1 files changed, 19 insertions, 14 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index fe00b3b983a8..891a84eb9d30 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -571,8 +571,8 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
 
         if (inode) {
                 inode->i_mode = mode;
-                inode->i_uid = current->fsuid;
-                inode->i_gid = current->fsgid;
+                inode->i_uid = current_fsuid();
+                inode->i_gid = current_fsgid();
                 inode->i_blocks = 0;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
                 inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
@@ -702,7 +702,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
          * any child cgroups exist. This is theoretically supportable
          * but involves complex error handling, so it's being left until
          * later */
-        if (!list_empty(&cgrp->children))
+        if (root->number_of_cgroups > 1)
                 return -EBUSY;
 
         /* Process each subsystem */
@@ -1024,7 +1024,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
                 if (ret == -EBUSY) {
                         mutex_unlock(&cgroup_mutex);
                         mutex_unlock(&inode->i_mutex);
-                        goto drop_new_super;
+                        goto free_cg_links;
                 }
 
                 /* EBUSY should be the only error here */
@@ -1073,10 +1073,11 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 
         return simple_set_mnt(mnt, sb);
 
+ free_cg_links:
+        free_cg_links(&tmp_cg_links);
  drop_new_super:
         up_write(&sb->s_umount);
         deactivate_super(sb);
-        free_cg_links(&tmp_cg_links);
         return ret;
 }
 
@@ -1279,6 +1280,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
 {
         struct task_struct *tsk;
+        const struct cred *cred = current_cred(), *tcred;
         int ret;
 
         if (pid) {
@@ -1288,14 +1290,16 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
                         rcu_read_unlock();
                         return -ESRCH;
                 }
-                get_task_struct(tsk);
-                rcu_read_unlock();
 
-                if ((current->euid) && (current->euid != tsk->uid)
-                    && (current->euid != tsk->suid)) {
-                        put_task_struct(tsk);
+                tcred = __task_cred(tsk);
+                if (cred->euid &&
+                    cred->euid != tcred->uid &&
+                    cred->euid != tcred->suid) {
+                        rcu_read_unlock();
                         return -EACCES;
                 }
+                get_task_struct(tsk);
+                rcu_read_unlock();
         } else {
                 tsk = current;
                 get_task_struct(tsk);
@@ -2934,9 +2938,6 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
  again:
         root = subsys->root;
         if (root == &rootnode) {
-                printk(KERN_INFO
-                       "Not cloning cgroup for unused subsystem %s\n",
-                       subsys->name);
                 mutex_unlock(&cgroup_mutex);
                 return 0;
         }
@@ -2944,7 +2945,11 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
         parent = task_cgroup(tsk, subsys->subsys_id);
 
         /* Pin the hierarchy */
-        atomic_inc(&parent->root->sb->s_active);
+        if (!atomic_inc_not_zero(&parent->root->sb->s_active)) {
+                /* We race with the final deactivate_super() */
+                mutex_unlock(&cgroup_mutex);
+                return 0;
+        }
 
         /* Keep the cgroup alive */
         get_css_set(cg);