From: Tejun Heo <tj@kernel.org>
To: Chenglong Tang <chenglongtang@google.com>
Cc: stable@vger.kernel.org, regressions@lists.linux.dev,
roman.gushchin@linux.dev, linux-mm@kvack.org,
lakitu-dev@google.com, Jan Kara <jack@suse.cz>
Subject: Re: [REGRESSION] workqueue/writeback: Severe CPU hang due to kworker proliferation during I/O flush and cgroup cleanup
Date: Fri, 26 Sep 2025 09:59:53 -1000 [thread overview]
Message-ID: <aNbwuc_Efg-Bj2Yu@slm.duckdns.org> (raw)
In-Reply-To: <CAOdxtTYKrMhjW9JiOCDBia+s=2tob1HF6yfAytYnajYsSoX5Kg@mail.gmail.com>
cc'ing Jan.
On Fri, Sep 26, 2025 at 12:54:29PM -0700, Chenglong Tang wrote:
> Just did more testing here. Confirmed that the system hang's still
> there but less frequently(6/40) with the patches
> http://lkml.kernel.org/r/20250912103522.2935-1-jack@suse.cz appied to
> v6.17-rc7. In the bad instances, the kworker count climbed to over
> 600+ and caused the hang over 80+ seconds.
>
> So I think the patches didn't fully solve the issue.
I wonder how the number of workers still exploded to 600+. Are there that
many cgroups being shut down? Does clamping down @max_active resolve the
problem? There's no reason to have really high concurrency for this.
Thanks.
--
tejun
next prev parent reply other threads:[~2025-09-26 19:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-25 0:29 Chenglong Tang
2025-09-26 19:54 ` Chenglong Tang
2025-09-26 19:59 ` Tejun Heo [this message]
2025-09-26 20:07 ` Chenglong Tang
-- strict thread matches above, loose matches on Subject: below --
2025-09-25 0:24 Chenglong Tang
2025-09-25 0:52 ` Tejun Heo
2025-09-25 16:58 ` Chenglong Tang
2025-09-26 19:50 ` Chenglong Tang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aNbwuc_Efg-Bj2Yu@slm.duckdns.org \
--to=tj@kernel.org \
--cc=chenglongtang@google.com \
--cc=jack@suse.cz \
--cc=lakitu-dev@google.com \
--cc=linux-mm@kvack.org \
--cc=regressions@lists.linux.dev \
--cc=roman.gushchin@linux.dev \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox