linux-kernel - Re: [PATCH 4/4] mm: shrinker: make shrinker not depend on memcg kmem

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Date:   Wed, 12 Jun 2019 13:11:04 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     ktkhai@...tuozzo.com, kirill.shutemov@...ux.intel.com,
        hannes@...xchg.org, mhocko@...e.com, hughd@...gle.com,
        shakeelb@...gle.com, rientjes@...gle.com,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] mm: shrinker: make shrinker not depend on memcg kmem

On Tue, Jun 11, 2019 at 10:07:54PM -0700, Yang Shi wrote:
> 
> 
> On 6/11/19 7:52 PM, Kirill A. Shutemov wrote:
> > On Fri, Jun 07, 2019 at 02:07:39PM +0800, Yang Shi wrote:
> > > Currently shrinker is just allocated and can work when memcg kmem is
> > > enabled.  But, THP deferred split shrinker is not slab shrinker, it
> > > doesn't make too much sense to have such shrinker depend on memcg kmem.
> > > It should be able to reclaim THP even though memcg kmem is disabled.
> > > 
> > > Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker,
> > > i.e. THP deferred split shrinker.  When memcg kmem is disabled, just
> > > such shrinkers can be called in shrinking memcg slab.
> > Looks like it breaks bisectability. It has to be done before makeing
> > shrinker memcg-aware, hasn't it?
> 
> No, it doesn't break bisectability. But, THP shrinker just can be called
> with kmem charge enabled without this patch.

So, if kmem is disabled, it will not be called, right? Then it is
regression in my opinion. This patch has to go in before 2/4.

-- 
 Kirill A. Shutemov