Hyperv cleanup codes comes under panic path where preemption and irq is already disabled. So calling of unregister_syscore_ops which has mutex from hyperv cleanup might schedule out the thread and never comes back. To prevent the same remove unwanted unregister_syscore_ops function call. Signed-off-by: Gaurav Kohli <gauravkohli@xxxxxxxxxxxxxxxxxxx> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index f49bc3ec76e6..c050de69dfde 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -537,7 +537,12 @@ void hyperv_cleanup(void) union hv_x64_msr_hypercall_contents hypercall_msr; union hv_reference_tsc_msr tsc_msr; - unregister_syscore_ops(&hv_syscore_ops); + /* + * Avoid unregister_syscore_ops(&hv_syscore_ops) from cleanup code, + * as this is only called in crash path where irq and preemption disabled. + * If we add this, there is a chance that this get scheduled out due to mutex + * in unregister_syscore_ops and never comes back. + */ /* Reset our OS id */ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); -- 2.17.1
