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

[Julian Sun <sunjunchao@bytedance.com>]

On Mon, Sep 22, 2025 at 9:27 PM Peter Zijlstra <peterz@infradead.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@bytedance.com>