[PATCH 4/4] x86/platform/UV: Fix kernel panic running RHEL kdump kernel on UV

[Mike Travis]

The latest UV kernel support panics when RHEL7 kexec's the kdump kernel
to make a dumpfile.  This patch fixes the problem by turning off all UV
support if NUMA is off.

Reviewed-by: Dimitri Sivanich <sivanich@xxxxxxx>
Reviewed-by: Nathan Zimmer <nzimmer@xxxxxxx>
Tested-by: Frank Ramsay <framsay@xxxxxxx>
Tested-by: John Estabrook <estabrook@xxxxxxx>
Signed-off-by: Mike Travis <travis@xxxxxxx>
---
 arch/x86/kernel/apic/x2apic_uv_x.c |    5 +++++
 1 file changed, 5 insertions(+)

--- linux-3.12.orig/arch/x86/kernel/apic/x2apic_uv_x.c
+++ linux-3.12/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -223,6 +223,11 @@ static int __init uv_acpi_madt_oem_check
 	if (strncmp(oem_id, "SGI", 3) != 0)
 		return 0;
 
+	if (numa_off) {
+		pr_err("UV: NUMA is off, disabling UV support\n");
+		return 0;
+	}
+
 	/* Setup early hub type field in uv_hub_info for Node 0 */
 	uv_cpu_info->p_uv_hub_info = &uv_hub_info_node0;
 

--