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From: Oleg Nesterov <oleg@redhat.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: mmotm 2009-08-24-16-24 uploaded
Date: Thu, 27 Aug 2009 12:52:09 +0200	[thread overview]
Message-ID: <20090827105209.GA8469@redhat.com> (raw)
In-Reply-To: <20090827193133.b7eed4a9.kamezawa.hiroyu@jp.fujitsu.com>

On 08/27, KAMEZAWA Hiroyuki wrote:
>
> On Thu, 27 Aug 2009 12:08:46 +0200
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> >
> > OK, I seem to understand what happens. Could you try the patch below?
> >
>
> worked.

Thanks. I need to think a bit, then I send the fix.

> IMHO, it's necessary to "wake up parent with -ECHILD if all children dies"

Of course! It was supposed to do. More precisely, we should wake up when
any child which cuould be interesting to ->parent dies. No need to check
"all children died" case specially. If parent sleeps on ->wait_chldexit
there must be at least on eligible child.

The problem is, do_notify_parent() changes ->exit_signal _before_ it calls
__wake_up_parent(). This changes the result of eligible_child().

Oleg.


  reply	other threads:[~2009-08-27 10:56 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-24 23:28 akpm
2009-08-25 10:02 ` KAMEZAWA Hiroyuki
2009-08-26  4:52   ` Amerigo Wang
2009-08-26  6:54     ` KAMEZAWA Hiroyuki
2009-08-26  3:15 ` KAMEZAWA Hiroyuki
2009-08-26  3:36   ` Andrew Morton
2009-08-26  3:44     ` KAMEZAWA Hiroyuki
2009-08-27  5:44 ` KAMEZAWA Hiroyuki
2009-08-27  6:17   ` Hiroshi Shimamoto
2009-08-27  6:31     ` KAMEZAWA Hiroyuki
2009-08-27  7:05   ` KAMEZAWA Hiroyuki
2009-08-27  9:34     ` Oleg Nesterov
2009-08-27  9:43       ` KAMEZAWA Hiroyuki
2009-08-27 10:08         ` Oleg Nesterov
2009-08-27 10:31           ` KAMEZAWA Hiroyuki
2009-08-27 10:52             ` Oleg Nesterov [this message]
2009-08-28 17:17               ` eligible_child() && __WCLONE && task_detached() (Was: mmotm 2009-08-24-16-24 uploaded) Oleg Nesterov
2009-08-28 19:16                 ` Roland McGrath
2009-09-01 12:22                   ` [PATCH -mm 0/2] fix do_wait(!__WALL) hang " Oleg Nesterov
2009-09-01 12:23                     ` [PATCH -mm 1/2] do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage Oleg Nesterov
2009-09-10  0:36                       ` KAMEZAWA Hiroyuki
2009-09-01 12:24                     ` [PATCH -mm 2/2] do_wait-wakeup-optimization: simplify task_pid_type() Oleg Nesterov
2009-08-27 10:17         ` mmotm 2009-08-24-16-24 uploaded KAMEZAWA Hiroyuki
2009-08-27  9:37     ` KAMEZAWA Hiroyuki

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