linux-kernel - Re: [regression] boot failure on alpha, bisected

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Date:	Sun, 7 Oct 2012 18:04:20 +0000
From:	Thorsten Kranzkowski <dl8bcu@...bcu.de>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>
Subject: Re: [regression] boot failure on alpha, bisected

On Sun, Oct 07, 2012 at 07:13:00PM +0200, Oleg Nesterov wrote:
> On 10/07, Oleg Nesterov wrote:
> >
> > Hmm. I know nothing about arch/alpha and I can't understand its entry.S.
> > But _it seems_ to me that do_notify_resume() is called with irqs disabled.
> > If this is true, then imho arch/alpha should be fixed.
> >
> > Before this commit task_work_run() enabled irqs, but this was the "side
> > effect" of spin_lock_irq/spin_unlock_irq, we should not rely on this.
> 
> Could you please test the debugging patch below?

Of course. With that patch applied the kernel (ac3d0da) boots again. The trace line
is printed about once a second, with values '2' and '4'.

Thorsten

> 
> Oleg.
> 
> 
> --- x/arch/alpha/kernel/signal.c
> +++ x/arch/alpha/kernel/signal.c
> @@ -567,11 +567,19 @@ do_signal(struct pt_regs * regs, struct 
>  		ptrace_set_bpt(current);	/* re-set breakpoint */
>  }
>  
> +#include <linux/ratelimit.h>
> +
>  void
>  do_notify_resume(struct pt_regs *regs, struct switch_stack *sw,
>  		 unsigned long thread_info_flags,
>  		 unsigned long r0, unsigned long r19)
>  {
> +	if (irqs_disabled()) {
> +		printk_ratelimited(KERN_WARNING
> +			"NOTIFY with irqs_disabled:%lx\n", thread_info_flags);
> +		local_irq_enable();
> +	}
> +
>  	if (thread_info_flags & _TIF_SIGPENDING)
>  		do_signal(regs, sw, r0, r19);
>  
> 

-- 
| Thorsten Kranzkowski        Internet: dl8bcu@...bcu.de                      |
| Mobile: ++49 170 1876134       Snail: Kiebitzstr. 14, 49324 Melle, Germany  |
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