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Date:   Tue, 27 Aug 2019 15:53:22 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Hillf Danton <hdanton@sina.com>
Cc:     Yafang Shao <laoar.shao@gmail.com>,
        Adric Blake <promarbler14@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: WARNINGs in set_task_reclaim_state with memory
 cgroupandfullmemory usage
Message-ID: <20190827135322.GG7538@dhcp22.suse.cz>
References: <20190824130516.2540-1-hdanton@sina.com>
 <CALOAHbAuY9BnpX6x4KSNURbzybjn5UdSNL7-1Li3R0HSQBqiGQ@mail.gmail.com>
 <20190827132931.848986B0008@kanga.kvack.org>
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On Tue 27-08-19 21:29:24, Hillf Danton wrote:
> 
> >> No preference seems in either way except for retaining
> >> nr_to_reclaim == SWAP_CLUSTER_MAX and target_mem_cgroup == memcg.
> >
> > Setting  target_mem_cgroup here may be a very subtle change for
> > subsequent processing.
> > Regarding retraining nr_to_reclaim == SWAP_CLUSTER_MAX, it may not
> > proper for direct reclaim, that may cause some stall if we iterate all
> > memcgs here.
> 
> Mind posting a RFC to collect thoughts?

I hope I have explained why this is not desirable
http://lkml.kernel.org/r/20190827120335.GA7538@dhcp22.suse.cz
-- 
Michal Hocko
SUSE Labs