1 files changed, 8 insertions, 0 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 800852282c21..5d4c92ead691 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -422,12 +422,20 @@ static void __put_css_set(struct css_set *cg, int taskexit)
                 struct cgroup *cgrp = link->cgrp;
                 list_del(&link->cg_link_list);
                 list_del(&link->cgrp_link_list);
+
+                /*
+                 * We may not be holding cgroup_mutex, and if cgrp->count is
+                 * dropped to 0 the cgroup can be destroyed at any time, hence
+                 * rcu_read_lock is used to keep it alive.
+                 */
+                rcu_read_lock();
                 if (atomic_dec_and_test(&cgrp->count) &&
                     notify_on_release(cgrp)) {
                         if (taskexit)
                                 set_bit(CGRP_RELEASABLE, &cgrp->flags);
                         check_for_release(cgrp);
                 }
+                rcu_read_unlock();
 
                 kfree(link);
         }