linux-kernel - Re: [PACTH v1] kernel/hung_task.c: Dump all UNINTERUPTIBLE tasks

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Message-Id: <20160810154345.f0c34d0936b0835b541405b0@linux-foundation.org>
Date:	Wed, 10 Aug 2016 15:43:45 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	robert.foss@...labora.com
Cc:	adurbin@...omium.org, penguin-kernel@...ove.SAKURA.ne.jp,
	linux-kernel@...r.kernel.org
Subject: Re: [PACTH v1] kernel/hung_task.c: Dump all UNINTERUPTIBLE tasks

On Tue,  2 Aug 2016 11:23:11 -0400 robert.foss@...labora.com wrote:

> From: Aaron Durbin <adurbin@...omium.org>
> 
> When the panic path is taken for khungtaskd dump all
> tasks with the UNINTERUPTIBLE state. That way, any
> inter-dependent tasks that caused one another to hang
> will be saved in the crash output.
> 
> ...
>
> --- a/kernel/hung_task.c
> +++ b/kernel/hung_task.c
> @@ -122,6 +122,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
>  	touch_nmi_watchdog();
>  
>  	if (sysctl_hung_task_panic) {
> +		/* Dump all tasks. */
> +		show_state_filter(TASK_UNINTERRUPTIBLE);
>  		trigger_all_cpu_backtrace();
>  		panic("hung_task: blocked tasks");
>  	}

Well, it's going to produce more gunk for the operator to read through
and understand.

I'd like to hear a little more about the value of this change: what
particular problem prompted it, etc.