_operations proc_cgroupstats_operations;
 
 static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
 			      char *buf)
@@ -1415,7 +1328,7 @@ static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
  * inaccessible any time.  If the caller intends to continue to access the
  * cgroup, it should pin it before invoking this function.
  */
-static void cgroup_kn_unlock(struct kernfs_node *kn)
+void cgroup_kn_unlock(struct kernfs_node *kn)
 {
 	struct cgroup *cgrp;
 
@@ -1447,8 +1360,7 @@ static void cgroup_kn_unlock(struct kernfs_node *kn)
  * locking under kernfs active protection and allows all kernfs operations
  * including self-removal.
  */
-static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn,
-					  bool drain_offline)
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline)
 {
 	struct cgroup *cgrp;
 
@@ -1559,7 +1471,7 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
 	return ret;
 }
 
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 {
 	struct cgroup *dcgrp = &dst_root->cgrp;
 	struct cgroup_subsys *ss;
@@ -1656,8 +1568,7 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 	return len;
 }
 
-static int cgroup_show_options(struct seq_file *seq,
-			       struct kernfs_root *kf_root)
+static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
 {
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 	struct cgroup_subsys *ss;
@@ -2311,7 +2222,7 @@ static void cgroup_kill_sb(struct super_block *sb)
 	kernfs_kill_sb(sb);
 }
 
-static struct file_system_type cgroup_fs_type = {
+struct file_system_type cgroup_fs_type = {
 	.name = "cgroup",
 	.mount = cgroup_mount,
 	.kill_sb = cgroup_kill_sb,
@@ -2325,8 +2236,8 @@ static struct file_system_type cgroup2_fs_type = {
 	.fs_flags = FS_USERNS_MOUNT,
 };
 
-static int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
-				 struct cgroup_namespace *ns)
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+			  struct cgroup_namespace *ns)
 {
 	struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
 
@@ -2616,7 +2527,7 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
  * zero for migration destination cgroups with tasks so that child cgroups
  * don't compete against tasks.
  */
-static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
+bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
 {
 	return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
 		!dst_cgrp->subtree_control;
@@ -2629,7 +2540,7 @@ static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
  * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst().  See
  * those functions for details.
  */
-static void cgroup_migrate_finish(struct list_head *preloaded_csets)
+void cgroup_migrate_finish(struct list_head *preloaded_csets)
 {
 	struct css_set *cset, *tmp_cset;
 
@@ -2662,9 +2573,9 @@ static void cgroup_migrate_finish(struct list_head *preloaded_csets)
  * into play and the preloaded css_sets are guaranteed to cover all
  * migrations.
  */
-static void cgroup_migrate_add_src(struct css_set *src_cset,
-				   struct cgroup *dst_cgrp,
-				   struct list_head *preloaded_csets)
+void cgroup_migrate_add_src(struct css_set *src_cset,
+			    struct cgroup *dst_cgrp,
+			    struct list_head *preloaded_csets)
 {
 	struct cgroup *src_cgrp;
 
@@ -2709,7 +2620,7 @@ static void cgroup_migrate_add_src(struct css_set *src_cset,
  * using cgroup_migrate(), cgroup_migrate_finish() must be called on
  * @preloaded_csets.
  */
-static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
+int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
 {
 	LIST_HEAD(csets);
 	struct css_set *src_cset, *tmp_cset;
@@ -2773,8 +2684,8 @@ static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
  * decided for all targets by invoking group_migrate_prepare_dst() before
  * actually starting migrating.
  */
-static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
-			  struct cgroup_root *root)
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+		   struct cgroup_root *root)
 {
 	struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
 	struct task_struct *task;
@@ -2806,8 +2717,8 @@ static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
  *
  * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
  */
-static int cgroup_attach_task(struct cgroup *dst_cgrp,
-			      struct task_struct *leader, bool threadgroup)
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+		       bool threadgroup)
 {
 	LIST_HEAD(preloaded_csets);
 	struct task_struct *task;
@@ -2888,8 +2799,8 @@ static int cgroup_procs_write_permission(struct task_struct *task,
  * function to attach either it or all tasks in its threadgroup. Will lock
  * cgroup_mutex and threadgroup.
  */
-static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
-				    size_t nbytes, loff_t off, bool threadgroup)
+ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+			     size_t nbytes, loff_t off, bool threadgroup)
 {
 	struct task_struct *tsk;
 	struct cgroup_subsys *ss;
@@ -2950,86 +2861,12 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
 	return ret ?: nbytes;
 }
 
-/**
- * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
- * @from: attach to all cgroups of a given task
- * @tsk: the task to be attached
- */
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
-{
-	struct cgroup_root *root;
-	int retval = 0;
-
-	mutex_lock(&cgroup_mutex);
-	percpu_down_write(&cgroup_threadgroup_rwsem);
-	for_each_root(root) {
-		struct cgroup *from_cgrp;
-
-		if (root == &cgrp_dfl_root)
-			continue;
-
-		spin_lock_irq(&css_set_lock);
-		from_cgrp = task_cgroup_from_root(from, root);
-		spin_unlock_irq(&css_set_lock);
-
-		retval = cgroup_attach_task(from_cgrp, tsk, false);
-		if (retval)
-			break;
-	}
-	percpu_up_write(&cgroup_threadgroup_rwsem);
-	mutex_unlock(&cgroup_mutex);
-
-	return retval;
-}
-EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-
-static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
-				  char *buf, size_t nbytes, loff_t off)
-{
-	return __cgroup_procs_write(of, buf, nbytes, off, false);
-}
-
-static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
-				  char *buf, size_t nbytes, loff_t off)
+ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			   loff_t off)
 {
 	return __cgroup_procs_write(of, buf, nbytes, off, true);
 }
 
-static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
-					  char *buf, size_t nbytes, loff_t off)
-{
-	struct cgroup *cgrp;
-
-	BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
-
-	cgrp = cgroup_kn_lock_live(of->kn, false);
-	if (!cgrp)
-		return -ENODEV;
-	spin_lock(&release_agent_path_lock);
-	strlcpy(cgrp->root->release_agent_path, strstrip(buf),
-		sizeof(cgrp->root->release_agent_path));
-	spin_unlock(&release_agent_path_lock);
-	cgroup_kn_unlock(of->kn);
-	return nbytes;
-}
-
-static int cgroup_release_agent_show(struct seq_file *seq, void *v)
-{
-	struct cgroup *cgrp = seq_css(seq)->cgroup;
-
-	spin_lock(&release_agent_path_lock);
-	seq_puts(seq, cgrp->root->release_agent_path);
-	spin_unlock(&release_agent_path_lock);
-	seq_putc(seq, '\n');
-	return 0;
-}
-
-static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
-{
-	seq_puts(seq, "0\n");
-	return 0;
-}
-
 static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
 {
 	struct cgroup_subsys *ss;
@@ -3131,7 +2968,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
  * controller while the previous css is still around.  This function grabs
  * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
  */
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
 	__acquires(&cgroup_mutex)
 {
 	struct cgroup *dsct;
@@ -3610,48 +3447,6 @@ static struct kernfs_ops cgroup_kf_ops = {
 	.seq_show		= cgroup_seqfile_show,
 };
 
-/*
- * cgroup_rename - Only allow simple rename of directories in place.
- */
-static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-			 const char *new_name_str)
-{
-	struct cgroup *cgrp = kn->priv;
-	int ret;
-
-	if (kernfs_type(kn) != KERNFS_DIR)
-		return -ENOTDIR;
-	if (kn->parent != new_parent)
-		return -EIO;
-
-	/*
-	 * This isn't a proper migration and its usefulness is very
-	 * limited.  Disallow on the default hierarchy.
-	 */
-	if (cgroup_on_dfl(cgrp))
-		return -EPERM;
-
-	/*
-	 * We're gonna grab cgroup_mutex which nests outside kernfs
-	 * active_ref.  kernfs_rename() doesn't require active_ref
-	 * protection.  Break them before grabbing cgroup_mutex.
-	 */
-	kernfs_break_active_protection(new_parent);
-	kernfs_break_active_protection(kn);
-
-	mutex_lock(&cgroup_mutex);
-
-	ret = kernfs_rename(kn, new_parent, new_name_str);
-	if (!ret)
-		trace_cgroup_rename(cgrp);
-
-	mutex_unlock(&cgroup_mutex);
-
-	kernfs_unbreak_active_protection(kn);
-	kernfs_unbreak_active_protection(new_parent);
-	return ret;
-}
-
 /* set uid and gid of cgroup dirs and files to that of the creator */
 static int cgroup_kn_set_ugid(struct kernfs_node *kn)
 {
@@ -3948,26 +3743,6 @@ void cgroup_file_notify(struct cgroup_file *cfile)
 }
 
 /**
- * cgroup_task_count - count the number of tasks in a cgroup.
- * @cgrp: the cgroup in question
- *
- * Return the number of tasks in the cgroup.  The returned number can be
- * higher than the actual number of tasks due to css_set references from
- * namespace roots and temporary usages.
- */
-static int cgroup_task_count(const struct cgroup *cgrp)
-{
-	int count = 0;
-	struct cgrp_cset_link *link;
-
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &cgrp->cset_links, cset_link)
-		count += atomic_read(&link->cset->refcount);
-	spin_unlock_irq(&css_set_lock);
-	return count;
-}
-
-/**
  * css_next_child - find the next child of a given css
  * @pos: the current position (%NULL to initiate traversal)
  * @parent: css whose children to walk
@@ -4365,70 +4140,6 @@ void css_task_iter_end(struct css_task_iter *it)
 		put_task_struct(it->cur_task);
 }
 
