Re: [RFC PATCH] hung_task: Dump blocker task if it is not hung

[Sergey Senozhatsky]

On (25/07/30 18:53), Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> 
> Dump the lock blocker task if it is not hung because if the blocker
> task is also hung, it should be dumped by the detector. This will
> de-duplicate the same stackdumps if the blocker task is also blocked
> by another task (and hung).

[..]

>  #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
> -static void debug_show_blocker(struct task_struct *task)
> +static void debug_show_blocker(struct task_struct *task, unsigned long timeout)
>  {
>  	struct task_struct *g, *t;
>  	unsigned long owner, blocker, blocker_type;
> @@ -153,41 +193,21 @@ static void debug_show_blocker(struct task_struct *task)
>  			       task->comm, task->pid, t->comm, t->pid);
>  			break;
>  		}
> -		sched_show_task(t);
> +		/* Avoid duplicated task dump, skip if the task is also hung. */
> +		if (!task_is_hung(t, timeout))
> +			sched_show_task(t);
>  		return;
>  	}

This patch seems to be against the tree that is significantly
behind the current linux-next.  Namely it's in conflict with
linux-next's commit 77da18de55ac6.