======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.2129/12452 is trying to acquire lock:
ffffffff8eb20570 (&subsys->su_mutex){+.+.}-{3:3}, at: configfs_rmdir+0x63c/0x980 fs/configfs/dir.c:1561

but task is already holding lock:
ffff88807f96b910 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
ffff88807f96b910 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: vfs_rmdir+0xee/0x4b0 fs/namei.c:4252

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sb->s_type->i_mutex_key#21){++++}-{3:3}
:
       down_write+0x97/0x200 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:804 [inline]
       configfs_depend_item_unlocked+0x157/0x460 fs/configfs/dir.c:1260
       usbg_make_tpg+0x1e1/0x550 drivers/usb/gadget/function/f_tcm.c:1347
       target_fabric_make_tpg+0xa4/0x6d0 drivers/target/target_core_fabric_configfs.c:947
       configfs_mkdir+0x515/0x9e0 fs/configfs/dir.c:1365
       vfs_mkdir+0x2a5/0x470 fs/namei.c:4180
       do_mkdirat+0x1dc/0x450 fs/namei.c:4203
       __do_sys_mkdirat fs/namei.c:4218 [inline]
       __se_sys_mkdirat fs/namei.c:4216 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4216
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (tpg_instances_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xce0 kernel/locking/mutex.c:747
       usbg_make_tpg+0xf9/0x550 drivers/usb/gadget/function/f_tcm.c:1324
       target_fabric_make_tpg+0xa4/0x6d0 drivers/target/target_core_fabric_configfs.c:947
       configfs_mkdir+0x515/0x9e0 fs/configfs/dir.c:1365
       vfs_mkdir+0x2a5/0x470 fs/namei.c:4180
       do_mkdirat+0x1dc/0x450 fs/namei.c:4203
       __do_sys_mkdirat fs/namei.c:4218 [inline]
       __se_sys_mkdirat fs/namei.c:4216 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4216
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&subsys->su_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3162 [inline]
       check_prevs_add kernel/locking/lockdep.c:3281 [inline]
       validate_chain kernel/locking/lockdep.c:3897 [inline]
       __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xce0 kernel/locking/mutex.c:747
       configfs_rmdir+0x63c/0x980 fs/configfs/dir.c:1561
       vfs_rmdir+0x352/0x4b0 fs/namei.c:4263
       do_rmdir+0x29f/0x590 fs/namei.c:4322
       __do_sys_rmdir fs/namei.c:4341 [inline]
       __se_sys_rmdir fs/namei.c:4339 [inline]
       __x64_sys_rmdir+0x49/0x50 fs/namei.c:4339
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.0.2129/12452:
 #0: ffff888141a96418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff8880213fc160 (&default_group_class[depth - 1]#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
 #1: ffff8880213fc160 (&default_group_class[depth - 1]#7/1){+.+.}-{3:3}, at: do_rmdir+0x1c6/0x590 fs/namei.c:4310
 #2: ffff88807f96b910 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff88807f96b910 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: vfs_rmdir+0xee/0x4b0 fs/namei.c:4252

stack backtrace:
CPU: 0 PID: 12452 Comm: syz.0.2129 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2215
 check_prev_add kernel/locking/lockdep.c:3162 [inline]
 check_prevs_add kernel/locking/lockdep.c:3281 [inline]
 validate_chain kernel/locking/lockdep.c:3897 [inline]
 __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x135/0xce0 kernel/locking/mutex.c:747
 configfs_rmdir+0x63c/0x980 fs/configfs/dir.c:1561
 vfs_rmdir+0x352/0x4b0 fs/namei.c:4263
 do_rmdir+0x29f/0x590 fs/namei.c:4322
 __do_sys_rmdir fs/namei.c:4341 [inline]
 __se_sys_rmdir fs/namei.c:4339 [inline]
 __x64_sys_rmdir+0x49/0x50 fs/namei.c:4339
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0d3899fb19
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:00007f0d3636e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f0d38c26360 RCX: 00007f0d3899fb19
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000280
RBP: 00007f0d38a37b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0d38c263f8 R14: 00007f0d38c26360 R15: 00007ffe693f47f8
 </TASK>
config_item rd_mcp_0: cleaning up
CORE_HBA[1] - Detached Ramdisk HBA: 0 from Generic Target Core
CORE_HBA[1] - Detached HBA from Generic Target Core
kcov: kcov_task_exit: t = ffff888024cebc00, kcov->t = ffff888024cebc00