-/**
- * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
- * @to: cgroup to which the tasks will be moved
- * @from: cgroup in which the tasks currently reside
- *
- * Locking rules between cgroup_post_fork() and the migration path
- * guarantee that, if a task is forking while being migrated, the new child
- * is guaranteed to be either visible in the source cgroup after the
- * parent's migration is complete or put into the target cgroup.  No task
- * can slip out of migration through forking.
- */
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
-{
-	LIST_HEAD(preloaded_csets);
-	struct cgrp_cset_link *link;
-	struct css_task_iter it;
-	struct task_struct *task;
-	int ret;
-
-	if (cgroup_on_dfl(to))
-		return -EINVAL;
-
-	if (!cgroup_may_migrate_to(to))
-		return -EBUSY;
-
-	mutex_lock(&cgroup_mutex);
-
-	percpu_down_write(&cgroup_threadgroup_rwsem);
-
-	/* all tasks in @from are being moved, all csets are source */
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &from->cset_links, cset_link)
-		cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
-	spin_unlock_irq(&css_set_lock);
-
-	ret = cgroup_migrate_prepare_dst(&preloaded_csets);
-	if (ret)
-		goto out_err;
-
-	/*
-	 * Migrate tasks one-by-one until @from is empty.  This fails iff
-	 * ->can_attach() fails.
-	 */
-	do {
-		css_task_iter_start(&from->self, &it);
-		task = css_task_iter_next(&it);
-		if (task)
-			get_task_struct(task);
-		css_task_iter_end(&it);
-
-		if (task) {
-			ret = cgroup_migrate(task, false, to->root);
-			if (!ret)
-				trace_cgroup_transfer_tasks(to, task, false);
-			put_task_struct(task);
-		}
-	} while (task && !ret);
-out_err:
-	cgroup_migrate_finish(&preloaded_csets);
-	percpu_up_write(&cgroup_threadgroup_rwsem);
-	mutex_unlock(&cgroup_mutex);
-	return ret;
-}
-
 static void cgroup_procs_release(struct kernfs_open_file *of)
 {
 	if (of->priv) {
@@ -4483,456 +4194,6 @@ static int cgroup_procs_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-/*
- * Stuff for reading the 'tasks'/'procs' files.
- *
- * Reading this file can return large amounts of data if a cgroup has
- * *lots* of attached tasks. So it may need several calls to read(),
- * but we cannot guarantee that the information we produce is correct
- * unless we produce it entirely atomically.
- *
- */
-
-/* which pidlist file are we talking about? */
-enum cgroup_filetype {
-	CGROUP_FILE_PROCS,
-	CGROUP_FILE_TASKS,
-};
-
-/*
- * A pidlist is a list of pids that virtually represents the contents of one
- * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
- * a pair (one each for procs, tasks) for each pid namespace that's relevant
- * to the cgroup.
- */
-struct cgroup_pidlist {
-	/*
-	 * used to find which pidlist is wanted. doesn't change as long as
-	 * this particular list stays in the list.
-	*/
-	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
-	/* array of xids */
-	pid_t *list;
-	/* how many elements the above list has */
-	int length;
-	/* each of these stored in a list by its cgroup */
-	struct list_head links;
-	/* pointer to the cgroup we belong to, for list removal purposes */
-	struct cgroup *owner;
-	/* for delayed destruction */
-	struct delayed_work destroy_dwork;
-};
-
-/*
- * The following two functions "fix" the issue where there are more pids
- * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
- * TODO: replace with a kernel-wide solution to this problem
- */
-#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
-static void *pidlist_allocate(int count)
-{
-	if (PIDLIST_TOO_LARGE(count))
-		return vmalloc(count * sizeof(pid_t));
-	else
-		return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
-}
-
-static void pidlist_free(void *p)
-{
-	kvfree(p);
-}
-
-/*
- * Used to destroy all pidlists lingering waiting for destroy timer.  None
- * should be left afterwards.
- */
-static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
-{
-	struct cgroup_pidlist *l, *tmp_l;
-
-	mutex_lock(&cgrp->pidlist_mutex);
-	list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
-		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
-	mutex_unlock(&cgrp->pidlist_mutex);
-
-	flush_workqueue(cgroup_pidlist_destroy_wq);
-	BUG_ON(!list_empty(&cgrp->pidlists));
-}
-
-static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
-{
-	struct delayed_work *dwork = to_delayed_work(work);
-	struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
-						destroy_dwork);
-	struct cgroup_pidlist *tofree = NULL;
-
-	mutex_lock(&l->owner->pidlist_mutex);
-
-	/*
-	 * Destroy iff we didn't get queued again.  The state won't change
-	 * as destroy_dwork can only be queued while locked.
-	 */
-	if (!delayed_work_pending(dwork)) {
-		list_del(&l->links);
-		pidlist_free(l->list);
-		put_pid_ns(l->key.ns);
-		tofree = l;
-	}
-
-	mutex_unlock(&l->owner->pidlist_mutex);
-	kfree(tofree);
-}
-
-/*
- * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
- * Returns the number of unique elements.
- */
-static int pidlist_uniq(pid_t *list, int length)
-{
-	int src, dest = 1;
-
-	/*
-	 * we presume the 0th element is unique, so i starts at 1. trivial
-	 * edge cases first; no work needs to be done for either
-	 */
-	if (length == 0 || length == 1)
-		return length;
-	/* src and dest walk down the list; dest counts unique elements */
-	for (src = 1; src < length; src++) {
-		/* find next unique element */
-		while (list[src] == list[src-1]) {
-			src++;
-			if (src == length)
-				goto after;
-		}
-		/* dest always points to where the next unique element goes */
-		list[dest] = list[src];
-		dest++;
-	}
-after:
-	return dest;
-}
-
-/*
- * The two pid files - task and cgroup.procs - guaranteed that the result
- * is sorted, which forced this whole pidlist fiasco.  As pid order is
- * different per namespace, each namespace needs differently sorted list,
- * making it impossible to use, for example, single rbtree of member tasks
- * sorted by task pointer.  As pidlists can be fairly large, allocating one
- * per open file is dangerous, so cgroup had to implement shared pool of
- * pidlists keyed by cgroup and namespace.
- */
-static int cmppid(const void *a, const void *b)
-{
-	return *(pid_t *)a - *(pid_t *)b;
-}
-
-static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
-						  enum cgroup_filetype type)
-{
-	struct cgroup_pidlist *l;
-	/* don't need task_nsproxy() if we're looking at ourself */
-	struct pid_namespace *ns = task_active_pid_ns(current);
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	list_for_each_entry(l, &cgrp->pidlists, links)
-		if (l->key.type == type && l->key.ns == ns)
-			return l;
-	return NULL;
-}
-
-/*
- * find the appropriate pidlist for our purpose (given procs vs tasks)
- * returns with the lock on that pidlist already held, and takes care
- * of the use count, or returns NULL with no locks held if we're out of
- * memory.
- */
-static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
-						enum cgroup_filetype type)
-{
-	struct cgroup_pidlist *l;
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	l = cgroup_pidlist_find(cgrp, type);
-	if (l)
-		return l;
-
-	/* entry not found; create a new one */
-	l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
-	if (!l)
-		return l;
-
-	INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
-	l->key.type = type;
-	/* don't need task_nsproxy() if we're looking at ourself */
-	l->key.ns = get_pid_ns(task_active_pid_ns(current));
-	l->owner = cgrp;
-	list_add(&l->links, &cgrp->pidlists);
-	return l;
-}
-
-/*
- * Load a cgroup's pidarray with either procs' tgids or tasks' pids
- */
-static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
-			      struct cgroup_pidlist **lp)
-{
-	pid_t *array;
-	int length;
-	int pid, n = 0; /* used for populating the array */
-	struct css_task_iter it;
-	struct task_struct *tsk;
-	struct cgroup_pidlist *l;
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	/*
-	 * If cgroup gets more users after we read count, we won't have
-	 * enough space - tough.  This race is indistinguishable to the
-	 * caller from the case that the additional cgroup users didn't
-	 * show up until sometime later on.
-	 */
-	length = cgroup_task_count(cgrp);
-	array = pidlist_allocate(length);
-	if (!array)
-		return -ENOMEM;
-	/* now, populate the array */
-	css_task_iter_start(&cgrp->self, &it);
-	while ((tsk = css_task_iter_next(&it))) {
-		if (unlikely(n == length))
-			break;
-		/* get tgid or pid for procs or tasks file respectively */
-		if (type == CGROUP_FILE_PROCS)
-			pid = task_tgid_vnr(tsk);
-		else
-			pid = task_pid_vnr(tsk);
-		if (pid > 0) /* make sure to only use valid results */
-			array[n++] = pid;
-	}
-	css_task_iter_end(&it);
-	length = n;
-	/* now sort & (if procs) strip out duplicates */
-	sort(array, length, sizeof(pid_t), cmppid, NULL);
-	if (type == CGROUP_FILE_PROCS)
-		length = pidlist_uniq(array, length);
-
-	l = cgroup_pidlist_find_create(cgrp, type);
-	if (!l) {
-		pidlist_free(array);
-		return -ENOMEM;
-	}
-
-	/* store array, freeing old if necessary */
-	pidlist_free(l->list);
-	l->list = array;
-	l->length = length;
-	*lp = l;
-	return 0;
-}
-
-/**
- * cgroupstats_build - build and fill cgroupstats
- * @stats: cgroupstats to fill information into
- * @dentry: A dentry entry belonging to the cgroup for which stats have
- * been requested.
- *
- * Build and fill cgroupstats so that taskstats can export it to user
- * space.
- */
-int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
-{
-	struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
-	struct cgroup *cgrp;
-	struct css_task_iter it;
-	struct task_struct *tsk;
-
-	/* it should be kernfs_node belonging to cgroupfs and is a directory */
-	if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
-	    kernfs_type(kn) != KERNFS_DIR)
-		return -EINVAL;
-
-	mutex_lock(&cgroup_mutex);
-
-	/*
-	 * We aren't being called from kernfs and there's no guarantee on
-	 * @kn->priv's validity.  For this and css_tryget_online_from_dir(),
-	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
-	 */
-	rcu_read_lock();
-	cgrp = rcu_dereference(kn->priv);
-	if (!cgrp || cgroup_is_dead(cgrp)) {
-		rcu_read_unlock();
-		mutex_unlock(&cgroup_mutex);
-		return -ENOENT;
-	}
-	rcu_read_unlock();
-
-	css_task_iter_start(&cgrp->self, &it);
-	while ((tsk = css_task_iter_next(&it))) {
-		switch (tsk->state) {
-		case TASK_RUNNING:
-			stats->nr_running++;
-			break;
-		case TASK_INTERRUPTIBLE:
-			stats->nr_sleeping++;
-			break;
-		case TASK_UNINTERRUPTIBLE:
-			stats->nr_uninterruptible++;
-			break;
-		case TASK_STOPPED:
-			stats->nr_stopped++;
-			break;
-		default:
-			if (delayacct_is_task_waiting_on_io(tsk))
-				stats->nr_io_wait++;
-			break;
-		}
-	}
-	css_task_iter_end(&it);
-
-	mutex_unlock(&cgroup_mutex);
-	return 0;
-}
-
-
-/*
- * seq_file methods for the tasks/procs files. The seq_file position is the
- * next pid to display; the seq_file iterator is a pointer to the pid
- * in the cgroup->l->list array.
- */
-
-static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
-{
-	/*
-	 * Initially we receive a position value that corresponds to
-	 * one more than the last pid shown (or 0 on the first call or
-	 * after a seek to the start). Use a binary-search to find the
-	 * next pid to display, if any
-	 */
-	struct kernfs_open_file *of = s->private;
-	struct cgroup *cgrp = seq_css(s)->cgroup;
-	struct cgroup_pidlist *l;
-	enum cgroup_filetype type = seq_cft(s)->private;
-	int index = 0, pid = *pos;
-	int *iter, ret;
-
-	mutex_lock(&cgrp->pidlist_mutex);
-
-	/*
-	 * !NULL @of->priv indicates that this isn't the first start()
-	 * after open.  If the matching pidlist is around, we can use that.
-	 * Look for it.  Note that @of->priv can't be used directly.  It
-	 * could already have been destroyed.
-	 */
-	if (of->priv)
-		of->priv = cgroup_pidlist_find(cgrp, type);
-
-	/*
-	 * Either this is the first start() after open or the matching
-	 * pidlist has been destroyed inbetween.  Create a new one.
-	 */
-	if (!of->priv) {
-		ret = pidlist_array_load(cgrp, type,
-					 (struct cgroup_pidlist **)&of->priv);
-		if (ret)
-			return ERR_PTR(ret);
-	}
-	l = of->priv;
-
-	if (pid) {
-		int end = l->length;
-
-		while (index < end) {
-			int mid = (index + end) / 2;
-			if (l->list[mid] == pid) {
-				index = mid;
-				break;
-			} else if (l->list[mid] <= pid)
-				index = mid + 1;
-			else
-				end = mid;
-		}
-	}
-	/* If we're off the end of the array, we're done */
-	if (index >= l->length)
-		return NULL;
-	/* Update the abstract position to be the actual pid that we found */
-	iter = l->list + index;
-	*pos = *iter;
-	return iter;
-}
-
-static void cgroup_pidlist_stop(struct seq_file *s, void *v)
-{
-	struct kernfs_open_file *of = s->private;
-	struct cgroup_pidlist *l = of->priv;
-
-	if (l)
-		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
-				 CGROUP_PIDLIST_DESTROY_DELAY);
-	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
-}
-
-static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
-{
-	struct kernfs_open_file *of = s->private;
-	struct cgroup_pidlist *l = of->priv;
-	pid_t *p = v;
-	pid_t *end = l->list + l->length;
-	/*
-	 * Advance to the next pid in the array. If this goes off the
-	 * end, we're done
-	 */
-	p++;
-	if (p >= end) {
-		return NULL;
-	} else {
-		*pos = *p;
-		return p;
-	}
-}
-
-static int cgroup_pidlist_show(struct seq_file *s, void *v)
-{
-	seq_printf(s, "%d\n", *(int *)v);
-
-	return 0;
-}
-
-static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
-					 struct cftype *cft)
-{
-	return notify_on_release(css->cgroup);
-}
-
-static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
-					  struct cftype *cft, u64 val)
-{
-	if (val)
-		set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
-	else
-		clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
-	return 0;
-}
-
-static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
-				      struct cftype *cft)
-{
-	return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-}
-
-static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
-				       struct cftype *cft, u64 val)
-{
-	if (val)
-		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-	else
-		clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-	return 0;
-}
-
 /* cgroup core interface files for the default hierarchy */
 static struct cftype cgroup_dfl_base_files[] = {
 	{
@@ -4962,51 +4223,6 @@ static struct cftype cgroup_dfl_base_files[] = {
 	{ }	/* terminate */
 };
 
-/* cgroup core interface files for the legacy hierarchies */
-static struct cftype cgroup_legacy_base_files[] = {
-	{
-		.name = "cgroup.procs",
-		.seq_start = cgroup_pidlist_start,
-		.seq_next = cgroup_pidlist_next,
-		.seq_stop = cgroup_pidlist_stop,
-		.seq_show = cgroup_pidlist_show,
-		.private = CGROUP_FILE_PROCS,
-		.write = cgroup_procs_write,
-	},
-	{
-		.name = "cgroup.clone_children",
-		.read_u64 = cgroup_clone_children_read,
-		.write_u64 = cgroup_clone_children_write,
-	},
-	{
-		.name = "cgroup.sane_behavior",
-		.flags = CFTYPE_ONLY_ON_ROOT,
-		.seq_show = cgroup_sane_behavior_show,
-	},
-	{
-		.name = "tasks",
-		.seq_start = cgroup_pidlist_start,
-		.seq_next = cgroup_pidlist_next,
-		.seq_stop = cgroup_pidlist_stop,
-		.seq_show = cgroup_pidlist_show,
-		.private = CGROUP_FILE_TASKS,
-		.write = cgroup_tasks_write,
-	},
-	{
-		.name = "notify_on_release",
-		.read_u64 = cgroup_read_notify_on_release,
-		.write_u64 = cgroup_write_notify_on_release,
-	},
-	{
-		.name = "release_agent",
-		.flags = CFTYPE_ONLY_ON_ROOT,
-		.seq_show = cgroup_release_agent_show,
-		.write = cgroup_release_agent_write,
-		.max_write_len = PATH_MAX - 1,
-	},
-	{ }	/* terminate */
-};
-
 /*
  * css destruction is four-stage process.
  *
@@ -5792,15 +5008,6 @@ static int __init cgroup_wq_init(void)
 	 */
 	cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
 	BUG_ON(!cgroup_destroy_wq);
-
-	/*
-	 * Used to destroy pidlists and separate to serve as flush domain.
-	 * Cap @max_active to 1 too.
-	 */
-	cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
-						    0, 1);
-	BUG_ON(!cgroup_pidlist_destroy_wq);
-
 	return 0;
 }
 core_initcall(cgroup_wq_init);
@@ -5883,42 +5090,6 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 	return retval;
 }
 
-/* Display information about each subsystem and each hierarchy */
-static int proc_cgroupstats_show(struct seq_file *m, void *v)
-{
-	struct cgroup_subsys *ss;
-	int i;
-
-	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
-	/*
-	 * ideally we don't want subsystems moving around while we do this.
-	 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
-	 * subsys/hierarchy state.
-	 */
-	mutex_lock(&cgroup_mutex);
-
-	for_each_subsys(ss, i)
-		seq_printf(m, "%s\t%d\t%d\t%d\n",
-			   ss->legacy_name, ss->root->hierarchy_id,
-			   atomic_read(&ss->root->nr_cgrps),
-			   cgroup_ssid_enabled(i));
-
-	mutex_unlock(&cgroup_mutex);
-	return 0;
-}
-
-static int cgroupstats_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, proc_cgroupstats_show, NULL);
-}
-
-static const struct file_operations proc_cgroupstats_operations = {
-	.open = cgroupstats_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
-
 /**
  * cgroup_fork - initialize cgroup related fields during copy_process()
  * @child: pointer to task_struct of forking parent process.
@@ -6098,76 +5269,6 @@ void cgroup_free(struct task_struct *task)
 	put_css_set(cset);
 }
 
-static void check_for_release(struct cgroup *cgrp)
-{
-	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
-	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
-		schedule_work(&cgrp->release_agent_work);
-}
-
-/*
- * Notify userspace when a cgroup is released, by running the
- * configured release agent with the name of the cgroup (path
- * relative to the root of cgroup file system) as the argument.
- *
- * Most likely, this user command will try to rmdir this cgroup.
- *
- * This races with the possibility that some other task will be
- * attached to this cgroup before it is removed, or that some other
- * user task will 'mkdir' a child cgroup of this cgroup.  That's ok.
- * The presumed 'rmdir' will fail quietly if this cgroup is no longer
- * unused, and this cgroup will be reprieved from its death sentence,
- * to continue to serve a useful existence.  Next time it's released,
- * we will get notified again, if it still has 'notify_on_release' set.
- *
- * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
- * means only wait until the task is successfully execve()'d.  The
- * separate release agent task is forked by call_usermodehelper(),
- * then control in this thread returns here, without waiting for the
- * release agent task.  We don't bother to wait because the caller of
- * this routine has no use for the exit status of the release agent
- * task, so no sense holding our caller up for that.
- */
-static void cgroup_release_agent(struct work_struct *work)
-{
-	struct cgroup *cgrp =
-		container_of(work, struct cgroup, release_agent_work);
-	char *pathbuf = NULL, *agentbuf = NULL;
-	char *argv[3], *envp[3];
-	int ret;
-
-	mutex_lock(&cgroup_mutex);
-
-	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
-	agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
-	if (!pathbuf || !agentbuf)
-		goto out;
-
-	spin_lock_irq(&css_set_lock);
-	ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
-	spin_unlock_irq(&css_set_lock);
-	if (ret < 0 || ret >= PATH_MAX)
-		goto out;
-
-	argv[0] = agentbuf;
-	argv[1] = pathbuf;
-	argv[2] = NULL;
-
-	/* minimal command environment */
-	envp[0] = "HOME=/";
-	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-	envp[2] = NULL;
-
-	mutex_unlock(&cgroup_mutex);
-	call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
-	goto out_free;
-out:
-	mutex_unlock(&cgroup_mutex);
-out_free:
-	kfree(agentbuf);
-	kfree(pathbuf);
-}
-
 static int __init cgroup_disable(char *str)
 {
 	struct cgroup_subsys *ss;
@@ -6189,33 +5290,6 @@ static int __init cgroup_disable(char *str)
 }
 __setup("cgroup_disable=", cgroup_disable);
 
