====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.91/6209 is trying to acquire lock: ffff888062b24d10 (&opts->dep_lock){+.+.}-{4:4}, at: tcm_register_callback+0x20/0x70 drivers/usb/gadget/function/f_tcm.c:2625 but task is already holding lock: ffff88802a5c6c68 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] ffff88802a5c6c68 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x23b/0x430 fs/configfs/file.c:229 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&p->frag_sem){++++}-{4:4}: down_write_killable+0x4a/0x80 kernel/locking/rwsem.c:1643 configfs_rmdir+0x3b0/0x950 fs/configfs/dir.c:1534 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5381 filename_rmdir+0x292/0x520 fs/namei.c:5438 __do_sys_unlinkat fs/namei.c:5613 [inline] __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5606 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 (&sb->s_type->i_mutex_key#24){++++}-{4:4}: down_write+0x3a/0x50 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+0x402/0x620 fs/namei.c:5276 filename_mkdirat+0x289/0x520 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5327 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 (&opts->dep_lock){+.+.}-{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+0x1520/0x2ce0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578 tcm_register_callback+0x20/0x70 drivers/usb/gadget/function/f_tcm.c:2625 usbg_attach drivers/usb/gadget/function/f_tcm.c:2649 [inline] usbg_enable_tpg+0x73/0x120 drivers/usb/gadget/function/f_tcm.c:1825 target_tpg_enable+0x2e5/0x590 drivers/target/target_core_tpg.c:481 target_fabric_tpg_base_enable_store+0x122/0x1c0 drivers/target/target_core_fabric_configfs.c:840 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61e/0xbb0 fs/read_write.c:687 ksys_write+0x156/0x270 fs/read_write.c:739 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: &opts->dep_lock --> &sb->s_type->i_mutex_key#24 --> &p->frag_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&p->frag_sem); lock(&sb->s_type->i_mutex_key#24); lock(&p->frag_sem); lock(&opts->dep_lock); *** DEADLOCK *** 4 locks held by syz.0.91/6209: #0: ffff888033538d28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259 #1: ffff88801cff8500 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline] #1: ffff88801cff8500 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683 #2: ffff8880335fc878 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x81/0x430 fs/configfs/file.c:226 #3: ffff88802a5c6c68 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] #3: ffff88802a5c6c68 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x23b/0x430 fs/configfs/file.c:229 stack backtrace: CPU: 0 UID: 0 PID: 6209 Comm: syz.0.91 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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+0x1520/0x2ce0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578 tcm_register_callback+0x20/0x70 drivers/usb/gadget/function/f_tcm.c:2625 usbg_attach drivers/usb/gadget/function/f_tcm.c:2649 [inline] usbg_enable_tpg+0x73/0x120 drivers/usb/gadget/function/f_tcm.c:1825 target_tpg_enable+0x2e5/0x590 drivers/target/target_core_tpg.c:481 target_fabric_tpg_base_enable_store+0x122/0x1c0 drivers/target/target_core_fabric_configfs.c:840 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61e/0xbb0 fs/read_write.c:687 ksys_write+0x156/0x270 fs/read_write.c:739 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: 0033:0x7fc7406be0d9 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:00007fc73e8f5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fc740946090 RCX: 00007fc7406be0d9 RDX: 0000000000000002 RSI: 00002000000006c0 RDI: 0000000000000003 RBP: 00007fc740755024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc740946128 R14: 00007fc740946090 R15: 00007ffe5c21fcc8