Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 18 Feb 2021 09:24:55 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     Tim Chen <tim.c.chen@linux.intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Ying Huang <ying.huang@intel.com>, linux-mm@kvack.org,
        cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] mm: Fix dropped memcg from mem cgroup soft limit
 tree
Message-ID: <YC4kV7dkJpxjW+df@dhcp22.suse.cz>
References: <cover.1613584277.git.tim.c.chen@linux.intel.com>
 <8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen@linux.intel.com>
Precedence: bulk

On Wed 17-02-21 12:41:34, Tim Chen wrote:
> During soft limit memory reclaim, we will temporarily remove the target
> mem cgroup from the cgroup soft limit tree.  We then perform memory
> reclaim, update the memory usage excess count and re-insert the mem
> cgroup back into the mem cgroup soft limit tree according to the new
> memory usage excess count.
> 
> However, when memory reclaim failed for a maximum number of attempts
> and we bail out of the reclaim loop, we forgot to put the target mem
> cgroup chosen for next reclaim back to the soft limit tree. This prevented
> pages in the mem cgroup from being reclaimed in the future even though
> the mem cgroup exceeded its soft limit.  Fix the logic and put the mem
> cgroup back on the tree when page reclaim failed for the mem cgroup.
> 
> Reviewed-by: Ying Huang <ying.huang@intel.com>
> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>

I have already acked this patch in the previous version along with Fixes
tag. It seems that my review feedback has been completely ignored also
for other patches in this series.

> ---
>  mm/memcontrol.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index ed5cc78a8dbf..a51bf90732cb 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3505,8 +3505,12 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
>  			loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
>  			break;
>  	} while (!nr_reclaimed);
> -	if (next_mz)
> +	if (next_mz) {
> +		spin_lock_irq(&mctz->lock);
> +		__mem_cgroup_insert_exceeded(next_mz, mctz, excess);
> +		spin_unlock_irq(&mctz->lock);
>  		css_put(&next_mz->memcg->css);
> +	}
>  	return nr_reclaimed;
>  }
>  
> -- 
> 2.20.1

-- 
Michal Hocko
SUSE Labs