From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@ZenIV.linux.org.uk>,
Jan Kratochvil <jan.kratochvil@redhat.com>,
Lennart Poettering <lpoetter@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Michal Schmidt <mschmidt@redhat.com>,
Roland McGrath <roland@hack.frob.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] kill the racy EXIT_ZOMBIE->EXIT_DEAD->EXIT_ZOMBIE transition
Date: Mon, 24 Feb 2014 16:51:21 +0100 [thread overview]
Message-ID: <20140224155121.GA10545@redhat.com> (raw)
In-Reply-To: <20140220194848.GA6573@mtj.dyndns.org>
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.
next prev parent reply other threads:[~2014-02-24 15:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-20 17:38 [PATCH 0/5] kill the racy EXIT_ZOMBIE->EXIT_DEAD->EXIT_ZOMBIE transition Oleg Nesterov
2014-02-20 17:38 ` [PATCH 1/5] wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE race Oleg Nesterov
2014-02-20 17:39 ` [PATCH 2/5] wait: introduce EXIT_TRACE to avoid the racy EXIT_DEAD->EXIT_ZOMBIE transition Oleg Nesterov
2014-02-20 17:39 ` [PATCH 3/5] wait: use EXIT_TRACE only if thread_group_leader(zombie) Oleg Nesterov
2014-02-20 17:39 ` [PATCH 4/5] wait: completely ignore the EXIT_DEAD tasks Oleg Nesterov
2014-02-20 17:39 ` [PATCH 5/5] wait: swap EXIT_ZOMBIE and EXIT_DEAD to hide EXIT_TRACE from user-space Oleg Nesterov
2014-02-20 19:48 ` [PATCH 0/5] kill the racy EXIT_ZOMBIE->EXIT_DEAD->EXIT_ZOMBIE transition Tejun Heo
2014-02-24 15:51 ` Oleg Nesterov [this message]
2014-02-26 16:55 ` [PATCH 0/2] wait: WSTOPPED & ptrace fixes Oleg Nesterov
2014-02-26 16:55 ` [PATCH 1/2] wait: WSTOPPED|WCONTINUED hangs if a zombie child is traced by real_parent Oleg Nesterov
2014-02-26 16:56 ` [PATCH 2/2] wait: WSTOPPED|WCONTINUED doesn't work if a zombie leader is traced by another process Oleg Nesterov
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