Re: Glibc recvmsg from kernel netlink socket hangs forever

[Jun Wang]

> On 09/25/2015 08:55 AM, Herbert Xu wrote:
>> On Thu, Sep 24, 2015 at 10:34:10PM -0700, Guenter Roeck wrote:
>>>
>>> Any idea what may be needed for 4.1 ?
>>> I am currently trying https://patchwork.ozlabs.org/patch/473041/,
>>
>> This patch should not make any difference on 4.1 and later because
>> 4.1 is where I rewrote rhashtable resizing and it should work (or
>> if it is broken then the latest kernel should be broken too).
>>
> Yes, applying (only) the above patch to 4.1 didn't help.
>
>>> but I have no idea if that will help with the problem we are seeing there.
>>
>> Having looked at your message agin I don't think the issue I
>> alluded to is relevant since the symptom there ought to be a
>> straight kernel lock-up as opposed to just a user-space one because
>> you will end up with the kernel sending a message to itself.
>>
>> And the fact that 4.2 works is more indicative as the bug is
>> present in both 4.1 and 4.2.
>>
>> I'll try to reproduce this in 4.1 as time permits but no promises.
>>
>
> I applied your patches (and a few additional netlink changes from 4.2)
> to our 4.1 branch. I'll let you know if it makes a difference for us.
>
> Thanks,
> Guenter

Guenter,

Which additional netlink changes from 4.2 did you patch? We still see
the problem with your test program with 4.1.12 which have the
following two patches mentioned by Herbert Xu on this thread.


> https://patchwork.ozlabs.org/patch/519245/
> https://patchwork.ozlabs.org/patch/520824/

Thanks,
Jun