======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/4319 is trying to acquire lock:
ffff888023b61220 (&mdc800->io_lock){+.+.}-{3:3}, at: mdc800_device_open+0x2a/0x430 drivers/usb/image/mdc800.c:611

but task is already holding lock:
ffffffff8cdbb3d0 (minor_rwsem#2){++++}-{3:3}, at: usb_open+0x2c/0x300 drivers/usb/core/file.c:39

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (minor_rwsem#2){++++}-{3:3}:
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       usb_register_dev+0x2a3/0x7f0 drivers/usb/core/file.c:187
       mdc800_usb_probe+0xf8a/0x1870 drivers/usb/image/mdc800.c:485
       usb_probe_interface+0x5be/0xae0 drivers/usb/core/driver.c:396
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x276/0xc70 drivers/base/dd.c:595
       __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:775
       driver_probe_device+0x4f/0x420 drivers/base/dd.c:805
       __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:927
       bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
       __device_attach+0x2a7/0x480 drivers/base/dd.c:999
       bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
       device_add+0xbcf/0x1050 drivers/base/core.c:3427
       usb_set_configuration+0x19d5/0x2030 drivers/usb/core/message.c:2223
       usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
       usb_probe_device+0x126/0x250 drivers/usb/core/driver.c:293
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x276/0xc70 drivers/base/dd.c:595
       __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:775
       driver_probe_device+0x4f/0x420 drivers/base/dd.c:805
       __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:927
       bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
       __device_attach+0x2a7/0x480 drivers/base/dd.c:999
       bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
       device_add+0xbcf/0x1050 drivers/base/core.c:3427
       usb_new_device+0x9f6/0x15d0 drivers/usb/core/hub.c:2632
       hub_port_connect drivers/usb/core/hub.c:5497 [inline]
       hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
       port_event drivers/usb/core/hub.c:5799 [inline]
       hub_event+0x2b8d/0x5260 drivers/usb/core/hub.c:5881
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (&mdc800->io_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       mdc800_device_open+0x2a/0x430 drivers/usb/image/mdc800.c:611
       usb_open+0x1fe/0x300 drivers/usb/core/file.c:48
       chrdev_open+0x585/0x5f0 fs/char_dev.c:414
       do_dentry_open+0x7f7/0xf90 fs/open.c:826
       do_open fs/namei.c:3616 [inline]
       path_openat+0x2718/0x2fb0 fs/namei.c:3750
       do_filp_open+0x1df/0x400 fs/namei.c:3777
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(minor_rwsem#2);
                               lock(&mdc800->io_lock);
                               lock(minor_rwsem#2);
  lock(&mdc800->io_lock);

 *** DEADLOCK ***

1 lock held by syz.0.17/4319:
 #0: ffffffff8cdbb3d0 (minor_rwsem#2){++++}-{3:3}, at: usb_open+0x2c/0x300 drivers/usb/core/file.c:39

stack backtrace:
CPU: 1 PID: 4319 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 mdc800_device_open+0x2a/0x430 drivers/usb/image/mdc800.c:611
 usb_open+0x1fe/0x300 drivers/usb/core/file.c:48
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3750
 do_filp_open+0x1df/0x400 fs/namei.c:3777
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4bb253890e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffcf431ef28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00005555727f6500 RCX: 00007f4bb253890e
RDX: 0000000000000002 RSI: 00007ffcf431f000 RDI: ffffffffffffff9c
RBP: 00007f4bb260f024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4bb27fffac R14: 00007f4bb27fffa0 R15: 00007f4bb27fffa0
 </TASK>