Mark emergency sections wherever multiple lines of rcu stall information are generated. In an emergency section the CPU will not perform console output for the printk() calls. Instead, a flushing of the console output is triggered when exiting the emergency section. This allows the full message block to be stored as quickly as possible in the ringbuffer.
Signed-off-by: John Ogness <[email protected]> --- kernel/rcu/tree_exp.h | 9 +++++++++ kernel/rcu/tree_stall.h | 11 +++++++++++ 2 files changed, 20 insertions(+) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 6b83537480b1..bc1d8733c08f 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -7,6 +7,7 @@ * Authors: Paul E. McKenney <[email protected]> */ +#include <linux/console.h> #include <linux/lockdep.h> static void rcu_exp_handler(void *unused); @@ -571,6 +572,9 @@ static void synchronize_rcu_expedited_wait(void) return; if (rcu_stall_is_suppressed()) continue; + + nbcon_cpu_emergency_enter(); + j = jiffies; rcu_stall_notifier_call_chain(RCU_STALL_NOTIFY_EXP, (void *)(j - jiffies_start)); trace_rcu_stall_warning(rcu_state.name, TPS("ExpeditedStall")); @@ -612,6 +616,7 @@ static void synchronize_rcu_expedited_wait(void) } pr_cont("\n"); } + nbcon_cpu_emergency_flush(); rcu_for_each_leaf_node(rnp) { for_each_leaf_node_possible_cpu(rnp, cpu) { mask = leaf_node_cpu_bit(rnp, cpu); @@ -624,6 +629,9 @@ static void synchronize_rcu_expedited_wait(void) rcu_exp_print_detail_task_stall_rnp(rnp); } jiffies_stall = 3 * rcu_exp_jiffies_till_stall_check() + 3; + + nbcon_cpu_emergency_exit(); + panic_on_rcu_stall(); } } @@ -792,6 +800,7 @@ static void rcu_exp_print_detail_task_stall_rnp(struct rcu_node *rnp) */ touch_nmi_watchdog(); sched_show_task(t); + nbcon_cpu_emergency_flush(); } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 5d666428546b..1ca0826545c1 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -7,6 +7,7 @@ * Author: Paul E. McKenney <[email protected]> */ +#include <linux/console.h> #include <linux/kvm_para.h> #include <linux/rcu_notifier.h> @@ -260,6 +261,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) */ touch_nmi_watchdog(); sched_show_task(t); + nbcon_cpu_emergency_flush(); } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } @@ -522,6 +524,7 @@ static void print_cpu_stall_info(int cpu) falsepositive ? " (false positive?)" : ""); print_cpu_stat_info(cpu); + nbcon_cpu_emergency_flush(); } /* Complain about starvation of grace-period kthread. */ @@ -604,6 +607,8 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) if (rcu_stall_is_suppressed()) return; + nbcon_cpu_emergency_enter(); + /* * OK, time to rat on our buddy... * See Documentation/RCU/stallwarn.rst for info on how to debug @@ -655,6 +660,8 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) rcu_check_gp_kthread_expired_fqs_timer(); rcu_check_gp_kthread_starvation(); + nbcon_cpu_emergency_exit(); + panic_on_rcu_stall(); rcu_force_quiescent_state(); /* Kick them all. */ @@ -675,6 +682,8 @@ static void print_cpu_stall(unsigned long gps) if (rcu_stall_is_suppressed()) return; + nbcon_cpu_emergency_enter(); + /* * OK, time to rat on ourselves... * See Documentation/RCU/stallwarn.rst for info on how to debug @@ -703,6 +712,8 @@ static void print_cpu_stall(unsigned long gps) jiffies + 3 * rcu_jiffies_till_stall_check() + 3); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + nbcon_cpu_emergency_exit(); + panic_on_rcu_stall(); /* -- 2.39.2