-static int __init cgroup_no_v1(char *str)
-{
-	struct cgroup_subsys *ss;
-	char *token;
-	int i;
-
-	while ((token = strsep(&str, ",")) != NULL) {
-		if (!*token)
-			continue;
-
-		if (!strcmp(token, "all")) {
-			cgroup_no_v1_mask = U16_MAX;
-			break;
-		}
-
-		for_each_subsys(ss, i) {
-			if (strcmp(token, ss->name) &&
-			    strcmp(token, ss->legacy_name))
-				continue;
-
-			cgroup_no_v1_mask |= 1 << i;
-		}
-	}
-	return 1;
-}
-__setup("cgroup_no_v1=", cgroup_no_v1);
-
 /**
  * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
  * @dentry: directory dentry of interest
@@ -6557,149 +5631,3 @@ void cgroup_bpf_update(struct cgroup *cgrp,
 	mutex_unlock(&cgroup_mutex);
 }
 #endif /* CONFIG_CGROUP_BPF */
-
-#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *
-debug_css_alloc(struct cgroup_subsys_state *parent_css)
-{
-	struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
-
-	if (!css)
-		return ERR_PTR(-ENOMEM);
-
-	return css;
-}
-
-static void debug_css_free(struct cgroup_subsys_state *css)
-{
-	kfree(css);
-}
-
-static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
-				struct cftype *cft)
-{
-	return cgroup_task_count(css->cgroup);
-}
-
-static u64 current_css_set_read(struct cgroup_subsys_state *css,
-				struct cftype *cft)
-{
-	return (u64)(unsigned long)current->cgroups;
-}
-
-static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
-					 struct cftype *cft)
-{
-	u64 count;
-
-	rcu_read_lock();
-	count = atomic_read(&task_css_set(current)->refcount);
-	rcu_read_unlock();
-	return count;
-}
-
-static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
-{
-	struct cgrp_cset_link *link;
-	struct css_set *cset;
-	char *name_buf;
-
-	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
-	if (!name_buf)
-		return -ENOMEM;
-
-	spin_lock_irq(&css_set_lock);
-	rcu_read_lock();
-	cset = rcu_dereference(current->cgroups);
-	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
-		struct cgroup *c = link->cgrp;
-
-		cgroup_name(c, name_buf, NAME_MAX + 1);
-		seq_printf(seq, "Root %d group %s\n",
-			   c->root->hierarchy_id, name_buf);
-	}
-	rcu_read_unlock();
-	spin_unlock_irq(&css_set_lock);
-	kfree(name_buf);
-	return 0;
-}
-
-#define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct seq_file *seq, void *v)
-{
-	struct cgroup_subsys_state *css = seq_css(seq);
-	struct cgrp_cset_link *link;
-
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
-		struct css_set *cset = link->cset;
-		struct task_struct *task;
-		int count = 0;
-
-		seq_printf(seq, "css_set %p\n", cset);
-
-		list_for_each_entry(task, &cset->tasks, cg_list) {
-			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
-				goto overflow;
-			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
-		}
-
-		list_for_each_entry(task, &cset->mg_tasks, cg_list) {
-			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
-				goto overflow;
-			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
-		}
-		continue;
-	overflow:
-		seq_puts(seq, "  ...\n");
-	}
-	spin_unlock_irq(&css_set_lock);
-	return 0;
-}
-
-static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
-{
-	return (!cgroup_is_populated(css->cgroup) &&
-		!css_has_online_children(&css->cgroup->self));
-}
-
-static struct cftype debug_files[] =  {
-	{
-		.name = "taskcount",
-		.read_u64 = debug_taskcount_read,
-	},
-
-	{
-		.name = "current_css_set",
-		.read_u64 = current_css_set_read,
-	},
-
-	{
-		.name = "current_css_set_refcount",
-		.read_u64 = current_css_set_refcount_read,
-	},
-
-	{
-		.name = "current_css_set_cg_links",
-		.seq_show = current_css_set_cg_links_read,
-	},
-
-	{
-		.name = "cgroup_css_links",
-		.seq_show = cgroup_css_links_read,
-	},
-
-	{
-		.name = "releasable",
-		.read_u64 = releasable_read,
-	},
-
-	{ }	/* terminate */
-};
-
-struct cgroup_subsys debug_cgrp_subsys = {
-	.css_alloc = debug_css_alloc,
-	.css_free = debug_css_free,
-	.legacy_cftypes = debug_files,
-};
-#endif /* CONFIG_CGROUP_DEBUG */
-- 
2.9.3

[PATCH v2 3/8] cgroup: move cgroup v1 specific code to kernel/cgroup/cgroup-v1.c

[Tejun Heo]

From 738c8be934e713c7841f49adaece8d7afa0e9166 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Date: Tue, 20 Dec 2016 16:59:05 -0500

cgroup.c is getting too unwieldy.  Let's move out cgroup v1 specific
code along with the debug controller into kernel/cgroup/cgroup-v1.c.

v2: cgroup_mutex and css_set_lock made available in cgroup-internal.h
    regardless of CONFIG_PROVE_RCU.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/cgroup/Makefile          |    2 +-
 kernel/cgroup/cgroup-internal.h |  103 ++++
 kernel/cgroup/cgroup-v1.c       | 1027 +++++++++++++++++++++++++++++++++++
 kernel/cgroup/cgroup.c          | 1140 ++-------------------------------------
 4 files changed, 1164 insertions(+), 1108 deletions(-)
 create mode 100644 kernel/cgroup/cgroup-internal.h
 create mode 100644 kernel/cgroup/cgroup-v1.c

diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
index 4d561a5..719588c 100644
--- a/kernel/cgroup/Makefile
+++ b/kernel/cgroup/Makefile
@@ -1,4 +1,4 @@
-obj-y := cgroup.o
+obj-y := cgroup.o cgroup-v1.o
 
 obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
 obj-$(CONFIG_CGROUP_PIDS) += pids.o
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
new file mode 100644
index 0000000..dca3193
--- /dev/null
+++ b/kernel/cgroup/cgroup-internal.h
@@ -0,0 +1,103 @@
+#ifndef __CGROUP_INTERNAL_H
+#define __CGROUP_INTERNAL_H
+
+#include <linux/cgroup.h>
+#include <linux/kernfs.h>
+#include <linux/workqueue.h>
+#include <linux/list.h>
+
+/*
+ * A cgroup can be associated with multiple css_sets as different tasks may
+ * belong to different cgroups on different hierarchies.  In the other
+ * direction, a css_set is naturally associated with multiple cgroups.
+ * This M:N relationship is represented by the following link structure
+ * which exists for each association and allows traversing the associations
+ * from both sides.
+ */
+struct cgrp_cset_link {
+	/* the cgroup and css_set this link associates */
+	struct cgroup		*cgrp;
+	struct css_set		*cset;
+
+	/* list of cgrp_cset_links anchored at cgrp->cset_links */
+	struct list_head	cset_link;
+
+	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
+	struct list_head	cgrp_link;
+};
+
+extern struct mutex cgroup_mutex;
+extern spinlock_t css_set_lock;
+extern struct cgroup_subsys *cgroup_subsys[];
+extern struct list_head cgroup_roots;
+extern struct file_system_type cgroup_fs_type;
+
+/* iterate across the hierarchies */
+#define for_each_root(root)						\
+	list_for_each_entry((root), &cgroup_roots, root_list)
+
+/**
+ * for_each_subsys - iterate all enabled cgroup subsystems
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ */
+#define for_each_subsys(ss, ssid)					\
+	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
+	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
+
+static inline bool cgroup_is_dead(const struct cgroup *cgrp)
+{
+	return !(cgrp->self.flags & CSS_ONLINE);
+}
+
+static inline bool notify_on_release(const struct cgroup *cgrp)
+{
+	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+}
+
+bool cgroup_ssid_enabled(int ssid);
+bool cgroup_on_dfl(const struct cgroup *cgrp);
+
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+				     struct cgroup_root *root);
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
+void cgroup_kn_unlock(struct kernfs_node *kn);
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+			  struct cgroup_namespace *ns);
+
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+
+bool cgroup_may_migrate_to(struct cgroup *dst_cgrp);
+void cgroup_migrate_finish(struct list_head *preloaded_csets);
+void cgroup_migrate_add_src(struct css_set *src_cset,
+			    struct cgroup *dst_cgrp,
+			    struct list_head *preloaded_csets);
+int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets);
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+		   struct cgroup_root *root);
+
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+		       bool threadgroup);
+ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+			     size_t nbytes, loff_t off, bool threadgroup);
+ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			   loff_t off);
+
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
+
+/*
+ * cgroup-v1.c
+ */
+extern spinlock_t release_agent_path_lock;
+extern struct cftype cgroup_legacy_base_files[];
+extern const struct file_operations proc_cgroupstats_operations;
+
+bool cgroup_ssid_no_v1(int ssid);
+void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
+int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		  const char *new_name_str);
+void cgroup_release_agent(struct work_struct *work);
+void check_for_release(struct cgroup *cgrp);
+
+#endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
new file mode 100644
index 0000000..7af745a
--- /dev/null
+++ b/kernel/cgroup/cgroup-v1.c
@@ -0,0 +1,1027 @@
+#include "cgroup-internal.h"
+
+#include <linux/kmod.h>
+#include <linux/sort.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delayacct.h>
+#include <linux/pid_namespace.h>
+#include <linux/cgroupstats.h>
+
+#include <trace/events/cgroup.h>
+
+/*
+ * pidlists linger the following amount before being destroyed.  The goal
+ * is avoiding frequent destruction in the middle of consecutive read calls
+ * Expiring in the middle is a performance problem not a correctness one.
+ * 1 sec should be enough.
+ */
+#define CGROUP_PIDLIST_DESTROY_DELAY	HZ
+
+/* Controllers blocked by the commandline in v1 */
+static u16 cgroup_no_v1_mask;
+
+/*
+ * pidlist destructions need to be flushed on cgroup destruction.  Use a
+ * separate workqueue as flush domain.
+ */
+static struct workqueue_struct *cgroup_pidlist_destroy_wq;
+
+/*
+ * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
+ * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
+ */
+DEFINE_SPINLOCK(release_agent_path_lock);
+
+bool cgroup_ssid_no_v1(int ssid)
+{
+	return cgroup_no_v1_mask & (1 << ssid);
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+	struct cgroup_root *root;
+	int retval = 0;
+
+	mutex_lock(&cgroup_mutex);
+	percpu_down_write(&cgroup_threadgroup_rwsem);
+	for_each_root(root) {
+		struct cgroup *from_cgrp;
+
+		if (root == &cgrp_dfl_root)
+			continue;
+
+		spin_lock_irq(&css_set_lock);
+		from_cgrp = task_cgroup_from_root(from, root);
+		spin_unlock_irq(&css_set_lock);
+
+		retval = cgroup_attach_task(from_cgrp, tsk, false);
+		if (retval)
+			break;
+	}
+	percpu_up_write(&cgroup_threadgroup_rwsem);
+	mutex_unlock(&cgroup_mutex);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
+
+/**
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ *
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup.  No task
+ * can slip out of migration through forking.
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+	LIST_HEAD(preloaded_csets);
+	struct cgrp_cset_link *link;
+	struct css_task_iter it;
+	struct task_struct *task;
+	int ret;
+
+	if (cgroup_on_dfl(to))
+		return -EINVAL;
+
+	if (!cgroup_may_migrate_to(to))
+		return -EBUSY;
+
+	mutex_lock(&cgroup_mutex);
+
+	percpu_down_write(&cgroup_threadgroup_rwsem);
+
+	/* all tasks in @from are being moved, all csets are source */
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &from->cset_links, cset_link)
+		cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
+	spin_unlock_irq(&css_set_lock);
+
+	ret = cgroup_migrate_prepare_dst(&preloaded_csets);
+	if (ret)
+		goto out_err;
+
+	/*
+	 * Migrate tasks one-by-one until @from is empty.  This fails iff
+	 * ->can_attach() fails.
+	 */
+	do {
+		css_task_iter_start(&from->self, &it);
+		task = css_task_iter_next(&it);
+		if (task)
+			get_task_struct(task);
+		css_task_iter_end(&it);
+
+		if (task) {
+			ret = cgroup_migrate(task, false, to->root);
+			if (!ret)
+				trace_cgroup_transfer_tasks(to, task, false);
+			put_task_struct(task);
+		}
+	} while (task && !ret);
+out_err:
+	cgroup_migrate_finish(&preloaded_csets);
+	percpu_up_write(&cgroup_threadgroup_rwsem);
+	mutex_unlock(&cgroup_mutex);
+	return ret;
+}
+
+/*
+ * Stuff for reading the 'tasks'/'procs' files.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ */
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+	CGROUP_FILE_PROCS,
+	CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+	/*
+	 * used to find which pidlist is wanted. doesn't change as long as
+	 * this particular list stays in the list.
+	*/
+	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+	/* array of xids */
+	pid_t *list;
+	/* how many elements the above list has */
+	int length;
+	/* each of these stored in a list by its cgroup */
+	struct list_head links;
+	/* pointer to the cgroup we belong to, for list removal purposes */
+	struct cgroup *owner;
+	/* for delayed destruction */
+	struct delayed_work destroy_dwork;
+};
+
+/*
+ * The following two functions "fix" the issue where there are more pids
+ * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
+ * TODO: replace with a kernel-wide solution to this problem
+ */
+#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
+static void *pidlist_allocate(int count)
+{
+	if (PIDLIST_TOO_LARGE(count))
+		return vmalloc(count * sizeof(pid_t));
+	else
+		return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
+}
+
+static void pidlist_free(void *p)
+{
+	kvfree(p);
+}
+
+/*
+ * Used to destroy all pidlists lingering waiting for destroy timer.  None
+ * should be left afterwards.
+ */
+void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
+{
+	struct cgroup_pidlist *l, *tmp_l;
+
+	mutex_lock(&cgrp->pidlist_mutex);
+	list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
+		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
+	mutex_unlock(&cgrp->pidlist_mutex);
+
+	flush_workqueue(cgroup_pidlist_destroy_wq);
+	BUG_ON(!list_empty(&cgrp->pidlists));
+}
+
+static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
+						destroy_dwork);
+	struct cgroup_pidlist *tofree = NULL;
+
+	mutex_lock(&l->owner->pidlist_mutex);
+
+	/*
+	 * Destroy iff we didn't get queued again.  The state won't change
+	 * as destroy_dwork can only be queued while locked.
+	 */
+	if (!delayed_work_pending(dwork)) {
+		list_del(&l->links);
+		pidlist_free(l->list);
+		put_pid_ns(l->key.ns);
+		tofree = l;
+	}
+
+	mutex_unlock(&l->owner->pidlist_mutex);
+	kfree(tofree);
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * Returns the number of unique elements.
+ */
+static int pidlist_uniq(pid_t *list, int length)
+{
+	int src, dest = 1;
+
+	/*
+	 * we presume the 0th element is unique, so i starts at 1. trivial
+	 * edge cases first; no work needs to be done for either
+	 */
+	if (length == 0 || length == 1)
+		return length;
+	/* src and dest walk down the list; dest counts unique elements */
+	for (src = 1; src < length; src++) {
+		/* find next unique element */
+		while (list[src] == list[src-1]) {
+			src++;
+			if (src == length)
+				goto after;
+		}
+		/* dest always points to where the next unique element goes */
+		list[dest] = list[src];
+		dest++;
+	}
+after:
+	return dest;
+}
+
+/*
+ * The two pid files - task and cgroup.procs - guaranteed that the result
+ * is sorted, which forced this whole pidlist fiasco.  As pid order is
+ * different per namespace, each namespace needs differently sorted list,
+ * making it impossible to use, for example, single rbtree of member tasks
+ * sorted by task pointer.  As pidlists can be fairly large, allocating one
+ * per open file is dangerous, so cgroup had to implement shared pool of
+ * pidlists keyed by cgroup and namespace.
+ */
+static int cmppid(const void *a, const void *b)
+{
+	return *(pid_t *)a - *(pid_t *)b;
+}
+
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+						  enum cgroup_filetype type)
+{
+	struct cgroup_pidlist *l;
+	/* don't need task_nsproxy() if we're looking at ourself */
+	struct pid_namespace *ns = task_active_pid_ns(current);
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	list_for_each_entry(l, &cgrp->pidlists, links)
+		if (l->key.type == type && l->key.ns == ns)
+			return l;
+	return NULL;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
+						enum cgroup_filetype type)
+{
+	struct cgroup_pidlist *l;
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	l = cgroup_pidlist_find(cgrp, type);
+	if (l)
+		return l;
+
+	/* entry not found; create a new one */
+	l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+	if (!l)
+		return l;
+
+	INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
+	l->key.type = type;
+	/* don't need task_nsproxy() if we're looking at ourself */
+	l->key.ns = get_pid_ns(task_active_pid_ns(current));
+	l->owner = cgrp;
+	list_add(&l->links, &cgrp->pidlists);
+	return l;
+}
+
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ *
+ * Return the number of tasks in the cgroup.  The returned number can be
+ * higher than the actual number of tasks due to css_set references from
+ * namespace roots and temporary usages.
+ */
+static int cgroup_task_count(const struct cgroup *cgrp)
+{
+	int count = 0;
+	struct cgrp_cset_link *link;
+
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &cgrp->cset_links, cset_link)
+		count += atomic_read(&link->cset->refcount);
+	spin_unlock_irq(&css_set_lock);
+	return count;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
+ */
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+			      struct cgroup_pidlist **lp)
+{
+	pid_t *array;
+	int length;
+	int pid, n = 0; /* used for populating the array */
+	struct css_task_iter it;
+	struct task_struct *tsk;
+	struct cgroup_pidlist *l;
+
+	lockdep_assert_held(&cgrp->pidlist_mutex);
+
+	/*
+	 * If cgroup gets more users after we read count, we won't have
+	 * enough space - tough.  This race is indistinguishable to the
+	 * caller from the case that the additional cgroup users didn't
+	 * show up until sometime later on.
+	 */
+	length = cgroup_task_count(cgrp);
+	array = pidlist_allocate(length);
+	if (!array)
+		return -ENOMEM;
+	/* now, populate the array */
+	css_task_iter_start(&cgrp->self, &it);
+	while ((tsk = css_task_iter_next(&it))) {
+		if (unlikely(n == length))
+			break;
+		/* get tgid or pid for procs or tasks file respectively */
+		if (type == CGROUP_FILE_PROCS)
+			pid = task_tgid_vnr(tsk);
+		else
+			pid = task_pid_vnr(tsk);
+		if (pid > 0) /* make sure to only use valid results */
+			array[n++] = pid;
+	}
+	css_task_iter_end(&it);
+	length = n;
+	/* now sort & (if procs) strip out duplicates */
+	sort(array, length, sizeof(pid_t), cmppid, NULL);
+	if (type == CGROUP_FILE_PROCS)
+		length = pidlist_uniq(array, length);
+
+	l = cgroup_pidlist_find_create(cgrp, type);
+	if (!l) {
+		pidlist_free(array);
+		return -ENOMEM;
+	}
+
+	/* store array, freeing old if necessary */
+	pidlist_free(l->list);
+	l->list = array;
+	l->length = length;
+	*lp = l;
+	return 0;
+}
+
+/*
+ * seq_file methods for the tasks/procs files. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->l->list array.
+ */
+
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
+{
+	/*
+	 * Initially we receive a position value that corresponds to
+	 * one more than the last pid shown (or 0 on the first call or
+	 * after a seek to the start). Use a binary-search to find the
+	 * next pid to display, if any
+	 */
+	struct kernfs_open_file *of = s->private;
+	struct cgroup *cgrp = seq_css(s)->cgroup;
+	struct cgroup_pidlist *l;
+	enum cgroup_filetype type = seq_cft(s)->private;
+	int index = 0, pid = *pos;
+	int *iter, ret;
+
+	mutex_lock(&cgrp->pidlist_mutex);
+
+	/*
+	 * !NULL @of->priv indicates that this isn't the first start()
+	 * after open.  If the matching pidlist is around, we can use that.
+	 * Look for it.  Note that @of->priv can't be used directly.  It
+	 * could already have been destroyed.
+	 */
+	if (of->priv)
+		of->priv = cgroup_pidlist_find(cgrp, type);
+
+	/*
+	 * Either this is the first start() after open or the matching
+	 * pidlist has been destroyed inbetween.  Create a new one.
+	 */
+	if (!of->priv) {
+		ret = pidlist_array_load(cgrp, type,
+					 (struct cgroup_pidlist **)&of->priv);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+	l = of->priv;
+
+	if (pid) {
+		int end = l->length;
+
+		while (index < end) {
+			int mid = (index + end) / 2;
+			if (l->list[mid] == pid) {
+				index = mid;
+				break;
+			} else if (l->list[mid] <= pid)
+				index = mid + 1;
+			else
+				end = mid;
+		}
+	}
+	/* If we're off the end of the array, we're done */
+	if (index >= l->length)
+		return NULL;
+	/* Update the abstract position to be the actual pid that we found */
+	iter = l->list + index;
+	*pos = *iter;
+	return iter;
+}
+
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
+{
+	struct kernfs_open_file *of = s->private;
+	struct cgroup_pidlist *l = of->priv;
+
+	if (l)
+		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
+				 CGROUP_PIDLIST_DESTROY_DELAY);
+	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+}
+
+static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct kernfs_open_file *of = s->private;
+	struct cgroup_pidlist *l = of->priv;
+	pid_t *p = v;
+	pid_t *end = l->list + l->length;
+	/*
+	 * Advance to the next pid in the array. If this goes off the
+	 * end, we're done
+	 */
+	p++;
+	if (p >= end) {
+		return NULL;
+	} else {
+		*pos = *p;
+		return p;
+	}
+}
+
+static int cgroup_pidlist_show(struct seq_file *s, void *v)
+{
+	seq_printf(s, "%d\n", *(int *)v);
+
+	return 0;
+}
+
+static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
+				  char *buf, size_t nbytes, loff_t off)
+{
+	return __cgroup_procs_write(of, buf, nbytes, off, false);
+}
+
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+					  char *buf, size_t nbytes, loff_t off)
+{
+	struct cgroup *cgrp;
+
+	BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+
+	cgrp = cgroup_kn_lock_live(of->kn, false);
+	if (!cgrp)
+		return -ENODEV;
+	spin_lock(&release_agent_path_lock);
+	strlcpy(cgrp->root->release_agent_path, strstrip(buf),
+		sizeof(cgrp->root->release_agent_path));
+	spin_unlock(&release_agent_path_lock);
+	cgroup_kn_unlock(of->kn);
+	return nbytes;
+}
+
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
+{
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+	spin_lock(&release_agent_path_lock);
+	seq_puts(seq, cgrp->root->release_agent_path);
+	spin_unlock(&release_agent_path_lock);
+	seq_putc(seq, '\n');
+	return 0;
+}
+
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
+{
+	seq_puts(seq, "0\n");
+	return 0;
+}
+
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+					 struct cftype *cft)
+{
+	return notify_on_release(css->cgroup);
+}
+
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+					  struct cftype *cft, u64 val)
+{
+	if (val)
+		set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+	else
+		clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+	return 0;
+}
+
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+				      struct cftype *cft)
+{
+	return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+}
+
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+				       struct cftype *cft, u64 val)
+{
+	if (val)
+		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+	else
+		clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+	return 0;
+}
+
+/* cgroup core interface files for the legacy hierarchies */
+struct cftype cgroup_legacy_base_files[] = {
+	{
+		.name = "cgroup.procs",
+		.seq_start = cgroup_pidlist_start,
+		.seq_next = cgroup_pidlist_next,
+		.seq_stop = cgroup_pidlist_stop,
+		.seq_show = cgroup_pidlist_show,
+		.private = CGROUP_FILE_PROCS,
+		.write = cgroup_procs_write,
+	},
+	{
+		.name = "cgroup.clone_children",
+		.read_u64 = cgroup_clone_children_read,
+		.write_u64 = cgroup_clone_children_write,
+	},
+	{
+		.name = "cgroup.sane_behavior",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = cgroup_sane_behavior_show,
+	},
+	{
+		.name = "tasks",
+		.seq_start = cgroup_pidlist_start,
+		.seq_next = cgroup_pidlist_next,
+		.seq_stop = cgroup_pidlist_stop,
+		.seq_show = cgroup_pidlist_show,
+		.private = CGROUP_FILE_TASKS,
+		.write = cgroup_tasks_write,
+	},
+	{
+		.name = "notify_on_release",
+		.read_u64 = cgroup_read_notify_on_release,
+		.write_u64 = cgroup_write_notify_on_release,
+	},
+	{
+		.name = "release_agent",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.seq_show = cgroup_release_agent_show,
+		.write = cgroup_release_agent_write,
+		.max_write_len = PATH_MAX - 1,
+	},
+	{ }	/* terminate */
+};
+
+/* Display information about each subsystem and each hierarchy */
+static int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+	struct cgroup_subsys *ss;
+	int i;
+
+	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+	/*
+	 * ideally we don't want subsystems moving around while we do this.
+	 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
+	 * subsys/hierarchy state.
+	 */
+	mutex_lock(&cgroup_mutex);
+
+	for_each_subsys(ss, i)
+		seq_printf(m, "%s\t%d\t%d\t%d\n",
+			   ss->legacy_name, ss->root->hierarchy_id,
+			   atomic_read(&ss->root->nr_cgrps),
+			   cgroup_ssid_enabled(i));
+
+	mutex_unlock(&cgroup_mutex);
+	return 0;
+}
+
+static int cgroupstats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_cgroupstats_show, NULL);
+}
+
+const struct file_operations proc_cgroupstats_operations = {
+	.open = cgroupstats_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+	struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+	struct cgroup *cgrp;
+	struct css_task_iter it;
+	struct task_struct *tsk;
+
+	/* it should be kernfs_node belonging to cgroupfs and is a directory */
+	if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+	    kernfs_type(kn) != KERNFS_DIR)
+		return -EINVAL;
+
+	mutex_lock(&cgroup_mutex);
+
+	/*
+	 * We aren't being called from kernfs and there's no guarantee on
+	 * @kn->priv's validity.  For this and css_tryget_online_from_dir(),
+	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
+	 */
+	rcu_read_lock();
+	cgrp = rcu_dereference(kn->priv);
+	if (!cgrp || cgroup_is_dead(cgrp)) {
+		rcu_read_unlock();
+		mutex_unlock(&cgroup_mutex);
+		return -ENOENT;
+	}
+	rcu_read_unlock();
+
+	css_task_iter_start(&cgrp->self, &it);
+	while ((tsk = css_task_iter_next(&it))) {
+		switch (tsk->state) {
+		case TASK_RUNNING:
+			stats->nr_running++;
+			break;
+		case TASK_INTERRUPTIBLE:
+			stats->nr_sleeping++;
+			break;
+		case TASK_UNINTERRUPTIBLE:
+			stats->nr_uninterruptible++;
+			break;
+		case TASK_STOPPED:
+			stats->nr_stopped++;
+			break;
+		default:
+			if (delayacct_is_task_waiting_on_io(tsk))
+				stats->nr_io_wait++;
+			break;
+		}
+	}
+	css_task_iter_end(&it);
+
+	mutex_unlock(&cgroup_mutex);
+	return 0;
+}
+
+void check_for_release(struct cgroup *cgrp)
+{
+	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
+	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
+		schedule_work(&cgrp->release_agent_work);
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup.  That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence.  Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d.  The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task.  We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+void cgroup_release_agent(struct work_struct *work)
+{
+	struct cgroup *cgrp =
+		container_of(work, struct cgroup, release_agent_work);
+	char *pathbuf = NULL, *agentbuf = NULL;
+	char *argv[3], *envp[3];
+	int ret;
+
+	mutex_lock(&cgroup_mutex);
+
+	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+	agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
+	if (!pathbuf || !agentbuf)
+		goto out;
+
+	spin_lock_irq(&css_set_lock);
+	ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+	spin_unlock_irq(&css_set_lock);
+	if (ret < 0 || ret >= PATH_MAX)
+		goto out;
+
+	argv[0] = agentbuf;
+	argv[1] = pathbuf;
+	argv[2] = NULL;
+
+	/* minimal command environment */
+	envp[0] = "HOME=/";
+	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+	envp[2] = NULL;
+
+	mutex_unlock(&cgroup_mutex);
+	call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+	goto out_free;
+out:
+	mutex_unlock(&cgroup_mutex);
+out_free:
+	kfree(agentbuf);
+	kfree(pathbuf);
+}
+
+/*
+ * cgroup_rename - Only allow simple rename of directories in place.
+ */
+int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		  const char *new_name_str)
+{
+	struct cgroup *cgrp = kn->priv;
+	int ret;
+
+	if (kernfs_type(kn) != KERNFS_DIR)
+		return -ENOTDIR;
+	if (kn->parent != new_parent)
+		return -EIO;
+
+	/*
+	 * This isn't a proper migration and its usefulness is very
+	 * limited.  Disallow on the default hierarchy.
+	 */
+	if (cgroup_on_dfl(cgrp))
+		return -EPERM;
+
+	/*
+	 * We're gonna grab cgroup_mutex which nests outside kernfs
+	 * active_ref.  kernfs_rename() doesn't require active_ref
+	 * protection.  Break them before grabbing cgroup_mutex.
+	 */
+	kernfs_break_active_protection(new_parent);
+	kernfs_break_active_protection(kn);
+
+	mutex_lock(&cgroup_mutex);
+
+	ret = kernfs_rename(kn, new_parent, new_name_str);
+	if (!ret)
+		trace_cgroup_rename(cgrp);
+
+	mutex_unlock(&cgroup_mutex);
+
+	kernfs_unbreak_active_protection(kn);
+	kernfs_unbreak_active_protection(new_parent);
+	return ret;
+}
+
+static int __init cgroup1_wq_init(void)
+{
+	/*
+	 * Used to destroy pidlists and separate to serve as flush domain.
+	 * Cap @max_active to 1 too.
+	 */
+	cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
+						    0, 1);
+	BUG_ON(!cgroup_pidlist_destroy_wq);
+	return 0;
+}
+core_initcall(cgroup1_wq_init);
+
+static int __init cgroup_no_v1(char *str)
+{
+	struct cgroup_subsys *ss;
+	char *token;
+	int i;
+
+	while ((token = strsep(&str, ",")) != NULL) {
+		if (!*token)
+			continue;
+
+		if (!strcmp(token, "all")) {
+			cgroup_no_v1_mask = U16_MAX;
+			break;
+		}
+
+		for_each_subsys(ss, i) {
+			if (strcmp(token, ss->name) &&
+			    strcmp(token, ss->legacy_name))
+				continue;
+
+			cgroup_no_v1_mask |= 1 << i;
+		}
+	}
+	return 1;
+}
+__setup("cgroup_no_v1=", cgroup_no_v1);
+
+
+#ifdef CONFIG_CGROUP_DEBUG
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+	if (!css)
+		return ERR_PTR(-ENOMEM);
+
+	return css;
+}
+
+static void debug_css_free(struct cgroup_subsys_state *css)
+{
+	kfree(css);
+}
+
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+				struct cftype *cft)
+{
+	return cgroup_task_count(css->cgroup);
+}
+
+static u64 current_css_set_read(struct cgroup_subsys_state *css,
+				struct cftype *cft)
+{
+	return (u64)(unsigned long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
+					 struct cftype *cft)
+{
+	u64 count;
+
+	rcu_read_lock();
+	count = atomic_read(&task_css_set(current)->refcount);
+	rcu_read_unlock();
+	return count;
+}
+
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
+{
+	struct cgrp_cset_link *link;
+	struct css_set *cset;
+	char *name_buf;
+
+	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+	if (!name_buf)
+		return -ENOMEM;
+
+	spin_lock_irq(&css_set_lock);
+	rcu_read_lock();
+	cset = rcu_dereference(current->cgroups);
+	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+		struct cgroup *c = link->cgrp;
+
+		cgroup_name(c, name_buf, NAME_MAX + 1);
+		seq_printf(seq, "Root %d group %s\n",
+			   c->root->hierarchy_id, name_buf);
+	}
+	rcu_read_unlock();
+	spin_unlock_irq(&css_set_lock);
+	kfree(name_buf);
+	return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
+{
+	struct cgroup_subsys_state *css = seq_css(seq);
+	struct cgrp_cset_link *link;
+
+	spin_lock_irq(&css_set_lock);
+	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
+		struct css_set *cset = link->cset;
+		struct task_struct *task;
+		int count = 0;
+
+		seq_printf(seq, "css_set %p\n", cset);
+
+		list_for_each_entry(task, &cset->tasks, cg_list) {
+			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+				goto overflow;
+			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
+		}
+
+		list_for_each_entry(task, &cset->mg_tasks, cg_list) {
+			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+				goto overflow;
+			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
+		}
+		continue;
+	overflow:
+		seq_puts(seq, "  ...\n");
+	}
+	spin_unlock_irq(&css_set_lock);
+	return 0;
+}
+
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+	return (!cgroup_is_populated(css->cgroup) &&
+		!css_has_online_children(&css->cgroup->self));
+}
+
+static struct cftype debug_files[] =  {
+	{
+		.name = "taskcount",
+		.read_u64 = debug_taskcount_read,
+	},
+
+	{
+		.name = "current_css_set",
+		.read_u64 = current_css_set_read,
+	},
+
+	{
+		.name = "current_css_set_refcount",
+		.read_u64 = current_css_set_refcount_read,
+	},
+
+	{
+		.name = "current_css_set_cg_links",
+		.seq_show = current_css_set_cg_links_read,
+	},
+
+	{
+		.name = "cgroup_css_links",
+		.seq_show = cgroup_css_links_read,
+	},
+
+	{
+		.name = "releasable",
+		.read_u64 = releasable_read,
+	},
+
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys debug_cgrp_subsys = {
+	.css_alloc = debug_css_alloc,
+	.css_free = debug_css_free,
+	.legacy_cftypes = debug_files,
+};
+#endif /* CONFIG_CGROUP_DEBUG */
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 1a815f2..d34c170 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -28,15 +28,14 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/cgroup.h>
+#include "cgroup-internal.h"
+
 #include <linux/cred.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/init_task.h>
 #include <linux/kernel.h>
-#include <linux/list.h>
 #include <linux/magic.h>
-#include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>
@@ -47,14 +46,8 @@
 #include <linux/spinlock.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/string.h>
-#include <linux/sort.h>
-#include <linux/kmod.h>
-#include <linux/delayacct.h>
-#include <linux/cgroupstats.h>
 #include <linux/hashtable.h>
-#include <linux/pid_namespace.h>
 #include <linux/idr.h>
-#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
@@ -67,14 +60,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/cgroup.h>
 
