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rcu: Panic after fixed number of stalls

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Some stalls are transient, so that system fully recovers.  This commit
therefore allows users to configure the number of stalls that must happen
in order to trigger kernel panic.

Signed-off-by: chao <chao@eero.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
chao 2020-08-30 23:41:17 -07:00 committed by Paul E. McKenney
parent 29368e0939
commit dfe564045c
3 changed files with 18 additions and 0 deletions
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1
include/linux/kernel.h
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@ -536,6 +536,7 @@ extern int panic_on_warn;
extern unsigned long panic_on_taint;
extern bool panic_on_taint_nousertaint;
extern int sysctl_panic_on_rcu_stall;
extern int sysctl_max_rcu_stall_to_panic;
extern int sysctl_panic_on_stackoverflow;
extern bool crash_kexec_post_notifiers;

6
kernel/rcu/tree_stall.h
View File

@ -13,6 +13,7 @@
/* panic() on RCU Stall sysctl. */
int sysctl_panic_on_rcu_stall __read_mostly;
int sysctl_max_rcu_stall_to_panic __read_mostly;
#ifdef CONFIG_PROVE_RCU
#define RCU_STALL_DELAY_DELTA (5 * HZ)
@ -106,6 +107,11 @@ early_initcall(check_cpu_stall_init);
/* If so specified via sysctl, panic, yielding cleaner stall-warning output. */
static void panic_on_rcu_stall(void)
{
static int cpu_stall;
if (++cpu_stall < sysctl_max_rcu_stall_to_panic)
return;
if (sysctl_panic_on_rcu_stall)
panic("RCU Stall\n");
}

11
kernel/sysctl.c
View File

@ -2650,6 +2650,17 @@ static struct ctl_table kern_table[] = {
.extra2 = SYSCTL_ONE,
},
#endif
#if defined(CONFIG_TREE_RCU)
{
.procname = "max_rcu_stall_to_panic",
.data = &sysctl_max_rcu_stall_to_panic,
.maxlen = sizeof(sysctl_max_rcu_stall_to_panic),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_INT_MAX,
},
#endif
#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
{
.procname = "stack_erasing",