[GIT PULL] cgroup fixes for v3.2-rc6

[GIT PULL] cgroup fixes for v3.2-rc6

[Tejun Heo]

Hello, Linus.

Trying to migrating a zombie task hits BUG.  This is already fixed in
the devel branch with the threadgroup locking and this is only for
v3.2 and -stable.  The fix is simple - not skipping PF_EXITING tasks
in cgroup_attach_proc() preparation steps is enough.

Please pull from the following git branch to receive the fix.

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-3.2-fixes

Thank you.

Mandeep Singh Baines (1):
      cgroups: fix a css_set not found bug in cgroup_attach_proc

 kernel/cgroup.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)
---
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d9d5648..a184470 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2098,11 +2098,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
 			continue;
 		/* get old css_set pointer */
 		task_lock(tsk);
-		if (tsk->flags & PF_EXITING) {
-			/* ignore this task if it's going away */
-			task_unlock(tsk);
-			continue;
-		}
 		oldcg = tsk->cgroups;
 		get_css_set(oldcg);
 		task_unlock(tsk);