Re: [PATCH][usercr]: Ghost tasks must be detached

From: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
To: Oren Laadan <orenl-eQaUEPhvms7ENvBUuze7eA@public.gmane.org>,
	Containers
	<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
Subject: Re: [PATCH][usercr]: Ghost tasks must be detached
Date: Thu, 10 Feb 2011 14:31:59 -0800	[thread overview]
Message-ID: <20110210223159.GA4544@us.ibm.com> (raw)
In-Reply-To: <20110210180433.GI6360-Hu8+6S1rdjywhHL9vcZdMVaTQe2KTcn/@public.gmane.org>

Louis Rilling [Louis.Rilling-aw0BnHfMbSpBDgjK7y7TUQ@public.gmane.org] wrote:
| On 10/02/11  9:54 -0800, Sukadev Bhattiprolu wrote:
| > Louis Rilling [Louis.Rilling-aw0BnHfMbSpBDgjK7y7TUQ@public.gmane.org] wrote:

| > If it was a detached task, do_wait_thread() skipped over it. In the C/R
| > kernel we were setting the ->exit_signal to -1 for a "ghost" process. 
| > I assumed that the container-init exited without waiting for the "ghost"
| > and we were getting the crash in proc_flush_mnt() when the ghost exited.
| 
| The point is that wait_consider_task() skips detached tasks as soon as they are
| not ptraced. So removing the check in do_wait_thread() should not have changed
| the behavior. Am I missing something?

No. I was :-) You are right that it did not change the behavior. I still
need to investigate why the crash does not occur on 2.6.37 even without
Eric's fix.

Sukadev