====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.776/7192 is trying to acquire lock: ffff0000c14cba40 (&sb->s_type->i_mutex_key#23){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff0000c14cba40 (&sb->s_type->i_mutex_key#23){++++}-{4:4}, at: configfs_depend_item_unlocked+0x154/0x344 fs/configfs/dir.c:1259 but task is already holding lock: ffff80008985d740 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x14c/0x4a0 drivers/usb/gadget/function/f_tcm.c:1669 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (tpg_instances_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 tcm_alloc_inst+0x6c/0x190 drivers/usb/gadget/function/f_tcm.c:2687 try_get_usb_function_instance+0xe4/0x164 drivers/usb/gadget/functions.c:28 usb_get_function_instance+0x24/0xb0 drivers/usb/gadget/functions.c:44 function_make+0x110/0x300 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2e4/0x46c fs/namei.c:5410 filename_mkdirat+0x228/0x3f4 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat fs/namei.c:5461 [inline] __arm64_sys_mkdirat+0x9c/0xc0 fs/namei.c:5461 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 -> #2 (func_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 try_get_usb_function_instance+0x38/0x164 drivers/usb/gadget/functions.c:18 usb_get_function_instance+0x24/0xb0 drivers/usb/gadget/functions.c:44 function_make+0x110/0x300 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2e4/0x46c fs/namei.c:5410 filename_mkdirat+0x228/0x3f4 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat fs/namei.c:5461 [inline] __arm64_sys_mkdirat+0x9c/0xc0 fs/namei.c:5461 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 -> #1 (gadget_subsys.su_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 uvcg_streaming_header_allow_link+0x7c/0x47c drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x478/0xde0 fs/configfs/symlink.c:196 vfs_symlink+0x16c/0x290 fs/namei.c:5794 filename_symlinkat+0x18c/0x328 fs/namei.c:5819 __do_sys_symlinkat fs/namei.c:5839 [inline] __se_sys_symlinkat fs/namei.c:5834 [inline] __arm64_sys_symlinkat+0xb0/0xdc fs/namei.c:5834 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 -> #0 (&sb->s_type->i_mutex_key#23){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1600/0x2a6c kernel/locking/lockdep.c:5254 lock_acquire+0x150/0x370 kernel/locking/lockdep.c:5908 down_write+0x50/0xc0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0x154/0x344 fs/configfs/dir.c:1259 usbg_make_tpg+0x218/0x4a0 drivers/usb/gadget/function/f_tcm.c:1692 target_fabric_make_tpg+0x98/0x518 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2e4/0x46c fs/namei.c:5410 filename_mkdirat+0x228/0x3f4 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat fs/namei.c:5461 [inline] __arm64_sys_mkdirat+0x9c/0xc0 fs/namei.c:5461 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#23 --> func_lock --> tpg_instances_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tpg_instances_lock); lock(func_lock); lock(tpg_instances_lock); lock(&sb->s_type->i_mutex_key#23); *** DEADLOCK *** locks held by syz.3.776/7192: 4, last CPU#0: #0: ffff0000c44da460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494 #1: ffff0000da586280 (&sb->s_type->i_mutex_key#6/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline] #1: ffff0000da586280 (&sb->s_type->i_mutex_key#6/1){+.+.}-{4:4}, at: __start_dirop+0xa0/0xf4 fs/namei.c:2918 #2: ffff800089561608 (&subsys->su_mutex){+.+.}-{4:4}, at: configfs_mkdir+0x334/0x7d4 fs/configfs/dir.c:1358 #3: ffff80008985d740 (tpg_instances_lock){+.+.}-{4:4}, at: usbg_make_tpg+0x14c/0x4a0 drivers/usb/gadget/function/f_tcm.c:1669 stack backtrace: CPU: 0 UID: 0 PID: 7192 Comm: syz.3.776 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2059 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2191 check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1600/0x2a6c kernel/locking/lockdep.c:5254 lock_acquire+0x150/0x370 kernel/locking/lockdep.c:5908 down_write+0x50/0xc0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0x154/0x344 fs/configfs/dir.c:1259 usbg_make_tpg+0x218/0x4a0 drivers/usb/gadget/function/f_tcm.c:1692 target_fabric_make_tpg+0x98/0x518 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2e4/0x46c fs/namei.c:5410 filename_mkdirat+0x228/0x3f4 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat fs/namei.c:5461 [inline] __arm64_sys_mkdirat+0x9c/0xc0 fs/namei.c:5461 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590