1 files changed, 39 insertions, 3 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index d12fcc4db8a3..348fe73155bc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1377,9 +1377,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         sig->oom_score_adj = current->signal->oom_score_adj;
         sig->oom_score_adj_min = current->signal->oom_score_adj_min;
 
-        sig->has_child_subreaper = current->signal->has_child_subreaper ||
-                                   current->signal->is_child_subreaper;
-
         mutex_init(&sig->cred_guard_mutex);
 
         return 0;
@@ -1814,6 +1811,13 @@ static __latent_entropy struct task_struct *copy_process(
 
                         p->signal->leader_pid = pid;
                         p->signal->tty = tty_kref_get(current->signal->tty);
+                        /*
+                         * Inherit has_child_subreaper flag under the same
+                         * tasklist_lock with adding child to the process tree
+                         * for propagate_has_child_subreaper optimization.
+                         */
+                        p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
+                                                         p->real_parent->signal->is_child_subreaper;
                         list_add_tail(&p->sibling, &p->real_parent->children);
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
                         attach_pid(p, PIDTYPE_PGID);
@@ -2067,6 +2071,38 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
 }
 #endif
 
+void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
+{
+        struct task_struct *leader, *parent, *child;
+        int res;
+
+        read_lock(&tasklist_lock);
+        leader = top = top->group_leader;
+down:
+        for_each_thread(leader, parent) {
+                list_for_each_entry(child, &parent->children, sibling) {
+                        res = visitor(child, data);
+                        if (res) {
+                                if (res < 0)
+                                        goto out;
+                                leader = child;
+                                goto down;
+                        }
+up:
+                        ;
+                }
+        }
+
+        if (leader != top) {
+                child = leader;
+                parent = child->real_parent;
+                leader = parent->group_leader;
+                goto up;
+        }
+out:
+        read_unlock(&tasklist_lock);
+}
+
 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
 #define ARCH_MIN_MMSTRUCT_ALIGN 0
 #endif