From 9b9500da81502738efa1b485a8835f174ff7be6d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 17 Aug 2017 17:05:59 -0700 Subject: rcu: Make RCU CPU stall warnings check for irq-disabled CPUs One common question upon seeing an RCU CPU stall warning is "did the stalled CPUs have interrupts disabled?" However, the current stall warnings are silent on this point. This commit therefore uses irq_work to check whether stalled CPUs still respond to IPIs, and flags this state in the RCU CPU stall warning console messages. Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel/rcu/tree_plugin.h') diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index e012b9b..14977d0 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1671,6 +1671,7 @@ static void print_cpu_stall_info_begin(void) */ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu) { + unsigned long delta; char fast_no_hz[72]; struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); struct rcu_dynticks *rdtp = rdp->dynticks; @@ -1685,11 +1686,15 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu) ticks_value = rsp->gpnum - rdp->gpnum; } print_cpu_stall_fast_no_hz(fast_no_hz, cpu); - pr_err("\t%d-%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n", + delta = rdp->mynode->gpnum - rdp->rcu_iw_gpnum; + pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n", cpu, "O."[!!cpu_online(cpu)], "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)], "N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)], + !IS_ENABLED(CONFIG_IRQ_WORK) ? '?' : + rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : + "!."[!delta], ticks_value, ticks_title, rcu_dynticks_snap(rdtp) & 0xfff, rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting, -- cgit v1.1