On Fri, Mar 13, 2026 at 09:56:49AM -0700, Gustavo Luiz Duarte wrote: > Add a Kconfig option to set the default value of the > kernel.panic_on_rcu_stall sysctl, allowing the kernel to be built > with panic-on-RCU-stall enabled by default. > > This is useful for high-availability systems that require automatic > recovery (via panic_timeout) when a CPU stall is detected, without > needing userspace to configure the sysctl at boot. > > This follows the pattern established by BOOTPARAM_SOFTLOCKUP_PANIC > and BOOTPARAM_HUNG_TASK_PANIC. The runtime sysctl can still override > the Kconfig default. > > Signed-off-by: Gustavo Luiz Duarte <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]> > --- > kernel/rcu/Kconfig.debug | 24 ++++++++++++++++++++++++ > kernel/rcu/tree_stall.h | 2 +- > 2 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug > index 625d75392647..fc2c775eeefc 100644 > --- a/kernel/rcu/Kconfig.debug > +++ b/kernel/rcu/Kconfig.debug > @@ -175,6 +175,30 @@ config RCU_CPU_STALL_NOTIFIER > Say Y here if you want RCU CPU stall notifiers (you don't want them) > Say N if you are unsure. > > +config BOOTPARAM_RCU_STALL_PANIC > + bool "Panic (reboot) on RCU CPU stall" > + depends on RCU_STALL_COMMON > + default n > + help > + Say Y here to enable the kernel to panic when an RCU CPU stall > + is detected. > + > + The panic can be used in combination with panic_timeout, > + to cause the system to reboot automatically after an > + RCU CPU stall has been detected. This feature is useful for > + high-availability systems that have uptime guarantees and > + where a CPU stall must be resolved ASAP. > + > + The kernel.max_rcu_stall_to_panic sysctl can be used to set > + a minimum number of stalls before panicking, allowing the > + system to tolerate a given number of RCU CPU stalls before > + triggering a panic. > + > + This setting can be overridden at runtime via the > + kernel.panic_on_rcu_stall sysctl parameter. > + > + Say N if unsure. > + > config RCU_TRACE > bool "Enable tracing for RCU" > depends on DEBUG_KERNEL > diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h > index b67532cb8770..43ddabf46b5e 100644 > --- a/kernel/rcu/tree_stall.h > +++ b/kernel/rcu/tree_stall.h > @@ -17,7 +17,7 @@ > // Controlling CPU stall warnings, including delay calculation. > > /* panic() on RCU Stall sysctl. */ > -static int sysctl_panic_on_rcu_stall __read_mostly; > +static int sysctl_panic_on_rcu_stall __read_mostly = > IS_ENABLED(CONFIG_BOOTPARAM_RCU_STALL_PANIC); > static int sysctl_max_rcu_stall_to_panic __read_mostly; > > static const struct ctl_table rcu_stall_sysctl_table[] = { > > --- > base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681 > change-id: 20260313-panic_on_rcustall-95709d1abf2f > > Best regards, > -- > Gustavo Luiz Duarte <[email protected]> >
