====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.210/4989 is trying to acquire lock: ffff88806088a918 (kn->active#407){++++}-{0:0}, at: kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566 but task is already holding lock: ffffffff8cf51008 (serio_mutex){+.+.}-{3:3}, at: serio_unregister_port+0x2b/0x150 drivers/input/serio/serio.c:707 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (serio_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765 drvctl_store+0x2a/0xae0 drivers/input/serio/serio.c:388 kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2179 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x748/0xd70 fs/read_write.c:594 ksys_write+0x153/0x260 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #0 (kn->active#407){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 kernfs_drain fs/kernfs/dir.c:478 [inline] __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372 kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566 kernfs_remove_by_name include/linux/kernfs.h:598 [inline] remove_files fs/sysfs/group.c:28 [inline] sysfs_remove_group+0xfd/0x290 fs/sysfs/group.c:289 sysfs_remove_groups+0x50/0xa0 fs/sysfs/group.c:313 device_remove_groups drivers/base/core.c:2498 [inline] device_remove_attrs+0xc2/0x140 drivers/base/core.c:2698 device_del+0x637/0xa80 drivers/base/core.c:3614 serio_destroy_port+0x34a/0x470 drivers/input/serio/serio.c:573 serio_unregister_port+0x12c/0x150 drivers/input/serio/serio.c:709 userio_char_release+0x7f/0xb0 drivers/input/serio/userio.c:111 __fput+0x212/0x8c0 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2909 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(serio_mutex); lock(kn->active#407); lock(serio_mutex); lock(kn->active#407); *** DEADLOCK *** 1 lock held by syz.4.210/4989: #0: ffffffff8cf51008 (serio_mutex){+.+.}-{3:3}, at: serio_unregister_port+0x2b/0x150 drivers/input/serio/serio.c:707 stack backtrace: CPU: 1 PID: 4989 Comm: syz.4.210 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 kernfs_drain fs/kernfs/dir.c:478 [inline] __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372 kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566 kernfs_remove_by_name include/linux/kernfs.h:598 [inline] remove_files fs/sysfs/group.c:28 [inline] sysfs_remove_group+0xfd/0x290 fs/sysfs/group.c:289 sysfs_remove_groups+0x50/0xa0 fs/sysfs/group.c:313 device_remove_groups drivers/base/core.c:2498 [inline] device_remove_attrs+0xc2/0x140 drivers/base/core.c:2698 device_del+0x637/0xa80 drivers/base/core.c:3614 serio_destroy_port+0x34a/0x470 drivers/input/serio/serio.c:573 serio_unregister_port+0x12c/0x150 drivers/input/serio/serio.c:709 userio_char_release+0x7f/0xb0 drivers/input/serio/userio.c:111 __fput+0x212/0x8c0 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2909 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f1007cd40d9 Code: Unable to access opcode bytes at RIP 0x7f1007cd40af. RSP: 002b:00007f1005f2c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffed RBX: 00007f1007f5bfa0 RCX: 00007f1007cd40d9 RDX: 0000000000000008 RSI: 00002000000001c0 RDI: 0000000000000007 RBP: 00007f1007d6b024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1007f5c038 R14: 00007f1007f5bfa0 R15: 00007ffc2a3062f8