From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f52.google.com (mail-la0-f52.google.com [209.85.215.52]) by kanga.kvack.org (Postfix) with ESMTP id 5B87C6B0038 for ; Tue, 6 Oct 2015 21:01:27 -0400 (EDT) Received: by labzv5 with SMTP id zv5so1188245lab.1 for ; Tue, 06 Oct 2015 18:01:26 -0700 (PDT) Received: from mail-lb0-f172.google.com (mail-lb0-f172.google.com. [209.85.217.172]) by mx.google.com with ESMTPS id r7si19539541lfe.1.2015.10.06.18.01.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Oct 2015 18:01:25 -0700 (PDT) Received: by lbos8 with SMTP id s8so1230521lbo.0 for ; Tue, 06 Oct 2015 18:01:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <5612DCC8.4040605@gmail.com> References: <20151002101822.12499.27658.stgit@buzz> <56128238.8010305@suse.cz> <5612DCC8.4040605@gmail.com> From: Jesse Gross Date: Tue, 6 Oct 2015 18:01:06 -0700 Message-ID: Subject: Re: [ovs-dev] [PATCH] ovs: do not allocate memory from offline numa node Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Alexander Duyck , Jarno Rajahalme Cc: Vlastimil Babka , Konstantin Khlebnikov , "dev@openvswitch.org" , Pravin Shelar , "David S. Miller" , netdev , Linux Kernel Mailing List , linux-mm@kvack.org On Mon, Oct 5, 2015 at 1:25 PM, Alexander Duyck wrote: > On 10/05/2015 06:59 AM, Vlastimil Babka wrote: >> >> On 10/02/2015 12:18 PM, Konstantin Khlebnikov wrote: >>> >>> When openvswitch tries allocate memory from offline numa node 0: >>> stats = kmem_cache_alloc_node(flow_stats_cache, GFP_KERNEL | __GFP_ZERO, >>> 0) >>> It catches VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid)) >>> [ replaced with VM_WARN_ON(!node_online(nid)) recently ] in linux/gfp.h >>> This patch disables numa affinity in this case. >>> >>> Signed-off-by: Konstantin Khlebnikov >> >> >> ... >> >>> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c >>> index f2ea83ba4763..c7f74aab34b9 100644 >>> --- a/net/openvswitch/flow_table.c >>> +++ b/net/openvswitch/flow_table.c >>> @@ -93,7 +93,8 @@ struct sw_flow *ovs_flow_alloc(void) >>> >>> /* Initialize the default stat node. */ >>> stats = kmem_cache_alloc_node(flow_stats_cache, >>> - GFP_KERNEL | __GFP_ZERO, 0); >>> + GFP_KERNEL | __GFP_ZERO, >>> + node_online(0) ? 0 : NUMA_NO_NODE); >> >> >> Stupid question: can node 0 become offline between this check, and the >> VM_WARN_ON? :) BTW what kind of system has node 0 offline? > > > Another question to ask would be is it possible for node 0 to be online, but > be a memoryless node? > > I would say you are better off just making this call kmem_cache_alloc. I > don't see anything that indicates the memory has to come from node 0, so > adding the extra overhead doesn't provide any value. I agree that this at least makes me wonder, though I actually have concerns in the opposite direction - I see assumptions about this being on node 0 in net/openvswitch/flow.c. Jarno, since you original wrote this code, can you take a look to see if everything still makes sense? -- 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