linux-kernel - Re: [PATCH] mm/slab: fix kmemcg cache creation delayed issue

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Message-ID: <20161007051400.GA7294@js1304-P5Q-DELUXE>
Date:   Fri, 7 Oct 2016 14:14:01 +0900
From:   Joonsoo Kim <iamjoonsoo.kim@....com>
To:     Doug Smythies <dsmythies@...us.net>
Cc:     'Andrew Morton' <akpm@...ux-foundation.org>,
        'Christoph Lameter' <cl@...ux.com>,
        'Pekka Enberg' <penberg@...nel.org>,
        'David Rientjes' <rientjes@...gle.com>,
        'Johannes Weiner' <hannes@...xchg.org>,
        'Vladimir Davydov' <vdavydov.dev@...il.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] mm/slab: fix kmemcg cache creation delayed issue

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 superseded this patch.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.

Thanks.

> 
> References:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=172981
> https://bugzilla.kernel.org/show_bug.cgi?id=172991
> https://patchwork.kernel.org/patch/9361853
> https://patchwork.kernel.org/patch/9359271