linux-kernel - [PATCH] x86/numa: Allow node distance table to have I/O nodes

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Date:	Tue, 15 Oct 2013 15:07:44 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	mingo@...nel.org, hpa@...or.com, tglx@...utronix.de
Cc:	akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-pci@...r.kernel.org, yinghai@...nel.org, tj@...nel.org,
	rientjes@...gle.com, isimatu.yasuaki@...fujitsu.com,
	Toshi Kani <toshi.kani@...com>
Subject: [PATCH] x86/numa: Allow node distance table to have I/O nodes

When a system has I/O devices (ex. PCI bridges) with their own
locality, the following error message shows up.

 NUMA: Warning: node ids are out of bound, from=-1 to=-1 distance=10

acpi_numa_slit_init() calls numa_set_distance(), which assumes
that all nodes on the system have been parsed with SRAT already.
However, SRAT does not list I/O devices.  SLIT has the distance
table for all localities including I/Os.  Hence, the above message
shows up when a system has a unique I/O device locality.

This patch changes acpi_numa_slit_init() to make sure all the
nodes are parsed, so that it can initialize the distance table
with all the localities.

The following map tables may contain I/O nodes as a result.
 - numa_distance[], i.e. node distance table
 - node_states[N_POSSIBLE], aka. node_possible_map
 - mp_bus_to_node[], i.e. pci bus# to node# map

There is no functional change since there is no code that makes
use of the I/O nodes.
 - I/O nodes are set to off-line.
 - pci_acpi_scan_root() continues to set -1 to pci_sysdata.node
   of a PCI bridge with a unique locality (per commit b755de8d).

Signed-off-by: Toshi Kani <toshi.kani@...com>
---
 arch/x86/mm/srat.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
index 26f4e12..fb5bd73 100644
--- a/arch/x86/mm/srat.c
+++ b/arch/x86/mm/srat.c
@@ -45,7 +45,20 @@ static __init inline int srat_disabled(void)
 /* Callback for SLIT parsing */
 void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
 {
-	int i, j;
+	int node, i, j;
+
+	/* SLIT may have I/O nodes, which are not listed in SRAT */
+	for (i = 0; i < slit->locality_count; i++) {
+		if (pxm_to_node(i) != NUMA_NO_NODE)
+			continue;
+
+		node = setup_node(i);
+		if (WARN_ONCE(node < 0, "SLIT: Too many proximity domains.\n"))
+			continue;
+
+		node_set(node, numa_nodes_parsed);
+		pr_info("SLIT: Node %u PXM %u I/O only\n", node, i);
+	}
 
 	for (i = 0; i < slit->locality_count; i++)
 		for (j = 0; j < slit->locality_count; j++)
--
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