From: Oleg Nesterov The child was found on ->children list under tasklist_lock, it must have a valid ->signal. __exit_signal() both removes the task from parent->children and clears ->signal "atomically" under write_lock(tasklist). Remove unneeded checks. Signed-off-by: Oleg Nesterov Acked-by: Roland McGrath Signed-off-by: Andrew Morton --- kernel/exit.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff -puN kernel/exit.c~wait_task_stopped-continued-remove-unneeded-p-signal-=-null-check kernel/exit.c --- a/kernel/exit.c~wait_task_stopped-continued-remove-unneeded-p-signal-=-null-check +++ a/kernel/exit.c @@ -1316,7 +1316,7 @@ static int wait_task_stopped(struct task if (!p->exit_code) return 0; if (delayed_group_leader && !(p->ptrace & PT_PTRACED) && - p->signal && p->signal->group_stop_count > 0) + p->signal->group_stop_count > 0) /* * A group stop is in progress and this is the group leader. * We won't report until all threads have stopped. @@ -1430,9 +1430,6 @@ static int wait_task_continued(struct ta pid_t pid; uid_t uid; - if (unlikely(!p->signal)) - return 0; - if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) return 0; _