On Thu, Oct 15, 2015 at 05:18:19PM +0200, Oleg Nesterov wrote: > 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.
Oooh, that's subtle! > > > 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. Ok. > 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/
