usb 3-1: USB disconnect, device number 2 ============================================ WARNING: possible recursive locking detected 5.7.0-rc5-syzkaller #0 Not tainted -------------------------------------------- kworker/1:7/4084 is trying to acquire lock: ffffffff89676308 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_release+0x19/0xd0 drivers/media/mc/mc-devnode.c:53 but task is already holding lock: ffffffff89676308 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x13/0x64 drivers/media/mc/mc-devnode.c:283 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(media_devnode_lock); lock(media_devnode_lock); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by kworker/1:7/4084: #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff8880a6eb2938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x814/0x15d0 kernel/workqueue.c:2239 #1: ffffc900046c7e00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x849/0x15d0 kernel/workqueue.c:2243 #2: ffff888217c30218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:768 [inline] #2: ffff888217c30218 (&dev->mutex){....}-{3:3}, at: hub_event+0x13e/0x2d60 drivers/usb/core/hub.c:5521 #3: ffff88809f430218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:768 [inline] #3: ffff88809f430218 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x8c/0x850 drivers/usb/core/hub.c:2207 #4: ffff88809cd841a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x1b/0x470 drivers/base/dd.c:1138 #5: ffffffff89676308 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x13/0x64 drivers/media/mc/mc-devnode.c:283 stack backtrace: CPU: 1 PID: 4084 Comm: kworker/1:7 Not tainted 5.7.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: usb_hub_wq hub_event Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x128/0x182 lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:2410 [inline] check_deadlock kernel/locking/lockdep.c:2451 [inline] validate_chain kernel/locking/lockdep.c:3221 [inline] __lock_acquire.cold.67+0x148/0x3da kernel/locking/lockdep.c:4355 lock_acquire+0x1e3/0x970 kernel/locking/lockdep.c:4934 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x153/0x13e0 kernel/locking/mutex.c:1103 media_devnode_release+0x19/0xd0 drivers/media/mc/mc-devnode.c:53 device_release+0x65/0x1c0 drivers/base/core.c:1394 kobject_cleanup lib/kobject.c:701 [inline] kobject_release lib/kobject.c:732 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x12e/0x230 lib/kobject.c:749 media_devnode_unregister+0x26/0x64 drivers/media/mc/mc-devnode.c:285 media_device_unregister+0x370/0x540 drivers/media/mc/mc-device.c:846 uvc_disconnect+0x98/0x100 drivers/media/usb/uvc/uvc_driver.c:2270 usb_unbind_interface+0x15c/0x870 drivers/usb/core/driver.c:436 __device_release_driver drivers/base/dd.c:1110 [inline] device_release_driver_internal+0x1d2/0x470 drivers/base/dd.c:1141 bus_remove_device+0x293/0x460 drivers/base/bus.c:533 device_del+0x421/0xc00 drivers/base/core.c:2734 usb_disable_device+0x1ae/0x580 drivers/usb/core/message.c:1245 usb_disconnect+0x227/0x850 drivers/usb/core/hub.c:2216 hub_port_connect drivers/usb/core/hub.c:5058 [inline] hub_port_connect_change drivers/usb/core/hub.c:5347 [inline] port_event drivers/usb/core/hub.c:5493 [inline] hub_event+0x1048/0x2d60 drivers/usb/core/hub.c:5575 process_one_work+0x908/0x15d0 kernel/workqueue.c:2268 worker_thread+0x82/0xb50 kernel/workqueue.c:2414 kthread+0x340/0x410 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351