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.
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index ec31534..fd7f8a6 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -26,6 +26,7 @@ #include <linux/poison.h>
#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>
@@ -72,6 +73,11 @@ 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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