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-rw-r--r--kernel/cgroup.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 9624db80dc4e..d1c51b7f5221 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2209,12 +2209,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
goto out_unlock;
}
- /*
- * We know this subsystem has not yet been bound. Users in a non-init
- * user namespace may only mount hierarchies with no bound subsystems,
- * i.e. 'none,name=user1'
- */
- if (!opts.none && !capable(CAP_SYS_ADMIN)) {
+ /* Hierarchies may only be created in the initial cgroup namespace. */
+ if (ns != &init_cgroup_ns) {
ret = -EPERM;
goto out_unlock;
}
@@ -2956,6 +2952,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
int retval = 0;
mutex_lock(&cgroup_mutex);
+ percpu_down_write(&cgroup_threadgroup_rwsem);
for_each_root(root) {
struct cgroup *from_cgrp;
@@ -2970,6 +2967,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
if (retval)
break;
}
+ percpu_up_write(&cgroup_threadgroup_rwsem);
mutex_unlock(&cgroup_mutex);
return retval;
@@ -4337,6 +4335,8 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
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)
@@ -4365,6 +4365,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
} while (task && !ret);
out_err:
cgroup_migrate_finish(&preloaded_csets);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
mutex_unlock(&cgroup_mutex);
return ret;
}
@@ -6339,14 +6340,11 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
- mutex_lock(&cgroup_mutex);
+ /* 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);
- mutex_unlock(&cgroup_mutex);
new_ns = alloc_cgroup_ns();
if (IS_ERR(new_ns)) {