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| author |   Paul E. McKenney <paulmck@kernel.org> | 2020-11-12 12:19:47 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-01-04 13:59:47 -0800 |
| commit | 725969ac11d7fa50aa701321daa600ce421fc21b (patch) | |
| tree | aa8891bc0679692fddeb7da6d34cc6163e19e059 /kernel/rcu/tree_stall.h | |
| parent | rcu: For RCU grace-period kthread starvation, dump last CPU it ran on (diff) | |
| download | linux-dev-725969ac11d7fa50aa701321daa600ce421fc21b.tar.xz linux-dev-725969ac11d7fa50aa701321daa600ce421fc21b.zip | |
rcu: Do not NMI offline CPUs
Currently, RCU CPU stall warning messages will NMI whatever CPU looks
like it is blocking either the current grace period or the grace-period
kthread. This can produce confusing output if the target CPU is offline.
This commit therefore checks for offline CPUs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree_stall.h')
| -rw-r--r-- | kernel/rcu/tree_stall.h | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 35c1355d44e7..29cf096b5d20 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -333,9 +333,12 @@ static void rcu_dump_cpu_stacks(void) rcu_for_each_leaf_node(rnp) { raw_spin_lock_irqsave_rcu_node(rnp, flags); for_each_leaf_node_possible_cpu(rnp, cpu) - if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) - if (!trigger_single_cpu_backtrace(cpu)) + if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) { + if (cpu_is_offline(cpu)) + pr_err("Offline CPU %d blocking current GP.\n", cpu); + else if (!trigger_single_cpu_backtrace(cpu)) dump_cpu_task(cpu); + } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } } @@ -466,9 +469,13 @@ static void rcu_check_gp_kthread_starvation(void) pr_err("RCU grace-period kthread stack dump:\n"); sched_show_task(gpk); if (cpu >= 0) { - pr_err("Stack dump where RCU grace-period kthread last ran:\n"); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); + if (cpu_is_offline(cpu)) { + pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu); + } else { + pr_err("Stack dump where RCU GP kthread last ran:\n"); + if (!trigger_single_cpu_backtrace(cpu)) + dump_cpu_task(cpu); + } } wake_up_process(gpk); } |