======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.5837/27796 is trying to acquire lock:
ffff8880238f6c00 (&sb->s_type->i_mutex_key#44){++++}-{4:4}, at: inode_lock include/linux/fs.h:1025 [inline]
ffff8880238f6c00 (&sb->s_type->i_mutex_key#44){++++}-{4:4}, at: configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1259

but task is already holding lock:
ffff888035418118 (&opts->dep_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x147/0x590 drivers/usb/gadget/function/f_tcm.c:1678

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&opts->dep_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       tcm_set_name+0x2b/0xd0 drivers/usb/gadget/function/f_tcm.c:2669
       function_make+0x1a8/0x360 drivers/usb/gadget/configfs.c:636
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x40c/0x620 fs/namei.c:5410
       filename_mkdirat+0x285/0x510 fs/namei.c:5443
       __do_sys_mkdirat fs/namei.c:5464 [inline]
       __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x510 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (gadget_subsys.su_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       uvcg_streaming_header_allow_link+0x75/0x4d0 drivers/usb/gadget/function/uvc_configfs.c:1750
       configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
       vfs_symlink+0x18b/0x330 fs/namei.c:5794
       filename_symlinkat+0x1cd/0x410 fs/namei.c:5819
       __do_sys_symlinkat fs/namei.c:5839 [inline]
       __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5834
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x510 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&sb->s_type->i_mutex_key#44){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3181 [inline]
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
       down_write+0x96/0x200 kernel/locking/rwsem.c:1631
       inode_lock include/linux/fs.h:1025 [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+0x40c/0x620 fs/namei.c:5410
       filename_mkdirat+0x285/0x510 fs/namei.c:5443
       __do_sys_mkdirat fs/namei.c:5464 [inline]
       __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x510 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &sb->s_type->i_mutex_key#44 --> gadget_subsys.su_mutex --> &opts->dep_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&opts->dep_lock);
                               lock(gadget_subsys.su_mutex);
                               lock(&opts->dep_lock);
  lock(&sb->s_type->i_mutex_key#44);

 *** DEADLOCK ***

locks held by syz.5.5837/27796: 5, last CPU#0:
 #0: ffff88801d7ac460 (sb_writers#29){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff888078e41440 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1070 [inline]
 #1: ffff888078e41440 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
 #1: ffff888078e41440 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
 #1: ffff888078e41440 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: filename_create+0x200/0x370 fs/namei.c:5092
 #2: ffffffff8f7241e8 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_mkdir+0x4b0/0x9e0 fs/configfs/dir.c:1358
 #3: ffffffff8fa597c0 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0xf7/0x590 drivers/usb/gadget/function/f_tcm.c:1669
 #4: ffff888035418118 (&opts->dep_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x147/0x590 drivers/usb/gadget/function/f_tcm.c:1678

stack backtrace:
CPU: 0 UID: 0 PID: 27796 Comm: syz.5.5837 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191
 check_prev_add kernel/locking/lockdep.c:3181 [inline]
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 down_write+0x96/0x200 kernel/locking/rwsem.c:1631
 inode_lock include/linux/fs.h:1025 [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+0x40c/0x620 fs/namei.c:5410
 filename_mkdirat+0x285/0x510 fs/namei.c:5443
 __do_sys_mkdirat fs/namei.c:5464 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x510 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fab32b9e0d9
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:00007fab33a4c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fab32e25fa0 RCX: 00007fab32b9e0d9
RDX: 00000000000001ff RSI: 0000200000000740 RDI: ffffffffffffff9c
RBP: 00007fab32c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fab32e26038 R14: 00007fab32e25fa0 R15: 00007ffc8f9e7e98
 </TASK>