1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index cc0395d7eba1..8c3c400cce91 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1225,7 +1225,12 @@ static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
 
         task_lock(tsk);
         oldcs = tsk->cpuset;
-        if (!oldcs) {
+        /*
+         * After getting 'oldcs' cpuset ptr, be sure still not exiting.
+         * If 'oldcs' might be the top_cpuset due to the_top_cpuset_hack
+         * then fail this attach_task(), to avoid breaking top_cpuset.count.
+         */
+        if (tsk->flags & PF_EXITING) {
                 task_unlock(tsk);
                 mutex_unlock(&callback_mutex);
                 put_task_struct(tsk);