====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.315/6871 is trying to acquire lock: ffff8880238c5dc0 (&sb->s_type->i_mutex_key#36){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff8880238c5dc0 (&sb->s_type->i_mutex_key#36){++++}-{4:4}, at: configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1268 but task is already holding lock: ffffffff8fc6f9e0 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0xf8/0x550 drivers/usb/gadget/function/f_tcm.c:1669 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (tpg_instances_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 tcm_alloc+0x21/0x2e0 drivers/usb/gadget/function/f_tcm.c:2734 usb_get_function+0x63/0xb0 drivers/usb/gadget/functions.c:61 config_usb_cfg_link+0x148/0x260 drivers/usb/gadget/configfs.c:469 configfs_symlink+0x74e/0x11d0 fs/configfs/symlink.c:211 vfs_symlink+0x18b/0x330 fs/namei.c:5794 filename_symlinkat+0x1cd/0x410 fs/namei.c:5819 __do_sys_symlinkat fs/namei.c:5839 [inline] __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5834 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 (&gi->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 config_usb_cfg_link+0x59/0x260 drivers/usb/gadget/configfs.c:439 configfs_symlink+0x74e/0x11d0 fs/configfs/symlink.c:211 vfs_symlink+0x18b/0x330 fs/namei.c:5794 filename_symlinkat+0x1cd/0x410 fs/namei.c:5819 __do_sys_symlinkat fs/namei.c:5839 [inline] __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5834 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 (&sb->s_type->i_mutex_key#36){++++}-{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 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: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+0x40c/0x620 fs/namei.c:5410 filename_mkdirat+0x285/0x510 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 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#36 --> &gi->lock --> tpg_instances_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tpg_instances_lock); lock(&gi->lock); lock(tpg_instances_lock); lock(&sb->s_type->i_mutex_key#36); *** DEADLOCK *** locks held by syz.4.315/6871: 4, last CPU#0: #0: ffff88801d3fc460 (sb_writers#23){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494 #1: ffff888050d3c600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline] #1: ffff888050d3c600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline] #1: ffff888050d3c600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline] #1: ffff888050d3c600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: filename_create+0x200/0x370 fs/namei.c:5092 #2: ffffffff8f93a168 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_mkdir+0x4b0/0x9e0 fs/configfs/dir.c:1367 #3: ffffffff8fc6f9e0 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0xf8/0x550 drivers/usb/gadget/function/f_tcm.c:1669 stack backtrace: CPU: 0 UID: 0 PID: 6871 Comm: syz.4.315 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 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 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: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+0x40c/0x620 fs/namei.c:5410 filename_mkdirat+0x285/0x510 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 RIP: 0033:0x7f1ac039e159 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:00007f1ac1240028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007f1ac0625fa0 RCX: 00007f1ac039e159 RDX: 00000000000001ff RSI: 00002000000003c0 RDI: ffffffffffffff9c RBP: 00007f1ac043506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1ac0626038 R14: 00007f1ac0625fa0 R15: 00007ffdb41b84a8