======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.0/5316 is trying to acquire lock:
ffffffff8f7173e8 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1556

but task is already holding lock:
ffff8880123ab580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
ffff8880123ab580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6a0 fs/namei.c:5366

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&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_mkdir fs/namei.c:5336 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5333
       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 (&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_mkdir fs/namei.c:5336 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5333
       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 (tpg_instances_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       usbg_make_tpg+0xf7/0x590 drivers/usb/gadget/function/f_tcm.c:1669
       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_mkdir fs/namei.c:5336 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5333
       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 (&subsys->su_mutex){+.+.}-{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
       configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1556
       vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5381
       filename_rmdir+0x292/0x520 fs/namei.c:5438
       __do_sys_rmdir fs/namei.c:5461 [inline]
       __se_sys_rmdir+0x2e/0x140 fs/namei.c:5458
       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:
  &subsys->su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#24

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sb->s_type->i_mutex_key#24);
                               lock(&opts->dep_lock);
                               lock(&sb->s_type->i_mutex_key#24);
  lock(&subsys->su_mutex);

 *** DEADLOCK ***

3 locks held by syz.0.0/5316:
 #0: ffff888000bbe450 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff8880416d7a40 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
 #1: ffff8880416d7a40 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
 #1: ffff8880416d7a40 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
 #1: ffff8880416d7a40 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: filename_rmdir+0x1cd/0x520 fs/namei.c:5431
 #2: ffff8880123ab580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #2: ffff8880123ab580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6a0 fs/namei.c:5366

stack backtrace:
CPU: 0 UID: 0 PID: 5316 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
 configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1556
 vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5381
 filename_rmdir+0x292/0x520 fs/namei.c:5438
 __do_sys_rmdir fs/namei.c:5461 [inline]
 __se_sys_rmdir+0x2e/0x140 fs/namei.c:5458
 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: 0033:0x7efd5659e0d9
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:00007efd5752afe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007efd56826090 RCX: 00007efd5659e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000340
RBP: 00007efd56635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efd56826128 R14: 00007efd56826090 R15: 00007ffc7c7e0c78
 </TASK>