We set sig->notify_count = -1 between RELEASE and ACQUIRE operations: spin_unlock_irq(lock); ... if (!thread_group_leader(tsk)) { ... for (;;) { sig->notify_count = -1; write_lock_irq(&tasklist_lock);
So, there are no restriction on it, other processors may see this STORE mixed with other STOREs in the both areas limited by the spinlocks. Probably, it may be reordered with the above sig->group_exit_task = tsk; sig->notify_count = zap_other_threads(tsk); in some way. Set it under tasklist_lock locked to be sure nothing will be reordered. Signed-off-by: Kirill Tkhai <ktk...@parallels.com> Acked-by: Oleg Nesterov <o...@redhat.com> --- fs/exec.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index c7f9b73..314e8d8 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -926,10 +926,14 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) { struct task_struct *leader = tsk->group_leader; - sig->notify_count = -1; /* for exit_notify() */ for (;;) { threadgroup_change_begin(tsk); write_lock_irq(&tasklist_lock); + /* + * Do this under tasklist_lock to ensure that + * exit_notify() can't miss ->group_exit_task + */ + sig->notify_count = -1; if (likely(leader->exit_state)) break; __set_current_state(TASK_KILLABLE); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/