From 58fc949e945ae63e4fe3c9d88bfe0307348030d7 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Wed, 11 Jan 2006 22:43:42 +0100
Subject: [PATCH] --- yaml --- r: 17952 b: refs/heads/master c:
 1584b89c921acefe88881f08d836d80f00600a84 h: refs/heads/master v: v3

---
 [refs]                      |  2 +-
 trunk/arch/x86_64/mm/srat.c | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 5aa835ce976c..5db7f6738470 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7a4a76cc1057de0dc96ee481590347aa8c5b9ffb
+refs/heads/master: 1584b89c921acefe88881f08d836d80f00600a84
diff --git a/trunk/arch/x86_64/mm/srat.c b/trunk/arch/x86_64/mm/srat.c
index 33340bd1e328..9f69d28652f8 100644
--- a/trunk/arch/x86_64/mm/srat.c
+++ b/trunk/arch/x86_64/mm/srat.c
@@ -91,9 +91,36 @@ static __init inline int srat_disabled(void)
 	return numa_off || acpi_numa < 0;
 }
 
+/*
+ * A lot of BIOS fill in 10 (= no distance) everywhere. This messes
+ * up the NUMA heuristics which wants the local node to have a smaller
+ * distance than the others.
+ * Do some quick checks here and only use the SLIT if it passes.
+ */
+static __init int slit_valid(struct acpi_table_slit *slit)
+{
+	int i, j;
+	int d = slit->localities;
+	for (i = 0; i < d; i++) {
+		for (j = 0; j < d; j++)  {
+			u8 val = slit->entry[d*i + j];
+			if (i == j) {
+				if (val != 10)
+					return 0;
+			} else if (val <= 10)
+				return 0;
+		}
+	}
+	return 1;
+}
+
 /* Callback for SLIT parsing */
 void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
 {
+	if (!slit_valid(slit)) {
+		printk(KERN_INFO "ACPI: SLIT table looks invalid. Not used.\n");
+		return;
+	}
 	acpi_slit = slit;
 }