diff options
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 50 |
1 files changed, 27 insertions, 23 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 121f833acd04..6ec3abbe90e2 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -500,16 +500,29 @@ void rcu_force_quiescent_state(void) EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); /* + * Convert a ->gp_state value to a character string. + */ +static const char *gp_state_getname(short gs) +{ + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names)) + return "???"; + return gp_state_names[gs]; +} + +/* * Show the state of the grace-period kthreads. */ void show_rcu_gp_kthreads(void) { int cpu; + unsigned long j; struct rcu_data *rdp; struct rcu_node *rnp; - pr_info("%s: wait state: %d ->state: %#lx\n", rcu_state.name, - rcu_state.gp_state, rcu_state.gp_kthread->state); + j = jiffies - READ_ONCE(rcu_state.gp_activity); + pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %ld\n", + rcu_state.name, gp_state_getname(rcu_state.gp_state), + rcu_state.gp_state, rcu_state.gp_kthread->state, j); rcu_for_each_node_breadth_first(rnp) { if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) continue; @@ -891,12 +904,12 @@ void rcu_irq_enter_irqson(void) } /** - * rcu_is_watching - see if RCU thinks that the current CPU is idle + * rcu_is_watching - see if RCU thinks that the current CPU is not idle * * Return true if RCU is watching the running CPU, which means that this * CPU can safely enter RCU read-side critical sections. In other words, - * if the current CPU is in its idle loop and is neither in an interrupt - * or NMI handler, return true. + * if the current CPU is not in its idle loop or is in an interrupt or + * NMI handler, return true. */ bool notrace rcu_is_watching(void) { @@ -1143,16 +1156,6 @@ static void record_gp_stall_check_time(void) } /* - * Convert a ->gp_state value to a character string. - */ -static const char *gp_state_getname(short gs) -{ - if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names)) - return "???"; - return gp_state_names[gs]; -} - -/* * Complain about starvation of grace-period kthread. */ static void rcu_check_gp_kthread_starvation(void) @@ -2032,9 +2035,9 @@ static void rcu_gp_cleanup(void) rnp = rcu_get_root(); raw_spin_lock_irq_rcu_node(rnp); /* GP before ->gp_seq update. */ - /* Declare grace period done. */ - rcu_seq_end(&rcu_state.gp_seq); + /* Declare grace period done, trace first to use old GP number. */ trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end")); + rcu_seq_end(&rcu_state.gp_seq); rcu_state.gp_state = RCU_GP_IDLE; /* Check for GP requests since above loop. */ rdp = this_cpu_ptr(&rcu_data); @@ -2600,10 +2603,10 @@ static void force_quiescent_state(void) * This function checks for grace-period requests that fail to motivate * RCU to come out of its idle mode. */ -static void -rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp) +void +rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp, + const unsigned long gpssdelay) { - const unsigned long gpssdelay = rcu_jiffies_till_stall_check() * HZ; unsigned long flags; unsigned long j; struct rcu_node *rnp_root = rcu_get_root(); @@ -2690,7 +2693,7 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused local_irq_restore(flags); } - rcu_check_gp_start_stall(rnp, rdp); + rcu_check_gp_start_stall(rnp, rdp, rcu_jiffies_till_stall_check()); /* If there are callbacks ready, invoke them. */ if (rcu_segcblist_ready_cbs(&rdp->cblist)) @@ -2826,7 +2829,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, int cpu, bool lazy) * Very early boot, before rcu_init(). Initialize if needed * and then drop through to queue the callback. */ - BUG_ON(cpu != -1); + WARN_ON_ONCE(cpu != -1); WARN_ON_ONCE(!rcu_is_watching()); if (rcu_segcblist_empty(&rdp->cblist)) rcu_segcblist_init(&rdp->cblist); @@ -3485,7 +3488,8 @@ static int __init rcu_spawn_gp_kthread(void) rcu_scheduler_fully_active = 1; t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name); - BUG_ON(IS_ERR(t)); + if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM is now expected behavior\n", __func__)) + return 0; rnp = rcu_get_root(); raw_spin_lock_irqsave_rcu_node(rnp, flags); rcu_state.gp_kthread = t; |