From: David Rientjes <rientjes@google.com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>,
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
Subject: Re: [PATCH] mm, x86: Skip NUMA_NO_NODE while parsing SLIT
Date: Thu, 5 Dec 2013 15:21:00 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.02.1312051517130.7717@chino.kir.corp.google.com> (raw)
In-Reply-To: <52A054A0.6060108@jp.fujitsu.com>
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.
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prev parent reply other threads:[~2013-12-05 23:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-04 21:09 Toshi Kani
2013-12-05 10:25 ` Yasuaki Ishimatsu
2013-12-05 15:11 ` Toshi Kani
2013-12-06 7:23 ` Yasuaki Ishimatsu
2013-12-06 14:52 ` Toshi Kani
2013-12-05 23:21 ` David Rientjes [this message]
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