======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.0/5324 is trying to acquire lock:
ffffffff8fa50d80 (tpg_instances_lock){+.+.}-{4:4}, at: tcm_alloc+0x21/0x2e0 drivers/usb/gadget/function/f_tcm.c:2733

but task is already holding lock:
ffff888012aba390 (&gi->lock){+.+.}-{4:4}, at: config_usb_cfg_link+0x59/0x260 drivers/usb/gadget/configfs.c:439

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&gi->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       config_usb_cfg_link+0x59/0x260 drivers/usb/gadget/configfs.c:439
       configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
       vfs_symlink+0x18b/0x330 fs/namei.c:5660
       filename_symlinkat+0x1cd/0x410 fs/namei.c:5685
       __do_sys_symlinkat fs/namei.c:5705 [inline]
       __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5700
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&sb->s_type->i_mutex_key#24){++++}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1631
       inode_lock include/linux/fs.h:1024 [inline]
       configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1259
       usbg_make_tpg+0x1f6/0x590 drivers/usb/gadget/function/f_tcm.c:1686
       target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:939
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x406/0x620 fs/namei.c:5276
       filename_mkdirat+0x285/0x510 fs/namei.c:5309
       __do_sys_mkdirat fs/namei.c:5330 [inline]
       __se_sys_mkdirat+0x35/0x150 fs/namei.c:5327
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&opts->dep_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       usbg_make_tpg+0x147/0x590 drivers/usb/gadget/function/f_tcm.c:1678
       target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:939
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x406/0x620 fs/namei.c:5276
       filename_mkdirat+0x285/0x510 fs/namei.c:5309
       __do_sys_mkdirat fs/namei.c:5330 [inline]
       __se_sys_mkdirat+0x35/0x150 fs/namei.c:5327
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (tpg_instances_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       tcm_alloc+0x21/0x2e0 drivers/usb/gadget/function/f_tcm.c:2733
       usb_get_function+0x63/0xb0 drivers/usb/gadget/functions.c:61
       config_usb_cfg_link+0x148/0x260 drivers/usb/gadget/configfs.c:469
       configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
       vfs_symlink+0x18b/0x330 fs/namei.c:5660
       filename_symlinkat+0x1cd/0x410 fs/namei.c:5685
       __do_sys_symlinkat fs/namei.c:5705 [inline]
       __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5700
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  tpg_instances_lock --> &sb->s_type->i_mutex_key#24 --> &gi->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&gi->lock);
                               lock(&sb->s_type->i_mutex_key#24);
                               lock(&gi->lock);
  lock(tpg_instances_lock);

 *** DEADLOCK ***

3 locks held by syz.0.0/5324:
 #0: ffff888000326450 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff888013248600 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff888013248600 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: configfs_symlink+0x3af/0x1030 fs/configfs/symlink.c:186
 #2: ffff888012aba390 (&gi->lock){+.+.}-{4:4}, at: config_usb_cfg_link+0x59/0x260 drivers/usb/gadget/configfs.c:439

stack backtrace:
CPU: 0 UID: 0 PID: 5324 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
 tcm_alloc+0x21/0x2e0 drivers/usb/gadget/function/f_tcm.c:2733
 usb_get_function+0x63/0xb0 drivers/usb/gadget/functions.c:61
 config_usb_cfg_link+0x148/0x260 drivers/usb/gadget/configfs.c:469
 configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
 vfs_symlink+0x18b/0x330 fs/namei.c:5660
 filename_symlinkat+0x1cd/0x410 fs/namei.c:5685
 __do_sys_symlinkat fs/namei.c:5705 [inline]
 __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5700
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ba239e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8ba319dfe8 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007f8ba2625fa0 RCX: 00007f8ba239e019
RDX: 0000200000000900 RSI: ffffffffffffff9c RDI: 00002000000008c0
RBP: 00007f8ba243500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8ba2626038 R14: 00007f8ba2625fa0 R15: 00007fff99d52878
 </TASK>