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rcu: Mark emergency sections in rcu stalls

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BugLink: https://bugs.launchpad.net/bugs/2060704

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 <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kevin Becker <kevin.becker@canonical.com>
This commit is contained in:
John Ogness
2023-09-11 15:53:39 +00:00
committed by Kevin Becker
parent d2c8329a4c
commit 52f6a084c0
2 changed files with 16 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/rcu/tree_exp.h
+7
View File
@@ -7,6 +7,7 @@
* Authors: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/console.h>
#include <linux/lockdep.h>
static void rcu_exp_handler(void *unused);
@@ -636,6 +637,9 @@ 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"));
@@ -689,6 +693,9 @@ 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();
}
}
kernel/rcu/tree_stall.h
+9
View File
@@ -7,6 +7,7 @@
* Author: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/console.h>
#include <linux/kvm_para.h>
#include <linux/rcu_notifier.h>
@@ -605,6 +606,8 @@ 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
@@ -656,6 +659,8 @@ 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. */
@@ -676,6 +681,8 @@ 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
@@ -704,6 +711,8 @@ 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();
/*