4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 82c08c3e7f171aa7f579b231d0abbc1d62e91974 ]
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 Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 12a6172263c0..3bf82232b1be 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -724,6 +724,21 @@ 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 */