workqueue: work func io_tctx_fallback_work enqueued on deprecated workqueue. Use system_{percpu|dfl}_wq instead. ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.54/6108 is trying to acquire lock: ffffffff8e6f2020 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x61/0x80 kernel/printk/printk.c:1902 but task is already holding lock: ffff88807d14f4f8 (&tty->write_wait){-.-.}-{3:3}, at: __wake_up_common_lock kernel/sched/wait.c:124 [inline] ffff88807d14f4f8 (&tty->write_wait){-.-.}-{3:3}, at: __wake_up+0x1c/0x60 kernel/sched/wait.c:146 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&tty->write_wait){-.-.}-{3:3}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 __wake_up_common_lock kernel/sched/wait.c:124 [inline] __wake_up+0x1c/0x60 kernel/sched/wait.c:146 tty_port_default_wakeup+0x47/0x60 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1723 serial8250_handle_irq_locked+0x770/0x9a0 drivers/tty/serial/8250/8250_port.c:1837 serial8250_handle_irq.part.0+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1853 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1849 [inline] serial8250_default_handle_irq+0xc2/0x280 drivers/tty/serial/8250/8250_port.c:1867 serial8250_interrupt+0xf8/0x1b0 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x232/0x880 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263 handle_edge_irq+0x34c/0x950 kernel/irq/chip.c:859 generic_handle_irq_desc include/linux/irqdesc.h:188 [inline] handle_irq arch/x86/kernel/irq.c:209 [inline] call_irq_handler arch/x86/kernel/irq.c:265 [inline] __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:280 common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:273 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665 finish_task_switch.isra.0+0x2cd/0x1010 kernel/sched/core.c:5361 context_switch kernel/sched/core.c:5507 [inline] __schedule+0x1264/0x6730 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7322 worker_thread+0x53b/0xe50 kernel/workqueue.c:3501 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (&port_lock_key){-.-.}-{3:3}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166 uart_port_lock_irqsave include/linux/serial_core.h:719 [inline] serial8250_console_write+0x177/0x1a50 drivers/tty/serial/8250/8250_port.c:3338 console_emit_next_record kernel/printk/printk.c:3183 [inline] console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 _printk+0xcf/0x110 kernel/printk/printk.c:2504 register_console.cold+0xc0/0x248 kernel/printk/printk.c:4208 univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515 console_init+0x3d5/0x5b0 kernel/printk/printk.c:4407 start_kernel+0x314/0x490 init/main.c:1112 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x158 -> #0 (console_owner){....}-{0:0}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1902 console_emit_next_record kernel/printk/printk.c:3177 [inline] console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 _printk+0xcf/0x110 kernel/printk/printk.c:2504 __queue_work.cold+0x3b/0x8f kernel/workqueue.c:2287 queue_work_on+0x1a9/0x1e0 kernel/workqueue.c:2452 queue_work include/linux/workqueue.h:699 [inline] io_fallback_tw io_uring/tw.c:58 [inline] io_req_normal_work_add+0x2a2/0x510 io_uring/tw.c:233 __io_req_task_work_add io_uring/tw.h:45 [inline] __io_poll_execute+0x1c2/0x3b0 io_uring/poll.c:222 io_poll_wake+0x3e6/0x540 io_uring/poll.c:433 __wake_up_common+0x135/0x1f0 kernel/sched/wait.c:108 __wake_up_common_lock kernel/sched/wait.c:125 [inline] __wake_up+0x31/0x60 kernel/sched/wait.c:146 tty_write_unlock drivers/tty/tty_io.c:934 [inline] iterate_tty_write