3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Avi Kivity <avi@xxxxxxxxxx> (cherry picked from commit 95ef1e52922cf75b1ea2eae54ef886f2cc47eecb) Prevent tracing of preempt_disable() in get_cpu_var() in kvm_clock_read(). When CONFIG_DEBUG_PREEMPT is enabled, preempt_disable/enable() are traced and this causes the function_graph tracer to go into an infinite recursion. By open coding the preempt_disable() around the get_cpu_var(), we can use the notrace version which prevents preempt_disable/enable() from being traced and prevents the recursion. Based on a similar patch for Xen from Jeremy Fitzhardinge. Tested-by: Gleb Natapov <gleb@xxxxxxxxxx> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Avi Kivity <avi@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx> --- arch/x86/kernel/kvmclock.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -74,9 +74,10 @@ static cycle_t kvm_clock_read(void) struct pvclock_vcpu_time_info *src; cycle_t ret; - src = &get_cpu_var(hv_clock); + preempt_disable_notrace(); + src = &__get_cpu_var(hv_clock); ret = pvclock_clocksource_read(src); - put_cpu_var(hv_clock); + preempt_enable_notrace(); return ret; } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
