There's one place that works with task pids - its the "tasks" file
in cgroups. The read/write handlers assume, that the pid values 
go to/come from the user space and thus it is a virtual pid, i.e. 
the pid as it is seen from inside a namespace.

Tune the code accordingly.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---
 kernel/cgroup.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2c5cccb..4766bb6 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1269,7 +1269,7 @@ static int attach_task_by_pid(struct cgroup *cgrp, char *pidbuf)
 
 	if (pid) {
 		rcu_read_lock();
-		tsk = find_task_by_pid(pid);
+		tsk = find_task_by_vpid(pid);
 		if (!tsk || tsk->flags & PF_EXITING) {
 			rcu_read_unlock();
 			return -ESRCH;
@@ -1955,7 +1955,7 @@ static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
 	while ((tsk = cgroup_iter_next(cgrp, &it))) {
 		if (unlikely(n == npids))
 			break;
-		pidarray[n++] = task_pid_nr(tsk);
+		pidarray[n++] = task_pid_vnr(tsk);
 	}
 	cgroup_iter_end(cgrp, &it);
 	return n;
-- 
1.5.3.4