-/*
- * pidlists linger the following amount before being destroyed.  The goal
- * is avoiding frequent destruction in the middle of consecutive read calls
- * Expiring in the middle is a performance problem not a correctness one.
- * 1 sec should be enough.
- */
-#define CGROUP_PIDLIST_DESTROY_DELAY	HZ
-
 #define CGROUP_FILE_NAME_MAX		(MAX_CGROUP_TYPE_NAMELEN +	\
 					 MAX_CFTYPE_NAME + 2)
 
@@ -88,14 +73,12 @@
  * These locks are exported if CONFIG_PROVE_RCU so that accessors in
  * cgroup.h can use them for lockdep annotations.
  */
-#ifdef CONFIG_PROVE_RCU
 DEFINE_MUTEX(cgroup_mutex);
 DEFINE_SPINLOCK(css_set_lock);
+
+#ifdef CONFIG_PROVE_RCU
 EXPORT_SYMBOL_GPL(cgroup_mutex);
 EXPORT_SYMBOL_GPL(css_set_lock);
-#else
-static DEFINE_MUTEX(cgroup_mutex);
-static DEFINE_SPINLOCK(css_set_lock);
 #endif
 
 /*
@@ -110,12 +93,6 @@ static DEFINE_SPINLOCK(cgroup_idr_lock);
  */
 static DEFINE_SPINLOCK(cgroup_file_kn_lock);
 
-/*
- * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
- * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
- */
-static DEFINE_SPINLOCK(release_agent_path_lock);
-
 struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
 
 #define cgroup_assert_mutex_or_rcu_locked()				\
@@ -131,15 +108,9 @@ struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
  */
 static struct workqueue_struct *cgroup_destroy_wq;
 
-/*
- * pidlist destructions need to be flushed on cgroup destruction.  Use a
- * separate workqueue as flush domain.
- */
-static struct workqueue_struct *cgroup_pidlist_destroy_wq;
-
 /* generate an array of cgroup subsystem pointers */
 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
-static struct cgroup_subsys *cgroup_subsys[] = {
+struct cgroup_subsys *cgroup_subsys[] = {
 #include <linux/cgroup_subsys.h>
 };
 #undef SUBSYS
@@ -186,9 +157,6 @@ EXPORT_SYMBOL_GPL(cgrp_dfl_root);
  */
 static bool cgrp_dfl_visible;
 
-/* Controllers blocked by the commandline in v1 */
-static u16 cgroup_no_v1_mask;
-
 /* some controllers are not supported in the default hierarchy */
 static u16 cgrp_dfl_inhibit_ss_mask;
 
@@ -196,8 +164,7 @@ static u16 cgrp_dfl_inhibit_ss_mask;
 static unsigned long cgrp_dfl_implicit_ss_mask;
 
 /* The list of hierarchy roots */
-
-static LIST_HEAD(cgroup_roots);
+LIST_HEAD(cgroup_roots);
 static int cgroup_root_count;
 
 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
@@ -235,10 +202,7 @@ static u16 have_canfork_callback __read_mostly;
 
 static struct file_system_type cgroup2_fs_type;
 static struct cftype cgroup_dfl_base_files[];
-static struct cftype cgroup_legacy_base_files[];
 
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 static int cgroup_apply_control(struct cgroup *cgrp);
 static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
 static void css_task_iter_advance(struct css_task_iter *it);
@@ -259,7 +223,7 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
  * is fine for individual subsystems but unsuitable for cgroup core.  This
  * is slower static_key_enabled() based test indexed by @ssid.
  */
-static bool cgroup_ssid_enabled(int ssid)
+bool cgroup_ssid_enabled(int ssid)
 {
 	if (CGROUP_SUBSYS_COUNT == 0)
 		return false;
@@ -267,11 +231,6 @@ static bool cgroup_ssid_enabled(int ssid)
 	return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
 }
 
-static bool cgroup_ssid_no_v1(int ssid)
-{
-	return cgroup_no_v1_mask & (1 << ssid);
-}
-
 /**
  * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
  * @cgrp: the cgroup of interest
@@ -325,7 +284,7 @@ static bool cgroup_ssid_no_v1(int ssid)
  *
  * - debug: disallowed on the default hierarchy.
  */
-static bool cgroup_on_dfl(const struct cgroup *cgrp)
+bool cgroup_on_dfl(const struct cgroup *cgrp)
 {
 	return cgrp->root == &cgrp_dfl_root;
 }
@@ -481,12 +440,6 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
 	return css;
 }
 
-/* convenient tests for these bits */
-static inline bool cgroup_is_dead(const struct cgroup *cgrp)
-{
-	return !(cgrp->self.flags & CSS_ONLINE);
-}
-
 static void cgroup_get(struct cgroup *cgrp)
 {
 	WARN_ON_ONCE(cgroup_is_dead(cgrp));
@@ -518,11 +471,6 @@ struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
 }
 EXPORT_SYMBOL_GPL(of_css);
 
-static int notify_on_release(const struct cgroup *cgrp)
-{
-	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
-}
-
 /**
  * for_each_css - iterate all css's of a cgroup
  * @css: the iteration cursor
@@ -553,15 +501,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 		else
 
 /**
- * for_each_subsys - iterate all enabled cgroup subsystems
- * @ss: the iteration cursor
- * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- */
-#define for_each_subsys(ss, ssid)					\
-	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
-	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
-
-/**
  * do_each_subsys_mask - filter for_each_subsys with a bitmask
  * @ss: the iteration cursor
  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
@@ -585,10 +524,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 	}								\
 } while (false)
 
-/* iterate across the hierarchies */
-#define for_each_root(root)						\
-	list_for_each_entry((root), &cgroup_roots, root_list)
-
 /* iterate over child cgrps, lock should be held throughout iteration */
 #define cgroup_for_each_live_child(child, cgrp)				\
 	list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
@@ -615,29 +550,6 @@ static int notify_on_release(const struct cgroup *cgrp)
 			;						\
 		else
 
-static void cgroup_release_agent(struct work_struct *work);
-static void check_for_release(struct cgroup *cgrp);
-
-/*
- * A cgroup can be associated with multiple css_sets as different tasks may
- * belong to different cgroups on different hierarchies.  In the other
- * direction, a css_set is naturally associated with multiple cgroups.
- * This M:N relationship is represented by the following link structure
- * which exists for each association and allows traversing the associations
- * from both sides.
- */
-struct cgrp_cset_link {
-	/* the cgroup and css_set this link associates */
-	struct cgroup		*cgrp;
-	struct css_set		*cset;
-
-	/* list of cgrp_cset_links anchored at cgrp->cset_links */
-	struct list_head	cset_link;
-
-	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
-	struct list_head	cgrp_link;
-};
-
 /*
  * The default css_set - used by init and its children prior to any
  * hierarchies being mounted. It contains a pointer to the root state
@@ -1138,7 +1050,7 @@ static struct css_set *find_css_set(struct css_set *old_cset,
 	return cset;
 }
 
-static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
 {
 	struct cgroup *root_cgrp = kf_root->kn->priv;
 
@@ -1283,8 +1195,8 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
  * Return the cgroup for "task" from the given hierarchy. Must be
  * called with cgroup_mutex and css_set_lock held.
  */
-static struct cgroup *task_cgroup_from_root(struct task_struct *task,
-					    struct cgroup_root *root)
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+				     struct cgroup_root *root)
 {
 	/*
 	 * No need to lock the task - since we hold cgroup_mutex the
@@ -1321,7 +1233,6 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task,
  */
 
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
-static const struct file_operations proc_cgroupstats_operations;
 
 static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
 			      char *buf)
@@ -1415,7 +1326,7 @@ static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
  * inaccessible any time.  If the caller intends to continue to access the
  * cgroup, it should pin it before invoking this function.
  */
-static void cgroup_kn_unlock(struct kernfs_node *kn)
+void cgroup_kn_unlock(struct kernfs_node *kn)
 {
 	struct cgroup *cgrp;
 
@@ -1447,8 +1358,7 @@ static void cgroup_kn_unlock(struct kernfs_node *kn)
  * locking under kernfs active protection and allows all kernfs operations
  * including self-removal.
  */
-static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn,
-					  bool drain_offline)
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline)
 {
 	struct cgroup *cgrp;
 
@@ -1559,7 +1469,7 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
 	return ret;
 }
 
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 {
 	struct cgroup *dcgrp = &dst_root->cgrp;
 	struct cgroup_subsys *ss;
@@ -1656,8 +1566,7 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 	return len;
 }
 
-static int cgroup_show_options(struct seq_file *seq,
-			       struct kernfs_root *kf_root)
+static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
 {
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 	struct cgroup_subsys *ss;
@@ -2311,7 +2220,7 @@ static void cgroup_kill_sb(struct super_block *sb)
 	kernfs_kill_sb(sb);
 }
 
-static struct file_system_type cgroup_fs_type = {
+struct file_system_type cgroup_fs_type = {
 	.name = "cgroup",
 	.mount = cgroup_mount,
 	.kill_sb = cgroup_kill_sb,
@@ -2325,8 +2234,8 @@ static struct file_system_type cgroup2_fs_type = {
 	.fs_flags = FS_USERNS_MOUNT,
 };
 
-static int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
-				 struct cgroup_namespace *ns)
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+			  struct cgroup_namespace *ns)
 {
 	struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
 
@@ -2616,7 +2525,7 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
  * zero for migration destination cgroups with tasks so that child cgroups
  * don't compete against tasks.
  */
-static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
+bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
 {
 	return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
 		!dst_cgrp->subtree_control;
@@ -2629,7 +2538,7 @@ static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
  * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst().  See
  * those functions for details.
  */
-static void cgroup_migrate_finish(struct list_head *preloaded_csets)
+void cgroup_migrate_finish(struct list_head *preloaded_csets)
 {
 	struct css_set *cset, *tmp_cset;
 
@@ -2662,9 +2571,9 @@ static void cgroup_migrate_finish(struct list_head *preloaded_csets)
  * into play and the preloaded css_sets are guaranteed to cover all
  * migrations.
  */
-static void cgroup_migrate_add_src(struct css_set *src_cset,
-				   struct cgroup *dst_cgrp,
-				   struct list_head *preloaded_csets)
+void cgroup_migrate_add_src(struct css_set *src_cset,
+			    struct cgroup *dst_cgrp,
+			    struct list_head *preloaded_csets)
 {
 	struct cgroup *src_cgrp;
 
@@ -2709,7 +2618,7 @@ static void cgroup_migrate_add_src(struct css_set *src_cset,
  * using cgroup_migrate(), cgroup_migrate_finish() must be called on
  * @preloaded_csets.
  */
-static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
+int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
 {
 	LIST_HEAD(csets);
 	struct css_set *src_cset, *tmp_cset;
@@ -2773,8 +2682,8 @@ static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
  * decided for all targets by invoking group_migrate_prepare_dst() before
  * actually starting migrating.
  */
-static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
-			  struct cgroup_root *root)
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+		   struct cgroup_root *root)
 {
 	struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
 	struct task_struct *task;
@@ -2806,8 +2715,8 @@ static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
  *
  * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
  */
-static int cgroup_attach_task(struct cgroup *dst_cgrp,
-			      struct task_struct *leader, bool threadgroup)
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+		       bool threadgroup)
 {
 	LIST_HEAD(preloaded_csets);
 	struct task_struct *task;
@@ -2888,8 +2797,8 @@ static int cgroup_procs_write_permission(struct task_struct *task,
  * function to attach either it or all tasks in its threadgroup. Will lock
  * cgroup_mutex and threadgroup.
  */
-static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
-				    size_t nbytes, loff_t off, bool threadgroup)
+ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+			     size_t nbytes, loff_t off, bool threadgroup)
 {
 	struct task_struct *tsk;
 	struct cgroup_subsys *ss;
@@ -2950,86 +2859,12 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
 	return ret ?: nbytes;
 }
 
-/**
- * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
- * @from: attach to all cgroups of a given task
- * @tsk: the task to be attached
- */
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
-{
-	struct cgroup_root *root;
-	int retval = 0;
-
-	mutex_lock(&cgroup_mutex);
-	percpu_down_write(&cgroup_threadgroup_rwsem);
-	for_each_root(root) {
-		struct cgroup *from_cgrp;
-
-		if (root == &cgrp_dfl_root)
-			continue;
-
-		spin_lock_irq(&css_set_lock);
-		from_cgrp = task_cgroup_from_root(from, root);
-		spin_unlock_irq(&css_set_lock);
-
-		retval = cgroup_attach_task(from_cgrp, tsk, false);
-		if (retval)
-			break;
-	}
-	percpu_up_write(&cgroup_threadgroup_rwsem);
-	mutex_unlock(&cgroup_mutex);
-
-	return retval;
-}
-EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-
-static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
-				  char *buf, size_t nbytes, loff_t off)
-{
-	return __cgroup_procs_write(of, buf, nbytes, off, false);
-}
-
-static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
-				  char *buf, size_t nbytes, loff_t off)
+ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			   loff_t off)
 {
 	return __cgroup_procs_write(of, buf, nbytes, off, true);
 }
 
