cgroups: skip processes from other namespaces when listing a cgroup

Once tasks are populated from system namespace inside cgroup, container
replaces other namespace task with 0 while listing tasks, inside
container.

Though this is expected behaviour from container end, there is no use of
showing unwanted 0s.

In this patch, we check if a process is in same namespace before loading
into pid array.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Gowrishankar M <gowrishankar.m@in.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4c475ce4e222..cb7c72b91f46 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2007,14 +2007,16 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
  */
 static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp)
 {
-        int n = 0;
+        int n = 0, pid;
         struct cgroup_iter it;
         struct task_struct *tsk;
         cgroup_iter_start(cgrp, &it);
         while ((tsk = cgroup_iter_next(cgrp, &it))) {
                 if (unlikely(n == npids))
                         break;
-                pidarray[n++] = task_pid_vnr(tsk);
+                pid = task_pid_vnr(tsk);
+                if (pid > 0)
+                        pidarray[n++] = pid;
         }
         cgroup_iter_end(cgrp, &it);
         return n;