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cgroup: remove the ns_cgroup

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The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and
leads to some problems:

  * cgroup creation is out-of-control
  * cgroup name can conflict when pids are looping
  * it is not possible to have a single process handling a lot of
    namespaces without falling in a exponential creation time
  * we may want to create a namespace without creating a cgroup

  The ns_cgroup was replaced by a compatibility flag 'clone_children',
  where a newly created cgroup will copy the parent cgroup values.
  The userspace has to manually create a cgroup and add a task to
  the 'tasks' file.

This patch removes the ns_cgroup as suggested in the following thread:

https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html

The 'cgroup_clone' function is removed because it is no longer used.

This is a userspace-visible change.  Commit 45531757b4 ("cgroup: notify
ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a
printk warning users that the feature is planned for removal.  Since that
time we have heard from XXX users who were affected by this.

Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jamal Hadi Salim <hadi@cyberus.ca>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daniel Lezcano 2011-05-26 16:25:23 -07:00 committed by Linus Torvalds
parent d846687d7f
commit a77aea9201
22 changed files with 4 additions and 287 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/cgroups/cgroups.txt
View File

@ -651,7 +651,7 @@ always handled well.
void post_clone(struct cgroup_subsys *ss, struct cgroup *cgrp)
(cgroup_mutex held by caller)
Called at the end of cgroup_clone() to do any parameter
Called during cgroup_create() to do any parameter
initialization which might be required before a task could attach. For
example in cpusets, no task may attach before 'cpus' and 'mems' are set
up.

1
arch/mips/configs/bcm47xx_defconfig
View File

@ -16,7 +16,6 @@ CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_AUDIT=y
CONFIG_TINY_RCU=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_CPUACCT=y
CONFIG_RELAY=y
CONFIG_BLK_DEV_INITRD=y

1
arch/mn10300/configs/asb2364_defconfig
View File

@ -8,7 +8,6 @@ CONFIG_TASK_XACCT=y
CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y

1
arch/powerpc/configs/ppc6xx_defconfig
View File

@ -10,7 +10,6 @@ CONFIG_TASK_XACCT=y
CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_AUDIT=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y
CONFIG_RESOURCE_COUNTERS=y

1
arch/powerpc/configs/pseries_defconfig
View File

@ -15,7 +15,6 @@ CONFIG_AUDITSYSCALL=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CPUSETS=y

1
arch/sh/configs/apsh4ad0a_defconfig
View File

@ -7,7 +7,6 @@ CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y

1
arch/sh/configs/sdk7786_defconfig
View File

@ -12,7 +12,6 @@ CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_DEBUG=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CPUSETS=y

1
arch/sh/configs/se7206_defconfig
View File

@ -8,7 +8,6 @@ CONFIG_RCU_TRACE=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_CGROUP_DEBUG=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y
CONFIG_RESOURCE_COUNTERS=y

1
arch/sh/configs/shx3_defconfig
View File

@ -9,7 +9,6 @@ CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y

1
arch/sh/configs/urquell_defconfig
View File

@ -9,7 +9,6 @@ CONFIG_IKCONFIG_PROC=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_CGROUP_DEBUG=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CPUSETS=y

1
arch/x86/configs/i386_defconfig
View File

@ -10,7 +10,6 @@ CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_AUDIT=y
CONFIG_LOG_BUF_SHIFT=18
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CPUSETS=y
CONFIG_CGROUP_CPUACCT=y

1
arch/x86/configs/x86_64_defconfig
View File

@ -11,7 +11,6 @@ CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_AUDIT=y
CONFIG_LOG_BUF_SHIFT=18
CONFIG_CGROUPS=y
CONFIG_CGROUP_NS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CPUSETS=y
CONFIG_CGROUP_CPUACCT=y

3
include/linux/cgroup.h
View File

@ -555,9 +555,6 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
return task_subsys_state(task, subsys_id)->cgroup;
}
int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss,
char *nodename);
/* A cgroup_iter should be treated as an opaque object */
struct cgroup_iter {
struct list_head *cg_link;

