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Date: Fri, 2 Nov 2018 10:31:27 +0800 From: wangyufen <wangyufen@...wei.com> To: Russell King - ARM Linux <linux@...linux.org.uk> CC: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, <akpm@...ux-foundation.org>, <kstewart@...uxfoundation.org>, <rppt@...ux.vnet.ibm.com>, <gregkh@...uxfoundation.org>, <tglx@...utronix.de>, <pombredanne@...b.com>, <weiyongjun1@...wei.com>, <huawei.libin@...wei.com>, Wangyufen <wangyufen@...wei.com> Subject: [PATCH v2] ARM:kexec:offline panic_smp_self_stop CPU 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@...wei.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
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