[OpenAFS] RHEL 7.5 beta / 3.10.0-830.el7.x86_66 kernel lock up

[Anders Nordin]

Hello,

Is there any progress on this issue? Can we expect a stable release for RHE=
L 7.5?

MVH
Anders

-----Original Message-----
From: openafs-info-admin@openafs.org [mailto:openafs-info-admin@openafs.org=
] On Behalf Of Benjamin Kaduk
Sent: den 9 februari 2018 01:02
To: Kodiak Firesmith <kfiresmith@gmail.com>
Cc: openafs-info <openafs-info@openafs.org>
Subject: Re: [OpenAFS] RHEL 7.5 beta / 3.10.0-830.el7.x86_66 kernel lock up

On Wed, Feb 07, 2018 at 11:46:28AM -0500, Kodiak Firesmith wrote:
> Hello again All,
>=20
> As part of continued testing, I've been able to confirm that the=20
> SystemD double-service startup thing only happens to my hosts when=20
> going from RHEL
> 7.4 to RHEL 7.5beta.  On a test host installed directly as RHEL=20
> 7.5beta, I get a bit farther with 1.6.18.22, in that I get to the=20
> point where OpenAFS "kind of" works.

Thanks for tracking this down.  The rpm packaging maintainers may want to t=
ry to track down why the double-start happens in the upgrade scenario, as t=
hat's pretty nasty behavior.

> What I'm observing is that the openafs client Kernel module (built by=20
> DKMS) loads fine, and just so long as you know where you need to go in=20
> /afs, you can get there, and you can read and write files and the OpenAFS=
 'fs'
> command works.  But doing an 'ls' of /afs or any path underneath=20
> results in
> "ls: reading directory /afs/: Not a directory".
>=20
> I ran an strace of a good RHEL 7.4 host running ls on /afs, and a RHEL=20
> 7.5beta host running ls on /afs and have created pastebins of both, as=20
> well as an inline diff.
>=20
> All can be seen at the following locations:
>=20
> works
> https://paste.fedoraproject.org/paste/Hiojt2~Be3wgez47bKNucQ
>=20
> fails
> https://paste.fedoraproject.org/paste/13ZXBfJIOMsuEJFwFShBfg
>=20
>=20
> diff
> https://paste.fedoraproject.org/paste/FJKRwep1fWJogIDbLnkn8A
>=20
> Hopefully this might help the OpenAFS devs, or someone might know what=20
> might be borking on every RHEL 7.5 beta host.  It does fit with what=20
> other
> 7.5 beta users have observed OpenAFS doing.

Yes, now it seems like all our reports are consistent, and we just have to =
wait for a developer to get a better look at what Red Hat changed in the ke=
rnel that we need to adapt to.

-Ben

> Thanks!
>  - Kodiak
>=20
> On Mon, Feb 5, 2018 at 12:31 PM, Stephan Wiesand=20
> <stephan.wiesand@desy.de>
> wrote:
>=20
> >
> > > On 04.Feb 2018, at 02:11, Jeffrey Altman <jaltman@auristor.com> wrote=
:
> > >
> > > On 2/2/2018 6:04 PM, Kodiak Firesmith wrote:
> > >> I'm relatively new to handling OpenAFS.  Are these problems part=20
> > >> of a normal "kernel release; openafs update" cycle and perhaps=20
> > >> I'm getting snagged just by being too early of an adopter?  I=20
> > >> wanted to raise the alarm on this and see if anything else was=20
> > >> needed from me as the reporter of the issue, but perhaps that's=20
> > >> an overreaction to what is just part of a normal process I just=20
> > >> haven't been tuned into in prior RHEL release cycles?
> > >
> > >
> > > Kodiak,
> > >
> > > On RHEL, DKMS is safe to use for kernel modules that restrict=20
> > > themselves to using the restricted set of kernel interfaces (the=20
> > > RHEL KABI) that Red Hat has designated will be supported across=20
> > > the lifespan of the RHEL major version number.  OpenAFS is not=20
> > > such a kernel module.  As a result it is vulnerable to breakage each =
and every time a new kernel is shipped.
> >
> > Jeffrey,
> >
> > the usual way to use DKMS is to either have it build a module for a=20
> > newly installed kernel or install a prebuilt module for that kernel.=20
> > It may be possible to abuse it for providing a module built for=20
> > another kernel, but I think that won't happen accidentally.
> >
> > You may be confusing DKMS with RHEL's "KABI tracking kmods". Those=20
> > should be safe to use within a RHEL minor release (and the SL=20
> > packaging has been using them like this since EL6.4), but aren't=20
> > across minor releases (and that's why the SL packaging modifies the=20
> > kmod handling to require a build for the minor release in question.
> >
> > > There are two types of failures that can occur:
> > >
> > > 1. a change results in failure to build the OpenAFS kernel module
> > >    for the new kernel
> > >
> > > 2. a change results in the OpenAFS kernel module building and
> > >    successfully loading but failing to operate correctly
> >
> > The latter shouldn't happen within a minor release, but can across=20
> > minor releases.
> >
> > > It is the second of these possibilities that has taken place with=20
> > > the release of the 3.10.0-830.el7 kernel shipped as part of the=20
> > > RHEL 7.5
> > beta.
> > >
> > > Are you an early adopter of RHEL 7.5 beta?  Absolutely, its a beta=20
> > > release and as such you should expect that there will be bugs and=20
> > > that third party kernel modules that do not adhere to the KABI=20
> > > functionality might have compatibility issues.
> >
> > The -830 kernel can break 3rd-party modules using non-whitelisted=20
> > ABIs, whether or not they adhere to the "KABI functionality".
> >
> > > There was a compatibility issue with RHEL 7.4 kernel
> > > (3.10.0_693.1.1.el7) as well that was only fixed in the OpenAFS=20
> > > 1.6 release series this past week as part of 1.6.22.2:
> > >
> > >  http://www.openafs.org/dl/openafs/1.6.22.2/RELNOTES-1.6.22.2
> >
> > Yes, and this one was hard to fix. Thanks are due to Mark Vitale for=20
> > developing the fix and all those who reviewed and tested it.
> >
> > > Jeffrey Altman
> > > AuriStor, Inc.
> > >
> > > P.S. - Welcome to the community.
> >
> > Seconded. In particular, the problem report regarding the EL7.5beta=20
> > kernel was absolutely appropriate.
> >
> > --
> > Stephan Wiesand
> > DESY - DV -
> > Platanenallee 6
> > 15738 Zeuthen, Germany
> >
> >
> >
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