From: Gaurav Kohli <gauravkohli@xxxxxxxxxxxxxxxxxxx> Sent: Friday, November 25, 2022 10:15 PM > > Hyper-V cleanup code comes under panic path where preemption and irq > is already disabled. So calling of unregister_syscore_ops might schedule > out the thread even for the case where mutex lock is free. > hyperv_cleanup > unregister_syscore_ops > mutex_lock(&syscore_ops_lock) > might_sleep > Here might_sleep might schedule out this thread, where voluntary preemption > config is on and this thread will never comes back. And also this was added > earlier to maintain the symmetry which is not required as this can comes > during crash shutdown path only. > > To prevent the same, removing unregister_syscore_ops function call. > > Signed-off-by: Gaurav Kohli <gauravkohli@xxxxxxxxxxxxxxxxxxx> > --- > v2: Update commit message > --- > arch/x86/hyperv/hv_init.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index f49bc3ec76e6..5ec7badab600 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -537,8 +537,6 @@ 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); > - > /* Reset our OS id */ > wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); > hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0); > -- > 2.17.1 Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
