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

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Message-ID: <aNFJ_EKj4fnRDg1_@tiehlicka>
Date: Mon, 22 Sep 2025 15:07:08 +0200
From: Michal Hocko <mhocko@...e.com>
To: Julian Sun <sunjunchao@...edance.com>
Cc: 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,
	peterz@...radead.org, 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, roman.gushchin@...ux.dev,
	shakeel.butt@...ux.dev, muchun.song@...ux.dev
Subject: Re: [PATCH 0/3] Suppress undesirable hung task warnings.

On Mon 22-09-25 17:41:43, Julian Sun wrote:
> As suggested by Andrew Morton in [1], we need a general mechanism 

what is the reference?

> that allows the hung task detector to ignore unnecessary hung 
> tasks. This patch set implements this functionality.
> 
> Patch 1 introduces a PF_DONT_HUNG flag. The hung task detector will 
> ignores all tasks that have the PF_DONT_HUNG flag set.
> 
> Patch 2 introduces wait_event_no_hung() and wb_wait_for_completion_no_hung(), 
> which enable the hung task detector to ignore hung tasks caused by these
> wait events.
> 
> Patch 3 uses wb_wait_for_completion_no_hung() in the final phase of memcg 
> teardown to eliminate the hung task warning.
> 
> 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.
> 
>  fs/fs-writeback.c           | 15 +++++++++++++++
>  include/linux/backing-dev.h |  1 +
>  include/linux/sched.h       | 12 +++++++++++-
>  include/linux/wait.h        | 15 +++++++++++++++
>  kernel/hung_task.c          |  6 ++++++
>  mm/memcontrol.c             |  2 +-
>  6 files changed, 49 insertions(+), 2 deletions(-)
> 
> -- 
> 2.39.5

-- 
Michal Hocko
SUSE Labs