Messages in this thread | | | Subject | Re: [PATCH] ARM:kexec:offline panic_smp_self_stop CPU | From | wangyufen <> | Date | Fri, 2 Nov 2018 09:17:00 +0800 |
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On 2018/11/1 19:34, Russell King - ARM Linux wrote: > On Thu, Nov 01, 2018 at 07:20:49PM +0800, Wang Yufen wrote: >> From: Yufen Wang <wangyufen@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.
Thanks.
I will send v2.
>> Signed-off-by: Yufen Wang <wangyufen@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 >> >>
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