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[24.187.169.170]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6ce00999c52sm17193516d6.95.2024.10.21.06.37.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Oct 2024 06:37:50 -0700 (PDT) Date: Mon, 21 Oct 2024 09:37:48 -0400 From: Alan Stern To: Oliver Neukum Cc: syzbot , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, sylv@sylv.io, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [usb?] INFO: task hung in usb_port_suspend Message-ID: References: <67153205.050a0220.1e4b4d.0048.GAE@google.com> <0abd3cbd-0e8a-43b2-8cb0-6556297aa7c9@suse.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: <0abd3cbd-0e8a-43b2-8cb0-6556297aa7c9@suse.com> On Mon, Oct 21, 2024 at 10:04:52AM +0200, Oliver Neukum wrote: > On 20.10.24 18:38, syzbot wrote: > > INFO: task kworker/0:0:8 blocked for more than 143 seconds. > > Not tainted 6.12.0-rc3-syzkaller-00051-g07b887f8236e #0 > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > task:kworker/0:0 state:D stack:24544 pid:8 tgid:8 ppid:2 flags:0x00004000 > > Workqueue: pm pm_runtime_work > > Call Trace: > > > > context_switch kernel/sched/core.c:5322 [inline] > > __schedule+0x105f/0x34b0 kernel/sched/core.c:6682 > > __schedule_loop kernel/sched/core.c:6759 [inline] > > schedule+0xe7/0x350 kernel/sched/core.c:6774 > > And this sleeps forever. This must not happen. > > usb_kill_urb.part.0+0x1ca/0x250 drivers/usb/core/urb.c:713 > > usb_kill_urb+0x83/0xa0 drivers/usb/core/urb.c:702 > > We are changing our mind, presumably due to a timeout > > usb_start_wait_urb+0x255/0x4c0 drivers/usb/core/message.c:65 > > We are sending a control message, presumably to enable > remote wakeup > > usb_internal_control_msg drivers/usb/core/message.c:103 [inline] > > usb_control_msg+0x327/0x4b0 drivers/usb/core/message.c:154 > > usb_enable_remote_wakeup drivers/usb/core/hub.c:3365 [inline] > > usb_port_suspend+0x339/0xf10 drivers/usb/core/hub.c:3472 > > Suspending ... > > usb_generic_driver_suspend+0xeb/0x1d0 drivers/usb/core/generic.c:302 > > usb_suspend_device drivers/usb/core/driver.c:1272 [inline] > > usb_suspend_both+0x66d/0x9c0 drivers/usb/core/driver.c:1443 > > usb_runtime_suspend+0x49/0x180 drivers/usb/core/driver.c:1968 > > This very much looks like the HC driver used to run these tests > can hand in unlink. If that happens there is nothing usbcore > or a driver can do. > As this is now reproducible I would suggest a bisection. Brute force, > but I see no good alternative. > > Syzbot is an important tool and if the HC driver it uses is unreliable, > the whole thing becomes unreliable and that is most undesirable. This issue should be fixed by commit 5189df7b8088 ("USB: gadget: dummy-hcd: Fix "task hung" problem"). Alan Stern