From: Oleg Nesterov <oleg@redhat.com>
To: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Nick Piggin <npiggin@suse.de>
Subject: Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads
Date: Tue, 1 Jun 2010 23:20:23 +0200 [thread overview]
Message-ID: <20100601212023.GA24917@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1006011333470.13136@chino.kir.corp.google.com>
On 06/01, David Rientjes wrote:
>
> On Mon, 31 May 2010, KOSAKI Motohiro wrote:
>
> > select_bad_process() thinks a kernel thread can't have ->mm != NULL, this
> > is not true due to use_mm().
> >
> > Change the code to check PF_KTHREAD.
>
> This is already pushed in my oom killer rewrite as patch 14/18 "check
> PF_KTHREAD instead of !mm to skip kthreads".
>
> This does not need to be merged immediately since it's not vital: use_mm()
> is only temporary state and these kthreads will once again be excluded
> when they call unuse_mm(). The worst case scenario here is that the oom
> killer will erroneously select one of these kthreads which cannot die
It can't die but force_sig() does bad things which shouldn't be done
with workqueue thread. Note that it removes SIG_IGN, sets
SIGNAL_GROUP_EXIT, makes signal_pending/fatal_signal_pedning true, etc.
But yes, I agree, the problem is minor. But nevertheless it is bug,
the longstanding bug with the simple fix. Why should we "hide" this fix
inside the long series of non-trivial patches which rewrite oom-killer?
And it is completely orthogonal to other changes.
Oleg.
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next prev parent reply other threads:[~2010-06-01 21:21 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-31 9:33 [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads KOSAKI Motohiro
2010-05-31 9:35 ` [PATCH 2/5] oom: select_bad_process: PF_EXITING check should take ->mm into account KOSAKI Motohiro
2010-05-31 16:43 ` Oleg Nesterov
2010-06-01 1:10 ` KOSAKI Motohiro
2010-06-01 20:18 ` Oleg Nesterov
2010-06-02 13:54 ` [PATCH] oom: remove PF_EXITING check completely KOSAKI Motohiro
2010-06-02 15:54 ` Oleg Nesterov
2010-06-02 21:02 ` David Rientjes
2010-06-03 4:48 ` KOSAKI Motohiro
2010-06-03 6:29 ` David Rientjes
2010-06-02 13:54 ` [PATCH] oom: Make coredump interruptible KOSAKI Motohiro
2010-06-02 15:42 ` Oleg Nesterov
2010-06-02 17:29 ` Roland McGrath
2010-06-02 17:53 ` Oleg Nesterov
2010-06-02 18:58 ` Roland McGrath
2010-06-02 20:38 ` Oleg Nesterov
2010-06-03 14:03 ` Oleg Nesterov
2010-06-04 10:54 ` KOSAKI Motohiro
2010-06-04 11:27 ` Oleg Nesterov
2010-06-04 11:34 ` Oleg Nesterov
2010-06-09 19:53 ` Oleg Nesterov
2010-06-09 20:41 ` David Rientjes
2010-06-09 21:03 ` Oleg Nesterov
2010-06-13 11:24 ` KOSAKI Motohiro
2010-06-13 15:53 ` Oleg Nesterov
2010-06-13 17:13 ` uninterruptible CLONE_VFORK (Was: oom: Make coredump interruptible) Oleg Nesterov
2010-06-14 0:56 ` Roland McGrath
2010-06-14 16:33 ` Oleg Nesterov
2010-06-14 19:17 ` Roland McGrath
2010-06-28 17:33 ` Oleg Nesterov
2010-06-28 18:04 ` Roland McGrath
2010-06-14 0:36 ` [PATCH] oom: Make coredump interruptible Roland McGrath
2010-06-14 0:26 ` Roland McGrath
2010-06-01 20:39 ` [PATCH 2/5] oom: select_bad_process: PF_EXITING check should take ->mm into account David Rientjes
2010-05-31 9:36 ` [PATCH 3/5] oom: introduce find_lock_task_mm() to fix !mm false positives KOSAKI Motohiro
2010-06-01 0:57 ` KAMEZAWA Hiroyuki
2010-06-01 20:42 ` David Rientjes
2010-06-02 16:05 ` Minchan Kim
2010-05-31 9:37 ` [PATCH 4/5] oom: the points calculation of child processes must use find_lock_task_mm() too KOSAKI Motohiro
2010-05-31 16:56 ` Oleg Nesterov
2010-05-31 23:48 ` KOSAKI Motohiro
2010-05-31 9:38 ` [PATCH 5/5] oom: __oom_kill_task() " KOSAKI Motohiro
2010-06-01 1:02 ` KAMEZAWA Hiroyuki
2010-06-01 20:44 ` David Rientjes
2010-06-01 0:54 ` [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads KAMEZAWA Hiroyuki
2010-06-01 20:36 ` David Rientjes
2010-06-01 21:20 ` Oleg Nesterov [this message]
2010-06-01 21:26 ` David Rientjes
2010-06-02 13:54 ` KOSAKI Motohiro
2010-06-02 21:09 ` David Rientjes
2010-06-02 21:33 ` Oleg Nesterov
2010-06-02 21:46 ` David Rientjes
2010-06-03 14:27 ` Oleg Nesterov
2010-06-03 20:11 ` David Rientjes
2010-06-02 15:32 ` Minchan Kim
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