From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3849731ED83; Sun, 23 Aug 2026 11:48:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787485705; cv=none; b=MOyUxmDz6N/pEH+H+vFMxcdcj/nd5tFf98TKYK+8piAGFpTvcu58q01aXbrX6AG6JN1bsfr+slqfKW3cF8UI4lb0rvky4S9DGkSB8ArFd4Qn8fsFo/tu8hOwsYudxU2uIvJl5vxcULw5wfO+6ar37o218Ix7Fyk+sNo2AE7RV78= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787485705; c=relaxed/simple; bh=6ct0qj1+D4Oyz2D9fNsOOPpl6RnmhIlFP9uj18Ozjn0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sWED7lxNwcehkryLDkyDkmq+Jb1DaQhwHaa7xSFXd1O5WMZLFO9q57ONJGdNTTX4MEJEiIC5Jtn17/5RnA3UQtG5WWQ3lXi+824UZ/RFRdyxmToKOidseIui9v0UBwcDQyfWmg36W7EmNAw3M+rXwCg2pF/vkLixREgSSYHJLew= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ixo23Nz0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ixo23Nz0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33A381F000E9; Sun, 23 Aug 2026 11:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787485703; bh=Kf12DRObSBFv1CspFHy/sUm74JFT+Ouecqhr1g5Di1A=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ixo23Nz0MgQcbOgT61iv2HiwXOLYuTP07jWZGVcy3jIT7D3pkXrvGGrf8Kh6gd2PN 992RK0sW1U0O6R/qK4bAkwh6a7HxwpEgrl6Ijyt52hS8cZALd26WccydoexkeCR7l1 Y2kgo/cuCzc2Fz2M/F+W8ganFDl7rkSCRUvWdhgA= Date: Sun, 23 Aug 2026 13:46:43 +0200 From: Greg KH To: syzbot Cc: dakr@kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, rafael@kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [usb?] INFO: task hung in unbind_store Message-ID: <2026082307-negligent-lusty-750a@gregkh> References: <6a8adc31.ae6ddae5.3da009.0064.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <6a8adc31.ae6ddae5.3da009.0064.GAE@google.com> On Sun, Aug 23, 2026 at 04:40:33AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: e8bf40d15402 Merge tag 'chrome-platform-firmware-v7.3' of .. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=13e9f679580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1941312e3e971b07 > dashboard link: https://syzkaller.appspot.com/bug?extid=fd7be5ad9795b7f29df3 > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14a75679580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/7df7b958efe0/disk-e8bf40d1.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/cefbf90e524a/vmlinux-e8bf40d1.xz > kernel image: https://storage.googleapis.com/syzbot-assets/37a530b91001/bzImage-e8bf40d1.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+fd7be5ad9795b7f29df3@syzkaller.appspotmail.com > > INFO: task syz.4.23:6285 blocked for more than 143 seconds. > Not tainted syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.4.23 state:D stack:27592 pid:6285 tgid:6285 ppid:6213 task_flags:0x400140 flags:0x00080002 > Call Trace: > > context_switch kernel/sched/core.c:5510 [inline] > __schedule+0x17d4/0x5630 kernel/sched/core.c:7239 > __schedule_loop kernel/sched/core.c:7316 [inline] > schedule+0x164/0x2b0 kernel/sched/core.c:7331 > schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7388 > __mutex_lock_common kernel/locking/mutex.c:726 [inline] > __mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821 > device_lock include/linux/device.h:1104 [inline] > __device_driver_lock drivers/base/dd.c:1170 [inline] > device_release_driver_internal+0x93/0x880 drivers/base/dd.c:1369 > unbind_store+0x1a1/0x1d0 drivers/base/bus.c:244 Ok, I'm going to add a new TAINT flag for when unbind is written to as that is obviously not a normal operation and is only for debugging things by kernel developers. Adding loads of work-arounds in the kernel for this not-real-workload-path is just not required. If syzbot could stop hitting this path, that would be great, as it's a root-only thing for debugging and not something "real". thanks, greg k-h