From: Chen Jiahao chenjiahao16@huawei.com
hulk inclusion category: bugfix bugzilla: 187431, https://gitee.com/openeuler/kernel/issues/I5ZUTK
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f86d165bfe5f ("arm64: Add non nmi ipi backtrace support") introduced the IPI backtrace support on arm64 with NMI unsupported.
However a warning message comes when triggering the non-NMI IPI backtrace:
WARNING: CPU: 6 PID: 1121 at kernel/smp.c:680 smp_call_function_many_cond+0x78/0x3dc Modules linked in: soft_lockup_test(OE) [last unloaded: soft_lockup_test] CPU: 6 PID: 1121 Comm: loop_thread Tainted: G OEL 5.10.0+ #9 Hardware name: linux,dummy-virt (DT) pstate: 40000085 (nZcv daIf -PAN -UAO -TCO BTYPE=--) pc : smp_call_function_many_cond+0x78/0x3dc lr : smp_call_function_many+0x40/0x50 sp : ffffffc010033c10 x29: ffffffc010033c10 x28: 0000000000000000 x27: ffffffd5dfe2a9a8 x26: ffffffa9bfdb4430 x25: 0000000000000000 x24: 0000000000000000 x23: ffffffd5dfe29000 x22: 0000000000000000 x21: 0000000000000006 x20: ffffffd5df216418 x19: ffffffd5dfe2a9a8 x18: 0000000000000000 x17: 0000000000000000 x16: ffffffd5df293d78 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0025001680000006 x8 : 4e4d492066726f6d x7 : 53656e64696e6720 x6 : 0000000000000001 x5 : ffffffa9bfdb0750 x4 : 0000000000000000 x3 : 0000000000000000 x2 : ffffffd3e01ab000 x1 : ffffffd5dfc03000 x0 : 0000000000010000 Call trace: smp_call_function_many_cond+0x78/0x3dc smp_call_function_many+0x40/0x50 arm64_send_ipi+0x30/0x3c nmi_trigger_cpumask_backtrace+0xfc/0x154 arch_trigger_cpumask_backtrace+0x3c/0x58 watchdog_timer_fn+0x1d4/0x220 __hrtimer_run_queues+0x1bc/0x2c8 hrtimer_run_queues+0xe4/0x110 run_local_timers+0x24/0x50 update_process_times+0x5c/0x88 tick_periodic+0xd0/0xec tick_handle_periodic+0x38/0x8c arch_timer_handler_virt+0x38/0x50 handle_percpu_devid_irq+0xe0/0x1e0 generic_handle_irq+0x34/0x4c __handle_domain_irq+0xb0/0xb8 gic_handle_irq+0x98/0xb8 el1_irq+0xa8/0x140 loop_func+0x14/0x28 [soft_lockup_test] kthread+0x120/0x130 ret_from_fork+0x10/0x18
The cause is calling smp_call_function_many to send IPI to other CPUs in a softirq handling context, which is unsafe and may lead to deadlock.
Use smp_call_function_single_async() instead to avoid the warning above.
Fixes: f86d165bfe5f ("arm64: Add non nmi ipi backtrace support") Signed-off-by: Chen Jiahao chenjiahao16@huawei.com Reviewed-by: Zhang Jianhua chris.zjh@huawei.com Reviewed-by: Liao Chang liaochang1@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- arch/arm64/kernel/ipi_nmi.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c index 2cf28e511b23..9a8f7c256117 100644 --- a/arch/arm64/kernel/ipi_nmi.c +++ b/arch/arm64/kernel/ipi_nmi.c @@ -40,9 +40,25 @@ static void ipi_cpu_backtrace(void *info) printk_safe_exit(); }
+static DEFINE_PER_CPU(call_single_data_t, cpu_backtrace_csd) = + CSD_INIT(ipi_cpu_backtrace, NULL); + static void arm64_send_ipi(cpumask_t *mask) { - smp_call_function_many(mask, ipi_cpu_backtrace, NULL, false); + call_single_data_t *csd; + int this_cpu = raw_smp_processor_id(); + int cpu; + int ret; + + for_each_online_cpu(cpu) { + if (cpu == this_cpu) + continue; + + csd = &per_cpu(cpu_backtrace_csd, cpu); + ret = smp_call_function_single_async(cpu, csd); + if (ret) + pr_info("Sending IPI failed to CPU %d\n", cpu); + } }
bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)