Re: net: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected in skb_array_produce

Dmitry Vyukov
2017-02-18T17:29:03Z

On Fri, Feb 10, 2017 at 6:17 AM, Jason Wang <jasowang@redhat.com> wrote:
>
>
> On 2017年02月10日 02:10, Michael S. Tsirkin wrote:
>>
>> On Thu, Feb 09, 2017 at 05:02:31AM -0500, Jason Wang wrote:
>>>
>>> ----- Original Message -----
>>>>
>>>> Hello,
>>>>
>>>> I've got the following report while running syzkaller fuzzer on mmotm
>>>> (git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git)
>>>> remotes/mmotm/auto-latest ee4ba7533626ba7bf2f8b992266467ac9fdc045e:
>>>>
>>> [...]
>>>
>>>> other info that might help us debug this:
>>>>
>>>> Possible interrupt unsafe locking scenario:
>>>>
>>>> CPU0 CPU1
>>>> ---- ----
>>>> lock(&(&r->consumer_lock)->rlock);
>>>> local_irq_disable();
>>>> lock(&(&r->producer_lock)->rlock);
>>>> lock(&(&r->consumer_lock)->rlock);
>>>> <Interrupt>
>>>> lock(&(&r->producer_lock)->rlock);
>>>>
>>> Thanks a lot for the testing.
>>>
>>> Looks like we could address this by using skb_array_consume_bh() instead.
>>>
>>> Could you pls verify if the following patch works?
>>
>> I think we should use _bh for the produce call as well,
>> since resizing takes the producer lock.
>
> Looks not since irq was disabled during resizing?

Hello,

Is there a fix for this that we can pick up?
This killed 10'000 VMs on our testing infra over the last day. Still
happening on linux-next.

Thanks