From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751238AbaIJF4X (ORCPT ); Wed, 10 Sep 2014 01:56:23 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:60922 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbaIJF4V (ORCPT ); Wed, 10 Sep 2014 01:56:21 -0400 MIME-Version: 1.0 In-Reply-To: <20140909235534.GH24649@awork2.anarazel.de> References: <20140907.164109.1944849896872238507.davem@davemloft.net> <20140908212514.GA2348@awork2.anarazel.de> <20140909234806.GG24649@awork2.anarazel.de> <20140909235534.GH24649@awork2.anarazel.de> Date: Wed, 10 Sep 2014 09:56:19 +0400 Message-ID: Subject: Re: Macvlan WARNiNGS about duplicate sysfs filenames (Was [GIT] Networking) From: "Alexander Y. Fomichev" To: Andres Freund Cc: Cong Wang , David Miller , Linus Torvalds , Andrew Morton , netdev , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 10, 2014 at 3:55 AM, Andres Freund wrote: > On 2014-09-10 01:48:06 +0200, Andres Freund wrote: >> On 2014-09-09 15:43:55 -0700, Cong Wang wrote: >> > On Mon, Sep 8, 2014 at 2:25 PM, Andres Freund wrote: >> > > Hi, >> > > >> > > (don't have netdev archived, thus answering here, sorry) >> > > >> > > On 2014-09-07 16:41:09 -0700, David Miller wrote: >> > >> Alexander Y. Fomichev (1): >> > >> net: prevent of emerging cross-namespace symlinks >> > > >> > >> > Since you are quoting this change, are you saying it causes >> > the following kernel warning? >> >> I thought it might be a likely candidate; but I'm not sure at all. I'll >> verify it as soon as I can reboot the machine a couple of times (end of >> week-ish). >> >> > > I'm seeing WARNINGs like: >> > > [ 1005.269134] ------------[ cut here ]------------ >> > > [ 1005.269148] WARNING: CPU: 6 PID: 4213 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80() >> > > [ 1005.269150] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:1c.4/0000:03:00.0/net/eth0/upper_mv-eth0' >> > >> > >> > Is there a network device named upper_mv-eth0 existed in your system >> > before you created macvlan? >> >> No, there wasn't any. Afaics, the sequence is: >> 1) macvlan mv-eth0 is created in global namespace >> 2) mv-eth0 is moved (by systemd-nsspawn) into a new network >> namespace. Leaving a dangling symlink in the host namespace >> /devices/pci0000:00/0000:00:1c.4/0000:03:00.0/net/eth0/upper_mv-eth0 pointing toward >> ../mv-eth0 >> which doesn't exist in the external namespace. The new namespace seems >> to have broken 'lower_bond0' symlink as well >> >> This seems to be the case (and probably the actual root cause) in >> slightly earlier kernels as well. >> What changed seems to be that: >> 3) macvlan mv-eth0 is destroyed in the namespace (potentially while >> tearing it down) >> 4) Now there's a broken symlink that doesn't make sense in any namespace >> 5) mv-eth0 can't be created anew >> >> It seems that 3-5 didn't happen that way on older kernels. The most >> recent where it's not persistently broken is 3.16.0-rc7-00007 - >> 31dab719f. The oldest where I know it's reproducible is >> 3.17.0-rc4-andres-00135-g35af256. > > I've reproduced the problem on another machine where it's perfectly > reproducible (except being about mv-bond0). After reverting only the > aforementioned 4c75431ac352063 it works again. > As I said above, I'm not sure whether 4c75431ac352063 is the actual > culprit, but it certainly made the problem visible. How are these > upper_$if/lower_$if supposed to behave when the macvlan and the > underlying device are in differing namespaces? supposed to be destroyed before moving device into new net_ns and created just after but only if both lower/upper devices has the same netns. whether i understood you correctly that you see lowar_/upper_ links just after new container is up? > Greetings, > > Andres Freund -- Best regards. Alexander Y. Fomichev