From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f48.google.com (mail-pb0-f48.google.com [209.85.160.48]) by kanga.kvack.org (Postfix) with ESMTP id 337B86B00DD for ; Fri, 21 Feb 2014 17:07:38 -0500 (EST) Received: by mail-pb0-f48.google.com with SMTP id rr13so4015551pbb.7 for ; Fri, 21 Feb 2014 14:07:37 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id o7si8527675pbh.212.2014.02.21.14.07.36 for ; Fri, 21 Feb 2014 14:07:37 -0800 (PST) Date: Fri, 21 Feb 2014 14:07:35 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: exclude memory less nodes from zone_reclaim Message-Id: <20140221140735.cef7531462f31c408012b8cb@linux-foundation.org> In-Reply-To: <1392889904-18019-1-git-send-email-mhocko@suse.cz> References: <1392889904-18019-1-git-send-email-mhocko@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: David Rientjes , Mel Gorman , Nishanth Aravamudan , linux-mm@kvack.org, LKML On Thu, 20 Feb 2014 10:51:44 +0100 Michal Hocko wrote: > We had a report about strange OOM killer strikes on a PPC machine > although there was a lot of swap free and a tons of anonymous memory > which could be swapped out. In the end it turned out that the OOM was > a side effect of zone reclaim which wasn't doesn't unmap and swapp out > and so the system was pushed to the OOM. Although this sounds like a bug > somewhere in the kswapd vs. zone reclaim vs. direct reclaim interaction > numactl on the said hardware suggests that the zone reclaim should > have been set in the first place: > node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 > node 0 size: 0 MB > node 0 free: 0 MB > node 2 cpus: > node 2 size: 7168 MB > node 2 free: 6019 MB > node distances: > node 0 2 > 0: 10 40 > 2: 40 10 > > So all the CPUs are associated with Node0 which doesn't have any memory > while Node2 contains all the available memory. Node distances cause an > automatic zone_reclaim_mode enabling. > > Zone reclaim is intended to keep the allocations local but this doesn't > make any sense on the memory less nodes. So let's exclude such nodes > for init_zone_allows_reclaim which evaluates zone reclaim behavior and > suitable reclaim_nodes. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1855,7 +1855,7 @@ static void __paginginit init_zone_allows_reclaim(int nid) > { > int i; > > - for_each_online_node(i) > + for_each_node_state(i, N_MEMORY) > if (node_distance(nid, i) <= RECLAIM_DISTANCE) > node_set(i, NODE_DATA(nid)->reclaim_nodes); > else > @@ -4901,7 +4901,8 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size, > > pgdat->node_id = nid; > pgdat->node_start_pfn = node_start_pfn; > - init_zone_allows_reclaim(nid); > + if (node_state(nid, N_MEMORY)) > + init_zone_allows_reclaim(nid); > #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP > get_pfn_range_for_nid(nid, &start_pfn, &end_pfn); > #endif What happens if someone later hot-adds some memory to that node? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org