======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.3.1310/10935 is trying to acquire lock:
ffff8880248e5dc0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
ffff8880248e5dc0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: configfs_depend_item_unlocked+0xf3/0x6a0 fs/configfs/dir.c:1268

but task is already holding lock:
ffffffff90480000 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x10b/0x610 drivers/usb/gadget/function/f_tcm.c:1669

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (tpg_instances_lock){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       usbg_make_tpg+0x10b/0x610 drivers/usb/gadget/function/f_tcm.c:1669
       target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:947
       configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369
       vfs_mkdir+0x364/0x850 fs/namei.c:5410
       filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443
       __do_sys_mkdirat fs/namei.c:5464 [inline]
       __se_sys_mkdirat fs/namei.c:5461 [inline]
       __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5461
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&subsys->su_mutex){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       configfs_rmdir+0x5ae/0x950 fs/configfs/dir.c:1565
       vfs_rmdir fs/namei.c:5515 [inline]
       vfs_rmdir+0x328/0x8a0 fs/namei.c:5488
       filename_rmdir+0x31a/0x5c0 fs/namei.c:5572
       __do_sys_rmdir fs/namei.c:5595 [inline]
       __se_sys_rmdir fs/namei.c:5592 [inline]
       __x64_sys_rmdir+0x46/0x70 fs/namei.c:5592
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
       check_prevs_add kernel/locking/lockdep.c:3328 [inline]
       validate_chain kernel/locking/lockdep.c:3952 [inline]
       __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
       inode_lock include/linux/fs.h:1024 [inline]
       configfs_depend_item_unlocked+0xf3/0x6a0 fs/configfs/dir.c:1268
       usbg_make_tpg+0x251/0x610 drivers/usb/gadget/function/f_tcm.c:1692
       target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:947
       configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369
       vfs_mkdir+0x364/0x850 fs/namei.c:5410
       filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443
       __do_sys_mkdirat fs/namei.c:5464 [inline]
       __se_sys_mkdirat fs/namei.c:5461 [inline]
       __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5461
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 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#25 --> &subsys->su_mutex --> tpg_instances_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tpg_instances_lock);
                               lock(&subsys->su_mutex);
                               lock(tpg_instances_lock);
  lock(&sb->s_type->i_mutex_key#25);

 *** DEADLOCK ***

locks held by syz.3.1310/10935: 4, last CPU#1:
 #0: ffff88801e7ec460 (sb_writers#15){.+.+}-{0:0}, at: filename_create+0x10d/0x400 fs/namei.c:5085
 #1: ffff888079165900 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
 #1: ffff888079165900 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
 #1: ffff888079165900 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
 #1: ffff888079165900 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: filename_create+0x1c0/0x400 fs/namei.c:5092
 #2: ffffffff8ffb2e68 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_mkdir+0x4c0/0xd40 fs/configfs/dir.c:1367
 #3: ffffffff90480000 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x10b/0x610 drivers/usb/gadget/function/f_tcm.c:1669

stack backtrace:
CPU: 1 UID: 0 PID: 10935 Comm: syz.3.1310 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
 check_prevs_add kernel/locking/lockdep.c:3328 [inline]
 validate_chain kernel/locking/lockdep.c:3952 [inline]
 __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
 lock_acquire kernel/locking/lockdep.c:5942 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
 inode_lock include/linux/fs.h:1024 [inline]
 configfs_depend_item_unlocked+0xf3/0x6a0 fs/configfs/dir.c:1268
 usbg_make_tpg+0x251/0x610 drivers/usb/gadget/function/f_tcm.c:1692
 target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:947
 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369
 vfs_mkdir+0x364/0x850 fs/namei.c:5410
 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443
 __do_sys_mkdirat fs/namei.c:5464 [inline]
 __se_sys_mkdirat fs/namei.c:5461 [inline]
 __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5461
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f411ab9e159
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:00007f411ba51028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f411ae26270 RCX: 00007f411ab9e159
RDX: 00000000000001ff RSI: 0000200000000380 RDI: ffffffffffffff9c
RBP: 00007f411ac3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f411ae26308 R14: 00007f411ae26270 R15: 00007fffd3b10758
 </TASK>