[dpdk-dev] [v3] kni: fix possible kernel crash with va2pa

[Ferruh Yigit]

On 7/10/2019 9:40 PM, yoursunny wrote:
> Hi Ferruh
> 
> I've uploaded my test case to Bug 183.
> You can determine whether it is a bug that should be covered by this
> patch, or it should be handled separately.

Thanks for clarification,
your use case is about indirect mbufs, I can see why it is not working from your
explanation in the bug report.
I think previously when all mbufs were coming from same physically continuous
memory, indirect mbufs should work. Right now I don't know how to support them.

This defect fixes an issue for multi segment packages, caused by wrong address
calculation for next segments.

So I am for continuing with this patch, independent from indirect mbufs issue.

Do you have any other issue, except than the indirect mbuf issue, if you have
other KNI use cases?


> 
> Yours, Junxiao
> 
> On Wed, Jul 10, 2019 at 4:11 PM Ferruh Yigit <ferruh.yigit at intel.com> wrote:
>>
>> On 7/2/2019 9:07 PM, Junxiao Shi wrote:
>>> I am battling a related problem as reported on
>>> https://bugs.dpdk.org/show_bug.cgi?id=183 and this patch seems
>>> relevant, so I applied this patch on 196a46fab6eeb3ce2039e3bcaca80f8ba43ffc8d
>>>
>>> However, this patch does not work for me:
>>> with CONFIG_RTE_LIBRTE_MBUF_DEBUG enabled, kni_free_mbufs's invocation of
>>> rte_pktmbuf_free throws "bad mbuf pool" error.
>>>
>>> While all mbufs and segments in kni->rx_q now have physical addresses,
>>> the mbufs and segments placed back to kni->free_q still have (mis-)calculated
>>> virtual address. The pa2va function is not working properly.
>>>
>>> Consequently, userspace side is passing wrong pointer to rte_pktmbuf_free,
>>> so that application crashes with CONFIG_RTE_LIBRTE_MBUF_DEBUG enabled.
>>>
>>
>> Hi Junxiao,
>>
>> I don't see any issue in the code, and as far as I tested not seeing any issue.
>>
>> Can you please provide more information how to reproduce the issue, is it only
>> enabling "CONFIG_RTE_LIBRTE_MBUF_DEBUG" config?
>>
>> Thanks,
>> ferruh