Date: Fri, 7 Oct 2016 10:20:55 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Doug Smythies <dsmythies@telus.net>,
        "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'Christoph Lameter'" <cl@linux.com>,
        "'Pekka Enberg'" <penberg@kernel.org>,
        "'David Rientjes'" <rientjes@google.com>,
        "'Johannes Weiner'" <hannes@cmpxchg.org>,
        "'Vladimir Davydov'" <vdavydov.dev@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] mm/slab: fix kmemcg cache creation delayed issue
Message-ID: <20161007082055.GH18439@dhcp22.suse.cz>
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 <20161007051400.GA7294@js1304-P5Q-DELUXE>
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On Fri 07-10-16 14:14:01, Joonsoo Kim wrote:
> On Thu, Oct 06, 2016 at 09:02:00AM -0700, Doug Smythies wrote:
> > It was my (limited) understanding that the subsequent 2 patch set
> > superseded this patch. Indeed, the 2 patch set seems to solve
> > both the SLAB and SLUB bug reports.
> 
> It would mean that patch 1 solves both the SLAB and SLUB bug reports
> since patch 2 is only effective for SLUB.
> 
> Reason that I send this patch is that although patch 1 fixes the
> issue that too many kworkers are created, kmem_cache creation/destory
> is still slowed by synchronize_sched() and it would cause kmemcg
> usage counting delayed. I'm not sure how bad it is but it's generally
> better to start accounting as soon as possible. With patch 2 for SLUB
> and this patch for SLAB, performance of kmem_cache
> creation/destory would recover.

OK, so do we really want/need it for stable as well. I am not opposing
that but the effect doesn't seem to be a clear cut.
-- 
Michal Hocko
SUSE Labs