====================================================== WARNING: possible circular locking dependency detected 5.3.0-rc2+ #25 Not tainted ------------------------------------------------------ syz-executor.4/6708 is trying to acquire lock: 000000006ac79e71 (iowarrior_open_disc_lock){+.+.}, at: iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600 but task is already holding lock: 000000001f588c1b (iowarrior_mutex){+.+.}, at: iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (iowarrior_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:930 [inline] __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077 iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589 usb_open+0x1df/0x270 drivers/usb/core/file.c:48 chrdev_open+0x219/0x5c0 fs/char_dev.c:414 do_dentry_open+0x494/0x1120 fs/open.c:797 do_last fs/namei.c:3416 [inline] path_openat+0x1430/0x3f50 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3c0/0x580 fs/open.c:1089 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (minor_rwsem){++++}: down_write+0x92/0x150 kernel/locking/rwsem.c:1500 usb_deregister_dev drivers/usb/core/file.c:238 [inline] usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230 iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873 usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423 __device_release_driver drivers/base/dd.c:1120 [inline] device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151 bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556 device_del+0x420/0xb10 drivers/base/core.c:2288 usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237 usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199 hub_port_connect drivers/usb/core/hub.c:4949 [inline] hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] port_event drivers/usb/core/hub.c:5359 [inline] hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441 process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 worker_thread+0x96/0xe20 kernel/workqueue.c:2415 kthread+0x318/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 -> #0 (iowarrior_open_disc_lock){+.+.}: check_prev_add kernel/locking/lockdep.c:2405 [inline] check_prevs_add kernel/locking/lockdep.c:2507 [inline] validate_chain kernel/locking/lockdep.c:2897 [inline] __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880 lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412 __mutex_lock_common kernel/locking/mutex.c:930 [inline] __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077 iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600 usb_open+0x1df/0x270 drivers/usb/core/file.c:48 chrdev_open+0x219/0x5c0 fs/char_dev.c:414 do_dentry_open+0x494/0x1120 fs/open.c:797 do_last fs/namei.c:3416 [inline] path_openat+0x1430/0x3f50 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3c0/0x580 fs/open.c:1089 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: iowarrior_open_disc_lock --> minor_rwsem --> iowarrior_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(iowarrior_mutex); lock(minor_rwsem); lock(iowarrior_mutex); lock(iowarrior_open_disc_lock); *** DEADLOCK *** 2 locks held by syz-executor.4/6708: #0: 00000000a695bcde (minor_rwsem){++++}, at: usb_open+0x23/0x270 drivers/usb/core/file.c:39 #1: 000000001f588c1b (iowarrior_mutex){+.+.}, at: iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589 stack backtrace: CPU: 0 PID: 6708 Comm: syz-executor.4 Not tainted 5.3.0-rc2+ #25 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xca/0x13e lib/dump_stack.c:113 check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741 check_prev_add kernel/locking/lockdep.c:2405 [inline] check_prevs_add kernel/locking/lockdep.c:2507 [inline] validate_chain kernel/locking/lockdep.c:2897 [inline] __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880 lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412 __mutex_lock_common kernel/locking/mutex.c:930 [inline] __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077 iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600 usb_open+0x1df/0x270 drivers/usb/core/file.c:48 chrdev_open+0x219/0x5c0 fs/char_dev.c:414 do_dentry_open+0x494/0x1120 fs/open.c:797 do_last fs/namei.c:3416 [inline] path_openat+0x1430/0x3f50 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3c0/0x580 fs/open.c:1089 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x413711 Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007fa8a31e07a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000413711 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007fa8a31e07d0 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 000000000000000f R10: 0000000000000064 R11: 0000000000000293 R12: 00007fa8a31e16d4 R13: 00000000004c8b6f R14: 00000000004dfa78 R15: 00000000ffffffff