======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.18/4317 is trying to acquire lock:
ffffffff8cc23e70 (&subsys->su_mutex){+.+.}-{3:3}, at: configfs_rmdir+0x638/0x980 fs/configfs/dir.c:1556

but task is already holding lock:
ffff88805ca89590 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff88805ca89590 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: vfs_rmdir+0xe1/0x410 fs/namei.c:4147

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}:
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       inode_lock include/linux/fs.h:787 [inline]
       configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255
       usbg_make_tpg+0x1f3/0x580 drivers/usb/gadget/function/f_tcm.c:1351
       target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:837
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4073
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       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 (&opts->dep_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
       usbg_make_tpg+0x144/0x580 drivers/usb/gadget/function/f_tcm.c:1343
       target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:837
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4073
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       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 (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
       usbg_make_tpg+0xf4/0x580 drivers/usb/gadget/function/f_tcm.c:1334
       target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:837
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4073
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       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 (&subsys->su_mutex){+.+.}-{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
       configfs_rmdir+0x638/0x980 fs/configfs/dir.c:1556
       vfs_rmdir+0x19d/0x410 fs/namei.c:4157
       do_rmdir+0x27f/0x710 fs/namei.c:4218
       __do_sys_rmdir fs/namei.c:4237 [inline]
       __se_sys_rmdir fs/namei.c:4235 [inline]
       __x64_sys_rmdir+0x45/0x50 fs/namei.c:4235
       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:
  &subsys->su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#21

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sb->s_type->i_mutex_key#21);
                               lock(&opts->dep_lock);
                               lock(&sb->s_type->i_mutex_key#21);
  lock(&subsys->su_mutex);

 *** DEADLOCK ***

3 locks held by syz.0.18/4317:
 #0: ffff88801d64a460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88814674d080 (&default_group_class[depth - 1]#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
 #1: ffff88814674d080 (&default_group_class[depth - 1]#7/1){+.+.}-{3:3}, at: do_rmdir+0x1b0/0x710 fs/namei.c:4205
 #2: ffff88805ca89590 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #2: ffff88805ca89590 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: vfs_rmdir+0xe1/0x410 fs/namei.c:4147

stack backtrace:
CPU: 0 PID: 4317 Comm: syz.0.18 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
 configfs_rmdir+0x638/0x980 fs/configfs/dir.c:1556
 vfs_rmdir+0x19d/0x410 fs/namei.c:4157
 do_rmdir+0x27f/0x710 fs/namei.c:4218
 __do_sys_rmdir fs/namei.c:4237 [inline]
 __se_sys_rmdir fs/namei.c:4235 [inline]
 __x64_sys_rmdir+0x45/0x50 fs/namei.c:4235
 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: 0033:0x7f145ef950d9
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:00007fffceb828b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f145f21cfa0 RCX: 00007f145ef950d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000001640
RBP: 00007f145f02c024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f145f21cfac R14: 00007f145f21cfa0 R15: 00007f145f21cfa0
 </TASK>