linux-kernel - Re: [PATCH v3 0/3] vmstats/vmevents flushing

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Message-ID: <20190826073332.GA7659@dhcp22.suse.cz>
Date:   Mon, 26 Aug 2019 09:33:32 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Roman Gushchin <guro@...com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH v3 0/3] vmstats/vmevents flushing

On Sat 24-08-19 13:53:39, Andrew Morton wrote:
> On Fri, 23 Aug 2019 00:33:51 +0000 Roman Gushchin <guro@...com> wrote:
> 
> > On Thu, Aug 22, 2019 at 04:27:09PM -0700, Andrew Morton wrote:
> > > On Mon, 19 Aug 2019 16:00:51 -0700 Roman Gushchin <guro@...com> wrote:
> > > 
> > > > v3:
> > > >   1) rearranged patches [2/3] and [3/3] to make [1/2] and [2/2] suitable
> > > >   for stable backporting
> > > > 
> > > > v2:
> > > >   1) fixed !CONFIG_MEMCG_KMEM build by moving memcg_flush_percpu_vmstats()
> > > >   and memcg_flush_percpu_vmevents() out of CONFIG_MEMCG_KMEM
> > > >   2) merged add-comments-to-slab-enums-definition patch in
> > > > 
> > > > Thanks!
> > > > 
> > > > Roman Gushchin (3):
> > > >   mm: memcontrol: flush percpu vmstats before releasing memcg
> > > >   mm: memcontrol: flush percpu vmevents before releasing memcg
> > > >   mm: memcontrol: flush percpu slab vmstats on kmem offlining
> > > > 
> > > 
> > > Can you please explain why the first two patches were cc:stable but not
> > > the third?
> > > 
> > > 
> > 
> > Because [1] and [2] are fixing commit 42a300353577 ("mm: memcontrol: fix
> > recursive statistics correctness & scalabilty"), which has been merged into 5.2.
> > 
> > And [3] fixes commit fb2f2b0adb98 ("mm: memcg/slab: reparent memcg kmem_caches
> > on cgroup removal"), which is in not yet released 5.3, so stable backport isn't
> > required.
> 
> OK, thanks.  Patches 1 & 2 are good to go but I don't think that #3 has
> had suitable review and I have a note here that Michal has concerns
> with it.

My concern was http://lkml.kernel.org/r/20190814113242.GV17933@dhcp22.suse.cz
so more of a code style kinda thing. Roman has chosen to stay with his
original form and added a comment that NR_SLAB_{UN}RECLAIMABLE are
magic. This is something I can live with even though I would have
preferred it a different way. Nothing serious enough to Nack or insist.
-- 
Michal Hocko
SUSE Labs