On Fri, Nov 02, 2018 at 10:31:27AM +0800, wangyufen wrote:
> 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.
> To fix this problem, this patch split out the panic_smp_self_stop()
> and add set_cpu_online(smp_processor_id(), false).
Looks fine now, please send it to the patch system (details in my
signature.) Thanks.
>
> Signed-off-by: Yufen Wang <wangyu...@huawei.com>
> ---
> arch/arm/kernel/smp.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 9000d8b..d7b86e4 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -682,6 +682,21 @@ void smp_send_stop(void)
> pr_warn("SMP: failed to stop secondary CPUs\n");
> }
>
> +/* In case panic() and panic() called at the same time on CPU1 and CPU2,
> + * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
> + * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
> + * kdump fails. So split out the panic_smp_self_stop() and add
> + * set_cpu_online(smp_processor_id(), false).
> + */
> +void panic_smp_self_stop(void)
> +{
> + pr_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();
> +}
> +
> /*
> * not supported here
> */
> --
> 2.7.4
>
>
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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