======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.18/4323 is trying to acquire lock:
ffff888145f10660 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
ffff888145f10660 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255

but task is already holding lock:
ffffffff8cf20cc8 (tpg_instances_lock){+.+.}-{3:3}, at: usbg_make_tpg+0xf5/0x550 drivers/usb/gadget/function/f_tcm.c:1334

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (tpg_instances_lock){+.+.}-{3:3}:
       __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
       tcm_alloc_inst+0x61/0x190 drivers/usb/gadget/function/f_tcm.c:2371
       try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
       usb_get_function_instance+0xd9/0x2e0 drivers/usb/gadget/functions.c:44
       function_make+0x118/0x350 drivers/usb/gadget/configfs.c:610
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4116
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
       __do_sys_mkdirat fs/namei.c:4156 [inline]
       __se_sys_mkdirat fs/namei.c:4154 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4154
       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

-> #2 (func_lock){+.+.}-{3:3}:
       __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
       try_get_usb_function_instance drivers/usb/gadget/functions.c:18 [inline]
       usb_get_function_instance+0x2a/0x2e0 drivers/usb/gadget/functions.c:44
       function_make+0x118/0x350 drivers/usb/gadget/configfs.c:610
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4116
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
       __do_sys_mkdir fs/namei.c:4161 [inline]
       __se_sys_mkdir fs/namei.c:4159 [inline]
       __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4159
       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

-> #1 (gadget_subsys.su_mutex){+.+.}-{3:3}:
       __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
       uvcg_streaming_header_allow_link+0x6d/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:942
       configfs_symlink+0x5a4/0x13b0 fs/configfs/symlink.c:202
       vfs_symlink+0x245/0x3d0 fs/namei.c:4480
       do_symlinkat+0x1ab/0x6b0 fs/namei.c:4509
       __do_sys_symlink fs/namei.c:4531 [inline]
       __se_sys_symlink fs/namei.c:4529 [inline]
       __x64_sys_symlink+0x7a/0x90 fs/namei.c:4529
       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

-> #0 (&sb->s_type->i_mutex_key#21){+.+.}-{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:5625
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       inode_lock include/linux/fs.h:793 [inline]
       configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255
       usbg_make_tpg+0x1dd/0x550 drivers/usb/gadget/function/f_tcm.c:1357
       target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:845
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4116
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
       __do_sys_mkdirat fs/namei.c:4156 [inline]
       __se_sys_mkdirat fs/namei.c:4154 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4154
       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:

Chain exists of:
  &sb->s_type->i_mutex_key#21 --> func_lock --> tpg_instances_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tpg_instances_lock);
                               lock(func_lock);
                               lock(tpg_instances_lock);
  lock(&sb->s_type->i_mutex_key#21);

 *** DEADLOCK ***

4 locks held by syz.0.18/4323:
 #0: ffff888140dcc460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff888067b15590 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:828 [inline]
 #1: ffff888067b15590 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3886
 #2: ffffffff8cc24710 (&subsys->su_mutex){+.+.}-{3:3}, at: configfs_mkdir+0x4b5/0x9e0 fs/configfs/dir.c:1358
 #3: ffffffff8cf20cc8 (tpg_instances_lock){+.+.}-{3:3}, at: usbg_make_tpg+0xf5/0x550 drivers/usb/gadget/function/f_tcm.c:1334

stack backtrace:
CPU: 1 PID: 4323 Comm: syz.0.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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:5625
 down_write+0x38/0x60 kernel/locking/rwsem.c:1551
 inode_lock include/linux/fs.h:793 [inline]
 configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255
 usbg_make_tpg+0x1dd/0x550 drivers/usb/gadget/function/f_tcm.c:1357
 target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:845
 configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
 vfs_mkdir+0x386/0x570 fs/namei.c:4116
 do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
 __do_sys_mkdirat fs/namei.c:4156 [inline]
 __se_sys_mkdirat fs/namei.c:4154 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4154
 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: 0033:0x7f3b192d6159
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:00007ffd71298dc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f3b1955dfa0 RCX: 00007f3b192d6159
RDX: 00000000000001ff RSI: 0000200000000380 RDI: ffffffffffffff9c
RBP: 00007f3b1936d06b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3b1955dfac R14: 00007f3b1955dfa0 R15: 00007f3b1955dfa0
 </TASK>