====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.7.2193/18424 is trying to acquire lock: ffffffff8f9f0ba8 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_streaming_header_allow_link+0x75/0x4d0 drivers/usb/gadget/function/uvc_configfs.c:1750 but task is already holding lock: ffff88803501d440 (&sb->s_type->i_mutex_key#27){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff88803501d440 (&sb->s_type->i_mutex_key#27){++++}-{4:4}, at: configfs_symlink+0x3af/0x1030 fs/configfs/symlink.c:186 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#27){++++}-{4:4}: 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:1259 usbg_make_tpg+0x1f6/0x590 drivers/usb/gadget/function/f_tcm.c:1686 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:939 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x406/0x620 fs/namei.c:5276 filename_mkdirat+0x285/0x510 fs/namei.c:5309 __do_sys_mkdir fs/namei.c:5336 [inline] __se_sys_mkdir+0x34/0x150 fs/namei.c:5333 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&opts->dep_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 tcm_set_name+0x2b/0xd0 drivers/usb/gadget/function/f_tcm.c:2540 function_make+0x1a8/0x360 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x406/0x620 fs/namei.c:5276 filename_mkdirat+0x285/0x510 fs/namei.c:5309 __do_sys_mkdir fs/namei.c:5336 [inline] __se_sys_mkdir+0x34/0x150 fs/namei.c:5333 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_streaming_header_allow_link+0x75/0x4d0 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196 vfs_symlink+0x18b/0x330 fs/namei.c:5660 filename_symlinkat+0x1cd/0x410 fs/namei.c:5685 __do_sys_symlink fs/namei.c:5712 [inline] __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5708 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 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: gadget_subsys.su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#27 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#27); lock(&opts->dep_lock); lock(&sb->s_type->i_mutex_key#27); lock(gadget_subsys.su_mutex); *** DEADLOCK *** 2 locks held by syz.7.2193/18424: #0: ffff88801db70450 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494 #1: ffff88803501d440 (&sb->s_type->i_mutex_key#27){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff88803501d440 (&sb->s_type->i_mutex_key#27){++++}-{4:4}, at: configfs_symlink+0x3af/0x1030 fs/configfs/symlink.c:186 stack backtrace: CPU: 1 UID: 0 PID: 18424 Comm: syz.7.2193 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_streaming_header_allow_link+0x75/0x4d0 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196 vfs_symlink+0x18b/0x330 fs/namei.c:5660 filename_symlinkat+0x1cd/0x410 fs/namei.c:5685 __do_sys_symlink fs/namei.c:5712 [inline] __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5708 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe99239de99 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:00007fe993264028 EFLAGS: 00000246 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 00007fe992625fa0 RCX: 00007fe99239de99 RDX: 0000000000000000 RSI: 0000200000001500 RDI: 0000200000001400 RBP: 00007fe992433eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe992626038 R14: 00007fe992625fa0 R15: 00007ffd94f16148