linux-kernel - Re: [BUG] act_ife: sleeping functions called in atomic context

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Message-ID: <CAM_iQpVkFvgbYQsVB0hFKa5zVa1KCPAz=cQ7sAXdJwNM=8hpzQ@mail.gmail.com>
Date:	Thu, 16 Jun 2016 19:14:36 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Jamal Hadi Salim <jhs@...atatu.com>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	"David S. Miller" <davem@...emloft.net>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, ldv-project@...uxtesting.org
Subject: Re: [BUG] act_ife: sleeping functions called in atomic context

On Thu, Jun 16, 2016 at 5:38 PM, Jamal Hadi Salim <jhs@...atatu.com> wrote:
> On 16-06-16 05:43 PM, Cong Wang wrote:
>>
>> On Thu, Jun 16, 2016 at 1:50 PM, Alexey Khoroshilov
>> <khoroshilov@...ras.ru> wrote:
>>>
>>> tcf_ife_init() contains a big chunk of code executed with
>>> ife->tcf_lock spinlock held. But that code contains several calls
>>> to sleeping functions:
>>>    populate_metalist() and use_all_metadata()
>>>      -> add_metainfo()
>>>        -> find_ife_oplist(metaid)
>>>          -> read_lock()
>>>          -> try_module_get(o->owner)
>>>        -> kzalloc(sizeof(*mi), GFP_KERNEL);
>>
>>
>> Hmm, we don't need to hold that spinlock when we create a new ife action,
>> since we haven't inserted it yet. We do need it when we modify an existing
>> one. So I am thinking if we can refactor that code to avoid spinlock
>> whenever possible.
>>
>
> Does attached (compile tested) patch help?

You at least miss the unlock in load_metaops_and_vet()?

I think we can just remove that tcf_lock, I am testing a patch now.