From: Andrew Morton <akpm@linux-foundation.org>
To: Lance Yang <lance.yang@linux.dev>
Cc: Julian Sun <sunjunchao@bytedance.com>,
mhiramat@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org,
jack@suse.cz, mingo@redhat.com, peterz@infradead.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, vschneid@redhat.com,
agruenba@redhat.com, hannes@cmpxchg.org, mhocko@kernel.org,
roman.gushchin@linux.dev, shakeel.butt@linux.dev,
muchun.song@linux.dev, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 0/3] Suppress undesirable hung task warnings.
Date: Mon, 22 Sep 2025 14:57:54 -0700 [thread overview]
Message-ID: <20250922145754.31890092257495f70db3909d@linux-foundation.org> (raw)
In-Reply-To: <b31a538a-c361-4e3e-a5b6-6a3d2083ef3b@linux.dev>
On Mon, 22 Sep 2025 19:38:21 +0800 Lance Yang <lance.yang@linux.dev> wrote:
> On 2025/9/22 17:41, Julian Sun wrote:
> > As suggested by Andrew Morton in [1], we need a general mechanism
> > that allows the hung task detector to ignore unnecessary hung
>
> Yep, I understand the goal is to suppress what can be a benign hung task
> warning during memcg teardown.
>
> > 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.
>
> However, I'm concerned that the PF_DONT_HUNG flag is a bit too powerful
> and might mask real, underlying hangs.
I think that's OK if the calling task is discriminating about it. Just
set PF_DONT_HUNG (unpleasing name!) around those bits of code where
it's needed, clear it otherwise.
Julian, did you take a look at what a touch_hung_task_detector() would
involve? It's a bit of an interface inconsistency - our various other
timeout detectors (softlockup, NMI, rcu) each have a touch_ function.
next prev parent reply other threads:[~2025-09-22 21:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-22 9:41 [PATCH 0/3] Suppress undesirable hung task warnings Julian Sun
2025-09-22 9:41 ` [PATCH 1/3] sched: Introduce a new flag PF_DONT_HUNG Julian Sun
2025-09-22 9:41 ` [PATCH 2/3] writeback: Introduce wb_wait_for_completion_no_hung() Julian Sun
2025-09-22 9:41 ` [PATCH 3/3] memcg: Don't trigger hung task warnings when memcg is releasing resources Julian Sun
2025-09-22 11:38 ` [PATCH 0/3] Suppress undesirable hung task warnings Lance Yang
2025-09-22 12:40 ` Julian Sun
2025-09-22 13:12 ` Lance Yang
2025-09-22 21:57 ` Andrew Morton [this message]
2025-09-23 2:30 ` Lance Yang
2025-09-23 2:45 ` [External] " Julian Sun
2025-09-23 3:18 ` Lance Yang
2025-09-22 13:07 ` Michal Hocko
2025-09-22 14:24 ` [External] " Julian Sun
2025-09-22 13:27 ` Peter Zijlstra
2025-09-22 14:29 ` [External] " Julian Sun
2025-09-22 15:27 ` Jan Kara
2025-09-22 18:08 ` Christoph Hellwig
2025-09-22 21:50 ` Andrew Morton
2025-09-23 7:16 ` Peter Zijlstra
2025-09-23 12:44 ` Masami Hiramatsu
2025-09-24 10:34 ` Jan Kara
2025-09-25 15:07 ` [External] " Julian Sun
2025-09-25 16:30 ` Jan Kara
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