On 10/15, Frederic Weisbecker wrote: > > On Wed, Oct 14, 2015 at 08:52:09PM +0200, Oleg Nesterov wrote: > > This reverts commit bb304a5c6fc63d8506cd9741a3a5f35b73605625. > > > > Because this patch leads to kthread zombies. > > > > call_usermodehelper_exec_sync() does fork() + wait() with "unignored" > > SIGCHLD. What we have missed is that this worker thread can have other > > children previously forked by call_usermodehelper_exec_work() without > > UMH_WAIT_PROC. If such a child exits in between it becomes a zombie > > and nobody can reap it (unless/until this worker thread exits too). > > I missed that indeed.
Heh me too ;) > But then when we create the async thread with > UMH_NO_WAIT, who reaps it? It's created by the workqueue which never > exits. It is auto-reaped because SIGCHILD is ignored. And this is why bb304a5c6fc6 is wrong; it can die while UMH_WAIT_PROC case waits for the new child. > And on others cases, who buries the sync thread? The same. Please see V2 I sent. I'll try to send more cleanups soon to make this all more explicit. Oleg. -- 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/
