diff --git a/fs/proc/base.c b/fs/proc/base.c
index 36983e7bb2c..50e149e08d9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2333,7 +2333,7 @@ static struct task_struct *next_tgid(unsigned int tgid)
 	rcu_read_lock();
 retry:
 	task = NULL;
-	pid = find_ge_pid(tgid);
+	pid = find_ge_pid(tgid, &init_pid_ns);
 	if (pid) {
 		tgid = pid->nr + 1;
 		task = pid_task(pid, PIDTYPE_PID);
diff --git a/include/linux/pid.h b/include/linux/pid.h
index c5fee61bfb4..0dc940f4be4 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -99,17 +99,29 @@ extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
 extern void FASTCALL(transfer_pid(struct task_struct *old,
 				  struct task_struct *new, enum pid_type));
 
+struct pid_namespace;
+extern struct pid_namespace init_pid_ns;
+
 /*
  * look up a PID in the hash table. Must be called with the tasklist_lock
  * or rcu_read_lock() held.
+ *
+ * find_pid_ns() finds the pid in the namespace specified
+ * find_pid() find the pid by its global id, i.e. in the init namespace
+ * find_vpid() finr the pid by its virtual id, i.e. in the current namespace
+ *
+ * see also find_task_by_pid() set in include/linux/sched.h
  */
-extern struct pid *FASTCALL(find_pid(int nr));
+extern struct pid *FASTCALL(find_pid_ns(int nr, struct pid_namespace *ns));
+
+#define find_vpid(pid)	find_pid_ns(pid, current->nsproxy->pid_ns)
+#define find_pid(pid)	find_pid_ns(pid, &init_pid_ns)
 
 /*
  * Lookup a PID in the hash table, and return with it's count elevated.
  */
 extern struct pid *find_get_pid(int nr);
-extern struct pid *find_ge_pid(int nr);
+extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
 
 extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 77e8cad3b17..511cc4549f5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1514,8 +1514,35 @@ extern struct task_struct init_task;
 
 extern struct   mm_struct init_mm;
 
-#define find_task_by_pid(nr)	find_task_by_pid_type(PIDTYPE_PID, nr)
-extern struct task_struct *find_task_by_pid_type(int type, int pid);
+extern struct pid_namespace init_pid_ns;
+
+/*
+ * find a task by one of its numerical ids
+ *
+ * find_task_by_pid_type_ns():
+ *      it is the most generic call - it finds a task by all id,
+ *      type and namespace specified
+ * find_task_by_pid_ns():
+ *      finds a task by its pid in the specified namespace
+ * find_task_by_pid_type():
+ *      finds a task by its global id with the specified type, e.g.
+ *      by global session id
+ * find_task_by_pid():
+ *      finds a task by its global pid
+ *
+ * see also find_pid() etc in include/linux/pid.h
+ */
+
+extern struct task_struct *find_task_by_pid_type_ns(int type, int pid,
+		struct pid_namespace *ns);
+
+#define find_task_by_pid_ns(nr, ns)	\
+		find_task_by_pid_type_ns(PIDTYPE_PID, nr, ns)
+#define find_task_by_pid_type(type, nr)	\
+		find_task_by_pid_type_ns(type, nr, &init_pid_ns)
+#define find_task_by_pid(nr)		\
+		find_task_by_pid_type(PIDTYPE_PID, nr)
+
 extern void __set_special_pids(pid_t session, pid_t pgrp);
 
 /* per-UID process charging. */
diff --git a/kernel/pid.c b/kernel/pid.c
index 6eb14841b73..a2b4cbbdd63 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -71,6 +71,7 @@ struct pid_namespace init_pid_ns = {
 	.level = 0,
 	.child_reaper = &init_task,
 };
+EXPORT_SYMBOL_GPL(init_pid_ns);
 
 int is_global_init(struct task_struct *tsk)
 {
@@ -210,7 +211,8 @@ fastcall void free_pid(struct pid *pid)
 	unsigned long flags;
 
 	spin_lock_irqsave(&pidmap_lock, flags);
-	hlist_del_rcu(&pid->pid_chain);
+	for (i = 0; i <= pid->level; i++)
+		hlist_del_rcu(&pid->numbers[i].pid_chain);
 	spin_unlock_irqrestore(&pidmap_lock, flags);
 
 	for (i = 0; i <= pid->level; i++)
@@ -225,6 +227,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
 	enum pid_type type;
 	int i, nr;
 	struct pid_namespace *tmp;
+	struct upid *upid;
 
 	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
 	if (!pid)
@@ -251,7 +254,11 @@ struct pid *alloc_pid(struct pid_namespace *ns)
 		INIT_HLIST_HEAD(&pid->tasks[type]);
 
 	spin_lock_irq(&pidmap_lock);
-	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, ns)]);
+	for (i = ns->level; i >= 0; i--) {
+		upid = &pid->numbers[i];
+		hlist_add_head_rcu(&upid->pid_chain,
+				&pid_hash[pid_hashfn(upid->nr, upid->ns)]);
+	}
 	spin_unlock_irq(&pidmap_lock);
 
 out:
@@ -266,19 +273,20 @@ out_free:
 	goto out;
 }
 
-struct pid * fastcall find_pid(int nr)
+struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
 {
 	struct hlist_node *elem;
-	struct pid *pid;
+	struct upid *pnr;
+
+	hlist_for_each_entry_rcu(pnr, elem,
+			&pid_hash[pid_hashfn(nr, ns)], pid_chain)
+		if (pnr->nr == nr && pnr->ns == ns)
+			return container_of(pnr, struct pid,
+					numbers[ns->level]);
 
-	hlist_for_each_entry_rcu(pid, elem,
-			&pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {
-		if (pid->nr == nr)
-			return pid;
-	}
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(find_pid);
+EXPORT_SYMBOL_GPL(find_pid_ns);
 
 /*
  * attach_pid() must be called with the tasklist_lock write-held.
@@ -338,12 +346,13 @@ struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.
  */
-struct task_struct *find_task_by_pid_type(int type, int nr)
+struct task_struct *find_task_by_pid_type_ns(int type, int nr,
+		struct pid_namespace *ns)
 {
-	return pid_task(find_pid(nr), type);
+	return pid_task(find_pid_ns(nr, ns), type);
 }
 
-EXPORT_SYMBOL(find_task_by_pid_type);
+EXPORT_SYMBOL(find_task_by_pid_type_ns);
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
 {
@@ -370,7 +379,7 @@ struct pid *find_get_pid(pid_t nr)
 	struct pid *pid;
 
 	rcu_read_lock();
-	pid = get_pid(find_pid(nr));
+	pid = get_pid(find_vpid(nr));
 	rcu_read_unlock();
 
 	return pid;
@@ -394,15 +403,15 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
  *
  * If there is a pid at nr this function is exactly the same as find_pid.
  */
-struct pid *find_ge_pid(int nr)
+struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
 {
 	struct pid *pid;
 
 	do {
-		pid = find_pid(nr);
+		pid = find_pid_ns(nr, ns);
 		if (pid)
 			break;
-		nr = next_pidmap(task_active_pid_ns(current), nr);
+		nr = next_pidmap(ns, nr);
 	} while (nr > 0);
 
 	return pid;