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

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Message-ID: <x5crxfuhbnlk4pz3lidlwh7y5meoqlkmteedaljeepizbxbvjr@7orhkqjvdpnk>
Date: Wed, 30 Jul 2025 22:28:45 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Boqun Feng <boqun.feng@...il.com>, 
	Waiman Long <longman@...hat.com>, Joel Granados <joel.granados@...nel.org>, 
	Anna Schumaker <anna.schumaker@...cle.com>, Lance Yang <ioworker0@...il.com>, 
	Kent Overstreet <kent.overstreet@...ux.dev>, Yongliang Gao <leonylgao@...cent.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Tomasz Figa <tfiga@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] hung_task: Dump blocker task if it is not hung

On (25/07/30 18:53), Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> 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.