From ae32b1297a77c23fd0badd642bb685062f7a37f8 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek <konrad@darnok.org>
Date: Wed, 2 May 2007 19:27:11 +0200
Subject: [PATCH] [PATCH] x86-64: Inhibit machine from asserting an NMI when
doing Alt-SysRq-M operation.
This patch touches the NMI watchdog every MAX_ORDER_NR_PAGES
to inhibit the machine from triggering an NMI while the CPUs
are locked. This situation is happening on boxes with more
than 64CPUs and 128GB of RAM when Alt-SysRq-m is performed.
It has been succesfully tested for regression on uni, 2, 4, 8
32, and 64 CPU boxes with various memory configuration.
Signed-off-by: Andi Kleen <ak@suse.de>
---
arch/x86_64/mm/init.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index e3134bc9a4fc9..282b0a8f00adb 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -27,6 +27,7 @@
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <linux/memory_hotplug.h>
+#include <linux/nmi.h>
#include <asm/processor.h>
#include <asm/system.h>
@@ -73,6 +74,11 @@ void show_mem(void)
for_each_online_pgdat(pgdat) {
for (i = 0; i < pgdat->node_spanned_pages; ++i) {
+ /* this loop can take a while with 256 GB and 4k pages
+ so update the NMI watchdog */
+ if (unlikely(i % MAX_ORDER_NR_PAGES == 0)) {
+ touch_nmi_watchdog();
+ }
page = pfn_to_page(pgdat->node_start_pfn + i);
total++;
if (PageReserved(page))
--
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