The following commit has been merged into the timers/core branch of tip: Commit-ID: f96272a90d9eaea9933aaab704ddbd258feb3841 Gitweb: https://git.kernel.org/tip/f96272a90d9eaea9933aaab704ddbd258feb3841 Author: Frederic Weisbecker <frederic@xxxxxxxxxx> AuthorDate: Tue, 08 Feb 2022 17:16:35 +01:00 Committer: Frederic Weisbecker <frederic@xxxxxxxxxx> CommitterDate: Mon, 07 Mar 2022 23:53:50 +01:00 lib/irq_poll: Declare IRQ_POLL softirq vector as ksoftirqd-parking safe The following warning may appear while setting a CPU down: NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #20!!! The IRQ_POLL_SOFTIRQ vector can be raised during the hotplug cpu_down() path after ksoftirqd is parked and before the CPU actually dies. However this is handled afterward at the CPUHP_IRQ_POLL_DEAD stage where the queue gets migrated. Hence this warning can be considered spurious and the vector can join the "hotplug-safe" list. Reported-and-tested-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Paul Menzel <pmenzel@xxxxxxxxxxxxx> --- include/linux/interrupt.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 9613326..f40754c 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -580,12 +580,15 @@ enum }; /* - * Ignoring the RCU vector after ksoftirqd is parked is fine - * because: - * 1) rcutree_migrate_callbacks() takes care of the queue. + * The following vectors can be safely ignored after ksoftirqd is parked: + * + * _ RCU: + * 1) rcutree_migrate_callbacks() migrates the queue. * 2) rcu_report_dead() reports the final quiescent states. + * + * _ IRQ_POLL: irq_poll_cpu_dead() migrates the queue */ -#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ)) +#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ) | BIT(IRQ_POLL_SOFTIRQ)) /* map softirq index to softirq name. update 'softirq_to_name' in * kernel/softirq.c when adding a new softirq.
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