====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.25/5885 is trying to acquire lock: ffffffff8ecb4940 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1565 but task is already holding lock: ffff8880618ca750 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff8880618ca750 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6b0 fs/namei.c:5500 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#26){++++}-{4:4}: down_write+0x3a/0x50 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1268 usbg_make_tpg+0x1e0/0x550 drivers/usb/gadget/function/f_tcm.c:1692 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x408/0x620 fs/namei.c:5410 filename_mkdirat+0x289/0x520 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (tpg_instances_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580 usbg_make_tpg+0xf8/0x550 drivers/usb/gadget/function/f_tcm.c:1669 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x408/0x620 fs/namei.c:5410 filename_mkdirat+0x289/0x520 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&subsys->su_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580 configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1565 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5515 filename_rmdir+0x292/0x520 fs/namei.c:5572 __do_sys_unlinkat fs/namei.c:5747 [inline] __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5740 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &subsys->su_mutex --> tpg_instances_lock --> &sb->s_type->i_mutex_key#26 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#26); lock(tpg_instances_lock); lock(&sb->s_type->i_mutex_key#26); lock(&subsys->su_mutex); *** DEADLOCK *** locks held by syz.0.25/5885: 3, last CPU#1: #0: ffff88801d358510 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494 #1: ffff8880618cb788 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline] #1: ffff8880618cb788 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline] #1: ffff8880618cb788 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline] #1: ffff8880618cb788 (&sb->s_type->i_mutex_key#7/1){+.+.}-{4:4}, at: filename_rmdir+0x1cd/0x520 fs/namei.c:5565 #2: ffff8880618ca750 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #2: ffff8880618ca750 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: vfs_rmdir+0xf8/0x6b0 fs/namei.c:5500 stack backtrace: CPU: 1 UID: 0 PID: 5885 Comm: syz.0.25 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580 configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1565 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5515 filename_rmdir+0x292/0x520 fs/namei.c:5572 __do_sys_unlinkat fs/namei.c:5747 [inline] __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5740 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7b92a5e159 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:00007f7b90cb6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000107 RAX: ffffffffffffffda RBX: 00007f7b92ce5fa0 RCX: 00007f7b92a5e159 RDX: 0000000000000200 RSI: 00002000000002c0 RDI: ffffffffffffff9c RBP: 00007f7b92af506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7b92ce6038 R14: 00007f7b92ce5fa0 R15: 00007ffc4c2e7fd8