From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Wang Yufen <wangyufen@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
kstewart@linuxfoundation.org, rppt@linux.vnet.ibm.com,
gregkh@linuxfoundation.org, tglx@linutronix.de,
pombredanne@nexb.com, weiyongjun1@huawei.com,
huawei.libin@huawei.com
Subject: Re: [PATCH] ARM:kexec:offline panic_smp_self_stop CPU
Date: Thu, 1 Nov 2018 11:34:30 +0000 [thread overview]
Message-ID: <20181101113430.GO30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <1541071249-15660-1-git-send-email-wangyufen@huawei.com>
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.
>
> 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
>
>
--
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
next prev parent reply other threads:[~2018-11-01 11:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 11:20 [PATCH] ARM:kexec:offline panic_smp_self_stop CPU Wang Yufen
2018-11-01 11:34 ` Russell King - ARM Linux [this message]
2018-11-02 1:17 ` wangyufen
2018-11-02 2:31 ` [PATCH v2] " wangyufen
2018-11-02 9:55 ` Russell King - ARM Linux
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