6
include/linux/cgroup_subsys.h
View File

@ -19,12 +19,6 @@ SUBSYS(debug)
/* */
#ifdef CONFIG_CGROUP_NS
SUBSYS(ns)
#endif
/* */
#ifdef CONFIG_CGROUP_SCHED
SUBSYS(cpu_cgroup)
#endif

9
include/linux/nsproxy.h
View File

@ -81,13 +81,4 @@ static inline void get_nsproxy(struct nsproxy *ns)
atomic_inc(&ns->count);
}
#ifdef CONFIG_CGROUP_NS
int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid);
#else
static inline int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid)
{
return 0;
}
#endif
#endif

8
init/Kconfig
View File

@ -589,14 +589,6 @@ config CGROUP_DEBUG
Say N if unsure.
config CGROUP_NS
bool "Namespace cgroup subsystem"
help
Provides a simple namespace cgroup subsystem to
provide hierarchical naming of sets of namespaces,
for instance virtual servers and checkpoint/restart
jobs.
config CGROUP_FREEZER
bool "Freezer cgroup subsystem"
help

1
kernel/Makefile
View File

@ -61,7 +61,6 @@ obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_CGROUPS) += cgroup.o
obj-$(CONFIG_CGROUP_FREEZER) += cgroup_freezer.o
obj-$(CONFIG_CPUSETS) += cpuset.o
obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o
obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o

116
kernel/cgroup.c
View File

@ -4629,122 +4629,6 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
put_css_set_taskexit(cg);
}
/**
* cgroup_clone - clone the cgroup the given subsystem is attached to
* @tsk: the task to be moved
* @subsys: the given subsystem
* @nodename: the name for the new cgroup
*
* Duplicate the current cgroup in the hierarchy that the given
* subsystem is attached to, and move this task into the new
* child.
*/
int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
char *nodename)
{
struct dentry *dentry;
int ret = 0;
struct cgroup *parent, *child;
struct inode *inode;
struct css_set *cg;
struct cgroupfs_root *root;
struct cgroup_subsys *ss;
/* We shouldn't be called by an unregistered subsystem */
BUG_ON(!subsys->active);
/* First figure out what hierarchy and cgroup we're dealing
* with, and pin them so we can drop cgroup_mutex */
mutex_lock(&cgroup_mutex);
again:
root = subsys->root;
if (root == &rootnode) {
mutex_unlock(&cgroup_mutex);
return 0;
}
/* Pin the hierarchy */
if (!atomic_inc_not_zero(&root->sb->s_active)) {
/* We race with the final deactivate_super() */
mutex_unlock(&cgroup_mutex);
return 0;
}
/* Keep the cgroup alive */
task_lock(tsk);
parent = task_cgroup(tsk, subsys->subsys_id);
cg = tsk->cgroups;
get_css_set(cg);
task_unlock(tsk);
mutex_unlock(&cgroup_mutex);
/* Now do the VFS work to create a cgroup */
inode = parent->dentry->d_inode;
/* Hold the parent directory mutex across this operation to
* stop anyone else deleting the new cgroup */
mutex_lock(&inode->i_mutex);
dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
if (IS_ERR(dentry)) {
printk(KERN_INFO
"cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
PTR_ERR(dentry));
ret = PTR_ERR(dentry);
goto out_release;
}
/* Create the cgroup directory, which also creates the cgroup */
ret = vfs_mkdir(inode, dentry, 0755);
child = __d_cgrp(dentry);
dput(dentry);
if (ret) {
printk(KERN_INFO
"Failed to create cgroup %s: %d\n", nodename,
ret);
goto out_release;
}
/* The cgroup now exists. Retake cgroup_mutex and check
* that we're still in the same state that we thought we
* were. */
mutex_lock(&cgroup_mutex);
if ((root != subsys->root) ||
(parent != task_cgroup(tsk, subsys->subsys_id))) {
/* Aargh, we raced ... */
mutex_unlock(&inode->i_mutex);
put_css_set(cg);
deactivate_super(root->sb);
/* The cgroup is still accessible in the VFS, but
* we're not going to try to rmdir() it at this
* point. */
printk(KERN_INFO
"Race in cgroup_clone() - leaking cgroup %s\n",
nodename);
goto again;
}
/* do any required auto-setup */
for_each_subsys(root, ss) {
if (ss->post_clone)
ss->post_clone(ss, child);
}
/* All seems fine. Finish by moving the task into the new cgroup */
ret = cgroup_attach_task(child, tsk);
mutex_unlock(&cgroup_mutex);
out_release:
mutex_unlock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
put_css_set(cg);
mutex_unlock(&cgroup_mutex);
deactivate_super(root->sb);
return ret;
}
/**
* cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
* @cgrp: the cgroup in question

