Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752653AbbFDIZO (ORCPT ); Thu, 4 Jun 2015 04:25:14 -0400 Received: from mail-pd0-f177.google.com ([209.85.192.177]:36452 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752114AbbFDIZB (ORCPT ); Thu, 4 Jun 2015 04:25:01 -0400 From: Grant Likely Subject: Re: [PATCH] of: return NUMA_NO_NODE from fallback of_node_to_nid() To: Rob Herring , Konstantin Khlebnikov Cc: "devicetree@vger.kernel.org" , Rob Herring , "linux-kernel@vger.kernel.org" , sparclinux@vger.kernel.org, "linux-mm@kvack.org" , linuxppc-dev In-Reply-To: References: <20150408165920.25007.6869.stgit@buzz> <552BC6E8.1040400@yandex-team.ru> Date: Thu, 04 Jun 2015 14:45:23 +0900 Message-Id: <20150604054523.6D86DC40872@trevor.secretlab.ca> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2343 Lines: 60 On Mon, 13 Apr 2015 11:49:31 -0500 , Rob Herring wrote: > 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. Sounds like you're in agreement with this patch then? Shall I apply it? g. -- 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/