From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
syzkaller-bugs@googlegroups.com
Cc: Bart Van Assche <bvanassche@acm.org>,
syzbot <syzbot+831661966588c802aae9@syzkaller.appspotmail.com>,
jgg@ziepe.ca, linux-kernel@vger.kernel.org,
linux-rdma@vger.kernel.org, syzkaller-bugs@googlegroups.com,
Lai Jiangshan <jiangshanlai@gmail.com>, Tejun Heo <tj@kernel.org>
Subject: Re: [syzbot] possible deadlock in worker_thread
Date: Thu, 17 Feb 2022 13:27:08 +0100 [thread overview]
Message-ID: <4168398.ejJDZkT8p0@leap> (raw)
In-Reply-To: <YgnQGZWT/n3VAITX@slm.duckdns.org>
On lunedì 14 febbraio 2022 04:44:25 CET Tejun Heo wrote:
> Hello,
>
> On Mon, Feb 14, 2022 at 10:08:00AM +0900, Tetsuo Handa wrote:
> > + destroy_workqueue(srp_tl_err_wq);
> >
> > Then, we can call WARN_ON() if e.g. flush_workqueue() is called on system-wide workqueues.
>
> Yeah, this is the right thing to do. It makes no sense at all to call
> flush_workqueue() on the shared workqueues as the caller has no idea what
> it's gonna end up waiting for. It was on my todo list a long while ago but
> slipped through the crack. If anyone wanna take a stab at it (including
> scrubbing the existing users, of course), please be my guest.
>
Just to think and understand... what if the system-wide WQ were allocated as unbound
ordered (i.e., as in alloc_ordered_workqueue()) with "max_active" of one?
1) Would it solve the locks dependency problem?
2) Would it introduce performance penalties (bottlenecks)?
Greetings,
Fabio
>
> Thanks.
>
> --
> tejun
>
next prev parent reply other threads:[~2022-02-17 12:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-10 19:27 [syzbot] possible deadlock in worker_thread syzbot
2022-02-11 18:59 ` Bart Van Assche
2022-02-12 5:31 ` Tetsuo Handa
2022-02-12 16:37 ` Bart Van Assche
2022-02-12 17:14 ` Tetsuo Handa
2022-02-13 15:33 ` Leon Romanovsky
2022-02-13 23:06 ` Bart Van Assche
2022-02-14 1:08 ` Tetsuo Handa
2022-02-14 3:44 ` Tejun Heo
2022-02-14 13:36 ` Tetsuo Handa
2022-02-14 17:34 ` Tejun Heo
2022-02-15 10:26 ` Tetsuo Handa
2022-02-15 10:43 ` Haakon Bugge
2022-02-15 12:48 ` Tetsuo Handa
2022-02-15 17:05 ` Bart Van Assche
2022-02-15 22:05 ` Tetsuo Handa
2022-02-22 18:26 ` Tejun Heo
2022-02-17 11:22 ` [PATCH v2] workqueue: Warn flush attempt using system-wide workqueues Tetsuo Handa
2022-02-22 18:36 ` Tejun Heo
2022-02-23 21:20 ` Marek Szyprowski
2022-02-23 21:35 ` Tejun Heo
2022-02-23 22:06 ` Tetsuo Handa
2022-02-17 12:27 ` Fabio M. De Francesco [this message]
2022-02-22 18:30 ` [syzbot] possible deadlock in worker_thread Tejun Heo
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