linux-kernel - Re: [PATCH 0/5] kill the racy EXIT_ZOMBIE->EXIT_DEAD->EXIT

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Date:	Mon, 24 Feb 2014 16:51:21 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...IV.linux.org.uk>,
	Jan Kratochvil <jan.kratochvil@...hat.com>,
	Lennart Poettering <lpoetter@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Michal Schmidt <mschmidt@...hat.com>,
	Roland McGrath <roland@...k.frob.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] kill the racy EXIT_ZOMBIE->EXIT_DEAD->EXIT_ZOMBIE
	transition

On 02/20, Tejun Heo wrote:
>
> On Thu, Feb 20, 2014 at 06:38:38PM +0100, Oleg Nesterov wrote:
> > Tejun, unless I missed something WSTOPPED logic is broken if a process
> > has a zombie/ptraced leader, "A zombie ptracee is only visible to its
> > ptracer" is wrong in this case. Plus perhaps some cleanups make sense.
>
> Heh, I already forgot most details about ptrace. :)

This is mostly about do_wait(), although yes, !ptrace case looks fine.
And it turns out, I forgot these details too.

> Is it something
> urgent?

No, please forget. But it seems that wait_consider_task(zombie_leader)
is very wrong wrt zombie leaders. WSTOPPED is simple, but I am still
trying to find a simple fix for other problems. And the main problem,
of course, is that this API is broken and we can't fix it.

Oleg.

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