From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Daniel Vacek <neelx@suse.com>
Cc: edumazet@google.com, kuba@kernel.org,
linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev,
netdev@vger.kernel.org, spasswolf@web.de, tglx@linutronix.de,
Aaron Tomlin <atomlin@atomlin.com>
Subject: Re: "Dead loop on virtual device" error without softirq-BKL on PREEMPT_RT
Date: Thu, 2 Apr 2026 10:31:23 +0200 [thread overview]
Message-ID: <20260402083123.1H4kyAEn@linutronix.de> (raw)
In-Reply-To: <CAPjX3Ffz22M_ADE1xPqHOCyni1wLwc+reLTVyOrJ+gqNYY6vwg@mail.gmail.com>
On 2026-04-02 09:50:35 [+0200], Daniel Vacek wrote:
> My idea was that the non-preemptible one can record `current` task
> instead of the CPU to detect the deadlock. And that would also work
> for the preemptible case (it would actually match the lock owner
> approach as you did for the PREEMPT_RT case).
> One code for both configurations, no special-casing. I'd argue that's
> a better result. Am I missing something?
>
> The size of the netdev_queue structure would grow by 8 bytes for !RT
> case, but that's not a big deal, IMO. For RT case it would just fill
> the hole.
We have xmit_lock_owner as int. If you replace it with task_struct *
then on 64bit the size of the struct netdev_queue will remain unchanged
as it fills the hole before the following long.
Then you could record `current' as the lock owner in both cases. This
should work.
> --nX
Sebastian
next prev parent reply other threads:[~2026-04-02 8:31 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-16 13:43 "Dead loop on virtual device" error without softirq-BKL on PREEMPT_RT Bert Karwatzki
2026-02-16 15:32 ` Bert Karwatzki
2026-02-16 15:37 ` Sebastian Andrzej Siewior
2026-02-16 23:48 ` Bert Karwatzki
2026-02-17 7:19 ` Sebastian Andrzej Siewior
2026-02-17 8:56 ` Bert Karwatzki
2026-02-17 9:57 ` Sebastian Andrzej Siewior
2026-02-17 10:42 ` Bert Karwatzki
2026-02-17 11:24 ` Bert Karwatzki
2026-02-17 16:52 ` Bert Karwatzki
2026-02-17 19:10 ` Bert Karwatzki
2026-02-18 7:30 ` Sebastian Andrzej Siewior
2026-02-18 12:50 ` Bert Karwatzki
2026-02-26 17:29 ` Sebastian Andrzej Siewior
2026-03-18 10:30 ` Daniel Vacek
2026-03-18 11:18 ` Sebastian Andrzej Siewior
2026-03-18 14:43 ` Daniel Vacek
2026-03-18 14:51 ` Sebastian Andrzej Siewior
2026-03-18 14:58 ` Daniel Vacek
2026-04-01 16:55 ` Daniel Vacek
2026-04-02 7:03 ` Sebastian Andrzej Siewior
2026-04-02 7:50 ` Daniel Vacek
2026-04-02 8:31 ` Sebastian Andrzej Siewior [this message]
2026-04-02 9:21 ` Daniel Vacek
2026-04-02 13:46 ` Sebastian Andrzej Siewior
2026-04-02 13:58 ` Daniel Vacek
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