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Date: Thu, 16 Nov 2017 12:44:22 -0500
From: Johannes Weiner <hannes@cmpxchg.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Huang Ying <ying.huang@intel.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Shakeel Butt <shakeelb@google.com>, Greg Thelen <gthelen@google.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm,vmscan: Kill global shrinker lock.
Message-ID: <20171116174422.GC26475@cmpxchg.org>
References: <1510609063-3327-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
 <20171115005602.GB23810@bbox>
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On Wed, Nov 15, 2017 at 09:56:02AM +0900, Minchan Kim wrote:
> @@ -498,6 +498,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>  			sc.nid = 0;
>  
>  		freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
> +		/*
> +		 * bail out if someone want to register a new shrinker to prevent
> +		 * long time stall by parallel ongoing shrinking.
> +		 */
> +		if (rwsem_is_contended(&shrinker_rwsem)) {
> +			freed = 1;
> +			break;
> +		}
>  	}

When you send the formal version, please include

Acked-by: Johannes Weiner <hannes@cmpxchg.org>