rcu: Dump local stack if cannot dump all CPUs' stacks (4627e240) · Commits · 戴 / test

The trigger_all_cpu_backtrace() function is a no-op in architectures that do not define arch_trigger_all_cpu_backtrace. On such architectures, RCU CPU stall warning messages contain no stack trace information, which makes debugging quite difficult. This commit therefore substitutes dump_stack() for architectures that do not define arch_trigger_all_cpu_backtrace, so that at least the local CPU's stack is dumped as part of the RCU CPU stall warning message. Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcutree.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -583,7 +583,8 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
		}
		printk("} (detected by %d, t=%ld jiffies)\n",
		smp_processor_id(), (long)(jiffies - rsp->gp_start));
		trigger_all_cpu_backtrace();
		if (!trigger_all_cpu_backtrace())
		dump_stack();

		/* If so configured, complain about tasks blocking the grace period. */

		@@ -604,7 +605,8 @@ static void print_cpu_stall(struct rcu_state *rsp)
		*/
		printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n",
		rsp->name, smp_processor_id(), jiffies - rsp->gp_start);
		trigger_all_cpu_backtrace();
		if (!trigger_all_cpu_backtrace())
		dump_stack();

		raw_spin_lock_irqsave(&rnp->lock, flags);
		if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))

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