keytouch 0003:0926:3333.0029: input,hidraw0: USB HID v0.00 Keyboard [HID 0926:3333] on usb-dummy_hcd.9-1/input0 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kworker/0:3/2232 is trying to acquire lock: ffff88813fe2a0b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x74/0x2b0 drivers/tty/tty_buffer.c:236 but task is already holding lock: ffffffff8ef4eb20 (console_lock){+.+.}-{0:0}, at: class_console_lock_constructor include/linux/console.h:734 [inline] ffffffff8ef4eb20 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x28/0x220 drivers/tty/vt/vt_ioctl.c:989 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (console_lock){+.+.}-{0:0}: console_lock+0x71/0x90 kernel/printk/printk.c:2896 class_console_lock_constructor include/linux/console.h:734 [inline] con_flush_chars+0x74/0x90 drivers/tty/vt/vt.c:3730 __receive_buf drivers/tty/n_tty.c:1620 [inline] n_tty_receive_buf_common+0xd2a/0x13d0 drivers/tty/n_tty.c:1715 tiocsti+0x218/0x2a0 drivers/tty/tty_io.c:2263 tty_ioctl+0x626/0xdd0 drivers/tty/tty_io.c:2679 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&tty->termios_rwsem){++++}-{4:4}: down_write+0x91/0x200 kernel/locking/rwsem.c:1631 tty_unthrottle+0x23/0x110 drivers/tty/tty_ioctl.c:103 tiocsti+0x218/0x2a0 drivers/tty/tty_io.c:2263 tty_ioctl+0x626/0xdd0 drivers/tty/tty_io.c:2679 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&buf->lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 tty_buffer_flush+0x74/0x2b0 drivers/tty/tty_buffer.c:236 tty_ldisc_flush+0x6b/0xc0 drivers/tty/tty_ldisc.c:388 __do_SAK+0x25e/0x680 drivers/tty/tty_io.c:2998 vc_SAK+0x78/0x220 drivers/tty/vt/vt_ioctl.c:998 process_one_work kernel/workqueue.c:3399 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3482 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3563 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: &buf->lock --> &tty->termios_rwsem --> console_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(console_lock); lock(&tty->termios_rwsem); lock(console_lock); lock(&buf->lock); *** DEADLOCK *** locks held by kworker/0:3/2232: 4, last CPU#0: #0: ffff88813ff43140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813ff43140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813ff43140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3364 [inline] #0: ffff88813ff43140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3482 #1: ffffc9000751fc40 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9000751fc40 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9000751fc40 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3364 [inline] #1: ffffc9000751fc40 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3482 #2: ffffffff8ef4eb20 (console_lock){+.+.}-{0:0}, at: class_console_lock_constructor include/linux/console.h:734 [inline] #2: ffffffff8ef4eb20 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x28/0x220 drivers/tty/vt/vt_ioctl.c:989 #3: ffff8880227440a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline] #3: ffff8880227440a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x20/0xc0 drivers/tty/tty_ldisc.c:386 stack backtrace: CPU: 0 UID: 0 PID: 2232 Comm: kworker/0:3 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/08/2026 Workqueue: events vc_SAK Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 tty_buffer_flush+0x74/0x2b0 drivers/tty/tty_buffer.c:236 tty_ldisc_flush+0x6b/0xc0 drivers/tty/tty_ldisc.c:388 __do_SAK+0x25e/0x680 drivers/tty/tty_io.c:2998 vc_SAK+0x78/0x220 drivers/tty/vt/vt_ioctl.c:998 process_one_work kernel/workqueue.c:3399 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3482 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3563 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 tty tty1: SAK: killed process 12799 (syz.5.1913): by fd#5 tty tty1: SAK: killed process 12799 (syz.5.1913): by fd#5