Disable soft lockup detector on virtual machines. (rhbz 971139)

1 files changed, 67 insertions, 0 deletions

diff --git a/nowatchdog-on-virt.patch b/nowatchdog-on-virt.patch
new file mode 100644
index 00000000..b2064220
--- /dev/null
+++ b/nowatchdog-on-virt.patch
@@ -0,0 +1,67 @@
+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 05039e3..a28aab9 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_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 Bochs"),
++		},
++	},
++	{}
++};
++
++
+ /*
+  * Hard-lockup warnings should be triggered after just a few seconds. Soft-
+  * lockups can have false positives under extreme conditions. So we generally
+@@ -543,6 +570,8 @@ static struct smp_hotplug_thread watchdog_threads = {
+ 
+ void __init lockup_detector_init(void)
+ {
++	dmi_check_system(watchdog_virt_dmi_table);
++
+ 	set_sample_period();
+ 	if (smpboot_register_percpu_thread(&watchdog_threads)) {
+ 		pr_err("Failed to create watchdog threads, disabled\n");