From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 2B95D1396D0 for ; Sun, 20 Aug 2017 06:17:30 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 0FF36E0DD1; Sun, 20 Aug 2017 06:17:24 +0000 (UTC) Received: from smarthost01c.mail.zen.net.uk (smarthost01c.mail.zen.net.uk [212.23.1.5]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id AD6E4E0DC2 for ; Sun, 20 Aug 2017 06:17:23 +0000 (UTC) Received: from [82.69.83.178] (helo=mail.digimed.co.uk) by smarthost01c.mail.zen.net.uk with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1djJY1-0002y4-LV for gentoo-user@lists.gentoo.org; Sun, 20 Aug 2017 06:17:21 +0000 Received: from [10.144.243.206] (82-132-227-226.dab.02.net [82.132.227.226]) by mail.digimed.co.uk (Postfix) with ESMTPA id D00B59C6F76 for ; Sun, 20 Aug 2017 07:17:19 +0100 (BST) Date: Sun, 20 Aug 2017 09:17:15 +0300 User-Agent: K-9 Mail for Android In-Reply-To: References: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----81RHJOQ2VCZ27HC55URY8UPKZ86M77" Content-Transfer-Encoding: 7bit Subject: Re: [gentoo-user] Nameserver lookups fail on virtual server after Kernel upgrade from version 4.9 to 4.12 To: gentoo-user@lists.gentoo.org From: Neil Bothwick Message-ID: X-Originating-smarthost01c-IP: [82.69.83.178] Feedback-ID: 82.69.83.178 X-Archives-Salt: 7dc89f04-b152-416d-9d55-9370b1aacff0 X-Archives-Hash: 3bdff445c97b94948a4035444ef14515 ------81RHJOQ2VCZ27HC55URY8UPKZ86M77 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable I'd try again with a clean kernel tree but using make oldconfig=2E It's pos= sible the automagic stuff answered n somewhere where you need a y=2E=20 On 19 August 2017 21:28:05 EEST, Ralph Seichter wrote: >It seems strange to me as I write it, but since I updated one of my >virtual servers from Kernel version 4=2E9=2E34 to 4=2E12=2E5, the server >(Gentoo >Linux running as a KVM guest) is experiencing timeouts when trying to >connect to DNS resolvers=2E For the Kernel update, I followed the same >steps I used for years, like > > cd /usr/src/linux > zcat /proc/config=2Egz >=2Econfig > make silentoldconfig (answering "no" whereever possible) > make =2E=2E=2E > >After booting with Kernel 4=2E12, commands like "dig +trace www=2Eibm=2Ec= om" >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=2E > >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=2E >With Kernel 4=2E12, I see timeouts in both cases=2E These problems do not >occur when I boot with the 4=2E9 Kernel which I have been using for the >past two months=2E > >It is also worth noting that I updated two other servers to Kernel 4=2E12 >without any issues, but these are "real" servers, not VMs=2E At this >point >I am searching for ways to debug the issue, vaguely suspecting some KVM >magic behind it (without any proof)=2E I know that Kernel 4=2E11 introduc= ed >several KVM related changes, but that's about it=2E > >I appreciate all pointers=2E > >-Ralph --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E ------81RHJOQ2VCZ27HC55URY8UPKZ86M77 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable I'd try again with a clean kernel tree but usi= ng make oldconfig=2E It's possible the automagic stuff answered n somew= here where you need a y=2E

On 19 August = 2017 21:28:05 EEST, Ralph Seichter <m16+gentoo@monksofcool=2Enet> wro= te:
It seems strange to me as I write it, but since I up=
dated one of my
virtual servers from Kernel version 4=2E9=2E34 to 4=2E=
12=2E5, the server (Gentoo
Linux running as a KVM guest) is experienci=
ng timeouts when trying to
connect to DNS resolvers=2E For the Kernel =
update, I followed the same
steps I used for years, like

  =
cd /usr/src/linux
  zcat /proc/config=2Egz >=2Econfig
  make s=
ilentoldconfig (answering "no" whereever possible)
  make =
=2E=2E=2E

After booting with Kernel 4=2E12, commands like "=
dig +trace www=2Eibm=2Ecom"
work just fine for a while, duration depending on server load, but after<=
br />some threshold is passed, all further attempts to contact resolvers fa=
il
due to timeouts=2E

I have tried running a local, caching=
 resolver (BIND 9) on the server,
like I usually do, and also tried us=
ing the hoster's dedicated resolvers=2E
With Kernel 4=2E12, I see time=
outs in both cases=2E These problems do not
occur when I boot with the=
 4=2E9 Kernel which I have been using for the
past two months=2E
=

It is also worth noting that I updated two other servers to Kernel 4=
=2E12
without any issues, but these are "real" servers, not =
VMs=2E At this point
I am searching for ways to debug the issue, vague=
ly suspecting some KVM
magic behind it (without any proof)=2E I know t=
hat Kernel 4=2E11 introduced
several KVM related changes, but that's a=
bout it=2E

I appreciate all pointers=2E

-Ralph
<=
br />

--
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E ------81RHJOQ2VCZ27HC55URY8UPKZ86M77--