======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.9.4899/21821 is trying to acquire lock:
ffffffff8f5b35d0 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: configfs_rmdir+0x642/0x9a0

but task is already holding lock:
ffff8881bb14b798 (&sb->s_type->i_mutex_key#36){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6a0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sb->s_type->i_mutex_key#36){++++}-{4:4}:
       down_write+0x96/0x200
       configfs_depend_item_unlocked+0x153/0x410
       usbg_make_tpg+0x1f6/0x590
       target_fabric_make_tpg+0xa8/0x6d0
       configfs_mkdir+0x51c/0xa10
       vfs_mkdir+0x406/0x620
       filename_mkdirat+0x285/0x510
       __se_sys_mkdir+0x34/0x150
       do_syscall_64+0x170/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&opts->dep_lock){+.+.}-{4:4}:
       __mutex_lock+0x199/0x12d0
       tcm_set_name+0x2b/0xd0
       function_make+0x1a8/0x360
       configfs_mkdir+0x51c/0xa10
       vfs_mkdir+0x406/0x620
       filename_mkdirat+0x285/0x510
       __se_sys_mkdir+0x34/0x150
       do_syscall_64+0x170/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}:
       __lock_acquire+0x1520/0x2cd0
       lock_acquire+0xf0/0x2e0
       __mutex_lock+0x199/0x12d0
       configfs_rmdir+0x642/0x9a0
       vfs_rmdir+0x3e6/0x6a0
       filename_rmdir+0x292/0x520
       __se_sys_rmdir+0x2e/0x140
       do_syscall_64+0x170/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  gadget_subsys.su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#36

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sb->s_type->i_mutex_key#36);
                               lock(&opts->dep_lock);
                               lock(&sb->s_type->i_mutex_key#36);
  lock(gadget_subsys.su_mutex);

 *** DEADLOCK ***

3 locks held by syz.9.4899/21821:
 #0: ffff8881699d8420 (sb_writers#18){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff8881bfb13798 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: filename_rmdir+0x1cd/0x520
 #2: ffff8881bb14b798 (&sb->s_type->i_mutex_key#36){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6a0

stack backtrace:
CPU: 1 UID: 0 PID: 21821 Comm: syz.9.4899 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x1520/0x2cd0
 lock_acquire+0xf0/0x2e0
 __mutex_lock+0x199/0x12d0
 configfs_rmdir+0x642/0x9a0
 vfs_rmdir+0x3e6/0x6a0
 filename_rmdir+0x292/0x520
 __se_sys_rmdir+0x2e/0x140
 do_syscall_64+0x170/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f141e79e019
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:00007f141f6ec028 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f141ea25fa0 RCX: 00007f141e79e019
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000440
RBP: 00007f141e83500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f141ea26038 R14: 00007f141ea25fa0 R15: 00007ffd31e1d498
 </TASK>
Cannot find del_set index 2 as target
