linux-kernel - Re: [PATCH 0/3] Suppress undesirable hung task warnings.

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Message-ID: <aNGQoPFTH2_xrd9L@infradead.org>
Date: Mon, 22 Sep 2025 11:08:32 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Julian Sun <sunjunchao@...edance.com>, cgroups@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
	mingo@...hat.com, juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, akpm@...ux-foundation.org,
	lance.yang@...ux.dev, mhiramat@...nel.org, agruenba@...hat.com,
	hannes@...xchg.org, mhocko@...nel.org, roman.gushchin@...ux.dev,
	shakeel.butt@...ux.dev, muchun.song@...ux.dev
Subject: Re: [PATCH 0/3] Suppress undesirable hung task warnings.

On Mon, Sep 22, 2025 at 03:27:18PM +0200, Peter Zijlstra wrote:
> > Julian Sun (3):
> >   sched: Introduce a new flag PF_DONT_HUNG.
> >   writeback: Introduce wb_wait_for_completion_no_hung().
> >   memcg: Don't trigger hung task when memcg is releasing.
> 
> This is all quite terrible. I'm not at all sure why a task that is
> genuinely not making progress and isn't killable should not be reported.

The hung device detector is way to aggressive for very slow I/O.
See blk_wait_io, which has been around for a long time to work
around just that.  Given that this series targets writeback I suspect
it is about an overloaded device as well.

> 
---end quoted text---