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-rw-r--r--arch/x86_64/mm/srat.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/x86_64/mm/srat.c b/arch/x86_64/mm/srat.c
index 33340bd1e328..9f69d28652f8 100644
--- a/arch/x86_64/mm/srat.c
+++ b/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;
}