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From: Gao feng <gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed
Date: Fri, 02 Nov 2012 17:02:37 +0800	[thread overview]
Message-ID: <50938C2D.90908@cn.fujitsu.com> (raw)
In-Reply-To: <87wqy4fkqx.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>

于 2012年11月02日 16:54, Eric W. Biederman 写道:
> Gao feng <gaofeng@cn.fujitsu.com> writes:
> 
>> 于 2012年11月02日 15:02, Eric W. Biederman 写道:
>>> Gao feng <gaofeng@cn.fujitsu.com> writes:
>>>
>>>> we should call pid_ns_release_proc to unmount pid_namespace's
>>>> proc_mnt when copy_net_ns failed in function create_new_namespaces.
>>>>
>>>> otherwise,the proc_mnt will not be freed and because the super_block
>>>> of proc_mnt also add the reference of the pid_namespace,so this
>>>> pid_namespace will never be released too.
>>>
>>> Ouch!
>>>
>>> Have you encountered this failure in practice or is this just from
>>> review?
>>
>> I add some printk in pid_ns_release_proc,it's not called in above case.
>> when copy_net_ns failed,this pid_namespace is not used by any task,
>> so proc_flush_task can't call pid_ns_release_proc to umount this pidns->proc_mnt.
>> it's the only chance we can unmount this pindns->proc_mnt.
>>
>> With this patch,everything runs well.
> 
> I have reviewed the code and I don't doubt that this is necessary.
> 
> What caused you to look into this failure?  Is there some semi-practical
> real world case that someone is hitting?
> 

So far,there is no case hitting this problem.
Thanks

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WARNING: multiple messages have this Message-ID (diff)
From: Gao feng <gaofeng@cn.fujitsu.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org
Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed
Date: Fri, 02 Nov 2012 17:02:37 +0800	[thread overview]
Message-ID: <50938C2D.90908@cn.fujitsu.com> (raw)
In-Reply-To: <87wqy4fkqx.fsf@xmission.com>

于 2012年11月02日 16:54, Eric W. Biederman 写道:
> Gao feng <gaofeng@cn.fujitsu.com> writes:
> 
>> 于 2012年11月02日 15:02, Eric W. Biederman 写道:
>>> Gao feng <gaofeng@cn.fujitsu.com> writes:
>>>
>>>> we should call pid_ns_release_proc to unmount pid_namespace's
>>>> proc_mnt when copy_net_ns failed in function create_new_namespaces.
>>>>
>>>> otherwise,the proc_mnt will not be freed and because the super_block
>>>> of proc_mnt also add the reference of the pid_namespace,so this
>>>> pid_namespace will never be released too.
>>>
>>> Ouch!
>>>
>>> Have you encountered this failure in practice or is this just from
>>> review?
>>
>> I add some printk in pid_ns_release_proc,it's not called in above case.
>> when copy_net_ns failed,this pid_namespace is not used by any task,
>> so proc_flush_task can't call pid_ns_release_proc to umount this pidns->proc_mnt.
>> it's the only chance we can unmount this pindns->proc_mnt.
>>
>> With this patch,everything runs well.
> 
> I have reviewed the code and I don't doubt that this is necessary.
> 
> What caused you to look into this failure?  Is there some semi-practical
> real world case that someone is hitting?
> 

So far,there is no case hitting this problem.
Thanks


  parent reply	other threads:[~2012-11-02  9:02 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-02  0:38 [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed Gao feng
     [not found] ` <1351816703-8805-1-git-send-email-gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2012-11-02  7:02   ` Eric W. Biederman
2012-11-02  7:02     ` Eric W. Biederman
     [not found]     ` <87ehkcij1a.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-02  7:33       ` Gao feng
2012-11-02  7:33         ` Gao feng
     [not found]         ` <5093773B.5010706-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2012-11-02  8:54           ` Eric W. Biederman
2012-11-02  8:54             ` Eric W. Biederman
     [not found]             ` <87wqy4fkqx.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-02  9:02               ` Gao feng [this message]
2012-11-02  9:02                 ` Gao feng
     [not found]                 ` <50938C2D.90908-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2012-11-02  9:10                   ` Eric W. Biederman
2012-11-02  9:10                     ` Eric W. Biederman
  -- strict thread matches above, loose matches on Subject: below --
2012-11-02  0:38 Gao feng

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