From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/6] mm, oom: kill all tasks sharing the mm
Date: Tue, 31 May 2016 23:48:23 +0200 [thread overview]
Message-ID: <20160531214823.GC26582@redhat.com> (raw)
In-Reply-To: <20160531074318.GD26128@dhcp22.suse.cz>
On 05/31, Michal Hocko wrote:
>
> On Mon 30-05-16 20:18:16, Oleg Nesterov wrote:
> >
> > perhaps the is_global_init() == T case needs a warning too? the previous changes
> > take care about vfork() from /sbin/init, so the only reason we can see it true
> > is that /sbin/init shares the memory with a memory hog... Nevermind, forget.
>
> I have another two patches waiting for this to settle and one of them
> adds a warning to that path.
Good,
> > This is a bit off-topic, but perhaps we can also change the PF_KTHREAD check later.
> > Of course we should not try to kill this kthread, but can_oom_reap can be true in
> > this case. A kernel thread which does use_mm() should handle the errors correctly
> > if (say) get_user() fails because we unmap the memory.
>
> I was worried that the kernel thread would see a zero page so this could
> lead to a data corruption.
We can't avoid this anyway. use_mm(victim->mm) can be called after we decide to kill
the victim.
So I think that we should always ignore kthreads, and in task_will_free_mem() too.
But let me repeat, I agree we should discuss this later, I am not trying to suggest
this change right now.
Oleg.
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WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/6] mm, oom: kill all tasks sharing the mm
Date: Tue, 31 May 2016 23:48:23 +0200 [thread overview]
Message-ID: <20160531214823.GC26582@redhat.com> (raw)
In-Reply-To: <20160531074318.GD26128@dhcp22.suse.cz>
On 05/31, Michal Hocko wrote:
>
> On Mon 30-05-16 20:18:16, Oleg Nesterov wrote:
> >
> > perhaps the is_global_init() == T case needs a warning too? the previous changes
> > take care about vfork() from /sbin/init, so the only reason we can see it true
> > is that /sbin/init shares the memory with a memory hog... Nevermind, forget.
>
> I have another two patches waiting for this to settle and one of them
> adds a warning to that path.
Good,
> > This is a bit off-topic, but perhaps we can also change the PF_KTHREAD check later.
> > Of course we should not try to kill this kthread, but can_oom_reap can be true in
> > this case. A kernel thread which does use_mm() should handle the errors correctly
> > if (say) get_user() fails because we unmap the memory.
>
> I was worried that the kernel thread would see a zero page so this could
> lead to a data corruption.
We can't avoid this anyway. use_mm(victim->mm) can be called after we decide to kill
the victim.
So I think that we should always ignore kthreads, and in task_will_free_mem() too.
But let me repeat, I agree we should discuss this later, I am not trying to suggest
this change right now.
Oleg.
next prev parent reply other threads:[~2016-05-31 21:48 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-30 13:05 [PATCH 0/6 -v2] Handle oom bypass more gracefully Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 1/6] proc, oom: drop bogus task_lock and mm check Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-31 7:32 ` Michal Hocko
2016-05-31 7:32 ` Michal Hocko
2016-05-31 22:53 ` Oleg Nesterov
2016-05-31 22:53 ` Oleg Nesterov
2016-06-01 6:53 ` Michal Hocko
2016-06-01 6:53 ` Michal Hocko
2016-06-01 10:41 ` Tetsuo Handa
2016-06-01 10:41 ` Tetsuo Handa
2016-06-01 10:48 ` Michal Hocko
2016-06-01 10:48 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 2/6] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 3/6] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-31 7:41 ` Michal Hocko
2016-05-31 7:41 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 4/6] mm, oom: skip vforked tasks from being selected Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 19:28 ` Oleg Nesterov
2016-05-30 19:28 ` Oleg Nesterov
2016-05-31 7:42 ` Michal Hocko
2016-05-31 7:42 ` Michal Hocko
2016-05-31 21:43 ` Oleg Nesterov
2016-05-31 21:43 ` Oleg Nesterov
2016-06-01 7:09 ` Michal Hocko
2016-06-01 7:09 ` Michal Hocko
2016-06-01 14:12 ` Tetsuo Handa
2016-06-01 14:25 ` Michal Hocko
2016-06-02 10:45 ` Tetsuo Handa
2016-06-02 11:20 ` Michal Hocko
2016-06-02 11:31 ` Tetsuo Handa
2016-06-02 12:55 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 5/6] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 18:18 ` Oleg Nesterov
2016-05-30 18:18 ` Oleg Nesterov
2016-05-31 7:43 ` Michal Hocko
2016-05-31 7:43 ` Michal Hocko
2016-05-31 21:48 ` Oleg Nesterov [this message]
2016-05-31 21:48 ` Oleg Nesterov
2016-05-30 13:05 ` [PATCH 6/6] mm, oom: fortify task_will_free_mem Michal Hocko
2016-05-30 13:05 ` Michal Hocko
2016-05-30 17:35 ` Oleg Nesterov
2016-05-30 17:35 ` Oleg Nesterov
2016-05-31 7:46 ` Michal Hocko
2016-05-31 7:46 ` Michal Hocko
2016-05-31 22:29 ` Oleg Nesterov
2016-05-31 22:29 ` Oleg Nesterov
2016-06-01 7:03 ` Michal Hocko
2016-06-01 7:03 ` Michal Hocko
2016-05-31 15:03 ` Tetsuo Handa
2016-05-31 15:10 ` Michal Hocko
2016-05-31 15:29 ` Tetsuo Handa
2016-06-01 7:25 ` Michal Hocko
2016-06-01 12:04 ` Tetsuo Handa
2016-06-01 12:43 ` Michal Hocko
2016-06-02 14:03 ` [PATCH 7/6] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-02 14:03 ` Michal Hocko
2016-06-02 15:24 ` Tetsuo Handa
2016-06-02 15:50 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2016-05-26 12:40 [PATCH 0/5] Handle oom bypass more gracefully Michal Hocko
2016-05-26 12:40 ` [PATCH 5/6] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-05-26 12:40 ` Michal Hocko
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