From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE71D128819; Sat, 26 Jul 2025 06:36:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753511801; cv=none; b=kpRrTeZx0yLOqi+LajCYdDLsIDqPkb9uDGB5kJEkXQso5+CcODZXWGQahxGkePv+uWjXgNWf0oC5ulQCaaJH4usQN9NNoJFP6/yWXu2wemBbtO17FGQeYNoonZo6S3gF8x9H7PSe4Z869nRe+0fxABTX75HUJYhcnleyEnYLVIg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753511801; c=relaxed/simple; bh=5vwqn6VniSu+7gYJT+ma+sD+AePMl3SSq5Xjl7bcOCU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lmIG4h1fIKzGP3r7GPV35+xjM2alQZybc2I7Fe8GqUaK4vZm6DGDLD+lnDM7r5KwanNdKABkF8AMWk2zqTjYBrt8huLqadWDvE6aeZhkdHitcpRX0aN5CZIuFCP70jSh9yxRAU9VL16VMOrJ2VHVQVFQ+Q3y3eOIjkG+IYUCHGQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Z4FAtJ2R; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Z4FAtJ2R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7B37C4CEEF; Sat, 26 Jul 2025 06:36:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1753511800; bh=5vwqn6VniSu+7gYJT+ma+sD+AePMl3SSq5Xjl7bcOCU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z4FAtJ2RhA5fhEX0nzzCnRKaNYzpE2Y6tuFBTbs8p1u0vvJJu1fnggHciIAL8lqoa qi/5tg2w01WA025v9e+AZfLGyz/VJt58Af/gDj9CjUpI7qyN3xTvRq2VlgUp0bofXR Q8KtJ1rrtAIePcM0PSUlTZAZWRzv3kGKxkGPKouM= Date: Sat, 26 Jul 2025 08:36:37 +0200 From: Greg Kroah-Hartman To: Yunseong Kim Cc: Dmitry Vyukov , Andrey Konovalov , Byungchul Park , max.byungchul.park@gmail.com, Yeoreum Yun , Michelle Jin , linux-kernel@vger.kernel.org, Tetsuo Handa , Alan Stern , Thomas Gleixner , Sebastian Andrzej Siewior , stable@vger.kernel.org, kasan-dev@googlegroups.com, syzkaller@googlegroups.com, linux-usb@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] kcov, usb: Fix invalid context sleep in softirq path on PREEMPT_RT Message-ID: <2025072615-espresso-grandson-d510@gregkh> References: <20250725201400.1078395-2-ysk@kzalloc.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250725201400.1078395-2-ysk@kzalloc.com> On Fri, Jul 25, 2025 at 08:14:01PM +0000, Yunseong Kim wrote: > When fuzzing USB with syzkaller on a PREEMPT_RT enabled kernel, following > bug is triggered in the ksoftirqd context. > > | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 > | in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 30, name: ksoftirqd/1 > | preempt_count: 0, expected: 0 > | RCU nest depth: 2, expected: 2 > | CPU: 1 UID: 0 PID: 30 Comm: ksoftirqd/1 Tainted: G W 6.16.0-rc1-rt1 #11 PREEMPT_RT > | Tainted: [W]=WARN > | Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025 > | Call trace: > | show_stack+0x2c/0x3c (C) > | __dump_stack+0x30/0x40 > | dump_stack_lvl+0x148/0x1d8 > | dump_stack+0x1c/0x3c > | __might_resched+0x2e4/0x52c > | rt_spin_lock+0xa8/0x1bc > | kcov_remote_start+0xb0/0x490 > | __usb_hcd_giveback_urb+0x2d0/0x5e8 > | usb_giveback_urb_bh+0x234/0x3c4 > | process_scheduled_works+0x678/0xd18 > | bh_worker+0x2f0/0x59c > | workqueue_softirq_action+0x104/0x14c > | tasklet_action+0x18/0x8c > | handle_softirqs+0x208/0x63c > | run_ksoftirqd+0x64/0x264 > | smpboot_thread_fn+0x4ac/0x908 > | kthread+0x5e8/0x734 > | ret_from_fork+0x10/0x20 Why is this only a USB thing? What is unique about it to trigger this issue? thanks, greg k-h