Re: [gentoo-user] Nameserver lookups fail on virtual server after Kernel upgrade from version 4.9 to 4.12

[Craig MacKinder]

It sounds like this vmxnet3 bug causing intermittent interface problems

https://bugzilla.kernel.org/show_bug.cgi?id=191201

Try adding this to the VMware guest advanced settings.

vmxnet3.rev.30 = FALSE

And restart the guests.



--

Craig



On Aug 19, 2017, at 11:28 AM, Ralph Seichter <m16+gentoo@×××××××××××.net<mailto:m16+gentoo@×××××××××××.net>> wrote:



It seems strange to me as I write it, but since I updated one of my

virtual servers from Kernel version 4.9.34 to 4.12.5, the server (Gentoo

Linux running as a KVM guest) is experiencing timeouts when trying to

connect to DNS resolvers. For the Kernel update, I followed the same

steps I used for years, like



 cd /usr/src/linux

 zcat /proc/config.gz >.config

 make silentoldconfig (answering "no" whereever possible)

 make ...



After booting with Kernel 4.12, commands like "dig +trace www.ibm.com<http://www.ibm.com>"

work just fine for a while, duration depending on server load, but after

some threshold is passed, all further attempts to contact resolvers fail

due to timeouts.



I have tried running a local, caching resolver (BIND 9) on the server,

like I usually do, and also tried using the hoster's dedicated resolvers.

With Kernel 4.12, I see timeouts in both cases. These problems do not

occur when I boot with the 4.9 Kernel which I have been using for the

past two months.



It is also worth noting that I updated two other servers to Kernel 4.12

without any issues, but these are "real" servers, not VMs. At this point

I am searching for ways to debug the issue, vaguely suspecting some KVM

magic behind it (without any proof). I know that Kernel 4.11 introduced

several KVM related changes, but that's about it.



I appreciate all pointers.



-Ralph