[CentOS] kpatch (live kernel patching) in CentOS 7.7?

Phelps, Matthew mphelps at cfa.harvard.edu
Fri Oct 4 13:35:51 UTC 2019


On Fri, Oct 4, 2019 at 9:24 AM Stephen John Smoogen <smooge at gmail.com>
wrote:

> On Fri, 4 Oct 2019 at 08:18, Phelps, Matthew <mphelps at cfa.harvard.edu>
> wrote:
> >
> > On Fri, Oct 4, 2019 at 6:33 AM Jim Perrin <jperrin at centos.org> wrote:
> >
> > >
> > >
> > > On 10/3/19 9:35 PM, Stephen John Smoogen wrote:
> > > > On Thu, 3 Oct 2019 at 13:52, Phelps, Matthew <
> mphelps at cfa.harvard.edu>
> > > wrote:
> > > >>
> > > >> On Thu, Oct 3, 2019 at 1:42 PM Jim Perrin <jperrin at centos.org>
> wrote:
> > > >>
> > > >>>
> > > >>>
> > > >>> On 10/3/19 1:32 PM, Phelps, Matthew wrote:
> > > >>>> Forgive me if this has been answered before and I've missed it.
> > > >>>>
> > > >>>> This https://access.redhat.com/solutions/2206511 says live kernel
> > > >>> patches
> > > >>>> will be available via yum updates as of RHEL 7.7. Is this carried
> > > over to
> > > >>>> CentOS 7.7.1908?
> > > >>>>
> > > >>>
> > > >>> The functionality should be available, but we don't provide
> patches in
> > > >>> this way, no.
> > > >
> > > >>
> > > >> What would it take to make this happen? This would be a huge help to
> > > those
> > > >> of us running servers. Not to mention it would make the world a more
> > > secure
> > > >> place :)
> > > >>
> > >
> > > The short answer is "a team of kernel engineers, which we don't have".
> > > Smooge's overview which I've left below is great at explaining some of
> > > this:
> > >
> > >
> > I don't understand. If RHEL is putting out patches, and CentOS is a
> > recompile of RHEL, hasn't that "team of kernel engineers " already done
> the
> > work?
> >
>
> No. because most of the work on making a patch is after the kernel is
> compiled and working. Thus even though you have the same source code,
> similar compilers etc.. there are going to be differences which have
> to be looked at to make sure it is really working. A CentOS kernel is
> not exactly the same as a RHEL kernel is not the same as a Oracle
> kernel is not the same as the one you recompiled locally. From most
> operational points they seem the same, but kernel patching is where
> those differences really show up.
>
> Yes it would be easy to set up some automated tool which 'made'
> kpatches.. and I expect they may 'work' for most systems. But I also
> expect that they would also eat babies more times than people would
> like. If sites really need them, they can set up the tooling
> themselves and make them work when they know they want it. Trying to
> make it a general purpose answer for something which may corrupt data
> 5 or 20% or 40% of the time.. is just waiting to be on Slashdot daily
> (wait do we do Slashdot anymore.. Reddit? nope the kids aren't there
> anymore either.. ok someplace daily) in a bad way.
>
>
>
Thanks for the explanation(s).

I'm still puzzled why RedHat is doing it then, and making it more generally
available (to paying customers even), if it's so dire a proposition that it
will fail so badly, so often. That seems counter-intuitive to me.

Anyway, I again point out that the CentOS documentation should be made
clear that this functionality won't ever be coming to CentOS.

-Matt


-- 

*Matt Phelps*

*Information Technology Specialist, Systems Administrator*

(Computation Facility, Smithsonian Astrophysical Observatory)

Center for Astrophysics | Harvard & Smithsonian


60 Garden Street | MS 39 | Cambridge, MA 02138
email: mphelps at cfa.harvard.edu


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