On Thu, Nov 01, 2018 at 07:20:49PM +0800, Wang Yufen wrote: > From: Yufen Wang <wangyu...@huawei.com> > > In case panic() and panic() called at the same time on different CPUS. > For example: > CPU 0: > panic() > __crash_kexec > machine_crash_shutdown > crash_smp_send_stop > machine_kexec > BUG_ON(num_online_cpus() > 1); > > CPU 1: > panic() > local_irq_disable > panic_smp_self_stop > > If CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop(), kdump > fails. CPU1 can't receive the ipi irq, CPU1 will be always online. > I changed BUG_ON to WARN in kexec crash as arm64 does, kdump also fails. > Because num_online_cpus() > 1, can't disable the L2 in _soft_restart. > To fix this problem, this patch split out the panic_smp_self_stop() > and add set_cpu_online(smp_processor_id(), false).
Thanks. I think this may as well go into arch/arm/kernel/smp.c - it won't be required for single-CPU systems, since there aren't "other" CPUs. It's probably also worth a comment above the function as to why we have this. > > Signed-off-by: Yufen Wang <wangyu...@huawei.com> > --- > arch/arm/kernel/setup.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index 31940bd..151861f 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -602,6 +602,16 @@ static void __init smp_build_mpidr_hash(void) > } > #endif > > +void panic_smp_self_stop(void) > +{ > + printk(KERN_DEBUG "CPU %u will stop doing anything useful since another > CPU has paniced\n", > + smp_processor_id()); > + set_cpu_online(smp_processor_id(), false); > + while (1) > + cpu_relax(); > + > +} > + > static void __init setup_processor(void) > { > struct proc_info_list *list; > -- > 2.7.4 > > -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up