From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yh0-f44.google.com (mail-yh0-f44.google.com [209.85.213.44]) by kanga.kvack.org (Postfix) with ESMTP id 221D16B0037 for ; Thu, 5 Dec 2013 18:21:04 -0500 (EST) Received: by mail-yh0-f44.google.com with SMTP id f64so13329277yha.31 for ; Thu, 05 Dec 2013 15:21:03 -0800 (PST) Received: from mail-yh0-x22b.google.com (mail-yh0-x22b.google.com [2607:f8b0:4002:c01::22b]) by mx.google.com with ESMTPS id y62si60267966yhc.69.2013.12.05.15.21.02 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 05 Dec 2013 15:21:03 -0800 (PST) Received: by mail-yh0-f43.google.com with SMTP id a41so12542369yho.2 for ; Thu, 05 Dec 2013 15:21:02 -0800 (PST) Date: Thu, 5 Dec 2013 15:21:00 -0800 (PST) From: David Rientjes Subject: Re: [PATCH] mm, x86: Skip NUMA_NO_NODE while parsing SLIT In-Reply-To: <52A054A0.6060108@jp.fujitsu.com> Message-ID: References: <1386191348-4696-1-git-send-email-toshi.kani@hp.com> <52A054A0.6060108@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: Toshi Kani , akpm@linux-foundation.org, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org On Thu, 5 Dec 2013, Yasuaki Ishimatsu wrote: > (2013/12/05 6:09), Toshi Kani wrote: > > When ACPI SLIT table has an I/O locality (i.e. a locality unique > > to an I/O device), numa_set_distance() emits the warning message > > below. > > > > NUMA: Warning: node ids are out of bound, from=-1 to=-1 distance=10 > > > > acpi_numa_slit_init() calls numa_set_distance() with pxm_to_node(), > > which assumes that all localities have been parsed with SRAT previously. > > SRAT does not list I/O localities, where as SLIT lists all localities > > > including I/Os. Hence, pxm_to_node() returns NUMA_NO_NODE (-1) for > > an I/O locality. I/O localities are not supported and are ignored > > today, but emitting such warning message leads unnecessary confusion. > > In this case, the warning message should not be shown. But if SLIT table > is really broken, the message should be shown. Your patch seems to not care > for second case. > It's a subtle problem of the difference in the definition of a "NUMA node" between the ACPI specification and how it is defined in the kernel. The specification allows I/O buses to define a NUMA node and the kernel doesn't setup a separate node id for them, so there's no way to distinguish between an erroneous SLIT and system localities that only include I/O devices. If that were to change in the future we could remove this limitation since pxm_to_node() wouldn't return NUMA_NO_NODE for Toshi's config. A follow-up patch that adds the comment about why this is done has been proposed to be folded into this patch. -- 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