7
kernel/cpuset.c
View File

@ -1802,10 +1802,9 @@ static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
}
/*
* post_clone() is called at the end of cgroup_clone().
* 'cgroup' was just created automatically as a result of
* a cgroup_clone(), and the current task is about to
* be moved into 'cgroup'.
* post_clone() is called during cgroup_create() when the
* clone_children mount argument was specified. The cgroup
* can not yet have any tasks.
*
* Currently we refuse to set up the cgroup - thereby
* refusing the task to be entered, and as a result refusing

6
kernel/fork.c
View File

@ -1229,12 +1229,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
if (clone_flags & CLONE_THREAD)
p->tgid = current->tgid;
if (current->nsproxy != p->nsproxy) {
retval = ns_cgroup_clone(p, pid);
if (retval)
goto bad_fork_free_pid;
}
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
/*
* Clear TID on mm_release()?

118
kernel/ns_cgroup.c
View File

@ -1,118 +0,0 @@
/*
* ns_cgroup.c - namespace cgroup subsystem
*
* Copyright 2006, 2007 IBM Corp
*/
#include <linux/module.h>
#include <linux/cgroup.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>
struct ns_cgroup {
struct cgroup_subsys_state css;
};
struct cgroup_subsys ns_subsys;
static inline struct ns_cgroup *cgroup_to_ns(
struct cgroup *cgroup)
{
return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
struct ns_cgroup, css);
}
int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
{
char name[PROC_NUMBUF];
snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
return cgroup_clone(task, &ns_subsys, name);
}
/*
* Rules:
* 1. you can only enter a cgroup which is a descendant of your current
* cgroup
* 2. you can only place another process into a cgroup if
* a. you have CAP_SYS_ADMIN
* b. your cgroup is an ancestor of task's destination cgroup
* (hence either you are in the same cgroup as task, or in an
* ancestor cgroup thereof)
*/
static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
struct task_struct *task, bool threadgroup)
{
if (current != task) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (!cgroup_is_descendant(new_cgroup, current))
return -EPERM;
}
if (!cgroup_is_descendant(new_cgroup, task))
return -EPERM;
if (threadgroup) {
struct task_struct *c;
rcu_read_lock();
list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
if (!cgroup_is_descendant(new_cgroup, c)) {
rcu_read_unlock();
return -EPERM;
}
}
rcu_read_unlock();
}
return 0;
}
/*
* Rules: you can only create a cgroup if
* 1. you are capable(CAP_SYS_ADMIN)
* 2. the target cgroup is a descendant of your own cgroup
*/
static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
struct cgroup *cgroup)
{
struct ns_cgroup *ns_cgroup;
if (!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
if (!cgroup_is_descendant(cgroup, current))
return ERR_PTR(-EPERM);
if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
printk("ns_cgroup can't be created with parent "
"'clone_children' set.\n");
return ERR_PTR(-EINVAL);
}
printk_once("ns_cgroup deprecated: consider using the "
"'clone_children' flag without the ns_cgroup.\n");
ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
if (!ns_cgroup)
return ERR_PTR(-ENOMEM);
return &ns_cgroup->css;
}
static void ns_destroy(struct cgroup_subsys *ss,
struct cgroup *cgroup)
{
struct ns_cgroup *ns_cgroup;
ns_cgroup = cgroup_to_ns(cgroup);
kfree(ns_cgroup);
}
struct cgroup_subsys ns_subsys = {
.name = "ns",
.can_attach = ns_can_attach,
.create = ns_create,
.destroy = ns_destroy,
.subsys_id = ns_subsys_id,
};

4
kernel/nsproxy.c
View File

@ -201,10 +201,6 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
goto out;
}
err = ns_cgroup_clone(current, task_pid(current));
if (err)
put_nsproxy(*new_nsp);
out:
return err;
}