From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 A84803594F; Mon, 11 Aug 2025 09:16:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754903766; cv=none; b=d+tnseF5jnOX7MboYLfAGhCbeJe8Mi4cT+MS58/MTJlxayRP+kgECG6Zy1g5wAQ2sroMZv59CkBgBVEB09+dTqWRzmy81pNP/Owy+ixM4F0ysCGK4Edz90YJ9Y7ab0ZHZ+4Vc2be83laLKmxEUfDEOyP0J089gu+AkCBEz+uAUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754903766; c=relaxed/simple; bh=3gvCQOh6C5GJIsuPURtBiqN006xYmsfrt4uX4V1wT1U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AEvK5gRkV0maibQ9wDKwo3qlqUc9cr0m7v8I5fC6kHeYwz+vOcRuQz/Vc//NrmgJtMnzjy57bNYEhIFBgG2h1JlFdxhuGiufpnAiQocuYK+pujIMwWolpuNhhl+1h4zRGHtQoxbDwDvMSt0ufWEEgmQ9Hk8n4R+SLSBHdSHRJ2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=k/obJeoS; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=dT6uveYr; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="k/obJeoS"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dT6uveYr" Date: Mon, 11 Aug 2025 11:15:59 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1754903760; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Xhk8ImetUzF8D0zaYt5H2LhPKkbfmmDl4qiWDQ3+Yns=; b=k/obJeoSdTlreKOiO839gioCZpb79DC5QxDpfh52u1p/xuxIrl+bABA3xf2OuizloY/v/2 IdcFODJhgq8SnAn8VjkqAclaKNASSsIUFYym3gkVt/FiV2IkwduMQOIxQawTcpz9CqmVva FnrZjDc1MdiAjzv589070n9Zx0ma3vNQZw7TQpksyTRp4X8w/NwjTC1qmanxXnlE9Ku/tP S3kZWNsjSlsOFZrQhvnyYbN4FhLyX9zaMSVha8o5vqpDjoGzbjSjpmZh1EX6hmRdO0cxS0 77KjbhNX1o4f+lR7C4XA+qsLg6/ZHmRjaGm/va0aCle5ZpTV42WaL67uWf+9KQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1754903760; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Xhk8ImetUzF8D0zaYt5H2LhPKkbfmmDl4qiWDQ3+Yns=; b=dT6uveYr/y0FouDVq4hoDzonHMQ2drGBSiuSMB/5VKBKTzJ6ekocxWOGZI5fSYGfynbZ1O xHx2EXNWKjxGuaDQ== From: Sebastian Andrzej Siewior To: Yunseong Kim Cc: linux-usb@vger.kernel.org, linux-rt-users@vger.kernel.org, gregkh@linuxfoundation.org, stern@rowland.harvard.edu, Thomas Gleixner , Clark Williams , Steven Rostedt , linux-kernel@vger.kernel.org, syzkaller@googlegroups.com Subject: Re: [BUG] usb: sleepable spinlock used in USB bh_worker softirq on PREEMPT_RT Message-ID: <20250811091559.CXIs7FvU@linutronix.de> References: <1f8dd706-0eb0-4e09-a0fe-fc48fb24005e@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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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. >=20 =E2=80=A6 > I believe this requires a change in the USB core framework rather than > just in individual drivers. >=20 > Kernel config, full logs, and reproduction steps can be provided on > request. >=20 > This bug was uncovered during my work to fixing KCOV for PREEMPT_RT aware= ness. > Link: https://lore.kernel.org/all/ee26e7b2-80dd-49b1-bca2-61e460f73c2d@kz= alloc.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