rcu: Panic after fixed number of stalls
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>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 500def6..fc2dd3f 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -536,6 +536,7 @@
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;
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 0fde39b8..228c55f 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -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 @@
/* 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");
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 287862f..1bca490 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2651,6 +2651,17 @@
.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",
