Bugzilla: 971139

Upstream-status: Fedora mustard for now

Disable watchdog on virtual machines.

For various reasons, VMs seem to trigger the soft lockup detector a lot,

in cases where it's just not possible for a lockup to occur.

(Example: https://bugzilla.redhat.com/show_bug.cgi?id=971139)

In some cases it seems that the host just never scheduled the app running

the VM for a very long time (Could be the host was under heavy load).

Just disable the detector on VMs.

Signed-off-by: Dave Jones <davej@redhat.com>

diff --git a/kernel/watchdog.c b/kernel/watchdog.c

index 1241d8c..b2dc4e4 100644

--- a/kernel/watchdog.c

+++ b/kernel/watchdog.c

@@ -24,6 +24,7 @@

 #include <linux/sysctl.h>

 #include <linux/smpboot.h>

 #include <linux/sched/rt.h>

+#include <linux/dmi.h>

 #include <asm/irq_regs.h>

 #include <linux/kvm_para.h>

@@ -96,6 +97,32 @@ static int __init nosoftlockup_setup(char *str)

 __setup("nosoftlockup", nosoftlockup_setup);

 /*  */

+static int disable_watchdog(const struct dmi_system_id *d)

+{

+	printk(KERN_INFO "watchdog: disabled (inside virtual machine)\n");

+	watchdog_user_enabled = 0;

+	return 0;

+}

+

+static const struct dmi_system_id watchdog_virt_dmi_table[] = {

+	{

+		.callback = disable_watchdog,

+		.ident = "VMware",

+		.matches = {

+			DMI_MATCH(DMI_SYS_VENDOR, "VMware, Inc."),

+		},

+	},

+	{

+		.callback = disable_watchdog,

+		.ident = "Bochs",

+		.matches = {

+			DMI_MATCH(DMI_SYS_VENDOR, "Bochs"),

+		},

+	},

+	{}

+};

+

+

 /*

  * Hard-lockup warnings should be triggered after just a few seconds. Soft-

  * lockups can have false positives under extreme conditions. So we generally

@@ -551,6 +578,8 @@ int proc_dowatchdog(struct ctl_table *table, int write,

 void __init lockup_detector_init(void)

 {

+	dmi_check_system(watchdog_virt_dmi_table);

+

 	set_sample_period();

 #ifdef CONFIG_NO_HZ_FULL