[Ksummit-discuss] [CORE TOPIC] Issues with stable process

NeilBrown neilb at suse.com
Mon Jul 13 05:10:12 UTC 2015


On Mon, 13 Jul 2015 00:27:52 -0400 Sasha Levin <sasha.levin at oracle.com>
wrote:

> On 07/12/2015 08:52 PM, NeilBrown wrote:
> > My proposal would be to change the default timing.
> > Currently patches tagged for 'stable' go into the next -stable release
> > after they get into Linus's tree.  You can ask for an exception
> > (sooner, later, different patch) and Greg (or any other stable
> > maintainer) tries to be accommodating.  But you have to remember to ask.
> > 
> > I would rather that the default was that patches don't go into -stable
> > until they have
> >   - been in a full release from Linus and
> >   - been in a Linus's tree for at least 2 weeks.
> >     (or 1 week times the age of the target in releases.
> >      So a fix in 4.4 get to 4.3-stable after a week, 4.2-stable
> >      after 2 weeks etc .... maybe I'm going over-board here).
> > 
> > Many fixes are important but simply aren't that urgent so the two or
> > more weeks is no great cost.
> 
> I'd actually argue that Linus shouldn't be pulling *anything* that wasn't in
> -next for 2+ weeks. There's no good excuse to want something pulled immediately
> as the only benefit Linus's tree provides in that aspect is the wider testing
> it receives, so it would make sense to weed out more bugs in -next before they
> get to Linus.

As long as there is a clear 2 week window between a patch being "out
there for wide testing" and being auto-pulled into a -stable, I would
see an improvement.

However I'm not at all convinced that being in -next is really "out
there for wide testing".  Certainly some testing happens in -next, but
my understand is that it is mainly about integration testing, not
burn-in testing.

Isn't the point of the 2-week merge window is that we all stop writing
more bugs and instead start testing to find each others bugs?  You seem
to want to make the previous two weeks fill that role.  I don't think
that would work.



> 
> I think that this is a small mind-shift from thinking about Linus's tree as
> an integration tree to considering it as mostly bug-free code, and stop
> merging in risky patches. We already have -next for that.

I certainly do see Linus's tree as mostly bug-free code.  Certainly I
don't submit something until I'm reasonably confident.  Unfortunately I
am sometimes wrong.  Usually by rc8 it is a lot closer to bug-free.
That steady improvement is the whole point.  So going from rc8 to
stable makes lots more sense than going from rc1 to stable.


> 
> > If a developer/maintainer thinks a fix is urgent, then they need to
> > explicitly ask for a quick release, and that could be as easy as saying:
> > 
> >   Cc: stable at vger.kernel.org (URGENT v3.0 and later)
> > 
> > An 'URGENT' fix *should* come with an independent
> > "Reviewed-by:"  (well ... everything should of course, but if URGENT
> > stable patches with no Reviewed-by got some push-back, I think that
> > would be a "very good thing" all around).
> 
> I suppose that this is something Linus/maintainers would need to enforce? No
> patch unless it lived in -next unless it was acked by the maintainer of that
> subsystem?
> 
> > I don't think that tightening the criteria for going into any
> > particular tree will really help.  I'm not sure there is even real
> > agreement on what is or is not allowed in -stable (we have clearly
> > written rules, but the practice is really whatever a maintainer
> > chooses).
> > -rc prereleases for -stable would only help if people tested them.
> > Given that the same bugs are in -linus, the testing done there should
> > be sufficient providing it is given enough time.
> 
> My reasoning for -rc prereleases for stable was to test out the backports that
> go into stable kernels: they don't see the light of day until they're shipped
> out to folks who want *stable* kernels, but end up being the first testers of
> a backport.

That is certainly a worthy goal - if the testing actually eventuates.

Thanks,
NeilBrown


> 
> I don't want to suggest that we do a few of those per stable kernel, but even
> one -rc release that would end up in distros (marked as "proposed/devel") and
> would let users test that would be a great step forward.
> 
> The reason I've suggested it for Ksummit rather than hashing it out on stable@
> is that I believe that the solution is more complex and would need more discussion
> than just slapping a "cooldown period" on patches. We need to make sure less
> bugs/untested code ends up in Linus's tree to begin with, and we need a way to
> validate proposed stable releases before releasing them, since -stable users
> aren't interested in being testers.
> 
> 
> Thanks,
> Sasha



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