BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 244s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=4/256 refcnt=5 pending: cache_reap, defense_work_handler, defense_work_handler, defense_work_handler ====================================================== WARNING: possible circular locking dependency detected 4.19.91-syzkaller #0 Not tainted ------------------------------------------------------ swapper/0/0 is trying to acquire lock: 0000000033276fd8 (console_owner){-.-.}, at: log_next kernel/printk/printk.c:499 [inline] 0000000033276fd8 (console_owner){-.-.}, at: console_unlock+0x432/0x10d0 kernel/printk/printk.c:2416 but task is already holding lock: 000000007543a18a (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x1213 kernel/workqueue.c:4582 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&(&pool->lock)->rlock){-.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x23d/0x10a0 kernel/workqueue.c:1417 queue_work_on+0x192/0x200 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] schedule_work include/linux/workqueue.h:570 [inline] put_pwq kernel/workqueue.c:1090 [inline] put_pwq+0x171/0x1c0 kernel/workqueue.c:1075 put_pwq_unlocked.part.0+0x34/0x70 kernel/workqueue.c:1107 put_pwq_unlocked kernel/workqueue.c:1101 [inline] destroy_workqueue+0x611/0x700 kernel/workqueue.c:4241 do_floppy_init drivers/block/floppy.c:4734 [inline] floppy_async_init+0x2026/0x2165 drivers/block/floppy.c:4751 async_run_entry_fn+0x124/0x570 kernel/async.c:127 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 -> #3 (&pool->lock/1){..-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x23d/0x10a0 kernel/workqueue.c:1417 queue_work_on+0x192/0x200 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] tty_schedule_flip drivers/tty/tty_buffer.c:408 [inline] tty_flip_buffer_push+0xc5/0x100 drivers/tty/tty_buffer.c:551 pty_write+0x1a6/0x200 drivers/tty/pty.c:125 n_tty_write+0xafa/0x1140 drivers/tty/n_tty.c:2354 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x458/0x7a0 drivers/tty/tty_io.c:1044 __vfs_write+0x114/0x810 fs/read_write.c:485 vfs_write+0x20c/0x560 fs/read_write.c:549 ksys_write+0x14f/0x2d0 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:608 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&(&port->lock)->rlock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 tty_port_tty_get+0x22/0x90 drivers/tty/tty_port.c:288 tty_port_default_wakeup+0x16/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x57/0x70 drivers/tty/tty_port.c:390 uart_write_wakeup+0x46/0x70 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x495/0xaf0 drivers/tty/serial/8250/8250_port.c:1806 serial8250_handle_irq.part.0+0x261/0x2b0 drivers/tty/serial/8250/8250_port.c:1879 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1865 [inline] serial8250_default_handle_irq+0xc0/0x150 drivers/tty/serial/8250/8250_port.c:1895 serial8250_interrupt+0xfc/0x1e0 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x144/0x8f0 kernel/irq/handle.c:149 handle_irq_event_percpu+0x74/0x160 kernel/irq/handle.c:189 handle_irq_event+0xa7/0x134 kernel/irq/handle.c:206 handle_edge_irq+0x25e/0x8d0 kernel/irq/chip.c:797 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline] handle_irq+0x39/0x50 arch/x86/kernel/irq_64.c:87 do_IRQ+0x99/0x1d0 arch/x86/kernel/irq.c:246 ret_from_intr+0x0/0x1e native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:556 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x30c/0x4d0 kernel/sched/idle.c:263 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:369 start_secondary+0x3e8/0x5b0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 serial8250_console_write+0x7ca/0x9f0 drivers/tty/serial/8250/8250_port.c:3247 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590 call_console_drivers kernel/printk/printk.c:1736 [inline] console_unlock+0xbdf/0x10d0 kernel/printk/printk.c:2429 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1937 vprintk_default+0x28/0x30 kernel/printk/printk.c:1979 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2012 register_console+0x77f/0xb90 kernel/printk/printk.c:2745 univ8250_console_init+0x3e/0x4b drivers/tty/serial/8250/8250_core.c:685 console_init+0x4f7/0x761 kernel/printk/printk.c:2831 start_kernel+0x59c/0x8c5 init/main.c:660 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 console_lock_spinning_enable kernel/printk/printk.c:1599 [inline] console_unlock+0x49c/0x10d0 kernel/printk/printk.c:2426 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1937 vprintk_default+0x28/0x30 kernel/printk/printk.c:1979 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2012 show_pwq kernel/workqueue.c:4488 [inline] show_workqueue_state.cold+0xa05/0x1213 kernel/workqueue.c:4584 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5596 call_timer_fn+0x18d/0x720 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers kernel/time/timer.c:1684 [inline] __run_timers kernel/time/timer.c:1652 [inline] run_timer_softirq+0xd00/0x16a0 kernel/time/timer.c:1699 __do_softirq+0x25c/0x921 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:556 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x30c/0x4d0 kernel/sched/idle.c:263 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:369 rest_init+0x219/0x222 init/main.c:441 start_kernel+0x88c/0x8c5 init/main.c:737 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 other info that might help us debug this: Chain exists of: console_owner --> &pool->lock/1 --> &(&pool->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&pool->lock)->rlock); lock(&pool->lock/1); lock(&(&pool->lock)->rlock); lock(console_owner); *** DEADLOCK *** 4 locks held by swapper/0/0: #0: 00000000abae4592 ((&wq_watchdog_timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:168 [inline] #0: 00000000abae4592 ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0xda/0x720 kernel/time/timer.c:1316 #1: 00000000fc04e669 (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x120 kernel/workqueue.c:4453 #2: 000000007543a18a (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x1213 kernel/workqueue.c:4582 #3: 0000000046021c34 (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1661 [inline] #3: 0000000046021c34 (console_lock){+.+.}, at: vprintk_emit+0x267/0x6d0 kernel/printk/printk.c:1936 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.91-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x2e19/0x49c0 kernel/locking/lockdep.c:3411 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 console_lock_spinning_enable kernel/printk/printk.c:1599 [inline] console_unlock+0x49c/0x10d0 kernel/printk/printk.c:2426 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1937 vprintk_default+0x28/0x30 kernel/printk/printk.c:1979 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2012 show_pwq kernel/workqueue.c:4488 [inline] show_workqueue_state.cold+0xa05/0x1213 kernel/workqueue.c:4584 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5596 call_timer_fn+0x18d/0x720 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers kernel/time/timer.c:1684 [inline] __run_timers kernel/time/timer.c:1652 [inline] run_timer_softirq+0xd00/0x16a0 kernel/time/timer.c:1699 __do_softirq+0x25c/0x921 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893 RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61 Code: ff ff 48 89 df e8 92 b5 56 fa eb 82 e9 07 00 00 00 0f 00 2d a4 c3 5b 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 94 c3 5b 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 8e 93 0d fa e8 09 RSP: 0018:ffffffff88e07cb0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff11e4b7c RBX: ffffffff88e79ec0 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffff88e7a73c RBP: ffffffff88e07ce0 R08: ffffffff88e79ec0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff88f25bd0 R14: 0000000000000000 R15: ffffffff88e79ec0 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:556 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x30c/0x4d0 kernel/sched/idle.c:263 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:369 rest_init+0x219/0x222 init/main.c:441 start_kernel+0x88c/0x8c5 init/main.c:737 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 workqueue events_power_efficient: flags=0x80 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=2/256 refcnt=3 pending: gc_worker, neigh_periodic_work workqueue mm_percpu_wq: flags=0x8 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: vmstat_update workqueue krxrpcd: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 refcnt=2 pending: rxrpc_peer_keepalive_worker