db_root: cannot be changed because it's in use ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.254/5370 is trying to acquire lock: ffff888148c264c0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline] ffff888148c264c0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255 but task is already holding lock: ffff88807d8af120 (&opts->dep_lock){+.+.}-{3:3}, at: usbg_make_tpg+0x144/0x580 drivers/usb/gadget/function/f_tcm.c:1357 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&opts->dep_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 tcm_bind+0x98/0x3f0 drivers/usb/gadget/function/f_tcm.c:1978 usb_add_function+0x2d9/0x980 drivers/usb/gadget/composite.c:337 configfs_composite_bind+0xa02/0xf60 drivers/usb/gadget/configfs.c:1409 gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x24a/0xb40 drivers/base/dd.c:638 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804 driver_probe_device+0x4f/0x420 drivers/base/dd.c:834 __driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220 bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303 bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620 driver_register+0x32d/0x430 drivers/base/driver.c:246 usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730 gadget_dev_desc_UDC_store+0x1c3/0x2e0 drivers/usb/gadget/configfs.c:290 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229 call_write_iter include/linux/fs.h:2265 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x482/0x9a0 fs/read_write.c:584 ksys_write+0x14d/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (&gi->lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 config_usb_cfg_link+0x55/0x250 drivers/usb/gadget/configfs.c:429 configfs_symlink+0x5a4/0x13c0 fs/configfs/symlink.c:202 vfs_symlink+0x245/0x3d0 fs/namei.c:4479 do_symlinkat+0x1b6/0x400 fs/namei.c:4508 __do_sys_symlink fs/namei.c:4530 [inline] __se_sys_symlink fs/namei.c:4528 [inline] __x64_sys_symlink+0x7a/0x90 fs/namei.c:4528 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 down_write+0x36/0x60 kernel/locking/rwsem.c:1573 inode_lock include/linux/fs.h:758 [inline] configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255 usbg_make_tpg+0x1f3/0x580 drivers/usb/gadget/function/f_tcm.c:1365 target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:905 configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x386/0x570 fs/namei.c:4114 do_mkdirat+0x1d8/0x440 fs/namei.c:4139 __do_sys_mkdir fs/namei.c:4159 [inline] __se_sys_mkdir fs/namei.c:4157 [inline] __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4157 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#21 --> &gi->lock --> &opts->dep_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&opts->dep_lock); lock(&gi->lock); lock(&opts->dep_lock); lock(&sb->s_type->i_mutex_key#21); *** DEADLOCK *** 5 locks held by syz.4.254/5370: #0: ffff888145aca460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402 #1: ffff8880781e4150 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline] #1: ffff8880781e4150 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3884 #2: ffffffff8d4e96b0 (&subsys->su_mutex){+.+.}-{3:3}, at: configfs_mkdir+0x4b5/0x9e0 fs/configfs/dir.c:1358 #3: ffffffff8d8089e8 (tpg_instances_lock){+.+.}-{3:3}, at: usbg_make_tpg+0xf4/0x580 drivers/usb/gadget/function/f_tcm.c:1348 #4: ffff88807d8af120 (&opts->dep_lock){+.+.}-{3:3}, at: usbg_make_tpg+0x144/0x580 drivers/usb/gadget/function/f_tcm.c:1357 stack backtrace: CPU: 1 PID: 5370 Comm: syz.4.254 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 down_write+0x36/0x60 kernel/locking/rwsem.c:1573 inode_lock include/linux/fs.h:758 [inline] configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255 usbg_make_tpg+0x1f3/0x580 drivers/usb/gadget/function/f_tcm.c:1365 target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:905 configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x386/0x570 fs/namei.c:4114 do_mkdirat+0x1d8/0x440 fs/namei.c:4139 __do_sys_mkdir fs/namei.c:4159 [inline] __se_sys_mkdir fs/namei.c:4157 [inline] __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4157 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb0c3b9e019 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:00007fb0c49b1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 00007fb0c3e25fa0 RCX: 00007fb0c3b9e019 RDX: 0000000000000000 RSI: 00000000000001ff RDI: 0000200000000c00 RBP: 00007fb0c3c3500c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb0c3e26038 R14: 00007fb0c3e25fa0 R15: 00007ffd7071c368 se_dev->se_dev_ptr already set for storage object