linux-kernel - RE: [PATCH] x86_dump_trace: avoiding endless " <IRQ> " is printed

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Date:	Thu, 16 Aug 2012 01:04:26 +0000
From:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
To:	"'linux-kernel@...r.kernel.org' (linux-kernel@...r.kernel.org)" 
	<linux-kernel@...r.kernel.org>
CC:	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...or.com" <hpa@...or.com>
Subject: RE: [PATCH] x86_dump_trace: avoiding endless " <IRQ> " is printed


> The endless " <IRQ> " is as below:
> ...
> [   82.215244,0]  <IRQ>
> [   82.215399,0]  <IRQ>
> [   82.215554,0]  <IRQ>
> [   82.215710,0]  <IRQ>
> [   82.215865,0]  <IRQ>
> [   82.216022,0]  <IRQ>
> [   82.216178,0]  <IRQ>
> [   82.216333,0]  <IRQ>
> [   82.216488,0]  <IRQ>
> [   82.216643,0]  <IRQ>
> [   82.216798,0]  <IRQ>
> [   82.216953,0]  <IRQ>
> ...
> 
Anyone can give some help for the above logs? It is the real case we meet on our x86_32 platform.
I checked the code, the tons of " <IRQ> " should be printed from the below code in dumpstack_32.c:
[if (ops->stack(data, "IRQ") < 0)] will print " <IRQ> ", as for the endless printing, it should be for(;;) is not
broken, so I guess in this case context->previous_esp == context.

But from code review, previous_esp is just set at hardirq. No possible this case happening.
Who can give help? Thanks.

void dump_trace(struct task_struct *task, struct pt_regs *regs,
		unsigned long *stack, unsigned long bp,
		const struct stacktrace_ops *ops, void *data)
{
	for (;;) {
		struct thread_info *context;

		context = (struct thread_info *)
			((unsigned long)stack & (~(THREAD_SIZE - 1)));
		bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);

		stack = (unsigned long *)context->previous_esp;
		if (!stack)
			break;
		if (ops->stack(data, "IRQ") < 0) == > Here printing the " <IRQ> "
			break;
		touch_nmi_watchdog();
	}
}

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