From a59a940ff89fcaf305362443335f99010ff3b9cf Mon Sep 17 00:00:00 2001 From: Wang Shuaiwei Date: Fri, 4 Sep 2026 14:45:06 +0800 Subject: [PATCH] tick/nohz: Add BLOCK_SOFTIRQ to the hotplug safe mask During CPU-hotplug stress testing combined with an I/O workload, the following message is observed: "NOHZ tick-stop error: local softirq work is pending, handler #10!!!" On CPU offline, ksoftirqd is parked at CPUHP_AP_SMPBOOT_THREADS while the CPU still takes interrupts. A block completion raised after that point stays pending, and if the dying CPU goes idle before teardown, report_idle_softirq() sees it, keeps the tick alive and prints the error above. Such pending block completions on the outgoing CPU are drained later by blk_softirq_cpu_dead() (CPUHP_BLOCK_SOFTIRQ_DEAD), so a pending BLOCK_SOFTIRQ is harmless here. Add it to SOFTIRQ_HOTPLUG_SAFE_MASK like the other teardown-covered vectors. Signed-off-by: Wang Shuaiwei Signed-off-by: Thomas Gleixner Reviewed-by: Sebastian Andrzej Siewior Reviewed-by: Frederic Weisbecker Link: https://patch.msgid.link/20260904064506.671203-1-wangshuaiwei1@xiaomi.com --- include/linux/interrupt.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 3bf969ad8fe0..52bb684090c0 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -573,9 +573,11 @@ enum * _ IRQ_POLL: irq_poll_cpu_dead() migrates the queue * * _ (HR)TIMER_SOFTIRQ: (hr)timers_dead_cpu() migrates the queue + * + * _ BLOCK_SOFTIRQ: blk_softirq_cpu_dead() completes the remaining requests */ -#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(TIMER_SOFTIRQ) | BIT(IRQ_POLL_SOFTIRQ) |\ - BIT(HRTIMER_SOFTIRQ) | BIT(RCU_SOFTIRQ)) +#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(TIMER_SOFTIRQ) | BIT(BLOCK_SOFTIRQ) |\ + BIT(IRQ_POLL_SOFTIRQ) | BIT(HRTIMER_SOFTIRQ) | BIT(RCU_SOFTIRQ)) /* map softirq index to softirq name. update 'softirq_to_name' in