-static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
-					  char *buf, size_t nbytes, loff_t off)
-{
-	struct cgroup *cgrp;
-
-	BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
-
-	cgrp = cgroup_kn_lock_live(of->kn, false);
-	if (!cgrp)
-		return -ENODEV;
-	spin_lock(&release_agent_path_lock);
-	strlcpy(cgrp->root->release_agent_path, strstrip(buf),
-		sizeof(cgrp->root->release_agent_path));
-	spin_unlock(&release_agent_path_lock);
-	cgroup_kn_unlock(of->kn);
-	return nbytes;
-}
-
-static int cgroup_release_agent_show(struct seq_file *seq, void *v)
-{
-	struct cgroup *cgrp = seq_css(seq)->cgroup;
-
-	spin_lock(&release_agent_path_lock);
-	seq_puts(seq, cgrp->root->release_agent_path);
-	spin_unlock(&release_agent_path_lock);
-	seq_putc(seq, '\n');
-	return 0;
-}
-
-static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
-{
-	seq_puts(seq, "0\n");
-	return 0;
-}
-
 static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
 {
 	struct cgroup_subsys *ss;
@@ -3131,7 +2966,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
  * controller while the previous css is still around.  This function grabs
  * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
  */
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
 	__acquires(&cgroup_mutex)
 {
 	struct cgroup *dsct;
@@ -3610,48 +3445,6 @@ static struct kernfs_ops cgroup_kf_ops = {
 	.seq_show		= cgroup_seqfile_show,
 };
 
-/*
- * cgroup_rename - Only allow simple rename of directories in place.
- */
-static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-			 const char *new_name_str)
-{
-	struct cgroup *cgrp = kn->priv;
-	int ret;
-
-	if (kernfs_type(kn) != KERNFS_DIR)
-		return -ENOTDIR;
-	if (kn->parent != new_parent)
-		return -EIO;
-
-	/*
-	 * This isn't a proper migration and its usefulness is very
-	 * limited.  Disallow on the default hierarchy.
-	 */
-	if (cgroup_on_dfl(cgrp))
-		return -EPERM;
-
-	/*
-	 * We're gonna grab cgroup_mutex which nests outside kernfs
-	 * active_ref.  kernfs_rename() doesn't require active_ref
-	 * protection.  Break them before grabbing cgroup_mutex.
-	 */
-	kernfs_break_active_protection(new_parent);
-	kernfs_break_active_protection(kn);
-
-	mutex_lock(&cgroup_mutex);
-
-	ret = kernfs_rename(kn, new_parent, new_name_str);
-	if (!ret)
-		trace_cgroup_rename(cgrp);
-
-	mutex_unlock(&cgroup_mutex);
-
-	kernfs_unbreak_active_protection(kn);
-	kernfs_unbreak_active_protection(new_parent);
-	return ret;
-}
-
 /* set uid and gid of cgroup dirs and files to that of the creator */
 static int cgroup_kn_set_ugid(struct kernfs_node *kn)
 {
@@ -3948,26 +3741,6 @@ void cgroup_file_notify(struct cgroup_file *cfile)
 }
 
 /**
- * cgroup_task_count - count the number of tasks in a cgroup.
- * @cgrp: the cgroup in question
- *
- * Return the number of tasks in the cgroup.  The returned number can be
- * higher than the actual number of tasks due to css_set references from
- * namespace roots and temporary usages.
- */
-static int cgroup_task_count(const struct cgroup *cgrp)
-{
-	int count = 0;
-	struct cgrp_cset_link *link;
-
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &cgrp->cset_links, cset_link)
-		count += atomic_read(&link->cset->refcount);
-	spin_unlock_irq(&css_set_lock);
-	return count;
-}
-
-/**
  * css_next_child - find the next child of a given css
  * @pos: the current position (%NULL to initiate traversal)
  * @parent: css whose children to walk
@@ -4365,70 +4138,6 @@ void css_task_iter_end(struct css_task_iter *it)
 		put_task_struct(it->cur_task);
 }
 
-/**
- * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
- * @to: cgroup to which the tasks will be moved
- * @from: cgroup in which the tasks currently reside
- *
- * Locking rules between cgroup_post_fork() and the migration path
- * guarantee that, if a task is forking while being migrated, the new child
- * is guaranteed to be either visible in the source cgroup after the
- * parent's migration is complete or put into the target cgroup.  No task
- * can slip out of migration through forking.
- */
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
-{
-	LIST_HEAD(preloaded_csets);
-	struct cgrp_cset_link *link;
-	struct css_task_iter it;
-	struct task_struct *task;
-	int ret;
-
-	if (cgroup_on_dfl(to))
-		return -EINVAL;
-
-	if (!cgroup_may_migrate_to(to))
-		return -EBUSY;
-
-	mutex_lock(&cgroup_mutex);
-
-	percpu_down_write(&cgroup_threadgroup_rwsem);
-
-	/* all tasks in @from are being moved, all csets are source */
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &from->cset_links, cset_link)
-		cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
-	spin_unlock_irq(&css_set_lock);
-
-	ret = cgroup_migrate_prepare_dst(&preloaded_csets);
-	if (ret)
-		goto out_err;
-
-	/*
-	 * Migrate tasks one-by-one until @from is empty.  This fails iff
-	 * ->can_attach() fails.
-	 */
-	do {
-		css_task_iter_start(&from->self, &it);
-		task = css_task_iter_next(&it);
-		if (task)
-			get_task_struct(task);
-		css_task_iter_end(&it);
-
-		if (task) {
-			ret = cgroup_migrate(task, false, to->root);
-			if (!ret)
-				trace_cgroup_transfer_tasks(to, task, false);
-			put_task_struct(task);
-		}
-	} while (task && !ret);
-out_err:
-	cgroup_migrate_finish(&preloaded_csets);
-	percpu_up_write(&cgroup_threadgroup_rwsem);
-	mutex_unlock(&cgroup_mutex);
-	return ret;
-}
-
 static void cgroup_procs_release(struct kernfs_open_file *of)
 {
 	if (of->priv) {
@@ -4483,456 +4192,6 @@ static int cgroup_procs_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-/*
- * Stuff for reading the 'tasks'/'procs' files.
- *
- * Reading this file can return large amounts of data if a cgroup has
- * *lots* of attached tasks. So it may need several calls to read(),
- * but we cannot guarantee that the information we produce is correct
- * unless we produce it entirely atomically.
- *
- */
-
-/* which pidlist file are we talking about? */
-enum cgroup_filetype {
-	CGROUP_FILE_PROCS,
-	CGROUP_FILE_TASKS,
-};
-
-/*
- * A pidlist is a list of pids that virtually represents the contents of one
- * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
- * a pair (one each for procs, tasks) for each pid namespace that's relevant
- * to the cgroup.
- */
-struct cgroup_pidlist {
-	/*
-	 * used to find which pidlist is wanted. doesn't change as long as
-	 * this particular list stays in the list.
-	*/
-	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
-	/* array of xids */
-	pid_t *list;
-	/* how many elements the above list has */
-	int length;
-	/* each of these stored in a list by its cgroup */
-	struct list_head links;
-	/* pointer to the cgroup we belong to, for list removal purposes */
-	struct cgroup *owner;
-	/* for delayed destruction */
-	struct delayed_work destroy_dwork;
-};
-
-/*
- * The following two functions "fix" the issue where there are more pids
- * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
- * TODO: replace with a kernel-wide solution to this problem
- */
-#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
-static void *pidlist_allocate(int count)
-{
-	if (PIDLIST_TOO_LARGE(count))
-		return vmalloc(count * sizeof(pid_t));
-	else
-		return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
-}
-
-static void pidlist_free(void *p)
-{
-	kvfree(p);
-}
-
-/*
- * Used to destroy all pidlists lingering waiting for destroy timer.  None
- * should be left afterwards.
- */
-static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
-{
-	struct cgroup_pidlist *l, *tmp_l;
-
-	mutex_lock(&cgrp->pidlist_mutex);
-	list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
-		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
-	mutex_unlock(&cgrp->pidlist_mutex);
-
-	flush_workqueue(cgroup_pidlist_destroy_wq);
-	BUG_ON(!list_empty(&cgrp->pidlists));
-}
-
-static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
-{
-	struct delayed_work *dwork = to_delayed_work(work);
-	struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
-						destroy_dwork);
-	struct cgroup_pidlist *tofree = NULL;
-
-	mutex_lock(&l->owner->pidlist_mutex);
-
-	/*
-	 * Destroy iff we didn't get queued again.  The state won't change
-	 * as destroy_dwork can only be queued while locked.
-	 */
-	if (!delayed_work_pending(dwork)) {
-		list_del(&l->links);
-		pidlist_free(l->list);
-		put_pid_ns(l->key.ns);
-		tofree = l;
-	}
-
-	mutex_unlock(&l->owner->pidlist_mutex);
-	kfree(tofree);
-}
-
-/*
- * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
- * Returns the number of unique elements.
- */
-static int pidlist_uniq(pid_t *list, int length)
-{
-	int src, dest = 1;
-
-	/*
-	 * we presume the 0th element is unique, so i starts at 1. trivial
-	 * edge cases first; no work needs to be done for either
-	 */
-	if (length == 0 || length == 1)
-		return length;
-	/* src and dest walk down the list; dest counts unique elements */
-	for (src = 1; src < length; src++) {
-		/* find next unique element */
-		while (list[src] == list[src-1]) {
-			src++;
-			if (src == length)
-				goto after;
-		}
-		/* dest always points to where the next unique element goes */
-		list[dest] = list[src];
-		dest++;
-	}
-after:
-	return dest;
-}
-
-/*
- * The two pid files - task and cgroup.procs - guaranteed that the result
- * is sorted, which forced this whole pidlist fiasco.  As pid order is
- * different per namespace, each namespace needs differently sorted list,
- * making it impossible to use, for example, single rbtree of member tasks
- * sorted by task pointer.  As pidlists can be fairly large, allocating one
- * per open file is dangerous, so cgroup had to implement shared pool of
- * pidlists keyed by cgroup and namespace.
- */
-static int cmppid(const void *a, const void *b)
-{
-	return *(pid_t *)a - *(pid_t *)b;
-}
-
-static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
-						  enum cgroup_filetype type)
-{
-	struct cgroup_pidlist *l;
-	/* don't need task_nsproxy() if we're looking at ourself */
-	struct pid_namespace *ns = task_active_pid_ns(current);
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	list_for_each_entry(l, &cgrp->pidlists, links)
-		if (l->key.type == type && l->key.ns == ns)
-			return l;
-	return NULL;
-}
-
-/*
- * find the appropriate pidlist for our purpose (given procs vs tasks)
- * returns with the lock on that pidlist already held, and takes care
- * of the use count, or returns NULL with no locks held if we're out of
- * memory.
- */
-static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
-						enum cgroup_filetype type)
-{
-	struct cgroup_pidlist *l;
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	l = cgroup_pidlist_find(cgrp, type);
-	if (l)
-		return l;
-
-	/* entry not found; create a new one */
-	l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
-	if (!l)
-		return l;
-
-	INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
-	l->key.type = type;
-	/* don't need task_nsproxy() if we're looking at ourself */
-	l->key.ns = get_pid_ns(task_active_pid_ns(current));
-	l->owner = cgrp;
-	list_add(&l->links, &cgrp->pidlists);
-	return l;
-}
-
-/*
- * Load a cgroup's pidarray with either procs' tgids or tasks' pids
- */
-static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
-			      struct cgroup_pidlist **lp)
-{
-	pid_t *array;
-	int length;
-	int pid, n = 0; /* used for populating the array */
-	struct css_task_iter it;
-	struct task_struct *tsk;
-	struct cgroup_pidlist *l;
-
-	lockdep_assert_held(&cgrp->pidlist_mutex);
-
-	/*
-	 * If cgroup gets more users after we read count, we won't have
-	 * enough space - tough.  This race is indistinguishable to the
-	 * caller from the case that the additional cgroup users didn't
-	 * show up until sometime later on.
-	 */
-	length = cgroup_task_count(cgrp);
-	array = pidlist_allocate(length);
-	if (!array)
-		return -ENOMEM;
-	/* now, populate the array */
-	css_task_iter_start(&cgrp->self, &it);
-	while ((tsk = css_task_iter_next(&it))) {
-		if (unlikely(n == length))
-			break;
-		/* get tgid or pid for procs or tasks file respectively */
-		if (type == CGROUP_FILE_PROCS)
-			pid = task_tgid_vnr(tsk);
-		else
-			pid = task_pid_vnr(tsk);
-		if (pid > 0) /* make sure to only use valid results */
-			array[n++] = pid;
-	}
-	css_task_iter_end(&it);
-	length = n;
-	/* now sort & (if procs) strip out duplicates */
-	sort(array, length, sizeof(pid_t), cmppid, NULL);
-	if (type == CGROUP_FILE_PROCS)
-		length = pidlist_uniq(array, length);
-
-	l = cgroup_pidlist_find_create(cgrp, type);
-	if (!l) {
-		pidlist_free(array);
-		return -ENOMEM;
-	}
-
-	/* store array, freeing old if necessary */
-	pidlist_free(l->list);
-	l->list = array;
-	l->length = length;
-	*lp = l;
-	return 0;
-}
-
-/**
- * cgroupstats_build - build and fill cgroupstats
- * @stats: cgroupstats to fill information into
- * @dentry: A dentry entry belonging to the cgroup for which stats have
- * been requested.
- *
- * Build and fill cgroupstats so that taskstats can export it to user
- * space.
- */
-int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
-{
-	struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
-	struct cgroup *cgrp;
-	struct css_task_iter it;
-	struct task_struct *tsk;
-
-	/* it should be kernfs_node belonging to cgroupfs and is a directory */
-	if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
-	    kernfs_type(kn) != KERNFS_DIR)
-		return -EINVAL;
-
-	mutex_lock(&cgroup_mutex);
-
-	/*
-	 * We aren't being called from kernfs and there's no guarantee on
-	 * @kn->priv's validity.  For this and css_tryget_online_from_dir(),
-	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
-	 */
-	rcu_read_lock();
-	cgrp = rcu_dereference(kn->priv);
-	if (!cgrp || cgroup_is_dead(cgrp)) {
-		rcu_read_unlock();
-		mutex_unlock(&cgroup_mutex);
-		return -ENOENT;
-	}
-	rcu_read_unlock();
-
-	css_task_iter_start(&cgrp->self, &it);
-	while ((tsk = css_task_iter_next(&it))) {
-		switch (tsk->state) {
-		case TASK_RUNNING:
-			stats->nr_running++;
-			break;
-		case TASK_INTERRUPTIBLE:
-			stats->nr_sleeping++;
-			break;
-		case TASK_UNINTERRUPTIBLE:
-			stats->nr_uninterruptible++;
-			break;
-		case TASK_STOPPED:
-			stats->nr_stopped++;
-			break;
-		default:
-			if (delayacct_is_task_waiting_on_io(tsk))
-				stats->nr_io_wait++;
-			break;
-		}
-	}
-	css_task_iter_end(&it);
-
-	mutex_unlock(&cgroup_mutex);
-	return 0;
-}
-
-
-/*
- * seq_file methods for the tasks/procs files. The seq_file position is the
- * next pid to display; the seq_file iterator is a pointer to the pid
- * in the cgroup->l->list array.
- */
-
-static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
-{
-	/*
-	 * Initially we receive a position value that corresponds to
-	 * one more than the last pid shown (or 0 on the first call or
-	 * after a seek to the start). Use a binary-search to find the
-	 * next pid to display, if any
-	 */
-	struct kernfs_open_file *of = s->private;
-	struct cgroup *cgrp = seq_css(s)->cgroup;
-	struct cgroup_pidlist *l;
-	enum cgroup_filetype type = seq_cft(s)->private;
-	int index = 0, pid = *pos;
-	int *iter, ret;
-
-	mutex_lock(&cgrp->pidlist_mutex);
-
-	/*
-	 * !NULL @of->priv indicates that this isn't the first start()
-	 * after open.  If the matching pidlist is around, we can use that.
-	 * Look for it.  Note that @of->priv can't be used directly.  It
-	 * could already have been destroyed.
-	 */
-	if (of->priv)
-		of->priv = cgroup_pidlist_find(cgrp, type);
-
-	/*
-	 * Either this is the first start() after open or the matching
-	 * pidlist has been destroyed inbetween.  Create a new one.
-	 */
-	if (!of->priv) {
-		ret = pidlist_array_load(cgrp, type,
-					 (struct cgroup_pidlist **)&of->priv);
-		if (ret)
-			return ERR_PTR(ret);
-	}
-	l = of->priv;
-
-	if (pid) {
-		int end = l->length;
-
-		while (index < end) {
-			int mid = (index + end) / 2;
-			if (l->list[mid] == pid) {
-				index = mid;
-				break;
-			} else if (l->list[mid] <= pid)
-				index = mid + 1;
-			else
-				end = mid;
-		}
-	}
-	/* If we're off the end of the array, we're done */
-	if (index >= l->length)
-		return NULL;
-	/* Update the abstract position to be the actual pid that we found */
-	iter = l->list + index;
-	*pos = *iter;
-	return iter;
-}
-
-static void cgroup_pidlist_stop(struct seq_file *s, void *v)
-{
-	struct kernfs_open_file *of = s->private;
-	struct cgroup_pidlist *l = of->priv;
-
-	if (l)
-		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
-				 CGROUP_PIDLIST_DESTROY_DELAY);
-	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
-}
-
-static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
-{
-	struct kernfs_open_file *of = s->private;
-	struct cgroup_pidlist *l = of->priv;
-	pid_t *p = v;
-	pid_t *end = l->list + l->length;
-	/*
-	 * Advance to the next pid in the array. If this goes off the
-	 * end, we're done
-	 */
-	p++;
-	if (p >= end) {
-		return NULL;
-	} else {
-		*pos = *p;
-		return p;
-	}
-}
-
-static int cgroup_pidlist_show(struct seq_file *s, void *v)
-{
-	seq_printf(s, "%d\n", *(int *)v);
-
-	return 0;
-}
-
-static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
-					 struct cftype *cft)
-{
-	return notify_on_release(css->cgroup);
-}
-
-static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
-					  struct cftype *cft, u64 val)
-{
-	if (val)
-		set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
-	else
-		clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
-	return 0;
-}
-
-static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
-				      struct cftype *cft)
-{
-	return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-}
-
-static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
-				       struct cftype *cft, u64 val)
-{
-	if (val)
-		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-	else
-		clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-	return 0;
-}
-
 /* cgroup core interface files for the default hierarchy */
 static struct cftype cgroup_dfl_base_files[] = {
 	{
@@ -4962,51 +4221,6 @@ static struct cftype cgroup_dfl_base_files[] = {
 	{ }	/* terminate */
 };
 
