1 files changed, 34 insertions, 17 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ba7b3284c2e4..918658497625 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5379,14 +5379,34 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
                         seq_printf(m, "%sname=%s", count ? "," : "",
                                    root->name);
                 seq_putc(m, ':');
+
                 cgrp = task_cgroup_from_root(tsk, root);
-                path = cgroup_path(cgrp, buf, PATH_MAX);
-                if (!path) {
-                        retval = -ENAMETOOLONG;
-                        goto out_unlock;
+
+                /*
+                 * On traditional hierarchies, all zombie tasks show up as
+                 * belonging to the root cgroup.  On the default hierarchy,
+                 * while a zombie doesn't show up in "cgroup.procs" and
+                 * thus can't be migrated, its /proc/PID/cgroup keeps
+                 * reporting the cgroup it belonged to before exiting.  If
+                 * the cgroup is removed before the zombie is reaped,
+                 * " (deleted)" is appended to the cgroup path.
+                 */
+                if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
+                        path = cgroup_path(cgrp, buf, PATH_MAX);
+                        if (!path) {
+                                retval = -ENAMETOOLONG;
+                                goto out_unlock;
+                        }
+                } else {
+                        path = "/";
                 }
+
                 seq_puts(m, path);
-                seq_putc(m, '\n');
+
+                if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
+                        seq_puts(m, " (deleted)\n");
+                else
+                        seq_putc(m, '\n');
         }
 
         retval = 0;
@@ -5593,7 +5613,6 @@ void cgroup_exit(struct task_struct *tsk)
 {
         struct cgroup_subsys *ss;
         struct css_set *cset;
-        bool put_cset = false;
         int i;
 
         /*
@@ -5606,22 +5625,20 @@ void cgroup_exit(struct task_struct *tsk)
                 spin_lock_bh(&css_set_lock);
                 css_set_move_task(tsk, cset, NULL, false);
                 spin_unlock_bh(&css_set_lock);
-                put_cset = true;
+        } else {
+                get_css_set(cset);
         }
 
-        /* Reassign the task to the init_css_set. */
-        RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
-
         /* see cgroup_post_fork() for details */
-        for_each_subsys_which(ss, i, &have_exit_callback) {
-                struct cgroup_subsys_state *old_css = cset->subsys[i];
-                struct cgroup_subsys_state *css = task_css(tsk, i);
+        for_each_subsys_which(ss, i, &have_exit_callback)
+                ss->exit(tsk);
+}
 
-                ss->exit(css, old_css, tsk);
-        }
+void cgroup_free(struct task_struct *task)
+{
+        struct css_set *cset = task_css_set(task);
 
-        if (put_cset)
-                put_css_set(cset);
+        put_css_set(cset);
 }
 
 static void check_for_release(struct cgroup *cgrp)