Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932472AbbDMQt6 (ORCPT ); Mon, 13 Apr 2015 12:49:58 -0400 Received: from mail-wi0-f176.google.com ([209.85.212.176]:36627 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932119AbbDMQtx (ORCPT ); Mon, 13 Apr 2015 12:49:53 -0400 MIME-Version: 1.0 In-Reply-To: <552BC6E8.1040400@yandex-team.ru> References: <20150408165920.25007.6869.stgit@buzz> <552BC6E8.1040400@yandex-team.ru> From: Rob Herring Date: Mon, 13 Apr 2015 11:49:31 -0500 Message-ID: Subject: Re: [PATCH] of: return NUMA_NO_NODE from fallback of_node_to_nid() To: Konstantin Khlebnikov Cc: Grant Likely , "devicetree@vger.kernel.org" , Rob Herring , "linux-kernel@vger.kernel.org" , sparclinux@vger.kernel.org, "linux-mm@kvack.org" , linuxppc-dev Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2095 Lines: 54 On Mon, Apr 13, 2015 at 8:38 AM, Konstantin Khlebnikov wrote: > On 13.04.2015 16:22, Rob Herring wrote: >> >> On Wed, Apr 8, 2015 at 11:59 AM, Konstantin Khlebnikov >> wrote: >>> >>> Node 0 might be offline as well as any other numa node, >>> in this case kernel cannot handle memory allocation and crashes. >>> >>> Signed-off-by: Konstantin Khlebnikov >>> Fixes: 0c3f061c195c ("of: implement of_node_to_nid as a weak function") >>> --- >>> drivers/of/base.c | 2 +- >>> include/linux/of.h | 5 ++++- >>> 2 files changed, 5 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/of/base.c b/drivers/of/base.c >>> index 8f165b112e03..51f4bd16e613 100644 >>> --- a/drivers/of/base.c >>> +++ b/drivers/of/base.c >>> @@ -89,7 +89,7 @@ EXPORT_SYMBOL(of_n_size_cells); >>> #ifdef CONFIG_NUMA >>> int __weak of_node_to_nid(struct device_node *np) >>> { >>> - return numa_node_id(); >>> + return NUMA_NO_NODE; >> >> >> This is going to break any NUMA machine that enables OF and expects >> the weak function to work. > > > Why? NUMA_NO_NODE == -1 -- this's standard "no-affinity" signal. > As I see powerpc/sparc versions of of_node_to_nid returns -1 if they > cannot find out which node should be used. Ah, I was thinking those platforms were relying on the default implementation. I guess any real NUMA support is going to need to override this function. The arm64 patch series does that as well. We need to be sure this change is correct for metag which appears to be the only other OF enabled platform with NUMA support. In that case, then there is little reason to keep the inline and we can just always enable the weak function (with your change). It is slightly less optimal, but the few callers hardly appear to be hot paths. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/