-/* cgroup core interface files for the legacy hierarchies */
-static struct cftype cgroup_legacy_base_files[] = {
-	{
-		.name = "cgroup.procs",
-		.seq_start = cgroup_pidlist_start,
-		.seq_next = cgroup_pidlist_next,
-		.seq_stop = cgroup_pidlist_stop,
-		.seq_show = cgroup_pidlist_show,
-		.private = CGROUP_FILE_PROCS,
-		.write = cgroup_procs_write,
-	},
-	{
-		.name = "cgroup.clone_children",
-		.read_u64 = cgroup_clone_children_read,
-		.write_u64 = cgroup_clone_children_write,
-	},
-	{
-		.name = "cgroup.sane_behavior",
-		.flags = CFTYPE_ONLY_ON_ROOT,
-		.seq_show = cgroup_sane_behavior_show,
-	},
-	{
-		.name = "tasks",
-		.seq_start = cgroup_pidlist_start,
-		.seq_next = cgroup_pidlist_next,
-		.seq_stop = cgroup_pidlist_stop,
-		.seq_show = cgroup_pidlist_show,
-		.private = CGROUP_FILE_TASKS,
-		.write = cgroup_tasks_write,
-	},
-	{
-		.name = "notify_on_release",
-		.read_u64 = cgroup_read_notify_on_release,
-		.write_u64 = cgroup_write_notify_on_release,
-	},
-	{
-		.name = "release_agent",
-		.flags = CFTYPE_ONLY_ON_ROOT,
-		.seq_show = cgroup_release_agent_show,
-		.write = cgroup_release_agent_write,
-		.max_write_len = PATH_MAX - 1,
-	},
-	{ }	/* terminate */
-};
-
 /*
  * css destruction is four-stage process.
  *
@@ -5792,15 +5006,6 @@ static int __init cgroup_wq_init(void)
 	 */
 	cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
 	BUG_ON(!cgroup_destroy_wq);
-
-	/*
-	 * Used to destroy pidlists and separate to serve as flush domain.
-	 * Cap @max_active to 1 too.
-	 */
-	cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
-						    0, 1);
-	BUG_ON(!cgroup_pidlist_destroy_wq);
-
 	return 0;
 }
 core_initcall(cgroup_wq_init);
@@ -5883,42 +5088,6 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 	return retval;
 }
 
-/* Display information about each subsystem and each hierarchy */
-static int proc_cgroupstats_show(struct seq_file *m, void *v)
-{
-	struct cgroup_subsys *ss;
-	int i;
-
-	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
-	/*
-	 * ideally we don't want subsystems moving around while we do this.
-	 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
-	 * subsys/hierarchy state.
-	 */
-	mutex_lock(&cgroup_mutex);
-
-	for_each_subsys(ss, i)
-		seq_printf(m, "%s\t%d\t%d\t%d\n",
-			   ss->legacy_name, ss->root->hierarchy_id,
-			   atomic_read(&ss->root->nr_cgrps),
-			   cgroup_ssid_enabled(i));
-
-	mutex_unlock(&cgroup_mutex);
-	return 0;
-}
-
-static int cgroupstats_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, proc_cgroupstats_show, NULL);
-}
-
-static const struct file_operations proc_cgroupstats_operations = {
-	.open = cgroupstats_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
-
 /**
  * cgroup_fork - initialize cgroup related fields during copy_process()
  * @child: pointer to task_struct of forking parent process.
@@ -6098,76 +5267,6 @@ void cgroup_free(struct task_struct *task)
 	put_css_set(cset);
 }
 
-static void check_for_release(struct cgroup *cgrp)
-{
-	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
-	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
-		schedule_work(&cgrp->release_agent_work);
-}
-
-/*
- * Notify userspace when a cgroup is released, by running the
- * configured release agent with the name of the cgroup (path
- * relative to the root of cgroup file system) as the argument.
- *
- * Most likely, this user command will try to rmdir this cgroup.
- *
- * This races with the possibility that some other task will be
- * attached to this cgroup before it is removed, or that some other
- * user task will 'mkdir' a child cgroup of this cgroup.  That's ok.
- * The presumed 'rmdir' will fail quietly if this cgroup is no longer
- * unused, and this cgroup will be reprieved from its death sentence,
- * to continue to serve a useful existence.  Next time it's released,
- * we will get notified again, if it still has 'notify_on_release' set.
- *
- * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
- * means only wait until the task is successfully execve()'d.  The
- * separate release agent task is forked by call_usermodehelper(),
- * then control in this thread returns here, without waiting for the
- * release agent task.  We don't bother to wait because the caller of
- * this routine has no use for the exit status of the release agent
- * task, so no sense holding our caller up for that.
- */
-static void cgroup_release_agent(struct work_struct *work)
-{
-	struct cgroup *cgrp =
-		container_of(work, struct cgroup, release_agent_work);
-	char *pathbuf = NULL, *agentbuf = NULL;
-	char *argv[3], *envp[3];
-	int ret;
-
-	mutex_lock(&cgroup_mutex);
-
-	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
-	agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
-	if (!pathbuf || !agentbuf)
-		goto out;
-
-	spin_lock_irq(&css_set_lock);
-	ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
-	spin_unlock_irq(&css_set_lock);
-	if (ret < 0 || ret >= PATH_MAX)
-		goto out;
-
-	argv[0] = agentbuf;
-	argv[1] = pathbuf;
-	argv[2] = NULL;
-
-	/* minimal command environment */
-	envp[0] = "HOME=/";
-	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-	envp[2] = NULL;
-
-	mutex_unlock(&cgroup_mutex);
-	call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
-	goto out_free;
-out:
-	mutex_unlock(&cgroup_mutex);
-out_free:
-	kfree(agentbuf);
-	kfree(pathbuf);
-}
-
 static int __init cgroup_disable(char *str)
 {
 	struct cgroup_subsys *ss;
@@ -6189,33 +5288,6 @@ static int __init cgroup_disable(char *str)
 }
 __setup("cgroup_disable=", cgroup_disable);
 
-static int __init cgroup_no_v1(char *str)
-{
-	struct cgroup_subsys *ss;
-	char *token;
-	int i;
-
-	while ((token = strsep(&str, ",")) != NULL) {
-		if (!*token)
-			continue;
-
-		if (!strcmp(token, "all")) {
-			cgroup_no_v1_mask = U16_MAX;
-			break;
-		}
-
-		for_each_subsys(ss, i) {
-			if (strcmp(token, ss->name) &&
-			    strcmp(token, ss->legacy_name))
-				continue;
-
-			cgroup_no_v1_mask |= 1 << i;
-		}
-	}
-	return 1;
-}
-__setup("cgroup_no_v1=", cgroup_no_v1);
-
 /**
  * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
  * @dentry: directory dentry of interest
@@ -6557,149 +5629,3 @@ void cgroup_bpf_update(struct cgroup *cgrp,
 	mutex_unlock(&cgroup_mutex);
 }
 #endif /* CONFIG_CGROUP_BPF */
-
-#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *
-debug_css_alloc(struct cgroup_subsys_state *parent_css)
-{
-	struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
-
-	if (!css)
-		return ERR_PTR(-ENOMEM);
-
-	return css;
-}
-
-static void debug_css_free(struct cgroup_subsys_state *css)
-{
-	kfree(css);
-}
-
-static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
-				struct cftype *cft)
-{
-	return cgroup_task_count(css->cgroup);
-}
-
-static u64 current_css_set_read(struct cgroup_subsys_state *css,
-				struct cftype *cft)
-{
-	return (u64)(unsigned long)current->cgroups;
-}
-
-static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
-					 struct cftype *cft)
-{
-	u64 count;
-
-	rcu_read_lock();
-	count = atomic_read(&task_css_set(current)->refcount);
-	rcu_read_unlock();
-	return count;
-}
-
-static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
-{
-	struct cgrp_cset_link *link;
-	struct css_set *cset;
-	char *name_buf;
-
-	name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
-	if (!name_buf)
-		return -ENOMEM;
-
-	spin_lock_irq(&css_set_lock);
-	rcu_read_lock();
-	cset = rcu_dereference(current->cgroups);
-	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
-		struct cgroup *c = link->cgrp;
-
-		cgroup_name(c, name_buf, NAME_MAX + 1);
-		seq_printf(seq, "Root %d group %s\n",
-			   c->root->hierarchy_id, name_buf);
-	}
-	rcu_read_unlock();
-	spin_unlock_irq(&css_set_lock);
-	kfree(name_buf);
-	return 0;
-}
-
-#define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct seq_file *seq, void *v)
-{
-	struct cgroup_subsys_state *css = seq_css(seq);
-	struct cgrp_cset_link *link;
-
-	spin_lock_irq(&css_set_lock);
-	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
-		struct css_set *cset = link->cset;
-		struct task_struct *task;
-		int count = 0;
-
-		seq_printf(seq, "css_set %p\n", cset);
-
-		list_for_each_entry(task, &cset->tasks, cg_list) {
-			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
-				goto overflow;
-			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
-		}
-
-		list_for_each_entry(task, &cset->mg_tasks, cg_list) {
-			if (count++ > MAX_TASKS_SHOWN_PER_CSS)
-				goto overflow;
-			seq_printf(seq, "  task %d\n", task_pid_vnr(task));
-		}
-		continue;
-	overflow:
-		seq_puts(seq, "  ...\n");
-	}
-	spin_unlock_irq(&css_set_lock);
-	return 0;
-}
-
-static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
-{
-	return (!cgroup_is_populated(css->cgroup) &&
-		!css_has_online_children(&css->cgroup->self));
-}
-
-static struct cftype debug_files[] =  {
-	{
-		.name = "taskcount",
-		.read_u64 = debug_taskcount_read,
-	},
-
-	{
-		.name = "current_css_set",
-		.read_u64 = current_css_set_read,
-	},
-
-	{
-		.name = "current_css_set_refcount",
-		.read_u64 = current_css_set_refcount_read,
-	},
-
-	{
-		.name = "current_css_set_cg_links",
-		.seq_show = current_css_set_cg_links_read,
-	},
-
-	{
-		.name = "cgroup_css_links",
-		.seq_show = cgroup_css_links_read,
-	},
-
-	{
-		.name = "releasable",
-		.read_u64 = releasable_read,
-	},
-
-	{ }	/* terminate */
-};
-
-struct cgroup_subsys debug_cgrp_subsys = {
-	.css_alloc = debug_css_alloc,
-	.css_free = debug_css_free,
-	.legacy_cftypes = debug_files,
-};
-#endif /* CONFIG_CGROUP_DEBUG */
-- 
2.9.3

[PATCH 4/8] cgroup: refactor mount path and clearly distinguish v1 and v2 paths

[Tejun Heo]

While sharing some mechanisms, the mount paths of v1 and v2 are
substantially different.  Their implementations were mixed in
cgroup_mount().  This patch splits them out so that they're easier to
follow and organize.

