====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.152/4883 is trying to acquire lock: ffff888019fd9918 (kn->active#610){++++}-{0:0}, at: kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566 but task is already holding lock: ffffffff8cf511e8 (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#610){++++}-{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 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 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#610); lock(serio_mutex); lock(kn->active#610); *** DEADLOCK *** 1 lock held by syz.0.152/4883: #0: ffffffff8cf511e8 (serio_mutex){+.+.}-{3:3}, at: serio_unregister_port+0x2b/0x150 drivers/input/serio/serio.c:707 stack backtrace: CPU: 0 PID: 4883 Comm: syz.0.152 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 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 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: 0033:0x7f5fcaf7f0d9 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:00007ffd14f8f718 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f5fcb208da0 RCX: 00007f5fcaf7f0d9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f5fcb208da0 R08: 0000000000000006 R09: 0000000000000000 R10: 00007f5fcb208cb0 R11: 0000000000000246 R12: 0000000000020648 R13: 00007f5fcb206fac R14: 000000000002060c R15: 00007f5fcb206fa0