From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Yunseong Kim <ysk@kzalloc.com>
Cc: linux-usb@vger.kernel.org, linux-rt-users@vger.kernel.org,
gregkh@linuxfoundation.org, stern@rowland.harvard.edu,
Thomas Gleixner <tglx@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, syzkaller@googlegroups.com
Subject: Re: [BUG] usb: sleepable spinlock used in USB bh_worker softirq on PREEMPT_RT
Date: Mon, 11 Aug 2025 11:15:59 +0200 [thread overview]
Message-ID: <20250811091559.CXIs7FvU@linutronix.de> (raw)
In-Reply-To: <1f8dd706-0eb0-4e09-a0fe-fc48fb24005e@kzalloc.com>
On 2025-08-11 00:05:49 [+0900], Yunseong Kim wrote:
> While running a PREEMPT_RT-enabled kernel I observed a sleepable
> spinlock (rt_spin_lock) being taken from a softirq context within
> the USB core framework. On PREEMPT_RT, spin_lock() may sleep when
> contended. This is unsafe in softirq context and can cause hangs or
> deadlocks.
>
…
> I believe this requires a change in the USB core framework rather than
> just in individual drivers.
>
> Kernel config, full logs, and reproduction steps can be provided on
> request.
>
> This bug was uncovered during my work to fixing KCOV for PREEMPT_RT awareness.
> Link: https://lore.kernel.org/all/ee26e7b2-80dd-49b1-bca2-61e460f73c2d@kzalloc.com/t/#u
I'm confused. Is this new or this the same bug that was reported by you
in the thread you linked?
The kcov issue should be fixed by
https://lore.kernel.org/all/20250811082745.ycJqBXMs@linutronix.de/
> Best Regards,
> Yunseong Kim
Sebastian
next prev parent reply other threads:[~2025-08-11 9:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-10 15:05 [BUG] usb: sleepable spinlock used in USB bh_worker softirq on PREEMPT_RT Yunseong Kim
2025-08-11 9:15 ` Sebastian Andrzej Siewior [this message]
2025-08-11 15:40 ` Yunseong Kim
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