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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHSKhteGasUZa8u6_YUhwH3V_b_QLwBu7dDAEob4SBC7K8KTGQ@mail.gmail.com>
Date: Mon, 22 Sep 2025 22:29:23 +0800
From: Julian Sun <sunjunchao@...edance.com>
To: Peter Zijlstra <peterz@...radead.org>
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, 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: [External] Re: [PATCH 0/3] Suppress undesirable hung task warnings.

On Mon, Sep 22, 2025 at 9:27 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Mon, Sep 22, 2025 at 05:41:43PM +0800, 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
> > 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.
>
> 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.

Actually, I tried another approach to fix this issue [1], but Andrew
thinks eliminating the warning should be simpler. Either approach is
fine with me.

[1]: https://lore.kernel.org/cgroups/20250917212959.355656-1-sunjunchao@bytedance.com/

Thanks,
-- 
Julian Sun <sunjunchao@...edance.com>