From dfe564045c653d9e6969ccca57a8a04771d333f7 Mon Sep 17 00:00:00 2001 From: chao Date: Sun, 30 Aug 2020 23:41:17 -0700 Subject: [PATCH] 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 Signed-off-by: Paul E. McKenney --- include/linux/kernel.h | 1 + kernel/rcu/tree_stall.h | 6 ++++++ kernel/sysctl.c | 11 +++++++++++ 3 files changed, 18 insertions(+) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2f05e9128201..4b5fd3da5fe8 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -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; diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index ca21d28a0f98..70d48c52fabc 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 @@ 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"); } diff --git a/kernel/sysctl.c b/kernel/sysctl.c index afad085960b8..c9fbdd848138 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -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",