1 files changed, 10 insertions, 8 deletions

diff --git a/kernel/pid.c b/kernel/pid.c
index d3f722d20f9c..aebb30d9c233 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -141,11 +141,12 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
                          * installing it:
                          */
                         spin_lock_irq(&pidmap_lock);
-                        if (map->page)
-                                kfree(page);
-                        else
+                        if (!map->page) {
                                 map->page = page;
+                                page = NULL;
+                        }
                         spin_unlock_irq(&pidmap_lock);
+                        kfree(page);
                         if (unlikely(!map->page))
                                 break;
                 }
@@ -268,12 +269,11 @@ struct pid *alloc_pid(struct pid_namespace *ns)
         for (type = 0; type < PIDTYPE_MAX; ++type)
                 INIT_HLIST_HEAD(&pid->tasks[type]);
 
+        upid = pid->numbers + ns->level;
         spin_lock_irq(&pidmap_lock);
-        for (i = ns->level; i >= 0; i--) {
-                upid = &pid->numbers[i];
+        for ( ; upid >= pid->numbers; --upid)
                 hlist_add_head_rcu(&upid->pid_chain,
                                 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
-        }
         spin_unlock_irq(&pidmap_lock);
 
 out:
@@ -367,7 +367,9 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
         struct task_struct *result = NULL;
         if (pid) {
                 struct hlist_node *first;
-                first = rcu_dereference(pid->tasks[type].first);
+                first = rcu_dereference_check(pid->tasks[type].first,
+                                              rcu_read_lock_held() ||
+                                              lockdep_tasklist_lock_is_held());
                 if (first)
                         result = hlist_entry(first, struct task_struct, pids[(type)].node);
         }
@@ -376,7 +378,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
 EXPORT_SYMBOL(pid_task);
 
 /*
- * Must be called under rcu_read_lock() or with tasklist_lock read-held.
+ * Must be called under rcu_read_lock().
  */
 struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
 {