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Date: Fri, 27 Mar 2015 13:17:59 -0700
From: Dave Hansen <dave.hansen@intel.com>
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To: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>,
        Mel Gorman <mgorman@suse.de>
CC: anton@sambar.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Rik van Riel <riel@redhat.com>, Dan Streetman <ddstreet@ieee.org>
Subject: Re: [PATCH] mm: vmscan: do not throttle based on pfmemalloc reserves
 if node has no reclaimable zones
References: <20150327192850.GA18701@linux.vnet.ibm.com>
In-Reply-To: <20150327192850.GA18701@linux.vnet.ibm.com>
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On 03/27/2015 12:28 PM, Nishanth Aravamudan wrote:
> @@ -2585,7 +2585,7 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
>  
>         for (i = 0; i <= ZONE_NORMAL; i++) {
>                 zone = &pgdat->node_zones[i];
> -               if (!populated_zone(zone))
> +               if (!populated_zone(zone) || !zone_reclaimable(zone))
>                         continue;
>  
>                 pfmemalloc_reserve += min_wmark_pages(zone);

Do you really want zone_reclaimable()?  Or do you want something more
direct like "zone_reclaimable_pages(zone) == 0"?