diff options
Diffstat (limited to 'kernel/rcu/tree_stall.h')
| -rw-r--r-- | kernel/rcu/tree_stall.h | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 0fde39b8daab..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"); } @@ -249,13 +255,16 @@ static bool check_slow_task(struct task_struct *t, void *arg) /* * Scan the current list of tasks blocked within RCU read-side critical - * sections, printing out the tid of each. + * sections, printing out the tid of each of the first few of them. */ -static int rcu_print_task_stall(struct rcu_node *rnp) +static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags) + __releases(rnp->lock) { + int i = 0; int ndetected = 0; struct rcu_stall_chk_rdr rscr; struct task_struct *t; + struct task_struct *ts[8]; if (!rcu_preempt_blocked_readers_cgp(rnp)) return 0; @@ -264,6 +273,14 @@ static int rcu_print_task_stall(struct rcu_node *rnp) t = list_entry(rnp->gp_tasks->prev, struct task_struct, rcu_node_entry); list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { + get_task_struct(t); + ts[i++] = t; + if (i >= ARRAY_SIZE(ts)) + break; + } + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + for (i--; i; i--) { + t = ts[i]; if (!try_invoke_on_locked_down_task(t, check_slow_task, &rscr)) pr_cont(" P%d", t->pid); else @@ -273,6 +290,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp) ".q"[rscr.rs.b.need_qs], ".e"[rscr.rs.b.exp_hint], ".l"[rscr.on_blkd_list]); + put_task_struct(t); ndetected++; } pr_cont("\n"); @@ -293,8 +311,9 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) * Because preemptible RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. */ -static int rcu_print_task_stall(struct rcu_node *rnp) +static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags) { + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); return 0; } #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ @@ -472,7 +491,6 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) pr_err("INFO: %s detected stalls on CPUs/tasks:\n", rcu_state.name); rcu_for_each_leaf_node(rnp) { raw_spin_lock_irqsave_rcu_node(rnp, flags); - ndetected += rcu_print_task_stall(rnp); if (rnp->qsmask != 0) { for_each_leaf_node_possible_cpu(rnp, cpu) if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) { @@ -480,7 +498,7 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) ndetected++; } } - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + ndetected += rcu_print_task_stall(rnp, flags); // Releases rnp->lock. } for_each_possible_cpu(cpu) |