From: Frederic Weisbecker <fweisbec@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Christoph Lameter <cl@linux.com>,
Tejun Heo <tj@kernel.org>, Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] Revert "kmod: handle UMH_WAIT_PROC from system unbound workqueue"
Date: Thu, 15 Oct 2015 15:37:39 +0200 [thread overview]
Message-ID: <20151015133737.GC12822@lerouge> (raw)
In-Reply-To: <20151014185209.GB8117@redhat.com>
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. But then when we create the async thread with
UMH_NO_WAIT, who reaps it? It's created by the workqueue which never
exits.
And on others cases, who buries the sync thread?
next prev parent reply other threads:[~2015-10-15 13:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-14 18:51 [PATCH 0/1] Revert "kmod: handle UMH_WAIT_PROC from system unbound workqueue" Oleg Nesterov
2015-10-14 18:52 ` [PATCH 1/1] " Oleg Nesterov
2015-10-15 13:37 ` Frederic Weisbecker [this message]
2015-10-15 15:18 ` Oleg Nesterov
2015-10-15 15:34 ` Frederic Weisbecker
2015-10-15 14:37 ` [PATCH 0/1] kmod: don't run async usermode helper as a child of kworker thread Oleg Nesterov
2015-10-15 14:37 ` Oleg Nesterov
2015-10-15 15:52 ` Frederic Weisbecker
2015-10-15 16:32 ` Oleg Nesterov
2015-10-15 16:53 ` Frederic Weisbecker
2015-10-15 17:51 ` Oleg Nesterov
2015-10-15 17:52 ` [PATCH v2 1/1] " Oleg Nesterov
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