This patch causes one functional change - the WARN_ON(new_sb) gets
lost.  This is because the actual mounting gets moved to
cgroup_do_mount() and thus @new_sb is no longer accessible by default
to cgroup1_mount().  While we can add it as an explicit out parameter
to cgroup_do_mount(), this part of code hasn't changed and the warning
hasn't triggered for quite a while.  Dropping it should be fine.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/cgroup/cgroup.c | 140 ++++++++++++++++++++++++++++---------------------
 1 file changed, 79 insertions(+), 61 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index cb0d29e..6225c4b 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1991,48 +1991,55 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	return ret;
 }
 
-static struct dentry *cgroup_mount(struct file_system_type *fs_type,
-			 int flags, const char *unused_dev_name,
-			 void *data)
+static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
+				      int flags, struct cgroup_root *root,
+				      unsigned long magic,
+				      struct cgroup_namespace *ns)
 {
-	bool is_v2 = fs_type == &cgroup2_fs_type;
-	struct super_block *pinned_sb = NULL;
-	struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
-	struct cgroup_subsys *ss;
-	struct cgroup_root *root;
-	struct cgroup_sb_opts opts;
 	struct dentry *dentry;
-	int ret;
-	int i;
 	bool new_sb;
 
-	get_cgroup_ns(ns);
-
-	/* Check if the caller has permission to mount. */
-	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
-		put_cgroup_ns(ns);
-		return ERR_PTR(-EPERM);
-	}
+	dentry = kernfs_mount(fs_type, flags, root->kf_root, magic, &new_sb);
 
 	/*
-	 * The first time anyone tries to mount a cgroup, enable the list
-	 * linking each css_set to its tasks and fix up all existing tasks.
+	 * In non-init cgroup namespace, instead of root cgroup's dentry,
+	 * we return the dentry corresponding to the cgroupns->root_cgrp.
 	 */
-	if (!use_task_css_set_links)
-		cgroup_enable_task_cg_lists();
+	if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
+		struct dentry *nsdentry;
+		struct cgroup *cgrp;
 
-	if (is_v2) {
-		if (data) {
-			pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
-			put_cgroup_ns(ns);
-			return ERR_PTR(-EINVAL);
-		}
-		cgrp_dfl_visible = true;
-		root = &cgrp_dfl_root;
-		cgroup_get(&root->cgrp);
-		goto out_mount;
+		mutex_lock(&cgroup_mutex);
+		spin_lock_irq(&css_set_lock);
+
+		cgrp = cset_cgroup_from_root(ns->root_cset, root);
+
+		spin_unlock_irq(&css_set_lock);
+		mutex_unlock(&cgroup_mutex);
+
+		nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
+		dput(dentry);
+		dentry = nsdentry;
 	}
 
+	if (IS_ERR(dentry) || !new_sb)
+		cgroup_put(&root->cgrp);
+
+	return dentry;
+}
+
+static struct dentry *cgroup1_mount(struct file_system_type *fs_type,
+				    int flags, void *data,
+				    unsigned long magic,
+				    struct cgroup_namespace *ns)
+{
+	struct super_block *pinned_sb = NULL;
+	struct cgroup_sb_opts opts;
+	struct cgroup_root *root;
+	struct cgroup_subsys *ss;
+	struct dentry *dentry;
+	int i, ret;
+
 	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
 
 	/* First find the desired set of subsystems */
@@ -2154,47 +2161,58 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 	kfree(opts.release_agent);
 	kfree(opts.name);
 
-	if (ret) {
-		put_cgroup_ns(ns);
+	if (ret)
 		return ERR_PTR(ret);
-	}
-out_mount:
-	dentry = kernfs_mount(fs_type, flags, root->kf_root,
-			      is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
-			      &new_sb);
+
+	dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
+				 CGROUP_SUPER_MAGIC, ns);
 
 	/*
-	 * In non-init cgroup namespace, instead of root cgroup's
-	 * dentry, we return the dentry corresponding to the
-	 * cgroupns->root_cgrp.
+	 * If @pinned_sb, we're reusing an existing root and holding an
+	 * extra ref on its sb.  Mount is complete.  Put the extra ref.
 	 */
-	if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
-		struct dentry *nsdentry;
-		struct cgroup *cgrp;
+	if (pinned_sb)
+		deactivate_super(pinned_sb);
 
-		mutex_lock(&cgroup_mutex);
-		spin_lock_irq(&css_set_lock);
+	return dentry;
+}
 
-		cgrp = cset_cgroup_from_root(ns->root_cset, root);
+static struct dentry *cgroup_mount(struct file_system_type *fs_type,
+			 int flags, const char *unused_dev_name,
+			 void *data)
+{
+	struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
+	struct dentry *dentry;
 
-		spin_unlock_irq(&css_set_lock);
-		mutex_unlock(&cgroup_mutex);
+	get_cgroup_ns(ns);
 
-		nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
-		dput(dentry);
-		dentry = nsdentry;
+	/* Check if the caller has permission to mount. */
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
+		put_cgroup_ns(ns);
+		return ERR_PTR(-EPERM);
 	}
 
-	if (IS_ERR(dentry) || !new_sb)
-		cgroup_put(&root->cgrp);
-
 	/*
-	 * If @pinned_sb, we're reusing an existing root and holding an
-	 * extra ref on its sb.  Mount is complete.  Put the extra ref.
+	 * The first time anyone tries to mount a cgroup, enable the list
+	 * linking each css_set to its tasks and fix up all existing tasks.
 	 */
-	if (pinned_sb) {
-		WARN_ON(new_sb);
-		deactivate_super(pinned_sb);
+	if (!use_task_css_set_links)
+		cgroup_enable_task_cg_lists();
+
+	if (fs_type == &cgroup2_fs_type) {
+		if (data) {
+			pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
+			put_cgroup_ns(ns);
+			return ERR_PTR(-EINVAL);
+		}
+		cgrp_dfl_visible = true;
+		cgroup_get(&cgrp_dfl_root.cgrp);
+
+		dentry = cgroup_do_mount(&cgroup2_fs_type, flags, &cgrp_dfl_root,
+					 CGROUP2_SUPER_MAGIC, ns);
+	} else {
+		dentry = cgroup1_mount(&cgroup_fs_type, flags, data,
+				       CGROUP_SUPER_MAGIC, ns);
 	}
 
 	put_cgroup_ns(ns);
-- 
2.9.3

[PATCH 5/8] cgroup: separate out cgroup1_kf_syscall_ops

[Tejun Heo]

Currently, cgroup_kf_syscall_ops is shared by v1 and v2 and the
specific methods test the version and take different actions.  Split
out v1 functions and put them in cgroup1_kf_syscall_ops and remove the
now unnecessary explicit branches in specific methods.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/cgroup/cgroup-internal.h |  4 ++--
 kernel/cgroup/cgroup-v1.c       | 11 ++---------
 kernel/cgroup/cgroup.c          | 40 ++++++++++++++++++++++++++--------------
 3 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index d86fbbc..7b8182e 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -93,8 +93,8 @@ extern const struct file_operations proc_cgroupstats_operations;
 
 bool cgroup_ssid_no_v1(int ssid);
 void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
-int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-		  const char *new_name_str);
+int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		   const char *new_name_str);
 void cgroup_release_agent(struct work_struct *work);
 void check_for_release(struct cgroup *cgrp);
 
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 7af745a..0b2c24f 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -800,8 +800,8 @@ void cgroup_release_agent(struct work_struct *work)
 /*
  * cgroup_rename - Only allow simple rename of directories in place.
  */
-int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-		  const char *new_name_str)
+int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+		   const char *new_name_str)
 {
 	struct cgroup *cgrp = kn->priv;
 	int ret;
@@ -812,13 +812,6 @@ int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
 		return -EIO;
 
 	/*
-	 * This isn't a proper migration and its usefulness is very
-	 * limited.  Disallow on the default hierarchy.
-	 */
-	if (cgroup_on_dfl(cgrp))
-		return -EPERM;
-
-	/*
 	 * We're gonna grab cgroup_mutex which nests outside kernfs
 	 * active_ref.  kernfs_rename() doesn't require active_ref
 	 * protection.  Break them before grabbing cgroup_mutex.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 6225c4b..f1b71fb 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1234,6 +1234,7 @@ struct cgroup *task_cgroup_from_root(struct task_struct *task,
  * update of a tasks cgroup pointer by cgroup_attach_task()
  */
 
+static struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
 
 static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
@@ -1568,16 +1569,15 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 	return len;
 }
 
-static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
 {
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 	struct cgroup_subsys *ss;
 	int ssid;
 
-	if (root != &cgrp_dfl_root)
-		for_each_subsys(ss, ssid)
-			if (root->subsys_mask & (1 << ssid))
-				seq_show_option(seq, ss->legacy_name, NULL);
+	for_each_subsys(ss, ssid)
+		if (root->subsys_mask & (1 << ssid))
+			seq_show_option(seq, ss->legacy_name, NULL);
 	if (root->flags & CGRP_ROOT_NOPREFIX)
 		seq_puts(seq, ",noprefix");
 	if (root->flags & CGRP_ROOT_XATTR)
@@ -1738,18 +1738,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	return 0;
 }
 
-static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
 {
 	int ret = 0;
 	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 	struct cgroup_sb_opts opts;
 	u16 added_mask, removed_mask;
 
-	if (root == &cgrp_dfl_root) {
-		pr_err("remount is not allowed\n");
-		return -EINVAL;
-	}
-
 	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
 
 	/* See what subsystems are wanted */
@@ -1800,6 +1795,12 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
 	return ret;
 }
 
+static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+	pr_err("remount is not allowed\n");
+	return -EINVAL;
+}
+
 /*
  * To reduce the fork() overhead for systems that are not actually using
  * their cgroups capability, we don't maintain the lists running through
@@ -1902,6 +1903,7 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 {
 	LIST_HEAD(tmp_links);
 	struct cgroup *root_cgrp = &root->cgrp;
+	struct kernfs_syscall_ops *kf_sops;
 	struct css_set *cset;
 	int i, ret;
 
@@ -1933,7 +1935,10 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 	if (ret)
 		goto cancel_ref;
 
-	root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
+	kf_sops = root == &cgrp_dfl_root ?
+		&cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;
+
+	root->kf_root = kernfs_create_root(kf_sops,
 					   KERNFS_ROOT_CREATE_DEACTIVATED,
 					   root_cgrp);
 	if (IS_ERR(root->kf_root)) {
@@ -4815,12 +4820,19 @@ static int cgroup_rmdir(struct kernfs_node *kn)
 	return ret;
 }
 
+static struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
+	.remount_fs		= cgroup1_remount,
+	.show_options		= cgroup1_show_options,
+	.rename			= cgroup1_rename,
+	.mkdir			= cgroup_mkdir,
+	.rmdir			= cgroup_rmdir,
+	.show_path		= cgroup_show_path,
+};
+
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
 	.remount_fs		= cgroup_remount,
-	.show_options		= cgroup_show_options,
 	.mkdir			= cgroup_mkdir,
 	.rmdir			= cgroup_rmdir,
-	.rename			= cgroup_rename,
 	.show_path		= cgroup_show_path,
 };
 
-- 
2.9.3

[PATCH 7/8] cgroup: rename functions for consistency

[Tejun Heo]

Now that v1 functions are separated out, rename some functions for
consistency.

 cgroup_dfl_base_files		-> cgroup_base_files
 cgroup_legacy_base_files	-> cgroup1_base_files
 cgroup_ssid_no_v1()		-> cgroup1_ssid_disabled()
 cgroup_pidlist_destroy_all	-> cgroup1_pidlist_destroy_all()
 cgroup_release_agent()		-> cgroup1_release_agent()
 check_for_release()		-> cgroup1_check_for_release()

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/cgroup/cgroup-internal.h | 10 +++++-----
 kernel/cgroup/cgroup-v1.c       | 14 +++++++-------
 kernel/cgroup/cgroup.c          | 22 +++++++++++-----------
 3 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 3d431b6..2020d8d 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -108,14 +108,14 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 /*
  * cgroup-v1.c
  */
-extern struct cftype cgroup_legacy_base_files[];
+extern struct cftype cgroup1_base_files[];
 extern const struct file_operations proc_cgroupstats_operations;
 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 
-bool cgroup_ssid_no_v1(int ssid);
-void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
-void cgroup_release_agent(struct work_struct *work);
-void check_for_release(struct cgroup *cgrp);
+bool cgroup1_ssid_disabled(int ssid);
+void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
+void cgroup1_release_agent(struct work_struct *work);
+void cgroup1_check_for_release(struct cgroup *cgrp);
 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
 			     void *data, unsigned long magic,
 			     struct cgroup_namespace *ns);
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index ae240c0..37be09e 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -36,7 +36,7 @@ static struct workqueue_struct *cgroup_pidlist_destroy_wq;
  */
 static DEFINE_SPINLOCK(release_agent_path_lock);
 
-bool cgroup_ssid_no_v1(int ssid)
+bool cgroup1_ssid_disabled(int ssid)
 {
 	return cgroup_no_v1_mask & (1 << ssid);
 }
@@ -201,7 +201,7 @@ static void pidlist_free(void *p)
  * Used to destroy all pidlists lingering waiting for destroy timer.  None
  * should be left afterwards.
  */
-void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
+void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
 {
 	struct cgroup_pidlist *l, *tmp_l;
 
@@ -585,7 +585,7 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
 }
 
 /* cgroup core interface files for the legacy hierarchies */
-struct cftype cgroup_legacy_base_files[] = {
+struct cftype cgroup1_base_files[] = {
 	{
 		.name = "cgroup.procs",
 		.seq_start = cgroup_pidlist_start,
@@ -729,7 +729,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
 	return 0;
 }
 
-void check_for_release(struct cgroup *cgrp)
+void cgroup1_check_for_release(struct cgroup *cgrp)
 {
 	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
 	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
@@ -759,7 +759,7 @@ void check_for_release(struct cgroup *cgrp)
  * this routine has no use for the exit status of the release agent
  * task, so no sense holding our caller up for that.
  */
-void cgroup_release_agent(struct work_struct *work)
+void cgroup1_release_agent(struct work_struct *work)
 {
 	struct cgroup *cgrp =
 		container_of(work, struct cgroup, release_agent_work);
@@ -946,7 +946,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 				continue;
 			if (!cgroup_ssid_enabled(i))
 				continue;
-			if (cgroup_ssid_no_v1(i))
+			if (cgroup1_ssid_disabled(i))
 				continue;
 
 			/* Mutually exclusive option 'all' + subsystem name */
@@ -968,7 +968,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	 */
 	if (all_ss || (!one_ss && !opts->none && !opts->name))
 		for_each_subsys(ss, i)
-			if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
+			if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
 				opts->subsys_mask |= (1 << i);
 
 	/*
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index ae25f14..dcfbeb6 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -201,7 +201,7 @@ struct cgroup_namespace init_cgroup_ns = {
 static u16 have_canfork_callback __read_mostly;
 
 static struct file_system_type cgroup2_fs_type;
-static struct cftype cgroup_dfl_base_files[];
+static struct cftype cgroup_base_files[];
 
 static int cgroup_apply_control(struct cgroup *cgrp);
 static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
@@ -611,7 +611,7 @@ static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
 		if (!trigger)
 			break;
 
-		check_for_release(cgrp);
+		cgroup1_check_for_release(cgrp);
 		cgroup_file_notify(&cgrp->events_file);
 
 		cgrp = cgroup_parent(cgrp);
@@ -1442,9 +1442,9 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
 
 	if (!css->ss) {
 		if (cgroup_on_dfl(cgrp))
-			cfts = cgroup_dfl_base_files;
+			cfts = cgroup_base_files;
 		else
-			cfts = cgroup_legacy_base_files;
+			cfts = cgroup1_base_files;
 
 		return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
 	}
@@ -1647,7 +1647,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
 		INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
 
 	init_waitqueue_head(&cgrp->offline_waitq);
-	INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
+	INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);
 }
 
 void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts)
@@ -3838,7 +3838,7 @@ static int cgroup_procs_show(struct seq_file *s, void *v)
 }
 
 /* cgroup core interface files for the default hierarchy */
-static struct cftype cgroup_dfl_base_files[] = {
+static struct cftype cgroup_base_files[] = {
 	{
 		.name = "cgroup.procs",
 		.file_offset = offsetof(struct cgroup, procs_file),
@@ -3911,7 +3911,7 @@ static void css_free_work_fn(struct work_struct *work)
 	} else {
 		/* cgroup free path */
 		atomic_dec(&cgrp->root->nr_cgrps);
-		cgroup_pidlist_destroy_all(cgrp);
+		cgroup1_pidlist_destroy_all(cgrp);
 		cancel_work_sync(&cgrp->release_agent_work);
 
 		if (cgroup_parent(cgrp)) {
@@ -4413,7 +4413,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	 */
 	kernfs_remove(cgrp->kn);
 
-	check_for_release(cgroup_parent(cgrp));
+	cgroup1_check_for_release(cgroup_parent(cgrp));
 
 	/* put the base reference */
 	percpu_ref_kill(&cgrp->self.refcnt);
@@ -4550,8 +4550,8 @@ int __init cgroup_init(void)
 
 	BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
 	BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
-	BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
-	BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
+	BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
+	BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
 
 	/*
 	 * The latency of the synchronize_sched() is too high for cgroups,
@@ -4601,7 +4601,7 @@ int __init cgroup_init(void)
 			continue;
 		}
 
-		if (cgroup_ssid_no_v1(ssid))
+		if (cgroup1_ssid_disabled(ssid))
 			printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
 			       ss->name);
 
-- 
2.9.3