The patch titled
Subject: kvm: ensure hard lockup detection is disabled by default
has been added to the -mm tree. Its filename is
kvm-ensure-hard-lockup-detection-is-disabled-by-default.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kvm-ensure-hard-lockup-detection-is-disabled-by-default.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kvm-ensure-hard-lockup-detection-is-disabled-by-default.patch
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------------------------------------------------------
From: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Subject: kvm: ensure hard lockup detection is disabled by default
Use watchdog_enable_hardlockup_detector() to set hard lockup detection's
default value to false. It's risky to run this detection in a guest, as
false positives are easy to trigger, especially if the host is
overcommitted.
Signed-off-by: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/kvm.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN arch/x86/kernel/kvm.c~kvm-ensure-hard-lockup-detection-is-disabled-by-default arch/x86/kernel/kvm.c
--- a/arch/x86/kernel/kvm.c~kvm-ensure-hard-lockup-detection-is-disabled-by-default
+++ a/arch/x86/kernel/kvm.c
@@ -35,6 +35,7 @@
#include <linux/slab.h>
#include <linux/kprobes.h>
#include <linux/debugfs.h>
+#include <linux/nmi.h>
#include <asm/timer.h>
#include <asm/cpu.h>
#include <asm/traps.h>
@@ -499,6 +500,13 @@ void __init kvm_guest_init(void)
#else
kvm_guest_cpu_init();
#endif
+
+ /*
+ * Hard lockup detection is enabled by default. Disable it, as guests
+ * can get false positives too easily, for example if the host is
+ * overcommitted.
+ */
+ watchdog_enable_hardlockup_detector(false);
}
static noinline uint32_t __kvm_cpuid_base(void)
_
Patches currently in -mm which might be from uobergfe@xxxxxxxxxx are
watchdog-fix-print-once-on-enable.patch
watchdog-control-hard-lockup-detection-default.patch
kvm-ensure-hard-lockup-detection-is-disabled-by-default.patch
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