The TCB nchildren field should not be incremented when pthreads are created.

sched/sched/sched_waitid.c

@@ -239,6 +239,8 @@ int waitid(idtype_t idtype, id_t id, FAR siginfo_t *info, int options)
         }
     }
 #else
+  /* Child status is not retained. */
+
   if (rtcb->nchildren == 0)
     {
       /* There are no children */

sched/sched/sched_waitpid.c

@@ -383,6 +383,7 @@ pid_t waitpid(pid_t pid, int *stat_loc, int options)
       /* Get the TCB corresponding to this PID and make sure it is our child. */
 
       ctcb = sched_gettcb(pid);
+
 #ifdef HAVE_GROUP_MEMBERS
       if (!ctcb || ctcb->group->tg_pgid != rtcb->group->tg_gid)
 #else

sched/task/task_reparent.c

@@ -190,6 +190,7 @@ int task_reparent(pid_t ppid, pid_t chpid)
     }
 
 #else /* CONFIG_SCHED_CHILD_STATUS */
+  /* Child task exit status is not retained */
 
   DEBUGASSERT(otcb->nchildren > 0);
 
@@ -302,6 +303,7 @@ int task_reparent(pid_t ppid, pid_t chpid)
     }
 
 #else /* CONFIG_SCHED_CHILD_STATUS */
+  /* Child task exit status is not retained */
 
   DEBUGASSERT(otcb->nchildren > 0);
 

sched/task/task_setup.c

@@ -275,8 +275,17 @@ static inline void task_saveparent(FAR struct tcb_s *tcb, uint8_t ttype)
         }
     }
 #else
+  /* Child status is not retained.  Simply keep track of the number
+   * child tasks (not pthreads) created.
+   */
+
+#ifndef CONFIG_DISABLE_PTHREAD
+  if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
+#endif
+    {
       DEBUGASSERT(rtcb->nchildren < UINT16_MAX);
       rtcb->nchildren++;
+    }
 #endif
 }
 #else