[v2] ARM:kexec:offline panic_smp_self_stop CPU
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Message ID 5BDBB6FF.6080907@huawei.com
State New
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Series
  • [v2] ARM:kexec:offline panic_smp_self_stop CPU
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Commit Message

wangyufen Nov. 2, 2018, 2:31 a.m. UTC
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).

Signed-off-by: Yufen Wang <wangyufen@huawei.com>
---
 arch/arm/kernel/smp.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

Comments

Russell King - ARM Linux admin Nov. 2, 2018, 9:55 a.m. UTC | #1
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 <wangyufen@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
> 
>

Patch
diff mbox series

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
  */