Re: [MAINTAINERS SUMMIT] [4/4] Discuss how to better prevent backports of commits that turn out to cause regressions

Greg KH
2024-06-13T14:02:41Z

On Thu, Jun 13, 2024 at 09:56:56AM -0400, James Bottomley wrote:
> On Thu, 2024-06-13 at 09:06 -0400, Sasha Levin wrote:
> > On Thu, Jun 13, 2024 at 07:58:58AM -0400, James Bottomley wrote:
> > > On Thu, 2024-06-13 at 10:42 +0200, Thorsten Leemhuis wrote:
> > > > The scenario shown at the start of the thread illustrates a
> > > > problem I see frequently: commits with a Fixes: tag end up in new
> > > > to stable series releases just days after being mainlined and
> > > > cause regressions -- just like they do in mainline, which just
> > > > was not known yet at the time of backporting. This happens
> > > > extremely often right after merge windows when huge piles of
> > > > changes are backported to the stable trees each cycle shortly
> > > > after -rc1 is out (which even some kernel developers apparently
> > > > are somewhat afraid to test from what I've
> > > > seen).
> > >
> > > I haven't really observed this for curated fixes.  For most
> > > subsystems, patches with Fixes tags that are cc'd to stable tend to
> > > go steadily outside the merge window.  Obviously a few arrive
> > > within it, but usually at roughly the rate they arrive outside it.
> > >
> > > What I observe in the merge window is huge piles of patches go into
> > > stable *without* a cc:stable tag from the autosel machinery (and
> > > quite a few even without fixes: tags).
> >
> > Could you provide a concrete example? This shouldn't happen.
>
> This one has no fixes or cc stable:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=37f1663c91934f664fb850306708094a324c227c
>
> Yet here it is backported:
>
> Message-id: 20240603121056.1837607-1-sashal@kernel.org
>
> (I can't give a lore reference because conveniently it was a personal
> cc with no tracked mailing list).
>
> I picked that one because we discovered a bug with the strlcpy to
> strscpy conversions in SCSI which it looks like this backport has.

It says, in the commit message:
Stable-dep-of: c3408c4ae041 ("scsi: qla2xxx: Avoid possible run-time warning with long model_num")

That is why it was backported.

thanks,

greg k-h