[PATCH 4/4 V16] Add check for suspended vm in softlockup detector
From: Eric B Munson <hidden>
Date: 2012-03-10 19:38:23
Also in:
kvm, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
A suspended VM can cause spurious soft lockup warnings. To avoid these, the watchdog now checks if the kernel knows it was stopped by the host and skips the warning if so. When the watchdog is reset successfully, clear the guest paused flag. Signed-off-by: Eric B Munson <redacted> Cc: mingo@redhat.com Cc: hpa@zytor.com Cc: ryanh@linux.vnet.ibm.com Cc: aliguori@us.ibm.com Cc: mtosatti@redhat.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from V3: Clear the PAUSED flag when the watchdog is reset kernel/watchdog.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index d117262..f6ffdc2 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c@@ -25,6 +25,7 @@ #include <linux/sysctl.h> #include <asm/irq_regs.h> +#include <linux/kvm_para.h> #include <linux/perf_event.h> int watchdog_enabled = 1;
@@ -280,6 +281,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) __this_cpu_write(softlockup_touch_sync, false); sched_clock_tick(); } + + /* Clear the guest paused flag on watchdog reset */ + kvm_check_and_clear_guest_paused(); __touch_watchdog(); return HRTIMER_RESTART; }
@@ -292,6 +296,14 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) */ duration = is_softlockup(touch_ts); if (unlikely(duration)) { + /* + * If a virtual machine is stopped by the host it can look to + * the watchdog like a soft lockup, check to see if the host + * stopped the vm before we issue the warning + */ + if (kvm_check_and_clear_guest_paused()) + return HRTIMER_RESTART; + /* only warn once */ if (__this_cpu_read(soft_watchdog_warn) == true) return HRTIMER_RESTART;
--
1.7.5.4