drivers/tty/tty_io.c:1031 [inline] file_tty_write.isra.0+0x5dd/0x890 drivers/tty/tty_io.c:1081 io_write+0x6b2/0x1670 io_uring/rw.c:1174 __io_issue_sqe+0xe8/0x7a0 io_uring/io_uring.c:1395 io_issue_sqe+0x88/0x1540 io_uring/io_uring.c:1418 io_queue_sqe io_uring/io_uring.c:1649 [inline] io_submit_sqe io_uring/io_uring.c:1934 [inline] io_submit_sqes+0xb17/0x2480 io_uring/io_uring.c:2057 __do_sys_io_uring_enter+0xa88/0x1b10 io_uring/io_uring.c:2646 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 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: console_owner --> &port_lock_key --> &tty->write_wait Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&tty->write_wait); lock(&port_lock_key); lock(&tty->write_wait); lock(console_owner); *** DEADLOCK *** 5 locks held by syz.1.54/6108: #0: ffff88807a80e0a0 (&ctx->uring_lock){+.+.}-{4:4}, at: __do_sys_io_uring_enter+0xa7e/0x1b10 io_uring/io_uring.c:2645 #1: ffff88807d14f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #2: ffff88807d14f4f8 (&tty->write_wait){-.-.}-{3:3}, at: __wake_up_common_lock kernel/sched/wait.c:124 [inline] #2: ffff88807d14f4f8 (&tty->write_wait){-.-.}-{3:3}, at: __wake_up+0x1c/0x60 kernel/sched/wait.c:146 #3: ffffffff8e7d2460 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x110 kernel/printk/printk.c:2504 #4: ffffffff8e7d24d8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline] #4: ffffffff8e7d24d8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline] #4: ffffffff8e7d24d8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline] #4: ffffffff8e7d24d8 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfd/0xe50 kernel/printk/printk.c:3246 stack backtrace: CPU: 1 UID: 0 PID: 6108 Comm: syz.1.54 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 console_lock_spinning_enable+0x72/0x80 kernel/printk/printk.c:1902 console_emit_next_record kernel/printk/printk.c:3177 [inline] console_flush_one_record+0x739/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 _printk+0xcf/0x110 kernel/printk/printk.c:2504 __queue_work.cold+0x3b/0x8f kernel/workqueue.c:2287 queue_work_on+0x1a9/0x1e0 kernel/workqueue.c:2452 queue_work include/linux/workqueue.h:699 [inline] io_fallback_tw io_uring/tw.c:58 [inline] io_req_normal_work_add+0x2a2/0x510 io_uring/tw.c:233 __io_req_task_work_add io_uring/tw.h:45 [inline] __io_poll_execute+0x1c2/0x3b0 io_uring/poll.c:222 io_poll_wake+0x3e6/0x540 io_uring/poll.c:433 __wake_up_common+0x135/0x1f0 kernel/sched/wait.c:108 __wake_up_common_lock kernel/sched/wait.c:125 [inline] __wake_up+0x31/0x60 kernel/sched/wait.c:146 tty_write_unlock drivers/tty/tty_io.c:934 [inline] iterate_tty_write drivers/tty/tty_io.c:1031 [inline] file_tty_write.isra.0+0x5dd/0x890 drivers/tty/tty_io.c:1081 io_write+0x6b2/0x1670 io_uring/rw.c:1174 __io_issue_sqe+0xe8/0x7a0 io_uring/io_uring.c:1395 io_issue_sqe+0x88/0x1540 io_uring/io_uring.c:1418 io_queue_sqe io_uring/io_uring.c:1649 [inline] io_submit_sqe io_uring/io_uring.c:1934 [inline] io_submit_sqes+0xb17/0x2480 io_uring/io_uring.c:2057 __do_sys_io_uring_enter+0xa88/0x1b10 io_uring/io_uring.c:2646 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe2ba79ce59 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:00007fe2b9dfdf38 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 0000200000000340 RCX: 00007fe2ba79ce59 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000009 RBP: 0000000000000440 R08: 0000000000000000 R09: 0000000000000008 R10: 0000000000000000 R11: 0000000000000246 R12: 00002000000008a0 R13: 00002000000008a8 R14: 0000000000000e26 R15: 0000000000000001