Commit ae32b129 authored by Konrad Rzeszutek's avatar Konrad Rzeszutek Committed by Andi Kleen

[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: default avatarAndi Kleen <ak@suse.de>
parent c8118c6c
...@@ -27,6 +27,7 @@ ...@@ -27,6 +27,7 @@
#include <linux/dma-mapping.h> #include <linux/dma-mapping.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/memory_hotplug.h> #include <linux/memory_hotplug.h>
#include <linux/nmi.h>
#include <asm/processor.h> #include <asm/processor.h>
#include <asm/system.h> #include <asm/system.h>
...@@ -73,6 +74,11 @@ void show_mem(void) ...@@ -73,6 +74,11 @@ void show_mem(void)
for_each_online_pgdat(pgdat) { for_each_online_pgdat(pgdat) {
for (i = 0; i < pgdat->node_spanned_pages; ++i) { 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); page = pfn_to_page(pgdat->node_start_pfn + i);
total++; total++;
if (PageReserved(page)) if (PageReserved(page))
......
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