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-rw-r--r--kernel/fork.c10
-rw-r--r--kernel/sys.c22
2 files changed, 29 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 135b7a49ad59..c814e590cf76 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1367,9 +1367,6 @@ 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;
@@ -1800,6 +1797,13 @@ 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);
diff --git a/kernel/sys.c b/kernel/sys.c
index 842914ef7de4..0e4d566a6f16 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2063,6 +2063,24 @@ static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
}
#endif
+static int propagate_has_child_subreaper(struct task_struct *p, void *data)
+{
+ /*
+ * If task has has_child_subreaper - all its decendants
+ * already have these flag too and new decendants will
+ * inherit it on fork, skip them.
+ *
+ * If we've found child_reaper - skip descendants in
+ * it's subtree as they will never get out pidns.
+ */
+ if (p->signal->has_child_subreaper ||
+ is_child_reaper(task_pid(p)))
+ return 0;
+
+ p->signal->has_child_subreaper = 1;
+ return 1;
+}
+
SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
unsigned long, arg4, unsigned long, arg5)
{
@@ -2214,6 +2232,10 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
break;
case PR_SET_CHILD_SUBREAPER:
me->signal->is_child_subreaper = !!arg2;
+ if (!arg2)
+ break;
+
+ walk_process_tree(me, propagate_has_child_subreaper, NULL);
break;
case PR_GET_CHILD_SUBREAPER:
error = put_user(me->signal->is_child_subreaper,