====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.580/8102 is trying to acquire lock: ffffffff8ddf43f0 (gadget_subsys.su_mutex){+.+.}-{3:3}, at: uvcg_streaming_header_allow_link+0x71/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:1747 but task is already holding lock: ffff888079e3a9e0 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline] ffff888079e3a9e0 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: configfs_symlink+0x47a/0xfe0 fs/configfs/symlink.c:192 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}: down_write+0x97/0x200 kernel/locking/rwsem.c:1573 inode_lock include/linux/fs.h:804 [inline] configfs_depend_item_unlocked+0x157/0x430 fs/configfs/dir.c:1255 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:1360 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168 do_mkdirat+0x1dc/0x450 fs/namei.c:4191 __do_sys_mkdir fs/namei.c:4211 [inline] __se_sys_mkdir fs/namei.c:4209 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4209 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 -> #2 (tpg_instances_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 tcm_alloc_inst+0x65/0x190 drivers/usb/gadget/function/f_tcm.c:2335 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xdd/0x2e0 drivers/usb/gadget/functions.c:44 function_make+0x11c/0x350 drivers/usb/gadget/configfs.c:625 configfs_mkdir+0x515/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168 do_mkdirat+0x1dc/0x450 fs/namei.c:4191 __do_sys_mkdir fs/namei.c:4211 [inline] __se_sys_mkdir fs/namei.c:4209 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4209 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 (func_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 try_get_usb_function_instance drivers/usb/gadget/functions.c:18 [inline] usb_get_function_instance+0x2e/0x2e0 drivers/usb/gadget/functions.c:44 function_make+0x11c/0x350 drivers/usb/gadget/configfs.c:625 configfs_mkdir+0x515/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168 do_mkdirat+0x1dc/0x450 fs/namei.c:4191 __do_sys_mkdir fs/namei.c:4211 [inline] __se_sys_mkdir fs/namei.c:4209 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4209 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 (gadget_subsys.su_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5756 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 uvcg_streaming_header_allow_link+0x71/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:1747 configfs_symlink+0x5a5/0xfe0 fs/configfs/symlink.c:202 vfs_symlink+0x138/0x2b0 fs/namei.c:4528 do_symlinkat+0x1ba/0x400 fs/namei.c:4554 __do_sys_symlinkat fs/namei.c:4570 [inline] __se_sys_symlinkat fs/namei.c:4567 [inline] __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4567 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: gadget_subsys.su_mutex --> tpg_instances_lock --> &sb->s_type->i_mutex_key#23 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#23); lock(tpg_instances_lock); lock(&sb->s_type->i_mutex_key#23); lock(gadget_subsys.su_mutex); *** DEADLOCK *** 2 locks held by syz.1.580/8102: #0: ffff888017d66418 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412 #1: ffff888079e3a9e0 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline] #1: ffff888079e3a9e0 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: configfs_symlink+0x47a/0xfe0 fs/configfs/symlink.c:192 stack backtrace: CPU: 0 PID: 8102 Comm: syz.1.580 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5756 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 uvcg_streaming_header_allow_link+0x71/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:1747 configfs_symlink+0x5a5/0xfe0 fs/configfs/symlink.c:202 vfs_symlink+0x138/0x2b0 fs/namei.c:4528 do_symlinkat+0x1ba/0x400 fs/namei.c:4554 __do_sys_symlinkat fs/namei.c:4570 [inline] __se_sys_symlinkat fs/namei.c:4567 [inline] __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4567 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: 0033:0x7fca9519e159 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:00007fca96105028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a RAX: ffffffffffffffda RBX: 00007fca95425fa0 RCX: 00007fca9519e159 RDX: 0000200000001600 RSI: ffffffffffffff9c RDI: 0000200000001500 RBP: 00007fca9523503b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fca95426038 R14: 00007fca95425fa0 R15: 00007fffcc5d7298