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Date:   Thu, 15 Jul 2021 09:07:16 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Sasha Levin <sashal@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Hugh Dickins <hughd@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org
Subject: Re: 5.13.2-rc and others have many not for stable
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On Wed 14-07-21 11:30:46, Sasha Levin wrote:
> On Wed, Jul 14, 2021 at 09:52:58AM +0200, Michal Hocko wrote:
> > On Tue 13-07-21 18:28:13, Andrew Morton wrote:
> > > At present this -stable
> > > promiscuity is overriding the (sometime carefully) considered decisions
> > > of the MM developers, and that's a bit scary.
> > 
> > Not only scary, it is also a waste of precious time of those who
> > carefuly evaluate stable tree backports.
> 
> I'm just as concerned with the other direction: we end up missing quite
> a lot of patches that are needed in practice, and no one is circling
> back to make sure that we have everything we need.
> 
> I took a peek at SUSE's tree to see how things work there, and looking
> at the very latest mm/ commit:
> 
> commit c8c7b321edcf7a7e8c22dc66e0366f72aa2390f0
> Author: Michal Koutn? <mkoutny@suse.com>
> Date:   Tue May 4 11:12:10 2021 +0200
> 
>     mm: memcontrol: fix cpuhotplug statistics flushing
>     (bsc#1185606).
>     suse-commit: 3bba386a33fac144abf2507554cb21552acb16af
> 
> This seems to be commit a3d4c05a4474 ("mm: memcontrol: fix cpuhotplug
> statistics flushing") upstream, and I assume that it was picked because
> it fixed a real bug someone cares about.

Nope. It has been identified as potentially useful/nice to have. There
was no actual bug report requiring it. We do that a lot. In fact we do
have a full infrastructure around git fixes and backport fixes
proactively. Mostly because stable tree, which we used to track in the
past, has turned out to be overwhelming with questionable/risky
backports. The thing, though, is that those fixes are carefully reviewed
by a domain expert before backporting. 

> I can maybe understand that at the time that the patch was
> written/committed it didn't seem like stable@ material and thus there
> was no cc to stable.
> 
> But once someone realized it needs to be backported, why weren't we told
> to take it into stable too?

We tend to do that for many real bug reports.
-- 
Michal Hocko
SUSE Labs