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From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Hugh Dickins <hughd@google.com>,
	linux-mm@kvack.org, Andrey Vagin <avagin@openvz.org>,
	David Rientjes <rientjes@google.com>
Subject: [PATCH 0/3] oom: TIF_MEMDIE/PF_EXITING fixes
Date: Sat, 12 Mar 2011 14:43:41 +0100	[thread overview]
Message-ID: <20110312134341.GA27275@redhat.com> (raw)
In-Reply-To: <20110312123413.GA18351@redhat.com>

On 03/12, Oleg Nesterov wrote:
>
> On 03/11, David Rientjes wrote:
> >
> > On Wed, 9 Mar 2011, Andrew Morton wrote:
> >
> > > If Oleg's test program cause a hang with
> > > oom-prevent-unnecessary-oom-kills-or-kernel-panics.patch and doesn't
> > > cause a hang without
> > > oom-prevent-unnecessary-oom-kills-or-kernel-panics.patch then that's a
> > > big problem for
> > > oom-prevent-unnecessary-oom-kills-or-kernel-panics.patch, no?
> > >
> >
> > It's a problem, but not because of
> > oom-prevent-unnecessary-oom-kills-or-kernel-panics.patch.
>
> It is, afaics. oom-killer can't ussume that a single PF_EXITING && p->mm
> thread is going to free the memory.
>
> > If we don't
> > have this patch, then we have a trivial panic when an oom kill occurs in a
> > cpuset with no other eligible processes, the oom killed thread group
> > leader exits
>
> It is not clear what "leader exits" actually mean. OK, perhaps you mean
> its ->mm == NULL.
>
> > but its other threads do not and they trigger oom kills
> > themselves.  for_each_process() does not iterate over these threads and so
> > it finds no eligible threads to kill and then panics
>
> Could you explain what do you mean? No need to kill these threads, they
> are already killed, we should wait until they all exit.
>
> > I'll look at Oleg's test case
> > and see what can be done to fix that condition, but the answer isn't to
> > ignore eligible threads that can be killed.
>
> Once again, they are already killed. Or I do not understand what you meant.
>
> Could you please explain the problem in more details?
>
>
> Also. Could you please look at the patches I sent?
>
> 	[PATCH 1/1] oom_kill_task: mark every thread as TIF_MEMDIE
> 	[PATCH v2 1/1] select_bad_process: improve the PF_EXITING check

Cough. And both were not right, while_each_thread(p, t) needs the properly
initialized "t". At least I warned they were not tested ;)

> Note also the note about "p == current" check. it should be fixed too.

I am resending the fixes above plus the new one.

David, Kosaki, what do you think?

Oleg.

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  reply	other threads:[~2011-03-12 13:52 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-01 19:09 [patch] oom: prevent unnecessary oom kills or kernel panics David Rientjes
2011-03-03  1:20 ` KOSAKI Motohiro
2011-03-03 19:53   ` David Rientjes
2011-03-06 11:14     ` KOSAKI Motohiro
2011-03-06 22:06       ` David Rientjes
2011-03-08  0:24         ` KOSAKI Motohiro
2011-03-08  2:01         ` KOSAKI Motohiro
2011-03-08 13:42   ` Oleg Nesterov
2011-03-08 23:57     ` David Rientjes
2011-03-09 10:36       ` KOSAKI Motohiro
2011-03-09 11:06       ` Oleg Nesterov
2011-03-09 20:32         ` David Rientjes
2011-03-10 12:05           ` Oleg Nesterov
2011-03-10 15:40             ` [PATCH 0/1] Was: " Oleg Nesterov
2011-03-10 15:41               ` [PATCH 1/1] oom_kill_task: mark every thread as TIF_MEMDIE Oleg Nesterov
2011-03-13  1:08                 ` David Rientjes
2011-03-10 16:36               ` [PATCH 0/1] select_bad_process: improve the PF_EXITING check Oleg Nesterov
2011-03-10 16:37                 ` [PATCH 1/1] " Oleg Nesterov
2011-03-10 16:40                 ` [PATCH 0/1] " Oleg Nesterov
2011-03-10 17:18                   ` [PATCH v2 " Oleg Nesterov
2011-03-10 17:19                     ` [PATCH v2 1/1] " Oleg Nesterov
2011-03-13  1:06             ` [patch] oom: prevent unnecessary oom kills or kernel panics David Rientjes
2011-03-09 23:19       ` Andrew Morton
2011-03-11 19:45         ` David Rientjes
2011-03-12 12:34           ` Oleg Nesterov
2011-03-12 13:43             ` Oleg Nesterov [this message]
2011-03-12 13:44               ` [PATCH 1/3] oom: oom_kill_task: mark every thread as TIF_MEMDIE Oleg Nesterov
2011-03-13  1:14                 ` David Rientjes
2011-03-12 13:44               ` [PATCH 2/3] oom: select_bad_process: improve the PF_EXITING check Oleg Nesterov
2011-03-12 13:44               ` [PATCH 3/3] oom: select_bad_process: use same_thread_group() Oleg Nesterov
2011-03-12 19:40               ` [PATCH 0/3] oom: TIF_MEMDIE/PF_EXITING fixes Hugh Dickins
2011-03-13  8:53                 ` KOSAKI Motohiro
2011-03-13 21:27                 ` Oleg Nesterov
2011-03-14 19:04                   ` [PATCH 0/3 for 2.6.38] oom: fixes Oleg Nesterov
2011-03-14 19:04                     ` [PATCH 1/3 for 2.6.38] oom: oom_kill_process: don't set TIF_MEMDIE if !p->mm Oleg Nesterov
2011-03-14 19:35                       ` Linus Torvalds
2011-03-14 20:31                         ` Oleg Nesterov
2011-03-14 20:32                         ` David Rientjes
2011-03-15 19:12                           ` Oleg Nesterov
2011-03-15 19:51                             ` David Rientjes
2011-03-14 20:22                       ` David Rientjes
2011-03-15 18:53                         ` Oleg Nesterov
2011-03-15 19:54                           ` David Rientjes
2011-03-15 21:16                             ` Oleg Nesterov
2011-03-14 19:05                     ` [PATCH 2/3 for 2.6.38] oom: select_bad_process: ignore TIF_MEMDIE zombies Oleg Nesterov
2011-03-14 20:50                       ` David Rientjes
2011-03-14 19:05                     ` [PATCH 3/3 for 2.6.38] oom: oom_kill_process: fix the child_points logic Oleg Nesterov
2011-03-14 20:41                       ` David Rientjes
2011-03-15 19:21                         ` Oleg Nesterov
2011-03-13 11:36               ` [PATCH 0/3] oom: TIF_MEMDIE/PF_EXITING fixes KOSAKI Motohiro
2011-03-13  1:11             ` [patch] oom: prevent unnecessary oom kills or kernel panics David Rientjes
2011-03-13  1:15               ` [patch -mm] oom: avoid deferring oom killer if exiting task is being traced David Rientjes
2011-03-14 17:40                 ` Oleg Nesterov

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