======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor182/5934 is trying to acquire lock:
ffff88801cf5bb70
 (&p->frag_sem){++++}-{4:4}
, at: configfs_rmdir+0x3fa/0x950 fs/configfs/dir.c:1534

but task is already holding lock:
ffff8880700fb580 (
&sb->s_type->i_mutex_key#24){++++}-{4:4}
, at: inode_lock include/linux/fs.h:1024 [inline]
, at: vfs_rmdir fs/namei.c:5366 [inline]
, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5354

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sb->s_type->i_mutex_key#24){++++}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       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:1259
       usbg_make_tpg+0x261/0x620 drivers/usb/gadget/function/f_tcm.c:1686
       target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:939
       configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360
       vfs_mkdir+0x361/0x850 fs/namei.c:5276
       filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
       __do_sys_mkdir fs/namei.c:5336 [inline]
       __se_sys_mkdir fs/namei.c:5333 [inline]
       __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5333
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&opts->dep_lock){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       tcm_register_callback+0x1f/0x70 drivers/usb/gadget/function/f_tcm.c:2625
       usbg_attach drivers/usb/gadget/function/f_tcm.c:2649 [inline]
       usbg_enable_tpg+0x95/0x160 drivers/usb/gadget/function/f_tcm.c:1825
       target_tpg_enable+0x1fc/0x5d0 drivers/target/target_core_tpg.c:481
       target_fabric_tpg_base_enable_store+0x162/0x190 drivers/target/target_core_fabric_configfs.c:840
       flush_write_buffer fs/configfs/file.c:207 [inline]
       configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x6ac/0x1050 fs/read_write.c:687
       ksys_write+0x12a/0x250 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&p->frag_sem){++++}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       down_write_killable+0x93/0x250 kernel/locking/rwsem.c:1643
       configfs_rmdir+0x3fa/0x950 fs/configfs/dir.c:1534
       vfs_rmdir fs/namei.c:5381 [inline]
       vfs_rmdir+0x328/0x8a0 fs/namei.c:5354
       filename_rmdir+0x31a/0x5c0 fs/namei.c:5438
       __do_sys_rmdir fs/namei.c:5461 [inline]
       __se_sys_rmdir fs/namei.c:5458 [inline]
       __x64_sys_rmdir+0x46/0x70 fs/namei.c:5458
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 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:
  &p->frag_sem --> &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(&p->frag_sem);

 *** DEADLOCK ***

3 locks held by syz-executor182/5934:
 #0: ffff88801bd96450 (sb_writers#13){.+.+}-{0:0}, at: filename_rmdir+0x1ff/0x5c0 fs/namei.c:5427
 #1: ffff8880700f8f80 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
 #1: ffff8880700f8f80 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
 #1: ffff8880700f8f80 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
 #1: ffff8880700f8f80 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: filename_rmdir+0x258/0x5c0 fs/namei.c:5431
 #2: ffff8880700fb580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #2: ffff8880700fb580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: vfs_rmdir fs/namei.c:5366 [inline]
 #2: ffff8880700fb580 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5354

stack backtrace:
CPU: 1 UID: 0 PID: 5934 Comm: syz-executor182 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
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+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
 down_write_killable+0x93/0x250 kernel/locking/rwsem.c:1643
 configfs_rmdir+0x3fa/0x950 fs/configfs/dir.c:1534
 vfs_rmdir fs/namei.c:5381 [inline]
 vfs_rmdir+0x328/0x8a0 fs/namei.c:5354
 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438
 __do_sys_rmdir fs/namei.c:5461 [inline]
 __se_sys_rmdir fs/namei.c:5458 [inline]
 __x64_sys_rmdir+0x46/0x70 fs/namei.c:5458
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f07207bee27
Code: 00 00 90 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 00 31 c9 e8 ba 05 02 00 48 83 c4 18 c3 0f 1f 44 00 00 b8 54 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe76edc838 EFLAGS: 00000202 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f072081a2e0 RCX: 00007f07207bee27
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f072081a438
RBP: 00007f072081a308 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f072081a3f8
R13: 00007f072081a438 R14: 00007f0720842cc0 R15: 0000000000000002
 </TASK>