From: Oleg Nesterov <oleg@redhat.com>
To: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Andrey Vagin <avagin@openvz.org>,
Frantisek Hrbata <fhrbata@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3 for 2.6.38] oom: oom_kill_process: don't set TIF_MEMDIE if !p->mm
Date: Tue, 15 Mar 2011 19:53:16 +0100 [thread overview]
Message-ID: <20110315185316.GA21640@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1103141314190.31514@chino.kir.corp.google.com>
On 03/14, David Rientjes wrote:
>
> On Mon, 14 Mar 2011, Oleg Nesterov wrote:
>
> > oom_kill_process() simply sets TIF_MEMDIE and returns if PF_EXITING.
> > This is very wrong by many reasons. In particular, this thread can
> > be the dead group leader. Check p->mm != NULL.
> >
>
> This is true only for the oom_kill_allocating_task sysctl where it is
> required in all cases to kill current; current won't be triggering the oom
> killer if it's dead.
>
> oom_kill_process() is called with the thread selected by
> select_bad_process() and that function will not return any thread if any
> eligible task is found to be PF_EXITING and is not current, or any
> eligible task is found to have TIF_MEMDIE.
>
> In other words, for this conditional to be true in oom_kill_process(),
> then p must be current and so it cannot be the dead group leader as
> specified in your changelog unless PF_EXITING gets set between
> select_bad_process() and the oom_kill_process() call: we don't care about
> that since it's in the exit path and we therefore want to give it access
> to memory reserves to quickly exit anyway and the check for PF_EXITING in
> select_bad_process() prevents any infinite loop of that task getting
> constantly reselected if it's dead.
Confused. I sent the test-case. OK, may be you meant the code in -mm,
but I meant the current code.
Oleg.
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next prev parent reply other threads:[~2011-03-15 19:02 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 ` [PATCH 0/3] oom: TIF_MEMDIE/PF_EXITING fixes Oleg Nesterov
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 [this message]
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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